scholarly journals Theileria’s Strategies and Effector Mechanisms for Host Cell Transformation: From Invasion to Immortalization

2021 ◽  
Vol 9 ◽  
Author(s):  
Kerry Woods ◽  
Carmen Perry ◽  
Francis Brühlmann ◽  
Philipp Olias
Keyword(s):  
Host Cell ◽  
Signaling Pathways ◽  
Target Location ◽  
Cell Transformation ◽  
Parasitophorous Vacuole ◽  
Nuclear Pore ◽  
Host Cell Membrane ◽  
Binding Motifs ◽  
Host Cell Cytoplasm ◽  
Induced Apoptosis

One of the first events that follows invasion of leukocytes by Theileria sporozoites is the destruction of the surrounding host cell membrane and the rapid association of the intracellular parasite with host microtubules. This is essential for the parasite to establish its niche within the cytoplasm of the invaded leukocyte and sets Theileria spp. apart from other members of the apicomplexan phylum such as Toxoplasma gondii and Plasmodium spp., which reside within the confines of a host-derived parasitophorous vacuole. After establishing infection, transforming Theileria species (T. annulata, T. parva) significantly rewire the signaling pathways of their bovine host cell, causing continual proliferation and resistance to ligand-induced apoptosis, and conferring invasive properties on the parasitized cell. Having transformed its target cell, Theileria hijacks the mitotic machinery to ensure its persistence in the cytoplasm of the dividing cell. Some of the parasite and bovine proteins involved in parasite-microtubule interactions have been fairly well characterized, and the schizont expresses at least two proteins on its membrane that contain conserved microtubule binding motifs. Theileria-encoded proteins have been shown to be translocated to the host cell cytoplasm and nucleus where they have the potential to directly modify signaling pathways and host gene expression. However, little is known about their mode of action, and even less about how these proteins are secreted by the parasite and trafficked to their target location. In this review we explore the strategies employed by Theileria to transform leukocytes, from sporozoite invasion until immortalization of the host cell has been established. We discuss the recent description of nuclear pore-like complexes that accumulate on membranes close to the schizont surface. Finally, we consider putative mechanisms of protein and nutrient exchange that might occur between the parasite and the host. We focus in particular on differences and similarities with recent discoveries in T. gondii and Plasmodium species.

scholarly journals Reovirus Infection Activates JNK and the JNK-Dependent Transcription Factor c-Jun

2001 ◽  
Vol 75 (23) ◽  
pp. 11275-11283 ◽  
Author(s):  
Penny Clarke ◽  
Suzanne M. Meintzer ◽  
Christian Widmann ◽  
Gary L. Johnson ◽  
Kenneth L. Tyler
Keyword(s):  
Transcription Factor ◽  
Host Cell ◽  
Receptor Binding ◽  
Cell Interaction ◽  
Host Cell Membrane ◽  
Erk Activation ◽  
Reovirus Infection ◽  
Induced Apoptosis ◽  
Factor C ◽  
Jnk Activation

ABSTRACT Viral infection often perturbs host cell signaling pathways including those involving mitogen-activated protein kinases (MAPKs). We now show that reovirus infection results in the selective activation of c-Jun N-terminal kinase (JNK). Reovirus-induced JNK activation is associated with an increase in the phosphorylation of the JNK-dependent transcription factor c-Jun. Reovirus serotype 3 prototype strains Abney (T3A) and Dearing (T3D) induce significantly more JNK activation and c-Jun phosphorylation than does the serotype 1 prototypic strain Lang (T1L). T3D and T3A also induce more apoptosis in infected cells than T1L, and there was a significant correlation between the ability of these viruses to phosphorylate c-Jun and induce apoptosis. However, reovirus-induced apoptosis, but not reovirus-induced c-Jun phosphorylation, is inhibited by blocking TRAIL/receptor binding, suggesting that apoptosis and c-Jun phosphorylation involve parallel rather than identical pathways. Strain-specific differences in JNK activation are determined by the reovirus S1 and M2 gene segments, which encode viral outer capsid proteins (ς1 and μ1c) involved in receptor binding and host cell membrane penetration. These same gene segments also determine differences in the capacity of reovirus strains to induce apoptosis, and again a significant correlation between the capacity of T1L × T3D reassortant reoviruses to both activate JNK and phosphorylate c-Jun and to induce apoptosis was shown. The extracellular signal-related kinase (ERK) is also activated in a strain-specific manner following reovirus infection. Unlike JNK activation, ERK activation could not be mapped to specific reovirus gene segments, suggesting that ERK activation and JNK activation are triggered by different events during virus-host cell interaction.

