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Dilmen E, Orhon I, Jansen J, Hoenderop JGJ. Advancements in kidney organoids and tubuloids to study (dys)function. Trends Cell Biol 2024; 34:299-311. [PMID: 37865608 DOI: 10.1016/j.tcb.2023.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 09/14/2023] [Accepted: 09/27/2023] [Indexed: 10/23/2023]
Abstract
The rising prevalence of kidney diseases urges the need for novel therapies. Kidney organoids and tubuloids are advanced in vitro models and have recently been described as promising tools to study kidney (patho)physiology. Recent developments have shown their application in disease modeling, drug screening, and nephrotoxicity. These applications rely on their ability to mimic (dys)function in vitro including endocrine activity and drug, electrolyte, and water transport. This review provides an overview of these emerging kidney models and focuses on the most recent developments that utilize their functional capabilities. In addition, we cover current limitations and provide future perspectives for this rapidly evolving field, including what these functional properties mean for translational and personalized medicine now and in the future.
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Affiliation(s)
- E Dilmen
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - I Orhon
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - J Jansen
- Department of Internal Medicine, Nephrology, and Transplantation, Erasmus Medical Center, Rotterdam, The Netherlands; Institute of Experimental Medicine and Systems Biology, University Hospital RWTH Aachen, Aachen, Germany
| | - J G J Hoenderop
- Department of Medical BioSciences, Radboud University Medical Center, Nijmegen, The Netherlands.
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Dutta P, Hakimi S, Layton AT. How the kidney regulates magnesium: a modelling study. ROYAL SOCIETY OPEN SCIENCE 2024; 11:231484. [PMID: 38511086 PMCID: PMC10951724 DOI: 10.1098/rsos.231484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 01/23/2024] [Accepted: 02/15/2024] [Indexed: 03/22/2024]
Abstract
The kidneys are crucial for maintaining Mg2+ homeostasis. Along the proximal tubule and thick ascending limb, Mg2+ is reabsorbed paracellularly, while along the distal convoluted tubule (DCT), Mg2+ is reabsorbed transcellularly via transient receptor potential melastatin 6 (TRPM6). TRPM6 and other renal transporter expressions are regulated by sex hormones. To investigate renal Mg2 handling, we have developed sex-specific computational models of electrolyte transport along rat superficial nephron. Model simulations indicated that along the proximal tubule and thick ascending limb, Mg2+ and Na+ transport occur parallelly, but they are dissociated along the DCT. In addition, our models predicted higher paracellular Mg2+ permeability in females to attain similar cortical thick ascending limb fractional Mg2+ reabsorption in both sexes. Furthermore, DCT fractional Mg2+ reabsorption is higher in females than in males, allowing females to better fine-tune Mg2+ excretion. We validated our models by simulating the administration of three classes of diuretics. The model predicted significantly increased, marginally increased and significantly decreased Mg2+ excretions for loop, thiazide and K-sparing diuretics, respectively, aligning with experimental findings. The models can be used to conduct in silico studies on kidney adaptations to Mg2+ homeostasis alterations during conditions such as pregnancy, diabetes and chronic kidney disease.
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Affiliation(s)
- Pritha Dutta
- Department of Applied Mathematics, University of Waterloo, Waterloo, OntarioN2L 3G1, Canada
| | - Shervin Hakimi
- Department of Applied Mathematics, University of Waterloo, Waterloo, OntarioN2L 3G1, Canada
| | - Anita T. Layton
- Department of Applied Mathematics, University of Waterloo, Waterloo, OntarioN2L 3G1, Canada
- Department of Biology, University of Waterloo, Waterloo, OntarioN2L 3G1, Canada
- Cheriton School of Computer Science, University of Waterloo, Waterloo, OntarioN2L 3G1, Canada
- School of Pharmacology, University of Waterloo, Waterloo, OntarioN2L 3G1, Canada
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Hoogstraten CA, Hoenderop JG, de Baaij JHF. Mitochondrial Dysfunction in Kidney Tubulopathies. Annu Rev Physiol 2024; 86:379-403. [PMID: 38012047 DOI: 10.1146/annurev-physiol-042222-025000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Mitochondria play a key role in kidney physiology and pathology. They produce ATP to fuel energy-demanding water and solute reabsorption processes along the nephron. Moreover, mitochondria contribute to cellular health by the regulation of autophagy, (oxidative) stress responses, and apoptosis. Mitochondrial abundance is particularly high in cortical segments, including proximal and distal convoluted tubules. Dysfunction of the mitochondria has been described for tubulopathies such as Fanconi, Gitelman, and Bartter-like syndromes and renal tubular acidosis. In addition, mitochondrial cytopathies often affect renal (tubular) tissues, such as in Kearns-Sayre and Leigh syndromes. Nevertheless, the mechanisms by which mitochondrial dysfunction results in renal tubular diseases are only scarcely being explored. This review provides an overview of mitochondrial dysfunction in the development and progression of kidney tubulopathies. Furthermore, it emphasizes the need for further mechanistic investigations to identify links between mitochondrial function and renal electrolyte reabsorption.
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Affiliation(s)
- Charlotte A Hoogstraten
- Department of Medical Biosciences, Radboud University Medical Center, Nijmegen, The Netherlands;
| | - Joost G Hoenderop
- Department of Medical Biosciences, Radboud University Medical Center, Nijmegen, The Netherlands;
| | - Jeroen H F de Baaij
- Department of Medical Biosciences, Radboud University Medical Center, Nijmegen, The Netherlands;
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Gadoth A, Nisnboym M, Alcalay Y, Zubkov A, Schwartz I, Schwartz D, Abboud M, Rubinek T, Yossepowitch O, Weinstein T. Electrolyte Imbalance in Anti-LGI1 Encephalitis: It Is Not All in Your Head. NEUROLOGY(R) NEUROIMMUNOLOGY & NEUROINFLAMMATION 2023; 10:e200155. [PMID: 37591767 PMCID: PMC10434828 DOI: 10.1212/nxi.0000000000200155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 06/27/2023] [Indexed: 08/19/2023]
Abstract
BACKGROUND AND OBJECTIVES Antileucine-rich glioma-inactivated 1 (anti-LGI1) autoimmune encephalitis was first described in 2010 and is today the most common type of limbic encephalitis. During the course of the disease, 60%-88% of the patients develop hyponatremia. The etiology of the sodium disorder is unclear, often presumed to be the result of the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Other electrolyte abnormalities have not been reported in association with anti-LGI1 antibody encephalitis. Due to the presence of hypomagnesemia and hypophosphatemia in our patients, we set out to try to find the expression of LGI1 protein in the kidney as an explanation for these abnormalities. METHODS We reviewed the medical files of all patients diagnosed with anti-LGI1 antibody encephalitis, at the Department of Neurology in the Tel Aviv Medical Center between January 2011 and December 2020, exploring for electrolyte abnormalities. Using tissue staining, Western blot, mass spectrometry, and RNA expression techniques, we tried to demonstrate the expression of LGI1 protein in the human kidney. RESULTS We identified 15 patients diagnosed with anti-LGI1 antibody encephalitis. Their average age was 65 years (44-80), and 9 were male individuals. Thirteen of the 15 patients (87%) developed varying degrees of hyponatremia. Laboratory studies demonstrated low serum osmolality, low serum blood urea nitrogen, and low uric acid, with a high urinary sodium and inappropriately high urine osmolality, supporting the presumable diagnosis of SIADH. One patient with hyponatremia that was tested, had high levels of copeptin, supporting the diagnosis of SIADH. In addition to hyponatremia, 7 patients (47%) exhibited other electrolyte abnormalities; 5 patients (33%) had overt hypophosphatemia, 4 patients (27%) had overt hypomagnesemia, and 2 other patients (13%) had borderline low magnesium levels. Western blot analysis of human kidney lysate, mass spectrometry, and qRT-PCR failed to demonstrate the expression of LGI1 protein in the kidney. DISCUSSION Hyponatremia in patients with anti-LGI1 antibody encephalitis is due to SIADH as previously assumed. Other electrolyte abnormalities such as hypomagnesemia and hypophosphatemia occur in at least 40% of patients and may be another clue for the diagnosis of anti-LGI1 antibody encephalitis. Because we failed to demonstrate LGI1 expression in the kidney, the results of our study suggest that renal losses lead to these disturbances, most probably due to SIADH.
