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Su XT, Reyes JV, Lackey AE, Demirci H, Bachmann S, Maeoka Y, Cornelius RJ, McCormick JA, Yang CL, Jung HJ, Welling PA, Nelson JW, Ellison DH. Enriched Single-Nucleus RNA-Sequencing Reveals Unique Attributes of Distal Convoluted Tubule Cells. J Am Soc Nephrol 2024; 35:426-440. [PMID: 38238903 PMCID: PMC11000721 DOI: 10.1681/asn.0000000000000297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Accepted: 12/17/2023] [Indexed: 01/24/2024] Open
Abstract
SIGNIFICANCE STATEMENT High-resolution single-nucleus RNA-sequencing data indicate a clear separation between primary sites of calcium and magnesium handling within distal convoluted tubule (DCT). Both DCT1 and DCT2 express Slc12a3, but these subsegments serve distinctive functions, with more abundant magnesium-handling genes along DCT1 and more calcium-handling genes along DCT2. The data also provide insight into the plasticity of the distal nephron-collecting duct junction, formed from cells of separate embryonic origins. By focusing/changing gradients of gene expression, the DCT can morph into different physiological cell states on demand. BACKGROUND The distal convoluted tubule (DCT) comprises two subsegments, DCT1 and DCT2, with different functional and molecular characteristics. The functional and molecular distinction between these segments, however, has been controversial. METHODS To understand the heterogeneity within the DCT population with better clarity, we enriched for DCT nuclei by using a mouse line combining "Isolation of Nuclei Tagged in specific Cell Types" and sodium chloride cotransporter-driven inducible Cre recombinase. We sorted the fluorescently labeled DCT nuclei using Fluorescence-Activated Nucleus Sorting and performed single-nucleus transcriptomics. RESULTS Among 25,183 DCT cells, 75% were from DCT1 and 25% were from DCT2. In addition, there was a small population (<1%) enriched in proliferation-related genes, such as Top2a , Cenpp , and Mki67 . Although both DCT1 and DCT2 expressed sodium chloride cotransporter, magnesium transport genes were predominantly expressed along DCT1, whereas calcium, electrogenic sodium, and potassium transport genes were more abundant along DCT2. The transition between these two segments was gradual, with a transitional zone in which DCT1 and DCT2 cells were interspersed. The expression of the homeobox genes by DCT cells suggests that they develop along different trajectories. CONCLUSIONS Transcriptomic analysis of an enriched rare cell population using a genetically targeted approach clarifies the function and classification of distal cells. The DCT segment is short, can be separated into two subsegments that serve distinct functions, and is speculated to derive from different origins during development.
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Affiliation(s)
- Xiao-Tong Su
- Division of Hypertension and Nephrology, School of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Jeremiah V. Reyes
- Division of Hypertension and Nephrology, School of Medicine, Oregon Health & Science University, Portland, Oregon
- Department of Biochemistry and Molecular Biology, College of Medicine, University of the Philippines Manila, Manila, Philippines
| | - Anne E. Lackey
- Division of Hypertension and Nephrology, School of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Hasan Demirci
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Sebastian Bachmann
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Yujiro Maeoka
- Division of Hypertension and Nephrology, School of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Ryan J. Cornelius
- Division of Hypertension and Nephrology, School of Medicine, Oregon Health & Science University, Portland, Oregon
| | - James A. McCormick
- Division of Hypertension and Nephrology, School of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Chao-Ling Yang
- Division of Hypertension and Nephrology, School of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Hyun Jun Jung
- Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Paul A. Welling
- Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jonathan W. Nelson
- Division of Hypertension and Nephrology, School of Medicine, Oregon Health & Science University, Portland, Oregon
| | - David H. Ellison
- Division of Hypertension and Nephrology, School of Medicine, Oregon Health & Science University, Portland, Oregon
- Oregon Clinical and Translational Research Institute, Oregon Health & Science University, Portland, Oregon
- Renal Section, VA Portland Healthcare System, Portland, Oregon
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Maeoka Y, Nguyen LT, Sharma A, Cornelius RJ, Su XT, Gutierrez MR, Carbajal-Contreras H, Castañeda-Bueno M, Gamba G, McCormick JA. Dysregulation of the WNK4-SPAK/OSR1 pathway has a minor effect on baseline NKCC2 phosphorylation. Am J Physiol Renal Physiol 2024; 326:F39-F56. [PMID: 37881876 DOI: 10.1152/ajprenal.00100.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 10/12/2023] [Accepted: 10/13/2023] [Indexed: 10/27/2023] Open
Abstract
The with-no-lysine kinase 4 (WNK4)-sterile 20/SPS-1-related proline/alanine-rich kinase (SPAK)/oxidative stress-responsive kinase 1 (OSR1) pathway mediates activating phosphorylation of the furosemide-sensitive Na+-K+-2Cl- cotransporter (NKCC2) and the thiazide-sensitive NaCl cotransporter (NCC). The commonly used pT96/pT101-pNKCC2 antibody cross-reacts with pT53-NCC in mice on the C57BL/6 background due to a five amino acid deletion. We generated a new C57BL/6-specific pNKCC2 antibody (anti-pT96-NKCC2) and tested the hypothesis that the WNK4-SPAK/OSR1 pathway strongly regulates the phosphorylation of NCC but not NKCC2. In C57BL/6 mice, anti-pT96-NKCC2 detected pNKCC2 and did not cross-react with NCC. Abundances of pT96-NKCC2 and pT53-NCC were evaluated in Wnk4-/-, Osr1-/-, Spak-/-, and Osr1-/-/Spak-/- mice and in several models of the disease familial hyperkalemic hypertension (FHHt) in which the CUL3-KLHL3 ubiquitin ligase complex that promotes WNK4 degradation is dysregulated (Cul3+/-/Δ9, Klhl3-/-, and Klhl3R528H/R528H). All mice were on the C57BL/6 background. In Wnk4-/- mice, pT53-NCC was almost absent but pT96-NKCC2 was only slightly lower. pT53-NCC was almost absent in Spak-/- and Osr1-/-/Spak-/- mice, but pT96-NKCC2 abundance did not differ from controls. pT96-NKCC2/total NKCC2 was slightly lower in Osr1-/- and Osr1-/-/Spak-/- mice. WNK4 expression colocalized not only with NCC but also with NKCC2 in Klhl3-/- mice, but pT96-NKCC2 abundance was unchanged. Consistent with this, furosemide-induced urinary Na+ excretion following thiazide treatment was similar between Klhl3-/- and controls. pT96-NKCC2 abundance was also unchanged in the other FHHt mouse models. Our data show that disruption of the WNK4-SPAK/OSR1 pathway only mildly affects NKCC2 phosphorylation, suggesting a role for other kinases in NKCC2 activation. In FHHt models NKCC2 phosphorylation is unchanged despite higher WNK4 abundance, explaining the thiazide sensitivity of FHHt.NEW & NOTEWORTHY The renal cation cotransporters NCC and NKCC2 are activated following phosphorylation mediated by the WNK4-SPAK/OSR1 pathway. While disruption of this pathway strongly affects NCC activity, effects on NKCC2 activity are unclear since the commonly used phospho-NKCC2 antibody was recently reported to cross-react with phospho-NCC in mice on the C57BL/6 background. Using a new phospho-NKCC2 antibody specific for C57BL/6, we show that inhibition or activation of the WNK4-SPAK/OSR1 pathway in mice only mildly affects NKCC2 phosphorylation.
