title: Taurine in adipocytes prevents insulin-mediated H2O2 generation and activates Pka and lipolysis.
abstract: Among many actions assigned to taurine (Tau), the most abundant amino acid in numerous mammalian tissues, it prevents high-fat diet-induced obesity with increasing resting energy expenditure. To sustain this Tau action, the goal of the present study was to explore the acute effects of Tau on baseline and on adrenaline, insulin and their second messengers to modulate lipolysis in white adipose tissue (WAT) cells from rat epididymis. The Tau effects in this topic were compared with those recorded with Gly, Cys and Met. Tau on its own did not modify baseline lipolysis. Tau raised isoproterenol- and dibutyryl-cAMP (Bt2cAMP)-activated glycerol release. Gly diminished Bt2cAMP-activated glycerol release, and Cys and Met had no effect. Cyclic AMP-dependent activation of protein kinase A (PKA) in cell-free extracts decreased slightly by Gly and was unaltered by Cys, Met, and Tau. PKA catalytic activity in cell-free extracts was stimulated by Tau and unchanged by Cys, Gly and Met. Gly and Tau effects on PKA disappeared when these amino acids were withdrawn by gel filtration. Insulin-mediated NADPH-oxidase (NOX) raises H2O2 pool, which promotes PKA subunit oxidation, and precludes its cAMP activation; thus, lipolysis is diminished. Tau, but not Cys, Gly and Met, inhibited, by as much as 70%, insulin-mediated H2O2 pool increase. These data suggested that Tau raised lipolysis in adipocytes by two mechanisms: stimulating cAMP-dependent PKA catalytic activity and favoring PKA activation by cAMP as a consequence of lowering the H2O2 pool.
authors.affiliation: Department of Biochemistry, Faculty of Medicine, National Autonomous University of Mexico, P.O. Box 70159, 04510, Mexico, D.F, Mexico.
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Piña-Zentella
authors.forename: Gilda
authors.initials: G
authors.lastname: de la Rosa-Cuevas
authors.forename: Héctor
authors.initials: H
authors.lastname: Vázquez-Meza
authors.forename: Enrique
authors.initials: E
authors.lastname: Piña
authors.forename: Martha Zentella
authors.initials: MZ
authors.lastname: de Piña
mesh_terms: D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D002474:Cell-Free System; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004822:Epididymis / Q000378:metabolism; D005998:Glycine / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D008066:Lipolysis / Q000187:drug effects*; D008297:Male; D019255:NADPH Oxidases / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013654:Taurine / Q000008:administration & dosage*
chemical_list: D007328:Insulin; D013654:Taurine; D006861:Hydrogen Peroxide; D000242:Cyclic AMP; D019255:NADPH Oxidases; D017868:Cyclic AMP-Dependent Protein Kinases; D007545:Isoproterenol; D005998:Glycine