| 61. |
- Nyström, Sofie, et al.
(författare)
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Evidence for Age-Dependent in Vivo Conformational Rearrangement within A beta Amyloid Deposits
- 2013
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Ingår i: ACS Chemical Biology. - : American Chemical Society. - 1554-8929 .- 1554-8937. ; 8:6, s. 1128-1133
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Tidskriftsartikel (refereegranskat)abstract
- Deposition of aggregated A beta peptide in the brain is one of the major hallmarks of Alzheimers disease. Using a combination of two structurally different, but related, hypersensitive fluorescent amyloid markers, LCOs, reporting on separate ultrastructural elements, we show that conformational rearrangement occurs within A beta plaques of transgenic mouse models as the animals age. This important mechanistic insight should aid the design and evaluation of experiments currently using plaque load as readout.
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| 62. |
- Nyström, Sofie, et al.
(författare)
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Is the prevalent human prion protein 129M/V mutation a living fossil from a Paleolithic panzootic superprion pandemic?
- 2014
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Ingår i: Prion. - : Landes Bioscience. - 1933-6896 .- 1933-690X. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Prion diseases are consistently associated with prion protein (PrPC) misfolding rendering a cascade of auto-catalytic self-perpetuation of misfolded PrP in an afflicted individual. The molecular process is intriguingly similar to all known amyloid diseases both local and systemic. The prion disease is also infectious by the transfer of misfolded PrP from one individual to the next. Transmissibility is surprisingly efficient in prion diseases and given the rapid disease progression following initial symptoms the prionoses stand out from other amyloidoses, which all may be transmissible under certain circumstances. The nature of the infectious prion as well as the genotype of the host is important for transmissibility. For hitherto unexplained reasons the majority of Europeans carry a missense mutation on one or both alleles of the PrP gene (PRNP), and hence express a variant of PrP with a substitution for valine (V) instead of methionine (M) in position 129. In fact the 129M/V variant is very common in all populations except for the Japanese. Sporadic Creutzfeldt-Jakob disease is a disease rarely striking people below the age of 60, where homozygosity especially 129MM is a very strong risk factor. Paradoxically, the 129M/V polymorphism suggestive of heterozygote advantage is one of the most clear cut disease associated traits of the human population, yet prion disease is extraordinarily rare. The genetic basis for how this trait spread with such prevalence within human populations is still target to investigations and deserves attention. This short essay represents a somewhat provocative hypothetical notion of a possible ancient significance of this polymorphism.
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| 63. |
- Nyström, Sofie, et al.
(författare)
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Multiple substitutions of methionine 129 in human prion protein reveal its importance in the amyloid fibrillation pathway
- 2012
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Ingår i: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 287:31, s. 25975-25984
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Tidskriftsartikel (refereegranskat)abstract
- The role of the polymorphism Met or Val in position 129 in the human prion protein is well documented regarding disease susceptibility and clinical manifestations. However, little is known about the molecular background to this phenomenon. We investigated herein the conformational stability, amyloid fibrillation kinetics, and seeding propensity of different 129 mutants, located in β-strand 1 of PrP (Met129 (WT), M129A, M129V, M129L, M129W, M129P, M129E, M129K, and M129C) in HuPrP(90–231). The mutations M129V, M129L, M129K, and M129C did not affect stability (midpoints of thermal denaturation, Tm = 65–66 °C), whereas the mutants M129A and M129E and the largest side chain M129W were destabilized by 3–4 °C. The most destabilizing substitution was M129P, which lowered the Tm by 7.2 °C. All mutants, except for M129C, formed amyloid-like fibrils within hours during fibril formation under near physiological conditions. Fibril-forming mutants showed a sigmoidal kinetic profile and showed shorter lag times during seeding with preformed amyloid fibrils implicating a nucleated polymerization reaction. In the spontaneous reactions, the lag time of fibril formation was rather uniform for the mutants M129A, M129V, and M129L resembling the wild type. When the substituted amino acid had a distinct feature discriminating it from the wild type, such as size (M129W), charge (M129E, M129K), or rotational constraint (M129P), the fibrillation was impeded. M129C did not form ThT/Congo red-positive fibrils, and non-reducing SDS-PAGE of M129C during fibrillation conditions at different time points revealed covalent dimer formation already 15 min after fibrillation reaction initiation. Position 129 appears to be a key site for dictating PrP receptiveness toward recruitment into the amyloid state.
