RESUMO
Adipocyte differentiation is regulated by a transcriptional cascade that mainly includes CCAAT/enhancer-binding protein family members and the nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ). Here we show the defects in adipocyte differentiation as well as PPARγ expression in Senp1(-/-) mouse embryonic fibroblast cells induced by adipogenic stimuli. We further determine that SENP1 is a specific de-SUMOylation protease for Sharp-1, a repressor for PPARγ transcription and adipogenesis. SENP1 enhances adipogenesis through de-SUMOylation of Sharp-1, which then releases Sharp-1 repression of PPARγ expression and adipocyte differentiation. These results reveal SENP1 as a novel regulator in adipogenesis.
Assuntos
Adipócitos/citologia , Adipócitos/metabolismo , Endopeptidases/metabolismo , Fatores de Transcrição/metabolismo , Células 3T3-L1 , Adipogenia/fisiologia , Animais , Diferenciação Celular/fisiologia , Células Cultivadas , Cisteína Endopeptidases , Endopeptidases/deficiência , Endopeptidases/genética , Regulação da Expressão Gênica , Camundongos , Camundongos Knockout , Mutagênese Sítio-Dirigida , PPAR gama/genética , PPAR gama/metabolismo , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina/metabolismo , Sumoilação , Fatores de Transcrição/química , Fatores de Transcrição/genéticaRESUMO
Adipose triglyceride lipase (ATGL), as an adipose-enriched protein, is able to hydrolyze triglycerides and plays an important part in triglyceride lipolysis of fat tissue. Leptin, an adipocyte cytokine, can increase the fat decomposition process. Many phenomena indicate that ATGL has a close relationship with leptin's promoting the hydrolysis of triglycerides. However, the regulatory mechanism of ATGL in leptin's promoting fat hydrolysis has not been directly and systematically studied yet. This study demonstrated that ATGL was expressed in vitro by leptin regulation. The amount of ATGL mRNA increased and the amount of ATGL protein decreased based on a dose-dependent manner when leptin concentrations ranged from 5 to 50 ng/ml were used to treat fully differentiated porcine adipocytes for 3 h. In addition, this study revealed that JAK-STAT and MAPK signaling pathways, as well as PPAR gamma all played important roles in the ATGL expression mediated by leptin.
Assuntos
Adipócitos/metabolismo , Regulação Enzimológica da Expressão Gênica , Leptina/farmacologia , Lipase/genética , Lipólise , Adipócitos/enzimologia , Animais , Células Cultivadas , Lipase/análise , MAP Quinase Quinase 4 , Sistema de Sinalização das MAP Quinases , PPAR gama , RNA Mensageiro/análise , Fatores de Transcrição STAT , Transdução de Sinais , SuínosRESUMO
Sirt2, a NAD(+)-dependent histone deacetylase, plays a critical role in regulating lifespan, metabolism, mitosis and adipocyte differentiation. Here two bands of the porcine Sirt2 protein were found by western blotting, so we speculated existence of Sirt2 isoforms. Next, we cloned the porcine Sirt2 gene, and also found its alternative splice variant and named the novel splicing variant Sirt2(T). The complete cDNA sequence of Sirt2(T) is 1059 bp, encoding a deduced protein of 352 amino acids which is 39 amino acids shorter at the N-terminus than Sirt2. RT-PCR revealed that the Sirt2(T) mRNA is extensively expressed in porcine tissues, and can be expressed during adipocyte differentiation. In addition, immunofluorescence and transfection demonstrated that Sirt2(T) is located in the cytoplasm and nucleus.