Mycobacterium avium has emerged as a major opportunistic pathogen in AIDS patients. M.avium normally resides within the vacuolar compartment of the macrophage where it restricts access to the digestive and processing capabilities of the host cell. Access appears to be restricted by impaired membrane protein trafficking into and out of the M.avium and M.tuberculosis phagosome. Because of this and the similarity of intracellular M.avium to M.tuberculosis, M.avium may provide an ideal organism to investigate fundamental mechanism of protein traffic in mononuclear phagocytes. Newly formed phagosomes fuse and exchange membrane with multiple intracellular compartments including lysosomes and that the exchange of such proteins is critical to intracellular killing. We have developed methods to reconstitute phagosome fusion events in vitro and we have begun to identify the factors that are required for phagosome membrane traffic. Among the proteins that are likely to play structural and regulatory roles in phagosome membrane trafficking are the GTP binding proteins (Heterotrimeric G proteins, Rab GTP binding proteins and ADP- ribosylation factors-ARFs ) and the newly described SNARE docking proteins (i.e., receptors for the NEM-sensitive fusion protein ). Our initial experiments have successfully reconstituted the in vitro fusion of early phagosomes with endosomes. We propose to exploit the in vitro assay to determine the biochemical requirements for fusion of endosomes with phagosomes isolated from normal macrophages and from macrophages infected with M.avium. Our initial effort is to identify key GTP-binding proteins and SNARE docking proteins that mediate protein trafficking into and out of normal and M.avium phagosomes. Using membranes and cytosol from M.avium infected cells, we will investigate possible inhibitors produced by the organism. In our initial experiments we have begun to catalogue the biochemical changes occurring in phagosomal membranes during phagosome maturation. We propose to develop in vitro assays to reconstitute fusion of phagosomes with vesicles derived from the trans-Golgi Network and with lysosomes and to use these assays to determine whether products of M.avium intracellular infection impair membrane transport. Lastly, we will utilize in vitro assays using Mycobacterium avium to determine the influence of the live organism on the fusion of phagosomes with endosomes, vesicles derived from the trans Golgi Network and lysosomes.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI035884-02
Application #
2071846
Study Section
Special Emphasis Panel (SRC (83))
Project Start
1994-05-01
Project End
1999-01-31
Budget Start
1995-02-01
Budget End
1996-01-31
Support Year
2
Fiscal Year
1995
Total Cost
Indirect Cost
Name
Washington University
Department
Physiology
Type
Schools of Medicine
DUNS #
062761671
City
Saint Louis
State
MO
Country
United States
Zip Code
63130
Barbieri, M A; Ramkumar, T P; Fernadez-Pol, S et al. (2004) Receptor tyrosine kinase signaling and trafficking--paradigms revisited. Curr Top Microbiol Immunol 286:1-20
Barbieri, M Alejandro; Fernandez-Pol, Sebastian; Hunker, Christine et al. (2004) Role of rab5 in EGF receptor-mediated signal transduction. Eur J Cell Biol 83:305-14
Hodzic, Didier M; Yeater, David B; Bengtsson, Luiza et al. (2004) Sun2 is a novel mammalian inner nuclear membrane protein. J Biol Chem 279:25805-12
Barbieri, M Alejandro; Kong, Chen; Chen, Pin-I et al. (2003) The SRC homology 2 domain of Rin1 mediates its binding to the epidermal growth factor receptor and regulates receptor endocytosis. J Biol Chem 278:32027-36
Cordero, Julia B; Cozzolino, Mario; Lu, Yan et al. (2002) 1,25-Dihydroxyvitamin D down-regulates cell membrane growth- and nuclear growth-promoting signals by the epidermal growth factor receptor. J Biol Chem 277:38965-71
Wilkowsky, S E; Barbieri, M A; Stahl, P D et al. (2002) Regulation of Trypanosoma cruzi invasion of nonphagocytic cells by the endocytically active GTPases dynamin, Rab5, and Rab7. Biochem Biophys Res Commun 291:516-21
Barbieri, M A; Heath, C M; Peters, E M et al. (2001) Phosphatidylinositol-4-phosphate 5-kinase-1beta is essential for epidermal growth factor receptor-mediated endocytosis. J Biol Chem 276:47212-6
Tall, G G; Barbieri, M A; Stahl, P D et al. (2001) Ras-activated endocytosis is mediated by the Rab5 guanine nucleotide exchange activity of RIN1. Dev Cell 1:73-82
Barbieri, M A; Gumusboga, A; Roberts, R L et al. (2001) Measurement of Rab5 protein kinase B/akt and regulation of ras-activated endocytosis. Methods Enzymol 329:145-56
Ricard, C S; Jakubowski, J M; Verbsky, J W et al. (2001) Drosophila rab GDI mutants disrupt development but have normal Rab membrane extraction. Genesis 31:17-29

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