[Function, molecular structure and gene expression regulation of hepatocyte growth factor and its receptor].

Hepatocyte growth factor (HGF), a potent mitogen of mature hepatocytes in primary culture, is composed of 69 kDa alpha-chain with four kringle domains and 34 kDa beta-chain. HGF is currently thought to be a pleiotropic factor, that stimulates the growth and motility of various epithelial cells, and that inhibits the growth of some carcinoma cells. These cells have a single class of high affinity receptor with a dissociation constant (Kd) of 20-30 pM. The maximum number of binding sites (Bmax) was determined to be 100-1500 sites/cell. After 70% partial hepatectomy and unilateral nephrectomy, HGF activity in serum and their tissues increased markedly and HGF receptors of the injured organ rapidly decreased, but not in other normal organs. These results suggest that HGF acts only in a regenerating organ after injury through the control mechanisms governing HGF receptor.