| 11. |
- Agholme, Lotta
(författare)
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The involvement of degradation pathways and neuron-to-neuron transmission in Alzheimer’s disease
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Although the vast majority of Alzheimer’s disease (AD) cases are of the sporadic type, mutations causing the familial form have been the focus of AD research for decades. The disease is pathologically characterised by β-amyloid (Aβ) and tau protein aggregates in neuritic plaques and neurofibrillary tangles. Furthermore, it is known that AD pathology spreads throughout the brain, most often along the same anatomical pattern. However, so far no cause for the sporadic form of the disease has been found. Accumulation of protein aggregates as well as decreased activity of the protein degradation systems, lysosomes and proteasomes, is found in diseased brains. This indicates that defective degradation contributes to sporadic AD.The aim of this thesis was to develop an improved neuronal model, and study the effects of decreased proteasome function on tau phosphorylation and axonal transport. In addition, the effects on Aβ accumulation and generation upon proteasome inhibition were investigated. Finally, the possibility that intracellularly accumulated Aβ oligomers could be transferred from one neuron to another was tested.Differentiation of human SH-SY5Y neuroblastoma cells in an extracellular matrix gel, using a set of neurotrophic factors, resulted in cells with neuronal phenotype, expressing neuron specific markers and all six adult isoforms of tau. Within this neuronal model, we found that reduced proteasome activity inhibited neuritic transport, and caused tau phosphorylation in a c-Jun and ERK 1/2 dependent manner. Using proteasome inhibition in APP overexpressing cells, we found an autophagy dependent intralysosomal Aβ accumulation, together with elevation of intra- and extracellular concentrations of Aβ. Autophagy inhibition protected the cells from the toxicity induced by decreased proteasome activity. Finally, we could, as the first group, show that Aβ can be directly transferred from one neuron to another through connected neurites. Furthermore, accumulation of Aβ in the endo-lysosomal compartment of receiving cells caused toxicity and neurodegeneration.We believe that cells not able to degrade accumulated Aβ, due to increased generation or reduced degradative capacity, instead tries to clear its content through transfer to connected neurons. If not properly degraded in the receiving cell, this can accelerate AD pathology and cause neuritic and neuronal degeneration spreading throughout the brain. Increasing the activity of the degradative systems, or inhibiting transmission of Aβ between neurons could therefore be novel treatments for AD.
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| 12. |
- Ali, Tahir, et al.
(författare)
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Cellulose ether treatment inhibits amyloid beta aggregation, neuroinflammation and cognitive deficits in transgenic mouse model of Alzheimers disease
- 2023
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Ingår i: Journal of Neuroinflammation. - : BMC. - 1742-2094. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimers disease (AD) is an incurable, progressive and devastating neurodegenerative disease. Pathogenesis of AD is associated with the aggregation and accumulation of amyloid beta (A & beta;), a major neurotoxic mediator that triggers neuroinflammation and memory impairment. Recently, we found that cellulose ether compounds (CEs) have beneficial effects against prion diseases by inhibiting protein misfolding and replication of prions, which share their replication mechanism with A & beta;. CEs are FDA-approved safe additives in foods and pharmaceuticals. Herein, for the first time we determined the therapeutic effects of the representative CE (TC-5RW) in AD using in vitro and in vivo models. Our in vitro studies showed that TC-5RW inhibits A & beta; aggregation, as well as neurotoxicity and immunoreactivity in A & beta;-exposed human and murine neuroblastoma cells. In in vivo studies, for the first time we observed that single and weekly TC-5RW administration, respectively, improved memory functions of transgenic 5XFAD mouse model of AD. We further demonstrate that TC-5RW treatment of 5XFAD mice significantly inhibited A & beta; oligomer and plaque burden and its associated neuroinflammation via regulating astrogliosis, microgliosis and proinflammatory mediator glial maturation factor beta (GMF & beta;). Additionally, we determined that TC-5RW reduced lipopolysaccharide-induced activated gliosis and GMF & beta; in vitro. In conclusion, our results demonstrate that CEs have therapeutic effects against A & beta; pathologies and cognitive impairments, and direct, potent anti-inflammatory activity to rescue neuroinflammation. Therefore, these FDA-approved compounds are effective candidates for developing therapeutics for AD and related neurodegenerative diseases associated with protein misfolding.
