Cited by 92Genetics and Neurodevelopmental DisordersEpigenetics and DNA MethylationGenetic Neurodegenerative Diseases

Differential epigenetic modifications in the FMR1 gene of the fragile X syndrome after reactivating pharmacological treatments

Tabolacci, Elisabetta, Pietrobono, Roberta, Moscato, Umberto, Oostra, Ben A, Chiurazzi, Pietro, Neri, Giovanni·2005·European Journal of Human Genetics

Abstract

The fragile X syndrome is caused by a >200 CGG repeat expansion within the FMR1 gene promoter, with consequent DNA hypermethylation and inactivation of its expression. To further clarify the mechanisms that suppress the activity of the mutant gene and the conditions that may permit its reactivation, we investigated the acetylation and methylation status of three different regions of the FMR1 gene (promoter, exon 1 and exon 16) of three fragile X cell lines, using a chromatin immunoprecipitation (ChIP) assay with antibodies against acetylated-H3/H4 histones and against dimethylated lysine residues K4 and K9 of histone H3 (H3-K4 and H3-K9). We then coupled the ChIP assay with real-time PCR, obtaining absolute quantification of immunoprecipitated chromatin. Basal levels of histone acetylation and H3-K4 methylation were much higher in transcriptionally active wild-type controls than in inactive fragile X cell lines. Treatment of fragile X cell lines with the DNA demethylating drug 5-aza-2-deoxycytidine (5-azadC), known to reactivate the FMR1 gene, induced a decrease of H3-K9 methylation, an increase of H3 and H4 acetylation and an increase of H3-K4 methylation. Treatment with acetyl-L-carnitine (ALC), a compound that reduces the in vitro expression of the FRAXA fragile site without affecting DNA methylation, caused an increase of H3 and H4 acetylation. However, H3-K4 methylation remained extremely low, in accordance with the observation that ALC alone does not reactivate the FMR1 gene. Our experiments indicate that H3-K4 methylation and DNA demethylation are the main epigenetic switches activating the expression of the FMR1 gene, with histone acetylation playing an ancillary role.

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Crossref · 10.1038/sj.ejhg.5201393

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  • Reactivation by 5-azadC was accompanied by DNA demethylation and changes in the epigenetic code of histones H3 and H4.

    “Reactivation was accompanied not only by DNA demethylation but also by changes in the epigenetic code of histones H3 and H4 (97).”

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Authors
Tabolacci, E., Pietrobono, R., Moscato, U., Oostra, B. A., Chiurazzi, P., & Neri, G.
Affiliations
  • Università Cattolica del Sacro Cuore (IT)
  • Erasmus MC (NL)
Corresponding author
Neri, Giovanni
Venue
European Journal of Human Genetics
Published
2005-03-02
Volume
13
Issue
5
Pages
641-648
ISSN
  • 1018-4813 (ISSN-L)
  • 1476-5438
OpenAlex
W1975105273
Cited by
92
References
27
Citations by year
2025: 3 · 2024: 5 · 2023: 1 · 2022: 2 · 2021: 2 · 2020: 1 · 2019: 4 · 2018: 5 · 2017: 2 · 2016: 13 · 2015: 3 · 2014: 6 · 2013: 9 · 2012: 4
FWCI
2.34
Type
journal article
Language
en
Open access
closed
Locations
  • European Journal of Human Genetics (publishedVersion)
  • PubMed (publishedVersion)
  • EUR Research Repository (Erasmus University Rotterdam) (publishedVersion)
  • EUR Research Repository (Erasmus University Rotterdam) (submittedVersion)
Funders
FRAXA Research Foundation
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Genetics and Neurodevelopmental Disorders
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Epigenetics and DNA Methylation
  • Life Sciences › Neuroscience › Cellular and Molecular Neuroscience › Genetic Neurodegenerative Diseases
Keywords
fragile X syndrome, FMR1 gene, CGG repeat expansion, DNA methylation, histone acetylation, histone H3 lysine 9 methylation, gene reactivation, decitabine, acetyl-L-carnitine, epigenetic silencing
MeSH terms
Decitabine, Acetylation, Acetylcarnitine, Azacitidine, Cell Line, Exons, Fragile X Syndrome, Histones, Humans, Male, Nerve Tissue Proteins, Promoter Regions, Genetic, Polymerase Chain Reaction, RNA-Binding Proteins, DNA Methylation, Epigenesis, Genetic, Chromatin Immunoprecipitation, Fragile X Messenger Ribonucleoprotein 1

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