title: Synergistic effect of histone hyperacetylation and DNA demethylation in the reactivation of the FMR1 gene.
abstract: Most fragile X syndrome patients have expansion of a (CGG)(n)sequence with >200 repeats (full mutation) in the FMR1 gene responsible for this condition. Hypermethylation of the expanded repeat and of the FMR1 promoter is almost always present and apparently suppresses transcription, resulting in absence of the FMR1 protein. We recently showed that transcriptional reactivation of FMR1 full mutations can be achieved by inducing DNA demethylation with 5-azadeoxycytidine (5-azadC). The level of histone acetylation is another important factor in regulating gene expression; therefore, we treated lymphoblastoid cell lines of non-mosaic full mutation patients with three drugs capable of inducing histone hyperacetylation. We observed a consistent, although modest, reactivation of the FMR1 gene with 4-phenylbutyrate, sodium butyrate and trichostatin A, as shown by RT-PCR. However, we report that combining these drugs with 5-azadC results in a 2- to 5-fold increase in FMR1 mRNA levels obtained with 5-azadC alone, thus showing a marked synergistic effect of histone hyperacetylation and DNA demethylation in the reactivation of FMR1 full mutations.
authors.affiliation: Istituto di Genetica Medica, Università Cattolica and Centro Ricerche per la Disabilità Mentale e Motoria, Associazione Anni Verdi, Largo F. Vito 1, 00168 Rome, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Chiurazzi
authors.forename: M G
authors.initials: MG
authors.lastname: Pomponi
authors.forename: R
authors.initials: R
authors.lastname: Pietrobono
authors.forename: C E
authors.initials: CE
authors.lastname: Bakker
authors.forename: G
authors.initials: G
authors.lastname: Neri
authors.forename: B A
authors.initials: BA
authors.lastname: Oostra
mesh_terms: D000107:Acetylation; D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D001483:Base Sequence; D002460:Cell Line; D019175:DNA Methylation; D017931:DNA Primers; D000077209:Decitabine; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051860:Fragile X Messenger Ribonucleoprotein 1; D005600:Fragile X Syndrome / Q000235:genetics*; D056572:Histone Deacetylase Inhibitors; D006657:Histones / Q000378:metabolism*; D006801:Humans; D008297:Male; D009419:Nerve Tissue Proteins / Q000235:genetics*; D016601:RNA-Binding Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D001374:Azacitidine; D017931:DNA Primers; D000077209:Decitabine; D004791:Enzyme Inhibitors; D051860:Fragile X Messenger Ribonucleoprotein 1; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; C497683:FMR1 protein, human