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Ikeuchi M, Inoue M, Miyahara H, Sebastian WA, Miyazaki S, Takeno T, Kiyota K, Yano S, Shiraishi H, Shimizu N, Hanada R, Yoshimura A, Ihara K, Hanada T. A pH imbalance is linked to autophagic dysregulation of inner ear hair cells in Atp6v1ba-deficient zebrafish. Biochem Biophys Res Commun 2024; 699:149551. [PMID: 38277730 DOI: 10.1016/j.bbrc.2024.149551] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2024] [Accepted: 01/17/2024] [Indexed: 01/28/2024]
Abstract
V-ATPase is an ATP hydrolysis-driven proton pump involved in the acidification of intracellular organelles and systemic acid-base homeostasis through H+ secretion in the renal collecting ducts. V-ATPase dysfunction is associated with hereditary distal renal tubular acidosis (dRTA). ATP6V1B1 encodes the B1 subunit of V-ATPase that is integral to ATP hydrolysis and subsequent H+ transport. Patients with pathogenic ATP6V1B1 mutations often exhibit an early onset of sensorineural hearing loss. However, the mechanisms underlying this association remain unclear. We employed morpholino oligonucleotide-mediated knockdown and CRISPR/Cas9 gene editing to generate Atp6v1ba-deficient (atp6v1ba-/-) zebrafish as an ortholog model for ATP6V1B1. The atp6v1ba-/- zebrafish exhibited systemic acidosis and significantly smaller otoliths compared to wild-type siblings. Moreover, deficiency in Atp6v1ba led to degeneration of inner ear hair cells, with ultrastructural changes indicative of autophagy. Our findings indicate a critical role of ATP6V1B1 in regulating lysosomal pH and autophagy in hair cells, and the results provide insights into the pathophysiology of sensorineural hearing loss in dRTA. Furthermore, this study demonstrates that the atp6v1ba-/- zebrafish model is a valuable tool for further investigation into disease mechanisms and potential therapies for acidosis-related hearing impairment.
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Affiliation(s)
- Mayo Ikeuchi
- Department of Cell Biology, Oita University Faculty of Medicine, Yufu, Oita, Japan; Department of Pediatrics, Oita University Faculty of Medicine, Yufu, Oita, Japan
| | - Masanori Inoue
- Department of Pediatrics, Oita University Faculty of Medicine, Yufu, Oita, Japan
| | - Hiroaki Miyahara
- Department of Neuropathology, Institute for Medical Science of Aging, Aichi Medical University, Aichi, Japan
| | | | - Shuya Miyazaki
- Department of Cell Biology, Oita University Faculty of Medicine, Yufu, Oita, Japan
| | - Takashi Takeno
- Department of Cell Biology, Oita University Faculty of Medicine, Yufu, Oita, Japan
| | - Kyoko Kiyota
- Department of Cell Biology, Oita University Faculty of Medicine, Yufu, Oita, Japan; Department of Pediatrics, Oita University Faculty of Medicine, Yufu, Oita, Japan
| | - Shinji Yano
- Institute for Research Management, Oita University, Yufu, Oita, Japan
| | - Hiroshi Shiraishi
- Department of Cell Biology, Oita University Faculty of Medicine, Yufu, Oita, Japan
| | - Nobuyuki Shimizu
- Department of Cell Biology, Oita University Faculty of Medicine, Yufu, Oita, Japan
| | - Reiko Hanada
- Department of Neurophysiology, Oita University Faculty of Medicine, Yufu, Oita, Japan
| | - Akihiko Yoshimura
- Department of Microbiology and Immunology, Keio University School of Medicine, Tokyo, Japan
| | - Kenji Ihara
- Department of Pediatrics, Oita University Faculty of Medicine, Yufu, Oita, Japan
| | - Toshikatsu Hanada
- Department of Cell Biology, Oita University Faculty of Medicine, Yufu, Oita, Japan.
