Nitric Oxide is unique second messenger in that it can directly alter the proteins responsible for dynamic changes to spine morphology. Nitric Oxide signalling may regulate synaptic plasticity by altering the density and morphology of spines through a process called S-nitrosylation. While it is estimated that 50% of proteins in the brain are altered by S-nitrosylation, a comprehensive analysis of the role it plays in synaptic plasticity has never been performed.

Project 1: The Role of Nitric Oxide (NO) in spine plasticity

Opening of the NMDA-type ion channel (known as the NMDA receptor) by the neurotransmitter glutamate results in production of Nitric Oxide. Subsequent S-Nitrosylation events alter the function of near-by proteins and as a result the dynamic properties of the spines they inhabit. Using powerful mouse genetics we aim to control the level of nitric oxide synthesized in spines by altering the genetic composition of the NMDA receptor and thus their ability to open and close. Using live imaging microscopy techniques coupled with fluorescent probes, we will monitor the flux of ions through the NMDA receptor as well the amount nitric oxide subsequently produced in cultured brain slices and isolated neurons. This will allow us to determine how the level of Nitric Oxide correlates with dynamic changes to spine morphology. We will then monitor what proteins are S-nitrosylated by Nitric Oxide under conditions of spine growth, spine stabilization and spine retraction. This will form the basis of a novel molecular pathway that underlies the processes of synaptic plasticity.