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Karpman D, Lindström ML, Möller M, Ivarsson S, Kristoffersson AC, Bekassy Z, Fogo AB, Elfving M. Hypoaldosteronism due to a novel SEC61A1 variant successfully treated with fludrocortisone. Clin Kidney J 2024; 17:sfae213. [PMID: 39135939 PMCID: PMC11317836 DOI: 10.1093/ckj/sfae213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Indexed: 08/15/2024] Open
Abstract
Background Genetic variants in SEC61A1 are associated with autosomal dominant tubulointerstitial kidney disease. SEC61A1 is a translocon in the endoplasmic reticulum membrane and variants affect biosynthesis of renin and uromodulin. Methods A patient is described that presented at 1 year of age with failure-to-thrive, kidney failure (glomerular filtration rate, GFR, 18 ml/min/1.73m2), hyperkalemia and acidosis. Genetic evaluation was performed by whole genome sequencing. Results The patient has a novel de novo heterozygous SEC61A1 variant, Phe458Val. Plasma renin was low or normal, aldosterone was low or undetectable and uromodulin was low. Kidney biopsy at 2 years exhibited subtle changes suggestive of tubular dysgenesis without tubulocystic or glomerulocystic lesions and with renin staining of the juxtaglomerular cells. The patient experienced extreme fatigue due to severe hypotension attributed to hypoaldosteronism and at 8 years of age fludrocortisone treatment was initiated with marked improvement in her well-being. Blood pressure and potassium normalized. Biopsy at 9 years showed extensive glomerulosclerosis and mild tubulointerstitial fibrosis, as well as tubular mitochondrial abnormalities, without specific diagnostic changes. Her GFR improved to 54 ml/min/1.73m2. Conclusions As the renin-angiotensin system promotes aldosterone release, and the patient had repeatedly undetectable aldosterone levels, the SEC61A1 variant presumably contributed to severe hypotension. Treatment with a mineralocorticoid had a beneficial effect and corrected the electrolyte and acid-base disorder. We suggest that the increased blood pressure hemodynamically improved the patient's kidney function.
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Affiliation(s)
- Diana Karpman
- Department of Pediatrics, Clinical Sciences Lund, Lund University, Lund, Sweden
| | - Martin L Lindström
- Department of Pathology, Skåne University Hospital and Regional Laboratories, Malmö, Sweden
| | - Mattias Möller
- Division of Clinical Genetics, Department of Laboratory Medicine, Lund University, Lund, Sweden
- Department of Clinical Genetics and Pathology, Region Skåne, Lund, Sweden
| | - Sofie Ivarsson
- Division of Clinical Genetics, Department of Laboratory Medicine, Lund University, Lund, Sweden
- Department of Clinical Genetics and Pathology, Region Skåne, Lund, Sweden
| | | | - Zivile Bekassy
- Department of Pediatrics, Clinical Sciences Lund, Lund University, Lund, Sweden
| | - Agnes B Fogo
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Maria Elfving
- Department of Pediatrics, Clinical Sciences Lund, Lund University, Lund, Sweden
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2
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Jung M, Zimmermann R. Quantitative Mass Spectrometry Characterizes Client Spectra of Components for Targeting of Membrane Proteins to and Their Insertion into the Membrane of the Human ER. Int J Mol Sci 2023; 24:14166. [PMID: 37762469 PMCID: PMC10532041 DOI: 10.3390/ijms241814166] [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: 08/09/2023] [Revised: 09/07/2023] [Accepted: 09/12/2023] [Indexed: 09/29/2023] Open
Abstract
To elucidate the redundancy in the components for the targeting of membrane proteins to the endoplasmic reticulum (ER) and/or their insertion into the ER membrane under physiological conditions, we previously analyzed different human cells by label-free quantitative mass spectrometry. The HeLa and HEK293 cells had been depleted of a certain component by siRNA or CRISPR/Cas9 treatment or were deficient patient fibroblasts and compared to the respective control cells by differential protein abundance analysis. In addition to clients of the SRP and Sec61 complex, we identified membrane protein clients of components of the TRC/GET, SND, and PEX3 pathways for ER targeting, and Sec62, Sec63, TRAM1, and TRAP as putative auxiliary components of the Sec61 complex. Here, a comprehensive evaluation of these previously described differential protein abundance analyses, as well as similar analyses on the Sec61-co-operating EMC and the characteristics of the topogenic sequences of the various membrane protein clients, i.e., the client spectra of the components, are reported. As expected, the analysis characterized membrane protein precursors with cleavable amino-terminal signal peptides or amino-terminal transmembrane helices as predominant clients of SRP, as well as the Sec61 complex, while precursors with more central or even carboxy-terminal ones were found to dominate the client spectra of the SND and TRC/GET pathways for membrane targeting. For membrane protein insertion, the auxiliary Sec61 channel components indeed share the client spectra of the Sec61 complex to a large extent. However, we also detected some unexpected differences, particularly related to EMC, TRAP, and TRAM1. The possible mechanistic implications for membrane protein biogenesis at the human ER are discussed and can be expected to eventually advance our understanding of the mechanisms that are involved in the so-called Sec61-channelopathies, resulting from deficient ER protein import.
