The Role of a New Hepatocyte Growth Factor in Liver Regeneration

小鼠血清肝细胞生长刺激活性在四氯化碳染毒后24小时显著升高，然后下降。这一活性的时间进程与血清丙氨酸和天冬氨酸转氨酶活性的时间进程是平行的。未经处理的小鼠肝脏提取物中的肝细胞生长刺激活性很低，但经四氯化碳处理后，肝细胞生长刺激活性增加。肝毒素注射后12小时可检测到升高，并在24小时后显著升高。给药后48h达最大值，然后逐渐下降。肝细胞DNA合成在肝毒素作用后36h和48h开始升高，48h达高峰。因此，在四氯化碳处理的小鼠肝再生之前，血清和肝脏中的肝细胞生长刺激活性增加。血清和肝脏活性的升高可能在肝损伤后促进体内肝细胞的增殖中起重要作用。小鼠肝细胞生长因子经硫酸铵分级沉淀、亲和凝胶蓝层析、肝素琼脂糖层析、S琼脂糖层析后，可从小鼠肝细胞生长因子中纯化约28万倍，产率为21%。纯化的mHGF在非还原条件下的SDS-PAGE显示一条相对分子质量为76K的单一条带，而还原的mHGF经SDS-PAGE后出现两条相对分子质量分别为62K和31K的条带，表明mHGF为杂二聚体。人肝细胞生长因子与人肝细胞生长因子一样有效地促进肝细胞DNA合成。MHGF的作用与EGF和酸性成纤维细胞生长因子的作用相加，与胰岛素的作用有协同作用，但与hHGF的作用不是最大。因此，mHGF的性质与hHGF相似。MHGF可能是一种与hHGF结构不同的hHGF样因子，因为mHGF的活性不受兔抗hHGF抗血清的抑制，从而中和了hHGF的活性。

A mouse serum hepatocyte growth-stimulating activity markedly increased 24 h after carbon tetrachloride administration and then decreased. This time course of the activity was paralled with those of serum alanine and aspartate aminotransferses activities. hepatocyte growth-stimulating activity in liver extracts was low in untreated mice, but increased after carbon tetrachloride. The increase was detectable 12 h and marked 24 h after the hepatotoxin. It was maximal 48 h after the administration and then dropped gradually. Liver DNA synthesis began to rise and was highest 36 h and 48 h, respectively, after the hepatotoxin. Thus, the hepatocyte growth-stimulating activity in serum and liver increased prior to liver regeneration in carbon tetrachloride-treated mice. The elevated serum and liver activities may play an important role in promoting proliferation of liver cells in vivo subsequent to hepatic injury. Mouse hepatocyte growth factor (mHGF) was purified about 280,000-fold with 21% yield form the liver supernatant of mice treated with the hepatotoxin by ammonium sulfate fractionation followed by chromatography on Affi-Gel Blue, heparin-Sepharose and S-Sepharose. SDS-PolyacrylAmide Gel Electrophoresis (PAGE) of purified mHGF under nonreducing conditions showed a single band with a Molecular Weight (MW) of 76K, while two bands with MWs of 62K and 31K were detected after SDS-PAGE of reduced mHGF, showing that mHGF is a heterodimer. mHGF stimulated DNA synthesis of cultured hepatocytes as effectively as hHGF. The effect of mHGF was additive with the maximal effects of EGF and acidic FGF and synergistic with that of insulin, but not with the maximal effect of hHGF. Thus, the properties of mHGF are similar to those of hHGF. mHGF may be a hHGF-like factor with some structural differences from hHGF, because the activity of mHGF was not inhibited by rabbit anti-hHGF antiserum which neutralizes the hHGF activity.