Project Summary/Abstract Validation of a novel pain target is a critical step toward the development of new nonaddictive, therapeutic agents for chronic pain management, which is an urgent unmet medical need to be tackled by NIH's Helping to End Addiction Long-term (HEAL) initiative. We recently discovered that nerve injury induced concurrent upregulation of the calcium channel alpha-2-delta-1 subunit (CaV21) and thrombospondin-4 (TSP4) proteins in sensory and spinal cord neurons that contributes to neuropathic pain development by inducing aberrant excitatory synapse formation and sensitization of neurotransmission in spinal cord. We have identified a target side in the TSP4 that plays a critical role in mediating these pathological changes upon interaction with the CaV21 protein. To validate this novel target site for development of nonaddictive pain medications, we plan to use multidisciplinary approaches, involving three independent laboratories, to investigate if blocking and genetic deletion of the target site can block/prevent (Aim 1) pain state development; (Aim 2) aberrant excitatory synapse formation; (Am 3) spinal cord neuron sensitization after injury in two neuropathic pain models. Successful completion of this project will provide important information for further development of specific therapeutic medications for neuropathic pain management as inspired and supported by the HEAL initiative.

PROJECT NARRATIVE We plan to validate a new target for further development of target-specific, nonaddictive neuropathic pain medications in response to NIH's Helping to End Addiction Long-term (HEAL) initiative. We recently discovered that peripheral nerve injury induced concurrent dysregulation of the calcium channel alpha-2-delta-1 subunit (CaV21) and thrombospondin-4 (TSP4) proteins in dorsal root ganglia and spinal cord that contributes to neuropathic pain development by inducing aberrant excitatory synapse formation and pain-signal transmitting neuron sensitization. We have identified a target side in the TSP4 that plays a critical role in mediating these pathological changes upon interaction with the CaV21 protein. In this project, we plan to validate the role of this target site in mediating (1) pain state development in two neuropathic pain models; (2) aberrant excitatory synapse formation in vitro and in two neuropathic pain models; (3) spinal cord neuron sensitization after injury in two neuropathic pain models. Successful validation of this novel nonaddictive pain target will provide important information for further development of specific therapeutic pain medications as inspired and supported by the HEAL initiative.