title: Threshold-dependent BMP-mediated repression: a model for a conserved mechanism that patterns the neuroectoderm.
abstract: Subdivision of the neuroectoderm into three rows of cells along the dorsal-ventral axis by neural identity genes is a highly conserved developmental process. While neural identity genes are expressed in remarkably similar patterns in vertebrates and invertebrates, previous work suggests that these patterns may be regulated by distinct upstream genetic pathways. Here we ask whether a potential conserved source of positional information provided by the BMP signaling contributes to patterning the neuroectoderm. We have addressed this question in two ways: First, we asked whether BMPs can act as bona fide morphogens to pattern the Drosophila neuroectoderm in a dose-dependent fashion, and second, we examined whether BMPs might act in a similar fashion in patterning the vertebrate neuroectoderm. In this study, we show that graded BMP signaling participates in organizing the neural axis in Drosophila by repressing expression of neural identity genes in a threshold-dependent fashion. We also provide evidence for a similar organizing activity of BMP signaling in chick neural plate explants, which may operate by the same double negative mechanism that acts earlier during neural induction. We propose that BMPs played an ancestral role in patterning the metazoan neuroectoderm by threshold-dependent repression of neural identity genes.
authors.affiliation: Section of Cell and Developmental Biology, University of California San Diego, La Jolla, California, USA.
authors.forename: Claudia Mieko
authors.initials: CM
authors.lastname: Mizutani
authors.forename: Néva
authors.initials: N
authors.lastname: Meyer
authors.forename: Henk
authors.initials: H
authors.lastname: Roelink
authors.forename: Ethan
authors.initials: E
authors.lastname: Bier
mesh_terms: D000818:Animals; D019521:Body Patterning; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D002642:Chick Embryo; D003433:Crosses, Genetic; D029721:Drosophila Proteins / Q000378:metabolism; D004331:Drosophila melanogaster; D004475:Ectoderm / Q000378:metabolism*; D019143:Evolution, Molecular; D018507:Gene Expression Regulation, Developmental; D008954:Models, Biological; D009474:Neurons / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D019485:Bone Morphogenetic Proteins; D029721:Drosophila Proteins; D014157:Transcription Factors