Unc93B1 biases Toll-like receptor responses to nucleic acid in dendritic cells toward DNA- but against RNA-sensing

Ryutaro Fukui, Shin Ichiroh Saitoh, Fumi Matsumoto, Hiroko Kozuka-Hata, Masaaki Oyama, Koichi Tabeta, Bruce Beutler, Kensuke Miyake

Research output: Contribution to journalArticle

126 Scopus citations

Abstract

Toll-like receptors (TLRs) 3, 7, and 9 recognize microbial nucleic acids in endolysosomes and initiate innate and adaptive immune responses. TLR7/9 in dendritic cells (DCs) also respond to self-derived RNA/DNA, respectively, and drive autoantibody production. Remarkably, TLR7 and 9 appear to have mutually opposing, pathogenic or protective, impacts on lupus nephritis in MRL/lpr mice. Little is known, however, about the contrasting relationship between TLR7 and 9. We show that TLR7 and 9 are inversely linked by Unc93B1, a multiple membrane-spanning endoplasmic reticulum (ER) protein. Complementation cloning with a TLR7-unresponsive but TLR9-responsive cell line revealed that amino acid D34 in Unc93B1 repressed TLR7-mediated responses. D34A mutation rendered Unc93B1-deficient DCs hyperresponsive to TLR7 ligand but hyporesponsive to TLR9 ligand, with TLR3 responses unaltered. Unc93B1 associates with and delivers TLR7/9 from the ER to endolysosomes for ligand recognition. The D34A mutation up-regulates Unc93B1 association with endogenous TLR7 in DCs, whereas Unc93B1 association with TLR9 was down-regulated by the D34A mutation. Consistently, the D34A mutation up-regulated ligand-induced trafficking of TLR7 but down-regulated that of TLR9. Collectively, TLR response to nucleic acids in DCs is biased toward DNA-sensing by Unc93B1.

Original languageEnglish (US)
Pages (from-to)1339-1350
Number of pages12
JournalJournal of Experimental Medicine
Volume206
Issue number6
DOIs
StatePublished - Jun 8 2009

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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