scholarly journals Cellular Prion Protein Promotes Brucella Infection into Macrophages

2003 ◽  
Vol 198 (1) ◽  
pp. 5-17 ◽  
Author(s):  
Masahisa Watarai ◽  
Suk Kim ◽  
Janchivdorj Erdenebaatar ◽  
Sou-ichi Makino ◽  
Motohiro Horiuchi ◽  
...  
Keyword(s):  
Prion Protein ◽  
Cellular Prion Protein ◽  
Host Cells ◽  
Human Brucellosis ◽  
Intracellular Replication ◽  
Bacterial Surface ◽  
Brucella Infection ◽  
Cellular Target

The products of the Brucella abortus virB gene locus, which are highly similar to conjugative DNA transfer system, enable the bacterium to replicate within macrophage vacuoles. The replicative phagosome is thought to be established by the interaction of a substrate of the VirB complex with macrophages, although the substrate and its host cellular target have not yet been identified. We report here that Hsp60, a member of the GroEL family of chaperonins, of B. abortus is capable of interacting directly or indirectly with cellular prion protein (PrPC) on host cells. Aggregation of PrPC tail-like formation was observed during bacterial swimming internalization into macrophages and PrPC was selectively incorporated into macropinosomes containing B. abortus. Hsp60 reacted strongly with serum from human brucellosis patients and was exposed on the bacterial surface via a VirB complex–associated process. Under in vitro and in vivo conditions, Hsp60 of B. abortus bound to PrPC. Hsp60 of B. abortus, expressed on the surface of Lactococcus lactis, promoted the aggregation of PrPC but not PrPC tail formation on macrophages. The PrPC deficiency prevented swimming internalization and intracellular replication of B. abortus, with the result that phagosomes bearing the bacteria were targeted into the endocytic network. These results indicate that signal transduction induced by the interaction between bacterial Hsp60 and PrPC on macrophages contributes to the establishment of B. abortus infection.

scholarly journals Novel Salmonella enterica Serovar Typhimurium Protein That Is Indispensable for Virulence and Intracellular Replication

2001 ◽  
Vol 69 (12) ◽  
pp. 7413-7418 ◽  
Author(s):  
Tahar van der Straaten ◽  
Angela van Diepen ◽  
Kitty Kwappenberg ◽  
Sjaak van Voorden ◽  
Kees Franken ◽  
...  
Keyword(s):  
Amino Acid ◽  
Protein Function ◽  
Salmonella Enterica ◽  
Host Cells ◽  
Wild Type ◽  
Intracellular Replication ◽  
Oxygen Intermediates ◽  
Serovar Typhimurium

ABSTRACT Upon contact with host cells, the intracellular pathogenSalmonella enterica serovar Typhimurium promotes its uptake, targeting, and survival in intracellular niches. In this process, the bacterium evades the microbicidal effector mechanisms of the macrophage, including oxygen intermediates. This study reports the phenotypic and genotypic characterization of an S. enterica serovar Typhimurium mutant that is hypersusceptible to superoxide. The susceptible phenotype is due to a MudJ insertion-inactivation of a previously undescribedSalmonella gene designated sspJ that is located between 54.4 and 64 min of the Salmonellachromosome and encodes a 392-amino-acid protein. In vivo, upon intraperitoneal injection of 104 to 107bacteria in C3H/HeN and 101 to 104 bacteria in BALB/c mice, the mutant strain was less virulent than the wild type. Consistent with this finding, during the first hour after ingestion by macrophage-like J774 and RAW264.7 cells in vitro, the intracellular killing of the strain carrying sspJ::MudJ is enhanced fivefold over that of wild-type microorganisms. Wild-type salmonellae displayed significant intracellular replication during the first 24 h after uptake, but sspJ::MudJ mutants failed to do so. This phenotype could be restored to that of the wild type by sspJ complementation. The SspJ protein is found in the cytoplasmic membrane and periplasmic space. Amino acid sequence homology analysis did reveal a leader sequence and putative pyrroloquinoline quinone-binding domains, but no putative protein function. We excluded the possibility that SspJ is a scavenger of superoxide or has superoxide dismutase activity.

scholarly journals Differential Requirements for VirB1 and VirB2 during Brucella abortus Infection

2004 ◽  
Vol 72 (9) ◽  
pp. 5143-5149 ◽  
Author(s):  
Andreas B. den Hartigh ◽  
Yao-Hui Sun ◽  
David Sondervan ◽  
Niki Heuvelmans ◽  
Marjolein O. Reinders ◽  
...  
Keyword(s):  
Mouse Model ◽  
Brucella Abortus ◽  
Persistent Infection ◽  
Host Cells ◽  
Intracellular Replication ◽  
Bacterial Surface ◽  
Type Iv

