SRC FAMILY PROTEIN TYROSINE KINASE P62YES AND EPIDERMAL GROWTH FACTOR RECEPTOR

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。聚合免疫球蛋白受体（pIgR）介导的聚合IgA （pIgA）胞吞作用在粘膜对病原体和过敏原的免疫防御中起关键作用。所有粘膜上皮和肝细胞都有IgA淋巴细胞感染。pIgA与pIgR的结合刺激pIgR-pIgA复合物的转胞作用，并激活几种信号分子，包括src家族非受体酪氨酸激酶p62yes。最近发现p62yes在小鼠肝脏中控制pIgA胞吞。目前尚不清楚p62yes如何调节pIgA胞吞作用。先前的数据显示p62yes与pIgR之间没有直接的相互作用。pIgR不是p62yes的底物，因为p62yes不能磷酸化pIgR，而pIgR也不能在酪氨酸上磷酸化。最有可能的是，p62yes通过其底物调控pIgR-pIgA的胞吞作用。鉴定p62yes底物是理解pIgA胞吞机制的关键一步。通过使用Shokat博士开发的新技术，我们的初步数据表明表皮生长因子受体（EGFR）可能是p62yes底物之一。当pIgA与pIgR结合时，EGFR可能被p62yes激活。反过来，它直接激活PLC-gamma1，从而导致整个信号通路的激活。在拟进行的实验中，将验证以下具体假设：1)EGFR可能是p62yes的底物，并可能在上皮细胞和肝细胞中调控pIgA的胞吞作用。2) pIgR-pIgA、p62yes和p62yes的底物在大鼠肝细胞内体腔室中形成一种蛋白质复合物。3) EGFR的激活增加了pIgA的胞吞作用。本研究有助于我们了解极化上皮细胞和肝细胞的粘膜免疫和蛋白质转运的基本机制。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Polymeric IgA (pIgA) transcytosis mediated by the polymeric immunoglobulin receptor (pIgR) plays a key role in the mucosal immune defense against pathogens and allergens. IgA trancytosis occurs in all mucosal epithelium and in hepatocytes. The binding of pIgA to pIgR stimulates transcytosis of the pIgR-pIgA complex and activates several signaling molecules that include the Src-family non-receptor tyrosine kinase, p62yes. Recently p62yes has been found to control pIgA transcytosis in mouse liver. It is not clear how p62yes regulates pIgA transcytosis. Previous data showed that there is no direct interaction between p62yes and pIgR. pIgR is not the substrate of p62yes since p62yes is unable to phosphorylate pIgR and pIgR is not phosphorylated on tyrosine. Most likely, p62yes regulates the pIgR-pIgA transcytosis via its substrates. Identification of the substrates of p62yes is a key step leading to understanding the mechanisms of pIgA transcytosis. By using a novel technique developed by Dr. Shokat, our preliminary data suggest that Epidermal Growth Factor Receptor (EGFR) may be one of the p62yes substrates. EGFR may be activated by p62yes upon pIgA binding to pIgR. In turn it directly activates PLC-gamma1, thereby leading to activation of the entire signaling pathway. In the proposed experiments, the following specific hypotheses will be tested: 1) EGFR is a possible substrate of p62yes and may play a role in the regulation of pIgA transcytosis in epithelial cells and hepatocytes. 2) pIgR-pIgA, p62yes and a substrate of p62yes form a protein complex in an endosomal compartment in rat hepatocytes. 3) Activation of EGFR increases pIgA transcytosis. This proposed research could help us to understand mucosal immunity and the basic mechanisms of protein transport in polarized epithelial cells and hepatocytes.