Regulation of hemopexin transcription by calcium ionophores and phorbol ester in hepatoma cells.

Hemopexin (Hx) is an acute-phase hepatic protein, whose transcription is upregulated by IL-6. The transcription rate of Hx was found to be increased 11-fold by the calcium ionophore A23187, 25-fold by the calcium ionophore ionomycin, and 4-5-fold by phorbol 12-myristate 13-acetate (PMA) in serum-starved H4IIE rat hepatoma cells. Insulin did not affect the transcription rate of Hx. These findings are consistent with involvement of intracellular calcium concentrations and activation of protein kinase C (PKC) action in the regulation of Hx.