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Mitochondrial connexin43 and mitochondrial K ATP channels modulate triggered arrhythmias in mouse ventricular muscle. Pflugers Arch 2023; 475:477-488. [PMID: 36707457 DOI: 10.1007/s00424-023-02789-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 12/21/2022] [Accepted: 01/18/2023] [Indexed: 01/29/2023]
Abstract
Connexin43 (Cx43) exits as hemichannels in the inner mitochondrial membrane. We examined how mitochondrial Cx43 and mitochondrial KATP channels affect the occurrence of triggered arrhythmias. To generate cardiac-specific Cx43-deficient (cCx43-/-) mice, Cx43flox/flox mice were crossed with α-MHC (Myh6)-cre+/- mice. The resulting offspring, Cx43flox/flox/Myh6-cre+/- mice (cCx43-/- mice) and their littermates (cCx43+/+ mice), were used. Trabeculae were dissected from the right ventricles of mouse hearts. Cardiomyocytes were enzymatically isolated from the ventricles of mouse hearts. Force was measured with a strain gauge in trabeculae (22°C). To assess arrhythmia susceptibility, the minimal extracellular Ca2+ concentration ([Ca2+]o,min), at which arrhythmias were induced by electrical stimulation, was determined in trabeculae. ROS production was estimated with 2',7'-dichlorofluorescein (DCF), mitochondrial membrane potential with tetramethylrhodamine methyl ester (TMRM), and Ca2+ spark frequency with fluo-4 and confocal microscopy in cardiomyocytes. ROS production within the mitochondria was estimated with MitoSoxRed and mitochondrial Ca2+ with rhod-2 in trabeculae. Diazoxide was used to activate mitochondrial KATP. Most of cCx43-/- mice died suddenly within 8 weeks. Cx43 was present in the inner mitochondrial membrane in cCx43+/+ mice but not in cCx43-/- mice. In cCx43-/- mice, the [Ca2+]o,min was lower, and Ca2+ spark frequency, the slope of DCF fluorescence intensity, MitoSoxRed fluorescence, and rhod-2 fluorescence were higher. TMRM fluorescence was more decreased in cCx43-/- mice. Most of these changes were suppressed by diazoxide. In addition, in cCx43-/- mice, antioxidant peptide SS-31 and N-acetyl-L-cysteine increased the [Ca2+]o,min. These results suggest that Cx43 deficiency activates Ca2+ leak from the SR, probably due to depolarization of mitochondrial membrane potential, an increase in mitochondrial Ca2+, and an increase in ROS production, thereby causing triggered arrhythmias, and that Cx43 hemichannel deficiency may be compensated by activation of mitochondrial KATP channels in mouse hearts.
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Activation of Cx43 Hemichannels Induces the Generation of Ca 2+ Oscillations in White Adipocytes and Stimulates Lipolysis. Int J Mol Sci 2021; 22:ijms22158095. [PMID: 34360859 PMCID: PMC8347185 DOI: 10.3390/ijms22158095] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/22/2021] [Accepted: 07/26/2021] [Indexed: 12/11/2022] Open
Abstract
The aim of the study was to investigate the mechanisms of Ca2+ oscillation generation upon activation of connexin-43 and regulation of the lipolysis/lipogenesis balance in white adipocytes through vesicular ATP release. With fluorescence microscopy it was revealed that a decrease in the concentration of extracellular calcium ([Ca2+]ex) results in two types of Ca2+ responses in white adipocytes: Ca2+ oscillations and transient Ca2+ signals. It was found that activation of the connexin half-channels is involved in the generation of Ca2+ oscillations, since the blockers of the connexin hemichannels-carbenoxolone, octanol, proadifen and Gap26-as well as Cx43 gene knockdown led to complete suppression of these signals. The activation of Cx43 in response to the reduction of [Ca2+]ex was confirmed by TIRF microscopy. It was shown that in response to the activation of Cx43, ATP-containing vesicles were released from the adipocytes. This process was suppressed by knockdown of the Cx43 gene and by bafilomycin A1, an inhibitor of vacuolar ATPase. At the level of intracellular signaling, the generation of Ca2+ oscillations in white adipocytes in response to a decrease in [Ca2+]ex occurred due to the mobilization of the Ca2+ ions from the thapsigargin-sensitive Ca2+ pool of IP3R as a result of activation of the purinergic P2Y1 receptors and phosphoinositide signaling pathway. After activation of Cx43 and generation of the Ca2+ oscillations, changes in the expression levels of key genes and their encoding proteins involved in the regulation of lipolysis were observed in white adipocytes. This effect was accompanied by a decrease in the number of adipocytes containing lipid droplets, while inhibition or knockdown of Cx43 led to inhibition of lipolysis and accumulation of lipid droplets. In this study, we investigated the mechanism of Ca2+ oscillation generation in white adipocytes in response to a decrease in the concentration of Ca2+ ions in the external environment and established an interplay between periodic Ca2+ modes and the regulation of the lipolysis/lipogenesis balance.
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Yuan D, Li X, Luo C, Li X, Cheng N, Ji H, Qiu R, Luo G, Chen C, Hei Z. Inhibition of gap junction composed of Cx43 prevents against acute kidney injury following liver transplantation. Cell Death Dis 2019; 10:767. [PMID: 31601792 PMCID: PMC6787008 DOI: 10.1038/s41419-019-1998-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 08/12/2019] [Accepted: 09/23/2019] [Indexed: 12/19/2022]
Abstract
Postoperative acute kidney injury (AKI) is a severe complication after liver transplantation (LT). Its deterioration and magnification lead to the increase in mortality. Connexin43 (Cx43) mediates direct transmission of intracellular signals between neighboring cells, always considered to be the potent biological basis of organ damage deterioration and magnification. Thus, we explored the effects of Cx43 on AKI following LT and its related possible mechanism. In this study, alternations of Cx43 expression were observed in 82 patients, receiving the first-time orthotopic LT. We built autologous orthotopic liver transplantation (AOLT) models with Sprague–Dawley (SD) rats in vivo, and hypoxia-reoxygenation (H/R) or lipopolysaccharide (LPS) pretreatment models with kidney tubular epithelial cells (NRK-52E) in vitro, both of which were the most important independent risk factors of AKI following LT. Then, different methods were used to alter the function of Cx43 channels to determine its protective effects on AKI. The results indicated that patients with AKI suffering from longer time of tracheal intubation or intensive care unit stay, importantly, had significantly lower survival rate at postoperative 30 days and 3 years. In rat AOLT models, as Cx43 was inhibited with heptanol, postoperative AKI was attenuated significantly. In vitro experiments, downregulation of Cx43 with selective inhibitors, or siRNA protected against post-hypoxic NRK-52E cell injuries caused by H/R and/or LPS, while upregulation of Cx43 exacerbated the above-mentioned cell injuries. Of note, alternation of Cx43 function regulated the content of reactive oxygen species (ROS), which not only mediated oxidative stress and inflammation reactions effectively, but also regulated necroptosis. Therefore, we concluded that Cx43 inhibition protected against AKI following LT through attenuating ROS transmission between the neighboring cells. ROS alternation depressed oxidative stress and inflammation reaction, which ultimately reduced necroptosis. This might offer new insights for targeted intervention for organ protection in LT, or even in other major surgeries.
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Affiliation(s)
- Dongdong Yuan
- Department of Anesthesiology, the third affiliated Hospital of Sun Yat-sen University, Tianhe Road, Guangzhou, PR China.
| | - Xiaoyun Li
- Department of Anesthesiology, the third affiliated Hospital of Sun Yat-sen University, Tianhe Road, Guangzhou, PR China
| | - Chenfang Luo
- Department of Anesthesiology, the third affiliated Hospital of Sun Yat-sen University, Tianhe Road, Guangzhou, PR China
| | - Xianlong Li
- Department of Anesthesiology, the third affiliated Hospital of Sun Yat-sen University, Tianhe Road, Guangzhou, PR China
| | - Nan Cheng
- Department of Anesthesiology, the third affiliated Hospital of Sun Yat-sen University, Tianhe Road, Guangzhou, PR China
| | - Haocong Ji
- Department of Anesthesiology, Huizhou first People's Hospital, No. 20, San Xin Nan Road, Jiangbei, Huizhou, PR China
| | - Rongzong Qiu
- Department of Anesthesiology, Huizhou first People's Hospital, No. 20, San Xin Nan Road, Jiangbei, Huizhou, PR China
| | - Gangjian Luo
- Department of Anesthesiology, the third affiliated Hospital of Sun Yat-sen University, Tianhe Road, Guangzhou, PR China
| | - Chaojin Chen
- Department of Anesthesiology, the third affiliated Hospital of Sun Yat-sen University, Tianhe Road, Guangzhou, PR China.
| | - Ziqing Hei
- Department of Anesthesiology, the third affiliated Hospital of Sun Yat-sen University, Tianhe Road, Guangzhou, PR China.
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Abstract
Major depressive disorder (MDD) is a chronic and debilitating illness that affects over 350 million people worldwide; however, current treatments have failed to cure or prevent the progress of depression. Increasing evidence suggests a crucial role for connexins in MDD. In this review, we have summarised recent accomplishments regarding the role of connexins, gap junctions, and hemichannels in the aetiology of MDD, and discussed the limitations of current research. A blockage of gap junctions or hemichannels induces depressive behaviour. Possible underlying mechanisms include the regulation of neurosecretory functions and synaptic activity by gap junctions and hemichannels. Gap junctions are functionally inhibited under stress conditions. Conversely, hemichannel permeability is increased. Antidepressants inhibit hemichannel permeability; however, they have contrasting effects on the function of gap junctions under normal conditions and can protect them against stress. In conclusion, the blockage of hemichannels concurrent with improvements in gap junction functionality might be potential targets for depression treatment.
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Affiliation(s)
- Cong-Yuan Xia
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Zhen-Zhen Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China
| | - Tohru Yamakuni
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai 980-8578, Japan
| | - Nai-Hong Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China; College of Pharmacy, Hunan University of Chinese Medicine, Changsha, Hunan 410208, China.
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Mao Y, Nguyen T, Tonkin RS, Lees JG, Warren C, O'Carroll SJ, Nicholson LFB, Green CR, Moalem-Taylor G, Gorrie CA. Characterisation of Peptide5 systemic administration for treating traumatic spinal cord injured rats. Exp Brain Res 2017; 235:3033-3048. [PMID: 28725925 DOI: 10.1007/s00221-017-5023-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/03/2017] [Indexed: 11/27/2022]
Abstract
Systemic administration of a Connexin43 mimetic peptide, Peptide5, has been shown to reduce secondary tissue damage and improve functional recovery after spinal cord injury (SCI). This study investigated safety measures and potential off-target effects of Peptide5 systemic administration. Rats were subjected to a mild contusion SCI using the New York University impactor. One cohort was injected intraperitoneally with a single dose of fluorescently labelled Peptide5 and euthanised at 2 or 4 h post-injury for peptide distribution analysis. A second cohort received intraperitoneal injections of Peptide5 or a scrambled peptide and was culled at 8 or 24 h post-injury for the analysis of connexin proteins and systemic cytokine profile. We found that Peptide5 did not cross the blood-spinal cord barrier in control animals, but reached the lesion area in the spinal cord-injured animals without entering non-injured tissue. There was no evidence that the systemic administration of Peptide5 modulates Connexin43 protein expression or hemichannel closure in the heart and lung tissue of SCI animals. The expression levels of other major connexin proteins including Connexin30 in astrocytes, Connexin36 in neurons and Connexin47 in oligodendrocytes were also unaltered by systemic delivery of Peptide5 in either the injured or non-injured spinal cords. In addition, systemic delivery of Peptide5 had no significant effect on the plasma levels of cytokines, chemokines or growth factors. These data indicate that the systemic delivery of Peptide5 is unlikely to cause any off-target or adverse effects and may thus be a safe treatment option for traumatic SCI.
