ABSTRACT
Peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha) is a key regulator of cellular energy metabolism and regulates processes such as adaptive thermogenesis, hepatic gluconeogenesis, fatty acid oxidation, and mitochondrial biogenesis by coactivating numerous nuclear receptors and transcription factors. Here, we demonstrate the presence of the ERRalpha binding site in the regulatory sequence of the glucokinase gene and that PGC-1alpha coactivates ERRalpha to stimulate the transcription of glucokinase. Simultaneous overexpression of PGC-1alpha and ERRalpha potently induced the glucokinase gene expression and its enzymatic activity in primary hepatocytes; however, expression of either PGC-1alpha or ERRalpha alone had no significant effect. Electrophoretic mobility shift and chromatin immunoprecipitation assays revealed the interaction of ERRalpha with the glucokinase promoter. Finally, the knockdown of endogenous ERRalpha with specific siRNA (siERRalpha) or pharmacological inhibition of ERRalpha with XCT790 attenuated insulin-induced glucokinase expression. Taken together, this research identifies glucokinase as a novel target of PGC-1alpha/ERRalpha and underscores the regulatory function of ERRalpha in insulin-dependent enzyme regulation.
Subject(s)
Glucokinase/biosynthesis , Liver/metabolism , RNA-Binding Proteins/metabolism , Receptors, Estrogen/metabolism , Transcription Factors/metabolism , Animals , Blotting, Western , Chromatin Immunoprecipitation , Electrophoretic Mobility Shift Assay , Glucokinase/genetics , Glucose/metabolism , Hep G2 Cells , Hepatocytes/metabolism , Insulin/metabolism , Male , Mutagenesis, Site-Directed , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha , Promoter Regions, Genetic , RNA/chemistry , RNA/genetics , RNA Interference , RNA, Small Interfering/administration & dosage , RNA, Small Interfering/genetics , Rats , Receptors, Estrogen/antagonists & inhibitors , Reverse Transcriptase Polymerase Chain Reaction , Transcription, Genetic , ERRalpha Estrogen-Related ReceptorABSTRACT
As the most homologic homologue of silent information regulator 2 of yeast, Sirt1 gene is extensively expressed in mature tissues, and is rich in early embryo and reproductive cells. It is involved in the regulation of gene transcription, energy metabolism and cell aging. It promotes fat mobilization in adipocytes and glucose production in liver and regulates insulin secretion in islet beta cell. Furthermore, Sirt1 gene is an essential endogenous apoptosis inhibitor. In future, it may be used as new drug targets or applied in other disease management modalities.
Subject(s)
Sirtuin 1 , Animals , Humans , Sirtuin 1/genetics , Sirtuin 1/metabolism , Sirtuin 1/physiologyABSTRACT
The disorders of DNA and histone methylation have a close relationship with the development and progression of tumors. Epigenetic regulation is critical in maintaining the stability and integrity of the expression profiles of different cell types by modifying DNA methylation and histone methylation. However, the abnormal changes of methylation often result in the development and progression of tumors. This review summarized the theory of tumor genomic and histone methylation, detection methods of methylation and their applications, and the clinical application of methylation as biological markers and drug targets.