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Affiliation(s)
- Yujiro Maeoka
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon, United States
| | - Luan T Nguyen
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon, United States
| | - Avika Sharma
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon, United States
| | - Ryan J Cornelius
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon, United States
| | - Xiao-Tong Su
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon, United States
| | - Marissa R Gutierrez
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon, United States
| | - Héctor Carbajal-Contreras
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - María Castañeda-Bueno
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
| | - Gerardo Gamba
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Mexico City, Mexico
- Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - James A McCormick
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon, United States
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Cornelius RJ, Maeoka Y, McCormick JA. Renal effects of cullin 3 mutations causing familial hyperkalemic hypertension. Curr Opin Nephrol Hypertens 2023; 32:335-343. [PMID: 37070483 PMCID: PMC10330058 DOI: 10.1097/mnh.0000000000000891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/19/2023]
Abstract
PURPOSE OF REVIEW Mutations in the E3 ubiquitin ligase scaffold cullin 3 (CUL3) cause the disease familial hyperkalemic hypertension (FHHt) by hyperactivating the NaCl cotransporter (NCC). The effects of these mutations are complex and still being unraveled. This review discusses recent findings revealing the molecular mechanisms underlying the effects of CUL3 mutations in the kidney. RECENT FINDINGS The naturally occurring mutations that cause deletion of exon 9 (CUL3-Δ9) from CUL3 generate an abnormal CUL3 protein. CUL3-Δ9 displays increased interaction with multiple ubiquitin ligase substrate adaptors. However, in-vivo data show that the major mechanism for disease pathogenesis is that CUL3-Δ9 promotes degradation of itself and KLHL3, the specific substrate adaptor for an NCC-activating kinase. CUL3-Δ9 displays dysregulation via impaired binding to the CSN and CAND1, which cause hyperneddylation and compromised adaptor exchange, respectively. A recently discovered CUL3 mutant (CUL3-Δ474-477) displays many similarities to CUL3-Δ9 mutations but some key differences that likely account for the milder FHHt phenotype it elicits. Furthermore, recent work suggests that CUL3 mutations could have unidentified complications in patients and/or a predisposition to renal injury. SUMMARY This review summarizes recent studies highlighting advances in our understanding of the renal mechanisms by which CUL3 mutations modulate blood pressure in FHHt.
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Affiliation(s)
- Ryan J Cornelius
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon, USA
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Abstract
The study of rare monogenic forms of hypertension has led to the elucidation of important physiological pathways controlling blood pressure. Mutations in several genes cause familial hyperkalemic hypertension (also known as Gordon syndrome or pseudohypoaldosteronism type II). The most severe form of familial hyperkalemic hypertension is caused by mutations in CUL3, encoding CUL3 (Cullin 3)-a scaffold protein in an E3 ubiquitin ligase complex that tags substrates for proteasomal degradation. In the kidney, CUL3 mutations cause accumulation of the substrate WNK (with-no-lysine [K]) kinase and ultimately hyperactivation of the renal NaCl cotransporter-the target of the first-line antihypertensive thiazide diuretics. The precise mechanisms by which mutant CUL3 causes WNK kinase accumulation have been unclear, but several functional defects are likely to contribute. The hypertension seen in familial hyperkalemic hypertension also results from effects exerted by mutant CUL3 on several pathways in vascular smooth muscle and endothelium that modulate vascular tone. This review summarizes the mechanisms by which wild type and mutant CUL3 modulate blood pressure through effects on the kidney and vasculature, potential effects in the central nervous system and heart, and future directions for investigation.
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Affiliation(s)
- Yujiro Maeoka
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, OR
| | - Ryan J Cornelius
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, OR
| | - James A McCormick
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, OR
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Maeoka Y, Cornelius RJ, Ferdaus MZ, Sharma A, Nguyen LT, McCormick JA. Cullin 3 mutant causing familial hyperkalemic hypertension lacks normal activity in the kidney. Am J Physiol Renal Physiol 2022; 323:F564-F576. [PMID: 36007890 PMCID: PMC9602935 DOI: 10.1152/ajprenal.00153.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 07/27/2022] [Accepted: 08/15/2022] [Indexed: 01/07/2023] Open
Abstract
Mutations in the ubiquitin ligase scaffold protein cullin 3 (CUL3) cause the disease familial hyperkalemic hypertension (FHHt). We recently reported that in the kidney, aberrant mutant CUL3 (CUL3-Δ9) activity lowers the abundance of CUL3-Δ9 and Kelch-like 3, the CUL3 substrate adaptor for with-no-lysine kinase 4 (WNK4) and that this is mechanistically important. However, whether CUL3-Δ9 exerts additional effects on other targets that may alter renal function is unclear. Here, we sought to determine 1) whether CUL3-Δ9 expression can rescue the phenotype of renal tubule-specific Cul3 knockout mice, and 2) whether CUL3-Δ9 expression affects other CUL3 substrates. Using an inducible renal tubule-specific system, we studied two CUL3-Δ9-expressing mouse models: Cul3 knockout (Cul3-/-/Δ9) and Cul3 heterozygous background (Cul3+/-/Δ9, FHHt model). The effects of CUL3-Δ9 in these mice were compared with Cul3-/- and Cul3+/- mice. Similar to Cul3-/- mice, Cul3-/-/Δ9 mice displayed polyuria with loss of aquaporin 2 and collecting duct injury; proximal tubule injury also occurred. CUL3-Δ9 did not promote degradation of two CUL3 targets that accumulate in the Cul3-/- kidney: high-molecular-weight (HMW) cyclin E and NAD(P)H:quinone oxidoreductase 1 (NQO1) [a surrogate for the CUL3-Kelch-like ECH-associated protein 1 (KEAP1) substrate nuclear factor erythroid-2-related factor 2]. Since CUL3-Δ9 expression cannot rescue the Cul3-/- phenotype, our data suggest that CUL3-Δ9 cannot normally function in ubiquitin ligase complexes. In Cul3+/-/Δ9 mice, KEAP1 abundance did not differ but NQO1 abundance was higher, suggesting adaptor sequestration by CUL3-Δ9 in vivo. Together, our results provide evidence that in the kidney, CUL3-Δ9 completely lacks normal activity and can trap CUL3 substrate adaptors in inactive complexes.NEW & NOTEWORTHY CUL3 mutation (CUL3-Δ9) causes familial hyperkalemic hypertension (FHHt) by reducing adaptor KLHL3, impairing substrate WNK4 degradation. Whether CUL3-Δ9 affects other targets in kidneys remains unclear. We found that CUL3-Δ9 cannot degrade two CUL3 targets, cyclin E and nuclear factor erythroid-2-related factor 2 (NRF2; using a surrogate marker NQO1), or rescue injury or polyuria caused by Cul3 disruption. In an FHHt model, CUL3-Δ9 impaired NRF2 degradation without reduction of its adaptor KEAP1. Our data provide additional insights into CUL3-Δ9 function in the kidney.
