GPCR - Linked RhoGEFs in Tumor Growth and Metastasis

项目总结 G蛋白偶联受体(Gpcr)以其转换细胞外信息的能力而闻名。 在激素、气味和多肽中编码，通过调节细胞内稳态的快速变化 细胞内效应酶和通道的功能。然而，对人类癌症基因组的分析表明 一些GPCR信号通路导致持续的信号，在病理环境中与肿瘤有关 生长和转移。这种途径的一个共同特征是由DBL家族激活Rho GTP酶 Rho鸟嘌呤核苷酸交换因子(RhoGEF)。TrioC亚家族(由Trio、Kalirin和 P63Rhogef)被异源三聚体GαQ亚基直接激活，与眼部黑色素瘤密切相关 和白血病。P-Rex亚家族(由P-Rex1和P-Rex2组成)通过直接作用协同激活 与GBetagamma和脂质PIP3相互作用，并在许多乳腺和前列腺肿瘤中过度表达，其中 起着转移性的作用。因此，TRIO和P-REx1/2已成为重要的化疗靶点。事实是 到目前为止，这些酶的分子和细胞调控机制尚不清楚 理解阻止了设计新的治疗方法的理性方法。通过确定 这些罗氏亚家族成员的结晶学和低温电子显微镜结构，这项提议寻求 定义激活的分子机制，并通过一系列功能分析来检验这些假说。 同时，我们将我们的泛函分析扩展到模型细胞系统，以了解如何构成活性 异三聚体G蛋白和GPCRs促进癌细胞生长(如眼部黑色素瘤)和转移(AS 在乳腺癌中)通过TrioC和P-Rex亚家族RhoGEF。通过了解监管的基础 异三聚体G蛋白在体外和相关细胞环境中的Rhogef活性，我们将加速 发现可用于抗击癌症的新的生物学见解和新的治疗策略。

PROJECT SUMMARY G protein-coupled receptors (GPCRs) are well known for their ability to convert extracellular information encoded in hormones, odorants, and peptides into rapid changes in cellular homeostasis by modulating the function of effector enzymes and channels in the cell. However, analysis of human cancer genomes indicates that some GPCR signaling pathways lead to sustained signals that in pathological settings are linked to tumor growth and metastasis. A common feature of such pathways is the activation of Rho GTPases by Dbl family Rho guanine nucleotide exchange factors (RhoGEFs). The TrioC subfamily (composed of Trio, Kalirin, and p63RhoGEF) is directly activated by heterotrimeric Gαq subunits and is strongly implicated in ocular melanoma and leukemia. The P-Rex subfamily (composed of P-Rex1 and 2) is activated synergistically by direct interactions with GBetagamma and the lipid PIP3, and is overexpressed in many breast and prostate tumors where it plays a metastatic role. Trio and P-Rex1/2 have thus emerged as important chemotherapeutic targets. The fact that the molecular and cellular mechanisms underlying regulation of these enzymes are as of yet poorly understood prevents a rational approach to the design of novel therapeutic approaches. By determining crystallographic and cryo-EM structures of members from these RhoGEF subfamilies, this proposal seeks to define molecular mechanisms of activation and to test these hypotheses through a battery of functional assays. In parallel, we extend our functional analysis into model cell systems to understand how constitutively active heterotrimeric G proteins and GPCRs promote cancer cell growth (as in ocular melanoma) and metastasis (as in breast cancer) via TrioC and P-Rex subfamily RhoGEFs. By understanding the basis for regulation of RhoGEF activity by heterotrimeric G proteins both in vitro and in relevant cellular contexts, we will accelerate discovery of new biological insights and novel therapeutic strategies that can be used to combat cancer.