Tachykinins Processing is Significantly Impaired in PC1 and PC2 Mutant Mouse Spinal Cord S9 Fractions

摘要

Substance P (SP) play a central role in nociceptive transmission and it is an agonist of theNeurokinin-1 receptor located in the lamina I of the spinal cord. SP is a major proteolytic productof the protachykinin-1 primarily synthesized in neurons. Proprotein convertases (PCs) areextensively expressed in the central nervous system (CNS) and specifically cleave at C-terminalof either a pair of basic amino acids, or a single basic residue. The proteolysis control ofendogenous protachykinins has a profound impact on pain perception and the role of PCs remainunclear. The objective of this study was to decipher the role of PC1 and PC2 in the proteolysissurrogate protachykinins (i.e. Tachykinin 20-68 and Tachykinin 58-78) using cellular fractions ofspinal cords from wild type (WT), PC1-/+ and PC2-/+ animals and mass spectrometry. Full-lengthTachykinin 20-68 and Tachykinin 58-78 was incubated for 30 minutes in WT, PC1-/+ and PC2-/+mouse spinal cord S9 fractions and specific C-terminal peptide fragments were identified andquantified by mass spectrometry. The results clearly demonstrate that both PC1 and PC2 mediatethe formation of SP and Tachykinin 58-71, an important SP precursor, with over 50% reductionof the rate of formation in mutant PC 1 and PC2 mouse S9 spinal cord fractions. The resultsobtained revealed that PC1 and PC2 are involved in the C-terminal processing of protachykininpeptides and suggest a major role in the maturation of the protachykinin-1 protein.