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Affiliation(s)
- Yujiro Maeoka
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Ryan J Cornelius
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Mohammed Zubaerul Ferdaus
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Avika Sharma
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Luan T Nguyen
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - James A McCormick
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
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Cornelius RJ, Nelson JW, Su XT, Yang CL, Ellison DH. COP9 signalosome deletion promotes renal injury and distal convoluted tubule remodeling. Am J Physiol Renal Physiol 2022; 323:F4-F19. [PMID: 35532068 PMCID: PMC9236871 DOI: 10.1152/ajprenal.00436.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Cullin-RING ligases are a family of E3 ubiquitin ligases that control cellular processes through regulated degradation. Cullin 3 targets with-no-lysine kinase 4 (WNK4), a kinase that activates the Na+-Cl- cotransporter (NCC), the main pathway for Na+ reabsorption in the distal convoluted tubule (DCT). Mutations in the cullin 3 gene lead to familial hyperkalemic hypertension by increasing WNK4 abundance. The constitutive photomorphogenesis 9 (COP9) signalosome (CSN) regulates the activity of cullin-RING ligases by removing the ubiquitin-like protein neural precursor cell expressed developmentally downregulated protein 8. Genetic deletion of the catalytically active CSN subunit, Jab1, along the nephron in mice (KS-Jab1-/-) led to increased WNK4 abundance; however, NCC abundance was substantially reduced. We hypothesized that the reduction in NCC resulted from a cortical injury that led to hypoplasia of the segment, which counteracted WNK4 activation of NCC. To test this, we studied KS-Jab1-/- mice at weekly intervals over a period of 3 wk. The results showed that NCC abundance was unchanged until 3 wk after Jab1 deletion, at which time other DCT-specific proteins were also reduced. The kidney injury markers kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin demonstrated kidney injury immediately after Jab1 deletion; however, the damage was initially limited to the medulla. The injury progressed and expanded into the cortex 3 wk after Jab1 deletion coinciding with loss of the DCT. The data indicate that nephron-specific disruption of the cullin-RING ligase system results in a complex progression of tubule injury that leads to hypoplasia of the DCT.NEW & NOTEWORTHY Cullin 3 (CUL3) targets with-no-lysine-kinase 4 (WNK4), which activates Na+-Cl- cotransporter (NCC) in the distal convoluted tubule (DCT) of the kidney. Renal-specific genetic deletion of the constitutive photomorphogenesis 9 signalosome, an upstream regulator of CUL3, resulted in a reduction of NCC due to DCT hypoplasia, which coincided with cortical kidney injury. The data indicate that nephron-specific disruption of the cullin-RING ligase system results in a complex progression of tubule injury leading to hypoplasia of the DCT.
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Affiliation(s)
- Ryan J. Cornelius
- 1Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Jonathan W. Nelson
- 1Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Xiao-Tong Su
- 1Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Chao-Ling Yang
- 1Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - David H. Ellison
- 1Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon,2Veterans Affairs Portland Health Care System, Portland, Oregon
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Cornelius RJ, Su X, Yang C, Ellison DH. DCT‐specific COP9 Signalosome Deletion Activates the WNK4‐NCC Pathway and Mimics Familial Hyperkalemic Hypertension. FASEB J 2022. [DOI: 10.1096/fasebj.2022.36.s1.r2679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | - David H. Ellison
- Oregon Health and Science UniversityPortlandOR
- VA Portland Health Care SystemPortlandOR
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Maeoka Y, Ferdaus MZ, Cornelius RJ, Sharma A, Su XT, Miller LN, Robertson JA, Gurley SB, Yang CL, Ellison DH, McCormick JA. Combined Kelch-like 3 and Cullin 3 Degradation is a Central Mechanism in Familial Hyperkalemic Hypertension in Mice. J Am Soc Nephrol 2022; 33:584-600. [PMID: 35064051 PMCID: PMC8975056 DOI: 10.1681/asn.2021081099] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 01/10/2022] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Mutations in the ubiquitin ligase scaffold protein Cullin 3 (CUL3) gene cause the disease familial hyperkalemic hypertension (FHHt). In the kidney, mutant CUL3 (CUL3-Δ9) increases abundance of With-No-Lysine (K) Kinase 4 (WNK4), inappropriately activating sterile 20/SPS-1-related proline/alanine-rich kinase (SPAK), which then phosphorylates and hyperactivates the Na+Cl- cotransporter (NCC). The precise mechanism by which CUL3-Δ9 causes FHHt is unclear. We tested the hypothesis that reduced abundance of CUL3 and of Kelch-like 3 (KLHL3), the CUL3 substrate adaptor for WNK4, is mechanistically important. Because JAB1, an enzyme that inhibits CUL3 activity by removing the ubiquitin-like protein NEDD8, cannot interact with CUL3-Δ9, we also determined whether Jab1 disruption mimicked the effects of CUL3-Δ9 expression. METHODS We used an inducible renal tubule-specific system to generate several mouse models expressing CUL3-Δ9, mice heterozygous for both CUL3 and KLHL3 (Cul3+/-/Klhl3+/- ), and mice with short-term Jab1 disruption (to avoid renal injury associated with long-term disruption). RESULTS Renal KLHL3 was higher in Cul3-/- mice, but lower in Cul3-/-/Δ9 mice and in the Cul3+/-/Δ9 FHHt model, suggesting KLHL3 is a target for both WT and mutant CUL3. Cul3+/-/Klhl3+/- mice displayed increased WNK4-SPAK activation and phospho-NCC abundance and an FHHt-like phenotype with increased plasma [K+] and salt-sensitive blood pressure. Short-term Jab1 disruption in mice lowered the abundance of CUL3 and KLHL3 and increased the abundance of WNK4 and phospho-NCC. CONCLUSIONS Jab1-/- mice and Cul3+/-/Klhl3+/- mice recapitulated the effects of CUL3-Δ9 expression on WNK4-SPAK-NCC. Our data suggest degradation of both KLHL3 and CUL3 plays a central mechanistic role in CUL3-Δ9-mediated FHHt.
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Affiliation(s)
- Yujiro Maeoka
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Mohammed Z. Ferdaus
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Ryan J. Cornelius
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Avika Sharma
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Xiao-Tong Su
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Lauren N. Miller
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Joshua A. Robertson
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Susan B. Gurley
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Chao-Ling Yang
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University, Portland, Oregon
| | - David H. Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University, Portland, Oregon,Veterans Affairs Portland Healthcare System, Portland, Oregon
| | - James A. McCormick
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health & Science University, Portland, Oregon
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Cornelius RJ, Sharma A, Su XT, Guo JJ, McMahon JA, Ellison DH, McMahon AP, McCormick JA. A novel distal convoluted tubule-specific Cre-recombinase driven by the NaCl cotransporter gene. Am J Physiol Renal Physiol 2020; 319:F423-F435. [PMID: 32657158 DOI: 10.1152/ajprenal.00101.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cre-lox technology has revolutionized research in renal physiology by allowing site-specific genetic recombination in individual nephron segments. The distal convoluted tubule (DCT), consisting of distinct early (DCT1) and late (DCT2) segments, plays a central role in Na+ and K+ homeostasis. The only established Cre line targeting the DCT is Pvalb-Cre, which is limited by noninducibility, activity along DCT1 only, and activity in neurons. Here, we report the characterization of the first Cre line specific to the entire DCT. CRISPR/Cas9 targeting was used to introduce a tamoxifen-inducible IRES-Cre-ERT2 cassette downstream of the coding region of the Slc12a3 gene encoding the NaCl cotransporter (NCC). The resulting Slc12a3-Cre-ERT2 mice were crossed with R26R-YFP reporter mice, which revealed minimal leakiness with 6.3% of NCC-positive cells expressing yellow fluorescent protein (YFP) in the absence of tamoxifen. After tamoxifen injection, YFP expression was observed in 91.2% of NCC-positive cells and only in NCC-positive cells, revealing high recombination efficiency and DCT specificity. Crossing to R26R-TdTomato mice revealed higher leakiness (64.5%), suggesting differential sensitivity of the floxed site. Western blot analysis revealed no differences in abundances of total NCC or the active phosphorylated form of NCC in Slc12a3-Cre-ERT2 mice of either sex compared with controls. Plasma K+ and Mg2+ concentrations and thiazide-sensitive Na+ and K+ excretion did not differ in Slc12a3-Cre-ERT2 mice compared with controls when sex matched. These data suggest genetic modification had no obvious effect on NCC function. Slc12a3-Cre-ERT2 mice are the first line generated demonstrating inducible Cre recombinase activity along the entire DCT and will be a useful tool to study DCT function.
