Shcc Function In Growth, Development And Cancer

工作总结：我们小组感兴趣的是了解ShcC接头蛋白在受体酪氨酸激酶(RTK)功能中的作用，特别是神经发育。ShcC是接头蛋白Shc家族的一员。该家族由三个成员(SHCA、ShcB和ShcC)组成，每个成员的特征是存在一个氨基末端的磷酸酪氨酸结合结构域(PTB)、一个中心的富含甘氨酸和Pro的效应区(CH1)和一个羧基末端的Src同源2(SH2)结构域。尽管这个蛋白质家族缺乏任何内在的酶活性，但Shc蛋白作为支架，组装调节RTK功能的信号复合体，以及包括整合素、G蛋白偶联受体(GPCRs)和造血细胞受体在内的多种受体蛋白。此外，最近来自其他实验室的工作表明，SHCA的某些亚型可能在细胞对氧化应激的反应和生物体的生命周期中发挥重要作用。在与Tony Pawson博士的合作中，我们已经证明了ShcC的消除不会影响神经系统的发育，这表明ShcC对功能可能比对发育更重要。结合多种技术，我们已经证明ShcC的表达仅限于神经系统，尤其是神经元。为了解决ShcC在神经系统中的重要性，我们已经开始更精确地定义ShcC在发育过程中的时间和空间表达模式。除了确定ShcC的表达模式外，我们还开始了实验来确定ShcC在整个动物中的磷酸化状态。我们已经开发出针对ShcC激活形式的磷酸特异性抗体。利用这些抗体，我们希望不仅能确定ShcC在何时何地表达，而且还能确定它在何时何地被激活。此外，我们正在利用质谱学来确定体内磷酸化的具体位置。这些方法也将被证明对确定环境侮辱是否影响ShcC功能是有用的。例如，神经毒物是否影响ShcC的表达或酪氨酸的磷酸化？为了进一步探索ShcC的重要性，我们正在使用该蛋白的突变版本来干扰RTK信号。虽然ShcC有两个结构域与激活的RTK相互作用，但我们已经证明PTB结构域是ShcC与激活的EGFR结合的主要方式。此外，我们的结果表明，SH2结构域可能在与EGFR功能所必需的额外细胞成分(S)的结合中起重要作用。我们目前正试图分离SH2相互作用的蛋白，希望能确定ShcC和EGFR的重要下游靶点。

SUMMARY OF WORK: Our group is interested in understanding the role of the ShcC adaptor protein in receptor tyrosine kinase (RTK) function in general and neural development in particular. ShcC is a member of the Shc family of adaptor proteins. This family consists of three members (ShcA, ShcB and ShcC), each of which is characterized by the presence of an amino-terminal phosphotyrosine binding domain (PTB), a central Gly- and Pro-rich effector region (CH1), and a carboxy-terminal Src homology 2 (SH2) domain. Although this family of proteins lacks any intrinsic enzymatic activity, Shc proteins act as scaffolds to assemble signaling complexes that regulate the function of RTKs as well as a wide variety of receptor proteins including integrins, G-protein coupled receptors (GPCRs) and hematopoietic receptors. In addition, recent work from other laboratories suggests that certain isoforms of ShcA may play an important role in the response of cells to oxidative stress and in the life span of an organism. In collaboration with Dr. Tony Pawson, we have shown that elimination of ShcC does not affect development of the nervous system suggesting that ShcC may be more important for function rather than development. Using a combination of techniques, we have shown that ShcC expression is restricted to the nervous system and to neurons in particular. To address the importance of ShcC in the nervous system, we have begun to more precisely define both the temporal and spatial expression pattern of ShcC during development. In addition to determining the expression pattern of ShcC, we have begun experiments to determine the phosphorylation status of ShcC in the whole animal. We have developed phosphospecific antibodies directed against the activated forms of ShcC. Using these antibodies we hope to determine not only where and when ShcC is expressed but also where and when it is activated. In addition, we are utilizing mass spectrometry in order to determine the specific sites of phosphorylation in vivo. These approaches will also prove useful for determining whether environmental insult affects ShcC function. For example, do neurotoxicants affect ShcC expression or tyrosine phosphorylation? To further explore the importance of ShcC, we are using mutant versions of the protein to interfere with RTK signaling. Although ShcC possesses two domains with the potential of interacting with activated RTKs, we have demonstrated that the PTB domain is the predominant means by which ShcC binds to the activated EGFR. Furthermore, our results suggested that the SH2 domain might be important for binding to an additional cellular component(s) necessary for EGFR function. We are currently attempting to isolate SH2 interacting proteins with the hope of identifying important downstream targets of both ShcC and the EGFR.