Heart 6-phosphofructo-2-kinase activation by insulin requires protein kinase B but not serum- and glucocorticoid-inducible protein kinase-3

Véronique Mouton , Louise Toussaint , Didier Vertommen , Marie-Agnès Gueuning , Liliane Maisin , Xavier Havaux , Cossette Sanchez Canedo , Luc Bertrand , Franck Dequiedt , Brian A Hemmings , Louis Hue , Mark H Rider (1)

1 de Duve Institute

Based on transfection experiments using a dominant-negative approach, our previous studies suggested that protein kinase B (PKB) was not involved in heart 6-phosphofruco-2-kinase (PFK-2) activation by insulin. Therefore, we first tested whether the serum- and glucocorticoid-inducible protein kinase-3 (SGK3) might be involved in this effect. Treatment of recombinant heart PFK-2 with [γ-32P] labelled ATP and SGK3 in vitro led to PFK-2 activation and phosphorylation at Ser466 and Ser483. However, in HEK 293T cells co-transfected with SGK3 siRNA and heart PFK-2, insulin-induced heart PFK-2 activation was unaffected. The involvement of PKB in heart PFK-2 activation by insulin was re-evaluated using different models: (i) hearts from transgenic mice with a muscle/heart-specific mutation in the PDK1 substrate docking site injected with insulin; (ii) hearts from PKBbeta deficient mice injected with insulin; (iii) freshly isolated rat cardimyocytes and perfused hearts treated with the selective Akti-1/2 PKB inhibitor prior to insulin, (iv) HEK 293T cells co-transfected with heart PFK-2 and PKBα/β siRNA or PKBα siRNA and incubated with insulin. Together, the results indicated that SGK3 is not required for insulin-induced PFK-2 activation and that this effect is likely mediated by PKBα.

Mots clés: Life Sciences

Véronique Mouton, Louise Toussaint, Didier Vertommen, Marie-Agnès Gueuning, Liliane Maisin, et al.. Heart 6-phosphofructo-2-kinase activation by insulin requires protein kinase B but not serum- and glucocorticoid-inducible protein kinase-3. Biochemical Journal, 2010, 431 (2), pp.267-275. ⟨10.1042/BJ20101089⟩. ⟨hal-00521560⟩