Eimeria canadensis (Protozoa, Sporozoea): ultrastructure of the host–parasite interface during development of first-generation schizonts in vitro

1980 ◽  
Vol 58 (11) ◽  
pp. 2018-2025 ◽  
Author(s):  
Bodo E. G. Mueller
Keyword(s):  
Host Cell ◽  
Parasitophorous Vacuole ◽  
Eimeria Species ◽  
Outer Zone ◽  
Ultrastructural Observation ◽  
Cell Cytoplasm ◽  
Cell Organelles ◽  
Host Cell Cytoplasm ◽  
Host Parasite

Eimeria canadensis sporozoites were inoculated into monolayer cultures of Madin–Darby bovine kidney and primary bovine embryonic kidney cells. Sporozoites retained their shape for at least 9 days. At that time, the nucleus was enlarged and contained a prominent nucleolus, and amylopectin granules were no longer apparent. The width of the parasitophorous vacuole (pv) between host cell cytoplasm and parasite pellicle widened during transformation of sporozoites into multinucleate schizonts. Areas of altered host cell cytoplasm immediately adjacent to the pv membrane increased in size and became confluent, resulting in the formation of two distinct layers of cytoplasm. The outer zone contained the host cell nucleus, mitochondria, Golgi stacks, and ER, whereas the inner layer appeared granular and was void of all cell organelles except structures resembling ribosomes. Microfilaments were abundant at the border between inner and outer zone. In the most advanced stages observed, host cell organelles persisted only in the perinuclear region. The remaining, attenuated cytoplasm resembled the former inner zone.The novel ultrastructural observation of a bilayered cytoplasm of cells harbouring E. canadensis schizonts is compared with light microscope reports of similar effects caused by other Eimeria species of ruminants and with electron microscope findings of altered intestinal and abomasal cells of sheep harbouring "globidial" schizonts.

scholarly journals Characterization of Stages of Hepatozoon americanum and of Parasitized Canine Host Cells

2005 ◽  
Vol 42 (6) ◽  
pp. 788-796 ◽  
Author(s):  
C. A. Cummings ◽  
R. J. Panciera ◽  
K. M. Kocan ◽  
J. S. Mathew ◽  
S. A. Ewing
Keyword(s):  
Cell Membrane ◽  
Host Cell ◽  
Striated Muscle ◽  
Parasitophorous Vacuole ◽  
Protozoan Parasite ◽  
Host Cells ◽  
Blood Leukocytes ◽  
Host Cell Membrane ◽  
Asexual Multiplication ◽  
Hepatozoon Americanum

American canine hepatozoonosis is caused by Hepatozoon americanum, a protozoan parasite, the definitive host of which is the tick, Amblyomma maculatum. Infection of the dog follows ingestion of ticks that harbor sporulated H. americanum oocysts. Following penetration of the intestinal mucosa, sporozoites are disseminated systemically and give rise to extensive asexual multiplication in cells located predominantly in striated muscle. The parasitized canine cells in “onion skin” cysts and in granulomas situated within skeletal muscle, as well as those in peripheral blood leukocytes (PBL), were identified as macrophages by use of fine structure morphology and/or immunohistochemical reactivity with macrophage markers. Additionally, two basic morphologic forms of the parasite were observed in macrophages of granulomas and PBLs. The forms were presumptively identified as merozoites and gamonts. The presence of a “tail” in some gamonts in PBLs indicated differentiation toward microgametes. Recognition of merozoites in PBLs supports the contention that hematogenously redistributed merozoites initiate repeated asexual cycles and could explain persistence of infection for long periods in the vertebrate host. Failure to clearly demonstrate a host cell membrane defining a parasitophorous vacuole may indicate that the parasite actively penetrates the host cell membrane rather than being engulfed by the host cell, as is characteristic of some protozoans.

scholarly journals Trafficking of malarial proteins to the host cell cytoplasm and erythrocyte surface membrane involves multiple pathways.

1992 ◽  
Vol 119 (6) ◽  
pp. 1481-1495 ◽  
Author(s):  
J A Gormley ◽  
R J Howard ◽  
T F Taraschi
Keyword(s):  
Host Cell ◽  
Protein Trafficking ◽  
Surface Membrane ◽  
Lipid Vesicle ◽  
Cell Cytoplasm ◽  
Host Cell Membrane ◽  
Trophozoite Stage ◽  
Host Cell Cytoplasm ◽  
Texas Red

