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Aydin Ö, Wahlström A, de Jonge PA, Meijnikman AS, Sjöland W, Olsson L, Henricsson M, de Goffau MC, Oonk S, Bruin SC, Acherman YIZ, Marschall HU, Gerdes VEA, Nieuwdorp M, Bäckhed F, Groen AK. An integrated analysis of bile acid metabolism in humans with severe obesity. Hepatology 2025; 81:19-31. [PMID: 39010331 DOI: 10.1097/hep.0000000000000938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 03/26/2024] [Indexed: 07/17/2024]
Abstract
BACKGROUND AND AIMS Bile acids (BA) are vital regulators of metabolism. BAs are AQ6 secreted in the small intestine, reabsorbed, and transported back to the liver, where they can modulate metabolic functions. There is a paucity of data regarding the portal BA composition in humans. This study aimed to address this knowledge gap by investigating portal BA composition and the relation with peripheral and fecal BA dynamics in conjunction with the gut microbiome. APPROACH AND RESULTS Thirty-three individuals from the BARIA cohort were included. Portal plasma, peripheral plasma, and feces were collected. BA and C4 levels were measured employing mass spectrometry. FGF19 was measured using ELISA. Gut microbiota composition was determined through metagenomics analysis on stool samples. Considerable diversity in the portal BA composition was observed. The majority (n = 26) of individuals had a 9-fold higher portal than peripheral BA concentration. In contrast, 8 individuals showed lower portal BA concentration compared with peripheral and had higher levels of unconjugated and secondary BA in this compartment, suggesting more distal origin. The altered portal BA profile was associated with altered gut microbiota composition. In particular, taxa within Bacteroides were reduced in abundance in the feces of these individuals. CONCLUSIONS Characterization of the portal BA composition in relation to peripheral and fecal BA increased insight into the dynamics of BA metabolism in individuals with obesity. Peripheral BA composition was much more diverse due to microbial metabolism. About 24% of the portal samples was surprisingly low in total BA; the underlying mechanism requires further exploration.
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Affiliation(s)
- Ömrüm Aydin
- Department of Internal and (Experimental) Vascular Medicine, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands
- Department of Vascular Medicine, ACS Institute, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands
| | - Annika Wahlström
- Wallenberg Laboratory and Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Patrick A de Jonge
- Department of Internal and (Experimental) Vascular Medicine, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands
- Department of Vascular Medicine, ACS Institute, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands
| | - Abraham S Meijnikman
- Department of Internal and (Experimental) Vascular Medicine, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands
- Department of Vascular Medicine, ACS Institute, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands
| | - Wilhelm Sjöland
- Wallenberg Laboratory and Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Lisa Olsson
- Wallenberg Laboratory and Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Marcus Henricsson
- Wallenberg Laboratory and Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Marcus C de Goffau
- Department of Internal and (Experimental) Vascular Medicine, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands
- Department of Vascular Medicine, ACS Institute, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands
| | - Stijn Oonk
- Department of Scientific Research, Data Science, Spaarne Gasthuis Hospital, Hoofddorp, the Netherlands
| | - Sjoerd C Bruin
- Department of Bariatric Surgery, Spaarne Gasthuis Hospital, Hoofddorp, the Netherlands
| | - Yair I Z Acherman
- Department of Bariatric Surgery, Spaarne Gasthuis Hospital, Hoofddorp, the Netherlands
| | - Hanns-Ulrich Marschall
- Wallenberg Laboratory and Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Victor E A Gerdes
- Department of Internal and (Experimental) Vascular Medicine, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands
- Department of Vascular Medicine, ACS Institute, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands
- Department of Bariatric Surgery, Spaarne Gasthuis Hospital, Hoofddorp, the Netherlands
- Department of Internal Medicine, Spaarne Gasthuis Hospital, Hoofddorp, the Netherlands
| | - Max Nieuwdorp
- Department of Internal and (Experimental) Vascular Medicine, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands
- Department of Vascular Medicine, ACS Institute, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands
| | - Fredrik Bäckhed
- Wallenberg Laboratory and Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Department of Clinical Physiology, Region Västra Götaland, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Albert K Groen
- Department of Internal and (Experimental) Vascular Medicine, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands
- Department of Vascular Medicine, ACS Institute, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands
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Calzadilla N, Comiskey SM, Dudeja PK, Saksena S, Gill RK, Alrefai WA. Bile acids as inflammatory mediators and modulators of intestinal permeability. Front Immunol 2022; 13:1021924. [PMID: 36569849 PMCID: PMC9768584 DOI: 10.3389/fimmu.2022.1021924] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 10/26/2022] [Indexed: 12/12/2022] Open
Abstract
Bile acids are critical for the digestion and absorption of lipids and fat-soluble vitamins; however, evidence continues to emerge supporting additional roles for bile acids as signaling molecules. After they are synthesized from cholesterol in the liver, primary bile acids are modified into secondary bile acids by gut flora contributing to a diverse pool and making the composition of bile acids highly sensitive to alterations in gut microbiota. Disturbances in bile acid homeostasis have been observed in patients with Inflammatory Bowel Diseases (IBD). In fact, a decrease in secondary bile acids was shown to occur because of IBD-associated dysbiosis. Further, the increase in luminal bile acids due to malabsorption in Crohn's ileitis and ileal resection has been implicated in the induction of diarrhea and the exacerbation of inflammation. A causal link between bile acid signaling and intestinal inflammation has been recently suggested. With respect to potential mechanisms related to bile acids and IBD, several studies have provided strong evidence for direct effects of bile acids on intestinal permeability in porcine and rodent models as well as in humans. Interestingly, different bile acids were shown to exert distinct effects on the inflammatory response and intestinal permeability that require careful consideration. Such findings revealed a potential effect for changes in the relative abundance of different bile acids on the induction of inflammation by bile acids and the development of IBD. This review summarizes current knowledge about the roles for bile acids as inflammatory mediators and modulators of intestinal permeability mainly in the context of inflammatory bowel diseases.
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Affiliation(s)
- Nathan Calzadilla
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois, Chicago, IL, United States
- Department of Bioengineering, University of Illinois, Chicago, IL, United States
| | - Shane M. Comiskey
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois, Chicago, IL, United States
| | - Pradeep K. Dudeja
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois, Chicago, IL, United States
- Research and Development, Jesse Brown VA Medical Center, Chicago, IL, United States
| | - Seema Saksena
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois, Chicago, IL, United States
- Research and Development, Jesse Brown VA Medical Center, Chicago, IL, United States
| | - Ravinder K. Gill
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois, Chicago, IL, United States
| | - Waddah A. Alrefai
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois, Chicago, IL, United States
- Research and Development, Jesse Brown VA Medical Center, Chicago, IL, United States
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Salat APJ, Williams KL, Chiu S, Eickmeyer DC, Kimpe LE, Blais JM, Crump D. Extracts from Dated Lake Sediment Cores in the Athabasca Oil Sands Region Alter Ethoxyresorufin-O-deethylase Activity and Gene Expression in Avian Hepatocytes. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2021; 40:1883-1893. [PMID: 33751657 DOI: 10.1002/etc.5040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 02/12/2021] [Accepted: 03/07/2021] [Indexed: 06/12/2023]
Abstract
Increases in oil sands mining operations in the Athabasca oil sands region have resulted in increased concentrations of polycyclic aromatic compounds (PACs) and heavy metals in aquatic systems located near surface mining operations. In the present study, sediment cores were collected from 3 lakes with varying proximity to surface mining operations to determine the differences in PAC concentrations. Sediment cores were separated into 2 sections-current mining (top; 2000-2017) and premining (bottom; pre-1945)-and extracts were prepared for in vitro screening using a well-established chicken embryonic hepatocyte (CEH) assay. Concentrations and composition of PACs varied between sites, with the highest ∑PACs in Saline Lake, 5 km from an active oil sands mine site. The proportion of alkylated PACs was greater than that of parent PACs in the top sediment sections compared with the bottom. Ethoxyresorufin-O-deethylase activity in CEH permitted the ranking of lake sites/core sections based on an aryl hydrocarbon receptor-mediated end point; mean median effect concentration values were lowest for the top cores from Saline Lake and another near-mining operations lake, referred to as WF1. A ToxChip polymerase chain reaction (PCR) array was used to evaluate gene expression changes across 43 target genes associated with numerous toxicological pathways following exposure to top and bottom sediment core extracts. The 2 study sites with the greatest ∑PAC concentrations (Saline Lake and WF1) had the highest gene expression alterations on the ToxChip PCR array (19 [top] and 17 [bottom]/43), compared with a reference site (13 [top] and 7 [bottom]/43). The avian in vitro bioassay was useful for identifying the toxicity of complex PAC extracts associated with variably contaminated sediment cores, supporting its potential use for hotspot identification and complex mixture screening. EnvironToxicol Chem 2021;40:1883-1893. © 2021 SETAC.
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Affiliation(s)
| | - Kim L Williams
- Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, Ottawa, Ontario, Canada
| | - Suzanne Chiu
- Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, Ottawa, Ontario, Canada
| | - David C Eickmeyer
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Linda E Kimpe
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Jules M Blais
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Doug Crump
- Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, Ottawa, Ontario, Canada
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Cheng J, Cheng A, Clifford BL, Wu X, Hedin U, Maegdefessel L, Pamir N, Sallam T, Tarling EJ, de Aguiar Vallim TQ. MicroRNA-144 Silencing Protects Against Atherosclerosis in Male, but Not Female Mice. Arterioscler Thromb Vasc Biol 2020; 40:412-425. [PMID: 31852219 PMCID: PMC7018399 DOI: 10.1161/atvbaha.119.313633] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 11/15/2019] [Indexed: 12/18/2022]
Abstract
OBJECTIVE Atherosclerosis is a leading cause of death in developed countries. MicroRNAs act as fine-tuners of gene expression and have been shown to have important roles in the pathophysiology and progression of atherosclerosis. We, and others, previously demonstrated that microRNA-144 (miR-144) functions to post-transcriptionally regulate ABCA1 (ATP binding cassette transporter A1) and plasma HDL (high-density lipoprotein) cholesterol levels. Here, we explore how miR-144 inhibition may protect against atherosclerosis. Approach and Results: We demonstrate that miR-144 silencing reduced atherosclerosis in male, but not female low-density lipoprotein receptor null (Ldlr-/-) mice. MiR-144 antagonism increased circulating HDL cholesterol levels, remodeled the HDL particle, and enhanced reverse cholesterol transport. Notably, the effects on HDL and reverse cholesterol transport were more pronounced in male mice suggesting sex-specific differences may contribute to the effects of silencing miR-144 on atherosclerosis. As a molecular mechanism, we identify the oxysterol metabolizing enzyme CYP7B1 (cytochrome P450 enzyme 7B1) as a miR-144 regulated gene in male, but not female mice. Consistent with miR-144-dependent changes in CYP7B1 activity, we show decreased levels of 27-hydroxycholesterol, a known proatherogenic sterol and the endogenous substrate for CYP7B1 in male, but not female mice. CONCLUSIONS Our data demonstrate silencing miR-144 has sex-specific effects and that treatment with antisense oligonucleotides to target miR-144 might result in enhancements in reverse cholesterol transport and oxysterol metabolism in patients with cardiovascular disease.
