PT  - JOURNAL ARTICLE
AU  - Evgenia Paxinou
AU  - Qiping Chen
AU  - Marie Weisse
AU  - Benoit I. Giasson
AU  - Erin H. Norris
AU  - Susan M. Rueter
AU  - John Q. Trojanowski
AU  - Virginia M.-Y. Lee
AU  - Harry Ischiropoulos
TI  - Induction of α-Synuclein Aggregation by Intracellular Nitrative Insult
AID  - 10.1523/JNEUROSCI.21-20-08053.2001
DP  - 2001 Oct 15
TA  - The Journal of Neuroscience
PG  - 8053--8061
VI  - 21
IP  - 20
4099  - http://www.jneurosci.org/content/21/20/8053.short
4100  - http://www.jneurosci.org/content/21/20/8053.full
SO  - J. Neurosci.2001 Oct 15; 21
AB  - Brain lesions containing filamentous and aggregated α-synuclein are hallmarks of neurodegenerative synucleinopathies. Oxidative stress has been implicated in the formation of these lesions. Using HEK 293 cells stably transfected with wild-type and mutant α-synuclein, we demonstrated that intracellular generation of nitrating agents results in the formation of α-synuclein aggregates. Cells were exposed simultaneously to nitric oxide- and superoxide-generating compounds, and the intracellular formation of peroxynitrite was demonstrated by monitoring the oxidation of dihydrorhodamine 123 and the nitration of α-synuclein. Light microscopy using antibodies against α-synuclein and electron microscopy revealed the presence of perinuclear aggregates under conditions in which peroxynitrite was generated but not when cells were exposed to nitric oxide- or superoxide-generating compounds separately. α-Synuclein aggregates were observed in 20–30% of cells expressing wild-type or A53T mutant α-synuclein and in 5% of cells expressing A30P mutant α-synuclein. No evidence of synuclein aggregation was observed in untransfected cells or cells expressing β-synuclein. In contrast, selective inhibition of the proteasome resulted in the formation of aggregates detected with antibodies to ubiquitin in the majority of the untransfected cells and cells expressing α-synuclein. However, α-synuclein did not colocalize with these aggregates, indicating that inhibition of the proteasome does not promote α-synuclein aggregation. In addition, proteasome inhibition did not alter the steady-state levels of α-synuclein, but addition of the lysosomotropic agent ammonium chloride significantly increased the amount of α-synuclein, indicating that lysosomes are involved in degradation of α-synuclein. Our data indicate that nitrative and oxidative insult may initiate pathogenesis of α-synuclein aggregates.