BMP-4 regulates the dorsal-ventral differences in FGF/MAPKK-mediated mesoderm induction in Xenopus.
Recent studies on Xenopus development have revealed an increasingly complex array of inductive, prepatterning, and competence signals that are necessary for proper mesoderm formation. In this study, we establish that fibroblast growth factor (FGF) signals through mitogen-activated protein kinase kinase (MAPKK) to induce mesodermal gene expression. We demonstrate that a partially activated form of MAPKK restores expression of the mesodermal genes Xcad-3 and Xbra, eliminated by the dominant-negative FGF receptor (delta FGFR). Similar to the results reported earlier with delta FGFR, expression of a dominant-negative form of MAPKK (MAPKKD) preferentially eliminates the dorsal expression of Xcad-3 and Xbra. We tested whether the regional localization of bone morphogenetic protein-4 (BMP-4) could explain why both MAPKKD and delta FGFR eliminate the dorsal and not the ventral expression of Xcad-3 and Xbra. We show that ectopic expression of BMP-4 is sufficient to maintain the dorsal expression of Xcad-3 and Xbra in embryos containing delta FGFR and that expression of a dominant-negative BMP receptor reduces the dorsal-ventral differences in delta FGFR embryos. These results indicate that regional localization of BMP-4 is responsible for the dorsal-ventral asymmetry in FGF/MAPKK-mediated mesoderm induction.
Northrop
J
J
Department of Biochemistry, School of Medicine, University of Washington, Seattle 98195-7350, USA.
Woods
A
A
Seger
R
R
Suzuki
A
A
Ueno
N
N
Krebs
E
E
Kimelman
D
D
D000818:Animals; D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins / Q000096:biosynthesis; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000502:physiology*; D005260:Female; D005326:Fetal Proteins / Q000096:biosynthesis*; D015870:Gene Expression; D006133:Growth Substances / Q000096:biosynthesis; D017403:In Situ Hybridization; D008297:Male; D008648:Mesoderm / Q000166:cytology / Q000502:physiology*; D020929:Mitogen-Activated Protein Kinase Kinases; D016296:Mutagenesis; D014176:Protein Biosynthesis; D011494:Protein Kinases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D011506:Proteins / Q000502:physiology; D017468:Receptors, Fibroblast Growth Factor / Q000096:biosynthesis* / Q000502:physiology; D015398:Signal Transduction; D020825:T-Box Domain Proteins; D014158:Transcription, Genetic; D014981:Xenopus / Q000196:embryology*; D029867:Xenopus Proteins; D000098908:Brachyury Protein
D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; D005326:Fetal Proteins; D006133:Growth Substances; D020929:Mitogen-Activated Protein Kinase Kinases; D011494:Protein Kinases; D011506:Proteins; D017468:Receptors, Fibroblast Growth Factor; D020825:T-Box Domain Proteins; D029867:Xenopus Proteins; D000098908:Brachyury Protein; C096851:Cdx4 protein, Xenopus