Bone morphogenetic protein-4-induced activation of Xretpos is mediated by Smads and Olf-1/EBF associated zinc finger (OAZ).
We have previously isolated Xretpos, a novel family of long terminal repeat (LTR)-retrotransposons in Xenopus laevis, whose transcript is restricted to ventro-posterior-specific regions and induced by bone morphogenetic protein-4 (BMP-4) signaling. To explore the molecular mechanism of the transcriptional regulation, we identified and characterized Xretpos promoter regions consisting of LTRs and a 5'-untranslated region. We demonstrated that this promoter region contains all the necessary regulatory elements for the spatial and temporal expression of XRETPOS: Sequence analysis of the Xretpos promoter revealed multiple Smad-binding elements and Olf-1/EBF-associated zinc finger (OAZ) binding sites similar to BMP-4 response element, which were identified and proved to be required for BMP-4 induction in the Xvent2 promoter. We further demonstrated that Smads and OAZ proteins bind to their response elements in the promoter and these bindings are essential for the BMP-4-induced activation of the Xretpos promoter. Furthermore, we showed that the endogenous expression of Xretpos protein indeed occurred and was temporally regulated and BMP-4-inducible during the early Xenopus development. Finally, overexpression and partial loss-of-function study revealed that Xretpos has a posterio-ventralizing activity. Together, our results place Xretpos downstream of BMP-4 and provide evidence for the conserved mechanism of transcriptional regulation of the BMP-4 target genes.
Laboratory of Developmental Biology, Department of Life Science and Division of Molecular and Life Sciences, Pohang University of Science and Technology, San 31 Hyoja-Dong, Pohang, Kyungbuk, 790-784, South Korea.
Sangwoo
S
Shim
Narina
N
Bae
Jin-Kwan
JK
Han
D024506:5' Flanking Region / Q000235:genetics; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D001665:Binding Sites / Q000235:genetics; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000378:metabolism; D015870:Gene Expression; D017930:Genes, Reporter / Q000235:genetics; D008845:Microinjections; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D011506:Proteins; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D018626:Retroelements / Q000235:genetics*; D051785:Smad Proteins; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D029867:Xenopus Proteins; D014982:Xenopus laevis
D051792:Basic Helix-Loop-Helix Proteins; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; D011506:Proteins; D011993:Recombinant Fusion Proteins; D018626:Retroelements; D051785:Smad Proteins; D015534:Trans-Activators; D029867:Xenopus Proteins; C525812:bmp4 protein, Xenopus; C489924:ebf2 protein, Xenopus; C031017:ornithine decarboxylase antizyme