ABSTRACT
Prions are highly resistant to the decontamination procedures normally used to inactivate conventional pathogens. This is a challenging problem not only in the medical and veterinary fields for minimizing the risk of transmission from potentially infective sources but also for ensuring the safe disposal or subsequent use of animal by-products. Specific pressure autoclaving protocols were developed for this purpose, but different strains of prions have been reported to have differing resistance patterns to established prion decontamination procedures, and as additional TSE strains are identified it is necessary to determine the effectiveness of such procedures. In this study we assessed the efficacy of sterilization using the EU recommended autoclave procedure for prions (133°C, 3 Bar for 20 min) on the atypical or Nor98 (AS/Nor98) scrapie strain of sheep and goats. Using a highly sensitive murine mouse model (tg338) that overexpresses ovine PrPC , we determined that this method of decontamination reduced the infectivity titre by 1010 . Infectivity was nonetheless still detected after applying the recommended autoclaving protocol. This shows that AS/Nor98 can survive the designated legislative decontamination conditions, albeit with a significant decrease in titre. The infectivity of a classical scrapie isolate subjected to the same decontamination conditions was reduced by 106 suggesting that the AS/Nor98 isolate is less sensitive to decontamination than the classical scrapie source.
Subject(s)
Decontamination/methods , Prion Proteins/physiology , Sterilization/instrumentation , Animals , MiceABSTRACT
Apart from prion protein genotype, the factors determining the host range and susceptiblity for specific transmissible spongiform encephalopathy agents remain unclear. It is known that bovine atypical L-BSE can transmit to a range of species including primates and humanised transgenic mice. It is important, therefore, that there is as broad an understanding as possible of how such isolates might present in food animal species and how robust they are on inter- and intra-species transmission to inform surveillance sytems and risk assessments. This paper demonstrates that L-BSE can be intracerebrally transmitted to sheep of several genotypes, with the exception of ARR/ARR animals. Positive animals mostly present with a cataplectic form of disease characterized by collapsing episodes and reduced muscle tone. PrP accumulation is confined to the nervous system, with the exception of one animal with lymphoreticular involvement. In Western blot there was maintenance of the low molecular mass and glycoform profile associated with L-BSE, irrespective of ovine host genotype, but there was a substantially higher N-terminal antibody signal relative to the core-specific antibody, which is similar to the ratio associated with classical scrapie. The disease phenotype was maintained on experimental subpassage, but with a shortened survival time indicative of an original species barrier and subsequent adaptation. Passive surveillance approaches would be unlikely to identify such cases as TSE suspects, but current statutory active screening methods would be capable of detecting such cases and classifying them as unusual and requiring further investigation if they were to occur in the field.
Subject(s)
Encephalopathy, Bovine Spongiform/transmission , Sheep Diseases/transmission , Animals , Blotting, Western/veterinary , Brain/pathology , Cattle , Encephalopathy, Bovine Spongiform/diagnosis , Encephalopathy, Bovine Spongiform/pathology , Enzyme-Linked Immunosorbent Assay/veterinary , Phenotype , Sheep , Sheep Diseases/diagnosis , Sheep Diseases/mortality , Sheep Diseases/pathologyABSTRACT
INTRODUCTION: Scrapie and bovine spongiform encephalopathy (BSE) are transmissible spongiform encephalopathies (TSEs) which naturally affect small and large ruminants respectively. However, small ruminants, which are susceptible to BSE under experimental conditions, have been exposed to the same or similar contaminated food additives as cattle. To date two natural cases of BSE in small ruminants have been reported. As a result surveillance projects, combined with appropriate control measures, have been established throughout the European Union (EU) to minimize the overall incidence of small ruminant TSEs. Although BSE can be differentiated from classical scrapie (subsequently referred to as scrapie) if appropriate discriminatory tests are applied, the value of these tests in BSE/scrapie co-infection scenarios has not been evaluated fully. Mouse bioassay is regarded as the gold standard regarding differentiation of distinct TSE strains and has been used as to resolve TSE cases were laboratory tests produced equivocal results. However, the ability of this method to discriminate TSE strains when they co-exist has not been examined systematically. To address this issue we prepared in vitro mixtures of ovine BSE and scrapie and used them to challenge RIII, C57BL/6 and VM mice. RESULTS: Disease phenotype analysis in all three mouse lines indicated that most phenotypic parameters (attack rates, incubation periods, lesion profiles and Western blots) were compatible with scrapie phenotypes as were immunohistochemistry (IHC) data from RIII and C57BL/6 mice. However, in VM mice that were challenged with BSE/scrapie mixtures a single BSE-associated IHC feature was identified, indicating the existence of BSE in animals where the scrapie phenotype was dominant. CONCLUSIONS: We conclude that wild type mouse bioassay is of limited value in detecting BSE in the presence of scrapie particularly if the latter is in relative excess.
