Reactive oxygen species and mitochondrial dysfunction are critical determinants of neuronal cell death triggered by proteasome inhibition.
Item
-
Title
-
Reactive oxygen species and mitochondrial dysfunction are critical determinants of neuronal cell death triggered by proteasome inhibition.
-
Identifier
-
AAI3314669
-
identifier
-
3314669
-
Creator
-
Papa, Luena.
-
Contributor
-
Advisers: Patricia Rockwell | Richard Chappell
-
Date
-
2008
-
Language
-
English
-
Publisher
-
City University of New York.
-
Subject
-
Biology, Cell | Biology, Molecular | Biology, Neuroscience
-
Abstract
-
While increasing evidence shows that proteasome inhibition triggers oxidative damage, mitochondrial dysfunction and death in neuronal cells, the regulatory relationship among these events is unclear. Using mouse neuronal cells we show that the cytotoxicity induced by mild (0.25 muM) and potent (5.0 muM) levels of the reversible proteasome inhibitor, [N-Benzyloxycarbonyl-Ile-Glu (O-t-bytul)-Ala-leucinal; (PSI)] involved a dose- and time-dependent increase in caspase activation, overproduction of reactive oxygen species (ROS) and mitochondrial dysfunction. This dysfunction is manifested by membrane permeabilization and translocation of the proapoptotic protein, Bax, from the cytoplasm to the mitochondria and the release of cytochrome c and the apoptosis inducing factor (AIF) from mitochondria to the cytoplasm and nucleus, respectively. Whereas caspase and/or Bax inhibition offered no protection against a collapse in mitochondrial membrane potential and cell death, pretreatments with the antioxidant N-acetyl-L-cysteine (NAC) or overexpression of the antiapoptotic protein Bcl-xL abrogated these events in cells exposed or recovering from mild levels of PSI. These findings implicated ROS as a mediator of mitochondrial permeabilization and a caspase-independent cell death triggered by PSI. Moreover, the persistence of this oxidative insult and a collapse in inner mitochondrial potential follows a recovery from inhibitor removal over time. As proteasome inhibition intensified, Bcl-xL and glutathione depletion exacerbated the cellular responses that culminated in neuronal cell loss. Whereas, NAC alone augmented proteasome function, but not survival in cells exposed or recovering from extensive proteasome impairment, both NAC and Bcl-xL overexpression in concert were required to diminish mitochondrial permeabilization and subsequent cell death. Collectively, these results implicate the extent of oxidative stress and mitochondrial impairment as determinants of neuronal cell death.
-
Type
-
dissertation
-
Source
-
PQT Legacy CUNY.xlsx
-
degree
-
Ph.D.
