CLIC4 is enriched at cell-cell junctions and colocalizes with AKAP350 at the centrosome and midbody of cultured mammalian cells
CLIC4 is enriched at cell-cell junctions and colocalizes with AKAP350 at the centrosome and midbody of cultured mammalian cells
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DOI：
10.1002/cm.10141
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发表时间：
2003-11-01
影响因子：
--
通讯作者：
Goldenring, JR
中科院分区：
文献类型：
--
作者：
Berryman, MA;Goldenring, JR
CLIC4是氯离子胞内通道（CLIC）蛋白家族的一员，其主要细胞功能尚不清楚。最近，我们证明了包括CLIC4在内的几种CLIC蛋白与AKAP350相互作用。AKAP350集中在高尔基体、中心体和中间体，作为几种蛋白激酶和磷酸酶的支架蛋白。在本报告中，我们通过免疫荧光显微镜发现内源性CLIC4和AKAP350在培养细胞的中心体和中间体共定位。与AKAP350不同的是，CLIC4并不富集于高尔基体中，而是富集于线粒体、细胞皮层的肌动蛋白结构和核基质中，这表明在体内，CLIC4-AKAP350的相互作用在特定的亚细胞位点受到调控。除了中心体和中间体外，CLIC4还与AKAP350和紧密连接蛋白ZO-1在极化上皮细胞的顶端区域共定位，这表明在有丝分裂和细胞分裂过程中，CLIC4可能在维持顶端-基底侧膜极性方面发挥作用。生化研究表明，CLIC4主要表现为可溶性胞质蛋白，可与微管细胞骨架蛋白结合。CLIC4定位于皮质肌动蛋白细胞骨架及其与中心体和中间体的AKAP350的关联表明，在细胞周期中，CLIC4可能对调节细胞骨架组织很重要。这些发现得出结论，CLIC4和其他可能的CLIC蛋白具有不同于氯离子通道的细胞功能。(C) 2003 Wiley-Liss, Inc。
CLIC4 is a member of the chloride intracellular channel (CLIC) protein family whose principal cellular functions are poorly understood. Recently, we demonstrated that several CLIC proteins, including CLIC4, interact with AKAP350. AKAP350 is concentrated at the Golgi apparatus, centrosome, and midbody and acts as a scaffolding protein for several protein kinases and phosphatases. In this report, we show that endogenous CLIC4 and AKAP350 colocalize at the centrosome and midbody of cultured cells by immunofluorescence microscopy. Unlike AKAP350, CLIC4 is not enriched in the Golgi apparatus but is enriched in mitochondria, actin-based structures at the cell cortex, and the nuclear matrix, indicating that CLIC4-AKAP350 interactions are regulated at specific subcellular sites in vivo. In addition to the centrosome and midbody, CLIC4 colocalizes with AKAP350 and the tight junction protein ZO-1 in the apical region of polarized epithelial cells, suggesting that CLIC4 may play a role in maintaining apical-basolateral membrane polarity during mitosis and cytokinesis. Biochemical studies show that CLIC4 behaves mainly as a soluble cytosolic protein and can associate with proteins of the microtubule cytoskeleton. The localization of CLIC4 to the cortical actin cytoskeleton and its association with AKAP350 at the centrosome and midbody suggests that CLIC4 may be important for regulating cytoskeletal organization during the cell cycle. These findings lead to the conclusion that CLIC4 and possibly other CLIC proteins have alternate cellular functions that are distinct from their proposed roles as chloride channels. (C) 2003 Wiley-Liss, Inc.