Integration of DIGE and bioinformatics analyses reveals a role of the antiobesity agent tungstate in redox and energy homeostasis pathways in brown adipose tissue.
Our previous results demonstrated that tungstate decreased weight gain and adiposity in obese rats through increased thermogenesis and lipid oxidation, suggesting that brown adipose tissue was one of the targets of its antiobesity effect. To identify potential targets of tungstate, we used DIGE to compare brown adipose tissue protein extracts from the following experimental groups: untreated lean, tungstate-treated lean, untreated obese, and tungstate-treated obese rats. To distinguish direct targets of tungstate action from those that are secondary to body weight loss, we also included in the analysis an additional group consisting of obese rats that lose weight by caloric restriction. Hierarchical clustering of analysis of variance and t test contrasts clearly separated the different experimental groups. DIGE analysis identified 20 proteins as tungstate obesity direct targets involved in Krebs cycle, glycolysis, lipolysis and fatty acid oxidation, electron transport, and redox. Protein oxidation was decreased by tungstate treatment, confirming a role in redox processes; however, palmitate oxidation, as a measure of fatty acid beta-oxidation, was not altered by tungstate, thus questioning its putative function in fatty acid oxidation. Protein network analyses using Ingenuity Pathways Analysis highlighted peroxisome proliferator-activated receptor gamma coactivator 1alpha (PGC-1alpha) as a potential target. We confirmed by real time PCR that indeed tungstate up-regulates PGC-1alpha, and its major target, uncoupling protein 1, was also increased as shown by Western blot. These results illustrate the utility of proteomics and bioinformatics approaches to identify targets of obesity therapies and suggest that in brown adipose tissue tungstate modulates redox processes and increases energy dissipation through uncoupling and PGC-1alpha up-regulation, thus contributing to its overall antiobesity effect.
Barceló-Batllori
Sílvia
S
Laboratory of Experimental Diabetes and Obesity, Endocrinology and Diabetes Unit, Hospital Clínic de Barcelona, E-08036 Barcelona, Catalonia, Spain. sbarcelo@clinic.ub.es
Kalko
Susana G
SG
Esteban
Yaiza
Y
Moreno
Sílvia
S
Carmona
María C
MC
Gomis
Ramon
R
D002001:Adipose Tissue, Brown / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D019440:Anti-Obesity Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000378:metabolism; D031204:Caloric Restriction; D019295:Computational Biology / Q000379:methods*; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods*; D004734:Energy Metabolism / Q000187:drug effects*; D005786:Gene Expression Regulation / Q000187:drug effects; D006706:Homeostasis / Q000187:drug effects*; D007473:Ion Channels / Q000378:metabolism; D050356:Lipid Metabolism / Q000187:drug effects; D008297:Male; D024101:Mitochondrial Proteins / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D020543:Proteome / Q000737:chemistry / Q000378:metabolism; D016601:RNA-Binding Proteins; D051381:Rats; D017208:Rats, Wistar; D012984:Software; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D017973:Tungsten Compounds / Q000494:pharmacology*; D000071256:Uncoupling Protein 1
D019440:Anti-Obesity Agents; D000975:Antioxidants; D007473:Ion Channels; D024101:Mitochondrial Proteins; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C501429:Ppargc1a protein, rat; D020543:Proteome; D016601:RNA-Binding Proteins; D014157:Transcription Factors; D017973:Tungsten Compounds; C000604373:Ucp1 protein, rat; D000071256:Uncoupling Protein 1; C045951:tungstate