CRISPR/Cas9-Based Knockout of GNAQ Reveals Differences in Host Cell Signaling Necessary for Egress of 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.

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An Uninvited Seat at the Dinner Table: How Apicomplexan Parasites Scavenge Nutrients from the Host

Microorganisms ◽

10.3390/microorganisms9122592 ◽

2021 ◽

Vol 9 (12) ◽

pp. 2592

Author(s):

Federica Piro ◽

Riccardo Focaia ◽

Zhicheng Dou ◽

Silvia Masci ◽

David Smith ◽

...

Keyword(s):

Plasma Membrane ◽

Host Cell ◽

Defense Mechanisms ◽

Parasitophorous Vacuole ◽

Host Cells ◽

Metabolic Demand ◽

Host Cell Membrane ◽

Apicomplexan Parasites ◽

Extracellular Milieu ◽

Cell Defense

Obligate intracellular parasites have evolved a remarkable assortment of strategies to scavenge nutrients from the host cells they parasitize. Most apicomplexans form a parasitophorous vacuole (PV) within the invaded cell, a replicative niche within which they survive and multiply. As well as providing a physical barrier against host cell defense mechanisms, the PV membrane (PVM) is also an important site of nutrient uptake that is essential for the parasites to sustain their metabolism. This means nutrients in the extracellular milieu are separated from parasite metabolic machinery by three different membranes, the host plasma membrane, the PVM, and the parasite plasma membrane (PPM). In order to facilitate nutrient transport from the extracellular environment into the parasite itself, transporters on the host cell membrane of invaded cells can be modified by secreted and exported parasite proteins to maximize uptake of key substrates to meet their metabolic demand. To overcome the second barrier, the PVM, apicomplexan parasites secrete proteins contained in the dense granules that remodel the vacuole and make the membrane permissive to important nutrients. This bulk flow of host nutrients is followed by a more selective uptake of substrates at the PPM that is operated by specific transporters of this third barrier. In this review, we recapitulate and compare the strategies developed by Apicomplexa to scavenge nutrients from their hosts, with particular emphasis on transporters at the parasite plasma membrane and vacuolar solute transporters on the parasite intracellular digestive organelle.

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

Veterinary Pathology ◽

10.1354/vp.42-6-788 ◽

2005 ◽

Vol 42 (6) ◽

pp. 788-796 ◽

Cited By ~ 20

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.

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Developmental Stage Oxidoreductive States of Chlamydia and Infected Host Cells

mBio ◽

10.1128/mbio.01924-14 ◽

2014 ◽

Vol 5 (6) ◽

Cited By ~ 7

Author(s):

Xiaogang Wang ◽

Christian Schwarzer ◽

Kevin Hybiske ◽

Terry E. Machen ◽

Richard S. Stephens

Keyword(s):

Membrane Proteins ◽

Developmental Stage ◽

Host Cell ◽

Outer Membrane ◽

Host Cells ◽

Environmental Stability ◽

Infected Host ◽

Developmental Cycle ◽

Content Type ◽

Redox States

ABSTRACTA defining characteristic ofChlamydiaspp. is their developmental cycle characterized by outer membrane transformations of cysteine bonds among cysteine-rich outer membrane proteins. The reduction-oxidation states of host cell compartments were monitored during the developmental cycle using live fluorescence microscopy. Organelle redox states were studied using redox-sensitive green fluorescent protein (roGFP1) expressed in CF15 epithelial cells and targeted to the cytosol, mitochondria, and endoplasmic reticulum (ER). The redox properties of chlamydiae and the inclusion were monitored using roGFP expressed byChlamydia trachomatisfollowing transformation. Despite the large morphological changes associated with chlamydial infection, redox potentials of the cytosol (Ψcyto[average, −320 mV]), mitochondria (Ψmito[average, −345 mV]), and the ER (ΨER[average, −258 mV]) and their characteristic redox regulatory abilities remained unchanged until the cells died, at which point Ψcytoand Ψmitobecame more oxidized and ΨERbecame more reduced. The redox status of the chamydial cytoplasm was measured following transformation and expression of the roGFP biosensor inC. trachomatisthroughout the developmental cycle. The periplasmic and outer membrane redox states were assessed by the level of cysteine cross-linking of cysteine-rich envelope proteins. In both cases, the chlamydiae were highly reduced early in the developmental cycle and became oxidized late in the developmental cycle. The production of a late-developmental-stage oxidoreductase/isomerase, DsbJ, may play a key role in the regulation of the oxidoreductive developmental-stage-specific process.IMPORTANCEInfectiousChlamydiaorganisms have highly oxidized and cysteine cross-linked membrane proteins that confer environmental stability when outside their host cells. Once these organisms infect a new host cell, the proteins become reduced and remain reduced during the active growth stage. These proteins become oxidized at the end of their growth cycle, wherein infectious organisms are produced and released to the environment. How chlamydiae mediate and regulate this key step in their pathogenesis is unknown. Using biosensors specifically targeted to different compartments within the infected host cell and for the chlamydial organisms themselves, the oxidoreductive states of these compartments were measured during the course of infection. We found that the host cell redox states are not changed by infection withC. trachomatis, whereas the state of the chlamydial organisms remains reduced during infection until the late developmental stages, wherein the organisms’ cytosol and periplasm become oxidized and they acquire environmental resistance and infectivity.

