Author
Karin M Danzer
Other affiliations: German Center for Neurodegenerative Diseases, Harvard University, Boehringer Ingelheim
Bio: Karin M Danzer is an academic researcher from University of Ulm. The author has contributed to research in topics: Alpha-synuclein & Amyotrophic lateral sclerosis. The author has an hindex of 31, co-authored 65 publications receiving 5168 citations. Previous affiliations of Karin M Danzer include German Center for Neurodegenerative Diseases & Harvard University.
Papers published on a yearly basis
Papers
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TL;DR: The data suggest that αsyn may be secreted via different secretory pathways, and hypothesize that exosome-mediated release of αsyn oligomers is a mechanism whereby cells clear toxic α synuclein oligomers when autophagic mechanisms fail to be sufficient.
Abstract: Aggregation of alpha-synuclein (αsyn) and resulting cytotoxicity is a hallmark of sporadic and familial Parkinson’s disease (PD) as well as dementia with Lewy bodies, with recent evidence implicating oligomeric and pre-fibrillar forms of αsyn as the pathogenic species. Recent in vitro studies support the idea of transcellular spread of extracellular, secreted αsyn across membranes. The aim of this study is to characterize the transcellular spread of αsyn oligomers and determine their extracellular location. Using a novel protein fragment complementation assay where αsyn is fused to non-bioluminescent amino-or carboxy-terminus fragments of humanized Gaussia Luciferase we demonstrate here that αsyn oligomers can be found in at least two extracellular fractions: either associated with exosomes or free. Exosome-associated αsyn oligomers are more likely to be taken up by recipient cells and can induce more toxicity compared to free αsyn oligomers. Specifically, we determine that αsyn oligomers are present on both the outside as well as inside of exosomes. Notably, the pathway of secretion of αsyn oligomers is strongly influenced by autophagic activity. Our data suggest that αsyn may be secreted via different secretory pathways. We hypothesize that exosome-mediated release of αsyn oligomers is a mechanism whereby cells clear toxic αsyn oligomers when autophagic mechanisms fail to be sufficient. Preventing the early events in αsyn exosomal release and uptake by inducing autophagy may be a novel approach to halt disease spreading in PD and other synucleinopathies.
711 citations
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TL;DR: The data indicate that inhibition of early α- syn aggregation events would consequently prevent all α-syn oligomer related toxicities, which has important implications for the development of disease-modifying drugs for the treatment of PD and other synucleinopathies.
Abstract: Aggregation of α-synuclein (α-syn) has been linked to the pathogenesis of Parkinson's disease (PD) and other neurodegenerative diseases Increasing evidence suggests that prefibrillar oligomers and protofibrils, rather than mature fibrils of α-syn, are the pathogenic species in PD Despite extensive effort on studying oligomerization of α-syn, no studies have compared different oligomer species directly on a single-particle level and investigated their biological effects on cells In this study, we applied a novel highly sensitive single molecule detection system that allowed a direct comparison of different oligomer types Furthermore, we studied biological effects of different oligomer types on cells For this purpose, we developed new oligomerization protocols, that enabled the use of these different oligomers in cell culture We found that all of our three aggregation protocols resulted in heterogeneous populations of oligomers Some types of oligomers induced cell death via disruption of cellular ion homeostasis by a presumably pore-forming mechanism Other oligomer types could directly enter the cell resulting in increased α-syn aggregation Based on our results, we propose that under various physiological conditions, heterogeneous populations of oligomeric forms will coexist in an equilibrium These different oligomer types lead directly or indirectly to cell damage Our data indicate that inhibition of early α-syn aggregation events would consequently prevent all α-syn oligomer related toxicities This has important implications for the development of disease-modifying drugs for the treatment of PD and other synucleinopathies
694 citations
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TL;DR: It is concluded that haploinsufficiency of TBK1 causes ALS and fronto-temporal dementia.
