| 1. |
- Reyes, Juan, et al.
(författare)
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Accumulation of alpha-synuclein within the liver, potential role in the clearance of brain pathology associated with Parkinsons disease
- 2021
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Ingår i: Acta neuropathologica communications. - : BMC. - 2051-5960. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Alpha-synuclein (alpha-syn) aggregation is the hallmark pathological lesion in brains of patients with Parkinsons disease (PD) and related neurological disorders characterized as synucleinopathies. Accumulating evidence now indicates that alpha-syn deposition is also present within the gut and other peripheral organs outside the central nervous system (CNS). In the current study, we demonstrate for the first time that alpha-syn pathology also accumulates within the liver, the main organ responsible for substance clearance and detoxification. We further demonstrate that cultured human hepatocytes readily internalize oligomeric alpha-syn assemblies mediated, at least in part, by the gap junction protein connexin-32 (Cx32). Moreover, we identified a time-dependent accumulation of alpha-syn within the liver of three different transgenic (tg) mouse models expressing human alpha-syn under CNS-specific promoters, despite the lack of alpha-syn mRNA expression within the liver. Such a brain-to-liver transmission route could be further corroborated by detection of alpha-syn pathology within the liver of wild type mice one month after a single striatal alpha-syn injection. In contrast to the synucleinopathy models, aged mice modeling AD rarely show any amyloid-beta (Ass) deposition within the liver. In human post-mortem liver tissue, we identified cases with neuropathologically confirmed alpha-syn pathology containing alpha-syn within hepatocellular structures to a higher degree (75%) than control subjects without alpha-syn accumulation in the brain (57%). Our results reveal that alpha-syn accumulates within the liver and may be derived from the brain or other peripheral sources. Collectively, our findings indicate that the liver may play a role in the clearance and detoxification of pathological proteins in PD and related synucleinopathies.
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| 2. |
- Reyes, Juan, et al.
(författare)
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Binding of alfa-synuclein oligomers to Cx32 facilitates protein uptake and transfer in neurons and oligodendrocytes
- 2019
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Ingår i: Acta Neuropathologica. - : SPRINGER. - 0001-6322 .- 1432-0533. ; 138:1, s. 23-47
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Tidskriftsartikel (refereegranskat)abstract
- The intercellular transfer of alpha-synuclein (-syn) has been implicated in the progression of Parkinson's disease (PD) and multiple system atrophy (MSA). The cellular mechanisms underlying this process are now beginning to be elucidated. In this study, we demonstrate that the gap junction protein connexin-32 (Cx32) is centrally involved in the preferential uptake of -syn oligomeric assemblies (o-syn) in neurons and oligodendrocytes. In vitro, we demonstrate a clear correlation between Cx32 expression and o-syn uptake. Pharmacological and genetic strategies targeting Cx32 successfully blocked o-syn uptake. In cellular and transgenic mice modeling PD and MSA, we observed significant upregulation of Cx32 which correlates with -syn accumulation. Notably, we could alsodemonstrate a direct interaction between -syn and Cx32 in two out of four human PD cases that was absent in all four age-matched controls. These data are suggestive of a link between Cx32 and PD pathophysiology. Collectively, our results provide compelling evidence for Cx32 as a novel target for therapeutic intervention in PD and related -synucleinopathies.
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| 3. |
- Ansell - Schultz, Anna, et al.
(författare)
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Reduced retromer function results in the accumulation of amyloid-beta oligomers
- 2018
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Ingår i: Molecular and Cellular Neuroscience. - : Academic Press. - 1044-7431 .- 1095-9327. ; 93, s. 18-26
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimers disease (AD) is a neurodegenerative disorder characterized by a progressive loss of multiple cognitive functions. Accumulation of amyloid beta oligomers (oA beta) play a major role in the neurotoxicity associated with the disease process. One of the early affected brain regions is the hippocampus, wherein a reduction of the vacuolar protein sorting-associated protein 35 (VPS35), the core protein comprising the retromer complex involved in cellular cargo sorting, has been identified. To investigate the role of the retromer function on the accumulation and clearance of oA beta, we reduced retromer function by selectively inhibiting VPS35 gene expression using siRNA in differentiated neuronal SH-SY5Y cells. As cell-to-cell transfer of oA beta to new brain regions is believed to be important for disease progression we investigated the effect of VPS35 reduction both in cells with direct uptake of oA beta and in cells receiving oA beta from donor cells. We demonstrate that reduced retromer function increases oA beta accumulation in both cell systems, both the number of cells containing intracellular oA beta and the amount within them. This effect was shown at different time points and regardless if the AD originated from the extracellular milieu or via a direct neuronal cell-to-cell transfer. Interestingly, not only did reduced VPS35 cause oA beta accumulation, but oA beta treatment alone also lead to a reduction of VPS35 protein content. The accumulated oA beta seems to co-localize with VPS35 and early endosome markers. Together, these findings provide evidence that reduced retromer function decreases the ability for neurons to transport and clear neurotoxic oA beta received through different routes resulting in the accumulation of oA beta. Thus, enhancing retromer function may be a potential therapeutic strategy to slow down the pathophysiology associated with the progression of AD.
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| 4. |
- Azevedo, Carla, et al.
