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）在胚胎发生的组织形成过程中以及组织损伤后的组织再生过程中充当生长因子。我们发现了一种 115kDa 的蛋白质，该蛋白质在 HGF 刺激的细胞中被酪氨酸磷酸化，并将其命名为 Hrs。其cDNA的核苷酸序列表明Hrs是一种具有锌指结构域的新型蛋白质。本研究对该蛋白的功能进行了分析，得到以下结果： 1．通过亚细胞分级分离和免疫荧光染色对 Hrs 的细胞内定位进行分析表明，Hrs 定位于早期内体。几种具有保守锌指结构域且定位于内体的蛋白质参与囊泡运输。因此，Hrs可能参与囊泡运输，如生长因子-受体复合物的内化。2． EGF或PDGF处理的细胞中，Hrs的酪氨酸磷酸化被诱导。这些结果表明，Hrs在生长因子信号通路中发挥着独特而重要的作用。 3．通过使用酵母双杂交系统筛选小鼠肝脏 cDNA 文库，我们分离出了 Hrs 结合蛋白的 cDNA。 cDNA的核苷酸序列表明该结合蛋白是一种具有SH3结构域的新型蛋白。使用针对 Hrs 的抗体和结合蛋白，我们发现这两种蛋白在各种细胞中密切相关。这些结果表明 Hrs 通过与结合蛋白相互作用在 HGF 信号转导中发挥重要作用。