The Airn RNA does not require any DNA elements within its locus to silence distant imprinted genes
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ABSTRACT:
PROVIDER: PRJNA528075 | ENA |
REPOSITORIES: ENA
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Project description:Long non-coding (lnc) RNAs are numerous and found throughout the mammalian genome, and many are thought to be involved in the regulation of gene expression. However, the majority remain relatively uncharacterised and of uncertain function making the use to model systems to uncover their mode of action valuable. Imprinted lncRNAs target and recruit epigenetic silencing to a cluster of imprinted genes on the same chromosome, making them one of the best characterized lncRNAs to silence distant genes in cis. In this study we examined silencing of the distant imprinted gene Slc22a3 by the lncRNA Airn in the Igf2r imprinted cluster in mouse. Previously we proposed that imprinted lncRNAs may silence distant imprinted genes by disrupting promoter-enhancer interactions by being transcribed through the enhancer, which we called the enhancer interference hypothesis. Here we tested this hypothesis by first using allele-specific chromosome conformation capture (3C) to detect interactions between the Slc22a3 promoter and the locus of the Airn lncRNA that silences it on the paternal chromosome. In agreement with the model we found interactions enriched on the maternal allele, but across the entire Airn gene consistent with multiple enhancer-promoter interactions. Therefore, to further test the enhancer interference hypothesis we devised an approach to delete the entire Airn gene. However, the deletion showed that there are no essential enhancers for Slc22a3 within the Airn gene, strongly indicating that the Airn RNA rather than its transcription is responsible for silencing distant imprinted genes. Therefore we propose an alternative hypothesis whereby the chromosome interactions may initially guide the lncRNA to target imprinted promoters and recruit repressive chromatin, and that these interactions are lost once silencing is established.
2019-07-07 | GSE128513 | GEO
Project description: Not available
| S-EPMC6675118 | biostudies-literature
Project description: Not available
| S-EPMC7577474 | biostudies-literature
Project description:To test if the imprinted long non-coding RNA (lncRNA) Airn transcription or its product silences the protein-coding Igf2r gene, we shortened the endogenous lncRNA to four different lengths by inserting polyadenylation (polyA) cassettes on the paternal chromosome via homologous recombination in ES cells. ES cell differentiation was used to recapitulate the developmental onset of Airn and Igf2r imprinted expression and polyA cassettes inserted before (T3, T16, T27) or after (T31, T51) the Igf2r promoter successfully truncated Airn, with the exception of T27. RNA hybridization to a tiling array (MIRTA) demonstrated loss of Airn upstream of the Igf2r promoter (except T27) and absence of novel spliced variants in all truncation alleles. To further test the transcriptional overlap model we moved the Airn promoter ~700bp before the Igf2r TSS in ES cells that lack an endogenous paternal Airn promoter and called this cell line FAP (Forward-Airn-Promoter). RNA hybridization to a tiling array (MIRTA) demonstrated that the moved Airn promoter expresses Airn in wildtype orientation and terminates at the wildtype 3' end. ES cell lines expressing different Airn variants were differentiated on gelatinized dishes after feeder cell depletion and LIF withdrawal by 0.27M-BM-5M retinoic acid for 5 days and Airn length was assayed.
2012-12-20 | E-GEOD-41444 | biostudies-arrayexpress
Project description:To test if the imprinted long non-coding RNA (lncRNA) Airn transcription or its product silences the protein-coding Igf2r gene, we shortened the endogenous lncRNA to four different lengths by inserting polyadenylation (polyA) cassettes on the paternal chromosome via homologous recombination in ES cells. ES cell differentiation was used to recapitulate the developmental onset of Airn and Igf2r imprinted expression and polyA cassettes inserted before (T3, T16, T27) or after (T31, T51) the Igf2r promoter successfully truncated Airn, with the exception of T27. RNA hybridization to a tiling array (MIRTA) demonstrated loss of Airn upstream of the Igf2r promoter (except T27) and absence of novel spliced variants in all truncation alleles. To further test the transcriptional overlap model we moved the Airn promoter ~700bp before the Igf2r TSS in ES cells that lack an endogenous paternal Airn promoter and called this cell line FAP (Forward-Airn-Promoter). RNA hybridization to a tiling array (MIRTA) demonstrated that the moved Airn promoter expresses Airn in wildtype orientation and terminates at the wildtype 3' end.
2012-12-20 | GSE41444 | GEO
Project description:Imprinted macro ncRNAs such as Airn play an important role in silencing protein-coding genes in cis, macro ncRNAs could be a common feature in all imprinted gene clusters. By applying the RNA Expression on Tiling Array (RETA) technique, macro ncRNAs were found to be abundant in 26 known mouse genomic regions containing imprinted genes were detected. All well-known imprinted macro ncRNAs were up-regulated upon depletion of DNA methylation.
