Characterization of factors regulating the activity of hepatocyte growth factor which is being developed for a medicine

Hepatocyte growth factor （HGF）是Hepatocyte的潜在mitogen，并已被开发成一种liver disease的医学。HGF在血清蛋白酶、HGF激活剂（HGFA）、跟随肝脏损伤以及随后作为肝脏再生因子的功能中激活。在本研究中，我们审查了HGFA激活和不激活的机制，并获得了以下结果。对HGFA及其mRNA的分析，在活体诱导的CCly-D24 Y-D2对大鼠的治疗中发现的HGFA mRNA增加的数量，HGFA，血液在正常状态下循环，作为一个非活性前束器在活体损伤下激活。这些结果表明，HGFA在调节HGF的活动中发挥了一个关键作用，增加了其数量和蛋白质激活链接到血液结合系统跟随的肝脏损伤。HGFA抑制剂的两种类型，HAI-1和HAI-2，已被确认为HGFA潜在抑制剂。如果使用单克隆抗体来对抗HAI-1，我们已确定了一个将HA 1 -1集成在文化细胞等离子体膜中的跨膜形式。我们还在细胞的条件介质中识别了HAI-1的多种溶解度形式，并表明HAI-1跨膜形式的多个站点存在于其中的蛋白质清除释放的外链域中。至少有两种蛋白质，其中一种是金属蛋白质，似乎对释放有责任。此外，HAI-1的不稳定形式有不同的抑制剂活动，反对HGFA。这些发现建议，蛋白质加工在抑制剂活动中的重要作用在调节H1 - 1中。

Hepatocyte growth factor (HGF) is a potent mitogen for hepatocytes, and is being developed for a medicine of liver disease. HGF is activated in the liver by a serine protease, HGF activator (HGFA), following liver injury, and then functions as a liver regeneration factor. In this study, we examined mechanisms for activation and inactivation of HGFA and obtained the following results.1. Analysis of HGFA and its mRNA after liver injury induced by CClィイD24ィエD2 treatment of rat revealed that amount of HGFA mRNA increased, and HGFA, that circulates in the blood as an inactive precursor at normal state, was activated by thrombin following liver injury. These results indicate that HGFA plays an crucial role in regulating the activity of HGF by increase of its amount and proteolytic activation linked to blood coagulation system following liver injury.2. Two types of HGFA inhibitor, HAI-1 and HAI-2, were identified as potent inhibitors of HGFA. Using a monoclonal antibody against HAI-1, we identified a transmembrane form of HA1-1 integrated in the plasma membrane of cultured cells. We also identified several soluble forms of HAI-1 in the conditioned medium of the cells, indicating that multiple sites are present in the transmembrane form of HAI-1 at which proteolytic cleavage releases the extracellular domain. At least two proteases, one of which is a metalloprotease, appear to be responsible for the release. Further, the soluble forms of HAI-1 have different inhibitory activity against HGFA. These findings suggest that proteolytic processing plays important roles in regulation of the inhibitory activity of Hal-1.