Deletion of Tac1 gene impact kinase phosphorylation involved in signaling pathways associated with pain

Pain in elderly persons is often not adequately treated, and current treatments may lead to poor outcomes. Therefore, new treatment strategies need to be developed based on a better understanding of the mechanisms underlying the development of chronic pain. Recent studies have shown that Tac1-/- mice display a significant decrease in nociceptive pain responses to moderate or intense stimuli but present no phenotypic changes following light or nonpainful stimuli. Moreover, the deletion of the Tac1 gene led to a deficit of opioid peptides, which are essential to endogenous pain control mechanisms. Thus, we investigated whether Tac1-/- mice show defective pain modulatory pathways by specifically profiling protein kinases in mice spinal cord using phosphoproteomics and bioinformatics. Protein phosphorylation is a key feature of the cellular regulatory mechanism, and phosphorylation status is related to the regulation and modulation of protein-protein binding. Bioinformatics analysis revealed that MAPK, tyrosine kinase, senescence, interleukin signaling, and TCR signaling are modulated in Tac1-/- mice. Interestingly, these processes are intimately linked with inflammatory responses leading to the release of cytokines and chemokines implicated in the interactions and communications between cells. They are key players involved in the initiation and persistence of pathologic pain. The absence of the Tac1 gene products may trigger a much wider cell response to compensate for the lack of important components of the nociceptive pain transmission system.