Mapping protein interactions of sodium channel NaV1.7 using epitope-tagged gene targeted mice

The voltage-gated sodium channel Na V 1.7 plays a critical role in pain pathways. Besides action potential propagation, Na V 1.7 regulates neurotransmitter release, integrates depolarizing inputs over long periods and regulates transcription. In order to better understand these functions, we generated an epitope-tagged Na V 1.7 mouse that showed normal pain behavior. Analysis of Na V 1.7 complexes affinity-purified under native conditions by mass spectrometry revealed 267 Na V 1.7 associated proteins including known interactors, such as the sodium channel β3 subunit (Scn3b) and collapsin response mediator protein (Crmp2), and novel interactors. Selected novel Na V 1.7 protein interactors membrane-trafficking protein synapototagmin-2 (Syt2), G protein-regulated inducer of neurite outgrowth 1 (Gprin1), L-type amino acid transporter 1 (Lat1) and transmembrane P24 trafficking protein 10 (Tmed10) together with Scn3b and Crmp2 were validated using co-immunoprecipitation and functional assays. The information provided with this physiologically normal epitope-tagged mouse should provide useful insights into the pain mechanisms associated with Na V 1.7 channel function.