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Shirai Y, Miura K, Ishizuka K, Ando T, Kanda S, Hashimoto J, Hamasaki Y, Hotta K, Ito N, Honda K, Tanabe K, Takano T, Hattori M. A multi-institutional study found a possible role of anti-nephrin antibodies in post-transplant focal segmental glomerulosclerosis recurrence. Kidney Int 2024; 105:608-617. [PMID: 38110152 DOI: 10.1016/j.kint.2023.11.022] [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: 08/31/2023] [Revised: 11/07/2023] [Accepted: 11/10/2023] [Indexed: 12/20/2023]
Abstract
Possible roles of anti-nephrin antibodies in post-transplant recurrent focal segmental glomerulosclerosis (FSGS) have been reported recently. To confirm these preliminary results, we performed a multi-institutional study of 22 Japanese pediatric kidney transplant recipients with FSGS including eight genetic FSGS and 14 non-genetic (presumed primary) FSGS. Eleven of the 14 non-genetic FSGS patients had post-transplant recurrent FSGS. Median (interquartile range) plasma levels of anti-nephrin antibodies in post-transplant recurrent FSGS measured using ELISA were markedly high at 899 (831, 1292) U/mL (cutoff 231 U/mL) before transplantation or during recurrence. Graft biopsies during recurrence showed punctate IgG deposition co-localized with nephrin that had altered localization with increased nephrin tyrosine phosphorylation and Src homology and collagen homology A expressions. Graft biopsies after remission showed no signals for IgG and a normal expression pattern of nephrin. Anti-nephrin antibody levels decreased to 155 (53, 367) U/mL in five patients with samples available after remission. In patients with genetic FSGS as in those with non-genetic FSGS without recurrence, anti-nephrin antibody levels were comparable to those of 30 control individuals, and graft biopsies had no signals for IgG and a normal expression pattern of nephrin. Thus, our results suggest that circulating anti-nephrin antibodies are a possible candidate for circulating factors involved in the pathogenesis of post-transplant recurrent FSGS and that this may be mediated by nephrin phosphorylation. Larger studies including other ethnicities are required to confirm this finding.
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Affiliation(s)
- Yoko Shirai
- Department of Pediatric Nephrology, Tokyo Women's Medical University, Tokyo, Japan
| | - Kenichiro Miura
- Department of Pediatric Nephrology, Tokyo Women's Medical University, Tokyo, Japan
| | - Kiyonobu Ishizuka
- Department of Pediatric Nephrology, Tokyo Women's Medical University, Tokyo, Japan
| | - Taro Ando
- Department of Pediatric Nephrology, Tokyo Women's Medical University, Tokyo, Japan
| | | | - Junya Hashimoto
- Department of Nephrology, Toho University Faculty of Medicine, Tokyo, Japan
| | - Yuko Hamasaki
- Department of Nephrology, Toho University Faculty of Medicine, Tokyo, Japan
| | - Kiyohiko Hotta
- Department of Urology, Hokkaido University, Graduate School of Medicine, Hokkaido, Japan
| | - Naoko Ito
- Department of Surgical Pathology, Tokyo Women's Medical University, Tokyo, Japan
| | - Kazuho Honda
- Department of Anatomy, Showa University School of Medicine, Tokyo, Japan
| | - Kenji Tanabe
- Medical Research Institute, Tokyo Women's Medical University, Tokyo, Japan
| | - Tomoko Takano
- Division of Nephrology, McGill University Health Centre, Montreal, Québec, Canada
| | - Motoshi Hattori
- Department of Pediatric Nephrology, Tokyo Women's Medical University, Tokyo, Japan.
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Al Jurdi A, El Mouhayyar C, Efe O, Jeyabalan A, Riella LV. Nephrotic-range proteinuria: a potential risk factor for failure of tixagevimab-cilgavimab prophylaxis. J Nephrol 2024; 37:141-147. [PMID: 37658973 DOI: 10.1007/s40620-023-01750-5] [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: 05/09/2023] [Accepted: 07/28/2023] [Indexed: 09/05/2023]
Abstract
BACKGROUND Pre-exposure prophylaxis with tixagevimab-cilgavimab has been shown to reduce the incidence of SARS-CoV-2 infection in immunocompromised individuals. Individuals with nephrotic-range proteinuria can lose immunoglobulins such as tixagevimab-cilgavimab in the urine and, therefore, may derive less benefit from tixagevimab-cilgavimab. There are no published studies evaluating the association of nephrotic-range proteinuria with failure of tixagevimab-cilgavimab prophylaxis. METHODS We conducted a retrospective observational cohort study of all individuals at our center who received tixagevimab-cilgavimab while they had nephrotic-range proteinuria. Each individual in the nephrotic group was matched 1:3 with controls who were matched for B cell depletion therapy in addition to the total dose and date of first tixagevimab-cilgavimab administration. The primary outcome was the development of breakthrough SARS-CoV-2 infection after receiving tixagevimab-cilgavimab. RESULTS Sixteen patients received tixagevimab-cilgavimab between January 1st, 2022, and June 30th, 2022, at a time when they had nephrotic-range proteinuria. Proteinuria levels and serum creatinine levels were higher while serum albumin levels were lower in the nephrotic group compared to the control group. At a median follow-up of 251 days, 38% of individuals in the nephrotic group had developed breakthrough SARS-CoV-2 infections, compared to only 13% in the control group at a median follow-up of 238 days. Nephrotic-range proteinuria was associated with a higher incidence of breakthrough infection (log-rank P = 0.04). CONCLUSIONS Nephrotic-range proteinuria may increase the risk of failure of tixagevimab-cilgavimab pre-exposure prophylaxis. Prospective studies to validate these findings and to evaluate the optimal dosing strategy of antibody-based prophylaxis in this group of patients are needed.
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Affiliation(s)
- Ayman Al Jurdi
- Center for Transplantation Sciences, Massachusetts General Hospital, Boston, MA, USA
- Division of Nephrology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Vasculitis and Glomerulonephritis Center, Division of Nephrology, Massachusetts General Hospital, Boston, MA, USA
| | | | - Orhan Efe
- Division of Nephrology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Vasculitis and Glomerulonephritis Center, Division of Nephrology, Massachusetts General Hospital, Boston, MA, USA
| | - Anushya Jeyabalan
- Division of Nephrology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Vasculitis and Glomerulonephritis Center, Division of Nephrology, Massachusetts General Hospital, Boston, MA, USA
| | - Leonardo V Riella
- Center for Transplantation Sciences, Massachusetts General Hospital, Boston, MA, USA.
- Division of Nephrology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
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3
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Hayward S, Parmesar K, Saleem MA. What is circulating factor disease and how is it currently explained? Pediatr Nephrol 2023; 38:3513-3518. [PMID: 36952039 PMCID: PMC10514121 DOI: 10.1007/s00467-023-05928-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 02/15/2023] [Accepted: 02/20/2023] [Indexed: 03/24/2023]
Abstract
Nephrotic syndrome (NS) consists of the clinical triad of hypoalbuminaemia, high levels of proteinuria and oedema, and describes a heterogeneous group of disease processes with different underlying drivers. The existence of circulating factor disease (CFD) as a driver of NS has been epitomised by a subset of patients who exhibit disease recurrence after transplantation, alongside laboratory work. Several circulating factors have been proposed and studied, broadly grouped into protease components such as soluble urokinase-type plasminogen activator (suPAR), hemopexin (Hx) and calcium/calmodulin-serine protease kinase (CASK), and other circulating proteases, and immune components such as TNF-α, CD40 and cardiotrophin-like cytokine-1 (CLC-1). While currently there is no definitive way of assessing risk of CFD pre-transplantation, promising work is emerging through the study of 'multi-omic' bioinformatic data from large national cohorts and biobanks.
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Affiliation(s)
- Samantha Hayward
- Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK.
- MRC Integrative Epidemiology Unit, Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK.
| | - Kevon Parmesar
- Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Moin A Saleem
- Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
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Nagai K. Immunosuppressive Agent Options for Primary Nephrotic Syndrome: A Review of Network Meta-Analyses and Cost-Effectiveness Analysis. Medicina (B Aires) 2023; 59:medicina59030601. [PMID: 36984602 PMCID: PMC10054564 DOI: 10.3390/medicina59030601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 03/13/2023] [Accepted: 03/16/2023] [Indexed: 03/22/2023] Open
Abstract
Therapeutic options with immunosuppressive agents for glomerular diseases have widened with refinements to the Kidney Disease Improving Global Outcomes (KDIGO) guidelines from 2012 to 2021. However, international guidelines do not necessarily match the reality in each country. Expensive therapies such as rituximab and calcineurin inhibitors are sometimes inaccessible to patients with refractory nephrotic syndrome due to cost or regulations. Under the Japanese medical insurance system, rituximab is accessible but still limited to steroid-dependent patients who developed idiopathic nephrotic syndrome in childhood. Based on international KDIGO guidelines and other national guidelines, possible applications of immunosuppressive agents for nephrotic syndrome are comprehensively examined in this review. While rituximab has become the mainstay of immunosuppressive therapy for nephrotic syndrome, clinical trials have indicated that options such as cyclophosphamide, calcineurin inhibitors, and mycophenolate mofetil would be preferable. Given the rising number of patients with nephrotic syndrome worldwide, KDIGO guidelines mention the need for further consideration of cost-effectiveness. If the new option of rituximab is to be the first choice in combination with steroids for nephrotic syndrome, its cost-effectiveness should also be verified. Among the few studies examining the cost-effectiveness of treatments for nephrotic syndrome, administration of rituximab to young adults has been shown to be cost-beneficial, at least in Japan. However, further large-scale studies involving multiple facilities are needed to verify such findings. Network meta-analyses have concluded that the efficacy of rituximab remains controversial and confirmation through high-quality studies of large cohorts is needed. To this end, the mechanisms of action underlying immunosuppressive agents, both old and new, need to be understood and experience must be accumulated to evaluate possible effects and side effects.
