Unfolded Protein Response: Regulator of Human beta-cells

描述(由申请人提供)： 促炎细胞因子被认为参与了移植后功能性胰岛质量的丧失和移植物排斥反应。人类胰岛移植的另一个并发症是缺乏足够的胰岛质量，部分原因是分离后胰岛细胞的凋亡。这项研究的主要目标是阐明细胞因子介导胰岛β细胞破坏的生化机制，并确定从身体捐赠者分离后导致胰岛质量损失的机制。内质网(ER)应激激活一种未折叠蛋白反应(UPR)，从而诱导细胞凋亡。最近，我们发现一氧化氮是白细胞介素1(IL-1)和干扰素-γ(干扰素-γ)抑制啮齿动物和人类β细胞功能的主要介质，是β细胞中UPR的激活剂。这项建议将解决一种假设，即在人类胰岛分离期间，对细胞因子或一氧化氮治疗或应激反应的UPR激活时间延长会导致胰岛β细胞的凋亡丢失。有两个具体目标： 1.验证一氧化氮激活人胰岛UPR(或内质网应激)通路以及该通路的长时间激活导致(-)细胞凋亡丢失的假说。建议的实验将评估细胞因子和一氧化氮供体对UPR激活的影响，并确定抑制UPR是否保护β细胞免受细胞因子介导的死亡。 2.验证分离过程中胰岛损伤诱导内质网应激和UPR激活的假说，以及UPR激活是导致分离过程中胰岛质量损失的机制之一。拟议的实验将检查人胰岛分离对UPR激活的影响，并确定抑制UPR是否可以防止或减轻分离后胰岛的丢失。 许多生化、分子生物学、免疫学和组织化学技术将被用来研究在细胞因子治疗或人类胰岛分离后，UPR激活作为一种潜在的β细胞凋亡介体的作用。从这些研究中获得的对细胞因子介导的β细胞凋亡机制的深入了解，以及分离后胰岛质量损失的相关机制将影响旨在减轻胰岛移植排斥反应的治疗策略的设计，并增加可供移植的胰岛的功能质量。

DESCRIPTION (provided by applicant): Proinflammatory cytokines are believed to participate in the loss of functional islet mass as well as graft rejection following transplantation. Also complicating human islet transplantation is the lack of sufficient islet mass due, in part, to islet cell apoptosis following isolation. The broad goals of this research are to elucidate the biochemical mechanisms by which cytokines mediate pancreatic beta-cell destruction and to identify the mechanisms that mediate the loss of islet mass following isolation from cadaver donors. Endoplasmic reticulum (ER) stress activates an unfolded protein response (UPR) that is known to induce apoptosis. Recently, we have shown that nitric oxide, a primary mediator of the inhibitory actions of interleukin-1 (IL-1) and interferon-gamma(IFN-gamma) on rodent and human beta-cell function, is an activator of the UPR in beta-cells. This proposal will address the hypothesis that prolonged UPR activation in response to cytokine or nitric oxide treatment or stress during human islet isolation results in the apoptotic loss of pancreatic beta-cells. There are two specific aims: 1. To test the hypothesis that nitric oxide activates the UPR (or ER stress) pathway in human islets and that prolonged activation of this pathway results in the apoptotic loss of (-cells. Experiments proposed will evaluate the effects of cytokines and nitric oxide donors on UPR activation and determine if UPR inhibition protects beta-cells from cytokine-mediated death. 2. To test the hypothesis that islet damage during isolation induces ER stress and UPR activation, and that UPR activation is one mechanism responsible for the loss of islet mass during isolation. Proposed experiments will examine the effects of human islet isolation on UPR activation and determine whether UPR inhibition prevents or attenuates the loss of islets following isolation. A number of biochemical, molecular biological, immunological, and histochemical techniques will be utilized to investigate the role of UPR activation as one potential mediator of beta-cell apoptosis following cytokine treatment or following human islet isolation. It is hoped that insights into the mechanisms of cytokine-mediated beta-cell apoptosis, and the mechanisms associated with the loss of islet mass following isolation gained from these studies will influence the design of therapeutic strategies aimed at the attenuation of islet graft rejection and increase the functional mass of islets available for transplantation.