PROJECT SUMMARY: Mechanisms underlying hippocampal synaptic plasticity, specifically long-term potentiation (LTP) and depression (LTD) of synaptic strength, are thought to underlie learning, memory, and cognition. These functions are disrupted in patients with Alzheimer’s disease (AD), and AD mouse models and acute hippocampal slices treated with β-amyloid (Aβ, a major neuropathological agent in AD) exhibit severe LTP impairments. LTP requires the Ca2+/calmodulin(CaM)-dependent protein kinase II α (CaMKIIα) and its regulated binding to synaptic NMDA-type glutamate receptors (NMDAR), which results in rapid CaMKIIα accumulation at excitatory synapses. My preliminary findings indicate that this CaMKIIα synaptic targeting is suppressed by acute Aβ application in a dose- and time-dependent manner that requires CaMKIIα activity. This suppression of CaMKIIα targeting suggests a potential disruption in the CaMKIIα/NMDAR interaction. Studies from our lab demonstrate that CaMKIIα/NMDAR binding can be suppressed by two distinct mechanisms: CaMKIIα T305/306 auto- phosphorylation (pT305/306) and activation of death associated protein kinase 1 (DAPK1). My preliminary results and recent published findings from our lab indicate that CaMKIIα pT305/306 and DAPK1 activation suppress CaMKIIα accumulation at excitatory synapses during LTD, making them potential candidates for mediating the Aβ-induced disruption in CaMKIIα targeting during LTP. As CaMKII movement to excitatory synapses is required for normal LTP, its suppression provides a mechanism for the well-described Aβ-induced impairment of LTP. Therefore, my proposal will investigate the hypothesis that the Aβ-induced LTP impairment is mediated by mechanisms that suppress CaMKIIα targeting to excitatory synapses, namely CaMKIIα pT305/306 and/or DAPK1 activation. Specifically, I will utilize pharmacological inhibition and mutant mouse lines to determine whether these mechanisms mediate the Aβ-induced suppression of CaMKIIα targeting to excitatory synapses and/or the Aβ-induced LTP impairment. Notably, this project employs the use of intrabodies to monitor endogenous CaMKIIα targeting to excitatory and inhibitory synapses during plasticity. This innovative strategy allows for the simultaneous imaging of multiple endogenous proteins in living cells, without impacting basal localization or cellular function. The results of this proposal will provide insight into the cellular and molecular mechanisms underlying Aβ-induced malfunctions in synaptic plasticity, and potentially contribute to our understanding of AD-related memory and cognitive impairments.