1.
Applications of isothermal titration calorimetry in pure and applied research-survey of the literature from 2010.
Source
Institute for Molecular Bioscience (IMB), University of Queensland, St. Lucia, Queensland, 4072, Australia.
Abstract
Isothermal titration calorimetry (ITC) is a biophysical technique for measuring the formation and dissociation of molecular complexes and has become an invaluable tool in many branches of science from cell biology to food chemistry. By measuring the heat absorbed or released during bond formation, ITC provides accurate, rapid, and label-free measurement of the thermodynamics of molecular interactions. In this review, we survey the recent literature reporting the use of ITC and have highlighted a number of interesting studies that provide a flavour of the diverse systems to which ITC can be applied. These include measurements of protein-protein and protein-membrane interactions required for macromolecular assembly, analysis of enzyme kinetics, experimental validation of molecular dynamics simulations, and even in manufacturing applications such as food science. Some highlights include studies of the biological complex formed by Staphylococcus aureus enterotoxin C3 and the murine T-cell receptor, the mechanism of membrane association of the Parkinson's disease-associated protein α-synuclein, and the role of non-specific tannin-proteininteractions in the quality of different beverages. Recent developments in automation are overcoming limitations on throughput imposed by previous manual procedures and promise to greatly extend usefulness of ITC in the future. We also attempt to impart some practical advice for getting the most out of ITC data for those researchers less familiar with the method. Copyright © 2011 John Wiley & Sons, Ltd.
Copyright © 2011 John Wiley & Sons, Ltd.
- PMID:
- 22213449
- [PubMed - in process]
Transglutaminase 2: Biology, Relevance to Neurodegenerative Diseases and Therapeutic Implications.
Abstract
Neurodegenerative disorders are characterized by progressive neuronal loss and the aggregation of disease-specific pathogenic proteins in hallmark neuropathologic lesions. Many of these proteins, including amyloid Αβ, tau, α-synucleinand huntingtin, are cross-linked by the enzymatic activity of transglutaminase 2 (TG2). Additionally, the expression and activity of TG2 is increased in affected brain regions in these disorders. These observations along with experimental evidence in cellular and mouse models suggest that TG2 can contribute to the abnormal aggregation of disease causingproteins and consequently to neuronal damage. This accumulating evidence has provided the impetus to develop inhibitors of TG2 as possible neuroprotective agents. However, TG2 has other enzymatic activities in addition to its cross-linking function and can modulate multiple cellular processes including apoptosis, autophagy, energy production, synaptic function, signal transduction and transcription regulation. These diverse properties must be taken into consideration in designing TG2 inhibitors. In this review, we discuss the biochemistry of TG2, its various physiologic functions and our current understanding about its role in degenerative diseases of the brain. We also describe the different approaches to designing TG2 inhibitors that could be developed as potential disease-modifying therapies.
Copyright © 2011. Published by Elsevier Inc.
- PMID:
- 22212614
- [PubMed - as supplied by publisher]
Melatonin attenuates kainic acid-induced neurotoxicity in mouse hippocampus via inhibition of autophagy and α-synuclein aggregation.
Source
Institute of Pharmacology, National Yang-Ming University, Taipei, Taiwan Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan Institute of Physiology Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taipei, Taiwan.