Abstract: Amyotrophic lateral sclerosis (ALS) is a genetically heterogeneous neurodegenerative syndrome hallmarked by adult-onset loss of motor neurons. We performed exome sequencing of 252 familial ALS (fALS) and 827 control individuals. Gene-based rare variant analysis identified an exome-wide significant enrichment of eight loss-of-function (LoF) mutations in TBK1 (encoding TANK-binding kinase 1) in 13 fALS pedigrees. No enrichment of LoF mutations was observed in a targeted mutation screen of 1,010 sporadic ALS and 650 additional control individuals. Linkage analysis in four families gave an aggregate LOD score of 4.6. In vitro experiments confirmed the loss of expression of TBK1 LoF mutant alleles, or loss of interaction of the C-terminal TBK1 coiled-coil domain (CCD2) mutants with the TBK1 adaptor protein optineurin, which has been shown to be involved in ALS pathogenesis. We conclude that haploinsufficiency of TBK1 causes ALS and fronto-temporal dementia.
635 citations
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TL;DR: CSF exosomes of patients with Parkinson’s disease or dementia with Lewy bodies contain α- synuclein and induce α-synuclein aggregation in a reporter cell line, indicating that exosome support may support inter-neuronal transmission of α- Synuclein pathology.
Abstract: Extracellular α-synuclein has been proposed as a crucial mechanism for induction of pathological aggregate formation in previously healthy cells. In vitro, extracellular α-synuclein is partially associated with exosomal vesicles. Recently, we have provided evidence that exosomal α-synuclein is present in the central nervous system in vivo. We hypothesized that exosomal α-synuclein species from patients with α-synuclein related neurodegeneration serve as carriers for interneuronal disease transmission. We isolated exosomes from cerebrospinal fluid from patients with Parkinson's disease, dementia with Lewy bodies, progressive supranuclear palsy as a non-α-synuclein related disorder that clinically overlaps with Parkinson's disease, and neurological controls. Cerebrospinal fluid exosome numbers, α-synuclein protein content of cerebrospinal fluid exosomes and their potential to induce oligomerization of α-synuclein were analysed. The quantification of cerebrospinal fluid exosomal α-synuclein showed distinct differences between patients with Parkinson's disease and dementia with Lewy bodies. In addition, exosomal α-synuclein levels correlated with the severity of cognitive impairment in cross-sectional samples from patients with dementia with Lewy bodies. Importantly, cerebrospinal fluid exosomes derived from Parkinson's disease and dementia with Lewy bodies induce oligomerization of α-synuclein in a reporter cell line in a dose-dependent manner. Our data suggest that cerebrospinal fluid exosomes from patients with Parkinson's disease and dementia with Lewy bodies contain a pathogenic species of α-synuclein, which could initiate oligomerization of soluble α-synuclein in target cells and confer disease pathology.
314 citations
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TL;DR: In a cellular model, the presence of αsyn oligomers in the extracellular space, their uptake by neurons, retrograde axonal transport to cell soma, and detrimental effects on neighboring cells are demonstrated and their modulation by Hsp70 represents a potential new target for therapeutic interventions.
Abstract: The paradoxical appearance of aggregated α-synuclein (αsyn) in naive transplanted embryonic stem cells in Parkinson's disease (PD) brains has recently been reported, highlighting the possibility of neuron to neuron transmission of αsyn in PD. Here, we demonstrate in a cellular model the presence of αsyn oligomers in the extracellular space, their uptake by neurons, retrograde axonal transport to cell soma, and detrimental effects on neighboring cells. Moreover, we demonstrate that Hsp70 chaperones αsyn in the extracellular space and reduces extracellular αsyn oligomer formation and related toxicity. These novel findings provide evidence that extracellular αsyn oligomers may represent a crucial player in the propagation of pathology in PD, with their modulation by Hsp70 representing a potential new target for therapeutic interventions. —Danzer, K. M., Ruf, W. P., Putcha, P., Joyner, D., Hashimoto, T., Glabe, C., Hyman, B. T., McLean, P. J. Heat-shock protein 70 modulates toxic extracellular α-synuclein oligomers and rescues trans-synaptic toxicity.
