title: Elevated NADPH oxidase activity contributes to oxidative stress and cell death in Huntington's disease.
abstract: A mutation in the huntingtin (Htt) gene produces mutant Htt and Huntington's disease (HD), a neurodegenerative disorder. HD patients have oxidative damage in the brain, but the causes are unclear. Compared with controls, we found brain levels of NADPH oxidase (NOX) activity, which produces reactive oxygen species (ROS), elevated in human HD postmortem cortex and striatum and highest in striatum of presymptomatic individuals. Synaptosome fractions from cortex and striatum of HD(140Q/140Q) mice had elevated NOX activity at 3 months of age and a further rise at 6 and 12 months compared with synaptosomes of age-matched wild-type (WT) mice. High NOX activity in primary cortical and striatal neurons of HD(140Q/140Q) mice correlated with more ROS and neurite swellings. These features and neuronal cell death were markedly reduced by treatment with NOX inhibitors such as diphenyleneiodonium (DPI), apocynin (APO) and VAS2870. The rise in ROS levels in mitochondria of HD(140Q/140Q) neurons followed the rise in NOX activity and inhibiting only mitochondrial ROS was not neuroprotective. Mutant Htt colocalized at plasma membrane lipid rafts with gp91-phox, a catalytic subunit for the NOX2 isoform. Assembly of NOX2 components at lipid rafts requires activation of Rac1 which was also elevated in HD(140Q/140Q) neurons. HD(140Q/140Q) mice bred to gp91-phox knock-out mice had lower NOX activity in the brain and in primary neurons, and neurons had normal ROS levels and significantly improved survival. These findings suggest that increased NOX2 activity at lipid rafts is an early and major source of oxidative stress and cell death in HD(140Q/140Q) neurons.
authors.affiliation: Department of Neurology, Massachusetts General Hospital and Harvard Medical School, 114 16th Street, Charlestown, MA 02129, USA.
authors.forename: Antonio
authors.initials: A
authors.lastname: Valencia
authors.forename: Ellen
authors.initials: E
authors.lastname: Sapp
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Kimm
authors.forename: Hollis
authors.initials: H
authors.lastname: McClory
authors.forename: Patrick B
authors.initials: PB
authors.lastname: Reeves
authors.forename: Jonathan
authors.initials: J
authors.lastname: Alexander
authors.forename: Kwadwo A
authors.initials: KA
authors.lastname: Ansong
authors.forename: Nicholas
authors.initials: N
authors.lastname: Masso
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Frosch
authors.forename: Kimberly B
authors.initials: KB
authors.lastname: Kegel
authors.forename: Xueyi
authors.initials: X
authors.lastname: Li
authors.forename: Marian
authors.initials: M
authors.lastname: DiFiglia
mesh_terms: D000818:Animals; D016923:Cell Death; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009474:Neurons / Q000166:cytology / Q000201:enzymology / Q000378:metabolism; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism; D015854:Up-Regulation
chemical_list: C086055:HTT protein, human; D000071058:Huntingtin Protein; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D017382:Reactive Oxygen Species; C488842:Cybb protein, mouse; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases