Regulation of cell migration and signaling by phosphotyrosine and ubiquitin

描述（由申请人提供）：细胞迁移受细胞-细胞相互作用、细胞-基质相互作用和化学引诱剂和驱避剂的信号调节。这些信号通过翻译后修饰和蛋白-蛋白相互作用的级联传导和协调。具体来说，Src家族酪氨酸激酶被丝裂原和粘附受体激活，并磷酸化在迁移细胞中组织前沿和局灶粘附的蛋白。Cullin 5 RING (CRL5) E3泛素连接酶和SOCS蛋白（CRL5的磷酸酪氨酸依赖底物接头）被认为是潜在的肿瘤抑制因子。我们发现SOCS-CRL5复合物在多种细胞类型中调节Src活性、细胞迁移、增殖和/或转化。抑制上皮细胞中SOCS蛋白或Cul5的表达可刺激迁移、增殖和Src激酶活性。Src的增加对于crl5缺陷细胞的迁移和增殖增加是必要的，但不是充分的，这表明soc - crl5复合物有其他底物。我们提出了三个广泛的目标来深入了解CRL5如何调节Src和细胞迁移。首先，我们将确定CRL5如何调节Src活性。其次，我们将鉴定CRL5底物，重点是那些含有磷酸酪氨酸的底物，并测试哪些底物调节细胞迁移和增殖。第三，我们将剖析SOCS蛋白和底物在细胞迁移过程中协调焦点粘附和前沿动态的机制。总的来说，我们的研究将显示蛋白质酪氨酸磷酸化和泛素化如何协同调节细胞生物学。

DESCRIPTION (provided by applicant): Cell migration is regulated by signals from cell-cell interactions, cell-matrix interactions and chemo-attractants and -repellants. Such signals are transduced and coordinated by cascades of post-translational modifications and protein-protein interactions. Specifically, Src family tyrosine kinases are activated by mitogens and adhesion receptors and phosphorylate proteins that organize the leading edge and focal adhesions in migrating cells. The Cullin 5 RING (CRL5) E3 ubiquitin ligase and SOCS proteins (phosphotyrosine-dependent substrate adaptors for CRL5) have been implicated as potential tumor suppressors. We have found that SOCS-CRL5 complexes regulate Src activity, cell migration, proliferation and/or transformation in several cell types. Inhibiting the expression of SOCS proteins or Cul5 in epithelial cells stimulates migration, proliferation, and Src kinase activity. Increased Src is necessary but not sufficient for the increased migration and proliferation of CRL5-deficient cells, suggesting that SOCS-CRL5 complexes have additional substrates. We propose three broad aims to understand in depth how CRL5 regulates Src and cell migration. First, we will determine how CRL5 regulates Src activity. Second, we will identify CRL5 substrates, focusing on those that contain phosphotyrosine, and test which substrates regulate cell migration and proliferation. Third, we will dissect the mechanisms by which SOCS proteins and substrates coordinate focal adhesion and leading edge dynamics during cell migration. Collectively, our research will show how protein-tyrosine phosphorylation and ubiquitylation cooperate to regulate cell biology.