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| 13. |
- Amandusson, Åsa, 1974-, et al.
(författare)
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Estrogen-induced alterations of spinal cord enkephalin gene expression
- 1999
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Ingår i: Pain. - : Elsevier. - 0304-3959 .- 1872-6623. ; 83:2, s. 243-248
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Tidskriftsartikel (refereegranskat)abstract
- Enkephalin-synthesizing neurons in the super®cial laminae of the spinal and trigeminal dorsal horn are critical components of the endogenous pain-modulatory system. We have previously demonstrated that these neurons display intracellular estrogen receptors, suggesting that estrogen can potentially influence their enkephalin expression. By using Northern blot, we now show that a bolus injection of estrogen results in a rapid increase in spinal cord enkephalin mRNA levels in ovariectomized female rats. Thus, 4 h after estrogen administration the enkephalin mRNA-expression in the lumbar spinal cord was on average 68% higher (P , 0:05) than in control animals injected with vehicle only. A small increase in the amount of enkephalin mRNA was also seen after 8 h (P , 0:05), whereas no difference between estrogen-injected and control animals was found after 24 h or at time periods shorter than 4 h. Taken together with the previous anatomical data, the present findings imply that estrogen has an acute effect on spinal opioid levels in areas involved in the transmission of nociceptive information.
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| 14. |
- Andin, Josefine, et al.
(författare)
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Environmental enrichment induces changes in the mRNA expression of rat EAAC1 and NMDA but not in AMPA
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Interaction with the environment has a key role in refining the neuronal circuitry required for normal brain function throughout life. Profound effects of enriched environment has been shown on neuronal strucrure and chemistry in experimental animals. Epidemiological studies imply that this is true also in man, thus cognitive stimulation has a protective effect on neurodegeneration, e.g. Alzheimer's disease. Glutamatergic corticocortical pathways are imperative for cognitive functions, such as memory and learning, and long term porenriation relies on the AMPA and NMDAglutamate rcceptors. The glutamate signalling is also dependent on a fine-runed transport system, in the hippocampus primarily by theglutamate transporter EAACl. In this study we show how environmental enrichment modulates these parts of the glutamarergic system using in siru hybridization. This work demonstrates for the first time that environmental enrichment modulates the mRNA expression of EAAC1 which is significantly decreased in hippocampal and cortical areas. We also provide further evidence about the upregulation of NMDA mRNA after environmental enrichement, and show it to have a regionally and hemisphere specific regulation. The current work also confirms that AMPA mRNA is nor per se changed by environmental enrichment in adult animals. Taken together, our results extend the knowledge of the glutamatergic system and its modulation by environmental enrichment and could contribute to the development of strategies aimed at limiting pathological changes associated with glutamatergic dysfunctions.
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| 15. |
- Andin, Josefine, 1979-, et al.