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Affiliation(s)
- Kei Nagai
- University of Tsukuba Hospital Hitachi Social Cooperation Education Research Center, Hitachi 317-0077, Ibaraki, Japan
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5
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Hada I, Shimizu A, Takematsu H, Nishibori Y, Kimura T, Fukutomi T, Kudo A, Ito-Nitta N, Kiuchi Z, Patrakka J, Mikami N, Leclerc S, Akimoto Y, Hirayama Y, Mori S, Takano T, Yan K. A Novel Mouse Model of Idiopathic Nephrotic Syndrome Induced by Immunization with the Podocyte Protein Crb2. J Am Soc Nephrol 2022; 33:2008-2025. [PMID: 35985815 PMCID: PMC9678040 DOI: 10.1681/asn.2022010070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 07/25/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The cause of podocyte injury in idiopathic nephrotic syndrome (INS) remains unknown. Although recent evidence points to the role of B cells and autoimmunity, the lack of animal models mediated by autoimmunity limits further research. We aimed to establish a mouse model mimicking human INS by immunizing mice with Crb2, a transmembrane protein expressed at the podocyte foot process. METHODS C3H/HeN mice were immunized with the recombinant extracellular domain of mouse Crb2. Serum anti-Crb2 antibody, urine protein-to-creatinine ratio, and kidney histology were studied. For signaling studies, a Crb2-expressing mouse podocyte line was incubated with anti-Crb2 antibody. RESULTS Serum anti-Crb2 autoantibodies and significant proteinuria were detected 4 weeks after the first immunization. The proteinuria reached nephrotic range at 9-13 weeks and persisted up to 29 weeks. Initial kidney histology resembled minimal change disease in humans, and immunofluorescence staining showed delicate punctate IgG staining in the glomerulus, which colocalized with Crb2 at the podocyte foot process. A subset of mice developed features resembling FSGS after 18 weeks. In glomeruli of immunized mice and in Crb2-expressing podocytes incubated with anti-Crb2 antibody, phosphorylation of ezrin, which connects Crb2 to the cytoskeleton, increased, accompanied by altered Crb2 localization and actin distribution. CONCLUSION The results highlight the causative role of anti-Crb2 autoantibody in podocyte injury in mice. Crb2 immunization could be a useful model to study the immunologic pathogenesis of human INS, and may support the role of autoimmunity against podocyte proteins in INS.
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Affiliation(s)
- Ichiro Hada
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
| | - Akira Shimizu
- Department of Analytic Human Pathology, Nippon Medical School, Tokyo, Japan
| | - Hiromu Takematsu
- Department of Molecular Cell Biology, Faculty of Medical Technology, Graduate School of Health Sciences, Fujita Health University, Toyoake, Japan
| | - Yukino Nishibori
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
| | - Toru Kimura
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Tokyo, Japan
| | - Toshiyuki Fukutomi
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Tokyo, Japan
| | - Akihiko Kudo
- Department of Microscopic Anatomy, Kyorin University School of Medicine, Tokyo, Japan
| | - Noriko Ito-Nitta
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
| | - Zentaro Kiuchi
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
| | - Jaakko Patrakka
- KI/AZ Integrated Cardio Metabolic Center, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital, Stockholm, Sweden
| | - Naoaki Mikami
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
| | - Simon Leclerc
- Department of Medicine, Division of Nephrology, Research Institute of the McGill University Health Centre, Montreal, Canada
| | - Yoshihiro Akimoto
- Department of Microscopic Anatomy, Kyorin University School of Medicine, Tokyo, Japan
| | - Yoshiaki Hirayama
- Vaccine & Reagent, R&D Department, Denka Co., Ltd, Gosen-City, Japan
| | - Satoka Mori
- Denka Innovation Center, Denka Co., Ltd, Machida, Japan
| | - Tomoko Takano
- Department of Medicine, Division of Nephrology, Research Institute of the McGill University Health Centre, Montreal, Canada
| | - Kunimasa Yan
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
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6
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New Insights into the Treatment of Glomerular Diseases: When Mechanisms Become Vivid. Int J Mol Sci 2022; 23:ijms23073525. [PMID: 35408886 PMCID: PMC8998908 DOI: 10.3390/ijms23073525] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 03/18/2022] [Accepted: 03/22/2022] [Indexed: 12/23/2022] Open
Abstract
Treatment for glomerular diseases has been extrapolated from the experience of other autoimmune disorders while the underlying pathogenic mechanisms were still not well understood. As the classification of glomerular diseases was based on patterns of juries instead of mechanisms, treatments were typically the art of try and error. With the advancement of molecular biology, the role of the immune agent in glomerular diseases is becoming more evident. The four-hit theory based on the discovery of gd-IgA1 gives a more transparent outline of the pathogenesis of IgA nephropathy (IgAN), and dysregulation of Treg plays a crucial role in the pathogenesis of minimal change disease (MCD). An epoch-making breakthrough is the discovery of PLA2R antibodies in the primary membranous nephropathy (pMN). This is the first biomarker applied for precision medicine in kidney disease. Understanding the immune system’s role in glomerular diseases allows the use of various immunosuppressants or other novel treatments, such as complement inhibitors, to treat glomerular diseases more reasonable. In this era of advocating personalized medicine, it is inevitable to develop precision medicine with mechanism-based novel biomarkers and novel therapies in kidney disease.
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7
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Watts AJ, Keller KH, Lerner G, Rosales I, Collins AB, Sekulic M, Waikar SS, Chandraker A, Riella LV, Alexander MP, Troost JP, Chen J, Fermin D, Yee JL, Sampson MG, Beck LH, Henderson JM, Greka A, Rennke HG, Weins A. Discovery of Autoantibodies Targeting Nephrin in Minimal Change Disease Supports a Novel Autoimmune Etiology. J Am Soc Nephrol 2022; 33:238-252. [PMID: 34732507 PMCID: PMC8763186 DOI: 10.1681/asn.2021060794] [Citation(s) in RCA: 102] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 10/10/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Failure of the glomerular filtration barrier, primarily by loss of slit diaphragm architecture, underlies nephrotic syndrome in minimal change disease. The etiology remains unknown. The efficacy of B cell-targeted therapies in some patients, together with the known proteinuric effect of anti-nephrin antibodies in rodent models, prompted us to hypothesize that nephrin autoantibodies may be present in patients with minimal change disease. METHODS We evaluated sera from patients with minimal change disease, enrolled in the Nephrotic Syndrome Study Network (NEPTUNE) cohort and from our own institutions, for circulating nephrin autoantibodies by indirect ELISA and by immunoprecipitation of full-length nephrin from human glomerular extract or a recombinant purified extracellular domain of human nephrin. We also evaluated renal biopsies from our institutions for podocyte-associated punctate IgG colocalizing with nephrin by immunofluorescence. RESULTS In two independent patient cohorts, we identified circulating nephrin autoantibodies during active disease that were significantly reduced or absent during treatment response in a subset of patients with minimal change disease. We correlated the presence of these autoantibodies with podocyte-associated punctate IgG in renal biopsies from our institutions. We also identified a patient with steroid-dependent childhood minimal change disease that progressed to end stage kidney disease; she developed a massive post-transplant recurrence of proteinuria that was associated with high pretransplant circulating nephrin autoantibodies. CONCLUSIONS Our discovery of nephrin autoantibodies in a subset of adults and children with minimal change disease aligns with published animal studies and provides further support for an autoimmune etiology. We propose a new molecular classification of nephrin autoantibody minimal change disease to serve as a framework for instigation of precision therapeutics for these patients.
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Affiliation(s)
- Andrew J.B. Watts
- Department of Pathology, Brigham and Women’s Hospital, and Harvard Medical School, Boston, Massachusetts,Renal Division, Department of Medicine, Brigham and Women’s Hospital, and Harvard Medical School, Boston, Massachusetts
| | - Keith H. Keller
- Department of Pathology, Brigham and Women’s Hospital, and Harvard Medical School, Boston, Massachusetts
| | - Gabriel Lerner
- Department of Pathology, Boston Medical Center and Boston University, Boston, Massachusetts,Section of Nephrology, Department of Medicine, Boston Medical Center and Boston University, Boston, Massachusetts
| | - Ivy Rosales
- Department of Pathology, Massachusetts General Hospital, and Harvard Medical School, Boston, Massachusetts
| | - A. Bernard Collins
- Department of Pathology, Massachusetts General Hospital, and Harvard Medical School, Boston, Massachusetts
| | - Miroslav Sekulic
- Department of Pathology, Brigham and Women’s Hospital, and Harvard Medical School, Boston, Massachusetts,Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York
| | - Sushrut S. Waikar
- Renal Division, Department of Medicine, Brigham and Women’s Hospital, and Harvard Medical School, Boston, Massachusetts,Section of Nephrology, Department of Medicine, Boston Medical Center and Boston University, Boston, Massachusetts
| | - Anil Chandraker
- Renal Division, Department of Medicine, Brigham and Women’s Hospital, and Harvard Medical School, Boston, Massachusetts
| | - Leonardo V. Riella
- Division of Nephrology, Massachusetts General Hospital, and Harvard Medical School, Boston, Massachusetts
| | - Mariam P. Alexander
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Jonathan P. Troost
- Division of Nephrology, Department of Pediatrics, University of Michigan, Ann Arbor, Michigan
| | - Junbo Chen
- Department of Pathology, Boston Medical Center and Boston University, Boston, Massachusetts
| | - Damian Fermin
- Division of Medicine, Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan
| | - Jennifer L. Yee
- Division of Medicine, Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan
| | - Matthew G. Sampson
- Department of Medicine/Pediatric Nephrology, Boston Children’s Hospital, and Harvard Medical School, Boston, Massachusetts,Kidney Disease Initiative, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Laurence H. Beck
- Section of Nephrology, Department of Medicine, Boston Medical Center and Boston University, Boston, Massachusetts
| | - Joel M. Henderson
- Department of Pathology, Boston Medical Center and Boston University, Boston, Massachusetts
| | - Anna Greka
- Renal Division, Department of Medicine, Brigham and Women’s Hospital, and Harvard Medical School, Boston, Massachusetts,Kidney Disease Initiative, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Helmut G. Rennke
- Department of Pathology, Brigham and Women’s Hospital, and Harvard Medical School, Boston, Massachusetts
| | - Astrid Weins
- Department of Pathology, Brigham and Women’s Hospital, and Harvard Medical School, Boston, Massachusetts,Renal Division, Department of Medicine, Brigham and Women’s Hospital, and Harvard Medical School, Boston, Massachusetts
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8
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Horinouchi T, Nozu K, Iijima K. An updated view of the pathogenesis of steroid-sensitive nephrotic syndrome. Pediatr Nephrol 2022; 37:1957-1965. [PMID: 35006356 PMCID: PMC9307535 DOI: 10.1007/s00467-021-05401-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 11/01/2021] [Accepted: 11/24/2021] [Indexed: 11/28/2022]
Abstract
Idiopathic nephrotic syndrome is the most common childhood glomerular disease. Most forms of this syndrome respond to corticosteroids at standard doses and are, therefore, defined as steroid-sensitive nephrotic syndrome (SSNS). Immunological mechanisms and subsequent podocyte disorders play a pivotal role in SSNS and have been studied for years; however, the precise pathogenesis remains unclear. With recent advances in genetic techniques, an exhaustive hypothesis-free approach called a genome-wide association study (GWAS) has been conducted in various populations. GWASs in pediatric SSNS peaked in the human leukocyte antigen class II region in various populations. Additionally, an association of immune-related CALHM6/FAM26F, PARM1, BTNL2, and TNFSF15 genes, as well as NPHS1, which encodes nephrin expressed in podocytes, has been identified as a locus that achieves genome-wide significance in pediatric SSNS. However, the specific mechanism of SSNS development requires elucidation. This review describes an updated view of SSNS pathogenesis from immunological and genetic aspects, including interactions with infections or allergies, production of circulating factors, and an autoantibody hypothesis.
