Osmanagic-Myers Selma, Gregor Martin, Walko Gernot, Burgstaller Gerald, Reipert Siegfried, Wiche Gerhard
Department of Molecular Cell Biology, Max F. Perutz Laboratories, University of Vienna, A-1030 Vienna, Austria.
J Cell Biol. 2006 Aug 14;174(4):557-68. doi: 10.1083/jcb.200605172.
Plectin is a major intermediate filament (IF)-based cytolinker protein that stabilizes cells and tissues mechanically, regulates actin filament dynamics, and serves as a scaffolding platform for signaling molecules. In this study, we show that plectin deficiency is a cause of aberrant keratin cytoskeleton organization caused by a lack of orthogonal IF cross-linking. Keratin networks in plectin-deficient cells were more susceptible to osmotic shock-induced retraction from peripheral areas, and their okadaic acid-induced disruption (paralleled by stress-activated MAP kinase p38 activation) proceeded faster. Basal activities of the MAP kinase Erk1/2 and of the membrane-associated upstream protein kinases c-Src and PKCdelta were significantly elevated, and increased migration rates, as assessed by in vitro wound-closure assays and time-lapse microscopy, were observed. Forced expression of RACK1, which is the plectin-binding receptor protein for activated PKCdelta, in wild-type keratinocytes elevated their migration potential close to that of plectin-null cells. These data establish a link between cytolinker-controlled cytoarchitecture/scaffolding functions of keratin IFs and specific MAP kinase cascades mediating distinct cellular responses.
网蛋白是一种主要的基于中间丝（IF）的细胞连接蛋白，它在机械上稳定细胞和组织，调节肌动蛋白丝动力学，并作为信号分子的支架平台。在本研究中，我们表明网蛋白缺乏是由于缺乏正交IF交联导致角蛋白细胞骨架组织异常的一个原因。网蛋白缺陷细胞中的角蛋白网络更容易受到渗透压休克诱导的从周边区域回缩的影响，并且它们的冈田酸诱导的破坏（与应激激活的丝裂原活化蛋白激酶p38激活平行）进展更快。丝裂原活化蛋白激酶Erk1/2以及膜相关上游蛋白激酶c-Src和PKCδ的基础活性显著升高，并且通过体外伤口闭合试验和延时显微镜评估观察到迁移率增加。在野生型角质形成细胞中强制表达RACK1（它是活化PKCδ的网蛋白结合受体蛋白），其迁移潜力接近网蛋白缺失细胞。这些数据建立了角蛋白IF的细胞连接蛋白控制的细胞结构/支架功能与介导不同细胞反应的特定丝裂原活化蛋白激酶级联之间的联系。
