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Zhao K, Han T, Jia L, Wen L, Gao R, Li X. Exploring new horizons: angiotensin II, angiotensin II type 1 receptor, and renal outer medullary potassium channel interaction in distal convoluted tubule. Kidney Res Clin Pract 2025; 44:461-480. [PMID: 39384346 PMCID: PMC12066336 DOI: 10.23876/j.krcp.24.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 05/09/2024] [Accepted: 05/09/2024] [Indexed: 10/11/2024] Open
Abstract
BACKGROUND This study investigates angiotensin II (Ang II)'s regulatory mechanism on renal outer medullary potassium channel (ROMK) activity in the distal convoluted tubule (DCT) during low potassium intake, focusing on the janus kinase 2 (JAK2) pathway activation mediated by the Ang II type 1 receptor (AT1R). METHODS Utilizing a low potassium diet mouse model, various methods including patch clamping, reverse transcription-quantitative polymerase chain reaction, Western blotting, and immunohistochemical staining were applied to analyze ROMK channel activity and the expression of related proteins. RESULTS The findings reveal that Ang II inhibits ROMK activity in the DCT2 membrane through AT1R activation, with the JAK2 pathway playing a central role. Further, inhibiting JAK2 reverses this effect, indicating its potential in hypertension treatment. CONCLUSION This study provides novel insights into the role of Ang II in renal potassium excretion and hypertension pathophysiology.
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Affiliation(s)
- Kun Zhao
- Basic Medical Science College, Qiqihar Medical University, Qiqihar, China
| | - Tiantian Han
- Pharmacy College, Qiqihar Medical University, Qiqihar, China
| | - Linzhen Jia
- Pharmacy College, Qiqihar Medical University, Qiqihar, China
| | - Libo Wen
- Basic Medical Science College, Qiqihar Medical University, Qiqihar, China
| | - Renjun Gao
- The Sixth Department of Cardiology, The Second Affiliated Hospital of Qiqihar Medical University, Qiqihar, China
| | - Xue Li
- Basic Medical Science College, Qiqihar Medical University, Qiqihar, China
- Heilongjiang Provincial Key Laboratory of Medicine-food Homologous Resources and Metabolic Disease Prevention and Control, Qiqihar Medical University, Qiqihar, China
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Maeoka Y, Bradford T, Su XT, Sharma A, Yang CL, Ellison DH, McCormick JA, Cornelius RJ. Distal convoluted tubule-specific disruption of the COP9 signalosome but not its regulatory target cullin 3 causes tubular injury. Am J Physiol Renal Physiol 2024; 327:F667-F682. [PMID: 39205661 PMCID: PMC11483082 DOI: 10.1152/ajprenal.00138.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2024] [Revised: 08/07/2024] [Accepted: 08/23/2024] [Indexed: 09/04/2024] Open
Abstract
The disease familial hyperkalemic hypertension (FHHt; also known as Gordon syndrome) is caused by aberrant accumulation of with-no-lysine kinase (WNK4) activating the NaCl cotransporter (NCC) in the distal convoluted tubule (DCT) of the kidney. Mutations in cullin 3 (CUL3) cause FHHt by disrupting interaction with the deneddylase COP9 signalosome (CSN). Deletion of Cul3 or Jab1 (the catalytically active CSN subunit) along the entire nephron causes a partial FHHt phenotype with activation of the WNK4-STE20/SPS1-related proline/alanine-rich kinase (SPAK)-NCC pathway. However, progressive kidney injury likely prevents hypertension, hyperkalemia, and hyperchloremic metabolic acidosis associated with FHHt. We hypothesized that DCT-specific deletion would more closely model the disease. We used Slc12a3-Cre-ERT2 mice to delete Cul3 (DCT-Cul3-/-) or Jab1 (DCT-Jab1-/-) only in the DCT and examined the mice after short- and long-term deletion. Short-term DCT-specific knockout of both Cul3 and Jab1 mice caused elevated WNK4, pSPAKS373, and pNCCT53 abundance. However, neither model demonstrated changes in plasma K+, Cl-, or total CO2, even though no injury was present. Long-term DCT-Jab1-/- mice showed significantly lower NCC and parvalbumin abundance and a higher abundance of kidney injury molecule-1, a marker of proximal tubule injury. No injury or reduction in NCC or parvalbumin was observed in long-term DCT-Cul3-/- mice. In summary, the prevention of injury outside the DCT did not lead to a complete FHHt phenotype despite activation of the WNK4-SPAK-NCC pathway, possibly due to insufficient NCC activation. Chronically, only DCT-Jab1-/- mice developed tubule injury and atrophy of the DCT, suggesting a direct JAB1 effect or dysregulation of other cullins as mechanisms for injury.NEW & NOTEWORTHY CUL3 degrades WNK4, which prevents activation of NCC in the DCT. CSN regulation of CUL3 is impaired in the disease FHHt, causing accumulation of WNK4. Short-term DCT-specific disruption of CUL3 or the CSN in mice resulted in activation of the WNK4-SPAK-NCC pathway but not hyperkalemic metabolic acidosis found in FHHt. Tubule injury was observed only after long-term CSN disruption. The data suggest that disruption of other cullins may be the cause for the injury.