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Affiliation(s)
- Ryan J Cornelius
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Avika Sharma
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Xiao-Tong Su
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Jin-Jin Guo
- Department of Stem Cell Biology and Regenerative Medicine, Broad California Institute of Regenerative Medicine Center, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - Jill A McMahon
- Department of Stem Cell Biology and Regenerative Medicine, Broad California Institute of Regenerative Medicine Center, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon.,Veterans Affairs Portland Health Care System, Portland, Oregon
| | - Andrew P McMahon
- Department of Stem Cell Biology and Regenerative Medicine, Broad California Institute of Regenerative Medicine Center, Keck School of Medicine, University of Southern California, Los Angeles, California
| | - James A McCormick
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
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Cornelius RJ, Sharma A, Su XT, McMahon AP, Ellison DH, McCormick JA. A Novel Distal Convoluted Tubule‐Specific Tamoxifen‐Inducible Cre‐Recombinase Driven by the NaCl Cotransporter Gene. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.06565] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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11
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Abstract
The discovery of new genetic mutations that cause hypertension has illuminated previously unrecognized physiological pathways. One such regulatory pathway was identified when mutations in with no lysine kinase (WNK)4, Kelch-like 3 (KLHL3), and cullin 3 (CUL3) were shown to cause the disease familial hyperkalemic hypertension (FHHt). Mutations in all three genes upregulate the NaCl cotransporter (NCC) due to an impaired ability to degrade WNK protein through the cullin-RING-ligase (CRL) ubiquitin-proteasome system. The CUL3 FHHt mutations cause the most severe phenotype, yet the precise mechanism by which these mutations cause the disease has not been established and current proposed models are controversial. New data have identified a possible novel mechanism involving dysregulation of CUL3 activity by the COP9 signalosome (CSN). The CSN interaction with mutant CUL3 is diminished, causing hyperneddylation of the CRL. Recent work has shown that direct renal CSN impairment mimics some aspects of the CUL3 mutation, including lower KLHL3 abundance and activation of the WNK-NCC pathway. Furthermore, in vitro and in vivo studies of CSN inhibition have shown selective degradation of CRL substrate adaptors via auto-ubiquitination, allowing substrate accumulation. In this review, we will focus on recent research that highlights the role of the CSN role in CUL3 mutations that cause FHHt. We will also highlight how these results inform other recent studies of CSN dysfunction.
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Affiliation(s)
- Ryan J Cornelius
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Chao-Ling Yang
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon.,Veterans Affairs Portland Health Care System, Portland, Oregon
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Thomson MN, Cuevas CA, Bewarder TM, Dittmayer C, Miller LN, Si J, Cornelius RJ, Su XT, Yang CL, McCormick JA, Hadchouel J, Ellison DH, Bachmann S, Mutig K. WNK bodies cluster WNK4 and SPAK/OSR1 to promote NCC activation in hypokalemia. Am J Physiol Renal Physiol 2019; 318:F216-F228. [PMID: 31736353 DOI: 10.1152/ajprenal.00232.2019] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
K+ deficiency stimulates renal salt reuptake via the Na+-Cl- cotransporter (NCC) of the distal convoluted tubule (DCT), thereby reducing K+ losses in downstream nephron segments while increasing NaCl retention and blood pressure. NCC activation is mediated by a kinase cascade involving with no lysine (WNK) kinases upstream of Ste20-related proline-alanine-rich kinase (SPAK) and oxidative stress-responsive kinase-1 (OSR1). In K+ deficiency, WNKs and SPAK/OSR1 concentrate in spherical cytoplasmic domains in the DCT termed "WNK bodies," the significance of which is undetermined. By feeding diets of varying salt and K+ content to mice and using genetically engineered mouse lines, we aimed to clarify whether WNK bodies contribute to WNK-SPAK/OSR1-NCC signaling. Phosphorylated SPAK/OSR1 was present both at the apical membrane and in WNK bodies within 12 h of dietary K+ deprivation, and it was promptly suppressed by K+ loading. In WNK4-deficient mice, however, larger WNK bodies formed, containing unphosphorylated WNK1, SPAK, and OSR1. This suggests that WNK4 is the primary active WNK isoform in WNK bodies and catalyzes SPAK/OSR1 phosphorylation therein. We further examined mice carrying a kidney-specific deletion of the basolateral K+ channel-forming protein Kir4.1, which is required for the DCT to sense plasma K+ concentration. These mice displayed remnant mosaic expression of Kir4.1 in the DCT, and upon K+ deprivation, WNK bodies developed only in Kir4.1-expressing cells. We postulate a model of DCT function in which NCC activity is modulated by plasma K+ concentration via WNK4-SPAK/OSR1 interactions within WNK bodies.
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Affiliation(s)
- Martin N Thomson
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Catherina A Cuevas
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Tim M Bewarder
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Carsten Dittmayer
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Lauren N Miller
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Jinge Si
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Ryan J Cornelius
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Xiao-Tong Su
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Chao-Ling Yang
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon.,Renal Section, Veterans Affairs Portland Health Care System, Portland, Oregon
| | - James A McCormick
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Juliette Hadchouel
- Institut National de la Santé et de la Recherche Médicale, Paris Cardiovascular Research Center, Paris, France
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon.,Renal Section, Veterans Affairs Portland Health Care System, Portland, Oregon
| | - Sebastian Bachmann
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Kerim Mutig
- Department of Anatomy, Charité-Universitätsmedizin Berlin, Berlin, Germany.,I.M. Sechenov First Moscow State Medical University of the Ministry of Healthcare of the Russian Federation (Sechenovskiy University), Moscow, Russia
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13
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Abstract
PURPOSE OF REVIEW Members of the Cullin family act as scaffolds in E3 ubiquitin ligases and play a central role in mediating protein degradation. Interactions with many different substrate-binding adaptors permit Cullin-containing E3 ligases to participate in diverse cellular functions. In the kidney, one well established target of Cullin-mediated degradation is the transcription factor Nrf2, a key player in responses to oxidative stress. The goal of this review is to discuss more recent findings revealing broader roles for Cullins in the kidney. RECENT FINDINGS Cullin 3 acts as the scaffold in the E3 ligase regulating Nrf2 abundance, but was more recently shown to be mutated in the disease familial hyperkalemic hypertension. Studies seeking to elucidate the molecular mechanisms by which Cullin 3 mutations lead to dysregulation of renal sodium transport will be discussed. Disruption of Cullin 3 in mice unexpectedly causes polyuria and fibrotic injury suggesting it has additional roles in the kidney. We will also review recent transcriptomic data suggesting that other Cullins are also likely to play important roles in renal function. SUMMARY Cullins form a large and diverse family of E3 ubiquitin ligases that are likely to have many important functions in the kidney.
