Publications by authors named "Tiago F Outeiro"

159 Publications

Prion-like α-synuclein pathology in the brain of infants with Krabbe disease.

Brain 2022 Jan 6. Epub 2022 Jan 6.

Wellcome Centre for Mitochondrial Research, Claremont Road, Newcastle, NE2 4AA UK.

Krabbe disease is an infantile neurodegenerative disorder resulting from pathogenic variants in the GALC gene which causes accumulation of the toxic sphingolipid psychosine. GALC variants are also associated with Lewy body diseases, an umbrella term for age-associated neurodegenerative diseases in which the protein α-synuclein aggregates into Lewy bodies. To explore whether α-synuclein in Krabbe disease has pathological similarities to that in Lewy body disease, we performed an observational post-mortem study of Krabbe disease brain tissue (N = 4) compared to infant controls (N = 4) and identified widespread accumulations of α-synuclein. To determine whether α-synuclein in Krabbe disease brain displayed disease-associated pathogenic properties we evaluated its seeding capacity using the real-time quaking-induced conversion assay in two cases for which frozen tissue was available and strikingly identified aggregation into fibrils similar to those observed in Lewy body disease, confirming the prion-like capacity of Krabbe disease-derived α-synuclein. These observations constitute the first report of prion-like α-synuclein in the brain tissue of infants and challenge the putative view that α-synuclein pathology is merely an age-associated phenomenon, instead suggesting it results from alterations to biological pathways, such as sphingolipid metabolism. Our findings have important implications for understanding the mechanisms underlying Lewy body formation in Lewy body disease.
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http://dx.doi.org/10.1093/brain/awac002DOI Listing
January 2022

Cellular Prion Protein Mediates α-Synuclein Uptake, Localization, and Toxicity In Vitro and In Vivo.

Mov Disord 2022 Jan 27;37(1):39-51. Epub 2021 Aug 27.

Department of Neurology, University Medical Center Göttingen and the German Center for Neurodegenerative Diseases, Göttingen, Germany.

Background: The cellular prion protein (PrP ) is a membrane-bound, multifunctional protein mainly expressed in neuronal tissues. Recent studies indicate that the native trafficking of PrP can be misused to internalize misfolded amyloid beta and α-synuclein (aSyn) oligomers.

Objectives: We define PrP 's role in internalizing misfolded aSyn in α-synucleinopathies and identify further involved proteins.

Methods: We performed comprehensive behavioral studies on four transgenic mouse models (ThySyn and ThySynPrP00, TgM83 and TgMPrP00) at different ages. We developed PrP -(over)-expressing cell models (cell line and primary cortical neurons), used confocal laser microscopy to perform colocalization studies, applied mass spectrometry to identify interactomes, and determined disassociation constants using surface plasmon resonance (SPR) spectroscopy.

Results: Behavioral deficits (memory, anxiety, locomotion, etc.), reduced lifespans, and higher oligomeric aSyn levels were observed in PrP -expressing mice (ThySyn and TgM83), but not in homologous Prnp ablated mice (ThySynPrP00 and TgMPrP00). PrP colocalized with and facilitated aSyn (oligomeric and monomeric) internalization in our cell-based models. Glimepiride treatment of PrP -overexpressing cells reduced aSyn internalization in a dose-dependent manner. SPR analysis showed that the binding affinity of PrP to monomeric aSyn was lower than to oligomeric aSyn. Mass spectrometry-based proteomic studies identified clathrin in the immunoprecipitates of PrP and aSyn. SPR was used to show that clathrin binds to recombinant PrP, but not aSyn. Experimental disruption of clathrin-coated vesicles significantly decreased aSyn internalization.

Conclusion: PrP 's native trafficking can be misused to internalize misfolded aSyn through a clathrin-based mechanism, which may facilitate the spreading of pathological aSyn. Disruption of aSyn-PrP binding is, therefore, an appealing therapeutic target in α-synucleinopathies. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
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http://dx.doi.org/10.1002/mds.28774DOI Listing
January 2022

Alpha-synuclein research: defining strategic moves in the battle against Parkinson's disease.

NPJ Parkinsons Dis 2021 Jul 26;7(1):65. Epub 2021 Jul 26.

German Center for Neurodegenerative Diseases (DZNE), Göttingen, Germany.

With the advent of the genetic era in Parkinson's disease (PD) research in 1997, α-synuclein was identified as an important player in a complex neurodegenerative disease that affects >10 million people worldwide. PD has been estimated to have an economic impact of $51.9 billion in the US alone. Since the initial association with PD, hundreds of researchers have contributed to elucidating the functions of α-synuclein in normal and pathological states, and these remain critical areas for continued research. With this position paper the authors strive to achieve two goals: first, to succinctly summarize the critical features that define α-synuclein's varied roles, as they are known today; and second, to identify the most pressing knowledge gaps and delineate a multipronged strategy for future research with the goal of enabling therapies to stop or slow disease progression in PD.
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http://dx.doi.org/10.1038/s41531-021-00203-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8313662PMC
July 2021

In silico analysis of the aggregation propensity of the SARS-CoV-2 proteome: Insight into possible cellular pathologies.

Biochim Biophys Acta Proteins Proteom 2021 10 5;1869(10):140693. Epub 2021 Jul 5.

Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen 37073, Germany; Max Planck Institute for Experimental Medicine, Göttingen, Germany; Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom; Scientific Employee With a Honorary Contract at Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Göttingen, Germany.. Electronic address:

The SARS-CoV-2 virus causes the coronavirus disease 19 emerged in 2020. The pandemic triggered a turmoil in public health and is having a tremendous social and economic impact around the globe. Upon entry into host cells, the SARS-CoV-2 virus hijacks cellular machineries to produce and maintain its own proteins, spreading the infection. Although the disease is known for prominent respiratory symptoms, accumulating evidence is also demonstrating the involvement of the central nervous system, with possible mid- and long-term neurological consequences. In this study, we conducted a detailed bioinformatic analysis of the SARS-CoV-2 proteome aggregation propensity by using several complementary computational tools. Our study identified 10 aggregation prone proteins in the reference SARS-CoV-2 strain: the non-structural proteins Nsp4, Nsp6 and Nsp7 as well as ORF3a, ORF6, ORF7a, ORF7b, ORF10, CovE and CovM. By searching for the available mutants of each protein, we have found that most proteins are conserved, while ORF3a and ORF7b are variable and characterized by the occurrence of a large number of mutants with increased aggregation propensity. The geographical distribution of the mutants revealed interesting differences in the localization of aggregation-prone mutants of each protein. Aggregation-prone mutants of ORF7b were found in 7 European countries, whereas those of ORF3a in only 2. Aggregation-prone sequences of ORF7b, but not of ORF3a, were identified in Australia, India, Nepal, China, and Thailand. Our results are important for future analysis of a possible correlation between higher transmissibility and infection, as well as the presence of neurological symptoms with aggregation propensity of SARS-CoV-2 proteins.
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http://dx.doi.org/10.1016/j.bbapap.2021.140693DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8256665PMC
October 2021

Cerebral dopamine neurotrophic factor reduces α-synuclein aggregation and propagation and alleviates behavioral alterations in vivo.

Mol Ther 2021 09 1;29(9):2821-2840. Epub 2021 May 1.

Institute of Biotechnology, HiLIFE, University of Helsinki, 00014 Helsinki, Finland; Neuroscience Center, HiLIFE, University of Helsinki, 00014 Helsinki, Finland; Faculty of Pharmacy, University of Helsinki, Helsinki, Finland. Electronic address:

A molecular hallmark in Parkinson's disease (PD) pathogenesis are α-synuclein aggregates. Cerebral dopamine neurotrophic factor (CDNF) is an atypical growth factor that is mostly resident in the endoplasmic reticulum but exerts its effects both intracellularly and extracellularly. One of the beneficial effects of CDNF can be protecting neurons from the toxic effects of α-synuclein. Here, we investigated the effects of CDNF on α-synuclein aggregation in vitro and in vivo. We found that CDNF directly interacts with α-synuclein with a K = 23 ± 6 nM and reduces its auto-association. Using nuclear magnetic resonance (NMR) spectroscopy, we identified interaction sites on the CDNF protein. Remarkably, CDNF reduces the neuronal internalization of α-synuclein fibrils and induces the formation of insoluble phosphorylated α-synuclein inclusions. Intra-striatal CDNF administration alleviates motor deficits in rodents challenged with α-synuclein fibrils, though it did not reduce the number of phosphorylated α-synuclein inclusions in the substantia nigra. CDNF's beneficial effects on rodent behavior appear not to be related to the number of inclusions formed in the current context, and further study of its effects on the aggregation mechanism in vivo are needed. Nonetheless, the interaction of CDNF with α-synuclein, modifying its aggregation, spreading, and associated behavioral alterations, provides novel insights into the potential of CDNF as a therapeutic strategy in PD and other synucleinopathies.
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http://dx.doi.org/10.1016/j.ymthe.2021.04.035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8417450PMC
September 2021

Dysfunction of RAB39B-Mediated Vesicular Trafficking in Lewy Body Diseases.

Mov Disord 2021 08 3;36(8):1744-1758. Epub 2021 May 3.

Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.

Intracellular vesicular trafficking is essential for neuronal development, function, and homeostasis and serves to process, direct, and sort proteins, lipids, and other cargo throughout the cell. This intricate system of membrane trafficking between different compartments is tightly orchestrated by Ras analog in brain (RAB) GTPases and their effectors. Of the 66 members of the RAB family in humans, many have been implicated in neurodegenerative diseases and impairment of their functions contributes to cellular stress, protein aggregation, and death. Critically, RAB39B loss-of-function mutations are known to be associated with X-linked intellectual disability and with rare early-onset Parkinson's disease. Moreover, recent studies have highlighted altered RAB39B expression in idiopathic cases of several Lewy body diseases (LBDs). This review contextualizes the role of RAB proteins in LBDs and highlights the consequences of RAB39B impairment in terms of endosomal trafficking, neurite outgrowth, synaptic maturation, autophagy, as well as alpha-synuclein homeostasis. Additionally, the potential for therapeutic intervention is examined via a discussion of the recent progress towards the development of specific RAB modulators. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
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http://dx.doi.org/10.1002/mds.28605DOI Listing
August 2021

Identification of Two Novel Peptides That Inhibit α-Synuclein Toxicity and Aggregation.

