title: Activin A induces craniofacial cartilage from undifferentiated Xenopus ectoderm in vitro.
abstract: Activin A has potent mesoderm-inducing activity in amphibian embryos and induces various mesodermal tissues in vitro from the isolated presumptive ectoderm. By using a sandwich culture method established to examine activin A activity, we previously demonstrated that activin-treated ectoderm can function as both a head and trunk-tail organizer, depending on the concentration of activin A. By using activin A and undifferentiated presumptive ectoderm, it is theoretically possible to reproduce embryonic induction. Here, we test this hypothesis by studying the induction of cartilage tissue by using the sandwich-culture method. In the sandwiched explants, the mesenchymal cell condensation expressed type II collagen and cartilage homeoprotein-1 mRNA, and subsequently, cartilage were induced as they are in vivo. goosecoid (gsc) mRNA was prominently expressed in the cartilage in the explants. Xenopus distal-less 4 (X-dll4) mRNA was expressed throughout the explants. In Xenopus embryos, gsc expression is restricted to the cartilage of the lower jaw, and X-dll4 is widely expressed in the ventral head region, including craniofacial cartilage. These finding suggest that the craniofacial cartilage, especially lower jaw cartilage, was induced in the activin-treated sandwiched explants. In addition, a normal developmental pattern was recapitulated at the histological and genetic level. This work also suggests that the craniofacial cartilage-induction pathway is downstream of activin A. This study presents a model system suitable for the in vitro analysis of craniofacial cartilage induction in vertebrates.
authors.affiliation: Department of Biochemistry and Molecular Biology, Kanagawa Dental College, Yokosuka 238-8580, Japan.
authors.forename: Miho
authors.initials: M
authors.lastname: Furue
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Myoishi
authors.forename: Yasuto
authors.initials: Y
authors.lastname: Fukui
authors.forename: Takashi
authors.initials: T
authors.lastname: Ariizumi
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Okamoto
authors.forename: Makoto
authors.initials: M
authors.lastname: Asashima
mesh_terms: D028341:Activins / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D036703:Blastula; D002356:Cartilage / Q000166:cytology / Q000187:drug effects* / Q000196:embryology; D002454:Cell Differentiation; D024043:Collagen Type II / Q000096:biosynthesis / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D004475:Ectoderm / Q000187:drug effects*; D004627:Embryonic Induction / Q000502:physiology*; D005145:Face / Q000196:embryology*; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D051956:Goosecoid Protein; D006257:Head / Q000196:embryology*; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics; D028322:Inhibin-beta Subunits / Q000494:pharmacology / Q000502:physiology*; D008297:Male; D008334:Mandible / Q000166:cytology / Q000196:embryology; D008648:Mesoderm / Q000166:cytology / Q000187:drug effects; D009024:Morphogenesis / Q000187:drug effects; D009924:Organ Culture Techniques; D012333:RNA, Messenger / Q000096:biosynthesis; D012097:Repressor Proteins; D014157:Transcription Factors; D029867:Xenopus Proteins / Q000096:biosynthesis / Q000235:genetics; D014982:Xenopus laevis / Q000196:embryology*
chemical_list: D024043:Collagen Type II; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D051956:Goosecoid Protein; D018398:Homeodomain Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; D014157:Transcription Factors; D029867:Xenopus Proteins; C422405:activin A; C470088:dll4 protein, Xenopus; D028341:Activins; D028322:Inhibin-beta Subunits