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| 64. |
- Nyström, Sofie, et al.
(författare)
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Propagating Artificial Amyloid Strains of Recombinant Human Prion Protein with Mutations in Position 129
- 2010
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Ingår i: Prion. - Austin, TX, USA : Landes Bioscience. - 1933-6896 .- 1933-690X. ; 4:3, s. 124-124
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The influence of the polymorphism M129V in the human PrPgene is well documented. Most cases of sporadic CJD afflicthomozygous individuals. Differences in codon 129 genotypegive rise to differences in phenotype regarding plaque and clinicalsymptoms. Despite this, little is known about the molecularbackground to this phenomenon.To study this phenomenon in greater detail we employedrecombinant human prion protein. Using several artificial mutationsallowed us to study the influence of different amino acidproperties on the formation of amyloid prion protein. The variantsused were 129A, 129V, 129L, 129M, 129W, 129P, 129E and129K. Three mutants were chosen to vary the hydrophobicity,the tryptophan mutant was chosen due to its bulkiness and theproline for its constraint of the polypeptide backbone. 129E and129K may give information regarding the effect of charge in this position.The protein was expressed in Escherichia coli, purified andsubjected to agitation at 37°C at physiological pH and salt concentration(Almstedt et al. Prion 2009). All mutants formedcongophilic and Thioflavine T positive aggregates within hours.Fibrillar morphology was also confirmed using transmission electronmicroscopy.Seeding the mutant proteins with preformed fibrils of themutant itself or of wild type protein revealed differences in seedingefficiency for the different mutants. By monitoring the fibrilsresulting from the seeded fibrillation reactions using luminescentconjugated polymers, a templating effect was seen. This strainlikebehavior was followed through several generations of fibrils.The fragility of the seeding fibrils was taken under considerationand was analyzed using urea denaturation.Almstedt, Nyström S, Nilsson P, Hammarström P. Prion2009; 3:224-35.
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| 65. |
- Owenius, Rikard, et al.
(författare)
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GroEL-induced topological dislocation of a substrate protein β-sheet core : a solution EPR spin–spin distance study
- 2010
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Ingår i: Journal of chemical biology. - : Springer Science and Business Media LLC. - 1864-6158 .- 1864-6166. ; 3:3, s. 127-39
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Tidskriftsartikel (refereegranskat)abstract
- The Hsp60-type chaperonin GroEL assists in the folding of the enzyme human carbonic anhydrase II (HCA II) and protects it from aggregation. This study was aimed to monitor conformational rearrangement of the substrate protein during the initial GroEL capture (in the absence of ATP) of the thermally unfolded HCA II molten-globule. Single- and double-cysteine mutants were specifically spin-labeled at a topological breakpoint in the β-sheet rich core of HCA II, where the dominating antiparallel β-sheet is broken and β-strands 6 and 7 are parallel. Electron paramagnetic resonance (EPR) was used to monitor the GroEL-induced structural changes in this region of HCA II during thermal denaturation. Both qualitative analysis of the EPR spectra and refined inter-residue distance calculations based on magnetic dipolar interaction show that the spin-labeled positions F147C and K213C are in proximity in the native state of HCA II at 20 °C (as close as ∼8 Å), and that this local structure is virtually intact in the thermally induced molten-globule state that binds to GroEL. In the absence of GroEL, the molten globule of HCA II irreversibly aggregates. In contrast, a substantial increase in spin–spin distance (up to >20 Å) was observed within minutes, upon interaction with GroEL (at 50 and 60 °C), which demonstrates a GroEL-induced conformational change in HCA II. The GroEL binding-induced disentanglement of the substrate protein core at the topological break-point is likely a key event for rearrangement of this potent aggregation initiation site, and hence, this conformational change averts HCA II misfolding.
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| 66. |
- Sjölander, Daniel, et al.
