Vasopressin increases S261 phosphorylation in AQP2-P262L, a mutant in recessive nephrogenic diabetes insipidus

Item Type:	Article
Title:	Vasopressin increases S261 phosphorylation in AQP2-P262L, a mutant in recessive nephrogenic diabetes insipidus
Creators Name:	Trimpert, C. and van den Berg, D.T.M. and Fenton, R.A. and Klussmann, E. and Deen, P.M.T.
Abstract:	Background: Mutations in the aquaporin-2 (AQP2) gene cause nephrogenic diabetes insipidus (NDI), a renal disorder characterized by polyuria due to a lacking antidiuretic response to vasopressin. While most AQP2 mutants in recessive NDI are misfolded and retained in the endoplasmic reticulum, AQP2-P262L in NDI was impaired in its vasopressin-dependent translocation from vesicles to the plasma membrane. Methods: Vasopressin-induced translocation of AQP2 coincides with AQP2 phosphorylation at S256, S264 and T269 and dephosphorylation at S261. Since P262 lies adjacent to S261, we tested whether a changed phosphorylation could underlie AQP-P262L missorting in NDI. Results: In polarized cells, AQP2-P262L expressed as a double 29/30 kDa band, whereas wt-AQP2 expressed only as a 29 kDa band. Phosphatase treatment revealed that the 30 kDa AQP2-P262L band was due to changed phosphorylation. The use of newly developed phospho-specific antibodies showed that forskolin not only increased pS256 and pT269, but, in contrast to wt-AQP2, also pS261 in AQP2-P262L. The expression of AQP2-P262L proteins in which S261 phosphorylation was prevented (S261A), however, was still missorted to vesicles/basolateral membrane, despite the absence of the 30 kDa band. Conclusions: Together, our data reveal that vasopressin induces instead of reduces the phosphorylation of S261 in AQP2-P262L, but it remains to be established whether the changed phosphorylation causes its missorting in NDI.
Keywords:	AQP2 Water Channel, Nephrogenic Diabetes Insipidus, Phosphorylation, Water Transport, Animals
Source:	Nephrology Dialysis Transplantation
ISSN:	0931-0509
Publisher:	Oxford University Press
Volume:	27
Number:	12
Page Range:	4389-4397
Date:	December 2012
Official Publication:	https://doi.org/10.1093/ndt/gfs292
PubMed:	View item in PubMed

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