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Sun AB, Li FH, Zhu L, Zeng XX, Zhu M, Lei QH, Liao YH. TRPC6 Knockout Alleviates Renal Fibrosis through PI3K/AKT/GSK3B Pathway. Curr Med Sci 2024; 44:589-602. [PMID: 38748370 DOI: 10.1007/s11596-024-2869-z] [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: 12/21/2023] [Accepted: 03/22/2024] [Indexed: 06/29/2024]
Abstract
OBJECTIVE Renal fibrosis is the ultimate pathway of various forms of acute and chronic kidney damage. Notably, the knockout of transient receptor potential channel 6 (TRPC6) has shown promise in alleviating renal fibrosis. However, the regulatory impact of TRPC6 on renal fibrosis remains unclear. METHODS In vivo, TRPC6 knockout (TRPC6-/-) mice and age-matched 129 SvEv (WT) mice underwent unilateral renal ischemia-reperfusion (uIR) injury surgery on the left renal pedicle or sham operation. Kidneys and serum were collected on days 7, 14, 21, and 28 after euthanasia. In vitro, primary tubular epithelial cells (PTECs) were isolated from TRPC6-/- and WT mice, followed by treatment with transforming growth factor β1 (TGFβ1) for 72 h. The anti-fibrotic effect of TRPC6-/- and the underlying mechanisms were assessed through hematoxylin-eosin staining, Masson staining, immunostaining, qRT-PCR, and Western blotting. RESULTS Increased TRPC6 expression was observed in uIR mice and PTECs treated with TGFβ1. TRPC6-/- alleviated renal fibrosis by reducing the expression of fibrotic markers (Col-1, α-SMA, and vimentin), as well as decreasing the apoptosis and inflammation of PTECs during fibrotic progression both in vivo and in vitro. Additionally, we found that the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/glycogen synthase kinase 3 beta (GSK3β) signaling pathway, a pivotal player in renal fibrosis, was down-regulated following TRPC6 deletion. CONCLUSION These results suggest that the ablation of TRPC6 may mitigate renal fibrosis by inhibiting the apoptosis and inflammation of PTECs through down-regulation of the PI3K/AKT/GSK3β pathway. Targeting TRPC6 could be a novel therapeutic strategy for preventing chronic kidney disease.
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Affiliation(s)
- An-Bang Sun
- Department of Anatomy, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
- Department of Transfusion Medicine, Wuhan Hospital of Traditional Chinese and Western Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Fang-Hua Li
- Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Lin Zhu
- Department of Anatomy, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
- Department of Transfusion Medicine, Wuhan Hospital of Traditional Chinese and Western Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Xi-Xi Zeng
- Department of Anatomy, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Min Zhu
- Department of Thoracic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Qing-Hua Lei
- Department of Anatomy, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
- National Basic Medical Teaching Demonstration Center, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Yan-Hong Liao
- Department of Anatomy, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
- Key Laboratory of Neurological Diseases of Ministry of Education, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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2
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Bonilla M, Efe O, Selvaskandan H, Lerma EV, Wiegley N. A Review of Focal Segmental Glomerulosclerosis Classification With a Focus on Genetic Associations. Kidney Med 2024; 6:100826. [PMID: 38765809 PMCID: PMC11099322 DOI: 10.1016/j.xkme.2024.100826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) defines a distinct histologic pattern observed in kidney tissue that is linked to several distinct underlying causes, all converging on the common factor of podocyte injury. It presents a considerable challenge in terms of classification because of its varied underlying causes and the limited correlation between histopathology and clinical outcomes. Critically, precise nomenclature is key to describe and delineate the pathogenesis, subsequently guiding the selection of suitable and precision therapies. A proposed pathomechanism-based approach has been suggested for FSGS classification. This approach differentiates among primary, secondary, genetic, and undetermined causes, aiming to provide clarity. Genetic FSGS from monogenic mutations can emerge during childhood or adulthood, and it is advisable to conduct genetic testing in cases in which there is a family history of chronic kidney disease, nephrotic syndrome, or resistance to treatment. Genome-wide association studies have identified several genetic risk variants, such as those in apolipoprotein L1 (APOL1), that play a role in the development of FSGS. Currently, no specific treatments have been approved to treat genetic FSGS; however, interventions targeting underlying cofactor deficiencies have shown potential in some cases. Furthermore, encouraging results have emerged from a phase 2 trial investigating inaxaplin, a novel small molecule APOL1 channel inhibitor, in APOL1-associated FSGS.
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Affiliation(s)
- Marco Bonilla
- Section of Nephrology, Department of Medicine, University of Chicago, Chicago, IL
| | - Orhan Efe
- Division of Nephrology, Massachusetts General Hospital, Boston, MA
- Harvard Medical School, Boston, MA
| | - Haresh Selvaskandan
- IgA Mayer Nephropathy Laboratories, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- John Walls Renal Unit, University Hospitals of Leicester NHS Trust, Leicester, United Kingdom
| | - Edgar V. Lerma
- Section of Nephrology, University of Illinois at Chicago/Advocate Christ Medical Center, Oak Lawn, IL
| | - Nasim Wiegley
- University of California Davis School of Medicine, Division of Nephrology, Sacramento, CA
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3
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Nayak A, Ettenger R, Wesseling-Perry K. Recurrent disease after pediatric renal transplantation. Pediatr Transplant 2024; 28:e14676. [PMID: 38650536 DOI: 10.1111/petr.14676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 11/15/2023] [Accepted: 11/30/2023] [Indexed: 04/25/2024]
Abstract
BACKGROUND Recurrent disease after kidney transplant remains an important cause of allograft failure, accounting for 7-8% of graft loss and ranking as the fifth most common cause of allograft loss in the pediatric population. Although the pathophysiology of many recurrent diseases is incompletely understood, recent advances in basic science and therapeutics are improving outcomes and changing the course of several of these conditions. METHODS Review of the literature. RESULTS We discuss the diagnosis and management of recurrent disease. CONCLUSION We highlight new insights into the pathophysiology and treatment of post-transplant primary hyperoxaluria, focal segmental glomerulosclerosis, immune complex glomerulonephritis, C3 glomerulopathy, lupus nephritis, atypical hemolytic uremic syndrome, and IgA nephropathy.
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Affiliation(s)
- Anjali Nayak
- Phoenix Children's Hospital and the University of Arizona College of Medicine, Tucson, Arizona, USA
| | - Robert Ettenger
- Mattel Children's Hospital and the University of California at Los Angeles, Los Angeles, California, USA
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4
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Yu T, Ji Y, Cui X, Liang N, Wu S, Xiang C, Li Y, Tao H, Xie Y, Zuo H, Wang W, Khan N, Ullah K, Xu F, Zhang Y, Lin C. Novel Pathogenic Mutation of P209L in TRPC6 Gene Causes Adult Focal Segmental Glomerulosclerosis. Biochem Genet 2024:10.1007/s10528-023-10651-y. [PMID: 38315264 DOI: 10.1007/s10528-023-10651-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Accepted: 12/27/2023] [Indexed: 02/07/2024]
Abstract
Focal segmental glomerulosclerosis (FSGS) is a leading kidney disease, clinically associated with proteinuria and progressive renal failure. The occurrence of this disease is partly related to gene mutations. We describe a single affected family member who presented with FSGS. We used high-throughput sequencing, sanger sequencing to identify the pathogenic mutations, and a systems genetics analysis in the BXD mice was conducted to explore the genetic regulatory mechanisms of pathogenic genes in the development of FSGS. We identified high urinary protein (++++) and creatinine levels (149 μmol/L) in a 29-year-old male diagnosed with a 5-year history of grade 2 hypertension. Histopathology of the kidney biopsy showed stromal hyperplasia at the glomerular segmental sclerosis and endothelial cell vacuolation degeneration. Whole-exome sequencing followed by Sanger sequencing revealed a heterozygous missense mutation (c.643C > T) in exon 2 of TRPC6, leading to the substitution of arginine with tryptophan at position 215 (p.Arg215Trp). Systems genetics analysis of the 53 BXD mice kidney transcriptomes identified Pygm as the upstream regulator of Trpc6. Those two genes are jointly involved in the regulation of FSGS mainly via Wnt and Hippo signaling pathways. We present a novel variant in the TRPC6 gene that causes FSGS. Moreover, our data suggested TRPC6 works with PYGM, as well as Wnt and Hippo signaling pathways to regulate renal function, which could guide future clinical prevention and targeted treatment for FSGS outcomes.
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Affiliation(s)
- Tianxi Yu
- School of Clinical Medicine, Weifang Medical University, Weifang, 261042, China
- Department of Urology, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, 264000, Shandong, China
| | - Yongqiang Ji
- Department of Nephrology, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, 264000, Shandong, China
| | - Xin Cui
- School of Clinical Medicine, Weifang Medical University, Weifang, 261042, China
- Department of Urology, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, 264000, Shandong, China
| | - Ning Liang
- School of Clinical Medicine, Weifang Medical University, Weifang, 261042, China
- Department of Urology, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, 264000, Shandong, China
| | - Shuang Wu
- Department of Urology, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, 264000, Shandong, China
| | - Chongjun Xiang
- Department of Urology, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, 264000, Shandong, China
- The 2nd Medical College of Binzhou Medical University, Yantai, 264003, Shandong, China
| | - Yue Li
- Department of Urology, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, 264000, Shandong, China
- The 2nd Medical College of Binzhou Medical University, Yantai, 264003, Shandong, China
| | - Huiying Tao
- Department of Urology, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, 264000, Shandong, China
- The 2nd Medical College of Binzhou Medical University, Yantai, 264003, Shandong, China
| | - Yaqi Xie
- Department of Urology, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, 264000, Shandong, China
- The 2nd Medical College of Binzhou Medical University, Yantai, 264003, Shandong, China
| | - Hongwei Zuo
- Department of Urology, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, 264000, Shandong, China
- The 2nd Medical College of Binzhou Medical University, Yantai, 264003, Shandong, China
| | - Wenting Wang
- Central Laboratory, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, 264000, Shandong, China
| | - Nauman Khan
- Department of Biology, Faculty of Biological and Biomedical Sciences, The University of Haripur, Haripur, KP, Pakistan
| | - Kamran Ullah
- Department of Biology, Faculty of Biological and Biomedical Sciences, The University of Haripur, Haripur, KP, Pakistan
| | - Fuyi Xu
- Shandong Technology Innovation Center of Molecular Targeting and Intelligent Diagnosis and Treatment, Binzhou Medical University, Yantai, 264003, Shandong, China
| | - Yan Zhang
- Department of Nephrology, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, 264000, Shandong, China.
| | - Chunhua Lin
- Department of Urology, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, 264000, Shandong, China.
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Batool L, Hariharan K, Xu Y, Kaßmann M, Tsvetkov D, Gohlke BO, Kaden S, Gossen M, Nürnberg B, Kurtz A, Gollasch M. An inactivating human TRPC6 channel mutation without focal segmental glomerulosclerosis. Cell Mol Life Sci 2023; 80:265. [PMID: 37615749 PMCID: PMC10449997 DOI: 10.1007/s00018-023-04901-w] [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: 03/24/2023] [Revised: 07/27/2023] [Accepted: 07/28/2023] [Indexed: 08/25/2023]
Abstract
Transient receptor potential cation channel-6 (TRPC6) gene mutations cause familial focal segmental glomerulosclerosis (FSGS), which is inherited as an autosomal dominant disease. In patients with TRPC6-related FSGS, all mutations map to the N- or C-terminal TRPC6 protein domains. Thus far, the majority of TRPC6 mutations are missense resulting in increased or decreased calcium influx; however, the fundamental molecular mechanisms causing cell injury and kidney pathology are unclear. We report a novel heterozygous TRPC6 mutation (V691Kfs*) in a large kindred with no signs of FSGS despite a largely truncated TRPC6 protein. We studied the molecular effects of V691Kfs* TRPC6 mutant using the tridimensional cryo-EM structure of the tetrameric TRPC6 protein. The results indicated that V691 is localized at the pore-forming transmembrane region affecting the ion conduction pathway, and predicted that V691Kfs* causes closure of the ion-conducting pathway leading to channel inactivation. We assessed the impact of V691Kfs* and two previously reported TRPC6 disease mutants (P112Q and G757D) on calcium influx in cells. Our data show that the V691Kfs* fully inactivated the TRCP6 channel-specific calcium influx consistent with a complete loss-of-function phenotype. Furthermore, the V691Kfs* truncation exerted a dominant negative effect on the full-length TRPC6 proteins. In conclusion, the V691Kfs* non-functional truncated TRPC6 is not sufficient to cause FSGS. Our data corroborate recently characterized TRPC6 loss-of-function and gain-of-function mutants suggesting that one defective TRPC6 gene copy is not sufficient to cause FSGS. We underscore the importance of increased rather than reduced calcium influx through TRPC6 for podocyte cell death.
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Affiliation(s)
- Lilas Batool
- BIH Center for Regenerative Therapies (BCRT), Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
| | - Krithika Hariharan
- BIH Center for Regenerative Therapies (BCRT), Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
- Fraunhofer-Institute for Biomedical Engineering (IBMT), Fraunhofer Project Center for Stem Cell Process Engineering, Würzburg, Germany
| | - Yao Xu
- Klinik und Poliklinik für Innere Medizin D-Geriatrie, Universitätsmedizin Greifswald, Ferdinand-Sauerbruch-Straße, Greifswald, Germany
| | - Mario Kaßmann
- Klinik und Poliklinik für Innere Medizin D-Geriatrie, Universitätsmedizin Greifswald, Ferdinand-Sauerbruch-Straße, Greifswald, Germany
| | - Dmitry Tsvetkov
- Klinik und Poliklinik für Innere Medizin D-Geriatrie, Universitätsmedizin Greifswald, Ferdinand-Sauerbruch-Straße, Greifswald, Germany
| | - Björn-Oliver Gohlke
- Department of Information Technology, Science-IT, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Sylvia Kaden
- Electron Microscopy Core Facility, German Cancer Research Center, Heidelberg, Germany
| | - Manfred Gossen
- BIH Center for Regenerative Therapies (BCRT), Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
- Institut für Aktive Polymere, Hereon TeltowAbteilung Stammzellmodifikation und Biomaterialien, Teltow, Germany
| | - Bernd Nürnberg
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, University of Tübingen, Tübingen, Germany
| | - Andreas Kurtz
- BIH Center for Regenerative Therapies (BCRT), Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany.
- Biomedical Data and Bioethics, Fraunhofer-Institute for Biomedical Engineering (IBMT), Berlin, Germany.
| | - Maik Gollasch
- Klinik und Poliklinik für Innere Medizin D-Geriatrie, Universitätsmedizin Greifswald, Ferdinand-Sauerbruch-Straße, Greifswald, Germany.
- Klinik für Nephrologie und Internistische Intensivmedizin, Charité-Universitätsmedizin Berlin, Berlin, Germany.
