| 1. |
- Brundin, Patrik, et al.
(författare)
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Prion-like transmission of protein aggregates in neurodegenerative diseases.
- 2010
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Ingår i: Nature Reviews. Molecular Cell Biology. - : Springer Science and Business Media LLC. - 1471-0072 .- 1471-0080. ; 11:4, s. 301-307
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Forskningsöversikt (refereegranskat)abstract
- Neurodegenerative diseases are commonly associated with the accumulation of intracellular or extracellular protein aggregates. Recent studies suggest that these aggregates are capable of crossing cellular membranes and can directly contribute to the propagation of neurodegenerative disease pathogenesis. We propose that, once initiated, neuropathological changes might spread in a 'prion-like' manner and that disease progression is associated with the intercellular transfer of pathogenic proteins. The transfer of naked infectious particles between cells could therefore be a target for new disease-modifying therapies.
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| 2. |
- Camacho, Rafael, et al.
(författare)
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2D polarization imaging as a low-cost fluorescence method to detect α-synuclein aggregation ex vivo in models of Parkinson’s disease
- 2018
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- A hallmark of Parkinson’s disease is the formation of large protein-rich aggregates in neurons, where α-synuclein is the most abundant protein. A standard approach to visualize aggregation is to fluorescently label the proteins of interest. Then, highly fluorescent regions are assumed to contain aggregated proteins. However, fluorescence brightness alone cannot discriminate micrometer-sized regions with high expression of non-aggregated proteins from regions where the proteins are aggregated on the molecular scale. Here, we demonstrate that 2-dimensional polarization imaging can discriminate between preformed non-aggregated and aggregated forms of α-synuclein, and detect increased aggregation in brain tissues of transgenic mice. This imaging method assesses homo-FRET between labels by measuring fluorescence polarization in excitation and emission simultaneously, which translates into higher contrast than fluorescence anisotropy imaging. Exploring earlier aggregation states of α-synuclein using such technically simple imaging method could lead to crucial improvements in our understanding of α-synuclein-mediated pathology in Parkinson’s Disease.
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| 3. |
- De Mattos, Eduardo P., et al.
(författare)
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Protein Quality Control Pathways at the Crossroad of Synucleinopathies
- 2020
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Ingår i: Journal of Parkinson's Disease. - 1877-7171. ; 10:2, s. 369-382
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Forskningsöversikt (refereegranskat)abstract
- The pathophysiology of Parkinson's disease, dementia with Lewy bodies, multiple system atrophy, and many others converge at alpha-synuclein (α-Syn) aggregation. Although it is still not entirely clear what precise biophysical processes act as triggers, cumulative evidence points towards a crucial role for protein quality control (PQC) systems in modulating α-Syn aggregation and toxicity. These encompass distinct cellular strategies that tightly balance protein production, stability, and degradation, ultimately regulating α-Syn levels. Here, we review the main aspects of α-Syn biology, focusing on the cellular PQC components that are at the heart of recognizing and disposing toxic, aggregate-prone α-Syn assemblies: molecular chaperones and the ubiquitin-proteasome system and autophagy-lysosome pathway, respectively. A deeper understanding of these basic protein homeostasis mechanisms might contribute to the development of new therapeutic strategies envisioning the prevention and/or enhanced degradation of α-Syn aggregates.
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| 4. |
- Guo, Jian Jun, et al.
