INTRACELLULAR-DISTRIBUTION OF PHOSPHOLIPASE C-GAMMA-1 IN CELL-LINES WITH DIFFERENT LEVELS OF TRANSFORMATION

The intracellular localization of phospholipase C gamma 1 (PLC gamma 1 ) was studied in tell Lines with different levels of cell transformati on, Immunofluorescence analysis of cell Lines with differently organiz ed actin cytoskeletons (A431 cells, HeLa cells, mouse hepatoma MH 22A, Zajdela ascitic hepatoma, primary human embryo skin and lung fibrobla sts) gave evidence that PLC gamma 1 is colocalized only with cortical actin and not with stress fibers, Coimmunoprecipitation experiments in dicated that PLC gamma 1 was bound to actin in all cell lines investig ated. Further, the nuclei of highly transformed cell Lines (A431 cells , HeLa cells, mouse hepatoma IM 22A, rat Zajdela ascitic hepatoma) wer e labeled with the anti-PLC gamma 1 antibody; In contrast, PLC gamma 1 was not observed in the nuclei of primary human embryo skin or lung f ibroblasts, Since PLC gamma 1 exists only in the nuclei of highly tran sformed cell lines, we propose that the distinctive intracellular loca lization of PLC gamma 1 in normal and highly transformed cell Lines ma y reflect differences in cell signaling systems and mitogenic cell sig nal transduction.