1.
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. Published by Elsevier Ireland Ltd.
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 thealpha-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 showsalpha-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.
Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.
Progressive neurodegenerative and behavioural changes induced by AAV-mediated overexpression of α-synuclein in midbrain dopamine neurons.
Source
Wallenberg Neuroscience Center, Department of Experimental Medical Sciences, Lund University, BMC A11, Lund 22184, Sweden.
Abstract
Parkinson's disease (PD) is characterised by the progressive loss of nigral dopamine neurons and the presence of synucleinopathy. Overexpression of α-synuclein in vivo using viral vectors has opened interesting possibilities to model PD-like pathology in rodents. However, the attempts made so far have failed to show a consistent behavioural phenotype and pronounced dopamine neurodegeneration. Using a more efficient adeno-associated viral (AAV) vector construct, which includes a WPRE enhancer element and uses the neuron-specific synapsin-1 promoter to drive the expression of human wild-type α-synuclein, we have now been able to achieve increased levels of α-synuclein in the transduced midbrain dopamine neurons sufficient to induce profound deficits in motor function, accompanied by reduced expression of proteins involved in dopamine neurotransmission and a time-dependent loss of nigral dopamine neurons, that develop progressively over 2-4months after vector injection. As in human PD, nigral cell loss was preceded by degenerative changes in striatal axons and terminals, and the appearance of α-synuclein positive inclusions in dystrophic axons and dendrites, supporting the idea that α-synuclein-induced pathology hits the axons and terminals first and later progresses to involve also the cell bodies. The time-course of changes seen in the AAV-α-synuclein treated animals defines distinct stages of disease progression that matches the pre-symptomatic, early symptomatic, and advanced stages seen in PD patients. This model provides new interesting possibilities for studies of stage-specific pathologic mechanisms and identification of targets for disease-modifying therapeutic interventions linked to early or late stages of the disease.
Copyright © 2011. Published by Elsevier Inc.
Transmission electron microscopy characterization of fluorescently labelled amyloid beta 1-40 and alpha-synuclein aggregates.
Abstract
ABSTRACT:
BACKGROUND:
Fluorescent tags, including small organic molecules and fluorescent proteins, enable the localization ofprotein molecules in biomedical research experiments. However, the use of these labels may interfere with the formation of larger-scale protein structures such as amyloid aggregates. Therefore, we investigate the effects of some commonly used fluorescent tags on the morphologies of fibrils grown from the Alzheimer's disease-associated peptide Amyloid beta 1-40 (Abeta40) and the Parkinson's disease-associated protein alpha-synuclein (alphaS).
RESULTS:
Using transmission electron microscopy (TEM), we verify that N-terminal labelling of Abeta40 with AMCA, TAMRA, and Hilyte-Fluor 488 tags does not prevent the formation of protofibrils and amyloid fibrils of various widths. We also measure the two-photon action cross-section of Abeta40 labelled with Hilyte Fluor 488 and demonstrate that this tag is suitable for use with two-photon fluorescence techniques. Similarly, we find that Alexa Fluor 488 labelling of alphaS variant proteins near either the N or C terminus (position 9 or 130) does not interfere with the formation of amyloid and other types of alphaS fibrils. We also present TEM images of fibrils grown from alphaS C-terminally labelled with enhanced green fluorescent protein (EGFP). Near neutral pH, two types of alphaS-EGFP fibrils are observed via TEM, while denaturation of the EGFP tag leads to the formation of additional species.
CONCLUSIONS:
We demonstrate that several small extrinsic fluorescent tags are compatible with studies of amyloidprotein aggregation. However, although fibrils can be grown from alphaS labelled with EGFP, the conformation of the fluorescent protein tag affects the observed aggregate morphologies. Thus, our results should assist researchers with label selection and optimization of solution conditions for aggregation studies involving fluorescence techniques.
α-Synuclein potentiates interleukin-1β-induced CXCL10 expression in human A172 astrocytoma cells.
Source
Department of Pharmacology/Physiology, Oklahoma State University Center for Health Sciences, Tulsa, OK 74107, United States.
