A Quantitative proteomics study to investigate key proteins involved in oxidative pathways in patients with Alzheimer's disease

Alzheimer’s disease (AD) is an irreversible, progressive neurodegenerative disease that is characterized by accumulation of amyloid beta forming senile plaques and the deposition of microtubule-associated tau proteins into neurofibrillary tangles. It is primarily a disease of synaptic dysfunction and the loss of synapses can be correlated with cognitive decline. Oxidative stress also has been hypothesized to play an increasingly important role in pathogenesis of late onset AD. Using brain samples from participants in the Baltimore Longitudinal Study of Aging (BLSA) we developed and optimized a protein extraction protocol to investigate key proteins involved in oxidative pathways and the temporal relationship of synaptic dysfunction to onset of cognitive dysfunction. Using age matched samples from the BLSA who are cognitively normal, have mild cognitive impairment and those with dementia we investigated the role of TOMM40, COV-IV, synaptophysin and PSD95. Samples from the superior and middle temporal gyrus (SMTG) and middle frontal gyrus (MFG) were homogenized and soluble extracellular, cellular and insoluble fractions were extracted. Using semi-quantitative Western blotting the concentration of these proteins were measured and correlated with the onset of clinical symptoms of Alzheimer’s disease