Genetic and molecular search for targets of the Tribbles adaptor protein

 描述（由申请人提供）：胰岛素信号传导缺陷对代谢疾病和癌症均有影响。流行病学研究证实了长期的观察，即肥胖个体和2型糖尿病伴高胰岛素血症的患者患各种癌症的风险较高，但这些疾病之间的联系尚不清楚。高胰岛素血症可能直接增加具有高水平胰岛素受体的肿瘤的生长，或间接增加胰岛素样生长因子（IGF）水平，其激活与结肠癌、乳腺癌和甲状腺癌有明确联系的途径。2型糖尿病（T2 D）的患病率在全球人口中迅速增加，但改善饮食和营养的公共计划在很大程度上未能减少这一问题，迫切需要了解癌症进展期间如何调节这一途径。Trib家族成员与代谢缺陷和癌症形成有关。该蛋白家族共有一个保守的激酶系中心结构域，并通过结合关键调控蛋白（包括转录因子、激酶和酶）来连接调节细胞生长、增殖和分化的多种细胞信号传导途径。在人类中，Tribbles 3（Trib 3）水平在胰岛素抵抗和T2 DM患者中异常高，并且Trib 3蛋白变体（Trib 3Q/R85）与易患代谢疾病的人群有关。几种抗癌药物已显示通过TRIB 3上调促进癌细胞死亡，最近的一份报告显示，由于胰岛素信号传导途径的活性增加，Trib 3敲除小鼠表现出癌前病变的加速形成。模式遗传生物提供了一个强大的系统来揭示保守的遗传机制，将胰岛素信号传导与细胞生长和组织稳态联系起来，在过去的15年里，果蝇已被用于研究胰岛素调节代谢和能量稳态的遗传学。在果蝇中，Tribbles结合并阻断cdc 25磷酸酶，cdc 25磷酸酶是细胞增殖的关键触发因素，我们最近发表的数据表明，Trbl通过结合并抑制Akt激酶的活化来拮抗胰岛素信号传导，Akt激酶是胰岛素应答的关键介导物。我们将果蝇Trbl鉴定为胰岛素信号的拮抗剂使我们处于有利地位，可以使用这种简单模式生物中可用的遗传工具来鉴定相互作用的基因、途径和候选药物，以及进行遗传机制快速解剖的机会，这两者在高等模式生物中都不可行。在这里，我们建议寻找新的Trbl途径的组成部分-包括结合伙伴和途径的目标-结合遗传筛选与分子筛选。该提案还开发了一种基于计算机的工具，该工具将用作（1）定量分析细胞生长和增殖的新框架，以及（2）多功能，模块化，开源的算法工具箱，能够通过高通量筛选在整个生物体中发现与各种疾病相关的遗传途径，化学探针和候选药物。我们的目标是使用这个更简单的模型遗传系统，以确定新的保守的Trbl途径的组成部分，调节细胞的生长和增殖。

 DESCRIPTION (provided by applicant): Defects in insulin signaling have impacts on both metabolic disease and cancer. Epidemiological studies confirm long time observations that obese individuals and type 2 diabetics with hyperinsulinimia are at higher risk for various types of cancers, but the link between these disorders are unclear. Hyperinsulinimia may directly increase growth of tumor with high levels of insulin receptor, or indirectly increase Insulin-like Growth Factor (IGF) levels, which activates a pathway with well-established links to colon, breast and thyroid cancers. The prevalence of Type 2 diabetes (T2D) is increasing rapidly in populations worldwide, but public programs to improve diet and nutrition have largely failed to reduce the problem and an urgent need exists to understand how the pathway is modulated during cancer progression. Trib family members have been linked to both metabolic defects and cancer formation. This family of proteins shares a conserved kinase line central domain and functions by binding key regulatory proteins - with targets that include transcription factors, kinases and enzymes - to link multiple cell signaling pathways regulating cell growth, proliferation and differentiation. In humans, Tribbles 3 (Trib3) levels are aberrantly high in sufferers of both insulin resistance and T2DM, and a Trib3 protein variant (Trib3Q/R85) has been linked to populations predisposed to metabolic disease. Several anticancer agents have been shown to promote cancer cell death via TRIB3 upregulation and a recent report shows that Trib3 knockout mice exhibit accelerated formation of premalignant lesions due to increased activity of the insulin signaling pathway. Model genetic organisms offer a powerful system to uncover the conserved genetic mechanisms that connect the insulin signaling to cell growth and tissue homeostasis and over the past fifteen years, Drosophila has been used to study the genetics of insulin-regulated metabolism and energy homeostasis. In Drosophila, Tribbles binds and block cdc25 phosphatase, a key trigger of cell proliferation and our recently published data shows that Trbl antagonizes insulin signaling by binding and inhibiting the activation of Akt kinase, a key mediator of the insulin response. Our identification of fly Trbl as a antagonist of insulin signaling puts us in the advantageous position to use the genetic tools available in this simple model organism to identify interacting genes, pathways and drug candidates that as well as the opportunity to carry out rapid dissection of genetic mechanisms, neither of which is feasible in higher model organisms. Here we propose to search for novel Trbl pathway components - including binding partners and pathway targets - combining a genetic screen with a molecular screens. This proposal also develops a computer-based tool which will serve as (1) a new framework for quantitative analysis of cell growth and proliferation, and (2) a versatile, modular, open-source toolbox of algorithms enabling the discovery of genetic pathways, chemical probes, and drug candidates via high-throughput screens in the whole organism with relevance to a variety of diseases. Our goals are to use this simpler model genetic system to identify new conserved Trbl pathway components regulating cell growth and proliferation.