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Affiliation(s)
- Yilin Mao
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW, 2007, Australia
| | - Tara Nguyen
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW, 2007, Australia
| | - Ryan S Tonkin
- Neuropathic Pain Research Group, Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Justin G Lees
- Neuropathic Pain Research Group, Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Caitlyn Warren
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW, 2007, Australia
| | - Simon J O'Carroll
- Department of Anatomy and Medical Imaging and The Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Louise F B Nicholson
- Department of Anatomy and Medical Imaging and The Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Colin R Green
- Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Gila Moalem-Taylor
- Neuropathic Pain Research Group, Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Catherine A Gorrie
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW, 2007, Australia.
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Roy S, Jiang JX, Li AF, Kim D. Connexin channel and its role in diabetic retinopathy. Prog Retin Eye Res 2017; 61:35-59. [PMID: 28602949 DOI: 10.1016/j.preteyeres.2017.06.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Revised: 05/30/2017] [Accepted: 06/02/2017] [Indexed: 12/18/2022]
Abstract
Diabetic retinopathy is the leading cause of blindness in the working age population. Unfortunately, there is no cure for this devastating ocular complication. The early stage of diabetic retinopathy is characterized by the loss of various cell types in the retina, namely endothelial cells and pericytes. As the disease progresses, vascular leakage, a clinical hallmark of diabetic retinopathy, becomes evident and may eventually lead to diabetic macular edema, the most common cause of vision loss in diabetic retinopathy. Substantial evidence indicates that the disruption of connexin-mediated cellular communication plays a critical role in the pathogenesis of diabetic retinopathy. Yet, it is unclear how altered communication via connexin channel mediated cell-to-cell and cell-to-extracellular microenvironment is linked to the development of diabetic retinopathy. Recent observations suggest the possibility that connexin hemichannels may play a role in the pathogenesis of diabetic retinopathy by allowing communication between cells and the microenvironment. Interestingly, recent studies suggest that connexin channels may be involved in regulating retinal vascular permeability. These cellular events are coordinated at least in part via connexin-mediated intercellular communication and the maintenance of retinal vascular homeostasis. This review highlights the effect of high glucose and diabetic condition on connexin channels and their impact on the development of diabetic retinopathy.
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Affiliation(s)
- Sayon Roy
- Departments of Medicine and Ophthalmology, Boston University School of Medicine, Boston, MA, United States.
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
| | - An-Fei Li
- Department of Ophthalmology, Taipei Veterans General Hospital and National Yang-Ming University, Taipei, Taiwan
| | - Dongjoon Kim
- Departments of Medicine and Ophthalmology, Boston University School of Medicine, Boston, MA, United States
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7
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Nakase T, Ishikawa T, Miyata H. Protective effects of connexins in atheromatous plaques in patients of carotid artery stenosis. Neuropathology 2017; 37:97-104. [PMID: 27739121 DOI: 10.1111/neup.12345] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Revised: 09/02/2016] [Accepted: 09/02/2016] [Indexed: 11/26/2022]
Abstract
Fragility of atheromatous plaque in the internal carotid artery can be a risk of brain infarction. The activation of macrophages by oxidative stress and the vulnerability of vascular endothelial cells have been reported to participate in the fragility of atheromatous plaque. Therefore, from the view point of prevention of brain infarction, we investigated the pathological factors which may influence the stabilization of atheromatous plaque. Patients undertaking carotid endoarterectomy (CEA) were continuously screened. Then, 21 samples were obtained from the atheromatous plaques of CEA patients. The expression of connexin (Cx) which composes a gap junction, an intercellular communication organ, was immunohistochemicaly observed. The expression of CD36, an oxidized low-density lipoprotein receptor, was assessed as a marker of oxidative stress. As a result, asymptomatic plaques which were assumed the stable plaques expressed Cx43 along with CD36 expression. In contrast, in the symptomatic plaques, the expression of Cx43 was few and there was almost no coexpression with CD36. The distribution of Cx37 expression was not different between asymptomatic and symptomatic plaques. The expressions of CD36, Cx37 and Cx43 showed no relation to the previous treatment with statins. In conclusion, Cx43 might contribute to the stabilization of atheromatous plaque which is affected by oxidative stress.
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Affiliation(s)
- Taizen Nakase
- Department of Stroke Science, Research Institute for Brain and Blood Vessels - Akita, Japan
| | - Tatsuya Ishikawa
- Department of Surgical Neurology, Research Institute for Brain and Blood Vessels - Akita, Japan
| | - Hajime Miyata
- Department of Neuropathology, Research Institute for Brain and Blood Vessels - Akita, Japan
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8
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Hou S, Shen PP, Zhao MM, Liu XP, Xie HY, Deng F, Feng JC. Mechanism of Mitochondrial Connexin43's Protection of the Neurovascular Unit under Acute Cerebral Ischemia-Reperfusion Injury. Int J Mol Sci 2016; 17:ijms17050679. [PMID: 27164087 PMCID: PMC4881505 DOI: 10.3390/ijms17050679] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 04/27/2016] [Accepted: 04/29/2016] [Indexed: 02/08/2023] Open
Abstract
We observed mitochondrial connexin43 (mtCx43) expression under cerebral ischemia-reperfusion (I/R) injury, analyzed its regulation, and explored its protective mechanisms. Wistar rats were divided into groups based on injections received before middle cerebral artery occlusion (MCAO). Cerebral infarction volume was detected by 2,3,5-triphenyltetrazolim chloride staining, and cell apoptosis was observed by transferase dUTP nick end labeling. We used transmission electron microscopy to observe mitochondrial morphology and determined superoxide dismutase (SOD) activity and malondialdehyde (MDA) content. MtCx43, p-mtCx43, protein kinase C (PKC), and p-PKC expression were detected by Western blot. Compared with those in the IR group, cerebral infarction volumes in the carbenoxolone (CBX) and diazoxide (DZX) groups were obviously smaller, and the apoptosis indices were down-regulated. Mitochondrial morphology was damaged after I/R, especially in the IR and 5-hydroxydecanoic acid (5-HD) groups. Similarly, decreased SOD activity and increased MDA were observed after MCAO; CBX, DZX, and phorbol-12-myristate-13-acetate (PMA) reduced mitochondrial functional injury. Expression of mtCx43 and p-mtCx43 and the p-Cx43/Cx43 ratio were significantly lower in the IR group than in the sham group. These abnormalities were ameliorated by CBX, DZX, and PMA. MtCx43 may protect the neurovascular unit from acute cerebral IR injury via PKC activation induced by mitoKATP channel agonists.
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Affiliation(s)
- Shuai Hou
- Department of Neurology and Neuroscience center, the First Hospital of Jilin University, Changchun 130021, China.
| | - Ping-Ping Shen
- Department of Neurology and Neuroscience center, the First Hospital of Jilin University, Changchun 130021, China.
| | - Ming-Ming Zhao
- Department of Neurology and Neuroscience center, the First Hospital of Jilin University, Changchun 130021, China.
| | - Xiu-Ping Liu
- Department of Neurology and Neuroscience center, the First Hospital of Jilin University, Changchun 130021, China.
| | - Hong-Yan Xie
- Department of Neurology and Neuroscience center, the First Hospital of Jilin University, Changchun 130021, China.
| | - Fang Deng
- Department of Neurology and Neuroscience center, the First Hospital of Jilin University, Changchun 130021, China.
| | - Jia-Chun Feng
- Department of Neurology and Neuroscience center, the First Hospital of Jilin University, Changchun 130021, China.
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Wang L, Peng J, Huang H, Wang Q, Yu M, Tao L. Simvastatin protects Sertoli cells against cisplatin cytotoxicity through enhanced gap junction intercellular communication. Oncol Rep 2015; 34:2133-41. [PMID: 26260290 DOI: 10.3892/or.2015.4192] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 07/09/2015] [Indexed: 11/06/2022] Open
Abstract
Cisplatin, an important chemotherapeutic agent against testicular germ cell cancer, induces testicular toxicity on Leydig and Sertoli cells, leading to serious side-effects such as azoospermia and infertility. In a previous study, it was found that simvastatin enhanced the sensitivity of Leydig tumor cells to chemotherapeutic toxicity through the enhancement of gap junction functions. In the present study, the effect of simvastatin on the sensitivity of normal Sertoli cells to cisplatin and the role of gap junctions in such effects was investigated. The results showed that, simvastatin attenuated cisplatin toxicity only when cells exhibited high-density culture where gap junctional formation was possible. When gap junction function was decreased by the gap junction inhibitor or by siRNA targeting connexin 43, the protective effect of simvastatin to cisplatin toxicity was substantially attenuated. Simvastatin also enhanced gap junction functions between Sertoli cells. This effect was mediated by the reduction of PKC-mediated connexin phosphorylation, thereby increasing connexin 43 membrane localization. Thus, simvastatin-induced enhancement of gap junction‑mediated intercellular communication attenuated cisplatin toxicity on Sertoli cells. This result indicated that enhancement of gap junction function by simvastatin may have bilateral beneficial effects on cisplatin‑based chemotherapy, enhancing cisplatin killing on cancer while ameliorating the reproduction toxicity.
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Affiliation(s)
- Lingzhi Wang
- Department of Anaesthesia, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou 510260, P.R. China
| | - Jianxin Peng
- Department of Hepatobiliary Surgery, Guangdong Province Traditional Chinese Medical Hospital, Guangzhou 510120, P.R. China
| | - Huansen Huang
- Department of Anaesthesia, The Second Affiliated Hospital, Guangzhou Medical University, Guangzhou 510260, P.R. China
| | - Qin Wang
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou 510080, P.R. China
| | - Meiling Yu
- Department of Pharmacy, The First Affiliated Hospital, Bengbu Medical College, Bengbu, Anhui 233004, P.R. China
| | - Liang Tao
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou 510080, P.R. China
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He H, Li N, Zhao Z, Han F, Wang X, Zeng Y. Ischemic postconditioning improves the expression of cellular membrane connexin 43 and attenuates the reperfusion injury in rat acute myocardial infarction. Biomed Rep 2015; 3:668-674. [PMID: 26405543 DOI: 10.3892/br.2015.485] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Accepted: 05/21/2015] [Indexed: 11/05/2022] Open
Abstract
To investigate the effects of cellular membrane connexin 43 (Cx43) and the potential details in ischemic postconditioning (IPOC)-induced cardioprotection, ischemia/reperfusion (IR) models were generated in 8-week-old male Sprague-Dawley rats by ligating the left coronary artery anterior descending branch. The serum levels of myocardial creatases, nitric oxide (NO) and malondialdehyde (MDA) levels, infarct size, arrhythmia events, expression and distribution of Cx43, ultrastructure and apoptosis in the myocardium in different treatments with IR, IR + IPOC, IR + diazoxide or IR + IPOC + 5-hydroxydecanoate acid (5-HD) were investigated. Consequently, IPOC decreased infarct size (10.9 vs. 43.3%, P<0.01) and the levels of myocardial creatases, NO and MDA, and improved the expression (16.8 vs. 25.2% and 6.4 vs. 32.8%, after 1- and 3-h reperfusion, respectively; P<0.01) and distribution of Cx43, ultrastructure and apoptosis (19.2 vs. 42.9%, P<0.01) significantly. Diazoxide partly simulated the effects, and 5-HD attenuated but not completely abolished the effects of IPOC. In addition, the phosphorylated Cx43 (p-Cx43) level in the IR + IPOC group was lower than that in the IR + diazoxide group after 1-h reperfusion (26.1 vs. 29.4%, P>0.05); however, it was reversed after 3-h reperfusion and the p-Cx43 level in the IR + IPOC group was significantly higher than that in the IR + diazoxide group (32.8 vs. 18.7%, P<0.01). In conclusion, cell membrane Cx43 is also involved in the process of IPOC-induced cardioprotection and the improvement of membrane Cx43 is more dependent on mitochondrial KATP in the earlier phase of IPOC compared to the late phase of IPOC.