Front Mol Neurosci 2021 12;14:659926. Epub 2021 Apr 12.

Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Goettingen, Göttingen, Germany.

Aggregation of α-synuclein (αSyn) into proteinaceous deposits is a pathological hallmark of a range of neurodegenerative diseases including Parkinson's disease (PD). Numerous lines of evidence indicate that the accumulation of toxic oligomeric and prefibrillar αSyn species may underpin the cellular toxicity and spread of pathology between cells. Therefore, aggregation of αSyn is considered a priority target for drug development, as aggregation inhibitors are expected to reduce αSyn toxicity and serve as therapeutic agents. Here, we used the budding yeast as a platform for the identification of short peptides that inhibit αSyn aggregation and toxicity. A library consisting of approximately one million peptide variants was utilized in two high-throughput screening approaches for isolation of library representatives that reduce αSyn-associated toxicity and aggregation. Seven peptides were isolated that were able to suppress specifically αSyn toxicity and aggregation in living cells. Expression of the peptides in yeast reduced the accumulation of αSyn-induced reactive oxygen species and increased cell viability. Next, the peptides were chemically synthesized and probed for their ability to modulate αSyn aggregation . Two synthetic peptides, K84s and K102s, of 25 and 19 amino acids, respectively, significantly inhibited αSyn oligomerization and aggregation at sub-stoichiometric molar ratios. Importantly, K84s reduced αSyn aggregation in human cells. These peptides represent promising αSyn aggregation antagonists for the development of future therapeutic interventions.
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http://dx.doi.org/10.3389/fnmol.2021.659926DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8072481PMC
April 2021

MPV17 Mutations Are Associated With a Quiescent Energetic Metabolic Profile.

Front Cell Neurosci 2021 17;15:641264. Epub 2021 Mar 17.

Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany.

Mutations in the MPV17 gene are associated with hepatocerebral form of mitochondrial depletion syndrome. The mechanisms through which MPV17 mutations cause respiratory chain dysfunction and mtDNA depletion is still unclear. The MPV17 gene encodes an inner membrane mitochondrial protein that was recently described to function as a non-selective channel. Although its exact function is unknown, it is thought to be important in the maintenance of mitochondrial membrane potential (ΔΨm). To obtain more information about the role of MPV17 in human disease, we investigated the effect of MPV17 knockdown and of selected known MPV17 mutations associated with MPV17 disease . We used different approaches in order to evaluate the cellular consequences of MPV17 deficiency. We found that lower levels of MPV17 were associated with impaired mitochondrial respiration and with a quiescent energetic metabolic profile. All the mutations studied destabilized the protein, resulting in reduced protein levels. We also demonstrated that different mutations caused different cellular abnormalities, including increased ROS production, decreased oxygen consumption, loss of ΔΨm, and mislocalization of MPV17 protein. Our study provides novel insight into the molecular effects of MPV17 mutations and opens novel possibilities for testing therapeutic strategies for a devastating group of disorders.
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http://dx.doi.org/10.3389/fncel.2021.641264DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8011494PMC
March 2021

Alpha-Synuclein: Mechanisms of Release and Pathology Progression in Synucleinopathies.

Cells 2021 02 12;10(2). Epub 2021 Feb 12.

Center for Biostructural Imaging of Neurodegeneration, Department of Experimental Neurodegeneration, University Medical Center Göttingen, 37075 Göttingen, Germany.

The accumulation of misfolded alpha-synuclein (aSyn) throughout the brain, as Lewy pathology, is a phenomenon central to Parkinson's disease (PD) pathogenesis. The stereotypical distribution and evolution of the pathology during disease is often attributed to the cell-to-cell transmission of aSyn between interconnected brain regions. The spreading of conformationally distinct aSyn protein assemblies, commonly referred as strains, is thought to result in a variety of clinically and pathologically heterogenous diseases known as synucleinopathies. Although tremendous progress has been made in the field, the mechanisms involved in the transfer of these assemblies between interconnected neural networks and their role in driving PD progression are still unclear. Here, we present an update of the relevant discoveries supporting or challenging the prion-like spreading hypothesis. We also discuss the importance of aSyn strains in pathology progression and the various putative molecular mechanisms involved in cell-to-cell protein release. Understanding the pathways underlying aSyn propagation will contribute to determining the etiology of PD and related synucleinopathies but also assist in the development of new therapeutic strategies.
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http://dx.doi.org/10.3390/cells10020375DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7917664PMC
February 2021

DEAD-box RNA helicase Dbp4/DDX10 is an enhancer of α-synuclein toxicity and oligomerization.

PLoS Genet 2021 03 3;17(3):e1009407. Epub 2021 Mar 3.

Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Goettingen, Göttingen, Germany.

