Oxidative damage in nucleic acids and Parkinson's disease

Area of Science:

• Molecular Biology
• Neuroscience
• Genetics

Background:

• Oxidative DNA lesions like 8-oxoguanine (8-oxoG) accumulate with aging and are elevated in Parkinson's disease (PD).
• Human and rodent cells possess three enzymes (MTH1, OGG1, MUTYH) to counteract oxidative damage to nucleic acids.
• MTH1 hydrolyzes oxidized purine nucleoside triphosphates, while OGG1 and MUTYH are DNA glycosylases.

Purpose of the Study:

• To investigate the role of oxidative DNA damage and repair enzymes in Parkinson's disease pathogenesis.
• To determine the impact of MTH1 deficiency on cellular susceptibility to oxidative stress and DNA lesion accumulation.
• To assess the consequences of MTH1 deficiency on neuronal function and vulnerability in a PD model.

Main Methods:

• Analysis of 8-oxoG levels and expression of MTH1, OGG1, and MUTYH in dopaminergic neurons of PD patients.
• Generation and characterization of MTH1-null mice and fibroblasts.
• Assessment of cell death, DNA lesion accumulation, and neuronal dysfunction in MTH1-null models under oxidative stress conditions.

Main Results:

• PD patients showed increased 8-oxoG in mitochondrial DNA and elevated MTH1, OGG1, and MUTYH expression in nigrostriatal dopaminergic neurons.
• MTH1-null fibroblasts exhibited high susceptibility to hydrogen peroxide-induced cell death with significant 8-oxoG accumulation.
• MTH1-null mice displayed increased 8-oxoG in striatal mitochondrial DNA and exacerbated neuronal dysfunction following MPTP administration.

Conclusions:

• Oxidative damage to nucleic acids is a significant risk factor for Parkinson's disease.
• The MTH1 enzyme plays a crucial role in protecting against oxidative DNA damage, particularly in neurons.
• Understanding these defense mechanisms may lead to novel therapeutic strategies for neuroprotection against oxidative stress in PD.