title: Interleukin-22 Alleviated Palmitate-Induced Endoplasmic Reticulum Stress in INS-1 Cells through Activation of Autophagy.
abstract: OBJECTIVE
  Stimulation with saturated fatty acids has been shown to induce oxidative stress and endoplasmic reticulum (ER) stress in β cells and has been recognized as an important component of the pathogenesis of type 2 diabetes (T2D). Interleukin-22 (IL-22) plays a critical role in preventing β cells from oxidative and ER stress, and autophagy is associated with the survival and function of β cells. However, whether IL-22 alleviates cellular stress through activation of autophagy is unclear. In this study, we investigated the effects of IL-22 on rat insulin-secreting cells and the mechanisms underlying IL-22 and lipotoxicity-induced oxidative and ER stress in vitro.
  
  
  METHODS
  The levels of reactive oxygen species (ROS) were detected by flow cytometry and fluorescence microscopy. The protein expression of glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP), microtubule-associated protein light chain 3B (LC3B) and Bcl-2-interacting myosin-like coiled-coil protein (Beclin-1) were evaluated by western blot. Transmission electron microscopy was utilized to observe the process of autophagy.
  
  
  RESULTS
  Palmitate induced increased levels of ROS and the overexpression of GRP78 and CHOP, whereas these effects were partly reversed by treatment with IL-22. Furthermore, IL-22 upregulated the protein expression of Beclin-1 and the conversion of LC3B-I to LC3B-II. Moreover, the aforementioned effects were partly suppressed by treating cells with 3-methyladenine (3-MA), an autophagy inhibitor.
  
  
  CONCLUSIONS
  Our results suggest that IL-22 alleviated the oxidative and ER stress induced by palmitate, which was likely mediated by autophagy. These findings could facilitate the development of novel therapeutic strategies to suppress the progression of T2D.
authors.affiliation: Department of Endocrinology, Zhujiang Hospital of Southern Medical University, Guangzhou, P. R. China.
authors.forename: Minling
authors.initials: M
authors.lastname: Hu
authors.affiliation: Department of Endocrinology, Zhujiang Hospital of Southern Medical University, Guangzhou, P. R. China.
authors.forename: Shuangli
authors.initials: S
authors.lastname: Yang
authors.affiliation: Department of Endocrinology, Zhujiang Hospital of Southern Medical University, Guangzhou, P. R. China.
authors.forename: Li
authors.initials: L
authors.lastname: Yang
authors.affiliation: Department of Endocrinology, Zhujiang Hospital of Southern Medical University, Guangzhou, P. R. China.
authors.forename: Yanzhen
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: Department of Endocrinology, Zhujiang Hospital of Southern Medical University, Guangzhou, P. R. China.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
mesh_terms: D000818:Animals; D001343:Autophagy; D002460:Cell Line; D059865:Endoplasmic Reticulum Stress; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism*; D007378:Interleukins / Q000494:pharmacology*; D018384:Oxidative Stress; D010168:Palmitates / Q000633:toxicity; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D051742:Transcription Factor CHOP / Q000235:genetics / Q000378:metabolism; D000097043:Interleukin-22; D000091342:Endoplasmic Reticulum Chaperone BiP
chemical_list: D006360:Heat-Shock Proteins; D007378:Interleukins; D010168:Palmitates; D017382:Reactive Oxygen Species; D051742:Transcription Factor CHOP; D000097043:Interleukin-22; C497251:Ddit3 protein, rat; C051684:GRP78 protein, rat; D000091342:Endoplasmic Reticulum Chaperone BiP