(författare)
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Intranasal administration of α-synuclein preformed fibrils triggers microglial iron deposition in the substantia nigra of Macaca fascicularis
- 2021
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Ingår i: Cell Death and Disease. - : Springer Science and Business Media LLC. - 2041-4889. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Iron deposition is present in main lesion areas in the brains of patients with Parkinson’s disease (PD) and an abnormal iron content may be associated with dopaminergic neuronal cytotoxicity and degeneration in the substantia nigra of the midbrain. However, the cause of iron deposition and its role in the pathological process of PD are unclear. In the present study, we investigated the effects of the nasal mucosal delivery of synthetic human α-synuclein (α-syn) preformed fibrils (PFFs) on the pathogenesis of PD in Macaca fascicularis. We detected that iron deposition was clearly increased in a time-dependent manner from 1 to 17 months in the substantia nigra and globus pallidus, highly contrasting to other brain regions after treatments with α-syn PFFs. At the cellular level, the iron deposits were specifically localized in microglia but not in dopaminergic neurons, nor in other types of glial cells in the substantia nigra, whereas the expression of transferrin (TF), TF receptor 1 (TFR1), TF receptor 2 (TFR2), and ferroportin (FPn) was increased in dopaminergic neurons. Furthermore, no clear dopaminergic neuron loss was observed in the substantia nigra, but with decreased immunoreactivity of tyrosine hydroxylase (TH) and appearance of axonal swelling in the putamen. The brain region-enriched and cell-type-dependent iron localizations indicate that the intranasal α-syn PFFs treatment-induced iron depositions in microglia in the substantia nigra may appear as an early cellular response that may initiate neuroinflammation in the dopaminergic system before cell death occurs. Our data suggest that the inhibition of iron deposition may be a potential approach for the early prevention and treatment of PD.
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| 5. |
- Hansen, Christian, et al.
(författare)
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alpha-Synuclein propagates from mouse brain to grafted dopaminergic neurons and seeds aggregation in cultured human cells
- 2011
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Ingår i: Journal of Clinical Investigation. - 0021-9738. ; 121:2, s. 715-725
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Tidskriftsartikel (refereegranskat)abstract
- Post-mortem analyses of brains from patients with Parkinson disease who received fetal mesencephalic transplants show that alpha-synuclein-containing (alpha-syn-containing) Lewy bodies gradually appear in grafted neurons. Here, we explored whether intercellular transfer of alpha-syn from host to graft, followed by seeding of alpha-syn aggregation in recipient neurons, can contribute to this phenomenon. We assessed alpha-syn cell-to-cell transfer using microscopy, flow cytometry, and high-content screening in several coculture model systems. Coculturing cells engineered to express either GFP- or DsRed-tagged alpha-syn resulted in a gradual increase in double-labeled cells. Importantly, alpha-syn-GFP derived from 1 neuroblastoma cell line localized to red fluorescent aggregates in other cells expressing DsRed-alpha-syn, suggesting a seeding effect of transmitted alpha-syn. Extracellular alpha-syn was taken up by cells through endocytosis and interacted with intracellular alpha-syn. Next, following intracortical injection of recombinant alpha-syn in rats, we found neuronal uptake was attenuated by coinjection of an endocytosis inhibitor. Finally, we demonstrated in vivo transfer of alpha-syn between host cells and grafted dopaminergic neurons in mice overexpressing human alpha-syn. In summary, intercellularly transferred alpha-syn interacts with cytoplasmic alpha-syn and can propagate alpha-syn pathology. These results suggest that alpha-syn propagation is a key element in the progression of Parkinson disease pathology.
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| 6. |
- Holmqvist, Staffan, et al.
(författare)
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Direct evidence of Parkinson pathology spread from the gastrointestinal tract to the brain in rats.
- 2014
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Ingår i: Acta Neuropathologica. - : Springer Science and Business Media LLC. - 1432-0533 .- 0001-6322. ; 128:6, s. 805-820
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Tidskriftsartikel (refereegranskat)abstract
- The cellular hallmarks of Parkinson's disease (PD) are the loss of nigral dopaminergic neurons and the formation of α-synuclein-enriched Lewy bodies and Lewy neurites in the remaining neurons. Based on the topographic distribution of Lewy bodies established after autopsy of brains from PD patients, Braak and coworkers hypothesized that Lewy pathology primes in the enteric nervous system and spreads to the brain, suggesting an active retrograde transport of α-synuclein (the key protein component in Lewy bodies), via the vagal nerve. This hypothesis, however, has not been tested experimentally thus far. Here, we use a human PD brain lysate containing different forms of α-synuclein (monomeric, oligomeric and fibrillar), and recombinant α-synuclein in an in vivo animal model to test this hypothesis. We demonstrate that α-synuclein present in the human PD brain lysate and distinct recombinant α-synuclein forms are transported via the vagal nerve and reach the dorsal motor nucleus of the vagus in the brainstem in a time-dependent manner after injection into the intestinal wall. Using live cell imaging in a differentiated neuroblastoma cell line, we determine that both slow and fast components of axonal transport are involved in the transport of aggregated α-synuclein. In conclusion, we here provide the first experimental evidence that different α-synuclein forms can propagate from the gut to the brain, and that microtubule-associated transport is involved in the translocation of aggregated α-synuclein in neurons.
