Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Am J Physiol Renal Physiol
2011 Apr 01;3004:F840-7. doi: 10.1152/ajprenal.00552.2010.
Show Gene links
Show Anatomy links
Rare mutations in the human Na-K-Cl cotransporter (NKCC2) associated with lower blood pressure exhibit impaired processing and transport function.
Monette MY
,
Rinehart J
,
Lifton RP
,
Forbush B
.
???displayArticle.abstract???
The Na-K-Cl cotransporter (NKCC2) is the major salt transport pathway in the thick ascending limb of Henle's loop and is part of the molecular mechanism for blood pressure regulation. Recent screening of ∼3,000 members of the Framingham Heart Study identified nine rare independent mutations in the gene encoding NKCC2 (SLC12A1) associated with clinically reduced blood pressure and protection from hypertension (Ji WZ, Foo JN, O'Roak BJ, Zhao H, Larson MG, Simon DB, Newton-Cheh C, State M, Levy D, Lifton RP. Nat Genet 40: 592-599, 2008). To investigate their functional consequences, we introduced the nine mutations in human NKCC2A and examined protein function, expression, localization, regulation, and ion transport kinetics using heterologous expression in Xenopus laevis oocytes and HEK-293 cells. When expressed in oocytes, four of the mutants (T235M, R302W, L505V, and P569H) exhibited reduced transport function compared with wild-type. In HEK-293 cells, the same four mutants exhibited reduced function, and in addition N399S and P1083A had significantly lower activity than wild-type. The two most functionally impaired mutants (R302W and L505V) exhibited dramatically diminished production of complex-glycosylated protein and a decrease in or absence of plasma membrane localization, indicative of a processing defect. All of the functional human (h) NKCC2A variants were regulated by changes in oocyte volume and intracellular chloride in HEK cells, but P254A and N399S exhibited a lower constitutive activity in HEK cells. The P569H mutant exhibited a 50% reduction in sodium affinity compared with wild-type, predicting lower transport activity at lower intratubular salt concentrations, while the P254A mutant exhibited a 35% increase in rubidium affinity. We conclude that defects in NKCC2 processing, transport turnover rate, regulation, and ion affinity contribute to impaired transport function in six of the nine identified mutants, providing support for the predictive approach of Ji et al. to identify functionally important residues by sequence conservation. Such mutations in hNKCC2A are likely to reduce renal salt reabsorption, providing a mechanism for lower blood pressure.
Benziane,
NKCC2 surface expression in mammalian cells: down-regulation by novel interaction with aldolase B.
2007, Pubmed
Benziane,
NKCC2 surface expression in mammalian cells: down-regulation by novel interaction with aldolase B.
2007,
Pubmed
Carmosino,
Exon loss accounts for differential sorting of Na-K-Cl cotransporters in polarized epithelial cells.
2008,
Pubmed
Caron,
Cloning and functional characterization of a cation-Cl- cotransporter-interacting protein.
2000,
Pubmed
,
Xenbase
Carota,
Localization and functional characterization of the human NKCC2 isoforms.
2010,
Pubmed
,
Xenbase
Casula,
A dominant negative mutant of the KCC1 K-Cl cotransporter: both N- and C-terminal cytoplasmic domains are required for K-Cl cotransport activity.
2001,
Pubmed
,
Xenbase
Darman,
A regulatory locus of phosphorylation in the N terminus of the Na-K-Cl cotransporter, NKCC1.
2002,
Pubmed
Denning,
Processing of mutant cystic fibrosis transmembrane conductance regulator is temperature-sensitive.
1992,
Pubmed
,
Xenbase
Fang,
Hypertension resistance polymorphisms in ROMK (Kir1.1) alter channel function by different mechanisms.
2010,
Pubmed
,
Xenbase
Fang,
Structure of a prokaryotic virtual proton pump at 3.2 A resolution.
2009,
Pubmed
Giménez,
The residues determining differences in ion affinities among the alternative splice variants F, A, and B of the mammalian renal Na-K-Cl cotransporter (NKCC2).
2007,
Pubmed
,
Xenbase
Hannemann,
Functional expression of the Na-K-2Cl cotransporter NKCC2 in mammalian cells fails to confirm the dominant-negative effect of the AF splice variant.
2009,
Pubmed
,
Xenbase
Isenring,
Comparison of Na-K-Cl cotransporters. NKCC1, NKCC2, and the HEK cell Na-L-Cl cotransporter.
1998,
Pubmed
Isenring,
Ion and bumetanide binding by the Na-K-Cl cotransporter. Importance of transmembrane domains.
1997,
Pubmed
Ji,
Rare independent mutations in renal salt handling genes contribute to blood pressure variation.
2008,
Pubmed
Kunchaparty,
Defective processing and expression of thiazide-sensitive Na-Cl cotransporter as a cause of Gitelman's syndrome.
1999,
Pubmed
,
Xenbase
Kuznetsov,
Folding of secretory and membrane proteins.
1998,
Pubmed
Li,
Predicting Protein Disorder for N-, C-, and Internal Regions.
1999,
Pubmed
Linding,
Protein disorder prediction: implications for structural proteomics.
2003,
Pubmed
Parvin,
Regions in the cytosolic C-terminus of the secretory Na(+)-K(+)-2Cl(-) cotransporter NKCC1 are required for its homodimerization.
2007,
Pubmed
Pedersen,
Intramolecular and intermolecular fluorescence resonance energy transfer in fluorescent protein-tagged Na-K-Cl cotransporter (NKCC1): sensitivity to regulatory conformational change and cell volume.
2008,
Pubmed
Plata,
Isoforms of the Na-K-2Cl cotransporter in murine TAL II. Functional characterization and activation by cAMP.
1999,
Pubmed
,
Xenbase
Plata,
Functional properties of the apical Na+-K+-2Cl- cotransporter isoforms.
2002,
Pubmed
,
Xenbase
Sali,
Comparative protein modelling by satisfaction of spatial restraints.
1993,
Pubmed
Shaffer,
Structure and mechanism of a Na+-independent amino acid transporter.
2009,
Pubmed
Simon,
Bartter's syndrome, hypokalaemic alkalosis with hypercalciuria, is caused by mutations in the Na-K-2Cl cotransporter NKCC2.
1996,
Pubmed
Starremans,
Mutations in the human Na-K-2Cl cotransporter (NKCC2) identified in Bartter syndrome type I consistently result in nonfunctional transporters.
2003,
Pubmed
,
Xenbase
Subramanya,
Toward an understanding of hypertension resistance.
2011,
Pubmed
Vargas-Poussou,
Novel molecular variants of the Na-K-2Cl cotransporter gene are responsible for antenatal Bartter syndrome.
1998,
Pubmed
Warmuth,
X-ray structure of the C-terminal domain of a prokaryotic cation-chloride cotransporter.
2009,
Pubmed
Zaarour,
A highly conserved motif at the COOH terminus dictates endoplasmic reticulum exit and cell surface expression of NKCC2.
2009,
Pubmed
