scholarly journals Dual Role of Signaling Pathways Leading to Ca2+ and Cyclic AMP Elevation in Host Cell Invasion byTrypanosoma cruzi

2000 ◽  
Vol 68 (12) ◽  
pp. 6602-6610 ◽  
Author(s):  
Elisabet V. Caler ◽  
Rory E. Morty ◽  
Barbara A. Burleigh ◽  
Norma W. Andrews
Keyword(s):  
Cyclic Amp ◽  
Host Cell ◽  
Signaling Pathways ◽  
Signaling Pathway ◽  
Cell Invasion ◽  
Dominant Role ◽  
Host Cells ◽  
Entry Site ◽  
Oligopeptidase B ◽  
Invasion Capacity

ABSTRACT Cell invasion by the protozoan parasite Trypanosoma cruzi involves activation of host signaling pathways and the recruitment and fusion of lysosomes at the parasite entry site. A major signaling pathway regulating invasion of fibroblasts, epithelial cells, and myoblasts involves mobilization of Ca2+ from intracellular stores and requires the activity of a T. cruzi serine peptidase, oligopeptidase B (OPB). Deletion of the OPB gene results in a marked defect in trypomastigote virulence, consistent with a greatly reduced cell invasion capacity. Here we show that uptake by macrophages, on the other hand, is largely independent of OPB expression and sensitive to inhibition of by cytochalasin D. The residual invasion capacity of OPBnull trypomastigotes in fibroblasts still involves lysosome recruitment, although in a significantly delayed fashion. Transient elevations in intracellular Ca2+concentrations were observed in host cells exposed to both wild-type and OPBnull trypomastigotes, but the signals triggered by the mutant parasites were less vigorous and delayed. The capacity of triggering elevation in host cell cyclic AMP (cAMP), however, was unaltered in OPBnull trypomastigotes. Modulation in cAMP levels preferentially affected the residual cell invasion capacity of OPBnull parasites, suggesting that this signaling pathway can play a dominant role in promoting cell invasion in the absence of the major OPB-dependent pathway.

scholarly journals 1,3,4-Thiadiazoles Effectively Inhibit Proliferation of Toxoplasma gondii

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1053
Author(s):  
Lidia Węglińska ◽  
Adrian Bekier ◽  
Katarzyna Dzitko ◽  
Barbara Pacholczyk-Sienicka ◽  
Łukasz Albrecht ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Host Cell ◽  
Cell Invasion ◽  
Direct Action ◽  
Human Fibroblasts ◽  
Imidazole Ring ◽  
Host Cells ◽  
In Vitro Assays ◽  
Host Cell Invasion

Congenital and acquired toxoplasmosis caused by the food- and water-born parasite Toxoplasma gondii (T. gondii) is one of the most prevalent zoonotic infection of global importance. T. gondii is an obligate intracellular parasite with limited capacity for extracellular survival, thus a successful, efficient and robust host cell invasion process is crucial for its survival, proliferation and transmission. In this study, we screened a series of novel 1,3,4-thiadiazole-2-halophenylamines functionalized at the C5 position with the imidazole ring (1b–12b) for their effects on T. gondii host cell invasion and proliferation. To achieve this goal, these compounds were initially subjected to in vitro assays to assess their cytotoxicity on human fibroblasts and then antiparasitic efficacy. Results showed that all of them compare favorably to control drugs sulfadiazine and trimethoprim in terms of T. gondii growth inhibition (IC50) and selectivity toward the parasite, expressed as selectivity index (SI). Subsequently, the most potent of them with meta-fluoro 2b, meta-chloro 5b, meta-bromo 8b, meta-iodo 11b and para-iodo 12b substitution were tested for their efficacy in inhibition of tachyzoites invasion and subsequent proliferation by direct action on established intracellular infection. All the compounds significantly inhibited the parasite invasion and intracellular proliferation via direct action on both tachyzoites and parasitophorous vacuoles formation. The most effective was para-iodo derivative 12b that caused reduction in the percentage of infected host cells by 44% and number of tachyzoites per vacuole by 93% compared to non-treated host cells. Collectively, these studies indicate that 1,3,4-thiadiazoles 1b–12b, especially 12b with IC50 of 4.70 µg/mL and SI of 20.89, could be considered as early hit compounds for future design and synthesis of anti-Toxoplasma agents that effectively and selectively block the invasion and subsequent proliferation of T. gondii into host cells.