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Affiliation(s)
| | - Richard Zimmermann
- Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany;
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Schlevogt B, Schlieper V, Krader J, Schröter R, Wagner T, Weiand M, Zibert A, Schmidt HH, Bergmann C, Nedvetsky PI, Krahn MP. A SEC61A1 variant is associated with autosomal dominant polycystic liver disease. Liver Int 2023; 43:401-412. [PMID: 36478640 DOI: 10.1111/liv.15493] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Revised: 10/28/2022] [Accepted: 11/12/2022] [Indexed: 01/22/2023]
Abstract
BACKGROUND AND AIMS Autosomal dominant polycystic liver and kidney disease is a spectrum of hereditary diseases, which display disturbed function of primary cilia leading to cyst formation. In autosomal dominant polycystic kidney disease a genetic cause can be determined in almost all cases. However, in isolated polycystic liver disease (PLD) about half of all cases remain genetically unsolved, suggesting more, so far unidentified genes to be implicated in this disease. METHODS Customized next-generation sequencing was used to identify the underlying pathogenesis in two related patients with PLD. A variant identified in SEC61A1 was further analysed in immortalized patients' urine sediment cells and in an epithelial cell model. RESULTS In both patients, a heterozygous missense change (c.706C>T/p.Arg236Cys) was found in SEC61A1, which encodes for a subunit of the translocation machinery of protein biosynthesis at the endoplasmic reticulum (ER). While kidney disease is absent in the proposita, her mother displays an atypical polycystic kidney phenotype with severe renal failure. In immortalized urine sediment cells, mutant SEC61A1 is expressed at reduced levels, resulting in decreased levels of polycystin-2 (PC2). In an epithelial cell culture model, we found the proteasomal degradation of mutant SEC61A1 to be increased, whereas its localization to the ER is not affected. CONCLUSIONS Our data expand the allelic and clinical spectrum for SEC61A1, adding PLD as a new and the major phenotypic trait in the family described. We further demonstrate that mutant SEC61A1 results in enhanced proteasomal degradation and impaired biosynthesis of PC2.
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Affiliation(s)
- Bernhard Schlevogt
- Department of Medicine B, University Hospital Muenster, Muenster, Germany
| | - Vincent Schlieper
- Department of Medicine D, University Hospital Muenster, Muenster, Germany
| | - Jana Krader
- Department of Medicine D, University Hospital Muenster, Muenster, Germany
| | - Rita Schröter
- Department of Medicine D, University Hospital Muenster, Muenster, Germany
| | - Thomas Wagner
- Department of Medicine D, University Hospital Muenster, Muenster, Germany
| | - Matthias Weiand
- Department of Medicine B, University Hospital Muenster, Muenster, Germany
| | - Andree Zibert
- Department of Medicine B, University Hospital Muenster, Muenster, Germany
| | - Hartmut H Schmidt
- Department of Medicine B, University Hospital Muenster, Muenster, Germany.,Department of Gastroenterology and Hepatology, University Hospital Essen, Essen, Germany
| | - Carsten Bergmann
- Department of Medicine IV, Faculty of Medicine, Medical Center-University of Freiburg, Freiburg, Germany.,Medizinische Genetik Mainz, Limbach Genetics, Mainz, Germany
| | - Pavel I Nedvetsky
- Department of Medicine D, University Hospital Muenster, Muenster, Germany
| | - Michael P Krahn
- Department of Medicine D, University Hospital Muenster, Muenster, Germany
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4
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Autosomal dominant tubulointerstitial kidney disease: more than just HNF1β. Pediatr Nephrol 2022; 37:933-946. [PMID: 34021396 PMCID: PMC8722360 DOI: 10.1007/s00467-021-05118-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/14/2021] [Accepted: 05/04/2021] [Indexed: 12/25/2022]
Abstract
Autosomal dominant tubulointerstitial kidney disease (ADTKD) refers to a group of disorders with a bland urinary sediment, slowly progressive chronic kidney disease (CKD), and autosomal dominant inheritance. Due to advances in genetic diagnosis, ADTKD is becoming increasingly recognized as a cause of CKD in both children and adults. ADTKD-REN presents in childhood with mild hypotension, CKD, hyperkalemia, acidosis, and anemia. ADTKD-UMOD is associated with gout and CKD that may present in adolescence and slowly progresses to kidney failure. HNF1β mutations often present in childhood with anatomic abnormalities such as multicystic or dysplastic kidneys, as well as CKD and a number of other extra-kidney manifestations. ADTKD-MUC1 is less common in childhood, and progressive CKD is its sole clinical manifestation, usually beginning in the late teenage years. This review describes the pathophysiology, genetics, clinical characteristics, diagnosis, and treatment of the different forms of ADTKD, with an emphasis on diagnosis. We also present data on kidney function in children with ADTKD from the Wake Forest Rare Inherited Kidney Disease Registry.