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Affiliation(s)
- Hua He
- Department of Emergency Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, P.R. China
| | - Nan Li
- Department of Cardiology, China-Japan Friendship Hospital, Beijing 100029, P.R. China
| | - Zhihong Zhao
- Department of Cardiology, Pudong New Area District Zhoupu Hospital, Shanghai 201318, P.R. China
| | - Fusheng Han
- Department of Emergency Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, P.R. China
| | - Xifu Wang
- Department of Emergency Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, P.R. China
| | - Yujie Zeng
- Department of Emergency Cardiology, Beijing Anzhen Hospital, Capital Medical University, Beijing 100029, P.R. China
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11
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Chen YS, Green CR, Danesh-Meyer HV, Rupenthal ID. Neuroprotection in the treatment of glaucoma--A focus on connexin43 gap junction channel blockers. Eur J Pharm Biopharm 2015; 95:182-93. [PMID: 25676338 DOI: 10.1016/j.ejpb.2015.01.031] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 12/23/2014] [Accepted: 01/07/2015] [Indexed: 01/01/2023]
Abstract
Glaucoma is a form of optic neuropathy and a common cause of blindness, affecting over 60 million people worldwide with an expected rise to 80 million by 2020. Successful treatment is challenging due to the various causes of glaucoma, undetectable symptoms at an early stage and inefficient delivery of drugs to the back of the eye. Conventional glaucoma treatments focus on the reduction of elevated intraocular pressure (IOP) using topical eye drops. However, their efficacy is limited to patients who suffer from high IOP glaucoma and do not address the underlying susceptibility of retinal ganglion cells (RGC) to degeneration. Glaucoma is known as a neurodegenerative disease which starts with RGC death and eventually results in damage of the optic nerve. Neuroprotective strategies therefore offer a novel treatment option for glaucoma by not only preventing neuronal loss but also disease progression. This review firstly gives an overview of the pathophysiology of glaucoma as well as current treatment options including conventional and novel delivery strategies. It then summarizes the rational for neuroprotection as a novel therapy for glaucomatous neuropathies and reviews current potential neuroprotective strategies to preserve RGC, with a focus on connexin43 (Cx43) gap junction channel blockers.
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Affiliation(s)
- Ying-Shan Chen
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Colin R Green
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Helen V Danesh-Meyer
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Ilva D Rupenthal
- Buchanan Ocular Therapeutics Unit, Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
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Shan H, Wei J, Zhang M, Lin L, Yan R, Zhang R, Zhu YH. Suppression of PKCε-mediated mitochondrial connexin 43 phosphorylation at serine 368 is involved in myocardial mitochondrial dysfunction in a rat model of dilated cardiomyopathy. Mol Med Rep 2015; 11:4720-6. [PMID: 25625661 DOI: 10.3892/mmr.2015.3260] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 01/02/2015] [Indexed: 11/05/2022] Open
Abstract
Mitochondrial connexin 43 (Cx43) is important in cardioprotection by ischemic preconditioning; however, whether mitochondrial Cx43 is involved in mitochondrial dysfunction in the pathogenesis of dilated cardiomyopathy (DCM) remains to be elucidated. The present study was performed to investigate the changes in expression and the phosphorylation state of mitochondrial Cx43 in a rat model of DCM, and to determine whether the altered phosphorylation state of mitochondrial Cx43 was involved in mitochondrial dysfunction. A rat model of DCM was generated by daily oral administration of furazolidone (FZD) for 30 weeks. Reverse transcription polymerase chain reaction and western blot analysis revealed a decrease in the overall expression of Cx43, accompanied by reduced levels of serine 368‑phosphorylated‑Cx43 immunoreactivity in the myocardium and myocardial mitochondria. In addition, the mitochondrial membrane potential and the activities of cytochrome c oxidase, succinate dehydrogenase and protein kinase C (PKC) ε were all significantly reduced compared with those of the control group. Phorbol‑12‑myristate‑13‑acetate (PMA), a specific PKC activator, partially reversed the FZD‑induced mitochondrial Cx43 dephosphorylation at serine 368 and mitochondrial dysfunction in the cardiomyocytes. However, pretreatment with 18β‑glycerrhetinic acid, a connexin channel inhibitor, eliminated the mitochondrial protective effect of PMA in the cardiomyocytes sparsely plated without cell to cell contact. These results suggested that dephosphorylation of mitochondrial Cx43 at serine 368, due to the suppression of PKCε activity, may be a novel mechanism for mitochondrial dysfunction in the pathogenesis of DCM.
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Affiliation(s)
- Hu Shan
- Department of Cardiology, The Second Affiliated Hospital, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710004, P.R. China
| | - Jin Wei
- Department of Cardiology, The Second Affiliated Hospital, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710004, P.R. China
| | - Ming Zhang
- Department of Cardiology, The Second Affiliated Hospital, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710004, P.R. China
| | - Lin Lin
- Department of Cardiology, The Second Affiliated Hospital, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710004, P.R. China
| | - Rui Yan
- Department of Cardiology, The Second Affiliated Hospital, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710004, P.R. China
| | - Rong Zhang
- Department of Gastroenterology, Shaanxi Provincial People's Hospital, Xi'an, Shaanxi 710068, P.R. China
| | - Yan-He Zhu
- Department of Cardiology, The Second Affiliated Hospital, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi 710004, P.R. China
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13
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SUN JIMIN, WANG CHUNMIAO, GUO ZENG, HAO YUYU, XIE YANGJING, GU JIAN, WANG AILING. Reduction of isoproterenol-induced cardiac hypertrophy and modulation of myocardial connexin43 by a KATP channel agonist. Mol Med Rep 2014; 11:1845-50. [DOI: 10.3892/mmr.2014.2988] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 07/21/2014] [Indexed: 11/05/2022] Open
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14
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Oltulu F, Aktug H, Uysal A, Turgan N, Oktem G, Erbas O, Yavasoglu NK, Yavasoglu A. Immunoexpressions of embryonic and nonembryonic stem cell markers (Nanog, Thy-1, c-kit) and cellular connections (connexin 43 and occludin) on testicular tissue in thyrotoxicosis rat model. Hum Exp Toxicol 2014; 34:601-11. [PMID: 25304966 DOI: 10.1177/0960327114551392] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In this study, possible thyrotoxicosis-related histological changes in testicular tissues of rats with experimentally induced thyrotoxicosis model were evaluated on cellular connections and stem cell markers. Two experimental groups, thyrotoxicosis and control, each consisting of eight animals were used. Rats in the thyrotoxicosis group were injected intraperitoneally with 3,3',5-triiodo-l-thyronine (50 µg/100 g body weight/day) for 10 days. At the end of the study, animals in both groups were anesthetized, and blood samples were collected for biochemical analyses. Their testes were dissected out and histological procedure was conducted to perform further histochemical, immunohistochemical analyses and tissue expression analysis by real-time polymerase chain reaction. Expression of the stem cell markers such as c-kit and Thy-1 significantly decreased in the testes of the thyrotoxicosis group compared with the control group; however, Nanog expression was not detected in any of the groups. Similarly, connexin 43 and occludin expressions were also found to be significantly lower in the thyrotoxicosis group. These results on cellular connections are supported with the tissue expression analysis. Our findings are indicative of supporting microenvironmental tissue decay rather than parenchyma damage, which has been actually ignored in the literature. In conclusion, experimental thyrotoxicosis model may have adverse effects on the cell junctional complexes, cell-cell interactions, and pluripotency capacity.
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Affiliation(s)
- F Oltulu
- Department of Histology and Embryology, Merkez Efendi Hospital, Manisa, Turkey
| | - H Aktug
- Department of Histology and Embryology, Faculty of Medicine, Ege University, Izmir, Turkey
| | - A Uysal
- Department of Histology and Embryology, Faculty of Medicine, Ege University, Izmir, Turkey
| | - N Turgan
- Department of Biochemistry, Faculty of Medicine, Ege University, Izmir, Turkey
| | - G Oktem
- Department of Histology and Embryology, Faculty of Medicine, Ege University, Izmir, Turkey
| | - O Erbas
- Department of Physiology, Faculty of Medicine, Ege University, Izmir, Turkey
| | | | - A Yavasoglu
- Department of Histology and Embryology, Faculty of Medicine, Ege University, Izmir, Turkey
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15
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Abstract
Stem cell transplantation therapy has emerged as a promising regenerative medicine for ischemic stroke and other neurodegenerative disorders. However, many issues and problems remain to be resolved before successful clinical applications of the cell-based therapy. To this end, some recent investigations have sought to benefit from well-known mechanisms of ischemic/hypoxic preconditioning. Ischemic/hypoxic preconditioning activates endogenous defense mechanisms that show marked protective effects against multiple insults found in ischemic stroke and other acute attacks. As in many other cell types, a sub-lethal hypoxic exposure significantly increases the tolerance and regenerative properties of stem cells and progenitor cells. So far, a variety of preconditioning triggers have been tested on different stem cells and progenitor cells. Preconditioned stem cells and progenitors generally show much better cell survival, increased neuronal differentiation, enhanced paracrine effects leading to increased trophic support, and improved homing to the lesion site. Transplantation of preconditioned cells helps to suppress inflammatory factors and immune responses, and promote functional recovery. Although the preconditioning strategy in stem cell therapy is still an emerging research area, accumulating information from reports over the last few years already indicates it as an attractive, if not essential, prerequisite for transplanted cells. It is expected that stem cell preconditioning and its clinical applications will attract more attention in both the basic research field of preconditioning as well as in the field of stem cell translational research. This review summarizes the most important findings in this active research area, covering the preconditioning triggers, potential mechanisms, mediators, and functional benefits for stem cell transplant therapy.
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Affiliation(s)
- Shan Ping Yu
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, GA 30322, USA
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16
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Kalogeris T, Bao Y, Korthuis RJ. Mitochondrial reactive oxygen species: a double edged sword in ischemia/reperfusion vs preconditioning. Redox Biol 2014; 2:702-14. [PMID: 24944913 PMCID: PMC4060303 DOI: 10.1016/j.redox.2014.05.006] [Citation(s) in RCA: 532] [Impact Index Per Article: 48.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 05/23/2014] [Accepted: 05/27/2014] [Indexed: 02/06/2023] Open
Abstract
Reductions in the blood supply produce considerable injury if the duration of ischemia is prolonged. Paradoxically, restoration of perfusion to ischemic organs can exacerbate tissue damage and extend the size of an evolving infarct. Being highly metabolic organs, the heart and brain are particularly vulnerable to the deleterious effects of ischemia/reperfusion (I/R). While the pathogenetic mechanisms contributing to I/R-induced tissue injury and infarction are multifactorial, the relative importance of each contributing factor remains unclear. However, an emerging body of evidence indicates that the generation of reactive oxygen species (ROS) by mitochondria plays a critical role in damaging cellular components and initiating cell death. In this review, we summarize our current understanding of the mechanisms whereby mitochondrial ROS generation occurs in I/R and contributes to myocardial infarction and stroke. In addition, mitochondrial ROS have been shown to participate in preconditioning by several pharmacologic agents that target potassium channels (e.g., ATP-sensitive potassium (mKATP) channels or large conductance, calcium-activated potassium (mBKCa) channels) to activate cell survival programs that render tissues and organs more resistant to the deleterious effects of I/R. Finally, we review novel therapeutic approaches that selectively target mROS production to reduce postischemic tissue injury, which may prove efficacious in limiting myocardial dysfunction and infarction and abrogating neurocognitive deficits and neuronal cell death in stroke.