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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
| | - Tanner Bradford
- 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
| | - Avika Sharma
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon, United States
| | - Chao-Ling Yang
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon, United States
| | - David H Ellison
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University, Portland, Oregon, United States
- LeDucq Transatlantic Network of Excellence, Boston, Massachusetts, United States
| | - James A McCormick
- 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
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3
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Kelch-like protein 3 in human disease and therapy. Mol Biol Rep 2022; 49:9813-9824. [PMID: 35585379 DOI: 10.1007/s11033-022-07487-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 04/11/2022] [Accepted: 04/19/2022] [Indexed: 10/18/2022]
Abstract
Kelch-like protein 3 (KLHL3) is a substrate adaptor of Cullin3-RING ubiquitin ligase (CRL3), and KLHL3-CUL3 complex plays a vital role in the ubiquitination of specific substrates. Mutations and abnormal post-translational modifications of KLHL3-CUL3 affect substrate ubiquitination and may related to the pathogenesis of Gordon syndrome (GS), Primary Hyperparathyroidism (PHPT), Diabetes Mellitus (DM), Congenital Heart Disease (CHD), Pre-eclampsia (PE) and even cancers. Therefore, it is essential to understand the function and molecular mechanisms of KLHL3-CUL3 for the treatment of related diseases. In this review, we summary the structure and function of KLHL3-CUL3, the effect of KLHL3-CUL3 mutations and aberrant modifications in GS, PHPT, DM, CHD and PE. Moreover, we noted a possible role of KLHL3-CUL3 in carcinogenesis and provided ideas for targeting KLHL3-CUL3 for related disease treatment.
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Polidoro JZ, Rebouças NA, Girardi ACC. The Angiotensin II Type 1 Receptor-Associated Protein Attenuates Angiotensin II-Mediated Inhibition of the Renal Outer Medullary Potassium Channel in Collecting Duct Cells. Front Physiol 2021; 12:642409. [PMID: 34054566 PMCID: PMC8160308 DOI: 10.3389/fphys.2021.642409] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 04/16/2021] [Indexed: 11/13/2022] Open
Abstract
Adjustments in renal K+ excretion constitute a central mechanism for K+ homeostasis. The renal outer medullary potassium (ROMK) channel accounts for the major K+ secretory route in collecting ducts during basal conditions. Activation of the angiotensin II (Ang II) type 1 receptor (AT1R) by Ang II is known to inhibit ROMK activity under the setting of K+ dietary restriction, underscoring the role of the AT1R in K+ conservation. The present study aimed to investigate whether an AT1R binding partner, the AT1R-associated protein (ATRAP), impacts Ang II-mediated ROMK regulation in collecting duct cells and, if so, to gain insight into the potential underlying mechanisms. To this end, we overexpressed either ATRAP or β-galactosidase (LacZ; used as a control), in M-1 cells, a model line of cortical collecting duct cells. We then assessed ROMK channel activity by employing a novel fluorescence-based microplate assay. Experiments were performed in the presence of 10−10 M Ang II or vehicle for 40 min. We observed that Ang II-induced a significant inhibition of ROMK in LacZ, but not in ATRAP-overexpressed M-1 cells. Inhibition of ROMK-mediated K+ secretion by Ang II was accompanied by lower ROMK cell surface expression. Conversely, Ang II did not affect the ROMK-cell surface abundance in M-1 cells transfected with ATRAP. Additionally, diminished response to Ang II in M-1 cells overexpressing ATRAP was accompanied by decreased c-Src phosphorylation at the tyrosine 416. Unexpectedly, reduced phospho-c-Src levels were also found in M-1 cells, overexpressing ATRAP treated with vehicle, suggesting that ATRAP can also downregulate this kinase independently of Ang II-AT1R activation. Collectively, our data support that ATRAP attenuates inhibition of ROMK by Ang II in collecting duct cells, presumably by reducing c-Src activation and blocking ROMK internalization. The potential role of ATRAP in K+ homeostasis and/or disorders awaits further investigation.
