Published online Apr 21, 2020. doi: 10.3748/wjg.v26.i15.1758
Peer-review started: December 28, 2019
First decision: January 11, 2020
Revised: March 17, 2020
Accepted: March 27, 2020
Article in press: March 27, 2020
Published online: April 21, 2020
Processing time: 114 Days and 20.8 Hours
Intestinal ischemia reperfusion (I/R) occurs in various diseases, such as trauma and intestinal transplantation. Excessive reactive oxygen species (ROS) accumulation and subsequent apoptotic cell death in intestinal epithelia are important causes of I/R injury. PTEN-induced putative kinase 1 (PINK1) and phosphorylation of dynamin-related protein 1 (DRP1) are critical regulators of ROS and apoptosis. However, the correlation of PINK1 and DRP1 and their function in intestinal I/R injury have not been investigated. Thus, examining the PINK1/DRP1 pathway may help to identify a protective strategy and improve the patient prognosis.
To clarify the mechanism of the PINK1/DRP1 pathway in intestinal I/R injury.
Male C57BL/6 mice were used to generate an intestinal I/R model via superior mesenteric artery occlusion followed by reperfusion. Chiu’s score was used to evaluate intestinal mucosa damage. The mitochondrial fission inhibitor mdivi-1 was administered by intraperitoneal injection. Caco-2 cells were incubated in vitro in hypoxia/reoxygenation conditions. Small interfering RNAs and overexpression plasmids were transfected to regulate PINK1 expression. The protein expression levels of PINK1, DRP1, p-DRP1 and cleaved caspase 3 were measured by Western blotting. Cell viability was evaluated using a Cell Counting Kit-8 assay and cell apoptosis was analyzed by TUNEL staining. Mitochondrial fission and ROS were tested by MitoTracker and MitoSOX respectively.
Intestinal I/R and Caco-2 cell hypoxia/reoxygenation decreased the expression of PINK1 and p-DRP1 Ser637. Pretreatment with mdivi-1 inhibited mitochondrial fission, ROS generation, and apoptosis and ameliorated cell injury in intestinal I/R. Upon PINK1 knockdown or overexpression in vitro, we found that p-DRP1 Ser637 expression and DRP1 recruitment to the mitochondria were associated with PINK1. Furthermore, we verified the physical combination of PINK1 and p-DRP1 Ser637.
PINK1 is correlated with mitochondrial fission and apoptosis by regulating DRP1 phosphorylation in intestinal I/R. These results suggest that the PINK1/DRP1 pathway is involved in intestinal I/R injury, and provide a new approach for prevention and treatment.
Core tip: PTEN-induced kinase 1 (PINK1) is a kind of mitochondrial serine/threonine-protein kinase, which regulates mitochondrial homeostasis through regulating the phosphorylation of target proteins. Depletion of PINK1 has been proved to be associated with mitochondrial fragmentation and apoptosis in ischemic model. However, the underlying mechanism has not been clarified. By establishing an intestinal ischemia reperfusion model in mice and hypoxia/reoxygenation model in Caco-2 cells, we revealed that PINK1 inhibits mitochondrial fission and apoptosis via phosphorylating dynamin-related protein 1 on Ser637. The PINK1/dynamin-related protein 1 pathway may provide a potential target in treatment of intestinal ischemia reperfusion injury.