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Affiliation(s)
- Joan Cheng
- Department of Biological Chemistry, University of California Los Angeles, California, 90095, USA
| | - Angela Cheng
- Department of Biological Chemistry, University of California Los Angeles, California, 90095, USA
| | - Bethan L. Clifford
- Department of Medicine, University of California Los Angeles, California, 90095, USA
| | - Xiaohui Wu
- Department of Medicine, University of California Los Angeles, California, 90095, USA
| | - Ulf Hedin
- Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden
| | - Lars Maegdefessel
- Department of Medicine, Karolinska Institute, Stockholm, Sweden
- Department of Vascular and Endovascular Surgery, Klinikum rechts der Isar – Technical University Munich, Munich, Germany
| | - Nathalie Pamir
- Department of Medicine, Knight Cardiovascular Institute, Oregon Health & Sciences University, Portland, Oregon, USA
| | - Tamer Sallam
- Department of Medicine, University of California Los Angeles, California, 90095, USA
- Molecular Biology Institute, University of California Los Angeles, California, 90095, USA
| | - Elizabeth J. Tarling
- Department of Medicine, University of California Los Angeles, California, 90095, USA
- Molecular Biology Institute, University of California Los Angeles, California, 90095, USA
- Johnsson Comprehensive Cancer Center, University of California Los Angeles, California, 90095, USA
| | - Thomas Q. de Aguiar Vallim
- Department of Biological Chemistry, University of California Los Angeles, California, 90095, USA
- Department of Medicine, University of California Los Angeles, California, 90095, USA
- Molecular Biology Institute, University of California Los Angeles, California, 90095, USA
- Johnsson Comprehensive Cancer Center, University of California Los Angeles, California, 90095, USA
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Hajeyah AA, Griffiths WJ, Wang Y, Finch AJ, O’Donnell VB. The Biosynthesis of Enzymatically Oxidized Lipids. Front Endocrinol (Lausanne) 2020; 11:591819. [PMID: 33329396 PMCID: PMC7711093 DOI: 10.3389/fendo.2020.591819] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 10/26/2020] [Indexed: 12/14/2022] Open
Abstract
Enzymatically oxidized lipids are a specific group of biomolecules that function as key signaling mediators and hormones, regulating various cellular and physiological processes from metabolism and cell death to inflammation and the immune response. They are broadly categorized as either polyunsaturated fatty acid (PUFA) containing (free acid oxygenated PUFA "oxylipins", endocannabinoids, oxidized phospholipids) or cholesterol derivatives (oxysterols, steroid hormones, and bile acids). Their biosynthesis is accomplished by families of enzymes that include lipoxygenases (LOX), cyclooxygenases (COX), cytochrome P450s (CYP), and aldo-keto reductases (AKR). In contrast, non-enzymatically oxidized lipids are produced by uncontrolled oxidation and are broadly considered to be harmful. Here, we provide an overview of the biochemistry and enzymology of LOXs, COXs, CYPs, and AKRs in humans. Next, we present biosynthetic pathways for oxylipins, oxidized phospholipids, oxysterols, bile acids and steroid hormones. Last, we address gaps in knowledge and suggest directions for future work.
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Affiliation(s)
- Ali A. Hajeyah
- Systems Immunity Research Institute and Division of Infection and Immunity, Cardiff University, Cardiff, United Kingdom
- *Correspondence: Ali A. Hajeyah,
| | - William J. Griffiths
- Institute of Life Science, Swansea University Medical School, Swansea, United Kingdom
| | - Yuqin Wang
- Institute of Life Science, Swansea University Medical School, Swansea, United Kingdom
| | - Andrew J. Finch
- Centre for Tumour Biology, Barts Cancer Institute, Queen Mary University of London, London, United Kingdom
| | - Valerie B. O’Donnell
- Systems Immunity Research Institute and Division of Infection and Immunity, Cardiff University, Cardiff, United Kingdom
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Pandak WM, Kakiyama G. The acidic pathway of bile acid synthesis: Not just an alternative pathway ☆. LIVER RESEARCH 2019; 3:88-98. [PMID: 32015930 PMCID: PMC6996149 DOI: 10.1016/j.livres.2019.05.001] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Over the last two decades, the prevalence of obesity, and metabolic syndromes (MS) such as non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM), have dramatically increased. Bile acids play a major role in the digestion, absorption of nutrients, and the body's redistribution of absorbed lipids as a function of their chemistry and signaling properties. As a result, a renewed interest has developed in the bile acid metabolic pathways with the challenge of gaining insight into novel treatment approaches for this rapidly growing healthcare problem. Of the two major pathways of bile acid synthesis in the liver, the foremost role of the acidic (alternative) pathway is to generate and control the levels of regulatory oxysterols that help control cellular cholesterol and lipid homeostasis. Cholesterol transport to mitochondrial sterol 27-hydroxylase (CYP27A1) by steroidogenic acute regulatory protein (StarD1), and the subsequent 7α-hydroxylation of oxysterols by oxysterol 7α-hydroxylase (CYP7B1) are the key regulatory steps of the pathway. Recent observations suggest CYP7B1 to be the ultimate controller of cellular oxysterol levels. This review discusses the acidic pathway and its contribution to lipid, cholesterol, carbohydrate, and energy homeostasis. Additionally, discussed is how the acidic pathway's dysregulation not only leads to a loss in its ability to control cellular cholesterol and lipid homeostasis, but leads to inflammatory conditions.
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Affiliation(s)
- William M. Pandak
- Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA, USA,Department of Veterans Affairs, Richmond, VA, USA
| | - Genta Kakiyama
- Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA, USA,Department of Veterans Affairs, Richmond, VA, USA,Corresponding author. Department of Internal Medicine, Virginia Commonwealth University and Department of Veterans Affairs, Richmond, VA, USA. (G. Kakiyama)
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Meljon A, Crick PJ, Yutuc E, Yau JL, Seckl JR, Theofilopoulos S, Arenas E, Wang Y, Griffiths WJ. Mining for Oxysterols in Cyp7b1-/- Mouse Brain and Plasma: Relevance to Spastic Paraplegia Type 5. Biomolecules 2019; 9:biom9040149. [PMID: 31013940 PMCID: PMC6523844 DOI: 10.3390/biom9040149] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 03/28/2019] [Accepted: 04/02/2019] [Indexed: 01/19/2023] Open
Abstract
Deficiency in cytochrome P450 (CYP) 7B1, also known as oxysterol 7α-hydroxylase, in humans leads to hereditary spastic paraplegia type 5 (SPG5) and in some cases in infants to liver disease. SPG5 is medically characterized by loss of motor neurons in the corticospinal tract. In an effort to gain a better understanding of the fundamental biochemistry of this disorder, we have extended our previous profiling of the oxysterol content of brain and plasma of Cyp7b1 knockout (-/-) mice to include, amongst other sterols, 25-hydroxylated cholesterol metabolites. Although brain cholesterol levels do not differ between wild-type (wt) and knockout mice, we find, using a charge-tagging methodology in combination with liquid chromatography-mass spectrometry (LC-MS) and multistage fragmentation (MSn), that there is a build-up of the CYP7B1 substrate 25-hydroxycholesterol (25-HC) in Cyp7b1-/- mouse brain and plasma. As reported earlier, levels of (25R)26-hydroxycholesterol (26-HC), 3β-hydroxycholest-5-en-(25R)26-oic acid and 24S,25-epoxycholesterol (24S,25-EC) are similarly elevated in brain and plasma. Side-chain oxysterols including 25-HC, 26-HC and 24S,25-EC are known to bind to INSIG (insulin-induced gene) and inhibit the processing of SREBP-2 (sterol regulatory element-binding protein-2) to its active form as a master regulator of cholesterol biosynthesis. We suggest the concentration of cholesterol in brain of the Cyp7b1-/- mouse is maintained by balancing reduced metabolism, as a consequence of a loss in CYP7B1, with reduced biosynthesis. The Cyp7b1-/- mouse does not show a motor defect; whether the defect in humans is a consequence of less efficient homeostasis of cholesterol in brain has yet to be uncovered.
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Affiliation(s)
- Anna Meljon
- Swansea University Medical School, ILS1 Building, Singleton Park, Swansea SA2 8PP, UK.
- Institute for Global Food Security, Queens University Belfast, Stranmillis Road, Belfast BT9 5AG, UK.
| | - Peter J Crick
- Swansea University Medical School, ILS1 Building, Singleton Park, Swansea SA2 8PP, UK.
| | - Eylan Yutuc
- Swansea University Medical School, ILS1 Building, Singleton Park, Swansea SA2 8PP, UK.
| | - Joyce L Yau
- Endocrinology Unit, BHF Centre for Cardiovascular Science, The Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.
| | - Jonathan R Seckl
- Endocrinology Unit, BHF Centre for Cardiovascular Science, The Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, UK.
| | - Spyridon Theofilopoulos
- Swansea University Medical School, ILS1 Building, Singleton Park, Swansea SA2 8PP, UK.
- Laboratory of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden.
| | - Ernest Arenas
- Laboratory of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-17177 Stockholm, Sweden.
| | - Yuqin Wang
- Swansea University Medical School, ILS1 Building, Singleton Park, Swansea SA2 8PP, UK.
| | - William J Griffiths
- Swansea University Medical School, ILS1 Building, Singleton Park, Swansea SA2 8PP, UK.
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Qrafli M, Najimi M, Elaouad R, Sadki K. Current immunogenetic predisposition to tuberculosis in the Moroccan population. Int J Immunogenet 2017; 44:286-304. [PMID: 29057608 DOI: 10.1111/iji.12340] [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: 04/04/2017] [Revised: 08/06/2017] [Accepted: 08/27/2017] [Indexed: 11/30/2022]
Abstract
Tuberculosis (TB) is a serious infectious disease that kills approximately two million people per year, particularly in low- and middle-income countries. Numerous genetic epidemiology studies have been conducted of many ethnic groups worldwide and have highlighted the critical impact of the genetic environment on TB distribution. Many candidate genes associated with resistance or susceptibility to TB have been identified. In Morocco, where TB is still a major public health problem, various observations of clinical, microbiological and incidence distribution are heavily affected by genetic background and external environment. Morocco has almost the same clinical profile as do other North African countries, mainly the increase in more extrapulmonary than pulmonary forms of the diseases, when compared to European, Asian or American populations. In addition, a linkage analysis study that examined Moroccan TB patients identified a unique chromosome region that had a strong association with the risk of contracting TB. Other genes in the Moroccan population that were found to be associated seem to be involved predominantly in modulating the innate immunity. In this review, we appraise the major candidate genes that have been reported in Moroccan immunogenetic studies and discuss their updated role in TB, particularly during the first phase of the immune response to Mycobacterium tuberculosis (Mtb) infection.
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Affiliation(s)
- M Qrafli
- Physiopathology Team, Immunogenomic and Bioinformatic Unit, Faculty of Sciences, Genomic Center of Human Pathologies, Mohammed V University, Rabat, Morocco
| | - M Najimi
- Laboratory of Pediatric Hepatology and Cell Therapy, Institut de Recherche Expérimentale et Clinique (IREC), Université Catholique de Louvain, Brussels, Belgium
| | - R Elaouad
- School of Medicine and Pharmacy Sciences, Mohammed V University of Rabat, Rabat, Morocco
| | - K Sadki
- Physiopathology Team, Immunogenomic and Bioinformatic Unit, Faculty of Sciences, Genomic Center of Human Pathologies, Mohammed V University, Rabat, Morocco
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Li M, Xue S, Tan S, Qin X, Gu M, Wang D, Zhang Y, Guo L, Huang F, Yao Y, Zhou Z, Fan S, Huang C. Crabapple fruit extracts lower hypercholesterolaemia in high-fat diet-induced obese mice. J Funct Foods 2016. [DOI: 10.1016/j.jff.2016.09.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Abstract
Leptin, a 167 amino acid adipokine, plays a major role in human energy homeostasis. Its actions are mediated through binding to leptin receptor and activating JAK-STAT3 signal transduction pathway. It is expressed mainly in adipocytes, and its circulating levels reflect the body's energy stores in adipose tissue. Recombinant methionyl human leptin has been FDA approved for patients with generalized non-HIV lipodystrophy and for compassionate use in subjects with congenital leptin deficiency. The purpose of this review is to outline the role of leptin in energy homeostasis, as well as its interaction with other hormones.