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Affiliation(s)
| | - Nancy Amaral Rebouças
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
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Murthy M, O’Shaughnessy KM. Modified HEK cells simulate DCT cells in their sensitivity and response to changes in extracellular K. Physiol Rep 2019; 7:e14280. [PMID: 31762176 PMCID: PMC6875656 DOI: 10.14814/phy2.14280] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
A potassium (K+ ) rich diet is known to have an antihypertensive effect that has been embodied by the NHLBI in the DASH diet. However, the molecular basis for this blood pressure-lowering effect has been unclear, until a recent study proposed a model in which the DCT cells of the kidney regulate their salt transport in response to variations in intracellular chloride ([Cl- ]i ), which are directly regulated by serum K+ . With the knowledge that WNK proteins are Cl- sensors, and are a part of the WNK/SPAK/NCC signaling cascade which regulates the NCC, the main salt transporter in the distal nephron, we examined the effect of serum K+ on the ([Cl- ]i ) and, in turn its effect on the WNK4 signaling pathway in a "modified HEK 293T" cell line. Using a fluorescence-based approach in this cell line, we have shown that the membrane potential of the cell membrane is sensitive to the small changes in external KCl within the physiological range (2-5 mM), thus functioning as a K+ electrode. When the extracellular K+ was progressively increased (2-5 mM), the membrane depolarization lead to a subsequent increase in [Cl- ]i measured by fluorescence quenching of an intracellular chloride sensor. Increase in extracellular [K] resulted in a decrease in the phosphorylation of the WNK4 protein and its downstream targets, SPAK and NCC. This confirms that small changes in serum K can affect WNK4/SPAK/NCC signaling and transcellular Na+ flux through the DCT and provide a possible mechanism by which a K-rich DASH diet could reduce blood pressure.
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Affiliation(s)
- Meena Murthy
- Division of Experimental Medicine and ImmunotherapeuticsDepartment of MedicineUniversity of CambridgeCambridgeUK
| | - Kevin M. O’Shaughnessy
- Division of Experimental Medicine and ImmunotherapeuticsDepartment of MedicineUniversity of CambridgeCambridgeUK
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6
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Cornelius RJ, Ferdaus MZ, Nelson JW, McCormick JA. Cullin-Ring ubiquitin ligases in kidney health and disease. Curr Opin Nephrol Hypertens 2019; 28:490-497. [PMID: 31313673 PMCID: PMC6686897 DOI: 10.1097/mnh.0000000000000527] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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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Benchoula K, Khatib A, Jaffar A, Ahmed QU, Sulaiman WMAW, Wahab RA, El-Seedi HR. The promise of zebrafish as a model of metabolic syndrome. Exp Anim 2019; 68:407-416. [PMID: 31118344 PMCID: PMC6842808 DOI: 10.1538/expanim.18-0168] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Metabolic syndrome is a cluster including hyperglycaemia, obesity, hypertension, and
hypertriglyceridaemia as a result of biochemical and physiological alterations and can
increase the risk of cardiovascular disease and diabetes. Fundamental research on this
disease requires validated animal models. One potential animal model that is rapidly
gaining in popularity is zebrafish (Danio rerio). The use of zebrafish as
an animal model conveys several advantages, including high human genetic homology,
transparent embryos and larvae that allow easier visualization. This review discusses how
zebrafish models contribute to the development of metabolic syndrome studies. Different
diseases in the cluster of metabolic syndrome, such as hyperglycaemia, obesity, diabetes,
and hypertriglyceridaemia, have been successfully studied using zebrafish; and the model
is promising for hypertension and cardiovascular metabolic-related diseases due to its
genetic similarity to mammals. Genetic mutation, chemical induction, and dietary
alteration are among the tools used to improve zebrafish models. This field is expanding,
and thus, more effective and efficient techniques are currently developed to fulfil the
increasing demand for thorough investigations.