Subject(s)
Biological Assay/methods , Mice, Inbred Strains , Phenotype , Prion Diseases/physiopathology , Scrapie/physiopathology , Species Specificity , Animals , Blotting, Western , Cattle , Immunohistochemistry , Mice , Mice, Inbred C57BL , Prion Diseases/metabolism , Scrapie/metabolismABSTRACT
Several transgenic mouse models have been developed which facilitate the transmission of chronic wasting disease (CWD) of cervids and allow prion strain discrimination. The present study was designed to assess the susceptibility of the prototypic mouse line, Tg(CerPrP)1536(+/-), to bovine spongiform encephalopathy (BSE) prions, which have the ability to overcome species barriers. Tg(CerPrP)1536(+/-) mice challenged with red deer-adapted BSE resulted in 90% to 100% attack rates, and BSE from cattle failed to transmit, indicating agent adaptation in the deer.
Subject(s)
Deer/metabolism , Disease Models, Animal , Encephalopathy, Bovine Spongiform/metabolism , Mice , Prions/metabolism , Wasting Disease, Chronic/metabolism , Animals , Cattle , Central Nervous System/metabolism , Central Nervous System/pathology , Disease Susceptibility , Encephalopathy, Bovine Spongiform/pathology , Encephalopathy, Bovine Spongiform/transmission , Female , Male , Mice, Transgenic , Species Specificity , Wasting Disease, Chronic/pathology , Wasting Disease, Chronic/transmissionABSTRACT
Mouse-adapted transmissible spongiform encephalopathy (TSE) strains are routinely distinguished based on reproducible disease characteristics in a given mouse line following inoculation via a consistent route. We investigated whether different administration routes (oral, intragastric (i.g.) and intracerebral (i.c.)) can alter the disease characteristics in IM mice after serial dilution of a stabilized mouse-adapted bovine spongiform encephalopathy (BSE) strain (301V). In addition, the infectivity of distal ileum and mesenteric lymph nodes (ln) sampled at three time points (35 days postinoculation (dpi), 70 dpi and terminal disease) after i.g. inoculation of 301V strain was assessed in mice by i.c. challenge. Strain characteristics were assessed according to standard methodology and PrP(Sc) immunohistochemistry deposition patterns. Mean incubation periods were prolonged following oral or i.g. inoculations compared to the i.c. route. Lesion profiles following i.c. challenges were elevated compared to i.g. and oral routes although vacuolation in the dorsal medulla was consistently high irrespective of the route of administration. Nevertheless, the same PrP(Sc) deposition pattern was associated with each route of administration. Distal and mesenteric ln infectivity was detected as early as 35 dpi and displayed consistent lesion profiles and PrP(Sc) deposition patterns. Our data suggest that although 301V retained its properties, some phenotypic parameters were affected by the route of inoculation. We conclude that bioassay data should be interpreted carefully and should be standardized for route of inoculation.