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Affiliation(s)
- Theodore Kalogeris
- Department of Medical Pharmacology and Physiology, School of Medicine, Dalton Cardiovascular Research Center, University of Missouri, 1 Hospital Drive, Columbia, MO 65212-0001, United States of America
| | - Yimin Bao
- Department of Medical Pharmacology and Physiology, School of Medicine, Dalton Cardiovascular Research Center, University of Missouri, 1 Hospital Drive, Columbia, MO 65212-0001, United States of America
| | - Ronald J Korthuis
- Department of Medical Pharmacology and Physiology, School of Medicine, Dalton Cardiovascular Research Center, University of Missouri, 1 Hospital Drive, Columbia, MO 65212-0001, United States of America
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17
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Carette D, Gilleron J, Chevallier D, Segretain D, Pointis G. Connexin a check-point component of cell apoptosis in normal and physiopathological conditions. Biochimie 2014; 101:1-9. [DOI: 10.1016/j.biochi.2013.11.015] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 11/18/2013] [Indexed: 12/16/2022]
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18
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Dague E, Genet G, Lachaize V, Guilbeau-Frugier C, Fauconnier J, Mias C, Payré B, Chopinet L, Alsteens D, Kasas S, Severac C, Thireau J, Heymes C, Honton B, Lacampagne A, Pathak A, Sénard JM, Galés C. Atomic force and electron microscopic-based study of sarcolemmal surface of living cardiomyocytes unveils unexpected mitochondrial shift in heart failure. J Mol Cell Cardiol 2014; 74:162-72. [PMID: 24839910 DOI: 10.1016/j.yjmcc.2014.05.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 05/07/2014] [Accepted: 05/08/2014] [Indexed: 10/25/2022]
Abstract
Loss of T-tubules (TT), sarcolemmal invaginations of cardiomyocytes (CMs), was recently identified as a general heart failure (HF) hallmark. However, whether TT per se or the overall sarcolemma is altered during HF process is still unknown. In this study, we directly examined sarcolemmal surface topography and physical properties using Atomic Force Microscopy (AFM) in living CMs from healthy and failing mice hearts. We confirmed the presence of highly organized crests and hollows along myofilaments in isolated healthy CMs. Sarcolemma topography was tightly correlated with elasticity, with crests stiffer than hollows and related to the presence of few packed subsarcolemmal mitochondria (SSM) as evidenced by electron microscopy. Three days after myocardial infarction (MI), CMs already exhibit an overall sarcolemma disorganization with general loss of crests topography thus becoming smooth and correlating with a decreased elasticity while interfibrillar mitochondria (IFM), myofilaments alignment and TT network were unaltered. End-stage post-ischemic condition (15days post-MI) exacerbates overall sarcolemma disorganization with, in addition to general loss of crest/hollow periodicity, a significant increase of cell surface stiffness. Strikingly, electron microscopy revealed the total depletion of SSM while some IFM heaps could be visualized beneath the membrane. Accordingly, mitochondrial Ca(2+) studies showed a heterogeneous pattern between SSM and IFM in healthy CMs which disappeared in HF. In vitro, formamide-induced sarcolemmal stress on healthy CMs phenocopied post-ischemic kinetics abnormalities and revealed initial SSM death and crest/hollow disorganization followed by IFM later disarray which moved toward the cell surface and structured heaps correlating with TT loss. This study demonstrates that the loss of crest/hollow organization of CM surface in HF occurs early and precedes disruption of the TT network. It also highlights a general stiffness increased of the CM surface most likely related to atypical IFM heaps while SSM died during HF process. Overall, these results indicate that initial sarcolemmal stress leading to SSM death could underlie subsequent TT disarray and HF setting.
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Affiliation(s)
- Etienne Dague
- CNRS, LAAS, F-31400 Toulouse, France; CNRS, ITAV-USR3505, Toulouse, France; Université de Toulouse, ITAV, LAAS, F-31400 Toulouse France.
| | - Gaël Genet
- Institut des Maladies Métaboliques et Cardiovasculaires, INSERM UMR1048, Toulouse, France
| | | | - Céline Guilbeau-Frugier
- Institut des Maladies Métaboliques et Cardiovasculaires, INSERM UMR1048, Toulouse, France; Department of Histopathology, Centre Hospitalier Universitaire de Toulouse, 31432 Toulouse, France
| | - Jérémy Fauconnier
- INSERM U1046, Université Montpellier 1, Université Montpellier 2, Montpellier, France
| | - Céline Mias
- Institut des Maladies Métaboliques et Cardiovasculaires, INSERM UMR1048, Toulouse, France
| | - Bruno Payré
- Centre de Microscopie Électronique Appliquée à la Biologie, Faculté de Médecine Rangueil, 31062 Toulouse, France
| | - Louise Chopinet
- CNRS, LAAS, F-31400 Toulouse, France; CNRS, IPBS-UMR5089, F-31077 Toulouse, France
| | - David Alsteens
- Institute of Life Sciences, Université Catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
| | - Sandor Kasas
- Department of Cellular Biology and Morphology, Université de Lausanne, Institut de Physique des Systèmes Biologiques, École Polytechnique Fédérale de Lausanne, Switzerland
| | - Childerick Severac
- CNRS, ITAV-USR3505, Toulouse, France; Université de Toulouse, ITAV, LAAS, F-31400 Toulouse France
| | - Jérôme Thireau
- INSERM U1046, Université Montpellier 1, Université Montpellier 2, Montpellier, France
| | - Christophe Heymes
- Institut des Maladies Métaboliques et Cardiovasculaires, INSERM UMR1048, Toulouse, France
| | - Benjamin Honton
- Institut des Maladies Métaboliques et Cardiovasculaires, INSERM UMR1048, Toulouse, France
| | - Alain Lacampagne
- INSERM U1046, Université Montpellier 1, Université Montpellier 2, Montpellier, France
| | - Atul Pathak
- Institut des Maladies Métaboliques et Cardiovasculaires, INSERM UMR1048, Toulouse, France; Department of Clinical Pharmacology, Centre Hospitalier Universitaire de Toulouse, F-31432 Toulouse, France
| | - Jean-Michel Sénard
- Institut des Maladies Métaboliques et Cardiovasculaires, INSERM UMR1048, Toulouse, France; Department of Clinical Pharmacology, Centre Hospitalier Universitaire de Toulouse, F-31432 Toulouse, France
| | - Céline Galés
- CNRS, ITAV-USR3505, Toulouse, France; Institut des Maladies Métaboliques et Cardiovasculaires, INSERM UMR1048, Toulouse, France.
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19
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Yu J, Berga SL, Zou W, Sun HY, Johnston-MacAnanny E, Yalcinkaya T, Sidell N, Bagchi IC, Bagchi MK, Taylor RN. Gap junction blockade induces apoptosis in human endometrial stromal cells. Mol Reprod Dev 2014; 81:666-75. [PMID: 24753074 DOI: 10.1002/mrd.22334] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 04/16/2014] [Indexed: 11/10/2022]
Abstract
One of the most dynamic adult human tissues is the endometrium. Through coordinated, cyclical proliferation, differentiation, leukocyte recruitment, apoptosis, and desquamation, the uterine lining is expanded and shed monthly, unless pregnancy is established. Errors in these steps potentially cause endometrial dysfunction, abnormal uterine bleeding, failed embryonic implantation, infertility, or endometrial carcinoma. Our prior studies showed that gap junctions comprised of Gap junction alpha-1 (GJA1) protein, also known as connexin 43 (CX43), subunits are critical to endometrial stromal cell differentiation. The current studies were undertaken to explore the mechanism of endometrial dysfunction when gap junction intercellular communication (GJIC) is disrupted. Gap junction blockade by two distinct GJIC inhibitors, 18α-glycyrrhetinic acid (AGA) and octanol (OcOH), suppressed proliferation and induced apoptosis in endometrial stromal cells, as manifested by reduced biomarkers of cell viability, increased TUNEL staining, caspase-3 activation, sub-G1 chromosomal DNA complement, as well as shortened telomere length. Unexpectedly, we also observed that the chemical inhibitors blocked CX43 gene expression. Moreover, when endometrial stromal cells were induced to undergo hormonal decidualization, following a 7-day exposure to 10 nM 17β-estradiol + 100 nM progesterone + 0.5 mM dibutyryl cAMP, characteristic epithelioid changes in cell shape and secretion of prolactin were blunted in the presence of AGA or OcOH, recapitulating effects of RNA interference of CX43. Our findings indicate that endometrial stromal cell proliferation and maintenance of decidualized endometrial function are GJIC-dependent, and that disruption of gap junctions induces endometrial stromal cell apoptosis. These observations may have important implications for several common clinical endometrial pathologies.
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Affiliation(s)
- Jie Yu
- Department of Obstetrics and Gynecology, Wake Forest School of Medicine, Winston-Salem, North California
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20
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Yavaşoğlu NÜK, Köksal C, Dağdeviren M, Aktuğ H, Yavaşoğlu A. Induction of oxidative stress and histological changes in liver by subacute doses of butyl cyclohexyl phthalate. ENVIRONMENTAL TOXICOLOGY 2014; 29:345-353. [PMID: 22936646 DOI: 10.1002/tox.21813] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 08/02/2012] [Accepted: 08/04/2012] [Indexed: 06/01/2023]
Abstract
Phthalates are esters of phthalic acid and are mainly used as plasticizers in a wide variety of products and applications. There is no information on butyl cyclohexyl phthalate (BCP) toxicity. This study was performed to evaluate the histopathological effects and to determine oxidative stress inducing potential in liver by subacute exposure of BCP. The animals of the treatment groups were orally administered 100, 200, and 400 mg/kg/day BCP for 5 consecutive days per week during 28 days. As a result, no significant changes were observed in body weight gains, and absolute and relative liver weights of liver of BCP treated mice, when compared with control group. Although the degree of lipid peroxidation in the liver tissue of all BCP exposure groups were significantly higher than those of the control (p < 0.01), SOD and CAT activities in liver tissue of mice of 200 and 400 mg/kg exposure groups were significantly lower than those of the controls (p < 0.01). Moreover, BCP caused dose-dependent histological changes in the liver of mice such as congestions in vena centralis, an enlargement of the sinusoids, degeneration in hepatocytes, vacuole formations and presence of lipid droplets in hepatocytes, eosinophilic cytoplasm. While iNOS immunoreactivity was increased in all treatment groups, Type IV collagen and Connexin 43 immunoreactivities were decreased in all treatment groups compared with the control group. Significant decrease was observed in the number of TUNEL-positive liver cells of BCP treated mice. These results suggested that BCP exposure induces oxidative stress in liver and exposure of BCP during long time period could lead to hepatocarcinogenesis.
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21
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Nielsen MS, Axelsen LN, Sorgen PL, Verma V, Delmar M, Holstein-Rathlou NH. Gap junctions. Compr Physiol 2013; 2:1981-2035. [PMID: 23723031 DOI: 10.1002/cphy.c110051] [Citation(s) in RCA: 313] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease.