Abstract
In this study, the protective effect of melatonin on kainic acid (KA)-induced neurotoxicity involving autophagy and α-synuclein aggregation was investigated in the hippocampus of C57/BL6 mice. Our data showed that intraperitoneal injection of KA (20 mg/kg) increased LC3-II levels (a hallmark protein of autophagy) and reduced mitochondrial DNA content and cytochrome c oxidase levels (a protein marker of mitochondria). Atg7 siRNA transfection prevented KA-induced LC3-II elevations and mitochondria loss. Furthermore, Atg7 siRNA attenuated KA-induced activation of caspases 3/12 (biomarkers of apoptosis) and hippocampal neuronal loss, suggesting a pro-apoptotic role of autophagy in the KA-induced neurotoxicity. Nevertheless, KA-induced α-synuclein aggregation was not affected in the Atg7 siRNA-transfected hippocampus. The neuroprotective effect of melatonin (50 mg/kg) orally administered 1 hr prior to KA injection was studied. Melatonin was found to inhibit KA-induced autophagy-lysosomal activation by reducing KA-induced increases in LC3-II, lysosomal-associated membrane protein 2 (a biomarker of lysosomes) and cathepsin B (a lysosomal cysteine protease). Subsequently, KA-induced mitochondria loss was prevented in the melatonin-treated mice. At the same time, melatonin reduced KA-increased HO-1 levels and α-synuclein aggregation. Our immunoprecipitation study showed that melatonin enhanced ubiquitination of α-synuclein monomers and aggregates. The anti-apoptotic effect of melatonin was demonstrated by attenuating KA-induced DNA fragmentation, activation of caspases 3/12, and neuronal loss. Taken together, our study suggests that KA-induced neurotoxicity may be mediated by autophagy and α-synuclein aggregation. Moreover, melatonin may exert its neuroprotection via inhibiting KA-induced autophagy and a subsequent mitochondrial loss as well as reducing α-synuclein aggregation by enhancing α-synucleinubiquitination in the CNS.
© 2011 John Wiley & Sons A/S.
- PMID:
- 22212051
- [PubMed - as supplied by publisher]
α-Synuclein induces both positive mean curvature and negative Gaussian curvature in membranes.
Abstract
Using a combination of x-ray scattering, fluorescence correlation spectroscopy, coarse-grained molecular dynamics (MD) simulations and potential of mean force (PMF) calculations, we have explored the membrane remodeling effects of monomeric α-Synuclein (αS). Our initial findings from multiple approaches, are that αS 1) causes a significant thinning of the bilayer; and 2) stabilizes positive mean curvature, such that the maximum principle curvature matches that of synaptic vesicles, αS-induced tubules and the synthetic lipid vesicles to which the protein binds most tightly. This suggests that αS binding to synaptic vesicles likely stabilizes their intrinsic curvature. We then show that αS induces local negative Gaussian curvature, an effect that occurs in regions of αS shown previously via NMR and corroborated by MD simulation to have significant conformational flexibility. The induction of negative Gaussian curvature, which has implications for all curvature-sensing and curvature-generating amphipathic α-helices, supports a hypothesis that connects helix insertion to fusion and fission of vesicles, processes that have recently been linked to αS function. Then, in an effort to explain these biophysical properties of αS, we promote an intrinsic curvature-field model that recasts long-range protein-protein interactions in terms of the interactions between the local curvature-fields generated by lipid-proteincomplexes.
- PMID:
- 22211521
- [PubMed - as supplied by publisher]
Peculiarities of copper binding to alpha-synuclein.
Source
Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA. ahmadatt@umich.edu.
Abstract
Heavy metals have been implicated as the causative agents for the pathogenesis of the most prevalent neurodegenerative disease. Various mechanisms have been proposed to explain the toxic effects of metals ranging from metal-induced oxidation of protein to metal-induced changes in the protein conformation. Aggregation of a-synuclein is implicated in Parkinson's disease (PD), and various metals, including copper, constitute a prominent group of alpha-synuclein aggregation enhancers. In this study, we have systematically characterized the a-synuclein-Cu21 binding sites and analyzed the possible role of metal binding in a-synuclein fibrillation using a set of biophysical techniques, such as electron paramagnetic resonance (EPR), electron spin-echo envelope modulation (ESEEM), circular dichroism (CD), and size exclusion chromatography (SEC). Our analyses indicated that a-synuclein possesses at least two binding sites for Cu21. We have been able to locate one of the binding sites in the N-terminal region. Furthermore, based on the EPR studies of model peptides and Beta-synuclein, we concluded that the suspected His residue did not appear to participate in strong Cu21 binding.
