Mizuno K, Takehara T, Nakamura T
Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan.
Biochem Biophys Res Commun. 1992 Dec 30;189(3):1631-8. doi: 10.1016/0006-291x(92)90264-l.
Hepatocyte growth factor (HGF) is biosynthesized as a single-chain precursor (pro-HGF) and is proteolytically processed to a two-chain mature form. When MRC-5 fibroblasts were pulse-radiolabeled under serum-free conditions, pro-HGF was the predominant molecular form of HGF in the culture medium. CHO cells transfected with an expression plasmid containing a full-size human HGF cDNA produced pro-HGF when these cells were cultured in serum-free medium. These findings suggest that HGF is secreted as a pro-form, which is then converted to a two-chain form by extracellular protease. Single-chain HGF exhibited mitogenic activity on cultured hepatocytes, with a potency similar to that of mature HGF, but this activity was remarkably inhibited by leupeptin. We postulate that inactive pro-HGF is converted to an active two-chain form by a leupeptin-sensitive serine-protease expressed by hepatocytes. Neither plasminogen activators nor plasmin showed any processing activity of pro-HGF in vitro.
