Phagosome maturation is a dynamic process involving the engulfment and degradation of pathogens by phagocytic cells. However, several pathogens have employed mechanisms that facilitate their survival and escape from the phagosome. The fungal pathogen, Candida albicans, is capable of switching from yeast to hyphal form to facilitate its pathogenicity and escape from the phagosome. Rab GTPases are key regulators in phagosome maturation by mediating interactions with the endocytic pathway and leading to biogenesis of the phagolysosome. The temporal localisation dynamics of Rab2 on maturing phagosomes containing live C. albicans was investigated. Live-cell imaging revealed green fluorescent protein (GFP)-tagged Rab2 was recruited to C. albicans-containing phagosomes. Rab2 appeared on phagosomes within 2 min following complete engulfment of C. albicans. Rab2 persisted transiently on macrophage phagosomes and this correlated with the length of C. albicans hyphae at the time of uptake, suggesting C. albicans morphology modulates Rab2 localisation dynamics. Expression of dominant negative or dominant active Rab2 did not affect macrophage migration, the rate of engulfment or phagosome acidification during the early stages of phagosome maturation. Furthermore, altered expression of Rab2 did not interfere with C. albicans ability to escape from and kill macrophages, suggesting Rab2 is not involved in the outcome of the host-pathogen interaction. However, altered expression of Rab2 reduced the acquisition of the late-stage phagosome maturation markers, cathepsin B and LAMP1, suggesting Rab2 impacts upon phagosome-lysosome fusion. Finally, the uptake of other particles by macrophages revealed Rab2 recruitment, as well as localisation dynamics on phagosomes, may be cargo-dependent. Through the use of live-cell imaging, real-time dynamics of phagosome biogenesis in live cells was examined, offering unique insight at the host-pathogen interface.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:752693 |
| Date | January 2018 |
| Creators | Lyall, Natalie |
| Contributors | Gow, Neil ; Erwig, Lars-Peter |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=238253 |
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