Altered CSF Orexin and α-Synuclein Levels in Dementia Patients.
Source
Molecular Memory Research Unit, The Wallenberg Lab, Lund University, Department of Clinical Sciences Malmö, Sweden.
Abstract
Neurodegenerative dementia, most frequently represented by Alzheimer's disease (AD) and dementia with Lewy bodies (DLB), is often accompanied by altered sleeping patterns and excessive daytime sleepiness. Studies showing an association between the neuropeptide orexin and AD/DLB-related processes such as amyloid-β (Aβ)1-42 plaque formation, α-synuclein accumulation, and inflammation indicate that orexin might play a pathogenic role similar to the situation in narcolepsy. Our study of patients with AD (n = 26), DLB (n = 18), and non-demented controls (n = 24) shows a decrease in cerebrospinal fluid (CSF) orexin concentrations in DLB versus AD patients and controls. The observed differences in orexin levels were found to be specific to female DLB patients. We also show that the female DLB patients exclusively displayed lower levels of α-synuclein compared to AD patients and controls. Orexin was linked to α-synuclein and total-tau in female non-demented controls whereas associations between orexin and Aβ1-42 concentrations were absent in all groups regardless of gender. Thus, the proposed links between orexin, Aβ, and α-synuclein pathology could not be monitored in CSF protein concentrations. Interestingly, α-synuclein was strongly correlated to the CSF levels of total-tau in all groups, suggesting α-synuclein to be an unspecific marker of neurodegeneration. We conclude that lower levels of CSF orexin are specific to DLB versus AD and appear unrelated to Aβ1-42 and α-synuclein levels in AD and DLB. Alterations in CSF orexin and α-synuclein levels may be related to gender which warrants further investigation.
Tau reduction does not prevent motor deficits in two mouse models of Parkinson's disease.
Source
Gladstone Institute of Neurological Disease, San Francisco, California, United States of America.
Abstract
Many neurodegenerative diseases are increasing in prevalence and cannot be prevented or cured. If they shared common pathogenic mechanisms, treatments targeting such mechanisms might be of benefit in multiple conditions. The tau protein has been implicated in the pathogenesis of diverse neurodegenerative disorders, including Alzheimer's disease (AD) and Parkinson's disease (PD). Tau reduction prevents cognitive deficits, behavioral abnormalities and other pathological changes in multiple AD mouse models. Here we examined whether tau reduction also prevents motor deficits and pathological alterations in two mouse models of PD, generated by unilateral striatal injection of 6-hydroxydopamine (6-OHDA) or transgene-mediated neuronal expression of human wildtype α-synuclein. Both models were evaluated on Tau(+/+), Tau(+/-) and Tau(-/-) backgrounds in a variety of motor tests. Tau reduction did not prevent motor deficits caused by 6-OHDA and slightly worsened one of them. Tau reduction also did not prevent 6-OHDA-induced loss of dopaminergic terminals in the striatum. Similarly, tau reduction did not prevent motor deficits in α-synuclein transgenic mice. Our results suggest that tau has distinct roles in the pathogeneses of AD and PD and that tau reduction may not be of benefit in the latter condition.
Targeting Skp1, an Ubiquitin E3 Ligase Component Found Decreased in Sporadic Parkinson's Disease.
Source
Eve Topf Center for Neurodegenerative Diseases Research and Department of Molecular Pharmacology, Faculty of Medicine, Technion, Haifa, Israel.
