Relocalization of retinoic acid receptors from non-canonical to canonical spaced binding elements during embryoid body differentiation
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ABSTRACT: Retinoic Acid Receptors (RARs) bind RA-response elements in regulatory regions of their target genes. While canonical RAREs comprise direct repeats of the consensus 5’-RGKTCA-3’ sequence separated by 1, 2 or 5 nucleotides (DR1, DR2, DR5), we show that shortly after RA treatement of mouse embryoid bodies or F9 cells, RARs occupy a large repertoire of DR0, DR2, DR5, DR8 and IR0 elements. In vitro, RAR-RXR bind these non-canonical spacings with comparable affinities to DR2 and DR5. Most DR8 elements comprise three half sites with DR2 and DR0 spacings. This specific half site organisation constitutes a previously unrecognised, but frequent signature of RAR binding elements and acts as an RARE. At later stages of embryoid body differentiation, RARs relocalise to a restricted repertoire of sites comprising predominantly DR5 elements. Differentiation thus involves genomic relocalisation of RARs, and a switch from DR0 and DR8 at early times to DR5 at later stages.
Project description:Retinoic Acid Receptors (RARs) bind RA-response elements in regulatory regions of their target genes. While canonical RAREs comprise direct repeats of the consensus 5’-RGKTCA-3’ sequence separated by 1, 2 or 5 nucleotides (DR1, DR2, DR5), we show that shortly after RA treatement of mouse embryoid bodies or F9 cells, RARs occupy a large repertoire of DR0, DR2, DR5, DR8 and IR0 elements. In vitro, RAR-RXR bind these non-canonical spacings with comparable affinities to DR2 and DR5. Most DR8 elements comprise three half sites with DR2 and DR0 spacings. This specific half site organisation constitutes a previously unrecognised, but frequent signature of RAR binding elements and acts as an RARE. At later stages of embryoid body differentiation, RARs relocalise to a restricted repertoire of sites comprising predominantly DR5 elements. Differentiation thus involves genomic relocalisation of RARs, and a switch from DR0 and DR8 at early times to DR5 at later stages. Examination of genomic localisation of RAR in differentiating embryoid bodies.
Project description:Retinoic Acid Receptors (RARs) as a functional heterodimer with Retinoid X Receptors (RXRs), bind a diverse series of RA-response elements (RAREs) in regulated genes. Among them, the non-canonical DR0 elements are bound by RXR-RAR with comparable affinities to DR5 elements but DR0 elements do not act transcriptionally as independent RAREs. In this work, we present structural insight for the recognition of DR5 and DR0 elements by RXR-RAR heterodimer using x-ray crystallography, small angle x-ray scattering, and hydrogen/deuterium exchange coupled to mass spectrometry. We solved the crystal structure of RXR-RAR DNA-binding domain in complex with the Rarb2 DR5 and RXR DNA-binding domain in complex with Hoxb13 DR0. While cooperative binding was observed on DR5, on DR0 the two molecules bound non-cooperatively on opposite sides of the DNA. In addition, our data unveil the structural organization and dynamics of the multi-domain RXR-RAR DNA complexes providing evidence for DNA-dependent allosteric communication between domains. Differential binding mode between DR0 and DR5 were observed leading to differences in the conformation and structural dynamics of the multi-domain RXR-RAR DNA complex. These results reveal that the topological organization of the RAR binding element confer regulatory information by modulating the overall topology and structural dynamics of the RXR-RAR heterodimers.
Project description:Retinoic acid (RA) triggers growth-suppressive effects in tumor cells and therefore RA and its synthetic analogs have great potential as anti-carcinogenic agents. RA effects are mediated by retinoic acid receptors (RARs), which regulate gene expression in an RA-dependent manner. To define the genetic network regulated by RARs in breast cancer cells, we identified RAR genomic targets using chromatin immunoprecipitation and expression analysis in a model breast cancer cell line MCF-7. Furthermore, we identified genomic binding sites for two putative RAR coregulators FoxA1 and GATA3. Keywords: ChIP-Chip Analysis
Project description:Retinoic acid receptors (RARs) ?, ?, and ? heterodimerize with Retinoid X receptors (RXR) ?, ?, and ? and bind the cis-acting response elements known as RAREs to execute the biological functions of retinoic acid during mammalian development. RAR? mediates the anti-proliferative and apoptotic effects of retinoids in certain tissues and cancer cells, such as melanoma and neuroblastoma cells. Furthermore, ablation of RAR? enhanced the tumor incidence of Ras transformed keratinocytes and was associated with resistance to retinoid mediated growth arrest and apoptosis. We used microarray analysis to identify genes, which upon 8 or 24 hr of treatment with all-trans retinoic acid display differential expression in RAR? knockout (RAR?KO) murine embryonic stem cells relative to CCE WT cells. We demonstrate that following RA treatment the majority of inducible transcripts are present at lower levels in RAR?KO ES cells compared to WT ES cells. Murine embryonic stem cells (WT and RAR?KO) were treated with either all-trans retinoic acid (up to 24 hr) or with vehicle control (EtOH).
