Cbl Proteins as Regulators of Tyrosine Kinase Signaling

我们正在研究Cbl蛋白的功能，这是一种调节酪氨酸激酶活性的蛋白质家族。CBL蛋白属于泛素蛋白连接酶(E3s)的无名指类，其功能是激活酪氨酸激酶的E3s。我的团队克隆了三个哺乳动物Cbl基因中的两个(Cblb和CBLC)，并证明了所有哺乳动物Cbl蛋白都介导了激活的表皮生长因子受体(EGFR)以及信号复合体的其他成分的泛素化和降解。正在进行的工作集中在了解三种哺乳动物Cbl蛋白在上皮细胞中的生化和生理功能，并阐明它们在特异性和/或功能上的差异。我们一直关注CBLC的功能，CBLC是最近发现的、知之甚少的家庭成员。这种蛋白只在上皮细胞中表达，我的团队对乳腺癌等上皮性恶性肿瘤特别感兴趣。此前，为了了解CBLC蛋白的功能，我们与奥地利维也纳IMBA的Josef Penninger合作敲除了CBLC。不幸的是，CBLC基因缺失的小鼠没有检测到异常。为了深入了解CBLC的功能，我们使用酵母双杂交筛选来检测与CBLC相互作用的新蛋白。目前，我们正在研究这些蛋白质的功能以及它们与CBLC相互作用的后果。此外，我们已经确定了CBLC中的突变，预计这种突变将从小鼠乳腺癌中产生CBLC的转化版本。我们正在更详细地研究这个突变，看看它是否正在转化，并在鼠和人类肿瘤中寻找其他突变的证据。更广泛地说，正在进行的工作是表征Cbl蛋白介导泛素化的分子机制。这包括研究Cb1蛋白的结构-功能关系，以及它们与泛素结合蛋白(E2)的相互作用。我们已经与Randazzo小组(CCR)合作，调查ARAP1、Cb1蛋白和EGFR贩运之间的相互作用。此外，我们正在与芝加哥大学的马库斯·克拉克合作研究Cbl-b在B细胞抗原受体转运中的作用，并与张健合作了解Cbl-b在T细胞受体信号转导中的作用。最后，我们与Allan Weissman(CCR)就Cb1蛋白作为E3发挥作用的机制进行了持续的合作。总体而言，这些研究应该能深入了解Cbl蛋白的生化、生物学和病理生理功能。

We are investigating the function of Cbl proteins, a family of proteins that regulate tyrosine kinase activity. Cbl proteins belong to the RING finger class of ubiquitin protein ligases (E3s) and function as E3s for activated tyrosine kinases. My group cloned two of the three mammalian Cbl genes (Cblb and Cblc) and demonstrated that all mammalian Cbl proteins mediate ubiquitination and degradation of the activated epidermal growth factor receptor (EGFR) as well as other components of the signaling complex. Ongoing work is focused on understanding the biochemical and physiologic functions of the three mammalian Cbl proteins in epithelial cells and elucidating the differences in their specificity and/or function. We have been focused on the function of Cblc, the most recently identified family member about which the least is known. This protein is expressed only in epithelial cells and my group is particularly interested in epithelial malignancies such as breast cancer. Previously, to understand the function of the Cblc protein, we collaborated with Josef Penninger (IMBA, Vienna, Austria) to knock out Cblc. Unfortunately, the Cblc null mice have no detectable abnormalities. To gain insight into the function of Cblc, we have used yeast two-hybrid screens to detect novel proteins that interact with Cblc. Currently, we are characterizing the function of these proteins and the consequences of their interactions with Cblc. In addition, we have identified mutations in Cblc that is predicted to create a transforming version of Cblc from a murine breast cancer. We are investigating this mutant in more detail to see if it is transforming and searching for evidence of other mutants in murine and human tumors. More generally, ongoing work is characterizing the molecular mechanism by which the Cbl proteins mediate ubiquitination. This includes investigating the structure-function relationship of the Cbl proteins, and their interactions with the ubiquitin conjugating (E2) proteins. We have collaborated with the Randazzo group (CCR)to investigate the interaction between ARAP1, Cbl protiens, and EGFR trafficking. In addition we are collaborating with Marcus Clark (University of Chicago) to study the role of Cbl-b on B-Cell antigen receptor trafficking and with Jian Zhang to understand the function of Cbl-b in T-cell receptor signaling. Finally, we have an ongoing collaboration with Allan Weissman (CCR) on the general investigation of mechanisms by which the Cbl proteins function as E3s. Overall, these studies should provide insight into the biochemical, biological, and pathophysiological functions of the Cbl proteins.