C-CBL IN MODULATION OF CELL ADHESION AND MORPHOLOGY

描述：（改编自研究者摘要） 大量证据表明原癌蛋白c-Cbl参与了 正常和转化细胞中的信号转导。 c-Cbl变成酪氨酸 磷酸化的反应刺激通过各种受体，如 以及在由蛋白质酪氨酸的致癌形式转化的细胞中 酪氨酸磷酸化的c-Cbl显着上调其 与各种重要的信号分子结合 然而，生物 c-Cbl介导的信号转导的结果知之甚少。 最近，我们已经成功地绘制了 c-Cbl。 为了分析c-Cbl的生物学功能，我们 过表达的野生型c-Cbl或其缺乏酪氨酸的突变形式 磷酸化位点，并证明， 野生型c-Cbl抑制致癌Abl的转化，而 磷酸化缺陷的c-Cbl增强了这种转化。 的影响 野生型c-Gbl与细胞粘附和铺展的诱导有关 对细胞外基质的影响 这些意见，连同 以前的发现，使我们的假设，c-Cbl招募，在一个 酪氨酸磷酸化依赖方式，PI-3激酶和Crk家族 蛋白质粘附于膜和/或粘着斑复合物。 这反过来又 触发信号转导途径，促进聚集的焦点 粘附复合物和肌动蛋白应力纤维。 酪氨酸 细胞形态和粘附的磷酸化依赖性调节可 构成c-Cbl的主要生物学功能。 本提案的总体目标是检验这一假设。 因此，我们的项目的具体目标是：1）确定 c-Cbl的酪氨酸磷酸化位点是其 转换抑制功能; 2）确定关系 c-Cbl酪氨酸磷酸化的生物学效应与 c-Cbl与膜的相互作用，粘着斑复合物， 细胞骨架在转化成纤维细胞; 3），以确定 PI-3激酶与Crk依赖性信号转导的关系 c-Cbl在转化成纤维细胞中的途径和生物学效应; 和4）评估c-Cbl参与对各种肿瘤的生物学反应， 蛋白酪氨酸激酶介导的细胞外刺激类型 未转化的成纤维细胞。 研究人员相信，这项工作将定义生物学 c-Cbl的功能，并确定其分子基础。 这应该 实质上推进了我们对正常细胞激活理解， 肿瘤转化，并可能提出新的治疗方法， 靶向信号转导机制。

DESCRIPTION: (adapted from the investigator's abstract) There is substantial evidence that the protooncogenic protein c-Cbl is involved in signal transduction in normal and transformed cells. c-Cbl becomes tyrosine phosphorylated in response to stimulation through a variety of receptors, as well as in the cells transformed by oncogenic forms of the protein tyrosine kinase Abl. Tyrosine phosphorylation of c-Cbl dramatically upregulates its binding to various crucial signaling molecules. However, the biological consequences of c-Cbl-mediated signal transduction are poorly understood. Recently, we have succeeded in mapping the tyrosine phosphorylation sites of c-Cbl. In order to analyze the biological functions of c-Cbl, we overexpressed wild-type c-Cbl or its mutant form lacking tyrosine phosphorylation sites in Abl-transformed fibroblasts and demonstrated that the wild-type c-Cbl suppresses transformation by oncogenic Abl, whereas the phosphorylation-defective c-Cbl enhances this transformation. The effect of wild-type c-Cbl is connected to the induction of cell adhesion and spreading on the extracellular matrix. These observations, taken together with the previous findings, led us to the hypothesis that c-Cbl recruits, in a tyrosine-phosphorylation dependent manner, PI-3 kinase and Crk-family proteins to the membrane and/or focal adhesion complexes. This, in turn, triggers signal transduction pathways facilitating the assembly of focal adhesion complexes and actin stress fibers. The tyrosine phosphorylation-dependent regulation of cell morphology and adhesion may constitute the major biological functions of c-Cbl. The overall objective of the current proposal is to test this hypothesis. Accordingly, the specific aims of our project are: 1) to determine the tyrosine phosphorylation sites of c-Cbl essential for its transformation-suppressing function; 2) to determine the relationship between the biological effects of c-Cbl tyrosine phosphorylation and the interactions of c-Cbl with the membrane, focal adhesion complexes and cytoskeleton in Abl-transformed fibroblasts; 3) to determine the relationship between PI-3 kinase- and Crk-dependent signal transduction pathways and the biological effects of c-Cbl in Abl-transformed fibroblasts; and 4) to assess the involvement of c-Cbl in biological responses to various types of extracellular stimulation mediated by protein tyrosine kinases in untransformed fibroblasts. The investigators are confident that this work will define the biological functions of c-Cbl and determine their molecular basis. This should substantially advance our understanding of normal cell activation and neoplastic transformation and may suggest novel therapeutic approaches that target signal transduction mechanisms.