Smurf1 regulates neural patterning and folding in Xenopus embryos by antagonizing the BMP/Smad1 pathway.
The ubiquitin ligase Smurf1 can target a handful of signaling proteins for ubiquitin-mediated proteasomal destruction or functional modification, including TGF-beta receptors, Smads, transcription factors, RhoA and MEKK2. Smurf1 was initially implicated in BMP pathway regulation in embryonic development, but its potential role in vertebrate embryogenesis has yet to be clarified. Here we demonstrate that inhibition of Smurf1 in Xenopus laevis embryos with an antisense morpholino oligonucleotide or a dominant-negative protein disrupts early development, with the nervous system being the principal target. Smurf1 is enriched on the dorsal side of gastrula stage embryos, and blocking Smurf1 disturbs neural folding and neural, but not mesoderm differentiation, enhances BMP/Smad1 signaling, and elevates phospho-Smad1 levels in the dorsal ectoderm. We conclude that in Xenopus embryos, the BMP pathway is a major physiological target of Smurf1, and we propose that in normal development Smurf1 cooperates with secreted BMP antagonists to limit BMP signaling in dorsal ectoderm. Our data also reveal a novel role for Smurf1 and Smad1 in neural plate morphogenesis.
Alexandrova
Evguenia M
EM
Department of Biochemistry and Cell Biology, Graduate Program in Molecular and Cellular Biology, Center for Developmental Genetics, Stony Brook University, Stony Brook, NY 11794-5215, USA.
Thomsen
Gerald H
GH
D000818:Animals; D001483:Base Sequence; D019485:Bone Morphogenetic Proteins / Q000502:physiology*; D005775:Gastrula / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D009420:Nervous System / Q000196:embryology* / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction; D051898:Smad1 Protein / Q000502:physiology*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000502:physiology*; D014982:Xenopus laevis / Q000196:embryology* / Q000378:metabolism
D019485:Bone Morphogenetic Proteins; D051898:Smad1 Protein; C120925:SMURF1 protein, Xenopus; D044767:Ubiquitin-Protein Ligases