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Affiliation(s)
- Georgios A Triantafyllou
- Division of Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, ST 820, Boston, MA 02215, USA
| | - Stavroula A Paschou
- Division of Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, ST 820, Boston, MA 02215, USA
| | - Christos S Mantzoros
- Division of Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, ST 820, Boston, MA 02215, USA.
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11
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Yuan ZQ, Li KW. Role of farnesoid X receptor in cholestasis. J Dig Dis 2016; 17:501-509. [PMID: 27383832 DOI: 10.1111/1751-2980.12378] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 06/23/2016] [Accepted: 07/03/2016] [Indexed: 12/11/2022]
Abstract
The nuclear receptor farnesoid X receptor (FXR) plays an important role in physiological bile acid synthesis, secretion and transport. Defects of FXR regulation in these processes can cause cholestasis and subsequent pathological changes. FXR regulates the synthesis and uptake of bile acid via enzymes. It also increases bile acid solubility and elimination by promoting conjugation reactions and exports pump expression in cholestasis. The changes in bile acid transporters are involved in cholestasis, which can result from the mutations of transporter genes or acquired dysfunction of transport systems, such as inflammation-induced intrahepatic cholestasis. The modulation function of FXR in extrahepatic cholestasis is not identical to that in intrahepatic cholestasis, but the discrepancy may be reduced over time. In extrahepatic cholestasis, increasing biliary pressure can induce bile duct proliferation and bile infarcts, but the absence of FXR may ameliorate them. This review provides an update on the function of FXR in the regulation of bile acid metabolism, its role in the pathophysiological process of cholestasis and the therapeutic use of FXR agonists.
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Affiliation(s)
- Zhi Qing Yuan
- Department of Biliary-Pancreatic Surgery, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Ke Wei Li
- Department of Biliary-Pancreatic Surgery, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China.
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Crump D, Williams KL, Chiu S, Letcher RJ, Periard L, Kennedy SW. Biochemical and Transcriptomic Effects of Herring Gull Egg Extracts from Variably Contaminated Colonies of the Laurentian Great Lakes in Chicken Hepatocytes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:10190-10198. [PMID: 26192021 DOI: 10.1021/acs.est.5b02745] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Determining the effects of complex mixtures of environmental contaminants poses many challenges within the field of ecotoxicology. In this study, graded concentrations of herring gull egg extracts, collected from five Great Lakes breeding colonies with variable burdens of organohalogen contaminants (OHCs), were administered to chicken embryonic hepatocytes to determine effects on 7-ethoxyresorufin-O-deethylase (EROD) activity, porphyrin accumulation, and mRNA expression. EROD activity and porphyrin accumulation permitted the ranking of colonies based on the efficacy of eliciting an aryl hydrocarbon receptor-mediated response. An avian ToxChip polymerase chain reaction (PCR) array provided more exhaustive coverage in terms of potential toxicity pathways being affected, including xenobiotic and lipid metabolism and the thyroid hormone pathway. Herring gull eggs from Channel Shelter Island (CHSH, Lake Huron) and Gull Island (GULL, Lake Michigan) had among the highest OHC burdens, and extracts elicited a biochemical and transcriptomic response greater than that of extracts from the other three, less polluted colonies. For example, EROD EC50 values and porphyrin ECthreshold values were lower for CHSH and GULL extracts than for the other colonies. Extracts from CHSH and GULL altered 15 and 13 of 27 genes on the PCR array compared to no more than eight genes for the less contaminated sites. The combination of a well-established avian in vitro assay, two well-characterized biochemical assays, and the avian ToxChip PCR array permitted the geographical discrimination of variably contaminated herring gull eggs from the Great Lakes. Such high-throughput assays show potential promise as cost-effective tools for determining toxic potencies of complex mixtures in the environment.
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Affiliation(s)
- Doug Crump
- †Ecotoxicology and Wildlife Health Division, Environment Canada, National Wildlife Research Centre, Carleton University, Ottawa, ON, Canada K1A 0H3
| | - Kim L Williams
- †Ecotoxicology and Wildlife Health Division, Environment Canada, National Wildlife Research Centre, Carleton University, Ottawa, ON, Canada K1A 0H3
| | - Suzanne Chiu
- †Ecotoxicology and Wildlife Health Division, Environment Canada, National Wildlife Research Centre, Carleton University, Ottawa, ON, Canada K1A 0H3
| | - Robert J Letcher
- †Ecotoxicology and Wildlife Health Division, Environment Canada, National Wildlife Research Centre, Carleton University, Ottawa, ON, Canada K1A 0H3
| | - Luke Periard
- †Ecotoxicology and Wildlife Health Division, Environment Canada, National Wildlife Research Centre, Carleton University, Ottawa, ON, Canada K1A 0H3
| | - Sean W Kennedy
- †Ecotoxicology and Wildlife Health Division, Environment Canada, National Wildlife Research Centre, Carleton University, Ottawa, ON, Canada K1A 0H3
- ‡Department of Biology, University of Ottawa, Ottawa, ON, Canada K1N 6N5
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Qrafli M, Amar Y, Bourkadi J, Ben Amor J, Iraki G, Bakri Y, Amzazi S, Lahlou O, Seghrouchni F, El Aouad R, Sadki K. The CYP7A1 gene rs3808607 variant is associated with susceptibility of tuberculosis in Moroccan population. Pan Afr Med J 2014; 18:1. [PMID: 25360185 PMCID: PMC4212432 DOI: 10.11604/pamj.2014.18.1.3397] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 04/22/2014] [Indexed: 11/11/2022] Open
Abstract
Introduction Despite the medical progress in treatment. Tuberculosis (TB) continues to be a serious global health problem. A genome-wide linkage study identified a major susceptibility locus on chromosomal region 8q12-q13 in Moroccan TB patients. The CYP7A1 gene is located in this region and codes for cholesterol 7a-hydroxylase, an enzyme involved in cholesterol catabolism. Methods We selected three SNPs (rs3808607, rs8192875 and rs8192879) and studied their genotype and allele frequencies distribution in patients with pulmonary (PTB) or pleural TB (pTB), and compared them to Healthy Controls (HC). Genotyping of rs8192875 and rs8192879 SNPs was carried out using the Taq Man SNP genotyping Assay while rs3808607 was investigated by PCR-RFLP. Results We reported here for the first time a statistically significant increase in the AA homozygote genotype frequency of rs3808607 in PTB patients compared to HC (p = 0.02, OR = 1.93, 95% CI: 1.93 (1.07;3.49). The increased risk of developing TB was maintained when we combined the groups of patients (PTB-pTB) (p = 0.01, OR= 1.91, 95% CI = (1.07 - 3.42). In contrast, no genetic association was observed between the rs8192875 or rs8192879 polymorphisms and TB. Conclusion Our investigations suggest that rs3808607 may play a role in susceptibility to TB in a Moroccan population.
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Affiliation(s)
- Mounia Qrafli
- Laboratory of Human Genomic, National Institute of Hygiene, Rabat, Morocco ; Laboratory of Biochemistry and Immunology, Faculty of Sciences, University Mohammed V, Rabat, Morocco
| | - Youssef Amar
- Laboratory of Biochemistry and Immunology, Faculty of Sciences, University Mohammed V, Rabat, Morocco
| | | | - Jouda Ben Amor
- Department of Pneumophtisiology, Moulay Youssef Hospital, Rabat, Morocco
| | - Ghali Iraki
- Department of Pneumophtisiology, Moulay Youssef Hospital, Rabat, Morocco
| | - Youssef Bakri
- Laboratory of Biochemistry and Immunology, Faculty of Sciences, University Mohammed V, Rabat, Morocco
| | - Saaîd Amzazi
- Laboratory of Biochemistry and Immunology, Faculty of Sciences, University Mohammed V, Rabat, Morocco
| | - Ouafae Lahlou
- Laboratory of Human Genomic, National Institute of Hygiene, Rabat, Morocco
| | - Fouad Seghrouchni
- Laboratory of Human Genomic, National Institute of Hygiene, Rabat, Morocco
| | - Rajae El Aouad
- Laboratory of Human Genomic, National Institute of Hygiene, Rabat, Morocco
| | - Khalid Sadki
- Laboratory of Biochemistry and Immunology, Faculty of Sciences, University Mohammed V, Rabat, Morocco
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14
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Lan MY, Yeh TH, Chang YY, Kuo HC, Sun HS, Lai SC, Lu CS. Clinical and genetic analysis of Taiwanese patients with hereditary spastic paraplegia type 5. Eur J Neurol 2014; 22:211-4. [PMID: 24641183 DOI: 10.1111/ene.12407] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 02/07/2014] [Indexed: 01/28/2023]
Abstract
BACKGROUND AND PURPOSE Spastic paraplegia type 5 (SPG5) is an autosomal recessive (AR) hereditary spastic paraplegia (HSP) associated with pure or complicated phenotypes. This study aimed to screen SPG5 in Taiwanese HSP patients. METHODS Sequencing of the SPG5 gene, CYP7B1, was performed in a cohort of 25 ethnic Han Taiwanese patients with AR or sporadic HSP. Clinical information and magnetic resonance imaging (MRI) were analyzed in confirmed SPG5 patients. RESULTS One (33%) AR kindred and four (18%) sporadic cases had CYP7B1 mutations. All of the SPG5 cases carried the mutation c.334 C>T (R112X). Haplotype analysis suggested a 'founder effect' in ethnic Hans for this mutation. The phenotype was either pure or complicated by cerebellar ataxia. For the primary HSP phenotype, there were profound dorsal column sensory deficits in all patients. Spine MRI showed thoraco-lumbar cord atrophy in some patients. CONCLUSIONS Spastic paraplegia type 5 is a common cause of AR and sporadic HSPs that has a higher frequency in Taiwanese than in other ethnic groups. It is associated with a CYP7B1 founder mutation and its phenotype is characterized by pronounced dorsal column sensory loss, with cerebellar ataxia in some patients.
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Affiliation(s)
- M-Y Lan
- Center for Parkinson's Disease, Department of Neurology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan
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15
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Yantsevich AV, Dichenko YV, Mackenzie F, Mukha DV, Baranovsky AV, Gilep AA, Usanov SA, Strushkevich NV. Human steroid and oxysterol 7α-hydroxylase CYP7B1: substrate specificity, azole binding and misfolding of clinically relevant mutants. FEBS J 2014; 281:1700-13. [PMID: 24491228 DOI: 10.1111/febs.12733] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 12/23/2013] [Accepted: 01/28/2014] [Indexed: 11/28/2022]
Abstract
Oxysterols and neurosteroids are important signaling molecules produced by monooxygenases of the cytochrome P450 family that realize their effect through nuclear receptors. CYP7B1 catalyzes the 6- or 7-hydroxylation of both steroids and oxysterols and thus is involved in the metabolism of neurosteroids and bile acid synthesis, respectively. The dual physiological role of CYP7B1 is evidenced from different diseases, liver failure and progressive neuropathy, caused by enzyme malfunction. Here we present biochemical characterization of CYP7B1 at the molecular level to understand substrate specificity and susceptibility to azole drugs. Based on our experiments with purified enzyme, the requirements for CYP7B1 hydroxylation of steroid molecules are as follows: C5 hydrogen in the α-configuration (or double bond at C5), a polar group at C17, a hydroxyl group at C3, and the absence of the hydroxyl group at C20-C24 in the C27-sterol side chain. 21-hydroxy-pregnenolone was identified as a new substrate, and overall low activity toward pregnanes could be related to the increased potency of 7-hydroxy derivatives produced by CYP7B1. Metabolic conversion (deactivation) of oxysterols by CYP7B1 in a reconstituted system proceeds via two sequential hydroxylations. Two mutations that are found in patients with diseases, Gly57Arg and Phe216Ser, result in apo-P450 (devoid of heme) protein formation. Our CYP7B1 homology model provides a rationale for understanding clinical mutations and relatively broad substrate specificity for steroid hydroxylase.
