title: The basic helix-loop-helix (bHLH) transcription factor DEC2 negatively regulates Twist1 through an E-box element.
abstract: Differentiated embryo chondrocyte 2 (DEC2/Sharp-1/Bhlhe41), a basic helix-loop-helix (bHLH) transcription factor, has been shown to regulate the transcription of target genes by binding to their E-box elements. We identified a possible DEC2-response element (consensus E-box: CACGTG) in the promoter region of Twist1. Forced expression of DEC2 significantly repressed Twist1 promoter activity under normoxia and under hypoxia as assessed by a luciferase reporter assay. In addition, over-expression of DEC2 repressed Twist1 mRNA expression assessed by quantitative real-time PCR. Site-directed mutagenesis studies showed that mutagenesis of the consensus E-box sequence eliminated the ability of DEC2 to reduce the Twist1 promoter activity. Chromatin immunoprecipitation (ChIP) assays confirmed that the DEC2-mediated repression is primarily achieved by binding to the E-box in the Twist1 promoter. Knockdown of DEC2 by siRNA significantly attenuated the repression of Twist1 expression. DEC2 and Twist1 exhibit inversed protein expression patterns during development of mouse tongue embryo tissue. Given the fact that DEC2 protein is emerging as an important regulator in a vast array of cellular events, including cell differentiation, maturation of lymphocytes and the molecular clock, our study elucidates an important mechanism by which DEC2 regulates cellular function by modulating the expression of Twist1.
authors.affiliation: Department of Anesthesiology, Nihon University School of Dentistry at Matsudo, Chiba 271-8587, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Suzuki
authors.affiliation: First Department of Pathology, Wakayama Medical University School of Medicine, Wakayama 641-0012, Japan.
authors.forename: Fuyuki
authors.initials: F
authors.lastname: Sato
authors.affiliation: Department of Biochemistry and Molecular Biology, Nihon University School of Dentistry at Matsudo, Chiba 271-8587, Japan. Electronic address: bhawal.ujjal.kumar@nihon-u.ac.jp.
authors.forename: Ujjal K
authors.initials: UK
authors.lastname: Bhawal
mesh_terms: D000818:Animals; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D014059:Tongue / Q000196:embryology; D014157:Transcription Factors / Q000378:metabolism; D051879:Twist-Related Protein 1 / Q000378:metabolism*
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D014157:Transcription Factors; D051879:Twist-Related Protein 1; C422085:BHLHE41 protein, human; C470968:Bhlhb3 protein, mouse; C103173:TWIST1 protein, human; C067250:Twist1 protein, mouse
keywords: DEC2; E-box; Growth and development; Hypoxia; Tongue; Twist1