Project description:Retinoid signaling is important for patterning the vertebrate hindbrain and midaxial regions. We recently showed that signaling through retinoic acid receptors (RARs) is essential for anteroposterior patterning along the entire body axis. To further investigate the mechanisms through which RARs act, we employed microarray analysis to investigate the effects of modulating RAR activity on target gene expression. We identified 334 upregulated genes (92% of which were validated) including known RA responsive genes, known genes that have never been proposed as RA targets and many hypothetical and unidentified genes (n = 166). 67 validated downregulated genes were identified including known RA responsive genes and anterior marker genes. The expression patterns of selected upregulated genes (n = 45) were examined at neurula stages using whole mount in situ hybridization. We found that most of these genes were expressed in the neural tube and many were expressed in anterior tissues such as neural crest, brain, eye anlagen, and cement gland. Some were expressed in tissues such as notochord, somites, pronephros and blood islands, where retinoic acid (RA) plays established roles in organogenesis. Members of this set of newly identified RAR target genes are likely to play important roles in neural patterning and organogenesis under the control of RAR signaling pathways and their further characterization will expand our understanding of RA signaling during development. Keywords = retinoid Keywords = microarray Keywords = RAR Keywords = neurula Keywords = anteroposterior patterning Keywords = and organogenesis
Project description:Retinoid signaling is important for patterning the vertebrate hindbrain and midaxial regions. We recently showed that signaling through retinoic acid receptors (RARs) is essential for anteroposterior patterning along the entire body axis. To further investigate the mechanisms through which RARs act, we employed microarray analysis to investigate the effects of modulating RAR activity on target gene expression. We identified 334 upregulated genes (92% of which were validated) including known RA responsive genes, known genes that have never been proposed as RA targets and many hypothetical and unidentified genes (n = 166). 67 validated downregulated genes were identified including known RA responsive genes and anterior marker genes. The expression patterns of selected upregulated genes (n = 45) were examined at neurula stages using whole mount in situ hybridization. We found that most of these genes were expressed in the neural tube and many were expressed in anterior tissues such as neural crest, brain, eye anlagen, and cement gland. Some were expressed in tissues such as notochord, somites, pronephros and blood islands, where retinoic acid (RA) plays established roles in organogenesis. Members of this set of newly identified RAR target genes are likely to play important roles in neural patterning and organogenesis under the control of RAR signaling pathways and their further characterization will expand our understanding of RA signaling during development. Keywords = retinoid Keywords = microarray Keywords = RAR Keywords = neurula Keywords = anteroposterior patterning Keywords = and organogenesis Keywords: repeat sample
Project description:Retinoic acid (RA) triggers growth-suppressive effects in tumor cells and therefore RA and its synthetic analogs have great potential as anti-carcinogenic agents. RA effects are mediated by retinoic acid receptors (RARs), which regulate gene expression in an RA-dependent manner. To define the genetic network regulated by RARs in breast cancer cells, we identified RAR genomic targets using chromatin immunoprecipitation and expression analysis in a model breast cancer cell line MCF-7. Furthermore, we identified genomic binding sites for two putative RAR coregulators FoxA1 and GATA3. Keywords: ChIP-Chip Analysis This series contains ChIP-Chip raw data for four transcription factors (RARA, RARG, FoxA1 and GATA3) in MCF-7 cells. All the experiments are done in triplicates. We mapped the binding sites of RARA, RARG and GATA3 in the bacterial artificial chromosome (BAC) transgenic MCF7 cells in which we tagged the transcription factors with a modified LAP (localization and affinity purification) tag containing green fluorescent protein (GFP). Goat anti-GFP (raised against His-tagged full-length eGFP and affinity-purified with GST-tagged full-length eGFP) was used to perform ChIP experiments in those transgenic lines. To map the binding sites of RARs, MCF7 Cells were hormone-deprived for 3 days and then were treated with 100 nM AM580 (RARA-selective agonist) or 100 nM CD437 (RARG-selective agonist) for 1 hour at 80% confluence. FoxA1 binding sites were mapped using goat anti-FoxA1 antibodies (Abcam: ab5089). Control data include Input from MCF-7 cells. ChIP-Chip experiments with eGFP antibody in wide type MCF-7 cells are used to control eGFP antibody non-specific binding.
