A Novel Protein Associated with Membrane-type 1 Matrix Metalloproteinase Binds p27kip1 and Regulates RhoA Activation, Actin Remodeling, and Matrigel Invasion
A Novel Protein Associated with Membrane-type 1 Matrix Metalloproteinase Binds p27kip1 and Regulates RhoA Activation, Actin Remodeling, and Matrigel Invasion
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DOI：
10.1074/jbc.m109.041400
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发表时间：
2009-10-02
影响因子：
4.8
通讯作者：
Seiki, Motoharu
中科院分区：
文献类型：
--
作者：
Hoshino, Daisuke;Tomari, Taizo;Seiki, Motoharu
膜型基质金属蛋白酶（MT1-MMP）在肿瘤细胞侵袭过程中起关键作用。MT1-MMP在细胞侵袭前的定位，如板足和侵入足，必须与肌动蛋白细胞骨架的重组协调调节。然而，对于这些与侵袭相关的肌动蛋白结构是如何在MT1-MMP所在的位点进行调控的，我们知之甚少。在分析mt1 - mmp相关蛋白时，我们发现了一个迄今为止未被表征的蛋白。这种蛋白，我们称之为p27RF-Rho，通过将RhoA从p27（kip1）的抑制中释放出来，从而增强RhoA的激活，从而调节肌动蛋白结构。P27 （kip1）是细胞核中一个众所周知的细胞周期调节因子。相比之下，细胞质p27（kip1）已被证明结合GDP-RhoA并抑制由鸟嘌呤核苷酸交换因子介导的GDP-GTP交换。p27RF-Rho结合p27（kip1）并阻止p27（kip1）与RhoA结合，从而释放后者进行活化。p27RF-Rho表达的下调使细胞对RhoA激活刺激产生抗性，而p27RF-Rho的过表达使细胞对这种刺激敏感。p27RF-Rho在侵袭性人肿瘤细胞系中呈点状分布。溶血磷脂酸刺激细胞诱导RhoA活化，并诱导p27RF-Rho定位灶内点状肌动蛋白结构的形成。一些点状肌动蛋白结构与MT1-MMP和接触共定位。p27RF-Rho的下调既可以阻止肌动蛋白重新分布到点状结构中，也可以阻止肿瘤细胞的侵袭。因此，p27RF-Rho是癌症治疗发展的一个新的潜在靶点。
Pericellular proteolysis by membrane-type 1 matrix metalloproteinase (MT1-MMP) plays a pivotal role in tumor cell invasion. Localization of MT1-MMP at the invasion front of cells, e. g. on lamellipodia and invadopodia, has to be regulated in coordination with reorganization of the actin cytoskeleton. However, little is known about how such invasion-related actin structures are regulated at the sites where MT1-MMP localizes. During analysis of MT1-MMP-associated proteins, we identified a heretofore uncharacterized protein. This protein, which we call p27RF-Rho, enhances activation of RhoA by releasing it from inhibition by p27(kip1) and thereby regulates actin structures. p27(kip1) is a well known cell cycle regulator in the nucleus. In contrast, cytoplasmic p27(kip1) has been demonstrated to bind GDP-RhoA and inhibit GDP-GTP exchange mediated by guanine nucleotide exchange factors. p27RF-Rho binds p27(kip1) and prevents p27(kip1) from binding to RhoA, thereby freeing the latter for activation. Knockdown of p27RF-Rho expression renders cells resistant to RhoA activation stimuli, whereas overexpression of p27RF-Rho sensitizes cells to such stimulation. p27RF-Rho exhibits a punctate distribution in invasive human tumor cell lines. Stimulation of the cells with lysophosphatidic acid induces activation of RhoA and induces the formation of punctate actin structures within foci of p27RF-Rho localization. Some of the punctate actin structures co-localize with MT1-MMP and cortactin. Down-regulation of p27RF-Rho prevents both redistribution of actin into the punctate structures and tumor cell invasion. Thus, p27RF-Rho is a new potential target for cancer therapy development.