Protein kinase C isozymes during liver regeneration.

Protein kinase C isozyme (alpha, beta, delta and zeta) activities have been studied in compensatory cell proliferation at 20 and 24 hours after partial hepatectomy. Chromatographic analysis of PKC isozymes in male rats showed an activation of delta at 20 h after partial hepatectomy and of alpha, beta and zeta at 24 in correspondence with S phase peak. A peculiar sexual dimorphism, which matched sexual differences in DNA synthesis, has been observed. The administration of an excess of choline was able to modulate the protein kinase C isozyme pattern in females in relation to DNA synthesis and c-myc expression. Our data suggest that alpha, beta and zeta PKC positively regulated, while delta negatively controlled the liver compensatory growth after partial hepatectomy.