Isolation and characterization of rat 3Y1 fibroblast clones overexpressing the src homology region of phospholipase C-gamma 2.
To examine the regulatory function of the src-related SH2 and SH3 (SH2/SH3) region of phospholipase C-gamma 2 (PLC-gamma 2), we expressed this region of rat PLC-gamma 2 cDNA in rat 3Y1 fibroblasts and isolated and characterized a number of clones (approximately 20 clones). An increase of endogenous tyrosine kinase activity was observed in all cell clones that highly expressed a translational product of the SH2/SH3 domain. Moreover, endogenous phosphatidylinositol 4,5-bisphosphate hydrolyzing activity was also enhanced in these clones, and PLC-gamma 1 seemed to be preferentially activated among endogenous PLC isozymes. Genistein, an inhibitor of tyrosine kinase, inhibited this activation of PLC-gamma 1, and tyrosine phosphorylation was observed on PLC-gamma 1 molecules, indicating the involvement of tyrosine kinases in the PLC-gamma 1 activation. These results suggest that the SH2/SH3 region of PLC-gamma would function as a multidirectional regulator which controls at least two major signaling pathways: tyrosine kinase and phosphatidylinositol 4,5-bisphosphate hydrolysis.
Homma
Y
Y
Department of Biosignal Research, Tokyo Metropolitan Institute of Gerontology, Japan.
Emori
Y
Y
Takenawa
T
T
D000818:Animals; D002999:Clone Cells; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D005347:Fibroblasts; D016391:Genes, src; D019833:Genistein; D006868:Hydrolysis; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D007529:Isoflavones / Q000378:metabolism / Q000494:pharmacology; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols / Q000378:metabolism; D011233:Precipitin Tests; D014176:Protein Biosynthesis; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D014162:Transfection; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
D007527:Isoenzymes; D007529:Isoflavones; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D010738:Type C Phospholipases