LIM Kinase Has a Dual Role in Regulating Lamellipodium Extension by Decelerating the Rate of Actin Retrograde Flow and the Rate of Actin Polymerization
LIM Kinase Has a Dual Role in Regulating Lamellipodium Extension by Decelerating the Rate of Actin Retrograde Flow and the Rate of Actin Polymerization
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DOI：
10.1074/jbc.m111.259135
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发表时间：
2011-10-21
影响因子：
4.8
通讯作者：
Mizuno, Kensaku
中科院分区：
文献类型：
--
作者：
Ohashi, Kazumasa;Fujiwara, Sachiko;Mizuno, Kensaku
板状伪足的延伸对于细胞的迁移和扩展至关重要。板状伪足延伸的速率由肌动蛋白聚合速率和肌动蛋白逆行流动速率之间的平衡决定。LIM激酶1（LIMK 1）通过磷酸化和失活cofilin（一种肌动蛋白解聚蛋白）来调节肌动蛋白动力学。我们研究了LIMK 1在片状伪足扩展中的作用，通过测量肌动蛋白聚合，肌动蛋白逆行流动和片状伪足扩展的速率，使用延时成像的荧光恢复后光漂白。在表达活性Rac的N1 E-115细胞的非延伸板状伪足中，LIMK 1表达减速，LIMK 1敲低加速肌动蛋白逆行流动。在神经调节蛋白刺激的MCF-7细胞的延伸板状伪足中，LIMK 1敲低加速了肌动蛋白聚合的速率和肌动蛋白逆行流动的速率，但对逆行流动的加速作用大于对聚合的作用，从而导致板状伪足延伸的速率降低。这些结果表明，LIMK 1具有双重作用，调节板状伪足延伸，通过减速肌动蛋白逆行流动和聚合，并在MCF-7细胞内源性LIMK 1有助于板状伪足延伸，通过减速肌动蛋白逆行流动比减速肌动蛋白聚合更有效。
Lamellipodium extension is crucial for cell migration and spreading. The rate of lamellipodium extension is determined by the balance between the rate of actin polymerization and the rate of actin retrograde flow. LIM kinase 1 (LIMK1) regulates actin dynamics by phosphorylating and inactivating cofilin, an actin-depolymerizing protein. We examined the role of LIMK1 in lamellipodium extension by measuring the rates of actin polymerization, actin retrograde flow, and lamellipodium extension using time-lapse imaging of fluorescence recovery after photobleaching. In the non-extending lamellipodia of active Rac-expressing N1E-115 cells, LIMK1 expression decelerated and LIMK1 knockdown accelerated actin retrograde flow. In the extending lamellipodia of neuregulin-stimulated MCF-7 cells, LIMK1 knockdown accelerated both the rate of actin polymerization and the rate of actin retrograde flow, but the accelerating effect on retrograde flow was greater than the effect on polymerization, thus resulting in a decreased rate of lamellipodium extension. These results indicate that LIMK1 has a dual role in regulating lamellipodium extension by decelerating actin retrograde flow and polymerization, and in MCF-7 cells endogenous LIMK1 contributes to lamellipodium extension by decelerating actin retrograde flow more effectively than decelerating actin polymerization.