title: JAK2/STAT3 directs cardiomyogenesis within murine embryonic stem cells in vitro.
abstract: The heart is the first organ to form during development; however, little is known about the mechanisms that control the initial stages of cardiac differentiation. To investigate this process, we used a protein kinase expression screen, in which nonbeating embryonic stem (ES) cells were compared with beating ES cell-derived cardiomyocytes. We found that JAK2 experienced a 70% increase in protein levels within beating areas. Inhibition of JAK2 pharmacologically or by using dominant/negative JAK2 both resulted in diminished beating within embryoid bodies (EBs), whereas gain of function analysis using dominant/positive JAK2 resulted in a significant induction of beating. More important, inhibition of STAT3, a specific target of JAK2, by dominant/negative STAT3 resulted in the virtual complete loss of beating areas. Reverse transcription-polymerase chain reaction and Western analysis of STAT3-inhibited EBs resulted in lack of expression of several cardiac-specific genes, many of which contain within their promoter STAT3 DNA-binding regions. Taken together, the data reveal that the JAK2/STAT3 pathway is essential for initial stages of cardiomyogenesis.
authors.affiliation: Georgetown University Medical Institute, Department of Cell Biology, 3900 Reservoir Road NW, Room NE203, Washington, DC 20007, USA.
authors.forename: Kara
authors.initials: K
authors.lastname: Foshay
authors.forename: Gisella
authors.initials: G
authors.lastname: Rodriguez
authors.forename: Bonnie
authors.initials: B
authors.lastname: Hoel
authors.forename: Jonathon
authors.initials: J
authors.lastname: Narayan
authors.forename: G Ian
authors.initials: GI
authors.lastname: Gallicano
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D004622:Embryo, Mammalian / Q000166:cytology*; D018507:Gene Expression Regulation, Developmental; D006321:Heart / Q000502:physiology; D053614:Janus Kinase 2; D051379:Mice; D024510:Muscle Development; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000378:metabolism / Q000502:physiology; D011401:Promoter Regions, Genetic; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism / Q000502:physiology
chemical_list: D011518:Proto-Oncogene Proteins; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; D011505:Protein-Tyrosine Kinases; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2