A role for the homeobox gene Xvex-1 as part of the BMP-4 ventral signaling pathway.
BMP-4 is believed to play a central role in the patterning of the mesoderm by providing a strong ventral signal. As part of this ventral patterning signal, BMP-4 has to activate a number of transcription factors to fulfill this role. Among the transcription factors regulated by BMP-4 are the Xvent and the GATA genes. A novel homeobox gene has been isolated termed Xvex-1 which represents a new class of homeobox genes. Transcription of Xvex-1 initiates soon after the midblastula transition. Xvex-1 transcripts undergo spatial restriction from the onset of gastrulation to the ventral marginal zone, and the transcripts will remain in this localization including at the tailbud stage in the proctodeum. Expression of Xvex-1 during gastrula stages requires normal BMP-4 activity as evidenced from the injection of BMP-4, Smad1, Smad5 and Smad6 mRNA and antisense BMP-4 RNA. Xvex-1 overexpression ventralizes the Xenopus embryo in a dose dependent manner. Partial loss of Xvex-1 activity induced by antisense RNA injection results in the dorsalization of embryos and the induction of secondary axis formation. Xvex-1 can rescue the effects of overexpressing the dominant negative BMP receptor. These results place Xvex-1 downstream of BMP-4 during gastrulation and suggest that it represents a novel homeobox family in Xenopus which is part of the ventral signaling pathway.
Shapira
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E
Department of Cellular Biochemistry, Faculty of Medicine, Hebrew University, P.O. Box 12272, Jerusalem 91120, Israel.
Marom
K
K
Yelin
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R
Levy
A
A
Fainsod
A
A
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D055415:Bone Morphogenetic Protein 4; D052004:Bone Morphogenetic Protein Receptors; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000378:metabolism; D005775:Gastrula / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D051956:Goosecoid Protein; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism*; D008648:Mesoderm / Q000502:physiology; D008969:Molecular Sequence Data; D016372:RNA, Antisense; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D017978:Receptors, Growth Factor; D012097:Repressor Proteins; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D014157:Transcription Factors; D014981:Xenopus / Q000196:embryology*; D029867:Xenopus Proteins
D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D051956:Goosecoid Protein; D018398:Homeodomain Proteins; D016372:RNA, Antisense; D011956:Receptors, Cell Surface; D017978:Receptors, Growth Factor; D012097:Repressor Proteins; D014157:Transcription Factors; D029867:Xenopus Proteins; C525812:bmp4 protein, Xenopus; C112507:ventx1.2 protein, Xenopus; C099992:ventx2.1 protein, Xenopus; C121962:ventx3.2 protein, Xenopus; D052004:Bone Morphogenetic Protein Receptors