PROJECT SUMMARY/ABSTRACT Alzheimer's disease (AD) currently affects more than 5 million Americans and is a significant burden for patients, caregivers, and our healthcare system. Currently, there is no known cure for AD, and approved therapies do not reverse the underlying pathogenesis or inhibit disease progression. Amyloid deposits and their associated amyloid beta oligomers (A?) are linked to multiple cellular dysfunctions in the brains of AD patients and in animal and cell culture models of AD. Some of these dysfunctions include microtubule instability, loss of dendritic spine density, and depressed hippocampal long-term potentiation (LTP). Many hypotheses have been put forward to explain the routes by which A? contributes to these phenotypes. However, a unified mechanistic understanding has not yet been achieved. This project builds on previous studies that have shown that A? inhibits the activity of a select set of microtubule motor proteins. Among them, Kinesin-5/EG5/KIF11 is of particular interest due to its diverse functions, which include regulating microtubule stability, microtubule polymerization, and dendritic architecture, all of which are negatively impacted by A?. Based on these findings, the long-term goal of this project is to determine whether Kinesin-5 activity may serve as an effective target for preventing or reversing A ? -induced AD phenotypes: 1) by overexpressing Kinesin-5 to maintain its activity, or 2) by using small molecule drugs we identified in a screen that block A?-mediated inhibition of Kinesin-5 activity. In order to address these goals we are using a mouse model system in combination with cell culture and biochemical tests that aim to 1) Determine whether Kinesin-5 overexpression improves learning and memory in a wild-type mouse without AD pathology and whether Kinesin-5 overexpression rescues A?-induced AD phenotypes in the an AD mouse model; 2) Determine whether Kinesin-5 overexpression improves long-term potentiation (LTP) and whether deficits in LTP caused by A? are rescued by Kinesin-5 overexpression; and 3) Determine whether Kinesin-5 overexpression impacts neural process outgrowth, spine density, and morphology in wild-type and 5xFAD mice. Our proposed research will also provide an increased understanding of the role of Kinesin-5 activity in regulating diverse neuronal processes. The clinical significance of this work comes from the identification of underlying mechanisms linked to aberrant cellular functions that may uncover an entirely new therapeutic approach to AD. The innovative aspects of this project are rooted in the identification of Kinesin-5 as a potential therapeutic target for the treatment of AD and include: 1) interrogating of as yet uncharacterized functions of Kinesin-5 in learning, memory, and AD-related phenotypes; and 2) pursuing an entirely new avenue of investigation into desperately needed AD treatments using Kinesin-5 activity as a therapeutic target. !