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Affiliation(s)
- Ryan J. Cornelius
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR
| | - Mohammed Z. Ferdaus
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR
| | - Jonathan W. Nelson
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR
| | - James A. McCormick
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University, Portland, OR
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Cornelius RJ, Nelson JW, Su X, Yang C, Ellison DH. Long‐term Disruption of the COP9 Signalosome Decreases NCC Abundance Due to Remodeling of the DCT. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.862.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | | | | | - David H. Ellison
- Oregon Health and Science UniversityPortlandOR
- VA Portland Healthcare SystemPortlandOR
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15
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Cornelius RJ, Si J, Cuevas CA, Nelson JW, Gratreak BDK, Pardi R, Yang CL, Ellison DH. Renal COP9 Signalosome Deficiency Alters CUL3-KLHL3-WNK Signaling Pathway. J Am Soc Nephrol 2018; 29:2627-2640. [PMID: 30301860 DOI: 10.1681/asn.2018030333] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 09/07/2018] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND The familial hyperkalemic hypertension (FHHt) cullin 3 (CUL3) mutant does not degrade WNK kinases normally, thereby leading to thiazide-sensitive Na-Cl cotransporter (NCC) activation. CUL3 mutant (CUL3Δ9) does not bind normally to the COP9 signalosome (CSN), a deneddylase involved in regulating cullin-RING ligases. CUL3Δ9 also caused increased degradation of the CUL3-WNK substrate adaptor kelch-like 3 (KLHL3). Here, we sought to determine how defective CSN action contributes to the CUL3Δ9 phenotype. METHODS The Pax8/LC1 mouse system was used to generate mice in which the catalytically active CSN subunit, Jab1, was deleted only along the nephron, after full development (KS-Jab1 -/-). RESULTS Western blot analysis demonstrated that Jab1 deletion increased the abundance of neddylated CUL3. Moreover, total CUL3 expression was reduced, suggesting decreased CUL3 stability. KLHL3 was almost completely absent in KS-Jab1 -/- mice. Conversely, the protein abundances of WNK1, WNK4, and SPAK kinases were substantially higher. Activation of WNK4, SPAK, and OSR1 was indicated by higher phosphorylated protein levels and translocation of the proteins into puncta, as observed by immunofluorescence. The ratio of phosphorylated NCC to total NCC was also higher. Surprisingly, NCC protein abundance was low, likely contributing to hypokalemia and Na+ and K+ wasting. Additionally, long-term Jab1 deletion resulted in kidney damage. CONCLUSIONS Together, the results indicate that deficient CSN binding contributes importantly to the FHHt phenotype. Although defective CUL3Δ9-faciliated WNK4 degradation likely contributes, dominant effects on KLHL3 may be a second factor that is necessary for the phenotype.
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Affiliation(s)
- Ryan J Cornelius
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Jinge Si
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Catherina A Cuevas
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Jonathan W Nelson
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Brittany D K Gratreak
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - Ruggero Pardi
- School of Medicine and Scientific Institute, San Raffaele University, Milan, Italy; and
| | - Chao-Ling Yang
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; .,Renal Section, Veterans Affairs Portland Health Care System, Portland, Oregon
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16
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Cornelius RJ, Zhang C, Erspamer KJ, Agbor LN, Sigmund CD, Singer JD, Yang CL, Ellison DH. Dual gain and loss of cullin 3 function mediates familial hyperkalemic hypertension. Am J Physiol Renal Physiol 2018; 315:F1006-F1018. [PMID: 29897280 PMCID: PMC6230741 DOI: 10.1152/ajprenal.00602.2017] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 05/11/2018] [Accepted: 06/07/2018] [Indexed: 12/26/2022] Open
Abstract
Familial hyperkalemic hypertension is caused by mutations in with-no-lysine kinases (WNKs) or in proteins that mediate their degradation, kelch-like 3 (KLHL3) and cullin 3 (CUL3). Although the mechanisms by which WNK and KLHL3 mutations cause the disease are now clear, the effects of the disease-causing CUL3Δ403-459 mutation remain controversial. Possible mechanisms, including hyperneddylation, altered ubiquitin ligase activity, decreased association with the COP9 signalosome (CSN), and increased association with and degradation of KLHL3 have all been postulated. Here, we systematically evaluated the effects of Cul3Δ403-459 using cultured kidney cells. We first identified that the catalytically active CSN subunit jun activation domain-binding protein-1 (JAB1) does not associate with the deleted Cul3 4-helix bundle domain but instead with the adjacent α/β1 domain, suggesting that altered protein folding underlies the impaired binding. Inhibition of deneddylation with JAB1 siRNA increased Cul3 neddylation and decreased KLHL3 abundance, similar to the Cul3 mutant. We next determined that KLHL3 degradation has both ubiquitin ligase-dependent and -independent components. Proteasomal KLHL3 degradation was enhanced by Cul3Δ403-459; however, autophagic degradation was also upregulated by this Cul3 mutant. Finally, to evaluate whether deficient substrate adaptor was responsible for the disease, we restored KLHL3 to wild-type (WT) Cul3 levels. In the absence of WT Cul3, WNK4 was not degraded, demonstrating that Cul3Δ403-459 itself cannot degrade WNK4; conversely, when WT Cul3 was present, as in diseased humans, WNK4 degradation was restored. In conclusion, deletion of exon 9 from Cul3 generates a protein that is itself ubiquitin-ligase defective but also capable of enhanced autophagocytic KLHL3 degradation, thereby exerting dominant-negative effects on the WT allele.