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Bertolotti M, Crosignani A, Del Puppo M. The use of stable and radioactive sterol tracers as a tool to investigate cholesterol degradation to bile acids in humans in vivo. Molecules 2012; 17:1939-68. [PMID: 22343367 PMCID: PMC6268360 DOI: 10.3390/molecules17021939] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 02/03/2012] [Accepted: 02/08/2012] [Indexed: 12/17/2022] Open
Abstract
Alterations of cholesterol homeostasis represent important risk factors for atherosclerosis and cardiovascular disease. Different clinical-experimental approaches have been devised to study the metabolism of cholesterol and particularly the synthesis of bile acids, its main catabolic products. Most evidence in humans has derived from studies utilizing the administration of labeled sterols; these have several advantages over in vitro assay of enzyme activity and expression, requiring an invasive procedure such as a liver biopsy, or the determination of fecal sterols, which is cumbersome and not commonly available. Pioneering evidence with administration of radioactive sterol derivatives has allowed to characterize the alterations of cholesterol metabolism and degradation in different situations, including spontaneous disease conditions, aging, and drug treatment. Along with the classical isotope dilution methodology, other approaches were proposed, among which isotope release following radioactive substrate administration. More recently, stable isotope studies have allowed to overcome radioactivity exposure. Isotope enrichment studies during tracer infusion has allowed to characterize changes in the degradation of cholesterol via the "classical" and the "alternative" pathways of bile acid synthesis. Evidence brought by tracer studies in vivo, summarized here, provides an exceptional tool for the investigation of sterol metabolism, and integrate the studies in vitro on human tissue.
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Affiliation(s)
- Marco Bertolotti
- Divisone di Geriatria, Dipartimento di Medicina, Endocrinologia, Metabolismo e Geriatria, Università degli Studi di Modena e Reggio Emilia, Nuovo Ospedale Civile, Via Giardini 1355, Modena 41126, Italy.
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17
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Baik M, Yu JH, Hennighausen L. Growth hormone-STAT5 regulation of growth, hepatocellular carcinoma, and liver metabolism. Ann N Y Acad Sci 2011; 1229:29-37. [PMID: 21793836 PMCID: PMC3427656 DOI: 10.1111/j.1749-6632.2011.06100.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The liver is a primary target of growth hormone (GH). GH signals are mediated by the transcription factor signal transducer and activator of transcription 5 (STAT5). Here, we focus on recent discoveries about the role of GH-STAT5 signaling in hepatic physiology and pathophysiology. We discuss roles of the GH-STAT5 axis in body growth, lipid metabolism, and the cell cycle pertaining to hepatosteatosis, fibrosis, and hepatocellular carcinoma. Finally, we discuss recent discoveries about the role of GH-STAT5 in sex-specific gene expression and bile acid, steroid, and drug metabolism.
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Affiliation(s)
- Myunggi Baik
- Deptartment of Molecular Biotechnology, WCU-RNNM, Chonnam National University, Gwangju, Republic of Korea
| | - Ji Hoon Yu
- Laboratory of Genetics and Physiology, National Institutes of Health, Bethesda, Maryland
| | - Lothar Hennighausen
- Laboratory of Genetics and Physiology, National Institutes of Health, Bethesda, Maryland
- Deptartment of Molecular Biotechnology, WCU-RNNM, Chonnam National University, Gwangju, Republic of Korea
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18
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Salamanca-Pinzón SG, Guengerich FP. A tricistronic human adrenodoxin reductase-adrenodoxin-cytochrome P450 27A1 vector system for substrate hydroxylation in Escherichia coli. Protein Expr Purif 2011; 79:231-6. [PMID: 21621619 DOI: 10.1016/j.pep.2011.05.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2011] [Revised: 05/11/2011] [Accepted: 05/12/2011] [Indexed: 01/01/2023]
Abstract
Cytochrome P450 (P450) 27A1 catalyzes 27-hydroxylation of cholesterol and 25-hydroxylation of vitamin D(3), serving as an important component for the maintenance of lipid homeostasis. In eukaryotic cells P450 27A1 is a membrane-bound protein located on the inner mitochondrial membrane and requires two auxiliary reduction partners, adrenodoxin (Adx) and NADPH-adrenodoxin reductase (Adr), for catalysis in the bile acid biosynthesis pathway. A strategy was developed for the functional coexpression of P450 27A1 with Adr and Adx in a tricistronic fashion (single RNA, three proteins) in Escherichia coli, mimicking the mitochondrial P450 system. Intact bacterial cells coexpressing the P450 vector (pTC27A1) efficiently hydroxylated cholesterol at the 27 position as well as vitamin D(3) at the 25 position when supplemented with glycerol as a carbon source. Thus, E. coli containing pTC27A1 is able to hydroxylate cholesterol in a self-sufficient fashion and is suitable for further applications of protein interaction, drug discovery, and inhibitor evaluation and for the study of other mitochondrial P450s and oxysterol production in microorganisms without a need for membrane reconstitution, membrane simulation by detergents, or purification of the components.
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Affiliation(s)
- S Giovanna Salamanca-Pinzón
- Department of Biochemistry and Center in Molecular Toxicology, Vanderbilt University School of Medicine, Nashville, TN 37232-0146, USA
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19
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Zhao AY, Wang XD, Chen GH, Lu LZ. Low-level expression of cholesterol 7 α-hydroxylase is associated with the formation of goose fatty liver. Poult Sci 2011; 90:1045-9. [PMID: 21489953 DOI: 10.3382/ps.2010-01207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cholesterol 7α-hydroxylase (Cyp7a1) plays a crucial role in the synthesis of cholic acid and cholesterol catabolism. In this study, Cyp7a1 expression in goose liver was identified for the first time using differential display reverse transcription PCR. This study used real-time PCR and quantified the transcript levels of the cyp7a1 gene under different feeding conditions. In overfeeding, cyp7a1 expression by the liver was lower than that seen for normal feeding and the same result was observed for the Cyp7a1 protein level. The cholesterol level in serum and liver was higher in the overfed group. This study suggests that low-level expression of Cyp7a1 is associated with the formation of goose fatty liver.
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Affiliation(s)
- A Y Zhao
- College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu 225009, People's Republic of China
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20
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Park K, Scott AL. Cholesterol 25-hydroxylase production by dendritic cells and macrophages is regulated by type I interferons. J Leukoc Biol 2010; 88:1081-7. [PMID: 20699362 DOI: 10.1189/jlb.0610318] [Citation(s) in RCA: 187] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The oxysterol-producing enzyme CH25H plays an important role in regulating lipid metabolism, gene expression, and immune activation. In vitro experiments using a panel of TLR agonists to activate BMDCs and macrophages demonstrated that Ch25h expression is induced rapidly, selectively, and robustly by the TLR ligands poly I:C and LPS. The mechanism of TLR3- and TLR4-induced transcription levels of Ch25h relies on the TRIF-mediated production of type I IFNs and requires signaling through the IFNαR and JAK/STAT1 pathway. Treatment of BMDCs and macrophages with IFN-α or IFN-β induces Ch25h in a STAT1-dependent manner. IFN-γ also up-regulated Ch25h expression by signaling through STAT1, suggesting that multiple pathways regulate the production of this enzyme. In addition, we demonstrated that regulation of Ch25h expression in vivo in lung-derived DCs and macrophages is dependent on signaling through the IFNαR and STAT1. The results suggest that the rapid induction of Ch25h and subsequent oxysterol synthesis may represent a component of the regulatory network that modulates the magnitude of innate immune reactions and possibly the nature and intensity of subsequent adaptive responses.
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Affiliation(s)
- Kiwon Park
- The W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
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21
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Nishiura H, Kimura A, Yamato Y, Aoki K, Inokuchi T, Kurosawa T, Matsuishi T. Developmental pattern of urinary bile acid profile in preterm infants. Pediatr Int 2010; 52:44-50. [PMID: 19460125 DOI: 10.1111/j.1442-200x.2009.02887.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
BACKGROUND Bile acid metabolism in preterm infants is yet to be fully characterized. We compared the developmental pattern of urinary bile acid profiles in ten infants born at gestational ages from 25 to 33 weeks with previous data from full-term infants from birth to about 7 months of age. METHODS Gas chromatography-mass spectrometry was performed on serial samples. RESULTS Total urinary bile acid concentrations gradually increased until 1 to 2 months of age. After this peak of excretion (30 to 60 micromol/mmol creatinine), total urinary bile acid concentrations gradually decreased to less than 20 micromol/mmol creatinine. The percentage of usual bile acids (mainly cholic acid) relative to total urinary total bile acids gradually deceased from approximately 30% at birth to less than 15% at 7 months of age. On the other hand, 1beta-hydroxylated bile acids (mainly 1beta,3alpha,7alpha,12alpha-tetrahydroxy-5beta-cholan-24-oic acid) relative to total urinary bile acids were increased gradually from 60% at birth to reach 70% to 80% at 1 month of age. The percentage of 1beta-hydroxylated bile acids relative to total urinary bile acids then remained stable at a high percentage (70% to 90%) until the age of 7 months. CONCLUSION Physiological cholestasis in preterm infants persists longer than in full-term infants. Moreover, as large amounts of cholic and 1beta,3alpha,7alpha,12alpha-tetrahydroxy-5beta-cholan-24-oic acids were detected in urine from preterm infants during this study, the 25-hydroxylation pathway may be particularly important for bile acid synthesis in early preterm infants.
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Affiliation(s)
- Hiroshi Nishiura
- Department of Pediatrics and Child Health, Kurume University School of Medicine, Kurume, Fukuoka, Japan
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Abstract
Cholesterol and other cholesterol related metabolites, oxysterols, and bile acids, establish specific interactions with enzymes and other proteins involved in cholesterol and bile acid homeostasis, triggering a variety of biological responses. The substrate-enzyme binding represents the best-characterized type of complementary interaction between proteins and small molecules. Key enzymes in the pathway that converts cholesterol to bile acids belong to the cytochrome P450 superfamily. In contrast to the majority of P450 enzymes, those acting on cholesterol and related metabolites exhibit higher stringency with respect to substrate molecules. This stringency, coupled with the specificity of the reactions, dictates the chemical features of intermediate metabolites (oxysterols) and end products (bile acids). Both oxysterols and bile acids have emerged in recent years as new signalling molecules due to their ability to interact and activate nuclear receptors, and consequently to regulate the transcription of genes involved in cholesterol and bile acid homeostasis and metabolism, but also in glucose and fatty acid metabolism. Interestingly, other proteins function as bile acid or sterol receptors. New findings indicate that bile acids also interact with a membrane G protein-coupled receptor, triggering a signalling cascade that ultimately promote energy expenditure. On the other end, cholesterol and side chain oxysterols establish specific interactions with different proteins residing in the endoplasmic reticulum that result in controlled protein degradation and/or trafficking to the Golgi and the nucleus. These regulatory pathways converge and contribute to adapt cholesterol uptake and synthesis to the cellular needs.
