A role for oxidized DNA precursors in Huntington's disease-like striatal neurodegeneration.
Several human neurodegenerative disorders are characterized by the accumulation of 8-oxo-7,8-dihydroguanine (8-oxodG) in the DNA of affected neurons. This can occur either through direct oxidation of DNA guanine or via incorporation of the oxidized nucleotide during replication. Hydrolases that degrade oxidized purine nucleoside triphosphates normally minimize this incorporation. hMTH1 is the major human hydrolase. It degrades both 8-oxodGTP and 8-oxoGTP to the corresponding monophosphates. To investigate whether the incorporation of oxidized nucleic acid precursors contributes to neurodegeneration, we constructed a transgenic mouse in which the human hMTH1 8-oxodGTPase is expressed. hMTH1 expression protected embryonic fibroblasts and mouse tissues against the effects of oxidants. Wild-type mice exposed to 3-nitropropionic acid develop neuropathological and behavioural symptoms that resemble those of Huntington's disease. hMTH1 transgene expression conferred a dramatic protection against these Huntington's disease-like symptoms, including weight loss, dystonia and gait abnormalities, striatal degeneration, and death. In a complementary approach, an in vitro genetic model for Huntington's disease was also used. hMTH1 expression protected progenitor striatal cells containing an expanded CAG repeat of the huntingtin gene from toxicity associated with expression of the mutant huntingtin. The findings implicate oxidized nucleic acid precursors in the neuropathological features of Huntington's disease and identify the utilization of oxidized nucleoside triphosphates by striatal cells as a significant contributor to the pathogenesis of this disorder.
De Luca
Gabriele
G
Department of Environment and Primary Prevention, Experimental Carcinogenesis Division, Istituto Superiore di Sanità, Rome, Italy.
Russo
Maria Teresa
MT
Degan
Paolo
P
Tiveron
Cecilia
C
Zijno
Andrea
A
Meccia
Ettore
E
Ventura
Ilenia
I
Mattei
Elisabetta
E
Nakabeppu
Yusaku
Y
Crescenzi
Marco
M
Pepponi
Rita
R
Pèzzola
Antonella
A
Popoli
Patrizia
P
Bignami
Margherita
M
D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D003342:Corpus Striatum / Q000378:metabolism*; D004249:DNA Damage; D045643:DNA Repair Enzymes / Q000235:genetics / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000378:metabolism; D004622:Embryo, Mammalian / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D019636:Neurodegenerative Diseases / Q000235:genetics / Q000378:metabolism*; D009574:Nitro Compounds / Q000633:toxicity; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism; D011422:Propionates / Q000633:toxicity; D013234:Stem Cells / Q000378:metabolism
D018076:DNA, Complementary; C506812:Htt protein, mouse; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D009574:Nitro Compounds; D009687:Nuclear Proteins; D011422:Propionates; C024829:8-hydroxyguanine; D006147:Guanine; D000080242:8-Hydroxy-2'-Deoxyguanosine; D010744:Phosphoric Monoester Hydrolases; C078207:8-oxodGTPase; D045643:DNA Repair Enzymes; D003849:Deoxyguanosine; C015392:3-nitropropionic acid