Mechanisms of fat regulation by conserved anti-obesity genes

肥胖症影响着大多数美国成年人，对人类健康产生了多种显著的有害影响。 尽管遗传背景在肥胖中起着主要作用，但只有少数人类基因， 易患肥胖症的个体已经被确定。了解控制储存的途径 身体脂肪对于精确定位可能导致这种疾病易感性的基因至关重要。长期目标是 以确定其活性可以被修改以预防或治疗人类肥胖的基因。这个的目标 应用是阐明相关的RNA结合蛋白Spen和Nito调节的机制， 肥胖，并确定其他候选人的细胞自主调节肥胖。一个果蝇模型 已经开发了解剖基因功能的组织特异性，在调节身体脂肪水平，以及 分析行为改变的贡献并直接测量脂肪率的新工具 加入商店。一种使用培养细胞的补充方法将直接转化研究中的发现。 果蝇模型在哺乳动物脂肪储存中的功能。核心假设是，基因自主作用于 果蝇的脂肪储存组织（脂肪体，FB）控制身体脂肪的水平将发挥保守的作用， 哺乳动物脂肪储存这一想法得到了申请人先前成功鉴定此类基因的支持， 以及分析特定候选基因的初步数据，比如Spen。该项目的基本原理是， 脂肪储存组织中的调节途径必须响应生物体的提示以控制储存脂肪的水平， 确定在这些途径中起作用的关键基因可能直接转化为对遗传学的深入了解， 人类肥胖的易感性该模型将通过追求三个具体目标进行测试：（1）测试 Spen和Nito以相反的方式调节身体脂肪。(2)测试的假设 Spen/Nito通过结合特异性RNA来改变基因表达来调节能量平衡;以及（3）鉴定 候选基因的新的，保守的自主调节脂肪储存。在目标1中，我们将确定 缺乏Spen和/或Nito的果蝇幼虫中导致脂肪改变的缺陷的机制基础， 已知调节其他途径转录输出的同一家族蛋白质，但以前从未有过 与控制肥胖有关。在目标2中，我们测试了Spen和Nito将特定RNA结合到靶点的模型。 用于转录控制的特定代谢靶基因。在Aim 3中，果蝇基因的小鼠直系同源物， 直接调节FB中脂肪储存的基因（包括Shep、Rala和NFAT）将在培养的 小鼠脂肪细胞，以确定那些也控制哺乳动物脂肪储存在自主的方式。这 创新的方法组合将揭示基因的新作用，这些基因在脂肪调节中的功能是 目前未知。这一建议的意义在于它可能阐明一个新的途径控制 脂肪储存通过RNA结合蛋白，并表征其他候选肥胖基因，提供了显着的 深入了解这种疾病的多基因性质，并确定未来治疗的新靶点。

Obesity affects a majority of American adults, with diverse and significant detrimental effects on human health. Despite a major role for genetic background in obesity, only a small number of the human genes that predispose individuals to obesity have been identified. Understanding the pathways that control storage of body fat will be crucial for pinpointing genes likely to cause susceptibility to this disease. The long-term goal is to identify genes whose activities can be modified to prevent or treat human obesity. The goals of this application are to elucidate the mechanism by which the related RNA-binding proteins Spen and Nito regulate adiposity, and to identify other candidates for cell-autonomous regulation of adiposity. A fruit fly model has been developed to dissect the tissue specificity of gene function in the regulation of body fat levels, as well as new tools to parse out the contributions of behavioral alterations and to directly measure rates of fat incorporation into stores. A complementary approach using cultured cells will directly translate findings in the fly model to functions in mammalian fat storage. The central hypothesis is that genes acting autonomously in the fruit fly fat-storage tissue (the fat body, FB) to control levels of body fat will play conserved roles in mammalian fat storage. This idea is supported by the applicant's previous success in identifying such genes, and by preliminary data analyzing specific candidate genes, like Spen. The rationale for this project is that regulatory pathways in fat storage tissues must respond to organismal cues to control levels of stored fat, and that identifying key genes acting in these pathways may translate directly to insights into genetic predispositions to human obesity. This model will be tested by pursuing three specific aims: (1) Test the hypothesis that Spen and Nito function in an opposing manner to regulate body fat. (2) Test the hypothesis that Spen/Nito regulate energy balance by binding specific RNAs to alter gene expression; and (3) Identify candidate genes for novel, conserved autonomous regulators of fat storage. In Aim 1, we will determine the mechanistic basis of defects leading to altered fat in fly larvae lacking Spen and/or Nito, two RNA-binding proteins in the same family known to modulate transcriptional output of other pathways but never before implicated in the control of adiposity. In Aim 2, we test a model that Spen and Nito bind specific RNAs to target specific metabolic target genes for transcriptional control. In the Aim 3, the mouse orthologs of fly genes that directly regulate fat storage in the FB (including Shep, Rala and NFAT) will be analyzed functionally in cultured mouse adipocytes to identify those that also control mammalian fat storage in an autonomous manner. This innovative combination of approaches will uncover new roles for genes whose functions in fat regulation are currently unknown. The significance of this proposal lies in its potential to elucidate a new pathway controlling fat storage via RNA-binding proteins, and to characterize other candidate obesity genes, providing significant insights into the multigenic nature of this disease, and identifying new targets for future treatments.