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Garenc C, Julien P, Levy E. Oxysterols in biological systems: The gastrointestinal tract, liver, vascular wall and central nervous system. Free Radic Res 2009; 44:47-73. [DOI: 10.3109/10715760903321804] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Alnouti Y. Bile Acid sulfation: a pathway of bile acid elimination and detoxification. Toxicol Sci 2009; 108:225-46. [PMID: 19131563 DOI: 10.1093/toxsci/kfn268] [Citation(s) in RCA: 293] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Sulfotransferase-2A1 catalyzes the formation of bile acid-sulfates (BA-sulfates). Sulfation of BAs increases their solubility, decreases their intestinal absorption, and enhances their fecal and urinary excretion. BA-sulfates are also less toxic than their unsulfated counterparts. Therefore, sulfation is an important detoxification pathway of BAs. Major species differences in BA sulfation exist. In humans, only a small proportion of BAs in bile and serum are sulfated, whereas more than 70% of BAs in urine are sulfated, indicating their efficient elimination in urine. The formation of BA-sulfates increases during cholestatic diseases. Therefore, sulfation may play an important role in maintaining BA homeostasis under pathologic conditions. Farnesoid X receptor, pregnane X receptor, constitutive androstane receptor, and vitamin D receptor are potential nuclear receptors that may be involved in the regulation of BA sulfation. This review highlights current knowledge about the enzymes and transporters involved in the formation and elimination of BA-sulfates, the effect of sulfation on the pharmacologic and toxicologic properties of BAs, the role of BA sulfation in cholestatic diseases, and the regulation of BA sulfation.
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Affiliation(s)
- Yazen Alnouti
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska 68198, USA
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Wada T, Kang HS, Jetten AM, Xie W. The emerging role of nuclear receptor RORalpha and its crosstalk with LXR in xeno- and endobiotic gene regulation. Exp Biol Med (Maywood) 2008; 233:1191-201. [PMID: 18535165 PMCID: PMC2658633 DOI: 10.3181/0802-mr-50] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Retinoid-related orphan receptors (RORs), including the alpha, beta and gamma isoforms (NR1F1-3), are orphan nuclear receptors that have been implicated in tissue development, immune responses, and circadian rhythm. Although RORalpha and RORgamma have been shown to be expressed in the liver, the hepatic function of these two RORs remains unknown. We have recently shown that loss of RORalpha and/or RORgamma can positively or negatively influence the expression of multiple Phase I and Phase II drug metabolizing enzymes and transporters in the liver. Among ROR responsive genes, we identified oxysterol 7alpha-hydroxylase (Cyp7b1), which plays a critical role in the homeostasis of cholesterol, as a RORalpha target gene. We showed that RORalpha is both necessary and sufficient for Cyp7b1 activation. Studies of mice deficient of RORalpha or liver X receptors (LXRs) revealed an interesting and potentially important functional crosstalk between RORalpha and LXR. The respective activation of LXR target genes and ROR target genes in RORalpha null mice and LXR null mice led to our hypothesis that these two receptors are mutually suppressive in vivo. LXRs have been shown to regulate a battery of metabolic genes. We conclude that RORs participate in the xeno- and endobiotic regulatory network by regulating gene expression directly or through crosstalk with LXR, which may have broad implications in metabolic homeostasis.
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Affiliation(s)
- Taira Wada
- Center for Pharmacogenetics and Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA 15261
| | - Hong Soon Kang
- Cell Biology Section, Division of Intramural Research, The National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709
| | - Anton M. Jetten
- Cell Biology Section, Division of Intramural Research, The National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709
| | - Wen Xie
- Center for Pharmacogenetics and Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA 15261
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Griffiths WJ, Hornshaw M, Woffendin G, Baker SF, Lockhart A, Heidelberger S, Gustafsson M, Sjövall J, Wang Y. Discovering oxysterols in plasma: a window on the metabolome. J Proteome Res 2008; 7:3602-12. [PMID: 18605750 DOI: 10.1021/pr8001639] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
While the proteome defines the expressed gene products, the metabolome results from reactions controlled by such gene products. Plasma represents an accessible "window" to the metabolome both in regard of availability and content. The wide range of the plasma metabolome, in terms of molecular diversity and abundance, makes its comprehensive analysis challenging. Here we demonstrate an analytical method designed to target one region of the metabolome, that is, oxysterols. Since the discovery of their biological activity as ligands to nuclear receptors there has been a reawakening of interest in oxysterols and their analysis. In addition, the oxysterols, 24S- and 27-hydroxycholesterol, are currently under investigation as potential biomarkers associated with neurodegenerative disorders such as Alzheimer's disease and multiple sclerosis; widespread analysis of these lipids in clinical studies will require the development of robust, sensitive and rapid analytical techniques. In this communication we present results of an investigation of the oxysterols content of human plasma using a newly developed high-performance liquid chromatography-mass spectrometry (HPLC-MS) method incorporating charge-tagging and high-resolution MS. The method has allowed the identification in plasma of monohydroxylated cholesterol molecules, 7alpha-, 24S-, and 27-hydroxycholesterol; the cholestenetriol 7alpha,27-dihydroxycholesterol; and 3beta-hydroxycholest-5-en-27-oic acid and its metabolite 3beta,7alpha-dihydroxycholest-5-en-27-oic acid. The methodology described is also applicable for the analysis of other sterols in plasma, that is, cholesterol, 7-dehydrocholesterol, and desmosterol, as well as cholesterol 5,6- seco-sterols and steroid hormones. Although involving derivatization, sample preparation is straightforward and chromatographic analysis rapid (17 min), while the MS method offers high sensitivity (ng/mL of sterol in plasma, or pg on-column) and specificity. The methodology is suitable for targeted metabolomic analysis of sterols, oxysterols, and steroid hormones opening a "window" to view this region of the metabolome.
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Affiliation(s)
- William J Griffiths
- Institute of Mass Spectrometry, School of Medicine, Grove Building, Swansea University, Singleton Park, Swansea, UK.
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7Alpha-hydroxypregnenolone mediates melatonin action underlying diurnal locomotor rhythms. J Neurosci 2008; 28:2158-67. [PMID: 18305249 DOI: 10.1523/jneurosci.3562-07.2008] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Melatonin regulates diurnal changes in locomotor activity in vertebrates, but the molecular mechanism for this neurohormonal regulation of behavior is poorly understood. Here we show that 7alpha-hydroxypregnenolone, a previously undescribed avian neurosteroid, mediates melatonin action on diurnal locomotor rhythms in quail. In this study, we first identified 7alpha-hydroxypregnenolone and its stereoisomer 7beta-hydroxypregnenolone in quail brain. These neurosteroids have not been described previously in avian brain. We then demonstrated that 7alpha-hydroxypregnenolone acutely increased quail locomotor activity. To analyze the production of 7alpha-hydroxypregnenolone, cytochrome P450(7alpha), a steroidogenic enzyme of this neurosteroid, was also identified. Subsequently, we demonstrated diurnal changes in 7alpha-hydroxypregnenolone synthesis in quail. 7Alpha-Hydroxypregnenolone synthesis and locomotor activity in males were much higher than in females. This is the first demonstration in any vertebrate of a clear sex difference in neurosteroid synthesis. This sex difference in 7alpha-hydroxypregnenolone synthesis corresponded to the sex difference in locomotion. We show that only males exhibited marked diurnal changes in 7alpha-hydroxypregnenolone synthesis, and these changes occurred in parallel with changes in locomotor activity. Finally, we identified melatonin as a key component of the mechanism regulating 7alpha-hydroxypregnenolone synthesis. Increased synthesis of 7alpha-hydroxypregnenolone occurred in males in vivo after melatonin removal via pinealectomy and orbital enucleation (Px plus Ex). Conversely, decreased synthesis of this neurosteroid occurred after melatonin administration to Px plus Ex males. This study demonstrates that melatonin regulates synthesis of 7alpha-hydroxypregnenolone, a key factor for induction of locomotor activity, thus inducing diurnal locomotor changes in male birds. This is a previously undescribed role for melatonin.
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Wada T, Kang HS, Angers M, Gong H, Bhatia S, Khadem S, Ren S, Ellis E, Strom SC, Jetten AM, Xie W. Identification of oxysterol 7alpha-hydroxylase (Cyp7b1) as a novel retinoid-related orphan receptor alpha (RORalpha) (NR1F1) target gene and a functional cross-talk between RORalpha and liver X receptor (NR1H3). Mol Pharmacol 2008; 73:891-9. [PMID: 18055760 DOI: 10.1124/mol.107.040741] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The retinoid-related orphan receptors (RORs) and liver X receptors (LXRs) were postulated to have distinct functions. RORs play a role in tissue development and circadian rhythm, whereas LXRs are sterol sensors that affect lipid homeostasis. In this study, we revealed a novel function of RORalpha (NR1F1) in regulating the oxysterol 7alpha-hydroxylase (Cyp7b1), an enzyme critical for the homeostasis of cholesterol, bile acids, and oxysterols. The expression of Cyp7b1 gene was suppressed in the RORalpha null (RORalpha(sg/sg)) mice, suggesting RORalpha as a positive regulator of Cyp7b1. Promoter analysis established Cyp7b1 as a transcriptional target of RORalpha, and transfection of RORalpha induced the expression of endogenous Cyp7b1 in the liver. Interestingly, Cyp7b1 regulation seemed to be RORalpha-specific, because RORgamma had little effect. Reporter gene analysis showed that the activation of Cyp7b1 gene promoter by RORalpha was suppressed by LXRalpha (NR1H3), whereas RORalpha inhibited both the constitutive and ligand-dependent activities of LXRalpha. The mutual suppression between RORalpha and LXR was supported by the in vivo observation that loss of RORalpha increased the expression of selected LXR target genes, leading to hepatic triglyceride accumulation. Likewise, mice deficient of LXR alpha and beta isoforms showed activation of selected RORalpha target genes. Our results have revealed a novel role for RORalpha and a functional interplay between RORalpha and LXR in regulating endo- and xenobiotic genes, which may have broad implications in metabolic homeostasis.
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MESH Headings
- Adult
- Animals
- Cells, Cultured
- Cholesterol/blood
- Cytochrome P-450 Enzyme System/genetics
- Cytochrome P-450 Enzyme System/metabolism
- DNA-Binding Proteins/deficiency
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/physiology
- Fasting
- Female
- Gene Expression Regulation
- Genes, Reporter
- Hepatocytes/cytology
- Hepatocytes/metabolism
- Humans
- Liver X Receptors
- Luciferases/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred Strains
- Mice, Knockout
- Nuclear Receptor Subfamily 1, Group F, Member 1
- Orphan Nuclear Receptors
- Promoter Regions, Genetic
- Receptors, Cytoplasmic and Nuclear/deficiency
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/physiology
- Steroid Hydroxylases/genetics
- Steroid Hydroxylases/metabolism
- Trans-Activators/deficiency
- Trans-Activators/genetics
- Trans-Activators/physiology
- Transfection
- Triglycerides/blood
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Affiliation(s)
- Taira Wada
- Center for Pharmacogenetics, 633 Salk Hall, University of Pittsburgh, Pittsburgh, PA 15213, USA.