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Affiliation(s)
- Ryan J Cornelius
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University , Portland, Oregon
| | - Chong Zhang
- Department of Nephrology, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine , Shanghai , China
| | - Kayla J Erspamer
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University , Portland, Oregon
| | - Larry N Agbor
- Department of Pharmacology, UIHC Center for Hypertension Research, Carver College of Medicine, University of Iowa , Iowa City, Iowa
| | - Curt D Sigmund
- Department of Pharmacology, UIHC Center for Hypertension Research, Carver College of Medicine, University of Iowa , Iowa City, Iowa
| | - Jeffrey D Singer
- Department of Biology, Portland State University , Portland, Oregon
| | - Chao-Ling Yang
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University , Portland, Oregon
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University , Portland, Oregon
- Veterans Affairs Portland Health Care System, Portland, Oregon
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17
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Cornelius RJ, Zhang C, Erspamer KJ, Singer JD, Yang C, Ellison DH. Dual Gain and Loss of Cullin 3 Function Mediates Familial Hyperkalemic Hypertension. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.716.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | - Chong Zhang
- Shanghai Jiao Tong University School of MedicineShanghaiPeople's Republic of China
| | | | | | | | - David H. Ellison
- VA Portland Healthcare SystemPorltandOR
- Oregon Health and Science UniversityPortlandOR
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18
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Cornelius RJ, Yang C, Ellison DH. Kidney‐Specific COP9 Signalosome (CSN) Deletion Mimics FHHt Effects on WNK/NCC Signaling. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.716.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | - David H. Ellison
- VA Portland Healthcare SystemPortlandOR
- Oregon Health and Science UniversityPortlandOR
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19
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Terker AS, Castañeda-Bueno M, Ferdaus MZ, Cornelius RJ, Erspamer KJ, Su XT, Miller LN, McCormick JA, Wang WH, Gamba G, Yang CL, Ellison DH. With no lysine kinase 4 modulates sodium potassium 2 chloride cotransporter activity in vivo. Am J Physiol Renal Physiol 2018; 315:F781-F790. [PMID: 29412704 DOI: 10.1152/ajprenal.00485.2017] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
With no lysine kinase 4 (WNK4) is essential to activate the thiazide-sensitive NaCl cotransporter (NCC) along the distal convoluted tubule, an effect central to the phenotype of familial hyperkalemic hypertension. Although effects on potassium and sodium channels along the connecting and collecting tubules have also been documented, WNK4 is typically believed to have little role in modulating sodium chloride reabsorption along the thick ascending limb of the loop of Henle. Yet wnk4-/- mice (knockout mice lacking WNK4) do not demonstrate the hypocalciuria typical of pure distal convoluted tubule dysfunction. Here, we tested the hypothesis that WNK4 also modulates bumetanide-sensitive Na-K-2Cl cotransporter (NKCC2) function along the thick ascending limb. We confirmed that w nk4-/- mice are hypokalemic and waste sodium chloride, but are also normocalciuric. Results from Western blots suggested that the phosphorylated forms of both NCC and NKCC2 were in lower abundance in wnk4-/- mice than in controls. This finding was confirmed by immunofluorescence microscopy. Although the initial response to furosemide was similar in wnk4-/- mice and controls, the response was lower in the knockout mice when reabsorption along the distal convoluted tubule was inhibited. Using HEK293 cells, we showed that WNK4 increases the abundance of phosphorylated NKCC2. More supporting evidence that WNK4 may modulate NKCC2 emerges from a mouse model of WNK4-mediated familial hyperkalemic hypertension in which more phosphorylated NKCC2 is present than in controls. These data indicate that WNK4, in addition to modulating NCC, also modulates NKCC2, contributing to its physiological function in vivo.
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Affiliation(s)
- Andrew S Terker
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Maria Castañeda-Bueno
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán , Mexico City, Mexico
| | - Mohammed Z Ferdaus
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Ryan J Cornelius
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Kayla J Erspamer
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Xiao-Tong Su
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Lauren N Miller
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - James A McCormick
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Gerardo Gamba
- Department of Nephrology and Mineral Metabolism, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán , Mexico City, Mexico.,Molecular Physiology Unit, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma University de México , Mexico City, Mexico.,Tecnológico de Monterrey, Escuela de Medicina y de Ciencias de la Salud, Monterrey, México
| | - Chao-Ling Yang
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
| | - David H Ellison
- Division of Nephrology & Hypertension, Department of Medicine, Oregon Health & Science University , Portland, Oregon
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Cornelius RJ, Wang B, Wang-France J, Sansom SC. Maintaining K + balance on the low-Na +, high-K + diet. Am J Physiol Renal Physiol 2016; 310:F581-F595. [PMID: 26739887 DOI: 10.1152/ajprenal.00330.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 12/29/2015] [Indexed: 02/07/2023] Open
Abstract
A low-Na+, high-K+ diet (LNaHK) is considered a healthier alternative to the "Western" high-Na+ diet. Because the mechanism for K+ secretion involves Na+ reabsorptive exchange for secreted K+ in the distal nephron, it is not understood how K+ is eliminated with such low Na+ intake. Animals on a LNaHK diet produce an alkaline load, high urinary flows, and markedly elevated plasma ANG II and aldosterone levels to maintain their K+ balance. Recent studies have revealed a potential mechanism involving the actions of alkalosis, urinary flow, elevated ANG II, and aldosterone on two types of K+ channels, renal outer medullary K+ and large-conductance K+ channels, located in principal and intercalated cells. Here, we review these recent advances.
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Affiliation(s)
- Ryan J Cornelius
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon; and
| | - Bangchen Wang
- Department of Cellular/Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Jun Wang-France
- Department of Cellular/Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Steven C Sansom
- Department of Cellular/Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
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21
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Wen D, Yuan Y, Cornelius RJ, Li H, Warner PC, Wang B, Wang-France J, Boettger T, Sansom SC. Deficient acid handling with distal RTA in the NBCe2 knockout mouse. Am J Physiol Renal Physiol 2015; 309:F523-30. [PMID: 26109087 DOI: 10.1152/ajprenal.00163.2015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 06/22/2015] [Indexed: 12/20/2022] Open
Abstract
In many circumstances, the pathogenesis of distal renal tubular acidosis (dRTA) is not understood. In the present study, we report that a mouse model lacking the electrogenic Na(+)-HCO3 (-) cotransporter [NBCe2/Slc4a5; NBCe2 knockout (KO) mice] developed dRTA after an oral acid challenge. NBCe2 expression was identified in the connecting tubule (CNT) of wild-type mice, and its expression was significantly increased after acid loading. NBCe2 KO mice did not have dRTA when on a standard mouse diet. However, after acid loading, NBCe2 KO mice exhibited complete features of dRTA, characterized by insufficient urinary acidification, hyperchloremic hypokalemic metabolic acidosis, and hypercalciuria. Additional experiments showed that NBCe2 KO mice had decreased luminal transepithelial potential in the CNT, as revealed by micropuncture. Further immunofluorescence and Western blot experiments found that NBCe2 KO mice had increased expression of H(+)-ATPase B1 in the plasma membrane. These results showed that NBCe2 KO mice with acid loading developed increased urinary K(+) and Ca(2+) wasting due to decreased luminal transepithelial potential in the CNT. NBCe2 KO mice compensated to maintain systemic pH by increasing H(+)-ATPase in the plasma membrane. Therefore, defects in NBCe2 can cause dRTA, and NBCe2 has an important role to regulate urinary acidification and the transport of K(+) and Ca(2+) in the distal nephron.
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Affiliation(s)
- Donghai Wen
- Department of Cellular/Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Yang Yuan
- Department of Cellular/Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Ryan J Cornelius
- Department of Cellular/Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Huaqing Li
- Department of Cellular/Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Paige C Warner
- Department of Cellular/Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Bangchen Wang
- Department of Cellular/Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Jun Wang-France
- Department of Cellular/Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and
| | - Thomas Boettger
- Department of Cardiac Development and Remodeling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Steven C Sansom
- Department of Cellular/Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska; and
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22
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Wen D, Yuan Y, Warner PC, Wang B, Cornelius RJ, Wang-France J, Li H, Boettger T, Sansom SC. Increased Epithelial Sodium Channel Activity Contributes to Hypertension Caused by Na+-HCO3- Cotransporter Electrogenic 2 Deficiency. Hypertension 2015; 66:68-74. [PMID: 25941340 DOI: 10.1161/hypertensionaha.115.05394] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 04/14/2015] [Indexed: 11/16/2022]
Abstract
The gene SLC4A5 encodes the Na(+)-HCO3 (-) cotransporter electrogenic 2, which is located in the distal nephron. Genetically deleting Na(+)-HCO3 (-) cotransporter electrogenic 2 (knockout) causes Na(+)-retention and hypertension, a phenotype that is diminished with alkali loading. We performed experiments with acid-loaded mice and determined whether overactive epithelial Na(+) channels (ENaC) or the Na(+)-Cl(-) cotransporter causes the Na(+) retention and hypertension in knockout. In untreated mice, the mean arterial pressure was higher in knockout, compared with wild-type (WT); however, treatment with amiloride, a blocker of ENaC, abolished this difference. In contrast, hydrochlorothiazide, an inhibitor of Na(+)-Cl(-) cotransporter, decreased mean arterial pressure in WT, but not knockout. Western blots showed that quantity of plasmalemmal full-length ENaC-α was significantly higher in knockout than in WT. Amiloride treatment caused a 2-fold greater increase in Na(+) excretion in knockout, compared with WT. In knockout, but not WT, amiloride treatment decreased plasma [Na(+)] and urinary K(+) excretion, but increased hematocrit and plasma [K(+)] significantly. Micropuncture with microelectrodes showed that the [K(+)] was significantly higher and the transepithelial potential (Vte) was significantly lower in the late distal tubule of the knockout compared with WT. The reduced Vte in knockout was amiloride sensitive and therefore revealed an upregulation of electrogenic ENaC-mediated Na(+) reabsorption in this segment. These results show that, in the absence of Na(+)-HCO3 (-) cotransporter electrogenic 2 in the late distal tubule, acid-loaded mice exhibit disinhibition of ENaC-mediated Na(+) reabsorption, which results in Na(+) retention, K(+) wasting, and hypertension.
