Presence of different phospholipase C isoforms in the nucleus and their activation during compensatory liver growth

AbstractPhospholipase C (PLC) was purified from the membrane-depleted rat liver nuclei. About 60% of the total PLC-activity corresponded to β1b isoform, 30% to PLC-γ1 and less than 10% to PLC-δ1. PLC-β1b and -γ1 were found in the nuclear matrix, while PLC-δ1 was detected in the chromatin. Two peaks of an increase in the total PLC-activity were detected occurring at 6 and 20 h after partial hepatectomy. An early increase in PLC-β1b activity in the nuclear matrix was associated with serine phosphorylation of the enzyme, while the later increase paralleled the increase in the amount of protein. The increase in the PLC-γ1 activity measured at 6 and 20 h after partial hepatectomy was associated with tyrosine phosphorylation of the enzyme. The activity of PLC-δ1 and the amount of the protein found in the chromatin was increased only at 20 h after partial hepatectomy