A point mutation in the amino terminus of TLR7 abolishes signaling without affecting ligand binding

Carlo Iavarone, Katrin Ramsauer, Andriy V. Kubarenko, Jason C. Debasitis, Igor Leykin, Alexander N R Weber, Owen M. Siggs, Bruce Beutler, Pu Zhang, Gillis Otten, Ugo D'Oro, Nicholas M. Valiante, M. Lamine Mbow, Alberto Visintin

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

TLR7 is the mammalian receptor for ssRNA and some nucleotide-like small molecules.We have generated a mouse by N-nitrose-N9- ethyl urea mutagenesis in which threonine 68 of TLR7 was substituted with isoleucine. Cells bearing this mutant TLR7 lost the sensitivity to the small-molecule TLR7 agonist resiquimod, hence the name TLR7rsq1. In this work, we report the characterization of this mutant protein. Similar to the wild-type counterpart, TLR7 rsq1 localizes to the endoplasmic reticulum and is expressed at normal levels in both primary cells and reconstituted 293T cells. In addition to small-molecule TLR7 agonists, TLR7rsq1 fails to be activated by ssRNA. Whole-transcriptome analysis demonstrates that TLR7 is the exclusive and indispensable receptor for both classes of ligands, consistent with the fact that both ligands induce highly similar transcriptional signatures in TLR7wt/wt splenocytes. Thus, TLR7rsq1 is a bona fide phenocopy of the TLR7 null mouse. Because TLR7rsq1 binds to ssRNA, our studies imply that the N-terminal portion of TLR7 triggers a yet to be identified event on TLR7. TLR7rsq1 mice might represent a valuable tool to help elucidate novel aspects of TLR7 biology.

Original languageEnglish (US)
Pages (from-to)4213-4222
Number of pages10
JournalJournal of Immunology
Volume186
Issue number7
DOIs
StatePublished - Apr 1 2011

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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    Iavarone, C., Ramsauer, K., Kubarenko, A. V., Debasitis, J. C., Leykin, I., Weber, A. N. R., Siggs, O. M., Beutler, B., Zhang, P., Otten, G., D'Oro, U., Valiante, N. M., Mbow, M. L., & Visintin, A. (2011). A point mutation in the amino terminus of TLR7 abolishes signaling without affecting ligand binding. Journal of Immunology, 186(7), 4213-4222. https://doi.org/10.4049/jimmunol.1003585