Portal de Periódicos da CAPES

Endothelial nitric oxide synthase is involved in calcium-induced Akt signaling in mouse skeletal muscle

2009; Elsevier BV; Volume: 21; Issue: 3-4 Linguagem: Inglês

10.1016/j.niox.2009.08.001

1089-8611

J Drenning, Vitor A. Lira, Quinlyn A. Soltow, Claire N. Canon, Lauren M. Valera, Dana L. Brown, David S. Criswell,

Adipose Tissue and Metabolism

We hypothesized that targeted mutation of the endothelial nitric oxide synthase (eNOS) gene would reduce Akt-related signaling events in skeletal muscle cells, compared to wild type (WT) controls. Results show that slow myosin heavy chain (type I/beta) expression and the abundance of slow-twitch fibers are reduced in plantaris muscle of eNOS(-/-) mice, compared to WT. Further, basal phosphorylation of Akt (p-Akt (Ser-473)/total Akt) and GSK-3beta (GSK-3beta (Ser-9)/total GSK-3beta) are reduced 60-70% in primary myotubes from eNOS(-/-) mice. Treatment with the calcium ionophore, A23187 (0.4 microM, 1 h), increased phosphorylation of Akt and GSK-3beta by approximately 2-fold (P<0.05) in myotubes from WT mice, but had no effect on phosphorylation of these proteins in eNOS(-/-) myotubes. Additionally, A23187 treatment failed to induce nuclear translocation of the transcription factor, NFATc1, in eNOS(-/-) myotubes. Treatment with the nitric oxide donor, propylamine propylamine NONOate (PAPA-NO; 1 microM for 1 h) increased Akt and GSK-3beta phosphorylation, and induced NFATc1 nuclear translocation in WT and eNOS(-/-) myotubes, and eliminated differences from WT in the NOS knockout cultures. Parallel experiments in C2C12 myotubes found that Akt phosphorylation induced by NO or the guanylate cyclase activator, YC-1, is prevented by co-treatment with either a guanylate cyclase or PI3K inhibitor (10 microM ODQ or 25 microM LY2904002, respectively). These data suggest that eNOS activity is necessary for calcium-induced activation of the Akt pathway, and that nitric oxide is sufficient to elevate Akt activity in primary myotubes. NO appears to influence Akt signaling through a cGMP, PI3K-dependent pathway.