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6
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Gokce I, Kaya M, Cicek N, Guven S, Ercetin Y, Yildiz N, Kaya H, Alpay H. Collapsing Glomerulopathy in a Patient with a TRPC6 Mutation Presenting as Rapidly Progressive Glomerulonephritis: A Case Report and Review of the Literature. SAUDI JOURNAL OF KIDNEY DISEASES AND TRANSPLANTATION 2023; 34:254-258. [PMID: 38231721 DOI: 10.4103/1319-2442.393999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2024] Open
Abstract
Collapsing glomerulopathy (CG) is a proliferative disease characterized by segmental or global wrinkling of the glomerular basement membrane and the formation of pseudocrescents, whereas focal segmental glomerulosclerosis (FSGS) is characterized by podocytopenia, and focal and segmental sclerosis of the glomeruli. Mutations in NPHS1, NPHS2, WT1, PLCE1, CD2AP, ACTN4, and TRPC6 have been reported in steroid-resistant FSGS patients. The mutations p.R895C and p.R895L in Exon 13 are the only ones in TRPC6 causing CG reported to date. Here, we present the case of a 17-year-old male patient with a collapsing variant of familial FSGS caused by a mutation in TRPC6 (p.R895C) who presented with rapidly progressive (crescentic) and proliferative glomerulonephritis.
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Affiliation(s)
- Ibrahim Gokce
- Department of Pediatric Nephrology, Marmara University Medical School, Istanbul, Turkey
| | - Mehtap Kaya
- Department of Pediatric Nephrology, Marmara University Medical School, Istanbul, Turkey
| | - Neslihan Cicek
- Department of Pediatric Nephrology, Marmara University Medical School, Istanbul, Turkey
| | - Sercin Guven
- Department of Pediatric Nephrology, Marmara University Medical School, Istanbul, Turkey
| | - Yigit Ercetin
- Department of Medical Pathology, Marmara University Medical School, Istanbul, Turkey
| | - Nurdan Yildiz
- Department of Pediatric Nephrology, Marmara University Medical School, Istanbul, Turkey
| | - Handan Kaya
- Department of Medical Pathology, Marmara University Medical School, Istanbul, Turkey
| | - Harika Alpay
- Department of Pediatric Nephrology, Marmara University Medical School, Istanbul, Turkey
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7
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Mishra S, Ma J, McKoy D, Sasaki M, Farinelli F, Page RC, Ranek MJ, Zachara N, Kass DA. Transient receptor potential canonical type 6 (TRPC6) O-GlcNAcylation at Threonine-221 plays potent role in channel regulation. iScience 2023; 26:106294. [PMID: 36936781 PMCID: PMC10014292 DOI: 10.1016/j.isci.2023.106294] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 01/16/2023] [Accepted: 02/20/2023] [Indexed: 03/11/2023] Open
Abstract
Transient receptor potential canonical type 6 (TRPC6) is a non-voltage-gated channel that principally conducts calcium. Elevated channel activation contributes to fibrosis, hypertrophy, and proteinuria, often coupled to stimulation of nuclear factor of activated T-cells (NFAT). TRPC6 is post-translationally regulated, but a role for O-linked β-N-acetyl glucosamine (O-GlcNAcylation) as elevated by diabetes, is unknown. Here we show TRPC6 is constitutively O-GlcNAcylated at Ser14, Thr70, and Thr221 in the N-terminus ankryn-4 (AR4) and linker (LH1) domains. Mutagenesis to alanine reveals T221 as a critical controller of resting TRPC6 conductance, and associated NFAT activity and pro-hypertrophic signaling. T→A mutations at sites homologous in closely related TRPC3 and TRPC7 also increases their activity. Molecular modeling predicts interactions between Thr221-O-GlcNAc and Ser199, Glu200, and Glu246, and combined alanine substitutions of the latter similarly elevates resting NFAT activity. Thus, O-GlcNAcylated T221 and interactions with coordinating residues is required for normal TRPC6 channel conductance and NFAT activation.
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Affiliation(s)
- Sumita Mishra
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Junfeng Ma
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, USA
| | - Desirae McKoy
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Masayuki Sasaki
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Federica Farinelli
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Richard C. Page
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, USA
| | - Mark J. Ranek
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Natasha Zachara
- Department of Biological Chemistry, Department of Oncology, Johns Hopkins University, Baltimore, MD, USA
| | - David A. Kass
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University, Baltimore, MD, USA
- Corresponding author
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8
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Genetic nephrotic syndrome associated with disturbed function of glomerular slit membrane and podocyte cytoskeleton in children. Clin Exp Nephrol 2023; 27:101-109. [PMID: 36482266 DOI: 10.1007/s10157-022-02305-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 11/29/2022] [Indexed: 12/13/2022]
Abstract
BACKGROUND Genetic nephrotic syndrome is caused by pathogenic variants in genes encoding proteins necessary for the stability and functionality of the glomerular filtration barrier. To date, more than 70 genes associated with steroid-resistant nephrotic syndrome have been identified. We review the clinical and molecular aspects of genetic nephrotic syndrome with a particular focus on genes associated with slit membrane and podocyte cytoskeleton defects. Sanger sequencing and next-generation sequencing are widely used in the identification of novel gene variants and help us gain a better understanding of the disease. Despite these findings, therapy is mainly supportive and focused on the reduction of proteinuria and management of chronic kidney disease with an unfavorable outcome for a significant proportion of cases. Positive therapeutic effects of immunosuppressive drugs have been reported in some patients; however, their long-time administration cannot be generally recommended. CONCLUSION Personalized treatment based on understanding the distinct disease pathogenesis is needed. With this, it will be possible to avoid harmful immunosuppressive therapy and improve outcomes and quality of life for pediatric patients suffering from genetic nephrotic syndrome.
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Staruschenko A, Ma R, Palygin O, Dryer SE. Ion channels and channelopathies in glomeruli. Physiol Rev 2023; 103:787-854. [PMID: 36007181 PMCID: PMC9662803 DOI: 10.1152/physrev.00013.2022] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 08/15/2022] [Accepted: 08/21/2022] [Indexed: 11/22/2022] Open
Abstract
An essential step in renal function entails the formation of an ultrafiltrate that is delivered to the renal tubules for subsequent processing. This process, known as glomerular filtration, is controlled by intrinsic regulatory systems and by paracrine, neuronal, and endocrine signals that converge onto glomerular cells. In addition, the characteristics of glomerular fluid flow, such as the glomerular filtration rate and the glomerular filtration fraction, play an important role in determining blood flow to the rest of the kidney. Consequently, disease processes that initially affect glomeruli are the most likely to lead to end-stage kidney failure. The cells that comprise the glomerular filter, especially podocytes and mesangial cells, express many different types of ion channels that regulate intrinsic aspects of cell function and cellular responses to the local environment, such as changes in glomerular capillary pressure. Dysregulation of glomerular ion channels, such as changes in TRPC6, can lead to devastating glomerular diseases, and a number of channels, including TRPC6, TRPC5, and various ionotropic receptors, are promising targets for drug development. This review discusses glomerular structure and glomerular disease processes. It also describes the types of plasma membrane ion channels that have been identified in glomerular cells, the physiological and pathophysiological contexts in which they operate, and the pathways by which they are regulated and dysregulated. The contributions of these channels to glomerular disease processes, such as focal segmental glomerulosclerosis (FSGS) and diabetic nephropathy, as well as the development of drugs that target these channels are also discussed.
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Affiliation(s)
- Alexander Staruschenko
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida
- Hypertension and Kidney Research Center, University of South Florida, Tampa, Florida
- James A. Haley Veterans Hospital, Tampa, Florida
| | - Rong Ma
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Oleg Palygin
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Stuart E Dryer
- Department of Biology and Biochemistry, University of Houston, Houston, Texas
- Department of Biomedical Sciences, Tilman J. Fertitta Family College of Medicine, University of Houston, Houston, Texas
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10
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Dryer SE, Kim EY. The Effects of TRPC6 Knockout in Animal Models of Kidney Disease. Biomolecules 2022; 12:1710. [PMID: 36421724 PMCID: PMC9687984 DOI: 10.3390/biom12111710] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/12/2022] [Accepted: 11/14/2022] [Indexed: 11/21/2023] Open
Abstract
Diseases that induce a loss of renal function affect a substantial portion of the world's population and can range from a slight decline in the glomerular filtration rate or microalbuminuria to complete kidney failure. Kidney disorders can be acute or chronic, but any significant reduction in renal function is associated with increased all-cause morbidity and mortality, especially when the conditions become chronic. There is an urgent need for new therapeutic approaches to slow or halt the progression of kidney disease. One potential target of considerable interest is the canonical transient receptor potential-6 (TRPC6) channel. TRCP6 is a cationic channel with a significant permeability to Ca2+. It is expressed in several tissues, including in multiple cell types of the kidney in glomeruli, microvasculature, and tubules. Here, we will describe TRPC6 channels and their roles in signal transduction, with an emphasis on renal cells, and the studies implicating TRPC6 channels in the progression of inherited and acquired kidney diseases. We then describe studies using TRPC6 knockout mice and rats subjected to treatments that model human diseases, including nephrotic syndromes, diabetic nephropathy, autoimmune glomerulonephritis, and acute kidney injuries induced by renal ischemia and by obstruction of the urinary tract. TRPC6 knockout has been shown to reduce glomerular manifestations of disease in several of these models and reduces renal fibrosis caused by urinary tract obstruction. TRPC6 knockout has proven to be less effective at reducing diabetic nephropathy in mouse and rat models. We also summarize the implications of these studies for drug development.
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Affiliation(s)
- Stuart E. Dryer
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204-5001, USA
- Department of Biomedical Sciences, Tilman J. Fertitta Family College of Medicine, University of Houston, Houston, TX 77204-5001, USA
| | - Eun Young Kim
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204-5001, USA
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11
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Sambharia M, Rastogi P, Thomas CP. Monogenic focal segmental glomerulosclerosis: A conceptual framework for identification and management of a heterogeneous disease. AMERICAN JOURNAL OF MEDICAL GENETICS. PART C, SEMINARS IN MEDICAL GENETICS 2022; 190:377-398. [PMID: 35894442 PMCID: PMC9796580 DOI: 10.1002/ajmg.c.31990] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 05/31/2022] [Accepted: 06/30/2022] [Indexed: 01/29/2023]
Abstract
Focal segmental glomerulosclerosis (FSGS) is not a disease, rather a pattern of histological injury occurring from a variety of causes. The exact pathogenesis has yet to be fully elucidated but is likely varied based on the type of injury and the primary target of that injury. However, the approach to treatment is often based on the degree of podocyte foot process effacement and clinical presentation without sufficient attention paid to etiology. In this regard, there are many monogenic causes of FSGS with variable presentation from nephrotic syndrome with histological features of primary podocytopathy to more modest degrees of proteinuria with limited evidence of podocyte foot process injury. It is likely that genetic causes are largely underdiagnosed, as the role and the timing of genetic testing in FSGS is not established and genetic counseling, testing options, and interpretation of genotype in the context of phenotype may be outside the scope of practice for both nephrologists and geneticists. Yet most clinicians believe that a genetic diagnosis can lead to targeted therapy, limit the use of high-dose corticosteroids as a therapeutic trial, and allow the prediction of the natural history and risk for recurrence in the transplanted kidney. In this manuscript, we emphasize that genetic FSGS is not monolithic in its presentation, opine on the importance of genetic testing and provide an algorithmic approach to deployment of genetic testing in a timely fashion when faced with a patient with FSGS.
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Affiliation(s)
- Meenakshi Sambharia
- Division of Nephrology, Department of Internal MedicineUniversity of IowaIowa CityIowaUSA
| | - Prerna Rastogi
- Department of PathologyUniversity of IowaIowa CityIowaUSA
| | - Christie P. Thomas
- Division of Nephrology, Department of Internal MedicineUniversity of IowaIowa CityIowaUSA,Department of PediatricsUniversity of IowaIowa CityIowaUSA,The Iowa Institute of Human GeneticsUniversity of IowaIowa CityIowaUSA,Medical ServiceVeterans Affairs Medical CenterIowa CityIowaUSA
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12
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Kim EY, Dryer SE. TRPC6 Inactivation Reduces Albuminuria Induced by Protein Overload in Sprague Dawley Rats. Cells 2022; 11:1985. [PMID: 35805070 PMCID: PMC9265922 DOI: 10.3390/cells11131985] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 06/06/2022] [Accepted: 06/17/2022] [Indexed: 12/02/2022] Open
Abstract
Canonical transient receptor potential-6 (TRPC6) channels have been implicated in familial and acquired forms of focal and segmental glomerulosclerosis (FSGS), and in renal fibrosis following ureteral obstruction in mice. TRPC6 channels also appear to play a role in driving glomerular disease in aging and in autoimmune glomerulonephritis. In the present study, we examine the role of TRPC6 in the proteinuric state caused by prolonged albumin overload (AO) in Sprague Dawley rats induced by daily injections of exogenous albumin. This was assessed in rats with a global and constitutive inactivation of TRPC6 channels (Trpc6del/del rats) and in wild-type littermates (Trpc6wt/wt rats). AO for 14 and 28 days caused increased urine albumin excretion that was significantly attenuated in Trpc6del/del rats compared to Trpc6wt/wt controls. AO overload did not induce significant glomerulosclerosis or azotemia in either genotype. AO induced mild tubulointerstitial disease characterized by fibrosis, hypercellularity and increased expression of markers of fibrosis and inflammation. Those changes were equally severe in Trpc6wt/wt and Trpc6del/del rats. Immunoblot analysis of renal cortex indicated that AO increased the abundances of TRPC3 and TRPC6, and caused a nearly complete loss of TRPC5 in Trpc6wt/wt rats. The increase in TRPC3 and the loss of TRPC5 occurred to the same extent in Trpc6del/del rats. These data also suggest that TRPC6 plays a role in the normal function of the glomerular filtration barrier. However, whether TRPC6 inactivation protects the tubulointerstitial compartments in Sprague Dawley rats depends on the disease model examined.
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Affiliation(s)
- Eun Young Kim
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA;
| | - Stuart E. Dryer
- Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA;
- Department of Biomedical Sciences, Tilman J. Fertitta Family College of Medicine, University of Houston, Houston, TX 77204, USA
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13
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Lee SB, Park B, Hong KW, Jung DH. Genome-Wide Association of New-Onset Hypertension According to Renin Concentration: The Korean Genome and Epidemiology Cohort Study. J Cardiovasc Dev Dis 2022; 9:jcdd9040104. [PMID: 35448080 PMCID: PMC9025963 DOI: 10.3390/jcdd9040104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/21/2022] [Accepted: 03/29/2022] [Indexed: 11/16/2022] Open
Abstract
The renin-angiotensin system (RAS) is a crucial regulator of vascular resistance and blood volume in the body. This study aimed to examine the genetic predisposition of the plasma renin concentration influencing future hypertension incidence. Based on the Korean Genome and Epidemiology Cohort dataset, 5211 normotensive individuals at enrollment were observed over 12 years, categorized into the low-renin and high-renin groups. We conducted genome-wide association studies for the total, low-renin, and high-renin groups. Among the significant SNPs, the lead SNPs of each locus were focused on for further interpretation. The effect of genotypes was determined by logistic regression analysis between controls and new-onset hypertension, after adjusting for potential confounding variables. During a mean follow-up period of 7.6 years, 1704 participants (32.7%) developed hypertension. The low-renin group showed more incidence rates of new-onset hypertension (35.3%) than the high-renin group (26.5%). Among 153 SNPs in renin-related gene regions, two SNPs (rs11726091 and rs8137145) showed an association in the high-renin group, four SNPs (rs17038966, rs145286444, rs2118663, and rs12336898) in the low-renin group, and three SNPs (rs1938859, rs7968218, and rs117246401) in the total population. Most significantly, the low-renin SNP rs12336898 in the SPTAN1 gene, closely related to vascular wall remodeling, was associated with the development of hypertension (p-value = 1.3 × 10−6). We found the candidate genetic polymorphisms according to blood renin concentration. Our results might be a valuable indicator for hypertension risk prediction and preventive measure, considering renin concentration with genetic susceptibility.