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Live-Cell Imaging of Phosphoinositide Dynamics and Membrane Architecture during Legionella Infection

mBio ◽

10.1128/mbio.00839-13 ◽

2014 ◽

Vol 5 (1) ◽

Cited By ~ 63

Author(s):

Stephen Weber ◽

Maria Wagner ◽

Hubert Hilbi

Keyword(s):

Host Cell ◽

Legionella Pneumophila ◽

Live Cell Imaging ◽

Cell Imaging ◽

Effector Proteins ◽

Host Cells ◽

Wild Type ◽

Host Cell Membrane ◽

Content Type ◽

Temporal And Spatial

ABSTRACTThe causative agent of Legionnaires’ disease,Legionella pneumophila, replicates in amoebae and macrophages in a distinct membrane-bound compartment, theLegionella-containing vacuole (LCV). LCV formation is governed by the bacterial Icm/Dot type IV secretion system that translocates ~300 different “effector” proteins into host cells. Some of the translocated effectors anchor to the LCV membrane via phosphoinositide (PI) lipids. Here, we use the soil amoebaDictyostelium discoideum, producing fluorescent PI probes, to analyze the LCV PI dynamics by live-cell imaging. Upon uptake of wild-type or Icm/Dot-deficientL. pneumophila, PtdIns(3,4,5)P3transiently accumulated for an average of 40 s on early phagosomes, which acquired PtdIns(3)Pwithin 1 min after uptake. Whereas phagosomes containing ΔicmTmutant bacteria remained decorated with PtdIns(3)P, more than 80% of wild-type LCVs gradually lost this PI within 2 h. The process was accompanied by a major rearrangement of PtdIns(3)P-positive membranes condensing to the cell center. PtdIns(4)Ptransiently localized to early phagosomes harboring wild-type or ΔicmT L. pneumophilaand was cleared within minutes after uptake. During the following 2 h, PtdIns(4)Psteadily accumulated only on wild-type LCVs, which maintained a discrete PtdIns(4)Pidentity spatially separated from calnexin-positive endoplasmic reticulum (ER) for at least 8 h. The separation of PtdIns(4)P-positive and ER membranes was even more pronounced for LCVs harboring ΔsidC-sdcAmutant bacteria defective for ER recruitment, without affecting initial bacterial replication in the pathogen vacuole. These findings elucidate the temporal and spatial dynamics of PI lipids implicated in LCV formation and provide insight into host cell membrane and effector protein interactions.IMPORTANCEThe environmental bacteriumLegionella pneumophilais the causative agent of Legionnaires’ pneumonia. The bacteria form in free-living amoebae and mammalian immune cells a replication-permissive compartment, theLegionella-containing vacuole (LCV). To subvert host cell processes, the bacteria secrete the amazing number of ~300 different proteins into host cells. Some of these proteins bind phosphoinositide (PI) lipids to decorate the LCV. PI lipids are crucial factors involved in host cell membrane dynamics and LCV formation. UsingDictyosteliumamoebae producing one or two distinct fluorescent probes, we elucidated the dynamic LCV PI pattern in high temporal and spatial resolution. Notably, the endocytic PI lipid PtdIns(3)Pwas slowly cleared from LCVs, thus incapacitating the host cell’s digestive machinery, while PtdIns(4)Pgradually accumulated on the LCV, enabling critical interactions with host organelles. The LCV PI pattern underlies the spatiotemporal configuration of bacterial effector proteins and therefore represents a crucial aspect of LCV formation.

