The Xenopus POU class V transcription factor XOct-25 inhibits ectodermal competence to respond to bone morphogenetic protein-mediated embryonic induction.
Bone morphogenetic proteins (BMPs) have been shown to play a key role in controlling ectodermal cell fates by inducing epidermis at the expense of neural tissue during gastrulation. Here, we present evidence that the Xenopus POU class V transcription factor XOct-25 regulates ectodermal cell fate decisions by inhibiting the competence of ectodermal cells to respond to BMP during Xenopus embryogenesis. When overexpressed in the ectoderm after the blastula stage, XOct-25 suppressed early BMP responses of ectodermal cells downstream of BMP receptor activation and promoted neural induction while suppressing epidermal differentiation. In contrast, inhibition of XOct-25 function in the prospective neuroectoderm resulted in expansion of epidermal ectoderm at the expense of neuroectoderm. The reduction of neural tissue by inhibition of XOct-25 function could be rescued by decreasing endogenous BMP signaling, suggesting that XOct-25 plays a role in the formation of neural tissue at least in part by inhibiting BMP-mediated epidermal induction (neural inhibition). This hypothesis is supported by the observation that ectodermal cells from XOct-25 morphants were more sensitive to BMP signaling than cells from controls in inducing both immediate early BMP target genes and epidermis at the expense of neural tissue, while cells overexpressing XOct-25 are less competent to respond to BMP-mediated induction. These results document an essential role for XOct-25 in commitment to neural or epidermal cell fates in the ectoderm and highlight the importance of a regulatory mechanism that limits competence to respond to BMP-mediated embryonic induction.
Takebayashi-Suzuki
Kimiko
K
Institute for Amphibian Biology, Hiroshima University Graduate School of Science, Kagamiyama 1-3-1, Higashi-Hiroshima 739-8526, Japan.
Arita
Naoko
N
Murasaki
Eri
E
Suzuki
Atsushi
A
D000818:Animals; D052004:Bone Morphogenetic Protein Receptors / Q000378:metabolism; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects; D019070:Cell Lineage / Q000187:drug effects; D004475:Ectoderm / Q000166:cytology / Q000187:drug effects* / Q000196:embryology*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000187:drug effects; D004627:Embryonic Induction / Q000187:drug effects*; D000078404:Epidermal Cells; D004817:Epidermis / Q000187:drug effects; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D008969:Molecular Sequence Data; D009474:Neurons / Q000166:cytology / Q000187:drug effects; D050809:POU Domain Factors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D015534:Trans-Activators / Q000378:metabolism; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics
D019485:Bone Morphogenetic Proteins; D050809:POU Domain Factors; D015534:Trans-Activators; D029867:Xenopus Proteins; C527329:pou5f3.2 protein, Xenopus; D052004:Bone Morphogenetic Protein Receptors