Structure and Function of the SHOC2 Holophosphatase Complex in RAS-driven Cancer

项目概要/摘要： 发现RAS蛋白在癌症的临床病例中频繁突变。有效靶向治疗 针对RAS及其下游途径的研究一直备受追捧。在RAS效应器中， RAF/丝裂原活化蛋白激酶（MAPK）级联反应已被证明是重要的繁殖 RAS下游的致癌信号传导。已经开发了许多有希望的靶向疗法， 直接抑制突变的KRAS和MAPK成员，但由于抗性机制而受到限制。 SHOC 2是近年来发现的一种在多种RAS突变体中具有潜在的合成致死性的脆弱性。 包括RAS驱动的白血病/黑色素瘤，并促进癌症对许多RAS/MAPK的耐药性 抑制剂的SHOC 2是结合RAS和PP 1C以形成三元全磷酸酶复合物的支架， 使RAF蛋白上的抑制性“S259”去磷酸化并使MAPK信号传导成为可能。将SHOC 2实现为 治疗目标，并告知未来的努力，合理设计抑制剂对复杂的，一个深刻的 需要理解控制复杂组装和功能的SHOC 2结构特征。我们有 现在解决了SHOC 2复杂的结构，并已概述了几乎所有的功能后果， 通过深度突变扫描在SHOC 2的每个位置上可能的氨基酸取代。 这些发现强调了SHOC 2的新结构特征，这些特征可能对治疗靶点很重要。 RAS突变型癌症。本提案中概述的研究将在这项工作的基础上开展，其目的是：（1）界定和 验证SHOC 2全磷酸酶复合物对RAF底物的特异性的结构特征，和（2） 鉴定调节SHOC 2功能的新型翻译后修饰。我在K99接受的培训 我还将在结构生物学、蛋白质组学和泛素生物学方面获得必要的专业知识 使我具备教学/实验室管理经验，以便我能有效地领导我自己的独立工作。 研究计划。K99/R 00将帮助我实现长期目标， 实验室专注于研究新的RAS相关的脆弱性和耐药机制， 细胞信号传导和蛋白质结构-功能的系统方法。

Project Summary/Abstract: RAS proteins are found to be frequently mutated in clinical cases of cancer. Effective targeted therapies against RAS and its downstream pathways have been highly sought after. Among the RAS effectors, the RAF/mitogen-activated protein kinase (MAPK) cascade has been shown to be important for propagating oncogenic signaling downstream of RAS. Many promising targeted therapies have been developed that directly inhibit mutant KRAS and MAPK members but have been limited due to resistance mechanisms. SHOC2 has been recently found to be a potent synthetic lethal vulnerability in various RAS mutant contexts, including RAS-driven leukemia/melanoma and facilitates cancer resistance to numerous RAS/MAPK inhibitors. SHOC2 is a scaffold that binds RAS and PP1C to form a ternary holophosphatase complex which dephosphorylates inhibitory ‘S259’ on RAF proteins and enables MAPK signaling. To actualize SHOC2 as a therapeutic target and inform future efforts to rationally design inhibitors against the complex, a deep understanding of SHOC2 structural features that govern complex assembly and function is needed. We have now resolved the SHOC2 complex structure and have profiled the functional consequence of nearly all possible amino acid substitutions at every position of SHOC2 through deep mutational scanning. These findings highlight novel structural features of SHOC2 that may be important to therapeutically target in RAS mutant cancers. The studies outlined in this proposal will build on this work and aim to (1) define and validate the structural features of SHOC2 holophosphatase complex specificity toward RAF substrate, and (2) identify novel post-translational modifications that regulate SHOC2 function. The training I receive in the K99 phase will provide me the necessary expertise in structural biology, proteomics, and ubiquitin biology as well as equip me with teaching/lab management experience so that I can effectively lead my own independent research program. The K99/R00 will be instrumental in helping me achieve my long-term goal, to establish my laboratory focused on studying novel RAS-associated vulnerabilities and drug resistance mechanisms via systematic approaches in cell signaling and protein structure-function.