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29
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30
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Abstract
Dehydroepiandrosterone (DHEA) is 7alpha-hydroxylated by the cytochrome P4507B1 in the liver, skin and brain, which are targets for glucocorticoids. 7alpha-Hydroxy-DHEA produced anti-glucocorticoid effects in vivo but the interference between the glucocorticoid hormone binding with its receptor could not be determined. In the organs mentioned above, circulating inactive cortisone is reduced to active cortisol by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). 7alpha-Hydroxy-DHEA is also a substrate for this enzyme. Studies of 11beta-HSD1 action on 7alpha-hydroxy-DHEA show the reversible production of 7beta-hydroxy-DHEA through an intermediary 7-oxo-DHEA. Both the production of 7alpha-hydroxysteroids and their interference with the activation of cortisone into cortisol are basic to the concept of native anti-glucocorticoids. The cytochrome P4507B1 responsible for 7alpha-hydroxy-DHEA production and 11beta-HSD1 are key enzymes for the modulation of glucocorticoid action in humans. This is a promising new area for research.
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Affiliation(s)
- Sonia Chalbot
- Laboratoire de Biotechnologie, Conservatoire National des Arts et Métiers, Paris, France
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31
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Abstract
The nuclear receptors CAR and PXR were first characterized as xenosensing transcription factors regulating the induction of phase I and II xenobiotic-metabolizing enzymes as well as transporters in response to exogenous stimuli. It has now become clear, however, that these receptors cross-talk with endogenous stimuli as well, which extends their regulation to various physiological processes such as energy metabolism and cell growth. As recognition of the function of these receptors has widened, the molecular mechanism of their regulation has evolved from simple protein-DNA binding to regulation by complex protein-protein interactions. Novel mechanisms as to how xenobiotic exposure alters hepatic metabolic pathways such as gluconeogenesis and beta-oxidation have emerged. At the same time, the molecular mechanism of how endogenous stimuli, such as insulin, regulate xenobiotc metabolism via CAR and PXR have also become evident.
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Affiliation(s)
| | - MASAHIKO NEGISHI
- Corresponding author: Masahiko Negishi, Ph.D., Tel: 919-541-2404, Fax: 919-541-0696, E-mail:
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32
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Abstract
This review summarizes the mechanisms of cellular cholesterol transport and monogenic human diseases caused by defects in intracellular cholesterol processing. In addition, selected mouse models of disturbed cholesterol trafficking are discussed. Current pharmacological strategies to prevent atherosclerosis are largely based on altering cellular cholesterol balance and are introduced in this context. Finally, because of the organizing potential of cholesterol in membranes, disturbances in cellular cholesterol transport have implications for a wide variety of human diseases, of which selected examples are given.
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Affiliation(s)
- Elina Ikonen
- Institute of Biomedicine/Anatomy, University of Helsinki, Helsinki, Finland.
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33
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Tan X, Behari J, Cieply B, Michalopoulos GK, Monga SPS. Conditional deletion of beta-catenin reveals its role in liver growth and regeneration. Gastroenterology 2006; 131:1561-72. [PMID: 17101329 DOI: 10.1053/j.gastro.2006.08.042] [Citation(s) in RCA: 293] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Accepted: 07/19/2006] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS The Wnt/beta-catenin pathway plays a role in liver growth and development. To address this conclusively, we used a conditional knockout approach to delete beta-catenin in the liver. METHODS Floxed beta-catenin (exons 2-6) mice were intercrossed with Albumin-Cre recombinase transgenic mice; considerable beta-catenin deletion was evident 15 days after birth by Western blot and immunohistochemistry analyses. RESULTS Although these mice were viable, there was a significant decrease in their liver weight/body weight ratio by 14% at 1 month and 28%-35% by 2-6 months of age, which was sustained throughout their normal life span. There was an accompanying decrease in basal hepatocyte proliferation showed by Ki-67 staining. Additional analysis revealed several known and novel genes to be down-regulated in these mice that play a role in normal liver homeostasis. When subjected to two-thirds partial hepatectomy, the Ctnnb1(loxp/loxp); Alb-Cre(+/-) mice were sick and lethargic, especially during the first 2-3 days only. These mice display a 2-fold decrease in the number of Ki-67- or PCNA-positive cells at the time of peak hepatocyte proliferation at 40 hours, which coincided with decreased cyclin A, D, and E expression. However, a rebound increase in hepatocyte proliferation was evident in the knockout mice at 3 days. Also, increased apoptosis was observed in the knockout livers during regeneration at all stages. CONCLUSIONS Thus, beta-catenin is essential for normal liver growth and development. Also, although regeneration is delayed in the absence of beta-catenin, it does occur suboptimally, showing its redundancy in the liver.
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Affiliation(s)
- Xinping Tan
- Department of Pathology, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA
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34
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Stoilov I, Krueger W, Mankowski D, Guernsey L, Kaur A, Glynn J, Thrall RS. The cytochromes P450 (CYP) response to allergic inflammation of the lung. Arch Biochem Biophys 2006; 456:30-8. [PMID: 17081494 DOI: 10.1016/j.abb.2006.09.029] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Revised: 09/27/2006] [Accepted: 09/28/2006] [Indexed: 11/27/2022]
Abstract
The expression of the mouse Cyp family and key inflammatory mediators were examined in a model of ovalbumin (OVA)-induced allergic airway disease. The expression of IL-4, IL-13 and Ccl11 increased during the acute phase of allergic inflammation and decreased with its resolution. Interestingly, the expression of Ccl20 was increased during the resolution phase. The response of the Cyp gene family to the development of allergic inflammation was differential and correlated with the evolution of the inflammatory response. During the acute inflammatory phase the mRNA levels of Cyp2e1, Cyp2f2, Cyp2j6, Cyp4b1, Cyp8a1 and Cypor were decreased while the mRNA levels of Cyp4f18, Cyp5a1 and Cyp7b1 were elevated. With resolution of the inflammation the expression patterns returned to normal. These changes suggest that the Cyp family may play a role in the allergic inflammation by modulating the metabolism of xenobiotics and endogenous compounds such as LTB4, TXA1, PGI2 and native anti-glucocorticoids.
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Affiliation(s)
- Ivaylo Stoilov
- Department of Pharmacology, University of Connecticut Health Center, Farmington, CT 06030, USA.
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35
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Hubacek JA, Bobkova D. Role of cholesterol 7alpha-hydroxylase (CYP7A1) in nutrigenetics and pharmacogenetics of cholesterol lowering. Mol Diagn Ther 2006; 10:93-100. [PMID: 16669607 DOI: 10.1007/bf03256448] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The relationship between dietary composition/cholesterol-lowering therapy and final plasma lipid levels is to some extent genetically determined. It is clear that these responses are under polygenic control, with multiple variants in many genes participating in the total effect (and with each gene contributing a relatively small effect). Using different experimental approaches, several candidate genes have been analyzed to date.Interesting and consistent results have been published recently regarding the A-204C promoter variant in the cholesterol 7alpha-hydroxylase (CYP7A1) gene. CYP7A1 is a rate-limiting enzyme in bile acid synthesis and therefore plays an important role in maintaining cholesterol homeostasis. CYP7A1-204CC homozygotes have the greatest decrease in total cholesterol level in response to dietary changes in different types of dietary intervention studies. In contrast, one study has reported that the effect of statins in lowering low-density lipoprotein (LDL)-cholesterol levels was slightly greater in -204AA homozygotes. The CYP7A1 A-204C variant accounts for a significant proportion of the genetic predisposition of the response of plasma cholesterol levels.
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Affiliation(s)
- Jaroslav A Hubacek
- Institute for Clinical and Experimental Medicine, Prague, Czech Republic
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36
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Muller C, Hennebert O, Morfin R. The native anti-glucocorticoid paradigm. J Steroid Biochem Mol Biol 2006; 100:95-105. [PMID: 16713254 DOI: 10.1016/j.jsbmb.2006.03.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2006] [Accepted: 03/22/2006] [Indexed: 11/27/2022]
Abstract
Circulating 3beta-hydroxysteroids including dehydroepiandrosterone (DHEA) are 7alpha-hydroxylated by the cytochrome P450-7B1 in the liver, skin and brain, which are the target organs of glucocorticoids. Anti-glucocorticoid effects with 7alpha-hydroxy-DHEA were observed in vivo without an interference with glucocorticoid binding to its receptor. In the organs mentioned above, the circulating inactive cortisone was reduced into active cortisol by the 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). We demonstrated that 7alpha-hydroxy-DHEA was also a substrate for this enzyme. Studies of the 11beta-HSD1 action on 7alpha-hydroxy-DHEA showed the reversible production of 7beta-hydroxy-DHEA through an intermediary 7-oxo-DHEA, and the kinetic parameters favored this production over that of active glucocorticoids. Both the production of 7alpha-hydroxysteroids and their interference with the activation of cortisone into cortisol are basic to the concept of native anti-glucocorticoids efficient at their production site. This opens a promising new area for research.
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Affiliation(s)
- Caroline Muller
- Laboratoire de Biotechnologie, EA 3199, Conservatoire National des Arts et Métiers, 2 rue Conté, 75003 Paris, France
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37
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Tabata S, Yin G, Ogawa S, Yamaguchi K, Mineshita M, Kono S. Genetic polymorphism of cholesterol 7alpha-hydroxylase (CYP7A1) and colorectal adenomas: Self Defense Forces Health Study. Cancer Sci 2006; 97:406-10. [PMID: 16630139 PMCID: PMC11159969 DOI: 10.1111/j.1349-7006.2006.00182.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Bile acids have long been implicated in colorectal carcinogenesis, but epidemiological evidence is limited. Cholesterol 7alpha-hydroxylase (CYP7A1) is the rate-limiting enzyme producing bile acids from cholesterol. A recent case-control study showed a decreased risk of proximal colon cancer associated with the CC genotype of the CYP7A1 A-203C polymorphism. The present study examined the relationship between the CYP7A1 A-203C polymorphism and colorectal adenoma, which is a well-established precursor lesion of colorectal cancer. The study subjects comprised 446 cases of colorectal adenomas and 914 controls of normal total colonoscopy among men receiving a preretirement health examination at two hospitals of the Self Defense Forces (SDF). The CYP7A1 genotype was determined by the polymerase chain reaction-restriction fragment length polymorphism method. Statistical adjustment was made for age, hospital, rank in the SDF, smoking, alcohol use, body mass index, physical activity and parental history of colorectal cancer. The CYP7A1 polymorphism was not measurably related to the overall risk of colorectal adenomas. However, the CC genotype was associated with a decreased risk of proximal colon adenomas, but not of distal colon and rectal adenomas. Adjusted odds ratios of proximal colon adenomas (95% confidence intervals) for the AC and CC genotype versus AA genotype were 0.82 (0.54-1.24) and 0.56 (0.34-0.95), respectively. The findings add to evidence for the role of bile acids in colorectal carcinogenesis. The CC genotype of the CYP7A1 A-203C polymorphism probably renders lower activity of the enzyme synthesizing bile acids.
