application) Macrophages are central to maintenance of iron homeostasis, acting as a major iron storage site in the body (1-3). Iron is also a major factor in macrophage anti-microbial defense, acting as a catalyst in the generation of reactive hydroxyl radicals (4-6). The Nramp1 gene in mice (9-11) controls natural resistance to infection by a number of intracellular pathogens. The gene exists as two allelic forms that determine resistance or susceptibility to growth of these pathogens within macrophages during the early stages of infection. The protein is expressed in endocytic vesicles of macrophages that traffic to the phagosome. The susceptible allele differs from the resistant allele by a single glycine to aspartic acid substitution in the fourth transmembrane domain. Our laboratory has investigated the role of Nramp1 in macrophage antimicrobial activity and in iron metabolism. We have shown that Nramp1 transports iron into phagosomes where the iron serves to catalyze the Haber-Weiss reaction. The resulting production of reactive hydroxyl radical then inhibits the growth of the phagocytized bacteria. Our observations that Nramp serves as a regulator of antimicrobial activity by transporting iron into phagosomes serves as the basis of this application to determine the factors that regulate Nramp1 mediated iron transport.
Our specific aims are: 1. To determine regulation of Nramp1 mediated iron transport; 2. To determine if iron transport by Nramp1 requires protein phosphorylation and 3. To determine, by site directed mutagenesis, the domains within the Nramp1 protein that affect iron transport.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK057667-03
Application #
6517741
Study Section
Special Emphasis Panel (ZDK1-GRB-1 (J2))
Program Officer
Badman, David G
Project Start
2000-06-01
Project End
2005-04-30
Budget Start
2002-05-01
Budget End
2003-04-30
Support Year
3
Fiscal Year
2002
Total Cost
$280,092
Indirect Cost
Name
Ohio State University
Department
Microbiology/Immun/Virology
Type
Schools of Medicine
DUNS #
098987217
City
Columbus
State
OH
Country
United States
Zip Code
43210
Van Zandt, Kristopher E; Sow, Fatoumata B; Florence, William C et al. (2008) The iron export protein ferroportin 1 is differentially expressed in mouse macrophage populations and is present in the mycobacterial-containing phagosome. J Leukoc Biol 84:689-700
Sow, Fatoumata B; Florence, William C; Satoskar, Abhay R et al. (2007) Expression and localization of hepcidin in macrophages: a role in host defense against tuberculosis. J Leukoc Biol 82:934-45
Wang, Yue; Curry, Heather M; Zwilling, Bruce S et al. (2005) Mycobacteria inhibition of IFN-gamma induced HLA-DR gene expression by up-regulating histone deacetylation at the promoter region in human THP-1 monocytic cells. J Immunol 174:5687-94
Weatherby, Kelly E; Zwilling, Bruce S; Lafuse, William P (2003) Resistance of macrophages to Mycobacterium avium is induced by alpha2-adrenergic stimulation. Infect Immun 71:22-9
Wang, Tianyi; Lafuse, William P; Takeda, Kiyoshi et al. (2002) Rapid chromatin remodeling of Toll-like receptor 2 promoter during infection of macrophages with Mycobacterium avium. J Immunol 169:795-801
Lafuse, William P; Alvarez, Gail R; Zwilling, Bruce S (2002) Role of MAP kinase activation in Nramp1 mRNA stability in RAW264.7 macrophages expressing Nramp1(Gly169). Cell Immunol 215:195-206
Zhong, W; Lafuse, W P; Zwilling, B S (2001) Infection with Mycobacterium avium differentially regulates the expression of iron transport protein mRNA in murine peritoneal macrophages. Infect Immun 69:6618-24
Kuhn, D E; Lafuse, W P; Zwilling, B S (2001) Iron transport into mycobacterium avium-containing phagosomes from an Nramp1(Gly169)-transfected RAW264.7 macrophage cell line. J Leukoc Biol 69:43-9
Wang, T; Lafuse, W P; Zwilling, B S (2001) NFkappaB and Sp1 elements are necessary for maximal transcription of toll-like receptor 2 induced by Mycobacterium avium. J Immunol 167:6924-32