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Sicking M, Živná M, Bhadra P, Barešová V, Tirincsi A, Hadzibeganovic D, Hodaňová K, Vyleťal P, Sovová J, Jedličková I, Jung M, Bell T, Helms V, Bleyer AJ, Kmoch S, Cavalié A, Lang S. Phenylbutyrate rescues the transport defect of the Sec61α mutations V67G and T185A for renin. Life Sci Alliance 2022; 5:e202101150. [PMID: 35064074 PMCID: PMC8807872 DOI: 10.26508/lsa.202101150] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 01/06/2022] [Accepted: 01/06/2022] [Indexed: 11/24/2022] Open
Abstract
The human Sec61 complex is a widely distributed and abundant molecular machine. It resides in the membrane of the endoplasmic reticulum to channel two types of cargo: protein substrates and calcium ions. The SEC61A1 gene encodes for the pore-forming Sec61α subunit of the Sec61 complex. Despite their ubiquitous expression, the idiopathic SEC61A1 missense mutations p.V67G and p.T185A trigger a localized disease pattern diagnosed as autosomal dominant tubulointerstitial kidney disease (ADTKD-SEC61A1). Using cellular disease models for ADTKD-SEC61A1, we identified an impaired protein transport of the renal secretory protein renin and a reduced abundance of regulatory calcium transporters, including SERCA2. Treatment with the molecular chaperone phenylbutyrate reversed the defective protein transport of renin and the imbalanced calcium homeostasis. Signal peptide substitution experiments pointed at targeting sequences as the cause for the substrate-specific impairment of protein transport in the presence of the V67G or T185A mutations. Similarly, dominant mutations in the signal peptide of renin also cause ADTKD and point to impaired transport of this renal hormone as important pathogenic feature for ADTKD-SEC61A1 patients as well.
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Affiliation(s)
- Mark Sicking
- Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
| | - Martina Živná
- Research Unit for Rare Diseases, Department of Pediatrics and Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Pratiti Bhadra
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Veronika Barešová
- Research Unit for Rare Diseases, Department of Pediatrics and Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Andrea Tirincsi
- Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
| | - Drazena Hadzibeganovic
- Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
| | - Kateřina Hodaňová
- Research Unit for Rare Diseases, Department of Pediatrics and Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Petr Vyleťal
- Research Unit for Rare Diseases, Department of Pediatrics and Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Jana Sovová
- Research Unit for Rare Diseases, Department of Pediatrics and Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Ivana Jedličková
- Research Unit for Rare Diseases, Department of Pediatrics and Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Martin Jung
- Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
| | - Thomas Bell
- Department of Chemistry, University of Nevada, Reno, NV, USA
| | - Volkhard Helms
- Center for Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Anthony J Bleyer
- Research Unit for Rare Diseases, Department of Pediatrics and Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
- Section on Nephrology, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Stanislav Kmoch
- Research Unit for Rare Diseases, Department of Pediatrics and Metabolic Disorders, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Adolfo Cavalié
- Experimental and Clinical Pharmacology and Toxicology, Pre-clinical Center for Molecular Signaling (PZMS), Saarland University, Homburg, Germany
| | - Sven Lang
- Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
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Tirincsi A, Sicking M, Hadzibeganovic D, Haßdenteufel S, Lang S. The Molecular Biodiversity of Protein Targeting and Protein Transport Related to the Endoplasmic Reticulum. Int J Mol Sci 2021; 23:143. [PMID: 35008565 PMCID: PMC8745461 DOI: 10.3390/ijms23010143] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/19/2021] [Accepted: 12/20/2021] [Indexed: 12/15/2022] Open
Abstract
Looking at the variety of the thousands of different polypeptides that have been focused on in the research on the endoplasmic reticulum from the last five decades taught us one humble lesson: no one size fits all. Cells use an impressive array of components to enable the safe transport of protein cargo from the cytosolic ribosomes to the endoplasmic reticulum. Safety during the transit is warranted by the interplay of cytosolic chaperones, membrane receptors, and protein translocases that together form functional networks and serve as protein targeting and translocation routes. While two targeting routes to the endoplasmic reticulum, SRP (signal recognition particle) and GET (guided entry of tail-anchored proteins), prefer targeting determinants at the N- and C-terminus of the cargo polypeptide, respectively, the recently discovered SND (SRP-independent) route seems to preferentially cater for cargos with non-generic targeting signals that are less hydrophobic or more distant from the termini. With an emphasis on targeting routes and protein translocases, we will discuss those functional networks that drive efficient protein topogenesis and shed light on their redundant and dynamic nature in health and disease.