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Affiliation(s)
- Khaled Benchoula
- Department of Basic Medical Sciences, Kulliyyah of Pharmacy, International Islamic University Malaysia, Sultan Ahmad Shah Street, Kuantan 25200, Pahang, Malaysia
| | - Alfi Khatib
- Pharmacognosy Research Group, Department of Pharmaceutical Chemistry, Kulliyyah of Pharmacy, International Islamic University Malaysia, Sultan Ahmad Shah Street, Kuantan 25200, Pahang, Malaysia.,Central Research and Animal Facility (CREAM), Kulliyyah of Science, International Islamic University Malaysia, Sultan Ahamad Shah Street, Kuantan 25200, Pahang, Malaysia
| | - Ashika Jaffar
- School of Biosciences & Technology, VIT University, Vellore 632014, India
| | - Qamar Udin Ahmed
- Pharmacognosy Research Group, Department of Pharmaceutical Chemistry, Kulliyyah of Pharmacy, International Islamic University Malaysia, Sultan Ahmad Shah Street, Kuantan 25200, Pahang, Malaysia
| | - Wan Mohd Azizi Wan Sulaiman
- Department of Basic Medical Sciences, Kulliyyah of Pharmacy, International Islamic University Malaysia, Sultan Ahmad Shah Street, Kuantan 25200, Pahang, Malaysia
| | - Ridhwan Abd Wahab
- Kulliyah of Allied Health Science, International Islamic University Malaysia, Sultan Ahmad Shah Street, Kuantan 25200, Pahang, Malaysia
| | - Hesham R El-Seedi
- Pharmacognosy Group, Department of Medicinal Chemistry, Biomedical Centre, Uppsala University, Box 574, SE-751 23 Uppsala, Sweden.,Alrayan Medical colleges, Medina 42541, Kingdom of Saudi Arabia
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Lin CM, Cheng CJ, Yang SS, Tseng MH, Yen MT, Sung CC, Lin SH. Generation and analysis of a mouse model of pseudohypoaldosteronism type II caused by KLHL3 mutation in BTB domain. FASEB J 2018; 33:1051-1061. [PMID: 30148674 DOI: 10.1096/fj.201801023r] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The Kelch-like 3 ( KLHL3) mutations contributed to the most common causative genes in patients with pseudohypoaldosteronism type II (PHAII); however, the molecular mechanisms of PHAII-causing mutations in BTB domain of KLHL3 in vivo have not been investigated. We generated and analyzed Klhl3 knock-in (KI) mice carrying a missense M131V mutation in the BTB domain (corresponding to human KLHL3 M78V mutation). Klhl3M131V/+ KI mice exhibited typical PHAII phenotype with an exaggerated diuretic response to hydrochlorothiazide. Their kidney tissues showed an unchanged KLHL3, decreased cullin 3 (Cul3), and increased with-no-lysine kinases (WNKs) WNK1 and WNK4 along with an enhanced downstream ste20-related proline/alanine-rich kinase/oxidative stress response kinase 1-N(K)CC phosphorylation. Their Cul3 protein in the cytosol of distal convoluted tubule cells was also significantly attenuated on immunogold-labeling electron microscopy. In microdissected renal tubules, Klhl3M131V/+ KI mice expressed high levels of Wnk4 mRNA in the distal nephron. In vitro coimmunoprecipitation showed the KLHL3 BTB domain mutation retained intact interaction with WNKs but reduced binding to Cul3, thus leading to the increased abundance of total WNKs. In summary, Klhl3M131V/+ KI mice feature typical PHAII with a simultaneous increase of WNK1 and WNK4 through the impaired KLHL3 BTB domain binding to Cul3.-Lin, C.-M., Cheng, C.-J., Yang, S.-S., Tseng, M.-H., Yen, M.-T., Sung, C.-C., Lin, S.-H. Generation and analysis of a mouse model of pseudohypoaldosteronism type II caused by KLHL3 mutation in BTB domain.