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Bertholet-Thomas A, Manso-Silván MA, Navas-Serrano V, Guittet C, Joukoff S, Bacchetta J, Boyer O, Rodriguez Portillo M, Granier LA. Bone mineral density and growth changes in patients with distal renal tubular acidosis after two-years treatment with a new alkalizing drug (ADV7103). Nefrologia 2023; 43:458-466. [PMID: 36529656 DOI: 10.1016/j.nefroe.2022.02.012] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 02/27/2022] [Indexed: 06/17/2023] Open
Abstract
BACKGROUND AND OBJECTIVES ADV7103 is a new prolonged-release treatment for distal renal tubular acidosis (dRTA), containing potassium citrate and potassium bicarbonate. Since acidosis may affect bone mineral contents, the effects of ADV7103 on bone mineral density (BMD) and growth in patients with dRTA over 24 months were evaluated. PATIENTS AND METHODS Thirty patients (24 paediatric patients and 6 adults) were included in an open-label extension study after a phase II/III trial. BMD, measured by densitometry, was assessed at baseline and at 24 months. Growth was evaluated throughout the study. Plasma bicarbonate, parathyroid hormone, 25-hydroxy vitamin D, 1,25-dihydroxy vitamin D, bone alkaline phosphatase, calciuria and citraturia, were also determined. Safety and treatment compliance were evaluated as well. RESULTS After 24 months of treatment with ADV7103, mean spine BMD z-score values significantly increased as compared with baseline (p=0.024). In adults, spine and whole-body densitometry z-scores showed a significant correlation with plasma bicarbonate levels (rS=0.82 and rS=0.97, respectively, p<0.005). There was an increase>0.5 units in z-scores for height and weight in 18% and 36% of the paediatric patients, respectively. With treatment, plasma bicarbonate concentration and calciuria at the different visits were normal in 69-86% and 93-96% patients, respectively. Only nine treatment-related gastrointestinal AEs of mild/moderate severity, were reported in five patients. CONCLUSIONS Two years of ADV7103 treatment improved growth and increased spine BMD. These results suggest that control of acidosis by ADV7103 treatment improves bone parameters.
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Affiliation(s)
- Aurélia Bertholet-Thomas
- Centre de Référence des Maladies Rénales Rares - Néphrogones - Hôpital Femme Mère Enfant, Hospices Civils de Lyon - Filière ORKiD, Bron, France
| | | | | | | | | | - Justine Bacchetta
- Centre de Référence des Maladies Rénales Rares - Néphrogones - Hôpital Femme Mère Enfant, Hospices Civils de Lyon - Filière ORKiD, Bron, France
| | - Olivia Boyer
- Service de Néphrologie Pédiatrique, Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Institut Imagine, Hôpital Necker-Enfants Malades, Université de Paris, France
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Chu A, Yao Y, Saffi GT, Chung JH, Botelho RJ, Glibowicka M, Deber CM, Manolson MF. Characterization of a PIP Binding Site in the N-Terminal Domain of V-ATPase a4 and Its Role in Plasma Membrane Association. Int J Mol Sci 2023; 24. [PMID: 36902293 DOI: 10.3390/ijms24054867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/13/2023] [Accepted: 02/21/2023] [Indexed: 03/06/2023] Open
Abstract
Vacuolar ATPases (V-ATPases) are multi-subunit ATP-dependent proton pumps necessary for cellular functions, including pH regulation and membrane fusion. The evidence suggests that the V-ATPase a-subunit's interaction with the membrane signaling lipid phosphatidylinositol (PIPs) regulates the recruitment of V-ATPase complexes to specific membranes. We generated a homology model of the N-terminal domain of the human a4 isoform (a4NT) using Phyre2.0 and propose a lipid binding domain within the distal lobe of the a4NT. We identified a basic motif, K234IKK237, critical for interaction with phosphoinositides (PIP), and found similar basic residue motifs in all four mammalian and both yeast a-isoforms. We tested PIP binding of wildtype and mutant a4NT in vitro. In protein lipid overlay assays, the double mutation K234A/K237A and the autosomal recessive distal renal tubular-causing mutation K237del reduced both PIP binding and association with liposomes enriched with PI(4,5)P2, a PIP enriched within plasma membranes. Circular dichroism spectra of the mutant protein were comparable to wildtype, indicating that mutations affected lipid binding, not protein structure. When expressed in HEK293, wildtype a4NT localized to the plasma membrane in fluorescence microscopy and co-purified with the microsomal membrane fraction in cellular fractionation experiments. a4NT mutants showed reduced membrane association and decreased plasma membrane localization. Depletion of PI(4,5)P2 by ionomycin caused reduced membrane association of the WT a4NT protein. Our data suggest that information contained within the soluble a4NT is sufficient for membrane association and that PI(4,5)P2 binding capacity is involved in a4 V-ATPase plasma membrane retention.
