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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.
Figure 1. Stage†and tissueâ€specific expression of reporter constructs containing the LTR and 5′â€UTR of Xretpos promoter. The LTR is divided into three regions, U3, R and U5. (A) Activities of luciferase reporter constructs were measured from the extracts of embryos injected with pGL2â€Xretpos (LTRâ€UTR) or pGL2â€enhancer into all four blastomeres of the fourâ€cell stage embryos. One representative experiment is shown for this figure. (B) Xretpos reporter gene expression (left) was compared with endogenous Xretpos RNA (center). pgscâ€GFP expression is shown as control (right). pXretposâ€GFP was injected equatorially into all four blastomeres of fourâ€cell stage embryos, and the expression of GFP transcripts was visualized by wholeâ€mount in situ hybridization. The dorsal blastopore lip is indicated by arrowheads.
Figure 9. Phenotypic effects of overexpression (A) and partial loss (B and C) of Xretpos function. (A) Overexpression of Xretpos RNA resulted in reduced anteriorhead structures. Fourâ€cell stage embryos were injected into two dorsal animal or marginal regions at the fourâ€cell stage embryos with 4 ng of Xretpos RNA and allowed to develop until stage 43. Control embryos injected with 4 ng of PPL RNA produced normal tadpoles. (B) Rescue of axial structures in UVâ€irradiated embryos by antisense Xretpos RNA. Partial twinned axis structures were seen in UVâ€irradiated embryos injected into two nonâ€adjacent blastomeres at the fourâ€cell stage with antisense Xretpos RNA (1 ng/blastomere), but not in uninjected UVâ€irradiated controls. (C) Phenotypic effects of antisense Xretpos RNA injection in wildâ€type embryos. Anteroâ€dorsalized structures were observed in embryos which were injected diagonally at the fourâ€cell stage with antisense Xretpos RNA (1 ng/blastomere). Uninjected control embryos developed normally. (D) Reduction of endogenous Xretpos protein by antisense Xretpos RNA injection. The position of Xretpos protein is indicated by an arrow and Ponceau staining was performed as a loading control.
Altschul,
Gapped BLAST and PSI-BLAST: a new generation of protein database search programs.
1997, Pubmed
Altschul,
Gapped BLAST and PSI-BLAST: a new generation of protein database search programs.
1997,
Pubmed Attisano,
Smads as transcriptional co-modulators.
2000,
Pubmed Ault,
A novel homeobox gene PV.1 mediates induction of ventral mesoderm in Xenopus embryos.
1996,
Pubmed
,
Xenbase Bengal,
Functional antagonism between c-Jun and MyoD proteins: a direct physical association.
1992,
Pubmed Berger,
Predicting coiled coils by use of pairwise residue correlations.
1995,
Pubmed Bock,
Endogenous retroviruses and the human germline.
2000,
Pubmed Caricasole,
Bone morphogenetic proteins and retinoic acid induce human endogenous retrovirus HERV-K expression in NT2D1 human embryonal carcinoma cells.
2000,
Pubmed Chalaux,
JunB is involved in the inhibition of myogenic differentiation by bone morphogenetic protein-2.
1998,
Pubmed Chen,
A transcriptional partner for MAD proteins in TGF-beta signalling.
1996,
Pubmed
,
Xenbase Chen,
Smad4 and FAST-1 in the assembly of activin-responsive factor.
1997,
Pubmed
,
Xenbase Dennler,
Direct binding of Smad3 and Smad4 to critical TGF beta-inducible elements in the promoter of human plasminogen activator inhibitor-type 1 gene.
1998,
Pubmed Domansky,
Solitary HERV-K LTRs possess bi-directional promoter activity and contain a negative regulatory element in the U5 region.
2000,
Pubmed Elrouby,
A novel hybrid open reading frame formed by multiple cellular gene transductions by a plant long terminal repeat retroelement.
2001,
Pubmed Feng,
Human L1 retrotransposon encodes a conserved endonuclease required for retrotransposition.
1996,
Pubmed Flink,
Alternatively processed isoforms of cellular nucleic acid-binding protein interact with a suppressor region of the human beta-myosin heavy chain gene.
1995,
Pubmed Fong,
cis-acting regulatory elements in the bovine immunodeficiency virus long terminal repeat.
1995,
Pubmed Frank,
An essential splicing factor, SLU7, mediates 3' splice site choice in yeast.