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Affiliation(s)
- Chien-Ming Lin
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan.,Department of Pediatrics, National Defense Medical Center, Taipei, Taiwan
| | - Chih-Jen Cheng
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Sung-Sen Yang
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan.,Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Min-Hua Tseng
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan.,Division of Pediatric Nephrology, Department of Pediatrics, Chang Gung Memorial Hospital, Taoyuan, Taiwan; and
| | - Ming-Tso Yen
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan.,Division of Nephrology, Department of Medicine, Cathay General Hospital, Taipei, Taiwan
| | - Chih-Chien Sung
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan.,Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Shih-Hua Lin
- Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan.,Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
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Murthy M, Kurz T, O'Shaughnessy KM. ROMK expression remains unaltered in a mouse model of familial hyperkalemic hypertension caused by the CUL3Δ403-459 mutation. Physiol Rep 2016; 4:4/13/e12850. [PMID: 27378813 PMCID: PMC4945836 DOI: 10.14814/phy2.12850] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 06/09/2016] [Indexed: 01/18/2023] Open
Abstract
Familial hyperkalemic hypertension (FHHt) is a rare inherited form of salt‐dependent hypertension caused by mutations in proteins that regulate the renal Na+‐Cl‐ cotransporter NCC. Mutations in four genes have been reported to cause FHHt including CUL3 (Cullin3) that encodes a component of a RING E3 ligase. Cullin‐3 binds to WNK kinase‐bound KLHL3 (the substrate recognition subunit of the ubiquitin ligase complex) to promote ubiquitination and proteasomal degradation of WNK kinases. Deletion of exon 9 from CUL3 (affecting residues 403‐459, CUL3Δ403‐459) causes a severe form of FHHt (PHA2E) that is recapitulated closely in a knock‐in mouse model. The loss of functionality of CUL3Δ403‐459 and secondary accumulation of WNK kinases causes substantial NCC activation. This accounts for the hypertension in FHHt but the origin of the hyperkalemia is less clear. Hence, we explored the impact of CUL3Δ403‐459 on expression of the distal secretory K channel, ROMK, both in vitro and in vivo. We found that expressing wild‐type but not the CUL3Δ403‐459 mutant form of CUL3 prevented the suppression of ROMK currents by WNK4 expressed in Xenopus oocytes. The mutant CUL3 protein was also unable to affect ROMK‐EGFP protein expression at the surface of mouse M‐1 cortical collecting duct (CCD) cells. The effects of CUL3 on ROMK expression in both oocytes and M‐1 CCD cells was reduced by addition of the neddylation inhibitor, MLN4924. This confirms that neddylation is important for CUL3 activity. Nevertheless, in our knock‐in mouse model expressing CUL3Δ403‐459 we could not show any alteration in ROMK expression by either western blotting whole kidney lysates or confocal microscopy of kidney sections. This suggests that the hyperkalemia in our knock‐in mouse and human PHA2E subjects with the CUL3Δ403‐459 mutation is not caused by reduced ROMK expression in the distal nephron.
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Affiliation(s)
- Meena Murthy
- Division of Experimental Medicine and Immunotherapeutics, Department of Medicine, University of Cambridge, Cambridge, CB2 2QQ, United Kingdom
| | - Thimo Kurz
- MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences University of Dundee, Dow Street, Dundee DD15EH, Scotland, United Kingdom
| | - Kevin M O'Shaughnessy
- Division of Experimental Medicine and Immunotherapeutics, Department of Medicine, University of Cambridge, Cambridge, CB2 2QQ, United Kingdom
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