| 其他摘要 | In China, the centipede has been used for thousands of years as a traditional Chinese medicine to treat disorders, such as stroke-induced hemiplegia, apoplexy, epilepsy, tetanus, whooping cough, tuberculosis, scald burns, and pyocutaneous disease. Despite their abundance and oftenpainful encounters with humans, little is known about the composition and function of centipede venom. Nav1.6 channel plays a key role in neuropathicpain, but it was rarely reported as a target for screening of analgesic drugs. Currently, we isolated a peptide toxin from Scolopendra subspinipes mutilans venom, it can inhibit the tetrodotoxin-sensitive (TTX-S) sodium channels in rat dorsal root ganglion (DRG), further research shows that the it can selectively inhibit Nav1.6 channels, and has weak or no activity to other sodium channel subtypes. Firstly, a polypeptide named as μ-SLPTX-Ssm4a was purified from from Scolopendra subspinipes mutilans venoms by gel filtration and RP-HPLC and Edman degradation method was used for the determination of its N-terminal amino acid sequence. Secondly, according to the N-terminal sequence, cDNA sequence encoding the precursor of μ-SLPTX-Ssm4a was cloned from a cDNA library of Scolopendra subspinipes mutilans venom gland. The mature peptide was composed of 50 amino acid residues with a molecular mass of 5532.4 Da and contained three pairs of disulfide bonds. Finally, linear peptide of μ-SLPTX-Ssm4a was synthesized using a solid-phase chemical approach with Fmoc-protected amino acids. It was refolded by glutathione oxidation and was subjected to test its biological functions. μ -SLPTX-Ssm4a selectively inhibited Nav1.6 channels, the IC50 was 0.46 μM, and also had inhibition on Nav1.7 channel at high concentrations, the IC50 was 10.7 μM. Several animal models of persistent inflammatory and neuropathicpain showedμ-SLPTX-Ssm4a has a strong analgesic function in acetic acid-induced writhing test, tail-flick test, the formalin-induced paw licking and cold plate test, but the analgesic effect of morphine was significantly better. This study establishes Nav1.6 channel could be a target for screening of analgesic drugs and u-SPTX-Ssm4a may be a promising lead molecule for the development of novel analgesics targeting Nav1.6 channel. |
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