Manipulating islet GPCR activity to promote beta cell proliferation and survival

项目总结/摘要 T2 D发病率随年龄增长而增加，部分原因是β细胞应答能力下降 随着年龄的增长，我们的实验室将FoxM 1转录因子鉴定为 β细胞复制和存活的关键调节因子。胰岛中Foxm 1表达下降 在小鼠和人类中，随着年龄的增长，但在老年小鼠β细胞中FoxM 1的激活增加了β- 细胞增殖和质量。RNA测序显示，FoxM 1在β细胞中过表达， 细胞减少EP 3的表达，增加EP 4的表达，两种G蛋白- 偶联前列腺素E2（PGE 2）受体。在来自小鼠和人的分离的胰岛中，我们 发现药理学抑制EP 3或激活EP 4促进β细胞 增殖和生存。目前的建议利用体内小鼠模型， 人胰岛移植物和来自正常人的离体胰岛培养物， 2型糖尿病，以确定介导影响的下游信号通路 抑制EP 3或激活EP 4。使用离体处理的小鼠的磷蛋白阵列 在胰岛中，我们确定PLCγ和PKA作为EP 3抑制或EP 4 激活，分别。在目前的建议，我们探讨的hypopothesis，EP 3 阻断（通过PLCγ起作用）或EP 4激活（通过PKA起作用）将改善 糖尿病并通过增加胰岛素分泌来增强体内人胰岛移植， 以及增强β-细胞增殖和存活。我们认为FoxM 1直接激活 EP 4，同时抑制EP 3的表达。这些研究旨在确定分子 目的是增强β细胞的功能、增殖和存活， 功能性β细胞群。

Project Summary/Abstract T2D incidence increases with age, in part due to a decreased ability of β cells to respond to proliferative cues as they get older. Our lab identified the FoxM1 transcription factor as a critical regulator of β-cell replication and survival. Foxm1 expression in islets declines with age in mice and humans, but activation of FoxM1 in older mouse β cells increases β- cell proliferation and mass. RNA-sequencing revealed that FoxM1 over-expression in β cells decreases expression of EP3 and increases expression of EP4, two G protein- coupled prostaglandin E2 (PGE2) receptors. In isolated islets from mouse and human, we found that pharmacological inhibition of EP3 or activation of EP4 promotes β-cell proliferation and survival. The current proposal makes use of in vivo mouse models, human islet transplants and ex vivo islet cultures from humans with normoglycemia and Type 2 diabetes to determine the downstream signaling pathways that mediate the effects of inhibiting EP3 or activating EP4. Using phosphoprotein arrays of ex vivo treated mouse islets, we identified PLCγ and PKA as acting downstream of EP3 inhibition or EP4 activation, respectively. In the current proposal we explore the hyopothesis that EP3 blockade (working through PLCγ) or EP4 activation (working through PKA) will ameliorate diabetes and enhance human islet transplantation in vivo by increasing insulin secretion, and enhancing β-cell proliferation and survival. We propose that FoxM1 directly activates EP4 while repressing EP3 expression. These studies are designed to identify molecular targets to enhance function, proliferation and survival of β cells with the goal of increasing functional β cell mass.