Alpha-latrotoxin Triggers Extracellular Ca^(2+)-dependent Exocytosis and Sensitizes Fusion Machinery in Endocrine Cells  

作　　者：Zhi-Tao HU Ping ZHAO Jie LIU Zheng-Xing WU Tao XU 

机构地区：[1]School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China [2]National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China

出　　处：《Acta Biochimica et Biophysica Sinica》2006年第1期8-14,共7页生物化学与生物物理学报（英文版）

基　　金：This work was supported by the grants from the National Natural Science Foundation of China （30025023, 3000062, 30130230 and 30370647）;the Major State Basic Research Program of China （G1999054000 and 2004CB720000）;the Chinese Academy of Sciences Project （KSCX2-SW-224）;the National High Technology Research and Development Program of China （2002AA214061）.

摘　　要：α-Latrotoxin from the venom of black widow spider induces and augments neurotransmitter and hormone release by way of extracellular Ca^2＋ influx and cellular signal transduction pathways. By using whole cell current and capacitance recording, the photolysis of caged Ca^2＋, and Ca^2＋ microfluorometry and amperometry, we investigated the stimulating effect and mechanism of ot-latrotoxin on exocytosis in rat pancreatic β cells, LβT2 cells and latrophilin plasmid-transfected INS-1 cells. Our data indicated that： （1） α- latrotoxin increased cytosolic Ca^2＋ concentration through the formation of cation-permitting pores and subsequent Ca^2＋ influx with the presence of extracellular Ca^2＋; （2） α-latrotoxin stimulated exocytosis in normal bath solution and its stimulating effect on secretion was eradicated in Ca^2＋-free bath solution; and （3） α- latrotoxin sensitized the molecular machinery of fusion through activation of protein kinase C and increased the response of cells to Ca^2＋ photolysed by a flash of ultraviolet light. In summary, α-latrotoxin induced exocytosis by way of Ca^2＋ influx and accelerated vesicle fusion by the sensitization of fusion machinery.α-Latrotoxin from the venom of black widow spider induces and augments neurotransmitter and hormone release by way of extracellular Ca^2＋ influx and cellular signal transduction pathways. By using whole cell current and capacitance recording, the photolysis of caged Ca^2＋, and Ca^2＋ microfluorometry and amperometry, we investigated the stimulating effect and mechanism of ot-latrotoxin on exocytosis in rat pancreatic β cells, LβT2 cells and latrophilin plasmid-transfected INS-1 cells. Our data indicated that： （1） α- latrotoxin increased cytosolic Ca^2＋ concentration through the formation of cation-permitting pores and subsequent Ca^2＋ influx with the presence of extracellular Ca^2＋; （2） α-latrotoxin stimulated exocytosis in normal bath solution and its stimulating effect on secretion was eradicated in Ca^2＋-free bath solution; and （3） α- latrotoxin sensitized the molecular machinery of fusion through activation of protein kinase C and increased the response of cells to Ca^2＋ photolysed by a flash of ultraviolet light. In summary, α-latrotoxin induced exocytosis by way of Ca^2＋ influx and accelerated vesicle fusion by the sensitization of fusion machinery.

关 键 词：α-latrotoxin EXOCYTOSIS calcium Ca^2＋-sensitivity of fusion protein kinase C （PKC） capacitance measurement AMPEROMETRY 

分 类 号：Q50[生物学—生物化学]