Regulation of HAM function by proteolytic processing

通过蛋白水解过程调节 HAM 功能

基本信息

批准号：
13680709
负责人：
MIYAZAWA Keiji
金额：
$ 2.3万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13680709/
关键词：
growth factors protease inhibitor processing インイビター

项目摘要

HGF activator inhibitor (HAI-1) is a proteinaceous inhibitor of HGF activator (HGFA), which proteolytically activates hepatocyte growth factor (HGF). HGF is a multifunctional cytokine that is involved in regeneration and tissue repair after injury. HAI-1 is synthesized as a type I membrane protein, and secreted as a 40 kD HAI-1 or 58 kD HAI-1 by proteolytic processing. 40kD HAI-1 contains one Kunitz domain (Kunitz 1), whereas 58 kD HAI-1 contains two Kunitz domains (Kunitz 1 and 2). We generated deletion mutants of each Kunitz domains, and found that Kunitz 1is mainly involved in inhibition of HGFA. Although 58 kD HAI-1contains two Kunitz domains, its inhibitory activity for HGFA is very weak. We found that two Kunitz domains masked each other, thus lowering the inhibitory activity of the whole protein.When two-thirds of rat liver is resected, pro-HGF in the residual liver increases dramatically, but the active HGF is present in only a small amount. We then administered active HGFA via portal vein 24 h after partial hepatectomy, and examined the effect on liver regeneration. Administration of HGFA caused activation of pro-HGF in the residual liver and induced tyrosine phosphorylation of c-Met (HGF receptor). In addition, labeling index of hepatocytes was increased, and recovery of liver mass was promoted. We needed, however, a large amount of HGFA to obtain significant enhancement of liver regeneration, indicating that tissue-derived inhibitors such as HAI-1 play important roles in regulating activity of HGFA in vivo.

HGF激活剂抑制剂（HAI-1）是HGF激活剂（HGFA）的蛋白质抑制剂，蛋白水解激活肝细胞生长因子（HGF）。 HGF是一种多功能细胞因子，损伤后涉及再生和组织修复。 HAI-1被合成为I型膜蛋白，并通过蛋白水解处理被分泌为40 kD HAI-HAI-1或58 kD HAI-1。 40KD HAI-1包含一个Kunitz域（Kunitz 1），而58 kD Hai-1包含两个Kunitz域（Kunitz 1和2）。我们产生了每个kunitz结构域的缺失突变体，发现库尼兹1主要参与抑制HGFA。尽管58 kd hai-1 contains两个kunitz域，但其对HGFA的抑制活性非常弱。我们发现，两个kunitz结构域互相掩盖，从而降低了整个蛋白质的抑制活性。切除大鼠肝脏的三分之二时，残留肝脏中的pro-HGF显着增加，但活性HGF仅以少量数量存在。然后，我们在部分肝切除术后24小时通过门静脉施用活性HGFA，并检查对肝脏再生的影响。 HGFA的给药导致在残留肝脏中激活Pro-HGF并诱导C-MET的酪氨酸磷酸化（HGF受体）。此外，增加了肝细胞的标记指数，并促进了肝脏质量的恢复。但是，我们需要大量的HGFA才能获得肝脏再生的显着增强，这表明组织来源的抑制剂（例如HAI-1）在调节体内HGFA活性中起着重要作用。