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Affiliation(s)
- Sung-Bum Lee
- Severance Check-up, Yonsei University Health System, Yongin-si 16995, Korea;
- Department of Medicine, Graduate School, Yonsei University Wonju College of Medicine, Wonju-si 26426, Korea
| | - Byoungjin Park
- Department of Family Medicine, Yongin Severance Hosptal, Yongin-si 16995, Korea;
| | - Kyung-Won Hong
- Healthcare R&D Division, Theragen Bio Co., Ltd., Ganggyo-ro 145, Suwon-si 16229, Korea
- Correspondence: (K.-W.H.); (D.-H.J.)
| | - Dong-Hyuk Jung
- Department of Family Medicine, Yongin Severance Hosptal, Yongin-si 16995, Korea;
- Department of Family Medicine, Yonsei University College of Medicine, Seoul 03722, Korea
- Correspondence: (K.-W.H.); (D.-H.J.)
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14
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Sachdeva S, Khan S, Davalos C, Avanthika C, Jhaveri S, Babu A, Patterson D, Yamani AJ. Management of Steroid-Resistant Nephrotic Syndrome in Children. Cureus 2021; 13:e19363. [PMID: 34925975 PMCID: PMC8654081 DOI: 10.7759/cureus.19363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/08/2021] [Indexed: 11/23/2022] Open
Abstract
Nephrotic syndrome (NS) affects 115-169 children per 100,000, with rates varying by ethnicity and location. Immune dysregulation, systemic circulating substances, or hereditary structural abnormalities of the podocyte are considered to have a role in the etiology of idiopathic NS. Following daily therapy with corticosteroids, more than 85% of children and adolescents (often aged 1 to 12 years) with idiopathic nephrotic syndrome have full proteinuria remission. Patients with steroid-resistant nephrotic syndrome (SRNS) do not demonstrate remission after four weeks of daily prednisolone therapy. The incidence of steroid-resistant nephrotic syndrome in children varies between 35 and 92 percent. A third of SRNS patients have mutations in one of the important podocyte genes. An unidentified circulating factor is most likely to blame for the remaining instances of SRNS. The aim of this article is to explore and review the genetic factors and management of steroid-resistant nephrotic syndrome. An all language literature search was conducted on MEDLINE, COCHRANE, EMBASE, and Google Scholar till September 2021. The following search strings and Medical Subject Headings (MeSH) terms were used: “Steroid resistance”, “nephrotic syndrome”, “nephrosis” and “hypoalbuminemia”. We comprehensively reviewed the literature on the epidemiology, genetics, current treatment protocols, and management of steroid-resistant nephrotic syndrome. We found that for individuals with non-genetic SRNS, calcineurin inhibitors (cyclosporine and tacrolimus) constitute the current mainstay of treatment, with around 70% of patients achieving full or partial remission and an acceptable long-term prognosis. Patients with SRNS who do not react to calcineurin inhibitors or other immunosuppressive medications may have deterioration in kidney function and may develop end-stage renal failure. Nonspecific renal protective medicines, such as angiotensin-converting enzyme inhibitors, angiotensin 2 receptor blockers, and anti-lipid medications, slow the course of the illness. Recurrent focal segmental glomerulosclerosis in the allograft affects around a third of individuals who get a kidney transplant, and it frequently responds to a combination of plasma exchange, rituximab, and increased immunosuppression. Despite the fact that these results show a considerable improvement in outcome, further multicenter controlled studies are required to determine the optimum drugs and regimens to be used.
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Affiliation(s)
| | - Syeda Khan
- Medicine and Surgery, Dow University of Health Sciences, Karachi, PAK
| | | | - Chaithanya Avanthika
- Medicine and Surgery, Karnataka Institute of Medical Sciences, Hubli, IND.,Pediatrics, Karnataka Institute of Medical Sciences, Hubli, IND
| | - Sharan Jhaveri
- Internal Medicine, Smt. NHL Municipal Medical College (MMC), Ahmedabad, IND
| | - Athira Babu
- Pediatrics, Saudi German Hospital, Dubai, ARE
| | | | - Abdullah J Yamani
- Pediatric Medicine, Coast General Teaching and Referral Hospital, Mombasa, KEN
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15
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Hunanyan L, Ghamaryan V, Makichyan A, Popugaeva E. Computer-Based Drug Design of Positive Modulators of Store-Operated Calcium Channels to Prevent Synaptic Dysfunction in Alzheimer's Disease. Int J Mol Sci 2021; 22:ijms222413618. [PMID: 34948414 PMCID: PMC8707499 DOI: 10.3390/ijms222413618] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/14/2021] [Accepted: 12/16/2021] [Indexed: 11/25/2022] Open
Abstract
Store-operated calcium entry (SOCE) constitutes a fine-tuning mechanism responsible for the replenishment of intracellular stores. Hippocampal SOCE is regulated by store-operated channels (SOC) organized in tripartite complex TRPC6/ORAI2/STIM2. It is suggested that in neurons, SOCE maintains intracellular homeostatic Ca2+ concentration at resting conditions and is needed to support the structure of dendritic spines. Recent evidence suggests that positive modulators of SOC are prospective drug candidates to treat Alzheimer’s disease (AD) at early stages. Although STIM2 and ORAI2 are definitely involved in the regulation of nSOC amplitude and a play major role in AD pathogenesis, growing evidence suggest that it is not easy to target these proteins pharmacologically. Existing positive modulators of TRPC6 are unsuitable for drug development due to either bad pharmacokinetics or side effects. Thus, we concentrate the review on perspectives to develop specific nSOC modulators based on available 3D structures of TRPC6, ORAI2, and STIM2. We shortly describe the structural features of existing models and the methods used to prepare them. We provide commonly used steps applied for drug design based on 3D structures of target proteins that might be used to develop novel AD preventing therapy.
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Affiliation(s)
- Lernik Hunanyan
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia;
- Laboratory of Structural Bioinformatics, Institute of Biomedicine and Pharmacy, Russian-Armenian University, Yerevan 0051, Armenia; (V.G.); (A.M.)
| | - Viktor Ghamaryan
- Laboratory of Structural Bioinformatics, Institute of Biomedicine and Pharmacy, Russian-Armenian University, Yerevan 0051, Armenia; (V.G.); (A.M.)
| | - Ani Makichyan
- Laboratory of Structural Bioinformatics, Institute of Biomedicine and Pharmacy, Russian-Armenian University, Yerevan 0051, Armenia; (V.G.); (A.M.)
| | - Elena Popugaeva
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia;
- Correspondence:
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16
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Liu Z, Zhang H, Zhao S, Zhang Q, Zhang R, Han Y, Shao L, Zhao X. Novel gain-of-function mutation of TRPC6 Q134P contributes to late onset focal segmental glomerulosclerosis in a Chinese pedigree. Nephrology (Carlton) 2021; 26:1018-1025. [PMID: 34387384 DOI: 10.1111/nep.13963] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 07/06/2021] [Accepted: 08/07/2021] [Indexed: 11/28/2022]
Abstract
BACKGROUND Focal segmental glomerulosclerosis (FSGS, OMIM®#603 965) is an overriding cause that leads to end-stage renal disease (ESRD). As a member of TRP superfamily, mutations of TRPC6 gene are closely linked to FSGS. By now, 20 missense mutations have been reported, among them, nine gain-of-function (GOF), and five loss-of-function (LOF) mutations have been recognized according to the effect on TRPC6 channel activity. Systematic investigations of functional mutations will provide valuable evidences for understanding the pathophysiology of TRPC6 involved in FSGS. The aim of this study is to investigate the pathogenicity of a novel TRPC6 mutation p.Q134P in FSGS. METHODS High-throughput sequencing was performed to analyse 436 genes which are associated with hereditary kidney diseases in a Chinese pedigree. Then we constructed TRPC6 expression plasmids of wide type and variant. Immunofluorescence, cell-surface biotinylation assays and electrophysiology were used to analyse the localization, cell surface expression, and calcium transport activity of TRPC6. RESULTS A novel variant c.401A>C (p.Q134P) in exon 2 of TRPC6 gene was found. There was no significant difference between the expression levels of p.Q134P mutant and WT TRPC6 protein in the whole cell lysate and cell-surface fraction. Q134P mutant-bearing TRPC6 elicited much higher Ca+ current amplitude than WT. CONCLUSION We identified a novel GOF mutation p.Q134P of TRPC6 which contributed to late-onset FSGS. Our study expands the mutational spectrum of TRPC6 associated with FSGS and furtherly supports the hypothesis of calcium dose-response dependency that a moderate increased calcium influx elicited a mild FSGS phenotype.
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Affiliation(s)
- Zhiying Liu
- Medical Research Center, The Affiliated Hospital of Qingdao University, Qingdao, China.,Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Haiyan Zhang
- Department of Gastroenterology, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Shipeng Zhao
- Department of Physiology, Qingdao University, Qingdao, China
| | - Qian Zhang
- Medical Research Center, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Ruixiao Zhang
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Yue Han
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Leping Shao
- Department of Nephrology, The Affiliated Qingdao Municipal Hospital of Qingdao University, Qingdao, China
| | - Xiangzhong Zhao
- Medical Research Center, The Affiliated Hospital of Qingdao University, Qingdao, China
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17
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Lee JM, Kronbichler A, Shin JI, Oh J. Current understandings in treating children with steroid-resistant nephrotic syndrome. Pediatr Nephrol 2021; 36:747-761. [PMID: 32086590 PMCID: PMC7910243 DOI: 10.1007/s00467-020-04476-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 12/22/2019] [Accepted: 01/07/2020] [Indexed: 12/27/2022]
Abstract
Steroid-resistant nephrotic syndrome (SRNS) remains a challenge for paediatric nephrologists. SRNS is viewed as a heterogeneous disease entity including immune-based and monogenic aetiologies. Because SRNS is rare, treatment strategies are individualized and vary among centres of expertise. Calcineurin inhibitors (CNI) have been effectively used to induce remission in patients with immune-based SRNS; however, there is still no consensus on treating children who become either CNI-dependent or CNI-resistant. Rituximab is a steroid-sparing agent for patients with steroid-sensitive nephrotic syndrome, but its efficacy in SRNS is controversial. Recently, several novel monoclonal antibodies are emerging as treatment option, but their efficacy remains to be seen. Non-immune therapies, such as angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers, have been proven efficacious in children with SRNS and are recommended as adjuvant agents. This review summarizes and discusses our current understandings in treating children with idiopathic SRNS.
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Affiliation(s)
- Jiwon M. Lee
- Department of Pediatrics, Chungnam National University Hospital, Daejeon, South Korea
| | - Andreas Kronbichler
- Department of Internal Medicine IV (Nephrology and Hypertension), Medical University Innsbruck, Innsbruck, Austria
| | - Jae Il Shin
- Department of Pediatrics, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, C.P.O. Box 8044, Seoul, 120-752 South Korea ,Division of Pediatric Nephrology, Severance Children’s Hospital, Seoul, South Korea ,Institute of Kidney Disease Research, Yonsei University College of Medicine, Seoul, South Korea
| | - Jun Oh
- Department of Pediatrics Nephrology, University Hamburg-Eppendorf, Martinistrasse, 52 20246, Hamburg, Germany.
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18
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Prikhodko V, Chernyuk D, Sysoev Y, Zernov N, Okovityi S, Popugaeva E. Potential Drug Candidates to Treat TRPC6 Channel Deficiencies in the Pathophysiology of Alzheimer's Disease and Brain Ischemia. Cells 2020; 9:cells9112351. [PMID: 33114455 PMCID: PMC7692306 DOI: 10.3390/cells9112351] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/28/2020] [Accepted: 10/20/2020] [Indexed: 12/16/2022] Open
Abstract
Alzheimer’s disease and cerebral ischemia are among the many causative neurodegenerative diseases that lead to disabilities in the middle-aged and elderly population. There are no effective disease-preventing therapies for these pathologies. Recent in vitro and in vivo studies have revealed the TRPC6 channel to be a promising molecular target for the development of neuroprotective agents. TRPC6 channel is a non-selective cation plasma membrane channel that is permeable to Ca2+. Its Ca2+-dependent pharmacological effect is associated with the stabilization and protection of excitatory synapses. Downregulation as well as upregulation of TRPC6 channel functions have been observed in Alzheimer’s disease and brain ischemia models. Thus, in order to protect neurons from Alzheimer’s disease and cerebral ischemia, proper TRPC6 channels modulators have to be used. TRPC6 channels modulators are an emerging research field. New chemical structures modulating the activity of TRPC6 channels are being currently discovered. The recent publication of the cryo-EM structure of TRPC6 channels should speed up the discovery process even more. This review summarizes the currently available information about potential drug candidates that may be used as basic structures to develop selective, highly potent TRPC6 channel modulators to treat neurodegenerative disorders, such as Alzheimer’s disease and cerebral ischemia.
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Affiliation(s)
- Veronika Prikhodko
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia; (V.P.); (D.C.); (Y.S.); (N.Z.)
- Department of Pharmacology and Clinical Pharmacology, Saint Petersburg State Chemical Pharmaceutical University, 197022 St. Petersburg, Russia;
- N.P. Bechtereva Institute of the Human Brain of the Russian Academy of Sciences, 197376 St. Petersburg, Russia
| | - Daria Chernyuk
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia; (V.P.); (D.C.); (Y.S.); (N.Z.)
| | - Yurii Sysoev
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia; (V.P.); (D.C.); (Y.S.); (N.Z.)
- Department of Pharmacology and Clinical Pharmacology, Saint Petersburg State Chemical Pharmaceutical University, 197022 St. Petersburg, Russia;
- N.P. Bechtereva Institute of the Human Brain of the Russian Academy of Sciences, 197376 St. Petersburg, Russia
- Institute of Translational Biomedicine, Saint Petersburg State University, 199034 St. Petersburg, Russia
| | - Nikita Zernov
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia; (V.P.); (D.C.); (Y.S.); (N.Z.)
| | - Sergey Okovityi
- Department of Pharmacology and Clinical Pharmacology, Saint Petersburg State Chemical Pharmaceutical University, 197022 St. Petersburg, Russia;
- N.P. Bechtereva Institute of the Human Brain of the Russian Academy of Sciences, 197376 St. Petersburg, Russia
| | - Elena Popugaeva
- Laboratory of Molecular Neurodegeneration, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia; (V.P.); (D.C.); (Y.S.); (N.Z.)
