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Updated: Mar 20, 2026
A Genetic Screen to Isolate Toxoplasma gondii Host-cell Egress Mutants
Published on: February 8, 2012
A host cell membrane microdomain is a critical factor for organelle discharge by Toxoplasma gondii
Michiru Tahara1, Syed Bilal Ahmad Andrabi2, Ryuma Matsubara1
1Department of Parasitology, National Institute of Infectious Diseases, Toyama, Shinjuku-ku, Tokyo, Japan; Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennodai, Tsukuba, Ibaraki, Japan.
Abstract:
Host cell microdomains are involved in the attachment, entry, and replication of intracellular microbial pathogens. Entry into the host cell of Toxoplasma gondii and the subsequent survival of this protozoan parasite are tightly coupled with the proteins secreted from organelle called rhoptry. The rhoptry proteins are rapidly discharged into clusters of vesicles, called evacuoles, which are then delivered to parasitophorous vacuoles (PVs) or nucleus. In this study, we examined the roles of two host cell microdomain components, cholesterol and glycosylphosphatidylinositol (GPI), in evacuole formation. The acute depletion of cholesterol from the host cell plasma membrane blocked evacuole formation but not invasion. Whereas the lack of host cell GPI also altered evacuole formation but not invasion, instead inducing excess evacuole formation. The latter effect was not influenced by the evacuole-inhibiting effects of host cell cholesterol depletion, indicating the independent roles of host GPI and cholesterol in evacuole formation. In addition, the excess formation of evacuoles resulted in the enhanced recruitment of host mitochondria and endoplasmic reticulum to PVs, which in turn stimulated the growth of the parasite.
Insights
Host cell cholesterol and glycosylphosphatidylinositol (GPI) play distinct roles in evacuole formation during Toxoplasma gondii invasion. Cholesterol depletion blocks evacuole formation, while GPI absence causes excess formation, impacting parasite growth.
Area of Science:
- Cell Biology
- Parasitology
- Host-Pathogen Interactions
Background:
- Host cell microdomains are crucial for intracellular pathogen entry and survival.
- Toxoplasma gondii invasion relies on rhoptry proteins, forming evacuoles within host cells.
- The roles of specific host microdomain components in these processes require further elucidation.
Purpose of the Study:
- To investigate the involvement of host cell cholesterol and glycosylphosphatidylinositol (GPI) in Toxoplasma gondii evacuole formation.
- To determine the independent and combined effects of cholesterol and GPI on invasion and evacuole dynamics.
Main Methods:
- Acute depletion of host cell cholesterol using specific agents.
- Manipulation of host cell glycosylphosphatidylinositol (GPI) levels.
- Microscopy and imaging techniques to observe evacuole formation and parasite-host interactions.
Main Results:
- Cholesterol depletion blocked evacuole formation but did not impede parasite invasion.
- Absence of host cell GPI altered evacuole formation, leading to excess evacuoles without affecting invasion.
- Host cell cholesterol and GPI function independently in regulating evacuole formation.
- Excess evacuole formation enhanced recruitment of host mitochondria and endoplasmic reticulum, promoting parasite growth.
Conclusions:
- Host cell cholesterol and GPI are critical, independently acting regulators of evacuole biogenesis during Toxoplasma gondii infection.
- Dysregulation of these microdomain components significantly impacts parasite-host cell interactions and parasite proliferation.
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