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  • Blackwell Science Ltd.  (2)
  • Blackwell Publishing Ltd  (1)
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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract : The neurodegeneration seen in spongiform encephalopathies is believed to be mediated by protease-resistant forms of the prion protein (PrP). A peptide encompassing residues 106-126 of human PrP has been shown to be neurotoxic in vitro. The neurotoxicity of PrP 106-126 appears to be dependent upon its adoption of an aggregated fibril structure. To examine the role of the hydrophobic core, AGAAAAGA, on PrP106-126 toxicity, we performed structure-activity analyses by substituting two or more hydrophobic residues for the hydrophilic serine residue to decrease its hydrophobicity. A peptide with a deleted alanine was also synthesized. We found all the peptides except the deletion mutant were no longer toxic on mouse cerebellar neuronal cultures. Circular dichroism analysis showed that the nontoxic PrP peptides had a marked decrease in β-sheet structure. In addition, the mutants had alterations in aggregability as measured by turbidity, Congo red binding, and fibril staining using electron microscopy. These data show that the hydrophobic core sequence is important for PrP106-126 toxicity probably by influencing its assembly into a neurotoxic structure. The hydrophobic sequence may similarly affect aggregation and toxicity observed in prion diseases.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: To study amyloid β-protein (Aβ) production and aggregation in vivo, we created two transgenic (Tg) mouse lines expressing the C-terminal 100 amino acids of human amyloid precursor protein (APP): Tg C100.V717F and Tg C100.WT. Western blot analysis showed that human APP-C100 and Aβ were produced in brain and some peripheral tissues and Aβ was produced in serum. Using antibodies specific for the Aβ C terminus we found that Tg C100.V717F produced a 1.6-fold increase in Aβ42/Aβ40 compared with Tg C100.WT. Approximately 30% of total brain Aβ (∼122 ng/g of wet tissue) was water-soluble. The remaining 70% of Aβ partitioned into the particulate fraction and was completely sodium dodecyl sulfate-soluble. In contrast, human Alzheimer's disease brain has predominantly sodium dodecyl sulfate-insoluble Aβ. Immunohistochemistry with an Aβ(5-8) antibody showed that Aβ or Aβ-containing fragments accumulated intracellularly in the hippocampus of aged Tg C100.V717F mice. The soluble Aβ levels in Tg brain are similar to those in normal human brain, and this may explain the lack of microscopic amyloid deposits in the Tg mice. However, this mouse model provides a system to study the intracellular processing and accumulation of Aβ or Aβ-containing fragments and to screen for compounds directed at the γ-secretase activity.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 72 (1999), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Perturbations to glutathione (GSH) metabolism may play an important role in neurodegenerative disorders such as Alzheimer's, Parkinson's, and prion diseases. A primary function of GSH is to prevent the toxic interaction between free radicals and reactive transition metals such as copper (Cu). Due to the potential role of Cu in neurodegeneration, we examined the effect of GSH depletion on Cu toxicity in murine primary neuronal cultures. Depletion of cellular GSH with L-buthionine-[S,R]-sulfoximine resulted in a dramatic potentiation of Cu toxicity in neurons without effect on iron (Fe) toxicity. Similarly, inhibition of glutathione reductase (GR) activity with 1,3-bis(2-chloroethyl)-1-nitrosurea also increased Cu toxicity in neurons. To determine if the Alzheimer's amyloid-β (Aβ) peptide can affect neuronal resistance to transition metal toxicity, we exposed cultures to nontoxic concentrations of Aβ25-35 in the presence or absence of Cu or Fe. Aβ25-35 pretreatment was found to deplete neuronal GSH and increase GR activity, confirming the ability of Aβ to perturb neuronal GSH homeostasis. Aβ25-35 pretreatment potently increased Cu toxicity but had no effect on Fe toxicity. These studies demonstrate an important role for neuronal GSH homeostasis in selective protection against Cu toxicity, a finding with widespread implications for neurodegenerative disorders.
    Type of Medium: Electronic Resource
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