scholarly journals Evolution of Invasion in a Diverse Set of Fusobacterium Species

mBio ◽  
2014 ◽  
Vol 5 (6) ◽  
Author(s):  
Abigail Manson McGuire ◽  
Kyla Cochrane ◽  
Allison D. Griggs ◽  
Brian J. Haas ◽  
Thomas Abeel ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Preterm Birth ◽  
Host Cell ◽  
Cell Invasion ◽  
Unknown Function ◽  
Host Cells ◽  
Host Cell Invasion ◽  
Whole Genome ◽  
Large Expansion ◽  
Invading Species

ABSTRACTThe diverseFusobacteriumgenus contains species implicated in multiple clinical pathologies, including periodontal disease, preterm birth, and colorectal cancer. The lack of genetic tools for manipulating these organisms leaves us with little understanding of the genes responsible for adherence to and invasion of host cells. Actively invadingFusobacteriumspecies can enter host cells independently, whereas passively invading species need additional factors, such as compromise of mucosal integrity or coinfection with other microbes. We applied whole-genome sequencing and comparative analysis to study the evolution of active and passive invasion strategies and to infer factors associated with active forms of host cell invasion. The evolution of active invasion appears to have followed an adaptive radiation in which two of the three fusobacterial lineages acquired new genes and underwent expansions of ancestral genes that enable active forms of host cell invasion. Compared to passive invaders, active invaders have much larger genomes, encode FadA-related adhesins, and possess twice as many genes encoding membrane-related proteins, including a large expansion of surface-associated proteins containing the MORN2 domain of unknown function. We predict a role for proteins containing MORN2 domains in adhesion and active invasion. In the largest and most comprehensive comparison of sequencedFusobacteriumspecies to date, we have generated a testable model for the molecular pathogenesis ofFusobacteriuminfection and illuminate new therapeutic or diagnostic strategies.IMPORTANCEFusobacteriumspecies have recently been implicated in a broad spectrum of human pathologies, including Crohn’s disease, ulcerative colitis, preterm birth, and colorectal cancer. Largely due to the genetic intractability of member species, the mechanisms by whichFusobacteriumcauses these pathologies are not well understood, although adherence to and active invasion of host cells appear important. We examined whole-genome sequence data from a diverse set ofFusobacteriumspecies to identify genetic determinants of active forms of host cell invasion. Our analyses revealed that actively invadingFusobacteriumspecies have larger genomes than passively invading species and possess a specific complement of genes—including a class of genes of unknown function that we predict evolved to enable host cell adherence and invasion. This study provides an important framework for future studies on the role ofFusobacteriumin pathologies such as colorectal cancer.

scholarly journals Hierarchies of Host Factor Dynamics at the Entry Site of Shigella flexneri during Host Cell Invasion

2012 ◽  
Vol 80 (7) ◽  
pp. 2548-2557 ◽  
Author(s):  
Soudeh Ehsani ◽  
José Carlos Santos ◽  
Cristina D. Rodrigues ◽  
Ricardo Henriques ◽  
Laurent Audry ◽  
...  
Keyword(s):  
Host Cell ◽  
Tyrosine Kinases ◽  
Time Course ◽  
Shigella Flexneri ◽  
Time Lapse ◽  
Small Gtpases ◽  
Host Factors ◽  
Host Cells ◽  
Entry Site ◽  
Content Type

ABSTRACTShigella flexneri, the causative agent of bacillary dysentery, induces massive cytoskeletal rearrangement, resulting in its entry into nonphagocytic epithelial cells. The bacterium-engulfing membrane ruffles are formed by polymerizing actin, a process activated through injected bacterial effectors that target host small GTPases and tyrosine kinases. Once inside the host cell,S. flexneriescapes from the endocytic vacuole within minutes to move intra- and intercellularly. We quantified the fluorescence signals from fluorescently tagged host factors that are recruited to the site of pathogen entry and vacuolar escape. Quantitative time lapse fluorescence imaging revealed simultaneous recruitment of polymerizing actin, small GTPases of the Rho family, and tyrosine kinases. In contrast, we found that actin surrounding the vacuole containing bacteria dispersed first from the disassembling membranes, whereas other host factors remained colocalized with the membrane remnants. Furthermore, we found that the disassembly of the membrane remnants took place rapidly, within minutes after bacterial release into the cytoplasm. Superresolution visualization of galectin 3 through photoactivated localization microscopy characterized these remnants as small, specular, patchy structures between 30 and 300 nm in diameter. Using our experimental setup to track the time course of infection, we identified theS. flexnerieffector IpgB1 as an accelerator of the infection pace, specifically targeting the entry step, but not vacuolar progression or escape. Together, our studies show that bacterial entry into host cells follows precise kinetics and that this time course can be targeted by the pathogen.

