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A defect in nucleosome remodeling prevents IL-12(p35) gene transcription in neonatal dendritic cells.

par Goriely, Stanislas ;Van Lint, Carine ;Dadkhah, Réza;Libin, Myriam ;De Wit, Dominique ;Demonte, Dominique ;Willems, Fabienne ;Goldman, Michel
Référence The Journal of experimental medicine, 199, 7, page (1011-1016)
Publication Publié, 2004

Article révisé par les pairs

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Résumé :

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.