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Sökning: L773:1933 6896

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1.
  • Hammarström, Per, et al. (författare)
  • Porcine prion protein amyloid
  • 2015
  • Ingår i: Prion. - : Taylor andamp; Francis: STM, Behavioural Science and Public Health Titles. - 1933-6896 .- 1933-690X. ; 9:4, s. 266-277
  • Tidskriftsartikel (refereegranskat)abstract
    • Mammalian prions are composed of misfolded aggregated prion protein (PrP) with amyloid-like features. Prions are zoonotic disease agents that infect a wide variety of mammalian species including humans. Mammals and by-products thereof which are frequently encountered in daily life are most important for human health. It is established that bovine prions (BSE) can infect humans while there is no such evidence for any other prion susceptible species in the human food chain (sheep, goat, elk, deer) and largely prion resistant species (pig) or susceptible and resistant pets (cat and dogs, respectively). PrPs from these species have been characterized using biochemistry, biophysics and neurobiology. Recently we studied PrPs from several mammals in vitro and found evidence for generic amyloidogenicity as well as cross-seeding fibril formation activity of all PrPs on the human PrP sequence regardless if the original species was resistant or susceptible to prion disease. Porcine PrP amyloidogenicity was among the studied. Experimentally inoculated pigs as well as transgenic mouse lines overexpressing porcine PrP have, in the past, been used to investigate the possibility of prion transmission in pigs. The pig is a species with extraordinarily wide use within human daily life with over a billion pigs harvested for human consumption each year. Here we discuss the possibility that the largely prion disease resistant pig can be a clinically silent carrier of replicating prions.
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2.
  • Hammond, Maria, et al. (författare)
  • Sensitive detection of aggregated prion protein via proximity ligation
  • 2014
  • Ingår i: Prion. - : Taylor & Francis: STM, Behavioural Science and Public Health Titles. - 1933-6896 .- 1933-690X. ; 8:3, s. 261-265
  • Tidskriftsartikel (refereegranskat)abstract
    • The DNA assisted solid-phase proximity ligation assay (SP-PLA) provides a unique opportunity to specifically detect prion protein (PrP) aggregates by investigating the collocation of three or more copies of the specific protein. We have developed a SP-PLA that can detect PrP aggregates in brain homogenates from infected hamsters even after a 10(7)-fold dilution. In contrast, brain homogenate from uninfected animals did not generate a detectable signal at hundred-fold higher concentration. Using either of the two monoclonal anti-PrP antibodies 3F4 and 6H4 we successfully detected low concentrations of aggregated PrP. The presented results provide a proof of concept that this method might be an interesting tool in the development of diagnostic approaches of prion diseases.
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4.
  • Magnusson, Karin, et al. (författare)
  • Multimodal fluorescene microscopy of prion strain specific PrP deposits stained by thiophene-bassed amyloid ligands
  • 2014
  • Ingår i: Prion. - : Taylor & Francis. - 1933-6896 .- 1933-690X. ; 8:4, s. 319-329
  • Tidskriftsartikel (refereegranskat)abstract
    • The disease-associated prion protein (PrP) forms aggregates which vary in structural conformation yet share identical primary sequence. These variations in PrP conformation are believed to manifest in prion strains exhibiting distinctly different periods of disease incubation as well as regionally specific aggregate deposition within the brain. The anionic luminescent conjugated polythiophene (LCP), polythiophene acetic acid (PTAA) has previously been used to distinguish PrP deposits associated with distinct mouse adapted strains via distinct fluorescence emission profiles from the dye. Here we employed PTAA and 3 structurally related chemically defined luminescent conjugated oligothiophenes (LCOs) to stain brain tissue sections from mice inoculated with 2 distinct prion strains. Our results showed that in addition to emission spectra, excitation, and fluorescence lifetime imaging microscopy (FLIM) can fruitfully be assessed for optical distinction of PrP deposits associated with distinct prion strains. Our findings support the theory that alterations in LCP/LCO fluorescence are due to distinct conformational restriction of the thiophene backbone upon interaction with PrP aggregates associated with distinct prion strains. We foresee that LCP and LCO staining in combination with multimodal fluorescence microscopy might aid in detecting structural differences among discrete protein aggregates and in linking protein conformational features with disease phenotypes for a variety of neurodegenerative proteinopathies.
