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Functional characterization of a novel tyrosine phosphorylated protein in signal transduction of hepatocyte growth factor

新型酪氨酸磷酸化蛋白在肝细胞生长因子信号转导中的功能表征

基本信息

批准号：
07458164
负责人：
KITAMURA Naomi
金额：
$ 4.61万
依托单位：
TOKYO INSTITUTE OF TECHNOLOGY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

Hepatocyte growth factor (HGF) functions as a growth factor during tissue formation in embryogenesis and during tissue regeneration after tissue injury. We found a 115kDa protein which is tyrosine-phoshorylated in cells stimulated by HGF and designated it Hrs. The nucleotide sequence of its cDNA revealed that Hrs is a novel protein with a zinc-finger domain. In this study, we analyzed the function of the protein and obtained the following results.1. Analysis of intracellular localization of Hrs by subcellular fractionation and immunofluorescence staining revealed that Hrs is localized to early endosomes. Several proteins with the conserved zinc-finger domain that are localized to endosomes are involved in vesicular transport. Thus, Hrs may be involved in vesicular transport such as internalization of growth factor-receptor complexes.2. Tyrosine phosphorylation of Hrs was induced in cells treated by EGF or PDGF.These results suggest that Hrs plays a unique and important role in ths signaling pathway of growth factors.3. By screening a mouse liver cDNA library using yeast two-hybrid system, we isolated a cDNA of a Hrs binding protein. The nucleotide sequence of the cDNA revealed that the binding protein is a novel protein with a SH3 domain. Using the antibodies against Hrs and the binding protein, we showed that both proteins are strongly associated in various cells. These results suggest that Hrs plays an important role in HGF signaling by interaction with the binding protein.

肝细胞生长因子（HGF）在胚胎形成和组织损伤后的组织再生过程中发挥生长因子的作用。在HGF刺激的细胞中发现了一个115kDa的酪氨酸磷酸化蛋白，命名为Hrs。其cDNA的核苷酸序列表明，Hrs是一种具有锌指结构域的新蛋白。在本研究中，我们分析了该蛋白的功能，得到了以下结果：1。通过亚细胞分离和免疫荧光染色分析Hrs的细胞内定位，发现Hrs定位于早期核内体。一些具有保守锌指结构域的蛋白定位于核内体，参与囊泡运输。因此，Hrs可能参与囊泡运输，如生长因子受体复合物的内化。EGF或PDGF均可诱导Hrs的酪氨酸磷酸化。这些结果表明，Hrs在这条生长因子信号通路中起着独特而重要的作用。利用酵母双杂交系统筛选小鼠肝脏cDNA文库，分离出Hrs结合蛋白的cDNA。cDNA的核苷酸序列表明，该结合蛋白是一个具有SH3结构域的新蛋白。利用Hrs抗体和结合蛋白，我们发现这两种蛋白在各种细胞中都有很强的相关性。这些结果表明Hrs通过与HGF结合蛋白的相互作用在HGF信号传导中起重要作用。