Differential localization of aquaporin-2 and glucose transporter 4 in polarized MDCK cells.
Membrane water channel aquaporin-2 (AQP2) and glucose transporter 4 (GLUT4) exhibit a common feature in that they are stored in intracellular storage compartments and undergo translocation to the plasma membrane upon hormonal stimulation. We compared the intracellular localization and trafficking of AQP2 and GLUT4 in polarized Madin-Darby canine kidney cells stably transfected with human AQP2 (MDCK-hAQP2) by immunofluorescence microscopy. When expressed in MDCK-hAQP2 cells, GLUT4 and GLUT4-EGFP were predominantly localized in the perinuclear region close to and within the Golgi apparatus, similar to endogenous GLUT4 in adipocytes and myocytes. In addition, GLUT4 was occasionally seen in EEA1-positive early endosomes. AQP2, on the other hand, was sequestered in subapical Rab11-positive vesicles. In the basal state, the intracellular storage site of GLUT4 was distinct from that of AQP2. Forskolin induced translocation of AQP2 from the subapical storage vesicles to the apical plasma membrane, which did not affect GLUT4 localization. When forskolin was washed out, AQP2 was first retrieved to early endosomes from the apical plasma membrane, where it was partly colocalized with GLUT4. AQP2 was then transferred to Rab11-positive storage vesicles. These results show that AQP2 and GLUT4 share a common compartment after retrieval from the plasma membrane, but their storage compartments are distinct from each other in polarized MDCK-hAQP2 cells.
Hasegawa
Takahiro
T
Department of Anatomy and Cell Biology, Gunma University Graduate School of Medicine, 3-39-22, Showa-machi, Maebashi, Gunma 371-8511, Japan.
Matsuzaki
Toshiyuki
T
Tajika
Yuki
Y
Ablimit
Abduxukur
A
Suzuki
Takeshi
T
Aoki
Takeo
T
Hagiwara
Haruo
H
Takata
Kuniaki
K
D000818:Animals; D051399:Aquaporin 2 / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D016764:Cell Polarity; D004285:Dogs; D011992:Endosomes / Q000378:metabolism; D051275:Glucose Transporter Type 4 / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000166:cytology*; D018613:Microscopy, Confocal; D021381:Protein Transport; D014162:Transfection
C496023:AQP2 protein, human; D051399:Aquaporin 2; D051275:Glucose Transporter Type 4