FUNCTION OF P130 CAS IN CELL SURVIVAL

提出的研究计划的目的是研究p130Cas在细胞生理学中未被探索的重要功能，即其在调节细胞死亡和存活中的作用。p130Cas最初被鉴定为v-Crk或v-Src转化细胞中的主要酪氨酸磷酸化蛋白，是一种多功能细胞信号组装蛋白。它包含多个结构基序，并与许多信号分子相互作用，如Crk， Src和FAK。与其结构特征一致，p130Cas被发现在功能上参与细胞转化、粘附、迁移和肌动蛋白组织。这是正常动物发育所必需的。缺乏p130Cas的突变小鼠在子宫内死亡，表现出明显的全身充血和生长迟缓。然而，p130Cas在细胞死亡/存活调控中的功能尚未被研究。在我们对蛋白酪氨酸磷酸化和细胞生长调控的研究过程中，我们发现p130Cas在酪氨酸磷酸酶lar诱导的细胞凋亡中起关键作用。LAR使p130Cas蛋白去磷酸化并使其不稳定。LAR下调p130Cas可激活caspase通路，诱导细胞凋亡。恢复p130Cas蛋白水平可减轻lar诱导的细胞凋亡。这些数据表明p130Cas在调节细胞死亡/存活中的新功能以及p130Cas蛋白被调节的新机制。本研究旨在探讨p130Cas在调节细胞死亡/存活中的功能和机制。我们将结合生物化学、分子和细胞生物学技术来鉴定特定的信号分子和信号转导途径，p130Cas通过这些信号分子转导细胞死亡/生存信号。我们将通过检测p130Cas在anoikis（一种由上皮细胞和内皮细胞脱离基质引起的细胞死亡形式）和生长因子剥夺诱导的细胞死亡中的调控和功能来研究p130Cas介导的细胞死亡的生理相关性，在这两种情况下，蛋白酪氨酸磷酸化/去磷酸化都起着关键作用。最后，我们还将探讨p130Cas蛋白水平调控的新机制。本研究将增加我们对p130Cas的功能和机制的认识，加深我们对信号转导、细胞死亡/存活调控和细胞生长的认识，并有助于设计治疗药物来诱导/防止细胞凋亡治疗人类疾病。

The goal of the proposed research plan is to investigate an unexplored and important function of p130Cas in cellular physiology, i.e., its role in regulating cell death and survival. p130Cas, originally identified as a major tyrosine-phosphorylated protein in v-Crk or v-Src transformed cells, is a multifunctional cell signal assembly protein. It contains multiple structure motifs and interact with a number of signaling molecules, such as Crk, Src, and FAK. Consistent with its structural characteristics, p130Cas has been found to be functionally involved in cell transformation, adhesion, migration and actin organization. It is essential for normal animal development. Mutant mice lacking p130Cas die in utero showing marked systemic congestion and growth retardation. Function of p130Cas in cell death/survival regulation, however, has not been studied. During the course of our study on regulation of protein tyrosine phosphorylation and cell growth, we found p130Cas to be a key player in tyrosine phosphatase LAR-induced apoptosis. LAR dephosphorylates and destabilizes the p130Cas protein. The down regulation of p130Cas by LAR leads to activation of a caspase pathway and induces apoptosis. Restoring p130Cas protein level alleviates the LAR-induced apoptosis. These data suggest a new function of p130Cas in regulating cell death/survival and a new mechanism by which the p130Cas protein is regulated. The present proposal is designed to investigate the function and mechanism of p130Cas in regulating cell death/survival. We will use a combination of biochemical, molecular, and cell biological techniques to identify specific signaling molecules and signal transduction pathways, through which p130Cas transduces cell death/survival signals. We will investigate the physiological relevance of p130Cas-mediated cell death by examining the regulation and function of p130Cas during anoikis, a form of cell death caused by detachment of epithelial and endothelial cells from their substratum, and in growth factor deprivation induced cell death, in both of which protein tyrosine phosphorylation/dephosphorylation play a critical role. Finally, the new mechanism regulating p130Cas protein level will also be investigated. The proposed study will increase our knowledge on function and mechanism of p130Cas, shed light on our general understanding of signal transduction, regulation of cell death/survival, and cell growth, and help designing therapeutic reagents to induce/prevent apoptosis in treating human diseases.