Abstract
Neuroinflammation and neuronal degeneration observed in Parkinson's disease (PD) has been attributed in part to glial-mediated events. Increased expression of proinflammatory cytokines and abnormal accumulation of the neuronalprotein, α-synuclein in the brain are also characteristic of PD. While increasing evidence suggests that astrocytes contribute to neuroinflammation and dopaminergic neuronal degeneration associated with PD, there remains much to learn about these astroglial-mediated events. Therefore, we investigated the in vitro effects of interleukin-1β (IL-1β) and α-synuclein on astroglial expression of interferon-γ inducible protein-10 (CXCL10), a proinflammatory and neurotoxic chemokine. IL-1β-induced CXCL10 protein expression was potentiated by co-exposure to α-synuclein. α-Synuclein did not significantly affect IL-1β-induced CXCL10 mRNA expression, but did mediate increased CXCL10 mRNA stability, which may explain, in part, the increased levels of secreted CXCL10 protein. Future investigations are warranted to more fully define the mechanism by which α-synuclein enhances IL-1β-induced astroglial CXCL10 expression. These findings highlight the importance of α-synuclein in modulating inflammatory events in astroglia. These events may be particularly relevant to the pathology of CNS disorders involving α-synuclein accumulation, including PD and HIV-1 associated dementia.
Copyright © 2011. Published by Elsevier Ireland Ltd.
Interaction between pathogenic proteins in neurodegenerative disorders.
Source
Institute of Clinical Neurobiology, Vienna, Austria.
Abstract
The misfolding and progressive aggregation of specific proteins in selective regions of the nervous system is a seminal occurrence in many neurodegenerative disorders, and the interaction between pathological/toxic proteins to cause neurodegeneration is a hot topic of current neuroscience research. Despite clinical, genetic, and experimental differences, increasing evidence indicates considerable overlap between synucleinopathies, tauopathies and otherprotein-misfolding diseases. Inclusions, often characteristic hallmarks of these disorders, suggest interactions of pathological proteins enganging common downstream pathways. Novel findings that have shifted our understanding in the role of pathologic proteins in the pathogenesis of Alzheimer, Parkinson, Huntington, and prion diseases, have confirmed correlations/overlaps between these and other neurodegenerative disorders. Emerging evidence, in addition to synergistic effects of tau protein, amyloid β, α-synuclein, and other pathologic proteins, suggests that prion-like induction and spreading, involving secreted proteins, are major pathogenic mechanisms in various neurodegenerative diseases, depending on genetic backgrounds and environmental factors. The elucidation of the basic molecular mechanisms underlying the interaction and spreading of pathogenic proteins, suggesting a dualism or triad of neurodegeneration in protein-misfolding disorders, is a major challenge for modern neuroscience, in order to provide a deeper insight into their pathogenesis as a basis of effective diagnosis and treatment. © 2011 The Authors Journal of Cellular and Molecular Medicine © 2011 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd.
© 2011 The Authors Journal of Cellular and Molecular Medicine © 2011 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd.
Efficient construction of disordered protein ensembles in a bayesian framework with optimal selection of conformations.
Source
Committee on Higher Degrees in Biophysics, Harvard University, Cambridge, Massachusetts 02139-4307, United States. ckfisher@fas.harvard.edu.
Abstract
Constructing an accurate model for the thermally accessible states of an Intrinsically Disordered Protein (IDP) is a fundamental problem in structural biology. This problem requires one to consider a large number of conformations in order to ensure that the model adequately represents the range of structures that the protein can adopt. Typically, one samples a wide range of structures in an attempt to obtain an ensemble that agrees with some pre-specified set of experimental data. However, models that contain more structures than the available experimental restraints are problematic as the large number of degrees of freedom in the ensemble leads to considerable uncertainty in the final model. We introduce a computationally efficient algorithm called Variational Bayesian Weighting with Structure Selection (VBWSS) for constructing a model for the ensemble of an IDP that contains a minimal number of conformations and, simultaneously, provides estimates for the uncertainty in properties calculated from the model. The algorithm is validated using reference ensembles and applied to construct an ensemble for the 140-residue IDP, monomeric α- synuclein.
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