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This Article Full Text Full Text (PDF) All Versions of this Article: 294/4/C1088    most recent 00523.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Drenning, J. A. Articles by Criswell, D. S. PubMed PubMed Citation Articles by Drenning, J. A. Articles by Criswell, D. S.

MUSCLE CELL BIOLOGY AND CELL MOTILITY

Nitric oxide facilitates NFAT-dependent transcription in mouse myotubes

Center for Exercise Science, Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, Florida

Submitted 12 December 2007 ; accepted in final form 7 February 2008

Intracellular calcium transients in skeletal muscle cells initiate phenotypic adaptations via activation of calcineurin and its effector nuclear factor of activated t-cells (NFAT). Furthermore, endogenous production of nitric oxide (NO) via calcium-calmodulin-dependent NO synthase (NOS) is involved in skeletal muscle phenotypic plasticity. Here, we provide evidence that NO enhances calcium-dependent nuclear accumulation and transcriptional activity of NFAT and induces phosphorylation of glycogen synthase kinase-3β (GSK-3β) in C2C12 myotubes. The calcium ionophore A23187 [GenBank] (1 µM for 9 h) or thapsigargin (2 µM for 4 h) increased NFAT transcriptional activity by seven- and fourfold, respectively, in myotubes transiently transfected with an NFAT-dependent reporter plasmid (pNFAT-luc, Stratagene). Cotreatment with the NOS-inhibitor N^G-nitro-L-arginine methyl ester (L-NAME; 5 mM) or the guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 µM) prevented the calcium effects on NFAT activity. The NO donor diethylenetriamine-NONO (DETA-NO; 10 µM) augmented the effects of A23187 [GenBank] on NFAT-dependent transcription. Similarly, A23187 [GenBank] (0.4 µM for 4 h) caused nuclear accumulation of NFAT and increased phosphorylation (i.e., inactivation) of GSK-3β, whereas cotreatment with L-NAME or ODQ inhibited these responses. Finally, the NO donor 3-(2-hydroxy-2-nitroso-1-propylhydrazino)-1-propanamine (PAPA-NO; 1 µM for 1 h) increased phosphorylation of GSK-3β in a manner dependent on guanylate cyclase activity. We conclude that NOS activity mediates calcium-induced phosphorylation of GSK-3β and activation of NFAT-dependent transcription in myotubes. Furthermore, these effects of NO are guanylate cyclase-dependent.

nitric oxide synthase; nuclear factor of activated t-cells; glycogen synthase kinase-3β; soluble guanylate cyclase; myosin heavy chain I/β