(författare)
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Luminescent conjugated oligothiophenes: A novel dye for amyloid diagnostics
- 2013
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Ingår i: XIIIth International Symposium on Amyloidosis. - : GUARD (Groningen Unit for Amyloidosis Research & Development). - 9789082159301 - 9789082159318 ; , s. 179-182
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Konferensbidrag (refereegranskat)abstract
- The alkaline Congo red staining method has, for almost half a century, been the gold standard of amyloid diagnosis. Unfortunately, the method is both laborious and requires great skill to achieve proper diagnosis. In this study we are presenting an alternative method that is compatible with immunofluorescence typing. We used a novel dye, h-FTAA, designed and synthesized by us. The dye belongs to the novel class of conformation sensitive dyes known as Luminescent conjugated oligothiophenes (LCOs). We examined 37 different cases of systemic amyloidoses from various tissues. It was found that h-FTAA binds to amyloid with higher sensitivity and greater selectivity than Congo red, as was determined by both fluorescence- and light polarization microscopy. Due to the methods ease of use and performance compared to Congo red, it is concluded that h-FTAA is a better first choice for screening of systemic amyloidoses.
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| 67. |
- Sjölander, Daniel
(författare)
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Luminescent molecular recognition of pathognomonic and aging associated protein aggregates
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Various protein inclusions have been recognized to be associated with aging and pathogenic conditions, such as in Alzheimer’s disease, Parkinson’s disease, Type 2 diabetes, and the prionoses Creutzfeldt-Jakob disease, Chronic wasting disease (CWD), and Mad cow disease. The causative transition of protein aggregation is the alteration in the conformation of the protein that renders the protein susceptible towards self-assembly. Variations in the physico-chemical ultrastructure of the protein deposit, i.e. the conformation and the chemical nature of the fibril constituent protein monomers, translate into specific structure-property phenotype, hence clinicopathology. Upon transmission and/or propagation this phenomenon gives rise to specific protein aggregate strains. Today most potential treatments of the protein conformational diseases have been a huge failure, effectively due to late diagnosis and subsequent therapeutic intervention. An imperative for efficient treatment is early detection and accurate identification for proper clinical diagnosis.The purpose of the studies in this thesis was to develop highly sensitive methods for detection and discrimination of age- and disease associated protein deposits both for in vitro and ex vivo utilization.Herein we have shown that, for in vitro usage, Nile red will bind to amyloid-like protein aggregates derived from a plethora of precursor proteins. It was also found that the fluorescence was insensitive to acidic assay conditions in contrast to the standard in vitro dye Thioflavin T (ThT). Further, Nile red was shown to discriminate between conformational isoforms thus enabling conformational typing of amyloid structures.For the development of ex vivo detection methods we employed luminescent conjugated oligothiophenes (LCOs) and utilized the structure-conformation induced optical properties of this class of protein aggregate ligands. The heptameric oligothiophene h-FTAA was successfully used to detect, with high sensitivity, protein deposits from various systemic amyloidoses (ATTR, AA, AL-λ/κ, and the local amyloidosis AIAPP) derived from biopsy specimens. Also aging-associated protein deposits were detected which was found promising for early detection of potentially pathogenic protein inclusions. Further, LCO staining of tissue sections was found compatible with immunolabeling enabling subtyping of involved proteins. Early detection of amyloidosis also requires relatively non-invasive methods, why h-FTAA staining was directed towards fine-needle-aspirated (FNA) abdominal fat tissue smears. Staining of protein deposits and detection with high sensitivity was also found in the fat tissue smears.In addition to the relatively rare prionoses it has lately been shown that Alzheimer’s, Parkinson’s diseases share similar properties as the prion pathologies. Hence the urgent need for ligands that will recognize specific disease specific strain aggregates. Using an established murine model for prion strain propagation we were able to discriminate two different prion strains, murine adapted Sheep Scrapie (mSS) and murine adapted Chronic wasting disease (mCWD) from each other by using multimodal fluorescence microscopy entailing emission/excitation spectral imaging and fluorescent lifetime imaging (FLIM).In conclusion we have shown that the LCOs will recognize protein aggregates with high sensitivity and selectivity. In addition we have shown that the LCOs detect protein aggregates that Congo red failed to recognize thus allowing potentially early diagnosis. Last, we show that the LCOs will recognize and discriminate between different protein aggregate strains which potentially will allow disease specific therapeutic targeting.
