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Catalytically‐inactive WNK3 bypasses the tonicity requirement for K‐Cl cotransporter activation via a phosphatase‐dependent pathway
Author(s) -
De los Heros Paola,
Kahle Kristopher T,
Rinehart Jesse,
Bobadilla Norma A,
Cristobal Pedro San,
Vazquez Norma,
Lifton Richard,
Hebert Steven C,
Gamba Gerardo
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a1224
Subject(s) - cotransporter , dephosphorylation , phosphorylation , chemistry , phosphatase , xenopus , tonicity , biochemistry , sodium , gene , organic chemistry
SLC12A cation/Cl − cotransporter gene family has two major branches. The K + :Cl − cotransporters (KCC1 to KCC4) that are inhibited by phosphorylation and activated by dephosphorylation, and the Na‐coupled chloride cotransporters (NCC and NKCCs) that are activated by phosphorylation and inhibited by dephosphorylation. We have recently shown that the serine/threonine kinase WNK3 modulates the activity of the cation‐chloride cotransporters. Here we show that co‐injection of Xenopus laevis oocytes with any of the K + :Cl − cotransporters cRNA, together with the wild‐type WNK3 cRNA results in prevention of the cell swelling induced activation of the cotransporters (see 86 Rb + uptake per group in nmol/oocyte/h in the table). In contrast, co‐injection of the K + :Cl − cotransporters cRNA with the catalytically inactive WNK3‐D294A, resulted in a markedly increase of the cotransporters activity, even in isotonic conditions in which the K + :Cl − cotransporters are normally inactive (see table). The activation of KCC1 to KCC4 by WNK3‐D294A in isotonicity can be completely prevented by treatment of oocytes with a combination of calyculin A and cyclosporine A, which inhibit the protein phosphatase 1 and 2B, respectively. Thus, the catalytically inactive WNK3‐D294A bypasses the tonicity requirements for K + :Cl − cotransporters activation via a phosphatases dependent mechanism.