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Regulation of NKCC2 by WNK3 and SPAK
Author(s) -
PonceCoria Jose,
SanCristobal Pedro,
Vazquez Norma,
PachecoAlvarez Diana,
Muñoz Eva,
Bobadilla Norma,
Gimenez Igancio,
Kahle Kristopher,
Hebert Steve,
Gamba Gerardo
Publication year - 2008
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.22.1_supplement.935.2
Subject(s) - cotransporter , serine , phosphorylation , intracellular , chemistry , kinase , xenopus , threonine , chloride , microbiology and biotechnology , biochemistry , biology , sodium , gene , organic chemistry
Little is known about regulation of the Na‐K‐2Cl cotransporter (NKCC2) by non cAMP/PKA mechanisms. In this study, NKCC2 activity was analyzed by assessing 86 Rb + uptake in Xenopus laevis oocytes. We show that intracellular chloride depletion in oocytes, induced by co‐expression of NKCC2 with the K‐Cl cotransporter KCC2 or by low‐chloride hypotonic stress, activates NKCC2. This activation is associated with phosphorylation of three highly‐conserved threonines (96, 101, and 111) of NKCC2 amino terminus. The chloride‐sensitive activation of NKCC2 requires the interaction of two serine‐threonine kinases, WNK3 and SPAK. Elimination of WNK3's only SPAK‐binding motif prevents its binding with SPAK and activation of NKCC2. Thus, WNK3 appears to be positioned upstream of SPAK. Elimination of the threonines 96, 101, and 111 or the injection of a catalytically‐inactive WNK3 mutant also completely prevents NKCC2 activation by intracellular chloride depletion. Together, these data reveal a novel chloride‐sensing mechanism that regulates NKCC2, requiring WNK3 and SPAK. We propose that WNK3 appears to be the chloride‐sensitive kinase.