- Correspondence:
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Blaine J, Dylewski J. Regulation of the Actin Cytoskeleton in Podocytes. Cells 2020; 9:cells9071700. [PMID: 32708597 PMCID: PMC7408282 DOI: 10.3390/cells9071700] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 06/30/2020] [Accepted: 07/07/2020] [Indexed: 12/13/2022] Open
Abstract
Podocytes are an integral part of the glomerular filtration barrier, a structure that prevents filtration of large proteins and macromolecules into the urine. Podocyte function is dependent on actin cytoskeleton regulation within the foot processes, structures that link podocytes to the glomerular basement membrane. Actin cytoskeleton dynamics in podocyte foot processes are complex and regulated by multiple proteins and other factors. There are two key signal integration and structural hubs within foot processes that regulate the actin cytoskeleton: the slit diaphragm and focal adhesions. Both modulate actin filament extension as well as foot process mobility. No matter what the initial cause, the final common pathway of podocyte damage is dysregulation of the actin cytoskeleton leading to foot process retraction and proteinuria. Disruption of the actin cytoskeleton can be due to acquired causes or to genetic mutations in key actin regulatory and signaling proteins. Here, we describe the major structural and signaling components that regulate the actin cytoskeleton in podocytes as well as acquired and genetic causes of actin dysregulation.
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Affiliation(s)
- Judith Blaine
- Renal Division, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA;
| | - James Dylewski
- Renal Division, University of Colorado Anschutz Medical Campus and Denver Health Medical Center, Aurora, CO 80045, USA
- Correspondence: ; Tel.: +303-724-4841
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20
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Park E, Lee C, Kim NKD, Ahn YH, Park YS, Lee JH, Kim SH, Cho MH, Cho H, Yoo KH, Shin JI, Kang HG, Ha IS, Park WY, Cheong HI. Genetic Study in Korean Pediatric Patients with Steroid-Resistant Nephrotic Syndrome or Focal Segmental Glomerulosclerosis. J Clin Med 2020; 9:jcm9062013. [PMID: 32604935 PMCID: PMC7355646 DOI: 10.3390/jcm9062013] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 06/16/2020] [Accepted: 06/19/2020] [Indexed: 11/17/2022] Open
Abstract
Steroid-resistant nephrotic syndrome (SRNS) is one of the major causes of end-stage renal disease (ESRD) in childhood and is mostly associated with focal segmental glomerulosclerosis (FSGS). More than 50 monogenic causes of SRNS or FSGS have been identified. Recently, the mutation detection rate in pediatric patients with SRNS has been reported to be approximately 30%. In this study, genotype-phenotype correlations in a cohort of 291 Korean pediatric patients with SRNS/FSGS were analyzed. The overall mutation detection rate was 43.6% (127 of 291 patients). WT1 was the most common causative gene (23.6%), followed by COQ6 (8.7%), NPHS1 (8.7%), NUP107 (7.1%), and COQ8B (6.3%). Mutations in COQ6, NUP107, and COQ8B were more frequently detected, and mutations in NPHS2 were less commonly detected in this cohort than in study cohorts from Western countries. The mutation detection rate was higher in patients with congenital onset, those who presented with proteinuria or chronic kidney disease/ESRD, and those who did not receive steroid treatment. Genetic diagnosis in patients with SRNS provides not only definitive diagnosis but also valuable information for decisions on treatment policy and prediction of prognosis. Therefore, further genotype-phenotype correlation studies are required.
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Affiliation(s)
- Eujin Park
- Department of Pediatrics, Seoul National University College of Medicine, Seoul 03080, Korea; (E.P.); (Y.H.A.); (H.G.K.); (I.-S.H.)
- Department of Pediatrics, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul 07441, Korea
| | - Chung Lee
- Samsung Genome Institute, Samsung Medical Center, Seoul 06351, Korea; (C.L.); (N.K.D.K.); (W.-Y.P.)
- GENINUS Inc., Seoul 05836, Korea
| | - Nayoung K. D. Kim
- Samsung Genome Institute, Samsung Medical Center, Seoul 06351, Korea; (C.L.); (N.K.D.K.); (W.-Y.P.)
- GENINUS Inc., Seoul 05836, Korea
| | - Yo Han Ahn
- Department of Pediatrics, Seoul National University College of Medicine, Seoul 03080, Korea; (E.P.); (Y.H.A.); (H.G.K.); (I.-S.H.)
| | - Young Seo Park
- Department of Pediatrics, Asan Medical Center Children’s Hospital, University of Ulsan College of Medicine, Seoul 05505, Korea; (Y.S.P.); (J.H.L.)
| | - Joo Hoon Lee
- Department of Pediatrics, Asan Medical Center Children’s Hospital, University of Ulsan College of Medicine, Seoul 05505, Korea; (Y.S.P.); (J.H.L.)
| | - Seong Heon Kim
- Department of Pediatrics, Pusan National University Children’s Hospital, Yangsan 50612, Korea;
| | - Min Hyun Cho
- Department of Pediatrics, Kyungpook National University School of Medicine, Daegu 41944, Korea;
| | - Heeyeon Cho
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea;
| | - Kee Hwan Yoo
- Department of Pediatrics, Korea University Guro Hospital, Seoul 02841, Korea;
| | - Jae Il Shin
- Department of Pediatrics, Yonsei University College of Medicine, Seoul 03722, Korea;
- Division of Pediatric Nephrology, Severance Children’s Hospital, Seoul 03722, Korea
| | - Hee Gyung Kang
- Department of Pediatrics, Seoul National University College of Medicine, Seoul 03080, Korea; (E.P.); (Y.H.A.); (H.G.K.); (I.-S.H.)
| | - Il-Soo Ha
- Department of Pediatrics, Seoul National University College of Medicine, Seoul 03080, Korea; (E.P.); (Y.H.A.); (H.G.K.); (I.-S.H.)
| | - Woong-Yang Park
- Samsung Genome Institute, Samsung Medical Center, Seoul 06351, Korea; (C.L.); (N.K.D.K.); (W.-Y.P.)
- GENINUS Inc., Seoul 05836, Korea
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon 16419, Korea
| | - Hae Il Cheong
- Department of Pediatrics, Seoul National University College of Medicine, Seoul 03080, Korea; (E.P.); (Y.H.A.); (H.G.K.); (I.-S.H.)
- Correspondence: ; Tel.: +82-2-2072-2810
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21
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Post-Translational Modification and Natural Mutation of TRPC Channels. Cells 2020; 9:cells9010135. [PMID: 31936014 PMCID: PMC7016788 DOI: 10.3390/cells9010135] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Revised: 01/03/2020] [Accepted: 01/03/2020] [Indexed: 02/06/2023] Open
Abstract
Transient Receptor Potential Canonical (TRPC) channels are homologues of Drosophila TRP channel first cloned in mammalian cells. TRPC family consists of seven members which are nonselective cation channels with a high Ca2+ permeability and are activated by a wide spectrum of stimuli. These channels are ubiquitously expressed in different tissues and organs in mammals and exert a variety of physiological functions. Post-translational modifications (PTMs) including phosphorylation, N-glycosylation, disulfide bond formation, ubiquitination, S-nitrosylation, S-glutathionylation, and acetylation play important roles in the modulation of channel gating, subcellular trafficking, protein-protein interaction, recycling, and protein architecture. PTMs also contribute to the polymodal activation of TRPCs and their subtle regulation in diverse physiological contexts and in pathological situations. Owing to their roles in the motor coordination and regulation of kidney podocyte structure, mutations of TRPCs have been implicated in diseases like cerebellar ataxia (moonwalker mice) and focal and segmental glomerulosclerosis (FSGS). The aim of this review is to comprehensively integrate all reported PTMs of TRPCs, to discuss their physiological/pathophysiological roles if available, and to summarize diseases linked to the natural mutations of TRPCs.
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22
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Wang M, Wang R, He X, Yu M, Xia Z, Gao C. Two Children With Novel TRPC6 Spontaneous Missense Mutations and Atypical Phenotype: A Case Report and Literature Review. Front Pediatr 2020; 8:269. [PMID: 32509715 PMCID: PMC7249804 DOI: 10.3389/fped.2020.00269] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Accepted: 04/29/2020] [Indexed: 01/21/2023] Open
Abstract
Background: The phenotypes of TRPC6 mutations have been reported mainly in familial and sporadic focal segmental glomerulosclerosis (FSGS), which can occur in both adults and children. Herein, we report on two children with novel TRPC6 spontaneous missense mutations associated with immune complex-mediated glomerulonephritis and minor glomerular abnormality (MGA) that showed to be resistant to corticosteroids and other immunosuppressants. Case Presentation: A 9-year-old girl presented with steroid-resistant nephrotic syndrome (SRNS), while another 11-year-old boy developed proteinuria at 7 years old. Treatment with a variety of immunosuppressants had no effect, and the renal biopsy showed immune complex-mediated glomerulonephritis and MGA. No members of their family were clinically affected. Genetic testing was performed in the two patients, revealing two novel spontaneous missense mutations in TRPC6-N110S and P112R. The girl developed end-stage renal disease (ESRD) 5 months after onset while the boy continued to have sub-nephrotic range proteinuria and normal creatinine. Conclusions: Two novel TRPC6 mutations were associated with the atypical phenotype-immune complex-mediated glomerulonephritis and MGA, rather than FSGS as previously reported. Their rates of disease progression are different. Genetic testing is helpful to identify the etiology and avoid the side effects brought on by immunosuppressants.
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Affiliation(s)
- Meiqiu Wang
- Department of Pediatrics, Jinling Hospital, The First School of Clinical Medicine, Southern Medical University, Nanjing, China
| | - Ren Wang
- Department of Pediatrics, Jinling Hospital, Nanjing Medical University, Nanjing, China
| | - Xu He
- Department of Pediatrics, Jinling Hospital, Nanjing, China
| | - Min Yu
- Department of Pediatrics, Jinling Hospital, Nanjing Medical University, Nanjing, China.,Department of Neonatology, Taizhou People's Hospital, Taizhou, China
| | - Zhengkun Xia
- Department of Pediatrics, Jinling Hospital, Nanjing, China
| | - Chunlin Gao
- Department of Pediatrics, Jinling Hospital, Nanjing, China
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23
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Hall G, Wang L, Spurney RF. TRPC Channels in Proteinuric Kidney Diseases. Cells 2019; 9:cells9010044. [PMID: 31877991 PMCID: PMC7016871 DOI: 10.3390/cells9010044] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 12/18/2019] [Accepted: 12/19/2019] [Indexed: 12/20/2022] Open
Abstract
Over a decade ago, mutations in the gene encoding TRPC6 (transient receptor potential cation channel, subfamily C, member 6) were linked to development of familial forms of nephrosis. Since this discovery, TRPC6 has been implicated in the pathophysiology of non-genetic forms of kidney disease including focal segmental glomerulosclerosis (FSGS), diabetic nephropathy, immune-mediated kidney diseases, and renal fibrosis. On the basis of these findings, TRPC6 has become an important target for the development of therapeutic agents to treat diverse kidney diseases. Although TRPC6 has been a major focus for drug discovery, more recent studies suggest that other TRPC family members play a role in the pathogenesis of glomerular disease processes and chronic kidney disease (CKD). This review highlights the data implicating TRPC6 and other TRPC family members in both genetic and non-genetic forms of kidney disease, focusing on TRPC3, TRPC5, and TRPC6 in a cell type (glomerular podocytes) that plays a key role in proteinuric kidney diseases.
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24
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Fiedler S, Storch U, Erdogmus S, Gudermann T, Mederos Y Schnitzler M, Dietrich A. Small Fluorescein Arsenical Hairpin-Based Förster Resonance Energy Transfer Analysis Reveals Changes in Amino- to Carboxyl-Terminal Interactions upon OAG Activation of Classical Transient Receptor Potential 6. Mol Pharmacol 2019; 96:90-98. [PMID: 31171574 DOI: 10.1124/mol.119.115949] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 05/02/2019] [Indexed: 01/19/2023] Open
Abstract
Although the overall structure of many classical transient receptor potential proteins (TRPC), including human and murine TRPC6, were recently resolved by cryoelectron microscopy analysis, structural changes during channel activation by 1-oleoyl-1-acetyl-sn-glycerol (OAG), the membrane-permeable analog of diacylglycerol, were not defined. Moreover, data on carboxyl- and amino-terminal interactions were not provided, as the amino-terminal regions of murine and human TRPC6 were not resolved. Therefore, we employed a Förster resonance energy transfer (FRET) approach using a small fluorescein arsenical hairpin (FlAsH) targeted to a short tetracysteine sequence at the unresolved amino-terminus and cerulean, a cyan fluorescent protein, as a tag at the carboxyl-terminus of the murine TRPC6 protein. After OAG as well as GSK-1702934A activation, FRET efficiency was simultaneously and significantly reduced, indicating a decreased interaction between the amino to carboxyl termini in the functional tagged murine TRPC6 tetramer (TRPC6 WT) heterologously expressed in human embryonic kidney 293T cells. There was a significant reduction in the FRET signal obtained from analysis of murine TRPC6 FRET constructs with homologous amino-terminal mutations (M131T, G108S) that had been identified in human patients with inherited focal segmental glomerulosclerosis, a condition that can lead to end-stage renal disease. A novel, designed loss-of-function TRPC6 mutation (N109A) in the amino-terminus in close proximity to the carboxyl-terminus produced similar FRET ratios. SIGNIFICANCE STATEMENT: Our data show for the first time that FlAsH-tagging of ion channels is a promising tool to study conformational changes after channel opening and may significantly advance the analysis of ion channel activation as well as their mutants involved in channelopathies.
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Affiliation(s)
- Susanne Fiedler
- Walther-Straub-Institute of Pharmacology and Toxicology, Member of the German Center for Lung Research (DZL) (S.F., U.S., S.E., T.G., M.M.S., A.D.) and Institute for Cardiovascular Prevention (IPEK) (U.S.), Ludwig-Maximilians-Universitaet Muenchen, Munich, Germany; German Centre for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany (T.G., M.M.S.); and Comprehensive Pneumology Center Munich (CPC-M), Munich, Germany (T.G., A.D.)
| | - Ursula Storch
- Walther-Straub-Institute of Pharmacology and Toxicology, Member of the German Center for Lung Research (DZL) (S.F., U.S., S.E., T.G., M.M.S., A.D.) and Institute for Cardiovascular Prevention (IPEK) (U.S.), Ludwig-Maximilians-Universitaet Muenchen, Munich, Germany; German Centre for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany (T.G., M.M.S.); and Comprehensive Pneumology Center Munich (CPC-M), Munich, Germany (T.G., A.D.)
| | - Serap Erdogmus
- Walther-Straub-Institute of Pharmacology and Toxicology, Member of the German Center for Lung Research (DZL) (S.F., U.S., S.E., T.G., M.M.S., A.D.) and Institute for Cardiovascular Prevention (IPEK) (U.S.), Ludwig-Maximilians-Universitaet Muenchen, Munich, Germany; German Centre for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany (T.G., M.M.S.); and Comprehensive Pneumology Center Munich (CPC-M), Munich, Germany (T.G., A.D.)
| | - Thomas Gudermann
- Walther-Straub-Institute of Pharmacology and Toxicology, Member of the German Center for Lung Research (DZL) (S.F., U.S., S.E., T.G., M.M.S., A.D.) and Institute for Cardiovascular Prevention (IPEK) (U.S.), Ludwig-Maximilians-Universitaet Muenchen, Munich, Germany; German Centre for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany (T.G., M.M.S.); and Comprehensive Pneumology Center Munich (CPC-M), Munich, Germany (T.G., A.D.)
| | - Michael Mederos Y Schnitzler
- Walther-Straub-Institute of Pharmacology and Toxicology, Member of the German Center for Lung Research (DZL) (S.F., U.S., S.E., T.G., M.M.S., A.D.) and Institute for Cardiovascular Prevention (IPEK) (U.S.), Ludwig-Maximilians-Universitaet Muenchen, Munich, Germany; German Centre for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany (T.G., M.M.S.); and Comprehensive Pneumology Center Munich (CPC-M), Munich, Germany (T.G., A.D.)
| | - Alexander Dietrich
- Walther-Straub-Institute of Pharmacology and Toxicology, Member of the German Center for Lung Research (DZL) (S.F., U.S., S.E., T.G., M.M.S., A.D.) and Institute for Cardiovascular Prevention (IPEK) (U.S.), Ludwig-Maximilians-Universitaet Muenchen, Munich, Germany; German Centre for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany (T.G., M.M.S.); and Comprehensive Pneumology Center Munich (CPC-M), Munich, Germany (T.G., A.D.)