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A Toxoplasma gondii Ortholog of Plasmodium GAMA Contributes to Parasite Attachment and Cell Invasion

mSphere ◽

10.1128/msphere.00012-16 ◽

2016 ◽

Vol 1 (1) ◽

Cited By ~ 10

Author(s):

My-Hang Huynh ◽

Vern B. Carruthers

Keyword(s):

Toxoplasma Gondii ◽

Host Cell ◽

Cell Invasion ◽

Genetic Evidence ◽

Specific Role ◽

Host Cells ◽

Human Pathogen ◽

Content Type ◽

Apicomplexan Parasites ◽

Adhesive Proteins

ABSTRACT Toxoplasma gondii is a successful human pathogen in the same phylum as malaria-causing Plasmodium parasites. Invasion of a host cell is an essential process that begins with secretion of adhesive proteins onto the parasite surface for attachment and subsequent penetration of the host cell. Conserved invasion proteins likely play roles that were maintained through the divergence of these parasites. Here, we identify a new conserved invasion protein called glycosylphosphatidylinositol-anchored micronemal antigen (GAMA). Tachyzoites lacking TgGAMA were partially impaired in parasite attachment and invasion of host cells, yielding the first genetic evidence of a specific role in parasite entry into host cells. These findings widen our appreciation of the repertoire of conserved proteins that apicomplexan parasites employ for cell invasion. Toxoplasma gondii and its Plasmodium kin share a well-conserved invasion process, including sequential secretion of adhesive molecules for host cell attachment and invasion. However, only a few orthologs have been shown to be important for efficient invasion by both genera. Bioinformatic screening to uncover potential new players in invasion identified a previously unrecognized T. gondii ortholog of Plasmodium glycosylphosphatidylinositol-anchored micronemal antigen (TgGAMA). We show that TgGAMA localizes to the micronemes and is processed into several proteolytic products within the parasite prior to secretion onto the parasite surface during invasion. TgGAMA from parasite lysate bound to several different host cell types in vitro, suggesting a role in parasite attachment. Consistent with this function, tetracycline-regulatable TgGAMA and TgGAMA knockout strains showed significant reductions in host cell invasion at the attachment step, with no defects in any of the other stages of the parasite lytic cycle. Together, the results of this work reveal a new conserved component of the adhesive repertoire of apicomplexan parasites. IMPORTANCE Toxoplasma gondii is a successful human pathogen in the same phylum as malaria-causing Plasmodium parasites. Invasion of a host cell is an essential process that begins with secretion of adhesive proteins onto the parasite surface for attachment and subsequent penetration of the host cell. Conserved invasion proteins likely play roles that were maintained through the divergence of these parasites. Here, we identify a new conserved invasion protein called glycosylphosphatidylinositol-anchored micronemal antigen (GAMA). Tachyzoites lacking TgGAMA were partially impaired in parasite attachment and invasion of host cells, yielding the first genetic evidence of a specific role in parasite entry into host cells. These findings widen our appreciation of the repertoire of conserved proteins that apicomplexan parasites employ for cell invasion.

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Evidence for Host Cells as the Major Contributor of Lipids in the Intravacuolar Network of Toxoplasma-Infected Cells

Eukaryotic Cell ◽

10.1128/ec.00002-11 ◽

2011 ◽

Vol 10 (8) ◽

pp. 1095-1099 ◽

Cited By ~ 40

Author(s):

Carolina E. Caffaro ◽

John C. Boothroyd

Keyword(s):

Host Cell ◽

Fluorescence Recovery After Photobleaching ◽

Parasitophorous Vacuole ◽

Dense Granule ◽

Host Cells ◽

Cell Plasma Membrane ◽

Content Type ◽

Cell Plasma ◽

Continuous Stream ◽

Infected Cells

ABSTRACT The intracellular parasite Toxoplasma gondii develops inside a parasitophorous vacuole (PV) that derives from the host cell plasma membrane during invasion. Previous electron micrograph images have shown that the membrane of this vacuole undergoes an extraordinary remodeling with an extensive network of thin tubules and vesicles, the intravacuolar network (IVN), which fills the lumen of the PV. While dense granule proteins, secreted during and after invasion, are the main factors for the organization and tubulation of the network, little is known about the source of lipids used for this remodeling. By selectively labeling host cell or parasite membranes, we uncovered evidence that strongly supports the host cell as the primary, if not exclusive, source of lipids for parasite IVN remodeling. Fluorescence recovery after photobleaching (FRAP) microscopy experiments revealed that lipids are surprisingly dynamic within the parasitophorous vacuole and are continuously exchanged or replenished by the host cell. The results presented here suggest a new model for development of the parasitophorous vacuole whereby the host provides a continuous stream of lipids to support the growth and maturation of the PVM and IVN.