ABSTRACT The Brucella abortus virB operon, encoding a type IV secretion system (T4SS), is required for intracellular replication and persistent infection in the mouse model. The products of the first two genes of the virB operon, virB1 and virB2, are predicted to be localized at the bacterial surface, where they could potentially interact with host cells. Studies to date have focused on characterization of transposon mutations in these genes, which are expected to exert polar effects on downstream genes in the operon. In order to determine whether VirB1 and VirB2 are required for the function of the T4SS apparatus, we constructed and characterized nonpolar deletion mutations of virB1 and virB2. Both mutants were shown to be nonpolar, as demonstrated by their ability to express the downstream gene virB5 during stationary phase of growth in vitro. Both VirB1 and VirB2 were essential for intracellular replication in J774 macrophages. The nonpolar virB2 mutant was unable to cause persistent infection in the mouse model, demonstrating the essential role of VirB2 in the function of the T4SS apparatus during infection. In contrast, the nonpolar virB1 mutant persisted at wild-type levels, showing that the function of VirB1 is dispensable in the mouse model of persistent infection.

scholarly journals Neuroprotective role of PrPC against kainate-induced epileptic seizures and cell death depends on the modulation of JNK3 activation by GluR6/7–PSD-95 binding

2011 ◽  
Vol 22 (17) ◽  
pp. 3041-3054 ◽  
Author(s):  
Patricia Carulla ◽  
Ana Bribián ◽  
Alejandra Rangel ◽  
Rosalina Gavín ◽  
Isidro Ferrer ◽  
...  
Keyword(s):  
Prion Protein ◽  
Knockout Mice ◽  
Neuronal Excitability ◽  
Epileptic Seizures ◽  
Cellular Prion Protein ◽  
Transmissible Spongiform Encephalopathies ◽  
Spongiform Encephalopathies ◽  
Glycosyl Phosphatidylinositol

Cellular prion protein (PrPC) is a glycosyl-phosphatidylinositol–anchored glycoprotein. When mutated or misfolded, the pathogenic form (PrPSC) induces transmissible spongiform encephalopathies. In contrast, PrPC has a number of physiological functions in several neural processes. Several lines of evidence implicate PrPC in synaptic transmission and neuroprotection since its absence results in an increase in neuronal excitability and enhanced excitotoxicity in vitro and in vivo. Furthermore, PrPC has been implicated in the inhibition of N-methyl-d-aspartic acid (NMDA)–mediated neurotransmission, and prion protein gene (Prnp) knockout mice show enhanced neuronal death in response to NMDA and kainate (KA). In this study, we demonstrate that neurotoxicity induced by KA in Prnp knockout mice depends on the c-Jun N-terminal kinase 3 (JNK3) pathway since Prnpo/oJnk3o/o mice were not affected by KA. Pharmacological blockage of JNK3 activity impaired PrPC-dependent neurotoxicity. Furthermore, our results indicate that JNK3 activation depends on the interaction of PrPC with postsynaptic density 95 protein (PSD-95) and glutamate receptor 6/7 (GluR6/7). Indeed, GluR6–PSD-95 interaction after KA injections was favored by the absence of PrPC. Finally, neurotoxicity in Prnp knockout mice was reversed by an AMPA/KA inhibitor (6,7-dinitroquinoxaline-2,3-dione) and the GluR6 antagonist NS-102. We conclude that the protection afforded by PrPC against KA is due to its ability to modulate GluR6/7-mediated neurotransmission and hence JNK3 activation.

scholarly journals Expression and characterisation of fully posttranslationally modified cellular prion protein in Pichia pastoris

2013 ◽  
Vol 394 (11) ◽  
pp. 1475-1483
Author(s):  
Jendrik Marbach ◽  
Peter Zentis ◽  
Philipp Ellinger ◽  
Henrik Müller ◽  
Eva Birkmann
Keyword(s):  
Plasma Membrane ◽  
Pichia Pastoris ◽  
Prion Protein ◽  
Prion Diseases ◽  
Phosphatidyl Inositol ◽  
Cellular Prion Protein ◽  
Glycosylation Pattern ◽  
Signal Sequences