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Affiliation(s)
- Avi Gadoth
- From the Department of Neurology (A.G.), Encephalitis Center, Tel-Aviv Medical Center; Department of Neurology (M.N.Z.), Sourasky Tel Aviv Medical Center, Sackler School of Medicine, Tel Aviv University; Encephalitis Center (Y.A.), Immunology Laboratory, Sourasky Tel Aviv Medical Center; Department of Pathology (A.Z.), Tel Aviv Medical Center; Department of Nephrology (I.S., D.S., T.W.); Oncology Division (M.A., T.R.); and Department of Urology (O.Y.), Sourasky, Tel-Aviv Medical Center, Sackler School of Medicine, Tel Aviv University, Israel.
| | - Michal Nisnboym
- From the Department of Neurology (A.G.), Encephalitis Center, Tel-Aviv Medical Center; Department of Neurology (M.N.Z.), Sourasky Tel Aviv Medical Center, Sackler School of Medicine, Tel Aviv University; Encephalitis Center (Y.A.), Immunology Laboratory, Sourasky Tel Aviv Medical Center; Department of Pathology (A.Z.), Tel Aviv Medical Center; Department of Nephrology (I.S., D.S., T.W.); Oncology Division (M.A., T.R.); and Department of Urology (O.Y.), Sourasky, Tel-Aviv Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Yifat Alcalay
- From the Department of Neurology (A.G.), Encephalitis Center, Tel-Aviv Medical Center; Department of Neurology (M.N.Z.), Sourasky Tel Aviv Medical Center, Sackler School of Medicine, Tel Aviv University; Encephalitis Center (Y.A.), Immunology Laboratory, Sourasky Tel Aviv Medical Center; Department of Pathology (A.Z.), Tel Aviv Medical Center; Department of Nephrology (I.S., D.S., T.W.); Oncology Division (M.A., T.R.); and Department of Urology (O.Y.), Sourasky, Tel-Aviv Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Asia Zubkov
- From the Department of Neurology (A.G.), Encephalitis Center, Tel-Aviv Medical Center; Department of Neurology (M.N.Z.), Sourasky Tel Aviv Medical Center, Sackler School of Medicine, Tel Aviv University; Encephalitis Center (Y.A.), Immunology Laboratory, Sourasky Tel Aviv Medical Center; Department of Pathology (A.Z.), Tel Aviv Medical Center; Department of Nephrology (I.S., D.S., T.W.); Oncology Division (M.A., T.R.); and Department of Urology (O.Y.), Sourasky, Tel-Aviv Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Idit Schwartz
- From the Department of Neurology (A.G.), Encephalitis Center, Tel-Aviv Medical Center; Department of Neurology (M.N.Z.), Sourasky Tel Aviv Medical Center, Sackler School of Medicine, Tel Aviv University; Encephalitis Center (Y.A.), Immunology Laboratory, Sourasky Tel Aviv Medical Center; Department of Pathology (A.Z.), Tel Aviv Medical Center; Department of Nephrology (I.S., D.S., T.W.); Oncology Division (M.A., T.R.); and Department of Urology (O.Y.), Sourasky, Tel-Aviv Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Doron Schwartz
- From the Department of Neurology (A.G.), Encephalitis Center, Tel-Aviv Medical Center; Department of Neurology (M.N.Z.), Sourasky Tel Aviv Medical Center, Sackler School of Medicine, Tel Aviv University; Encephalitis Center (Y.A.), Immunology Laboratory, Sourasky Tel Aviv Medical Center; Department of Pathology (A.Z.), Tel Aviv Medical Center; Department of Nephrology (I.S., D.S., T.W.); Oncology Division (M.A., T.R.); and Department of Urology (O.Y.), Sourasky, Tel-Aviv Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Marana Abboud
- From the Department of Neurology (A.G.), Encephalitis Center, Tel-Aviv Medical Center; Department of Neurology (M.N.Z.), Sourasky Tel Aviv Medical Center, Sackler School of Medicine, Tel Aviv University; Encephalitis Center (Y.A.), Immunology Laboratory, Sourasky Tel Aviv Medical Center; Department of Pathology (A.Z.), Tel Aviv Medical Center; Department of Nephrology (I.S., D.S., T.W.); Oncology Division (M.A., T.R.); and Department of Urology (O.Y.), Sourasky, Tel-Aviv Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Tamar Rubinek
- From the Department of Neurology (A.G.), Encephalitis Center, Tel-Aviv Medical Center; Department of Neurology (M.N.Z.), Sourasky Tel Aviv Medical Center, Sackler School of Medicine, Tel Aviv University; Encephalitis Center (Y.A.), Immunology Laboratory, Sourasky Tel Aviv Medical Center; Department of Pathology (A.Z.), Tel Aviv Medical Center; Department of Nephrology (I.S., D.S., T.W.); Oncology Division (M.A., T.R.); and Department of Urology (O.Y.), Sourasky, Tel-Aviv Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Ofer Yossepowitch
- From the Department of Neurology (A.G.), Encephalitis Center, Tel-Aviv Medical Center; Department of Neurology (M.N.Z.), Sourasky Tel Aviv Medical Center, Sackler School of Medicine, Tel Aviv University; Encephalitis Center (Y.A.), Immunology Laboratory, Sourasky Tel Aviv Medical Center; Department of Pathology (A.Z.), Tel Aviv Medical Center; Department of Nephrology (I.S., D.S., T.W.); Oncology Division (M.A., T.R.); and Department of Urology (O.Y.), Sourasky, Tel-Aviv Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
| | - Talia Weinstein
- From the Department of Neurology (A.G.), Encephalitis Center, Tel-Aviv Medical Center; Department of Neurology (M.N.Z.), Sourasky Tel Aviv Medical Center, Sackler School of Medicine, Tel Aviv University; Encephalitis Center (Y.A.), Immunology Laboratory, Sourasky Tel Aviv Medical Center; Department of Pathology (A.Z.), Tel Aviv Medical Center; Department of Nephrology (I.S., D.S., T.W.); Oncology Division (M.A., T.R.); and Department of Urology (O.Y.), Sourasky, Tel-Aviv Medical Center, Sackler School of Medicine, Tel Aviv University, Israel
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Ming L, Wang D, Zhu Y. Association of sodium intake with diabetes in adults without hypertension: evidence from the National Health and Nutrition Examination Survey 2009-2018. Front Public Health 2023; 11:1118364. [PMID: 37727604 PMCID: PMC10506081 DOI: 10.3389/fpubh.2023.1118364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 08/18/2023] [Indexed: 09/21/2023] Open
Abstract