During the asexual stage of malaria infection, the intracellular parasite exports membranes into the erythrocyte cytoplasm and lipids and proteins to the host cell membrane, essentially "transforming" the erythrocyte. To investigate lipid and protein trafficking pathways within Plasmodium falciparum-infected erythrocytes, synchronous cultures are temporally analyzed by confocal fluorescence imaging microscopy for the production, location and morphology of exported membranes (vesicles) and parasite proteins. Highly mobile vesicles are observed as early as 4 h postinvasion in the erythrocyte cytoplasm of infected erythrocytes incubated in vitro with C6-NBD-labeled phospholipids. These vesicles are most prevalent in the trophozoite stage. An immunofluorescence technique is developed to simultaneously determine the morphology and distribution of the fluorescent membranes and a number of parasite proteins within a single parasitized erythrocyte. Parasite proteins are visualized with FITC- or Texas red-labeled monoclonal antibodies. Double-label immunofluorescence reveals that of the five parasite antigens examined, only one was predominantly associated with membranes in the erythrocyte cytoplasm. Two other parasite antigens localized only in part to these vesicles, with the majority of the exported antigens present in lipid-free aggregates in the host cell cytoplasm. Another parasite antigen transported into the erythrocyte cytoplasm is localized exclusively in lipid-free aggregates. A parasite plasma membrane (PPM) and/or parasitophorous vacuolar membrane (PVM) antigen which is not exported always colocalizes with fluorescent lipids in the PPM/PVM. Visualization of two parasite proteins simultaneously using FITC- and Texas red-labeled 2 degrees antibodies reveals that some parasite proteins are constitutively transported in the same vesicles, whereas other are segregated before export. Of the four exported antigens, only one appears to cross the barriers of the PPM and PVM through membrane-mediated events, whereas the others are exported across the PPM/PVM to the host cell cytoplasm and surface membrane through lipid (vesicle)-independent pathways.

scholarly journals Origins of the parasitophorous vacuole membrane of the malaria parasite, Plasmodium falciparum, in human red blood cells

1992 ◽  
Vol 102 (3) ◽  
pp. 527-532 ◽  
Author(s):  
A.R. Dluzewski ◽  
G.H. Mitchell ◽  
P.R. Fryer ◽  
S. Griffiths ◽  
R.J. Wilson ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Cell Membrane ◽  
Host Cell ◽  
Malaria Parasite ◽  
Parasitophorous Vacuole ◽  
Parasitophorous Vacuole Membrane ◽  
Host Cell Membrane ◽  
Vacuole Membrane ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum

We have attempted to determine whether the parasitophorous vacuole membrane, in which the malaria parasite (merozoite) encapsulates itself when it enters a red blood cell, is derived from the host cell plasma membrane, as the appearance of the invasion process in the electron microscope has been taken to suggest, or from lipid material stored in the merozoite. We have incorporated into the red cell membrane a haptenic phospholipid, phosphatidylethanolamine, containing an NBD (N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)) group, substituted in the acyl chain, and allowed it to translocate into the inner bilayer leaflet. After invasion of these labelled cells by the parasite, Plasmodium falciparum, immuno-gold electron microscopy was used to follow the distribution of the labelled lipid; this was found to be overwhelmingly in favour of the host cell membrane relative to the parasitophorous vacuole. Merozoites of P. knowlesi were allowed to attach irreversibly to red cells without invasion, using the method of pretreatment with cytochalasin. The region of contact between the merozoite and the host cell membrane was in all cases devoid of the labelled phosphatidylethanolamine. These results lead us to infer that the parasitophorous vacuole membrane is derived wholly or partly from lipid preexisting in the merozoite.

The origin of parasitophorous vacuole membrane lipids in malaria-infected erythrocytes

1993 ◽  
Vol 106 (1) ◽  
pp. 237-248 ◽  
Author(s):  
G.E. Ward ◽  
L.H. Miller ◽  
J.A. Dvorak
Keyword(s):  
Host Cell ◽  
Erythrocyte Membrane ◽  
Membrane Lipids ◽  
Parasitophorous Vacuole ◽  
Light Level ◽  
Surface Proteins ◽  
Parasitophorous Vacuole Membrane ◽  
Host Cell Membrane ◽  
Vacuole Membrane ◽  
Erythrocyte Surface

During invasion of an erythrocyte by a malaria merozoite, an indentation develops in the erythrocyte surface at the point of contact between the two cells. This indentation deepens as invasion progresses, until the merozoite is completely surrounded by a membrane known as the parasitophorous vacuole membrane (PVM). We incorporated fluorescent lipophilic probes and phospholipid analogs into the erythrocyte membrane, and followed the fate of these probes during PVM formation with low-light-level video fluorescence microscopy. The concentration of probe in the forming PVM was indistinguishable from the concentration of probe in the erythrocyte membrane, suggesting that the lipids of the PVM are continuous with and derived from the host cell membrane during invasion. In contrast, fluorescently labeled erythrocyte surface proteins were largely excluded from the forming PVM. These data are consistent with a model for PVM formation in which the merozoite induces a localized invagination in the erythrocyte lipid bilayer, concomitant with a localized restructuring of the host cell cytoskeleton.

