CELLULAR SIGNALING EVENTS ELICITED BY V-ABL ASSOCIATED WITH GROWTH-FACTOR INDEPENDENCE IN AN INTERLEUKIN-3-DEPENDENT CELL-LINE

A temperature-sensitive mutant of the v-abl oncoprotein has previously been shown to have markedly reduced tyrosine protein kinase activity in interleukin 3 (IL-3)-dependent cells grown at restrictive (39-degre es-C), compared to permissive (32-degrees-C) temperatures. Transfectio n of this mutant v-abl into the IC2.9 cell line, generated the IC.DP s ubclone which was dependent on IL-3 for survival at 39-degrees-C, but not at 32-degrees-C. Furthermore, IC.DP cells cultured at 32-degrees-C exhibited IL-3-independent thymidine incorporation, which was not app arent at 39-degrees-C. Switching cells from the restrictive to the per missive temperature resulted in an increase in cellular inositol-1,4,5 -trisphosphate, choline phosphate and diacylglycerol levels in the IC. DP cell line. These increases were only observed after a lag period of 4 h. Within 2 h of switching IC.DP cells previously maintained at 32 to 39-degrees-C, there was a significant decrease in all three metabol ites. Temperature switches had no effect upon these metabolites in the parent IC2.9 cell line. Down-regulation of protein kinase C inhibited v-abl-stimulated DNA synthesis in IC.DP cells cultured at 32-degrees- C. IC.DP cells cultured at 32-degrees-C were found to have a constitut ively activated Na+/H+ antiport, although this activation was inhibite d by the down-modulation of protein kinase C. These data indicate a ro le for phospholipid hydrolysis and protein kinase C activation in V-AB L-mediated abrogation of IL-3 dependence.