Subject(s)
Encephalopathy, Bovine Spongiform/pathology , Encephalopathy, Bovine Spongiform/transmission , Prions/administration & dosage , Prions/pathogenicity , Animals , Brain/metabolism , Brain/pathology , Cattle , Disease Models, Animal , Encephalopathy, Bovine Spongiform/metabolism , Ileum/metabolism , Ileum/pathology , Lymph Nodes/metabolism , Lymph Nodes/pathology , Mice , Mice, Inbred Strains , PrPSc Proteins/metabolism , Time FactorsABSTRACT
According to traditional murine bioassay methodology, prions must be serially passaged within a new host before a stable phenotype, and therefore a strain, can be assigned. Prions often transmit with difficulty from one species to another; a property termed the transmission barrier. Transgenic mouse lines that over express prion protein (PrP) genes of different species can circumvent the transmission barrier but serial passages may still be required, particularly if unknown strains are encountered. Here we sought to investigate whether protein misfolding cyclic amplification (PMCA), an in-vitro method of PrP(Sc) replication, could be used to replace serial passage of VRQ/VRQ classical scrapie isolates undergoing strain typing in ovine transgenic tg338 mice. Two classical scrapie field isolates that do not readily transmit to wild-type mice underwent bioassay in tg338 mice pre- and post- PMCA and the phenotype of disease in inoculated mice was compared. For one of the sources investigated, the PMCA product gave rise to the same disease phenotypes in tg338 mice as traditional bioassay, as indicated by lesion profile, IHC analysis and Western blot, whilst the second source produced phenotypic characteristics which were not identical with those that arose through traditional bioassay. These data show that differences in the efficiency of PMCA as a strain-typing tool may vary between ovine classical scrapie isolates and therefore suggest that the ability of PMCA to replace serial passage of classical scrapie in tg338 mice may depend on the strain present in the initial source.
Subject(s)
Biological Assay/methods , PrPSc Proteins/classification , Scrapie/metabolism , Animals , Genotype , Immunoenzyme Techniques , Immunohistochemistry , Mice , Mice, Transgenic , Molecular Typing , Phenotype , PrPSc Proteins/genetics , Protein Folding , Protein Isoforms , Scrapie/genetics , Sheep , TransgenesABSTRACT
In individual animals affected by transmissible spongiform encephalopathies, different disease phenotypes can be identified which are attributed to different strains of the agent. In the absence of reliable technology to fully characterise the agent, classification of disease phenotype has been used as a strain typing tool which can be applied in any host. This approach uses standardised data on biological parameters, established for a single host, to allow comparison of different prion sources. Traditionally prion strain characterisation in wild type mice is based on incubation periods and lesion profiles after the stabilisation of the agent into the new host which requires serial passages. Such analysis can take many years, due to prolonged incubation periods. The current study demonstrates that the PrPSc patterns produced by one serial passage in wild type mice of bovine or ovine BSE were consistent, stable and showed minimal and predictable differences from mouse-stabilised reference strains. This biological property makes PrPSc deposition pattern mapping a powerful tool in the identification and definition of TSE strains on primary isolation, making the process of characterisation faster and cheaper than a serial passage protocol. It can be applied to individual mice and therefore it is better suited to identify strain diversity within single inocula in case of co-infections or identify strains in cases where insufficient mice succumb to disease for robust lesion profiles to be constructed. The detailed description presented in this study provides a reference document for identifying BSE in wild type mice.
Subject(s)
Encephalopathy, Bovine Spongiform/genetics , PrPSc Proteins/genetics , Prion Diseases/veterinary , Animals , Brain/pathology , Cattle , Encephalopathy, Bovine Spongiform/etiology , Encephalopathy, Bovine Spongiform/pathology , Immunohistochemistry/veterinary , Mice , Paraffin Embedding/veterinary , PrPSc Proteins/metabolism , Prion Diseases/etiology , Prion Diseases/genetics , Prion Diseases/pathology , Retrospective Studies , SheepABSTRACT
Mouse bioassay can be readily employed for strain typing of naturally occurring transmissible spongiform encephalopathy cases. Classical scrapie strains have been characterised historically based on the established methodology of assessing incubation period of disease and the distribution of disease-specific vacuolation across the brain following strain stabilisation in a given mouse line. More recent research has shown that additional methods could be used to characterise strains and thereby expand the definition of strain "phenotype". Here we present the phenotypic characteristics of classical scrapie strains isolated from 24 UK ovine field cases through the wild-type mouse bioassay. PrPSc immunohistochemistry (IHC), paraffin embedded tissue blots (PET-blot) and Western blotting approaches were used to determine the neuroanatomical distribution and molecular profile of PrPSc associated with each strain, in conjunction with traditional methodologies. Results revealed three strains isolated through each mouse line, including a previously unidentified strain. Moreover IHC and PET-blot methodologies were effective in characterising the strain-associated types and neuroanatomical locations of PrPSc. The use of Western blotting as a parameter to define classical scrapie strains was limited. These data provide a comprehensive description of classical scrapie strain phenotypes on isolation through the mouse bioassay that can provide a reference for further scrapie strain identification.
