The neurofibromatosis type 1 gene product neurofibromin enhances cell motility by regulating actin filament dynamics via the Rho-ROCK-LIMK2-cofilin pathway
The neurofibromatosis type 1 gene product neurofibromin enhances cell motility by regulating actin filament dynamics via the Rho-ROCK-LIMK2-cofilin pathway
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DOI：
10.1074/jbc.m503707200
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发表时间：
2005-11-25
影响因子：
4.8
通讯作者：
Saya, H
中科院分区：
文献类型：
--
作者：
Ozawa, T;Araki, N;Saya, H
神经纤维蛋白是一种神经纤维瘤病1型(NF1)肿瘤抑制基因产物，其结构域具有GTP酶激活蛋白的功能，部分功能是RAS的负调控。NF1患者神经纤维蛋白表达的缺失与RAS活性升高和细胞增殖增加有关，从而易发生各种外周和中枢神经系统肿瘤。我们在这里展示了，使用小干扰RNA(SiRNA)技术，神经纤维素动态地调节肌动蛋白细胞骨架的重组，随后增强细胞运动和Matrigel基质中的总细胞聚集。NF1 siRNA可以诱导特征性的形态变化，如过度的肌动蛋白应激纤维形成，伴随着cofilin负磷酸化水平的升高，它通过解聚和切断肌动蛋白细丝来调节肌动蛋白细胞骨架的重组。我们发现，在神经纤维蛋白缺失的细胞中，cofilin的磷酸化水平升高是通过激活Rho-ROCK-LIMK2途径来促进的，该途径需要RAS激活，但不是通过Raf、磷脂酰肌醇3-激酶和Ralgef这三个主要的RAS介导的下游途径进行转导。此外，NF1-GTPase激活蛋白相关结构域的外源表达抑制了NF1 siRNA诱导的表型。神经纤维素被证明在调节细胞增殖和肌动蛋白细胞骨架重组的机制中发挥重要作用，而肌动蛋白细胞骨架重组影响细胞的运动和黏附。这些发现可能部分解释了NF1患者多发性神经纤维瘤的形成机制。
Neurofibromin is a neurofibromatosis type 1 (NF1) tumor suppressor gene product with a domain that acts as a GTPase-activating protein and functions, in part, as a negative regulator of Ras. Loss of neurofibromin expression in NF1 patients is associated with elevated Ras activity and increased cell proliferation, predisposing to a variety of tumors of the peripheral and central nervous systems. We show here, using the small interfering RNA ( siRNA) technique, that neurofibromin dynamically regulates actin cytoskeletal reorganization, followed by enhanced cell motility and gross cell aggregation in Matrigel matrix. NF1 siRNA induces characteristic morphological changes, such as excessive actin stress fiber formation, with elevated negative phosphorylation levels of cofilin, which regulates actin cytoskeletal reorganization by depolymerizing and severing actin filaments. Wefound that the elevated phosphorylation of cofilin in neurofibromin-depleted cells is promoted by activation of a Rho-ROCK-LIMK2 pathway, which requires Ras activation but is not transduced through three major Ras-mediated downstream pathways via Raf, phosphatidylinositol 3-kinase, and RalGEF. In addition, the exogenous expression of the NF1-GTPase-activating protein-related domain suppressed the NF1 siRNA-induced phenotypes. Neurofibromin was demonstrated to play a significant role in the machinery regulating cell proliferation and in actin cytoskeletal reorganization, which affects cell motility and adhesion. These findings may explain, in part, the mechanism of multiple neurofibroma formation in NF1 patients.