Ravi Archna, Kaushik Shelly, Ravichandran Aarthi, Pan Catherine Qiurong, Low Boon Chuan
From the Cell Signaling and Developmental Biology Laboratory, Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, 117543 Singapore and the Mechanobiology Institute, National University of Singapore, 5A Engineering Drive, 117411 Singapore.
the Mechanobiology Institute, National University of Singapore, 5A Engineering Drive, 117411 Singapore.
J Biol Chem. 2015 Feb 13;290(7):4149-62. doi: 10.1074/jbc.M114.616839. Epub 2014 Dec 18.
Deleted in Liver Cancer 1 (DLC1) is a RHO GTPase-activating protein (GAP) that negatively regulates RHO. Through its GAP activity, it modulates the actin cytoskeleton network and focal adhesion dynamics, ultimately leading to suppression of cell invasion and metastasis. Despite its presence in various structural and signaling components, little is known about how the activity of DLC1 is regulated at focal adhesions. Here we show that EGF stimulation activates the GAP activity of DLC1 through a concerted mechanism involving DLC1 phosphorylation by MEK/ERK and its subsequent dephosphorylation by protein phosphatase 2A (PP2A) and inhibition of focal adhesion kinase by MEK/ERK to allow the binding between DLC1 and PP2A. Phosphoproteomics and mutation studies revealed that threonine 301 and serine 308 on DLC1, known previously to be mutated in certain cancers, are required for DLC1-PP2A interaction and the subsequent activation of DLC1 upon their dephosphorylation. The intricate interplay of this "MEK/ERK-focal adhesion kinase-DLC1-PP2A" quartet provides a novel checkpoint in the spatiotemporal control of cell spreading and cell motility.
肝癌缺失基因1（DLC1）是一种RHO GTP酶激活蛋白（GAP），对RHO起负向调控作用。通过其GAP活性，它可调节肌动蛋白细胞骨架网络和粘着斑动力学，最终抑制细胞侵袭和转移。尽管DLC1存在于各种结构和信号成分中，但对于其在粘着斑处的活性调控方式却知之甚少。在此我们表明，表皮生长因子（EGF）刺激通过一种协同机制激活DLC1的GAP活性，该机制涉及MEK/ERK对DLC1的磷酸化作用以及随后蛋白磷酸酶2A（PP2A）对其的去磷酸化作用，同时MEK/ERK对粘着斑激酶的抑制作用，从而使DLC1与PP2A得以结合。磷酸化蛋白质组学和突变研究表明，DLC1上的苏氨酸301和丝氨酸308（先前已知在某些癌症中发生突变）对于DLC1与PP2A的相互作用以及去磷酸化后DLC1的后续激活是必需的。这个“MEK/ERK-粘着斑激酶-DLC1-PP2A”四重奏的复杂相互作用在细胞铺展和细胞运动的时空控制中提供了一个新的检查点。