Parkinson's disease is a neurodegenerative disorder associated with misfolding and aggregation of α-synuclein as a hallmark protein. Two yeast strain collections comprising conditional alleles of essential genes were screened for the ability of each allele to reduce or improve yeast growth upon α-synuclein expression. The resulting 98 novel modulators of α-synuclein toxicity clustered in several major categories including transcription, rRNA processing and ribosome biogenesis, RNA metabolism and protein degradation. Furthermore, expression of α-synuclein caused alterations in pre-rRNA transcript levels in yeast and in human cells. We identified the nucleolar DEAD-box helicase Dbp4 as a prominent modulator of α-synuclein toxicity. Downregulation of DBP4 rescued cells from α-synuclein toxicity, whereas overexpression led to a synthetic lethal phenotype. We discovered that α-synuclein interacts with Dbp4 or its human ortholog DDX10, sequesters the protein outside the nucleolus in yeast and in human cells, and stabilizes a fraction of α-synuclein oligomeric species. These findings provide a novel link between nucleolar processes and α-synuclein mediated toxicity with DDX10 emerging as a promising drug target.
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http://dx.doi.org/10.1371/journal.pgen.1009407DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7928443PMC
March 2021

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition).

Autophagy 2021 Jan 8;17(1):1-382. Epub 2021 Feb 8.

University of Crete, School of Medicine, Laboratory of Clinical Microbiology and Microbial Pathogenesis, Voutes, Heraklion, Crete, Greece; Foundation for Research and Technology, Institute of Molecular Biology and Biotechnology (IMBB), Heraklion, Crete, Greece.

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field.
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http://dx.doi.org/10.1080/15548627.2020.1797280DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7996087PMC
January 2021

Reply to: "Parkinson's Disease and COVID-19: Do We Need to Be More Patient?"

Mov Disord 2021 02;36(2):278-279

Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Goettingen, Goettingen, Germany.

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http://dx.doi.org/10.1002/mds.28482DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8013411PMC
February 2021

Lipids, lysosomes and mitochondria: insights into Lewy body formation from rare monogenic disorders.

Acta Neuropathol 2021 04 30;141(4):511-526. Epub 2021 Jan 30.

Newcastle University Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK.

Accumulation of the protein α-synuclein into insoluble intracellular deposits termed Lewy bodies (LBs) is the characteristic neuropathological feature of LB diseases, such as Parkinson's disease (PD), Parkinson's disease dementia (PDD) and dementia with LB (DLB). α-Synuclein aggregation is thought to be a critical pathogenic event in the aetiology of LB disease, based on genetic analyses, fundamental studies using model systems, and the observation of LB pathology in post-mortem tissue. However, some monogenic disorders not traditionally characterised as synucleinopathies, such as lysosomal storage disorders, iron storage disorders and mitochondrial diseases, appear disproportionately vulnerable to the deposition of LBs, perhaps suggesting the process of LB formation may be a result of processes perturbed as a result of these conditions. The present review discusses biological pathways common to monogenic disorders associated with LB formation, identifying catabolic processes, particularly related to lipid homeostasis, autophagy and mitochondrial function, as processes that could contribute to LB formation. These findings are discussed in the context of known mediators of α-synuclein aggregation, highlighting the potential influence of impairments to these processes in the aetiology of LB formation.
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http://dx.doi.org/10.1007/s00401-021-02266-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7952289PMC
April 2021

Cancer and Parkinson's Disease: Common Targets, Emerging Hopes.

Mov Disord 2021 02 21;36(2):340-346. Epub 2020 Dec 21.

Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center, Göttingen, Germany.

Cancer and neurodegeneration are two major leading causes of morbidity and death worldwide. At first sight, the two fields do not seem to share much in common and, if anything, might be placed on opposite ends of a spectrum. Although neurodegeneration results in excessive neuronal cell death, cancer emerges from increased proliferation and resistance to cell death. Therefore, one might expect significant differences in the underlying pathophysiological mechanisms. However, the more we deepen our understanding of these two types of diseases, the more we appreciate the unexpected overlap between them. Although most epidemiological studies support an inverse association between the risk for development of neurodegenerative diseases and cancer, increasing evidence points to a positive correlation between specific types of cancer, like melanoma, and neurodegenerative diseases, like Parkinson's disease (PD). We believe that deciphering the molecular processes and pathways underlying one of these diseases may significantly increase our understanding about the other. Therefore, the identification of novel biomarkers and therapeutic approaches in cancer, may lead to improved diagnosis and treatment of neurodegeneration, and vice versa. In this Viewpoint, we summarize recent findings connecting both diseases and speculate that insights from one disease may inform on mechanisms, and help identify novel biomarkers and targets for intervention, possibly leading to improved management of both diseases. © 2020 International Parkinson and Movement Disorder Society.
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http://dx.doi.org/10.1002/mds.28425DOI Listing
February 2021

From iPS Cells to Rodents and Nonhuman Primates: Filling Gaps in Modeling Parkinson's Disease.

Mov Disord 2021 04 16;36(4):832-841. Epub 2020 Nov 16.

Department of Experimental Medical Science, Basal Ganglia Pathophysiology Unit, Lund University, Lund, Sweden.

Parkinson's disease (PD) is primarily known as a movement disorder because of typical clinical manifestations associated with the loss of dopaminergic neurons in the substantia nigra. However, it is now widely recognized that PD is a much more complex condition, with multiple and severe nonmotor features implicating additional brain areas and organs in the disease process. Pathologically, typical forms of PD are characterized by the accumulation of α-synuclein-rich protein inclusions known as Lewy bodies and Lewy neurites, although other types of protein inclusions are also often present in the brain. Familial forms of PD have provided a wealth of information about molecular pathways leading to neurodegeneration, but only to add to the complexity of the problem and uncover new knowledge gaps. Therefore, modeling PD in the laboratory has become increasingly challenging. Here, we discuss knowledge gaps and challenges in the use of laboratory models for the study of a disease that is clinically heterogeneous and multifactorial. We propose that the combined use of patient-derived cells and animal models, along with current technological tools, will not only expand our molecular and pathophysiological understanding of PD, but also assist in the identification of therapeutic strategies targeting relevant pathogenic pathways. © 2020 International Parkinson and Movement Disorder Society.
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http://dx.doi.org/10.1002/mds.28387DOI Listing
April 2021

SARS-CoV-2, immunosenescence and inflammaging: partners in the COVID-19 crime.