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5.
  • Nyström, Sofie, et al. (författare)
  • Is the prevalent human prion protein 129M/V mutation a living fossil from a Paleolithic panzootic superprion pandemic?
  • 2014
  • Ingår i: Prion. - : Landes Bioscience. - 1933-6896 .- 1933-690X. ; 8:1
  • 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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6.
  • Nyström, Sofie, et al. (författare)
  • Propagating Artificial Amyloid Strains of Recombinant Human Prion Protein with Mutations in Position 129
  • 2010
  • Ingår i: Prion. - Austin, TX, USA : Landes Bioscience. - 1933-6896 .- 1933-690X. ; 4:3, s. 124-124
  • Tidskriftsartikel (övrigt vetenskapligt)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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7.
  • Paucar, Martin, et al. (författare)
  • Genotype-phenotype analysis in inherited prion disease with eight octapeptide repeat insertional mutation.
  • 2013
  • Ingår i: Prion. - 1933-6896 .- 1933-690X. ; 7:6, s. 501-10
  • Tidskriftsartikel (refereegranskat)abstract
    • A minority of inherited prion diseases (IPD) are caused by four to 12 extra octapeptide repeat insertions (OPRI) in the prion protein gene (PRNP). Only four families affected by IPD with 8-OPRI have been reported, one of them was a three-generation Swedish kindred in which four of seven affected subjects had chorea which was initially attributed to Huntington's disease (HD). Following the exclusion of HD, this phenotype was labeled Huntington disease-like 1 (HDL1). Here, we provide an update on the Swedish 8-OPRI family, describe the clinical features of one of its affected members with video-recordings, compare the four 8-OPRI families and study the effect of PRNP polymorphic codon 129 and gender on phenotype. Surprisingly, the Swedish kindred displayed the longest survival of all of the 8-OPRI families with a mean of 15.1 years from onset of symptoms. Subjects with PRNP polymorphic codon 129M in the mutated allele had significantly earlier age of onset, longer survival and earlier age of death than 129V subjects. Homozygous 129MM had earlier age of onset than 129VV. Females had a significantly earlier age of onset and earlier age of death than males. Up to 50% of variability in age of onset was conferred by the combined effect of PRNP polymorphic codon 129 and gender. An inverse correlation between early age of onset and long survival was found for this mutation.
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9.
  • Wik, Lotta, et al. (författare)
  • Separate mechanisms act concurrently to shed and release the prion protein from the cell
  • 2012
  • Ingår i: Prion. - : Taylor & Francis: STM, Behavioural Science and Public Health Titles. - 1933-6896 .- 1933-690X. ; 6
  • Tidskriftsartikel (refereegranskat)abstract
    • The cellular prion protein (PrPC) is attached to the cell membrane via its glycosylphosphatidylinositol (GPI)-anchor and is constitutively shed into the extracellular space. Here, three different mechanisms are presented that concurrently shed PrPC from the cell. The fast alpha-cleavage released a N-terminal fragment (N1) into the medium and the extreme C-terminal cleavage shed soluble full-length (FL-S) PrP and C-terminally cleaved (C1-S) fragments outside the cell. Also, a slow exosomal release of full-length (FL) and C1-fragment (C1) was demonstrated. The three separate mechanisms acting simultaneously, but with different kinetics, have to be taken into consideration when elucidating functional roles of PrPC and also when processing of PrPC is considered as a target for intervention in prion diseases. Further, in this study it was shown that metalloprotease inhibitors affected the extreme C-terminal cleavage and shedding of PrPC. The metalloprotease inhibitors did not influence the alpha-cleavage or the exosomal release. Taken together, these results are important for understanding the different mechanisms acting in parallel in the shedding and cleavage of PrPC.
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