Colocalization of APC and DLG at the tips of cellular protrusions in cultured epithelial cells and its dependency on cytoskeletons
Colocalization of APC and DLG at the tips of cellular protrusions in cultured epithelial cells and its dependency on cytoskeletons
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DOI：
10.1007/s00418-004-0729-2
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发表时间：
2005-01-01
影响因子：
2.3
通讯作者：
Senda, T
中科院分区：
文献类型：
--
作者：
Iizuka-Kogo, A;Shimomura, A;Senda, T
大肠腺瘤性息肉病基因产物（APC）是一种与家族性腺瘤性息肉病相关的肿瘤抑制因子，被认为参与了移动上皮细胞的细胞极化和迁移。APC与大圆盘（DLG）的哺乳动物同源物相互作用。DLG是膜相关鸟苷酸激酶超家族的成员，被认为是一种支架蛋白，协调上皮细胞中侧质膜定位蛋白复合物的组装。我们证实了几种抗apc抗体用于免疫细胞化学分析的适用性。使用这些抗体，我们发现APC簇与DLG蛋白在亚融合MDCK细胞的细胞突起处共定位。在延伸到细胞突起的微管尖端发现了一部分簇。此外，肌动蛋白应力纤维在簇附近聚集。当微管被诺可达唑破坏时，APC和DLG的共定位由于APC簇的消失而丧失。然而，在肌动蛋白丝与latrunculin a解聚后，共簇仍然存在。这是首次报道APC和DLG在非极化上皮细胞中共定位。这种共定位表明，DLG不仅在极化上皮细胞的外侧细胞-细胞接触部位起作用，而且通过与APC蛋白的相互作用在非极化上皮细胞的突起处起作用。
Adenomatous polyposis coli gene product (APC) is a tumor suppressor linked to familial adenomatous polyposis and is thought to be involved in cellular polarization and migration in moving epithelial cells. APC interacts with the mammalian homolog of Discs large (DLG). DLG is a member of the membrane-associated guanylate kinase superfamily and is thought to function as a scaffolding protein that coordinates the assembly of a lateral plasma membrane-localized protein complex in epithelial cells. We confirmed the suitability of several anti-APC antibodies for immunocytochemical analysis. Using these antibodies, we showed that APC clusters were colocalized with DLG protein at cellular protrusions of subconfluent MDCK cells. A portion of the clusters was found at the tips of microtubules extending into the cellular protrusions. In addition, actin stress fibers converged near the clusters. When microtubules were disrupted by nocodazole, the colocalization of APC and DLG was lost due to the disappearance of APC clusters. However, the coclusters remained after depolymerization of actin filaments with latrunculin A. This is the first report showing colocalization of APC and DLG in non-polarized epithelial cells. This colocalization suggests that DLG functions not only at the lateral cell-cell contact sites of polarized epithelial cells but also at the protrusions of non-polarized epithelial cells through the interaction with APC protein.