Abstract
Microarray-derived transcriptomic studies in human substantia nigra pars compacta (SNpc) samples from sporadic Parkinson's disease (SPD) cases have opened an avenue to concentrate on potential gene intersections or cross-talks along the dopaminergic (DAergic) neurodegenerative cascade in SPD. One emerging gene candidate identified by our group was SKP1A (p19, S-phase kinase-associated protein 1A), found significantly decreased in the SNpc. It is part of the SCF (Skp1, Cullin 1, F-box protein) complex, the largest class of sophisticated ubiquitin-proteasome/E3 ligases, and can directly interact with Fbxo7, a gene defective in PARK15-linked PD. In vitro target validation by viral-mediated RNA interference revealed that the deficiency of Skp1 in a mouse SN-derived DAergic neuronal cell line potentiated the damage caused by exogenous insults implicated in PD pathology and caused the death of neurons undergoing differentiation, which developed Lewy body-like, α-synuclein-positive inclusions preceding cell death. Furthermore, recent animal studies show that site-directed intranigral stereotaxic injections of lentiviruses targeting SKP1A induce pathological and behavioral deficits in mice, supporting a significant role of Skp1 in SN DAergic neuronal survival in SPD. Thus, strategies aimed at increasing the activity or content of Skp1 may represent a novel therapeutic approach that has the potential to treat PD.
Copyright © 2011 S. Karger AG, Basel.
Regulation of Physiologic Actions of LRRK2: Focus on Autophagy.
Source
Department of Pharmacology, Boston University School of Medicine, Boston, Mass., USA.
Abstract
Background: Mutations in LRRK2 are associated with familial and sporadic Parkinson's disease (PD). Subjects with PD caused by LRRK2 mutations show pleiotropic pathology that can involve inclusions containing α-synuclein, tau or neither protein. The mechanisms by which mutations in LRRK2 lead to this pleiotropic pathology remain unknown. Objectives: To investigate mechanisms by which LRRK2 might cause PD. Methods: We used systems biology to investigate the transcriptomes from human brains, human blood cells and Caenorhabditis elegans expressing wild-type LRRK2. The role of autophagy was tested in lines of C. elegans expressing LRRK2, V337M tau or both proteins. Neuronal function was measured by quantifying thrashing. Results: Genes regulating autophagy were coordinately regulated with LRRK2. C. elegans expressing V337M tau showed reduced thrashing, as has been noted previously. Coexpressing mutant LRRK2 (R1441C or G2019S) with V337M tau increased the motor deficits. Treating the lines of C. elegans with an mTOR inhibitor that enhances autophagic flux, ridaforolimus, increased the thrashing behavior to the same level as nontransgenic nematodes. Conclusion: These data support a role for LRRK2 in autophagy, raise the possibility that deficits in autophagy contribute to the pathophysiology of LRRK2, and point to a potential therapeutic approach addressing the pathophysiology of LRRK2 in PD.
Copyright © 2011 S. Karger AG, Basel.
Development and characterization of a novel rat model of Parkinson's disease induced by sequential intranigral administration of AAV-α-synuclein and the pesticide, rotenone.
Source
Department of Pharmacology and Therapeutics, National University of Ireland, Galway, Ireland; National Centre for Biomedical Engineering Science, National University of Ireland, Galway, Ireland.
Abstract
Modeling Parkinson's disease remains a major challenge for preclinical researchers, as existing models fail to reliably recapitulate all of the classic features of the disease, namely, the progressive emergence of a bradykinetic motor syndrome with underlying nigrostriatal α-synuclein accumulation protein and nigrostriatal neurodegeneration. One limitation of the existing models is that they are normally induced by a single neuropathological insult, whereas the human disease is thought to be multifactorial with genetic and environmental factors contributing to the disease pathogenesis. Thus, in order to develop a more relevant model, we sought to determine if administration of the Parkinson's disease-associated pesticide, rotenone, into the substantia nigra of rats overexpressing the Parkinson's disease-associated protein, α-synuclein, could reliably model the triad of classic features of the human disease. To do so, rats underwent stereotaxic surgery for unilateral delivery of AAV-α-synuclein into the substantia nigra. This was followed 13 weeks later by delivery of rotenone into the same site. The effect of the genetic and environmental insults alone or in combination on lateralized motor performance (Corridor, Stepping, and Whisker Tests), nigrostriatal integrity (tyrosine hydroxylase immunohistochemistry), and α-synucleinopathy (α-synuclein immunohistochemistry) was assessed. We found that rats treated with either AAV-α-synuclein or rotenone developed significant motor dysfunction with underlying nigrostriatal neurodegeneration. However, when the genetic and environmental insults were sequentially administered, the detrimental impact of the combined insults on motor performance and nigrostriatal integrity was significantly greater than the impact of either insult alone. This indicates that sequential exposure to relevant genetic and environmental insults is a valid approach to modeling human Parkinson's disease in the rat.