(författare)
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Influence of environmental enrichment on steady-state mRNA levels for EAAC1, AMPA1 and NMDA2A receptor subunits in rat hippocampus
- 2007
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Ingår i: Brain Research. - : Elsevier BV. - 0006-8993 .- 1872-6240. ; 1174:1, s. 18-27
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Tidskriftsartikel (refereegranskat)abstract
- Interaction with the environment has a key role in refining the neuronal circuitry required for normal brain function throughout life. Profound effects of enriched environment have been shown on neuronal structure and chemistry in experimental animals. Epidemiological studies imply that this is true also in man, thus cognitive stimulation has a protective effect on neurodegeneration, e.g., in Alzheimer's disease. Glutamatergic pathways are imperative for cognitive functions, such as memory, learning and long-term potentiation, and relies on the AMPA and NMDA glutamate receptors and the hippocampus, with its specific subregions, is an important anatomical substrate in this. The glutamate signalling is also dependent on a fine-tuned transport system, in the hippocampus primarily achieved by the glutamate transporter EAAC1. In this study we show how environmental enrichment modulates these parts of the glutamatergic system using quantitative in situ hybridisation. This work demonstrates for the first time that environmental enrichment modulates the mRNA expression of EAAC1 which is significantly and region specifically decreased in the hippocampus. We also provide evidence for regional and hemisphere-specific upregulation of NMDA mRNA in the hippocampus after environmental enrichment. The current work also shows that AMPA mRNA of the hippocampus is not per se changed by environmental enrichment in adult animals. Taken together, our results extend the knowledge of the glutamatergic system of specific regions of the hippocampus and its modulation by environmental enrichment and could contribute to the development of strategies aimed at limiting pathological changes associated with glutamatergic dysfunctions. © 2007.
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| 16. |
- 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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| 17. |
- 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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| 18. |
- Bauer, Susanne
(författare)
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Cell type-specific translatome analysis of mouse models of three genetic neurodegenerative diseases
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The burden neurodegenerative diseases place on patients, their loved ones, and the healthcare system is significant, and despite extensive research efforts, there is currently no cure. Since degenerative changes in the brain can begin years before symptoms appear, early intervention is critical. Additionally, neurodegenerative diseases target certain brain regions and neuron types early on. A more comprehensive understanding of the affected cells during the presymptomatic phase is therefore crucial for an effective and targeted intervention. Herein, we isolated, sequenced, and analyzed translatome samples from six neuronal cell types in knock-in mouse models of three monogenic neurodegenerative diseases at a presymptomatic stage: genetic Creutzfeldt-Jakob disease (gCJD), fatal familial insomnia (FFI), and Huntington’s disease (HD). To obtain the translatome samples, we used RiboTag to immunoprecipitate HA-tagged ribosomes with their translating mRNAs from targeted cell types. We analyzed six cell types across two brain regions: cerebral and cerebellar glutamatergic and GABAergic neurons, and cerebral parvalbumin (PV) and somatostatin (SST)-expressing neurons. In the first paper, we focused our analysis on the prion diseases, gCJD (E200K) and FFI (D178N). Here observed a similar response of SST+ neurons, a cell type not previously reported as affected, in both disease models. This was characterized by upregulation of ribosomeassociated genes, and downregulation of cytoskeleton and synapse-associated genes in FFI. Weighted gene co-expression network analysis of SST+ neurons pointed towards the downregulation of mTOR inhibition as a potential mechanism underlying the observed gene expression changes. In the second paper, we analyzed a 129S4-HdhQ200 knock-in mouse model of HD. Histological and behavioral assessment revealed pathological changes in the striatum and cerebellum at 9 months and a later, mild behavioral phenotype. Translatome analysis indicated a surprisingly strong response in reportedly resistant glutamatergic neurons of the cerebellum, marked by upregulation of cell cycle regulators Ccnd1 and chromobox protein genes. In the third paper, we aimed to compare disease-specific responses of PV+ neurons across the three disease models. This analysis revealed a milder response in HD compared to prion disease at comparable disease stages. Functional analysis further indicated PV+ neurons may respond differently in the investigated diseases, showing upregulation of immune response-associated pathways in gCJD, neurodegenerative-disease pathways in FFI, and autophagy in HD. Lastly, the generation of mouse models such as were used in papers I-III requires stable and predictable transgene expression without interfering with the expression of endogenous genes. In the fourth paper, we conducted a pilot study to compare three potential loci, Rpl6, Rpl7, and Eef1a1, as potential safe harbors for transgene integration. Preliminary results indicated that the Rpl6 locus may be best suited for our purposes. Furthermore, this work generated a novel dataset consisting of translatome profiles of six cell types in three neurodegenerative disease models. This provides gene expression data at a previously unavailable level of cellular resolution, especially in prion disease. We believe that this data will serve as a valuable resource for future research and help expand our understanding of the early molecular mechanisms in neurodegenerative disease beyond the scope of this thesis.
