: Aspergillus fumigatus is an opportunistic fungal pathogen that causes severe and often fatal infections in patients with depressed immunity. Although the incidence of invasive aspergillosis is continuing to rise, reflecting the increased population of immunosuppressed patients, there are only a few antifungal agents available for treatment and their efficacy is severely hampered by problems with toxicity and drug resistance. Since most patients will die from aspergillosis despite having received treatment, there is an urgent need for the development of new drugs to treat this disease. In this grant we are proposing that nucleolar proteins are important considerations for novel therapeutic targets because of their potent effects on protein synthesis. Our preliminary data has identified a conserved fungal-specific nucleolar protein that is essential for growth in S. cerevisiae, and we are proposing to test the hypothesis that the A. fumigatus ortholog, AfcgrA, defines a pathway of nucleolar function that would be an effective new target for therapy. The goal of Aim I is to use AfcgrA-deficient mutants of A. fumigatus to model the therapeutic efficacy of a putative nucleolus-targeting drug. The AfcgrA gene will be disrupted by gene targeting approaches and the extent to which the mutant alleles impair the rate of disease progression or pattern of tissue dissemination will be compared in two in vivo models of aspergillosis. The goal of Aim II is to acquire information on AfcgrA interactions that will facilitate future application of structure-based drug design to the identification of AfcgrA inhibitors. We will use the yeast two-hybrid system to identify the molecular partners of AfcgrA, and gain insight into the structural requirements for these interactions by determining the domain organization of AfcgrA with circular dichroism spectroscopy. The goal of Aim III is to determine the regions of AfcgrA that specify nucleolar localization. We propose to define these sequences, anticipating that an understanding of the mechanism used to localize AfcgrA could be exploited in the design of selective inhibitors of this transport process.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI048746-02
Application #
6621796
Study Section
Special Emphasis Panel (ZRG1-BM-1 (05))
Program Officer
Duncan, Rory A
Project Start
2002-02-15
Project End
2005-01-31
Budget Start
2003-02-01
Budget End
2004-01-31
Support Year
2
Fiscal Year
2003
Total Cost
$225,497
Indirect Cost
Name
University of Cincinnati
Department
Pathology
Type
Schools of Medicine
DUNS #
041064767
City
Cincinnati
State
OH
Country
United States
Zip Code
45221
Bhabhra, Ruchi; Richie, Daryl L; Kim, H Stanley et al. (2008) Impaired ribosome biogenesis disrupts the integration between morphogenesis and nuclear duplication during the germination of Aspergillus fumigatus. Eukaryot Cell 7:575-83
Bhabhra, Ruchi; Zhao, Wei; Rhodes, Judith C et al. (2006) Nucleolar localization of Aspergillus fumigatus CgrA is temperature-dependent. Fungal Genet Biol 43:1-7
Fortwendel, Jarrod R; Zhao, Wei; Bhabhra, Ruchi et al. (2005) A fungus-specific ras homolog contributes to the hyphal growth and virulence of Aspergillus fumigatus. Eukaryot Cell 4:1982-9
Fortwendel, Jarrod R; Panepinto, John C; Seitz, Amy E et al. (2004) Aspergillus fumigatus rasA and rasB regulate the timing and morphology of asexual development. Fungal Genet Biol 41:129-39
Bhabhra, Ruchi; Miley, Michael D; Mylonakis, Eleftherios et al. (2004) Disruption of the Aspergillus fumigatus gene encoding nucleolar protein CgrA impairs thermotolerant growth and reduces virulence. Infect Immun 72:4731-40
Panepinto, John C; Oliver, Brian G; Fortwendel, Jarrod R et al. (2003) Deletion of the Aspergillus fumigatus gene encoding the Ras-related protein RhbA reduces virulence in a model of Invasive pulmonary aspergillosis. Infect Immun 71:2819-26