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Acquadro M, Marrel A, Manso-Silván MA, Guittet C, Joukoff S, Bertholet-Thomas A. Lived experiences of patients with distal renal tubular acidosis treated with ADV7103 and of their caregivers: a qualitative study. Orphanet J Rare Dis 2022; 17:141. [PMID: 35346296 PMCID: PMC8962487 DOI: 10.1186/s13023-022-02294-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 02/27/2022] [Indexed: 12/30/2022] Open
Abstract
Background Consequences of distal renal tubular acidosis (dRTA) on growth, bone and kidney, sometimes associated with hearing loss, may significantly affect quality of life (QoL). This descriptive qualitative study explores QoL linked to dRTA and gathers the impressions of patients with this rare disease (and caregivers) 5 years after enrolment in a clinical study, during which patients were treated with ADV7103, a prolonged-release granule formulation combining potassium citrate and potassium bicarbonate. Semi-structured, one-hour interviews with 6 adult and 13 paediatric patients with a confirmed diagnosis of dRTA and with parents of paediatric patients were performed using an interview guide. Qualitative analysis of anonymized interview transcripts based on grounded theory was conducted. Results The main QoL domains impacted by dRTA and its treatment were education/work, social/family life, and emotional and physical well-being. ADV7103 (administered twice daily) was compared with the standard of care (SoC) taken before study entry (more than twice daily). Patients/parents reported that switching from previous SoC to ADV7103 had changed their lives:Difficulties at school due to burdensome administrative issues and need to explain disease and treatment affecting all families of paediatric patients (n = 13) disappeared, facilitating parents who had stopped working (to deal with their child’s treatment) to return to work, Family functioning was improved (n = 18), as travel and holidays became easier to organise and patients/parents stopped thinking about managing treatment daily/nightly, reducing tension in the family or couple, The emotional burden of disease perceived was relieved (n = 12) in the absence of treatment-related invasive questions from others, Gastro-intestinal adverse events and taste problems improved with ADV7103 (n = 18) and better compliance led to milder physical impacts and less need to be hospitalised.
The mean satisfaction score with ADV7103 compared to SoC was 9 out of 10 (10 = very satisfied). ADV7103 exceeded or met the expectations of 14 out of 17 patients that commented on that. Conclusions Qualitative interviews show that dRTA and its treatment have a significant impact on QoL of patients and parents and that ADV7103 helps improve daily-life and reduces treatment burden, resulting in greater overall satisfaction of the patients and their families. Trial registration EU Clinical Trials Register, EudraCT 2013-003828-36 on the 3rd of September 2013.
