Characterization of puma-dependent and puma-independent neuronal cell death pathways following prolonged proteasomal inhibition

Liam P. Tuffy, Caoimhín G. Concannon, Beatrice D'Orsi, Matthew A. King, Ina Woods, Heinrich J. Huber, Manus Ward, Jochen H.M. Prehn

    Research output: Contribution to journalArticlepeer-review

    14 Scopus citations

    Abstract

    Proteasomal stress and the accumulation of polyubiquitinated proteins are key features of numerous neurodegenerative disorders. Previously we demonstrated that stabilization of p53 and activation of its target gene, puma (p53-upregulated mediator of apoptosis), mediated proteasome inhibitor-induced apoptosis in cancer cells. Here we demonstrated that Puma also contributed to proteasome inhibitor-induced apoptosis in mouse neocortical neurons. Although protection afforded by puma gene deletion was incomplete, we found little evidence indicating contributions from other proapoptotic BH3-only proteins. Attenuation of bax expression did not further reduce Puma-independent apoptosis, suggesting that pathways other than the mitochondrial apoptosis pathway were activated. Real-time imaging experiments in wild-type and puma-deficient neurons using a fluorescence resonance energy transfer (FRET)-based caspase sensor confirmed the involvement of a second cell death pathway characterized by caspase activation prior to mitochondrial permeabilization and, more prominently, a third, caspase-independent and Puma-independent pathway characterized by rapid cell shrinkage and nuclear condensation. This pathway involved lysosomal permeabilization in the absence of autophagy activation and was sensitive to cathepsin but not autophagy inhibition. Our data demonstrate that proteasomal stress activates distinct cell death pathways in neurons, leading to both caspase-dependent and caspase-independent apoptosis, and demonstrate independent roles for Puma and lysosomal permeabilization in this model.

    Original languageEnglish (US)
    Pages (from-to)5484-5501
    Number of pages18
    JournalMolecular and Cellular Biology
    Volume30
    Issue number23
    DOIs
    StatePublished - Dec 1 2010

    ASJC Scopus subject areas

    • Molecular Biology
    • Cell Biology

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