Aging (Albany NY) 2020 Sep 29;12(18):18778-18789. Epub 2020 Sep 29.

Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Goettingen, Goettingen, Germany.

Pneumonia outbreak in the city of Wuhan, China, prompted the finding of a novel strain of severe acute respiratory syndrome virus (SARS-CoV-2). Here, we discuss potential long-term consequences of SARS-CoV-2 infection, and its possibility to cause permanent damage to the immune system and the central nervous system. Advanced chronological age is one of the main risk factors for the adverse outcomes of COVID-19, presumably due to immunosenescence and chronic low-grade inflammation, both characteristic of the elderly. The combination of viral infection and chronic inflammation in advanced chronological age might cause multiple detrimental unforeseen consequences for the predisposition and severity of neurodegenerative diseases and needs to be considered so that we can be prepared to deal with future outcomes of the ongoing pandemic.
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http://dx.doi.org/10.18632/aging.103989DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7585069PMC
September 2020

RAB39B is redistributed in dementia with Lewy bodies and is sequestered within aβ plaques and Lewy bodies.

Brain Pathol 2021 01 25;31(1):120-132. Epub 2020 Aug 25.

Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Framlington Place, Newcastle Upon Tyne, NE2 4HH, UK.

Loss of function mutations within the vesicular trafficking protein Ras analogy in brain 39B (RAB39B) are associated with rare X-linked Parkinson's disease (PD). Physiologically, RAB39B is localized to Golgi vesicles and recycling endosomes and is required for glutamatergic receptor maturation but also for alpha-Synuclein (aSyn) homeostasis and the inhibition of its aggregation. Despite evidence linking RAB39B to neurodegeneration, the involvement of the protein in idiopathic neurodegenerative diseases remains undetermined. Here, analysis of the spatial distribution and expression of RAB39B was conducted in post-mortem human brain tissue from cases of dementia with Lewy bodies (DLB, n = 10), Alzheimer's disease (AD, n = 12) and controls (n = 12). Assessment of cortical RAB39B immunoreactivity using tissue microarrays revealed an overall reduction in the area of RAB39B positive gray matter in DLB cases when compared to controls and AD cases. Strikingly, RAB39B co-localized with beta-amyloid (Aβ) plaques in all cases examined and was additionally present in a subpopulation of Lewy bodies (LBs) in DLB. Biochemical measures of total RAB39B levels within the temporal cortex were unchanged between DLB, AD and controls. However, upon subcellular fractionation, a reduction of RAB39B in the cytoplasmic pool was found in DLB cases, alongside an increase of phosphorylated aSyn and Aβ in whole tissue lysates. The reduction of cytoplasmic RAB39B is consistent with an impaired reserve capacity for RAB39B-associated functions, which in turn may facilitate LB aggregation and synaptic impairment. Collectively, our data support the involvement of RAB39B in the pathogenesis of DLB and the co-aggregation of RAB39B with Aβ in plaques suggests that age-associated cerebral Aβ pathology may be contributory to the loss of RAB39B. Thus RAB39B, its associated functional pathways and its entrapment in aggregates may be considered as future targets for therapeutic interventions to impede the overall pathological burden and cellular dysfunction in Lewy body diseases.
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http://dx.doi.org/10.1111/bpa.12890DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8018064PMC
January 2021

The Neuroprotective Action of Amidated-Kyotorphin on Amyloid β Peptide-Induced Alzheimer's Disease Pathophysiology.

Front Pharmacol 2020 9;11:985. Epub 2020 Jul 9.

Instituto de Farmacologia e Neurociências, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal.

