Oxidative damage to DNA: implications for neurodegeneration in aging Accumulation of the oxidatively damaged DNA base 8-hydroxy-2'-deoxyguanosine (oxo8dG) in distinct brain regions afflicted by neuronal loss is a common finding in aging and neurological disease. It has been shown that surviving neurons in brain regions impacted in age-related neurological deficits carry increased levels of oxo8dG;and recently it has been demonstrated that prior to neuronal degeneration there is a significant increase in oxo8dG levels in nuclear DNA. However, the mechanism of neuronal death triggered by elevated oxo8dG levels remains unknown. We have used a mice model that is deficient or null for the expression of the enzyme 8-hydroxyglycosylase, Ogg1, required for the repair of oxo8dG. These mice accumulate oxo8dG in an inverse relation to the level of Ogg1 expression and such an accumulation is accentuated by aging. Initial analyses show that lack of Ogg1 leads to an age-dependent loss in the nigrostriatal system and an increased susceptibility to dopaminergic toxins. In addition, we have found that Ogg1 expression appears to be dependent to changes in the redox state of the cell. Thus, we hypothesize that oxo8dG levels are not only epiphenomena of neurodegeneration, but a player in the neurodegenerative cascade. The studies in this proposal are aimed to establish a quantal relation between oxidative DNA damage and age-dependent and toxicological loss of the nigrostriatal system identifying the neurodegenerative mechanism involved (Specific Aim 1).
Specific Aim 2 will discern the cellular triggers that control Ogg1 expression, which will allow us to glimpse mechanism that allow for accumulation of oxo8dG in neurons and alter cell vulnerability.
Specific Aim 3 is designed to test the hypothesis that reestablishing Ogg1 expression in nigral dopaminergic neurons will afford neuroprotection. This model of increased susceptibility and accelerated age-dependent loss in the nigrostriatal system will allow us to test novel pharmacological and genetic manipulations to evaluate neuroprotective approaches, the simplicity of one gene one pathology can help us glean into direct mechanisms leading to neuronal loss and relevant therapeutic implications.

Public Health Relevance

The development of most neurodegenerative diseases is associated with increased oxidative damage to DNA;however, the mechanisms associated with oxidative damage-driven neuronal loss in neurodegenerative diseases is poorly understood. This proposal is designed to address such mechanisms and to use this information to design therapeutic approaches that target oxidative damage to DNA aimed to treat or prevent disease.

Agency
National Institute of Health (NIH)
Institute
National Institute on Aging (NIA)
Type
Research Project (R01)
Project #
5R01AG031184-04
Application #
8225196
Study Section
Neural Oxidative Metabolism and Death Study Section (NOMD)
Program Officer
Wise, Bradley C
Project Start
2009-01-01
Project End
2013-12-31
Budget Start
2012-01-01
Budget End
2013-12-31
Support Year
4
Fiscal Year
2012
Total Cost
$271,786
Indirect Cost
$76,710
Name
University of Montana
Department
Other Health Professions
Type
Schools of Pharmacy
DUNS #
010379790
City
Missoula
State
MT
Country
United States
Zip Code
59812
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Bolin, Celeste; Cardozo-Pelaez, Fernando (2009) Characterization of oxidized guanosine 5'-triphosphate as a viable inhibitor of soluble guanylyl cyclase. Free Radic Biol Med 46:828-35