Regulation of actin dynamics by annexin 2
Regulation of actin dynamics by annexin 2
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DOI：
10.1038/sj.emboj.7601078
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发表时间：
2006-05-03
期刊：
影响因子：
11.4
通讯作者：
Moss, Stephen E.
中科院分区：
文献类型：
--
作者：
Hayes, Matthew J.;Shao, Dongmin;Moss, Stephen E.
膜联蛋白2是一种普遍存在的钙离子结合蛋白，是肌动蛋白依赖的囊泡运输所必需的。在这里，我们表明，在自发运动的细胞膜联蛋白2是集中在动态肌动蛋白丰富的突起，并使用siRNA的膜联蛋白2的耗尽导致应力纤维的积累和膨胀和伸缩活动的损失。共表达膜联蛋白2-CFP和肌动蛋白-YFP的细胞在整个细胞质和膜皱褶和突起中表现出Ca 2+依赖的荧光共振能量转移，表明膜联蛋白2可能直接与肌动蛋白相互作用。这一观点得到了生物化学研究的支持，我们发现膜联蛋白2以剂量依赖性方式降低肌动蛋白单体的聚合速率。通过测量肌动蛋白聚合率的存在下，倒钩端和尖端帽，我们进一步证明，膜联蛋白2特异性抑制丝伸长的倒钩端。这些结果表明，膜联蛋白2在维持动态膜相关肌动蛋白细胞骨架的可塑性方面具有重要作用，并且其在这种情况下的活性可以至少部分地通过与聚合和单体肌动蛋白的直接相互作用来解释。
Annexin 2 is a ubiquitous Ca2+-binding protein that is essential for actin-dependent vesicle transport. Here, we show that in spontaneously motile cells annexin 2 is concentrated in dynamic actin-rich protrusions, and that depletion of annexin 2 using siRNA leads to the accumulation of stress fibres and loss of protrusive and retractile activity. Cells co-expressing annexin 2-CFP and actin-YFP exhibit Ca2+-dependent fluorescense resonance energy transfer throughout the cytoplasm and in membrane ruffles and protrusions, suggesting that annexin 2 may directly interact with actin. This notion was supported by biochemical studies, in which we show that annexin 2 reduces the polymerisation rate of actin monomers in a dose-dependent manner. By measuring actin polymerisation rates in the presence of barbed-end and pointed-end cappers, we further demonstrate that annexin 2 specifically inhibits filament elongation at the barbed ends. These results show that annexin 2 has an essential role in maintaining the plasticity of the dynamic membrane-associated actin cytoskeleton, and that its activity in this context may be at least partly explained through direct interactions with polymerised and monomeric actin.