Involvement of PDZ-SAP97 interactions in regulating AQP2 translocation in response to vasopressin in LLC-PK1 cells

Mohammed M. Nooh, Ajay Kale, Suleiman Bahouth

Research output: Contribution to journalArticle

Abstract

Arginine-vasopressin (AVP)-mediated translocation of aquaporin-2 (AQP2) protein-forming water channels from storage vesicles to the membrane of renal collecting ducts is critical for the renal conservation of water. The type-1 PDZ-binding motif (PBM) in AQP2, “GTKA,” is a critical barcode for its translocation, but its precise role and that of its interacting protein partners in this process remain obscure. We determined that synapse-associated protein-97 (SAP97), a membrane-associated guanylate kinase protein involved in establishing epithelial cell polarity, was an avid binding partner to the PBM of AQP2. The role of PBM and SAP97 on AQP2 redistribution in response to AVP was assessed in LLC-PK1 renal collecting cells by confocal microscopy and cell surface biotinylation techniques. These experiments indicated that distribution of AQP2 and SAP97 overlapped in the kidneys and LLC-PK1 cells and that knockdown of SAP97 inhibited the translocation of AQP2 in response to AVP. Binding between AQP2 and SAP97 was mediated by specific interactions between the second PDZ of SAP97 and PBM of AQP2. Mechanistically, inactivation of the PBM of AQP2, global delocal-ization of PKA, or knockdown of SAP97 inhibited AQP2 translocation as well as AVP-and forskolin-mediated phosphorylation of Ser256 in AQP2, which serves as the major translocation barcode of AQP2. These results suggest that the targeting of PKA to the mi-crodomain of AQP2 via SAP97-AQP2 interactions in association with cross-talk between two barcodes in AQP2, namely, the PBM and phospho-Ser256, plays an important role in the translocation of AQP2 in the kidney.

Original languageEnglish (US)
Pages (from-to)F375-F387
JournalAmerican Journal of Physiology - Renal Physiology
Volume317
Issue number2
DOIs
StatePublished - Jan 1 2019

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Aquaporin 2
LLC-PK1 Cells
Vasopressins
Confocal Microscopy
Phosphorylation
Arginine Vasopressin
Kidney
human DLG1 protein
Guanylate Kinases
Biotinylation
Cell Polarity
Aquaporins

All Science Journal Classification (ASJC) codes

  • Physiology
  • Urology

Cite this

Involvement of PDZ-SAP97 interactions in regulating AQP2 translocation in response to vasopressin in LLC-PK1 cells. / Nooh, Mohammed M.; Kale, Ajay; Bahouth, Suleiman.

In: American Journal of Physiology - Renal Physiology, Vol. 317, No. 2, 01.01.2019, p. F375-F387.

Research output: Contribution to journalArticle

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