title: A defect in nucleosome remodeling prevents IL-12(p35) gene transcription in neonatal dendritic cells.
abstract: To gain insight into the inability of newborns to mount efficient Th1 responses, we analyzed the molecular basis of defective IL-12(p35) expression in human neonatal monocyte-derived dendritic cells (DCs). Determination of IL-12(p35) pre-mRNA levels by real-time RT-PCR revealed that transcriptional activation of the gene in lipopolysaccharide-stimulated neonatal DCs was strongly impaired compared with adult DCs. We next showed that p50/p65 and p65/p65 dimers interact with kB#1 site, a critical cis-acting element of the IL-12(p35) promoter. We found that LPS-induced p65 activation was similar in adult and newborn DCs. Likewise, in vitro binding activity to the Sp1#1 site, previously shown to be critical for IL-12(p35) gene activation, did not differ in adults and newborns. Since the accessibility to this Sp1#1 site was found to depend on nucleosome remodeling, we used a chromatin accessibility assay to compare remodeling of the relevant nucleosome (nuc-2) in adult and neonatal DCs. We observed that nuc-2 remodeling in neonatal DCs was profoundly impaired in response to lipopolysaccharide. Both nuc-2 remodeling and IL-12(p35) gene transcription were restored upon addition of recombinant interferon-gamma. We conclude that IL-12(p35) transcriptional repression in neonatal DCs takes place at the chromatin level.
authors.affiliation: Laboratoire d'Immunologie Expérimentale, Université Libre de Bruxelles, Bruxelles et Institut d'Immunologie Médicale, Gosselies, Belgium.
authors.forename: Stanislas
authors.initials: S
authors.lastname: Goriely
authors.forename: Carine
authors.initials: C
authors.lastname: Van Lint
authors.forename: Réza
authors.initials: R
authors.lastname: Dadkhah
authors.forename: Myriam
authors.initials: M
authors.lastname: Libin
authors.forename: Dominique
authors.initials: D
authors.lastname: De Wit
authors.forename: Dominique
authors.initials: D
authors.lastname: Demonté
authors.forename: Fabienne
authors.initials: F
authors.lastname: Willems
authors.forename: Michel
authors.initials: M
authors.lastname: Goldman
mesh_terms: D000328:Adult; D001483:Base Sequence; D042002:Chromatin Assembly and Disassembly / Q000187:drug effects; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D007231:Infant, Newborn; D007371:Interferon-gamma / Q000494:pharmacology; D018664:Interleukin-12 / Q000235:genetics*; D053765:Interleukin-12 Subunit p35; D008070:Lipopolysaccharides / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism; D009707:Nucleosomes / Q000187:drug effects / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics*; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins; D016329:Sp1 Transcription Factor / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: C508858:IL12A protein, human; D053765:Interleukin-12 Subunit p35; D008070:Lipopolysaccharides; D016328:NF-kappa B; D009707:Nucleosomes; D021122:Protein Subunits; D012322:RNA Precursors; D011994:Recombinant Proteins; D016329:Sp1 Transcription Factor; D018664:Interleukin-12; D007371:Interferon-gamma