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25
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Farmer LK, Rollason R, Whitcomb DJ, Ni L, Goodliff A, Lay AC, Birnbaumer L, Heesom KJ, Xu SZ, Saleem MA, Welsh GI. TRPC6 Binds to and Activates Calpain, Independent of Its Channel Activity, and Regulates Podocyte Cytoskeleton, Cell Adhesion, and Motility. J Am Soc Nephrol 2019; 30:1910-1924. [PMID: 31416818 DOI: 10.1681/asn.2018070729] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 06/17/2019] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Mutations in the transient receptor potential channel 6 (TRPC6) gene are associated with an inherited form of FSGS. Despite widespread expression, patients with TRPC6 mutations do not present with any other pathologic phenotype, suggesting that this protein has a unique yet unidentified role within the target cell for FSGS, the kidney podocyte. METHODS We generated a stable TRPC6 knockout podocyte cell line from TRPC6 knockout mice. These cells were engineered to express wild-type TRPC6, a dominant negative TRPC6 mutation, or either of two disease-causing mutations of TRPC6, G109S or K874*. We extensively characterized these cells using motility, detachment, and calpain activity assays; immunofluorescence; confocal or total internal reflection fluorescence microscopy; and western blotting. RESULTS Compared with wild-type cells, TRPC6-/- podocytes are less motile and more adhesive, with an altered actin cytoskeleton. We found that TRPC6 binds to ERK1/2 and the actin regulatory proteins, caldesmon (a calmodulin- and actin-binding protein) and calpain 1 and 2 (calcium-dependent cysteine proteases that control the podocyte cytoskeleton, cell adhesion, and motility via cleavage of paxillin, focal adhesion kinase, and talin). Knockdown or expression of the truncated K874* mutation (but not expression of the gain-of-function G019S mutation or dominant negative mutant of TRPC6) results in the mislocalization of calpain 1 and 2 and significant downregulation of calpain activity; this leads to altered podocyte cytoskeleton, motility, and adhesion-characteristics of TRPC6 -/- podocytes. CONCLUSIONS Our data demonstrate that independent of TRPC6 channel activity, the physical interaction between TRPC6 and calpain in the podocyte is important for cell motility and detachment and demonstrates a scaffolding role of the TRPC6 protein in disease.
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Affiliation(s)
| | | | - Daniel J Whitcomb
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, Bristol Medical School, and
| | - Lan Ni
- Bristol Renal, Bristol Medical School
| | | | | | - Lutz Birnbaumer
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina.,Faculty of Medical Sciences, Institute of Biomedical Research, Catholic University of Argentina, Buenos Aires, Argentina; and
| | - Kate J Heesom
- Proteomics Facility, University of Bristol, Bristol, United Kingdom
| | - Shang-Zhong Xu
- Centre for Cardiovascular and Metabolic Research, Hull York Medical School, University of Hull, Hull, United Kingdom
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26
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Abstract
PURPOSE OF REVIEW The underlining goal of this review is to offer a concise, detailed look into current knowledge surrounding transient receptor potential canonical channel 6 (TRPC6) in the progression of diabetic kidney disease (DKD). RECENT FINDINGS Mutations and over-activation in TRPC6 channel activity lead to the development of glomeruli injury. Angiotensin II, reactive oxygen species, and other factors in the setting of DKD stimulate drastic increases in calcium influx through the TRPC6 channel, causing podocyte hypertrophy and foot process effacement. Loss of the podocytes further promote deterioration of the glomerular filtration barrier and play a major role in the development of both albuminuria and the renal injury in DKD. Recent genetic manipulation with TRPC6 channels in various rodent models provide additional knowledge about the role of TRPC6 in DKD and are reviewed here. The TRPC6 channel has a pronounced role in the progression of DKD, with deviations in activity yielding detrimental outcomes. The benefits of targeting TRPC6 or its upstream or downstream signaling pathways in DKD are prominent.
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Affiliation(s)
- Alexander Staruschenko
- Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, USA.
- Clement J. Zablocki VA Medical Center, Milwaukee, WI, 53295, USA.
| | - Denisha Spires
- Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, USA
| | - Oleg Palygin
- Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, USA
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27
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Dryer SE, Roshanravan H, Kim EY. TRPC channels: Regulation, dysregulation and contributions to chronic kidney disease. Biochim Biophys Acta Mol Basis Dis 2019; 1865:1041-1066. [PMID: 30953689 DOI: 10.1016/j.bbadis.2019.04.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 12/20/2018] [Accepted: 01/06/2019] [Indexed: 12/13/2022]
Abstract
Mutations in the gene encoding canonical transient receptor potential-6 (TRPC6) channels result in severe nephrotic syndromes that typically lead to end-stage renal disease. Many but not all of these mutations result in a gain in the function of the resulting channel protein. Since those observations were first made, substantial work has supported the hypothesis that TRPC6 channels can also contribute to progression of acquired (non-genetic) glomerular diseases, including primary and secondary FSGS, glomerulosclerosis during autoimmune glomerulonephritis, and possibly in type-1 diabetes. Their regulation has been extensively studied, especially in podocytes, but also in mesangial cells and other cell types present in the kidney. More recent evidence has implicated TRPC6 in renal fibrosis and tubulointerstitial disease caused by urinary obstruction. Consequently TRPC6 is being extensively investigated as a target for drug discovery. Other TRPC family members are present in kidney. TRPC6 can form a functional heteromultimer with TRPC3, and it has been suggested that TRPC5 may also play a role in glomerular disease progression, although the evidence on this is contradictory. Here we review literature on the expression and regulation of TRPC6, TRPC3 and TRPC5 in various cell types of the vertebrate kidney, the evidence that these channels are dysregulated in disease models, and research showing that knock-out or pharmacological inhibition of these channels can reduce the severity of kidney disease. We also summarize several areas that remain controversial, and some of the large gaps of knowledge concerning the fundamental role of these proteins in regulation of renal function.
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Affiliation(s)
- Stuart E Dryer
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA; Department of Internal Medicine, Division of Nephrology, Baylor College of Medicine, Houston, TX, USA.
| | - Hila Roshanravan
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA
| | - Eun Young Kim
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA
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28
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Genetic testing in steroid-resistant nephrotic syndrome: why, who, when and how? Pediatr Nephrol 2019; 34:195-210. [PMID: 29181713 PMCID: PMC6311200 DOI: 10.1007/s00467-017-3838-6] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 10/24/2017] [Accepted: 10/25/2017] [Indexed: 12/23/2022]
Abstract
Steroid-resistant nephrotic syndrome (SRNS) is a common cause of chronic kidney disease in childhood and has a significant risk of rapid progression to end-stage renal disease. The identification of over 50 monogenic causes of SRNS has revealed dysfunction in podocyte-associated proteins in the pathogenesis of proteinuria, highlighting their essential role in glomerular function. Recent technological advances in high-throughput sequencing have enabled indication-driven genetic panel testing for patients with SRNS. The availability of genetic testing, combined with the significant phenotypic variability of monogenic SRNS, poses unique challenges for clinicians when directing genetic testing. This highlights the need for clear clinical guidelines that provide a systematic approach for mutational screening in SRNS. The likelihood of identifying a causative mutation is inversely related to age at disease onset and is increased with a positive family history or the presence of extra-renal manifestations. An unequivocal molecular diagnosis could allow for a personalised treatment approach with weaning of immunosuppressive therapy, avoidance of renal biopsy and provision of accurate, well-informed genetic counselling. Identification of novel causative mutations will continue to unravel the pathogenic mechanisms of glomerular disease and provide new insights into podocyte biology and glomerular function.
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29
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Yu SMW, Nissaisorakarn P, Husain I, Jim B. Proteinuric Kidney Diseases: A Podocyte's Slit Diaphragm and Cytoskeleton Approach. Front Med (Lausanne) 2018; 5:221. [PMID: 30255020 PMCID: PMC6141722 DOI: 10.3389/fmed.2018.00221] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/18/2018] [Indexed: 01/19/2023] Open
Abstract
Proteinuric kidney diseases are a group of disorders with diverse pathological mechanisms associated with significant losses of protein in the urine. The glomerular filtration barrier (GFB), comprised of the three important layers, the fenestrated glomerular endothelium, the glomerular basement membrane (GBM), and the podocyte, dictates that disruption of any one of these structures should lead to proteinuric disease. Podocytes, in particular, have long been considered as the final gatekeeper of the GFB. This specialized visceral epithelial cell contains a complex framework of cytoskeletons forming foot processes and mediate important cell signaling to maintain podocyte health. In this review, we will focus on slit diaphragm proteins such as nephrin, podocin, TRPC6/5, as well as cytoskeletal proteins Rho/small GTPases and synaptopodin and their respective roles in participating in the pathogenesis of proteinuric kidney diseases. Furthermore, we will summarize the potential therapeutic options targeting the podocyte to treat this group of kidney diseases.
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Affiliation(s)
- Samuel Mon-Wei Yu
- Department of Medicine, Jacobi Medical Center, Bronx, NY, United States
| | | | - Irma Husain
- Department of Medicine, James J. Peters VA Medical Center, Bronx, NY, United States
| | - Belinda Jim
- Department of Medicine, Jacobi Medical Center, Bronx, NY, United States.,Renal Division, Jacobi Medical Center, Bronx, NY, United States
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30
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Sierra-Valdez F, Azumaya CM, Romero LO, Nakagawa T, Cordero-Morales JF. Structure-function analyses of the ion channel TRPC3 reveal that its cytoplasmic domain allosterically modulates channel gating. J Biol Chem 2018; 293:16102-16114. [PMID: 30139744 DOI: 10.1074/jbc.ra118.005066] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 08/17/2018] [Indexed: 12/14/2022] Open
Abstract
The transient receptor potential ion channels support Ca2+ permeation in many organs, including the heart, brain, and kidney. Genetic mutations in transient receptor potential cation channel subfamily C member 3 (TRPC3) are associated with neurodegenerative diseases, memory loss, and hypertension. To better understand the conformational changes that regulate TRPC3 function, we solved the cryo-EM structures for the full-length human TRPC3 and its cytoplasmic domain (CPD) in the apo state at 5.8- and 4.0-Å resolution, respectively. These structures revealed that the TRPC3 transmembrane domain resembles those of other TRP channels and that the CPD is a stable module involved in channel assembly and gating. We observed the presence of a C-terminal domain swap at the center of the CPD where horizontal helices (HHs) transition into a coiled-coil bundle. Comparison of TRPC3 structures revealed that the HHs can reside in two distinct positions. Electrophysiological analyses disclosed that shortening the length of the C-terminal loop connecting the HH with the TRP helices increases TRPC3 activity and that elongating the length of the loop has the opposite effect. Our findings indicate that the C-terminal loop affects channel gating by altering the allosteric coupling between the cytoplasmic and transmembrane domains. We propose that molecules that target the HH may represent a promising strategy for controlling TRPC3-associated neurological disorders and hypertension.
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Affiliation(s)
- Francisco Sierra-Valdez
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163 and
| | | | - Luis O Romero
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163 and
| | - Terunaga Nakagawa
- Department of Molecular Physiology and Biophysics, .,Center for Structural Biology, and.,Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Julio F Cordero-Morales
- From the Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163 and
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31
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Ramirez GA, Coletto LA, Sciorati C, Bozzolo EP, Manunta P, Rovere-Querini P, Manfredi AA. Ion Channels and Transporters in Inflammation: Special Focus on TRP Channels and TRPC6. Cells 2018; 7:E70. [PMID: 29973568 PMCID: PMC6070975 DOI: 10.3390/cells7070070] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2018] [Revised: 06/27/2018] [Accepted: 06/29/2018] [Indexed: 12/14/2022] Open
Abstract
Allergy and autoimmune diseases are characterised by a multifactorial pathogenic background. Several genes involved in the control of innate and adaptive immunity have been associated with diseases and variably combine with each other as well as with environmental factors and epigenetic processes to shape the characteristics of individual manifestations. Systemic or local perturbations in salt/water balance and in ion exchanges between the intra- and extracellular spaces or among tissues play a role. In this field, usually referred to as elementary immunology, novel evidence has been recently acquired on the role of members of the transient potential receptor (TRP) channel family in several cellular mechanisms of potential significance for the pathophysiology of the immune response. TRP canonical channel 6 (TRPC6) is emerging as a functional element for the control of calcium currents in immune-committed cells and target tissues. In fact, TRPC6 influences leukocytes’ tasks such as transendothelial migration, chemotaxis, phagocytosis and cytokine release. TRPC6 also modulates the sensitivity of immune cells to apoptosis and influences tissue susceptibility to ischemia-reperfusion injury and excitotoxicity. Here, we provide a view of the interactions between ion exchanges and inflammation with a focus on the pathogenesis of immune-mediated diseases and potential future therapeutic implications.
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Affiliation(s)
- Giuseppe A Ramirez
- Unit of Immunology, Rheumatology, Allergy and Rare Diseases, Università Vita-Salute San Raffaele, 20132 Milan, Italy.
- Unit of Immunology, Rheumatology, Allergy and Rare Diseases, IRCCS Ospedale San Raffaele, 20132 Milan, Italy.
- Division of Immunology, Transplantation and Infectious Immunity, IRCCS Ospedale San Raffaele, 20132 Milan, Italy.
| | - Lavinia A Coletto
- Unit of Immunology, Rheumatology, Allergy and Rare Diseases, Università Vita-Salute San Raffaele, 20132 Milan, Italy.
- Unit of Immunology, Rheumatology, Allergy and Rare Diseases, IRCCS Ospedale San Raffaele, 20132 Milan, Italy.
- Division of Immunology, Transplantation and Infectious Immunity, IRCCS Ospedale San Raffaele, 20132 Milan, Italy.
| | - Clara Sciorati
- Unit of Immunology, Rheumatology, Allergy and Rare Diseases, Università Vita-Salute San Raffaele, 20132 Milan, Italy.
- Division of Immunology, Transplantation and Infectious Immunity, IRCCS Ospedale San Raffaele, 20132 Milan, Italy.
| | - Enrica P Bozzolo
- Unit of Immunology, Rheumatology, Allergy and Rare Diseases, Università Vita-Salute San Raffaele, 20132 Milan, Italy.
- Unit of Immunology, Rheumatology, Allergy and Rare Diseases, IRCCS Ospedale San Raffaele, 20132 Milan, Italy.
| | - Paolo Manunta
- Unit of Immunology, Rheumatology, Allergy and Rare Diseases, Università Vita-Salute San Raffaele, 20132 Milan, Italy.
