title: Activation of cardiac and smooth muscle-specific genes in primary human cells after forced expression of human myocardin.
abstract: OBJECTIVE
  Myocardin is a recently discovered transcriptional regulator of cardiac and smooth muscle development. Its ability to transactivate smooth muscle-specific genes has been firmly established in animal cells but its effect on heart muscle genes has been investigated less extensively and the consequences of ectopic myocardin expression in human cells are unknown.
  
  
  METHODS
  In this study, primary human mesenchymal stem cells and foreskin fibroblasts were transduced with human adenovirus vectors expressing the longest splice variant of the human myocardin gene (hAd5/F50.CMV.myocL) or with control vectors. One week later, the expression of muscle-restricted genes in these cells was analyzed by reverse transcription-polymerase chain reactions and immunofluorescence microscopy.
  
  
  RESULTS
  Forced expression of myocardin induced transcription of cardiac and smooth muscle genes in both cell types but did not lead to activation of skeletal muscle-specific genes. Double labeling experiments using monoclonal antibodies directed against striated (i.e. sarcomeric alpha-actin and sarcomeric alpha-actinin) and cardiac (i.e. natriuretic peptide precursor A) muscle-specific proteins together with a polyclonal antiserum specific for smooth muscle myosin heavy chain revealed that hAd5/F50.CMV.myocL-transduced cells co-express heart and smooth muscle-specific genes.
  
  
  CONCLUSIONS
  These data indicate that the myocardin protein is a strong inducer of both smooth and cardiac muscle genes, but that additional factors are necessary to fully commit cells to either cardiac or smooth muscle cell fates.
authors.affiliation: Department of Cardiology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
authors.forename: John
authors.initials: J
authors.lastname: van Tuyn
authors.forename: Shoshan
authors.initials: S
authors.lastname: Knaän-Shanzer
authors.forename: Marloes J M
authors.initials: MJ
authors.lastname: van de Watering
authors.forename: Michelle
authors.initials: M
authors.lastname: de Graaf
authors.forename: Arnoud
authors.initials: A
authors.lastname: van der Laarse
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Schalij
authors.forename: Ernst E
authors.initials: EE
authors.lastname: van der Wall
authors.forename: Antoine A F
authors.initials: AA
authors.lastname: de Vries
authors.forename: Douwe E
authors.initials: DE
authors.lastname: Atsma
mesh_terms: D000185:Actinin / Q000235:genetics; D000199:Actins / Q000235:genetics; D000256:Adenoviridae / Q000235:genetics; D009320:Atrial Natriuretic Factor / Q000235:genetics; D002454:Cell Differentiation; D002470:Cell Survival; D005347:Fibroblasts; D015870:Gene Expression; D005822:Genetic Vectors / Q000008:administration & dosage; D006801:Humans; D007106:Immune Sera / Q000494:pharmacology; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism*; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000276:immunology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014161:Transduction, Genetic; D000099251:Myocardin
chemical_list: D000185:Actinin; D000199:Actins; D009320:Atrial Natriuretic Factor; D007106:Immune Sera; D018995:Myosin Heavy Chains; D009687:Nuclear Proteins; D015534:Trans-Activators; D000099251:Myocardin; C472955:NPPA protein, human