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Affiliation(s)
- Morten Schak Nielsen
- Department of Biomedical Sciences and The Danish National Research Foundation Centre for Cardiac Arrhythmia, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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Fowler S, Akins M, Zhou H, Figeys D, Bennett SA. The liver connexin32 interactome is a novel plasma membrane-mitochondrial signaling nexus. J Proteome Res 2013; 12:2597-610. [PMID: 23590695 PMCID: PMC3714164 DOI: 10.1021/pr301166p] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Indexed: 02/07/2023]
Abstract
Connexins are the structural subunits of gap junctions and act as protein platforms for signaling complexes. Little is known about tissue-specific connexin signaling nexuses, given significant challenges associated with affinity-purifying endogenous channel complexes to the level required for interaction analyses. Here, we used multiple subcellular fractionation techniques to isolate connexin32-enriched membrane microdomains from murine liver. We show, for the first time, that connexin32 localizes to both the plasma membrane and inner mitochondrial membrane of hepatocytes. Using a combination of immunoprecipitation-high throughput mass spectrometry, reciprocal co-IP, and subcellular fractionation methodologies, we report a novel interactome validated using null mutant controls. Eighteen connexin32 interacting proteins were identified. The majority represent resident mitochondrial proteins, a minority represent plasma membrane, endoplasmic reticulum, or cytoplasmic partners. In particular, connexin32 interacts with connexin26 and the mitochondrial protein, sideroflexin-1, at the plasma membrane. Connexin32 interaction enhances connexin26 stability. Converging bioinformatic, biochemical, and confocal analyses support a role for connexin32 in transiently tethering mitochondria to connexin32-enriched plasma membrane microdomains through interaction with proteins in the outer mitochondrial membrane, including sideroflexin-1. Complex formation increases the pool of sideroflexin-1 that is present at the plasma membrane. Together, these data identify a novel plasma membrane/mitochondrial signaling nexus in the connexin32 interactome.
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Affiliation(s)
- Stephanie
L. Fowler
- Neural
Regeneration Laboratory, Ottawa Institute of Systems Biology, Department of
Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Mark Akins
- Neural
Regeneration Laboratory, Ottawa Institute of Systems Biology, Department of
Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Hu Zhou
- Neural
Regeneration Laboratory, Ottawa Institute of Systems Biology, Department of
Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
- Shanghai Institute of Materia
Medica, Chinese Academy of Sciences, Shanghai,
China
| | - Daniel Figeys
- Neural
Regeneration Laboratory, Ottawa Institute of Systems Biology, Department of
Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Steffany A.L. Bennett
- Neural
Regeneration Laboratory, Ottawa Institute of Systems Biology, Department of
Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
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Xiaowei C, Jia M, Xiaowei W, Yina Z. Overexpression of CXCL12 chemokine up-regulates connexin and integrin expression in mesenchymal stem cells through PI3K/Akt pathway. ACTA ACUST UNITED AC 2013; 20:67-72. [PMID: 23659290 DOI: 10.3109/15419061.2013.791682] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Mesenchymal stem cells offer several potential advantages over other types of stem cells for cardiac repair. Nevertheless, poor survival of donor cells is one of the major concerns that hampers a better prognosis. Integrins, which involved in cell/extracellular matrix (ECM) interaction and connexins (Cxs), with a dual role as an anti-apoptotic and gap-junctional protein, can effectively resolve this issue. CXCL12, a member of the chemokine CXC subfamily, may play a role in stem cell survival and proliferation. CXCL12 activates several signaling pathways in stem cells, particularly the survival kinase, PI3K/Akt, which is also an important mediator of integrins and Cxs. Based on these characteristics of CXCL12, we investigated the potential of CXCL12 overexpression to induce integrin and connexin expression via PI3K/Akt pathway. Mesenchymal stem cells were transfected with adenovirus for increasing CXCL12 secretion. Membranous integrin and Cx expression as well as Akt expression levels were evaluated using Western blot analysis. Transfection resulted in increased CXCL12 in situ. Increased CXCL12 elevated membrane Cx43, Cx45, and integrin αVβ3 expression, as well as Cx phosphorylaton, which was activated by PI3K/Akt pathway. This mechanism may serve to improve mesenchymal stem cell viability in host tissue.
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Affiliation(s)
- Chi Xiaowei
- The second affiliated Hospital of Harbin Medical University, Harbin, People's Republic of China.
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24
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Penna C, Perrelli MG, Pagliaro P. Mitochondrial pathways, permeability transition pore, and redox signaling in cardioprotection: therapeutic implications. Antioxid Redox Signal 2013; 18:556-99. [PMID: 22668069 DOI: 10.1089/ars.2011.4459] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Reperfusion therapy is the indispensable treatment of acute myocardial infarction (AMI) and must be applied as soon as possible to attenuate the ischemic insult. However, reperfusion is responsible for additional myocardial damage likely involving opening of the mitochondrial permeability transition pore (mPTP). A great part of reperfusion injury occurs during the first minute of reperfusion. The prolonged opening of mPTP is considered one of the endpoints of the cascade to myocardial damage, causing loss of cardiomyocyte function and viability. Opening of mPTP and the consequent oxidative stress due to reactive oxygen and nitrogen species (ROS/RNS) are considered among the major mechanisms of mitochondrial and myocardial dysfunction. Kinases and mitochondrial components constitute an intricate network of signaling molecules and mitochondrial proteins, which interact in response to stressors. Cardioprotective pathways are activated by stimuli such as preconditioning and postconditioning (PostC), obtained with brief intermittent ischemia or with pharmacological agents, which drastically reduce the lethal ischemia/reperfusion injury. The protective pathways converging on mitochondria may preserve their function. Protection involves kinases, adenosine triphosphate-dependent potassium channels, ROS signaling, and the mPTP modulation. Some clinical studies using ischemic PostC during angioplasty support its protective effects, and an interesting alternative is pharmacological PostC. In fact, the mPTP desensitizer, cyclosporine A, has been shown to induce appreciable protections in AMI patients. Several factors and comorbidities that might interfere with cardioprotective signaling are considered. Hence, treatments adapted to the characteristics of the patient (i.e., phenotype oriented) might be feasible in the future.
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Affiliation(s)
- Claudia Penna
- Department of Clinical and Biological Sciences, University of Turin, Orbassano, Italy
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Diabetes mellitus reduces the function and expression of ATP-dependent K⁺ channels in cardiac mitochondria. Life Sci 2012; 92:664-8. [PMID: 23261529 DOI: 10.1016/j.lfs.2012.11.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 11/21/2012] [Accepted: 11/24/2012] [Indexed: 11/20/2022]
Abstract
AIM Our goal was to determine the effects of type I diabetes mellitus on the function and expression of ATP-dependent K(+) channels in cardiac mitochondria (mitoKATP), composed of a pore-forming subunit (Kir6.1) and a diazoxide-sensitive sulphonylurea receptor (SUR1). We tested the hypothesis that diabetes reduces Kir6.1 and SUR1 expression as well as diazoxide-induced depolarization of mitochondrial membrane potential (ΔΨm). MAIN METHODS Male FVB mice were made diabetic for 5weeks with multiple low dose injections of streptozotocin. Cardiac mitochondria were separated into two populations: subsarcolemmal mitochondria (SSM) and interfibrillar mitochondria (IFM). mitoKATP expression was determined via Western blot analysis of Kir6.1 and SUR1 proteins. mitoKATP function was determined by measuring ΔΨm with the potentiometric dye rhodamine 123. KEY FINDINGS Diabetes reduced Kir6.1 and SUR1 expression in IFM by over 40% (p<0.05 for both). Similarly, diabetes reduced Kir6.1 expression in SSM by approximately 40% (p<0.05); however, SUR1 expression was unaffected. Opening mitoKATP with diazoxide (100μM) depolarized control IFM ΔΨm by 80% of the valinomycin maximum; diabetic IFM depolarized only 30% (p<0.05). Diazoxide-induced depolarization was much less in SSM (20-30%) and unaffected by diabetes. SIGNIFICANCE Our data indicate that diabetes reduces mitoKATP expression and function in IFM. These changes in mitoKATP may provide an opportunity to understand mechanisms leading to diabetic cardiomyopathy and loss of cardioprotective mechanisms in the diabetic heart.
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Boengler K, Ruiz-Meana M, Gent S, Ungefug E, Soetkamp D, Miro-Casas E, Cabestrero A, Fernandez-Sanz C, Semenzato M, Di Lisa F, Rohrbach S, Garcia-Dorado D, Heusch G, Schulz R. Mitochondrial connexin 43 impacts on respiratory complex I activity and mitochondrial oxygen consumption. J Cell Mol Med 2012; 16:1649-55. [PMID: 22212640 PMCID: PMC3822677 DOI: 10.1111/j.1582-4934.2011.01516.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Connexin 43 (Cx43) is present at the sarcolemma and the inner membrane of cardiomyocyte subsarcolemmal mitochondria (SSM). Lack or inhibition of mitochondrial Cx43 is associated with reduced mitochondrial potassium influx, which might affect mitochondrial respiration. Therefore, we analysed the importance of mitochondrial Cx43 for oxygen consumption. Acute inhibition of Cx43 in rat left ventricular (LV) SSM by 18α glycyrrhetinic acid (GA) or Cx43 mimetic peptides (Cx43-MP) reduced ADP-stimulated complex I respiration and ATP generation. Chronic reduction of Cx43 in conditional knockout mice (Cx43(Cre-ER(T)/fl) + 4-OHT, 5-10% of Cx43 protein compared with control Cx43(fl/fl) mitochondria) reduced ADP-stimulated complex I respiration of LV SSM to 47.8 ± 2.4 nmol O(2)/min.*mg protein (n = 8) from 61.9 ± 7.4 nmol O(2)/min.*mg protein in Cx43(fl/fl) mitochondria (n = 10, P < 0.05), while complex II respiration remained unchanged. The LV complex I activities (% of citrate synthase activity) of Cx43(Cre-ER(T)/fl) +4-OHT mice (16.1 ± 0.9%, n = 9) were lower than in Cx43(fl/fl) mice (19.8 ± 1.3%, n = 8, P < 0.05); complex II activities were similar between genotypes. Supporting the importance of Cx43 for respiration, in Cx43-overexpressing HL-1 cardiomyocytes complex I respiration was increased, whereas complex II respiration remained unaffected. Taken together, mitochondrial Cx43 is required for optimal complex I activity and respiration and thus mitochondrial ATP-production.
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Affiliation(s)
- Kerstin Boengler
- Institut für Pathophysiologie, Universitätsklinikum Essen, Essen, Germany
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Lee TM, Lin CC, Lien HY, Chen CC. K ATP channel agonists preserve connexin43 protein in infarcted rats by a protein kinase C-dependent pathway. J Cell Mol Med 2012; 16:776-88. [PMID: 21692984 PMCID: PMC3822848 DOI: 10.1111/j.1582-4934.2011.01366.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Downward remodelling of gap junctional proteins between myocytes may trigger ventricular arrhythmia after myocardial infarction. We have demonstrated that ATP-sensitive potassium (KATP) channel agonists attenuated post-infarction arrhythmias. However, the involved mechanisms remain unclear. The purpose of this study was to determine whether KATP channel agonists can attenuate arrhythmias through preserving protein kinase C (PKC)-–dependent connexin43 level after myocardial infarction. Male Wistar rats after ligating coronary artery were randomized to either vehicle, nicorandil, pinacidil, glibenclamide or a combination of nicorandil and glibenclamide or pinacidil and glibenclamide for 4 weeks. To elucidate the role of PKC in the modulation of connexin43 level, carbachol and myristoylated PKC V1–2 peptide were also assessed. Myocardial connexin43 level was significantly decreased in vehicle-treated infarcted rats compared with sham. Attenuated connexin43 level was blunted after administering KATP channel agonists, assessed by immunofluorescent analysis, Western blotting, and real-time quantitative reverse transcription-PCR of connexin43. Arrhythmic scores during programmed stimulation in the KATP channel agonists-treated rats were significantly lower than those treated with vehicle. The beneficial effects of KATP channel agonists were blocked by either glibenclamide or 5-hydroxydecanoate. Addition of the PKC activator, phorbol 12-myristate 13-acetate and the specific PKC agonist, carbachol, blocked the effects of nicorandil on connexin43 phosphorylation and dye permeability. The specific PKC antagonist, myristoylated PKC V1–2 peptide, did not have additional beneficial effects on connexin43 phosphorylation compared with rats treated with nicorandil alone. Chronic use of KATP channel agonists after infarction, resulting in enhanced connexin43 level through a PKC-dependent pathway, may attenuate the arrhythmogenic response to programmed electrical stimulation.
