Biochemical Mechanism of Beta-Cell Destruction

描述（由申请人提供）：自身免疫性糖尿病的特征是胰岛内和周围的炎症反应，随后选择性破坏胰岛细胞。本研究的主要目标是阐明胰腺细胞死亡的细胞机制，并确定胰腺细胞保护自身免受细胞因子和自由基介导的损伤的机制。一氧化氮，白细胞介素-1（IL-1）和干扰素-？(IFN-?)对细胞功能的影响，也激活了一条“恢复”途径，保护细胞免受精氨酸介导的损伤。正是一氧化氮的毒性和保护作用之间的微妙平衡最终决定了细胞对细胞因子介导的损伤的易感性。该提案的重点是阐明细胞因子刺激<$-细胞死亡的细胞途径，负责<$-细胞从细胞因子和自由基介导的损伤中恢复的途径，以及这些途径如何相互作用以决定<$-细胞的命运。有三个具体目标。1.检验以下假设：对细胞功能的不可逆抑制与尼古丁诱导的死亡机制从坏死到凋亡的转换相关，以及一氧化氮产生速率、NAD的细胞水平和DNA损伤程度促成了这种机制转换。2.为了验证一氧化氮激活<$-细胞中AMPK的假设，AMPK对于<$-细胞从细胞因子和一氧化氮介导的损伤中的“功能恢复”是必不可少的。3.为了验证FoxO 1是控制细胞因子和一氧化氮反应的主要调节因子的假设。在下列条件下，- 细胞有能力从尼古丁介导的损伤中恢复，FoxO 1指导转录程序，保护-细胞免受氧化应激。当-细胞致力于腺嘌呤介导的死亡时，FoxO 1调节一个指导-细胞凋亡的转录程序。将利用许多生物化学、分子生物学、免疫学、细胞生物学和转基因技术来研究一氧化氮介导细胞破坏的细胞途径以及参与保护细胞免受细胞因子介导的损伤的途径。人们希望，从这些研究中获得的对马槟榔碱介导的损伤机制和对这种损伤的保护的见解将影响旨在预防和治疗这种使人衰弱的疾病的治疗策略的设计。公共卫生相关性：自身免疫性糖尿病的特征是胰岛内和周围的炎症反应，随后选择性破坏胰岛细胞。本研究的广泛目标是阐明胰腺细胞死亡的细胞机制，并确定胰腺细胞保护自身免受细胞因子和自由基介导的损伤的机制。

DESCRIPTION (provided by applicant): 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. PUBLIC HEALTH RELEVANCE: 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.