Biochemical Mechanism of Beta-Cell Destruction

描述(申请人提供)：自身免疫性糖尿病的特征是在胰岛内和周围的炎症反应中发生的细胞的选择性破坏。在这一过程中释放的炎性细胞因子会损害细胞功能，并可能导致细胞死亡。在2型糖尿病的发展过程中，细胞因子也与功能性细胞团的丧失有关。这项研究的主要目标是阐明细胞因子治疗后胰腺细胞功能损害和死亡的细胞机制，并确定细胞保护自己免受细胞因子介导的损伤的途径。活性氮(RNS；例如，一氧化氮)是白细胞介素1(IL-1)和干扰素(干扰素)对细胞功能和活性的破坏作用的主要介体。我们已经证明，一氧化氮还可以激活“保护通路”，导致胰岛素分泌功能的恢复、线粒体氧化代谢和受损DNA的修复。正是RNS的毒性和保护作用之间的微妙平衡，由细胞对细胞因子的反应产生，最终决定了这些细胞的生存或死亡。这项提议将阐明细胞因子治疗后控制细胞命运的途径。有三个特定的目的：1)检验细胞对细胞因子处理的反应取决于a)产生的活性氧物种(ROS)或活性氮物种(RNS)的形式，以及b)ROS和RNS选择性地调节控制细胞修复/保护通路或激活细胞死亡通路的信号级联的能力；2)检验毛细血管扩张性共济失调(ATM)在调节细胞对细胞因子和一氧化氮介导的损伤的反应(S)中起主要作用的假设；3)验证SIRT1激活状态决定细胞对细胞因子处理的反应是通过诱导“保护通路”还是通过刺激细胞死亡级联反应的假说。将利用生化、分子、免疫学、细胞生物学和转基因技术来研究一氧化氮及其活性中间体介导细胞损伤的细胞途径，以及参与保护细胞免受细胞因子诱导的损伤的途径。希望从这些研究中获得的对控制细胞对细胞因子反应的机制的洞察将影响旨在减轻糖尿病发展过程中功能性细胞团损失的治疗策略的设计。

DESCRIPTION (provided by applicant): Autoimmune diabetes is characterized by the selective destruction of ¿-cells that occurs during an inflammatory reaction in and around pancreatic islets. Inflammatory cytokines, released during this process, impair ¿-cell function and can induce ¿-cell death. Cytokines have also been implicated in the loss of functional ¿-cell mass during the development of type 2 diabetes. The broad goals of this research are to elucidate the cellular mechanisms that are responsible the functional impairment and death of pancreatic ¿-cell following cytokine treatment, and to identify pathways by which ¿-cells protect themselves against cytokine-mediated damage. Reactive nitrogen species (RNS; e.g., nitric oxide) are primary mediators of the damaging actions of interleukin-1 (IL-1) and interferon (IFN)-??on ¿-cell function and viability. We have shown that nitric oxide can also activate "protective pathways" that lead to the recovery of insulin secretory function, mitochondrial oxidative metabolism, and the repair of damaged DNA. It is the delicate balance between the toxic and protective actions of RNS, produced by ¿-cells in response to cytokines that ultimately determines whether these cells survive or die. This proposal will elucidate the pathways that control ¿-cell fate following cytokine treatment. There are three specific aims: 1) To test the hypothesis that the response of ¿-cells to cytokine treatment is determined by a) the form of reactive oxygen species (ROS) or reactive nitrogen species (RNS) produced, and b) the ability of ROS and RNS to selectively regulate signaling cascades that control cellular repair/protective pathways or activate cell death cascades; 2) To test the hypothesis that Ataxia telangiectasia mutated (ATM) plays a primary role in regulating the response(s) of ¿-cells to cytokine- and nitric oxide-mediated damage; 3) To test the hypothesis that the activation status of SIRT1 determines whether ¿-cells respond to cytokine treatment with the induction of "protective pathways" or the stimulation of cell death cascades. A number of biochemical, molecular, immunological, cell biological and transgenic techniques will be utilized to investigate the cellular pathways through which nitric oxide and its reactive intermediates mediate ¿-cell damage and the pathways that participate in the protection of ¿-cells from cytokine-induced damage. It is hoped that insights into the mechanisms controlling the response of ¿-cells to cytokines that are gained from these studies will influence the design of therapeutic strategies aimed at attenuating the loss of functional ¿-cell mass during the development of diabetes.