Xbra3 elicits the production of neural tissue by a non-BMP-dependent mechanism in Xenopus sp.
Ectoderm cells in animal caps from Xenopus embryos develop to form either epidermis or neural tissue depending upon their receipt of intercellular signals. To date, several secreted neural inducers have been identified which act through the local inhibition of bone morphogenetic protein (BMP) signaling, preventing differentiation to epidermis and resulting in adoption of neural fate. In this work, we have exploited an interspecies animal cap assay, which enables detection of the effects of signaling molecules produced by cells of one animal cap and influencing development in a second cap cultured in close apposition in a Holtfreter combination. We show that expression of the T-box protein, Xbra3, in one cap causes the production of a factor, which causes adoption of neural fate by cells of the other animal cap. The action of this factor is not inhibited by the over-expression of BMP in cells of the responding animal cap, or by the inhibition of Wnt signaling. These findings suggest the existence of a secreted signaling molecule that is able to induce ectodermal cells to adopt neural fate by a mechanism independent of the inhibition of the BMP or Wnt signaling pathways.
D000818:Animals; D001483:Base Sequence; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D002454:Cell Differentiation; D019070:Cell Lineage; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D004475:Ectoderm / Q000378:metabolism; D004817:Epidermis / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006133:Growth Substances / Q000378:metabolism; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid; D015398:Signal Transduction; D013045:Species Specificity; D020825:T-Box Domain Proteins / Q000235:genetics* / Q000502:physiology; D013997:Time Factors; D051153:Wnt Proteins; D014981:Xenopus; D029867:Xenopus Proteins; D014982:Xenopus laevis; D029961:Zebrafish Proteins
D019485:Bone Morphogenetic Proteins; D018076:DNA, Complementary; D006133:Growth Substances; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D020825:T-Box Domain Proteins; D051153:Wnt Proteins; D029867:Xenopus Proteins; D029961:Zebrafish Proteins; C401504:bra3 protein, Xenopus