title: Wnt11 and Wnt7a are up-regulated in association with differentiation of cardiac conduction cells in vitro and in vivo.
abstract: The heart beat is coordinated by a precisely timed sequence of action potentials propagated through cells of the conduction system. Previously, we have shown that conduction cells in the chick embryo are derived from multipotent, cardiomyogenic progenitors present in the looped, tubular heart. Moreover, analyses of heterogeneity within myocyte clones and cell birth dating have indicated that elaboration of the conduction system occurs by ongoing, localized recruitment from within this multipotent pool. In this study, we have focused on a potential role for Wnt signaling in development of the cardiac conduction system. Treatment of embryonic myocytes from chick with endothelin-1 (ET-1) has been shown to promote expression of markers of Purkinje fiber cells. By using this in vitro model, we find that Wnt11 are Wnt7a are up-regulated in association with ET-1 treatment. Moreover, in situ hybridization reveals expression, although not temporal coincidence of, Wnt11 and Wnt7a in specialized tissues in the developing heart in vivo. Specifically, whereas Wnt11 shows transient and prominent expression in central elements of the developing conduction system (e.g., the His bundle), relative increases in Wnt7a expression emerge at sites consistent with the location of peripheral conduction cells (e.g., subendocardial Purkinje fibers). The patterns of Wnt11 and Wnt7a expression observed in vitro and in the embryonic chick heart appear to be consistent with roles for these two Wnts in differentiation of cardiac conduction tissues.
authors.affiliation: Department of Cell Biology and Anatomy, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Bond
authors.forename: David
authors.initials: D
authors.lastname: Sedmera
authors.forename: Jane
authors.initials: J
authors.lastname: Jourdan
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Zhang
authors.forename: Carol A
authors.initials: CA
authors.lastname: Eisenberg
authors.forename: Leonard M
authors.initials: LM
authors.lastname: Eisenberg
authors.forename: Robert G
authors.initials: RG
authors.lastname: Gourdie
mesh_terms: D000818:Animals; D030161:Avian Proteins; D002454:Cell Differentiation; D002642:Chick Embryo; D019332:Endothelin-1 / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects*; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D006329:Heart Conduction System / Q000196:embryology*; D017403:In Situ Hybridization; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D015854:Up-Regulation / Q000187:drug effects; D051153:Wnt Proteins
chemical_list: D030161:Avian Proteins; D019332:Endothelin-1; D006023:Glycoproteins; D011518:Proto-Oncogene Proteins; C490509:WNT7A protein, Gallus gallus; D051153:Wnt Proteins