Background Sodium is essential for human health, however the prevalence of various diseases is associated with excessive sodium intake, particularly cardiovascular disorders. However, in most countries, salt intake is much higher than the World Health Organization recommends. Several studies in recent years have revealed that high salt intake is associated with diabetes in the general population, but the association is uncertain in people who do not have hypertension. In this study, we aimed to find out whether high sodium intake increases the risk of diabetes in this particular population. Method Data were extracted from the National Health and Nutrition Examination Survey (NHANES; 2009-2018). Participants included adults aged over 20 years old who have undergone the diabetes questionnaire, and the hypertension population was excluded. In order to adjust the confounders, multivariate analysis models were built. Finally, subgroup analysis were conducted to investigate the association between sodium intake and diabetes separately. Result In the present study, 7,907 participants are included (3,920 female and 3,987 male), and 512 (6.48%) individuals reported diabetes. The median sodium intake of the participants was 3,341 mg/d (IQR: 2498, 4,364 mg/d). A linear association between sodium intake and the prevalence of diabetes was found (p = 0.003). According to the multivariate analysis models, the odds ratio of diabetes for every 1,000 mg sodium intake increment is 1.20 (OR: 1.20, 95% CI 1.07-1.35). The highest sodium intake quartile was 1.80-fold more likely to have diabetes than the lowest quartile (OR: 1.80, 95% CI 1.17-2.76). Conclusion Our results suggest that higher sodium intake is associated with an increased risk of diabetes in the population without hypertension, and for every 1,000 mg sodium intake increment, the risk of diabetes increased by 1.20-fold. To sum up, we have provided the clue to the etiology of diabetes and further prospective research is needed to contribute recommendations for the primary prevention of diabetes in the US.
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Affiliation(s)
- Li Ming
- Department of Pediatrics, Xinqiao Hospital, Army Medical University, Chongqing, China
| | - Duan Wang
- Department of Rehabilitation, Children’s Hospital of Chongqing Medical University, Chongqing, China
| | - Yong Zhu
- Department of Pediatric Intensive Care Medicine, Zhangzhou Affiliated Hospital of Fujian Medical University, Fujian, China
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García-Castaño A, Gómez-Conde S, Gondra L, Herrero M, Aguirre M, de la Hoz AB, Castaño L, Madariaga L. Genotypic variability in patients with clinical diagnosis of Bartter syndrome type 3. Sci Rep 2023; 13:12587. [PMID: 37537162 PMCID: PMC10400606 DOI: 10.1038/s41598-023-38179-6] [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: 01/13/2023] [Accepted: 07/04/2023] [Indexed: 08/05/2023] Open
Abstract
Bartter syndrome (BS) is a salt-losing hereditary tubulopathy characterized by hypokalemic metabolic alkalosis with secondary hyperaldosteronism. Confirmatory molecular diagnosis may be difficult due to genetic heterogeneity and overlapping of clinical symptoms. The aim of our study was to describe the different molecular findings in patients with a clinical diagnosis of classic BS. We included 27 patients (26 families) with no identified pathogenic variants in CLCNKB. We used a customized Ion AmpliSeq Next-Generation Sequencing panel including 44 genes related to renal tubulopathies. We detected pathogenic or likely pathogenic variants in 12 patients (44%), reaching a conclusive genetic diagnosis. Variants in SLC12A3 were found in 6 (Gitelman syndrome). Median age at diagnosis was 14.6 years (range 0.1-31), with no history of prematurity or polyhydramnios. Serum magnesium level was low in 2 patients (33%) but urinary calcium excretion was normal or low in all, with no nephrocalcinosis. Variants in SLC12A1 were found in 3 (BS type 1); and in KCNJ1 in 1 (BS type 2). These patients had a history of polyhydramnios in 3 (75%), and the mean gestational age was 34.2 weeks (SD 1.7). The median age at diagnosis was 1.8 years (range 0.1-6). Chronic kidney disease and nephrocalcinosis were present in 1 (25%) and 3 (75%) patients, respectively. A variant in CLCN5 was found in one patient (Dent disease), and in NR3C2 in another patient (Geller syndrome). Genetic diagnosis of BS is heterogeneous as different tubulopathies can present with a similar clinical picture. The use of gene panels in these diseases becomes more efficient than the study gene by gene with Sanger sequencing.
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Affiliation(s)
- Alejandro García-Castaño
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
- CIBERDEM, CIBERER, Endo-ERN, Madrid, Spain
| | - Sara Gómez-Conde
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
- CIBERDEM, CIBERER, Endo-ERN, Madrid, Spain
- Pediatric Department, University of the Basque Country UPV/EHU, Bizkaia, Spain
| | - Leire Gondra
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
- CIBERDEM, CIBERER, Endo-ERN, Madrid, Spain
- Pediatric Department, University of the Basque Country UPV/EHU, Bizkaia, Spain
- Pediatric Nephrology Department, Cruces University Hospital, Plaza de Cruces, 48903, Barakaldo, Bizkaia, Spain
| | - María Herrero
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
- Pediatric Nephrology Department, Cruces University Hospital, Plaza de Cruces, 48903, Barakaldo, Bizkaia, Spain
| | - Mireia Aguirre
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
- Pediatric Nephrology Department, Cruces University Hospital, Plaza de Cruces, 48903, Barakaldo, Bizkaia, Spain
| | - Ana-Belén de la Hoz
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
- CIBERDEM, CIBERER, Endo-ERN, Madrid, Spain
| | - Luis Castaño
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain
- CIBERDEM, CIBERER, Endo-ERN, Madrid, Spain
- Pediatric Department, University of the Basque Country UPV/EHU, Bizkaia, Spain
| | - Leire Madariaga
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain.
- CIBERDEM, CIBERER, Endo-ERN, Madrid, Spain.