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

mSphere ◽  
2016 ◽  
Vol 1 (1) ◽  
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.

scholarly journals Not a Simple Tether: Binding of Toxoplasma gondii AMA1 to RON2 during Invasion Protects AMA1 from Rhomboid-Mediated Cleavage and Leads to Dephosphorylation of Its Cytosolic Tail

mBio ◽  
2016 ◽  
Vol 7 (5) ◽  
Author(s):  
Shruthi Krishnamurthy ◽  
Bin Deng ◽  
Roxana del Rio ◽  
Kerry R. Buchholz ◽  
Moritz Treeck ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Host Cell ◽  
Cell Invasion ◽  
Transmembrane Domain ◽  
Critical Role ◽  
Host Cells ◽  
Receptor Protein ◽  
Host Cell Invasion ◽  
Cell Binding ◽  
Apicomplexan Parasites

ABSTRACT Apical membrane antigen 1 (AMA1) is a receptor protein on the surface of Toxoplasma gondii that plays a critical role in host cell invasion. The ligand to which T . gondii AMA1 (TgAMA1) binds, TgRON2, is secreted into the host cell membrane by the parasite during the early stages of invasion. The TgAMA1-TgRON2 complex forms the core of the “moving junction,” a ring-shaped zone of tight contact between the parasite and host cell membranes, through which the parasite pushes itself during invasion. Paradoxically, the parasite also expresses rhomboid proteases that constitutively cleave the TgAMA1 transmembrane domain. How can TgAMA1 function effectively in host cell binding if its extracellular domain is constantly shed from the parasite surface? We show here that when TgAMA1 binds the domain 3 (D3) peptide of TgRON2, its susceptibility to cleavage by rhomboid protease(s) is greatly reduced. This likely serves to maintain parasite-host cell binding at the moving junction, a hypothesis supported by data showing that parasites expressing a hypercleavable version of TgAMA1 invade less efficiently than wild-type parasites do. Treatment of parasites with the D3 peptide was also found to reduce phosphorylation of S527 on the cytoplasmic tail of TgAMA1, and parasites expressing a phosphomimetic S527D allele of TgAMA1 showed an invasion defect. Taken together, these data suggest that TgAMA1-TgRON2 interaction at the moving junction protects TgAMA1 molecules that are actively engaged in host cell penetration from rhomboid-mediated cleavage and generates an outside-in signal that leads to dephosphorylation of the TgAMA1 cytosolic tail. Both of these effects are required for maximally efficient host cell invasion. IMPORTANCE Nearly one-third of the world’s population is infected with the protozoan parasite Toxoplasma gondii , which causes life-threatening disease in neonates and immunocompromised individuals. T. gondii is a member of the phylum Apicomplexa, which includes many other parasites of veterinary and medical importance, such as those that cause coccidiosis, babesiosis, and malaria. Apicomplexan parasites grow within their hosts through repeated cycles of host cell invasion, parasite replication, and host cell lysis. Parasites that cannot invade host cells cannot survive or cause disease. AMA1 is a highly conserved protein on the surface of apicomplexan parasites that is known to be important for invasion, and the work presented here reveals new and unexpected insights into AMA1 function. A more complete understanding of the role of AMA1 in invasion may ultimately contribute to the development of new chemotherapeutics designed to disrupt AMA1 function and invasion-related signaling in this important group of human pathogens.

scholarly journals Modulation of the host cell transcriptome and epigenome by Fusobacterium nucleatum

2021 ◽  
Author(s):  
Cody A Despins ◽  
Scott D Brown ◽  
Avery V Robinson ◽  
Andrew J Mungall ◽  
Emma Allen-Vercoe ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Host Cell ◽  
Cell Invasion ◽  
Vascular Endothelial Cells ◽  
Fusobacterium Nucleatum ◽  
Opportunistic Pathogen ◽  
Host Cells ◽  
Host Cell Invasion ◽  
Primary Host ◽  
Cell Responses