Subject(s)
Biological Assay/methods , PrPSc Proteins/classification , Scrapie/metabolism , Animals , Blotting, Western/methods , Brain/metabolism , Immunohistochemistry/methods , Mice , Mice, Inbred C57BL , Molecular Typing/methods , Paraffin Embedding/methods , PrPSc Proteins/genetics , Scrapie/genetics , SheepABSTRACT
It is widely accepted that abnormal forms of the prion protein (PrP) are the best surrogate marker for the infectious agent of prion diseases and, in practice, the detection of such disease-associated (PrP(d)) and/or protease-resistant (PrP(res)) forms of PrP is the cornerstone of diagnosis and surveillance of the transmissible spongiform encephalopathies (TSEs). Nevertheless, some studies question the consistent association between infectivity and abnormal PrP detection. To address this discrepancy, 11 brain samples of sheep affected with natural scrapie or experimental bovine spongiform encephalopathy were selected on the basis of the magnitude and predominant types of PrP(d) accumulation, as shown by immunohistochemical (IHC) examination; contra-lateral hemi-brain samples were inoculated at three different dilutions into transgenic mice overexpressing ovine PrP and were also subjected to quantitative analysis by three biochemical tests (BCTs). Six samples gave 'low' infectious titres (106·5 to 106·7 LD50 g⻹) and five gave 'high titres' (108·¹ to ≥ 108·7 LD50 g⻹) and, with the exception of the Western blot analysis, those two groups tended to correspond with samples with lower PrP(d)/PrP(res) results by IHC/BCTs. However, no statistical association could be confirmed due to high individual sample variability. It is concluded that although detection of abnormal forms of PrP by laboratory methods remains useful to confirm TSE infection, infectivity titres cannot be predicted from quantitative test results, at least for the TSE sources and host PRNP genotypes used in this study. Furthermore, the near inverse correlation between infectious titres and Western blot results (high protease pre-treatment) argues for a dissociation between infectivity and PrP(res).
Subject(s)
Encephalopathy, Bovine Spongiform , Prions/genetics , Prions/pathogenicity , Scrapie , Animals , Biological Assay/methods , Brain , Cattle , Female , Immunohistochemistry , Male , Mice , SheepABSTRACT
A few cases of transmissible spongiform encephalopathies in sheep have been described in France in which the protease-resistant prion protein (PrP(res)) exhibited some features in Western blot of experimental bovine spongiform encephalopathy in sheep. Their molecular characteristics were indistinguishable from those produced in the CH1641 experimental scrapie isolate. Four of these CH1641-like isolates were inoculated intracerebrally into wild-type C57Bl/6 mice. In striking contrast to previous results in ovine transgenic mice, CH1641 transmission in wild-type mice was efficient. Several components of the strain signature, that is, PrP(res) profile, brain distribution, and morphology of the deposits of the disease-associated prion protein, had some similarities with "classical" scrapie and clearly differed from both bovine spongiform encephalopathy in sheep and CH1641 transmission in ovine transgenic mice. These results on CH1641-like isolates in wild-type mice may be consistent with the presence in these isolates of mixed conformers with different abilities to propagate and mediate specific disease phenotypes in different species.