Copyright © 2011. Published by Elsevier Ltd.
Studies of protein aggregation in A53T α-synuclein transgenic, Tg2576 transgenic, and P246L presenilin-1 knock-in cross bred mice.
Source
Department of Pharmacology, University of Pennsylvania, Philadelphia, PA, USA.
Abstract
Synucleinopathies are a group of neurodegenerative disorders, including Parkinson disease, associated with neuronal amyloid inclusions comprised of the presynaptic protein α-synuclein (α-syn); however the biological events that initiate and lead to the formation of these inclusions are still poorly understood. There is mounting evidence that intracellular α-syn aggregation may proceed via a seeding mechanism and could spread between neurons through a prion-like mechanism that may involve other amyloidogenic proteins. Several lines of evidence suggest that Aβ peptides and/or extracellular Aβ deposits may directly or indirectly promote intracellular α-syn aggregation. To assess the effects of Aβ peptides and extracellular Aβ deposits on α-syn aggregate formation, transgenic mice (line M83) expressing A53T human α-syn that are sensitive to developing α-syn pathological inclusions were cross bred to Tg2576 transgenic mice that generated elevated levels of Aβ peptides and develop abundant Aβ plaques. In addition these mice were bred to mice with the P264L presenilin-1 knock-in mutation that further promotes Aβ plaque formation. These mice demonstrated the expected formation of Aβ plaques; however despite the accumulation of hyperphosphorylated α-syn dystrophic neurites within or surrounding Aβ plaques, no additional α-syn pathologies were observed. These studies show that Aβ amyloid deposits can cause the local aggregation of α-syn, but these did not lead to more extensive α-syn pathology.
Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.
Molecular pathways in sporadic PD.
Source
Neurogenetics Unit, CSS-Mendel Institute, Rome, Italy; Department of Medical and Surgical Pediatrie Sciences, University of Messina, Messina, Italy.
Abstract
Over the last decade, several autosomal dominant and recessive genes causative of Parkinson's disease (PD) have been identified. The functional studies on their protein products and the pathogenetic effect related to their mutations have greatly contributed to understand the many cellular pathways leading to neurodegeneration, that include oxidative stress damage, mitochondrial dysfunction, misfolded protein stress and impairment of cellular clearance systems, namely the ubiquitin-proteasome system (UPS) and the autophagy pathway. Although mendelian genes are responsible only for a small subset of PD patients, it is expected that the same pathogenetic mechanisms could play a relevant role also in the more frequent sporadic PD, that is currently recognized as a multifactorial disorder. In this model, different genetic and environmental factors, either playing a protective or a susceptibility role, variably interact to reach a threshold of disease over which PD will become clinically manifest. As an example, mutations or multiplication of the alpha-synuclein gene cause autosomal dominant PD, while common genetic variants at the same locus have been consistently associated to the risk of developing PD by genome-wide association studies. These findings are opening novel interesting perspectives to identify critical molecular pathways leading to neurodegeneration.
Copyright © 2011 Elsevier Ltd. All rights reserved.
Autosomal dominant Parkinson's disease.
Source
Department of Neurology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224, USA.
