[Expression of the protein kinase C genes during liver regeneration]

Protein kinase C (PKC) plays an important role in intracellular signaling. PKC consists of a family of at least eight distinct enzymes. How PKC can be responded to liver regeneration and growth is largely unknown. In an in vivo experiment, regenerating liver after partial hepatectomy (Hx) and carbon tetrachloride (CCl4) administration, expression of the PKC alpha-type was increased, with a single peak, after Hx and CCl4 administration. On the other hand, the PKC epsilon-type gene was activated with biphasic peaks following Hx but was elevated with a single peak after the CCl4 administration. In an in vitro experiment using primary cultured hepatocytes, both of the PKC alpha-type and epsilon-type genes could be induced only by combination of insulin and serum. These results demonstrate that both isoforms of PKC are identically regulated by extra- and intracellular stimuli, thereby influencing growth control of hepatocytes.