Role for actin filament turnover and a myosin II motor in cytoskeleton-driven disassembly of the epithelial apical junctional complex
Role for actin filament turnover and a myosin II motor in cytoskeleton-driven disassembly of the epithelial apical junctional complex
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DOI：
10.1091/mbc.e04-02-0163
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发表时间：
2004-06-01
影响因子：
3.3
通讯作者：
Nusrat, A
中科院分区：
文献类型：
--
作者：
Ivanov, AI;McCall, IC;Nusrat, A
上皮顶端连接复合体（epithelial apical junctional complex，AJC）由紧密连接（tight junction，TJ）和粘附连接（adherens junction，AJ）组成，在正常组织重建和病原体诱导的上皮屏障破坏中起重要作用。在T84上皮细胞中使用钙耗竭模型，我们先前发现AJC的分解导致AJ/TJ蛋白的内吞作用。在本研究中，我们研究了肌动蛋白细胞骨架在AJC分解和内化中的作用。钙耗竭诱导顶端F-肌动蛋白重组成收缩环。内化的AJ/TJ蛋白与这些环共定位。解聚和稳定的F-肌动蛋白抑制环的形成和拆卸的AJC，表明肌动蛋白丝营业额的作用。肌动蛋白重组伴随着cofilin-1的激活（去磷酸化）及其易位到F-肌动蛋白环。此外，Arp 3和corneum与这些环共域。F-actin的重组和AJC的解体被非肌肉肌球蛋白II的抑制剂blebbistatin阻断。肌球蛋白IIA在T84细胞中表达，并与F-肌动蛋白环共定位。我们的结论是，在钙耗竭的细胞AJC的解体是由顶端F-肌动蛋白的重组。这种重组的机制涉及cofilin-1依赖性解聚和Arp 2/3辅助的肌动蛋白丝的再聚合以及肌球蛋白IIA介导的收缩。
Disassembly of the epithelial apical junctional complex (AJC), composed of the tight junction (TJ) and adherens junction (AJ), is important for normal tissue remodeling and pathogen-induced disruption of epithelial barriers. Using a calcium depletion model in T84 epithelial cells, we previously found that disassembly of the AJC results in endocytosis of AJ/TJ proteins. In the present study, we investigated the role of the actin cytoskeleton in disassembly and internalization of the AJC. Calcium depletion induced reorganization of apical F-actin into contractile rings. Internalized AJ/TJ proteins colocalized with these rings. Both depolymerization and stabilization of F-actin inhibited ring formation and disassembly of the AJC, suggesting a role for actin filament turnover. Actin reorganization was accompanied by activation (dephosphorylation) of cofilin-1 and its translocation to the F-actin rings. In addition, Arp3 and cortactin colocalized with these rings. F-actin reorganization and disassembly of the AJC were blocked by blebbistatin, an inhibitor of nonmuscle myosin II. Myosin IIA was expressed in T84 cells and colocalized with F-actin rings. We conclude that disassembly of the AJC in calcium-depleted cells is driven by reorganization of apical F-actin. Mechanisms of such reorganization involve cofilin-1-dependent depolymerization and Arp2/3-assisted repolymerization of actin filaments as well as myosin IIA-mediated contraction.