Abstract
Over the past two decades the understanding and classification of Parkinson's disease (PD) has been revolutionized by genetic research. Currently, sixteen PARK loci have been identified with autosomal dominant genes such as SNCA, and LRRK2, and autosomal recessive genes such as PRKN, DJ-1, and PINK1. Among these genes, LRRK2 is the most prevalent. Additionally, susceptibility variants located on some of these genes are widely recognized as risk factors for PD in certain ethnic populations. Alpha synuclein Lewy body (LB) pathology, the hallmark of sporadic PD, is predominantly seen in carriers of SNCA and LRRK2. Recently two new autosomal dominant PD genes have been discovered, eukaryotic translation initiation factor 4-gamma (EIF4G1) and vacuolar protein sorting 35 (VPS35). EIF4G1 is associated with LB pathology; however, only limited data currently exists on pathology of the VPS35. Thus, it remains to be seen if LB pathology can be identified on autopsy examination of carriers of VPS35 gene. The mechanism behind the cause of PD has yet to be elucidated; however, genetic studies on autosomal dominant PD have provided novel insights into the potential etiology of PD. Thus, paving the way for future targeted therapies aimed at disease prevention and cure.
Copyright © 2011 Elsevier Ltd. All rights reserved.
Neuronal vulnerability in Parkinson's disease.
Source
Neurosdence Research Australia and the University of New South Wales, Sydney, NSW, 2031, Australia.
Abstract
The classic motor symptoms of Parkinson's disease result from the progressive death of dopaminergic neurons within the substantia nigra. To date the relatively selective vulnerability of this brain region is not understood. The unique feature of dopaminergic neurons of the human substantia nigra pars compacta is the presence of the polymer pigment neuromelanin which gives this region its characteristic dark colour. In the healthy brain, neuromelanin appears to play a functional role to protect neurons from oxidative load but we have shown that in the Parkinson's disease brain the pigment undergoes structural changes and is associated with aggregation of α-synuclein protein, even early in the disease process. Further, the role of the pigment as a metal binder has also been suggested to underlie the relative vulnerability of these neurons, as changes in metal levels are suggested to be associated with neurodegenerative cascades in Parkinson's disease. While most research to date has focused on the role of iron in these pathways we have recently shown that changes in copper may contribute to neuronal vulnerability in this disorder.
Copyright © 2011 Elsevier Ltd. All rights reserved.
Patterns of alpha-synuclein pathology in incidental cases and clinical subtypes of Parkinson's disease.
Source
Department of Anatomy and Neurostiences, Neurostience Campus Amsterdam, VU University Medical Center, Amsterdam, the Netherlands.
Abstract
Parkinson's disease (PD) is characterized by a gradual accumulation of neuropathology that may begin many years before a clinical diagnosis can be made using currently accepted criteria. Here, we first review the prevalence of alpha-synuclein neuropathology in elderly and discuss its clinical relevance in Parkinson patients. Subsequently, the results of a retrospective study focussing on the distribution of neuropathology in Parkinson patients with a tremor-dominant (TD), non-tremordominant (NTD) or rapid disease progression (RDP) subtype are presented. The study population recruited by the Netherlands Brain bank consisted of 149 non-neurological donors, 26 donors with incidental Lewy body disease (iLBD) and 111 Parkinson patients. In total, 89% of these cases could be classified in accordance with the Braak staging when taking into account the severity of alpha-synuclein pathology and adding an amygdala-predominant category of synucleinopathy. The pathological progression seemed to be non-linear. Interestingly, a strong correlation between neuronal loss and alpha-synuclein pathology was observed in the substantia nigra in Braak stages 3-6 (P < 0.01). However, there was no correlation between Hoehn & Yahr and Braak stages. Neuropathological progression may, however, vary between subtypes as cortical Lewy body load and Braak stages were higher in patients with NTD compared to TD and Alzheimer pathology was more prevalent in RDP patients. Recognition of clinical subtypes in neuropathological studies is essential to identify selective vulnerability to protein accumulation that may determine the clinical phenotype in PD.
