Overexpression of fructose 2,6-bisphosphatase decreases glycolysis and delays cell cycle progression

The ability to overexpress 6-phosphofructo-2-kinase/fructose 2,6-bisphospha tase (PFK-2)/( FB-Pase-2) or a truncated form of the enzyme with only the b isphosphatase domain allowed us to analyze the relative role of the kinase and the bisphosphatase activities in regulating fructose 2,6-bisphosphate ( Fru-2,6-P-2) concentration and to elucidate their differential metabolic im pact in epithelial Mv1Lu cells. The effect of overexpressing PFK-2/FB-Pase- 2 resulted in a small increase in the kinase activity and in the activity ratio of the bifunctional enzyme, increasing Fru-2,6-P-2 levels, but these changes had no major effects on cell metabolism. In contrast, expression of the bisphosphatase domain increased the bisphosphatase activity, producing a significant decrease in Fru-2,6-P-2 concentration. The fall in the bisph osphorylated metabolite correlated with a decrease in lactate production an d ATP concentration, as well as a delay in cell cycle. These results provid e support for Fru-2,6-P-2 as a regulator of glycolytic flux and point out t he role of glycolysis in cell cycle progression.