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Affiliation(s)
- Shinji Tabata
- Department of Preventive Medicine, Faculty of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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38
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Chalbot S, Morfin R. Human liver S9 fractions: metabolism of dehydroepiandrosterone, epiandrosterone, and related 7-hydroxylated derivatives. Drug Metab Dispos 2005; 33:563-9. [PMID: 15650074 DOI: 10.1124/dmd.104.003004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Dehydroepiandrosterone (DHEA) and 3beta-hydroxy-5alpha-androstan-17-one (epiandrosterone, EpiA) are both precursors for 7alpha- and 7beta-hydroxylated metabolites in the human brain. These 7-hydroxylated derivatives were shown to exert anti-glucocorticoid and neuroprotective effects. When these steroids are administered per os to humans, the first organ encountered is the liver, where extensive metabolism takes place. The objective of this work was to assess the cofactor dependence and metabolism of DHEA, EpiA, and their 7-hydroxylated derivatives in S9 fractions of human liver, using a radiolabeled steroid substrate for quantification and gas chromatography-mass spectrometry for identification. The best transformation yields were obtained with NADPH and were larger in female than in male. Results showed that both DHEA and EpiA mainly transformed into their 17beta-hydroxylated derivatives, 7- or 16alpha-hydroxylated metabolites under NAD(P)H conditions, and 5alpha-androstane-3,17-dione for EpiA under NAD(P)+ conditions. In turn, 7alpha-hydroxy-DHEA and 7beta-hydroxy-DHEA were partly transformed into each other via a 7-oxo-DHEA intermediate and were reduced into the 17beta-hydroxy derivative, respectively. The same type of transformations occurred for 7alpha-hydroxy-EpiA and 7beta-hydroxy-EpiA, except that no 7-oxo-EpiA intermediate was obtained. These findings determine the presence of enzymes responsible for the 7alpha- and 16alpha-hydroxylation in the human liver, the 11beta-hydroxysteroid dehydrogenase type 1 responsible for the oxidoreduction of the 7-hydroxylated substrates, and the 17beta-hydroxysteroid dehydrogenase responsible for the reduction of 17-oxo-steroids into 17beta-hydroxysteroids.
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Affiliation(s)
- Sonia Chalbot
- Biotechnologie CNAM, 2 rue Conté, 75003 Paris, France
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Chalbot S, Morfin R. Neurosteroids: metabolism in human intestine microsomes. Steroids 2005; 70:319-26. [PMID: 15784286 DOI: 10.1016/j.steroids.2004.12.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2004] [Revised: 12/20/2004] [Accepted: 12/23/2004] [Indexed: 11/17/2022]
Abstract
Both dehydroepiandrosterone (DHEA) and epiandrosterone (EpiA) are substrate for cytochrome P450 species and enzymes that produce 7alpha- and 7beta-hydroxylated metabolites in the brain and other organs. In contrast to DHEA and EpiA, the 7-hydroxylated derivatives were shown to mediate neuroprotection, and 7beta-hydroxy-EpiA was the most potent. The suggested use of any of these steroids as drugs administered per os for neuroprotection requires the assessment of their metabolism in the human intestine and liver. To achieve this, we produced radio-labeled 7alpha-hydroxy-DHEA, 7beta-hydroxy-DHEA, 7alpha-hydroxy-EpiA and 7beta-hydroxy-EpiA that were used as substrates in incubations with human intestine microsomes supplemented with reduced or oxidized cofactors. Identity of the radio-labeled metabolites obtained was determined by gas chromatography/mass spectrometry after comparison with authentic steroid references. The proportions of metabolites produced resulted from their radioactivity contents. The only metabolite obtained with DHEA, EpiA, 7alpha-hydroxy-DHEA and 7beta-hydroxy-DHEA substrates was its 17beta-reduced derivative, thus inferring the presence of 17beta-hydroxysteroid oxidoreductases in the human intestine microsomes. In addition to the 7alpha-hydroxy-EpiA and 7beta-hydroxy-EpiA substrates, their 17beta-reduced metabolites were obtained with 7beta-hydroxy-EpiA and 7alpha-hydroxy-EpiA, respectively. The identity of the enzyme responsible for the 7alpha-hydroxy-EpiA/7beta-hydroxy-EpiA inter-conversion is unknown. The incubation conditions used produced these metabolites in low but significant yields that suggest their presence in the portal blood before access to the liver.
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Affiliation(s)
- Sonia Chalbot
- Laboratoire de Biotechnologie, EA 3199, Conservatoire National des Arts et Metiers, 2 rue Conté, 75003 Paris, France
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40
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Isoda K, Sawada S, Ayaori M, Matsuki T, Horai R, Kagata Y, Miyazaki K, Kusuhara M, Okazaki M, Matsubara O, Iwakura Y, Ohsuzu F. Deficiency of interleukin-1 receptor antagonist deteriorates fatty liver and cholesterol metabolism in hypercholesterolemic mice. J Biol Chem 2004; 280:7002-9. [PMID: 15574426 DOI: 10.1074/jbc.m412220200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Although the anti-inflammatory effect of interleukin-1 (IL-1) receptor antagonist (IL-1Ra) has been described, the contribution of this cytokine to cholesterol metabolism remains unclear. Our aim was to ascertain whether deficiency of IL-1Ra deteriorates cholesterol metabolism upon consumption of an atherogenic diet. IL-1Ra-deficient mice (IL-1Ra(-/-)) showed severe fatty liver and portal fibrosis containing many inflammatory cells following 20 weeks of an atherogenic diet when compared with wild type (WT) mice. Expectedly, the levels of total cholesterol in IL-1Ra(-/-) mice were significantly increased, and the start of lipid accumulation in liver was observed earlier when compared with WT mice. Real-time PCR analysis revealed that IL-1Ra(-/-) mice failed to induce mRNA expression of cholesterol 7alpha-hydroxylase, which is the rate-limiting enzyme in bile acid synthesis, with concurrent up-regulation of small heterodimer partner 1 mRNA expression. Indeed, IL-1Ra(-/-) mice showed markedly decreased bile acid excretion, which is elevated in WT mice to maintain cholesterol level under atherogenic diet feeding. Therefore, we conclude that the lack of IL-1Ra deteriorates cholesterol homeostasis under atherogenic diet-induced inflammation.
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Affiliation(s)
- Kikuo Isoda
- Internal Medicine I, National Defense Medical College, Tokorozawa 359-8513, Japan.
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41
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Abstract
The molecular mechanism of how hepatocytes maintain cholesterol homeostasis has become much more transparent with the discovery of sterol regulatory element binding proteins (SREBPs) in recent years. These membrane proteins are members of the basic helix-loop-helix-leucine zipper (bHLH-Zip) family of transcription factors. They activate the expression of at least 30 genes involved in the synthesis of cholesterol and lipids. SREBPs are synthesized as precursor proteins in the endoplasmic reticulum (ER), where they form a complex with another protein, SREBP cleavage activating protein (SCAP). The SCAP molecule contains a sterol sensory domain. In the presence of high cellular sterol concentrations SCAP confines SREBP to the ER. With low cellular concentrations, SCAP escorts SREBP to activation in the Golgi. There, SREBP undergoes two proteolytic cleavage steps to release the mature, biologically active transcription factor, nuclear SREBP (nSREBP). nSREBP translocates to the nucleus and binds to sterol response elements (SRE) in the promoter/enhancer regions of target genes. Additional transcription factors are required to activate transcription of these genes. Three different SREBPs are known, SREBPs-1a, -1c and -2. SREBP-1a and -1c are isoforms produced from a single gene by alternate splicing. SREBP-2 is encoded by a different gene and does not display any isoforms. It appears that SREBPs alone, in the sequence described above, can exert complete control over cholesterol synthesis, whereas many additional factors (hormones, cytokines, etc.) are required for complete control of lipid metabolism. Medicinal manipulation of the SREBP/SCAP system is expected to prove highly beneficial in the management of cholesterol-related disease.
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Affiliation(s)
- Lutz-W Weber
- Institute of Toxicology, GSF-National Research Center for Environment and Health, Munich, D-85758 Neuherberg, Germany.
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42
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Abstract
Cholesterol and its metabolites, e.g., steroid hormones and bile acids, constitute a class of compounds of great biological importance. Their chemistry, biochemistry, and regulation in the body have been intensely studied for more than two centuries. The author has studied aspects of the biochemistry and clinical chemistry of steroids and bile acids for more than 50 years, and this paper, which is an extended version of the Schroepfer Medal Award lecture, reviews and discusses part of this work. Development and application of analytical methods based on chromatography and mass spectrometry (MS) have been a central part of many projects, aiming at detailed characterization and quantification of metabolic profiles of steroids and bile acids under different conditions. In present terminology, much of the work may be termed steroidomics and cholanoidomics. Topics discussed are bile acids in human bile and feces, bile acid production, bacterial dehydroxylation of bile acids and steroids during the enterohepatic circulation, profiles of steroid sulfates in plasma of humans and other primates, development of neutral and ion-exchanging lipophilic derivatives of Sephadex for sample preparation and group separation of steroid and bile acid conjugates, profiles of steroids and bile acids in human urine under different conditions, hydroxylation of bile acids in liver disease, effects of alcohol-induced redox changes on steroid synthesis and metabolism, alcohol-induced changes of bile acid biosynthesis, compartmentation of bile acid synthesis studied with 3H-labeled ethanol, formation and metabolism of sulfated metabolites of progesterone in human pregnancy, abnormal patterns of these in patients with intrahepatic cholestasis of pregnancy corrected by ursodeoxycholic acid, inherited and acquired defects of bile acid biosynthesis and their treatment, conjugation of bile acids and steroids with N-acetylglucosamine, sulfate-glucuronide double conjugates of hydroxycholesterols, extrahepatic 7alpha-hydroxylation and 3-dehydrogenation of hydroxycholesterols, and extrahepatic formation of C27 bile acids. The final part discusses analysis of free and sulfated steroids in brain tissue by capillary liquid chromatography-electrospray MS and suggests a need for reevaluation of the function of steroid sulfates in rat brain.
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Affiliation(s)
- Jan Sjövall
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77, Stockholm, Sweden.
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43
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Pullinger CR, Kane JP, Malloy MJ. Primary hypercholesterolemia: genetic causes and treatment of five monogenic disorders. Expert Rev Cardiovasc Ther 2004; 1:107-19. [PMID: 15030301 DOI: 10.1586/14779072.1.1.107] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Coronary heart disease is a major cause of death in Europe and the USA. Insudation of atherogenic lipoproteins, including low-density lipoprotein (LDL), into the artery wall is integral to atherosclerosis. It is clear that numerous genetic loci contribute to increased plasma levels of LDL. However, five specific monogenic disorders, three of which have been reported recently, are known to increase LDL. These are familial hypercholesterolemia (LDL receptor gene: LDLR); familial ligand-defective apoB- 100 (apoB gene: APOB); autosomal recessive hypercholesterolemia (ARH gene); sitosterolemia (ABCG5 or ABCG8 genes) and cholesterol 7alpha-hydroxylase deficiency (CYP7A1 gene). This review relates the mechanisms underlying these five disorders with specific therapeutic interventions.
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Affiliation(s)
- Clive R Pullinger
- Cardiovascular Research Institute, University of California, San Francisco, USA.
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44
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Wang L, Han Y, Kim CS, Lee YK, Moore DD. Resistance of SHP-null mice to bile acid-induced liver damage. J Biol Chem 2003; 278:44475-81. [PMID: 12933814 DOI: 10.1074/jbc.m305258200] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The orphan nuclear hormone receptor SHP (gene designation NROB2) is an important component of a negative regulatory cascade by which high levels of bile acids repress bile acid biosynthesis. Short term studies in SHP null animals confirm this function and also reveal the existence of additional pathways for bile acid negative feedback regulation. We have used long term dietary treatments to test the role of SHP in response to chronic elevation of bile acids, cholesterol, or both. In contrast to the increased sensitivity predicted from the loss of negative feedback regulation, the SHP null mice were relatively resistant to the hepatotoxicity associated with a diet containing 0.5% cholic acid and the much more severe effects of a diet containing both 0.5% cholic acid and 2% cholesterol. This was associated with decreased hepatic accumulation of cholesterol and triglycerides in the SHP null mice. There were also alterations in the expression of a number of genes involved in cholesterol and bile acid homeostasis, notably cholesterol 12alpha-hydroxylase (CYP8B1), which was strongly reexpressed in the SHP null mice, but not the wild type mice fed either bile acid containing diet. This contrasts with the strong repression of CYP8B1 observed with short term bile acid feeding, as well as the effects of long term feeding on other bile acid biosynthetic enzymes such as cholesterol 7alpha-hydroxylase (CYP7A1). CYP8B1 expression could contribute to the decreased toxicity of the chronic bile acid treatment by increasing the hydrophilicity of the bile acid pool. These results identify an unexpected role for SHP in hepatotoxicity and suggest new approaches to modulating effects of chronically elevated bile acids in cholestasis.