- Pediatric Department, University of the Basque Country UPV/EHU, Bizkaia, Spain.
- Pediatric Nephrology Department, Cruces University Hospital, Plaza de Cruces, 48903, Barakaldo, Bizkaia, Spain.
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Abstract
Mg2+ is essential for many cellular and physiological processes, including muscle contraction, neuronal activity, and metabolism. Consequently, the blood Mg2+ concentration is tightly regulated by balanced intestinal Mg2+ absorption, renal Mg2+ excretion, and Mg2+ storage in bone and soft tissues. In recent years, the development of novel transgenic animal models and identification of Mendelian disorders has advanced our current insight in the molecular mechanisms of Mg2+ reabsorption in the kidney. In the proximal tubule, Mg2+ reabsorption is dependent on paracellular permeability by claudin-2/12. In the thick ascending limb of Henle's loop, the claudin-16/19 complex provides a cation-selective pore for paracellular Mg2+ reabsorption. The paracellular Mg2+ reabsorption in this segment is regulated by the Ca2+-sensing receptor, parathyroid hormone, and mechanistic target of rapamycin (mTOR) signaling. In the distal convoluted tubule, the fine tuning of Mg2+ reabsorption takes place by transcellular Mg2+ reabsorption via transient receptor potential melastatin-like types 6 and 7 (TRPM6/TRPM7) divalent cation channels. Activity of TRPM6/TRPM7 is dependent on hormonal regulation, metabolic activity, and interacting proteins. Basolateral Mg2+ extrusion is still poorly understood but is probably dependent on the Na+ gradient. Cyclin M2 and SLC41A3 are the main candidates to act as Na+/Mg2+ exchangers. Consequently, disturbances of basolateral Na+/K+ transport indirectly result in impaired renal Mg2+ reabsorption in the distal convoluted tubule. Altogether, this review aims to provide an overview of the molecular mechanisms of Mg2+ reabsorption in the kidney, specifically focusing on transgenic mouse models and human hereditary diseases.
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Affiliation(s)
- Jeroen H F de Baaij
- Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
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Ilenwabor BP, Franken GAC, Sponder G, Bos C, Racay P, Kolisek M, Hoenderop JGJ, de Baaij JHF. SLC41A1 knockout mice display normal magnesium homeostasis. Am J Physiol Renal Physiol 2022; 323:F553-F563. [PMID: 36049064 DOI: 10.1152/ajprenal.00101.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Transcellular Mg2+ reabsorption in the distal convoluted tubule (DCT) of the kidneys plays an important role in maintaining systemic Mg2+ homeostasis. SLC41A1 is a Na+/Mg2+ exchanger that mediates Mg2+ efflux from cells and is hypothesized to facilitate basolateral extrusion of Mg2+ in the DCT. In this study, we generated a SLC41A1 knockout mouse model to examine the role of SLC41A1 in Mg2+ homeostasis. Slc41a1-/- mice exhibited similar serum and urine Mg2+ levels as their wild-type littermates. Dietary restriction of Mg2+ resulted in reduced serum Mg2+ concentration and urinary Mg2+ excretion, which was similar in the wild-type and knockout groups. Expression of genes encoding Mg2+ channels and transporters such as transient receptor potential melastatin 6 (Trpm6), transient receptor potential melastatin 7 (Trpm7), cyclin and CBS domain divalent metal cation transport mediator 2 (Cnnm2), and Slc41a3 were unchanged based on genotype. We investigated the potential redundancy of SLC41A1 and its homolog SLC41A3 by generating a double knockout mouse. Although Slc41a3-/- knockout mice showed significantly reduced serum Mg2+ compared with wild-type and Slc41a1-/- knockout groups, double knockout mice displayed similar serum Mg2+ levels as Slc41a3-/- knockout mice. In conclusion, our data show that SLC41A1 is not involved in the regulation of systemic Mg2+ homeostasis in mice. Our data also demonstrate that SLC41A1 does not compensate for the loss of SLC41A3, suggesting different functions of these SLC41 proteins in vivo.NEW & NOTEWORTHY SLC41A1 has been hypothesized to mediate Mg2+ extrusion in the distal convoluted tubule and thus regulate Mg2+ homeostasis. This study investigated the role of SLC41A1 in Mg2+ homeostasis in vivo using a transgenic mouse model. Our results demonstrate that SLC41A1 is not required to maintain normal Mg2+ balance in mice. We also show that SLC41A3 is more important than SLC41A1 in regulating systemic Mg2+ levels.
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Affiliation(s)
- Barnabas P Ilenwabor
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Gijs A C Franken
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Gerhard Sponder
- Institute of Veterinary Physiology, Freie Universität Berlin, Berlin, Germany
| | - Caro Bos
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Peter Racay
- Department of Medical Biochemistry, Jessenius Faculty of Medicine, Comenius University in Bratislava, Martin, Slovakia.,Biomedical Center Martin, Jessenius Faculty of Medicine, Comenius University in Bratislava, Martin, Slovakia
| | - Martin Kolisek
- Biomedical Center Martin, Jessenius Faculty of Medicine, Comenius University in Bratislava, Martin, Slovakia
| | - Joost G J Hoenderop
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jeroen H F de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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Abstract
PURPOSE OF REVIEW Gitelman syndrome is a recessive salt-wasting disorder characterized by hypomagnesemia, hypokalemia, metabolic alkalosis and hypocalciuria. The majority of patients are explained by mutations and deletions in the SLC12A3 gene, encoding the Na+-Cl--co-transporter (NCC). Recently, additional genetic causes of Gitelman-like syndromes have been identified that should be considered in genetic screening. This review aims to provide a comprehensive overview of the clinical, genetic and mechanistic aspects of Gitelman(-like) syndromes. RECENT FINDINGS Disturbed Na+ reabsorption in the distal convoluted tubule (DCT) is associated with hypomagnesemia and hypokalemic alkalosis. In Gitelman syndrome, loss-of-function mutations in SLC12A3 cause impaired NCC-mediated Na+ reabsorption. In addition, patients with mutations in CLCKNB, KCNJ10, FXYD2 or HNF1B may present with a similar phenotype, as these mutations indirectly reduce NCC activity. Furthermore, genetic investigations of patients with Na+-wasting tubulopathy have resulted in the identification of pathogenic variants in MT-TI, MT-TF, KCNJ16 and ATP1A1. These novel findings highlight the importance of cell metabolism and basolateral membrane potential for Na+ reabsorption in the DCT. SUMMARY Altogether, these findings extend the genetic spectrum of Gitelman-like electrolyte alterations. Genetic testing of patients with hypomagnesemia and hypokalemia should cover a panel of genes involved in Gitelman-like syndromes, including the mitochondrial genome.
