title: Role of BMP-4 in the inducing ability of the head organizer in Xenopus laevis.
abstract: BMP-4 has been implicated in the patterning of the Dorsal-Ventral axis of mesoderm and ectoderm. In this study, we describe the posteriorizing effect of BMP-4 on the neural inducing ability of dorsal mesoderm (dorsal lip region) in Xenopus gastrulae. Dorsal lip explants dissected from stage 10.25 embryos retained anterior inducing ability when precultured for 6 hrs until sibling embryos reach stage 12. When the dorsal lips from stage 10.25 embryos were treated with a range of BMP-4 concentrations, posterior tissues were induced in adjacent ectoderm in a dose-dependent manner. Thus activin-treated explants able to act as head inducers can also induce posterior structures in the presence of BMP-4. To investigate whether BMP-4 directly affects the inducing ability of dorsal mesoderm, we blocked the BMP-4 signaling pathway by injection of mRNA encoding a truncated form of the BMP-4 receptor (tBR) mRNA. Under these conditions, activin-treated explants induced anterior tissues following BMP-4 treatment. Taken together, these results indicate that BMP-4 may affect the head inducing ability of dorsal mesoderm and confer trunk-tail inducing ability during Xenopus gastrulation.
authors.affiliation: Department of Life Sciences (Biology), Graduate School of Art and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Sedohara
authors.forename: Akimasa
authors.initials: A
authors.lastname: Fukui
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Michiue
authors.forename: Makoto
authors.initials: M
authors.lastname: Asashima
mesh_terms: D028341:Activins / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology / Q000502:physiology*; D019070:Cell Lineage / Q000187:drug effects; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004475:Ectoderm / Q000166:cytology / Q000187:drug effects; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000187:drug effects / Q000196:embryology*; D004627:Embryonic Induction / Q000187:drug effects; D005260:Female; D005775:Gastrula / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D008297:Male; D008648:Mesoderm / Q000166:cytology / Q000187:drug effects; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000196:embryology*
chemical_list: D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D006063:Chorionic Gonadotropin; D029867:Xenopus Proteins; C525812:bmp4 protein, Xenopus; D028341:Activins