細胞骨架在突觸小泡運輸及突觸傳導所扮演的角色

Roles of Cytoskeleton in Synaptic Vesicle Trafficking and Synaptic Transmission

林靖(Chin Lin)

指導教授 ： 潘建源

國立臺灣大學/生命科學院/動物學研究所/碩士(2011年)

https://doi.org/10.6342/NTU.2011.01032

摘要

突觸小泡儲存神經傳導物質且被運送到軸突末端來參與突觸傳導。我們有興趣於細胞骨架調控小泡運動和突觸傳導。為了觀察小泡運動，將synaptophysin與光活化綠螢光蛋白(PA-GFP)結合，呈現在培養的皮質神經細胞Synaptophysin-PA-GFP位於亮點並且在神經細胞內緩慢移動，用CCD相機擷取亮點運動影像。為了觀察突觸傳導，重複地將紫外光照射在特定的區域來把MNI-caged-glutamate光解刺激目標細胞，使用fluo-2 MA呈現鈣離子的濃度變化。細胞骨架拮抗劑會使小泡移動速度從控制組的~0.7 μm/s下降到實驗組的~0.5 μm/s，並且使得目標細胞與相連鄰近細胞的鈣離子上升量減少。KIF17是驅動蛋白負責運送小泡，把其表現於神經細胞中會使小泡移動速度變快至~0.8 μm/s。Calmodulin與其突變蛋白會影響小泡運動和神經傳導，但是無顯著性差異。給予DHA則會使得目標細胞的鈣離子上升量增加。我們研究結果建議：減慢小泡運動會調控突觸傳導和突觸塑型。

關鍵字

細胞骨架 ； 突觸小泡 ； 突觸傳導 ； 神經傳導

並列摘要

Synaptic vesicles (SVs) store neurotransmitters and are transported to axon terminals for synaptic transmission. We are interested in how the vesicle movement and synaptic transmission are modulated by the cytoskeleton. To monitor the movement of SVs, synaptophysin was fused with photoactivatable green fluorescent protein (PA-GFP) and expressed in cultured cortical neurons. Synaptophysin-PA-GFP was located at some spots and moved slowly in neuritis captured by CCD camera. To monitor the synaptic transmission, UV flash was applied at designated regions repetitively to photolyze MNI-caged-glutamate to stimulate the target cell and the elevations in cytosolic Ca2+ concentration were visualized by fluo-2 MA. The vesicle movement was slowed down from ~0.7 μm/s in control group to ~0.5 μm/s in neurons treated with cytoskeleton antagonists; the Ca2+ responses in both target and connected neighbor cells were reduced as well. When KIF17, a kinesin for SV transportation, was expressed in neurons, the vesicle movement was significantly increased to ~0.8 μm/s. Calmodulin and its mutants interfered vesicle movement and neurotransmission but without significance. After being treated with DHA, the Ca2+ elevations in target cells were enhanced. These data suggest that slowing down SV movement may result in modulate the synaptic transmission and synaptic plasticity.

並列關鍵字

cytoskeleton ； synaptic vesicle ； synaptic transmission

參考文獻

Benfenati, F., Valtorta, F., Bähler, M., and Greengard, P. (1989). Synapsin I, a neuron-specific phosphoprotein interacting with small synaptic vesicles and F-actin. Cell Biology International Reports 13, 1007-1021.

Brose, N., Petrenko, A.G., Sudhof, T.C., and Jahn, R. (1992). Synaptotagmin: A calcium sensor on the synaptic vesicle surface. Science 256, 1021-1025.

Bubb, M.R., Spector, I., Beyer, B.B., and Fosen, K.M. (2000). Effects of jasplakinolide on the kinetics of actin polymerization. An explanation for certain in vivo observations. Journal of Biological Chemistry 275, 5163-5170.

Darios, F., Connell, E., and Davletov, B. (2007). Phospholipases and fatty acid signalling in exocytosis. Journal of Physiology 585, 699-704.

Dean, C., and Dresbach, T. (2006). Neuroligins and neurexins: Linking cell adhesion, synapse formation and cognitive function. Trends in Neurosciences 29, 21-29.