Aging, and age-related disorders such as Alzheimer's disease (AD), are associated with progressive decreases in cognitive function. Markers of inflammation are also well-documented in both aging and AD brains, but it is not known how inflammatory pathways are initiated, nor are the cell types involved in the inflammatory cascade identified. In addition to inflammation, calcium overload, oxidative stress, and proteasome inhibition are all thought to participate in age-related declines. New data from our laboratory suggests that these seemingly disparate phenomena may be linked; whereby changes in proteasome expression and activity in response to increased intracellular calcium and oxidative stress initiate inflammation in neurons. The focus of this proposal, therefore, is to test the hypothesis that oxidative stress- and calcium-induced alterations to the proteasome lead to inflammation in aging and AD brains. Studies will determine the effects of increasing doses of age- and AD-related stimuli on proteasome subunit expression, proteasome activity, and immune signaling in cultured neurons. The relationships between proteasome alterations, calcium homeostasis, inflammatory signaling, and cell death will be determined. Studies will also be carried out in cultured astrocytes, microglial cells, and oligodendrocytes to determine cell-type specific components of proteasome-dependent inflammation and cytotoxicity. Additionally, the role of preserved proteasome homeostasis and prevention of proteasome-dependent inflammation in the therapeutic effects of minocycline and estrogen will be tested in vitro and in vivo. Concurrently, this project will serve as a Core for the PPG, generating primary cultures of rat neurons and glial cells and providing quantitative assessments of inflammatory and proteasome homeostasis in long-term intervention studies. Completion of these studies will greatly increase our understanding of the role of the proteasome in the aging brain, and could aid in the development of novel therapies for brain aging by targeting inflammation.
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