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Affiliation(s)
- Tomoko Horinouchi
- grid.31432.370000 0001 1092 3077Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Kandai Nozu
- grid.31432.370000 0001 1092 3077Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Kazumoto Iijima
- Hyogo Prefectural Kobe Children's Hospital, Kobe, Japan. .,Department of Advanced Pediatric Medicine, Kobe University Graduate School of Medicine, Minatojimaminami-machi 1-6-7, Chuo-ku, Kobe, 650-0047, Japan.
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9
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Basgen JM, Wong JS, Ray J, Nicholas SB, Campbell KN. Podocyte Foot Process Effacement Precedes Albuminuria and Glomerular Hypertrophy in CD2-Associated Protein Deficient Mice. Front Med (Lausanne) 2021; 8:745319. [PMID: 34568396 PMCID: PMC8460869 DOI: 10.3389/fmed.2021.745319] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 08/20/2021] [Indexed: 12/15/2022] Open
Abstract
Background: Podocyte foot process effacement is a key histologic finding in proteinuric kidney disease. We previously showed that 3-week old CD2AP-deficient mice have significant proteinuria, glomerular hypertrophy and mesangial expansion. The goal of this study is to use morphometry to establish the temporal sequence of podocyte foot process effacement, glomerular volume expansion and albuminuria in Cd2ap−/− mice by measuring these parameters at the 2-week time point. Methods: Wild-type mice age 14 ± 1 days with the Cd2ap gene (WT, N = 5) and mice deficient for Cd2ap (Cd2ap KO, N = 5) were generated. Kidneys were harvested and fixed in 2.5% glutaraldehyde and processed for examination by light and electron microscopy. An average of 415.2 (range 268–716) grid points were counted for all the glomeruli, and quantification of glomerular volume from each kidney. Urine was collected the day prior to sacrifice for urine albumin-to-creatinine ratio (ACR) measurements. Results: There was no difference in albuminuria [median (range) mg/g] between WT [212.2 (177.6–388.4) mg/g] vs. Cd2ap KO mice [203.3 (164.7–910.2) mg/g], P = 0.89; or glomerular volume 68,307[10,931] vs. 66,844[13,022] μm3, p = 0.92. The volume densities of glomerular components of the podocyte, capillary lumen and mesangium were not different for the two groups, P = 0.14, 0.14 and 0.17 respectively. However, foot process width was increased in Cd2ap KO 1128[286] vs. WT [374 ± 42] nm, P = 0.02. Conclusion: Here we show that while 2-week old WT and Cd2ap KO mice have similar levels of albuminuria, glomerular and mesangial volume, Cd2ap KO mice have more extensive podocyte foot process effacement. The data suggests that podocyte injury is the initiating event leading to mesangial expansion and albuminuria in this model.
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Affiliation(s)
- John M Basgen
- Department of Research, Stereology and Morphometry Laboratory, Charles R. Drew University of Medicine and Science, Los Angeles, CA, United States
| | - Jenny S Wong
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Justina Ray
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| | - Susanne B Nicholas
- Division of Nephrology, David Geffen School of Medicine at University of California, Los Angeles, CA, United States
| | - Kirk N Campbell
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, NY, United States
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10
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Zhang Y, Fukusumi Y, Kayaba M, Nakamura T, Sakamoto R, Ashizawa N, Kawachi H. Xanthine oxidoreductase inhibitor topiroxostat ameliorates podocyte injury by inhibiting the reduction of nephrin and podoplanin. Nefrologia 2021; 41:539-547. [PMID: 36165136 DOI: 10.1016/j.nefroe.2021.11.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 10/17/2020] [Indexed: 06/16/2023] Open
Abstract
BACKGROUND Topiroxostat, an inhibitor of xanthine oxidoreductase (XOR) was shown to reduce urinary albumin excretion of hyperuricemic patients with chronic kidney disease. However, its pharmacological mechanism is not well understood. In this study, we examined the effects of topiroxostat on glomerular podocytes. Podocyte is characterized by foot process and a unique cell-cell junction slit diaphragm functioning as a final barrier to prevent proteinuria. METHODS The effects of topiroxostat on the expressions of podocyte functional molecules were analysed in db/db mice, a diabetic nephropathy model, anti-nephrin antibody-induced rat podocyte injury model and cultured podocytes treated with adriamycin. RESULTS Topiroxostat treatment ameliorated albuminuria in db/db mice. The expression of desmin, a podocyte injury marker was increased, and nephrin and podocin, key molecules of slit diaphragm, and podoplanin, an essential molecule in maintaining foot process were downregulated in db/db mice. Topiroxostat treatment prevented the alterations in the expressions of these molecules in db/db mice. XOR activity in kidney was increased in rats with anti-nephrin antibody-induced podocyte injury. Topiroxostat treatment reduced XOR activity and restored the decreased expression of nephrin, podocin and podoplanin in the podocyte injury. Furthermore, topiroxostat enhanced the expression of podoplanin in injured human cultured podocytes. CONCLUSIONS Podocyte injury was evident in db/db mice. Topiroxostat ameliorated albuminuria in diabetic nephropathy model by preventing podocyte injury. Increase of XOR activity in kidney contributes to development of podocyte injury caused by stimulation to slit diaphragm. Topiroxostat has an effect to stabilize slit diaphragm and foot processes by inhibiting the reduction of nephrin, podocin and podoplanin.
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Affiliation(s)
- Ying Zhang
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Yoshiyasu Fukusumi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Mutsumi Kayaba
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Takashi Nakamura
- Pharmacological Study Group, Pharmaceutical Research Laboratories, Sanwa Kagaku Kenkyusho, Mie, Japan
| | - Ryusuke Sakamoto
- Pharmacological Study Group, Pharmaceutical Research Laboratories, Sanwa Kagaku Kenkyusho, Mie, Japan
| | - Naoki Ashizawa
- Biological Research Group, Research Department, Medical R&D Division, Fuji Yakuhin, Saitama, Japan
| | - Hiroshi Kawachi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
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11
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Ivanov V, Fukusumi Y, Zhang Y, Yasuda H, Kitazawa M, Kawachi H. Synbindin Downregulation Participates in Slit Diaphragm Dysfunction. Am J Nephrol 2021; 52:620-629. [PMID: 34515036 DOI: 10.1159/000517975] [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: 05/12/2021] [Accepted: 06/01/2021] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Synbindin, originally identified as a neuronal cytoplasmic molecule, was found in glomeruli. The cDNA subtractive hybridization technique showed the mRNA expression of synbindin in glomeruli was downregulated in puromycin aminonucleoside (PAN) nephropathy, a mimic of minimal-change nephrotic syndrome. METHODS The expression of synbindin in podocytes was analyzed in normal rats and 2 types of rat nephrotic models, anti-nephrin antibody-induced nephropathy, a pure slit diaphragm injury model, and PAN nephropathy, by immunohistochemical analysis and RT-PCR techniques. To elucidate the function of synbindin, a gene silencing study with human cultured podocytes was performed. RESULTS Synbindin was mainly expressed at the slit diaphragm area of glomerular epithelial cells (podocytes). In both nephrotic models, decreased mRNA expression and the altered staining of synbindin were already detected at the early phase when proteinuria and the altered staining of nephrin, a key molecule of slit diaphragm, were not detected yet. Synbindin staining was clearly reduced when severe proteinuria was observed. When the cultured podocytes were treated with siRNA for synbindin, the cell changed to a round shape, and filamentous actin structure was clearly altered. The expression of ephrin-B1, a transmembrane protein at slit diaphragm, was clearly lowered, and synaptic vesicle-associated protein 2B (SV2B) was upregulated in the synbindin knockdown cells. CONCLUSION Synbindin participates in maintaining foot processes and slit diaphragm as a downstream molecule of SV2B-mediated vesicle transport. Synbindin downregulation participates in slit diaphragm dysfunction. Synbindin can be an early marker to detect podocyte injury.
