Molecular Mechanisms of Dysfunctional Prostaglandin Signaling in the Beta-Cell

描述（由申请人提供）：2型糖尿病（T2 D）是一种昂贵且复杂的慢性疾病，也是一个严重的公共卫生问题。今天的儿童一生中患糖尿病的风险接近50%。因此，开发预防T2 D的新方法以及识别和适当治疗T2 D患者是非常及时和重要的。T2 D的病理生理学越来越多地与炎症分子如前列腺素E2（PGE 2）（一种主要的花生四烯酸代谢物）相关联。β细胞本身表达合成PGE 2所需的所有酶，PGE 2被认为以自分泌或旁分泌方式起作用以调节胰岛素分泌，甚至可能调节β细胞生长、增殖和存活。即使该途径在正常和功能障碍的β细胞中具有明确的重要性，也很少有研究探索在β细胞水平上调节PGE 2的产生或信号传导的影响，部分原因是对这些途径中重要的分子机制的认识不足。我们的长期目标是充分表征正常和糖尿病β细胞中的PGE 2合成和信号通路，确定糖尿病状态下功能失调的步骤，并最终调节这些步骤以达到预防和治疗目的。这项工作的总体目标是阐明在不同步骤中的关键分子相互作用，这些步骤仍然相对未被表征，其基本原理是，在获得对这一重要β细胞信号传导途径的完整理解时，我们将能够更好地利用新颖和创新的方法在T2 D预防和治疗中靶向功能障碍的β细胞。我们的中心假设是PGE 2合成和信号传导途径是糖尿病β细胞功能障碍的关键介质，并且可以特异性地靶向除了充分研究的环氧合酶-2（考克斯-2;或胰高血糖素-内过氧化物酶合酶2，PTGS 2）步骤之外的一个或多个关键步骤。我们将检验我们的中心假设，从而通过追求以下三个具体目标实现本申请的目的：（1）鉴定花生四烯酸膜掺入和释放在糖尿病β细胞功能障碍中的作用;（2）确定PGE 2受体的EP 3同种型的C末端剪接变体在偶联G蛋白信号传导配偶体中的作用;以及（3）阐明EP 3下游促进β细胞功能、复制和存活的信号传导机制。随着这些目标的完成，我们预计将更全面地了解从花生四烯酸到PGE 2和其他代谢产物的途径，包括PGE 2激活其细胞受体如何影响糖尿病β细胞。这些结果是预期的。 对该领域产生重要的积极影响，如描绘这一长期已知但相对 通过研究未表征的途径，我们可能能够融合文献中的不一致结果，并揭示和确认预防和治疗T2 D的新靶点。

DESCRIPTION (provided by applicant): Type 2 diabetes (T2D) is a costly and complex chronic illness and a serious public health problem. The children of today have an overall lifetime risk of developing diabetes of nearly 50%. Therefore, developing new methods for preventing T2D and identifying and properly treating T2D patients is very timely and of great significance. The pathophysiology of T2D is increasingly being linked with inflammatory molecules such as prostaglandin E2 (PGE2), a major arachidonic acid metabolite. Beta-cells themselves express all of the enzymes required for synthesis of PGE2, which is thought to act in an autocrine or paracrine fashion to regulate insulin secretion and possibly even beta-cell growth, proliferation, and survival. Even with the clear importance of this pathway in the normal and dysfunctional beta-cell, few studies have explored the impact of modulating the production or signaling of PGE2 at the level of the beta-cell, in part because of insufficient knowledge of th molecular mechanisms important in these pathways. Our long-term goal is to fully characterize the PGE2 synthesis and signaling pathways in the normal and diabetic beta-cell, determining steps that become dysfunctional in the diabetic state, and ultimately modulating these steps for preventative and therapeutic purposes. The overall objective of this work is to elucidate critical molecular interactions at distinct steps that have remained relatively uncharacterized, with the rationale that in gaining a complete understanding of this important beta-cell signaling pathway, we will be better able to target the dysfunctional beta-cell in T2D prevention and therapy using novel and innovative approaches. Our central hypothesis is that the PGE2 synthesis and signaling pathway is a critical mediator of diabetic beta-cell dysfunction and can be specifically targeted at one or more key steps besides the well-studied cyclooxygenase-2 (COX-2; or prostaglandin-endoperoxidase synthase 2, PTGS2) step. We will test our central hypothesis and, thereby, accomplish the objective of this application, by pursuing the following three specific aims: (1) Identify the role of arachidonic acid membrane incorporation and release in diabetic beta-cell dysfunction; (2) Determine the role of C-terminal splice variants of the EP3 isoform of the PGE2 receptor in coupling to G-protein signaling partners; and (3) Elucidate the signaling mechanisms downstream of EP3 in promoting beta-cell function, replication, and survival. With the completion of these aims, we anticipate a much more complete understanding of the pathway from arachidonic acid to PGE2 and other metabolites, including how PGE2 activation of its cellular receptor impacts on the diabetic beta-cell. Such results are anticipated to have an important positive impact on the field, as in delineating this long-known but relatively uncharacterized pathway we may be able to meld the discrepant results in the literature and reveal and confirm new targets for the prevention and therapy of T2D.