Gene Control of Synaptic Transmission

突触传递的基因控制

• 批准号: 08044245
• 负责人: KIDOKORO Yoshiaki
• 金额: $ 4.35万
• 依托单位: Gunma University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for international Scientific Research
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08044245/
• 关键词: csp mutants; Drosophila melanogaster; presynaptic Ca^<2+>channel; synaptic transmission; shibire mutant; synaptic vesicle iecycling; cysteine-string protein; Ca^<2+>influx; Ca^<2+>imaging; CSP変異株; グルタミン酸受容体分布; シナプス形成; 受容体集積

Cysteine string proteins (csps) are synaptic proteins that are important for evoked neurotransmitter release at Drosophila neuromuscular junctions. In a temperature-sensitive csp mutant it has been reported that nerve-evoked synaptic potentials are not observed in non-permissive temperature while spontaneous synaptic potentials remain. When csp proteins were expressed together with Ca^<2+>channel proteins in Xenopus oocytes Ca^<2+>inward currents were greater than when Ca^<2+>channel proteins alone were expressed. Thus it has been speculated that csp proteins are interacting Ca^<2+>channels for Ca^<2+>influx at the nerve terminal. In this project we measured changes of Ca^<2+>concentration in the presynaptic nerve terminal during action potentials in 3rd instar larvae using a dye, Ca^<2+>Crimson AM.Upon repetitive nerve stimulation in csp mutant larvae Ca^<2+>signals were clearly detected at rcom temperature. However, at non-permissive temperature (32ﾟC) no signals were observed upon identical stimulation. In wild-type larvae Ca^<2+>signals were detected even at 32ﾟC.Therefore, we suggest that the normal functin of csp proteins is necessary for Ca^<2+>influx. Since csp proteins are on the synaptic vesicle membrane, synaptic vesicles have to be in the right position at the time of action potentia1 arrival. If there are no synaptic vesicles we expect no Ca^<2+>influx. To test this hypothesis we used another mutant, shibire, in which vesicle recycling is impaired at non-permissive temperature. In this mutant it has been shown that vesicles are depleted and no nerve evoked synaptic potentials are observed when the nerve was stimulated repetitively at non-permissive temperature. In this depleted condition no Ca^<2+>signals were observed at the nerve terminal upon repetitive nerve-stimulation. Thus, using two completely independent Drosophila mutants, we demonstrated that synaptic vesicles and csps are vital for the function of presynaptic Ca^<2+>channels.

半胱氨酸弦蛋白（csps）是一种突触蛋白，在果蝇神经肌肉连接处诱发神经递质释放中起重要作用。据报道，在温度敏感的csp突变体中，在非允许温度下未观察到神经诱发突触电位，而自发突触电位仍然存在。当csp蛋白与Ca^<2+>通道蛋白共同表达时，Ca^<2+>通道蛋白的内向电流大于单独表达Ca^<2+>通道蛋白时的内向电流。因此，我们推测csp蛋白与Ca^<2+>通道相互作用，导致Ca^<2+>在神经末梢内流。在本项目中，我们使用Ca^<2+>Crimson AM染料测量了3龄幼虫动作电位期间突触前神经末梢Ca^<2+>浓度的变化。csp突变体反复神经刺激后，在室温下可明显检测到Ca^<2+>信号。然而，在非允许温度（32℃）下，相同的刺激没有观察到信号。在32℃的温度下，野生型幼虫仍能检测到Ca^<2+>信号。因此，我们认为csp蛋白的正常功能是Ca^<2+>内流所必需的。由于csp蛋白位于突触囊泡膜上，所以当动作电位到达时，突触囊泡必须处于正确的位置。如果没有突触囊泡，我们预计不会有Ca^<2+>内流。为了验证这一假设，我们使用了另一种突变体shibiire，在非允许温度下，囊泡循环受损。在这个突变体中，当神经在不允许的温度下被反复刺激时，囊泡被耗尽，没有神经诱发的突触电位被观察到。在这种衰竭状态下，重复神经刺激后神经末梢未观察到Ca^<2+>信号。因此，使用两个完全独立的果蝇突变体，我们证明突触囊泡和csps对突触前Ca^<2+>通道的功能至关重要。

项目成果

Kuromi,H.,Kidokoro,Y.: "Two distinct pools of synaptic vesicles in single presynaptic boutons revealed in temperature-sensitive Drosophila mutant." Neuron. (in press). (1998)

Kuromi,H.,Kidokoro,Y.：“在温度敏感的果蝇突变体中发现了单个突触前布顿中两个不同的突触小泡池。”

Umbach,UA,Saitoe,M.,Kidokoro,Y.,Gundersen,C.: "Attenuated influx of calcium ions at nerve endings of csp and shibire mutant Drosophila" Journal of Neuroscience 18. (in press). (1998)

Umbach，UA，Saitoe，M.，Kidokoro，Y.，Gundersen，C.：“csp 和 shibire 突变体果蝇神经末梢的钙离子流入减弱”《神经科学杂志》18 期（出版中）。

Saitoe,M.,Tanaka,S.,Takata,K.,Kidokoro,Y.: "Neural activity affects distribution of glutamate receptors during neuromuscular junction formation in Drosophila embryos." Developmental Biology. (in press).

Saitoe，M.，Tanaka，S.，Takata，K.，Kidokoro，Y.：“神经活动影响果蝇胚胎神经肌肉接头形成过程中谷氨酸受体的分布。”

Ciani,S.,Nishikawa,K.,Kidokoro,Y.: "Permeation of organic cations and ammonium through the glutamate receptor channel in Drosophila larvalmuscle." Japanese Journal of Physiology. (in press).

Ciani，S.，Nishikawa，K.，Kidokoro，Y.：“有机阳离子和铵通过果蝇幼虫肌肉中谷氨酸受体通道的渗透。”

Deitcher,DL, Ueda,A., Kidokoro,Y., et al.: "Distinct requirements for evoked and spontaneous release of neurotransmitter are revealed by mutations in the Drosophila gene neuronal-synaptobrevin" Journal of Neuroscience. 18. 2028-2039 (1998)

Deitcher,DL、Ueda,A.、Kidokoro,Y. 等人：“果蝇基因神经元突触短蛋白的突变揭示了神经递质诱发和自发释放的不同要求”《神经科学杂志》。