The dense granule protein 8 (GRA8) is a component of the sub-pellicular cytoskeleton in Toxoplasma gondii

Díaz-Martín, Rubén D.; Mercier, Corinne; León, Carmen T. Gómez de; González, Ricardo Mondragón; Pozos, Sirenia González; Ríos-Castro, Emmanuel; García, Raúl Argüello; Fox, Barbara A.; Bzik, David J.; Flores, Ricardo Mondragón

doi:10.1007/s00436-019-06298-7

Cited by 13 publications

(9 citation statements)

References 49 publications

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“…Interestingly, GRA3 expression was enhanced when parasites were exposed to DHEA and DHEA/S-P. Recently, it was reported that GRA3 may have a role in the stabilization of the subpellicular cytoskeleton network, as ∆GRA3 strain tachyzoites-purified cytoskeletons lose the organization of this structure [47], which could be a possible explanation of why more parasites treated with DHEA/S-P preserve their characteristic form compared to tachyzoites treated with DHEA alone.…”

Section: Discussionmentioning

confidence: 99%

Dehydroepiandrosterone Effect on Toxoplasma gondii: Molecular Mechanisms Associated to Parasite Death

et al. 2021

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Toxoplasmosis is a zoonotic disease caused by the apicomplexa protozoan parasite Toxoplasma gondii. This disease is a health burden, mainly in pregnant women and immunocompromised individuals. Dehydroepiandrosterone (DHEA) has proved to be an important molecule that could drive resistance against a variety of infections, including intracellular parasites such as Plasmodium falciparum and Trypanozoma cruzi, among others. However, to date, the role of DHEA on T. gondii has not been explored. Here, we demonstrated for the first time the toxoplasmicidal effect of DHEA on extracellular tachyzoites. Ultrastructural analysis of treated parasites showed that DHEA alters the cytoskeleton structures, leading to the loss of the organelle structure and organization as well as the loss of the cellular shape. In vitro treatment with DHEA reduces the viability of extracellular tachyzoites and the passive invasion process. Two-dimensional (2D) SDS-PAGE analysis revealed that in the presence of the hormone, a progesterone receptor membrane component (PGRMC) with a cytochrome b5 family heme/steroid binding domain-containing protein was expressed, while the expression of proteins that are essential for motility and virulence was highly reduced. Finally, in vivo DHEA treatment induced a reduction of parasitic load in male, but not in female mice.

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Section: Discussionmentioning

confidence: 99%

Dehydroepiandrosterone Effect on Toxoplasma gondii: Molecular Mechanisms Associated to Parasite Death

et al. 2021

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“…GRA7 molecules were observed in association with membranes in the cyst wall and the cyst matrix (56). GRA8 is a proline-rich protein that localizes to the PVM (78) and is a component of the subpellicular cytoskeleton in tachyzoite-stage parasites (79). GRA14 is a transmembrane protein that localizes to the PVM, IVN, and PVE (80).…”

Section: Figmentioning

confidence: 99%

Toxoplasma gondii Parasitophorous Vacuole Membrane-Associated Dense Granule Proteins Regulate Maturation of the Cyst Wall

Guevara

Fox

Bzik

2020

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After differentiation is triggered, the tachyzoite-stage Toxoplasma gondii parasitophorous vacuole membrane (PVM) has been hypothesized to transition into the cyst membrane that surrounds the cyst wall and encloses bradyzoites. Here, we tracked the localization of two PVM dense granule (GRA) proteins (GRA5 and GRA7) after in vitro differentiation of the tachyzoite stage parasitophorous vacuole into the mature cyst. GRA5 and GRA7 were visible at the cyst periphery at 6 h and at all later times after differentiation, suggesting that the PVM remained intact as it transitioned into the cyst membrane. By day 3 postdifferentiation, GRA5 and GRA7 were visible in a continuous pattern at the cyst periphery. In mature 7- and 10-day-old cysts permeabilized with a saponin pulse, GRA5 and GRA7 were localized to the cyst membrane and the cyst wall regions. Cysts at different stages of cyst development exhibited differential susceptibility to saponin permeabilization, and, correspondingly, saponin selectively removed GRA5 from the cyst membrane and cyst wall region in 10-day-old cysts. GRA5 and GRA7 were localized at the cyst membrane and cyst wall region at all times after differentiation of the parasitophorous vacuole, which supports a previous model proposing that the PVM develops into the cyst membrane. In addition, evaluation of Δgra3, Δgra5, Δgra7, Δgra8, and Δgra14 mutants revealed that PVM-localized GRAs were crucial to support the normal rate of accumulation of cyst wall proteins at the cyst periphery. IMPORTANCE Toxoplasma gondii establishes chronic infection in humans by forming thick-walled cysts that persist in the brain. Once host immunity wanes, cysts reactivate to cause severe, and often lethal, toxoplasmic encephalitis. There is no available therapy to eliminate cysts or to prevent their reactivation. Furthermore, how the cyst membrane and cyst wall structures develop is poorly understood. Here, we visualized and tracked the localization of Toxoplasma parasitophorous vacuole membrane (PVM) dense granules (GRA) proteins during cyst development in vitro. PVM-localized GRA5 and GRA7 were found at the cyst membrane and cyst wall region throughout cyst development, suggesting that the PVM remains intact and develops into the cyst membrane. In addition, our results show that genetic deletion of PVM GRAs reduced the rate of accumulation of cyst wall cargo at the cyst periphery and suggest that PVM-localized GRAs mediate the development and maturation of the cyst wall and cyst membrane.

