Alzheimer's disease (AD) is one of the major health problems in the United States and as our populationages it will become more prominent unless measures to treat or prevent it are found. Understanding thepathogenesis of selective neuron degeneration in AD is the key to defining preventive or therapeuticmeasures. There is a rapidly increasing body of knowledge that indicates free radical-mediated oxidativedamage is involved in the pathogenesis of AD. Our recent studies have demonstrated significant oxidativedamage to brain lipids, proteins, DMA, and RNA in amnestic mild cognitive impairment, the earliestdetectable phase of AD, indicating that oxidative damage is an early event in AD and not secondary toneurodegeneration. The major hypothesis of this proposal is that RNA oxidation in early AD is mediated inpart by amyloid-beta peptide (AP) that promotes impairment of protein synthesis and neuron dysfunction.
In Specific Aims 1 and 2, we will quantify RNA oxidation and aldehydic modifications in neurons in theprogression of AD from normal to MCI to late AD (LAD), and in the APP/PS1 knock-in transgenic mice overtime using immunohistochemistry, confocal microscopy, and antibodies against 8-OHG, acrolein/guanineadducts, and MC-1. In the same brain regions of normal controls, disease controls (frontotemporaldementia), MCI and LAD, and brain specimens from APP/PS-1 mice, we will quantify RNA oxidation inpurified pools of rRNA, tRNA, and mRNA by GC-MS-SIM and acrolein-modified guanine in these pools usingLC-MS-MS.
In Specific Aim 3, we will determine the ability of toxic and non-toxic Ap from Core B to defineRNA oxidation and acrolein/guanine adducts in cultured neurons and compare this with the RNA oxidationobserved in vivo in Specific Aims 1 and 2.
In Specific Aim 4, we will determine if the individual mRNAsoxidized in response to Ap in vitro are also oxidized in the brains of control subjects and MCI, LAD, andfrontotemporal dementia patients. We will then determine whether the predicted proteins encoded by theoxidized mRNAs exhibit decreased expression and function in the progression from normal to MCI to LAD.
Specific Aim 5 will define the ability of histone deacetylase inhibitors to ameliorate Ap-induced neurotoxicityin vitro and in the APP/PS1 transgenic mice. We have preliminary data in all specific aims indicating thefeasibility of these studies. By conducting these studies in an unbiased manner and allowing the neuronsand brain specimens to guide us, we will define how Ap promotes neuron dysfunction in AD. This study hasthe potential of identifying molecular targets for development of therapeutic agents aimed at reducing neuroninjury and slowing the progression of or potentially preventing AD.
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