Pointed-end capping by tropomodulin3 negatively regulates endothelial cell motility.
Pointed-end capping by tropomodulin3 negatively regulates endothelial cell motility.
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DOI：
10.1083/jcb.200209057
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发表时间：
2003-04-28
期刊：
影响因子：
--
通讯作者：
Fowler VM
中科院分区：
文献类型：
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作者：
Fischer RS;Fritz-Six KL;Fowler VM
肌动蛋白细丝尖端动力学被认为在细胞运动中起关键作用，但对这一过程的调控仍然知之甚少。在这里，我们描述了一种以前没有特征的Tmod亚型，Tmod3，它在人体组织中广泛表达，并存在于人微血管内皮细胞(HMEC-1)中。Tmod3的数量足以覆盖肌动蛋白细丝的尖端，定位于HMEC-1细胞中的肌动蛋白细丝结构，并出现丰富的前沿褶皱和片脂。瞬时过表达GFP-Tmod3导致细胞形态去极化和细胞活力降低。Tmod3增加五倍会导致细胞中自由尖端的等量减少。出乎意料的是，在片状脂体中也观察到F-肌动蛋白、游离带刺末端和肌动蛋白相关蛋白2/3(Arp2/3)复合体的相对数量减少。相反，通过RNA干扰降低Tmod3的表达导致细胞平均迁移速度更快，以及板脂肌动蛋白细丝中自由尖端和带刺末端的增加。这些数据共同证明了Tmod3对肌动蛋白细丝尖端的封顶抑制了细胞的迁移，并揭示了一种新的调控片状脂体中肌动蛋白细丝的机制。
Actin filament pointed-end dynamics are thought to play a critical role in cell motility, yet regulation of this process remains poorly understood. We describe here a previously uncharacterized tropomodulin (Tmod) isoform, Tmod3, which is widely expressed in human tissues and is present in human microvascular endothelial cells (HMEC-1). Tmod3 is present in sufficient quantity to cap pointed ends of actin filaments, localizes to actin filament structures in HMEC-1 cells, and appears enriched in leading edge ruffles and lamellipodia. Transient overexpression of GFP–Tmod3 leads to a depolarized cell morphology and decreased cell motility. A fivefold increase in Tmod3 results in an equivalent decrease in free pointed ends in the cells. Unexpectedly, a decrease in the relative amounts of F-actin, free barbed ends, and actin-related protein 2/3 (Arp2/3) complex in lamellipodia are also observed. Conversely, decreased expression of Tmod3 by RNA interference leads to faster average cell migration, along with increases in free pointed and barbed ends in lamellipodial actin filaments. These data collectively demonstrate that capping of actin filament pointed ends by Tmod3 inhibits cell migration and reveal a novel control mechanism for regulation of actin filaments in lamellipodia.