2017-02-25 | GSE26718 | GEO
Project description:Background: In mammals, tight regulation of cytosine methylation is required for embryonic development and cellular differentiation. The trans-acting DNA methyltransferases that catalyze this modification have been identified and characterized; however, these proteins lack sequence specificity, leaving the mechanism of targeting unknown. A cis acting regulator within the Rasgrf1 imprinting control region (ICR) is necessary for establishment and maintenance of imprinted methylation at the locus. Here we investigate whether 3kb of sequence from the Rasgrf1 ICR is sufficient to direct appropriate imprinted methylation and target-gene expression patterns when ectopically inserted at the Wnt1 locus. Results: The Rasgrf1 ICR at Wnt1 lacked somatic methylation when maternally transmitted, and was fully methylated upon paternal transmission, consistent with its behavior at the Rasgrf1 locus. It was unmethylated in the female germline and was enriched for methylation in the male germline, though not to the levels seen at the endogenous Rasgrf1 allele. Wnt1 expression was not imprinted by our construct, likely due to additional sequences being required for this function. Conclusion: We have identified sequences that are sufficient for partial establishment and full maintenance of the imprinted DNA methylation patterns. Because full somatic methylation can occur without full gametic methylation, we infer that somatic methylation of the Rasgrf1 ICR is not simply a consequence of maintained gametic methylation.
2016-09-12 | GSE79895 | GEO
Project description:It is increasingly being recognized that physical interactions between distant chromosomal loci influence the expressivity of the genome. Thus, multiple enhancers may converge on a single gene promoter 1,2 and a single enhancer can stochastically loop to multiple promoters 3. Regulatory elements from neighboring domains or from other chromosomes may interact to generate chromatin structures poised for transcription4-8 or repression 9-11. However, a broader perspective on the formation and function of such networks remains largely unexplored. Using the high-resolution 4C (Circular Chromosome Conformation Capture) analysis, we identify here a genome-wide physical network between genomically imprinted domains impinging H19 imprinting control region (ICR). Sequences interacting with the H19 ICR constitutively map at or within most of known imprinted domains both in mouse embryonic stem cells and in vitro-derived embryoid bodies, despite distinct differences in chromatin environments. Moreover, all-to-all 3D DNA FISH analyses revealed that imprinted domains from 7 different chromosomes co-localize with each other in pair-wise patterns, highlighting the dynamic nature of these interactions. The observed interaction network is dependent on CTCF binding sites within the maternally inherited H19 ICR allele and delays reprogramming of epigenetic features at imprinted domains during male germline development. As other imprinted regions can interact with each other in an H19 ICR-dependent manner, the H19 ICR emerges as an organizer of chromosomal networks by specifically recognizing and reconfiguring imprinted domains. We propose that an ancient key regulatory region, such as the H19 ICR, gradually impacted epigenetic modifications via long-range interactions in the germline to facilitate the recruitment of imprinted genes and their formation in clusters during mammalian radiation. Furthermore, the perspective of epigenetic lesions de-stabilizing such chromosomal networks may advance our understanding of how quantitative traits influence human diseases, such as cancer.
2009-12-14 | GSE14074 | GEO
Project description: Not available
| S-EPMC3978896 | biostudies-literature
Project description:Naive pluripotent epiblast cells of the preimplantation murine embryo and their in vitro counterpart, embryonic stem (ES) cells, have the capacity to give rise to all cells of the adult. Such developmental plasticity is associated with global genome hypomethylation. It is unclear whether genome methylation is dynamically regulated only via differential expression of DNA methyltransferases (DNMTs) and Ten-eleven Translocation (TET) enzymes, which oxidase methylated DNA. Here we show that LIF/Stat3 signalling induces genomic hypomethylation via metabolic reconfiguration. In Stat3-/- ES cells we observed decreased alpha-ketoglutarate (ɑKG) production from reductive Glutamine metabolism, leading to decreased TET activity, increased Dnmt3a/b expression and to a global increase in DNA methylation. Notably, genome methylation is dynamically controlled by simply modulating αKG availability, mitochondrial activity or Stat3 activation in mitochondria, indicating effective crosstalk between metabolism and the epigenome. Stat3-/- ES cells also show increased methylation at Imprinting Control Regions accompanied with differential expression of >50% of imprinted genes. Single-cell transcriptome analysis of Stat3-/- embryos confirmed dysregulated expression of Dnmt3a/b, Tet2, and imprinted genes in vivo. Our results reveal that the LIF/Stat3 signal bridges the metabolic and epigenetic profiles of naive pluripotent cells, ultimately controlling genome methylation and imprinted gene expression. Several imprinted genes regulate cell proliferation and are often misregulated in tumors. Moreover, a wide range of cancers display Stat3-overactivation, raising the possibility that the molecular module we described here is exploited under pathological conditions.
2020-11-26 | PXD020385 | Pride