Interleukin 2 activates nuclear phospholipase Cbeta by mitogen-activated protein kinase-dependent phosphorylation in human natural killer cells.

SPECIFIC AIMAnalyzing the nuclear phospholipase C (PLC) signaling in primary human natural killer (NK) cells and its role in their proliferation induced by interleukin 2 (IL-2), we found that 1) IL-2 transiently stimulates nuclear PLCβ1b activity within 60 min of treatment; 2) IL-2 induces nuclear translocation of mitogen-activated protein kinase (MAPK), namely, extracellular signal-related kinase 2 (ERK-2) or p42-MAPK and, to a lesser extent, of ERK-1 or p44-MAPK, whose specific inhibition prevents the IL-2-driven nuclear PLCβ1 activation; 3) PLCβ1b is serine-phosphorylated after IL-2 treatment and the phosphorylation is abolished after MAPK inhibition; 4) inhibition of nuclear PLC activation leads to the inhibition of the IL-2-induced proliferation of NK cells.PRINCIPAL FINDINGS1. Nuclear PLC activity in NK cells is up-regulated by IL-2The PLC assay has been paralleled by the measurement of the actual mass of nuclear diacylglycerol (DAG) after IL-2 treatment of living NK cells showed an increase of this...