Kyotorphin (KTP, l-tyrosyl-l-arginine) is an endogenous dipeptide initially described to have analgesic properties. Recently, KTP was suggested to be an endogenous neuroprotective agent, namely for Alzheimer's disease (AD). In fact, KTP levels were shown to be decreased in the cerebrospinal fluid of patients with AD, and recent data showed that intracerebroventricular (i.c.v.) injection of KTP ameliorates memory impairments in a sporadic rat model of AD. However, this administration route is far from being a suitable therapeutic strategy. Here, we evaluated if the blood-brain permeant KTP-derivative, KTP-NH, when systemically administered, would be effective in preventing memory deficits in a sporadic AD animal model and if so, which would be the synaptic correlates of that action. The sporadic AD model was induced in male Wistar rats through i.c.v. injection of amyloid β peptide (Aβ). Animals were treated for 20 days with KTP-NH (32.3 mg/kg, intraperitoneally (i.p.), starting at day 3 after Aβ administration) before memory testing (Novel object recognition (NOR) and Y-maze (YM) tests). Animals were then sacrificed, and markers for gliosis were assessed by immunohistochemistry and Western blot analysis. Synaptic correlates were assessed by evaluating theta-burst induced long term potentiation (LTP) of field excitatory synaptic potentials (fEPSPs) recorded from hippocampal slices and cortical spine density analysis. In the absence of KTP-NH treatment, Aβ-injected rats had clear memory deficits, as assessed through NOR or YM tests. Importantly, these memory deficits were absent in Aβ-injected rats that had been treated with KTP-NH, which scored in memory tests as control (sham i.c.v. injected) rats. No signs of gliosis could be detected at the end of the treatment in any group of animals. LTP magnitude was significantly impaired in hippocampal slices that had been incubated with Aβ oligomers (200 nM) in the absence of KTP-NH. Co-incubation with KTP-NH (50 nM) rescued LTP toward control values. Similarly, Aβ caused a significant decrease in spine density in cortical neuronal cultures, and this was prevented by co-incubation with KTP-NH (50 nM). In conclusion, the present data demonstrate that i.p. KTP-NH treatment counteracts Aβ-induced memory impairments in an AD sporadic model, possibly through the rescuing of synaptic plasticity mechanisms.
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http://dx.doi.org/10.3389/fphar.2020.00985DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7363954PMC
July 2020

Effects of pharmacological modulators of α-synuclein and tau aggregation and internalization.

Sci Rep 2020 07 30;10(1):12827. Epub 2020 Jul 30.

Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Goettingen, 37073, Göttingen, Germany.

Parkinson's disease (PD) and Alzheimer's disease (AD) are common neurodegenerative disorders of the elderly and, therefore, affect a growing number of patients worldwide. Both diseases share, as a common hallmark, the accumulation of characteristic protein aggregates, known as Lewy bodies (LB) in PD, and neurofibrillary tangles in AD. LBs are primarily composed of misfolded α-synuclein (aSyn), and neurofibrillary tangles are primarily composed of tau protein. Importantly, upon pathological evaluation, most AD and PD/Lewy body dementia cases exhibit mixed pathology, with the co-occurrence of both LB and neurofibrillary tangles, among other protein inclusions. Recent studies suggest that both aSyn and tau pathology can spread and propagate through neuronal connections. Therefore, it is important to investigate the mechanisms underlying aggregation and propagation of these proteins for the development of novel therapeutic strategies. Here, we assessed the effects of different pharmacological interventions on the aggregation and internalization of tau and aSyn. We found that anle138b and fulvic acid decrease aSyn and tau aggregation, that epigallocatechin gallate decreases aSyn aggregation, and that dynasore reduces tau internalization. Establishing the effects of small molecules with different chemical properties on the aggregation and spreading of aSyn and tau will be important for the development of future therapeutic interventions.
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http://dx.doi.org/10.1038/s41598-020-69744-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7393090PMC
July 2020

Reply to: SARS-CoV-2 as a Potential Trigger of Neurodegenerative Diseases.

Mov Disord 2020 07;35(7):1106-1107

Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Goettingen, Goettingen, Germany.

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http://dx.doi.org/10.1002/mds.28178DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7300978PMC
July 2020

Protein trapping leads to altered synaptic proteostasis in synucleinopathies.

FEBS J 2020 12 23;287(24):5294-5303. Epub 2020 May 23.

Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany.

Parkinson's disease (PD) is associated with the accumulation of alpha-synuclein (aSyn) in intracellular inclusions known as Lewy bodies and Lewy neurites. Under physiological conditions, aSyn is found at the presynaptic terminal and exists in a dynamic equilibrium between soluble, membrane-associated and aggregated forms. Emerging evidence suggests that, under pathological conditions, aSyn begins to accumulate and acquire a toxic function at the synapse, impairing their normal function and connectivity. However, the precise molecular mechanisms linking aSyn accumulation and synaptic dysfunction are still elusive. Here, we provide an overview of our current findings and discuss the hypothesis that certain aSyn aggregates may interact with proteins with whom aSyn normally does not interact with, thereby trapping them and preventing them from performing their normal functions in the cell. We posit that such abnormal interactions start to occur during the prodromal stages of PD, eventually resulting in the overt manifestation of clinical features. Therefore, understanding the nature and behaviour of toxic aSyn species and their contribution to aSyn-mediated toxicity is crucial for the development of therapeutic strategies capable of modifying disease progression in PD and other synucleinopathies.
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http://dx.doi.org/10.1111/febs.15364DOI Listing
December 2020

X1INH, an improved next-generation affinity-optimized hydrazonic ligand, attenuates abnormal copper(I)/copper(II)-α-Syn interactions and affects protein aggregation in a cellular model of synucleinopathy.

Dalton Trans 2020 Nov;49(45):16252-16267

Departamento de Química, Pontifícia Universidade Católica do Rio de Janeiro, 22451-045, Rio de Janeiro, RJ, Brazil.

