Regulation of EGF Receptors by G protein receptor

描述（由申请人提供）：本申请的目的是 探索G蛋白偶联受体（GPCR）之间发生的串扰 和受体酪氨酸激酶（RTK），特别是表皮生长因子 受体（EGFR）。我们，像其他人一样，已经观察到， GPCR导致EGFR的转磷酸化和活化。我们还 提出了一个新的发现，即GPCR的预先激活导致了一个深刻的 EGFR的脱敏。此应用程序的目的是获得 对脱敏过程的机械见解。 在具体目标1中，我们将确定需要哪种信号通路 用于通过GPCR的EGF受体的脱敏和转磷酸化。我们 将主要使用具有内源性GPCR的细胞类型的原代培养物， 表皮生长因子受体。这些研究将通过明智地使用转染细胞来加强。 在这个目标中需要回答的主要问题是： GPCR激活EGFR磷酸化和反式激活？它们是一样的吗 与诱导EGFR脱敏的药物一样吗我们将主要关注 蛋白激酶C、非受体酪氨酸激酶Src和钠质子 交换器类型I（NHE-I）。EGFR的内吞作用是否是GPCR介导的 EGFR脱敏？肝素结合EGF（HB-EGF）是否需要 EGFR的脱敏或反式激活？为了回答这个 问题，我们将使用一些互补的方法来中和 在培养的原代细胞中的天然HB-EGF。 在具体目标2中，我们将确定EGFR的细胞内命运后， 刺激GPCR。EGFR靶向于哪些隔室， 通过GPCR的反式激活？还有哪些信号成分被内化 EGFR（GPCR，NRTK，NHE-1，HB-EGF），以及它们是否通过 相同的路径？什么样的酶途径是下调 EGFR？我们将研究溶酶体，蛋白酶体和锌调节的作用。 金属蛋白酶在这个过程中这些研究解决了我们的重要差距， 了解调控RTK功能的GPCR信号。

DESCRIPTION (provided by applicant): The purpose of this application is to explore the cross talk that occurs between G protein-coupled receptors (GPCR's) and receptor tyrosine kinases (RTK's), especially the epidermal growth factor receptor (EGFR). We, like others, have made the observation that activation of GPCR's leads to transphosphorylation and activation of EGFR's. We have also made the novel finding that prior activation of GPCR's leads to a profound desensitization of the EGFR's. The purpose of this application is to gain mechanistic insights into the desensitization process. In Specific Aim 1, we will determine which signaling pathway(s) is/are required for desensitization and transphosphorylation of the EGF receptor by GPCR's. We will mainly use primary cultures of cell types that have endogenous GPCR's and EGFR's. Those studies will be augmented by judicious use of transfected cells. Major questions to be answered in this aim are: What signaling molecules link GPCR activation to EGFR phosphorylation and transactivation? Are they the same as those that induce EGFR desensitization? We will focus primarily on the roles of protein kinase C, the non-receptor tyrosine kinase Src, and sodium proton exchanger type I (NHE-I). Is endocytosis of EGFR required for GPCR-mediated desensitization of EGFR? Is heparin-bound EGF (HB-EGF) required for either desensitization or transactivation of the EGFR? In order to answer this question, we will use a number of complementary methods to neutralize the native HB-EGF in primary cells in culture. In Specific Aim 2, we will determine the intracellular fate of the EGFR's after stimulation of GPCR's. To what compartments are the EGFR targeted after transactivation by GPCR' s? What other signaling components are internalized with the EGFR (GPCR, NRTK, NHE-1, HB-EGF), and are they processed through the same pathways? What enzymatic pathways are required for down-regulation of the EGFR? We will study the roles of lysosomes, proteasome, and zinc-regulated metalloproteinases in this process. These studies address important gaps in our knowledge of GPCR signals that regulate the functions of RTK's.