Abstract Prion diseases are fatal neurodegenerative diseases which occur as sporadic, genetic, and transmissible disorders. A molecular hallmark of prion diseases is the conformational conversion of the host-encoded cellular form of the prion protein (PrPC) into its misfolded pathogenic isoform (PrPSc). PrPSc is the main component of the pathological and infectious prion agent. The study of the conversion mechanism from PrPC to PrPSc is a major field in prion research. PrPC is glycosylated and attached to the plasma membrane via its glycosyl phosphatidyl inositol (GPI)-anchor. In this study we established and characterised the expression of fully posttranslationally modified mammalian Syrian golden hamster PrPC in the yeast Pichia pastoris using native PrPC-specific N- and C-terminal signal sequences. In vivo as well as in vitro-studies demonstrated that the signal sequences controlled posttranslational processing and trafficking of native PrPC, resulting in PrPC localised in the plasma membrane of P. pastoris. In addition, the glycosylation pattern of native PrPC could be confirmed.

scholarly journals Prion protein attenuates excitotoxicity by inhibiting NMDA receptors

2008 ◽  
Vol 181 (3) ◽  
pp. 551-565 ◽  
Author(s):  
Houman Khosravani ◽  
Yunfeng Zhang ◽  
Shigeki Tsutsui ◽  
Shahid Hameed ◽  
Christophe Altier ◽  
...  
Keyword(s):  
Nmda Receptors ◽  
Prion Protein ◽  
Hippocampal Neurons ◽  
Neuronal Excitability ◽  
Physiological Role ◽  
Cellular Prion Protein ◽  
Glutamate Excitotoxicity ◽  
Null Mouse

It is well established that misfolded forms of cellular prion protein (PrP [PrPC]) are crucial in the genesis and progression of transmissible spongiform encephalitis, whereas the function of native PrPC remains incompletely understood. To determine the physiological role of PrPC, we examine the neurophysiological properties of hippocampal neurons isolated from PrP-null mice. We show that PrP-null mouse neurons exhibit enhanced and drastically prolonged N-methyl-d-aspartate (NMDA)–evoked currents as a result of a functional upregulation of NMDA receptors (NMDARs) containing NR2D subunits. These effects are phenocopied by RNA interference and are rescued upon the overexpression of exogenous PrPC. The enhanced NMDAR activity results in an increase in neuronal excitability as well as enhanced glutamate excitotoxicity both in vitro and in vivo. Thus, native PrPC mediates an important neuroprotective role by virtue of its ability to inhibit NR2D subunits.

scholarly journals Rifapentine is active in vitro and in vivo against Toxoplasma gondii.

1996 ◽  
Vol 40 (6) ◽  
pp. 1335-1337 ◽  
Author(s):  
F G Araujo ◽  
A A Khan ◽  
J S Remington
Keyword(s):  
Toxoplasma Gondii ◽  
Protozoan Parasite ◽  
Host Cells ◽  
Intracellular Replication ◽  
Degree Of Protection

Rifapentine, a derivative of rifamycin, was examined for its in vitro and in vivo activities against the protozoan parasite Toxoplasma gondii. The drug inhibited the intracellular replication of parasites and was not cytotoxic for the host cells at inhibitory concentrations. Mice infected either intraperitoneally with tachyzoites of the RH strain or orally with tissue cysts of the C56 strain were protected against death by treatment with rifapentine. The degree of protection was similar to that induced by atovaquone and apparently higher than that induced by rifabutin. Rifapentine may be a useful drug for the treatment of toxoplasmosis in immunocompromised individuals.

scholarly journals Mutated but Not Deleted Ovine PrPCN-Terminal Polybasic Region Strongly Interferes with Prion Propagation in Transgenic Mice

2015 ◽  
Vol 90 (3) ◽  
pp. 1638-1646 ◽  
Author(s):  
Manal Khalifé ◽  
Fabienne Reine ◽  
Sophie Paquet-Fifield ◽  
Johan Castille ◽  
Laetitia Herzog ◽  
...  
Keyword(s):  
Amino Acid ◽  
Prion Protein ◽  
Major Effect ◽  
Cellular Prion Protein ◽  
Spongiform Encephalopathy ◽  
Structural Variations ◽  
Prion Propagation ◽  
Polybasic Region

ABSTRACTMammalian prions are proteinaceous infectious agents composed of misfolded assemblies of the host-encoded, cellular prion protein (PrP). Physiologically, the N-terminal polybasic region of residues 23 to 31 of PrP has been shown to be involved in its endocytic trafficking and interactions with glycosaminoglycans or putative ectodomains of membrane-associated proteins. Several recent reports also describe this PrP region as important for the toxicity of mutant prion proteins and the efficiency of prion propagation, bothin vitroandin vivo. The question remains as to whether the latter observations made with mouse PrP and mouse prions would be relevant to other PrP species/prion strain combinations given the dramatic impact on prion susceptibility of minimal amino acid substitutions and structural variations in PrP. Here, we report that transgenic mouse lines expressing ovine PrP with a deletion of residues 23 to 26 (KKRP) or mutated in this N-terminal region (KQHPH instead of KKRPK) exhibited a variable, strain-dependent susceptibility to prion infection with regard to the proportion of affected mice and disease tempo relative to findings in their wild-type counterparts. Deletion has no major effect on 127S scrapie prion pathogenesis, whereas mutation increased by almost 3-fold the survival time of the mice. Deletion marginally affected the incubation time of scrapie LA19K and ovine bovine spongiform encephalopathy (BSE) prions, whereas mutation caused apparent resistance to disease.IMPORTANCERecent reports suggested that the N-terminal polybasic region of the prion protein could be a therapeutic target to prevent prion propagation or toxic signaling associated with more common neurodegenerative diseases such as Alzheimer's disease. Mutating or deleting this region in ovine PrP completes the data previously obtained with the mouse protein by identifying the key amino acid residues involved.

