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PINT lincRNA connects the p53 pathway with epigenetic silencing by the Polycomb Repressive Complex 2 (MEF cells)

ABSTRACT: It has been recently shown that the transcription factor p53 induces the expression of multiple lincRNAs. However, relatively little is known about the role that lincRNAs play in this pathway. Here we characterize a lincRNA named PINT (p53 Induced Noncoding Transcript). We show that PINT is a ubiquitously expressed lincRNA that is finely regulated by p53. In mouse cells, PINT promotes cell proliferation and survival by regulating the expression of genes of TGF-beta, MAPK and p53 pathways. PINT is a nuclear lincRNA that directly interacts with Polycomb Repressive Complex 2 (PRC2), being required for PRC2 targeting of specific genes for repression. Furthermore, PINT functional activity is dependent on PRC2 expression, representing a connection between the p53 pathway and epigenetic regulation by PRC2. We have also identified PINT human ortholog (hPINT), which presents suggestive analogies with the mouse lincRNA. hPINT is similarly regulated by p53, and its expression correlates significantly with the same cellular pathways as the mouse ortholog, including the p53 pathway. Interestingly, hPINT is significantly downregulated in colon cancer, representing a novel tumor suppressor candidate. Our results not only help our understanding of the role of p53 and lincRNAs in cancer, but also contribute to the open debate regarding the utility of mouse models for the study of lincRNAs.

ORGANISM(S): Mus musculus

PROVIDER: GSE46247 | GEO | 2013/08/09

SECONDARY ACCESSION(S): PRJNA198507

REPOSITORIES: GEO

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Project description:We recently showed that the mammalian genome encodes more than a thousand large intergenic non-coding RNAs (lincRNAs) that are clearly conserved across mammals and thus functional. Gene expression patterns have implicated these lincRNAs in diverse biological processes including cell cycle regulation, immune surveillance, and embryonic stem cell pluripotency. However, the mechanism by which these lincRNAs function is unknown. Here, we expand the catalog of human lincRNAs to ~3300 by analyzing chromatin-state maps of various human cell types. Inspired by the observation that the well-characterized lincRNA HOTAIR bind the Polycomb Repressive Complex 2 (PRC2), we tested whether many lincRNAs are physically associated with PRC2. Remarkably, we observe that ~20% of lincRNAs expressed in various cell types are bound by PRC2, and that additional lincRNAs are bound by other chromatin-modifying complexes. Moreover, we show that siRNA-mediated depletion of certain lincRNAs associated with PRC2 leads to changes in gene expression and that the upregulated genes are enriched for those normally silenced by PRC2. We propose a model in which some lincRNAs guide chromatin–modifying complexes to specific genomic loci to regulate gene expression. siRNA-mediated lincRNA knockdown siRNAs targeting specific lincRNAs were transected into human fibroblasts. Non-targeting siRNAs were used as controls. Both of these experiment types were hybridized to Affymetrix gene expression arrays. PRC2 RIP-Chip The PRC2 complex was immunoprecipitated using antibodies targetting Suz12 and the associated RNA was hybridized to Nimblegen tiling arrays representing lincRNAs. In parallel an IgG IP was performed and hybridized to the same NG arrays. RIP was performed for PRC2 and hybridized using a Cy3 label. In parallel, RIP was performed using IGG and labelled with Cy5 PRC2 RIP-Chip (dye swap) The PRC2 complex was immunoprecipitated using antibodies targetting Suz12 and the associated RNA was hybridized to Nimblegen tiling arrays representing lincRNAs. In parallel an IgG IP was performed and hybridized to the same NG arrays. RIP was performed for PRC2 and hybridized using a Cy5 label. In parallel, RIP was performed using IGG and labelled with Cy3 PRC2 RIP-Chip (no proteins) The PRC2 complex was immunoprecipitated using antibodies targetting Suz12 and the associated RNA was hybridized to Nimblegen tiling arrays representing lincRNAs. In parallel an IgG IP was performed and hybridized to the same NG arrays. RIP was performed for PRC2 and hybridized using a Cy3 label. In parallel, RIP was performed using IGG and labelled with Cy5 COREST RIP-Chip The COREST complex was immunoprecipitated using antibodies targetting COREST and the associated RNA was hybridized to Nimblegen tiling arrays representing lincRNAs. In parallel an IgG IP was performed and hybridized to the same NG arrays. RIP was performed for COREST and hybridized using a Cy3 label. In parallel, RIP was performed using IGG and labelled with Cy5 H3K27me3 and H3K4me2 modified histones RIP-Chip The H3K27me3 and H3K4me2 modified histones were immunoprecipitated using antibodies targetting COREST and the associated RNA was hybridized to Nimbelgen tiling arrays representing lincRNAs. In parallel an IgG IP was performed and hybridized to the same NG arrays. RIP was performed for COREST and hybridized using a Cy3 label. In parallel, RIP was performed using IGG and labelled with Cy5 Human lincRNA expression Human lincRNAs were profiled in HeLa, Lung FB, and Foot FB. In addition, nuclear and cytoplasmic fractions were taken in HeLa cells Total RNA was extracted from HeLa, Foot, and Lung cells and hybridized to NG tiling array. In addition, the nucleus was fractionated and RNA was hybridized to an array.

Project description:Recently, more than a thousand large intergenic non-coding RNAs (lincRNAs) have been reported. These RNAs are evolutionarily conserved in mammalian genomes and thus presumably function in diverse biological processes. Here, we report the identification of lincRNAs that are regulated by p53. One of these lincRNAs (lincRNA-p21) serves as a repressor in p53-dependent transcriptional responses. Inhibition of lincRNA-p21 affects the expression of hundreds of gene targets enriched for genes normally repressed by p53. The observed transcriptional repression by lincRNA-p21 is mediated through the physical association with hnRNP-K. This interaction is required for proper genomic localization of hnRNP-K at repressed genes and regulation of p53 mediated apoptosis. We propose a model whereby transcription factors activate lincRNAs that serve as key repressors by physically associating with repressive complexes and modulating their localization to sets of previously active genes. Gene expression profiles of different p53 inducible mouse embryonic fibroblasts (p53LSL/LSL MEFs) across different time points after DNA damage. A large intergenic noncoding RNA induced by p53 mediates global gene repression in the p53 transcriptional response. [1] MEF profiling: p53 LSL/LSL MEFs were treated with adenoCRE for p53 restoration or adenoGFP as control for 24h and treated with 500nM doxorubicin for the indicated times. [2] hnRNPKKD profiling: p53 LSL/LSL MEFs were treated with adenoCRE for p53 restoration for 24h, transfected with siRNA oligos targeting different transcripts for 24h and then treated with 100nM doxorubicin for 13h. [3] lincP21KD profiling: p53 LSL/LSL MEFs were treated with adenoCRE for p53 restoration for 24h, transfected with siRNA oligos targeting different transcripts for 24h and then treated with 100nM doxorubicin for 13h. [4] RAS profiling: For p53 restoration, cultured tumor cell lines were incubated with 500nM 4-hydroxytamoxifen for the indicated times.

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PINT lincRNA connects the p53 pathway with epigenetic silencing by the Polycomb Repressive Complex 2 (MEF cells)

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