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Dev Biol May 15, 2003; 257 (2): 278-91.

Xenopus X-box binding protein 1, a leucine zipper transcription factor, is involved in the BMP signaling pathway.

We describe a novel basic leucine zipper transcription factor, XXBP-1, which interacts with BMP-4 in a positive feedback loop. It is a maternal factor and is zygotically expressed in the dorsal blastopore lip and ventral ectoderm with the exception of the prospective neural plate during gastrulation. Overexpression of XXBP-1 leads to ventralization of early embryos as described for BMP-4, and inhibits neuralization of dissociated ectoderm. Consistent with mediating BMP signaling, we show that the ectopic expression of XXBP-1 recovers the expression of epidermal keratin and reverses the dorsalization imposed by truncated BMP receptor type I, indicating that it may act downstream of the BMP receptor. Its effects can be partially mimicked by a fusion construct containing the VP16 activator domain and the XXBP-1 DNA-binding domain. In contrast, fusing the DNA-binding domain to the even-skipped repressor domain leads to upregulation of the neural markers NCAM and nrp-1 in animal cap assay. Taken together, the results suggest a role for XXBP-1 in the control of neural differentiation, possibly as an activator.

PubMed ID: 12729558
Article link: Dev Biol

Species referenced: Xenopus
Genes referenced: actl6a ag1 bmp4 chrd.1 dlx3 egr2 en2 gsc krt12.4 msx1 myc ncam1 nog nrp1 odc1 otx2 pax6 rax sox3 tbxt thibz ventx1.2 xbp1 zic3

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