Natural mutations in humans and introduced mutations in mice have unequivocally demonstrated the importance of interferon-gamma (IFN-gamma) for the control of tuberculosis (TB). How this cytokine exerts its protective effects is thought to owe much to the broad transcriptional programs it activates within Mycobacterium tuberculosis (Mto)-infected macrophages and dendritic cells. Here as many as 1,300 genes may be engaged. Prominent within this group is a new family of 47kDa guanosine 5'-triphosphatases (p47 GTPases) that confers host resistance to a number of human pathogens. At least one member of this family - LRG-47 - appears essential for combating TB in experimental mouse models. Preliminary evidence suggests that LRG-47 operates at the level of the infected cell via a mechanism distinct from all known tuberculocidal pathways, linking cytokine activation with phagolysomal fusion, events that are required for bacterial killing and which may enable Mtb antigens to be cross-presented. It is the purpose of this proposal to build on these initial observations by pursuing the following aims: (1) Characterize the intracellular location and trafficking behavior of mouse and human LRG-47 within Mtb-infected cells. Here a combination of high-resolution imaging and cell fractionation will be used to identify the LRG-47-positive compartment(s) and its recruitment to the nascent Mtb phagosome. (2) Define the molecular determinants of LRG-47 function in response to Mtb. Relocation of LRG-47 to the Mtb phagosome and subsequent remodeling of this organelle is likely to enlist other host proteins. Isolating LRG-47-interacting partners, the functional domains involved and their consequences for immunity will be dissected with an array of molecular, cellular and structural approaches. (3) Uncover Mtb-encoded pathways that counter LRG-47 - dependent immunity. Genetic screens conducted to identify bacterial components interfering with LRG-47 should yield further insights into how this GTPase operates. It could also uncover prospective drug targets. Information gleaned from these approaches will provide a paradigm for other members of the p47 GTPase family that is rapidly emerging as one of the most powerful host defense repertoires in the mammalian genome.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI068041-03
Application #
7470658
Study Section
Immunity and Host Defense Study Section (IHD)
Program Officer
Lacourciere, Karen A
Project Start
2006-07-01
Project End
2011-06-30
Budget Start
2008-07-01
Budget End
2009-06-30
Support Year
3
Fiscal Year
2008
Total Cost
$315,294
Indirect Cost
Name
Yale University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
043207562
City
New Haven
State
CT
Country
United States
Zip Code
06520
Kim, Bae-Hoon; Chee, Jonathan D; Bradfield, Clinton J et al. (2016) Interferon-induced guanylate-binding proteins in inflammasome activation and host defense. Nat Immunol 17:481-9
Gaudet, Ryan G; Bradfield, Clinton J; MacMicking, John D (2016) Evolution of Cell-Autonomous Effector Mechanisms in Macrophages versus Non-Immune Cells. Microbiol Spectr 4:
MacMicking, John D (2014) Cell-autonomous effector mechanisms against mycobacterium tuberculosis. Cold Spring Harb Perspect Med 4:
Das, Rituparna; Koo, Mi-Sun; Kim, Bae Hoon et al. (2013) Macrophage migration inhibitory factor (MIF) is a critical mediator of the innate immune response to Mycobacterium tuberculosis. Proc Natl Acad Sci U S A 110:E2997-3006
Randow, Felix; MacMicking, John D; James, Leo C (2013) Cellular self-defense: how cell-autonomous immunity protects against pathogens. Science 340:701-6
Selleck, Elizabeth M; Fentress, Sarah J; Beatty, Wandy L et al. (2013) Guanylate-binding protein 1 (Gbp1) contributes to cell-autonomous immunity against Toxoplasma gondii. PLoS Pathog 9:e1003320
MacMicking, John D (2012) Interferon-inducible effector mechanisms in cell-autonomous immunity. Nat Rev Immunol 12:367-82
Shenoy, Avinash R; Wellington, David A; Kumar, Pradeep et al. (2012) GBP5 promotes NLRP3 inflammasome assembly and immunity in mammals. Science 336:481-5
Bradfield, Clinton J; Kim, Bae-Hoon; MacMicking, John D (2012) Crossing the Rubicon: new roads lead to host defense. Cell Host Microbe 11:221-3
Kim, Bae-Hoon; Shenoy, Avinash R; Kumar, Pradeep et al. (2012) IFN-inducible GTPases in host cell defense. Cell Host Microbe 12:432-44

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