title: N-cadherin is essential for retinoic acid-mediated cardiomyogenic differentiation in mouse embryonic stem cells.
abstract: Contraction forces developed by cardiomyocytes are transmitted across the plasma membrane through end-to-end connections between the myocytes, called intercalated disks, which enable the coordinated contraction of heart muscle. A component of the intercalated disk, the adherens junction, consists of the cell adhesion molecule, N-cadherin. Embryos lacking N-cadherin die at mid-gestation from cardiovascular abnormalities. We have evaluated the role of N-cadherin in cardiomyogenesis using N-cadherin-null mouse embryonic stem (ES) cells grown as embryoid bodies (EBs) in vitro. Myofibrillogenesis, the spatial orientation of myofibers, and intercellular contacts including desmosomes were normal in N-cadherin-null ES cell-derived cardiomyocytes. The effect of retinoic acid (RA), a stage and dose-dependent cardiogenic factor, was assessed in differentiating ES cells. all-trans (at) RA increased the number of ES cell-derived cardiomyocytes by approximately 3-fold (at 3 x 10(-9) M) in wt EBs. However, this effect was lost in N-cadherin-null EBs. In the presence of supplemented at-RA, the emergence of spontaneously beating cardiomyocytes appeared to be delayed and slightly less efficient in N-cadherin-null compared with wt and heterozygous EBs (frequencies of EBs with beating activity at 5 days: 54+/-18% vs. 96+/-0.5%, and 93+/-7%, respectively; peak frequencies of EBs with beating activity: 83+/-8% vs. 96+/-0.5% and 100%, respectively). In conclusion, cardiomyoyctes differentiating from N-cadherin-null ES cells in vitro show normal myofibrillogenesis and intercellular contacts, but impaired responses to early cardiogenic effects mediated by at-RA. These results suggest that N-cadherin may be essential for RA-induced cardiomyogenesis in mouse ES cells in vitro.
authors.affiliation: Department of Cardiology, University of Lausanne Medical School, Lausanne, Switzerland.
authors.forename: R
authors.initials: R
authors.lastname: Bugorsky
authors.forename: J-C
authors.initials: JC
authors.lastname: Perriard
authors.forename: G
authors.initials: G
authors.lastname: Vassalli
mesh_terms: D000818:Animals; D015820:Cadherins / Q000235:genetics / Q000502:physiology*; D002454:Cell Differentiation; D002478:Cells, Cultured; D053595:Embryonic Stem Cells / Q000378:metabolism / Q000502:physiology*; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000502:physiology; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000502:physiology*; D009210:Myofibrils / Q000502:physiology; D014212:Tretinoin / Q000494:pharmacology / Q000502:physiology*
chemical_list: D015820:Cadherins; D014212:Tretinoin