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-γ. We conclude that IL-12(p35) transcriptional repression in neonatal DCs takes place at the chromatin level.

Perinatal Activation of the Interleukin-33 Pathway Promotes Type 2 Immunity in the Developing Lung

“…Reduced IL-12p70 synthesis in cord blood moDCs has been associated with impaired chromatin remodeling in the IL-12p35 promotor region, suggesting epigenetic regulation of gene transcription (Goriely et al, 2004). Here we identified an additional extrinsic cause for IL-12p35 deficiency in neonatal DCs.…”

Preferential production of the IL‐12(p40)/IL‐23(p19) heterodimer by dendritic cells from human newborns

“…We previously demonstrated that neonatal DC present a defect in IL-12(p35) expression. This deficient IL-12(p35) gene expression is associated with specific epigenetic phenomenons, involving impaired nucleosome remodeling [12]. More recently, we observed that interferon regulatory factor (IRF)-3 is essential for TLR-4-induced IL-12(p35) synthesis and that human newborns present a decreased activation of this transcription factor (V. Albarani et al, manuscript in preparation).…”

Inhibition of phosphoinositide 3-kinase enhances TRIF-dependent NF-κB activation and IFN-β synthesis downstream of Toll-like receptor 3 and 4

“…Assessment of NF-jB, or IRF3 binding activities in nuclear extracts by Trans-AM p65/RelA, p50, c-Rel or IRF3 transcription factor assay kits (Active Motif Europe, Rixensart, Belgium) was described earlier [47]. Briefly, 5 lg nuclear extract from each sample was incubated in plate-coated with consensus NF-jB or ISRE oligonucleotides.…”