PILOT PROJECT 1 UBIQUITIN-MEDIATED REGULATION OF KINASE SUPPRESSOR OF RAS1

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 本研究的长期目标是通过泛素化调节肿瘤发生来确定和表征分子机制。 该提案的中心假设是特定的E3连接酶复合物介导Ras 1（KSR 1）分子支架激酶抑制剂的泛素化，以控制其半衰期和信号传导。 KSR1是Raf/MEK/ERK激酶级联的支架。 我们观察到KSR 1与泛素E3连接酶的组分包括CUL4，DDB1，VPRBP（DCAF1），EDD1和BRUCE（BIRC 6）相互作用。 CUL4A的过表达促进KSR1的泛素化。 与DDB1-VPRBP复合物相互作用的激酶DYRK2使katanin磷酸化，使其成为连接酶泛素化的底物。 值得注意的是，DYRK2的底物磷酸化的共有序列被发现围绕KSR 1中的Thr274和Ser392。 这些数据表明，KSR1影响Ras诱导的肿瘤发生的能力是由特定的E3连接酶的泛素化调节的。我们将通过表征KSR1与E3连接酶组分的相互作用并确定KSR1的泛素化是否影响致癌Ras的细胞转化和肿瘤发生来验证这一假设。这些研究应该揭示细胞增殖和转化控制的新机制。这些知识将为探索和理解影响人类癌症易感性的分子机制开辟新的途径。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The long-term goal of this research is to identify and characterize molecular mechanisms through ubiquitylation regulates tumorigenesis. The central hypothesis of the proposal is that specific E3 ligase complexes mediate the ubiquitylation of the molecular scaffold Kinase Suppressor of Ras 1 (KSR1) to control its half-life, and signaling. KSR1 is a scaffold for the Raf/MEK/ERK kinase cascade. We observed that KSR1 interacts with the components of ubiquitin E3 ligases including CUL4, DDB1, VPRBP (DCAF1), EDD1, and BRUCE (BIRC6). Overexpression of CUL4A promotes ubiquitylation of KSR1. The kinase DYRK2, which interacts with the DDB1-VPRBP complex, phosphorylates katanin making it a substrate for ubiquitylation by the ligase. Notably, the consensus sequence for substrate phosphorylation by DYRK2 is found surrounding Thr274 and Ser392 in KSR1. These data suggest that the ability of KSR1 to affect Ras-induced tumorigenesis is regulated by its ubiquitylation by specific E3 ligases. We will test this hypothesis by characterizing the interaction of KSR1 with E3 ligase components and determining whether the ubiquitylation of KSR1 affects cell transformation and tumorigenesis by oncogenic Ras. These studies should reveal novel mechanisms underlying cellular control of proliferation and transformation. Such knowledge should open new avenues for exploration and understanding of the molecular mechanisms affecting cancer susceptibility in humans.