Copyright © 2011 Elsevier Ltd. All rights reserved.
Synucleinopathies from bench to bedside.
Source
Dept. for Geriatric Psychiatry, Lund University, Sweden; Dept. for Neurology, Lund, Skåne University Hospital, Lund, Sweden.
Abstract
Accumulation of alpha-synuclein is a pathological feature in several neurological diseases. Its characterization has allowed for a re-grouping of diseases according to the expected pathology. The clinical syndrome of PD can now be classified into forms with and without alpha-synuclein pathology. DLB and PDD are synucleinopathies, and MSA shows alpha-synuclein pathology with glial inclusions. ADHD symptoms commonly occur in persons that will subsequently develop DLB. A similar phenomenon may be the early personality changes and frontotemporal atrophy in patients with SNCA multiplication. RLS is not known to have alpha-synuclein pathology, but as PD and ADHD, involves a hypodopaminergic state. Furthermore, PD and RLS co-occur in families in a way that suggests common inheritance. A proportion of patients with ET have brainstem Lewy body pathology. Gaucher disease and other lysosomal storage disorders also have alpha-synuclein pathology. Alpha-synuclein is a naturally unfolded protein. Non-fibrillar oligomeres may be the toxic species, and Lewy body formation may in fact be protective. Inhibiting alpha-synuclein toxicity seems to be an attractive novel treatment strategy and several approaches are being developed. When such treatments become available, clinicians will need to be familiar with the clinical features that distinguish the synucleinopathies from their look-alikes.
Copyright © 2011 Elsevier Ltd. All rights reserved.
Misfolded α-synuclein and toll-like receptors: therapeutic targets for Parkinson's disease.
Source
Department of Neurostience and Interdisciplinary Program in Neuroscience, Georgetown University Medical Center, Washington, DC, USA.
Abstract
Parkinson's disease (PD) is typified by the loss of midbrain dopamine neurons, the presence of large proteinaceous α-synuclein-positive intracellular inclusions, oxidatively modified molecules and activated microglia. The etiology of sporadic PD is not fully understood but several lines of evidence suggest that genetic vulnerability and environmental toxicants converge to incite pathology-the multiple hit hypothesis. One gene linked to both familial and sporadic PD is SNCA, which encodes for the protein a-synuclein that has a propensity to misfold into toxic moieties. Here we show that a-synuclein directly activates microglia inciting the production of proinflammatory molecules and altering the expression of Toll-like receptors (TLRs). We discuss the role for α-synuclein-directed TLR expression changes in PD and the therapeutic potential of modifying this response.
Copyright © 2011 Elsevier Ltd. All rights reserved.
Vaccination for Parkinson's disease.
Source
AFFiRiS AG, Karl-Farkas Gasse 22, A-1030 Vienna, Austria.
Abstract
Idiopathic Parkinson's disease (PD) is, like other neurodegenerative diseases such as Alzheimer's disease (AD) considered a proteinopathy. Thus, a disease that is driven by the accumulation and aggregation of misfolded proteins, in case of PD α-synuclein (aSyn) is incriminated. Accordingly, removal of aSyn is assumed of having the potential to modify the course of the disease. Both active and passive aSyn targeting immunotherapy were found to modify disease in mice overexpressing human aSyn and recapitulating various aspects of synucleopathies. Translating immunotherapy to humans needs to consider the issue of potential autoimmunity. PD vaccines developed by AFFiRiS integrate the safety concept as applied for the company's AD vaccine candidates. This includes the use of short antigens, precluding activation of aSyn-specific T cells and, thus, cellular autoimmunity. Moreover, the selection of AFFITOPES® for clinical development is based on the principle of exclusive aSyn reactivity of vaccine-induced Abs excluding crossreactivity to β-synuclein (bSyn), which is ensured by the AFFITOME® platform technology. PD01, the first in class aSyn vaccine developed by AFFiRiS is about to enter the clinical phase of development.
