Differential regulation of AQP2 trafficking in endosomes by microtubules and actin filaments.
Vasopressin-induced trafficking of aquaporin-2 (AQP2) water channels in kidney collecting duct cells is critical to regulate the urine concentration. To better understand the mechanism of subcellular trafficking of AQP2, we examined MDCK cells expressing AQP2 as a model. We first performed double-immunolabeling of AQP2 with endosomal marker proteins, and showed that AQP2 is stored at a Rab11-positive subapical compartment. After the translocation to the plasma membrane, AQP2 was endocytosed to EEA1-positive early endosomes, and then transferred back to the original Rab11-positive compartment. When Rab11 was depleted by RNA interference, retention of AQP2 at the subapical storage compartment was impaired. We next examined the role of cytoskeleton in the AQP2 trafficking and localization. By the treatment with microtubule-disrupting agent such as nocodazole or colcemid, the distribution of AQP2 storage compartment was altered. The disruption of actin filaments with cytochalasin D or latrunculin B induced the accumulation of AQP2 in EEA1-positive early endosomes. Altogether, our data suggest that Rab11 and microtubules maintain the proper distribution of the subapical AQP2 storage compartment, and actin filaments regulate the trafficking of AQP2 from early endosomes to the storage compartment.
Tajika
Yuki
Y
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
Suzuki
Takeshi
T
Ablimit
Abdushukur
A
Aoki
Takeo
T
Hagiwara
Haruo
H
Kuwahara
Michio
M
Sasaki
Sei
S
Takata
Kuniaki
K
D008841:Actin Cytoskeleton / Q000378:metabolism* / Q000502:physiology; D011992:Endosomes / Q000378:metabolism*; D004847:Epithelial Cells; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000378:metabolism / Q000502:physiology; D008870:Microtubules / Q000378:metabolism* / Q000502:physiology; D021381:Protein Transport / Q000502:physiology*; D013997:Time Factors; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins / Q000378:metabolism / Q000502:physiology; D000099193:rab11 GTP-Binding Proteins
D008565:Membrane Proteins; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins; D000099193:rab11 GTP-Binding Proteins; C093846:early endosome antigen 1