RESUMO
BACKGROUND: Peroxisome proliferator-activated receptor γ coactivator- 1alpha (PGC-1α) plays an important role in whole body metabolism and, particularly in glucose homeostasis. Its expression is highly regulated and, small variations in tissue levels can have a major impact in a number of physiological and pathological conditions. Recent studies have shown that the ubiquitin/proteasome system plays a role in the control of PGC-1α degradation. METHODS: Here we evaluated the interaction of PGC-1α with the protein A20, which plays a dual-role in the control of the ubiquitin/proteasome system acting as a deubiquitinase and as an E3 ligase. We employed immunoprecipitation, quantitative real-time PCR and immunofluorescence staining to evaluate PGC-1α, A20, PPARγ and ubiquitin in the adipose tissue of humans and mice. RESULTS: In distinct sites of the adipose tissue, A20 binds to PGC-1α. At least in the subcutaneous fat of humans and mice the levels of PGC-1α decrease during obesity, while its physical association with A20 increases. The inhibition of A20 leads to a reduction of PGC-1α and PPARγ expression, suggesting that A20 acts as a protective factor against PGC-1α disposal. CONCLUSION: We provide evidence that mechanisms regulating PGC-1α ubiquitination are potentially involved in the control of the function of this transcriptional co-activator.
Assuntos
Tecido Adiposo/metabolismo , Obesidade/genética , PPAR gama/genética , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/genética , Proteína 3 Induzida por Fator de Necrose Tumoral alfa/genética , Tecido Adiposo/patologia , Adulto , Animais , Estudos de Casos e Controles , Metabolismo Energético/genética , Feminino , Regulação da Expressão Gênica , Glucose/metabolismo , Homeostase/genética , Humanos , Masculino , Camundongos , Obesidade/metabolismo , Obesidade/patologia , PPAR gama/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Ligação Proteica , Transdução de Sinais , Proteína 3 Induzida por Fator de Necrose Tumoral alfa/metabolismo , Ubiquitina/genética , Ubiquitina/metabolismo , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismoRESUMO
The development of new methods to improve skin wound healing may affect the outcomes of a number of medical conditions. Here, we evaluate the molecular and clinical effects of topical 5-azacytidine on wound healing in rats. 5-Azacytidine decreases the expression of follistatin-1, which negatively regulates activins. Activins, in turn, promote cell growth in different tissues, including the skin. Eight-week-old male Wistar rats were submitted to 8.0-mm punch-wounding in the dorsal region. After 3 days, rats were randomly assigned to receive either a control treatment or the topical application of a solution containing 5-azacytidine (10 mM) once per day. Photo documentation and sample collection were performed on days 5, 9, and 15. Overall, 5-azacytidine promoted a significant acceleration of complete wound healing (99.7% ± 0.7.0 vs. 71.2% ± 2.8 on day 15; n = 10; p < 0.01), accompanied by up to threefold reduction in follistatin expression. Histological examination of the skin revealed efficient reepithelization and cell proliferation, as evaluated by the BrdU incorporation method. 5-Azacytidine treatment also resulted in increased gene expression of transforming growth factor-beta and the keratinocyte markers involucrin and cytokeratin, as well as decreased expression of cytokines such as tumor necrosis factor-alpha and interleukin-10. Lastly, when recombinant follistatin was applied to the skin in parallel with topical 5-azacytidine, most of the beneficial effects of the drug were lost. Thus, 5-azacytidine acts, at least in part through the follistatin/activin pathway, to improve skin wound healing in rodents.