| 1. |
- Beretta, Chiara, et al.
(author)
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Amyloid-β deposits in human astrocytes contain truncated and highly resistant proteoforms
- 2024
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In: Molecular and Cellular Neuroscience. - : Elsevier. - 1044-7431 .- 1095-9327. ; 128
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Journal article (peer-reviewed)abstract
- Alzheimer's disease (AD) is a neurodegenerative disorder that develops over decades. Glial cells, including astrocytes are tightly connected to the AD pathogenesis, but their impact on disease progression is still unclear. Our previous data show that astrocytes take up large amounts of aggregated amyloid-beta (Aβ) but are unable to successfully degrade the material, which is instead stored intracellularly. The aim of the present study was to analyze the astrocytic Aβ deposits composition in detail in order to understand their role in AD propagation. For this purpose, human induced pluripotent cell (hiPSC)-derived astrocytes were exposed to sonicated Aβ42 fibrils and magnetic beads. Live cell imaging and immunocytochemistry confirmed that the ingested Aβ aggregates and beads were transported to the same lysosomal compartments in the perinuclear region, which allowed us to successfully isolate the Aβ deposits from the astrocytes. Using a battery of experimental techniques, including mass spectrometry, western blot, ELISA and electron microscopy we demonstrate that human astrocytes truncate and pack the Aβ aggregates in a way that makes them highly resistant. Moreover, the astrocytes release specifically truncated forms of Aβ via different routes and thereby expose neighboring cells to pathogenic proteins. Taken together, our study establishes a role for astrocytes in mediating Aβ pathology, which could be of relevance for identifying novel treatment targets for AD.
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| 2. |
- Delsing, Louise, et al.
(author)
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Models of the blood-brain barrier using iPSC-derived cells
- 2020
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In: Molecular and Cellular Neuroscience. - : Elsevier BV. - 1044-7431 .- 1095-9327. ; 107
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Journal article (peer-reviewed)abstract
- The blood-brain barrier (BBB) constitutes the interface between the blood and the brain tissue. Its primary function is to maintain the tightly controlled microenvironment of the brain. Models of the BBB are useful for studying the development and maintenance of the BBB as well as diseases affecting it. Furthermore, BBB models are important tools in drug development and support the evaluation of the brain-penetrating properties of novel drug molecules. Currently used in vitro models of the BBB include immortalized brain endothelial cell lines and primary brain endothelial cells of human and animal origin. Unfortunately, many cell lines and primary cells do not recreate physiological restriction of transport in vitro. Human-induced pluripotent stem cell (iPSC)-derived brain endothelial cells have proven a promising alternative source of brain endothelial-like cells that replicate tight cell layers with low paracellular permeability. Given the possibility to generate large amounts of human iPSC-derived brain endothelial cells they are a feasible alternative when modelling the BBB in vitro. iPSC-derived brain endothelial cells form tight cell layers in vitro and their barrier properties can be enhanced through co-culture with other cell types of the BBB. Currently, many different models of the BBB using iPSC-derived cells are under evaluation to study BBB formation, maintenance, disruption, drug transport and diseases affecting the BBB. This review summarizes important functions of the BBB and current efforts to create iPSC-derived BBB models in both static and dynamic conditions. In addition, it highlights key model requirements and remaining challenges for human iPSC-derived BBB models in vitro.
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| 3. |
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| 4. |
- Johannesson, Malin, et al.
(author)
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Elevated soluble amyloid beta protofibrils in Down syndrome and Alzheimer's disease
- 2021
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In: Molecular and Cellular Neuroscience. - : Elsevier. - 1044-7431 .- 1095-9327. ; 114
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Journal article (peer-reviewed)abstract
- Down syndrome (DS) is caused by trisomy of chromosome 21, which leads to a propensity to develop amyloid beta (A beta) brain pathology in early adulthood followed later by cognitive and behavioral deterioration. Characterization of the A beta pathology is important to better understand the clinical deterioration of DS individuals and to identify interventive strategies. Brain samples from people with DS and Alzheimer's disease (AD), as well as nondemented controls (NDC), were analyzed with respect to different A beta species. Immunohistochemical staining using antibodies towards A beta was also performed. Elevated levels of soluble A beta protofibrils and insoluble A beta x-40 and A beta x-42 in formic acid brain extracts, and elevated immunohistochemical staining of A beta deposits were demonstrated with the antibody BAN2401 (lecanemab) in DS and AD compared with NDC. These data and the promising data in a large phase 2 CE clinical trial with lecanemab suggest that lecanemab may have the potential to preserve cognitive capacity in DS. Lecanemab is currently in a phase 3 CE clinical trial.