Copyright © 2011 Elsevier Ltd. All rights reserved.
CSPα knockout causes neurodegeneration by impairing SNAP-25 function.
Source
1] Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA [2] Department of Neuroscience and Molecular Genetics, Howard Hughes Medical Institute, UT Southwestern Medical Center, Dallas, TX, USA.
Abstract
At a synapse, the synaptic vesicle protein cysteine-string protein-α (CSPα) functions as a co-chaperone for the SNAREprotein SNAP-25. Knockout (KO) of CSPα causes fulminant neurodegeneration that is rescued by α-synucleinoverexpression. The CSPα KO decreases SNAP-25 levels and impairs SNARE-complex assembly; only the latter but not the former is reversed by α-synuclein. Thus, the question arises whether the CSPα KO phenotype is due to decreased SNAP-25 function that then causes neurodegeneration, or due to the dysfunction of multiple as-yet uncharacterized CSPα targets. Here, we demonstrate that decreasing SNAP-25 levels in CSPα KO mice by either KO or knockdown of SNAP-25 aggravated their phenotype. Conversely, increasing SNAP-25 levels by overexpression rescued their phenotype. Inactive SNAP-25 mutants were unable to rescue, showing that the rescue was specific. Under all conditions, the neurodegenerative phenotype precisely correlated with SNARE-complex assembly, indicating that impaired SNARE-complex assembly due to decreased SNAP-25 levels is the ultimate correlate of neurodegeneration. Our findings suggest that the neurodegeneration in CSPα KO mice is primarily produced by defective SNAP-25 function, which causes neurodegeneration by impairing SNARE-complex assembly.
GSM-900MHz at low dose temperature-dependently downregulates α-synucleinin cultured cerebral cells independently of chaperone-mediated-autophagy.
Source
Groupe de Neurobiologie Cellulaire - EA3842 Homéostasie cellulaire et pathologies, Faculté de Médecine, 2 rue du Dr Raymond Marcland, 87025 Limoges Cedex, France; Laboratoire d'Histologie et de Cytogénétique - Hôpital de la Mère et de l'Enfant, 8 avenue D. Larrey, 87042 Limoges Cedex, France.
Abstract
The expanding use of GSM devices has resulted in public concern. Chaperone-mediated autophagy (CMA) is a way forprotein degradation in the lysosomes and increases under stress conditions as a cell defense response. α-synuclein, a CMA substrate, is a component of Parkinson disease. Since GSM might constitute a stress signal, we raised the possibility that GSM could alter the CMA process. Here, we analyzed the effects of chronic exposure to a low GSM-900MHz dose on apoptosis and CMA. Cultured cerebral cortical cells were sham-exposed or exposed to GSM-900MHz at specific absorption rate (SAR): 0.25W/kg for 24h using a wire-patch cell. Apoptosis was analyzed by DAPI stain of the nuclei and western blot of cleaved caspase-3. The expression of proteins involved in CMA (HSC70, HSP40, HSP90 and LAMP-2A) and α-synuclein were analyzed by western blot. CMA was also quantified in situ by analyzing the cell localization of active lysosomes. 24h exposure to GSM-900MHz resulted in ∼0.5°C temperature rise. It did not induce apoptosis but increased HSC70 by 26% and slightly decreased HSP90 (<10%). It also decreased α-synuclein by 24% independently of CMA, since the localization of active lysosomes was not altered. Comparable effects were observed in cells incubated at 37.5°C, a condition that mimics the GSM-generated temperature rise. The GSM-induced changes in HSC70, HSP90 and α-synuclein are most likely linked to temperature rise. We did not observe any immediate effect on cell viability. However, the delayed and long term consequences (protective or deleterious) of these changes on cell fate should be examined.
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