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Affiliation(s)
| | | | | | | | - Sophie Joukoff
- Advicenne S.A., 21 Allée Boissy d'Anglas, 30000, Nîmes, France
| | - Aurélia Bertholet-Thomas
- Centre de Référence des Maladies Rénales Rares-Néphrogones-Hôpital Femme Mère Enfant, Hospices Civils de Lyon-Filière ORKiD, Bron, France
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Bertholet-Thomas A, Guittet C, Manso-Silván MA, Castang A, Baudouin V, Cailliez M, Di Maio M, Gillion-Boyer O, Golubovic E, Harambat J, Klein A, Knebelmann B, Nobili F, Novo R, Podracka L, Roussey-Kesler G, Stylianou C, Granier LA. Efficacy and safety of an innovative prolonged-release combination drug in patients with distal renal tubular acidosis: an open-label comparative trial versus standard of care treatments. Pediatr Nephrol 2021; 36:83-91. [PMID: 32712761 PMCID: PMC7701073 DOI: 10.1007/s00467-020-04693-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 06/16/2020] [Accepted: 06/25/2020] [Indexed: 11/30/2022]
Abstract
BACKGROUND Distal renal tubular acidosis (dRTA), due to impaired acid secretion in the urine, can lead to severe long-term consequences. Standard of care (SoC) oral alkalizers, requiring several daily intakes, are currently used to restore normal plasma bicarbonate levels. A new prolonged-release formulation, ADV7103, has been developed to achieve a sustained effect with an improved dosing scheme. METHODS In a multicenter, open-label, non-inferiority trial (n = 37), patients with dRTA were switched from SoC to ADV7103. Mean plasma bicarbonate values and proportion of responders during steady state therapy with both treatments were compared, as were other blood and urine parameters, as well as acceptability, tolerability, and safety. RESULTS When switching from SoC to ADV7103, the number of daily intakes was reduced from a median of three to twice daily. Mean plasma bicarbonate was increased and non-inferiority of ADV7103 was demonstrated (p < 0.0001, per protocol), as was statistical superiority (p = 0.0008, intention to treat [ITT]), and the response rate increased from 43 to 90% with ADV7103 (p < 0.001, ITT). Urine calcium/citrate ratio was reduced below the threshold for risk of lithogenesis with ADV7103 in 56% of previously non-responders with SoC (p = 0.021, ITT). Palatability was improved (difference [95% CI] of 25 [10.7, 39.2] mm) and gastrointestinal discomfort was reduced (difference [95% CI] of - 14.2 [- 25.9, - 2.6] mm) with ADV7103. CONCLUSIONS Plasma bicarbonate levels and response rate were significantly higher with ADV7103 than with SoC. Urine calcium/citrate ratio, palatability, and gastrointestinal safety were significantly improved, supporting the use of ADV7103 as first-line treatment for dRTA. TRIAL REGISTRATION Registered as EudraCT 2013-002988-25 on the 1st July 2013 Graphical abstract.
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Affiliation(s)
- Aurélia Bertholet-Thomas
- Centre de Référence des Maladies Rénales Rares - Néphrogones - Hôpital Femme Mère Enfant - Filière ORKiD, Hospices Civils de Lyon, Bron, France.