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Uptake of Helicobacter pylori Vesicles Is Facilitated by Clathrin-Dependent and Clathrin-Independent Endocytic Pathways

mBio ◽

10.1128/mbio.00979-14 ◽

2014 ◽

Vol 5 (3) ◽

Cited By ~ 29

Author(s):

Annelie Olofsson ◽

Lars Nygård Skalman ◽

Ikenna Obi ◽

Richard Lundmark ◽

Anna Arnqvist

Keyword(s):

Helicobacter Pylori ◽

Host Cell ◽

Host Cells ◽

Gastric Epithelial Cells ◽

Host Cell Membrane ◽

Content Type ◽

Effector Molecules ◽

Chemical Inhibition ◽

H Pylori ◽

Endocytic Pathways

ABSTRACTBacteria shed a diverse set of outer membrane vesicles that function as transport vehicles to deliver effector molecules and virulence factors to host cells.Helicobacter pyloriis a gastric pathogen that infects half of the world’s population, and in some individuals the infection progresses into peptic ulcer disease or gastric cancer. Here we report that intact vesicles fromH. pyloriare internalized by clathrin-dependent endocytosis and further dynamin-dependent processes, as well as in a cholesterol-sensitive manner. We analyzed the uptake ofH. pylorivesicles by gastric epithelial cells using a method that we refer to as quantification of internalized substances (qIS). The qIS assay is based on a near-infrared dye with a cleavable linker that enables the specific quantification of internalized substances after exposure to reducing conditions. Both chemical inhibition and RNA interference in combination with the qIS assay showed thatH. pylorivesicles enter gastric epithelial cells via both clathrin-mediated endocytosis and additional endocytic processes that are dependent on dynamin. Confocal microscopy revealed thatH. pylorivesicles colocalized with clathrin and dynamin II and with markers of subsequent endosomal and lysosomal trafficking. Interestingly, however, knockdown of components required for caveolae had no significant effect on internalization and knockdown of components required for clathrin-independent carrier (CLIC) endocytosis increased internalization ofH. pylorivesicles. Furthermore, uptake of vesicles by both clathrin-dependent and -independent pathways was sensitive to depletion, but not sequestering, of cholesterol in the host cell membrane suggesting that membrane fluidity influences the efficiency ofH. pylorivesicle uptake.IMPORTANCEBacterial vesicles act as long-distance tools to deliver toxins and effector molecules to host cells. Vesicles can cause a variety of host cell responses via cell surface-induced cell signaling or internalization. Vesicles of diverse bacterial species enter host cells via different endocytic pathways or via membrane fusion. With the combination of a fluorescence-based quantification assay that quantifies internalized vesicles in a large number of cells and either chemical inhibition or RNA interference, we show that clathrin-mediated endocytosis is the major pathway for uptake ofHelicobacter pylorivesicles and that lipid microdomains of the host cell membrane affect uptake of vesicles via clathrin-independent pathways. Our results provide important insights about membrane fluidity and its important role in the complex process that directs theH. pylorivesicle to a specific endocytic pathway. Understanding the mechanisms that operate in vesicle-host interactions is important to fully recognize the impact of vesicles in pathogenesis.

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

Infection and Immunity ◽

10.1128/iai.00402-12 ◽

2012 ◽

Vol 80 (8) ◽

pp. 2940-2947 ◽

Cited By ~ 12

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.

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Microsporidia Interact with Host Cell Mitochondria via Voltage-Dependent Anion Channels Using Sporoplasm Surface Protein 1

mBio ◽

10.1128/mbio.01944-19 ◽

2019 ◽

Vol 10 (4) ◽

Cited By ~ 2

Author(s):

Bing Han ◽

Yanfen Ma ◽

Vincent Tu ◽

Tadakimi Tomita ◽

Joshua Mayoral ◽

...