Ultrastructure of the life-cycle stages of Goussia janae (Apicomplexa, Eimeriidae), with X-ray microanalysis of accompanying precipitates

1992 ◽  
Vol 70 (12) ◽  
pp. 2382-2397 ◽  
Author(s):  
Julius Lukeš ◽  
Vladimír Starý
Keyword(s):  
Life Cycle ◽  
Host Cell ◽  
Intestinal Epithelium ◽  
Parasitophorous Vacuole ◽  
Oocyst Wall ◽  
Cell Cytoplasm ◽  
X Ray ◽  
Host Cell Cytoplasm ◽  
Life Cycle Stages ◽  
Sporocyst Wall

The ultrastructural features of the life-cycle stages of Goussia janae from the intestinal epithelium of the dace Leuciscus leuciscus and chub L. cephalus are described. All merogonial, gamogonial, and early sporogonial stages were localized in the microvillar region in an intracellular and extracytoplasmic position, covered by closely apposed enterocyte and parasitophorous vacuole membranes. Two types of location in the host cell were observed: (i) a more frequent "monopodial" type with a single zone of attachment to the host-cell cytoplasm, and (ii) a "spider-like" type with several isolated zones of attachment. Merozoites were formed by either ecto- or endo-merogony. Microgamonts produced elongated biflagellate microgametes at their periphery. The oocyst wall, produced exclusively by the parasite, was formed at the end of the intracellular phase of the life cycle. Exogenous sporulation resulted in the formation of elongated sporocysts with a thin sporocyst wall bearing a longitudinal suture accompanied by a narrow membranaceous veil. In the cytoplasm and cytoplasmic and parasitophorous vacuoles of the parasite, fine, dense precipitates were present. X-ray microanalysis of these precipitates from osmicated and non-osmicated samples revealed high levels of Ca and P, indicating the possible presence of hydroxyapatite.

scholarly journals The Hydrophilic Translocator for Vibrio parahaemolyticus, T3SS2, Is Also Translocated

2012 ◽  
Vol 80 (8) ◽  
pp. 2940-2947 ◽  
Author(s):  
Xiaohui Zhou ◽  
Jennifer M. Ritchie ◽  
Hirotaka Hiyoshi ◽  
Tetsuya Iida ◽  
Brigid M. Davis ◽  
...  
Keyword(s):  
Host Cell ◽  
Vibrio Parahaemolyticus ◽  
Diarrheal Disease ◽  
Host Cells ◽  
Cell Cytoplasm ◽  
Host Cell Membrane ◽  
Membrane Pore ◽  
Content Type ◽  
Bacterial Proteins ◽  
Host Cell Cytoplasm

ABSTRACTThe pathogenesis of the diarrheal disease caused byVibrio parahaemolyticus, a leading cause of seafood-associated enteritis worldwide, is dependent upon a type III secretion system, T3SS2. This apparatus enables the pathogen to inject bacterial proteins (effectors) into the cytosol of host cells and thereby modulate host processes. T3SS effector proteins transit into the host cell via a membrane pore (translocon) typically formed by 3 bacterial proteins. We have identified the third translocon protein for T3SS2: VopW, which was previously classified as an effector protein for a homologous T3SS inV. cholerae. VopW is a hydrophilic translocon protein; like other such proteins, it is not inserted into the host cell membrane but is required for insertion of the two hydrophobic translocators, VopB2 and VopD2, that constitute the membrane channel. VopW is not required for secretion of T3SS2 effectors into the bacterial culture medium; however, it is essential for transfer of these proteins into the host cell cytoplasm. Consequently, deletion ofvopWabrogates the virulence ofV. parahaemolyticusin several animal models of diarrheal disease. Unlike previously described hydrophilic translocators, VopW is itself translocated into the host cell cytoplasm, raising the possibility that it functions as both a translocator and an effector.

