title: Neuronal nitric oxide synthase is phosphorylated in response to insulin stimulation in skeletal muscle.
abstract: Type 2 Diabetes (T2DM) is the seventh leading cause of death in the United States, and is quickly becoming a global pandemic. T2DM results from reduced insulin sensitivity coupled with a relative failure of insulin secretion. Reduced insulin sensitivity has been associated with reduced nitric oxide synthase (NOS) activity and impaired glucose uptake in T2DM skeletal muscle. Upon insulin stimulation, NO synthesis increases in normal adult skeletal muscle, whereas no such increase is observed in T2DM adults. Endothelial NOS is activated by phosphorylation in the C-terminal tail in response to insulin. Neuronal NOS (nNOS), the primary NOS isoform in skeletal muscle, contains a homologous phosphorylation site, raising the possibility that nNOS, too, may undergo an activating phosphorylation event upon insulin treatment. Yet it remains unknown if or how nNOS is regulated by insulin in skeletal muscle. Data shown herein indicate that nNOS is phosphorylated in response to insulin in skeletal muscle and that this phosphorylation event occurs rapidly in C2C12 myotubes, resulting in increased NO production. In vivo phosphorylation of nNOS was also observed in response to insulin in mouse skeletal muscle. These results indicate, for the first time, that nNOS is phosphorylated in skeletal muscle in response to insulin and in association with increased NO production.
authors.affiliation: Department of Biochemistry, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Dr., San Antonio, TX 78229-7760, USA.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Hinchee-Rodriguez
authors.forename: Neha
authors.initials: N
authors.lastname: Garg
authors.forename: Priya
authors.initials: P
authors.lastname: Venkatakrishnan
authors.forename: Madeline G
authors.initials: MG
authors.lastname: Roman
authors.forename: Martin L
authors.initials: ML
authors.lastname: Adamo
authors.forename: Bettie Sue
authors.initials: BS
authors.lastname: Masters
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Roman
mesh_terms: D000818:Animals; D002460:Cell Line; D003924:Diabetes Mellitus, Type 2 / Q000201:enzymology / Q000378:metabolism; D007328:Insulin / Q000378:metabolism* / Q000494:pharmacology; D007333:Insulin Resistance; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D009569:Nitric Oxide / Q000096:biosynthesis; D052248:Nitric Oxide Synthase Type I / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation
chemical_list: D007328:Insulin; D009569:Nitric Oxide; D052248:Nitric Oxide Synthase Type I; C496321:Nos1 protein, mouse