title: Expression of the human cardiac actin gene in differentiating rat skeletal myoblasts.
abstract: The human cardiac-actin (CH-actin) gene was transfected into rat L6 skeletal myoblasts and stable transformants were isolated. The level of the CH-actin transcript varied between clones but changed little during the differentiation of myoblasts into multinucleate myotubes. Chimeric genes were constructed in which the CH-actin promoter, first non-coding exon (44 bp), and first intron (about 700 bp) were linked to the Herpes simplex virus thymidine kinase (tk) coding region. Clones of L6 cells transformed with these chimeric genes contained variable levels of actin-tk mRNA which changed little during differentiation. Thus, the activity of the CH-actin promoter appeared not to be up-regulated upon differentiation of myoblasts into myotubes. In clones of cells expressing the actin-tk mRNA, the TK protein was not detected in myoblasts but appeared in differentiating multinucleate myotubes. We interpret these results as suggesting developmentally regulated translation of the actin-tk mRNA. Since the first 44 nucleotides of the actin-tk mRNA were derived from the 5'-untranslated region of the CH-actin mRNA. These experiments suggest that translation of the actin-tk mRNA may be controlled by this region.
authors.affiliation: Department of Medicine, University of Ottawa, Canada.
authors.forename: M M
authors.initials: MM
authors.lastname: Ruben
authors.forename: M A
authors.initials: MA
authors.lastname: Rudnicki
authors.forename: T S
authors.initials: TS
authors.lastname: Bladon
authors.forename: K
authors.initials: K
authors.lastname: Jardine
authors.forename: J
authors.initials: J
authors.lastname: Craig
authors.forename: M W
authors.initials: MW
authors.lastname: McBurney
mesh_terms: D000199:Actins / Q000235:genetics*; D000818:Animals; D015152:Blotting, Northern; D002454:Cell Differentiation; D002460:Cell Line; D004262:DNA Restriction Enzymes; D005786:Gene Expression Regulation; D005796:Genes; D005814:Genes, Viral; D006801:Humans; D009132:Muscles / Q000166:cytology / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D018139:Simplexvirus / Q000235:genetics; D013937:Thymidine Kinase / Q000235:genetics; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D000199:Actins; D012333:RNA, Messenger; D013937:Thymidine Kinase; D004262:DNA Restriction Enzymes