Proteomic analysis of isolated nerve terminals from NaV1.9 knockout mice reveals pathways relevant for pain perception.

Neuropathic pain substantially affects the mental and physical well-being of patients and magnifies the socio-economic burden on the healthcare system. It is important to understand the molecular mechanisms underlying chronic pain to effectively target it. To investigate peripheral mechanisms relevant to pain signalling, we isolated nerve terminals from mouse footpads of wild type and NaV1.9-deficient mice, which exhibit impaired pain sensation and chronification. The isolated peripheral terminals are functionally active and capable of endocytosis. They contain both pre- and postsynaptic proteins in samples from mice and humans. Components of the protein translational machinery and mitochondria are enriched in nerve terminals, and these components are altered in NaV1.9 deficient terminals. An unbiased proteomic analysis of nerve terminals from footpads of NaV1.9 knockout mice shows dysregulation of the mitogen-activated protein kinase and extracellular regulated kinase 1/2 pathways. Preliminary proteomic analysis reveals a strong similarity between mouse and human skin samples, highlighting the broad and translational value of our approach. Our findings uncover peripheral signalling mechanisms involved in nociception, paving the way for unprecedented translational approaches using human biomaterials in pain research.