Tracking autophagy during proliferation and differentiation of Trypanosoma brucei
Authors:William R. Proto1, Nathaniel G. Jones1, Graham H. Coombs2, and Jeremy C. Mottram1
doi: 10.15698/mic2014.01.120
Volume 1, pp. 9 to 20, published 06/01/2014.
1 Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8TA, UK.
2 Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, G4 0RE, UK.
Keywords:
trypanosome, protozoan, autophagy, differentiation, cell death.
Corresponding Author(s):
Conflict of interest statement:
The authors declare no conflict of interest.
Please cite this article as:
William R. Proto, Nathaniel G. Jones, Graham H. Coombs, and Jeremy C. Mottram (2014). Tracking autophagy during proliferation and differentiation of Trypanosoma brucei. Microbial Cell 1(1): 9-20. doi: 10.15698/mic2014.01.120
© 2013 Proto et al. This is an open-access article released under the terms of the Creative Commons Attribution-NonCommercial-Share Alike 3.0 license, which allows readers to twist, transform, or build upon the article and then distribute the resulting work non-commercially, as long as they credit the original authors and license their new creations under the identical terms.
Abstract:
Autophagy is a lysosome-dependent degradation mechanism that sequesters target cargo into autophagosomal vesicles. The Trypanosoma brucei genome contains apparent orthologues of several autophagy-related proteins including an ATG8 family. These ubiquitin-like proteins are required for autophagosome membrane formation, but our studies show that ATG8.3 is atypical. To investigate the function of other ATG proteins, RNAi compatible T. brucei were modified to function as autophagy reporter lines by expressing only either YFP-ATG8.1 or YFP-ATG8.2. In the insect procyclic lifecycle stage, independent RNAi down-regulation of ATG3 or ATG7 generated autophagy-defective mutants and confirmed a pro-survival role for autophagy in the procyclic form nutrient starvation response. Similarly, RNAi depletion of ATG5 or ATG7 in the bloodstream form disrupted autophagy, but did not impede proliferation. Further characterisation showed bloodstream form autophagy mutants retain the capacity to undergo the complex cellular remodelling that occurs during differentiation to the procyclic form and are equally susceptible to dihydroxyacetone-induced cell death as wild type parasites, not supporting a role for autophagy in this cell death mechanism. The RNAi reporter system developed, which also identified TOR1 as a negative regulator controlling YFP-ATG8.2 but not YFP-ATG8.1 autophagosome formation, will enable further targeted analysis of the mechanisms and function of autophagy in the medically relevant bloodstream form of T. brucei.