| 1. |
- Adolfsson, Dan E., 1989-, et al.
(författare)
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Intramolecular Povarov Reactions for the Synthesis of Chromenopyridine fused 2-Pyridone Polyheterocycles Binding to α-Synuclein and Amyloid-β fibrils
- 2020
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 85:21, s. 14174-14189
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A BF3×OEt2 catalyzed intramolecular Povarov reaction was used to synthesize a library of 15 chromenopyridine fused thiazolino-2-pyridone peptidomimetics. The reaction works with a range of O-alkylated salicylaldehydes and amino functionalized thiazolino-2-pyridones, to generate polyheterocycles with diverse substitution. The synthesized compounds were screened for their ability to bind α-synuclein and amyloid β fibrils in vitro. Analogs substituted with a nitro group bind to mature amyloid fibrils, and the activity moreover depends on the positioning of this functional group.
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| 2. |
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| 3. |
- Bharate, Jaideep B., et al.
(författare)
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K2S2O8-mediated coupling of 6-amino-7-aminomethyl-thiazolino-pyridones with aldehydes to construct amyloid affecting pyrimidine-fused thiazolino-2-pyridones
- 2021
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Ingår i: Organic and biomolecular chemistry. - : The Royal Society of Chemistry. - 1477-0520 .- 1477-0539. ; 19:44, s. 9758-9772
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Tidskriftsartikel (refereegranskat)abstract
- We herein present the synthesis of diversely functionalized pyrimidine fused thiazolino-2-pyridones via K2S2O8-mediated oxidative coupling of 6-amino-7-(aminomethyl)-thiazolino-2-pyridones with aldehydes. The developed protocol is mild, has wide substrate scope, and does not require transition metal catalyst or base. Some of the synthesized compounds have an ability to inhibit the formation of Amyloid-β fibrils associated with Alzheimer's disease, while others bind to mature amyloid-β and α-synuclein fibrils.
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| 4. |
- Brännström, Kristoffer, et al.
(författare)
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A Generic Method for Design of Oligomer-Specific Antibodies
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:3, s. e90857-
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Tidskriftsartikel (refereegranskat)abstract
- Antibodies that preferentially and specifically target pathological oligomeric protein and peptide assemblies, as opposed to their monomeric and amyloid counterparts, provide therapeutic and diagnostic opportunities for protein misfolding diseases. Unfortunately, the molecular properties associated with oligomer-specific antibodies are not well understood, and this limits targeted design and development. We present here a generic method that enables the design and optimisation of oligomer-specific antibodies. The method takes a two-step approach where discrimination between oligomers and fibrils is first accomplished through identification of cryptic epitopes exclusively buried within the structure of the fibrillar form. The second step discriminates between monomers and oligomers based on differences in avidity. We show here that a simple divalent mode of interaction, as within e. g. the IgG isotype, can increase the binding strength of the antibody up to 1500 times compared to its monovalent counterpart. We expose how the ability to bind oligomers is affected by the monovalent affinity and the turnover rate of the binding and, importantly, also how oligomer specificity is only valid within a specific concentration range. We provide an example of the method by creating and characterising a spectrum of different monoclonal antibodies against both the A beta peptide and alpha-synuclein that are associated with Alzheimer's and Parkinson's diseases, respectively. The approach is however generic, does not require identification of oligomer-specific architectures, and is, in essence, applicable to all polypeptides that form oligomeric and fibrillar assemblies.
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| 5. |
- Brännström, Kristoffer, et al.
(författare)
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Scanning electron microscopy as a tool for evaluating morphology of amyloid structures formed on surface plasmon resonance chips
- 2018
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Ingår i: Data in Brief. - : Elsevier. - 2352-3409. ; 19, s. 1166-1170
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the use of Scanning Electron microscopy (SEM) in combination with Surface Plasmon Resonance (SPR) to probe and verify the formation of amyloid and its morphology on an SPR chip. SPR is a technique that measures changes in the immobilized weight on the chip surface and is frequently used to probe the formation and biophysical properties of amyloid structures. In this context it is of interest to also monitor the morphology of the formed structures. The SPR chip surface is made of a layer of gold, which represent a suitable material for direct analysis of the surface using SEM. The standard SPR chip used here (CM5-chip, GE Healthcare, Uppsala, Sweden) can easily be disassembled and directly analyzed by SEM. In order to verify the formation of amyloid fibrils in our experimental conditions we analyzed also in-solution produced structures by using Transmission Electron Microscopy (TEM). For further details and experimental findings, please refer to the article published in Journal of Molecular Biology, (Brännström K. et al., 2018) [1].
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| 6. |
- Brännström, Kristoffer, et al.