(författare)
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Parkinsons disease and multiple system atrophy patient iPSC-derived oligodendrocytes exhibit alpha-synuclein-induced changes in maturation and immune reactive properties
- 2022
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 119:12
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Tidskriftsartikel (refereegranskat)abstract
- Limited evidence has shed light on how aSYN proteins affect the oligodendrocyte phenotype and pathogenesis in synucleinopathies that include Parkinsons disease (PD) and multiple system atrophy (MSA). Here, we investigated early transcriptomic changes within PD and MSA O4(+) oligodendrocyte lineage cells (OLCs) generated from patient-induced pluripotent stem cells (iPSCs). We found impaired maturation of PD and MSA O4(+) OLCs compared to controls. This phenotype was associated with changes in the human leukocyte antigen (HLA) genes, the immunoproteasome subunit PSMB9, and the complement component C4b for aSYN p.A53T and MSA O4(+) OLCs, but not in SNCA(trip) O4(+) OLCs despite high levels of aSYN assembly formation. Moreover, SNCA overexpression resulted in the development of O4(+) OLCs, whereas exogenous treatment with aSYN species led to significant toxicity. Notably, transcriptome profiling of genes encoding proteins forming Lewy bodies and glial cytoplasmic inclusions revealed clustering of PD aSYN p.A53T O4(+) OLCs with MSA O4(+) OLCs. Our work identifies early phenotypic and pathogenic changes within human PD and MSA O4(+) OLCs.
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| 5. |
- Johansson, Lovisa, et al.
(författare)
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Lack of cellular prion protein causes Amyloid ß accumulation, increased extracellular vesicle abundance, and changes to exosome biogenesis proteins
- 2024
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Ingår i: Molecular and Cellular Biochemistry. - : SPRINGER. - 0300-8177 .- 1573-4919.
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease (AD) progression is closely linked to the propagation of pathological Amyloid beta (A beta), a process increasingly understood to involve extracellular vesicles (EVs), namely exosomes. The specifics of A beta packaging into exosomes remain elusive, although evidence suggests an ESCRT (Endosomal Sorting Complex Required for Transport)-independent origin to be responsible in spreading of AD pathogenesis. Intriguingly, PrPC, known to influence exosome abundance and bind oligomeric A beta (oA beta), can be released in exosomes via both ESCRT-dependent and ESCRT-independent pathways, raising questions about its role in oA beta trafficking. Thus, we quantified A beta levels within EVs, cell medium, and intracellularly, alongside exosome biogenesis-related proteins, following deletion or overexpression of PrPC. The same parameters were also evaluated in the presence of specific exosome inhibitors, namely Manumycin A and GW4869. Our results revealed that deletion of PrPC increases intracellular A beta accumulation and amplifies EV abundance, alongside significant changes in cellular levels of exosome biogenesis-related proteins Vps25, Chmp2a, and Rab31. In contrast, cellular expression of PrPC did not alter exosomal A beta levels. This highlights PrPC's influence on exosome biogenesis, albeit not in direct A beta packaging. Additionally, our data confirm the ESCRT-independent exosome release of A beta and we show a direct reduction in Chmp2a levels upon oA beta challenge. Furthermore, inhibition of opposite exosome biogenesis pathway resulted in opposite cellular PrPC levels. In conclusion, our findings highlight the intricate relationship between PrPC, exosome biogenesis, and A beta release. Specifically, they underscore PrPC's critical role in modulating exosome-associated proteins, EV abundance, and cellular A beta levels, thereby reinforcing its involvement in AD pathogenesis.Graphical abstractThere are two main exosome biogenesis pathways: ESCRT dependent and ESCRT independent. In this study, we explored the effect of the cellular prion protein (PrPC) on the release of Amyloid beta via exosomes. Our findings demonstrate that Amyloid beta mainly is released via an ESCRT-independent pathway, independent of PrPC. However, lack of PrPC resulted in upregulation of the ESCRT-dependent proteins Tsg101 and VPS25, a decrease in Chmp2a, and an overall increase in extracellular vesicles. Lack of PrPC also caused an accumulation of cellular, but not exosomal, Amyloid beta.
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| 6. |
- Moudio, Serge, et al.
(författare)
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Exposure of alpha-Synuclein Aggregates to Organotypic Slice Cultures Recapitulates Key Molecular Features of Parkinsons Disease
- 2022
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Ingår i: Frontiers in Neurology. - : Frontiers Media SA. - 1664-2295. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- The accumulation of proteinaceous deposits comprised largely of the alpha-synuclein protein is one of the main hallmarks of Parkinsons disease (PD) and related synucleinopathies. Their progressive development coincides with site-specific phosphorylation, oxidative stress and eventually, compromised neuronal function. However, modeling protein aggregate formation in animal or in vitro models has proven notably difficult. Here, we took advantage of a preclinical organotypic brain slice culture model to study alpha-synuclein aggregate formation ex vivo. We monitored the progressive and gradual changes induced by alpha-synuclein such as cellular toxicity, autophagy activation, mitochondrial dysfunction, cellular death as well as alpha-synuclein modification including site-specific phosphorylation. Our results demonstrate that organotypic brain slice cultures can be cultured for long periods of time and when cultured in the presence of aggregated alpha-synuclein, the molecular features of PD are recapitulated. Taken together, this ex vivo model allows for detailed modeling of the molecular features of PD, thus enabling studies on the cumulative effects of alpha-synuclein in a complex environment. This provides a platform to screen potential disease-modifying therapeutic candidates aimed at impeding alpha-synuclein aggregation and/or cellular transmission. Moreover, this model provides a robust replacement for in vivo studies that do not include behavioral experiments, thus providing a way to reduce the number of animals used in an accelerated timescale.
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