Effect of aging on insulin regulation of fructose 2,6-bisphosphate metabolism in human fibroblasts.

Fructose 2,6-bisphosphate (Fru-2,6-P2) content in human fibroblasts is under hormonal control and is strictly related to glycolytic flux. In the present study it has been examined whether aging process is accompanied with an impairment in the control exerted by insulin on the metabolite content. Upon insulin stimulation old fibroblasts show a reduced increase in Fru-2,6-P2 content and glycolytic flux. Similarly, 6-phosphofructo-2-kinase (PFK-2) activity in old fibroblasts is increased at a lesser extent by insulin treatment, suggesting that an impairment at post-receptor level in the signalling pathway of insulin might occur with aging. In addition in unstimulated senescent fibroblasts PFK-2 displays higher activity and reduced Km for substrate, suggesting either that during senescence PFK-2 undergoes a post-translational modification or that a different PFK-2 isoenzyme is expressed.