Co-expression of the proprotein-processing endoprotease furin and its substrate transforming growth factor beta1 and the differentiation of rat hepatocytes.

Furin, a member of the yeast Kex2 endoprotease family, converts a number of proproteins to their active forms. The liver produces a number of proproteins having a furin-cleavable site; thus, furin may be involved in growth and differentiation both in the partially hepatectomized liver and in primary cultured hepatocytes. Furin mRNA levels are elevated in tissues regenerated from partially hepatectomized rat liver. In primary culture of rat hepatocytes, furin expression increases gradually with time, and its expression is greatly enhanced by transforming growth factor beta1, whose processing from the precursor requires cleavage by furin. Thus, we suggest that the regeneration and differentiation of hepatocytes is dependent upon the co-elevation of furin and transforming growth factor beta1 mRNAs.