Project description:In mouse embryonic cells, a retinoic acid (RA) stimulation triggers a massive change of gene expression leading the pluripotent, proliferating cells to a lineage-specific differentiation process. The retinoic acid receptor (RAR) plays a key role in this response by inhibiting pluripotency-maintaining genes and simultaneously activating some major actors of cell differentiation. To investigate the mechanism underlying this dual regulation, we performed joint RAR/RXR ChIP-seq and mRNA-seq time series during the first 48 hours of the RA-induced Primitive Endoderm differentiation process in F9 embryonic carcinoma cells. We detected significantly more RAR/RXR binding regions than previous studies and identified among them a handful of typical binding intensity patterns during differentiation. We demonstrate that these patterns are correlated with the coincidental binding of essential transcription factors (TFs) for pluripotency maintenance or PrE differentiation of embryonic stem (ES) cells, as well as the presence of variants of RAR binding motifs. Most importantly, early-bound regions coincide with pluripotency-associated transcription factor binding in ES (like Pou5f1, Sox2, Esrrb and Nr5a2) and display an increased frequency of the DR0 type RAR binding motifs; late-bound sites are associated to the PrE marker Sox17 and are enriched in the canonical DR5 binding motif. Our data offer an unprecedently detailed view on the action of RA in triggering pluripotent cell differentiation. Altogether, this work sheds light on the relocation of RAR/RXR binding sites throughout differentiation, and shows how RAR/RXR progressively shift from DR0 enriched regions, which were specifically identified in undifferentiated models, to canonical RAR binding sites containing loci.
Project description:In mouse embryonic cells, a retinoic acid (RA) stimulation triggers a massive change of gene expression leading the pluripotent, proliferating cells to a lineage-specific differentiation process. The retinoic acid receptor (RAR) plays a key role in this response by inhibiting pluripotency-maintaining genes and simultaneously activating some major actors of cell differentiation. To investigate the mechanism underlying this dual regulation, we performed joint RAR/RXR ChIP-seq and mRNA-seq time series during the first 48 hours of the RA-induced Primitive Endoderm differentiation process in F9 embryonic carcinoma cells. We detected significantly more RAR/RXR binding regions than previous studies and identified among them a handful of typical binding intensity patterns during differentiation. We demonstrate that these patterns are correlated with the coincidental binding of essential transcription factors (TFs) for pluripotency maintenance or PrE differentiation of embryonic stem (ES) cells, as well as the presence of variants of RAR binding motifs. Most importantly, early-bound regions coincide with pluripotency-associated transcription factor binding in ES (like Pou5f1, Sox2, Esrrb and Nr5a2) and display an increased frequency of the DR0 type RAR binding motifs; late-bound sites are associated to the PrE marker Sox17 and are enriched in the canonical DR5 binding motif. Our data offer an unprecedently detailed view on the action of RA in triggering pluripotent cell differentiation. Altogether, this work sheds light on the relocation of RAR/RXR binding sites throughout differentiation, and shows how RAR/RXR progressively shift from DR0 enriched regions, which were specifically identified in undifferentiated models, to canonical RAR binding sites containing loci. Time course (0, 2, 6, 12, 24, 48h) after stimulation of F9 cultured cells by retinoic acid: PanRAR and PanRXR ChIP-seq at 0, 2, 24 and 48h (no replicate); WCE-seq at 0h (no replicate); mRNA-seq at 0, 6, 12, 24, 48h (2 replicates except for time 0h, 4 replicates). Additionally, a control time course (culture in DMSO) sampled at 24 and 48h (no replicates).
Project description:Retinoic acid (RA) is a potent inducer of cell differentiation and plays an essential role in sex-specific germ cell development in the mammalian gonad. RA is essential for male gametogenesis and hence fertility. However, RA can also disrupt sexual cell fate in somatic cells of the testis, promoting transdifferentiation of male Sertoli cells to female granulosa-like cells when the male sexual regulator Dmrt1 is absent. The feminizing ability of RA in the somatic testis suggests that RA might normally play a role in somatic cell differentiation or cell fate maintenance in the ovary. To test for this possibility we disrupted RA signaling in somatic cells of the early fetal ovary using three genetic strategies and one pharmaceutical approach. We found that deleting all three RA receptors (RARs) in the XX somatic gonad at the time of sex determination did not significantly affect ovarian differentiation, follicle development, or female fertility. Transcriptome analysis of adult triple mutant ovaries revealed remarkably little effect on gene expression in the absence of somatic RAR function. Likewise, deletion of three RA synthesis enzymes (Aldha1-3) at the time of sex determination did not masculinize the ovary. A dominant-negative RAR transgene altered granulosa cell proliferation, likely due to interference with a non-RA signaling pathway, but did not affect granulosa cell specification or fertility. Finally, culture of fetal XX gonads with an RAR antagonist blocked germ cell meiotic initiation but did not disrupt sex-biased gene expression. We conclude that RA signaling, although crucial in the ovary for meiotic initiation, is not required for granulosa cell specification, differentiation, or reproductive function.