PROJECT SUMMARY Synaptic plasticity, specifically long-term potentiation (LTP), is thought to underlie learning, memory, and cognition. This function is disrupted in aging populations, where cognitive decline, such as forgetfulness and decreased problem-solving capacity, is a well known impairment. LTP requires Ca2+/calmodulin (CaM)- dependent protein kinase II (CaMKII), its Ca2+-independent autonomous activity and regulated binding to N- methyl-D-aspartate receptor (NMDAR), which results in CaMKII translocation to excitatory synapses. It has recently been suggested that hypo-nitrosylation may underlie the cognitive impairment seen in aging. My preliminary live-imaging data demonstrate that application of an NO donor is sufficient to stimulate CaMKII translocation to excitatory synapses and that this effect is abolished in a genetically modified knock-in mouse line, CaMKIIΔSNO, in which CaMKII is rendered un-nitrosylable. Other preliminary data from the lab suggests that these mice demonstrate normal high frequency stimulation (HFS)-induced LTP, but have impaired theta burst stimulation (TBS)-induced LTP, which mimics what is seen in aged animals. My proposal will test the hypotheses that (i) CaMKII synaptic targeting can be regulated by nitrosylation and (ii) CaMKII hypo-nitrosylation mediates both age-related LTP and cognitive impairment. Specifically, I will use live-imaging, biochemical, electrophysiological, and behavioral techniques on wild-type and mutant mice to determine the effect of CaMKII nitrosylation on synaptic plasticity and determine if hypo-nitrosylation underlies cognitive impairment seen in aging. Notably, this project utilizes intrabodies, which allow for simultaneous imaging of multiple endogenous proteins without the normal confounds seen in protein overexpression experiments, to live-monitor endogenous CaMKII targeting and an unpublished mouse line, CaMKIIΔSNO. Further, this project will provide a comprehensive investigation of the role of CaMKII nitrosylation in synaptic plasticity and aging, as it begins at the molecular level and proceeds through to functional behavioral outputs. The results from this project will not only elucidate the cellular and molecular role of CaMKII nitrosylation in synaptic plasticity, but also provide insights into how hypo- nitrosylation may underlie the cognitive impairment seen in aging, thus leading to a better understanding of synaptic plasticity and potential therapeutic interventions for aging populations.