RRC ID 5574
Author Benson SA, Ernst JD.
Title TLR2-dependent inhibition of macrophage responses to IFN-gamma is mediated by distinct, gene-specific mechanisms.
Journal PLoS ONE
Abstract Mycobacterium tuberculosis uses multiple mechanisms to avoid elimination by the immune system. We have previously shown that M. tuberculosis can inhibit selected macrophage responses to IFN-gamma through TLR2-dependent and -independent mechanisms. To specifically address the role of TLR2 signaling in mediating this inhibition, we stimulated macrophages with the specific TLR2/1 ligand Pam(3)CSK(4) and assayed responses to IFN-gamma. Pam(3)CSK(4) stimulation prior to IFN-gamma inhibited transcription of the unrelated IFN-gamma-inducible genes, CIITA and CXCL11. Surface expression of MHC class II and secretion of CXCL11 were greatly reduced as well, indicating that the reduction in transcripts had downstream effects. Inhibition of both genes required new protein synthesis. Using chromatin immunoprecipitation, we found that TLR2 stimulation inhibited IFN-gamma-induced RNA polymerase II binding to the CIITA and CXCL11 promoters. Furthermore, TATA binding protein was unable to bind the TATA box of the CXCL11 promoter, suggesting that assembly of transcriptional machinery was disrupted. However, TLR2 stimulation affected chromatin modifications differently at each of the inhibited promoters. Histone H3 and H4 acetylation was reduced at the CIITA promoter but unaffected at the CXCL11 promoter. In addition, NF-kappaB signaling was required for inhibition of CXCL11 transcription, but not for inhibition of CIITA. Taken together, these results indicate that TLR2-dependent inhibition of IFN-gamma-induced gene expression is mediated by distinct, gene-specific mechanisms that disrupt binding of the transcriptional machinery to the promoters.
Volume 4(7)
Pages e6329
Published 2009-7-24
DOI 10.1371/journal.pone.0006329
PMID 19629181
PMC PMC2710511
MeSH Animals Base Sequence Chemokine CXCL11 / genetics Chromatin Immunoprecipitation DNA Primers Enzyme-Linked Immunosorbent Assay Flow Cytometry Interferon-gamma / physiology* Macrophages / physiology* Mice Mice, Inbred BALB C Mice, Inbred C57BL Nuclear Proteins / genetics Promoter Regions, Genetic RNA Polymerase II / metabolism Toll-Like Receptor 2 / physiology* Trans-Activators / genetics
IF 2.766
Times Cited 11
Mice Nrf2 knockout mouse/C57BL6J