Mycobacterium tuberculosis (Mtb) is the causative agent of what remains one of the most insidious and invasive of human infections, responsible for up to 2 million deaths per year. For most of the course of disease the basic unit of infection is the infected macrophage, therefore the interplay between these two cell types plays a crucial role in determining the outcome of infection. The project details the identification of host environmental cues and bacterial responses that enable the bacterium to invade and survive within the host cell. Genes up-regulated during infection will be exploited to construct fluorescent reporter Mtb strains that express GFP under defined conditions. These reporter strains will be used for both genetic and chemical screens to dissect out the signaling networks and to identify small molecular inhibitors that will form the foundation of a novel drug discovery program. The central hypothesis is that Mtb relies on environmental cues inside its host cell to activate genetic networks to enable it to adapt and survive, and that genetic or chemical interference with these networks will lead to death of the infecting bacteria.
The Specific Aims are as follows: 1. Identification of genetic "networks" activated by intracellular infection. Focuses on the identification of intracellular cues that trigger transcriptional activity in Mtb and the construction of reporter strains that express GFP under the regulation of promoters from those genes up- regulated in response to the environmental cue. 2. Exploitation of genetic screens to identify and delineate regulatory networks. These synthetic phenotypes will be utilized to screen for mutants with aberrant regulation of GFP expression. Such a screen will encompass the sensor/regulator machinery including transcriptional control and feedback loops. The phenotypes of these mutants will be probed in tissue culture and animal models of infection to identify those networks most critical to infection of the host. 3. Exploitation of chemical screens to identify small molecule inhibitors of these networks. High-throughput screens will be conducted on the reporter strains to identify small molecule inhibitors that modulate GFP expression. These hits will be analyzed for their activity against Mtb in macrophages and, in collaboration with Vertex Pharmaceuticals, used as lead compounds for novel target identification and drug development.
Tuberculosis remains a serious global problem with the majority of deaths in poor countries. We have no effective vaccines and constant problems with emerging drug resistance. The central premise of this current proposal is that Mtb up-regulates genetic networks to support intracellular survival and that genetic and chemical screens against these sensor/regulator networks will lead to the identification of novel drug targets and lead compounds.
|Sukumar, Neelima; Tan, Shumin; Aldridge, Bree B et al. (2014) Exploitation of Mycobacterium tuberculosis reporter strains to probe the impact of vaccination at sites of infection. PLoS Pathog 10:e1004394|
|Podinovskaia, Maria; Lee, Wonsik; Caldwell, Shannon et al. (2013) Infection of macrophages with Mycobacterium tuberculosis induces global modifications to phagosomal function. Cell Microbiol 15:843-59|
|Lee, Wonsik; VanderVen, Brian C; Fahey, Ruth J et al. (2013) Intracellular Mycobacterium tuberculosis exploits host-derived fatty acids to limit metabolic stress. J Biol Chem 288:6788-800|
|Tan, Shumin; Sukumar, Neelima; Abramovitch, Robert B et al. (2013) Mycobacterium tuberculosis responds to chloride and pH as synergistic cues to the immune status of its host cell. PLoS Pathog 9:e1003282|
|Russell, David G (2013) The evolutionary pressures that have molded Mycobacterium tuberculosis into an infectious adjuvant. Curr Opin Microbiol 16:78-84|
|Thomas, Suzanne T; VanderVen, Brian C; Sherman, David R et al. (2011) Pathway profiling in Mycobacterium tuberculosis: elucidation of cholesterol-derived catabolite and enzymes that catalyze its metabolism. J Biol Chem 286:43668-78|
|Russell, David G (2011) Mycobacterium tuberculosis and the intimate discourse of a chronic infection. Immunol Rev 240:252-68|
|Abramovitch, Robert B; Rohde, Kyle H; Hsu, Fong-Fu et al. (2011) aprABC: a Mycobacterium tuberculosis complex-specific locus that modulates pH-driven adaptation to the macrophage phagosome. Mol Microbiol 80:678-94|
|Russell, David G (2011) The galvanizing of Mycobacterium tuberculosis: an antimicrobial mechanism. Cell Host Microbe 10:181-3|
|Russell, David G; Barry 3rd, Clifton E; Flynn, JoAnne L (2010) Tuberculosis: what we don't know can, and does, hurt us. Science 328:852-6|
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