Although normal aging presents an accumulation of copper and iron in the brain, this becomes more relevant in neurodegeneration. α-Synuclein (α-Syn) misfolding has long been linked with the development of Parkinson's disease (PD). Copper binding promotes aggregation of α-Syn, as well as generalized oxidative stress. In this sense, the use of therapies that target metal dyshomeostasis has been in focus in the past years. Metal-Protein Attenuating Compounds (MPACs) are moderate chelators that aim at disrupting specific, abnormal metal-protein interactions. Our research group has now established that N-acylhydrazones compose a set of truly encouraging MPACs for the bioinorganic management of metal-enhanced aggregopathies. In the present work, a novel ligand, namely 1-methyl-1H-imidazole-2-carboxaldehyde isonicotinoyl hydrazone (X1INH), is reported. We describe solution studies on the interaction and affinity of this compound for copper(ii) ions showing that a fine tuning of metal-affinity was achieved. A series of in vitro biophysical NMR experiments were performed in order to assess the X1INH ability to compete with α-Syn monomers for the binding of both copper(i) and copper(ii) ions, which are central in PD pathology. A preference for copper(i) has been observed. X1INH is less toxic to human neuroglioma (H4) cells in comparison to structure-related compounds. Finally, we show that treatment with X1INH results in a higher number of smaller, less compact inclusions in a well-established model of α-Syn aggregation. Thus, X1INH constitutes a promising MPAC for the treatment of Parkinson's disease.
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http://dx.doi.org/10.1039/d0dt01138jDOI Listing
November 2020

SARS-CoV-2: At the Crossroad Between Aging and Neurodegeneration.

Mov Disord 2020 05 24;35(5):716-720. Epub 2020 Apr 24.

Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center, Goettingen, Goettingen, Germany.

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http://dx.doi.org/10.1002/mds.28084DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7262312PMC
May 2020

The Interplay Between Proteostasis Systems and Parkinson's Disease.

Adv Exp Med Biol 2020 ;1233:223-236

Department of Experimental Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany.

The proteostasis network controls the balance between protein synthesis, folding, function, and degradation, and ensures proteins are recycled when they are no longer needed or become damaged, avoiding unwanted aggregation and accumulation. In various neurological disorders, such as Parkinson's disease (PD) and other synucleinopathies, the accumulation of misfolded and aggregated alpha-synuclein (aSyn) is considered a central event in the onset and progression of disease. During aging, there is a decline in the activity of various degradation machineries, and the overall buffering capacity of the proteostasis network starts to decrease. Such decline is thought to play a pivotal role in PD, causing aSyn to build-up due to compromised clearance, which in turn contributes to further disease progression.In this chapter, we summarize central findings related to aSyn accumulation and degradation, as well as to the consequences of the toxic effects caused by aSyn on proteostasis. We also highlight some of the factors and pathways that may be used as potential targets for therapeutic interventions in PD.
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http://dx.doi.org/10.1007/978-3-030-38266-7_9DOI Listing
April 2020

Inhibition of HDAC6 activity protects dopaminergic neurons from alpha-synuclein toxicity.

Sci Rep 2020 04 8;10(1):6064. Epub 2020 Apr 8.

Department of Human Molecular Genetics, Institute of Human Genetics, Ruprecht-Karls-University Heidelberg, Heidelberg, Germany.

The neuropathological hallmarks of Parkinson's disease include preferential vulnerability of dopaminergic neurons of the substantia nigra pars compacta, and accumulation of intraneuronal protein inclusions known as Lewy bodies. These inclusions contain, among other proteins, aggregated alpha-synuclein and histone deacetylase 6 (HDAC6). In our study we found that selective inhibition of HDAC6 activity by Tubastatin A has protective effects in a rat model of Parkinson's disease. We provide evidence that this protection may be due to the activation of chaperone-mediated autophagy through the up-regulation of key members of this pathway. Moreover, Tubastatin A significantly inhibited the expression of a toxic form of alpha-synuclein that is phosphorylated at serine position 129. Tubastatin A treatment also permitted to partially modulate neuroinflammation. Taken together, our study highlights the neuroprotective effects of Tubastatin A in a rat model of Parkinson's disease and provides mechanistic insight in Tubastatin A-mediated protection against alpha-synuclein toxicity and substantia nigra degeneration. These findings are of potential therapeutic value in Parkinson's disease and other synucleinopathies.
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http://dx.doi.org/10.1038/s41598-020-62678-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7142125PMC
April 2020

Editorial: Protein Misfolding and Spreading Pathology in Neurodegenerative Diseases.

Front Mol Neurosci 2019 17;12:312. Epub 2020 Jan 17.

Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Gottingen, Göttingen, Germany.

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http://dx.doi.org/10.3389/fnmol.2019.00312DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6978792PMC
January 2020

Identification of antiparkinsonian drugs in the 6-hydroxydopamine zebrafish model.

Pharmacol Biochem Behav 2020 02 28;189:172828. Epub 2019 Nov 28.

