title: Nitric oxide synthase-3 overexpression causes apoptosis and impairs neuronal mitochondrial function: relevance to Alzheimer's-type neurodegeneration.
abstract: Dementia in Alzheimer's disease (AD) is correlated with cell loss that is mediated by apoptosis, mitochondrial (Mt) dysfunction, and possibly necrosis. Previous studies demonstrated increased expression of the nitric oxide synthase 3 (NOS3) gene in degenerating neurons of AD brains. For investigating the role of NOS3 overexpression as a mediator of neuronal loss, human PNET2 central nervous system-derived neuronal cells were infected with recombinant adenovirus vectors that expressed either human NOS3 or green fluorescent protein cDNA under the control of a CMV promoter. NOS3 overexpression resulted in apoptosis accompanied by increased levels of p53, p21/Waf1, Bax, and CD95. In addition, NOS3 overexpression impaired neuronal Mt function as demonstrated by the reduced levels of 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide and nicotinamide adenine dinucleotide (reduced form)-tetrazolium reductase activities and MitoTracker Red fluorescence. These adverse effects of NOS3 were associated with increased cellular levels of reactive oxygen species and impaired membrane integrity and were not produced in cells that were transfected with a cDNA encoding catalytically inactive NOS3. Importantly, modest elevations in NOS3 expression, achieved by infection with low multiplicities of adenovirus-NOS3 infection, did not cause apoptosis but rendered the cells more sensitive to oxidative injury by H(2)O(2) or diethyldithiocarbamate. In contrast, treatment with NO donors did not enhance neuronal sensitivity to oxidative injury. These results suggest that NOS3-induced neuronal death is mediated by Mt dysfunction, oxidative injury, and impaired membrane integrity, rather than by NO production, and that neuroprotection from these adverse effects of NOS3 may be achieved by modulating intracellular levels of oxidative stress.
authors.affiliation: Department of Medicine, Rhode Island Hospital and Brown Medical School, Providence, Rhode Island 02903, USA. Suzanne_DeLaMonte_MD@Brown.edu
authors.forename: Suzanne M
authors.initials: SM
authors.lastname: de la Monte
authors.forename: Jean- Daniel
authors.initials: J
authors.lastname: Chiche
authors.forename: Annette
authors.initials: A
authors.lastname: von dem Bussche
authors.forename: Sohini
authors.initials: S
authors.lastname: Sanyal
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Lahousse
authors.forename: Stephan P
authors.initials: SP
authors.lastname: Janssens
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Bloch
mesh_terms: D000544:Alzheimer Disease / Q000201:enzymology* / Q000209:etiology / Q000473:pathology*; D017209:Apoptosis; D002478:Cells, Cultured; D006801:Humans; D008928:Mitochondria / Q000201:enzymology*; D009474:Neurons / Q000201:enzymology* / Q000473:pathology*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III