Subject(s)
Brain/metabolism , Phenotype , PrPSc Proteins/genetics , PrPSc Proteins/metabolism , Scrapie/genetics , Animals , Brain/pathology , Female , Gene Expression Regulation/genetics , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Models, Animal , Scrapie/pathology , Sheep/genetics , Spleen/metabolism , Spleen/pathologyABSTRACT
Two cases of unusual transmissible spongiform encephalopathy (TSE) were diagnosed on the same farm in ARQ/ARQ PrP sheep showing attributes of both bovine spongiform encephalopathy (BSE) and scrapie. These cases, UK-1 and UK-2, were investigated further by transmissions to wild-type and ovine transgenic mice. Lesion profiles (LP) on primary isolation and subpassage, incubation period (IP) of disease, PrP(Sc) immunohistochemical (IHC) deposition pattern and Western blot profiles were used to characterize the prions causing disease in these sheep. Results showed that both cases were compatible with scrapie. The presence of BSE was contraindicated by the following: LP on primary isolation in RIII and/or MR (modified RIII) mice; IP and LP after serial passage in wild-type mice; PrP(Sc) deposition pattern in wild-type mice; and IP and Western blot data in transgenic mice. Furthermore, immunohistochemistry (IHC) revealed that each case generated two distinct PrP(Sc) deposition patterns in both wild-type and transgenic mice, suggesting that two scrapie strains coexisted in the ovine hosts. Critically, these data confirmed the original differential IHC categorization that these UK-1 and UK-2 cases were not compatible with BSE.
Subject(s)
Brain/metabolism , Encephalopathy, Bovine Spongiform/diagnosis , PrPSc Proteins/metabolism , Scrapie/diagnosis , Animals , Biological Assay , Brain/pathology , Cattle , Diagnosis, Differential , Encephalopathy, Bovine Spongiform/pathology , Mice , Mice, Transgenic , PrPSc Proteins/genetics , Scrapie/pathology , SheepABSTRACT
Transmissible spongiform encephalopathies are fatal neurodegenerative diseases that include variant Creutzfeldt-Jakob disease in humans, scrapie in small ruminants, and bovine spongiform encephalopathy (BSE) in cattle. Scrapie is not considered a public health risk, but BSE has been linked to variant Creutzfeldt-Jakob disease. Small ruminants are susceptible to BSE, and in 2005 BSE was identified in a farmed goat in France. We confirm another BSE case in a goat in which scrapie was originally diagnosed and retrospectively identified as suspected BSE. The prion strain in this case was further characterized by mouse bioassay after extraction from formaldehyde-fixed brain tissue embedded in paraffin blocks. Our data show that BSE can infect small ruminants under natural conditions and could be misdiagnosed as scrapie. Surveillance should continue so that another outbreak of this zoonotic transmissible spongiform encephalopathy can be prevented and public health safeguarded.
Subject(s)
Encephalopathy, Bovine Spongiform/transmission , Goat Diseases/transmission , Goats , Prions/isolation & purification , Animals , Animals, Domestic , Biological Assay , Brain/pathology , Brain Chemistry , Cattle , Communicable Diseases, Emerging/diagnosis , Communicable Diseases, Emerging/transmission , Communicable Diseases, Emerging/veterinary , Encephalopathy, Bovine Spongiform/diagnosis , Goat Diseases/diagnosis , Humans , Mice , Mice, Inbred C57BL , Mice, Transgenic , PrPSc Proteins/isolation & purification , PrPSc Proteins/pathogenicity , Prions/pathogenicity , Scrapie/diagnosis , Scrapie/transmission , United KingdomABSTRACT
It is currently believed that primary transmission of classical scrapie to wild-type mice is inefficient and characterized by low attack rates and variable incubation periods and lesion profiles. Consequently, strain characterization of classical scrapie in these mice relies on subpassage. The aim of this study was to perform a retrospective analysis of lesion profiles and immunohistochemistry patterns after transmission of a large number of classical scrapie sources to wild-type mice and to investigate trends that might be used to characterize the agent without subpassaging. Scrapie field cases (n = 31) collected from individual farms between 1996 and 1999 were inoculated into RIII, C57BL, and VM mice and profiled using standard methodology and analyzed by immunohistochemistry. Using cluster analysis to resultant lesion profiles produced groups of similar lesion profiles in RIII and C57BL mice. We observed correlations between lesion profile clusters and the ovine prion protein (PrP) genotype. Immunohistochemistry indicated donor-mediated trends in the PrP pattern. These results indicate that ovine PrP genotype is a factor that is linked to both the lesion profile and the pattern of PrP deposition on primary transmission of classical scrapie to wild-type mice.
Subject(s)
Brain/metabolism , Brain/pathology , Immunohistochemistry/methods , PrPSc Proteins , Scrapie , Animals , Cell Count/methods , Cluster Analysis , Disease Models, Animal , Genotype , Mice , Mice, Inbred C57BL , Mice, Transgenic , Nerve Tissue Proteins/metabolism , Neurons/metabolism , PrPSc Proteins/classification , PrPSc Proteins/genetics , PrPSc Proteins/metabolism , Receptors, IgG/genetics , Retrospective Studies , Scrapie/genetics , Scrapie/pathology , Scrapie/transmission , SheepABSTRACT
Primary isolation of bovine spongiform encephalopathy (BSE) in RIII mice generates a lesion profile believed to be reproducible and distinct from that produced by classical scrapie. This profile, which is characterized by peaks at gray matter areas 1, 4 and 7 (dorsal medulla, hypothalamus and septal nuclei), is used to diagnose BSE on primary isolation. The aim of this study was to investigate whether the BSE agent could be present in sheep diagnosed with classical scrapie, using lesion profiles in RIII mice as a discriminatory method. Sixty-two positive scrapie field cases were collected from individual farms between 1996 and 1999 and bioassayed in RIII mice. Fifty-five of these isolates transmitted successfully to at least one mouse. Of the 31 that produced adequate data to allow lesion profile analysis, 10 showed a consistent profile with peaks at brain areas 1, 4 and 7. All inocula for this subgroup were derived from sheep of genotype ARQ/ARQ. While the 1-4-7-scrapie profile exhibited similarities to BSE in RIII mice at primary isolation, it was distinguishable based on histopathology, immunohistochemistry and cluster analysis. We conclude that caution should be taken to distinguish this profile from BSE and that additional parameters should be considered to reach a final diagnosis.
Subject(s)
Brain/pathology , Encephalopathy, Bovine Spongiform/diagnosis , Encephalopathy, Bovine Spongiform/pathology , PrPSc Proteins/analysis , Scrapie/diagnosis , Scrapie/pathology , Animals , Blotting, Western , Brain/metabolism , Brain Chemistry , Cattle , Cattle Diseases/diagnosis , Cattle Diseases/pathology , Cluster Analysis , Diagnosis, Differential , Encephalopathy, Bovine Spongiform/genetics , Immunohistochemistry , Mice , Nerve Fibers, Unmyelinated/chemistry , Nerve Fibers, Unmyelinated/pathology , PrPSc Proteins/isolation & purification , Scrapie/genetics , Sheep , Sheep Diseases/diagnosis , Sheep Diseases/genetics , Sheep Diseases/pathology , Survival AnalysisABSTRACT
In response to a conditioning stress, the expression of a set of molecular chaperones called heat shock proteins is increased. In neurons, stress-induced and constitutively expressed molecular chaperones protect against damage induced by ischemia and neurodegenerative diseases, however the molecular basis of this protection is not known. Here we have investigated the crosstalk between stress-induced chaperones and cysteine string protein (CSPalpha). CSPalpha is a constitutively expressed synaptic vesicle protein bearing a J domain and a cysteine rich "string" region that has been implicated in the long term functional integrity of synaptic transmission and the defense against neurodegeneration. We have shown previously that the CSPalpha chaperone complex increases isoproterenol-mediated signaling by stimulating GDP/GTP exchange of Galpha(s). In this report we demonstrate that in response to heat shock or treatment with the Hsp90 inhibitor geldanamycin, the J protein Hsp40 becomes a major component of the CSPalpha complex. Association of Hsp40 with CSPalpha decreases CSPalpha-CSPalpha dimerization and enhances the CSPalpha-induced increase in steady state GTP hydrolysis of Galpha(s). This newly identified CSPalpha-Hsp40 association reveals a previously undescribed coupling of J proteins. In view of the crucial importance of stress-induced chaperones in the protection against cell death, our data attribute a role for Hsp40 crosstalk with CSPalpha in neuroprotection.