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| 5. |
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| 6. |
- Konstantinidis, Evangelos, 1990-, et al.
(author)
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Long-term effects of amyloid-beta deposits in human iPSC-derived astrocytes
- 2023
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In: Molecular and Cellular Neuroscience. - : Elsevier. - 1044-7431 .- 1095-9327. ; 125
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Journal article (peer-reviewed)abstract
- Growing evidence indicates that astrocytes are tightly connected to Alzheimer's disease (AD) pathogenesis. However, the way in which astrocytes participate in AD initiation and progression remains to be clarified. Our previous data show that astrocytes engulf large amounts of aggregated amyloid-beta (A beta) but are unable to successfully degrade the material. In this study, we aimed to evaluate how intracellular A beta-accumulation affects the astrocytes over time. For this purpose, human induced pluripotent cell (hiPSC)-derived astrocytes were exposed to sonicated A beta-fibrils and then cultured further for one week or ten weeks in A beta-free medium. Cells from both time points were analyzed for lysosomal proteins and astrocyte reactivity markers and the media were screened for inflammatory cytokines. In addition, the overall health of cytoplasmic organelles was investigated by immunocytochemistry and electron microscopy. Our data demonstrate that long-term astrocytes retained frequent A beta-inclusions that were enclosed within LAMP1-positive organelles and sustained markers associated with reactivity. Furthermore, A beta-accumulation resulted in endoplasmic reticulum and mitochondrial swelling, increased secretion of the cytokine CCL2/MCP-1 and formation of pathological lipid structures. Taken together, our results provide valuable information of how intracellular A beta-deposits affect astrocytes, and thereby contribute to the understanding of the role of astrocytes in AD progression.
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| 7. |
- Niss, Frida, et al.
(author)
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Polyglutamine expanded Ataxin-7 induces DNA damage and alters FUS localization and function
- 2021
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In: Molecular and Cellular Neuroscience. - : Elsevier BV. - 1044-7431 .- 1095-9327. ; 110
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Journal article (peer-reviewed)abstract
- Polyglutamine (polyQ) diseases, such as Spinocerebellar ataxia type 7 (SCA7), are caused by expansions of polyQ repeats in disease specific proteins. The sequestration of vital proteins into aggregates formed by polyQ proteins is believed to be a common pathological mechanism in these disorders. The RNA-binding protein FUS has been observed in polyQ aggregates, though if disruption of this protein plays a role in the neuronal dysfunction in SCA7 or other polyQ diseases remains unclear. We therefore analysed FUS localisation and function in a stable inducible PC12 cell model expressing the SCA7 polyQ protein ATXN7. We found that there was a high degree of FUS sequestration, which was associated with a more cytoplasmic FUS localisation, as well as a decreased expression of FUS regulated mRNAs. In contrast, the role of FUS in the formation of gamma H2AX positive DNA damage foci was unaffected. In fact, a statistical increase in the number of gamma H2AX foci, as well as an increased trend of single and double strand DNA breaks, detected by comet assay, could be observed in mutant ATXN7 cells. These results were further corroborated by a clear trend towards increased DNA damage in SCA7 patient fibroblasts. Our findings suggest that both alterations in the RNA regulatory functions of FUS, and increased DNA damage, may contribute to the pathology of SCA7.
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| 8. |
- Revol, Rebecca, et al.
(author)
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Alpha-secretase dependent nuclear localization of the amyloid-β precursor protein-binding protein Fe65 promotes DNA repair
- 2023
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In: Molecular and Cellular Neuroscience. - 1044-7431 .- 1095-9327. ; 127
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Journal article (peer-reviewed)abstract
- Fe65 is a brain enriched adaptor protein involved in various cellular processes, including actin cytoskeleton regulation, DNA repair and transcription. A well-studied interacting partner of Fe65 is the transmembrane amyloid-beta precursor protein (APP), which can undergo regulated intramembrane proteolysis (RIP). Following beta and gamma-secretase-mediated RIP, the released APP intracellular domain (AICD) together with Fe65 can translocate to the nucleus and regulate transcription. In this study, we investigated if Fe65 nuclear localization can also be regulated by different alpha-secretases, also known to participate in RIP of APP and other transmembrane proteins. We found that in both Phorbol 12-myristate 13-acetate and all-trans retinoic acid differentiated neuroblastoma cells a strong negative impact on Fe65 nuclear localization, equal to the effect observed upon gamma-secretase inhibition, could be detected following inhibition of all three (ADAM9, ADAM10 and ADAM17) alpha-secretases. Moreover, using the comet assay and analysis of Fe65 dependent DNA repair associated posttranslational modifications of histones, we could show that inhibition of alpha-secretase-mediated Fe65 nuclear translocation resulted in impaired capacity of the cells to repair DNA damage. Taken together this suggests that alpha-secretase processing of APP and/or other Fe65 interacting transmembrane proteins play an important role in regulating Fe65 nuclear translocation and DNA repair.
