At least four members of the Toll-like receptor (TLR) family recognize some form of nucleic acid. For this strategy of microbial detection to be effective, the immune system must reliably discriminate between self and microbial nucleic acids. Failure to do so can result in autoimmune or auto inflammatory disease. An important aspect of this balance appears to be the intracellular sequestration of TLR9 and TLR7 in endolysosomal compartments. This proposal is the revision of a renewal submission of a grant examining how the cell biology (i.e., localization and trafficking) of TLR9 and TLR7 is regulated and how this regulation contributes to self/non-self-discrimination. In the previous funding period we made three important contributions to this area of research. First, we defined the route of trafficking by which nucleic acid sensing TLRs exit the endoplasmic reticulum and transit to the endolysosome. Second, we described a surprising requirement for ectodomain proteolysis in the activation of TLR9, TLR7, and TLR3. Third, we used a TLR9 mutant to demonstrate the importance of localization and proteolytic regulation in self/non-self-discrimination. Overall, thi work transformed the model for TLR trafficking and regulation and convincingly demonstrated that studying these questions has relevance for self/non-self-discrimination. In this renewal application, we propose to extend these studies to primary cells and in vivo models.
In Aim 1, we will use TLR9-HA knock-in mice to study the trafficking and processing of TLR9 expressed at endogenous levels in a range of cell types.
In Aim 2, we will determine how Unc93b1 controls the trafficking of endosomal TLRs.
In Aim 3, we will use knock-in mice with an inducible allele of a TLR9 mutant that fails to maintain tolerance to self-nucleic acid. These mice will be used to explore the cell types and triggers required for breaking tolerance to self-nucleic acid.

Public Health Relevance

An inappropriate response to self DNA and RNA by innate immune receptors can lead to fatal autoimmune and auto inflammatory diseases, such as systemic lupus erythematous and rheumatoid arthritis. This proposal seeks to understand the mechanisms that normally prevent immune receptors from responding to self DNA and RNA.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI072429-07
Application #
8604666
Study Section
Cellular and Molecular Immunology - A Study Section (CMIA)
Program Officer
Johnson, David R
Project Start
2006-09-01
Project End
2018-01-31
Budget Start
2014-02-01
Budget End
2015-01-31
Support Year
7
Fiscal Year
2014
Total Cost
$352,125
Indirect Cost
$127,125
Name
University of California Berkeley
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
124726725
City
Berkeley
State
CA
Country
United States
Zip Code
94704
Koch, Meghan A; Reiner, Gabrielle L; Lugo, Kyler A et al. (2016) Maternal IgG and IgA Antibodies Dampen Mucosal T Helper Cell Responses in Early Life. Cell 165:827-41
Majer, Olivia; Liu, Bo; Barton, Gregory M (2016) Nucleic acid-sensing TLRs: trafficking and regulation. Curr Opin Immunol 44:26-33
Newman, Zachary R; Young, Janet M; Ingolia, Nicholas T et al. (2016) Differences in codon bias and GC content contribute to the balanced expression of TLR7 and TLR9. Proc Natl Acad Sci U S A 113:E1362-71
Sivick, Kelsey E; Arpaia, Nicholas; Reiner, Gabrielle L et al. (2014) Toll-like receptor-deficient mice reveal how innate immune signaling influences Salmonella virulence strategies. Cell Host Microbe 15:203-13
Lee, Bettina L; Barton, Gregory M (2014) Trafficking of endosomal Toll-like receptors. Trends Cell Biol 24:360-9
Kagan, Jonathan C; Barton, Gregory M (2014) Emerging principles governing signal transduction by pattern-recognition receptors. Cold Spring Harb Perspect Biol 7:a016253
Lee, Bettina L; Moon, Joanne E; Shu, Jeffrey H et al. (2013) UNC93B1 mediates differential trafficking of endosomal TLRs. Elife 2:e00291
Deguine, Jacques; Lee, Bettina L; Newman, Zachary R et al. (2013) No antigen-presentation defect in Unc93b1(3d/3d) (3d) mice. Nat Immunol 14:1101-2
Chiang, Chih-Yuan; Engel, Alex; Opaluch, Amanda M et al. (2012) Cofactors required for TLR7- and TLR9-dependent innate immune responses. Cell Host Microbe 11:306-18
Ewald, Sarah E; Barton, Gregory M (2011) Nucleic acid sensing Toll-like receptors in autoimmunity. Curr Opin Immunol 23:3-9

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