Genetic and molecular search for targets of the Tribbles adaptor protein

 描述(由申请人提供)：胰岛素信号的缺陷对代谢性疾病和癌症都有影响。流行病学研究证实了长期的观察结果，即肥胖者和患有高胰岛素血症的2型糖尿病患者患各种癌症的风险更高，但这些疾病之间的联系尚不清楚。高胰岛素血症可通过高水平的胰岛素受体直接促进肿瘤生长，或间接增加胰岛素样生长因子(IGF)水平，从而激活与结肠癌、乳腺癌和甲状腺癌密切相关的通路。2型糖尿病(T2D)在全球人群中的患病率正在迅速上升，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，迫切需要了解该途径在癌症进展过程中是如何调节的。TRIB家族成员被认为与代谢缺陷和癌症的形成有关。这一蛋白家族共享一个保守的激酶线中心结构域，通过结合关键调节蛋白-与包括转录因子、激酶和酶在内的靶标-连接调节细胞生长、增殖和分化的多个细胞信号通路来发挥功能。在人类中，Tribble 3(Trib3)水平在胰岛素抵抗和T2 DM患者中异常高，Trib3蛋白变体(Trib3Q/R85)已被认为与易患代谢性疾病的人群有关。几种抗癌药物已被证明通过上调TRIB3来促进癌细胞死亡，最近的一份报告显示，Trib3基因敲除小鼠由于胰岛素信号通路的活性增加而加速了癌前病变的形成。模式遗传生物提供了一个强大的系统来揭示将胰岛素信号与细胞生长和组织稳态联系起来的保守遗传机制，在过去的15年里，果蝇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，Tribble结合并阻断CDC25磷酸酶，CDC25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通过结合和抑制胰岛素反应的关键介质Akt激酶的激活来拮抗胰岛素信号转导。我们发现Fly TRBL是胰岛素信号的拮抗剂，这使我们处于有利地位，可以使用这个简单的模式生物中可用的遗传工具来识别相互作用的基因、途径和候选药物，以及进行遗传机制的快速剖析的机会，这在高等模式生物中都是不可行的。在这里，我们建议寻找新的TRBL途径组件-包括结合伙伴和途径靶标-结合遗传筛选和分子筛选。这项提议还开发了一个基于计算机的工具，它将作为(1)一个新的细胞生长和增殖定量分析框架，以及(2)一个通用的、模块化的、开放源码的算法工具箱，能够通过与各种疾病相关的整个生物体的高通量筛选来发现遗传途径、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来识别调节细胞生长和增殖的新的保守的TRBL途径组件。

 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.