| | | | | | | | | | - Mathilde Cailliez
- Service de Pédiatrie Multidisciplinaire, Hôpital de la Timone, AP-HM, Marseille, France
| | - Massimo Di Maio
- Service de Réanimation Néonatale et Néonatologie, CHU de Nîmes, Nîmes, France
| | - Olivia Gillion-Boyer
- Service de Néphrologie Pédiatrique, Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Institut Imagine, Hôpital Necker-Enfants Malades, Université de Paris, Paris, France
| | - Emilija Golubovic
- Klinički Centar Niš, Klinika za dečije interne bolesti - Odeljenje za nefrologiju, Niš, Serbia
| | - Jérôme Harambat
- Service de Pédiatrie, CHU de Bordeaux, Hôpital Pellegrin-Enfants, Bordeaux, France
| | - Alexandre Klein
- Service de Néphrologie, Pôle DIACOR, Hôpitaux Civils de Colmar, Colmar, France
| | | | - François Nobili
- Service de Pédiatrie 2, Hôpital Jean Minjoz, CHU de Besançon, Besançon, France
| | - Robert Novo
- Service de Néphrologie Pédiatrique, Hôpital Jeanne de Flandre, CHRU de Lille, Lille, France
| | - Ludmila Podracka
- Department of Pediatrics, National Institute of Children's Health, Bratislava, Slovakia
| | - Gwenaëlle Roussey-Kesler
- Unité de Néphrologie et Hémodialyse Pédiatrique, Clinique Médicale Pédiatrique Hôpital Mère-Enfant, CHU de Nantes, Nantes, France
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Bertholet-Thomas A, Guittet C, Manso-Silván MA, Joukoff S, Navas-Serrano V, Baudouin V, Cailliez M, Di Maio M, Gillion-Boyer O, Golubovic E, Harambat J, Knebelmann B, Nobili F, Novo R, Podracka L, Roussey-Kesler G, Granier LA. Safety, efficacy, and acceptability of ADV7103 during 24 months of treatment: an open-label study in pediatric and adult patients with distal renal tubular acidosis. Pediatr Nephrol 2021; 36:1765-74. [PMID: 33635379 DOI: 10.1007/s00467-020-04873-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 10/21/2020] [Accepted: 11/23/2020] [Indexed: 11/17/2022]
Abstract
BACKGROUND A new prolonged-release formulation of potassium citrate and potassium bicarbonate, ADV7103, has been shown to improve metabolic control, palatability, and gastrointestinal safety in patients with distal renal tubular acidosis (dRTA) when compared to standard of care (SoC) treatments. The present work evaluates safety and efficacy of ADV7103 during 24 months. METHODS Thirty pediatric and adult patients were included in an open-label extension study after a phase II/III trial. Safety and tolerability were assessed. Plasma bicarbonate and potassium levels, as well as urine parameters, were evaluated over time. Acceptability, adherence, and quality of life were also assessed. The evolution of clinical consequences of dRTA in the cohort was explored. RESULTS There were 104 adverse events (AEs) reported, but only 9 gastrointestinal events observed in five patients (17%) were considered to be related to ADV7103 treatment. There were no AEs leading to treatment discontinuation. Plasma bicarbonate and potassium levels were in the normal ranges at the different visits, respectively, in 69-86% and 83-93% of patients. Overall adherence rates were ≥ 75% throughout the whole study in 79% patients. An average improvement of quality of life of 89% was reported at 24 months of study. CONCLUSIONS Common AEs concerned metabolism and gastrointestinal disorders; the former being related to the disease. Less than half of the gastrointestinal AEs were related to ADV7103 treatment and they were mostly mild in severity. Metabolic parameters were maintained in the normal ranges in most patients. Patient satisfaction was high and adherence to treatment was good and remained stable. TRIAL REGISTRATION NUMBER Registered as EudraCT 2013-003828-36 on the 3rd of September 2013.
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Elitok S, Sidler M, Bieringer M, Mohebbi N, Schneider W, Wagner CA. A patient with chronic kidney disease, primary biliary cirrhosis and metabolic acidosis. Clin Kidney J 2019; 13:463-467. [PMID: 32699627 PMCID: PMC7367120 DOI: 10.1093/ckj/sfz059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 04/17/2019] [Indexed: 11/14/2022] Open
Abstract
Autoimmune disorders such as rheumatoid arthritis or Sjögren's syndrome can be associated with impaired renal acid excretion. Only few cases of patients with primary biliary cirrhosis (PBC) and distal renal tubular acidosis (dRTA) have been described. Here, we present the case of a 60-year-old woman with PBC and dRTA. Her kidney biopsy showed an absence of markers of acid-secretory Type A intercalated cells (A-ICs) and expression of aquaporin-2, a marker of principal cells, in all cells lining the collecting duct. Moreover, the serum of the patient contained antibodies directed against a subset of cells of the collecting duct. Thus, PBC-related autoantibodies may target acid-secretory A-ICs and thereby impair urinary acidification.
