title: Transcriptional analysis of the titin cap gene.
abstract: Mutations in titin cap (Tcap), also known as telethonin, cause limb-girdle muscular dystrophy type 2G (LGMD2G). Tcap is one of the titin interacting Z-disc proteins involved in the regulation and development of normal sarcomeric structure. Given the essential role of Tcap in establishing and maintaining normal skeletal muscle architecture, we were interested in determining the regulatory elements required for expression of this gene in myoblasts. We have defined a highly conserved 421 bp promoter proximal promoter fragment that contains two E boxes and multiple putative Mef2 binding sequences. This promoter can be activated by MyoD and myogenin in NIH3T3 fibroblast cells, and maintains the differentiated cell-specific expression pattern of the endogenous Tcap in C2C12 cells. We find that while both E boxes are required for full activation by MyoD or myogenin in NIH3T3 cells, the promoter proximal E box has a greater contribution to activation of this promoter in C2C12 cells and to activation by MyoD in NIH3T3 cells. Together, the data suggest an important role for MyoD in activating Tcap expression through the promoter proximal E box. We also show that myogenin is required for normal expression in vivo and physically binds to the Tcap promoter during embryogenesis.
authors.affiliation: Department of Biochemistry and Molecular Biology, Southern Illinois University School of Medicine, 229 Neckers Building, 1245 Lincoln Drive, Carbondale, IL 62901-6899, USA.
authors.forename: Shuang
authors.initials: S
authors.lastname: Zhang
authors.forename: Priya
authors.initials: P
authors.lastname: Londhe
authors.forename: Meiling
authors.initials: M
authors.lastname: Zhang
authors.forename: Judith K
authors.initials: JK
authors.lastname: Davie
mesh_terms: D000818:Animals; D047369:Chromatin Immunoprecipitation; D003001:Cloning, Molecular; D064211:Connectin; D017931:DNA Primers / Q000235:genetics; D040461:Gene Components; D005786:Gene Expression Regulation / Q000235:genetics / Q000502:physiology*; D008156:Luciferases; D051379:Mice; D009124:Muscle Proteins / Q000235:genetics*; D018482:Muscle, Skeletal / Q000254:growth & development*; D016296:Mutagenesis; D017570:MyoD Protein / Q000235:genetics / Q000378:metabolism*; D032446:Myoblasts / Q000378:metabolism*; D041681:NIH 3T3 Cells; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
chemical_list: D064211:Connectin; D017931:DNA Primers; D009124:Muscle Proteins; D017570:MyoD Protein; C057363:MyoD1 myogenic differentiation protein; C577294:Tcap protein, mouse; D008156:Luciferases