- Unit of Nephrology, IRCCS Ospedale San Raffaele, 20132 Milan, Italy.
| | - Patrizia Rovere-Querini
- Unit of Immunology, Rheumatology, Allergy and Rare Diseases, Università Vita-Salute San Raffaele, 20132 Milan, Italy.
- Unit of Immunology, Rheumatology, Allergy and Rare Diseases, IRCCS Ospedale San Raffaele, 20132 Milan, Italy.
- Division of Immunology, Transplantation and Infectious Immunity, IRCCS Ospedale San Raffaele, 20132 Milan, Italy.
| | - Angelo A Manfredi
- Unit of Immunology, Rheumatology, Allergy and Rare Diseases, Università Vita-Salute San Raffaele, 20132 Milan, Italy.
- Unit of Immunology, Rheumatology, Allergy and Rare Diseases, IRCCS Ospedale San Raffaele, 20132 Milan, Italy.
- Division of Immunology, Transplantation and Infectious Immunity, IRCCS Ospedale San Raffaele, 20132 Milan, Italy.
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32
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Azumaya CM, Sierra-Valdez F, Cordero-Morales JF, Nakagawa T. Cryo-EM structure of the cytoplasmic domain of murine transient receptor potential cation channel subfamily C member 6 (TRPC6). J Biol Chem 2018; 293:10381-10391. [PMID: 29752403 PMCID: PMC6028952 DOI: 10.1074/jbc.ra118.003183] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 05/08/2018] [Indexed: 01/08/2023] Open
Abstract
The kidney maintains the internal milieu by regulating the retention and excretion of proteins, ions, and small molecules. The glomerular podocyte forms the slit diaphragm of the ultrafiltration filter, whose damage leads to progressive kidney failure and focal segmental glomerulosclerosis (FSGS). The canonical transient receptor potential 6 (TRPC6) ion channel is expressed in the podocyte, and mutations in its cytoplasmic domain cause FSGS in humans. In vitro evaluation of disease-causing mutations in TRPC6 has revealed that these genetic alterations result in abnormal ion channel gating. However, the mechanism whereby the cytoplasmic domain modulates TRPC6 function is largely unknown. Here, we report a cryo-EM structure of the cytoplasmic domain of murine TRPC6 at 3.8 Å resolution. The cytoplasmic fold of TRPC6 is characterized by an inverted dome-like chamber pierced by four radial horizontal helices that converge into a vertical coiled-coil at the central axis. Unlike other TRP channels, TRPC6 displays a unique domain swap that occurs at the junction of the horizontal helices and coiled-coil. Multiple FSGS mutations converge at the buried interface between the vertical coiled-coil and the ankyrin repeats, which form the dome, suggesting these regions are critical for allosteric gating modulation. This functionally critical interface is a potential target for drug design. Importantly, dysfunction in other family members leads to learning deficits (TRPC1/4/5) and ataxia (TRPC3). Our data provide a structural framework for the mechanistic investigation of the TRPC family.
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Affiliation(s)
| | - Francisco Sierra-Valdez
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Julio F Cordero-Morales
- Department of Physiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163
| | - Terunaga Nakagawa
- From the Department of Molecular Physiology and Biophysics,
- Center for Structural Biology, and
- Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, Tennessee 37232 and
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33
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Lepori N, Zand L, Sethi S, Fernandez-Juarez G, Fervenza FC. Clinical and pathological phenotype of genetic causes of focal segmental glomerulosclerosis in adults. Clin Kidney J 2018; 11:179-190. [PMID: 29644057 PMCID: PMC5888331 DOI: 10.1093/ckj/sfx143] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Accepted: 11/17/2017] [Indexed: 02/07/2023] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is a histologic lesion resulting from a variety of pathogenic processes that cause injury to the podocytes. Recently, mutations in more than 50 genes expressed in podocyte or glomerular basement membrane were identified as causing genetic forms of FSGS, the majority of which are characterized by onset in childhood. The prevalence of adult-onset genetic FSGS is likely to be underestimated and its clinical and histological features have not been clearly described. A small number of studies of adult-onset genetic FSGS showed that there is heterogeneity in clinical and histological findings, with a presentation ranging from sub-nephrotic proteinuria to full nephrotic syndrome. A careful evaluation of adult-onset FSGS that do not have typical features of primary or secondary FSGS (familial cases, resistance to immunosuppression and absence of evident cause of secondary FSGS) should include a genetic evaluation. Indeed, recognizing genetic forms of adult-onset FSGS is of the utmost importance, given that this diagnosis will have major implications on treatment strategies, selecting of living-related kidney donor and renal transplantation success.
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Affiliation(s)
- Nicola Lepori
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
- Division of Nephrology and Dialysis, Azienda Ospedaliera G. Brotzu, Cagliari, Italy
| | - Ladan Zand
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | - Sanjeev Sethi
- Division of Anatomic Pathology, Mayo Clinic, Rochester, MN, USA
| | - Gema Fernandez-Juarez
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
- Nephrology Division, Hospital Universitario Fundacion Alcorcon, Madrid, Spain
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34
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Rogg M, Yasuda-Yamahara M, Abed A, Dinse P, Helmstädter M, Conzelmann AC, Frimmel J, Sellung D, Biniossek ML, Kretz O, Grahammer F, Schilling O, Huber TB, Schell C. The WD40-domain containing protein CORO2B is specifically enriched in glomerular podocytes and regulates the ventral actin cytoskeleton. Sci Rep 2017; 7:15910. [PMID: 29162887 PMCID: PMC5698439 DOI: 10.1038/s41598-017-15844-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 10/31/2017] [Indexed: 11/13/2022] Open
Abstract
Podocytes are highly specialized epithelial cells essentially required to establish and maintain the kidney filtration barrier. Due to their complex cellular architecture these cells rely on an elaborated cytoskeletal apparatus providing plasticity as well as adaptive adhesion properties to withstand significant physical filtration forces. However, our knowledge about podocyte specific components of the cytoskeletal machinery is still incomplete. Employing cross-analysis of various quantitative omics-data sets we identify the WD40-domain containing protein CORO2B as a podocyte enriched protein. Furthermore, we demonstrate the distinct localization pattern of CORO2B to the ventral actin cytoskeleton serving as a physical linkage module to cell-matrix adhesion sites. Analysis of a novel Coro2b knockout mouse revealed that CORO2B modulates stress response of podocytes in an experimental nephropathy model. Using quantitative focal adhesome proteomics we identify the recruitment of CFL1 via CORO2B to focal adhesions as an underlying mechanism. Thus, we describe CORO2B as a novel podocyte enriched protein influencing cytoskeletal plasticity and stress adaptation.
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Affiliation(s)
- M Rogg
- Department of Medicine IV, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - M Yasuda-Yamahara
- Department of Medicine IV, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Department of Medicine, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - A Abed
- Department of Medicine IV, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - P Dinse
- Department of Medicine IV, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - M Helmstädter
- Department of Medicine IV, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - A C Conzelmann
- Department of Medicine IV, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - J Frimmel
- Department of Medicine IV, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - D Sellung
- Department of Medicine IV, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - M L Biniossek
- Institute of Molecular Medicine and Cell Research, University of Freiburg, Freiburg, Germany
| | - O Kretz
- Department of Medicine IV, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Institute of Anatomy and Cell Biology, Dept. for Neuroanatomy, Medical Faculty, Albert-Ludwigs-University Freiburg, Freiburg, Germany.,III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - F Grahammer
- Department of Medicine IV, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - O Schilling
- Institute of Molecular Medicine and Cell Research, University of Freiburg, Freiburg, Germany.,BIOSS Center for Biological Signalling Studies and Center for Systems Biology (ZBSA), Albert-Ludwigs-University, Freiburg, Germany.,German Cancer Consortium (DKTK) and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - T B Huber
- Department of Medicine IV, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany. .,III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. .,BIOSS Center for Biological Signalling Studies and Center for Systems Biology (ZBSA), Albert-Ludwigs-University, Freiburg, Germany.
| | - C Schell
- Department of Medicine IV, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Institute for Surgical Pathology, Medical Center Freiburg, Freiburg, Germany.,Berta-Ottenstein Programme, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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35
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Li Y, Wang Y, He Q, Dang X, Cao Y, Wu X, Mo S, He X, Yi Z. Genetic mutational testing of Chinese children with familial hematuria with biopsy‑proven FSGS. Mol Med Rep 2017; 17:1513-1526. [PMID: 29138824 PMCID: PMC5780091 DOI: 10.3892/mmr.2017.8023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 08/31/2017] [Indexed: 12/27/2022] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is a pathological lesion rather than a disease, with a diverse etiology. FSGS may result from genetic and non‑genetic factors. FSGS is considered a podocyte disease due to the fact that in the majority of patients with proven‑FSGS, the lesion results from defects in the podocyte structure or function. However, FSGS does not result exclusively from podocyte‑associated genes, however also from other genes including collagen IV‑associated genes. Patients who carry the collagen type IVA3 chain (COL4A3) or COL4A4 mutations usually exhibit Alport Syndrome (AS), thin basement membrane neuropathy or familial hematuria (FH). Previous studies revealed that long‑time persistent microscopic hematuria may lead to FSGS. A case of a family is presented here where affected individuals exhibited FH with FSGS‑proven, or chronic kidney disease. Renal biopsies were unhelpful and failed to demonstrate glomerular or basement membrane defects consistent with an inherited glomerulopathy, and therefore a possible underlying genetic cause for a unifying diagnosis was pursued. Genomic DNA of the siblings affected by FH with biopsy‑proven FSGS was analyzed, and their father was screened for 18 gene mutations associated with FSGS [nephrin, podocin, CD2 associated protein, phospholipase C ε, actinin α 4, transient receptor potential cation channel subfamily C member 6, inverted formin, FH2 and WH2 domain containing, Wilms tumor 1, LIM homeobox transcription factor 1 β, laminin subunit β 2, laminin subunit β 3, galactosida α, integrin subunit β 4, scavenger receptor class B member 2, coenzyme Q2, decaprenyl diphosphate synthase subunit 2, mitochondrially encoded tRNA leucine 1 (UUA/G; TRNL1) and SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a like 1] using matrix‑assisted laser desorption/ionization time‑of‑flight mass spectrometry technology. Then whole exome sequencing (WES) was performed in the two probands to ascertain whether there were other known or unknown gene mutations that segregated with the disease. Using mass array technology, a TRNL1 missense homozygous mutation (m. 3290T>C) was identified in the probands diagnosed with FH and manifested as FSGS on biopsy. In addition, a COL4A4 missense mutation c. 4195A>T (p. M1399L) in heterozygous pattern was identified using WES. None of these variants were detected in their father. In the present study, a mutation in TRNL1 (m. 3290T>C) was identified, which was the first reported variant associated with FSGS. The COL4A4 (c. 4195A>T) may co‑segregate with FSGS. Screening for COL4A mutations in familial FSGS patients is suggested in the present study. Genetic investigations of families with similar clinical phenotypes should be a priority for nephrologists. The combination of mass array technology and WES may improve the detection rate of genetic mutation with a high level of accuracy.
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Affiliation(s)
- Yongzhen Li
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Ying Wang
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Qingnan He
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Xiqiang Dang
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Yan Cao
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Xiaochuan Wu
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Shuanghong Mo
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Xiaoxie He
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Zhuwen Yi
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
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36
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Application of next-generation sequencing technology to diagnosis and treatment of focal segmental glomerulosclerosis. Clin Exp Nephrol 2017; 22:491-500. [PMID: 28752288 PMCID: PMC5956018 DOI: 10.1007/s10157-017-1449-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 07/06/2017] [Indexed: 12/15/2022]
Abstract
A broad range of genetic and non-genetic factors can lead to kidney injury that manifests as focal segmental glomerulosclerosis (FSGS), which can be classified into primary (idiopathic) and secondary forms. Previous genetic approaches to familial or sporadic cases of FSGS or steroid-resistant nephrotic syndrome identified causal mutations in a subset of genes. Recently, next-generation sequencing (NGS) approaches are becoming a part of a standard assessment in medical genetics. Current knowledge of the comprehensive genomic information is changing the way we think about FSGS and draws attention not only to identification of novel causal genes, but also to potential roles for combinations of mutations in multiple genes, mutations with complex inheritance, and susceptibility genes with variable penetrance carrying relatively minor but significant effects. This review provides an update on recent advances in the genetic analysis of FSGS and highlights the potential as well as the new challenges of NGS for diagnosis and mechanism-based treatment of FSGS.
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37
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Ars E, Torra R. Rare diseases, rare presentations: recognizing atypical inherited kidney disease phenotypes in the age of genomics. Clin Kidney J 2017; 10:586-593. [PMID: 28980669 PMCID: PMC5622904 DOI: 10.1093/ckj/sfx051] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 05/03/2017] [Indexed: 12/11/2022] Open
Abstract
A significant percentage of adults (10%) and children (20%) on renal replacement therapy have an inherited kidney disease (IKD). The new genomic era, ushered in by the next generation sequencing techniques, has contributed to the identification of new genes and facilitated the genetic diagnosis of the highly heterogeneous IKDs. Consequently, it has also allowed the reclassification of diseases and has broadened the phenotypic spectrum of many classical IKDs. Various genetic, epigenetic and environmental factors may explain ‘atypical’ phenotypes. In this article, we examine different mechanisms that may contribute to phenotypic variability and also provide case examples that illustrate them. The aim of the article is to raise awareness, among nephrologists and geneticists, of rare presentations that IKDs may show, to facilitate diagnosis.
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Affiliation(s)
- Elisabet Ars
- Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Spain
| | - Roser Torra
- Inherited Kidney Disorders, Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Spain
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38
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Li W, Ding Y, Smedley C, Wang Y, Chaudhari S, Birnbaumer L, Ma R. Increased glomerular filtration rate and impaired contractile function of mesangial cells in TRPC6 knockout mice. Sci Rep 2017. [PMID: 28646178 PMCID: PMC5482875 DOI: 10.1038/s41598-017-04067-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The present study was conducted to determine if TRPC6 regulates glomerular filtration rate (GFR) and the contractile function of glomerular mesangial cells (MCs). GFR was assessed in conscious TRPC6 wild type and knockout mice, and in anesthetized rats with and without in vivo knockdown of TRPC6 in kidneys. We found that GFR was significantly greater, and serum creatinine level was significantly lower in TRPC6 deficient mice. Consistently, local knockdown of TRPC6 in kidney using TRPC6 specific shRNA construct significantly attenuated Ang II-induced GFR decline in rats. Furthermore, Ang II-stimulated contraction and Ca2+ entry were significantly suppressed in primary MCs isolated from TRPC6 deficient mice, and the Ca2+ response could be rescued by re-introducing TRPC6. Moreover, inhibition of reverse mode of Na+-Ca2+ exchange by KB-R7943 significantly reduced Ca2+ entry response in TRPC6-expressing, but not in TRPC6-knocked down MCs. Ca2+ entry response was also significantly attenuated in Na+ free solution. Single knockdown of TRPC6 and TRPC1 resulted in a comparable suppression on Ca2+ entry with double knockdown of both. These results suggest that TRPC6 may regulate GFR by modulating MC contractile function through multiple Ca2+ signaling pathways.