Fusobacterium nucleatum (Fn) is a ubiquitous opportunistic pathogen with an emerging role as an oncomicrobe in colorectal and other cancer types. Fn can adhere to and invade host cells in a manner that varies across Fn strains and host cell phenotypes. Here we performed pairwise co-cultures between three Fn strains and two immortalized primary host cell types (colonic epithelial cells and vascular endothelial cells) followed by RNA-seq and ChIP-seq to investigate transcriptional and epigenetic host cell responses. We observed that Fn-induced host cell transcriptional modulation involves strong upregulation of genes related to immune migration and inflammatory processes, such as TNF, CXCL8, CXCL1, and CCL20. Further, we identified genes strongly upregulated specifically in conditions of host cell invasion, including overexpression of both EFNA1 and LIF, two genes commonly upregulated in colorectal cancer and associated with poor patient outcomes, and PTGS2 (COX2), a gene associated with the protective effect of aspirin in the colorectal cancer setting. Interestingly, we also observed downregulation of numerous histone modification genes upon Fn exposure. To further explore this relationship, we used the ChIP-seq data to annotate chromatin states genome-wide. We found significant chromatin remodeling following Fn exposure in conditions of host cell invasion, with substantial increases in the frequency of states corresponding to active enhancers as well as low signal or quiescent states. Thus, our results highlight increased inflammation and chemokine gene expression as conserved host cell responses to Fn exposure, and extensive host cell epigenomic changes associated with Fn host cell invasion. These results extend our understanding of Fn as an emerging pathogen and highlight the importance of considering strain heterogeneity and host cell phenotypic variation when exploring pathogenic mechanisms of Fn.

scholarly journals A Member of the Ferlin Calcium Sensor Family Is Essential for Toxoplasma gondii Rhoptry Secretion

mBio ◽  
2018 ◽  
Vol 9 (5) ◽  
Author(s):  
Bradley I. Coleman ◽  
Sudeshna Saha ◽  
Seiko Sato ◽  
Klemens Engelberg ◽  
David J. P. Ferguson ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Host Cell ◽  
Cell Invasion ◽  
Host Cells ◽  
Model Organisms ◽  
Host Cell Invasion ◽  
Content Type ◽  
Calcium Dependent ◽  
Calcium Sensing ◽  
Intracellular Ca

ABSTRACT Invasion of host cells by apicomplexan parasites such as Toxoplasma gondii is critical for their infectivity and pathogenesis. In Toxoplasma, secretion of essential egress, motility, and invasion-related proteins from microneme organelles is regulated by oscillations of intracellular Ca2+. Later stages of invasion are considered Ca2+ independent, including the secretion of proteins required for host cell entry and remodeling from the parasite’s rhoptries. We identified a family of three Toxoplasma proteins with homology to the ferlin family of double C2 domain-containing Ca2+ sensors. In humans and model organisms, such Ca2+ sensors orchestrate Ca2+-dependent exocytic membrane fusion with the plasma membrane. Here we focus on one ferlin that is conserved across the Apicomplexa, T. gondii FER2 (TgFER2). Unexpectedly, conditionally TgFER2-depleted parasites secreted their micronemes normally and were completely motile. However, these parasites were unable to invade host cells and were therefore not viable. Knockdown of TgFER2 prevented rhoptry secretion, and these parasites failed to form the moving junction at the parasite-host interface necessary for host cell invasion. Collectively, these data demonstrate the requirement of TgFER2 for rhoptry secretion in Toxoplasma tachyzoites and suggest a possible Ca2+ dependence of rhoptry secretion. These findings provide the first mechanistic insights into this critical yet poorly understood aspect of apicomplexan host cell invasion. IMPORTANCE Apicomplexan protozoan parasites, such as those causing malaria and toxoplasmosis, must invade the cells of their hosts in order to establish a pathogenic infection. Timely release of proteins from a series of apical organelles is required for invasion. Neither the vesicular fusion events that underlie secretion nor the observed reliance of the various processes on changes in intracellular calcium concentrations is completely understood. We identified a group of three proteins with strong homology to the calcium-sensing ferlin family, which are known to be involved in protein secretion in other organisms. Surprisingly, decreasing the amounts of one of these proteins (TgFER2) did not have any effect on the typically calcium-dependent steps in invasion. Instead, TgFER2 was essential for the release of proteins from organelles called rhoptries. These data provide a tantalizing first look at the mechanisms controlling the very poorly understood process of rhoptry secretion, which is essential for the parasite’s infection cycle.

