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The Leishmania pathogenicity factors GP63 and LPG traffic in vesicular structures via a Sec22b-mediated pathway

Arango Duque, Guillermo; Jardim, Armando; Fukuda, Mitsunori; Descoteaux, Albert . The Leishmania pathogenicity factors GP63 and LPG traffic in vesicular structures via a Sec22b-mediated pathway In: 16e symposium annuel de parasitologie moléculaire du Québec, 6-7 juin 2016, Université McGill, Montréal, QC.

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Résumé

Leishmania parasites conquer their hosts by sabotaging phagocytosis. Phagosomes become microbicidal via membrane exchanges that are mediated by soluble NSF attachment protein receptors (SNAREs), with organelles such as lysosomes and the ER-Golgi intermediate compartment (ERGIC). Leishmania uses pathogenicity factors such as the GP63 metalloprotease to cleave key membrane fusion proteins that regulate cytokine secretion and antigen cross-presentation. Additionally, Leishmania employs lipophosphoglycan (LPG) to retard phagosome maturation. We hypothesized that these pathogenicity molecules are redistributed in the cytoplasm of infected cells in vesicles whose trafficking is mediated by host organelles. Using confocal microscopy, we demonstrated that GP63 and LPG were found in vesicles that are dispersed, in a time-dependent manner, in the cytoplasm of infected phagocytes. This process was partly dependent on phagocytosis. Furthermore, the catalytic activity of GP63 did not alter its trafficking or that of LPG. Flotation assays showed that GP63 and LPG localize to low-density fractions containing vesicles, and to denser fractions enriched in ER/ERGIC proteins. We observed via immunofluorescence that these markers also colocalized with GP63 and LPG. Interestingly, Brefeldin A- and Monensin-mediated disruption of ER-Golgi transport hindered the redistribution of GP63 and LPG, as well as the cleavage of Syt XI. This prompted us to study the role of the SNARE Sec22b – which regulates ER-Golgi transport – on the redistribution of these parasite molecules. In infected cells transduced with shRNA to Sec22b, the trafficking of GP63 and LPG was hampered. Moreover, this ensued in lessened cleavage of Syt XI. Together, our data reveal a novel mechanism by which an intracellular pathogen hijacks membrane fusion regulators in the ER/ERCIG to promote the trafficking of the pathogen’s pathogenicity factors.

Type de document: Document issu d'une conférence ou d'un atelier
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Centre: Centre INRS-Institut Armand Frappier
Date de dépôt: 01 mai 2018 20:14
Dernière modification: 01 mai 2018 20:14
URI: http://espace.inrs.ca/id/eprint/7068

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