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Affiliation(s)
- Veniamin Ivanov
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Yoshiyasu Fukusumi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Ying Zhang
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Hidenori Yasuda
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Meiko Kitazawa
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Hiroshi Kawachi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
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12
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Chang MY, Chang SY, Su PP, Tian F, Liu ZS. The protective effect of beta-hydroxybutyric acid on renal glomerular epithelial cells in adriamycin-induced injury. Am J Transl Res 2021; 13:8847-8859. [PMID: 34539999 PMCID: PMC8430157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 06/18/2021] [Indexed: 06/13/2023]
Abstract
Beta-hydroxybutyric acid (BHB) exerts a protective effect in experimental of kidney disease models. However, the mechanisms underlying this activity are not well defined. BHB stands out for its ability to inhibit the Nε-lysine acetylation of histone and non-histone proteins, which may affect cellular processes and protein functions. In adriamycin-injured murine glomerular podocytes, BHB ameliorates podocyte damage and preserves actin cytoskeleton integrity, reminiscent of the effect of MS275, a highly selective inhibitor of lysine deacetylase. Further research found that adriamycin causes the reduced acetylation of nephrin, WT-1, and GSK3β. This process is abrogated by the lysine deacetylase inhibitor or BHB, suggesting that the acetylation of these molecules regulates their activity. In contrast, anacardic acid, a selective inhibitor of acetyltransferase, decreases the acetylation of nephrin, WT-1, and GSK3β and mitigates the podocyte protective effects of BHB. Taken together, BHB attenuates adriamycin-elicited glomerular epithelial cell injury, at least in part, by inhibiting the deacetylation of the key molecules implicated in glomerular injury.
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Affiliation(s)
- Ming-Yang Chang
- Department of Nephrology, The First Affiliated Hospital of Zhengzhou UniversityZhengzhou, Henan Province, P. R. China
| | - Si-Yuan Chang
- Department of Surgical Intensive Care Unit, The First Affiliated Hospital of Zhengzhou UniversityZhengzhou, Henan Province, P. R. China
| | - Pei-Pei Su
- Department of Nephrology, The First Affiliated Hospital of Zhengzhou UniversityZhengzhou, Henan Province, P. R. China
| | - Fei Tian
- Department of Nephrology, The First Affiliated Hospital of Zhengzhou UniversityZhengzhou, Henan Province, P. R. China
| | - Zhang-Suo Liu
- Department of Nephrology, The First Affiliated Hospital of Zhengzhou UniversityZhengzhou, Henan Province, P. R. China
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13
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Fukusumi Y, Yasuda H, Zhang Y, Kawachi H. Nephrin-Ephrin-B1-Na +/H + Exchanger Regulatory Factor 2-Ezrin-Actin Axis Is Critical in Podocyte Injury. THE AMERICAN JOURNAL OF PATHOLOGY 2021; 191:1209-1226. [PMID: 33887216 DOI: 10.1016/j.ajpath.2021.04.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 03/13/2021] [Accepted: 04/05/2021] [Indexed: 10/21/2022]
Abstract
Ephrin-B1 is one of the critical components of the slit diaphragm of kidney glomerular podocyte. However, the precise function of ephrin-B1 is unclear. To clarify the function of ephrin-B1, ephrin-B1-associated molecules were studied. RNA-sequencing analysis suggested that Na+/H+ exchanger regulatory factor 2 (NHERF2), a scaffolding protein, is associated with ephrin-B1. NHERF2 was expressed at the apical area and the slit diaphragm, and interacted with the nephrin-ephrin-B1 complex at the slit diaphragm. The nephrin-ephrin-B1-NHERF2 complex interacted with ezrin bound to F-actin. NHERF2 bound ephrin-B1 via its first postsynaptic density protein-95/disks large/zonula occludens-1 domain, and podocalyxin via its second postsynaptic density protein-95/disks large/zonula occludens-1 domain. Both in vitro analyses with human embryonic kidney 293 cells and in vivo study with rat nephrotic model showed that stimulaiton of the slit diaphragm, phosphorylation of nephrin and ephrin-B1, and dephosphorylation of NHERF2 and ezrin, disrupted the linkages of ephrin-B1-NHERF2 and NHERF2-ezrin. It is conceivable that the linkage of nephrin-ephrin-B1-NHERF2-ezrin-actin is a novel critical axis in the podocytes. Ephrin-B1 phosphorylation also disrupted the linkage of an apical transmembrane protein, podocalyxin, with NHERF2-ezrin-actin. The phosphorylation of ephrin-B1 and the consequent dephosphorylation of NHERF2 are critical initiation events leading to podocyte injury.
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Affiliation(s)
- Yoshiyasu Fukusumi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Hidenori Yasuda
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Ying Zhang
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Hiroshi Kawachi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
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14
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Affiliation(s)
- Thomas Benzing
- From Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine, and University Hospital Cologne, and the Excellence Cluster CECAD, University of Cologne, Cologne, Germany (T.B.); and the Section of Nephrology, Department of Medicine, Boston Medical Center and Boston University School of Medicine, Boston (D.S.)
| | - David Salant
- From Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine, and University Hospital Cologne, and the Excellence Cluster CECAD, University of Cologne, Cologne, Germany (T.B.); and the Section of Nephrology, Department of Medicine, Boston Medical Center and Boston University School of Medicine, Boston (D.S.)
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15
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Zhang Y, Fukusumi Y, Kayaba M, Nakamura T, Sakamoto R, Ashizawa N, Kawachi H. Xanthine oxidoreductase inhibitor topiroxostat ameliorates podocyte injury by inhibiting the reduction of nephrin and podoplanin. Nefrologia 2021. [PMID: 33707098 DOI: 10.1016/j.nefro.2020.10.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
BACKGROUND Topiroxostat, an inhibitor of xanthine oxidoreductase (XOR) was shown to reduce urinary albumin excretion of hyperuricemic patients with chronic kidney disease. However, its pharmacological mechanism is not well understood. In this study, we examined the effects of topiroxostat on glomerular podocytes. Podocyte is characterized by foot process and a unique cell-cell junction slit diaphragm functioning as a final barrier to prevent proteinuria. METHODS The effects of topiroxostat on the expressions of podocyte functional molecules were analysed in db/db mice, a diabetic nephropathy model, anti-nephrin antibody-induced rat podocyte injury model and cultured podocytes treated with adriamycin. RESULTS Topiroxostat treatment ameliorated albuminuria in db/db mice. The expression of desmin, a podocyte injury marker was increased, and nephrin and podocin, key molecules of slit diaphragm, and podoplanin, an essential molecule in maintaining foot process were downregulated in db/db mice. Topiroxostat treatment prevented the alterations in the expressions of these molecules in db/db mice. XOR activity in kidney was increased in rats with anti-nephrin antibody-induced podocyte injury. Topiroxostat treatment reduced XOR activity and restored the decreased expression of nephrin, podocin and podoplanin in the podocyte injury. Furthermore, topiroxostat enhanced the expression of podoplanin in injured human cultured podocytes. CONCLUSIONS Podocyte injury was evident in db/db mice. Topiroxostat ameliorated albuminuria in diabetic nephropathy model by preventing podocyte injury. Increase of XOR activity in kidney contributes to development of podocyte injury caused by stimulation to slit diaphragm. Topiroxostat has an effect to stabilize slit diaphragm and foot processes by inhibiting the reduction of nephrin, podocin and podoplanin.
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Affiliation(s)
- Ying Zhang
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Yoshiyasu Fukusumi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Mutsumi Kayaba
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Takashi Nakamura
- Pharmacological Study Group, Pharmaceutical Research Laboratories, Sanwa Kagaku Kenkyusho, Mie, Japan
| | - Ryusuke Sakamoto
- Pharmacological Study Group, Pharmaceutical Research Laboratories, Sanwa Kagaku Kenkyusho, Mie, Japan
| | - Naoki Ashizawa
- Biological Research Group, Research Department, Medical R&D Division, Fuji Yakuhin, Saitama, Japan
| | - Hiroshi Kawachi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
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16
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Kawachi H, Fukusumi Y. New insight into podocyte slit diaphragm, a therapeutic target of proteinuria. Clin Exp Nephrol 2020; 24:193-204. [PMID: 32020343 PMCID: PMC7040068 DOI: 10.1007/s10157-020-01854-3] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 01/15/2020] [Indexed: 12/26/2022]
Abstract
Dysfunction of slit diaphragm, a cell–cell junction of glomerular podocytes, is involved in the development of proteinuria in several glomerular diseases. Slit diaphragm should be a target of a novel therapy for proteinuria. Nephrin, NEPH1, P-cadherin, FAT, and ephrin-B1 were reported to be extracellular components forming a molecular sieve of the slit diaphragm. Several cytoplasmic proteins such as ZO-1, podocin, CD2AP, MAGI proteins and Par-complex molecules were identified as scaffold proteins linking the slit diaphragm to the cytoskeleton. In this article, new insights into these molecules and the pathogenic roles of the dysfunction of these molecules were introduced. The slit diaphragm functions not only as a barrier but also as a signaling platform transfer the signal to the inside of the cell. For maintaining the slit diaphragm function properly, the phosphorylation level of nephrin is strictly regulated. The recent studies on the signaling pathway from nephrin, NEPH1, and ephrin-B1 were reviewed. Although the mechanism regulating the function of the slit diaphragm had remained unclear, recent studies revealed TRPC6 and angiotensin II-regulating mechanisms play a critical role in regulating the barrier function of the slit diaphragm. In this review, recent investigations on the regulation of the slit diaphragm function were reviewed, and a strategy for the establishment of a novel therapy for proteinuria was proposed.