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Affiliation(s)
- Karl P Schlingmann
- Department of General Pediatrics, University Children's Hospital, Münster, Germany
| | - Jeroen H F de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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10
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Bothe TL, Pilz N, Dippel LJ. The compass of biomedicine. Acta Physiol (Oxf) 2022; 236:e13856. [PMID: 35759342 DOI: 10.1111/apha.13856] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 06/23/2022] [Accepted: 06/23/2022] [Indexed: 11/29/2022]
Affiliation(s)
- Tomas L Bothe
- Institute of Translational Physiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Niklas Pilz
- Institute of Translational Physiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
| | - Laura J Dippel
- Institute of Translational Physiology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany
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11
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Mechanisms of ion transport regulation by HNF1β in the kidney: beyond transcriptional regulation of channels and transporters. Pflugers Arch 2022; 474:901-916. [PMID: 35554666 PMCID: PMC9338905 DOI: 10.1007/s00424-022-02697-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/19/2022] [Accepted: 04/22/2022] [Indexed: 01/01/2023]
Abstract
Hepatocyte nuclear factor 1β (HNF1β) is a transcription factor essential for the development and function of the kidney. Mutations in and deletions of HNF1β cause autosomal dominant tubule interstitial kidney disease (ADTKD) subtype HNF1β, which is characterized by renal cysts, diabetes, genital tract malformations, and neurodevelopmental disorders. Electrolyte disturbances including hypomagnesemia, hyperuricemia, and hypocalciuria are common in patients with ADTKD-HNF1β. Traditionally, these electrolyte disturbances have been attributed to HNF1β-mediated transcriptional regulation of gene networks involved in ion transport in the distal part of the nephron including FXYD2, CASR, KCNJ16, and FXR. In this review, we propose additional mechanisms that may contribute to the electrolyte disturbances observed in ADTKD-HNF1β patients. Firstly, kidney development is severely affected in Hnf1b-deficient mice. HNF1β is required for nephron segmentation, and the absence of the transcription factor results in rudimentary nephrons lacking mature proximal tubule, loop of Henle, and distal convoluted tubule cluster. In addition, HNF1β is proposed to be important for apical-basolateral polarity and tight junction integrity in the kidney. Interestingly, cilia formation is unaffected by Hnf1b defects in several models, despite the HNF1β-mediated transcriptional regulation of many ciliary genes. To what extent impaired nephron segmentation, apical-basolateral polarity, and cilia function contribute to electrolyte disturbances in HNF1β patients remains elusive. Systematic phenotyping of Hnf1b mouse models and the development of patient-specific kidney organoid models will be essential to advance future HNF1β research.
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12
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Lo J, Forst AL, Warth R, Zdebik AA. EAST/SeSAME Syndrome and Beyond: The Spectrum of Kir4.1- and Kir5.1-Associated Channelopathies. Front Physiol 2022; 13:852674. [PMID: 35370765 PMCID: PMC8965613 DOI: 10.3389/fphys.2022.852674] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 02/08/2022] [Indexed: 12/13/2022] Open
Abstract
In 2009, two groups independently linked human mutations in the inwardly rectifying K+ channel Kir4.1 (gene name KCNJ10) to a syndrome affecting the central nervous system (CNS), hearing, and renal tubular salt reabsorption. The autosomal recessive syndrome has been named EAST (epilepsy, ataxia, sensorineural deafness, and renal tubulopathy) or SeSAME syndrome (seizures, sensorineural deafness, ataxia, intellectual disability, and electrolyte imbalance), accordingly. Renal dysfunction in EAST/SeSAME patients results in loss of Na+, K+, and Mg2+ with urine, activation of the renin-angiotensin-aldosterone system, and hypokalemic metabolic alkalosis. Kir4.1 is highly expressed in affected organs: the CNS, inner ear, and kidney. In the kidney, it mostly forms heteromeric channels with Kir5.1 (KCNJ16). Biallelic loss-of-function mutations of Kir5.1 can also have disease significance, but the clinical symptoms differ substantially from those of EAST/SeSAME syndrome: although sensorineural hearing loss and hypokalemia are replicated, there is no alkalosis, but rather acidosis of variable severity; in contrast to EAST/SeSAME syndrome, the CNS is unaffected. This review provides a framework for understanding some of these differences and will guide the reader through the growing literature on Kir4.1 and Kir5.1, discussing the complex disease mechanisms and the variable expression of disease symptoms from a molecular and systems physiology perspective. Knowledge of the pathophysiology of these diseases and their multifaceted clinical spectrum is an important prerequisite for making the correct diagnosis and forms the basis for personalized therapies.
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Affiliation(s)
- Jacky Lo
- Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Anna-Lena Forst
- Medical Cell Biology, Institute of Physiology, University of Regensburg, Regensburg, Germany
| | - Richard Warth
- Medical Cell Biology, Institute of Physiology, University of Regensburg, Regensburg, Germany
| | - Anselm A. Zdebik
- Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
- Centre for Nephrology, University College London, London, United Kingdom
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13
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Viering D, Schlingmann KP, Hureaux M, Nijenhuis T, Mallett A, Chan MM, van Beek A, van Eerde AM, Coulibaly JM, Vallet M, Decramer S, Pelletier S, Klaus G, Kömhoff M, Beetz R, Patel C, Shenoy M, Steenbergen EJ, Anderson G, Bongers EM, Bergmann C, Panneman D, Rodenburg RJ, Kleta R, Houillier P, Konrad M, Vargas-Poussou R, Knoers NV, Bockenhauer D, de Baaij JH. Gitelman-Like Syndrome Caused by Pathogenic Variants in mtDNA. J Am Soc Nephrol 2022; 33:305-325. [PMID: 34607911 PMCID: PMC8819995 DOI: 10.1681/asn.2021050596] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 09/06/2021] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Gitelman syndrome is the most frequent hereditary salt-losing tubulopathy characterized by hypokalemic alkalosis and hypomagnesemia. Gitelman syndrome is caused by biallelic pathogenic variants in SLC12A3, encoding the Na+-Cl- cotransporter (NCC) expressed in the distal convoluted tubule. Pathogenic variants of CLCNKB, HNF1B, FXYD2, or KCNJ10 may result in the same renal phenotype of Gitelman syndrome, as they can lead to reduced NCC activity. For approximately 10 percent of patients with a Gitelman syndrome phenotype, the genotype is unknown. METHODS We identified mitochondrial DNA (mtDNA) variants in three families with Gitelman-like electrolyte abnormalities, then investigated 156 families for variants in MT-TI and MT-TF, which encode the transfer RNAs for phenylalanine and isoleucine. Mitochondrial respiratory chain function was assessed in patient fibroblasts. Mitochondrial dysfunction was induced in NCC-expressing HEK293 cells to assess the effect on thiazide-sensitive 22Na+ transport. RESULTS Genetic investigations revealed four mtDNA variants in 13 families: m.591C>T (n=7), m.616T>C (n=1), m.643A>G (n=1) (all in MT-TF), and m.4291T>C (n=4, in MT-TI). Variants were near homoplasmic in affected individuals. All variants were classified as pathogenic, except for m.643A>G, which was classified as a variant of uncertain significance. Importantly, affected members of six families with an MT-TF variant additionally suffered from progressive chronic kidney disease. Dysfunction of oxidative phosphorylation complex IV and reduced maximal mitochondrial respiratory capacity were found in patient fibroblasts. In vitro pharmacological inhibition of complex IV, mimicking the effect of the mtDNA variants, inhibited NCC phosphorylation and NCC-mediated sodium uptake. CONCLUSION Pathogenic mtDNA variants in MT-TF and MT-TI can cause a Gitelman-like syndrome. Genetic investigation of mtDNA should be considered in patients with unexplained Gitelman syndrome-like tubulopathies.
