title: Nongenomic estrogen effects on nitric oxide synthase activity in rat adipocytes.
abstract: Estrogens exert multiple genomic effects on adipose tissue through binding to nuclear estrogen receptors. However, there is evidence for additional nongenomic mechanisms whereby estrogens may exert their control on adipose tissue metabolism through rapid activation of various membrane-initiated kinase cascades. Here, we tested rapid effects of estrogens on nitric oxide production in white adipose tissue using 17-beta estradiol (E2) and its membrane impermeant albumin conjugated form (17-beta estradiol hemisuccinate BSA, E2-BSA). We found that both E2 and E2-BSA stimulate nitric oxide synthase (NOS) activity in adipocytes. These effects were abolished by 1) ICI 182-780, a selective estrogen receptor antagonist; 2) wortmannin, an inhibitor of phosphatidylinositol 3-kinase; and 3) N-[2-(p-bromocinnamylamino) ethyl]-5-isoquinolinesulfonamide (H-89) an inhibitor of protein kinase A. In contrast to NOS activation by E2, E2-BSA-induced NOS activity was abolished by UO126, an inhibitor of MAPK kinase/ERK (p42/p44 MAPKs). Immunoblotting studies have shown that both estrogens phosphorylate endothelial NOS (NOS III) on Ser(1179), an effect that is prevented by wortmannin and H89, suggesting that NOS III is the target for estrogen-induced NOS activity. Furthermore, only the E2-BSA-induced NOS III phosphorylation on Ser(1179) was totally abolished by UO126. These results indicate that the signaling cascades involved in adipocyte NOS stimulation by estrogens are different depending on whether estrogens are free or conjugated to albumin and therefore underline the importance of estrogen receptor locations in the nongenomic actions of estrogens in these cells.
authors.affiliation: Départment de Biochimie et de Biologie Moléculaire, Université de Versailles Saint-Quentine en Yuelines, Versailles, France.
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Jaubert
authors.forename: Nadia
authors.initials: N
authors.lastname: Mehebik-Mojaat
authors.forename: Danièle
authors.initials: D
authors.lastname: Lacasa
authors.forename: Dominique
authors.initials: D
authors.lastname: Sabourault
authors.forename: Yves
authors.initials: Y
authors.lastname: Giudicelli
authors.forename: Catherine
authors.initials: C
authors.lastname: Ribière
mesh_terms: D052438:Adipocytes, White / Q000187:drug effects / Q000201:enzymology*; D000818:Animals; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D023281:Genomics; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011960:Receptors, Estrogen / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D012710:Serum Albumin, Bovine / Q000494:pharmacology
chemical_list: D017868:Cyclic AMP-Dependent Protein Kinases; D004958:Estradiol; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D052250:Nitric Oxide Synthase Type III; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D011960:Receptors, Estrogen; D012694:Serine; D012710:Serum Albumin, Bovine; C043090:estradiol-bovine serum albumin; C496316:Nos3 protein, rat