TechnoPhage, SA, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal. Electronic address:

Parkinson's disease (PD) is known as a movement disorder due to characteristic motor features. Existing therapies for PD are only symptomatic, and their efficacy decreases as disease progresses. Zebrafish, a vertebrate in which parkinsonism has been modelled, offers unique features for the identification of molecules with antiparkinsonian properties. Here, we developed a screening assay for the selection of neuroactive agents with antiparkinsonian potential. First, we performed a pharmacological validation of the phenotypes exhibited by the 6-hydroxydopamine zebrafish model, by testing the effects of known antiparkinsonian agents. These drugs were also tested for disease-modifying properties by whole mount immunohistochemistry to TH neurons and confocal microscopy in the dopaminergic diencephalic cluster of zebrafish. Next, we optimized a phenotypic screening using the 6-hydroxydopamine zebrafish model and tested 1600 FDA-approved bioactive drugs. We found that 6-hydroxydopamine-lesioned zebrafish larvae exhibit bradykinetic and dyskinetic-like behaviours that are rescued by the administration of levodopa, rasagiline, isradipine or amantadine. The rescue of dopaminergic cell loss by isradipine was also verified, through the observation of a higher number of TH neurons in 6-OHDA-lesioned zebrafish larvae treated with this compound as compared to untreated lesioned larvae. The phenotypic screening enabled us to identify several compounds previously positioned for PD, as well as, new molecules with potential antiparkinsonian properties. Among these, we selected stavudine, tapentadol and nabumetone as the most promising candidates. Our results demonstrate the functional similarities of the motor impairments exhibited by 6-hydroxydopamine-lesioned zebrafish with mammalian models of PD and with PD patients, and highlights novel molecules with antiparkinsonian potential.
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http://dx.doi.org/10.1016/j.pbb.2019.172828DOI Listing
February 2020

Tapentadol Prevents Motor Impairments in a Mouse Model of Dyskinesia.

Neuroscience 2020 01 1;424:58-71. Epub 2019 Nov 1.

Department of Experimental Neurodegeneration, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany; CEDOC, Chronic Diseases Research Centre, NOVA Medical School, Faculdade de Ciências Médicas, Universidade NOVA de Lisboa, Campo dos Mártires da Pátria, 130, 1169-056 Lisboa, Portugal; Max Planck Institute for Experimental Medicine, Goettingen, Germany; Institute of Neuroscience, The Medical School, Newcastle University, Framlington Place, Newcastle Upon Tyne NE2 4HH, UK. Electronic address:

The motor features in Parkinson's disease (PD) are associated with the degeneration of dopaminergic cells in the substantia nigra in the brain. Thus, the gold-standard in PD therapeutics still consists of dopamine replacement with levodopa. However, as the disease progresses, this therapeutic option becomes less effective and can be accompanied by levodopa-induced complications. On the other hand, several other neuronal pathways have been implicated in the pathological mechanisms of PD. In this context, the development of alternative therapeutic options that modulate non-dopaminergic targets is emerging as a major goal in the field. In a phenotypic-based screen in a zebrafish model of PD, we identified tapentadol as a candidate molecule for PD. The therapeutic potential of an agent that modulates the opioid and noradrenergic systems has not been explored, despite the implication of both neuronal pathways in parkinsonism. Therefore, we assessed the therapeutic properties of this µ-opioid receptor agonist and norepinephrine reuptake inhibitor in the 6-hydroxydopamine mouse model of parkinsonism. We further submitted 6-hydroxydopamine-lesioned mice to chronic treatment with levodopa and evaluated the effects of tapentadol during levodopa OFF states and on levodopa-induced dyskinesia. Importantly, we found that tapentadol halted the aggravation of dyskinesia and improved the motor impairments during levodopa OFF states. Altogether, our findings raise the hypothesis that concomitant modulation of µ-opioid receptor and norepinephrine transporter might constitute relevant intervention strategies in PD and that tapentadol holds therapeutic potential that may be translated into the clinical practice.
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http://dx.doi.org/10.1016/j.neuroscience.2019.08.046DOI Listing
January 2020

Molecular characterization of an aggregation-prone variant of alpha-synuclein used to model synucleinopathies.

Biochim Biophys Acta Proteins Proteom 2020 01 30;1868(1):140298. Epub 2019 Oct 30.

Department of Experimental Neurodegeneration, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany; Max Planck Institute for Experimental Medicine, Göttingen, Germany; Institute of Neuroscience, Medical School, Newcastle University, Framlington Place, Newcastle Upon Tyne NE2 4HH, UK. Electronic address:

The misfolding and aggregation of alpha-synuclein (aSyn) are thought to be central events in synucleinopathies. The physiological function of aSyn has been related to vesicle binding and trafficking, but the precise molecular mechanisms leading to aSyn pathogenicity are still obscure. In cell models, aSyn does not readily aggregate, even upon overexpression. Therefore, cellular models that enable the study of aSyn aggregation are essential tools for our understanding of the molecular mechanisms that govern such processes. Here, we investigated the structural features of SynT, an artificial variant of aSyn that has been widely used as a model of aggregation in mammalian cell systems, since it is more prone to aggregation than aSyn. Using Nuclear Magnetic Resonance (NMR) spectroscopy we performed a detailed structural characterization of SynT through a systematic comparison with normal, unmodified aSyn. Interestingly, we found that the conformations adopted by SynT resemble those described for the unmodified protein, demonstrating the usefulness of SynT as a model for aSyn aggregation. However, subtle differences were observed at the N-terminal region involving transient intra and/or intermolecular interactions that are known to regulate aSyn aggregation. Importantly, our results indicate that disturbances in the N-terminal region of SynT, and the consequent decrease in membrane binding of the modified protein, might contribute to the observed aggregation behavior of aSyn, and validate the use of SynT, one of the few models of aSyn aggregation in cultured cells.
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http://dx.doi.org/10.1016/j.bbapap.2019.140298DOI Listing
January 2020
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