Activation of 6-phosphofructo-2-kinase by pp60v-src is an indirect effect.
6-Phosphofructo-2-kinase (PFK-2) catalyses the synthesis of fructose 2,6-bisphosphate (Fru-2,6-P2), a potent stimulator of glycolysis. In chick-embryo fibroblasts, PFK-2 activity and Fru-2,6-P2 concentration increase upon transformation by Rous sarcoma virus. We show here that the increase in PFK-2 activity required more than 2 h after shifting fibroblasts infected with a thermosensitive mutant of Rous sarcoma virus from the restrictive to the permissive temperature. Pretreatment of the cells with actinomycin D prevented this increase in PFK-2 activity, suggesting a requirement for RNA synthesis. However, the increase in PFK-2 activity did not correspond to an increase in immunoprecipitable PFK-2. Moreover, the thermostability of PFK-2 and the affinity of this enzyme for its substrate fructose 6-phosphate were increased upon transformation by Rous sarcoma virus. Staurosporine, an inhibitor of protein kinase C, prevented the increase in PFK-2 activity brought about by the shift to the permissive temperature. This, together with a comparison of the effects of phorbol esters on PFK-2 activity, suggests that pp60v-src stimulates, via protein kinase C, the transcription of a gene whose products is a distinct PFK-2 isoenzyme or a protein that activates PFK-2.
Marchand
M J
MJ
Hormone and Metabolic Research Unit, University of Louvain Medical School, Brussels, Belgium.
Maisin
L
L
Hue
L
L
Rousseau
G G
GG
D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D001358:Avian Sarcoma Viruses; D002472:Cell Transformation, Viral; D002642:Chick Embryo; D003609:Dactinomycin / Q000494:pharmacology; D004789:Enzyme Activation; D004795:Enzyme Stability; D005347:Fibroblasts / Q000201:enzymology; D005635:Fructosediphosphates / Q000378:metabolism; D006358:Hot Temperature; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D015688:Oncogene Protein pp60(v-src) / Q000378:metabolism*; D025481:Phosphofructokinase-2; D010770:Phosphotransferases / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D019311:Staurosporine; D013379:Substrate Specificity
D000470:Alkaloids; D005635:Fructosediphosphates; D003609:Dactinomycin; C027652:fructose 2,6-diphosphate; D010770:Phosphotransferases; D025481:Phosphofructokinase-2; D015688:Oncogene Protein pp60(v-src); D011493:Protein Kinase C; D019311:Staurosporine