Bone morphogenetic protein function is required for terminal differentiation of the heart but not for early expression of cardiac marker genes.
To examine potential roles for bone morphogenetic proteins (BMPs) in cardiogenesis, we used intracellular BMP inhibitors to disrupt this signaling cascade in Xenopus embryos. BMP-deficient embryos showed endodermal defects, a reduction in cardiac muscle-specific gene expression, a decrease in the number of cardiomyocytes and cardia bifida. Early expression of markers of endodermal and precardiac fate, however, was not perturbed. Heart defects were observed even when BMP signal transduction was blocked only in cells that contribute primarily to endodermal, and not cardiac fates, suggesting a non-cell autonomous function. Our results suggest that BMPs are not required for expression of early transcriptional regulators of cardiac fate but are essential for migration and/or fusion of the heart primordia and cardiomyocyte differentiation.
Walters
M J
MJ
Department of Cell and Developmental Biology, Oregon Health Sciences University, School of Medicine, Portland 97201-3098, USA.
Wayman
G A
GA
Christian
J L
JL
D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000502:physiology*; D002454:Cell Differentiation; D019070:Cell Lineage; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism; D004064:Digestive System / Q000196:embryology; D015536:Down-Regulation; D004707:Endoderm / Q000378:metabolism; D050991:GATA4 Transcription Factor; D050992:GATA5 Transcription Factor; D050993:GATA6 Transcription Factor; D018507:Gene Expression Regulation, Developmental; D005819:Genetic Markers; D006321:Heart / Q000196:embryology*; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins / Q000096:biosynthesis; D017403:In Situ Hybridization; D009206:Myocardium / Q000166:cytology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D051905:Smad6 Protein; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors / Q000096:biosynthesis; D014158:Transcription, Genetic; D014981:Xenopus; D029867:Xenopus Proteins
D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; C494752:GATA-5a protein, Xenopus; C494753:GATA-5b protein, Xenopus; D050991:GATA4 Transcription Factor; C494751:GATA4 protein, Xenopus; D050992:GATA5 Transcription Factor; D050993:GATA6 Transcription Factor; C494758:GATA6 protein, Xenopus; D005819:Genetic Markers; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins; C092720:NKX2-5 protein, Xenopus; C095552:NKX2-5 protein, human; D051905:Smad6 Protein; C497805:Smad6 protein, Xenopus; D015534:Trans-Activators; D014157:Transcription Factors; D029867:Xenopus Proteins