1,721,164 research outputs found

    Co-localization of truncated tau and DNA fragmentation in Alzheimer's disease neurones

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    Monoclonal antibody MN423 stains all hallmarks of tau neurofibrillary pathology in Alzheimer's disease (AD), without reacting with full-length tau. It recognizes tau molecules which are cleaved at Glu-391, suggesting that tau is endogenously truncated in AD brains. We investigated whether truncation of tau takes place in pre-tangle neurones. Our results showed that tau truncation occurs inside AD neurones in the absence of other signs of AD neurofibrillary pathology. Using in situ end labelling (ISEL) of DNA we found evidence for DNA fragmentation in a significant subpopulation of MN423-positive neurones. Our results therefore suggest that tau truncation is an early intracellular event preceding cell death in AD

    Apoptotic effect of caspase-3 cleaved tau in hippocampal neurons and its potentiation by tau FTDP-mutation N279K

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    Pathological changes in the microtubule associated protein tau are a major hallmark of many human dementias collectively defined as tauopathies. In familiar frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17), several mutations in the tau gene have been identified showing that primary malfunction of tau can lead to neurodegeneration. In addition to mutation at genetic level, a number of post-translational modifications of tau occur in tauopathies, including abnormal phosphorylation and aberrant proteolysis described in Alzheimer's Disease (AD). The presence of cleaved tau in AD neurons is associated with expression of markers for neuronal death. According to our previous work, tau is a substrate for the apoptotic protease caspase-3 that turns tau itself into an effector of apoptosis (tau cleaved at D-421), generating a positive-feedback loop that is self-propagating. Cleavage of tau by caspase-3 was recently confirmed to occur in AD brain as an early event. Here we show the apoptotic properties of tau fragment tau151-421 in primary cultures of rat hippocampal neurons; such cellular model is of special interest considering the selective vulnerability of hippocampal neurones in AD. The apoptotic capacity of tau151-421 is markedly enhanced by both treatment with amyloid peptide Abeta25-35, and the FTDP-17 tau mutation N279K

    Ettore Majorana: l'uomo e lo scienziato

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    Erasmo Recami: Sciascia e Majorana. Il problema della responsabilità dello scienziat
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