Interferon (IFN)-gamma is a prominent activator of pathways that effect host defense against intracellular pathogens, including many category A, B, and C biodefense priority pathogens. The Immunity-related GTPases (IRG;also known as p47 GTPases) are a family of IFN-gamma-induced proteins that play critical roles in resistance to intracellular bacteria and protozoa, including Salmonella typhimurium and Toxoplasma gondii. Mice lacking certain IRG proteins have crippled host defense against these pathogens;further, macrophages isolated from the IRG-deficient mice display defects in phagosome processing and intracellular killing, as well as in cellular motility. However, the underlying mechanisms are unknown. Based on our published and preliminary data, we hypothesize the following: Hypothesis 1. IRG proteins form complexes among themselves - both homotypic and heterotypic - that regulate phagosome processing and macrophage motility. Hypothesis 2. IRG proteins in the GMS subfamily play dominant roles as regulators of the IRG proteins in the GKS subfamily. GMS proteins complex with specific GKS proteins to prevent their degradation, enabling subsequent GKS protein assembly in homotypic complexes at sites of contact between lipid membranes and the actin cytoskeleton, impacting phagosome processing and cell motility. We will address these hypotheses with the following:
Aim 1. We will define homotypic and heterotypic IRG protein complexes that exist among specific GMS and GKS proteins in activated macrophages. We will determine the localization of the complexes, and the time frames in which they appear as related to cell motility and phagosome processing. We will determine the dependence on biochemical activity and protein domains on formation of the complexes.
Aim 2. We will define the role of IRG GMS proteins in regulating IRG GKS proteins, and in coordinating IRG protein-mediated host defense functions. We will determine the effect of GMS protein deficiency on regulating GKS protein levels. Where levels are altered, we will determine whether GMS proteins impact GKS expression at the level of transcription, translation, and/or protein stability. We will determine the effect of IRG GMS protein-deficiency on the creation of homotypic IRG GKS protein complexes on the phagosome, and on the plasma membrane at the leading edge of the migrating macrophages.

Public Health Relevance

This research will elucidate a fundamental mechanism that governs resistance to intracellular bacteria and protozoa. Our ultimate goals are the generation of broadly applicable therapeutic agents for human infectious disease and biodefense.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
Project #
Application #
Study Section
Immunity and Host Defense Study Section (IHD)
Program Officer
Gondre-Lewis, Timothy A
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Duke University
Internal Medicine/Medicine
Schools of Medicine
United States
Zip Code
Pilla-Moffett, Danielle; Barber, Matthew F; Taylor, Gregory A et al. (2016) Interferon-Inducible GTPases in Host Resistance, Inflammation and Disease. J Mol Biol 428:3495-513
Murray, Henry W; Mitchell-Flack, Marisa; Taylor, Gregory A et al. (2015) IFN-γ-induced macrophage antileishmanial mechanisms in mice: A role for immunity-related GTPases, Irgm1 and Irgm3, in Leishmania donovani infection in the liver. Exp Parasitol 157:103-9
Guo, Jintao; McQuillan, James A; Yau, Belinda et al. (2015) IRGM3 contributes to immunopathology and is required for differentiation of antigen-specific effector CD8+ T cells in experimental cerebral malaria. Infect Immun 83:1406-17
Henry, Stanley C; Schmidt, Elyse A; Fessler, Michael B et al. (2014) Palmitoylation of the immunity related GTPase, Irgm1: impact on membrane localization and ability to promote mitochondrial fission. PLoS One 9:e95021
Haldar, Arun K; Saka, Hector A; Piro, Anthony S et al. (2013) IRG and GBP host resistance factors target aberrant, ""non-self"" vacuoles characterized by the missing of ""self"" IRGM proteins. PLoS Pathog 9:e1003414
Springer, Helen M; Schramm, Michael; Taylor, Gregory A et al. (2013) Irgm1 (LRG-47), a regulator of cell-autonomous immunity, does not localize to mycobacterial or listerial phagosomes in IFN-γ-induced mouse cells. J Immunol 191:1765-74
Liu, Bo; Gulati, Ajay S; Cantillana, Viviana et al. (2013) Irgm1-deficient mice exhibit Paneth cell abnormalities and increased susceptibility to acute intestinal inflammation. Am J Physiol Gastrointest Liver Physiol 305:G573-84
Klionsky, Daniel J (author list too long to display - see original citation for additional authors) (2012) Guidelines for the use and interpretation of assays for monitoring autophagy. Autophagy 8:445-544
Liu, Zhen; Zhang, Huifang M; Yuan, Ji et al. (2012) The immunity-related GTPase Irgm3 relieves endoplasmic reticulum stress response during coxsackievirus B3 infection via a PI3K/Akt dependent pathway. Cell Microbiol 14:133-46
Skariah, Sini; Bednarczyk, Robert B; McIntyre, Matthew K et al. (2012) Discovery of a novel Toxoplasma gondii conoid-associated protein important for parasite resistance to reactive nitrogen intermediates. J Immunol 188:3404-15

Showing the most recent 10 out of 32 publications