(författare)
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The Properties of Amyloid-β Fibrils Are Determined by their Path of Formation
- 2018
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Ingår i: Journal of Molecular Biology. - : Elsevier. - 0022-2836 .- 1089-8638. ; 430:13, s. 1940-1949
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Tidskriftsartikel (refereegranskat)abstract
- Fibril formation of the amyloid-β peptide (Aβ) follows a nucleation-dependent polymerization process and is associated with Alzheimer's disease. Several different lengths of Aβ are observed in vivo, but Aβ1-40 and Aβ1-42 are the dominant forms. The fibril architectures of Aβ1-40 and Aβ1-42 differ and Aβ1-42 assemblies are generally considered more pathogenic. We show here that monomeric Aβ1-42 can be cross-templated and incorporated into the ends of Aβ1-40 fibrils, while incorporation of Aβ1-40 monomers into Aβ1-42 fibrils is very poor. We also show that via cross-templating incorporated Aβ monomers acquire the properties of the parental fibrils. The suppressed ability of Aβ1-40 to incorporate into the ends of Aβ1-42 fibrils and the capacity of Aβ1-42 monomers to adopt the properties of Aβ1-40 fibrils may thus represent two mechanisms reducing the total load of fibrils having the intrinsic, and possibly pathogenic, features of Aβ1-42 fibrils in vivo. We also show that the transfer of fibrillar properties is restricted to fibril-end templating and does not apply to cross-nucleation via the recently described path of surface-catalyzed secondary nucleation, which instead generates similar structures to those acquired via de novo primary nucleation in the absence of catalyzing seeds. Taken together these results uncover an intrinsic barrier that prevents Aβ1-40 from adopting the fibrillar properties of Aβ1-42 and exposes that the transfer of properties between amyloid-β fibrils are determined by their path of formation.
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| 7. |
- Drakenberg, Katarina, et al.
(författare)
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Mu opioid receptor A118G polymorphism in association with striatal opioid neuropeptide gene expression in heroin abusers
- 2006
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 103:20, s. 7883-7888
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Tidskriftsartikel (refereegranskat)abstract
- μ Opioid receptors are critical for heroin dependence, and A118G SNP of the μ opioid receptor gene (OPRM1) has been linked with heroin abuse. In our population of European Caucasians (n = 118), ≈90% of 118G allelic carriers were heroin users. Postmortem brain analyses showed the OPRM1 genotype associated with transcription, translation, and processing of the human striatal opioid neuropeptide system. Whereas down-regulation of preproenkephalin and preprodynorphin genes was evident in all heroin users, the effects were exaggerated in 118G subjects and were most prominent for preproenkephalin in the nucleus accumbens shell. Reduced opioid neuropeptide transcription was accompanied by increased dynorphin and enkephalin peptide concentrations exclusively in 118G heroin subjects, suggesting that the peptide processing is associated with the OPRM1 genotype. Abnormal gene expression related to peptide convertase and ubiquitin/proteosome regulation was also evident in heroin users. Taken together, alterations in opioid neuropeptide systems might underlie enhanced opiate abuse vulnerability apparent in 118G individuals.
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| 8. |
- Gharibyan, Anna, 1974-
(författare)
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Amyloids here, amyloids there…What’s wrong with them?
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Amyloid formation is inherent property of proteins which under certain circumstances can become a pathologic feature of a group of diseases called amyloidosis. There are about 30 known human amyloidosis and more than 27 identified proteins involved in these pathologies. Besides these proteins, there are a growing number of proteins non-related to diseases shown to form amyloid-like structures in vitro, which make them excellent tools for studying amyloid formation mechanisms, physicochemical properties of different amyloid species and the nature of their influence on tissues and cells. It is important to understand the mechanisms by which amyloids interact with different types of cells, as the leading hypothesis in amyloid field suggests that amyloids and especially their intermediate states are the main harmful, toxic species causing tissue and cell degeneration. Using de-novo synthesized protein albebetin as a model of amyloidogenic protein, we demonstrated that it forms amyloid-like structures under physiological conditions (pH 7 and 37°C). During aggregation it forms 2 different types of intermediate oligomers — cross-b sheet containing and lacking β-sheet oligomers. Only the former induces cellular toxicity in a dose dependent manner. Further aggregation leads to the formation of fully mature amyloid-like fibrils, which are not toxic to the cells during studied period of incubation. Another model protein in our studies was hen egg white lysozyme, which readily forms amyloid under denaturing conditions (pH 2,2 and 57°C). In contrast to albebetin and many other proteins reported in the literature, we showed that both oligomers and mature fibrils from hen lysozyme affect cell viability. Targeting different mechanisms involved in cellular death, we revealed that oligomers induce slow and apoptotic-like cell death, while mature fibrils cause rapid