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Proc Natl Acad Sci U S A November 26, 2002; 99 (24): 15474-9.

Activin A induces craniofacial cartilage from undifferentiated Xenopus ectoderm in vitro.

Furue M , Myoishi Y , Fukui Y , Ariizumi T , Okamoto T , Asashima M .

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.

PubMed ID: 12424341
PMC ID: PMC137741
Article link: Proc Natl Acad Sci U S A

Species referenced: Xenopus laevis
Genes referenced: alx1 cartpt dll4 dlx2 gsc inhba tbx2

Article Images: [+] show captions
References [+] :
Ariizumi, Dose and time-dependent mesoderm induction and outgrowth formation by activin A in Xenopus laevis. 1992, Pubmed, Xenbase