title: Hedgehog signaling induces cardiomyogenesis in P19 cells.
abstract: Sonic Hedgehog (Shh) is a critical signaling factor for a variety of developmental pathways during embryogenesis, including the specification of left-right asymmetry in the heart. Mice that lack Hedgehog signaling show a delay in the induction of cardiomyogenesis, as indicated by a delayed expression of Nkx2-5. To further examine a role for Shh in cardiomyogenesis, clonal populations of P19 cells that stably express Shh, termed P19(Shh) cells, were isolated. In monolayer P19(Shh) cultures the Shh pathway was functional as shown by the up-regulation of Ptc1 and Gli1 expression, but no cardiac muscle markers were activated. However, Shh expression induced cardiomyogenesis following cellular aggregation, resulting in the expression of factors expressed in cardiac muscle including GATA-4, MEF2C, and Nkx2-5. Furthermore, aggregated P19 cell lines expressing Gli2 or Meox1 also up-regulated the expression of cardiac muscle factors, leading to cardiomyogenesis. Meox1 up-regulated the expression of Gli1 and Gli2 and, thus, can modify the Shh signaling pathway. Finally, Shh, Gli2, and Meox1 all up-regulated BMP-4 expression, implying that activation of the Hedgehog pathway can regulate bone morphogenetic protein signals. Taken together, we propose a model in which Shh, functioning via Gli1/2, can specify mesodermal cells into the cardiac muscle lineage.
authors.affiliation: Department of Biochemistry, Medical Sciences Building, University of Western Ontario, London, Ontario N6A 5C1, Canada.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Gianakopoulos
authors.forename: Ilona S
authors.initials: IS
authors.lastname: Skerjanc
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D015152:Blotting, Northern; D002454:Cell Differentiation; D002460:Cell Line; D019070:Cell Lineage; D017931:DNA Primers / Q000737:chemistry; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D050991:GATA4 Transcription Factor; D053823:Hedgehog Proteins; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins / Q000378:metabolism; D051741:Kruppel-Like Transcription Factors; D064326:MEF2 Transcription Factors; D008648:Mesoderm / Q000378:metabolism; D051379:Mice; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009206:Myocardium / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism; D018006:Myogenic Regulatory Factors / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D016133:Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism; D015854:Up-Regulation; D000071676:Zinc Finger Protein GLI1; D000075746:Zinc Finger Protein Gli2
chemical_list: D000199:Actins; D017931:DNA Primers; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D050991:GATA4 Transcription Factor; C498520:Gli1 protein, mouse; C000618551:Gli2 protein, mouse; D053823:Hedgehog Proteins; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins; D051741:Kruppel-Like Transcription Factors; D064326:MEF2 Transcription Factors; C578041:Mef2c protein, mouse; C484871:Meox1 protein, mouse; D018006:Myogenic Regulatory Factors; C484469:Nkx2-5 protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; D000071676:Zinc Finger Protein GLI1; D000075746:Zinc Finger Protein Gli2