title: Bridges between mitochondrial oxidative stress, ER stress and mTOR signaling in pancreatic β cells.
abstract: Pancreatic β cell dysfunction, i.e., failure to provide insulin in concentrations sufficient to control blood sugar, is central to the etiology of all types of diabetes. Current evidence implicates mitochondrial oxidative stress and endoplasmic reticulum (ER) stress in pancreatic β cell loss and impaired insulin secretion. Oxidative and ER stress are interconnected so that misfolded proteins induce reactive oxygen species (ROS) production; likewise, oxidative stress disturbs the ER redox state thereby disrupting correct disulfide bond formation and proper protein folding. mTOR signaling regulates many metabolic processes including protein synthesis, cell growth, survival and proliferation. Oxidative stress inhibits mTORC1, which is considered an important suppressor of mitochondrial oxidative stress in β cells, and ultimately, controls cell survival. The interplay between ER stress and mTORC1 is complicated, since the unfolded protein response (UPR) activation can occur upstream or downstream of mTORC1. Persistent activation of mTORC1 initiates protein synthesis and UPR activation, while in the later phase induces ER stress. Chronic activation of ER stress inhibits Akt/mTORC1 pathway, while under particular settings, acute activation of UPR activates Akt-mTOR signaling. Thus, modulating mitochondrial oxidative stress and ER stress via mTOR signaling may be an approach that will effectively suppress obesity- or glucolipotoxicity-induced metabolic disorders such as insulin resistance and type 2 diabetes mellitus (T2DM). In this review, we focus on the regulations between mTOR signaling and mitochondrial oxidative or ER stress in pancreatic β cells.
authors.affiliation: Institute of Metabolism and Endocrinology, Metabolic Syndrome Research Center, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China; Key Laboratory of Diabetes Immunology, Ministry of Education, National Clinical Research Center for Metabolic Diseases, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.affiliation: Institute of Metabolism and Endocrinology, Metabolic Syndrome Research Center, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China; Key Laboratory of Diabetes Immunology, Ministry of Education, National Clinical Research Center for Metabolic Diseases, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Yang
authors.affiliation: Institute of Metabolism and Endocrinology, Metabolic Syndrome Research Center, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China; Key Laboratory of Diabetes Immunology, Ministry of Education, National Clinical Research Center for Metabolic Diseases, the Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, China. Electronic address: Doctorzhangjj@hotmail.com.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Zhang
mesh_terms: D000818:Animals; D059865:Endoplasmic Reticulum Stress; D006801:Humans; D050417:Insulin-Secreting Cells / Q000378:metabolism* / Q000473:pathology*; D008928:Mitochondria / Q000378:metabolism*; D018384:Oxidative Stress; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D058570:TOR Serine-Threonine Kinases
keywords: ER stress; Mitochondrial oxidative stress; Pancreatic β cells; mTOR