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Affiliation(s)
- Weizu Li
- Department of Pharmacology, Anhui Medical University, Hefei, Anhui, 230032, P. R. China
| | - Yanfeng Ding
- Institute for Cardiovascular and Metabolic Disease, University of North Texas Health Science Center, Fort Worth, Texas, 76107, USA
| | - Crystal Smedley
- Institute for Cardiovascular and Metabolic Disease, University of North Texas Health Science Center, Fort Worth, Texas, 76107, USA
| | - Yanxia Wang
- Institute for Cardiovascular and Metabolic Disease, University of North Texas Health Science Center, Fort Worth, Texas, 76107, USA
| | - Sarika Chaudhari
- Institute for Cardiovascular and Metabolic Disease, University of North Texas Health Science Center, Fort Worth, Texas, 76107, USA
| | - Lutz Birnbaumer
- Transmembrane Signaling Group, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina, 27709, USA
| | - Rong Ma
- Institute for Cardiovascular and Metabolic Disease, University of North Texas Health Science Center, Fort Worth, Texas, 76107, USA.
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39
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Boyer O, Dorval G, Servais A. Hereditary Podocytopathies in Adults: The Next Generation. KIDNEY DISEASES 2017; 3:50-56. [PMID: 28868292 DOI: 10.1159/000477243] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 04/28/2017] [Indexed: 01/15/2023]
Abstract
Idiopathic nephrotic syndrome may have two underlying mechanisms: either (1) an alteration of the immune system resulting in the production of a putative circulating factor of glomerular permeability; or (2) mutations in the structural genes of the glomerular filtration barrier in which case patients are typically multidrug resistant and do not recur after transplantation. The latter forms have been recently recognized as "hereditary podocytopathies." In the past few years, positional cloning approaches that allow the identification of gene mutations underlying diseases whose pathophysiology is unknown and animal models have helped decipher the pathophysiological mechanisms of the glomerular filtration process. Recently, the advent of next-generation sequencing (NGS) techniques has greatly facilitated the identification of numerous novel causative genes in hereditary podocytopathies. Moreover, it has revealed mutations in unexpected genes and has widened the phenotypes associated with podocyte gene mutations. The list of genes mutated in hereditary podocytopathies is constantly evolving and consists to date of more than 40 genes. However, the most recently identified genes are extremely rarely mutated and may concern only a couple of families worldwide. These discoveries provided crucial insight into the pathophysiological mechanisms linking podocyte proteins to kidney function. This review will focus on monogenic podocytopathies affecting adult patients.
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Affiliation(s)
- Olivia Boyer
- Néphrologie pédiatrique, Centre de référence MARHEA, Hôpital Necker - Enfants Malades, APHP, Paris, France.,Inserm U1163, Institut Imagine, Université Paris-Descartes Sorbonne Paris Cité, Paris, France
| | - Guillaume Dorval
- Néphrologie pédiatrique, Centre de référence MARHEA, Hôpital Necker - Enfants Malades, APHP, Paris, France.,Inserm U1163, Institut Imagine, Université Paris-Descartes Sorbonne Paris Cité, Paris, France
| | - Aude Servais
- Néphrologie, Centre de référence MARHEA, Hôpital Necker - Enfants Malades, APHP, Paris, France.,Inserm U1163, Institut Imagine, Université Paris-Descartes Sorbonne Paris Cité, Paris, France
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40
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Markó L, Mannaa M, Haschler TN, Krämer S, Gollasch M. Renoprotection: focus on TRPV1, TRPV4, TRPC6 and TRPM2. Acta Physiol (Oxf) 2017; 219:589-612. [PMID: 28028935 DOI: 10.1111/apha.12828] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Revised: 04/22/2016] [Accepted: 10/31/2016] [Indexed: 01/09/2023]
Abstract
Members of the transient receptor potential (TRP) cation channel receptor family have unique sites of regulatory function in the kidney which enables them to promote regional vasodilatation and controlled Ca2+ influx into podocytes and tubular cells. Activated TRP vanilloid 1 receptor channels (TRPV1) have been found to elicit renoprotection in rodent models of acute kidney injury following ischaemia/reperfusion. Transient receptor potential cation channel, subfamily C, member 6 (TRPC6) in podocytes is involved in chronic proteinuric kidney disease, particularly in focal segmental glomerulosclerosis (FSGS). TRP vanilloid 4 receptor channels (TRPV4) are highly expressed in the kidney, where they induce Ca2+ influx into endothelial and tubular cells. TRP melastatin (TRPM2) non-selective cation channels are expressed in the cytoplasm and intracellular organelles, where their inhibition ameliorates ischaemic renal pathology. Although some of their basic properties have been recently identified, the renovascular role of TRPV1, TRPV4, TRPC6 and TRPM2 channels in disease states such as obesity, hypertension and diabetes is largely unknown. In this review, we discuss recent evidence for TRPV1, TRPV4, TRPC6 and TRPM2 serving as potential targets for acute and chronic renoprotection in chronic vascular and metabolic disease.
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Affiliation(s)
- L. Markó
- Experimental and Clinical Research Center; A Joint Cooperation Between the Charité Medical Faculty and the Max-Delbrück Center (MDC) for Molecular Medicine; Berlin Germany
| | - M. Mannaa
- Experimental and Clinical Research Center; A Joint Cooperation Between the Charité Medical Faculty and the Max-Delbrück Center (MDC) for Molecular Medicine; Berlin Germany
- Charité Campus Virchow; Nephrology/Intensive Care; Berlin Germany
- German Institute of Human Nutrition; Potsdam-Rehbrücke Germany
| | - T. N. Haschler
- Experimental and Clinical Research Center; A Joint Cooperation Between the Charité Medical Faculty and the Max-Delbrück Center (MDC) for Molecular Medicine; Berlin Germany
- German Institute of Human Nutrition; Potsdam-Rehbrücke Germany
| | - S. Krämer
- German Institute of Human Nutrition; Potsdam-Rehbrücke Germany
| | - M. Gollasch
- Experimental and Clinical Research Center; A Joint Cooperation Between the Charité Medical Faculty and the Max-Delbrück Center (MDC) for Molecular Medicine; Berlin Germany
- Charité Campus Virchow; Nephrology/Intensive Care; Berlin Germany
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41
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Ma R, Chaudhari S, Li W. Canonical Transient Receptor Potential 6 Channel: A New Target of Reactive Oxygen Species in Renal Physiology and Pathology. Antioxid Redox Signal 2016; 25:732-748. [PMID: 26937558 PMCID: PMC5079416 DOI: 10.1089/ars.2016.6661] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 02/06/2016] [Indexed: 02/07/2023]
Abstract
SIGNIFICANCE Regulation of Ca2+ signaling cascade by reactive oxygen species (ROS) is becoming increasingly evident and this regulation represents a key mechanism for control of many fundamental cellular functions. Canonical transient receptor potential (TRPC) 6, a member of Ca2+-conductive channel in the TRPC family, is widely expressed in kidney cells, including glomerular mesangial cells, podocytes, tubular epithelial cells, and vascular myocytes in renal microvasculature. Both overproduction of ROS and dysfunction of TRPC6 channel are involved in renal injury in animal models and human subjects. Although regulation of TRPC channel function by ROS has been well described in other tissues and cell types, such as vascular smooth muscle, this important cell regulatory mechanism has not been fully reviewed in kidney cells. Recent Advances: Accumulating evidence has shown that TRPC6 is a redox-sensitive channel, and modulation of TRPC6 Ca2+ signaling by altering TRPC6 protein expression or TRPC6 channel activity in kidney cells is a downstream mechanism by which ROS induce renal damage. CRITICAL ISSUES This review highlights how recent studies analyzing function and expression of TRPC6 channels in the kidney and their response to ROS improve our mechanistic understanding of oxidative stress-related kidney diseases. FUTURE DIRECTIONS Although it is evident that ROS regulate TRPC6-mediated Ca2+ signaling in several types of kidney cells, further study is needed to identify the underlying molecular mechanism. We hope that the newly identified ROS/TRPC6 pathway will pave the way to new, promising therapeutic strategies to target kidney diseases such as diabetic nephropathy. Antioxid. Redox Signal. 25, 732-748.
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Affiliation(s)
- Rong Ma
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, Texas
| | - Sarika Chaudhari
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, Texas
| | - Weizu Li
- Department of Pharmacology, Anhui Medical University, Hefei, People's Republic of China
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42
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Riehle M, Büscher AK, Gohlke BO, Kaßmann M, Kolatsi-Joannou M, Bräsen JH, Nagel M, Becker JU, Winyard P, Hoyer PF, Preissner R, Krautwurst D, Gollasch M, Weber S, Harteneck C. TRPC6 G757D Loss-of-Function Mutation Associates with FSGS. J Am Soc Nephrol 2016; 27:2771-83. [PMID: 26892346 PMCID: PMC5004639 DOI: 10.1681/asn.2015030318] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 01/06/2016] [Indexed: 01/15/2023] Open
Abstract
FSGS is a CKD with heavy proteinuria that eventually progresses to ESRD. Hereditary forms of FSGS have been linked to mutations in the transient receptor potential cation channel, subfamily C, member 6 (TRPC6) gene encoding a nonselective cation channel. Most of these TRPC6 mutations cause a gain-of-function phenotype, leading to calcium-triggered podocyte cell death, but the underlying molecular mechanisms are unclear. We studied the molecular effect of disease-related mutations using tridimensional in silico modeling of tetrameric TRPC6. Our results indicated that G757 is localized in a domain forming a TRPC6-TRPC6 interface and predicted that the amino acid exchange G757D causes local steric hindrance and disruption of the channel complex. Notably, functional characterization of model interface domain mutants suggested a loss-of-function phenotype. We then characterized 19 human FSGS-related TRPC6 mutations, the majority of which caused gain-of-function mutations. However, five mutations (N125S, L395A, G757D, L780P, and R895L) caused a loss-of-function phenotype. Coexpression of wild-type TRPC6 and TRPC6 G757D, mimicking heterozygosity observed in patients, revealed a dominant negative effect of TRPC6 G757D. Our comprehensive analysis of human disease-causing TRPC6 mutations reveals loss of TRPC6 function as an additional concept of hereditary FSGS and provides molecular insights into the mechanism responsible for the loss-of-function phenotype of TRPC6 G757D in humans.
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Affiliation(s)
- Marc Riehle
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany
| | - Anja K Büscher
- Pediatric Nephrology, Pediatrics II, University of Duisburg-Essen, Essen, Germany
| | - Björn-Oliver Gohlke
- German Cancer Consortium, Heidelberg, Germany; Charité University Medicine Berlin, Structural Bioinformatics Group, Institute of Physiology and Experimental Clinical Research Center, Berlin, Germany
| | - Mario Kaßmann
- Nephrology/Intensive Care, Experimental and Clinical Research Center and Max Delbrück Center for Molecular Medicine, Charité University Medicine Berlin, Berlin, Germany
| | - Maria Kolatsi-Joannou
- Nephro-Urology Unit, University College London Institute of Child Health, London, United Kingdom
| | - Jan H Bräsen
- Institute of Pathology, University Hospital of Hannover, Hannover, Germany
| | - Mato Nagel
- Center of Nephrology and Metabolism, Weisswasser, Germany
| | - Jan U Becker
- Institute of Pathology, University Hospital of Cologne, Cologne, Germany; and
| | - Paul Winyard
- Nephro-Urology Unit, University College London Institute of Child Health, London, United Kingdom
| | - Peter F Hoyer
- Pediatric Nephrology, Pediatrics II, University of Duisburg-Essen, Essen, Germany
| | - Robert Preissner
- German Cancer Consortium, Heidelberg, Germany; Charité University Medicine Berlin, Structural Bioinformatics Group, Institute of Physiology and Experimental Clinical Research Center, Berlin, Germany
| | - Dietmar Krautwurst
- Deutsche Forschungsanstalt für Lebensmittelchemie, Molekulare Zellphysiologie und Chemorezeption, Freising, Germany
| | - Maik Gollasch
- Nephrology/Intensive Care, Experimental and Clinical Research Center and Max Delbrück Center for Molecular Medicine, Charité University Medicine Berlin, Berlin, Germany
| | - Stefanie Weber
- Pediatric Nephrology, Pediatrics II, University of Duisburg-Essen, Essen, Germany;
| | - Christian Harteneck
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany;
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43
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Bouron A, Chauvet S, Dryer S, Rosado JA. Second Messenger-Operated Calcium Entry Through TRPC6. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 898:201-49. [PMID: 27161231 DOI: 10.1007/978-3-319-26974-0_10] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Canonical transient receptor potential 6 (TRPC6) proteins assemble into heteromultimeric structures forming non-selective cation channels. In addition, many TRPC6-interacting proteins have been identified like some enzymes, channels, pumps, cytoskeleton-associated proteins, immunophilins, or cholesterol-binding proteins, indicating that TRPC6 are engaged into macromolecular complexes. Depending on the cell type and the experimental conditions used, TRPC6 activity has been reported to be controlled by diverse modalities. For instance, the second messenger diacylglycerol, store-depletion, the plant extract hyperforin or H2O2 have all been shown to trigger the opening of TRPC6 channels. A well-characterized consequence of TRPC6 activation is the elevation of the cytosolic concentration of Ca(2+). This latter response can reflect the entry of Ca(2+) through open TRPC6 channels but it can also be due to the Na(+)/Ca(2+) exchanger (operating in its reverse mode) or voltage-gated Ca(2+) channels (recruited in response to a TRPC6-mediated depolarization). Although TRPC6 controls a diverse array of biological functions in many tissues and cell types, its pathophysiological functions are far from being fully understood. This chapter covers some key features of TRPC6, with a special emphasis on their biological significance in kidney and blood cells.
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Affiliation(s)
- Alexandre Bouron
- Université Grenoble Alpes, 38000, Grenoble, France. .,CNRS, iRTSV-LCBM, 38000, Grenoble, France.
| | - Sylvain Chauvet
- Université Grenoble Alpes, 38000, Grenoble, France.,CNRS, iRTSV-LCBM, 38000, Grenoble, France
| | - Stuart Dryer
- University of Houston, Houston, TX, USA.,Baylor College of Medicine, Houston, TX, USA
| | - Juan A Rosado
- Departamento de Fisiología, University of Extremadura, Cáceres, Spain
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Sun ZJ, Ng KH, Liao P, Zhang Y, Ng JL, Liu ID, Tan PH, Chong SSC, Chan YH, Liu J, Davila S, Heng CK, Jordan SC, Soong TW, Yap HK. Genetic Interactions Between TRPC6 and NPHS1 Variants Affect Posttransplant Risk of Recurrent Focal Segmental Glomerulosclerosis. Am J Transplant 2015; 15:3229-38. [PMID: 26147534 DOI: 10.1111/ajt.13378] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 04/20/2015] [Accepted: 05/05/2015] [Indexed: 01/25/2023]
Abstract
Individuals with TRPC6 mutations have variable phenotypes, ranging from healthy carrier to focal segmental glomerulosclerosis (FSGS) leading to renal failure. Here, we describe a family where six members had a novel TRPC6 p.R68W (c.202C>T) mutation, two of whom had renal failure from FSGS, and one had proteinuria. One healthy carrier donated a kidney to her sister. Both donor and recipient had no proteinuria at 20 years posttransplant. Two synonymous NPHS1 polymorphisms, rs2285450 (c.294C>T) and rs437168 (c.2289C>T) segregated with renal failure in this family. These variants had higher allele frequencies in 97 unrelated patients with nephrotic syndrome or FSGS compared to 224 controls. Using patch-clamp experiments in HEK293 and podocytes, we showed that the p.R68W mutation increased TRPC6 current amplitudes, which may be explained by enhanced TRPC6 surface expression. Additionally, while wild-type nephrin suppressed TRPC6 currents, this ability was lost in the presence of NPHS1 c.294C>T polymorphism. When cells were transfected according to combined TRPC6 and NPHS1 genotypes in the family, those representing the donor had lower TRPC6 currents than cells representing the recipient, suggesting that interactions between TRPC6 and NPHS1 variants could possibly account for the variable penetrance of TRPC6 mutations and the absence of recurrence in the graft.