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Affiliation(s)
- Saban Elitok
- Department of Nephrology and Endocrinology/Diabetology, Klinikum Ernst von Bergmann, Potsdam, Germany
- Correspondence and offprint requests to: Saban Elitok; E-mail: , Carsten A. Wagner; E-mail:
| | - Marius Sidler
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | | | - Nilufar Mohebbi
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | | | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Correspondence and offprint requests to: Saban Elitok; E-mail: , Carsten A. Wagner; E-mail:
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Faller N, Dhayat NA, Fuster DG. Nephrolithiasis secondary to inherited defects in the thick ascending loop of henle and connecting tubules. Urolithiasis 2019; 47:43-56. [PMID: 30460527 DOI: 10.1007/s00240-018-1097-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 11/08/2018] [Indexed: 12/19/2022]
Abstract
Twin and genealogy studies suggest a strong genetic component of nephrolithiasis. Likewise, urinary traits associated with renal stone formation were found to be highly heritable, even after adjustment for demographic, anthropometric and dietary covariates. Recent high-throughput sequencing projects of phenotypically well-defined cohorts of stone formers and large genome-wide association studies led to the discovery of many new genes associated with kidney stones. The spectrum ranges from infrequent but highly penetrant variants (mutations) causing mendelian forms of nephrolithiasis (monogenic traits) to common but phenotypically mild variants associated with nephrolithiasis (polygenic traits). About two-thirds of the genes currently known to be associated with nephrolithiasis code for membrane proteins or enzymes involved in renal tubular transport. The thick ascending limb of Henle and connecting tubules are of paramount importance for renal water and electrolyte handling, urinary concentration and maintenance of acid-base homeostasis. In most instances, pathogenic variants in genes involved in thick ascending limb of Henle and connecting tubule function result in phenotypically severe disease, frequently accompanied by nephrocalcinosis with progressive CKD and to a variable degree by nephrolithiasis. The aim of this article is to review the current knowledge on kidney stone disease associated with inherited defects in the thick ascending loop of Henle and the connecting tubules. We also highlight recent advances in the field of kidney stone genetics that have implications beyond rare disease, offering new insights into the most common type of kidney stone disease, i.e., idiopathic calcium stone disease.
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Rungroj N, Nettuwakul C, Sawasdee N, Sangnual S, Deejai N, Misgar RA, Pasena A, Khositseth S, Kirdpon S, Sritippayawan S, Vasuvattakul S, Yenchitsomanus PT. Distal renal tubular acidosis caused by tryptophan-aspartate repeat domain 72 (WDR72) mutations. Clin Genet 2018; 94:409-418. [PMID: 30028003 DOI: 10.1111/cge.13418] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [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: 05/04/2018] [Revised: 06/21/2018] [Accepted: 07/17/2018] [Indexed: 12/18/2022]
Abstract
Hereditary distal renal tubular acidosis (dRTA) is a rare genetic disease that is caused by mutations in SLC4A1, ATP6V1B1, or ATP6V0A4. However, there are many families with hereditary dRTA in whom the disease-causing genes are unknown. Accordingly, we performed whole exome sequencing and genetic studies of the members of a family with autosomal recessive dRTA of an unknown genetic etiology. Here, we report compound heterozygous pathogenic variations in tryptophan-aspartate repeat domain 72 (WDR72) (c.1777A>G [p.R593G] and c.2522T>A [p.L841Q]) in three affected siblings of a family with dRTA. Both variants segregated with dRTA in the family and were not observed in normal control subjects. Homologous modeling and in silico mutagenesis indicated that R593G and L841Q alter the H-bond formations in the nearby residues, affecting the WDR72 protein structure. All these evidences indicate that the identified WDR72 variations were probably to have caused hereditary dRTA in the reported family. In addition, homozygous nonsense mutation (c.2686C>T [p.R896X]) was identified in another family, strongly supporting the causal role of WDR72 in dRTA. Based on our literature review, WDR72 mutations associated with dRTA have not been previously described. This is the first identification of pathogenic variations in WDR72 as a cause of hereditary dRTA.
