title: Epicardial retinoid X receptor alpha is required for myocardial growth and coronary artery formation.
abstract: Vitamin A signals play critical roles during embryonic development. In particular, heart morphogenesis depends on vitamin A signals mediated by the retinoid X receptor alpha (RXRalpha), as the systemic mutation of this receptor results in thinning of the myocardium and embryonic lethality. However, the molecular and cellular mechanisms controlled by RXRalpha signaling in this process are unclear, because a myocardium-restricted RXRalpha mutation does not perturb heart morphogenesis. Here, we analyze a series of tissue-restricted mutations of the RXRalpha gene in the cardiac neural crest, endothelial, and epicardial lineages, and we show that RXRalpha signaling in the epicardium is required for proper cardiac morphogenesis. Moreover, we detect an additional phenotype of defective coronary arteriogenesis associated with RXRalpha deficiency and identify a retinoid-dependent Wnt signaling pathway that cooperates in epicardial epithelial-to-mesenchymal transformation.
authors.affiliation: Institute of Molecular Medicine, University of California, San Diego, CA 92093, USA.
authors.forename: Esther
authors.initials: E
authors.lastname: Merki
authors.forename: Mónica
authors.initials: M
authors.lastname: Zamora
authors.forename: Angel
authors.initials: A
authors.lastname: Raya
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kawakami
authors.forename: Jianming
authors.initials: J
authors.lastname: Wang
authors.forename: Xiaoxue
authors.initials: X
authors.lastname: Zhang
authors.forename: John
authors.initials: J
authors.lastname: Burch
authors.forename: Steven W
authors.initials: SW
authors.lastname: Kubalak
authors.forename: Perla
authors.initials: P
authors.lastname: Kaliman
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Izpisua Belmonte
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Chien
authors.forename: Pilar
authors.initials: P
authors.lastname: Ruiz-Lozano
mesh_terms: D000818:Animals; D019070:Cell Lineage; D002642:Chick Embryo; D003331:Coronary Vessels / Q000166:cytology / Q000196:embryology* / Q000378:metabolism*; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D005346:Fibroblast Growth Factors / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006321:Heart / Q000196:embryology*; D051379:Mice; D008822:Mice, Transgenic; D009206:Myocardium / Q000166:cytology* / Q000378:metabolism*; D009432:Neural Crest / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D047490:Retinoid X Receptor alpha / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D051153:Wnt Proteins / Q000378:metabolism
chemical_list: D047490:Retinoid X Receptor alpha; D051153:Wnt Proteins; D005346:Fibroblast Growth Factors