title: Involvement of dynamin-related protein 1 in free fatty acid-induced INS-1-derived cell apoptosis.
abstract: Elevated extracellular free fatty acids (FFAs) can induce pancreatic beta cell apoptosis, thereby contributing to the pathogenesis of type 2 diabetes mellitus (T2D). Mitochondrial dysfunction has been implicated in FFA-induced beta cell apoptosis. However, molecular mechanisms linking mitochondrial dysfunction and FFA-induced beta cell apoptosis are not clear. Dynamin-related protein 1 (DRP-1) is a mitochondrial fission modulator. In this study, we investigated its role in FFA-induced INS-1 beta cell apoptosis. DRP-1 protein was promptly induced in INS-1 cells and rat islets after stimulation by FFAs, and this DRP-1 upregulation was accompanied by increased INS-1 cell apoptosis. Induction of DRP-1 expression significantly promoted FFA-induced apoptosis in DRP-1 WT (DRP-1 wild type) inducible INS-1-derived cell line, but not in DRP-1K38A (a dominant negative mutant of DRP-1) inducible INS-1-derived cell line. To validate these in vitro results, we transplanted DRP-1 WT or DRP-1 K38A cells into renal capsules of streptozotocin (STZ)-treated diabetic mice to study the apoptosis in xenografts. Consistent with the in vitro results, the over-expression of DRP-1 led to aggravated INS-1-derived cell apoptosis triggered by FFAs. In contrast, dominant-negative suppression of DRP-1 function as represented by DRP-1 K38A significantly prevented FFA-induced apoptosis in xenografts. It was further demonstrated that mitochondrial membrane potential decreased, while cytochrome c release, caspase-3 activation, and generation of reactive oxygen species (ROS) were enhanced by the induction of DRP-1WT, but prevented by DRP-1 K38A in INS-1-derived cells under FFA stimulation. These results indicated that DRP-1 mediates FFA-induced INS-1-derived cell apoptosis, suggesting that suppression of DRP-1 is a potentially useful therapeutic strategy for protecting against beta cell loss that leads to type 2 diabetes.
authors.affiliation: Institute of Clinical Medical Sciences, China-Japan Friendship Hospital, Beijing, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Peng
authors.forename: Xiuli
authors.initials: X
authors.lastname: Men
authors.forename: Wenjian
authors.initials: W
authors.lastname: Zhang
authors.forename: Haiyan
authors.initials: H
authors.lastname: Wang
authors.forename: Shiqing
authors.initials: S
authors.lastname: Xu
authors.forename: Qing
authors.initials: Q
authors.lastname: Fang
authors.forename: Honglin
authors.initials: H
authors.lastname: Liu
authors.forename: Wenying
authors.initials: W
authors.lastname: Yang
authors.forename: Jinning
authors.initials: J
authors.lastname: Lou
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D034281:Dynamins / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D005434:Flow Cytometry; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D007328:Insulin / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000502:physiology*; D051379:Mice; D046529:Microscopy, Electron, Transmission; D051381:Rats; D014183:Transplantation, Heterologous
chemical_list: D005230:Fatty Acids, Nonesterified; D007328:Insulin; C519851:Dnm1l protein, rat; D034281:Dynamins