Proc Natl Acad Sci U S A. 2000 Dec 5;97(25):13937-42. Prion infection impairs the cellular response to oxidative stress.
Milhavet O, McMahon HE, Rachidi W, Nishida N, Katamine S, Mange A, Arlotto M, Casanova D, Riondel J, Favier A, Lehmann S.
Institut de Genetique Humaine, Centre National de la Recherche Scientifique U.P.R. 1142, 141, rue de la Cardonille, 34396 Montpellier Cedex 5, France.
The molecular mechanism of neurodegeneration in transmissible spongiform encephalopathies remains uncertain. In this study, it was demonstrated that prion-infected hypothalamic neuronal GT1 cells displayed a higher sensitivity to induced oxidative stress over noninfected cells. In addition, the infected cells presented an increased lipid peroxidation and signs of apoptosis associated with a dramatic reduction in the activities of the glutathione-dependent and superoxide dismutase antioxidant systems. This study indicates for the first time that prion infection results in an alteration of the molecular mechanisms promoting cellular resistance to reactive oxygen species. This finding is vital for future therapeutic approaches in transmissible spongiform encephalopathies and the understanding of the function of the prion protein.
PMID:_11095725
Biochem Biophys Res Commun. 2000 Nov 30;278(3):646-52. Modeling a prion protein dimer: predictions for fibril formation.
Warwicker J.
Department of Biomolecular Sciences, UMIST, Manchester, M60 1QD, United Kingdom. jim.warwickemist.ac.uk
Models of structural transition in prion protein (PrP) focus on the domain visualised by solution NMR. Accumulating evidence suggests that the adjacent and highly conserved nonpolar segment, as well as PrP-membrane interactions, should also be considered. Calculations predict that membrane-induced structural destabilisation is mediated by stabilisation of the unfolded form. Comparative analysis of PrP structures leads to a model for PrP dimerisation that incorporates the nonpolar segment. A prediction that PrP will interact with the PrP-like protein (Dpl) to form a heterodimer, but that Dpl will not form a homodimer, can be tested. Modelling is discussed in the context of ataxias associated with the expression of Dpl or truncated PrP in transgenic animals lacking wild-type PrP. A PrP(C) dimer model forms the basis for considering the geometry of PrP(Sc) fibril formation. 2000 Academic Press.
PMID:_11095963
J Hepatol. 2000 Nov;33(5):751-7. Clinicopathological characterization of prion: a novel marker of activated human hepatic stellate cells.
Kitada T, Seki S, Ikeda K, Nakatani K, Sakaguchi H, Kawada N, Kadoya H, Kaneda K.
Third Department of Internal Medicine, Osaka City University Medical School, Japan.
BACKGROUND/AIMS: We recently demonstrated prion as a new marker for hepatic stellate cell activation in rats. Here, we have examined prion expression in normal and diseased human livers. METHODS: Prion expression was examined at protein level by immunohistochemistry and at mRNA level by in situ hybridization. RESULTS: While normal livers were negative for prion, all liver specimens but one from patients with chronic liver disease were positively stained. In chronic hepatitis, prion protein expression was found not only in the sinusoidal lining cells within the lobules but also in mesenchymal cells in expanded portal tracts. In alcoholic liver disease, prion-positive cells were found mainly in the areas of alcoholic hepatitis. Immunoelectronmicroscopy revealed that prion-positive cells were activated stellate cells. In situ hybridization demonstrated that the distribution of prion mRNA is similar to that of prion protein. In chronic hepatitis, the number of prion-positive cells correlated with the grade of activity but not with the stage of fibrosis. In alcoholic liver disease, levels of prion protein expression were significantly increased in the presence of alcoholic hepatitis. CONCLUSION: Prion as a novel marker of activated stellate cells correlates well with disease activity in human chronic liver diseases.
PMID:_11097483
Mol Microbiol. 2001 Jan;39(1):37-46. The relationship between visible intracellular aggregates that appear after overexpression of Sup35 and the yeast prion-like elements [PSI(+)] and [PIN(+)].
Zhou P, Derkatch IL, Liebman SW.
Laboratory for Molecular Biology, Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA.
Overproduced fusions of Sup35 or its prion domain with green fluorescent protein (GFP) have previously been shown to form frequent dots in [PSI(+)] cells. Rare foci seen in [psi(-)] cells were hypothesized to indicate the de novo induction of [PSI(+)] caused by the overproduced prion domain. Here, we describe novel ring-type aggregates that also appear in [psi(-)] cultures upon Sup35 overproduction and show directly that dot and ring aggregates only appear in cells that have become [PSI(+)]. The formation of either type of aggregate requires [PIN(+)], an element needed for the induction of [PSI(+)]. Although aggregates are visible predominantly in stationary-phase cultures, [PSI(+)] induction starts in exponential phase, suggesting that much smaller aggregates can also propagate [PSI(+)]. Such small aggregates are probably present in [PSI(+)] cells and, upon Sup35-GFP overproduction, facilitate the frequent formation of dot aggregates, but only the occasional appearance of ring aggregates. In contrast, rings are very frequent when [PSI(+)] cultures, including those lacking [PIN(+)], are grown in the presence of GuHCl or excess Hsp104 while overexpressing Sup35-GFP. Thus, intermediates formed during [PSI(+)] curing seem to facilitate ring formation. Surprisingly, GuHCl and excess Hsp104, which are known to promote loss of [PSI(+)], did not prevent the de novo induction of [PSI(+)] by excess Sup35 in [psi(-)][PIN(+)] strains.
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