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

Phospholipase C (PLC) was purified from the membrane-depleted rat liver nuclei. About 60% of the total PLC-activity corresponded to beta(1b) isoform, 30% to PLC-gamma(1) and less than 10% to PLC-delta(t). PLC-beta(1b) and -gamma(1) were found in the nuclear matrix, while PLC-delta(1) 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-beta(1b) 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-gamma(1) activity measured at 6 and 20 h after partial hepatectomy was associated with tyrosine phosphorylation of the enzyme. The activity of PLC-delta(1) and the amount of the protein found in the chromatin was increased only at 20 h after partial hepatectomy. (C) 2004 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.