1992,
Pubmed Gao,
Characterization of a functional promoter for the Xenopus wnt-1 gene on vivo.
1994,
Pubmed
,
Xenbase Gawantka,
Antagonizing the Spemann organizer: role of the homeobox gene Xvent-1.
1995,
Pubmed
,
Xenbase Germain,
Homeodomain and winged-helix transcription factors recruit activated Smads to distinct promoter elements via a common Smad interaction motif.
2000,
Pubmed
,
Xenbase Greene,
A novel family of retrotransposon-like elements in Xenopus laevis with a transcript inducible by two growth factors.
1993,
Pubmed
,
Xenbase Gruidl,
Multiple potential germ-line helicases are components of the germ-line-specific P granules of Caenorhabditis elegans.
1996,
Pubmed Hata,
OAZ uses distinct DNA- and protein-binding zinc fingers in separate BMP-Smad and Olf signaling pathways.
2000,
Pubmed
,
Xenbase Henningfeld,
Smad1 and Smad4 are components of the bone morphogenetic protein-4 (BMP-4)-induced transcription complex of the Xvent-2B promoter.
2000,
Pubmed
,
Xenbase Hill,
TGF-beta signalling pathways in early Xenopus development.
2001,
Pubmed
,
Xenbase Hollnagel,
Id genes are direct targets of bone morphogenetic protein induction in embryonic stem cells.
1999,
Pubmed Johnson,
Interaction of Smad complexes with tripartite DNA-binding sites.
1999,
Pubmed Jonk,
Identification and functional characterization of a Smad binding element (SBE) in the JunB promoter that acts as a transforming growth factor-beta, activin, and bone morphogenetic protein-inducible enhancer.
1998,
Pubmed Kao,
The entire mesodermal mantle behaves as Spemann's organizer in dorsoanterior enhanced Xenopus laevis embryos.
1988,
Pubmed
,
Xenbase Kazazian,
Genetics. L1 retrotransposons shape the mammalian genome.
2000,
Pubmed Korchynskyi,
Identification and functional characterization of distinct critically important bone morphogenetic protein-specific response elements in the Id1 promoter.
2002,
Pubmed Labbé,
Smad2 and Smad3 positively and negatively regulate TGF beta-dependent transcription through the forkhead DNA-binding protein FAST2.
1998,
Pubmed
,
Xenbase Ladher,
Xom: a Xenopus homeobox gene that mediates the early effects of BMP-4.
1996,
Pubmed
,
Xenbase Landschulz,
The leucine zipper: a hypothetical structure common to a new class of DNA binding proteins.
1988,
Pubmed Laurent,
The Xenopus homeobox gene twin mediates Wnt induction of goosecoid in establishment of Spemann's organizer.
1997,
Pubmed
,
Xenbase Leibold,
Translation of LINE-1 DNA elements in vitro and in human cells.
1990,
Pubmed Li,
Characterization of the DNA-binding property of Smad5.
2001,
Pubmed López-Rovira,
Direct binding of Smad1 and Smad4 to two distinct motifs mediates bone morphogenetic protein-specific transcriptional activation of Id1 gene.
2002,
Pubmed Lupas,
Predicting coiled coils from protein sequences.
1991,
Pubmed Maeda,
Xmsx-1 modifies mesodermal tissue pattern along dorsoventral axis in Xenopus laevis embryo.
1997,
Pubmed
,
Xenbase Maeno,
The role of BMP-4 and GATA-2 in the induction and differentiation of hematopoietic mesoderm in Xenopus laevis.
1996,
Pubmed
,
Xenbase Massagué,
Transcriptional control by the TGF-beta/Smad signaling system.
2000,
Pubmed Massagué,
TGFbeta signaling in growth control, cancer, and heritable disorders.
2000,
Pubmed Michelotti,
Cellular nucleic acid binding protein regulates the CT element of the human c-myc protooncogene.
1995,
Pubmed Mosquera,
A mRNA localized to the vegetal cortex of Xenopus oocytes encodes a protein with a nanos-like zinc finger domain.
1993,
Pubmed
,
Xenbase Moss,
The cold shock domain protein LIN-28 controls developmental timing in C. elegans and is regulated by the lin-4 RNA.
1997,
Pubmed Nakashima,
BMP2-mediated alteration in the developmental pathway of fetal mouse brain cells from neurogenesis to astrocytogenesis.
