Biochemical Mechanism of Beta-Cell Destruction

自身免疫性糖尿病的特点是胰岛内部和周围的炎症反应，

Autoimmune diabetes is characterized by an inflammatory reaction in and around pancreatic islets, followed by selective destruction of -cells. The broad goals of this research are to elucidate the cellular mechanisms that are responsible for pancreatic -cells death and to identify mechanisms by which -cells protect themselves against cytokine- and free radical-mediated damage. Nitric oxide, the primary mediator of the inhibitory actions of interleukin-1 (IL-1) and interferon- (IFN-) on -cell function, also activates a "recovery" pathway that protects -cells from cytokine-mediated damage. It is the delicate balance between the toxic and protective actions of nitric oxide that ultimately determine the susceptibility of -cells to cytokine- mediated damage. This proposal focuses on elucidating the cellular pathways by which cytokines stimulate - cell death, the pathways responsible for -cell recovery from cytokine- and free radical-mediated damage, and how these pathways interact to determine -cell fate. There are three specific aims. 1. To test the hypothesis that irreversible inhibition of -cell function is associated with a switch in the mechanism of cytokine-induced death from necrosis to apoptosis and that the rate of nitric oxide production, the cellular levels of NAD, and the extent of DNA damage contribute to this mechanistic switch. 2. To test the hypothesis that nitric oxide activates AMPK in -cells and that AMPK is essential for the "functional recovery" of -cells from cytokine- and nitric oxide-mediated damage. 3. To test the hypothesis that FoxO1 is a primary regulator controlling the response of -cells to cytokines and nitric oxide. Under conditions in which -cells have the ability to recover from cytokine-mediated damage, FoxO1 directs a transcriptional program affording -cells protection from oxidative stress. When -cells are committed to cytokine-mediated death, FoxO1 regulates a transcriptional program that directs -cell apoptosis. A number of biochemical, molecular biological, immunological, cell biological, and transgenic techniques will be utilized to investigate the cellular pathways through which nitric oxide mediates -cell destruction and the pathways that participate in the protection of -cells from cytokine-mediated damage. It is hoped that insights into the mechanisms of cytokine-mediated damage and protection from this damage gained from these studies will influence the design of therapeutic strategies aimed at the prevention and treatment of this debilitating disorder.