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Abstract: TH-PO343

TAZ Regulates the Vasopressin-Induced AQP2 Trafficking and Protein Expression in Kidney Collecting Duct Cells

Session Information

Category: Fluid‚ Electrolyte‚ and Acid-Base Disorders

  • 1001 Fluid‚ Electrolyte‚ and Acid-Base Disorders: Basic


  • Choi, Hong Seok, Kyungpook National University School of Medicine, Daegu, Korea (the Republic of)
  • Jang, Hyo-Ju, Kyungpook National University School of Medicine, Daegu, Korea (the Republic of)
  • Kwon, Tae-Hwan, Kyungpook National University School of Medicine, Daegu, Korea (the Republic of)

Aquaporin-2 (AQP2) is the vasopressin-regulated water channel protein in the kidney collecting duct (CD) cells. Transcriptional coactivator with PDZ-binding motif (TAZ) is a downstream effector of the hippo signaling pathway. TAZ regulates the expression of target genes by acting as a transcription cofactor and acts as a mechanotransducer that detects various cell responses. Since TAZ is known to regulate the activity of Tonicity-Responsive Enhancer Binding Protein (TonEBP), a transcription factor of AQP2, and to affect the arrangement of the cytoskeleton, we aimed to study the role of TAZ in the vasopressin-induced AQP2 trafficking and protein abundance.


1) siRNA-mediated knockdown of TAZ in mpkCCDc14 cells; 2) immunocytochemistry of AQP2; 3) qRT-PCR and semiquantitative immunoblotting of AQP2.


To induce AQP2 expression in mpkCCDc14 cells, cells were pretreated with dDAVP (10-9M) for 48 h, and dDAVP stimulation was withdrawn for the next 6 h for the experiments. When the cells were treated again with dDAVP (10-9M) for 15 and 30 min, AQP2 was translocated to the cell membrane. In contrast, the AQP2 trafficking was markedly attenuated, and it was mainly observed in the cytoplasm in the cells with siRNA-mediated TAZ knockdown (TAZ-KD). Phalloidin staining demonstrated that stress fiber formation was markedly enhanced in the TAZ-KD, suggesting that excessive stress fiber formation is likely to inhibit AQP2 trafficking. To study the changes of AQP2 mRNA and protein abundance, cells were treated with dDAVP (10-9 M) for 12 h. In the control mpkCCDc14 cells, dDAVP induced AQP2 mRNA (3,575 ± 477% of the control) and AQP protein (270 ± 18%). In contrast, the dDAVP-induced increase of AQP2 mRNA (50 ± 5% of the control) and protein abundance (99 ± 17%) was not observed in TAZ-KD. In addition, to avoid the effects of dDAVP pretreatment, cells were stimulated with dDAVP (10-9M, 24 h) without the periods of pretreatment and withdrawal. Semiquantitative immunoblotting revealed that dDAVP increased AQP2 protein abundance in the control, whereas it was not observed in TAZ-KD. TonEBP was significantly decreased (52 ± 4%) in TAZ KD.


TAZ knockdown is associated with an inhibition in AQP2 trafficking, at least partly, due to an excessive stress fiber formation, and downregulation of AQP2, possibly via decreased TonEBP expression.


  • Government Support – Non-U.S.