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Affiliation(s)
- Tsung-Ming Lee
- Department of Medicine, Cardiology Section, Taipei Medical University and Chi-Mei Medical Center, Tainan, Taiwan.
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28
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Bell R, Beeuwkes R, Bøtker HE, Davidson S, Downey J, Garcia-Dorado D, Hausenloy DJ, Heusch G, Ibanez B, Kitakaze M, Lecour S, Mentzer R, Miura T, Opie L, Ovize M, Ruiz-Meana M, Schulz R, Shannon R, Walker M, Vinten-Johansen J, Yellon D. Trials, tribulations and speculation! Report from the 7th Biennial Hatter Cardiovascular Institute Workshop. Basic Res Cardiol 2012; 107:300. [DOI: 10.1007/s00395-012-0300-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 09/11/2012] [Indexed: 02/05/2023]
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Lu G, Jiang S, Ashraf M, Haider KH. Subcellular preconditioning of stem cells: mito-Cx43 gene targeting is cytoprotective via shift of mitochondrial Bak and Bcl-xL balance. Regen Med 2012; 7:323-34. [PMID: 22594326 DOI: 10.2217/rme.12.13] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
AIM To achieve mitochondria-specific expression of connexin-43 (Cx43) transgene for mitochondrial preconditioning in stem cells to improve their survival post-transplantation during heart cell therapy. METHODS & RESULTS Cx43- or GFP-encoding adenoviral vectors with a mitochondrial targeting sequence were constructed for transduction of bone marrow Sca-1(+) cells (>90% transduction efficiency). Double-fluorescence immunostaining for cytochrome-c and Cx43 supported by western blotting confirmed mitochondria-specific Cx43 expression in adenoviral-mito-Cx43-transduced cells ((Cx43)Sca-1(+)). (Cx43)Sca-1(+) showed improved survival under lethal oxygen-glucose deprivation culture conditions. (Cx43)Sca-1(+) showed an increased mitochondrial Bcl-xL:Bak ratio and reduced cytochrome-c release into cytosol with concomitantly abolished caspase-3 activity. An in vivo study was performed such that 2 × 10(6) male (Cx43)Sca-1(+) or (GFP)Sca-1(+) cells were injected into a female rat model of acute myocardial infarction. DMEM-injected rats served as controls. On day 7 post-transplantation, 4.3-fold higher survival of (Cx43)Sca-1(+) cells (p < 0.05 vs control) and reduced terminal deoxynucleotidyl transferase dUTP nick end labeling positivity in the left ventricle (LV) were observed. In comparison, LV ejection fraction (40.2 ± 0.9%), LV fractional shortening (20.0 ± 1.6%) and LV end diastolic dimension (6.5 ± 0.3 mm) were observed in (GFP)Sca-1(+), and treatment with (Cx43)Sca-1(+) cells improved these parameters (47.6 ± 2.5%, p < 0.05; 27.7 ± 1.2%, p < 0.05; and 5.6 ± 0.1 mm, p < 0.05, respectively), along with concomitant reductions in infarction size (33.7 ± 2.9% vs 39.8 ± 1.4%; p < 0.05). CONCLUSION Mitochondria-targeted Cx43 expression is a novel approach to improve stem cell survival in the infarcted heart.
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Affiliation(s)
- Gang Lu
- Department of Pathology & Laboratory Medicine, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH 45267, USA
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Ahmad Waza A, Andrabi K, Ul Hussain M. Adenosine-triphosphate-sensitive K+ channel (Kir6.1): a novel phosphospecific interaction partner of connexin 43 (Cx43). Exp Cell Res 2012; 318:2559-66. [PMID: 22960107 DOI: 10.1016/j.yexcr.2012.08.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 08/21/2012] [Accepted: 08/22/2012] [Indexed: 01/30/2023]
Abstract
Connexin 43 (Cx43) is a phosphoprotein expressed in a wide variety of cells. Cx43 and adenosine-triphosphate-sensitive K(+)channels [K(+)(ATP)] are part of same signaling pathway that regulates cell survival during stress and ischemia preconditioning. Molecular mechanism for their coordinated role in ischemia/hypoxia preconditioning is not well known. Using pull down, co-immunoprecipitation assays and co-localization studies we provide evidence, for the first time that Kir6.1, a K(+)(ATP) channel protein component, can interact with Cx43. Further we show that the interaction was phospho-specific such that Cx43 phosphorylated at serine 262 (S262) interacted with Kir6.1 in preference to the unphosphorylated form of Cx43. Introduction of phospho-deficient mutation at serine 262 (S262A) in Cx43 completely abolished the interaction. Our data provide an interesting lead about a possible partnership between Cx43 and Kir6.1, which will help in better understanding their role in ischemia/hypoxia preconditioning.
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Frock RL, Chen SC, Da DF, Frett E, Lau C, Brown C, Pak DN, Wang Y, Muchir A, Worman HJ, Santana LF, Ladiges WC, Rabinovitch PS, Kennedy BK. Cardiomyocyte-specific expression of lamin a improves cardiac function in Lmna-/- mice. PLoS One 2012; 7:e42918. [PMID: 22905185 PMCID: PMC3419749 DOI: 10.1371/journal.pone.0042918] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 07/16/2012] [Indexed: 11/18/2022] Open
Abstract
Lmna(-/-) mice display multiple tissue defects and die by 6-8 weeks of age reportedly from dilated cardiomyopathy with associated conduction defects. We sought to determine whether restoration of lamin A in cardiomyocytes improves cardiac function and extends the survival of Lmna(-/-) mice. We observed increased total desmin protein levels and disorganization of the cytoplasmic desmin network in ~20% of Lmna(-/-) ventricular myocytes, rescued in a cell-autonomous manner in Lmna(-/-) mice expressing a cardiac-specific lamin A transgene (Lmna(-/-); Tg). Lmna(-/-); Tg mice displayed significantly increased contractility and preservation of myocardial performance compared to Lmna(-/-) mice. Lmna(-/-); Tg mice attenuated ERK1/2 phosphorylation relative to Lmna(-/-) mice, potentially underlying the improved localization of connexin43 to the intercalated disc. Electrocardiographic recordings from Lmna(-/-) mice revealed arrhythmic events and increased frequency of PR interval prolongation, which is partially rescued in Lmna(-/-); Tg mice. These findings support our observation that Lmna(-/-); Tg mice have a 12% median extension in lifespan compared to Lmna(-/-) mice. While significant, Lmna(-/-); Tg mice only have modest improvement in cardiac function and survival likely stemming from the observation that only 40% of Lmna(-/-); Tg cardiomyocytes have detectable lamin A expression. Cardiomyocyte-specific restoration of lamin A in Lmna(-/-) mice improves heart-specific pathology and extends lifespan, demonstrating that the cardiac pathology of Lmna(-/-) mice limits survival. The expression of lamin A is sufficient to rescue certain cellular defects associated with loss of A-type lamins in cardiomyocytes in a cell-autonomous fashion.
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Affiliation(s)
- Richard L. Frock
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Steven C. Chen
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Dao-Fu Da
- Department of Pathology, University of Washington, Seattle, Washington, United States of America
| | - Ellie Frett
- Department of Pharmacology and Physiology, University of Rochester, Rochester, New York, United States of America
| | - Carmen Lau
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Christina Brown
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Diana N. Pak
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Yuexia Wang
- Department of Medicine and Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America
| | - Antoine Muchir
- Department of Medicine and Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America
| | - Howard J. Worman
- Department of Medicine and Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, New York, United States of America
| | - Luis F. Santana
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
| | - Warren C. Ladiges
- Department of Comparative Medicine, University of Washington, Seattle, Washington, United States of America
| | - Peter S. Rabinovitch
- Department of Pathology, University of Washington, Seattle, Washington, United States of America
| | - Brian K. Kennedy
- Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
- Buck Institute for Age Research, Novato, California, United States of America
- * E-mail:
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Kar R, Batra N, Riquelme MA, Jiang JX. Biological role of connexin intercellular channels and hemichannels. Arch Biochem Biophys 2012; 524:2-15. [PMID: 22430362 PMCID: PMC3376239 DOI: 10.1016/j.abb.2012.03.008] [Citation(s) in RCA: 175] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 02/16/2012] [Accepted: 03/06/2012] [Indexed: 12/11/2022]
Abstract
Gap junctions (GJ) and hemichannels (HC) formed from the protein subunits called connexins are transmembrane conduits for the exchange of small molecules and ions. Connexins and another group of HC-forming proteins, pannexins comprise the two families of transmembrane proteins ubiquitously distributed in vertebrates. Most cell types express more than one connexin or pannexin. While connexin expression and channel activity may vary as a function of physiological and pathological states of the cell and tissue, only a few studies suggest the involvement of pannexin HC in acquired pathological conditions. Importantly, genetic mutations in connexin appear to interfere with GJ and HC function which results in several diseases. Thus connexins could serve as potential drug target for therapeutic intervention. Growing evidence suggests that diseases resulting from HC dysfunction might open a new direction for development of specific HC reagents. This review provides a comprehensive overview of the current studies of GJ and HC formed by connexins and pannexins in various tissue and organ systems including heart, central nervous system, kidney, mammary glands, ovary, testis, lens, retina, inner ear, bone, cartilage, lung and liver. In addition, present knowledge of the role of GJ and HC in cell cycle progression, carcinogenesis and stem cell development is also discussed.
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Affiliation(s)
| | | | - Manuel A Riquelme
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX 78229-3900
| | - Jean X. Jiang
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, TX 78229-3900
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Heusch G. HIF-1 and paradoxical phenomena in cardioprotection: EXPERT'S PERSPECTIVE. Cardiovasc Res 2012; 96:214-5; discussion 216-9. [DOI: 10.1093/cvr/cvs145] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Foster DB, Ho AS, Rucker J, Garlid AO, Chen L, Sidor A, Garlid KD, O'Rourke B. Mitochondrial ROMK channel is a molecular component of mitoK(ATP). Circ Res 2012; 111:446-54. [PMID: 22811560 DOI: 10.1161/circresaha.112.266445] [Citation(s) in RCA: 162] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Activation of the mitochondrial ATP-sensitive potassium channel (mitoK(ATP)) has been implicated in the mechanism of cardiac ischemic preconditioning, yet its molecular composition is unknown. OBJECTIVE To use an unbiased proteomic analysis of the mitochondrial inner membrane to identify the mitochondrial K(+) channel underlying mitoK(ATP). METHODS AND RESULTS Mass spectrometric analysis was used to identify KCNJ1(ROMK) in purified bovine heart mitochondrial inner membrane and ROMK mRNA was confirmed to be present in neonatal rat ventricular myocytes and adult hearts. ROMK2, a short form of the channel, is shown to contain an N-terminal mitochondrial targeting signal, and a full-length epitope-tagged ROMK2 colocalizes with mitochondrial ATP synthase β. The high-affinity ROMK toxin, tertiapin Q, inhibits mitoK(ATP) activity in isolated mitochondria and in digitonin-permeabilized cells. Moreover, short hairpin RNA-mediated knockdown of ROMK inhibits the ATP-sensitive, diazoxide-activated component of mitochondrial thallium uptake. Finally, the heart-derived cell line, H9C2, is protected from cell death stimuli by stable ROMK2 overexpression, whereas knockdown of the native ROMK exacerbates cell death. CONCLUSIONS The findings support ROMK as the pore-forming subunit of the cytoprotective mitoK(ATP) channel.