2001,
Pubmed Norton,
Id helix-loop-helix proteins in cell growth and differentiation.
1998,
Pubmed Onichtchouk,
The Xvent-2 homeobox gene is part of the BMP-4 signalling pathway controlling [correction of controling] dorsoventral patterning of Xenopus mesoderm.
1996,
Pubmed
,
Xenbase Osada,
Activin/nodal responsiveness and asymmetric expression of a Xenopus nodal-related gene converge on a FAST-regulated module in intron 1.
2000,
Pubmed
,
Xenbase Papalopulu,
A Xenopus gene, Xbr-1, defines a novel class of homeobox genes and is expressed in the dorsal ciliary margin of the eye.
1996,
Pubmed
,
Xenbase Pellizzoni,
Cellular nucleic acid binding protein binds a conserved region of the 5' UTR of Xenopus laevis ribosomal protein mRNAs.
1997,
Pubmed
,
Xenbase Rastegar,
Transcriptional regulation of Xvent homeobox genes.
1999,
Pubmed
,
Xenbase Saka,
A screen for targets of the Xenopus T-box gene Xbra.
2000,
Pubmed
,
Xenbase Sato,
Localized and inducible expression of Xenopus-posterior (Xpo), a novel gene active in early frog embryos, encoding a protein with a 'CCHC' finger domain.
1991,
Pubmed
,
Xenbase Schmidt,
Regulation of dorsal-ventral patterning: the ventralizing effects of the novel Xenopus homeobox gene Vox.
1996,
Pubmed
,
Xenbase Shi,
Structural insights on Smad function in TGFbeta signaling.
2001,
Pubmed Shi,
Crystal structure of a Smad MH1 domain bound to DNA: insights on DNA binding in TGF-beta signaling.
1998,
Pubmed Shim,
A novel family of retrotransposons in Xenopus with a developmentally regulated expression.
2000,
Pubmed
,
Xenbase Smit,
Identification of a new, abundant superfamily of mammalian LTR-transposons.
1993,
Pubmed Smit,
Interspersed repeats and other mementos of transposable elements in mammalian genomes.
1999,
Pubmed Steinbeisser,
The role of gsc and BMP-4 in dorsal-ventral patterning of the marginal zone in Xenopus: a loss-of-function study using antisense RNA.
1995,
Pubmed
,
Xenbase Summers,
Nucleocapsid zinc fingers detected in retroviruses: EXAFS studies of intact viruses and the solution-state structure of the nucleocapsid protein from HIV-1.
1992,
Pubmed Suzuki,
Xenopus msx1 mediates epidermal induction and neural inhibition by BMP4.
1997,
Pubmed
,
Xenbase Vize,
DNA sequences mediating the transcriptional response of the Mix.2 homeobox gene to mesoderm induction.
1996,
Pubmed
,
Xenbase Vogel,
Promoter activity of the zebrafish bhikhari retroelement requires an intact activin signaling pathway.
1999,
Pubmed
,
Xenbase Watabe,
Molecular mechanisms of Spemann's organizer formation: conserved growth factor synergy between Xenopus and mouse.
1995,
Pubmed
,
Xenbase Whitman,
Smads and early developmental signaling by the TGFbeta superfamily.
1998,
Pubmed Wrana,
Regulation of Smad activity.
2000,
Pubmed Xu,
Differential regulation of neurogenesis by the two Xenopus GATA-1 genes.
1997,
Pubmed
,
Xenbase Yang,
Deletion analysis of both the long terminal repeat and the internal promoters of the human foamy virus.
1997,
Pubmed Yeo,
The role of FAST-1 and Smads in transcriptional regulation by activin during early Xenopus embryogenesis.
1999,
Pubmed
,
Xenbase Zaret,
Site-directed mutagenesis reveals a liver transcription factor essential for the albumin transcriptional enhancer.
1990,
Pubmed Zawel,
Human Smad3 and Smad4 are sequence-specific transcription activators.
1998,
Pubmed Zhang,
Synergistic cooperation between Sp1 and Smad3/Smad4 mediates transforming growth factor beta1 stimulation of alpha 2(I)-collagen (COL1A2) transcription.
2000,
Pubmed Zhou,
Characterization of human FAST-1, a TGF beta and activin signal transducer.
1998,
Pubmed
,
Xenbase