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Affiliation(s)
- Donghai Wen
- From the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha (D.W., Y.Y., P.C.W., B.W., R.J.C., J.W.-F., H.L., S.C.S.); and Department of Cardiac Development and Remodeling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (T.B.)
| | - Yang Yuan
- From the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha (D.W., Y.Y., P.C.W., B.W., R.J.C., J.W.-F., H.L., S.C.S.); and Department of Cardiac Development and Remodeling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (T.B.)
| | - Paige C Warner
- From the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha (D.W., Y.Y., P.C.W., B.W., R.J.C., J.W.-F., H.L., S.C.S.); and Department of Cardiac Development and Remodeling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (T.B.)
| | - Bangchen Wang
- From the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha (D.W., Y.Y., P.C.W., B.W., R.J.C., J.W.-F., H.L., S.C.S.); and Department of Cardiac Development and Remodeling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (T.B.)
| | - Ryan J Cornelius
- From the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha (D.W., Y.Y., P.C.W., B.W., R.J.C., J.W.-F., H.L., S.C.S.); and Department of Cardiac Development and Remodeling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (T.B.)
| | - Jun Wang-France
- From the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha (D.W., Y.Y., P.C.W., B.W., R.J.C., J.W.-F., H.L., S.C.S.); and Department of Cardiac Development and Remodeling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (T.B.)
| | - Huaqing Li
- From the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha (D.W., Y.Y., P.C.W., B.W., R.J.C., J.W.-F., H.L., S.C.S.); and Department of Cardiac Development and Remodeling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (T.B.)
| | - Thomas Boettger
- From the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha (D.W., Y.Y., P.C.W., B.W., R.J.C., J.W.-F., H.L., S.C.S.); and Department of Cardiac Development and Remodeling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (T.B.)
| | - Steven C Sansom
- From the Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha (D.W., Y.Y., P.C.W., B.W., R.J.C., J.W.-F., H.L., S.C.S.); and Department of Cardiac Development and Remodeling, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany (T.B.).
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Cornelius RJ, Wen D, Li H, Yuan Y, Wang-France J, Warner PC, Sansom SC. Low Na, high K diet and the role of aldosterone in BK-mediated K excretion. PLoS One 2015; 10:e0115515. [PMID: 25607984 PMCID: PMC4301648 DOI: 10.1371/journal.pone.0115515] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 11/25/2014] [Indexed: 12/23/2022] Open
Abstract
A low Na, high K diet (LNaHK) is associated with a low rate of cardiovascular (CV) disease in many societies. Part of the benefit of LNaHK relies on its diuretic effects; however, the role of aldosterone (aldo) in the diuresis is not understood. LNaHK mice exhibit an increase in renal K secretion that is dependent on the large, Ca-activated K channel, (BK-α with accessory BK-β4; BK-α/β4). We hypothesized that aldo causes an osmotic diuresis by increasing BK-α/β4-mediated K secretion in LNaHK mice. We found that the plasma aldo concentration (P[aldo]) was elevated by 10-fold in LNaHK mice compared with control diet (Con) mice. We subjected LNaHK mice to either sham surgery (sham), adrenalectomy (ADX) with low aldo replacement (ADX-LA), or ADX with high aldo replacement (ADX-HA). Compared to sham, the urinary flow, K excretion rate, transtubular K gradient (TTKG), and BK-α and BK-β4 expressions, were decreased in ADX-LA, but not different in ADX-HA. BK-β4 knockout (β4KO) and WT mice exhibited similar K clearance and TTKG in the ADX-LA groups; however, in sham and ADX-HA, the K clearance and TTKG of β4KO were less than WT. In response to amiloride treatment, the osmolar clearance was increased in WT Con, decreased in WT LNaHK, and unchanged in β4KO LNaHK. These data show that the high P[aldo] of LNaHK mice is necessary to generate a high rate of BK-α/β4-mediated K secretion, which creates an osmotic diuresis that may contribute to a reduction in CV disease.
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Affiliation(s)
- Ryan J. Cornelius
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Donghai Wen
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Huaqing Li
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Yang Yuan
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Jun Wang-France
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Paige C. Warner
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Steven C. Sansom
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- * E-mail:
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Wen D, Cornelius RJ, Sansom SC. Interacting influence of diuretics and diet on BK channel-regulated K homeostasis. Curr Opin Pharmacol 2013; 15:28-32. [PMID: 24721651 DOI: 10.1016/j.coph.2013.11.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 11/04/2013] [Indexed: 12/26/2022]
Abstract
Large conductance, Ca-activated K channels (BK) are abundantly located in cells of vasculature, glomerulus, and distal nephron, where they are involved in maintaining blood volume, blood pressure, and K homeostasis. In mesangial cells and smooth muscle cells of vessels, the BK-α pore associates with BK-β1 subunits and regulates contraction in a Ca-mediated feedback manner. The BK-β1 also resides in connecting tubule cells of the nephron. BK-β1 knockout mice (β1KO) exhibit fluid retention, hypertension, and compromised K handling. The BK-α/β4 resides in acid/base transporting intercalated cells (IC) of the distal nephron, where they mediate K secretion in mammals on a high K, alkaline diet. BK-α expression in IC is increased by a high K diet via aldosterone. The BK-β4 subunit and alkaline urine are necessary for the luminal expression and function of BK-α in mouse IC. In distal nephron cells, membrane BK-α expression is inhibited by WNK4 in in vitro expression systems, indicating a role in the hyperkalemic phenotype in patients with familial hyperkalemic hypertension type 2 (FHHt2). β1KO and BK-β4 knockout mice (β4KO) are hypertensive because of exaggerated epithelial Na channels (ENaC) mediated Na retention in an effort to secrete K via only renal outer medullary K channels (ROMK). BK hypertension is resistant to thiazides and furosemide, and would be more amenable to ENaC and aldosterone inhibiting drugs. Activators of BK-α/β1 or BK-α/β4 might be effective blood pressure lowering agents for a subset of hypertensive patients. Inhibitors of renal BK would effectively spare K in patients with Bartter Syndrome, a renal K wasting disease.