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Affiliation(s)
- D Brian Foster
- Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Abstract
Cardiac ischemia damages the mitochondrial electron transport chain and the damage persists during reperfusion. Ischemic postconditioning (PC), applied during early reperfusion, decreases cardiac injury. This finding suggests that the ischemia-damaged mitochondria can be regulated to decrease cardiac injury. The reversible blockade of electron transport during ischemia prevents damage to mitochondria. We propose that the targets of PC cytoprotective signaling are mitochondria damaged by ischemia. Thus, if ischemia-mediated mitochondrial damage is prevented, PC at the onset of reperfusion will not result in additional protection. Isolated, Langendorff-perfused adult rat hearts underwent 25-minute global ischemia and 30-minute reperfusion. Amobarbital (2.5 mM) was used to reversibly inhibit electron transport during ischemia. PC (6 cycles of 10-second ischemia-reperfusion) was applied at the onset of reperfusion. Subsarcolemmal and interfibrillar mitochondria were isolated after reperfusion. Blockade of electron transport with amobarbital only during ischemia preserved oxidative phosphorylation and decreased myocardial injury. PC, after untreated ischemia, decreased cardiac injury without improvement of oxidative phosphorylation. Blockade of electron transport during ischemia or PC improved calcium tolerance and inner membrane potential in subsarcolemmal mitochondria after reperfusion. In hearts treated with amobarbital before ischemia, PC did not provide further protection. Thus, PC protects myocardium via the regulation of ischemia-damaged mitochondria during early reperfusion.
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Cardiac vulnerability to ischemia/reperfusion injury drastically increases in late pregnancy. Basic Res Cardiol 2012; 107:271. [PMID: 22648276 DOI: 10.1007/s00395-012-0271-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 04/12/2012] [Accepted: 05/02/2012] [Indexed: 12/11/2022]
Abstract
Although the murine late pregnant (LP) heart is speculated to be a better functioning heart during physiological conditions, the susceptibility of LP hearts to I/R injury is still unknown. The aims of this study were to investigate the cardiac vulnerability of LP rodents to ischemia/reperfusion (I/R) injury and to explore its underlying mechanisms. In vivo female rat hearts [non-pregnant (NP) or LP] or ex vivo Langendorff-perfused mouse hearts were subjected to I/R. The infarct size was approximately fourfold larger in LP animals compared with NP both in vivo and ex vivo. The heart functional recovery was extremely poor in LP mice compared with NP (~10% recovery in LP vs. 80% recovery in NP at the end of reperfusion, P < 0.01). Interestingly, the poor functional recovery and the larger infarct size in LP were partially restored one day post-partum and almost fully restored 1 week post-partum to their corresponding NP levels. Mitochondrial respiratory function and the threshold for opening of the mitochondrial permeability transition pore were significantly lower in LP compared with NP when they both were subjected to myocardial I/R injury [Respiratory control ratio = 1.9 ± 0.1 vs. 4.0 ± 0.5 in NP, P < 0.05; calcium retention capacity (CRC) = 167 ± 10 vs. 233 ± 18 nmol/mg protein in NP, P < 0.01]. Cardiac reactive oxygen species (ROS) generation, as well mitochondrial superoxide production, was approximately twofold higher in LP compared with NP following I/R. The phosphorylation levels of Akt, ERK1/2, and STAT3, but not GSK3β, were significantly reduced in the hearts from LP subjected to I/R. In conclusion, increased mitochondrial ROS generation, decreased CRC as well as impaired activation of Akt/ERK/STAT3 at reperfusion are the possible underlying mechanisms for higher vulnerability of LP hearts to I/R.
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Ishikawa S, Kuno A, Tanno M, Miki T, Kouzu H, Itoh T, Sato T, Sunaga D, Murase H, Miura T. Role of connexin-43 in protective PI3K-Akt-GSK-3β signaling in cardiomyocytes. Am J Physiol Heart Circ Physiol 2012; 302:H2536-44. [PMID: 22505645 DOI: 10.1152/ajpheart.00940.2011] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Sarcolemmal connexin-43 (Cx43) and mitochondrial Cx43 play distinct roles: formation of gap junctions and production of reactive oxygen species (ROS) for redox signaling. In this study, we examined the hypothesis that Cx43 contributes to activation of a major cytoprotective signal pathway, phosphoinositide 3-kinase (PI3K)-Akt-glycogen synthase kinase-3β (GSK-3β) signaling, in cardiomyocytes. A δ-opioid receptor agonist {[d-Ala(2),d-Leu(5)]enkephalin acetate (DADLE)}, endothelin-1 (ET-1), and insulin-like growth factor-1 (IGF-1) induced phosphorylation of Akt and GSK-3β in H9c2 cardiomyocytes. Reduction of Cx43 protein to 20% of the normal level by Cx43 small interfering RNA abolished phosphorylation of Akt and GSK-3β induced by DADLE or ET-1 but not that induced by IGF-1. DADLE and IGF-1 protected H9c2 cells from necrosis after treatment with H(2)O(2) or antimycin A. The protection by DADLE or ET-1, but not that by IGF-1, was lost by reduction of Cx43 protein expression. In contrast to Akt and GSK-3β, PKC-ε, ERK and p38 mitogen-activated protein kinase were phosphorylated by ET-1 in Cx43-knocked-down cells. Like diazoxide, an activator of the mitochondrial ATP-sensitive K(+) channel, DADLE and ET-1 induced significant ROS production in mitochondria, although such an effect was not observed for IGF-1. Cx43 knockdown did not attenuate the mitochondrial ROS production by DADLE or ET-1. Cx43 was coimmunoprecipitated with the β-subunit of G protein (Gβ), and knockdown of Gβ mimicked the effect of Cx43 knockdown on ET-1-induced phosphorylation of Akt and GSK-3β. These results suggest that Cx43 contributes to activation of class I(B) PI3K in PI3K-Akt-GSK-3β signaling possibly as a cofactor of Gβ in cardiomyocytes.
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Affiliation(s)
- Satoko Ishikawa
- Division of Cardiology, Second Department of Internal Medicine, Sapporo Medical University, School of Medicine, Sapporo, Japan
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Ponsaerts R, Wang N, Himpens B, Leybaert L, Bultynck G. The contractile system as a negative regulator of the connexin 43 hemichannel. Biol Cell 2012; 104:367-77. [DOI: 10.1111/boc.201100079] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Accepted: 02/21/2012] [Indexed: 02/04/2023]
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Glycogen synthase kinase 3β transfers cytoprotective signaling through connexin 43 onto mitochondrial ATP-sensitive K+ channels. Proc Natl Acad Sci U S A 2012; 109:E242-51. [PMID: 22238425 DOI: 10.1073/pnas.1107479109] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Despite compelling evidence supporting key roles for glycogen synthase kinase 3β (GSK3β), mitochondrial adenosine triphosphate-sensitive K(+) (mitoK(ATP)) channels, and mitochondrial connexin 43 (Cx43) in cytoprotection, it is not clear how these signaling modules are linked mechanistically. By patch-clamping the inner membrane of murine cardiac mitochondria, we found that inhibition of GSK3β activated mitoK(ATP). PKC activation and protein phosphatase 2a inhibition increased the open probability of mitoK(ATP) channels through GSK3β, and this GSK3β signal was mediated via mitochondrial Cx43. Moreover, (i) PKC-induced phosphorylation of mitochondrial Cx43 was reduced in GSK3β-S9A mice; (ii) Cx43 and GSK3β proteins associated in mitochondria; and (iii) SB216763-mediated reduction of infarct size was abolished in Cx43 KO mice in vivo, consistent with the notion that GSK3β inhibition results in mitoK(ATP) opening via mitochondrial Cx43. We therefore directly targeted mitochondrial Cx43 by the Cx43 C-terminal binding peptide RRNYRRNY for cardioprotection, circumventing further upstream pathways. RRNYRRNY activated mitoK(ATP) channels via Cx43. We directly recorded mitochondrial Cx43 channels that were activated by RRNYRRNY and blocked by the Cx43 mimetic peptide (43)GAP27. RRNYRRNY rendered isolated cardiomyocytes in vitro and the heart in vivo resistant to ischemia/reperfusion injury, indicating that mitochondrial Cx43- and/or mitoK(ATP)-mediated reduction of infarct size was not undermined by RRNYRRNY-related opening of sarcolemmal Cx43 channels. Our results demonstrate that GSK3β transfers cytoprotective signaling through mitochondrial Cx43 onto mitoK(ATP) channels and that Cx43 functions as a channel in mitochondria, being an attractive target for drug treatment against cardiomyocyte injury.
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Szabò I, Leanza L, Gulbins E, Zoratti M. Physiology of potassium channels in the inner membrane of mitochondria. Pflugers Arch 2011; 463:231-46. [PMID: 22089812 DOI: 10.1007/s00424-011-1058-7] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2011] [Accepted: 10/30/2011] [Indexed: 02/06/2023]
Abstract
The inner membrane of the ATP-producing organelles of endosymbiotic origin, mitochondria, has long been considered to be poorly permeable to cations and anions, since the strict control of inner mitochondrial membrane permeability is crucial for efficient ATP synthesis. Over the past 30 years, however, it has become clear that various ion channels--along with antiporters and uniporters--are present in the mitochondrial inner membrane, although at rather low abundance. These channels are important for energy supply, and some are a decisive factor in determining whether a cell lives or dies. Their electrophysiological and pharmacological characterisations have contributed importantly to the ongoing elucidation of their pathophysiological roles. This review gives an overview of recent advances in our understanding of the functions of the mitochondrial potassium channels identified so far. Open issues concerning the possible molecular entities giving rise to the observed activities and channel protein targeting to mitochondria are also discussed.
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Affiliation(s)
- Ildikò Szabò
- Department of Biology, University of Padova, Padova, Italy.
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Ischemic preconditioning: the role of mitochondria and aging. Exp Gerontol 2011; 47:1-7. [PMID: 22100642 DOI: 10.1016/j.exger.2011.11.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 10/24/2011] [Accepted: 11/02/2011] [Indexed: 11/22/2022]
Abstract
Aging represents a triple threat for myocardial infarction (MI). Not only does the incidence of MI increase with age, but the heart becomes more susceptible to MI induced damage and protective interventions such as ischemic preconditioning (IPC) become less effective. Therefore, any rational therapeutic strategy must be built around the ability to combat the detrimental effects of ischemia in aged individuals. To accomplish this, we need to develop a better understanding of how ischemic damage, protection, and aging are linked. In this regard, mitochondria have emerged as a common theme. First, mitochondria contribute to cell damage during ischemia-reperfusion (IR) and are central to cell death. Second, the protective signaling pathways activated by IPC converge on mitochondria, and the opening of mitochondrial ion channels alone is sufficient to elicit protection. Finally, mitochondria clearly influence the aging process, and specific defects in mitochondrial activity are associated with age-related functional decline. This review will summarize the effects of aging on myocardial IR injury and discuss relevant and emerging strategies to protect against MI with an emphasis on mitochondrial function.
