OPC are migratory and proliferative and are characterised by expression of the large membrane glycoprotein NG2 which is down-regulated as the cells mature. To understand the function of the NG2 protein, we are identifying its binding partners. These include the PDZ-domain protein GRIP which also binds to AMPA-type glutamate receptors expressed by OPC and may position the AMPA receptors on the cells towards sites of neuronal glutamate release (see below). We have also identified the protein Syntenin which could link NG2 to the cytoskeleton, important for migration and axonal wrapping. Lastly, we have identified a binding partner which plays a role in regulating the induction of apoptosis.
We have recently generated a knockin mouse in which NG2+ cells in vivo express the enhanced yellow fluorescent protein (EYFP). In the homozygous state the cells express two copies of EYFP but are lacking NG2. We are using this mouse to analyse the properties of NG2 cells in development and in response to injury (e.g gene expression profile) and are also studying the knockout animals.