Aquaporin-2 is retrieved to the apical storage compartment via early endosomes and phosphatidylinositol 3-kinase-dependent pathway
Aquaporin-2 is retrieved to the apical storage compartment via early endosomes and phosphatidylinositol 3-kinase-dependent pathway
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DOI：
10.1210/en.2004-0073
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发表时间：
2004-09-01
期刊：
影响因子：
4.8
通讯作者：
Takata, K
中科院分区：
文献类型：
--
作者：
Tajika, Y;Matsuzaki, T;Takata, K
水通道蛋白-2 (AQP2) 是肾集合管主细胞中表达的水通道蛋白之一，储存在细胞内区室中。先前的研究表明，AQP2 囊泡构成了一个独特的细胞内区室，与早期内体部分重叠。在本报告中，我们使用稳定表达 AQP2 (MDCK-hAQP2) 的肾上皮细胞系 Madin-Darby 犬肾 (MDCK) 细胞进行了体外实验。在非极化细胞中，AQP2 囊泡分散在细胞质中，并且不与高尔基体 58K 或 TGN38 共定位。小部分 AQP2 囊泡的溶酶体标记物组织蛋白酶 D 呈阳性。早期内体抗原 (EEA1) 位于 AQP2 囊泡周围，非常接近，表明内体系统参与了 AQP2 的运输。 AQP2 囊泡不同于其他回收分子，例如葡萄糖转运蛋白 4 (GLUT4) 和内吞转铁蛋白。在极化的 MDCK-hAQP2 细胞中，AQP2 囊泡位于心尖下循环室中，与未刺激的高尔基体、跨高尔基体网络、溶酶体和早期内体不同。状态。当用毛喉素处理细胞时，观察到 AQP2 易位至顶膜。毛喉素的冲洗诱导 AQP2 恢复到细胞质中，并且 AQP2 短暂地与 EEA1 阳性内体共定位。然后，。 AQP2 从 EEA1 阳性核内体转移到顶端下 AQP2 储存室，该储存室对渥曼青霉素和 LY294002 敏感。这些结果表明，AQP2 存在于极化 MDCK-hAQP2 细胞顶端侧的回收室中，其回收利用顶端内体系统和磷脂酰肌醇 3 激酶依赖性途径。
Aquaporin-2 (AQP2) is one of the water-channel proteins expressed in principal cells of kidney collecting ducts, where it is stored in the intracellular compartment. Previous studies have demonstrated that AQP2 vesicles constitute a distinct intracellular compartment partially overlapping with early endosomes. In this report, we performed in vitro experiments using the renal epithelia] cell line, Madin-Darby canine,kidney (MDCK) cells, stably expressing AQP2 (MDCK-hAQP2). In nonpolarized cells, AQP2 vesicles were scattered in the cytoplasm and did not colocalize with Golgi 58K or TGN38. Small portions of AQP2 vesicles were positive for the lysosome marker cathepsin D. An early endosome antigen (EEA1) localized around AQP2 vesicles in close proximity, suggesting involvement of the endosomal system in the trafficking of AQP2. AQP2 vesicles are distinct from other recycling molecules, such as glucose transporter 4 (GLUT4) and endocytosed transferrin. In polarized MDCK-hAQP2 cells, AQP2 vesicles were localized in the subapical recycling compartment and distinct from the Golgi apparatus, trans-Golgi network, lysosome, and early endosome in the nonstimulated. state. When the cells were treated with forskolin, translocation of AQP2 to the apical membrane was observed. Washout of forskolin induced retrieval of AQP2 into the cytoplasm, and AQP2 was transiently colocalized with EEA1-positive endosomes. Then,. AQP2 moved from EEA1-positive endosomes to the subapical AQP2-storage compartment, which is sensitive to wortmannin and LY294002. These results suggest that AQP2 resides in a recycling compartment at the apical side in polarized MDCK-hAQP2 cells, and its retrieval uses the apical endosomal system and the phosphatidylinositol 3-kinase-dependent pathway.