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Affiliation(s)
- Hiroshi Kawachi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata, 951-8510, Japan.
| | - Yoshiyasu Fukusumi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata, 951-8510, Japan
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17
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Takamura S, Fukusumi Y, Zhang Y, Narita I, Kawachi H. Partitioning-Defective-6-Ephrin-B1 Interaction Is Regulated by Nephrin-Mediated Signal and Is Crucial in Maintaining Slit Diaphragm of Podocyte. THE AMERICAN JOURNAL OF PATHOLOGY 2019; 190:333-346. [PMID: 31837290 DOI: 10.1016/j.ajpath.2019.10.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 09/04/2019] [Accepted: 10/18/2019] [Indexed: 01/15/2023]
Abstract
Ephrin-B1 plays a critical role at slit diaphragm. Partitioning-defective (Par)-6 is down-regulated in podocyte of ephrin-B1 knockout mouse, suggesting that Par-6 is associated with ephrin-B1. Par polarity complex, consisting of Par-6, Par-3, and atypical protein kinase C, is essential for tight junction formation. In this study, the expression of Par-6 was analyzed in the normal and nephrotic syndrome model rats, and the molecular association of Par-6, Par-3, ephrin-B1, and nephrin was assessed with the human embryonic kidney 293 cell expression system. Par-6 was concentrated at slit diaphragm. Par 6 interacted with ephrin-B1 but not with nephrin, and Par-3 interacted with nephrin but not with ephrin-B1. The complexes of Par-6-ephrin-B1 and Par-3-nephrin were linked via extracellular sites of ephrin-B1 and nephrin. The Par-6-ephrin-B1 complex was delinked from the Par-3-nephrin complex, and Par-6 and ephrin-B1 were clearly down-regulated already at early phase of nephrotic model. The alteration of Par-6/ephrin-B1 advanced that of Par-3/nephrin. Stimulation to nephrin phosphorylated not only nephrin but also ephrin-B1, and consequently inhibited the interaction between ephrin-B1 and Par-6. Par-6 appeared at presumptive podocyte of early developmental stage and moved to basal area at capillary loop stage to participate in slit diaphragm formation at the final stage. Par-6-ephrin-B1 interaction is crucial for formation and maintenance of slit diaphragm of podocyte.
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Affiliation(s)
- Sayuri Takamura
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan; Division of Clinical Nephrology and Rheumatology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Yoshiyasu Fukusumi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Ying Zhang
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Ichiei Narita
- Division of Clinical Nephrology and Rheumatology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Hiroshi Kawachi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
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18
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Asada Y, Takayanagi T, Kawakami T, Tomatsu E, Masuda A, Yoshino Y, Sekiguchi-Ueda S, Shibata M, Ide T, Niimi H, Yaoita E, Seino Y, Sugimura Y, Suzuki A. Risedronate Attenuates Podocyte Injury in Phosphate Transporter-Overexpressing Rats. Int J Endocrinol 2019; 2019:4194853. [PMID: 31772574 PMCID: PMC6854176 DOI: 10.1155/2019/4194853] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 08/29/2019] [Indexed: 01/01/2023] Open
Abstract
Osteoporosis patients with chronic kidney disease (CKD) are becoming common in our superaging society. Renal dysfunction causes phosphorus accumulation in the circulating plasma and leads to the development of CKD-mineral bone disorder (MBD). We have previously reported that type III Pi transporter-overexpressing transgenic (Pit-1 TG) rats manifest phosphate (Pi)-dependent podocyte injury. In the present study, we explored the effect of risedronate on Pi-induced podocyte injury in vivo. Pit-1 TG rats and wild-type rats at 5 weeks old were divided into a risedronate-treated group and an untreated group. We subcutaneously administered 5 μg/kg body weight of risedronate or saline twice a week during the experimental period. Risedronate did not alter serum creatinine levels at 5, 8, and 12 weeks of age. However, electron microscopy images showed that thickening of the glomerular basement membrane was improved in the risedronate treatment group. Furthermore, immunostaining for podocyte injury markers revealed that both desmin- and connexin43-positive areas were smaller in the risedronate-treated group than in the untreated group, suggesting that bisphosphonates could rescue Pi-induced podocyte injury. In conclusion, our findings suggest that risedronate could maintain glomerular barrier function by rescuing Pi-induced podocyte injury.
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Affiliation(s)
- Yohei Asada
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Takeshi Takayanagi
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Tsukasa Kawakami
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Eisuke Tomatsu
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Atsushi Masuda
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Yasumasa Yoshino
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Sahoko Sekiguchi-Ueda
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Megumi Shibata
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Tomihiko Ide
- Joint Research Support Promotion Facility, Center for Research Promotion and Support, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Hajime Niimi
- Department of Anatomy, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Eishin Yaoita
- Department of Structural Pathology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata 950-2102, Japan
| | - Yusuke Seino
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Yoshihisa Sugimura
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
| | - Atsushi Suzuki
- Department of Endocrinology and Metabolism, Fujita Health University, Toyoake, Aichi 470-1192, Japan
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19
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Ito Y, Katayama K, Nishibori Y, Akimoto Y, Kudo A, Kurayama R, Hada I, Takahashi S, Kimura T, Fukutomi T, Katada T, Suehiro J, Beltcheva O, Tryggvason K, Yan K. Wolf-Hirschhorn syndrome candidate 1-like 1 epigenetically regulates nephrin gene expression. Am J Physiol Renal Physiol 2017; 312:F1184-F1199. [PMID: 28228401 DOI: 10.1152/ajprenal.00305.2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 02/09/2017] [Accepted: 02/21/2017] [Indexed: 01/13/2023] Open
Abstract
Altered expression of nephrin underlies the pathophysiology of proteinuria in both congenital and acquired nephrotic syndrome. However, the epigenetic mechanisms of nephrin gene regulation remain elusive. Here, we show that Wolf-Hirschhorn syndrome candidate 1-like 1 long form (WHSC1L1-L) is a novel epigenetic modifier of nephrin gene regulation. WHSC1L1-L was associated with histone H3K4 and H3K36 in human embryonic kidney cells. WHSC1L1-L gene was expressed in the podocytes, and functional protein product was detected in these cells. WHSC1L1-L was found to bind nephrin but not other podocyte-specific gene promoters, leading to its inhibition/suppression, abrogating the stimulatory effect of WT1 and NF-κB. Gene knockdown of WHSC1L1-L in primary cultured podocytes accelerated the transcription of nephrin but not CD2AP. An in vivo zebrafish study involving the injection of Whsc1l1 mRNA into embryos demonstrated an apparent reduction of nephrin mRNA but not podocin and CD2AP mRNA. Immunohistochemistry showed that both WHSC1L1-L and nephrin emerged at the S-shaped body stage in glomeruli. Immunofluorescence and confocal microscopy displayed WHSC1L1 to colocalize with trimethylated H3K4 in the glomerular podocytes. Chromatin immunoprecipitation assay revealed the reduction of the association of trimethylated H3K4 at the nephrin promoter regions. Finally, nephrin mRNA was upregulated in the glomerulus at the early proteinuric stage of mouse nephrosis, which was associated with the reduction of WHSC1L1. In conclusion, our results demonstrate that WHSC1L1-L acts as a histone methyltransferase in podocytes and regulates nephrin gene expression, which may in turn contribute to the integrity of the slit diaphragm of the glomerular filtration barrier.
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Affiliation(s)
- Yugo Ito
- Department of Pediatrics, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Kan Katayama
- Department of Medical Biochemistry and Biophysics, Division of Matrix Biology, Karolinska Institute, Stockholm, Sweden
| | - Yukino Nishibori
- Department of Pediatrics, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Yoshihiro Akimoto
- Department of Anatomy, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Akihiko Kudo
- Department of Anatomy, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Ryota Kurayama
- Department of Pediatrics, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Ichiro Hada
- Department of Pediatrics, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Shohei Takahashi
- Department of Pediatrics, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Toru Kimura
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Mitaka, Tokyo, Japan; and
| | - Toshiyuki Fukutomi
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Mitaka, Tokyo, Japan; and
| | - Tomohisa Katada
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Mitaka, Tokyo, Japan; and
| | - Junichi Suehiro
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Mitaka, Tokyo, Japan; and
| | - Olga Beltcheva
- Molecular Medicine Center and Department of Medical Chemistry and Biochemistry, Medical University of Sofia, Sofia, Bulgaria
| | - Karl Tryggvason
- Department of Medical Biochemistry and Biophysics, Division of Matrix Biology, Karolinska Institute, Stockholm, Sweden
| | - Kunimasa Yan
- Department of Pediatrics, Kyorin University School of Medicine, Mitaka, Tokyo, Japan;
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20
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Kato T, Mizuno S. Nephron, Wilms' tumor-1 (WT1), and synaptopodin expression in developing podocytes of mice. Exp Anim 2017; 66:183-189. [PMID: 28179596 PMCID: PMC5543238 DOI: 10.1538/expanim.16-0101] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Newborn mouse glomeruli are still immature with a morphological feature of an early
capillary loop stage, but infant mice do not manifest proteinuria. Little is known about
the molecular mechanism whereby infant mice are resistant to proteinuria. Nephrin and
synaptopodin are crucial for slit diaphragm and foot process (FP) formation for avoiding
proteinuria. Nephrin tyrosine phosphorylation means a transient biological signaling
required for FP repair or extension during nephrotic disease. Using an immunohistochemical
technique, we examined the natural course of nephrin, Wilms’ tumor-1 (WT1) and
synaptopodin at 16.5 days of embryonic age (E16.5d) and E19.5d, 7 days of post-neonatal
age (P7d) and P42d during renal development of mice. As a result, nephrin and synaptopodin
were detected at E19.5d in S-shaped bodies. WT1, a transcriptional factor for nephrin, was
detected in nucleus in podocyte-like cells in all stages. Nephrin tyrosine phosphorylation
was evident in glomeruli at P7d, and this was associated with an early-stage of FP
extension. Inversely, nephrin phosphorylation became faint at P42d, along with maturated
FP. Based on the present results, we suggest the sequential molecular mechanism to protect
growing mice from proteinuria: (i) WT1-induced nephrin production by podocytes in S-shaped
bodies at E19.5d; (ii) Synchronized induction of synaptopodin at the same period; and
(iii) FP extension is initiated at a milk-suckling stage under a nephrin
tyrosine-phosphorylated condition, while it is arrested at an adult stage, associated with
a loss of nephrin-based signaling.
