title: Distinct requirements for extra-embryonic and embryonic bone morphogenetic protein 4 in the formation of the node and primitive streak and coordination of left-right asymmetry in the mouse.
abstract: In the mouse and chick embryo, the node plays a central role in generating left-right (LR) positional information. Using several different strategies, we provide evidence in the mouse that bone morphogenetic protein 4 (Bmp4) is required independently in two different sites for node morphogenesis and for LR patterning. Bmp4 expression in the trophoblast-derived extra-embryonic ectoderm is essential for the normal formation of the node and primitive streak. However, tetraploid chimera analysis demonstrates that Bmp4 made in epiblast-derived tissues is required for robust LR patterning, even when normal node morphology is restored. In the absence of embryonic Bmp4, the expression of left-side determinants such as Nodal and Lefty2 is absent in the left lateral plate mesoderm (LPM). Noggin-mediated inhibition of Bmp activity in cultured wild-type embryos results in suppression of Nodal expression in the LPM. Thus, unlike previous models proposed in the chick embryo in which Bmp4 suppresses left-sided gene expression, our results suggest that Bmp acts as a positive facilitator of the left-sided molecular cascade and is required for Nodal induction and maintenance in the left LPM.
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000235:genetics*; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism*; D004475:Ectoderm / Q000378:metabolism; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006257:Head / Q000196:embryology; D006321:Heart / Q000196:embryology; D036341:Intercellular Signaling Peptides and Proteins; D055458:Left-Right Determination Factors; D008648:Mesoderm / Q000378:metabolism; D051379:Mice; D008817:Mice, Mutant Strains; D009154:Mutation; D055457:Nodal Protein; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism
chemical_list: C525810:Bmp4 protein, mouse; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; C119003:Dte protein, mouse; C496457:Fgf8 protein, mouse; D036341:Intercellular Signaling Peptides and Proteins; D055458:Left-Right Determination Factors; D055457:Nodal Protein; C526008:Nodal protein, mouse; D011506:Proteins; D016212:Transforming Growth Factor beta; C112971:fibroblast growth factor 14; D051524:Fibroblast Growth Factor 8; D005346:Fibroblast Growth Factors