Here we have identified 'triple D' (3d), a recessive N-ethyl-N-nitrosourea-induced mutation and phenotype in which no signaling occurs via the intracellular Toll-like receptors 3, 7 and 9 (sensors for double-stranded RNA, single-stranded RNA and unmethylated DNA, respectively). The 3d mutation also prevented cross-presentation and diminished major histocompatibility complex class II presentation of exogenous antigen; it also caused hypersusceptibility to infection by mouse cytomegalovirus and other microbes. By positional identification, we found 3d to be a missense allele of Unc93b1, which encodes the 12-membrane-spanning protein UNC-93B, a highly conserved molecule found in the endoplasmic reticulum with multiple paralogs in mammals. Innate responses to nucleic acids and exogenous antigen presentation, which both initiate in endosomes, thus seem to depend on an endoplasmic reticulum–resident protein, which suggests communication between these organellar systems.
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We thank C.C. Scott (HSC), L. Yu (HSC) and A. Kiemer (University of California, San Diego) for help and advice. Supported by the National Institutes of Health, Canadian Institutes of Health Research, Uehara Memorial Foundation (K.T.) and Leukemia and Lymphoma Society (3248-05 to E.J.).
The authors declare no competing financial interests.
3d/3d mice are unable to contain Gram-positive S. aureus infection. (PDF 190 kb)
Coarse microsatellite mapping of the 3d locus. (PDF 25 kb)
Fine genetic mapping of 3d region. (PDF 24 kb)
SNPs and a novel microsatellite marker used to confine the 3d critical region. (PDF 28 kb)
Illustration of 3d critical region. (PDF 30 kb)
Alignment of the orthologous sequences from vertebrate and invertebrate species in the region of the mutation (boxed). (PDF 124 kb)
Optimal alignment (Clustal-W) between UNC-93A and UNC-93B proteins. (PDF 173 kb)
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Tabeta, K., Hoebe, K., Janssen, E. et al. The Unc93b1 mutation 3d disrupts exogenous antigen presentation and signaling via Toll-like receptors 3, 7 and 9. Nat Immunol 7, 156–164 (2006). https://doi.org/10.1038/ni1297
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