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Affiliation(s)
- Takashi Kato
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.,Department of Pathology, Faculty of Medicine, Kindai University, 377-2 Ohno-higashi, Osaka-sayama, Osaka 589-8511, Japan
| | - Shinya Mizuno
- Department of Biochemistry and Molecular Biology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.,Department of Microbiology and Immunology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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21
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Wasik AA, Dumont V, Tienari J, Nyman TA, Fogarty CL, Forsblom C, Lehto M, Lehtonen E, Groop PH, Lehtonen S. Septin 7 reduces nonmuscle myosin IIA activity in the SNAP23 complex and hinders GLUT4 storage vesicle docking and fusion. Exp Cell Res 2016; 350:336-348. [PMID: 28011197 PMCID: PMC5243148 DOI: 10.1016/j.yexcr.2016.12.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 12/10/2016] [Accepted: 12/17/2016] [Indexed: 12/28/2022]
Abstract
Glomerular epithelial cells, podocytes, are insulin responsive and can develop insulin resistance. Here, we demonstrate that the small GTPase septin 7 forms a complex with nonmuscle myosin heavy chain IIA (NMHC-IIA; encoded by MYH9), a component of the nonmuscle myosin IIA (NM-IIA) hexameric complex. We observed that knockdown of NMHC-IIA decreases insulin-stimulated glucose uptake into podocytes. Both septin 7 and NM-IIA associate with SNAP23, a SNARE protein involved in GLUT4 storage vesicle (GSV) docking and fusion with the plasma membrane. We observed that insulin decreases the level of septin 7 and increases the activity of NM-IIA in the SNAP23 complex, as visualized by increased phosphorylation of myosin regulatory light chain. Also knockdown of septin 7 increases the activity of NM-IIA in the complex. The activity of NM-IIA is increased in diabetic rat glomeruli and cultured human podocytes exposed to macroalbuminuric sera from patients with type 1 diabetes. Collectively, the data suggest that the activity of NM-IIA in the SNAP23 complex plays a key role in insulin-stimulated glucose uptake into podocytes. Furthermore, we observed that septin 7 reduces the activity of NM-IIA in the SNAP23 complex and thereby hinders GSV docking and fusion with the plasma membrane. Septin 7, nonmuscle myosin heavy chain IIA (NMHC-IIA) and SNAP23 form a complex. Knockdown of septin 7 increases NM-IIA activity in the SNAP23 complex. Insulin decreases septin 7 level and increases NM-IIA activity in the SNAP23 complex. Septin 7 hinders GSV docking/fusion by reducing NM-IIA activity in the SNAP23 complex.
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Affiliation(s)
- Anita A Wasik
- Department of Pathology, University of Helsinki, 00014 Helsinki, Finland
| | - Vincent Dumont
- Department of Pathology, University of Helsinki, 00014 Helsinki, Finland
| | - Jukka Tienari
- Department of Pathology, University of Helsinki and Helsinki University Hospital, 00290 Helsinki, 05850 Hyvinkää, Finland
| | - Tuula A Nyman
- Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Christopher L Fogarty
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland; Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki, Finland; Diabetes&Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki, Finland
| | - Carol Forsblom
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland; Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki, Finland; Diabetes&Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki, Finland
| | - Markku Lehto
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland; Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki, Finland; Diabetes&Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki, Finland
| | - Eero Lehtonen
- Department of Pathology, University of Helsinki, 00014 Helsinki, Finland; Laboratory Animal Centre, University of Helsinki, 00014 Helsinki, Finland
| | - Per-Henrik Groop
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland; Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki, Finland; Diabetes&Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki, Finland; Baker IDI Heart & Diabetes Institute, 3004 Melbourne, Australia
| | - Sanna Lehtonen
- Department of Pathology, University of Helsinki, 00014 Helsinki, Finland.
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22
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Fan X, Yang H, Kumar S, Tumelty KE, Pisarek-Horowitz A, Rasouly HM, Sharma R, Chan S, Tyminski E, Shamashkin M, Belghasem M, Henderson JM, Coyle AJ, Salant DJ, Berasi SP, Lu W. SLIT2/ROBO2 signaling pathway inhibits nonmuscle myosin IIA activity and destabilizes kidney podocyte adhesion. JCI Insight 2016; 1:e86934. [PMID: 27882344 DOI: 10.1172/jci.insight.86934] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The repulsive guidance cue SLIT2 and its receptor ROBO2 are required for kidney development and podocyte foot process structure, but the SLIT2/ROBO2 signaling mechanism regulating podocyte function is not known. Here we report that a potentially novel signaling pathway consisting of SLIT/ROBO Rho GTPase activating protein 1 (SRGAP1) and nonmuscle myosin IIA (NMIIA) regulates podocyte adhesion downstream of ROBO2. We found that the myosin II regulatory light chain (MRLC), a subunit of NMIIA, interacts directly with SRGAP1 and forms a complex with ROBO2/SRGAP1/NMIIA in the presence of SLIT2. Immunostaining demonstrated that SRGAP1 is a podocyte protein and is colocalized with ROBO2 on the basal surface of podocytes. In addition, SLIT2 stimulation inhibits NMIIA activity, decreases focal adhesion formation, and reduces podocyte attachment to collagen. In vivo studies further showed that podocyte-specific knockout of Robo2 protects mice from hypertension-induced podocyte detachment and albuminuria and also partially rescues the podocyte-loss phenotype in Myh9 knockout mice. Thus, we have identified SLIT2/ROBO2/SRGAP1/NMIIA as a potentially novel signaling pathway in kidney podocytes, which may play a role in regulating podocyte adhesion and attachment. Our findings also suggest that SLIT2/ROBO2 signaling might be a therapeutic target for kidney diseases associated with podocyte detachment and loss.
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Affiliation(s)
- Xueping Fan
- Renal Section, Department of Medicine, Boston University Medical Center, Boston, Massachusetts, USA
| | - Hongying Yang
- Centers for Therapeutic Innovation, Pfizer Inc., Boston, Massachusetts, USA
| | - Sudhir Kumar
- Renal Section, Department of Medicine, Boston University Medical Center, Boston, Massachusetts, USA
| | - Kathleen E Tumelty
- Centers for Therapeutic Innovation, Pfizer Inc., Boston, Massachusetts, USA
| | - Anna Pisarek-Horowitz
- Renal Section, Department of Medicine, Boston University Medical Center, Boston, Massachusetts, USA
| | - Hila Milo Rasouly
- Renal Section, Department of Medicine, Boston University Medical Center, Boston, Massachusetts, USA
| | - Richa Sharma
- Renal Section, Department of Medicine, Boston University Medical Center, Boston, Massachusetts, USA
| | - Stefanie Chan
- Renal Section, Department of Medicine, Boston University Medical Center, Boston, Massachusetts, USA
| | - Edyta Tyminski
- Centers for Therapeutic Innovation, Pfizer Inc., Boston, Massachusetts, USA
| | - Michael Shamashkin
- Centers for Therapeutic Innovation, Pfizer Inc., Boston, Massachusetts, USA
| | - Mostafa Belghasem
- Department of Pathology and Laboratory Medicine, Boston University Medical Center, Boston, Massachusetts, USA
| | - Joel M Henderson
- Department of Pathology and Laboratory Medicine, Boston University Medical Center, Boston, Massachusetts, USA
| | - Anthony J Coyle
- Centers for Therapeutic Innovation, Pfizer Inc., Boston, Massachusetts, USA
| | - David J Salant
- Renal Section, Department of Medicine, Boston University Medical Center, Boston, Massachusetts, USA
| | - Stephen P Berasi
- Centers for Therapeutic Innovation, Pfizer Inc., Boston, Massachusetts, USA
| | - Weining Lu
- Renal Section, Department of Medicine, Boston University Medical Center, Boston, Massachusetts, USA
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23
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Cathepsin L is crucial for the development of early experimental diabetic nephropathy. Kidney Int 2016; 90:1012-1022. [DOI: 10.1016/j.kint.2016.06.035] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 06/22/2016] [Accepted: 06/30/2016] [Indexed: 11/20/2022]
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24
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Wakamatsu A, Fukusumi Y, Hasegawa E, Tomita M, Watanabe T, Narita I, Kawachi H. Role of calcineurin (CN) in kidney glomerular podocyte: CN inhibitor ameliorated proteinuria by inhibiting the redistribution of CN at the slit diaphragm. Physiol Rep 2016; 4:4/6/e12679. [PMID: 27009276 PMCID: PMC4814882 DOI: 10.14814/phy2.12679] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 12/14/2015] [Indexed: 12/21/2022] Open
Abstract
Although calcineurin (CN) is distributed in many cell types and functions in regulating cell functions, the precise roles of CN remained in each type of the cells are not well understood yet. A CN inhibitor (CNI) has been used for steroid‐resistant nephrotic syndrome. A CNI is assumed to ameliorate proteinuria by preventing the overproduction of T‐cell cytokines. However, recent reports suggest that CNI has a direct effect on podocyte. It is accepted that a slit diaphragm (SD), a unique cell–cell junction of podocytes, is a critical barrier preventing a leak of plasma protein into urine. Therefore, we hypothesized that CNI has an effect on the SD. In this study, we analyzed the expression of CN in physiological and in the nephrotic model caused by the antibody against nephrin, a critical component of the SD. We observed that CN is expressed at the SD in normal rat and human kidney sections and has an interaction with nephrin. The staining of CN at the SD was reduced in the nephrotic model, while CN activity in glomeruli was increased. We also observed that the treatment with tacrolimus, a CNI, in this nephrotic model suppressed the redistribution of CN, nephrin, and other SD components and ameliorated proteinuria. These observations suggested that the redistribution and the activation of CN may participate in the development of the SD injury.
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Affiliation(s)
- Ayako Wakamatsu
- Department of Cell Biology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan Division of Clinical Nephrology and Rheumatology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Yoshiyasu Fukusumi
- Department of Cell Biology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Eriko Hasegawa
- Department of Cell Biology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Masayuki Tomita
- Department of Cell Biology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Toru Watanabe
- Department of Pediatrics, Niigata City General Hospital, Niigata, Japan
| | - Ichiei Narita
- Division of Clinical Nephrology and Rheumatology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Hiroshi Kawachi
- Department of Cell Biology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
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25
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Focal segmental glomerular sclerosis: do not overlook the role of immune response. J Nephrol 2016; 29:525-34. [DOI: 10.1007/s40620-016-0272-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 01/28/2016] [Indexed: 10/22/2022]
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26
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Full-length soluble urokinase plasminogen activator receptor down-modulates nephrin expression in podocytes. Sci Rep 2015; 5:13647. [PMID: 26380915 PMCID: PMC4585377 DOI: 10.1038/srep13647] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 08/03/2015] [Indexed: 12/25/2022] Open
Abstract
Increased plasma level of soluble urokinase-type plasminogen activator receptor (suPAR) was associated recently with focal segmental glomerulosclerosis (FSGS). In addition, different clinical studies observed increased concentration of suPAR in various glomerular diseases and in other human pathologies with nephrotic syndromes such as HIV and Hantavirus infection, diabetes and cardiovascular disorders. Here, we show that suPAR induces nephrin down-modulation in human podocytes. This phenomenon is mediated only by full-length suPAR, is time-and dose-dependent and is associated with the suppression of Wilms’ tumor 1 (WT-1) transcription factor expression. Moreover, an antagonist of αvβ3 integrin RGDfv blocked suPAR-induced suppression of nephrin. These in vitro data were confirmed in an in vivo uPAR knock out Plaur−/− mice model by demonstrating that the infusion of suPAR inhibits expression of nephrin and WT-1 in podocytes and induces proteinuria. This study unveiled that interaction of full-length suPAR with αvβ3 integrin expressed on podocytes results in down-modulation of nephrin that may affect kidney functionality in different human pathologies characterized by increased concentration of suPAR.
