β-G spectrin的显性基因突变破坏致密核心囊泡的分泌(英文)  

DCVs Exocytosis is Damaged in The Dominant Allele of β-G Spectrin Mutant in C. elegans

作　　者：酒亚明[1] 于俊伟[1] 林显光[1] 章永登[1] 王燕[1] 张蓉颖[1] 吴政星[1] 

机构地区：[1]华中科技大学分子生物物理教育部重点实验室、生物物理与生物化学研究所,武汉430074

出　　处：《生物化学与生物物理进展》2009年第12期1589-1596,共8页Progress In Biochemistry and Biophysics

基　　金：supported by a grant from The National Natural Science Foundation of China(30630020,30670502,30700162)~~

摘　　要：β-spectrin是细胞膜骨架的重要组成蛋白,其主要分布于质膜的基底部位.在线虫中只有一个编码β-spectrin亚基(β-G)的基因即unc-70.除了稳定质膜,使细胞产生极性等功能外,有报道称它还参与细胞分泌的调节过程.研究发现,在线虫中β-G spectrin的显性基因突变体unc-70(n493)会导致DCVs的分泌缺陷.在活体下,unc-70(n493)突变虫系的神经多肽分泌显著下降.此外,在主要分泌致密核心囊泡的ALA神经元内,钙光解释放促发的快相分泌也比野生型减少.运用TIRFM成像技术,观察在unc-70缺失的情况下ALA神经元内DCVs的锚定过程,结果显示质膜附近囊泡的密度没有显著变化,但囊泡在细胞膜附近停留的时程变短,表明囊泡锚定受到阻碍.为了验证unc-70是否还同时参与调控突触囊泡的分泌过程,运用电生理记录活体线虫神经肌肉接头的方法,发现自发的突触后电流mEPSCs没有明显变化.上述试验结果表明,β-G spectrin的显性基因突变虫系能够影响致密核心囊泡的分泌过程,其机制可能是影响了囊泡的锚定过程.β-Spectrin is a major component of the membrane skeleton, a structure found at the plasma membrane of most animal cells.C. elegans genome encodes only one gene of β-spectrin subunit （β-G）, uric-70. Besides stabilizing plasma membranes and generating cell polarity, β-spectrin is also reported to mediate the secretary pathway. In the present studies, it was demonstrated that UNC-70 is involved in the dense core vesicle （DCV） exocytosis in C. elegans neurons. It was found that uric-70 dominant allele mutants exhibited reduced peptide release in vivo. In IDA-1 （related to islet cell diabetes autoantigen） labeled ALA neurons, which serve as a good model for studying DCV exoeytosis, mutant of β-spectrin leads to visible reduction of the readily released pool （RRP） size. The analysis of vesicular docking by total internal reflection microscopy revealed that loss-of-function of uric-70 hindered the docking of DCVs in neurons. The electrophysiological experiments at the neuromuscular junctions excluded the possibility that the quantum size of acetylcholine in synaptic vesicles in neurous and postsynaptic response in muscle cells were affected. The above results provide evidences that β-spectrin is required for the exocytosis of DCVs and also possibly involved in the release ofneurotransmitter.

关 键 词：线虫 β-spectrin unc-70 致密核心囊泡 细胞分泌 

分 类 号：Q71[生物学—分子生物学] Q424