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Affiliation(s)
- N Rungroj
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.,Division of Molecular Genetics, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - C Nettuwakul
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - N Sawasdee
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - S Sangnual
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - N Deejai
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - R A Misgar
- Department of Endocrinology, Sher-i-Kashmir Institute of Medical Sciences, Srinagar, India
| | - A Pasena
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.,Department of Immunology and Immunology Graduate Program, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - S Khositseth
- Department of Pediatrics, Faculty of Medicine, Thammasat University, Pathumthani, Thailand
| | - S Kirdpon
- Department of Pediatrics, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - S Sritippayawan
- Division of Nephrology, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - S Vasuvattakul
- Division of Nephrology, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - P T Yenchitsomanus
- Division of Molecular Medicine, Department of Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
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Merkulova M, Păunescu TG, Nair AV, Wang CY, Capen DE, Oliver PL, Breton S, Brown D. Targeted deletion of the Ncoa7 gene results in incomplete distal renal tubular acidosis in mice. Am J Physiol Renal Physiol 2018; 315:F173-F185. [PMID: 29384414 DOI: 10.1152/ajprenal.00407.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [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: 12/27/2022] Open
Abstract
We recently reported that nuclear receptor coactivator 7 (Ncoa7) is a vacuolar proton pumping ATPase (V-ATPase) interacting protein whose function has not been defined. Ncoa7 is highly expressed in the kidney and partially colocalizes with the V-ATPase in collecting duct intercalated cells (ICs). Here, we hypothesized that targeted deletion of the Ncoa7 gene could affect V-ATPase activity in ICs in vivo. We tested this by analyzing the acid-base status, major electrolytes, and kidney morphology of Ncoa7 knockout (KO) mice. We found that Ncoa7 KO mice, similar to Atp6v1b1 KOs, did not develop severe distal renal tubular acidosis (dRTA), but they exhibited a persistently high urine pH and developed hypobicarbonatemia after acid loading with ammonium chloride. Conversely, they did not develop significant hyperbicarbonatemia and alkalemia after alkali loading with sodium bicarbonate. We also found that ICs were larger and with more developed apical microvilli in Ncoa7 KO compared with wild-type mice, a phenotype previously associated with metabolic acidosis. At the molecular level, the abundance of several V-ATPase subunits, carbonic anhydrase 2, and the anion exchanger 1 was significantly reduced in medullary ICs of Ncoa7 KO mice, suggesting that Ncoa7 is important for maintaining high levels of these proteins in the kidney. We conclude that Ncoa7 is involved in IC function and urine acidification in mice in vivo, likely through modulating the abundance of V-ATPase and other key acid-base regulators in the renal medulla. Consequently, mutations in the NCOA7 gene may also be involved in dRTA pathogenesis in humans.
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Affiliation(s)
- Maria Merkulova
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School , Boston, Massachusetts
| | - Teodor G Păunescu
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School , Boston, Massachusetts
| | - Anil V Nair
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School , Boston, Massachusetts
| | - Chia-Yu Wang
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School , Boston, Massachusetts
| | - Diane E Capen
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School , Boston, Massachusetts
| | - Peter L Oliver
- Department of Physiology, Anatomy and Genetics, University of Oxford , Oxford , United Kingdom
| | - Sylvie Breton
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School , Boston, Massachusetts
| | - Dennis Brown
- Center for Systems Biology, Program in Membrane Biology and Division of Nephrology, Massachusetts General Hospital and Harvard Medical School , Boston, Massachusetts
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11
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Bhargava R, Abohashem Aly AA, Mertz JI, Mustafa R. Rhabdomyolysis as the first manifestation of human immunodeficiency virus infection. CEN Case Rep 2015; 5:48-50. [PMID: 28509166 DOI: 10.1007/s13730-015-0189-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [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: 06/20/2015] [Accepted: 07/15/2015] [Indexed: 10/23/2022] Open
Abstract
Renal tubular acidosis (RTA) is a known complication of anti-retroviral medications. The presence of RTA in treatment naive-HIV patients is rare. A 49-year-old Caucasian woman presented with recurrent non-anion gap metabolic acidosis, AKI, rhabdomyolysis and hypokalemia on several occasions. Diagnosis of acquired distal RTA due to HIV was made given the history and laboratory data. To the best of our knowledge, this is the first case of HIV diagnosed with an initial presentation of rhabdomyolysis. We believe that acute renal failure was due to hypokalemia precipitating rhabdomyolysis caused by HIV-induced dRTA which was further exacerbated by amphetamine use.
