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Overexpression of the autophagic beclin-1 protein clears mutant ataxin-3 and alleviates Machado–Joseph disease

Isabel Nascimento-Ferreira, Tiago Santos-Ferreira, Lígia Sousa-Ferreira, Gwennaëlle Auregan, Isabel Onofre, Sandro Alves, Noëlle Dufour, Veronica F. Colomer Gould, Arnulf Koeppen, Nicole Déglon, Luís Pereira de Almeida
DOI: http://dx.doi.org/10.1093/brain/awr047 awr047 First published online: 7 April 2011

Summary

Machado–Joseph disease, also known as spinocerebellar ataxia type 3, is the most common of the dominantly inherited ataxias worldwide and is characterized by mutant ataxin-3 misfolding, intracellular accumulation of aggregates and neuronal degeneration. Here we investigated the implication of autophagy, the major pathway for organelle and protein turnover, in the accumulation of mutant ataxin-3 aggregates and neurodegeneration found in Machado–Joseph disease and we assessed whether specific stimulation of this pathway could mitigate the disease. Using tissue from patients with Machado–Joseph disease, transgenic mice and a lentiviral-based rat model, we found an abnormal expression of endogenous autophagic markers, accumulation of autophagosomes and decreased levels of beclin-1, a crucial protein in the early nucleation step of autophagy. Lentiviral vector-mediated overexpression of beclin-1 led to stimulation of autophagic flux, mutant ataxin-3 clearance and overall neuroprotective effects in neuronal cultures and in a lentiviral-based rat model of Machado–Joseph disease. These data demonstrate that autophagy is a key degradation pathway, with beclin-1 playing a significant role in alleviating Machado–Joseph disease pathogenesis.

  • Machado–Joseph disease
  • ataxin-3
  • autophagy
  • beclin-1
  • neuroprotection
  • Abbreviations
    Atg
    autophagic related protein
    DARPP-32
    dopamine-and-cyclic AMP-regulated phosphoprotein of 32 kDa
    p62
    sequestosome 1/p62 protein
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