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Affiliation(s)
- Donghai Wen
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Ryan J Cornelius
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States
| | - Steven C Sansom
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE, United States.
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25
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Abstract
In the distal nephron, the large-conductance Ca-activated K (BK) channel, comprised of a pore-forming-α (BK-α) and the BK-β4 subunit, promotes K excretion when mice are maintained on a high-K alkaline diet (HK-alk). We examined whether BK-β4 and the acid-base status regulate apical membrane expression of BK-α in the cortical (CCD) and medullary collecting ducts (MCD) using immunohistochemical analysis (IHC) and Western blot. With the use of IHC, BK-α of mice on acontrol diet localized mostly cytoplasmically in intercalated cells (IC) of the CCD and in the perinuclear region of both principle cells (PC) and IC of the MCD. HK-alk wild-type mice (WT), but not BK-β4 knockout mice (β4KO), exhibited increased apical BK-α in both the CCD and MCD. When given a high-K acidic diet (HK-Cl), BK-α expression increased but remained cytoplasmic in the CCD and perinuclear in the MCD of both WT and β4KO. Western blot confirmed that total BK-α expression was enhanced by either HK-alk or HK-Cl but only increased in the plasma membrane with HK-alk. Compared with controls, mice drinking NaHCO3 water exhibited more apical BK-α and total cellular BK-β4. Spironolactone given to mice on HK-alk significantly reduced K secretion and decreased total cellular BK-α but did not affect cellular BK-β4 and apical BK-α. Experiments with MDCK-C11 cells indicated that BK-β4 stabilizes surface BK-α by inhibiting degradation through a lysosomal pathway. These data suggest that aldosterone mediates a high-K-induced increase in BK-α and urinary alkalinization increases BK-β4 expression, which promotes the apical localization of BK-α.
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Affiliation(s)
- Donghai Wen
- Dept. of Cellular and Integrative Physiology, 985850 Nebraska Medical Center, Omaha, NE 68198-5850.
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Cornelius RJ, Wen D, Sansom SC. Aldosterone (aldo) and epithelial Na channel (ENaC)‐ dependent K secretion by BK‐α/β4 in the distal nephron (DN). FASEB J 2013. [DOI: 10.1096/fasebj.27.1_supplement.lb860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Ryan J Cornelius
- Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
| | - Donghai Wen
- Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
| | - Steve C Sansom
- Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
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Cornelius RJ, Wen D, Hatcher LI, Sansom SC. Bicarbonate promotes BK-α/β4-mediated K excretion in the renal distal nephron. Am J Physiol Renal Physiol 2012; 303:F1563-71. [PMID: 22993067 DOI: 10.1152/ajprenal.00490.2012] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Ca-activated K channels (BK), which are stimulated by high distal nephron flow, are utilized during high-K conditions to remove excess K. Because BK predominantly reside with BK-β4 in acid/base-transporting intercalated cells (IC), we determined whether BK-β4 knockout mice (β4KO) exhibit deficient K excretion when consuming a high-K alkaline diet (HK-alk) vs. high-K chloride diet (HK-Cl). When wild type (WT) were placed on HK-alk, but not HK-Cl, renal BK-β4 expression increased (Western blot). When WT and β4KO were placed on HK-Cl, plasma K concentration ([K]) was elevated compared with control K diets; however, K excretion was not different between WT and β4KO. When HK-alk was consumed, the plasma [K] was lower and K clearance was greater in WT compared with β4KO. The urine was alkaline in mice on HK-alk; however, urinary pH was not different between WT and β4KO. Immunohistochemical analysis of pendrin and V-ATPase revealed the same increases in β-IC, comparing WT and β4KO on HK-alk. We found an amiloride-sensitive reduction in Na excretion in β4KO, compared with WT, on HK-alk, indicating enhanced Na reabsorption as a compensatory mechanism to secrete K. Treating mice with an alkaline, Na-deficient, high-K diet (LNaHK) to minimize Na reabsorption exaggerated the defective K handling of β4KO. When WT on LNaHK were given NH(4)Cl in the drinking water, K excretion was reduced to the magnitude of β4KO on LNaHK. These results show that WT, but not β4KO, efficiently excretes K on HK-alk but not on HK-Cl and suggest that BK-α/β4-mediated K secretion is promoted by bicarbonaturia.
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Affiliation(s)
- Ryan J Cornelius
- Dept. of Cellular and Integrative Physiology, Nebraska Medical Center, Omaha, NE 68198-5850, USA
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Contreras JI, Hatcher LI, Cornelius RJ, Sansom SC. Role of Aquaporin2 (Aqp2) in the increased urinary flow of K‐adapted mice. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.881.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Jacob I. Contreras
- Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
| | - Lori I Hatcher
- Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
| | - Ryan J. Cornelius
- Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
| | - Steven C. Sansom
- Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
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Cornelius RJ, Hatcher LI, Echtenkamp KM, Contreras JI, Sansom SC. Bicarbonate transport drives Na‐independent K secretion (NIKS) via BK‐α/β4 in β‐intercalated cells (IC‐β). FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.867.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Ryan J Cornelius
- Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
| | - Lori I Hatcher
- Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
| | - Kari M Echtenkamp
- Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
- University of Nebraska at OmahaOmahaNE
| | - Jacob I Contreras
- Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
| | - Steve C Sansom
- Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
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Echtenkamp KM, Hatcher LI, Cornelius RJ, Samson SC. The trans‐tubular K gradients (TTKG) reveal long‐term adaptation in mice to Na deficient, high K diets. FASEB J 2012. [DOI: 10.1096/fasebj.26.1_supplement.867.6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Kari M Echtenkamp
- Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
- University of Nebraska at OmahaOmahaNE
| | - Lori I Hatcher
- Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
| | - Ryan J Cornelius
- Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
| | - Steven C Samson
- Cellular and Integrative PhysiologyUniversity of Nebraska Medical CenterOmahaNE
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Hatcher L, Grimm PR, Cornelius RJ, Holtzclaw JD, Sansom SC. Mediation of Na‐independent K secretion by intercalated cell BK‐α/β4. FASEB J 2011. [DOI: 10.1096/fasebj.25.1_supplement.1041.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Abstract
Increased flow in the distal nephron induces K secretion through the large-conductance, calcium-activated K channel (BK), which is primarily expressed in intercalated cells (IC). Since flow also increases ATP release from IC, we hypothesized that purinergic signaling has a role in shear stress (τ; 10 dynes/cm(2)) -induced, BK-dependent, K efflux. We found that 10 μM ATP led to increased IC Ca concentration, which was significantly reduced in the presence of the P(2) receptor blocker suramin or calcium-free buffer. ATP also produced BK-dependent K efflux, and IC volume decrease. Suramin inhibited τ-induced K efflux, suggesting that K efflux is at least partially dependent on purinergic signaling. BK-β4 small interfering (si) RNA, but not nontarget siRNA, decreased ATP secretion and both ATP-dependent and τ-induced K efflux. Similarly, carbenoxolone (25 μM), which blocks connexins, putative ATP pathways, blocked τ-induced K efflux and ATP secretion. Compared with BK-β4(-/-) mice, wild-type mice with high distal flows exhibited significantly more urinary ATP excretion. These data demonstrate coupled electrochemical efflux between K and ATP as part of the mechanism for τ-induced ATP release in IC.
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Affiliation(s)
- J David Holtzclaw
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska 68198-5850, USA
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