Download NADPH Oxidase 1, a novel molecular source of ROS in

NADPH Oxidase 1, a novel molecular source of ROS in
dopaminergic neuronal death
Dong- Hee Choi, PhD.
ABSTRACT
While oxidative stress has been strongly implicated in the pathogenesis of
Parkinson’s disease (PD), the molecular mechanism underlying selective
vulnerability of the nigrostriatal dopaminergic pathway to oxidative damage
remains unknown. Increased levels of reactive oxygen species (ROS) result in
accumulation of oxidative damage to a variety of cellular macromolecule
including DNA. Here we report that dopaminergic cells are equipped with the
NADPH oxidase 1 (Nox1) enzyme complex, a specialized superoxide
generation system. In dopaminergic (DA) cells treated with 6-hydroxydopamine
(6-OHDA), Nox1 level in the nucleus was increased. Increased nuclear
localization of activated Rac1, a key component for Nox1 activation was also
observed. DNA oxidative damage was elevated as determined by increased 8oxo-2'-deoxyguanosine (8-oxo2dG) immunoreactivity in the nucleus. Either
RNAi-mediated knock down of Nox1 or inhibition of Rac1 by overexpressing
dominant negative Rac1 (T17N Rac1) led to reduction in ROS generation,
decrease in nuclear 8-oxo-2dG immunoreactivity and diminish in DA cell death.
In vivo, increased Nox1 level as well as 8-oxo-2dG in the nucleus of substantia
nigra (SN) DA neurons are confirmed in rats striatally injected with 6-OHDA.
Both 8-oxo-2dG level and DA neuronal death were significantly reduced by
adeno-associated virus (AAV)-mediated transduction of Nox1 shRNA or T17N
Rac1 in the SN. The identification of Nox1 in DA neurons in postmortem PD
patients further support that Nox1 is a major source of ROS that is responsible
for oxidative damage to DNA and subsequent DA neuronal degeneration.