Mechanism of action of two insect toxins huwentoxin-Ⅲ and hainantoxin-Ⅵ on voltage-gated sodium channels  

作　　者：Rui-lan WANG Su YI Song-ping LIANG 

机构地区：[1]Department of Food Science Guangdong Food and Drug Vocational College, Guangzhou 510520, China [2]School of Life Science, Hunan Science and Technology University, Xiangtan 411201, China [3]Key Laboratory of Protein Chemistry and Developmental Biology of Ministry of Education, College of Life Science, Hunan Normal University, Changsha 410081, China

出　　处：《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》2010年第6期451-457,共7页浙江大学学报（英文版）B辑（生物医学与生物技术）

基　　金：supported by the National Natural Science Foundation of China (No.30500146);the National Basic Research Program (973) of China (No.2006CB708508)

摘　　要：Selenocosmia huwena and Selenocosmia hainana are two tarantula species found in southern China.Their venoms contain abundant peptide toxins.Two new neurotoxic peptides,huwentoxin-Ⅲ(HWTX-Ⅲ) and hainantoxin-VI(HNTX-VI),were obtained from the venom using ion-exchange chromatography and reverse-phase high performance liquid chromatography(RP-HPLC).The mechanism of action of HWTX-Ⅲ and HNTX-VI on insect neuronal voltage-gated sodium channels(VGSCs) was studied via whole-cell patch clamp techniques.In a fashion similar to δ-atracotoxins,HNTX-VI can induce a slowdown of current inactivation of the VGSC and reduction in the peak of Na+ current in cockroach dorsal unpaired median(DUM) neurons.Meanwhile,10 μmol/L HNTX-IV caused a positive shift of steady-state inactivation of sodium channel.HWTX-ⅡI inhibited VGSCs on DUM neurons(concentration of toxin at half-maximal inhibition(IC50)≈1.106 μmol/L) in a way much similar to tetrodotoxin(TTX).HWTX-Ⅲ had no effect on the kinetics of activation and inactivation.The shift in the steady-state inactivation curve was distinct from other depressant spider toxins.The diverse effect and the mechanism of action of the two insect toxins illustrate the diverse biological activities of spider toxins and provide a fresh theoretical foundation to design and develop novel insecticides.Selenocosmia huwena and Selenocosmia hainana are two tarantula species found in southern China.Their venoms contain abundant peptide toxins.Two new neurotoxic peptides,huwentoxin-Ⅲ（HWTX-Ⅲ） and hainantoxin-VI（HNTX-VI）,were obtained from the venom using ion-exchange chromatography and reverse-phase high performance liquid chromatography（RP-HPLC）.The mechanism of action of HWTX-Ⅲ and HNTX-VI on insect neuronal voltage-gated sodium channels（VGSCs） was studied via whole-cell patch clamp techniques.In a fashion similar to δ-atracotoxins,HNTX-VI can induce a slowdown of current inactivation of the VGSC and reduction in the peak of Na^＋ current in cockroach dorsal unpaired median（DUM） neurons.Meanwhile,10 μmol/L HNTX-IV caused a positive shift of steady-state inactivation of sodium channel.HWTX-ⅡI inhibited VGSCs on DUM neurons（concentration of toxin at half-maximal inhibition（IC50）≈1.106 μmol/L） in a way much similar to tetrodotoxin（TTX）.HWTX-Ⅲ had no effect on the kinetics of activation and inactivation.The shift in the steady-state inactivation curve was distinct from other depressant spider toxins.The diverse effect and the mechanism of action of the two insect toxins illustrate the diverse biological activities of spider toxins and provide a fresh theoretical foundation to design and develop novel insecticides.

关 键 词：Insect neurotoxin Dorsal unpaired median neurons Sodium channel Whole-cell patch clamp technique 

分 类 号：Q965.9[生物学—昆虫学]