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| 68. |
- Theorell, Töres, et al.
(författare)
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Job strain and depressive symptoms in men and women : a prospective study of the working population in Sweden
- 2014
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Ingår i: Journal of Epidemiology and Community Health. - : BMJ Publishing Group. - 0143-005X .- 1470-2738. ; 68:1, s. 78-82
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Several prospective studies have indicated increased risk of developing depressive symptoms in employees who report psychologically demanding and uncontrollable work (job strain). There are diverging findings regarding gender differences in this relationship. The aim was to analyse whether men and women differ with regard to the prospective relationship between adverse psychosocial work environment and depressive symptoms during a 2-year period.METHOD: The Swedish Longitudinal Occupational Survey of Health cohort based on representative recruitment of working men and women in Sweden was used. 2731 men and 3446 women had answered questions regarding work environment and mental health in 2008 and 2010. Psychological demands, decision authority, age and income as well as depressive symptoms in 2008 were used as predictors of depressive symptoms in 2010.RESULTS: Women reported less decision authority at work and their demand level developed more unfavourably than did men's-resulting in increased job strain gap between men and women from 2008 to 2010. The relationship between demand and decision authority (and job strain) on one hand and depressive symptoms on the other hand was not statistically different in men and women.CONCLUSIONS: Overall, women reported higher levels of job strain than men. In Sweden, job strain was as strongly related to depressive symptoms among men as among women.
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| 69. |
- Usmani, Shariq M., et al.
(författare)
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Direct visualization of HIV-enhancing endogenous amyloid fibrils in human semen
- 2014
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Ingår i: Nature Communications. - : Nature Publishing Group: Nature Communications. - 2041-1723. ; 5, s. 3508-
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Tidskriftsartikel (refereegranskat)abstract
- Naturally occurring fragments of the abundant semen proteins prostatic acid phosphatase ( PAP) and semenogelins form amyloid fibrils in vitro. These fibrils boost HIV infection and may play a key role in the spread of the AIDS pandemic. However, the presence of amyloid fibrils in semen remained to be demonstrated. Here, we use state of the art confocal and electron microscopy techniques for direct imaging of amyloid fibrils in human ejaculates. We detect amyloid aggregates in all semen samples and find that they partially consist of PAP fragments, interact with HIV particles and increase viral infectivity. Our results establish semen as a body fluid that naturally contains amyloid fibrils that are exploited by HIV to promote its sexual transmission.
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| 70. |
- Waenerlund, Anna-Karin, et al.
(författare)
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History of labour market attachment as a determinant of health status: a 12-year follow-up of the Northern Swedish Cohort
- 2014
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Ingår i: BMJ Open. - : BMJ. - 2044-6055. ; 4:2, s. e004053-
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Tidskriftsartikel (refereegranskat)abstract
- Objective The present study aims at using trajectory analysis to measure labour market attachment (LMA) over 12years and at examining whether labour market tracks relate to perceived health status.Design Data were retrieved from a 26-year prospective cohort study, the Northern Swedish Cohort.Setting and participants All ninth grade students (n=1083) within the municipality of Lulea in northern Sweden were included in the baseline investigation in 1981. The vast majority (94%) of the original cohort participated at the fourth follow-up. In this study, 969 participants were included.Measures Perceived health status (psychological distress and non-optimal self-rated health) at age 42 and the data obtained from questionnaires.Results We have identified four tracks in relation to LMA across the 12-year period: permanent', high level', strengthening' and poor level' of attachment. LMA history relates to psychological distress. High level (OR 1.55 (95% CI 1.06 to 2.27)), strengthening (OR 1.95 (95% CI 1.29 to 2.93)) and poor attachment (OR 3.14 (95% CI 2.10 to 4.70) involve higher OR for psychological distress compared with permanent attachment. The overall p value remained significant in the final model (p=0.001). Analyses regarding non-optimal self-rated health displayed a similar pattern but this was not significant in the final model.Conclusions Our results suggest that health status in mid-life, particularly psychological distress, is related to patterns of LMA history, to a large part independently of other social risk factors and previous health. Consideration of heterogeneity and time in LMA might be important when analysing associations with perceived health.
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