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Affiliation(s)
- Andrea Tirincsi
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany; (A.T.); (M.S.); (D.H.)
| | - Mark Sicking
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany; (A.T.); (M.S.); (D.H.)
| | - Drazena Hadzibeganovic
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany; (A.T.); (M.S.); (D.H.)
| | - Sarah Haßdenteufel
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Sven Lang
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany; (A.T.); (M.S.); (D.H.)
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Sicking M, Lang S, Bochen F, Roos A, Drenth JPH, Zakaria M, Zimmermann R, Linxweiler M. Complexity and Specificity of Sec61-Channelopathies: Human Diseases Affecting Gating of the Sec61 Complex. Cells 2021; 10:1036. [PMID: 33925740 PMCID: PMC8147068 DOI: 10.3390/cells10051036] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 04/15/2021] [Accepted: 04/17/2021] [Indexed: 12/14/2022] Open
Abstract
The rough endoplasmic reticulum (ER) of nucleated human cells has crucial functions in protein biogenesis, calcium (Ca2+) homeostasis, and signal transduction. Among the roughly one hundred components, which are involved in protein import and protein folding or assembly, two components stand out: The Sec61 complex and BiP. The Sec61 complex in the ER membrane represents the major entry point for precursor polypeptides into the membrane or lumen of the ER and provides a conduit for Ca2+ ions from the ER lumen to the cytosol. The second component, the Hsp70-type molecular chaperone immunoglobulin heavy chain binding protein, short BiP, plays central roles in protein folding and assembly (hence its name), protein import, cellular Ca2+ homeostasis, and various intracellular signal transduction pathways. For the purpose of this review, we focus on these two components, their relevant allosteric effectors and on the question of how their respective functional cycles are linked in order to reconcile the apparently contradictory features of the ER membrane, selective permeability for precursor polypeptides, and impermeability for Ca2+. The key issues are that the Sec61 complex exists in two conformations: An open and a closed state that are in a dynamic equilibrium with each other, and that BiP contributes to its gating in both directions in cooperation with different co-chaperones. While the open Sec61 complex forms an aqueous polypeptide-conducting- and transiently Ca2+-permeable channel, the closed complex is impermeable even to Ca2+. Therefore, we discuss the human hereditary and tumor diseases that are linked to Sec61 channel gating, termed Sec61-channelopathies, as disturbances of selective polypeptide-impermeability and/or aberrant Ca2+-permeability.
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Affiliation(s)
- Mark Sicking
- Department of Medical Biochemistry & Molecular Biology, Saarland University, D-66421 Homburg, Germany;
| | - Sven Lang
- Department of Medical Biochemistry & Molecular Biology, Saarland University, D-66421 Homburg, Germany;
| | - Florian Bochen
- Department of Otorhinolaryngology, Head and Neck Surgery, Saarland University Medical Center, D-66421 Homburg, Germany; (F.B.); (M.L.)
| | - Andreas Roos
- Department of Neuropediatrics, Essen University Hospital, D-45147 Essen, Germany;
| | - Joost P. H. Drenth
- Department of Molecular Gastroenterology and Hepatology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands;
| | - Muhammad Zakaria
- Department of Genetics, Hazara University, Mansehra 21300, Pakistan;
| | - Richard Zimmermann
- Department of Medical Biochemistry & Molecular Biology, Saarland University, D-66421 Homburg, Germany;
| | - Maximilian Linxweiler
- Department of Otorhinolaryngology, Head and Neck Surgery, Saarland University Medical Center, D-66421 Homburg, Germany; (F.B.); (M.L.)
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