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Affiliation(s)
- Z J Sun
- Department of Pediatrics, National University of Singapore, Singapore, Singapore
| | - K H Ng
- Department of Pediatrics, National University of Singapore, Singapore, Singapore.,Khoo Teck Puat - National University Children's Medical Institute, National University Health System, Singapore, Singapore
| | - P Liao
- Department of Research, National Neuroscience Institute, Singapore, Singapore.,Department of Physiology, National University of Singapore, Singapore, Singapore
| | - Y Zhang
- Department of Pediatrics, National University of Singapore, Singapore, Singapore
| | - J L Ng
- Khoo Teck Puat - National University Children's Medical Institute, National University Health System, Singapore, Singapore.,Department of Pediatrics, National University of Singapore, Singapore, Singapore
| | - I D Liu
- Khoo Teck Puat - National University Children's Medical Institute, National University Health System, Singapore, Singapore
| | - P H Tan
- Department of Pathology, Singapore General Hospital, Singapore, Singapore
| | - S S C Chong
- Department of Pediatrics, National University of Singapore, Singapore, Singapore
| | - Y H Chan
- Biostatistics Unit, National University of Singapore, Singapore, Singapore
| | - J Liu
- Human Genetics, Genome Institute of Singapore, Singapore, Singapore
| | - S Davila
- Human Genetics, Genome Institute of Singapore, Singapore, Singapore
| | - C K Heng
- Khoo Teck Puat - National University Children's Medical Institute, National University Health System, Singapore, Singapore.,Department of Pediatrics, National University of Singapore, Singapore, Singapore
| | - S C Jordan
- David Geffen School of Medicine at UCLA, Los Angeles, CA.,Cedars-Sinai Medical Center, Los Angeles, CA
| | - T W Soong
- Department of Physiology, National University of Singapore, Singapore, Singapore
| | - H K Yap
- Khoo Teck Puat - National University Children's Medical Institute, National University Health System, Singapore, Singapore.,Department of Pediatrics, National University of Singapore, Singapore, Singapore
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45
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Ng KH, Heng CK, Khor CC, Yap HK. Genes in FSGS: Diagnostic and Management Strategies in Children. CURRENT PEDIATRICS REPORTS 2015. [DOI: 10.1007/s40124-014-0064-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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46
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Canales CP, Krall P, Kairath P, Perez IC, Fragoso MA, Carmona-Mora P, Ruiz P, Reiser J, Young JI, Walz K. Characterization of a Trpc6 Transgenic Mouse Associated with Early Onset FSGS. ACTA ACUST UNITED AC 2015; 5:1198-2012. [PMID: 34012910 PMCID: PMC8130885 DOI: 10.9734/bjmmr/2015/12493] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Rationale: Mutations in Transient Receptor Potential Channel 6 (TRPC6) gene are associated with autosomal dominant focal and segmental glomerulosclerosis (FSGS). The majority of the identified mutations affect the ion channel function. Since calcium channels are promising candidate drug targets, there is an an urgent need for a mouse model to assess new therapeutic drugs and to help delineate the pathogenic process leading to FSGS. We have previously reported the generation of three independent transgenic mouse lines carrying different Trpc6 mutations that display a glomerular disease comparable to the phenotype presented by individuals with FSGS. However, the utility of these models for drug testing is dampened by the late-onset of the presentation and the mild phenotypic manifestations. Methodology: In order to obtain a time-effective mouse model for Trpc6-associated FSGS we generated a new transgenic mutant Trpc6 mouse model emulating the amino acid change carried by the first pediatric patient of FSGS associated with a TRPC6 mutation: M132T. Results: Mice carrying the orthologous Trpc6 M131T transgene showed early onset proteinuria and early signs of FSGS. When exploring molecular consequences of the overexpression of this mutated form of Trpc6 in podocytes, differences in expression levels of Axin2 and β-catenin were found in glomeruli from transgenic Trpc6 M131T mice. These data supports the proposed molecular mechanisms related to the activation of calcineurin-NFAT/Wnt signaling, as outcome of the increased calcium influx caused by the mutated form of Trpc6. Conclusion: Given that the Trpc6 M131T mouse develops an early onset of FSGS-like phenotypes it represents a promising model for studying the pathogenesis of FSGS caused by TRpC6, facilitating the assessment of new drugs as treatments and allowing further studies to understand underlying molecular pathways involved in the development of the TRPC6 mediated disease.
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Affiliation(s)
- Cesar P Canales
- John P. Hussman Institute for Human Genomics, University of Miami Leonard Miller School of Medicine, Miami, Florida, USA.,Cellular and Genetic Medicine Unit, School of Medical Sciences, UNSW, Sydney, Australia
| | - Paola Krall
- Nephrology Unit, Faculty of Medicine, Universidad Austral de Chile, Valdivia, Chile
| | - Pamela Kairath
- School of Biochemistry, Faculty of Sciences, Universidad Austral de Chile, Valdivia, Chile
| | - Irene C Perez
- John P. Hussman Institute for Human Genomics, University of Miami Leonard Miller School of Medicine, Miami, Florida, USA
| | - Miryam A Fragoso
- John P. Hussman Institute for Human Genomics, University of Miami Leonard Miller School of Medicine, Miami, Florida, USA
| | - Paulina Carmona-Mora
- John P. Hussman Institute for Human Genomics, University of Miami Leonard Miller School of Medicine, Miami, Florida, USA.,Cellular and Genetic Medicine Unit, School of Medical Sciences, UNSW, Sydney, Australia
| | - Phillip Ruiz
- Department of Surgery and Pathology, University of Miami Leonard Miller School of Medicine, Miami, Florida, USA.,Division of Nephrology and Hypertension, University of Miami Leonard Miller School of Medicine, Miami, Florida, USA
| | - Jochen Reiser
- Department of Internal Medicine, Rush University, Chicago, USA
| | - Juan I Young
- John P. Hussman Institute for Human Genomics, University of Miami Leonard Miller School of Medicine, Miami, Florida, USA.,Department of Human Genetics, University of Miami Leonard Miller School of Medicine, Miami, Florida, USA
| | - Katherina Walz
- John P. Hussman Institute for Human Genomics, University of Miami Leonard Miller School of Medicine, Miami, Florida, USA.,Division of Nephrology and Hypertension, University of Miami Leonard Miller School of Medicine, Miami, Florida, USA.,Department of Human Genetics, University of Miami Leonard Miller School of Medicine, Miami, Florida, USA
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47
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Bullich G, Trujillano D, Santín S, Ossowski S, Mendizábal S, Fraga G, Madrid Á, Ariceta G, Ballarín J, Torra R, Estivill X, Ars E. Targeted next-generation sequencing in steroid-resistant nephrotic syndrome: mutations in multiple glomerular genes may influence disease severity. Eur J Hum Genet 2014; 23:1192-9. [PMID: 25407002 PMCID: PMC4538209 DOI: 10.1038/ejhg.2014.252] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 10/14/2014] [Accepted: 10/16/2014] [Indexed: 01/26/2023] Open
Abstract
Genetic diagnosis of steroid-resistant nephrotic syndrome (SRNS) using Sanger sequencing is complicated by the high genetic heterogeneity and phenotypic variability of this disease. We aimed to improve the genetic diagnosis of SRNS by simultaneously sequencing 26 glomerular genes using massive parallel sequencing and to study whether mutations in multiple genes increase disease severity. High-throughput mutation analysis was performed in 50 SRNS and/or focal segmental glomerulosclerosis (FSGS) patients, a validation cohort of 25 patients with known pathogenic mutations, and a discovery cohort of 25 uncharacterized patients with probable genetic etiology. In the validation cohort, we identified the 42 previously known pathogenic mutations across NPHS1, NPHS2, WT1, TRPC6, and INF2 genes. In the discovery cohort, disease-causing mutations in SRNS/FSGS genes were found in nine patients. We detected three patients with mutations in an SRNS/FSGS gene and COL4A3. Two of them were familial cases and presented a more severe phenotype than family members with mutation in only one gene. In conclusion, our results show that massive parallel sequencing is feasible and robust for genetic diagnosis of SRNS/FSGS. Our results indicate that patients carrying mutations in an SRNS/FSGS gene and also in COL4A3 gene have increased disease severity.
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Affiliation(s)
- Gemma Bullich
- 1] Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Catalonia, Spain [2] Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Catalonia, Spain
| | - Daniel Trujillano
- 1] Genomics and Disease Group, Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG), Barcelona, Catalonia, Spain [2] Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain [3] Hospital del Mar Medical Research Institute (IMIM), Barcelona, Catalonia, Spain [4] CIBER in Epidemiology and Public Health (CIBERESP), Barcelona, Catalonia, Spain
| | - Sheila Santín
- Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Catalonia, Spain
| | - Stephan Ossowski
- 1] Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain [2] Genomic and Epigenomic Variation in Disease Group, Centre for Genomic Regulation (CRG), Barcelona, Catalonia, Spain
| | - Santiago Mendizábal
- Pediatric Nephrology Department, Hospital Universitario La Fe, Valencia, Spain
| | - Gloria Fraga
- Pediatric Nephrology Department, Hospital de la Santa Creu i Sant Pau, Barcelona, Catalonia, Spain
| | - Álvaro Madrid
- Pediatric Nephrology Department, Hospital Vall d'Hebron, Barcelona, Spain
| | - Gema Ariceta
- Pediatric Nephrology Department, Hospital Vall d'Hebron, Barcelona, Spain
| | - José Ballarín
- Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Catalonia, Spain
| | - Roser Torra
- Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Catalonia, Spain
| | - Xavier Estivill
- 1] Genomics and Disease Group, Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG), Barcelona, Catalonia, Spain [2] Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain [3] Hospital del Mar Medical Research Institute (IMIM), Barcelona, Catalonia, Spain [4] CIBER in Epidemiology and Public Health (CIBERESP), Barcelona, Catalonia, Spain
| | - Elisabet Ars
- 1] Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Catalonia, Spain [2] Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Catalonia, Spain
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Abstract
Specific channels permit movement of selected ions through cellular membranes, and are of vital importance in a number of physiological processes, particularly in excitable tissues such as nerve and muscle, but also in endocrine organs and in epithelial biology. Disorders of channel proteins are termed channelopathies, and their importance is increasingly recognised within medicine. In the kidney, ion channels have critical roles enabling sodium and potassium reuptake or excretion along the nephron, in magnesium homeostasis, in the control of water reabsorption in the collecting duct, and in determining glomerular permeability. In this review, we assess the channelopathies encountered in each nephron segment, and see how their molecular and genetic characterisation in the past 20–30 years has furthered our understanding of normal kidney physiology and disease processes, aids correct diagnosis and promises future therapeutic opportunities.
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Affiliation(s)
- KW Loudon
- Department of Renal Medicine, Addenbrooke’s Hospital, Cambridge, UK
| | - AC Fry
- Department of Renal Medicine, Addenbrooke’s Hospital, Cambridge, UK
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49
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Brown EJ, Pollak MR, Barua M. Genetic testing for nephrotic syndrome and FSGS in the era of next-generation sequencing. Kidney Int 2014; 85:1030-8. [PMID: 24599252 PMCID: PMC4118212 DOI: 10.1038/ki.2014.48] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 01/07/2014] [Accepted: 01/09/2014] [Indexed: 12/11/2022]
Abstract
The haploid human genome is composed of three billion base pairs, about one percent of which consists of exonic regions, the coding sequence for functional proteins, also now known as the “exome”. The development of next-generation sequencing makes it possible from a technical and economic standpoint to sequence an individual’s exome but at the cost of generating long lists of gene variants that are not straightforward to interpret. Various public consortiums such as the 1000 Genomes Project and the NHLBI Exome Sequencing Project have sequenced the exomes and a subset of entire genomes of over 2500 control individuals with ongoing efforts to further catalogue genetic variation in humans.1 The use of these public databases facilitates the interpretation of these variant lists produced by exome sequencing and, as a result, novel genetic variants linked to disease are being discovered and reported at a record rate. However, the interpretation of these results and their bearing on diagnosis, prognosis, and treatment is becoming ever more complicated. Here, we discuss the application of genetic testing to individuals with focal and segmental glomerulosclerosis (FSGS), taking a historical perspective on gene identification and its clinical implications along with the growing potential of next-generation sequencing.
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Affiliation(s)
- Elizabeth J Brown
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Martin R Pollak
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
| | - Moumita Barua
- 1] Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA [2] Department of Medicine, Toronto General Hospital, Toronto, Ontario, Canada
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50
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Krall P, Pineda C, Ruiz P, Ejarque L, Vendrell T, Camacho JA, Mendizábal S, Oliver A, Ballarín J, Torra R, Ars E. Cost-effective PKHD1 genetic testing for autosomal recessive polycystic kidney disease. Pediatr Nephrol 2014; 29:223-34. [PMID: 24162162 DOI: 10.1007/s00467-013-2657-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 09/30/2013] [Accepted: 10/04/2013] [Indexed: 12/22/2022]
Abstract
BACKGROUND Genetic diagnosis of autosomal recessive polycystic kidney disease (ARPKD) is challenging due to the length and allelic heterogeneity of the PKHD1 gene. Mutations appear to be clustered at specific exons, depending on the geographic origin of the patient. We aimed to identify the PKHD1 exons most likely mutated in Spanish ARPKD patients. METHODS Mutation analysis was performed in 50 ARPKD probands and nine ARPKD-suspicious patients by sequencing PKHD1 exons arranged by their reported mutation frequency. Haplotypes containing the most frequent mutations were analyzed. Other PKD genes (HNF1B, PKD1, PKD2) were sequenced in PKHD1-negative cases. RESULTS Thirty-six different mutations (concentrated in 24 PKHD1 exons) were detected, giving a mutation detection rate of 86%. The screening of five exons (58, 32, 34, 36, 37) yielded a 54% chance of detecting one mutation; the screening of nine additional exons (3, 9, 39, 61, 5, 22, 26, 41, 57) increased the chance to 76%. The c.9689delA mutation was present in 17 (34%) patients, all of whom shared the same haplotype. Two HNF1B mutations and one PKD1 variant were detected in negative cases. CONCLUSIONS Establishing a PKHD1 exon mutation profile in a specific population and starting the analysis with the most likely mutated exons might significantly enhance the efficacy of genetic testing in ARPKD. Analysis of other PKD genes might be considered, especially in suspicious cases.
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Affiliation(s)
- Paola Krall
- Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, C/Cartagena, 340-350, 08025, Barcelona, Spain
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