Mammalian Sir2 Function in Pancreatic Beta Cells

描述(申请人提供)：这项建议的长期目标是了解哺乳动物Sir2在通过胰岛素/IGF-I系统对哺乳动物衰老和长寿的内分泌控制中的功能。最近的研究表明，胰岛素/IGF-I信号通路在调节蠕虫、苍蝇和小鼠的衰老和寿命方面发挥着关键作用。此外，卡路里限制延长了多种生物的寿命，降低了哺乳动物的血液胰岛素和IGF-I水平。依赖于烟酰胺腺嘌呤二核苷酸(NAD)的Sir2(沉默信息调节因子2)脱乙酰酶已被证明与酵母和线虫的衰老和长寿机制有关。我们发现有证据表明哺乳动物Sir2在调节胰岛β细胞转录方面起着重要作用。根据我们在这项提议中提出的初步发现，我们假设哺乳动物Sir2通过其依赖于NAD的脱乙酰酶活性来调节胰腺b细胞胰岛素产生功能所需的特定基因的转录，从而控制葡萄糖代谢、衰老和寿命。1)检测携带Sir2基因或siRNA的重组腺病毒感染的小鼠原代胰岛中胰岛素基因的表达和胰岛素分泌；2)通过检测重要的转录调控因子在β细胞中的表达和修饰，阐明哺乳动物Sir2介导的转录调控的分子机制；3)通过测量β细胞特异性Sir2转基因小鼠中葡萄糖稳态的多个生理参数，研究哺乳动物Sir2在b细胞中的功能。这些研究应该为理解哺乳动物Sir2在β细胞中的功能、哺乳动物的葡萄糖代谢和长寿控制提供一个分子框架。

DESCRIPTION (provided by applicant): The long-term objectives of this proposal are to understand the function of mammalian Sir2 in the endocrine control of aging and longevity by the insulin/IGF-I system in mammals. Recent studies have demonstrated that insulin/IGF-I signaling pathways play critical roles in regulating the pace of aging and longevity in worms, flies and mice. Additionally, caloric restriction, which extends life span in a wide variety of organisms, reduces blood insulin and IGF-I levels in mammals. The Sir2 (silent information regulator 2) nicotinamide adenine dinucleotide (NAD)-dependent deacetylases have been demonstrated to link glucose metabolism to the mechanism of aging and longevity in yeast and C. elegans. We have found evidence that mammalian Sir2 plays an important role in regulating transcription in pancreatic beta cells. Based on our preliminary findings presented in this proposal, it is hypothesized that mammalian Sir2 controls glucose metabolism, aging and longevity by regulating transcription of specific genes required for the insulin-producing function of pancreatic b cells through its NAD-dependent deacetylase activity. This hypothesis will be addressed by the following specific aims: 1) examine insulin gene expression and insulin secretion in mouse primary islets infected with recombinant adenovirus carrying Sir2 cDNA or siRNA, 2) elucidate the molecular mechanism of mammalian Sir2-mediated transcriptional regulation by examining expression and modification of important transcriptional regulators in beta cells, and 3) examine the in vivo function of mammalian Sir2 in b cells by measuring multiple physiological parameters for glucose homeostasis in beta cell-specific Sir2 transgenic mice. These studies should provide a molecular framework to understand the function of mammalian Sir2 in beta cells, glucose metabolism and longevity control in mammals.