The sodium/proton exchanger NHA2 regulates blood pressure through a WNK4-NCC dependent pathway in the kidney

Anderegg, Manuel; Albano, Giuseppe; Hanke, Daniela; Deisl, Christine; Uehlinger, Dominik E.; Brandt, Simone; Bhardwaj, Rajesh; Hediger, Matthias A.; Fuster, Daniel

doi:10.1016/j.kint.2020.08.023

Cited by 11 publications

(21 citation statements)

References 65 publications

(69 reference statements)

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“…Based on tissue expression, genome location and phloretin sensitivity, human NHA2 was proposed to be the candidate gene for the Na + (Li + ) countertransport activity associated with the development of essential hypertension and diabetes in humans [9][10][11][12] . Indeed, NHA2 aids in sodium reabsorption in the kidney 13,14 and is a critical component of the with-no-lysine kinase 4-sodium-chloride cotransporter (WNK4-NCC) pathway in the regulation of blood pressure 14 . Furthermore, in vitro and in vivo studies show that NHA2 contributes to β-cell insulin secretion 15 .…”

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confidence: 99%

Structure, mechanism and lipid-mediated remodeling of the mammalian Na+/H+ exchanger NHA2

Matsuoka

Fudim

Jung

et al. 2022

Nat Struct Mol Biol

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The Na+/H+ exchanger SLC9B2, also known as NHA2, correlates with the long-sought-after Na+/Li+ exchanger linked to the pathogenesis of diabetes mellitus and essential hypertension in humans. Despite the functional importance of NHA2, structural information and the molecular basis for its ion-exchange mechanism have been lacking. Here we report the cryo-EM structures of bison NHA2 in detergent and in nanodiscs, at 3.0 and 3.5 Å resolution, respectively. The bison NHA2 structure, together with solid-state membrane-based electrophysiology, establishes the molecular basis for electroneutral ion exchange. NHA2 consists of 14 transmembrane (TM) segments, rather than the 13 TMs previously observed in mammalian Na+/H+ exchangers (NHEs) and related bacterial antiporters. The additional N-terminal helix in NHA2 forms a unique homodimer interface with a large intracellular gap between the protomers, which closes in the presence of phosphoinositol lipids. We propose that the additional N-terminal helix has evolved as a lipid-mediated remodeling switch for the regulation of NHA2 activity.

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confidence: 99%

Structure, mechanism and lipid-mediated remodeling of the mammalian Na+/H+ exchanger NHA2

Matsuoka

Fudim

Jung

et al. 2022

Nat Struct Mol Biol

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“…6B). Since we observed this phenomenon in yeast cells, which may lack some regulatory mechanisms or protein interactions that regulate the activity of Hs NHA2 in mammalian cells (Anderegg et al, 2021), the first 40-50 amino acids of the protein instead perform an autoinhibitory function in Hs NHA2.…”

Section: Resultsmentioning

confidence: 93%

“…In the kidney, NHA2 localizes to distal convoluted tubules, where it is critical for electrolyte (sodium reabsorption) and blood pressure homeostasis (Fuster et al, 2008; Kondapalli et al, 2017). In 2021, Anderegg et al corroborated the NHA2 role in blood pressure regulation in mice, and identified it as critical for the maintenance of serine-threonine with-no-lysine kinase 4 (WNK4) levels, and thus ultimately for the activity of the Na + /Cl − cotransporter NCC in the distal convoluted tubules of the kidney (Anderegg et al, 2021). Increased NHA2 expression also promotes cyst development in an in vitro model of polycystic kidney disease (Prasad et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Allosteric links between the hydrophilic N-terminus and transmembrane core of human Na⁺/H⁺ antiporter NHA2