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“…While GRA7 deforms liposomes into tubular membranes in vitro (37), Δ gra7 parasites induce a hyperformation of the IVN membranes (38). The role of GRA8 at the PVM is currently unknown, but the protein was recently shown to play an independent role in organization of the subpellicular cytoskeleton and motility (39). GRA14 localizes to membranous extensions (PV extensions [PVE]) that radiate from the PVM into the host cell cytoplasm (40).…”

Section: Introductionmentioning

confidence: 99%

Toxoplasma gondii Parasitophorous Vacuole Membrane-Associated Dense Granule Proteins Orchestrate Chronic Infection and GRA12 Underpins Resistance to Host Gamma Interferon

Fox

Guevara

Rommereim

et al. 2019

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Toxoplasma gondii evades host immunity to establish a chronic infection. Here, we assessed the role of parasitophorous vacuole (PV) membrane (PVM)- and intravacuolar network (IVN) membrane-localized dense granule (GRA) proteins in the development of acute and chronic Toxoplasma infection. Deletion of PVM-associated GRA3, GRA7, GRA8, and GRA14 or IVN membrane-associated GRA2, GRA9, and GRA12 in the low-virulence type II Prugniaud (Pru) strain induced severe defects in the development of chronic-stage cysts in vivo without affecting the parasite growth rate or the ability to differentiate into cysts in vitro. Acute virulence of the PruΔgra2, PruΔgra3, and PruΔgra4 mutants was reduced but not abolished. In contrast, the PruΔgra12 mutant was avirulent in mice and PruΔgra12 parasites failed to establish a chronic infection. High-virulence type I strain RHΔgra12 parasites also exhibited a major defect in acute virulence. In gamma interferon (IFN-γ)-activated macrophages, type I RHΔgra12 and type II PruΔgra12 parasites resisted the coating of the PVM with host immunity-related GTPases as effectively as the parental type I RHΔku80 and type II PruΔku80 strains, respectively. Despite this resistance, Δgra12 PVs ultimately succumbed to IFN-γ-activated host cell innate immunity. Our findings uncover a key role for GRA12 in mediating resistance to host IFN-γ and reveal that many other IVN membrane-associated GRA proteins, as well as PVM-localized GRA proteins, play important roles in establishing chronic infection. IMPORTANCE Toxoplasma gondii cysts reactivate during immune deficiency and cause fatal encephalitis. Parasite molecules that coordinate the development of acute and chronic infection are poorly characterized. Here, we show that many intravacuolar network membrane and parasitophorous vacuole membrane-associated dense granule (GRA) proteins orchestrate the development of chronic cysts in vivo. A subset of these GRA proteins also modulate acute virulence, and one protein that associates with the intravacuolar network membranes, namely GRA12, was identified as a major virulence factor required for parasite resistance to host gamma interferon (IFN-γ). Our results revealed that many parasitophorous vacuole membrane and intravacuolar network membrane-associated GRA proteins are essential for successful chronic infection.

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The dense granule protein 8 (GRA8) is a component of the sub-pellicular cytoskeleton in Toxoplasma gondii

Cited by 13 publications

References 49 publications

Dehydroepiandrosterone Effect on Toxoplasma gondii: Molecular Mechanisms Associated to Parasite Death

Dehydroepiandrosterone Effect on Toxoplasma gondii: Molecular Mechanisms Associated to Parasite Death

Toxoplasma gondii Parasitophorous Vacuole Membrane-Associated Dense Granule Proteins Regulate Maturation of the Cyst Wall

Toxoplasma gondii Parasitophorous Vacuole Membrane-Associated Dense Granule Proteins Orchestrate Chronic Infection and GRA12 Underpins Resistance to Host Gamma Interferon

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