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| 9. |
- Rizoska, Biljana, et al.
(author)
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Disease modifying effects of the amyloid-beta protofibril-selective antibody mAb158 in aged Tg2576 transgenic mice
- 2024
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In: Molecular and Cellular Neuroscience. - : Elsevier. - 1044-7431 .- 1095-9327. ; 130
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Journal article (peer-reviewed)abstract
- Amyloid beta (Aβ) peptides, which aggregate to form neocortical plaques in Alzheimer's disease, exist in states that range from soluble monomers and oligomers/protofibrils to insoluble fibrillar amyloid. The present study evaluated the effects of mAb158, a mouse monoclonal antibody version of lecanemab that preferentially binds to soluble Aβ protofibrils, in aged transgenic mice (Tg2576) with Aβ pathology. Female Tg2576 mice (12 months old) received weekly intraperitoneal mAb158 (35 mg/kg) or vehicle for 4 weeks or for 18 weeks, with or without a subsequent 12-week off-treatment period. Aβ protofibril levels were significantly lower in mAb158-treated animals at both 4 and 18 weeks, while longer treatment duration (18 weeks) was required to observe significantly lower Aβ42 levels in insoluble brain fractions and lower Aβ plaque load. Following the off-treatment period, comparison of the vehicle- and mAb158-treated mice demonstrated that the Aβ protofibril levels, insoluble Aβ42 levels and Aβ plaque load remained significantly lower in mAb158-treated animals, as compared with age-matched controls. However, there was a significant increase of brain accumulation of both the Aβ protofibril levels, insoluble Aβ42 levels and Aβ plaque load after treatment cessation. Thus, repeated mAb158 treatment of aged Tg2576 mice first reduced Aβ protofibril levels within 4 weeks of treatment, which then was followed by a reduction of amyloid plaque pathology within 18 weeks of treatment. These effects were maintained 12 weeks after the final dose, indicating that mAb158 had a disease-modifying effect on the Aβ pathology in this mouse model. In addition, brain accumulation of both Aβ protofibril levels and amyloid pathology progressed after discontinuation of the treatment which supports the importance of continued treatment with mAb158 to maintain the effects on Aβ pathology.
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| 10. |
- Shimozawa, Makoto, et al.
(author)
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Identification of cytoskeletal proteins as binding partners of Bri2 BRICHOS domain
- 2023
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In: Molecular and Cellular Neuroscience. - : Elsevier. - 1044-7431 .- 1095-9327. ; 125
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Journal article (peer-reviewed)abstract
- Proteins must fold into three-dimensional structures to execute their biological functions. Therefore, maintenance of protein homeostasis, proteostasis, including prevention of protein misfolding is essential for cellular activity and health. Molecular chaperones are key actors in proteostasis. BRICHOS domain is an intramolecular chaperone that also interferes with several aggregation-prone proteins including amyloid beta (A beta), involved in Alzheimer's disease (AD). To extend the knowledge about Bri2 BRICHOS interactome we here used recombinant human (rh) Bri2 BRICHOS-mCherry fusion protein to probe for potential binding partners. Firstly, exogenously added Bri2 BRICHOS-mCherry was used to stain brain sections of wildtype and amyloid precursor protein (App) knock-in AD mice exhibiting robust A beta pathology. Unexpectedly, we found that rh Bri2 BRICHOS-mCherry stained the cytoplasm of neurons which are devoid of A beta deposits. To identify these intraneuronal proteins that bind to the rh Bri2 BRICHOS domain, we performed co-immunoprecipitation (co-IP) of mouse brain hippocampi homogenates using the Bri2 BRICHOS-mCherry probe and analyzed co-IP proteins by LC-MS/MS. This identified several cytoskeletal proteins including spectrin alpha and beta chain, drebrin, tubulin beta 3, and beta-actin as binding partners. The interactions were confirmed by a second round of pulldown experiments using rh Bri2 BRICHOS linked to magnetic beads. The interaction of rh Bri2 BRICHOS and tubulin beta 3 was further investigated by staining both mouse brain sections and SH-SY5Y neuroblastoma cells with rh Bri2 BRICHOSmCherry and tubulin beta 3 immunostaining, which revealed partial co-localization. These data suggest a possible interplay of extracellular chaperone Bri2 BRICHOS domain in the intracellular space including the cytoskeleton.
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