Velázquez

Průša

Masrati

et al. 2022

Preprint

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The human Na+/H+ antiporter NHA2 (SLC9B2) transports Na+ or Li+ across the plasma membrane in exchange for protons, and is implicated in various pathologies. It is a 537 amino acids protein with an 82 residues long hydrophilic cytoplasmic N-terminus followed by a transmembrane part comprising 14 transmembrane helices. We optimized the functional expression of HsNHA2 in the plasma membrane of a salt-sensitive Saccharomyces cerevisiae strain and characterized a set of mutated or truncated versions of HsNHA2 in terms of their substrate specificity, transport activity, localization and protein stability. We identified a highly conserved proline 246, located in the core of the protein, as being crucial for ion selectivity. The replacement of P246 with serine or threonine resulted in antiporters with altered substrate specificity and increased resistance to the HsNHA2-specific inhibitor phloretin that were not only highly active at an acidic pH of 4.0 (like the native antiporter), but also at neutral pH. We also experimentally confirmed the importance of a putative salt bridge between E215 and R432 for antiporter function and structural integrity. Truncations of the first 50 - 70 residues of the N-terminus doubled the transport activity of HsNHA2, whilst changes in the charge at positions E47, E56, K57, or K58 decreased the antiporter’s transport activity. Thus, the hydrophilic N-terminal part of the protein appears to allosterically autoinhibit its cation transport. Our data also show this in vivo approach to be useful for a rapid screening of SNP’s effect on HsNHA2 activity.

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“…Prior to collections, mice were allowed 2 days to adapt to the metabolic cages. HCT (Sigma-Aldrich, St. Louis, MO) or vehicle (1:1 mixture of 0.9% NaCl solution with DMSO) was applied as a single intraperitoneal injection and urine was collected for the next 6 h (56).…”

Section: Animal Studiesmentioning

confidence: 99%

Thiazides induce glucose intolerance through inhibition of mitochondrial carbonic anhydrase 5b in β-cells

Kucharczyk

Albano

Deisl

et al. 2022

Preprint

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Thiazides are associated with glucose intolerance and new onset diabetes mellitus, but the molecular mechanisms remain elusive. The aim of this study was to decipher the molecular basis of thiazide-induced glucose intolerance. In mice, hydrochlorothiazide induced a pathological glucose tolerance, characterized by reduced first phase insulin secretion but normal insulin sensitivity. In vitro, thiazides inhibited glucose- and sulfonylurea-stimulated insulin secretion in islets and the murine β-cell line Min6 at pharmacologically relevant concentrations. Inhibition of insulin secretion by thiazides was CO2/HCO3--dependent, not additive to unselective carbonic anhydrase (CA) inhibition with acetazolamide and independent of extracellular potassium. In contrast, insulin secretion was unaltered in islets of mice lacking the known molecular thiazide targets NCC (SLC12A3) or NDCBE (SLC4A8). CA expression profiling with subsequent knock-down of individual CA isoforms suggested mitochondrial CA5b as molecular target. In support of these findings, thiazides significantly attenuated Krebs cycle anaplerosis through reduction of mitochondrial oxalacetate synthesis. CA5b KO mice were resistant to thiazide-induced glucose intolerance, and insulin secretion of islets isolated from CA5b KO mice was unaffected by thiazides. In summary, our study reveals attenuated insulin secretion due to inhibition of the mitochondrial CA5b isoform in β-cells as molecular mechanism of thiazide-induced glucose intolerance.

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The sodium/proton exchanger NHA2 regulates blood pressure through a WNK4-NCC dependent pathway in the kidney

Abstract: The sodium/proton exchanger NHA2 regulates blood pressure through a WNK4-NCC dependent pathway in the kidney.

Cited by 11 publications

References 65 publications

Structure, mechanism and lipid-mediated remodeling of the mammalian Na+/H+ exchanger NHA2

Structure, mechanism and lipid-mediated remodeling of the mammalian Na+/H+ exchanger NHA2

Allosteric links between the hydrophilic N-terminus and transmembrane core of human Na⁺/H⁺ antiporter NHA2

Thiazides induce glucose intolerance through inhibition of mitochondrial carbonic anhydrase 5b in β-cells

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The sodium/proton exchanger NHA2 regulates blood pressure through a WNK4-NCC dependent pathway in the kidney

Abstract: The sodium/proton exchanger NHA2 regulates blood pressure through a WNK4-NCC dependent pathway in the kidney.

Cited by 11 publications

References 65 publications

Structure, mechanism and lipid-mediated remodeling of the mammalian Na+/H+ exchanger NHA2

Structure, mechanism and lipid-mediated remodeling of the mammalian Na+/H+ exchanger NHA2

Allosteric links between the hydrophilic N-terminus and transmembrane core of human Na+/H+ antiporter NHA2

Thiazides induce glucose intolerance through inhibition of mitochondrial carbonic anhydrase 5b in β-cells

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Allosteric links between the hydrophilic N-terminus and transmembrane core of human Na⁺/H⁺ antiporter NHA2