USP38 protects intestinal epithelial cells from ischemia/reperfusion injury by stabilizing BIRC5.

BACKGROUND: Intestinal ischemia/reperfusion (II/R) is a severe condition with high mortality and limited treatment options. Extracellular vesicles that are derived from bone marrow mesenchymal stem cells (BM-MSC-EVs) exhibit therapeutic potential in alleviating II/R injury. However, the mechanism by which BM-MSC-EVs fulfill this function requires further characterization. The ubiquitin-proteasome system plays an essential role in II/R, but the functions of individual ubiquitination regulators such as ubiquitin-specific proteases (USPs) in this process remain incompletely understood. METHODS: An II/R cellular model was established by using IEC-6 intestinal epithelial cells with oxygen-glucose deprivation/reperfusion (OGD/R) treatment. The expression of USPs was evaluated by using quantitative polymerase chain reaction and Western blot. The role of USP38 on the viability, apoptosis, migration, and reactive oxygen species (ROS) levels in OGD/R-treated IEC-6 cells were measured by using CCK-8, Annexin V/PI staining, transwell assay, and 2',7'-dichlorofluorescin diacetate (DCFDA) staining, respectively. The interaction between USP38 and BIRC5 was explored by using co-immunoprecipitation (Co-IP) and the ubiquitination level and stability of BIRC5 were examined by using Western blot. USP38-overexpressing BM-MSC-EVs were produced to treat OGD/R-treated IEC-6 cells. RESULTS: USP38 expression was significantly downregulated in OGD/R-treated IEC-6 cells. Incubation of these cells with BM-MSC-EVs substantially elevated the USP38 expression, resulting in improved viability, reduced apoptosis, enhanced migration, and decreased ROS levels. Furthermore, overexpression of USP38 in BM-MSC-EVs further enhanced their protective effect on OGD/R-treated IEC-6 cells. At the molecular level, USP38 interacts with and stabilizes BIRC5 by decreasing its ubiquitination. Knock-down of BIRC5 abolished the protective effect of excessive USP38 on OGD/R-treated IEC-6 cells. CONCLUSION: USP38 protects intestinal epithelial cells from I/R injury by enhancing the stability of BIRC5.