Keyword(s):

Host Cell ◽

Parasitophorous Vacuole ◽

Surface Protein ◽

Host Cells ◽

Anion Channels ◽

Polar Tube ◽

Content Type ◽

Proteomic Approach ◽

Voltage Dependent ◽

Microsporidian Infection

ABSTRACT Microsporidia are opportunistic intracellular pathogens that can infect a wide variety of hosts ranging from invertebrates to vertebrates. During invasion, the microsporidian polar tube pushes into the host cell, creating a protective microenvironment, the invasion synapse, into which the sporoplasm extrudes. Within the synapse, the sporoplasm then invades the host cell, forming a parasitophorous vacuole (PV). Using a proteomic approach, we identified Encephalitozoon hellem sporoplasm surface protein 1 (EhSSP1), which localized to the surface of extruded sporoplasms. EhSSP1 was also found to interact with polar tube protein 4 (PTP4). Recombinant EhSSP1 (rEhSSP1) bound to human foreskin fibroblasts, and both anti-EhSSP1 and rEhSSP1 caused decreased levels of host cell invasion, suggesting that interaction of SSP1 with the host cell was involved in invasion. Coimmunoprecipitation (Co-IP) followed by proteomic analysis identified host cell voltage-dependent anion channels (VDACs) as EhSSP1 interacting proteins. Yeast two-hybrid assays demonstrated that EhSSP1 was able to interact with VDAC1, VDAC2, and VDAC3. rEhSSP1 colocalized with the host mitochondria which were associated with microsporidian PVs in infected cells. Transmission electron microscopy revealed that the outer mitochondrial membrane interacted with meronts and the PV membrane, mitochondria clustered around meronts, and the VDACs were concentrated at the interface of mitochondria and parasite. Knockdown of VDAC1, VDAC2, and VDAC3 in host cells resulted in significant decreases in the number and size of the PVs and a decrease in mitochondrial PV association. The interaction of EhSSP1 with VDAC probably plays an important part in energy acquisition by microsporidia via its role in the association of mitochondria with the PV. IMPORTANCE Microsporidia are important opportunistic human pathogens in immune-suppressed individuals, such as those with HIV/AIDS and recipients of organ transplants. The sporoplasm is critical for establishing microsporidian infection. Despite the biological importance of this structure for transmission, there is limited information about its structure and composition that could be targeted for therapeutic intervention. Here, we identified a novel E. hellem sporoplasm surface protein, EhSSP1, and demonstrated that it can bind to host cell mitochondria via host VDAC. Our data strongly suggest that the interaction between SSP1 and VDAC is important for the association of mitochondria with the parasitophorous vacuole during microsporidian infection. In addition, binding of SSP1 to the host cell is associated with the final steps of invasion in the invasion synapse.

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Involvement of Host Cell Integrin α2 in Cryptosporidium parvum Infection

Infection and Immunity ◽

10.1128/iai.05862-11 ◽

2012 ◽

Vol 80 (5) ◽

pp. 1753-1758 ◽

Cited By ~ 18

Author(s):

Haili Zhang ◽

Fengguang Guo ◽

Guan Zhu

Keyword(s):

Host Cell ◽

Cryptosporidium Parvum ◽

Type I Collagen ◽

Parasitophorous Vacuole ◽

Regulatory Elements ◽

Parasite Infection ◽

Host Cells ◽

Type I ◽

Content Type ◽

Integrin Α2

ABSTRACTCryptosporidium parvumis an opportunistic pathogen in AIDS patients. It is an intracellular but extracytoplasmic parasite residing in a host cell-derived parasitophorous vacuole. It is still poorly understood how this parasite interacts with host cells. We observed that expression of the integrin α2 (ITGA2) gene in host cells was significantly upregulated uponC. parvuminfection, and a higher level of ITGA2 protein was present in the parasite infection sites. The infection could be reduced by the treatment of antibodies against ITGA2 and integrin β1 (ITGB1) subunits, as well as by type I collagen (an integrin α2β1 ligand). We also generated stable knockdown of ITGA2 gene expression in HCT-8 cells and observed consistent reduction of parasite infection in these knockdown cells. Collectively, our evidence indicates that host cell ITGA2 might be involved in interacting withCryptosporidiumduring infection, probably acting as part of the regulatory elements upstream of the reported recruiting and reorganization of F actin at the infection sites.

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