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Evidence for a functional nitric oxide synthase system in brown adipocyte nucleus
Author(s) -
Giordano Antonio,
Tonello Cristina,
Bulbarelli Alessandra,
Cozzi Valeria,
Cinti Saverio,
Carruba Michele O,
Nisoli Enzo
Publication year - 2002
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(02)02245-7
Subject(s) - nitric oxide synthase , enos , nucleus , cytosol , endothelial nos , medicine , endocrinology , cytoplasm , nitric oxide , adipocyte , chemistry , nitric oxide synthase type iii , citrulline , biology , biochemistry , arginine , adipose tissue , microbiology and biotechnology , enzyme , amino acid
The intracellular localization and activity of the nitric oxide synthase (NOS) isoforms were investigated in rat brown adipocytes. Immunohistochemistry showed cytoplasmic and nuclear staining for the endothelial NOS (eNOS) and inducible NOS (iNOS) isoforms; accordingly, anti‐ L ‐citrulline antibody, a marker of NOS activity, immunostained both the cytoplasm and the nucleus. The presence of metabolically active NOS in the nucleus was further confirmed by immunoblotting analyses of subcellular fractions of homogenates from cultured brown adipocytes and by measurements of NOS activity in the cytosol and nucleus. Sympathetic stimulation in vivo (i.e. cold exposure or β 3 ‐adrenergic agonist treatment) and in vitro (i.e. noradrenaline treatment of cultured cells) significantly increased both cytosolic and nuclear eNOS and iNOS expression and activities. By contrast, the number of iNOS‐positive, but not eNOS‐positive, nuclei was significantly lower in the functionally impaired brown fat of genetically obese Zucker fa/fa rats. These data suggest the existence of a noradrenaline‐modulated functional NOS system in the nucleus of brown adipocytes.