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Affiliation(s)
- Daan Viering
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Karl P. Schlingmann
- Department of General Pediatrics, University Children’s Hospital, Münster, Germany
| | - Marguerite Hureaux
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies rénales héréditaires de l'enfant et de l'adulte [MARHEA]), Paris, France,Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges-Pompidou, Paris, France
| | - Tom Nijenhuis
- Department of Nephrology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Andrew Mallett
- Department of Renal Medicine, Townsville University Hospital, Townsville, Australia,Queensland Conjoint Renal Genetics Service – Genetic Health Queensland, Royal Brisbane and Women’s Hospital, Brisbane, Australia
| | - Melanie M.Y. Chan
- Department of Renal Medicine, University College London, London, United Kingdom
| | - André van Beek
- Department of Endocrinology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | | | | | - Marion Vallet
- Department of Physiological Functional Investigations, Centre Hospitalier Universitaire de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Stéphane Decramer
- Pediatric Nephrology, Internal Medicine and Rheumatology, Southwest Renal Rare Diseases Centre (SORARE), University Children's Hospital, Toulouse, France
| | - Solenne Pelletier
- Department of Nephrology, University Hospital–Lyon Sud, Lyon, France
| | - Günter Klaus
- Kuratorium für Heimdialyse Pediatric Kidney Center, Marburg, Germany
| | - Martin Kömhoff
- University Children's Hospital, Philipps-University, Marburg, Germany
| | - Rolf Beetz
- Johannes Gutenberg Universität Mainz, Zentrum für Kinder- und Jugendmedizin, Mainz, Germany
| | - Chirag Patel
- Queensland Conjoint Renal Genetics Service – Genetic Health Queensland, Royal Brisbane and Women’s Hospital, Brisbane, Australia
| | - Mohan Shenoy
- Department of Paediatric Nephrology, Royal Manchester Children’s Hospital, Manchester, United Kingdom
| | - Eric J. Steenbergen
- Department of Pathology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Glenn Anderson
- Department of Pathology, Great Ormond Street Hospital for Children National Health Service (NHS) Foundation Trust, London, United Kingdom
| | - Ernie M.H.F. Bongers
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Carsten Bergmann
- Limbach Genetics, Medizinische Genetik Mainz, Prof. Bergmann & Kollegen, Mainz, Germany,Department of Medicine, Division of Nephrology, University Hospital Freiburg, Germany
| | - Daan Panneman
- Radboud Center for Mitochondrial Medicine, Translational Metabolic Laboratory, Department of Pediatrics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Richard J. Rodenburg
- Radboud Center for Mitochondrial Medicine, Translational Metabolic Laboratory, Department of Pediatrics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Robert Kleta
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Paediatric Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Pascal Houillier
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies rénales héréditaires de l'enfant et de l'adulte [MARHEA]), Paris, France,Centre de Recherche des Cordeliers, Sorbonne Université, Institut National de la Santé et de Recherche Médicale (INSERM), Université de Paris, Centre National de la Recherche Scientifique (CNRS), Paris, France,Department of Physiology, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France
| | - Martin Konrad
- Department of General Pediatrics, University Children’s Hospital, Münster, Germany
| | - Rosa Vargas-Poussou
- Reference Center for Hereditary Kidney and Childhood Diseases (Maladies rénales héréditaires de l'enfant et de l'adulte [MARHEA]), Paris, France,Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges-Pompidou, Paris, France,Centre de Recherche des Cordeliers, Sorbonne Université, Institut National de la Santé et de Recherche Médicale (INSERM), Université de Paris, Centre National de la Recherche Scientifique (CNRS), Paris, France
| | - Nine V.A.M. Knoers
- Department of Genetics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Detlef Bockenhauer
- Department of Renal Medicine, University College London, London, United Kingdom,Renal Unit, Great Ormond Street Hospital for Children NHS Foundation Trust, London, United Kingdom
| | - Jeroen H.F. de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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14
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Reyes JV, Medina PMB. Renal calcium and magnesium handling in Gitelman syndrome. Am J Transl Res 2022; 14:1-19. [PMID: 35173827 PMCID: PMC8829599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 11/24/2021] [Indexed: 06/14/2023]
Abstract
Gitelman syndrome (GS) is an autosomal recessive salt-losing tubulopathy caused by biallelic inactivating mutations in the SLC12A3 gene. This gene encodes the thiazide-sensitive sodium-chloride cotransporter (NCC) which is exclusively expressed in the distal convoluted tubules (DCT). GS patients classically present with hypokalemic metabolic alkalosis with hypocalciuria and hypomagnesemia. While hypokalemia and metabolic alkalosis are easily explained by effects of the genotypic defect in GS, the mechanisms by which hypomagnesemia and hypocalciuria develop in GS are poorly understood. In this review, we aim to achieve three major objectives. First, present a concise discussion about current understanding on physiologic calcium and magnesium handling in the DCT. Second, integrate expression data from studies on calciotropic and magnesiotropic proteins relevant to the GS disease state. Lastly, provide insights into the possible mechanisms of calcium-magnesium crosstalk relating to the co-occurrence of hypocalciuria and hypomagnesemia in GS models. Our analyses highlight specific areas of study that are valuable in elucidating possible molecular pathways of hypocalciuria and hypomagnesemia in GS.
