Developmental Cell：膜融合的启动步骤
细胞里要进行任何的生理活动，都得靠着来自不同地方的成份分子，而这些成份分子的输送，就得要透过细胞膜所构成的胞器，来进行特定分子的输送，因此胞器间的膜融合 (Membrane Fusion)过程，就成了细胞代谢的一个重要的过程，而相关的研究也曾证实，膜融合过程的异常，往往是许多疾病发生的原因之一，甚至像是爱兹病毒的感染，都和胞膜的活动，有直接而且密切的关系，由此可见胞膜间的活动在细胞的生理上 扮演这十分重要的地位。
这次由布朗大学生物学家 Gary Wessel博士所领导的研究小组，就尝试着利用海胆 (urchin)的卵子(eggs) 细胞，来分析膜融合的瞬间，据了解Wessel 博士所领导的研究团队，长期以来就卵子受精的过程，来分析胞膜融合的过程，就先前该团队的研究资料发现，卵子受精发生膜融合的过程，几乎只有百万分之一秒，精子细胞进入卵子细胞后，原本卵细胞膜上成百上千个胞膜所形成的囊泡，会瞬间的释放出内含物，科学家怀疑这瞬间进行胞膜融合的过程，必然受到了特定蛋白讯号的调控。
结果研究人员利用到荧光染剂，搭配着高分辨率的显微镜，发现这些胞膜融合过程中，存在着半融合 (hemifusion)的启动阶段，而这个阶段可长可短，短可以只有只有几小时，长则可达数月之久，不过它却是任何膜融合过程的起点。
研究人员把这个发现，发表在最新一期发育细胞 (Developmental Cell)期刊上，并表示下一个阶段的研究，就是如何的把这一个发现，应用到药物的输送上。
(资料来源 : Bio.com)
英文原文链接:
原始出处:
Developmental Cell, Vol 12, 653-659, 09 April 2007
Short Article
Membrane Hemifusion Is a Stable Intermediate of Exocytosis
Julian L. Wong,1 Dennis E. Koppel,2 Ann E. Cowan,2 and Gary M. Wessel1,
1 Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, Providence, RI 02912, USA
2 Department of Molecular, Microbial, and Structural Biology and Richard D. Berlin Center for Cell Analysis and Modeling, University of Connecticut Health Center, Farmington, CT 06032, USA
Corresponding author
Gary M. Wessel
rhet@brown.edu
Summary
Membrane fusion during exocytosis requires that two initially distinct bilayers pass through a hemifused intermediate in which the proximal monolayers are shared. Passage through this intermediate is an essential step in the process of secretion, but is difficult to observe directly in vivo. Here we study membrane fusion in the sea urchin egg, in which thousands of homogeneous cortical granules are associated with the plasma membrane prior to fertilization. Using fluorescence redistribution after photobleaching, we find that these granules are stably hemifused to the plasma membrane, sharing a cytoplasmic-facing monolayer. Furthermore, we find that the proteins implicated in the fusion process—the vesicle-associated proteins VAMP/synaptobrevin, synaptotagmin, and Rab3—are each immobile within the granule membrane. Thus, these secretory granules are tethered to their target plasma membrane by a static, catalytic fusion complex that maintains a hemifused membrane intermediate.
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