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Gregory M, Kahiri CN, Barr KJ, Smith CE, Hermo L, Cyr DG, Kidder GM. Male reproductive system defects and subfertility in a mutant mouse model of oculodentodigital dysplasia1. ACTA ACUST UNITED AC 2011; 34:e630-41. [DOI: 10.1111/j.1365-2605.2011.01224.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Ye Y, Perez-Polo JR, Aguilar D, Birnbaum Y. The potential effects of anti-diabetic medications on myocardial ischemia-reperfusion injury. Basic Res Cardiol 2011; 106:925-52. [PMID: 21892746 DOI: 10.1007/s00395-011-0216-6] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Revised: 08/04/2011] [Accepted: 08/16/2011] [Indexed: 12/15/2022]
Abstract
Heart disease and stroke account for 65% of the deaths in people with diabetes mellitus (DM). DM and hyperglycemia cause systemic inflammation, endothelial dysfunction, a hypercoagulable state with impaired fibrinolysis and increased platelet degranulation, and reduced coronary collateral blood flow. DM also interferes with myocardial protection afforded by preconditioning and postconditioning. Newer anti-diabetic agents should not only reduce serum glucose and HbA1c levels, but also improve cardiovascular outcomes. The older sulfonylurea agent, glyburide, abolishes the benefits of ischemic and pharmacologic preconditioning, but newer sulfonylurea agents, such as glimepiride, may not interfere with preconditioning. GLP-1 analogs and sitagliptin, an oral dipeptidyl peptidase IV inhibitor, limit myocardial infarct size in animal models by increasing intracellular cAMP levels and activating protein kinase A, whereas metformin protects the heart by activating AMP-activated protein kinase. Both thiazolidinediones (rosiglitazone and pioglitazone) limit infarct size in animal models. The protective effect of pioglitazone is dependent on downstream activation of cytosolic phospholipase A(2) and cyclooxygenase-2 with subsequent increased production of 15-epi-lipoxin A(4), prostacyclin and 15-d-PGJ(2). We conclude that agents used to treat DM have additional actions that have been shown to affect the ability of the heart to protect itself against ischemia-reperfusion injury in preclinical models. However, the effects of these agents in doses used in the clinical setting to minimize ischemia-reperfusion injury and to affect clinical outcomes in patients with DM have yet to be shown. The clinical implications as well as the mechanisms of protection should be further studied.
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Affiliation(s)
- Yumei Ye
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA
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44
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EphB signaling inhibits gap junctional intercellular communication and synchronized contraction in cultured cardiomyocytes. Basic Res Cardiol 2011; 106:1057-68. [DOI: 10.1007/s00395-011-0219-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 08/04/2011] [Accepted: 08/22/2011] [Indexed: 12/20/2022]
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45
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Sanada S, Komuro I, Kitakaze M. Pathophysiology of myocardial reperfusion injury: preconditioning, postconditioning, and translational aspects of protective measures. Am J Physiol Heart Circ Physiol 2011; 301:H1723-41. [PMID: 21856909 DOI: 10.1152/ajpheart.00553.2011] [Citation(s) in RCA: 277] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Heart diseases due to myocardial ischemia, such as myocardial infarction or ischemic heart failure, are major causes of death in developed countries, and their number is unfortunately still growing. Preliminary exploration into the pathophysiology of ischemia-reperfusion injury, together with the accumulation of clinical evidence, led to the discovery of ischemic preconditioning, which has been the main hypothesis for over three decades for how ischemia-reperfusion injury can be attenuated. The subcellular pathophysiological mechanism of ischemia-reperfusion injury and preconditioning-induced cardioprotection is not well understood, but extensive research into components, including autacoids, ion channels, receptors, subcellular signaling cascades, and mitochondrial modulators, as well as strategies for modulating these components, has made evolutional progress. Owing to the accumulation of both basic and clinical evidence, the idea of ischemic postconditioning with a cardioprotective potential has been discovered and established, making it possible to apply this knowledge in the clinical setting after ischemia-reperfusion insult. Another a great outcome has been the launch of translational studies that apply basic findings for manipulating ischemia-reperfusion injury into practical clinical treatments against ischemic heart diseases. In this review, we discuss the current findings regarding the fundamental pathophysiological mechanisms of ischemia-reperfusion injury, the associated protective mechanisms of ischemic pre- and postconditioning, and the potential seeds for molecular, pharmacological, or mechanical treatments against ischemia-reperfusion injury, as well as subsequent adverse outcomes by modulation of subcellular signaling mechanisms (especially mitochondrial function). We also review emerging translational clinical trials and the subsistent clinical comorbidities that need to be overcome to make these trials applicable in clinical medicine.
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Affiliation(s)
- Shoji Sanada
- Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Suita, Japan
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Wang ZH, Chen YX, Zhang CM, Wu L, Yu Z, Cai XL, Guan Y, Zhou ZN, Yang HT. Intermittent hypobaric hypoxia improves postischemic recovery of myocardial contractile function via redox signaling during early reperfusion. Am J Physiol Heart Circ Physiol 2011; 301:H1695-705. [PMID: 21821784 DOI: 10.1152/ajpheart.00276.2011] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intermittent hypobaric hypoxia (IHH) protects hearts against ischemia-reperfusion (I/R) injury, but the underlying mechanisms are far from clear. ROS are paradoxically regarded as a major cause of myocardial I/R injury and a trigger of cardioprotection. In the present study, we investigated whether the ROS generated during early reperfusion contribute to IHH-induced cardioprotection. Using isolated perfused rat hearts, we found that IHH significantly improved the postischemic recovery of left ventricular (LV) contractile function with a concurrent reduction of lactate dehydrogenase release and myocardial infarct size (20.5 ± 5.3% in IHH vs. 42.1 ± 3.8% in the normoxic control, P < 0.01) after I/R. Meanwhile, IHH enhanced the production of protein carbonyls and malondialdehyde, respective products of protein oxidation and lipid peroxidation, in the reperfused myocardium and ROS generation in reperfused cardiomyocytes. Such effects were blocked by the mitochondrial ATP-sensitive K(+) channel inhibitor 5-hydroxydecanoate. Moreover, the IHH-improved postischemic LV performance, enhanced phosphorylation of PKB (Akt), PKC-ε, and glycogen synthase kinase-3β, as well as translocation of PKC-ε were not affected by applying H(2)O(2) (20 μmol/l) during early reperfusion but were abolished by the ROS scavengers N-(2-mercaptopropionyl)glycine (MPG) and manganese (III) tetrakis (1-methyl-4-pyridyl)porphyrin. Furthermore, IHH-reduced lactate dehydrogenase release and infarct size were reversed by MPG. Consistently, inhibition of Akt with wortmannin and PKC-ε with εV1-2 abrogated the IHH-improved postischemic LV performance. These findings suggest that IHH-induced cardioprotection depends on elevated ROS production during early reperfusion.
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Affiliation(s)
- Zhi-Hua Wang
- Key Laboratory of Stem Cell Biology and Laboratory of Molecular Cardiology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, and Shanghai Jiao Tong University School of Medicine, Shanghai, China
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47
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Rodríguez-Sinovas A, Sánchez JA, Fernandez-Sanz C, Ruiz-Meana M, Garcia-Dorado D. Connexin and pannexin as modulators of myocardial injury. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:1962-70. [PMID: 21839721 DOI: 10.1016/j.bbamem.2011.07.041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Revised: 07/20/2011] [Accepted: 07/28/2011] [Indexed: 01/02/2023]
Abstract
Multicellular organisms have developed a variety of mechanisms that allow communication between their cells. Whereas some of these systems, as neurotransmission or hormones, make possible communication between remote areas, direct cell-to-cell communication through specific membrane channels keep in contact neighboring cells. Direct communication between the cytoplasm of adjacent cells is achieved in vertebrates by membrane channels formed by connexins. However, in addition to allowing exchange of ions and small metabolites between the cytoplasms of adjacent cells, connexin channels also communicate the cytosol with the extracellular space, thus enabling a completely different communication system, involving activation of extracellular receptors. Recently, the demonstration of connexin at the inner mitochondrial membrane of cardiomyocytes, probably forming hemichannels, has enlarged the list of actions of connexins. Some of these mechanisms are also shared by a different family of proteins, termed pannexins. Importantly, these systems allow not only communication between healthy cells, but also play an important role during different types of injury. The aim of this review is to discuss the role played by both connexin hemichannels and pannexin channels in cell communication and injury. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.
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Jeyaraman MM, Srisakuldee W, Nickel BE, Kardami E. Connexin43 phosphorylation and cytoprotection in the heart. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:2009-13. [PMID: 21763271 DOI: 10.1016/j.bbamem.2011.06.023] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Revised: 06/17/2011] [Accepted: 06/27/2011] [Indexed: 01/20/2023]
Abstract
The fundamental role played by connexins including connexin43 (Cx43) in forming intercellular communication channels (gap junctions), ensuring electrical and metabolic coupling between cells, has long been recognized and extensively investigated. There is also increasing recognition that Cx43, and other connexins, have additional roles, such as the ability to regulate cell proliferation, migration, and cytoprotection. Multiple phosphorylation sites, targets of different signaling pathways, are present at the regulatory, C-terminal domain of Cx43, and contribute to constitutive as well as transient phosphorylation Cx43 patterns, responding to ever-changing environmental stimuli and corresponding cellular needs. The present paper will focus on Cx43 in the heart, and provide an overview of the emerging recognition of a relationship between Cx43, its phosphorylation pattern, and development of resistance to injury. We will also review our recent work regarding the role of an enhanced phosphorylation state of Cx43 in cardioprotection. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.
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Di Lisa F, Carpi A, Giorgio V, Bernardi P. The mitochondrial permeability transition pore and cyclophilin D in cardioprotection. BIOCHIMICA ET BIOPHYSICA ACTA 2011; 1813:1316-22. [PMID: 21295622 DOI: 10.1016/j.bbamcr.2011.01.031] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 01/18/2011] [Accepted: 01/26/2011] [Indexed: 01/12/2023]
Abstract
Mitochondria play a central role in heart energy metabolism and Ca(2+) homeostasis and are involved in the pathogenesis of many forms of heart disease. The body of knowledge on mitochondrial pathophysiology in living cells and organs is increasing, and so is the interest in mitochondria as potential targets for cardioprotection. This critical review will focus on the permeability transition pore (PTP) and its regulation by cyclophilin (CyP) D as effectors of endogenous protective mechanisms and as potential drug targets. The complexity of the regulatory interactions underlying control of mitochondrial function in vivo is beginning to emerge, and although apparently contradictory findings still exist we believe that the network of regulatory protein interactions involving the PTP and CyPs in physiology and pathology will increase our repertoire for therapeutic interventions in heart disease. This article is part of a Special Issue entitled: Mitochondria and Cardioprotection.
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Affiliation(s)
- Fabio Di Lisa
- Department of Biomedical Sciences and CNR Institute of Neuroscience, University of Padova, 35121 Padova, Italy.
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50
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Murphy E, Steenbergen C. What makes the mitochondria a killer? Can we condition them to be less destructive? BIOCHIMICA ET BIOPHYSICA ACTA 2011; 1813:1302-8. [PMID: 20837069 PMCID: PMC3398608 DOI: 10.1016/j.bbamcr.2010.09.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 08/10/2010] [Accepted: 09/01/2010] [Indexed: 12/22/2022]
Abstract
Cardioprotection, such as preconditioning and postconditioning, has been shown to result in a significant reduction in cell death. Many of the signaling pathways activated by cardioprotection have been elucidated, but there is still a lack of understanding of the mechanisms by which these signaling pathways reduce cell death. Mitochondria have been reported to be an important player in many types of apoptotic and necrotic cell death. If mitochondria play an important role in cell death, then it seems reasonable to consider that cardioprotective mechanisms might act, at least in part, by opposing mitochondrial cell death pathways. One of the major mechanisms of cell death in ischemia-reperfusion is suggested to be the opening of a large conductance pore in the inner mitochondrial membrane, known as the mitochondrial permeability transition pore. Inhibition of this mitochondrial pore appears to be one of the major mechanisms by which cardioprotection reduces cell death. Cardioprotection activates a number of signaling pathways that reduce the level of triggers (reactive oxygen species and calcium) or enhances inhibitors of the mitochondrial permeability transition pore at the start of reperfusion. This article is part of a Special Issue entitled: Mitochondria and Cardioprotection.
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Affiliation(s)
- Elizabeth Murphy
- Translational Medicine Branch, NHLBI, NIH, Bethesda, MD 20892, USA.
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