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| 19. |
- Bjartmar, Lisa, 1966-, et al.
(författare)
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Long-term treatment with antidepressants, but not environmental stimulation, induces expression of NP2 mRNA in hippocampus and medial habenula
- 2010
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Ingår i: Brain Research. - : Elsevier. - 0006-8993 .- 1872-6240. ; 1328, s. 24-33
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Tidskriftsartikel (refereegranskat)abstract
- Neuronal Pentraxin 2 (NP2, Narp), known to mediate clustering of glutamatergic AMPA receptors at synapses, is involved in activity-dependent synaptogenesis and synaptic plasticity. In experimental settings, antidepressant treatment as well as a stimulating environment has a positive influence on cognition and hippocampal plasticity. This study demonstrates that NP2 mRNA is robustly expressed in the hippocampus and the medial habenula (MHb), both regions implicated in cognitive functions. Furthermore, NP2 mRNA expression is enhanced in the hippocampal subregions as well as in the MHb after long-term treatment with antidepressant drugs of various monoaminergic profiles, indicating a common mode of action of different antidepressant drugs. This effect occurs at the time frame where clinical response is normally achieved. In contrast, neither environmental enrichment nor deprivation has any influence on long-term NP2 mRNA expression. These findings support an involvement of NP2 in the pathway of antidepressant induced plasticity, but not EE induced plasticity; that NP2 might constitute a common link for the action of different types of antidepressant drugs and that the MHb could be a putative region for further studies of NP2.
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| 20. |
- Bratengeier, Cornelia, et al.
(författare)
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Mechanical loading intensities affect the release of extracellular vesicles from mouse bone marrow-derived hematopoietic progenitor cells and change their osteoclast-modulating effect
- 2024
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Ingår i: The FASEB Journal. - : WILEY. - 0892-6638 .- 1530-6860. ; 38:1
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Tidskriftsartikel (refereegranskat)abstract
- Low-intensity loading maintains or increases bone mass, whereas lack of mechanical loading and high-intensity loading decreases bone mass, possibly via the release of extracellular vesicles by mechanosensitive bone cells. How different loading intensities alter the biological effect of these vesicles is not fully understood. Dynamic fluid shear stress at low intensity (0.7 +/- 0.3 Pa, 5 Hz) or high intensity (2.9 +/- 0.2 Pa, 1 Hz) was used on mouse hematopoietic progenitor cells for 2 min in the presence or absence of chemical compounds that inhibit release or biogenesis of extracellular vesicles. We used a Receptor activator of nuclear factor kappa-Beta ligand-induced osteoclastogenesis assay to evaluate the biological effect of different fractions of extracellular vesicles obtained through centrifugation of medium from hematopoietic stem cells. Osteoclast formation was reduced by microvesicles (10 000x g) obtained after low-intensity loading and induced by exosomes (100 000x g) obtained after high-intensity loading. These osteoclast-modulating effects could be diminished or eliminated by depletion of extracellular vesicles from the conditioned medium, inhibition of general extracellular vesicle release, inhibition of microvesicle biogenesis (low intensity), inhibition of ESCRT-independent exosome biogenesis (high intensity), as well as by inhibition of dynamin-dependent vesicle uptake in osteoclast progenitor cells. Taken together, the intensity of mechanical loading affects the release of extracellular vesicles and change their osteoclast-modulating effect. The intensity of mechanical loading strongly affects bone remodeling by either formation of bone or resorption of bone. Low-intensity loading on bone cells releases microvesicles that reduce formation of bone-resorbing osteoclasts, while high-intensity loading on bone cells releases exosomes that induce formation of bone-resorbing osteoclasts. The graphical abstract was created with image
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