This proposal is Project 2 within a P01 renewal, entitled """"""""Intracellular pathogens and innate immunity"""""""". M. tuberculosis is an important human pathogen that causes severe morbidity and mortality around the world. The goal of the previous proposal was to identify the mechanisms by which M. tuberculosis triggers and manipulates host responses of its primary host cell, the macrophage. We made the striking discovery that M. tuberculosis, a phagosomal pathogen, activates the host cytosolic surveillance pathway (CSP), an innate signaling pathway that senses bacterial molecules in the cytoplasm. We are interested in host and bacterial factors required for CSP activation, and in elucidating the functional role of the pathway in M. tuberculosis pathogenesis. We have shown that the ESX-1 secretion pathway and the cell wall lipid PDIM are critical for perturbing phagosomal membranes of macrophages, allowing activation of cytosolic DNA receptors. Unexpectedly, cytosolic access also targets bacteria to the autophagy pathway. We hypothesize that intracellular pathogens perturb intracellular membranes to promote virulence, but activation of the CSP allows host cells to discriminate and mount qualitatively different immune responses to pathogens versus non-pathogens.
In Aim 1, we propose to elucidate the mechanism by which M. tuberculosis gains access to the cytosol and activates the CSP, building upon our evidence that a single ESX-1 substrate, ESAT-6, functions to permeabilize the phagosomal membrane. We propose to identify the nature of the DNA that is recognized by the host, test the role of putative host receptors responsible for CSP activation, and probe the role of cytosolic signaling in M. tuberculosis infection.
In Aim 2, we will examine how cytosolic access leads to targeting of M. tuberculosis to the autophagy pathway. In particular, we will test the role of ubiquitination and ubiquitin-binding adapters in targeting of autophagic vesicles to M. tuberculosis during infection. In the final Aim, We will collaborate extensively with the Portnoy (Project 1) and Vance (Project 3) groups to screen for modulators of M. tuberculosis growth and host innate responses by carrying out a screen in macrophages isolated from ENU mutagenized mice, and by performing an RNAi screen in macrophages.

Public Health Relevance

We recently discovered that M. tuberculosis utilizes its specialized secretion system to stimulate a robust host response leading to the production of interferon. The interferon response signature has recently been identified as a strong correlate of active disease in humans, thus these studies may impact the development of diagnostics and therapeutics that protect against tuberculosis.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Program Projects (P01)
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Special Emphasis Panel (ZAI1-QV-I)
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University of California Berkeley
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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
Burke, Thomas P; Portnoy, Daniel A (2016) SpoVG Is a Conserved RNA-Binding Protein That Regulates Listeria monocytogenes Lysozyme Resistance, Virulence, and Swarming Motility. MBio 7:e00240
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
Mitchell, Gabriel; Chen, Chen; Portnoy, Daniel A (2016) Strategies Used by Bacteria to Grow in Macrophages. Microbiol Spectr 4:
Sanman, Laura E; Qian, Yu; Eisele, Nicholas A et al. (2016) Disruption of glycolytic flux is a signal for inflammasome signaling and pyroptotic cell death. Elife 5:e13663
Rauch, Isabella; Tenthorey, Jeannette L; Nichols, Randilea D et al. (2016) NAIP proteins are required for cytosolic detection of specific bacterial ligands in vivo. J Exp Med 213:657-65
Mitchell, Gabriel; Ge, Liang; Huang, Qiongying et al. (2015) Avoidance of autophagy mediated by PlcA or ActA is required for Listeria monocytogenes growth in macrophages. Infect Immun 83:2175-84
Coady, Alison; Sil, Anita (2015) MyD88-dependent signaling drives host survival and early cytokine production during Histoplasma capsulatum infection. Infect Immun 83:1265-75
McKay, Susannah L; Portnoy, Daniel A (2015) Ribosome hibernation facilitates tolerance of stationary-phase bacteria to aminoglycosides. Antimicrob Agents Chemother 59:6992-9
Siegrist, M Sloan; Aditham, Arjun K; Espaillat, Akbar et al. (2015) Host actin polymerization tunes the cell division cycle of an intracellular pathogen. Cell Rep 11:499-507

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