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27
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Delville M, Sigdel TK, Wei C, Li J, Hsieh SC, Fornoni A, Burke GW, Bruneval P, Naesens M, Jackson A, Alachkar N, Canaud G, Legendre C, Anglicheau D, Reiser J, Sarwal MM. A circulating antibody panel for pretransplant prediction of FSGS recurrence after kidney transplantation. Sci Transl Med 2015; 6:256ra136. [PMID: 25273097 DOI: 10.1126/scitranslmed.3008538] [Citation(s) in RCA: 144] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Recurrence of focal segmental glomerulosclerosis (rFSGS) after kidney transplantation is a cause of accelerated graft loss. To evaluate pathogenic antibodies (Abs) in rFSGS, we processed 141 serum samples from 64 patients with and without primary rFSGS and 34 non-FSGS control patients transplanted at four hospitals. We screened about 9000 antigens in pretransplant sera and selected 10 Abs targeting glomerular antigens for enzyme-linked immunosorbent assay (ELISA) validation. A panel of seven Abs (CD40, PTPRO, CGB5, FAS, P2RY11, SNRPB2, and APOL2) could predict posttransplant FSGS recurrence with 92% accuracy. Pretransplant elevation of anti-CD40 Ab alone had the best correlation (78% accuracy) with rFSGS risk after transplantation. Epitope mapping of CD40 with customized peptide arrays and rFSGS sera demonstrated altered immunogenicity of the extracellular CD40 domain in rFSGS. Immunohistochemistry of CD40 demonstrated a differential expression in FSGS compared to non-FSGS controls. Anti-CD40 Abs purified from rFSGS patients were particularly pathogenic in human podocyte cultures. Injection of anti-CD40/rFSGS Ab enhanced suPAR (soluble urokinase receptor)-mediated proteinuria in wild-type mice, yet no sensitizing effect was noted in mice deficient in CD40 or in wild-type mice that received blocking Ab to CD40. In conclusion, a panel of seven Abs can help identify primary FSGS patients at high risk of recurrence before transplantation. Intrarenal CD40 (and possibly other specific glomerular antigens) is an important contributor to FSGS disease pathogenesis. Human trials of anti-CD40 therapies are warranted to evaluate their efficacy for preventing rFSGS and improving graft survival.
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Affiliation(s)
- Marianne Delville
- Department of Kidney Transplantation, Necker Hospital, Assistance Publique-Hôpitaux de Paris, Université Paris Descartes Sorbonne Paris Cité, INSERM U1171, Réseau Thématique de Recherche et de Soins Centaure, Labex Transplantex, 75015 Paris, France
| | - Tara K Sigdel
- Division of Transplant Surgery, University of California San Francisco, San Francisco, CA 94143, USA
| | - Changli Wei
- Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Jing Li
- Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA
| | - Szu-Chuan Hsieh
- Division of Transplant Surgery, University of California San Francisco, San Francisco, CA 94143, USA
| | - Alessia Fornoni
- Peggy and Harold Katz Family Drug Discovery Center, Division of Nephrology and Hypertension, University of Miami School of Medicine, Miami, FL 33146, USA
| | - George W Burke
- Division of Transplant Surgery, University of Miami School of Medicine, Miami, FL 33146, USA
| | - Patrick Bruneval
- Department of Pathology, Hôpital Européen Georges Pompidou, 20 rue Leblanc, 75015 Paris, France
| | - Maarten Naesens
- Nephrology and Renal Transplantation, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Annette Jackson
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Nada Alachkar
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Guillaume Canaud
- Department of Kidney Transplantation, Necker Hospital, Assistance Publique-Hôpitaux de Paris, Université Paris Descartes Sorbonne Paris Cité, INSERM U1171, Réseau Thématique de Recherche et de Soins Centaure, Labex Transplantex, 75015 Paris, France
| | - Christophe Legendre
- Department of Kidney Transplantation, Necker Hospital, Assistance Publique-Hôpitaux de Paris, Université Paris Descartes Sorbonne Paris Cité, INSERM U1171, Réseau Thématique de Recherche et de Soins Centaure, Labex Transplantex, 75015 Paris, France
| | - Dany Anglicheau
- Department of Kidney Transplantation, Necker Hospital, Assistance Publique-Hôpitaux de Paris, Université Paris Descartes Sorbonne Paris Cité, INSERM U1171, Réseau Thématique de Recherche et de Soins Centaure, Labex Transplantex, 75015 Paris, France
| | - Jochen Reiser
- Department of Medicine, Rush University Medical Center, Chicago, IL 60612, USA.
| | - Minnie M Sarwal
- Division of Transplant Surgery, University of California San Francisco, San Francisco, CA 94143, USA.
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28
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Grahammer F, Benzing T, Huber TB. New insights into mechanisms of glomerular injury and repair from the 10th International Podocyte Conference 2014. Kidney Int 2015; 87:885-93. [DOI: 10.1038/ki.2015.5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 11/11/2014] [Accepted: 11/20/2014] [Indexed: 01/17/2023]
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29
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An update: the role of Nephrin inside and outside the kidney. SCIENCE CHINA-LIFE SCIENCES 2015; 58:649-57. [PMID: 25921941 DOI: 10.1007/s11427-015-4844-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 02/27/2015] [Indexed: 12/18/2022]
Abstract
Nephrin is a key molecule in podocytes to maintain normal slit diaphragm structure. Nephin interacts with many other podocyte and slit diaphragm protein and also mediates important cell signaling pathways in podocytes. Loss of nephrin during the development leads to the congenital nephrotic syndrome in children. Reduction of nephrin expression is often observed in adult kidney diseases including diabetic nephropathy and HIV-associated nephropathy. The critical role of nephrin has been confirmed by different animal models with nephrin knockout and knockdown. Recent studies demonstrate that knockdown of nephrin expression in adult mice aggravates the progression of unilateral nephrectomy and Adriamycin-induced kidney disease. In addition to its critical role in maintaining normal glomerular filtration unit in the kidney, nephrin is also expressed in other organs. However, the exact role of nephrin in kidney and extra-renal organs has not been well characterized. Future studies are required to determine whether nephrin could be developed as a drug target to treat patients with kidney disease.
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30
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Li X, Chuang PY, D'Agati VD, Dai Y, Yacoub R, Fu J, Xu J, Taku O, Premsrirut PK, Holzman LB, He JC. Nephrin Preserves Podocyte Viability and Glomerular Structure and Function in Adult Kidneys. J Am Soc Nephrol 2015; 26:2361-77. [PMID: 25644109 DOI: 10.1681/asn.2014040405] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 11/19/2014] [Indexed: 01/12/2023] Open
Abstract
Nephrin is required during kidney development for the maturation of podocytes and formation of the slit diaphragm junctional complex. Because nephrin expression is downregulated in acquired glomerular diseases, nephrin deficiency is considered a pathologic feature of glomerular injury. However, whether nephrin deficiency exacerbates glomerular injury in glomerular diseases has not been experimentally confirmed. Here, we generated mice with inducible RNA interference-mediated nephrin knockdown. Short-term nephrin knockdown (6 weeks), starting after the completion of kidney development at 5 weeks of age, did not affect glomerular structure or function. In contrast, mice with long-term nephrin knockdown (20 weeks) developed mild proteinuria, foot process effacement, filtration slit narrowing, mesangial hypercellularity and sclerosis, glomerular basement membrane thickening, subendothelial zone widening, and podocyte apoptosis. When subjected to an acquired glomerular insult induced by unilateral nephrectomy or doxorubicin, mice with short-term nephrin knockdown developed more severe glomerular injury compared with mice without nephrin knockdown. Additionally, nephrin-knockdown mice developed more exaggerated glomerular enlargement when subjected to unilateral nephrectomy and more podocyte apoptosis and depletion after doxorubicin challenge. AKT phosphorylation, which is a slit diaphragm-mediated and nephrin-dependent pathway in the podocyte, was markedly reduced in mice with long-term or short-term nephrin knockdown challenged with uninephrectomy or doxorubicin. Taken together, our data establish that under the basal condition and in acquired glomerular diseases, nephrin is required to maintain slit diaphragm integrity and slit diaphragm-mediated signaling to preserve glomerular function and podocyte viability in adult mice.