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Affiliation(s)
- Jeremiah V Reyes
- Biological Models Laboratory, Department of Biochemistry and Molecular Biology, College of Medicine, University of the Philippines Manila Ermita, Manila 1000, Philippines
| | - Paul Mark B Medina
- Biological Models Laboratory, Department of Biochemistry and Molecular Biology, College of Medicine, University of the Philippines Manila Ermita, Manila 1000, Philippines
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15
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Nashawi M, Ahmed MS, Amin T, Abualfoul M, Chilton R. Cardiovascular benefits from SGLT2 inhibition in type 2 diabetes mellitus patients is not impaired with phosphate flux related to pharmacotherapy. World J Cardiol 2021; 13:676-694. [PMID: 35070111 PMCID: PMC8716977 DOI: 10.4330/wjc.v13.i12.676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 08/02/2021] [Accepted: 11/30/2021] [Indexed: 02/06/2023] Open
Abstract
The beneficial cardiorenal outcomes of sodium-glucose cotransporter 2 inhibitors (SGLT2i) in patients with type 2 diabetes mellitus (T2DM) have been substantiated by multiple clinical trials, resulting in increased interest in the multifarious pathways by which their mechanisms act. The principal effect of SGLT2i (-flozin drugs) can be appreciated in their ability to block the SGLT2 protein within the kidneys, inhibiting glucose reabsorption, and causing an associated osmotic diuresis. This ameliorates plasma glucose elevations and the negative cardiorenal sequelae associated with the latter. These include aberrant mitochondrial metabolism and oxidative stress burden, endothelial cell dysfunction, pernicious neurohormonal activation, and the development of inimical hemodynamics. Positive outcomes within these domains have been validated with SGLT2i administration. However, by modulating the sodium-glucose cotransporter in the proximal tubule (PT), SGLT2i consequently promotes sodium-phosphate cotransporter activity with phosphate retention. Phosphatemia, even at physiologic levels, poses a risk in cardiovascular disease burden, more so in patients with type 2 diabetes mellitus (T2DM). There also exists an association between phosphatemia and renal impairment, the latter hampering cardiovascular function through an array of physiologic roles, such as fluid regulation, hormonal tone, and neuromodulation. Moreover, increased phosphate flux is associated with an associated increase in fibroblast growth factor 23 levels, also detrimental to homeostatic cardiometabolic function. A contemporary commentary concerning this notion unifying cardiovascular outcome trial data with the translational biology of phosphate is scant within the literature. Given the apparent beneficial outcomes associated with SGLT2i administration notwithstanding negative effects of phosphatemia, we discuss in this review the effects of phosphate on the cardiometabolic status in patients with T2DM and cardiorenal disease, as well as the mechanisms by which SGLT2i counteract or overcome them to achieve their net effects. Content drawn to develop this conversation begins with proceedings in the basic sciences and works towards clinical trial data.
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Affiliation(s)
- Mouhamed Nashawi
- Department of Internal Medicine, Baylor Scott and White All Saints Medical Center, Fort Worth, TX 76132, United States
| | - Mahmoud S Ahmed
- Division of Medicine-Cardiology, UT Health San Antonio, San Antonio, TX 78229, United States
| | - Toka Amin
- Division of Medicine-Cardiology, UT Health San Antonio, San Antonio, TX 78229, United States
| | - Mujahed Abualfoul
- Department of Internal Medicine, Faculty of Medicine, Cairo University, Dallas, TX 75203, United States
| | - Robert Chilton
- Department of Internal Medicine, Methodist Dallas Medical Center, Dallas, TX 75203, United States
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16
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Claverie-Martin F, Perdomo-Ramirez A, Garcia-Nieto V. Hereditary kidney diseases associated with hypomagnesemia. Kidney Res Clin Pract 2021; 40:512-526. [PMID: 34784661 PMCID: PMC8685365 DOI: 10.23876/j.krcp.21.112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 06/20/2021] [Indexed: 11/04/2022] Open
Abstract
In the kidney, a set of proteins expressed in the epithelial cells of the thick ascending loop of Henle and the distal convoluted tubule directly or indirectly play important roles in the regulation of serum magnesium levels. Magnesium reabsorption in the thick ascending loop of Henle occurs through a passive paracellular pathway, while in the distal convoluted tubule, the final magnesium concentration is established through an active transcellular pathway. The players involved in magnesium reabsorption include proteins with diverse functions including tight junction proteins, cation and anion channels, sodium chloride cotransporter, calcium-sensing receptor, epidermal growth factor, cyclin M2, sodium potassium adenosine triphosphatase subunits, transcription factors, a serine protease, and proteins involved in mitochondrial function. Mutations in the genes that encode these proteins impair their function and cause different rare diseases associated with hypomagnesemia, which may lead to muscle cramps, fatigue, epileptic seizures, intellectual disability, cardiac arrhythmias, and chronic kidney disease. The purpose of this review is to describe the clinical and genetic characteristics of these hereditary kidney diseases and the current research findings on the pathophysiological basis of these diseases.
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Affiliation(s)
- Felix Claverie-Martin
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Ana Perdomo-Ramirez
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Victor Garcia-Nieto
- Unidad de Nefrología Pediátrica, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
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17
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Nuñez-Gonzalez L, Carrera N, Garcia-Gonzalez MA. Molecular Basis, Diagnostic Challenges and Therapeutic Approaches of Bartter and Gitelman Syndromes: A Primer for Clinicians. Int J Mol Sci 2021; 22:11414. [PMID: 34768847 PMCID: PMC8584233 DOI: 10.3390/ijms222111414] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/13/2021] [Accepted: 10/14/2021] [Indexed: 12/18/2022] Open
Abstract
Gitelman and Bartter syndromes are rare inherited diseases that belong to the category of renal tubulopathies. The genes associated with these pathologies encode electrolyte transport proteins located in the nephron, particularly in the Distal Convoluted Tubule and Ascending Loop of Henle. Therefore, both syndromes are characterized by alterations in the secretion and reabsorption processes that occur in these regions. Patients suffer from deficiencies in the concentration of electrolytes in the blood and urine, which leads to different systemic consequences related to these salt-wasting processes. The main clinical features of both syndromes are hypokalemia, hypochloremia, metabolic alkalosis, hyperreninemia and hyperaldosteronism. Despite having a different molecular etiology, Gitelman and Bartter syndromes share a relevant number of clinical symptoms, and they have similar therapeutic approaches. The main basis of their treatment consists of electrolytes supplements accompanied by dietary changes. Specifically for Bartter syndrome, the use of non-steroidal anti-inflammatory drugs is also strongly supported. This review aims to address the latest diagnostic challenges and therapeutic approaches, as well as relevant recent research on the biology of the proteins involved in disease. Finally, we highlight several objectives to continue advancing in the characterization of both etiologies.