Subject(s)
HSP40 Heat-Shock Proteins/metabolism , Heat-Shock Response , Membrane Proteins/metabolism , Animals , Benzoquinones/pharmacology , Cell Line, Tumor , Lactams, Macrocyclic/pharmacology , Mice , Molecular Chaperones , Multiprotein Complexes , Neuroblastoma/pathology , Protein Binding , Protein Multimerization , Receptor Cross-TalkABSTRACT
A number of structurally divergent proteins with J domains, called J proteins, interact with and activate the ATPase of Hsp70s, thereby harnessing the ATPase activity for conformational work on target proteins. The precise role of most mammalian J proteins remains undefined. In this paper, we demonstrate that transient expression of the J protein, Rdj2, in HEK 293 cells increased cellular cyclic adenosine monophosphate (cAMP) levels in the presence of the beta-adrenergic agonist isoproterenol. In CNS-derived catecholaminergic neuronal cell line (CAD) neuroblastoma cells, expression of Rdj2 increased isoproterenol-stimulated phosphorylation of cAMP response element binding protein (CREB). Moreover, we have characterized the binding properties of Rdj2 and observed a direct interaction between Rdj2 and receptor-coupled trimeric GTP-binding proteins (G proteins). We further show that the composition of the Rdj2-chaperone complex and the cysteine string protein (CSPalpha)-chaperone complex, another J protein, is distinct. Our data demonstrate that Rdj2 modulates G protein signaling and further suggest that chaperoning G proteins is an emerging theme of the J protein network.
Subject(s)
GTP-Binding Proteins/metabolism , HSP40 Heat-Shock Proteins/metabolism , Molecular Chaperones/metabolism , Nervous System/metabolism , Signal Transduction , Amino Acid Sequence , Animals , Brain/drug effects , Brain/metabolism , Cell Line , Cyclic AMP/metabolism , Cyclic AMP Response Element-Binding Protein/metabolism , Escherichia coli/metabolism , Estrogens/pharmacology , HSC70 Heat-Shock Proteins/metabolism , HSP110 Heat-Shock Proteins/metabolism , HSP40 Heat-Shock Proteins/chemistry , HSP90 Heat-Shock Proteins/metabolism , Mice , Molecular Chaperones/chemistry , Molecular Sequence Data , Nervous System/drug effects , Neuroblastoma/metabolism , Phosphorylation/drug effects , Protein Binding/drug effects , Rats , Signal Transduction/drug effectsABSTRACT
Mitochondrial impairment, glutathione depletion and oxidative stress have been implicated in the pathogenesis of Parkinson's disease (PD), linked recently to proteasomal dysfunction. Our study analysed how these factors influence the various activities of the proteasome in human SH-SY5Y neuroblastoma cells treated with the PD mimetics MPP+ (a complex 1 inhibitor) or dopamine. Treatment with these toxins led to dose- and time-dependent reductions in ATP and glutathione and also chymotrypsin-like and post-acidic like activities; trypsin-like activity was unaffected. Antioxidants blocked the effects of dopamine, but not MPP+, suggesting that oxidative stress was more important in the dopamine-mediated effects. With MPP+, ATP depletion was a prerequisite for loss of proteasomal activity. Thus in a dopaminergic neuron with complex 1 dysfunction both oxidative stress and ATP depletion will contribute independently to loss of proteasomal function. We show for the first time that addition of MPP+ or dopamine to purified samples of the human 20S proteasome also reduced proteasomal activities; with dopamine being most damaging. As with toxin-treated cells, chymotrypsin-like activity was most sensitive and trypsin-like activity the least sensitive. The observed differential sensitivity of the various proteasomal activities to PD mimetics is novel and its significance needs further study in human cells.
Subject(s)
1-Methyl-4-phenylpyridinium/pharmacology , Dopamine/pharmacology , Proteasome Endopeptidase Complex/drug effects , Proteasome Endopeptidase Complex/metabolism , Adenosine Triphosphate/metabolism , Cell Line, Tumor , Cell Survival/drug effects , Chymotrypsin/metabolism , Dose-Response Relationship, Drug , Drug Interactions , Glutathione/metabolism , Humans , Neuroblastoma/metabolism , Neuroblastoma/pathology , Reactive Oxygen Species/metabolism , Time FactorsABSTRACT
Cysteine string protein (CSPalpha) is a member of the cellular folding machinery that is located on regulated secretory vesicles. We have previously shown that CSPalpha in association with Hsc70 (70kDa heat shock cognate protein) and SGT (small glutamine-rich tetratricopeptide repeat domain protein) is a guanine nucleotide exchange factor (GEF) for G(alphas). Association of this CSPalpha complex with N-type calcium channels, a channel key in coupling calcium influx with synaptic vesicle exocytosis, triggers tonic G protein inhibition of the channels. Syntaxin 1A, a plasma membrane SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) critical for neurotransmission, coimmunoprecipitates with the CSPalpha/G protein/N-type calcium channel complex, however the significance of syntaxin 1A as a component of this complex remains unknown. In this report, we establish that syntaxin 1A interacts with CSPalpha, Hsc70 as well as the synaptic protein interaction (synprint) region of N-type channels. We demonstrate that huntingtin(exon1), a putative biologically active fragment of huntingtin, displaces both syntaxin 1A and CSPalpha from N-type channels. Identification of the protein components of the CSPalpha/GEF system is essential in establishing its precise role in synaptic transmission.
