The Transcriptional Regulation Of Adipose And The Study Of Its Function

Adipose tissue is the crucial organ for energy storage and metabolic, excess deposition of fat in other tissues may led to a series of heath problems, such as fatty liver, myopathy and so on. Adipose (Adp) was first identified as an obesity-related gene in Drosophila. This gene is conserved from flies to humans. Overexpression of the Adp gene in mice adipose tissue reduces lipid accumulation, and high Adp expression in human adipose tissue is related to lower adiposity and improvement of insulin sensitivity. Here we analysed 5’-flanking region of Adp promoter and identified several potential binding sites for pivotal transcriptional factors, the KLFs binding sites catched our attention. We performed BLAST analysis of human, pig and mouse 5’-flanking regions to identify whether they shared homologous in the three species. The results exhibited that several cis-acting elements for KLFs, CREB, and NF-κB were conserved in the detected region.We have confirmed that KLF6 and KLF15 can enhance the promoter activity of Adp and up-regulate its mRNA expression. Using EMSA, ChIP and mutant assay, we found that KLF15 regulated the expression of Adp via binding to its response elements in Adp promoter region. To investigate the influence of TNFa on Adp expression, protein and mRNA levels were examined. Adp mRNA and protein levels were decreased in both C2C12 and IBRS2 cells. Further research showed that the decrease in Adp expression by TNFa was mediated at the transcription level. A decrease of KLF15 mRNA expression was observed after TNFa treatment. KLF15 overexpression was found to abrogate the TNFa-mediated inhibition of Adp gene promoter. TNFa interfered with formation of the KLF15-DNA complex at the KLF15 binding sites. The data also suggested that the reduction of endogenous KLF15 expression may be involved in the TNFa-mediated transcription of Adp gene. KLF15 was also found to participate in Adp-mediated myogenic differentiation.Adp plays a crucial role in adipogenesis. It forms a complex with H2B, H4 and histone deacetylase 3 (HDAC3) that suppresses the transcriptional activity of peroxisome proliferator-activated receptor gamma (PPARγ). We found that the expression of Adp was increase during adipogenesis. To investigate the regulation mechanism of Adp on PPARy expression, we transfected Adp with the PPARy promoter. The results showed that Adp repressed the activity of PPARy promoter. Using bioinformatics approaches, we identified several PPARy binding sites. ChIP and mutant assay suggested that Adp can bind to one of the PPARy responding sites. Co-immunoprecipitation showed that Adp can interact with PPARy. Adp inhibited PPARy expression by interaction with PPARy and binding to its promoter region, then suppressed the transcriptional activity of PPARy. Adipogenesis of the 3T3-L1 cell line is accompanied by a stimulation of mitochondrial biogenesis. Mito-Tracker Green stain research showed that overexpressing Adp reduced the amount of mitochondria.