scholarly journals CRISPR/Cas9-Based Knockout of GNAQ Reveals Differences in Host Cell Signaling Necessary for Egress of Apicomplexan Parasites

mSphere ◽  
2020 ◽  
Vol 5 (6) ◽  
pp. e01001-20
Author(s):  
Paul-Christian Burda ◽  
Hugo Bisio ◽  
Jean-Baptiste Marq ◽  
Dominique Soldati-Favre ◽  
Volker T. Heussler
Keyword(s):  
Host Cell ◽  
Parasitophorous Vacuole ◽  
Host Cells ◽  
Infected Host ◽  
Protein Subunit ◽  
Host Cell Membrane ◽  
Guanine Nucleotide Binding Protein ◽  
Liver Stage ◽  
Content Type ◽  
Apicomplexan Parasites

ABSTRACTToxoplasma gondii and members of the genus Plasmodium are obligate intracellular parasites that leave their infected host cell upon a tightly controlled process of egress. Intracellular replication of the parasites occurs within a parasitophorous vacuole, and its membrane as well as the host plasma membrane need to be disrupted during egress, leading to host cell lysis. While several parasite-derived factors governing egress have been identified, much less is known about host cell factors involved in this process. Previously, RNA interference (RNAi)-based knockdown and antibody-mediated depletion identified a host signaling cascade dependent on guanine nucleotide-binding protein subunit alpha q (GNAQ) to be required for the egress of Toxoplasma tachyzoites and Plasmodium blood stage merozoites. Here, we used CRISPR/Cas9 technology to generate HeLa cells deficient in GNAQ and tested their capacity to support the egress of T. gondii tachyzoites and Plasmodium berghei liver stage parasites. While we were able to confirm the importance of GNAQ for the egress of T. gondii, we found that the egress of P. berghei liver stages was unaffected in the absence of GNAQ. These results may reflect differences between the lytic egress process in apicomplexans and the formation of host cell-derived vesicles termed merosomes by P. berghei liver stages.IMPORTANCE The coordinated release of apicomplexan parasites from infected host cells prior to reinvasion is a critical process for parasite survival and the spread of infection. While Toxoplasma tachyzoites and Plasmodium blood stages induce a fast disruption of their surrounding membranes during their egress from host cells, Plasmodium liver stages keep the host cell membrane intact and leave their host cell in host cell-derived vesicles called merosomes. The knockout of GNAQ, a protein involved in G-protein-coupled receptor signaling, demonstrates the importance of this host factor for the lytic egress of T. gondii tachyzoites. Contrastingly, the egress of P. berghei is independent of GNAQ at the liver stage, indicating the existence of a mechanistically distinct strategy to exit the host cell.

scholarly journals The Toxoplasma gondii rhoptry protein ROP 2 is inserted into the parasitophorous vacuole membrane, surrounding the intracellular parasite, and is exposed to the host cell cytoplasm.

1994 ◽  
Vol 127 (4) ◽  
pp. 947-961 ◽  
Author(s):  
C J Beckers ◽  
J F Dubremetz ◽  
O Mercereau-Puijalon ◽  
K A Joiner
Keyword(s):  
Toxoplasma Gondii ◽  
Host Cell ◽  
Direct Evidence ◽  
Parasitophorous Vacuole ◽  
Velocity Sedimentation ◽  
Parasitophorous Vacuole Membrane ◽  
Cell Cytoplasm ◽  
Vacuole Membrane ◽  
Specific Antibodies ◽  
Host Cell Cytoplasm

The origin of the vacuole membrane surrounding the intracellular protozoan parasite Toxoplasma gondii is not known. Although unique secretory organelles, the rhoptries, discharge during invasion of the host cell and may contribute to the formation of this parasitophorous vacuole membrane (PVM), no direct evidence for this hypothesis exists. Using a novel approach we have determined that parasite-encoded proteins are present in the PVM, exposed to the host cell cytoplasm. In infected cells incubated with streptolysin-O or low concentrations of digitonin, the host cell plasma membrane was selectively permeabilized without significantly affecting the integrity of the PVM. Antisera prepared against whole parasites or a parasite fraction enriched in rhoptries and dense granules reacted with the PVM in these permeabilized cells, indicating that parasite-encoded antigens were exposed on the cytoplasmic side of the PVM. Parasite antigens responsible for this staining of the PVM were identified by fractionating total parasite proteins by SDS-PAGE and velocity sedimentation, and then affinity purifying "fraction-specific" antibodies from the crude antisera. Proteins responsible for the PVM-staining, identified with fraction-specific antibodies, cofractionated with known rhoptry proteins. The gene encoding one of the rhoptry proteins, ROP 2, was cloned and sequenced, predicting and integral membrane protein. Antibodies specific for ROP 2 reacted with the intact PVM. These results provide the first direct evidence that rhoptry contents participate in the formation of the PVM of T. gondii and suggest a possible role of ROP 2 in parasite-host cell interactions.

Sign in / Sign up

Export Citation Format

Share Document