Toxoplasma gondii actively remodels the microtubule network in host cells

Abstract

Toxoplasma gondii infection triggers host microtubule rearrangement and organelle recruitment around the parasite vacuole. Factors affecting initial stages of microtubule remodeling are unknown. To illuminate the mechanism, we tested the hypothesis that the parasite actively remodels host microtubules. Utilizing heat-killed parasites and time-lapse analysis, we determined microtubule rearrangement requires living parasites and is time dependent. We discovered a novel aster of microtubules (MTs) associates with the vacuole within 1 h of infection. This aster lacks the concentrated foci of gamma (γ)-tubulin normally associated with MT nucleation sites. Unexpectedly, vacuole enlargement does not correlate with an increase in MT staining around the vacuole. We conclude microtubule remodeling does not result from steric constraints. Using nocodazole washout studies, we demonstrate the vacuole nucleates host microtubule growth in-vivo via γ-tubulinassociated sites. Moreover, superinfected host cells display multiple γ-tubulin foci. Microtubule dynamics are critical for cell cycle control in uninfected cells. Using non-confluent monolayers, we show host cells commonly fail to finish cytokinesis resulting in larger, multinucleated cells. Our data suggest intimate interactions between T. gondii and host microtubules result in suppression of cell division and/or cause a mitotic defect, thus providing a larger space for parasite duplication.

Coordinate Control of Host Centrosome Position, Organelle Distribution, and Migratory Response by Toxoplasma gondii via Host mTORC2

“…Immunostaining for the centrosome marker ␥-tubulin revealed a close association between the host cell centrosome and the PV in wild-type cells (Fig. 1, A and B, upper panels), consistent with earlier studies (6,7). In contrast, in MEFs deficient in either of two mTORC2 components, Rictor and mLST8, this association was disrupted, and centrosome position was observed to be distributed around the periphery of the host nucleus in an apparently random orientation with respect to the PV (Fig.…”

“…The loss of constraint in centrosome position was associated with altered microtubule distribution. Although microtubule wrapping of the PV was observed in all genotypes, as previously observed for wild-type cells (6,7), ϳ50% of mTORC2-deficient MEFs displayed an additional concentration of microtubules adjacent to the host nucleus at some distance from the PV (Fig. 1C).…”

Neospora caninum Recruits Host Cell Structures to Its Parasitophorous Vacuole and Salvages Lipids from Organelles

“…T. gondii (RH) dramatically modifies the architecture of the host microtubular network as its PV is entirely wrapped by microtubules (32,57). To determine whether the PV of Nc-Liv is comparably surrounded by host microtubules, we examined the distribution of the host microtubular cytoskeleton in Nc-Liv-infected cells by IFA, using anti-␣-tubulin antibodies, and by EM.…”

A Review: Competence, Compromise, and Concomitance—Reaction of the Host Cell To Toxoplasma gondii Infection and Development

“…Differences occur between nonphagocytic and phagocytic cells, but the mechanisms are the same except for some modifications, which occur on the cell membrane of phagocytes. Nevertheless, T. gondii can be actively phagocytosed by competent phagocytic cells (Pacheco-Soares and De Souza, 2000;Li et al, 2008;Walker et al, 2008).…”

“…The remodeling of MTs is dependent on parasite viability and infection time. The intimate interactions between T. gondii and host MTs results in suppression of host cell division or causes a mitotic defect, or both, thus providing a larger space for parasite multiplication (Walker et al, 2008).…”