Insulin stimulates nitric oxide production in rat adipocytes.
In adipocytes, insulin regulates the activity of different protein kinases (PI3K/Akt, MAPK, PKC) and protein phosphatases (PP-1, PP-2A). Since these enzymes are implicated in the regulation of NOS activity which is present in adipose tissue, we tested the effects of insulin on white adipocyte NOS activity. Exposure of adipocytes to insulin resulted simultaneously in NOS activity stimulation and Akt activation with maximal effect observed at 1 nM. Higher concentrations of insulin induced a progressive decline of NOS activity. In the presence of wortmannin, a PI3K inhibitor, 1 nM insulin failed to stimulate NOS activity. Insulin (1 nM)-stimulated NOS activity was also abolished by U0126, an inhibitor of p42/p44 MAPK activation, and by 1 microM okadaic acid (OA), which inhibits both PP-1 and PP-2A but not by 1 nM OA which inhibits only PP-2A. Moreover, inhibition of cPKC allowed a high (1 microM) insulin concentration to stimulate NOS activity. These results (i) demonstrate that insulin activates NO production in adipocytes through both PI3K/Akt and MAPK/PP-1 activation and (ii) suggest that PP-1 activation protects NOS against the inhibitory effect of cPKC activation.
Ribière
Catherine
C
Laboratory of Biochemistry and Molecular Biology, Faculté de Médecine Paris-Ouest, UFR Biomédicale des Saints-Pères, Université Paris V, 45 rue des Saints-Pères, Paris, France. catherine.ribiere@paris-ouest.univ-paris5.fr
Jaubert
Anne-Marie
AM
Sabourault
Dominique
D
Lacasa
Danièle
D
Giudicelli
Yves
Y
D017667:Adipocytes / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D002070:Butadienes / Q000494:pharmacology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology*; D007425:Intracellular Membranes / Q000737:chemistry; D008297:Male; D008301:Maleimides / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000032:analysis; D052250:Nitric Oxide Synthase Type III; D009570:Nitriles / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017207:Rats, Sprague-Dawley; D000077191:Wortmannin
D000730:Androstadienes; D002070:Butadienes; D004791:Enzyme Inhibitors; D007211:Indoles; D007328:Insulin; D008301:Maleimides; D009570:Nitriles; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011518:Proto-Oncogene Proteins; C113580:U 0126; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; C070515:bisindolylmaleimide I; D000077191:Wortmannin