Chapter Category: DNA

From the book DNA Repair and Human Disease

Mechanisms of DNA Damage and Repair in Alzheimer Disease

V. Prakash Reddy, George Perry, Marcus S. Cooke, Lawrence M. Sayre and Mark A. Smith

Reactive oxygen species (ROS) are produced during the respiratory cycle in mitochon- dria,1 as well as normal cellular and xenobiotic metabolism. Exposure to various noxious insults can also lead to ROS production. In addition, ROS are also generated through metal-catalyzed reactions. A consequence of ROS production is the modification of cellular biomolecules, such as DNA, protein and lipids.2,3 In addition to mutation, which is commonly considered, oxidative modification of DNA can have other, broad-ranging effects upon the function of the cell, impacting upon telomeres, microsatellite sequences, promoters and sites of methylation.4,5 Perhaps as a consequence, such damage appears to have an important role in the pathogenesis of many diseases,4 including Alzheimer disease (AD). Notably in AD, oxidative stress is regarded as one of the earliest pathological changes6,7 and likely involves metabolic changes,8 and redox-active metals9,10 as well as other factors.11 Oxidative modification of nuclear and mitochondrial DNA are thought to exacerbate AD, and their measurement is often used as a marker of oxidative stress. Indeed, extensive mitochondrial DNA damage was observed when PC12 cells were exposed to amyloid-b (Ab), showing a direct correlation between oxidative stress and DNA damage.12 Treatment of the exposed cells with endonuclease III or formamidopyrimidine (FaPy) glycosylase revealed significant damage to pyrimidine or purine bases, although in recent studies Ab was found to sequester ROS, thus acting as an antioxidant equivalent.13

Taken from the book

DNA Repair and Human Disease

Edited by: Adayabalam Balajee

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