Control of Fructose 2,6-Bisphosphate Metabolism by Different Mitogenic Signals in Swiss 3T3 Fibroblasts

Abstract

The mitogenic signals that control fructose 2,6-bisphosphate metabolism in murine Swiss 3T3 fibroblasts have been studied. Bombesin, vasopressin, insulin, protein kinase C activation by phorbol esters, or increase in the intracellular cAMP concentration by forskolin induced an increase in fructose 2,6-bisphosphate levels. When the cells were incubated in the presence of insulin or phorbol esters, an increase in the V max of 6-phosphofructo-2-kinase activity was observed. However, forskolin did not produce this effect. The increase in 6-phosphofructo-2-kinase activity elicited by phorbol 12,13-dibutyrate was blocked by cycloheximide. In contrast, the effect of insulin did not require protein synthesis. This study demonstrates that different mitogenic signal transduction pathways control the levels of fructose 2,6-bisphosphate. The high rate of glycolysis in proliferating Swiss 3T3 cells may be explained by an increase in the levels of this regulatory metabolite.