title: Bmp signaling represses Vegfa to promote outflow tract cushion development.
abstract: Congenital heart disease (CHD) is a devastating anomaly that affects ∼1% of live births. Defects of the outflow tract (OFT) make up a large percentage of human CHD. We investigated Bmp signaling in mouse OFT development by conditionally deleting both Bmp4 and Bmp7 in the second heart field (SHF). SHF Bmp4/7 deficiency resulted in defective epithelial to mesenchymal transition (EMT) and reduced cardiac neural crest ingress, with resultant persistent truncus arteriosus. Using a candidate gene approach, we found that Vegfa was upregulated in the Bmp4/7 mutant hearts. To determine if Vegfa is a downstream Bmp effector during EMT, we examined whether Vegfa is transcriptionally regulated by the Bmp receptor-regulated Smad. Our findings indicate that Smad directly binds to Vegfa chromatin and represses Vegfa transcriptional activity. We also found that Vegfa is a direct target for the miR-17-92 cluster, which is also regulated by Bmp signaling in the SHF. Deletion of miR-17-92 reveals similar phenotypes to Bmp4/7 SHF deletion. To directly address the function of Vegfa repression in Bmp-mediated EMT, we performed ex vivo explant cultures from Bmp4/7 and miR-17-92 mutant hearts. EMT was defective in explants from the Bmp4/7 double conditional knockout (dCKO; Mef2c-Cre;Bmp4/7(f/f)) and miR-17-92 null. By antagonizing Vegfa activity in explants, EMT was rescued in Bmp4/7 dCKO and miR-17-92 null culture. Moreover, overexpression of miR-17-92 partially suppressed the EMT defect in Bmp4/7 mutant embryos. Our study reveals that Vegfa levels in the OFT are tightly controlled by Smad- and microRNA-dependent pathways to modulate OFT development.
authors.affiliation: Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: Bai
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Yuka
authors.initials: Y
authors.lastname: Morikawa
authors.forename: Margarita
authors.initials: M
authors.lastname: Bonilla-Claudio
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Klysik
authors.forename: James F
authors.initials: JF
authors.lastname: Martin
mesh_terms: D000818:Animals; D001483:Base Sequence; D055415:Bone Morphogenetic Protein 4 / Q000235:genetics / Q000378:metabolism*; D055419:Bone Morphogenetic Protein 7 / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D004622:Embryo, Mammalian / Q000378:metabolism; D058750:Epithelial-Mesenchymal Transition; D018507:Gene Expression Regulation, Developmental; D051379:Mice; D018345:Mice, Knockout; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D051898:Smad1 Protein / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D014339:Truncus Arteriosus, Persistent / Q000378:metabolism / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*; D014694:Ventricular Outflow Obstruction / Q000378:metabolism / Q000473:pathology*
chemical_list: C525810:Bmp4 protein, mouse; D055415:Bone Morphogenetic Protein 4; D055419:Bone Morphogenetic Protein 7; D035683:MicroRNAs; C543614:Mirn17 microRNA, mouse; C532375:Mirn20 microRNA, mouse; D012097:Repressor Proteins; D051898:Smad1 Protein; C497401:Smad1 protein, mouse; D042461:Vascular Endothelial Growth Factor A; C525820:bmp7 protein, mouse; C467480:vascular endothelial growth factor A, mouse
keywords: Bone morphogenetic protein; Epithelial to mesenchymal transition; Mouse; Outflow tract; Vascular endothelial growth factor A; microRNA