and mainly necrotic-like cellular death. One of the important aspects of amyloid studies is to develop measures for inhibiting or re-directing the process of amyloid formation to abolish or neutralize toxic amyloid species. Among the agents having inhibitory or modulatory properties small, phenol containing molecules are widely studied. We investigated the effect of the novel nootropic drug noopept on amyloid formation process of α-synuclein, as this drug is a small dipeptide containing a phenol ring. We showed that noopept is able to modulate amyloid formation process by accelerating it to rapid conversion of α-synuclein into fully mature fibrils, thus eliminating the stage of population of toxic oligomeric species. Using wide range of cytotoxicity assays we showed that amyloid-like fibrils formed in the presence of noopept have no cytotoxic properties. As this medicine is becoming popular and freely available in some countries as a cognitive enhancer, neuroprotective and nootropic agent, further detailed investigations and clinical trials are needed to assess the safety and benefit of noopept in particular for the patients with amyloid related neurodegenerative diseases (such as Parkinson’s or Alzheimer’s diseases). While in vitro models are useful to study some specific aspects of protein aggregation, their properties and effects on cell viability, it is very difficult or practically impossible to create an absolutely accurate model of in vivo situation. Therefore, it is important to turn to in vivo/ex vivo studies to relate the knowledge accumulated from in vitro studies to the real situation in the body. Using human brain hippocampus tissues from individuals with Alzheimer’s disease, we found that besides well-known and widely accepted main pathological hallmark — Ab peptide deposition, S100A9 and S100A8 pro-inflammatory calcium-binding proteins are also localized in the plaques and in surrounding tissues and very explicitly co-localized with Ab. Moreover, we found the presence of S100A9 within the neuronal cells, which has not been reported before and can be an important clue for understanding the mechanisms of neurodegeneration. In vitro cytotoxicity studies showed that S100A9 protein can efficiently induce cytotoxicity when added exogenously to the neuronal cell culture. These findings suggest that S100A8 and S100A9 proteins play an important role in Alzheimer’s pathology, and potentially can be candidates for the amyloid plaque formation and neurodegeneration. Whether they are associated with inflammatory processes underlying the early onset of disease or produced and accumulated as a consequence of A-beta induced pathology remain to be clarified. We found that Alzheimer’s disease is not the only pathology associated with A-beta and S100A9 deposition in a form of plaques. Immunohistochemical studies of an aortic valve surgically removed from a patient with aortic stenosis revealed plaque-like structures positively stained with A-beta and S100A9 proteins. These areas are also positively stained with fibril-specific antibodies as well as with Congo red, which also shows very distinct apple-green birefringence under the polarized light. Besides, there is intracellular localization and co-localization of both proteins in interstitial cells throughout the whole fibrous tissue of the valve. The presented case report is the first finding suggesting inflammatory protein S100A9 as well as A-beta peptide as potential candidates for amyloid formation in aortic stenosis valves. We suggest that there is a specific interaction between A-beta and S100A9 during amyloid formation, which can be involved in amyloid-associated pathology in various tissues and organs in the body, which can potentially be caused by inflammatory processes, particularly by its chronic, long lasting forms.
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| 9. |
- Gharibyan, Anna, et al.
(författare)
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Apolipoprotein E Interferes with IAPP Aggregation and Protects Pericytes from IAPP-Induced Toxicity
- 2020
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Ingår i: Biomolecules. - : MDPI. - 2218-273X. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Apolipoprotein E (ApoE) has become a primary focus of research after the discovery of its strong linkage to Alzheimer’s disease (AD), where the ApoE4 variant is the highest genetic risk factor for this disease. ApoE is commonly found in amyloid deposits of different origins, and its interaction with amyloid-β peptide (Aβ), the hallmark of AD, is well known. However, studies on the interaction of ApoEs with other amyloid-forming proteins are limited. Islet amyloid polypeptide (IAPP) is an amyloid-forming peptide linked to the development of type-2 diabetes and has also been shown to be involved in AD pathology and vascular dementia. Here we studied the impact of ApoE on IAPP aggregation and IAPP-induced toxicity on blood vessel pericytes. Using both in vitro and cell-based assays, we show that ApoE efficiently inhibits the amyloid formation of IAPP at highly substoichiometric ratios and that it interferes with both nucleation and elongation. We also show that ApoE protects the pericytes against IAPP-induced toxicity, however, the ApoE4 variant displays the weakest protective potential. Taken together, our results suggest that ApoE has a generic amyloid-interfering property and can be protective against amyloid-induced cytotoxicity, but there is a loss of function for the ApoE4 variant.
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| 10. |
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