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| 7. |
- Kakkar, Vaishali, et al.
(författare)
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The S/T-Rich Motif in the DNAJB6 Chaperone Delays Polyglutamine Aggregation and the Onset of Disease in a Mouse Model
- 2016
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Ingår i: Molecular Cell. - : Elsevier BV. - 1097-2765. ; 62:2, s. 272-283
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Tidskriftsartikel (refereegranskat)abstract
- Expanded CAG repeats lead to debilitating neurodegenerative disorders characterized by aggregation of proteins with expanded polyglutamine (polyQ) tracts. The mechanism of aggregation involves primary and secondary nucleation steps. We show how a noncanonical member of the DNAJ-chaperone family, DNAJB6, inhibits the conversion of soluble polyQ peptides into amyloid fibrils, in particular by suppressing primary nucleation. This inhibition is mediated by a serine/threonine-rich region that provides an array of surface-exposed hydroxyl groups that bind to polyQ peptides and may disrupt the formation of the H bonds essential for the stability of amyloid fibrils. Early prevention of polyQ aggregation by DNAJB6 occurs also in cells and leads to delayed neurite retraction even before aggregates are visible. In a mouse model, brain-specific coexpression of DNAJB6 delays polyQ aggregation, relieves symptoms, and prolongs lifespan, pointing to DNAJB6 as a potential target for disease therapy and tool for unraveling early events in the onset of polyQ diseases. Kakkar et al. show that DNAJB6 is a chaperone that inhibits early steps in the formation of polyQ amyloid fibrils. An S/T-rich region in DNAJB6 is crucial for this function. In a polyQ mouse model, the inhibitory effects of DNAJB6 delay disease onset and increase lifespan.
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| 8. |
- Månsson, Cecilia, et al.
(författare)
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DNAJB6 is a peptide-binding chaperone which can suppress amyloid fibrillation of polyglutamine peptides at substoichiometric molar ratios.
- 2014
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Ingår i: Cell Stress & Chaperones. - : Springer Science and Business Media LLC. - 1466-1268 .- 1355-8145. ; 19:2, s. 227-239
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Tidskriftsartikel (refereegranskat)abstract
- Expanded polyglutamine (polyQ) stretches lead to protein aggregation and severe neurodegenerative diseases. A highly efficient suppressor of polyQ aggregation was identified, the DNAJB6, when molecular chaperones from the HSPH, HSPA, and DNAJ families were screened for huntingtin exon 1 aggregation in cells (Hageman et al. in Mol Cell 37(3):355-369, 2010). Furthermore, also aggregation of polyQ peptides expressed in cells was recently found to be efficiently suppressed by co-expression of DNAJB6 (Gillis et al. in J Biol Chem 288:17225-17237, 2013). These suppression effects can be due to an indirect effect of DNAJB6 on other cellular components or to a direct interaction between DNAJB6 and polyQ peptides that may depend on other cellular components. Here, we have purified the DNAJB6 protein to investigate the suppression mechanism. The purified DNAJB6 protein formed large heterogeneous oligomers, in contrast to the more canonical family member DNAJB1 which is dimeric. Purified DNAJB6 protein, at substoichiometric molar ratios, efficiently suppressed fibrillation of polyQ peptides with 45°Q in a thioflavin T fibrillation. No suppression was obtained with DNAJB1, but with the closest homologue to DNAJB6, DNAJB8. The suppression effect was independent of HSPA1 and ATP. These data, based on purified proteins and controlled fibrillation in vitro, strongly suggest that the fibrillation suppression is due to a direct protein-protein interaction between the polyQ peptides and DNAJB6 and that the DNAJB6 has unique fibrillation suppression properties lacking in DNAJB1. Together, the data obtained in cells and in vitro support the view that DNAJB6 is a peptide-binding chaperone that can interact with polyQ peptides that are incompletely degraded by and released from the proteasome.
