Neuron-glia interactions: Molecular basis of alzheimer's disease and applications of neuroproteomics

Neurodegenerative disorders present with progressive and irreversible degeneration of the neurons. Alzheimer's disease (AD) is one of the most common neurodegenerative disorders affecting 50 million people worldwide (2017), expected to be doubled every 20 years. Primarily affected by age, AD is the cause for old-age dementia, progressive memory loss, dysfunctional thoughts, confusion, cognitive impairment and personality changes. Neuroglia formerly understood as "glue" of the brain neurons consists of macroglia (astrocytes and oligodendrocyte), microglia and progenitors NG2-glia, and constitute a large fraction of the mammalian brain. The primary functions of glial cells are to provide neurons with metabolic and structural support in the healthy brain; however, they attain a "reactive" state from the "resting" state upon challenged with a pathological insult such as a neurodegenerative cascade. Failure or defects in their homoeostatic functions (i.e. concentration of ions, neurotransmitters) ultimately jeopardize neurons with excitotoxicity and oxidative stress. Moreover, the most common clinical outcome of AD is the cognitive impairment and memory loss, which are attributed mainly by the accumulation of A beta. Failure of glial cells to remove the A beta toxic proteins accelerates the AD progression. The rapidly emerging proteomic techniques such as mass spectrometry (MS), cross-linking mass spectrometry, hydrogen deuterium trade mass spectrometry, protein foot printing and 2-DGE combined with LC-MS/MS present wide array of possibilities for the identification of differentially expressed proteins in AD.