ABSTRACT
Nuclear receptor subfamily 4 group A member 1 (NR4A1) is an orphan nuclear receptor with diverse functions. It has been reported that NR4A1, as a transcriptional activator, is implicated in glucose and lipid metabolism. The aim of this study was to investigate the regulatory role of NR4A1 in adipogenesis and explore the underlying mechanisms. Quantitative real-time PCR and Western blotting were used to analyse the expression of genes involved in synthesis and mobilization of fats in vivo and in vitro. Dual-luciferase reporter assay was conducted to study the regulatory mechanisms of NR4A1. Our data from in vivo study confirmed that NR4A1 knockout (KO) mice fed with high-fat diet were more prone to obesity, and gene expression levels of PPARγ and FAS were increased in KO mice compared to controls; our data from in vitro study showed that NR4A1 overexpression in 3T3-L1 pre-adipocytes inhibited adipogenesis. Moreover, NR4A1 enhanced GATA binding protein 2 (GATA2) expression, which in turn inhibited peroxisome proliferator-activated receptor γ (PPARγ); NR4A1 inhibited sterol regulatory element binding transcription factor 1 (SREBP1) and its downstream gene fatty acid synthase (FAS) by up-regulating p53. NR4A1 inhibits the differentiation and lipid accumulation of adipocytes by enhancing the expression of GATA2 and p53.
Subject(s)
Adipocytes/metabolism , Adipogenesis/genetics , GATA2 Transcription Factor/genetics , Nuclear Receptor Subfamily 4, Group A, Member 1/genetics , Obesity/genetics , Tumor Suppressor Protein p53/genetics , 3T3-L1 Cells , Adipocytes/cytology , Animals , Base Sequence , Cell Differentiation/genetics , Diet, High-Fat/adverse effects , Fatty Acid Synthase, Type I/genetics , Fatty Acid Synthase, Type I/metabolism , GATA2 Transcription Factor/metabolism , Gene Expression Regulation , Genes, Reporter , Lipid Metabolism/genetics , Luciferases/genetics , Luciferases/metabolism , Mice , Mice, Inbred C57BL , Mice, Knockout , Nuclear Receptor Subfamily 4, Group A, Member 1/deficiency , Obesity/etiology , Obesity/metabolism , Obesity/pathology , PPAR gamma/genetics , PPAR gamma/metabolism , Promoter Regions, Genetic , Protein Binding , Signal Transduction , Sterol Regulatory Element Binding Protein 1/genetics , Sterol Regulatory Element Binding Protein 1/metabolism , Tumor Suppressor Protein p53/metabolismABSTRACT
OBJECTIVE: To investigate the advantages of nitric acid digestion method and its differences with the traditional method. METHODS: Ethanol was used to fully fix the testing sample. About 80-100 g of the testing samples were cut into pieces and digested with nitric acid. It was then centrifuged and washed to remove organic components. Smears were prepared and examined under the light microscope. RESULTS: The diatom had been identified with clear striations, counted conveniently and classified easily. CONCLUSION: The improved nitric acid digestion method is not only simple with a higher successful rate of detection, but also can prevent interference from contamination. It can improve the stability of the experimental results, avoid harm to human and environment, and provide higher safety in the course of experiment.