The flagellated protozoan parasite Trypanosoma brucei is responsible for African trypanosomiasis, which causes widespread mortality and morbidity of humans and livestock in sub-Saharan Africa. Sleeping sickness is fatal if untreated, yet no vaccine exists and current treatments are old, toxic and difficult to administer. Thus, ther is a pressing need for research to better understand these parasites and facilitate development of new therapeutic interventions. Trypanosomes are also an important experimental system for studying biology of flagella and cilia, which are critical to normal human health. T. brucei depends on its flagellum for movement within host tissues and for directing cell development and division. Extensive work in a wide range of eukaryotes demonstrates that in addition to the flagellum's canonical role in motility, it functions as a signaling center to perceive and respond o external cues in the environment. Recent work indicates that the trypanosome flagellum likewise functions in motility and signaling capacity. The long term goal of the proposed work is to determine the role of motility in pathogenesis, define mechanisms that regulate trypanosome motility and test the hypothesis that the flagellum directs signaling systems important for virulence. To do this, we will employ motility mutants, mouse infection models to test signaling and motility functions for a contribution to infection. We will also employ systems biology approaches to define signaling systems in the flagellum and identify genes controlled by these signaling systems. Finally, we will use cryoelectron tomography, together with mutational analysis to build a three-dimensional molecular model of the flagellum in an effort to understand structural foundations of unique flagellum functions in trypanosomes. Our focus is on the flagellum of T. brucei. However, flagella are important for many other pathogenic protozoa as well as for normal human development and health. Therefore, we expect our results to be of wide interest for the community studying pathogenesis of parasitic protozoa, human development and physiology, and fundamental biology of eukaryotes.

Public Health Relevance

African trypanosomes are devastating human and animal pathogens that cause significant human mortality and limit economic development. The trypanosome flagellum is an essential organelle that is receiving increased attention as a drug target. The current proposal aims to understand aspects of flagellum biology that are important for disease transmission and pathogenesis. The studies will also provide insights into fundamental aspects of flagellum biology that are relevant for a broad spectrum of infectious and inherited diseases in humans.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
Project #
Application #
Study Section
Pathogenic Eukaryotes Study Section (PTHE)
Program Officer
Mcgugan, Glen C
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of California Los Angeles
Schools of Medicine
Los Angeles
United States
Zip Code
Langousis, Gerasimos; Shimogawa, Michelle M; Saada, Edwin A et al. (2016) Loss of the BBSome perturbs endocytic trafficking and disrupts virulence of Trypanosoma brucei. Proc Natl Acad Sci U S A 113:632-7
Marti, Matthias; Hill, Kent L (2016) Sensing and signaling in parasitism. Mol Biochem Parasitol 208:1
Oberholzer, Michael; Saada, Edwin A; Hill, Kent L (2015) Cyclic AMP Regulates Social Behavior in African Trypanosomes. MBio 6:e01954-14
Saada, Edwin A; DeMarco, Stephanie F; Shimogawa, Michelle M et al. (2015) ""With a Little Help from My Friends""-Social Motility in Trypanosoma brucei. PLoS Pathog 11:e1005272
Shimogawa, Michelle M; Saada, Edwin A; Vashisht, Ajay A et al. (2015) Cell Surface Proteomics Provides Insight into Stage-Specific Remodeling of the Host-Parasite Interface in Trypanosoma brucei. Mol Cell Proteomics 14:1977-88
Lopez, Miguel A; Saada, Edwin A; Hill, Kent L (2015) Insect stage-specific adenylate cyclases regulate social motility in African trypanosomes. Eukaryot Cell 14:104-12
Kisalu, Neville K; Langousis, Gerasimos; Bentolila, Laurent A et al. (2014) Mouse infection and pathogenesis by Trypanosoma brucei motility mutants. Cell Microbiol 16:912-24
Saada, Edwin A; Kabututu, Z Pius; Lopez, Miguel et al. (2014) Insect stage-specific receptor adenylate cyclases are localized to distinct subdomains of the Trypanosoma brucei Flagellar membrane. Eukaryot Cell 13:1064-76
Freire, Eden R; Malvezzi, Amaranta M; Vashisht, Ajay A et al. (2014) Trypanosoma brucei translation initiation factor homolog EIF4E6 forms a tripartite cytosolic complex with EIF4G5 and a capping enzyme homolog. Eukaryot Cell 13:896-908
Freire, Eden R; Vashisht, Ajay A; Malvezzi, Amaranta M et al. (2014) eIF4F-like complexes formed by cap-binding homolog TbEIF4E5 with TbEIF4G1 or TbEIF4G2 are implicated in post-transcriptional regulation in Trypanosoma brucei. RNA 20:1272-86

Showing the most recent 10 out of 33 publications