Subject(s)
HSC70 Heat-Shock Proteins/chemistry , HSP40 Heat-Shock Proteins/chemistry , Membrane Proteins/chemistry , Synaptic Transmission , Syntaxin 1/chemistry , Animals , Binding Sites , Exons , Guanine Nucleotide Exchange Factors/chemistry , Guanine Nucleotide Exchange Factors/genetics , Guanine Nucleotide Exchange Factors/metabolism , HSC70 Heat-Shock Proteins/metabolism , HSP40 Heat-Shock Proteins/metabolism , Membrane Proteins/metabolism , Models, Molecular , Multiprotein Complexes/chemistry , Multiprotein Complexes/metabolism , Nerve Tissue Proteins/chemistry , Nerve Tissue Proteins/genetics , Peptide Fragments/chemistry , Peptide Fragments/metabolism , Protein Binding , Protein Transport , Rats , SNARE Proteins/metabolism , Syntaxin 1/metabolismABSTRACT
Tissue transglutaminase (TG2) can induce post-translational modification of proteins, resulting in protein cross-linking or incorporation of polyamines into substrates, and can also function as a signal transducing G protein. The role of TG2 in the formation of insoluble cross-links has led to its implication in some neurodegenerative conditions. Exposure of pre-differentiated SH-SY5Y cells to the Parkinsonian neurotoxin 1-methyl-4-phenylpyridinium ion (MPP(+)) resulted in significant dose-dependent reductions in TG2 protein levels, measured by probing Western blots with a TG2-specific antibody. Transglutaminase (TG) transamidating activity, on the other hand, monitored by incorporation of a polyamine pseudo-substrate into cellular proteins, was increased. Inhibitors of TG (putrescine) and TG2 (R283) exacerbated MPP(+) toxicity, suggesting that activation of TG2 may promote a survival response in this toxicity paradigm.
Subject(s)
1-Methyl-4-phenylpyridinium/toxicity , Transglutaminases/physiology , Cell Differentiation , Cell Line, Tumor , Cell Survival/drug effects , GTP-Binding Proteins , Humans , Imidazoles/pharmacology , Neuroblastoma , Parkinson Disease/enzymology , Polyamines/metabolism , Protein Glutamine gamma Glutamyltransferase 2 , Putrescine/pharmacology , Transglutaminases/antagonists & inhibitors , Transglutaminases/metabolismABSTRACT
PrP(C) is a glycosylphosphatidylinositol (GPI) anchored glycoprotein of unknown function. Misfolding of normal cellular PrP(C) to the pathogenic PrP(Sc) is the hallmark of prion diseases (transmissible spongiform encephalopathies). Prion diseases are characterized by extensive neurodegeneration and early death. Understanding how PrP(C) maintains its correct conformation is a major endeavor of current inquiry. Here we demonstrate a novel interaction between PrP(C) and the J protein family member, Rdj2 (DjA2; Dj3, Dnj3, Cpr3, and Hirip4). The importance of the J protein family in the cellular folding machinery has been recognized for many years. The PrP(C)/Rdj2 association was direct and concentration-dependent. Other J proteins such as CSPalpha and auxilin did not associate with PrP(C) in the absence of ATP, demonstrating the specificity of the PrP(C)/J protein interaction. These findings suggest that the J protein family serves as a 'folding catalyst' for PrP(C) and implicates Rdj2 as a factor in the protection against prion diseases.