Human PrP90-231-induced cell death is associated with intracellular accumulation of insoluble and protease-resistant macroaggregates and lysosomal dysfunction

S. Thellung, A. Corsaro, V. Villa, S. Simi, S. Vella, A. Pagano, T. Florio

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

To define the mechanisms by which hPrP90-231 induces cell death, we analyzed its interaction with living cells and monitored its intracellular fate. Treatment of SH-SY5Y cells with fluorescein-5-isothiocyanate (FITC)-conjugated hPrP90-231 caused the accumulation of cytosolic aggregates of the prion protein fragment that increased in number and size in a time-dependent manner. The formation of large intracellular hPrP90-231 aggregates correlated with the activation of apoptosis. hPrP90-231 aggregates occurred within lysotracker-positive vesicles and induced the formation of activated cathepsin D (CD), indicating that hPrP90-231 is partitioned into the endosomal-lysosomal system structures, activating the proteolytic machinery. Remarkably, the inhibition of CD activity significantly reduced hPrP-90-231-dependent apoptosis. Internalized hPrP90-231 forms detergentinsoluble and SDS-stable aggregates, displaying partial resistance to proteolysis. By confocal microscopy analysis of Lucifer yellow (LY) intracellular partition, we show that hPrP90-231 accumulation induces lysosome destabilization and loss of lysosomal membrane impermeability. In fact, although control cells evidenced a vesicular pattern of LY fluorescence (index of healthy lysosomes), hPrP90-231-treated cells showed diffuse cytosolic fluorescence, indicating LY diffusion through damaged lysosomes. In conclusion, these data indicate that exogenously added hPrP90-231 forms intralysosomal deposits having features of insoluble, protease-resistant aggregates and could trigger a lysosome-mediated apoptosis by inducing lysosome membrane permeabilization, followed by the release of hydrolytic enzymes.

Original languageEnglish
Article numbere138
JournalCell Death and Disease
Volume2
Issue number3
DOIs
Publication statusPublished - Mar 2011

Fingerprint

Lysosomes
Peptide Hydrolases
Cell Death
Cathepsin D
Apoptosis
Fluorescence
Membranes
Fluorescein-5-isothiocyanate
Confocal Microscopy
Proteolysis
Enzymes
lucifer yellow

Keywords

  • Apoptosis
  • Cell internalization
  • Lysoome dysfunction
  • Prion diseases
  • Prion protein
  • Proteinase K resistence

ASJC Scopus subject areas

  • Cell Biology
  • Immunology
  • Cancer Research
  • Cellular and Molecular Neuroscience
  • Medicine(all)

Cite this

Human PrP90-231-induced cell death is associated with intracellular accumulation of insoluble and protease-resistant macroaggregates and lysosomal dysfunction. / Thellung, S.; Corsaro, A.; Villa, V.; Simi, S.; Vella, S.; Pagano, A.; Florio, T.

In: Cell Death and Disease, Vol. 2, No. 3, e138, 03.2011.

Research output: Contribution to journalArticle

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AB - To define the mechanisms by which hPrP90-231 induces cell death, we analyzed its interaction with living cells and monitored its intracellular fate. Treatment of SH-SY5Y cells with fluorescein-5-isothiocyanate (FITC)-conjugated hPrP90-231 caused the accumulation of cytosolic aggregates of the prion protein fragment that increased in number and size in a time-dependent manner. The formation of large intracellular hPrP90-231 aggregates correlated with the activation of apoptosis. hPrP90-231 aggregates occurred within lysotracker-positive vesicles and induced the formation of activated cathepsin D (CD), indicating that hPrP90-231 is partitioned into the endosomal-lysosomal system structures, activating the proteolytic machinery. Remarkably, the inhibition of CD activity significantly reduced hPrP-90-231-dependent apoptosis. Internalized hPrP90-231 forms detergentinsoluble and SDS-stable aggregates, displaying partial resistance to proteolysis. By confocal microscopy analysis of Lucifer yellow (LY) intracellular partition, we show that hPrP90-231 accumulation induces lysosome destabilization and loss of lysosomal membrane impermeability. In fact, although control cells evidenced a vesicular pattern of LY fluorescence (index of healthy lysosomes), hPrP90-231-treated cells showed diffuse cytosolic fluorescence, indicating LY diffusion through damaged lysosomes. In conclusion, these data indicate that exogenously added hPrP90-231 forms intralysosomal deposits having features of insoluble, protease-resistant aggregates and could trigger a lysosome-mediated apoptosis by inducing lysosome membrane permeabilization, followed by the release of hydrolytic enzymes.

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