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| 9. |
- Negrini, Matilde, et al.
(författare)
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Sequential or Simultaneous Injection of Preformed Fibrils and AAV Overexpression of Alpha-Synuclein Are Equipotent in Producing Relevant Pathology and Behavioral Deficits
- 2022
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Ingår i: Journal of Parkinson's Disease. - 1877-7171. ; 12:4, s. 1133-1153
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Tidskriftsartikel (refereegranskat)abstract
- Background: Preclinical rodent models for Parkinson's disease (PD) based on viral human alpha-synuclein (h-αSyn) overexpression recapitulate some of the pathological hallmarks as it presents in humans, such as progressive cell loss and additional synucleinopathy in cortical and subcortical structures. Recent studies have combined viral vector-based overexpression of human wild-type αSyn with the sequential or simultaneous inoculation of preformed fibrils (PFFs) derived from human αSyn. Objective: The goal of the study was to investigate whether sequential or combined delivery of the AAV vector and the PFFs are equipotent in inducing stable neurodegeneration and behavioral deficits. Methods: Here we compare between four experimental paradigms (PFFs only, AAV-h-αSyn only, AAV-h-αSyn with simultaneous PFFs, and AAV-h-αSyn with sequential PFFs) and their respective GFP control groups. Results: We observed reduction of TH expression and loss of neurons in the midbrain in all AAV (h-αSyn or GFP) injected groups, with or without additional PFFs inoculation. The overexpression of either h-αSyn or GFP alone induced motor deficits and dysfunctional dopamine release/reuptake in electrochemical recordings in the ipsilateral striatum. However, we observed a substantial formation of insoluble h-αSyn aggregates and inflammatory response only when h-αSyn and PFFs were combined. Moreover, the presence of h-αSyn induced higher axonal pathology compared to control groups. Conclusion: Simultaneous AAV and PFFs injections are equipotent in the presented experimental setup in inducing histopathological and behavioral changes. This model provides new and interesting possibilities for characterizing PD pathology in preclinical models and means to assess future therapeutic interventions.
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| 10. |
- Rey, Nolwen, et al.
(författare)
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Transfer of human α-synuclein from the olfactory bulb to interconnected brain regions in mice.
- 2013
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Ingår i: Acta Neuropathologica. - : Springer Science and Business Media LLC. - 1432-0533 .- 0001-6322. ; 126:4, s. 555-573
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Tidskriftsartikel (refereegranskat)abstract
- α-Synuclein (α-syn) is a protein prevalent in neural tissue and known to undergo axonal transport. Intracellular α-syn aggregates are a hallmark of Parkinson's disease (PD). Braak and collaborators have suggested that in people who are destined to eventually develop PD, α-syn aggregate pathology progresses following a stereotypic pattern, starting in the olfactory bulb (OB) and the gut. α-Synuclein aggregates are postulated to spread to interconnected brain regions over several years. Thus, propagation of the pathology via neural pathways can potentially explain how α-syn aggregates spread in PD. We have now studied if α-syn can transfer from the OB to other brain structures through neural connections, by injecting different molecular species of human α-syn (monomers, oligomers, fibrils) into the OB of wild-type mice. We found that non-fibrillar human α-syn is taken up very quickly by OB neurons. Within minutes to hours, it is also found in neurons in structures connected to the OB. Conversely, when we injected bovine serum albumin used as a control protein, we found that it does not diffuse beyond the OB, is rarely taken up by OB cells, and does not transfer to other structures. Taken together, our results show that OB cells readily take up α-syn, and that monomeric and oligomeric, but not fibrillar, forms of α-syn are rapidly transferred to interconnected structures within the timeframe we explored. Our results support the idea that α-syn can transfer along neural pathways and thereby contribute to the progression of the α-syn-related pathology.
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