title: The 5' regulatory sequences of active miR-146a promoters are hypomethylated and associated with euchromatic histone modification marks in B lymphoid cells.
abstract: Although the microRNA miR-146a is an important regulator of immunological processes and contributes to the pathogenesis of certain B cell lymphoma types, in B cells the epigenetic regulation of miR-146a expresion has not been studied yet. To elucidate the mechanisms controlling miR-146a expression in B lymphoid cells we analysed epigenetic marks, including CpG methylation and histone modifications, at the miR-146a promoter in well characterized Epstein-Barr virus (EBV) positive and EBV negative B cell lines. In addition, EBV positive epithelial cell lines were also studied as controls. In cells with a silent miR-146a promoter the 5' regulatory sequences comprising a CpG island were devoid of activating histone modifications, independently of the methylation pattern of the regulatory region. The regulatory sequences flanking the inactive miR-146 promoter were hypermethylated at CpG dinucleotides in the EBV positive Burkitt's lymphoma (BL) cell lines of memory B cell phenotype (Rael and Akata), partially methylated in the mammary carcinoma cell lines C2G6 and C4A3, and completely unmethylated in the nasopharyngeal carcinoma cell line C666-1. In contrast, in EBV positive cell lines of activated B cell phenotype, and EBV negative BL cell lines the invariably unmethylated 5' regulatory sequences of active miR-146a promoters were enriched in the euchromatic histone modification marks acetylated histone H3, acetylated histone H4, and histone H3 dimethylated at lysine 4. The euchromatic histone modification marks extended over the immediate vicinity of the transcriptional initiation site to the 3' intron, too. We concluded that similarly to the promoters of protein coding genes, both DNA methylation and histone modifications contribute to the host cell dependent expression of miR-146a.
authors.affiliation: Microbiological Research Group, National Center for Epidemiology, Piheno ut 1, H-1529 Budapest, Hungary.
authors.forename: Kalman
authors.initials: K
authors.lastname: Szenthe
authors.forename: Anita
authors.initials: A
authors.lastname: Koroknai
authors.forename: Ferenc
authors.initials: F
authors.lastname: Banati
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Bathori
authors.forename: Rita
authors.initials: R
authors.lastname: Lozsa
authors.forename: Jozsef
authors.initials: J
authors.lastname: Burgyan
authors.forename: Hans
authors.initials: H
authors.lastname: Wolf
authors.forename: Daniel
authors.initials: D
authors.lastname: Salamon
authors.forename: Katalin
authors.initials: K
authors.lastname: Nagy
authors.forename: Hans Helmut
authors.initials: HH
authors.lastname: Niller
authors.forename: Janos
authors.initials: J
authors.lastname: Minarovits
mesh_terms: D024506:5' Flanking Region; D000107:Acetylation; D001402:B-Lymphocytes / Q000378:metabolism / Q000473:pathology / Q000821:virology*; D015415:Biomarkers / Q000378:metabolism; D015152:Blotting, Northern; D002051:Burkitt Lymphoma / Q000473:pathology / Q000821:virology; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D018899:CpG Islands; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D022041:Euchromatin / Q000235:genetics / Q000378:metabolism; D016679:Genome, Viral; D004854:Herpesvirus 4, Human / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity; D006657:Histones / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007438:Introns; D008239:Lysine / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D024363:Transcription Initiation Site; D017735:Virus Latency
chemical_list: D015415:Biomarkers; D022041:Euchromatin; D006657:Histones; C542542:MIRN146 microRNA, human; D035683:MicroRNAs; D008239:Lysine