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Affiliation(s)
- Li Wang
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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Maeda K, Kimura A, Yamato Y, Matsuishi T. Perinatal bile acid metabolism: analysis of urinary unsaturated ketonic bile acids in preterm and full-term infants. Acta Paediatr 2003; 92:216-20. [PMID: 12710649 DOI: 10.1111/j.1651-2227.2003.tb00529.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIM To compare urinary concentrations of unsaturated ketonic bile acids in preterm and full-term infants. METHODS Urinary unsaturated ketonic bile acids were determined using gas chromatography-mass spectrometry. RESULTS Urinary concentrations of total bile acids in early preterm infants (of less than 29wk gestational age) exceeded concentrations in late preterm (between 30 and 37 wk) and full-term infants (between 38 and 41 wk; p < 0.01). The percentage of ketonic bile acids (7alpha, 12alpha-dihydroxy-3-oxo-4-cholenoic acid and 7alpha-hydroxy-3-oxo-4-cholenoic acid) among total urinary bile acids in full-term infants (20.2 +/- 14.1%) was higher than that in early preterm infants (8.94 +/- 8.1%; p < 0.05). The percentage of unsaturated bile acids (3beta-hydroxy-delta5-bile acids) among total bile acids in urine did not differ greatly between groups. CONCLUSION The percentage of 3-oxo-delta4 bile acids among total bile acids in urine gradually increased from early to late preterm infants, while healthy full-term infants excreted large amounts of 3-oxo-delta4 bile acids in urine at delivery.
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Affiliation(s)
- K Maeda
- Department of Pediatrics and Child Health, Kurume University School of Medicine, Kurume, Japan
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Ren S, Marques D, Redford K, Hylemon PB, Gil G, Vlahcevic ZR, Pandak WM. Regulation of oxysterol 7alpha-hydroxylase (CYP7B1) in the rat. Metabolism 2003; 52:636-42. [PMID: 12759897 DOI: 10.1053/meta.2003.50106] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cholesterol metabolized to 7alpha-hydroxylated bile acids is a principle pathway of cholesterol degradation. Cholesterol 7alpha-hydroxylase (CYP7A1) is the initial and rate-determining enzyme in the "classic pathway" of bile acid synthesis. An "alternative" pathway of bile acid synthesis begins with 27-hydroxylation of cholesterol by 27-hydroxylase (CYP27), followed by 7alpha-hydroxylation by oxysterol 7alpha-hydroxylase (CYP7B1). The aim of the current study was to investigate the regulation of CYP7B1 by bile acids, cholesterol, and thyroid hormone in a previously well-studied in vivo model of bile acid synthesis, and to compare its regulation to that of CYP7A1. Three study groups were examined. In the first, male Sprague-Dawley rats with intact enterohepatic circulations were fed normal chow (controls), cholestyramine (CT), cholic acid (CA), chenodeoxycholic acid (CDCA), deoxycholic acid (DCA), or cholesterol (Chol). In the second group, taurocholate (TCA) was continuously intraduodenally infused for 48 hours to chronic biliary diverted rats. In a third set of studies, squalestatin, an inhibitor of cholesterol synthesis, was intravenously infused for 48 hours. In a fourth set of studies, the diurnal variation in CYP7B1 was compared to that of CYP7A1. At the end of each study livers were harvested, and CYP7B1 and CYP7A1 activities and mRNA levels were determined. Complete biliary diversion significantly increased the specific activity (SA) of both CYP7B1 ( upward arrow 212%; P <.002) and CYP7A1 ( upward arrow 212%; P <.007). Intraduodenal infusion of TCA to rats with biliary diversion decreased SA of both CYP7B1 ( downward arrow 29%; P <.001) and CYP7A1 ( downward arrow 46%; P <.01). The addition of CA, CDCA, or DCA to rat chow led to downregulation of CYP7B1 SAs by 42% (P <.003), 51% (P <.009), and 47% (P <.003), and CYP7A1 SAs by 32% +/- 6% (P <.003), 73% +/- 9% (P <.002), and 60% +/- 13% (P <.004), respectively. CT feeding upregulated both CYP7B1 ( upward arrow 136%; P <.004) and CYP7A1 ( upward arrow 216%; P <.001) SAs. While Chol feeding significantly upregulated CYP7A1 SA, no significant increase in CYP7B1 SA was found. Conversely, as previously shown in vitro, inhibition of cholesterol synthesis significantly suppressed both CYP7A1 and CYP7B1 activity and mRNA levels. Both CYP7B1 and CYP7A1 underwent diurnal variation, with peak and trough values for CYP7B1 lagging approximately 6 hours behind CYP7A1. We conclude that, in the rat, like CYP7A1, CYP7B1 demonstrates diurnal rhythm and is regulated by bile acids and cholesterol.
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Affiliation(s)
- Shunlin Ren
- Department of Medicine, Veterans Affairs Medical Center and Virginia Commonwealth University, Richmond, VA 23249, USA
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Cheng JB, Jacquemin E, Gerhardt M, Nazer H, Cresteil D, Heubi JE, Setchell KDR, Russell DW. Molecular genetics of 3beta-hydroxy-Delta5-C27-steroid oxidoreductase deficiency in 16 patients with loss of bile acid synthesis and liver disease. J Clin Endocrinol Metab 2003; 88:1833-41. [PMID: 12679481 DOI: 10.1210/jc.2002-021580] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The 3beta-hydroxy-Delta(5)-C(27)-steroid oxidoreductase (C(27) 3beta-HSD) is a membrane-bound enzyme of the endoplasmic reticulum that catalyzes an early step in the synthesis of bile acids from cholesterol. Subjects with autosomal recessive mutations in the encoding gene, HSD3B7, on chromosome 16p11.2-12 fail to synthesize bile acids and develop a form of progressive liver disease characterized by cholestatic jaundice and malabsorption of lipids and lipid-soluble vitamins from the gastrointestinal tract. The gene encoding the human C(27) 3beta-HSD enzyme was isolated previously, and a 2-bp deletion in exon 6 of HSD3B7 was identified in a well characterized subject with this disorder. Here, we report a molecular analysis of 15 additional patients from 13 kindreds with C(27) 3beta-HSD deficiency. Twelve different mutations were identified in the HSD3B7 gene on chromosome 16p11.2-12. Ten mutations were studied in detail and shown to cause complete loss of enzyme activity and, in two cases, alterations in the size or amount of the transcribed mRNA. Mutations were inherited in homozygous form in 13 subjects from 10 families and compound heterozygous form in four subjects from three families. We conclude that a diverse spectrum of mutations in the HSD3B7 gene underlies this rare form of neonatal cholestasis.
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Affiliation(s)
- Jeffrey B Cheng
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9046, USA
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Yoo JY, Desiderio S. Innate and acquired immunity intersect in a global view of the acute-phase response. Proc Natl Acad Sci U S A 2003; 100:1157-62. [PMID: 12540827 PMCID: PMC298743 DOI: 10.1073/pnas.0336385100] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recognition of stereotypic chemical patterns by sentinel cells of the innate immune system provokes a transient deviation from homeostasis, the acute-phase response (APR). Although APR effectors have been identified individually, the complexity of the response suggested that emergent properties would be uncovered by a more comprehensive examination. Our global assessment revealed that approximately 7% of genes in the mouse are mobilized in the hepatic APR to endotoxin. Extensive metabolic adjustments include suppression of pathways for cholesterol, fatty acid, and phospholipid synthesis. Increased expression of genes for innate defense was accompanied by coordinate induction of the MHC class I antigen presentation machinery, illustrating an intersection between innate and adaptive immunity.
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Affiliation(s)
- Joo-Yeon Yoo
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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Murtazina D, Puchkaev AV, Schein CH, Oezguen N, Braun W, Nanavati A, Pikuleva IA. Membrane-protein interactions contribute to efficient 27-hydroxylation of cholesterol by mitochondrial cytochrome P450 27A1. J Biol Chem 2002; 277:37582-9. [PMID: 12124390 DOI: 10.1074/jbc.m204909200] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mitochondrial cytochrome P450 27A1 (P450 27A1) catalyzes 27-hydroxylation of cholesterol, the first step in the alternative bile acid biosynthetic pathway. Although several crystal structures of P450s are known, no structural information is available for the mammalian, membrane-bound enzymes involved in the removal of cholesterol from the body. We prepared a three-dimensional model of P450 27A1 based on the structure of P450 BM-3. Conservative and non-conservative mutations were introduced at hydrophobic and positively charged residues in the putative F-G loop and the adjacent helix G (positions 219-237). Subcellular distribution of the mutant P450s expressed in Escherichia coli was used as a measure of membrane-protein interactions. Conservative substitutions of residues located on the surface, according to our model, L219V, L219I, Y220F, F223Y, L224I, R229K, V231L, F234Y, K236R, and R237K, weakened the association of the mutant P450s with the membrane and led to the appearance of up to 21% of P450 27A1 in the bacterial cytosol. It is likely that the mutated side chains are involved in binding to membrane phospholipids. Substitutions in the F-G loop did not significantly affect the K(m) value for cholesterol hydroxylation. However, non-conservative mutants, L219N, Y220A, Y220S, F223A, K226R, and R229A, had significantly impaired catalytic properties, indicating strict requirements for the size and polarity of the side chains at these positions for the catalysis. The results provide insight into the membrane topology of mitochondrial P450s and indicate the importance of membrane-protein interactions in the efficiency of reactions catalyzed by P450 27A1.
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Affiliation(s)
- Dilyara Murtazina
- Department of Pharmacology and Toxicology and Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, Texas 77555, USA
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Pullinger CR, Eng C, Salen G, Shefer S, Batta AK, Erickson SK, Verhagen A, Rivera CR, Mulvihill SJ, Malloy MJ, Kane JP. Human cholesterol 7alpha-hydroxylase (CYP7A1) deficiency has a hypercholesterolemic phenotype. J Clin Invest 2002. [PMID: 12093894 DOI: 10.1172/jci0215387] [Citation(s) in RCA: 356] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Bile acid synthesis plays a critical role in the maintenance of mammalian cholesterol homeostasis. The CYP7A1 gene encodes the enzyme cholesterol 7alpha-hydroxylase, which catalyzes the initial step in cholesterol catabolism and bile acid synthesis. We report here a new metabolic disorder presenting with hyperlipidemia caused by a homozygous deletion mutation in CYP7A1. The mutation leads to a frameshift (L413fsX414) that results in loss of the active site and enzyme function. High levels of LDL cholesterol were seen in three homozygous subjects. Analysis of a liver biopsy and stool from one of these subjects revealed double the normal hepatic cholesterol content, a markedly deficient rate of bile acid excretion, and evidence for upregulation of the alternative bile acid pathway. Two male subjects studied had hypertriglyceridemia and premature gallstone disease, and their LDL cholesterol levels were noticeably resistant to 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors. One subject also had premature coronary and peripheral vascular disease. Study of the kindred, which is of English and Celtic background, revealed that individuals heterozygous for the mutation are also hyperlipidemic, indicating that this is a codominant disorder.
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Affiliation(s)
- Clive R Pullinger
- Cardiovascular Research Institute, University of California-San Francisco, San Francisco, CA 94143-0130, USA.
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