title: Mef2c is an essential regulatory element required for unique expression of the cardiac-specific CARK gene.
abstract: The cardiac ankyrin repeat kinase (CARK) gene, also named TNNI3K for its interaction with cardiac troponin I, is both a unique expression and heart-enriched gene. To understand the mechanisms of CARK gene expression and regulation, we first cloned the full-length mRNA sequence and mapped the transcription start site of the mouse CARK gene and characterized its promoter regions. Two transcriptional isoforms of the CARK gene were identified in mouse heart tissue. Truncation analysis of the CARK promoter identified a minimal 151 bp region that has strong basal transcription activity. Mutational analysis revealed five conserved cis-acting elements in this 151-bp long minimal promoter. Mutational and loss-of-functional analysis and co-transfection studies indicated that MEF2 binding region is the most critical cis-acting element in the CARK promoter, and CARK transcription level can be down-regulated by MEF2C antisense. Binding to the MEF2 sites by Mef2c protein was confirmed by electrophoretic mobility shift assay and competition and supershift electrophoretic mobility shift assays.
authors.affiliation: Sino-German Laboratory for Molecular Medicine, Ministry of Education, FuWai Cardiovascular Hospital and Cardiovascular Institute, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
authors.forename: Hu
authors.initials: H
authors.lastname: Wang
authors.forename: Chen
authors.initials: C
authors.lastname: Chen
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Song
authors.forename: Jingzhou
authors.initials: J
authors.lastname: Chen
authors.forename: Yisong
authors.initials: Y
authors.lastname: Zhen
authors.forename: Kai
authors.initials: K
authors.lastname: Sun
authors.forename: Rutai
authors.initials: R
authors.lastname: Hui
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001011:Aorta / Q000502:physiology; D001483:Base Sequence; D015153:Blotting, Western; D024202:Electrophoretic Mobility Shift Assay; D006321:Heart / Q000502:physiology*; D064326:MEF2 Transcription Factors; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D009124:Muscle Proteins; D009154:Mutation / Q000235:genetics; D032389:Myocytes, Smooth Muscle / Q000378:metabolism; D018006:Myogenic Regulatory Factors / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D020320:Oligoribonucleotides, Antisense / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid; D024363:Transcription Initiation Site; D014158:Transcription, Genetic
chemical_list: C104844:Ankrd1 protein, mouse; D064326:MEF2 Transcription Factors; C578041:Mef2c protein, mouse; D009124:Muscle Proteins; D018006:Myogenic Regulatory Factors; D009687:Nuclear Proteins; D020320:Oligoribonucleotides, Antisense; D012333:RNA, Messenger; D012097:Repressor Proteins