scholarly journals Differences in Host Cell Invasion and Salmonella Pathogenicity Island 1 Expression between Salmonella enterica Serovar Paratyphi A and NontyphoidalS. Typhimurium

2016 ◽  
Vol 84 (4) ◽  
pp. 1150-1165 ◽  
Author(s):  
Dana Elhadad ◽  
Prerak Desai ◽  
Guntram A. Grassl ◽  
Michael McClelland ◽  
Galia Rahav ◽  
...  
Keyword(s):  
Host Cell ◽  
Cell Invasion ◽  
Salmonella Enterica ◽  
Intestinal Inflammation ◽  
Pathogenicity Island ◽  
Effector Proteins ◽  
Host Cells ◽  
Host Cell Invasion ◽  
Content Type ◽  
Microaerobic Conditions

Active invasion into nonphagocytic host cells is central toSalmonella entericapathogenicity and dependent on multiple genes withinSalmonellapathogenicity island 1 (SPI-1). Here, we explored the invasion phenotype and the expression of SPI-1 in the typhoidal serovarS. Paratyphi A compared to that of the nontyphoidal serovarS. Typhimurium. We demonstrate that whileS. Typhimurium is equally invasive under both aerobic and microaerobic conditions,S. Paratyphi A invades only following growth under microaerobic conditions. Transcriptome sequencing (RNA-Seq), reverse transcription-PCR (RT-PCR), Western blot, and secretome analyses established thatS. Paratyphi A expresses much lower levels of SPI-1 genes and secretes lesser amounts of SPI-1 effector proteins thanS. Typhimurium, especially under aerobic growth. Bypassing the native SPI-1 regulation by inducible expression of the SPI-1 activator, HilA, considerably elevated SPI-1 gene expression, host cell invasion, disruption of epithelial integrity, and induction of proinflammatory cytokine secretion byS. Paratyphi A but not byS. Typhimurium, suggesting that SPI-1 expression is naturally downregulated inS. Paratyphi A. Using streptomycin-treated mice, we were able to establish substantial intestinal colonization byS. Paratyphi A and showed moderately higher pathology and intestinal inflammation in mice infected withS. Paratyphi A overexpressinghilA. Collectively, our results reveal unexpected differences in SPI-1 expression betweenS. Paratyphi A andS. Typhimurium, indicate thatS. Paratyphi A host cell invasion is suppressed under aerobic conditions, and suggest that lower invasion in aerobic sites and suppressed expression of immunogenic SPI-1 components contributes to the restrained inflammatory infection elicited byS. Paratyphi A.

scholarly journals Molecular basis of mammalian cell invasion by Trypanosoma cruzi

2006 ◽  
Vol 78 (1) ◽  
pp. 87-111 ◽  
Author(s):  
Nobuko Yoshida
Keyword(s):  
Trypanosoma Cruzi ◽  
Cell Invasion ◽  
Target Cell ◽  
Protein Tyrosine Kinase ◽  
Host Cells ◽  
Target Cells ◽  
Cytokeratin 18 ◽  
Parasite Protein ◽  
Oligopeptidase B ◽  
Surface Glycoproteins

Establishment of infection by Trypanosoma cruzi, the agent of Chagas' disease, depends on a series of events involving interactions of diverse parasite molecules with host components. Here we focus on the mechanisms of target cell invasion by metacyclic trypomastigotes (MT) and mammalian tissue culture trypomastigotes (TCT). During MT or TCT internalization, signal transduction pathways are activated both in the parasite and the target cell, leading to Ca2+ mobilization. For cell adhesion, MT engage surface glycoproteins, such as gp82 and gp35/50, which are Ca2+ signal-inducing molecules. In T. cruzi isolates that enter host cells in gp82-mediated manner, parasite protein tyrosine kinase as well as phospholipase C are activated, and Ca2+ is released from I P3-sensitive stores, whereas in T. cruzi isolates that attach to target cells mainly through gp35/50, the signaling pathway involving adenylate cyclase appears to be stimulated, with Ca2+ release from acidocalciosomes. In addition, T. cruzi isolate-dependent inhibitory signals, mediated by MT-specific gp90, may be triggered both in the host cell and the parasite. The repertoire of TCT molecules implicated in cell invasion includes surface glycoproteins of gp85 family, with members containing binding sites for laminin and cytokeratin 18, enzymes such as cruzipain, trans-sialidase, and an oligopeptidase B that generates a Ca2+-agonist from a precursor molecule.

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