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Affiliation(s)
- Laura Nuñez-Gonzalez
- Grupo de Xenetica e Bioloxia do Desenvolvemento das Enfermidades Renais, Laboratorio de Nefroloxia (No. 11), Instituto de Investigacion Sanitaria de Santiago (IDIS), Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain;
- Grupo de Medicina Xenomica, Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain
| | - Noa Carrera
- Grupo de Xenetica e Bioloxia do Desenvolvemento das Enfermidades Renais, Laboratorio de Nefroloxia (No. 11), Instituto de Investigacion Sanitaria de Santiago (IDIS), Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain;
- Grupo de Medicina Xenomica, Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain
- RedInRen (Red en Investigación Renal) RETIC (Redes Temáticas de Investigación Cooperativa en Salud), ISCIII (Instituto de Salud Carlos III), 28029 Madrid, Spain
| | - Miguel A. Garcia-Gonzalez
- Grupo de Xenetica e Bioloxia do Desenvolvemento das Enfermidades Renais, Laboratorio de Nefroloxia (No. 11), Instituto de Investigacion Sanitaria de Santiago (IDIS), Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain;
- Grupo de Medicina Xenomica, Complexo Hospitalario de Santiago de Compostela (CHUS), 15706 Santiago de Compostela, Spain
- RedInRen (Red en Investigación Renal) RETIC (Redes Temáticas de Investigación Cooperativa en Salud), ISCIII (Instituto de Salud Carlos III), 28029 Madrid, Spain
- Fundación Pública Galega de Medicina Xenomica—SERGAS, Complexo Hospitalario de Santiago de Compotela (CHUS), 15706 Santiago de Compostela, Spain
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18
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Affiliation(s)
- Tomas L Bothe
- Charité – Universitätsmedizin Berlincorporate member of Freie Universität Berlin and Humboldt‐Universität zu BerlinInstitute of Vegetative Physiology Berlin Germany
| | - Andreas Patzak
- Charité – Universitätsmedizin Berlincorporate member of Freie Universität Berlin and Humboldt‐Universität zu BerlinInstitute of Vegetative Physiology Berlin Germany
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19
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Abstract
Magnesium (Mg2+) plays an essential role in many biological processes. Mg2+ deficiency is therefore associated with a wide range of clinical effects including muscle cramps, fatigue, seizures and arrhythmias. To maintain sufficient Mg2+ levels, (re)absorption of Mg2+ in the intestine and kidney is tightly regulated. Genetic defects that disturb Mg2+ uptake pathways, as well as drugs interfering with Mg2+ (re)absorption cause hypomagnesemia. The aim of this review is to provide an overview of the molecular mechanisms underlying genetic and drug-induced Mg2+ deficiencies. This leads to the identification of four main mechanisms that are affected by hypomagnesemia-causing mutations or drugs: luminal transient receptor potential melastatin type 6/7-mediated Mg2+ uptake, paracellular Mg2+ reabsorption in the thick ascending limb of Henle's loop, structural integrity of the distal convoluted tubule and Na+-dependent Mg2+ extrusion driven by the Na+/K+-ATPase. Our analysis demonstrates that genetic and drug-induced causes of hypomagnesemia share common molecular mechanisms. Targeting these shared pathways can lead to novel treatment options for patients with hypomagnesemia.
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20
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Franken GAC, Adella A, Bindels RJM, Baaij JHF. Mechanisms coupling sodium and magnesium reabsorption in the distal convoluted tubule of the kidney. Acta Physiol (Oxf) 2021; 231:e13528. [PMID: 32603001 PMCID: PMC7816272 DOI: 10.1111/apha.13528] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 05/29/2020] [Accepted: 06/22/2020] [Indexed: 02/06/2023]
Abstract
Hypomagnesaemia is a common feature of renal Na+ wasting disorders such as Gitelman and EAST/SeSAME syndrome. These genetic defects specifically affect Na+ reabsorption in the distal convoluted tubule, where Mg2+ reabsorption is tightly regulated. Apical uptake via TRPM6 Mg2+ channels and basolateral Mg2+ extrusion via a putative Na+ -Mg2+ exchanger determines Mg2+ reabsorption in the distal convoluted tubule. However, the mechanisms that explain the high incidence of hypomagnesaemia in patients with Na+ wasting disorders of the distal convoluted tubule are largely unknown. In this review, we describe three potential mechanisms by which Mg2+ reabsorption in the distal convoluted tubule is linked to Na+ reabsorption. First, decreased activity of the thiazide-sensitive Na+ /Cl- cotransporter (NCC) results in shortening of the segment, reducing the Mg2+ reabsorption capacity. Second, the activity of TRPM6 and NCC are determined by common regulatory pathways. Secondary effects of NCC dysregulation such as hormonal imbalance, therefore, might disturb TRPM6 expression. Third, the basolateral membrane potential, maintained by the K+ permeability and Na+ -K+ -ATPase activity, provides the driving force for Na+ and Mg2+ extrusion. Depolarisation of the basolateral membrane potential in Na+ wasting disorders of the distal convoluted tubule may therefore lead to reduced activity of the putative Na+ -Mg2+ exchanger SLC41A1. Elucidating the interconnections between Mg2+ and Na+ transport in the distal convoluted tubule is hampered by the currently available models. Our analysis indicates that the coupling of Na+ and Mg2+ reabsorption may be multifactorial and that advanced experimental models are required to study the molecular mechanisms.
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Affiliation(s)
- Gijs A. C. Franken
- Department of Physiology Radboud Institute for Molecular Life SciencesRadboud University Medical Center Nijmegen the Netherlands
| | - Anastasia Adella
- Department of Physiology Radboud Institute for Molecular Life SciencesRadboud University Medical Center Nijmegen the Netherlands
| | - René J. M. Bindels
- Department of Physiology Radboud Institute for Molecular Life SciencesRadboud University Medical Center Nijmegen the Netherlands
| | - Jeroen H. F. Baaij
- Department of Physiology Radboud Institute for Molecular Life SciencesRadboud University Medical Center Nijmegen the Netherlands
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21
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Maeoka Y, McCormick JA. NaCl cotransporter activity and Mg 2+ handling by the distal convoluted tubule. Am J Physiol Renal Physiol 2020; 319:F1043-F1053. [PMID: 33135481 DOI: 10.1152/ajprenal.00463.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The genetic disease Gitelman syndrome, knockout mice, and pharmacological blockade with thiazide diuretics have revealed that reduced activity of the NaCl cotransporter (NCC) promotes renal Mg2+ wasting. NCC is expressed along the distal convoluted tubule (DCT), and its activity determines Mg2+ entry into DCT cells through transient receptor potential channel subfamily M member 6 (TRPM6). Several other genetic forms of hypomagnesemia lower the drive for Mg2+ entry by inhibiting activity of basolateral Na+-K+-ATPase, and reduced NCC activity may do the same. Lower intracellular Mg2+ may promote further Mg2+ loss by directly decreasing activity of Na+-K+-ATPase. Lower intracellular Mg2+ may also lower Na+-K+-ATPase indirectly by downregulating NCC. Lower NCC activity also induces atrophy of DCT cells, decreasing the available number of TRPM6 channels. Conversely, a mouse model with increased NCC activity was recently shown to display normal Mg2+ handling. Moreover, recent studies have identified calcineurin and uromodulin (UMOD) as regulators of both NCC and Mg2+ handling by the DCT. Calcineurin inhibitors paradoxically cause hypomagnesemia in a state of NCC activation, but this may be related to direct effects on TRPM6 gene expression. In Umod-/- mice, the cause of hypomagnesemia may be partly due to both decreased NCC expression and lower TRPM6 expression on the cell surface. This mini-review discusses these new findings and the possible role of altered Na+ flux through NCC and ultimately Na+-K+-ATPase in Mg2+ reabsorption by the DCT.
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Affiliation(s)
- Yujiro Maeoka
- 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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