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Affiliation(s)
- Rhea Bhargava
- Department of Internal Medicine, University of Missouri-Kansas City, 2301 Holmes Street, Kansas City, MO, 64108, USA.
| | | | - Jim I Mertz
- Department of Nephrology and Hypertension, University of Missouri-Kansas City, Kansas City, USA
- Saint Luke's Hospital, Kansas City, MO, USA
- Kansas City Kidney Consultants, Kansas City, MO, USA
| | - Reem Mustafa
- Department of Internal Medicine, University of Missouri-Kansas City, 2301 Holmes Street, Kansas City, MO, 64108, USA
- Department of Biomedical and Health Informatics, University of Missouri-Kansas City, Kansas City, MO, USA
- Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Canada
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Kumar PS, Venkatesh K, Sowjenya G, Srikanth L, Sunitha MM, Prasad UV, Swarupa V, Yeswanth S, Naveen PSR, Sridhar A, Kumar VS, Sarma PVGK. Mutations in exons 3 and 7 resulting in truncated expression of human ATP6V1B1 gene showing structural variations contributing to poor substrate binding-causative reason for distal renal tubular acidosis with sensorineural deafness. J Biomol Struct Dyn 2015; 33:2094-103. [PMID: 25517796 DOI: 10.1080/07391102.2014.999704] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Distal renal tubular acidosis (dRTA) is an autosomal recessive syndrome results defect in either proximal tubule bicarbonate reabsorption or in distal tubule H(+) secretion and is characterized by severe hyperchloraemic metabolic acidosis in childhood. dRTA is associated with functional variations in the ATP6V1B1 gene encoding β1 subunit of H(+)-ATPase, key membrane transporters for net acid excretion of α-intercalated cells of medullary collecting ducts. In the present study, a 13-year-old male patient suffering with nephropathy and sensorineural deafness was reported in the Department of Nephrology. We predicted improper functioning of ATP6V1B1 gene could be the reason for diseased condition. Therefore, exons 3, 4, and 7 contributing active site of ATP6V1B1 gene was amplified and sequenced (Accession numbers: KF571726, KM222653). The obtained sequences were BLAST searched against the wild type ATP6V1B1 gene which showed novel mutations c.307 A > G, c.308 C > A, c.310 C > G, c.704 T > C, c.705 G > T, c.709 A > G, c.710 A > G, c.714 G > A, c.716 C > A, c.717delC, c.722 C > G, c.728insG, c.741insT, c.753G > C. These mutations resulted in the expression of truncated protein terminating at Lys 209. The mutated ATP6V1B1structure superimposed with wild type showed extensive variations with RMSD 1.336 Å and could not bind to substrate ADP leading to non-functional ATPase. These results conclusively explain these mutations in ATP6V1B1 gene resulted in structural changes causing accumulation of H(+) ions contributing to dRTA with sensorineural deafness.
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Affiliation(s)
- Pasupuleti Santhosh Kumar
- a Department of Biotechnology , Sri Venkateswara Institute of Medical Sciences , Tirupati , AP 517507 , India
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