294 citations
Cited by
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Harvard University1, Broad Institute2, Boston Children's Hospital3, University of Washington4, University of Arizona5, Cardiff University6, Google7, Icahn School of Medicine at Mount Sinai8, Samsung Medical Center9, Vertex Pharmaceuticals10, University of Michigan11, University of Cambridge12, State University of New York Upstate Medical University13, Karolinska Institutet14, University of Eastern Finland15, University of Oxford16, Wellcome Trust Centre for Human Genetics17, Cedars-Sinai Medical Center18, University of Ottawa19, University of Pennsylvania20, University of North Carolina at Chapel Hill21, University of Helsinki22, University of California, San Diego23, University of Mississippi Medical Center24
TL;DR: The aggregation and analysis of high-quality exome (protein-coding region) DNA sequence data for 60,706 individuals of diverse ancestries generated as part of the Exome Aggregation Consortium (ExAC) provides direct evidence for the presence of widespread mutational recurrence.
Abstract: Large-scale reference data sets of human genetic variation are critical for the medical and functional interpretation of DNA sequence changes. Here we describe the aggregation and analysis of high-quality exome (protein-coding region) DNA sequence data for 60,706 individuals of diverse ancestries generated as part of the Exome Aggregation Consortium (ExAC). This catalogue of human genetic diversity contains an average of one variant every eight bases of the exome, and provides direct evidence for the presence of widespread mutational recurrence. We have used this catalogue to calculate objective metrics of pathogenicity for sequence variants, and to identify genes subject to strong selection against various classes of mutation; identifying 3,230 genes with near-complete depletion of predicted protein-truncating variants, with 72% of these genes having no currently established human disease phenotype. Finally, we demonstrate that these data can be used for the efficient filtering of candidate disease-causing variants, and for the discovery of human 'knockout' variants in protein-coding genes.
8,758 citations
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TL;DR: The intrinsic properties of exosomes in regulating complex intracellular pathways has advanced their potential utility in the therapeutic control of many diseases, including neurodegenerative conditions and cancer.
Abstract: The study of extracellular vesicles (EVs) has the potential to identify unknown cellular and molecular mechanisms in intercellular communication and in organ homeostasis and disease. Exosomes, with an average diameter of ~100 nanometers, are a subset of EVs. The biogenesis of exosomes involves their origin in endosomes, and subsequent interactions with other intracellular vesicles and organelles generate the final content of the exosomes. Their diverse constituents include nucleic acids, proteins, lipids, amino acids, and metabolites, which can reflect their cell of origin. In various diseases, exosomes offer a window into altered cellular or tissue states, and their detection in biological fluids potentially offers a multicomponent diagnostic readout. The efficient exchange of cellular components through exosomes can inform their applied use in designing exosome-based therapeutics.
3,715 citations
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TL;DR: There is evidence for a remarkable convergence in the mechanisms responsible for the sensing, transduction, and amplification of inflammatory processes that result in the production of neurotoxic mediators in neurodegenerative diseases.
2,838 citations
01 Jan 1981
1,737 citations
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TL;DR: It is now apparent that autophagy is deregulated in the context of various human pathologies, including cancer and neurodegeneration, and its modulation has considerable potential as a therapeutic approach.
Abstract: Autophagy is a highly conserved catabolic process induced under various conditions of cellular stress, which prevents cell damage and promotes survival in the event of energy or nutrient shortage and responds to various cytotoxic insults. Thus, autophagy has primarily cytoprotective functions and needs to be tightly regulated to respond correctly to the different stimuli that cells experience, thereby conferring adaptation to the ever-changing environment. It is now apparent that autophagy is deregulated in the context of various human pathologies, including cancer and neurodegeneration, and its modulation has considerable potential as a therapeutic approach.
1,701 citations