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Role of CTCF Protein in Regulating FMR1 Locus Transcription

Fragile X syndrome (FXS), the leading cause of inherited intellectual disability, is caused by epigenetic silencing of the FMR1 gene, through expansion and methylation of a CGG triplet repeat (methylated full mutation). An antisense transcript (FMR1-AS1), starting from both promoter and intron 2 of...

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Autores principales: Lanni, Stella, Goracci, Martina, Borrelli, Loredana, Mancano, Giorgia, Chiurazzi, Pietro, Moscato, Umberto, Ferrè, Fabrizio, Helmer-Citterich, Manuela, Tabolacci, Elisabetta, Neri, Giovanni
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2013
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3715420/
https://www.ncbi.nlm.nih.gov/pubmed/23874213
http://dx.doi.org/10.1371/journal.pgen.1003601
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author Lanni, Stella
Goracci, Martina
Borrelli, Loredana
Mancano, Giorgia
Chiurazzi, Pietro
Moscato, Umberto
Ferrè, Fabrizio
Helmer-Citterich, Manuela
Tabolacci, Elisabetta
Neri, Giovanni
author_facet Lanni, Stella
Goracci, Martina
Borrelli, Loredana
Mancano, Giorgia
Chiurazzi, Pietro
Moscato, Umberto
Ferrè, Fabrizio
Helmer-Citterich, Manuela
Tabolacci, Elisabetta
Neri, Giovanni
author_sort Lanni, Stella
collection PubMed
description Fragile X syndrome (FXS), the leading cause of inherited intellectual disability, is caused by epigenetic silencing of the FMR1 gene, through expansion and methylation of a CGG triplet repeat (methylated full mutation). An antisense transcript (FMR1-AS1), starting from both promoter and intron 2 of the FMR1 gene, was demonstrated in transcriptionally active alleles, but not in silent FXS alleles. Moreover, a DNA methylation boundary, which is lost in FXS, was recently identified upstream of the FMR1 gene. Several nuclear proteins bind to this region, like the insulator protein CTCF. Here we demonstrate for the first time that rare unmethylated full mutation (UFM) alleles present the same boundary described in wild type (WT) alleles and that CTCF binds to this region, as well as to the FMR1 gene promoter, exon 1 and intron 2 binding sites. Contrariwise, DNA methylation prevents CTCF binding to FXS alleles. Drug-induced CpGs demethylation does not restore this binding. CTCF knock-down experiments clearly established that CTCF does not act as insulator at the active FMR1 locus, despite the presence of a CGG expansion. CTCF depletion induces heterochromatinic histone configuration of the FMR1 locus and results in reduction of FMR1 transcription, which however is not accompanied by spreading of DNA methylation towards the FMR1 promoter. CTCF depletion is also associated with FMR1-AS1 mRNA reduction. Antisense RNA, like sense transcript, is upregulated in UFM and absent in FXS cells and its splicing is correlated to that of the FMR1-mRNA. We conclude that CTCF has a complex role in regulating FMR1 expression, probably through the organization of chromatin loops between sense/antisense transcriptional regulatory regions, as suggested by bioinformatics analysis.
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spelling pubmed-37154202013-07-19 Role of CTCF Protein in Regulating FMR1 Locus Transcription Lanni, Stella Goracci, Martina Borrelli, Loredana Mancano, Giorgia Chiurazzi, Pietro Moscato, Umberto Ferrè, Fabrizio Helmer-Citterich, Manuela Tabolacci, Elisabetta Neri, Giovanni PLoS Genet Research Article Fragile X syndrome (FXS), the leading cause of inherited intellectual disability, is caused by epigenetic silencing of the FMR1 gene, through expansion and methylation of a CGG triplet repeat (methylated full mutation). An antisense transcript (FMR1-AS1), starting from both promoter and intron 2 of the FMR1 gene, was demonstrated in transcriptionally active alleles, but not in silent FXS alleles. Moreover, a DNA methylation boundary, which is lost in FXS, was recently identified upstream of the FMR1 gene. Several nuclear proteins bind to this region, like the insulator protein CTCF. Here we demonstrate for the first time that rare unmethylated full mutation (UFM) alleles present the same boundary described in wild type (WT) alleles and that CTCF binds to this region, as well as to the FMR1 gene promoter, exon 1 and intron 2 binding sites. Contrariwise, DNA methylation prevents CTCF binding to FXS alleles. Drug-induced CpGs demethylation does not restore this binding. CTCF knock-down experiments clearly established that CTCF does not act as insulator at the active FMR1 locus, despite the presence of a CGG expansion. CTCF depletion induces heterochromatinic histone configuration of the FMR1 locus and results in reduction of FMR1 transcription, which however is not accompanied by spreading of DNA methylation towards the FMR1 promoter. CTCF depletion is also associated with FMR1-AS1 mRNA reduction. Antisense RNA, like sense transcript, is upregulated in UFM and absent in FXS cells and its splicing is correlated to that of the FMR1-mRNA. We conclude that CTCF has a complex role in regulating FMR1 expression, probably through the organization of chromatin loops between sense/antisense transcriptional regulatory regions, as suggested by bioinformatics analysis. Public Library of Science 2013-07-18 /pmc/articles/PMC3715420/ /pubmed/23874213 http://dx.doi.org/10.1371/journal.pgen.1003601 Text en © 2013 Lanni et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Lanni, Stella
Goracci, Martina
Borrelli, Loredana
Mancano, Giorgia
Chiurazzi, Pietro
Moscato, Umberto
Ferrè, Fabrizio
Helmer-Citterich, Manuela
Tabolacci, Elisabetta
Neri, Giovanni
Role of CTCF Protein in Regulating FMR1 Locus Transcription
title Role of CTCF Protein in Regulating FMR1 Locus Transcription
title_full Role of CTCF Protein in Regulating FMR1 Locus Transcription
title_fullStr Role of CTCF Protein in Regulating FMR1 Locus Transcription
title_full_unstemmed Role of CTCF Protein in Regulating FMR1 Locus Transcription
title_short Role of CTCF Protein in Regulating FMR1 Locus Transcription
title_sort role of ctcf protein in regulating fmr1 locus transcription
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3715420/
https://www.ncbi.nlm.nih.gov/pubmed/23874213
http://dx.doi.org/10.1371/journal.pgen.1003601
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