Shortly after protozoan parasites enter cells they undergo profound morphological changes, including restructuring of entire organelles and the cytoskeleton. These massive modifications must include selective proteolysis of cytoplasmic components. In eukaryotic cells most cytoplasmic proteins are degraded in proteasomes, highly conserved organelles found in humans, archaebacteria, plants and yeast. Proteasomes have various functions, including the degradation of regulatory proteins, thus providing a mechanism for rapidly switching cellular programs. Lactacystin, a microbial metabolite isolated from cultured broth of Streptomyces sp., is a specific and irreversible inhibitor of proteasomes. It inhibits the transformation of trypomastigotes of Trypanosoma cruzi into amastigote-like organisms, the transformation of malaria sporozoites into liver stages and encystation of Entamoeba. We propose: 1) to study the roles of proteasomes and lysosomes in remodeling of T. Cruzi; 2) to determine the main site(s) of degradation of the parasite's short and long -lived proteins; 3) to develop a cell-free system to study the ATP-proteasome- dependent pathway in T. Cruzi; 4) to document the activation of the ubiquitin (Ub)- proteasome pathway during parasite remodeling; 5) to determine at the ultrastructural level the localization of proteasomes in the parasites, and verify if they are associated with the cytoskelleton. 6) to clone some alpha and beta subunits of T. Cruzi proteasomes; and 7) to study the effect of lactacystin in the infection and development of T. Cruzi in mammalian cells. The long-term objective of this proposal is to clarify the mechanisms involved in the proteasome-dependent, stage-specific transformation of parasites during their life cycle. These basic studies may provide the rationale for engineering mutant proteasomes that cannot switch on the programs required for parasite infectivity. In addition, our studies are likely to uncover differences between the mammalian and parasite proteasome-pathways, and lead to successful therapies.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI032966-06
Application #
2607801
Study Section
Tropical Medicine and Parasitology Study Section (TMP)
Project Start
1992-07-01
Project End
2001-11-30
Budget Start
1997-12-01
Budget End
1998-11-30
Support Year
6
Fiscal Year
1998
Total Cost
Indirect Cost
Name
New York University
Department
Pathology
Type
Schools of Medicine
DUNS #
City
New York
State
NY
Country
United States
Zip Code
10016
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