The Role of the Exocyst in Matrix Metalloproteinase Secretion and Actin Dynamics during Tumor Cell Invadopodia Formation
The Role of the Exocyst in Matrix Metalloproteinase Secretion and Actin Dynamics during Tumor Cell Invadopodia Formation
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DOI：
10.1091/mbc.e08-09-0967
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发表时间：
2009-08-15
影响因子：
3.3
通讯作者：
Guo, Wei
中科院分区：
文献类型：
--
作者：
Liu, Jianglan;Yue, Peng;Guo, Wei
侵袭伪足是由肿瘤细胞形成的富含肌动蛋白的膜突起，其降解细胞外基质以用于侵袭。侵入伪足的形成涉及Arp 2/3介导的肌动蛋白聚合和在病灶降解位点分泌基质金属蛋白酶（MMPs）驱动的膜突起。外泌囊介导高尔基体后分泌囊泡在质膜上的束缚作用，用于胞吐作用，最近被认为与细胞迁移过程中调节肌动蛋白动力学有关。在这里，我们报告，外囊在侵袭伪足活动中起着关键作用。通过RNAi敲除外囊组分Exo 70或Sec 8，表达组成型活性c-Src的MDA-MB-231细胞不能形成侵袭伪足。另一方面，Exo 70的过表达促进侵袭伪足的形成。通过siEXO 70或siSEC 8处理或通过Exo 70的显性负性片段的表达来破坏外泌囊功能抑制MMP的分泌。我们还发现，在具有高侵袭潜力的细胞中，外囊与Arp 2/3复合物相互作用;阻断外囊-Arp 2/3相互作用可抑制Arp 2/3介导的肌动蛋白聚合和侵袭伪足形成。总之，我们的研究结果表明，外囊在细胞入侵中起着重要的作用，通过介导的MMPs的分泌在焦点降解网站和调节Arp 2/3介导的肌动蛋白动力学。
Invadopodia are actin-rich membrane protrusions formed by tumor cells that degrade the extracellular matrix for invasion. Invadopodia formation involves membrane protrusions driven by Arp2/3-mediated actin polymerization and secretion of matrix metalloproteinases (MMPs) at the focal degrading sites. The exocyst mediates the tethering of post-Golgi secretory vesicles at the plasma membrane for exocytosis and has recently been implicated in regulating actin dynamics during cell migration. Here, we report that the exocyst plays a pivotal role in invadopodial activity. With RNAi knockdown of the exocyst component Exo70 or Sec8, MDA-MB-231 cells expressing constitutively active c-Src failed to form invadopodia. On the other hand, overexpression of Exo70 promoted invadopodia formation. Disrupting the exocyst function by siEXO70 or siSEC8 treatment or by expression of a dominant negative fragment of Exo70 inhibited the secretion of MMPs. We have also found that the exocyst interacts with the Arp2/3 complex in cells with high invasion potential; blocking the exocyst-Arp2/3 interaction inhibited Arp2/3-mediated actin polymerization and invadopodia formation. Together, our results suggest that the exocyst plays important roles in cell invasion by mediating the secretion of MMPs at focal degrading sites and regulating Arp2/3-mediated actin dynamics.