scholarly journals Trovafloxacin is active against Toxoplasma gondii.

1996 ◽  
Vol 40 (8) ◽  
pp. 1855-1859 ◽  
Author(s):  
A A Khan ◽  
T Slifer ◽  
F G Araujo ◽  
J S Remington
Keyword(s):  
Toxoplasma Gondii ◽  
Host Cells ◽  
Intracellular Replication ◽  
Congenital Infections ◽  
Time To Death ◽  
Significant Toxicity ◽  
Acute Toxoplasmosis ◽  
Toxic Drugs

Drugs currently used for treatment of toxoplasmosis in pregnant women, congenital infections, immunocompromised patients, and patients with the ocular disease are not always effective or may be dangerous to use; therefore, there is a need for more-effective and less-toxic drugs. Recently, we examined a group of fluoroquinolones for in vitro and in vivo activities against Toxoplasma gondii. Among those examined in vitro (ciprofloxacin, fleroxacin, ofloxacin, temafloxacin, and trovafloxacin), only trovafloxacin significantly inhibited intracellular replication of T. gondii without significant toxicity for host cells. In a murine model of acute toxoplasmosis, 100 or 200 mg of trovafloxacin per kg of body weight per day for 10 days protected 100% of infected mice against death. A dose of 50 mg/kg/day protected 90% of the mice, and a dose of 25 mg/kg/day effected prolongation of time to death. The other fluoroquinolones did not have such in vivo activities. These results indicate that trovafloxacin may be useful for treatment of toxoplasmosis in humans.

Anti-invasive activity of bovine lactoferrin towards group A streptococci

2002 ◽  
Vol 80 (1) ◽  
pp. 119-124 ◽  
Author(s):  
Maria Ajello ◽  
Rita Greco ◽  
Francesco Giansanti ◽  
Maria Teresa Massucci ◽  
Giovanni Antonini ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Host Cells ◽  
Bovine Lactoferrin ◽  
Group A Streptococci ◽  
Intracellular Replication ◽  
In Vitro Invasion ◽  
Cultured Epithelial Cells ◽  
Group A

Group A streptococci (GAS) are able to invade cultured epithelial and endothelial cells without evidence of intracellular replication. GAS, like other facultative intracellular bacterial pathogens, evolved such ability to enter and to survive within host cells avoiding the host defences, and bacterial intracellular survival could explain the recurrence of infections. We report here that 1 mg bovine lactoferrin (bLf)/mL significantly hindered the in vitro invasion of cultured epithelial cells by GAS isolated from patients suffering from pharyngitis and completely inhibited the invasiveness of GAS pretreated with subinhibiting concentrations of erythromycin or ampicillin. One milligram of bLf per millilitre was also able to increase the number of epithelial cells undergoing apoptosis following GAS invasion, although the number of intracellular GAS in the presence of bLf decreased by about 10-fold. The ability of bLf to decrease GAS invasion was confirmed by an in vivo trial carried out on 12 children suffering from pharyngitis and already scheduled for tonsillectomy. In tonsil specimens from children treated for 15 days before tonsillectomy with both oral erythromycin (500 mg t.i.d. (three times daily)) and bLf gargles (100 mg t.i.d.), a lower number of intracellular GAS was found in comparison with that retrieved in tonsil specimens from children treated with erythromycin alone (500 mg t.i.d.).Key words: lactoferrin, group A streptococci, invasiveness, anti-invasive activity, apoptosis.

scholarly journals Cellular Prion Protein Mediates α‐Synuclein Uptake, Localization, and Toxicity In Vitro and In Vivo

2021 ◽  
Author(s):  
Tobias Thom ◽  
Matthias Schmitz ◽  
Anna‐Lisa Fischer ◽  
Angela Correia ◽  
Susana Correia ◽  
...  
Keyword(s):  
Prion Protein ◽  
Cellular Prion Protein ◽  
Toxicity In Vitro
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