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Affiliation(s)
- Xuezhu Li
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Nephrology; Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Peter Y Chuang
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York;
| | - Vivette D D'Agati
- Department of Pathology, College of Physicians and Surgeons, Columbia University, New York, New York
| | - Yan Dai
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Nephrology, Shanghai First Municipal Hospital, Shanghai Jiaotao University School of Medicine; Shanghai, China
| | - Rabi Yacoub
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jia Fu
- Research Institute of Nephrology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
| | - Jin Xu
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Oltjon Taku
- State University of New York at University at Binghamton, Binghamton, New York
| | | | - Lawrence B Holzman
- Renal Electrolyte and Hypertension Division, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania; and
| | - John Cijiang He
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York; Renal Section, James J Peter Veterans Administration Medical Center, Bronx, New York
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31
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Muthenna P, Raghu G, Kumar PA, Surekha M, Reddy GB. Effect of cinnamon and its procyanidin-B2 enriched fraction on diabetic nephropathy in rats. Chem Biol Interact 2014; 222:68-76. [DOI: 10.1016/j.cbi.2014.08.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Revised: 08/23/2014] [Accepted: 08/27/2014] [Indexed: 01/17/2023]
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32
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Fukusumi Y, Miyauchi N, Hashimoto T, Saito A, Kawachi H. Therapeutic target for nephrotic syndrome: Identification of novel slit diaphragm associated molecules. World J Nephrol 2014; 3:77-84. [PMID: 25332898 PMCID: PMC4202494 DOI: 10.5527/wjn.v3.i3.77] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 05/15/2014] [Accepted: 06/27/2014] [Indexed: 02/06/2023] Open
Abstract
The slit diaphragm bridging the neighboring foot processes functions as a final barrier of glomerular capillary wall for preventing the leak of plasma proteins into primary urine. It is now accepted that the dysfunction of the sit diaphragm contributes to the development of proteinuria in several glomerular diseases. Nephrin, a gene product of NPHS1, a gene for a congenital nephrotic syndrome of Finnish type, constitutes an extracellular domain of the slit diaphragm. Podocin was identified as a gene product of NPHS2, a gene for a familial steroid-resistant nephrotic syndrome of French. Podocin binds the cytoplasmic domain of nephrin. After then, CD2 associated protein, NEPH1 and transient receptor potential-6 were also found as crucial molecules of the slit diaphragm. In order to explore other novel molecules contributing to the development of proteinuria, we performed a subtraction hybridization assay with a normal rat glomerular RNA and a glomerular RNA of rats with a puromycin aminonucleoside nephropathy, a mimic of a human minimal change type nephrotic syndrome. Then we have found that synaptic vesicle protein 2B, ephrin-B1 and neurexin were already downregulated at the early stage of puromycin aminonucleoside nephropathy, and that these molecules were localized close to nephrin. It is conceivable that these molecules are the slit diaphragm associated molecules, which participate in the regulation of the barrier function. These molecules could be targets to establish a novel therapy for nephrotic syndrome.
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33
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Satoh D, Hirose T, Harita Y, Daimon C, Harada T, Kurihara H, Yamashita A, Ohno S. aPKCλ maintains the integrity of the glomerular slit diaphragm through trafficking of nephrin to the cell surface. J Biochem 2014; 156:115-28. [PMID: 24700503 PMCID: PMC4112437 DOI: 10.1093/jb/mvu022] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The slit diaphragm (SD), the specialized intercellular junction between renal glomerular epithelial cells (podocytes), provides a selective-filtration barrier in renal glomeruli. Dysfunction of the SD results in glomerular diseases that are characterized by disappearance of SD components, such as nephrin, from the cell surface. Although the importance of endocytosis and degradation of SD components for the maintenance of SD integrity has been suggested, the dynamic nature of the turnover of intact cell-surface SD components remained unclear. Using isolated rat glomeruli we show that the turnover rates of cell-surface SD components are relatively high; they almost completely disappear from the cell surface within minutes. The exocytosis, but not endocytosis, of heterologously expressed nephrin requires the kinase activity of the cell polarity regulator atypical protein kinase C (aPKC). Consistently, we demonstrate that podocyte-specific deletion of aPKCλ resulted in a decrease of cell-surface localization of SD components, causing massive proteinuria. In conclusion, the regulation of SD turnover by aPKC is crucial for the maintenance of SD integrity and defects in aPKC signalling can lead to proteinuria. These findings not only reveal the pivotal importance of the dynamic turnover of cell-surface SD components but also suggest a novel pathophysiological basis in glomerular disease.
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Affiliation(s)
- Daisuke Satoh
- Department of Molecular Biology, Graduate School of Medical Science, Yokohama City University, Yokohama; Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo; Department of Pediatrics, Yokohama City University, Yokohama; Department of Anatomy, Juntendo University, School of Medicine, Bunkyo, Tokyo; and Advanced Medical Research Center, Yokohama City University, Yokohama, Kanagawa, Japan
| | - Tomonori Hirose
- Department of Molecular Biology, Graduate School of Medical Science, Yokohama City University, Yokohama; Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo; Department of Pediatrics, Yokohama City University, Yokohama; Department of Anatomy, Juntendo University, School of Medicine, Bunkyo, Tokyo; and Advanced Medical Research Center, Yokohama City University, Yokohama, Kanagawa, Japan
| | - Yutaka Harita
- Department of Molecular Biology, Graduate School of Medical Science, Yokohama City University, Yokohama; Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo; Department of Pediatrics, Yokohama City University, Yokohama; Department of Anatomy, Juntendo University, School of Medicine, Bunkyo, Tokyo; and Advanced Medical Research Center, Yokohama City University, Yokohama, Kanagawa, JapanDepartment of Molecular Biology, Graduate School of Medical Science, Yokohama City University, Yokohama; Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo; Department of Pediatrics, Yokohama City University, Yokohama; Department of Anatomy, Juntendo University, School of Medicine, Bunkyo, Tokyo; and Advanced Medical Research Center, Yokohama City University, Yokohama, Kanagawa, Japan
| | - Chikara Daimon
- Department of Molecular Biology, Graduate School of Medical Science, Yokohama City University, Yokohama; Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo; Department of Pediatrics, Yokohama City University, Yokohama; Department of Anatomy, Juntendo University, School of Medicine, Bunkyo, Tokyo; and Advanced Medical Research Center, Yokohama City University, Yokohama, Kanagawa, Japan
| | - Tomonori Harada
- Department of Molecular Biology, Graduate School of Medical Science, Yokohama City University, Yokohama; Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo; Department of Pediatrics, Yokohama City University, Yokohama; Department of Anatomy, Juntendo University, School of Medicine, Bunkyo, Tokyo; and Advanced Medical Research Center, Yokohama City University, Yokohama, Kanagawa, Japan
| | - Hidetake Kurihara
- Department of Molecular Biology, Graduate School of Medical Science, Yokohama City University, Yokohama; Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo; Department of Pediatrics, Yokohama City University, Yokohama; Department of Anatomy, Juntendo University, School of Medicine, Bunkyo, Tokyo; and Advanced Medical Research Center, Yokohama City University, Yokohama, Kanagawa, Japan
| | - Akio Yamashita
- Department of Molecular Biology, Graduate School of Medical Science, Yokohama City University, Yokohama; Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo; Department of Pediatrics, Yokohama City University, Yokohama; Department of Anatomy, Juntendo University, School of Medicine, Bunkyo, Tokyo; and Advanced Medical Research Center, Yokohama City University, Yokohama, Kanagawa, Japan
| | - Shigeo Ohno
- Department of Molecular Biology, Graduate School of Medical Science, Yokohama City University, Yokohama; Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo; Department of Pediatrics, Yokohama City University, Yokohama; Department of Anatomy, Juntendo University, School of Medicine, Bunkyo, Tokyo; and Advanced Medical Research Center, Yokohama City University, Yokohama, Kanagawa, JapanDepartment of Molecular Biology, Graduate School of Medical Science, Yokohama City University, Yokohama; Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, Tokyo; Department of Pediatrics, Yokohama City University, Yokohama; Department of Anatomy, Juntendo University, School of Medicine, Bunkyo, Tokyo; and Advanced Medical Research Center, Yokohama City University, Yokohama, Kanagawa, Japan
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Yaoita E, Yoshida Y, Nameta M, Zhang Y, Fujinaka H, Magdeldin S, Xu B, Yamamoto T. Heparin increasing podocyte-specific gene expressions. Nephrology (Carlton) 2014; 19:195-201. [DOI: 10.1111/nep.12207] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/12/2014] [Indexed: 01/20/2023]
Affiliation(s)
- Eishin Yaoita
- Department of Structural Pathology, Institute of Nephrology; Niigata University Graduate School of Medical and Dental Sciences; Niigata Japan
| | - Yutaka Yoshida
- Department of Structural Pathology, Institute of Nephrology; Niigata University Graduate School of Medical and Dental Sciences; Niigata Japan
| | - Masaaki Nameta
- Cooperative Laboratory of Electron Microscopy; Niigata University; Niigata Japan
| | - Ying Zhang
- Department of Structural Pathology, Institute of Nephrology; Niigata University Graduate School of Medical and Dental Sciences; Niigata Japan
| | - Hidehiko Fujinaka
- Institute for Clinical Research; Niigata National Hospital; Niigata Japan
| | - Sameh Magdeldin
- Department of Structural Pathology, Institute of Nephrology; Niigata University Graduate School of Medical and Dental Sciences; Niigata Japan
- Department of Physiology, Faculty of Veterinary Medicine; Suez Canal University; Ismailia Egypt
| | - Bo Xu
- Department of Structural Pathology, Institute of Nephrology; Niigata University Graduate School of Medical and Dental Sciences; Niigata Japan
| | - Tadashi Yamamoto
- Department of Structural Pathology, Institute of Nephrology; Niigata University Graduate School of Medical and Dental Sciences; Niigata Japan
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Yoshida Y, Miyamoto M, Taguchi I, Xu B, Zhang Y, Yaoita E, Fujinaka H, Yamamoto T. Human kidney glomerulus proteome and biomarker discovery of kidney diseases. Proteomics Clin Appl 2012; 2:420-7. [PMID: 21136843 DOI: 10.1002/prca.200780016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The kidney glomerulus is the site of plasma filtration and production of primary urine in the kidney. The structure not only plays a pivotal role in ultrafiltration of plasma into urine but also is the locus of kidney diseases progressing to chronic renal failure. Patients afflicted with these glomerular diseases frequently progress to irreversible loss of renal function and inevitably require replacement therapies. The diagnosis and treatment of glomerular diseases are now based on clinical manifestations, urinary protein excretion level, and renal pathology of needle biopsy specimens. The molecular mechanisms underlying the progression of glomerular diseases are still obscure despite a great number of clinical and experimental studies. Proteomics is a particularly promising approach for the discovery of proteins relevant to physiological and pathophysiological processes, and has been recently employed in nephrology. Although until now most efforts of proteomic analysis have been conducted with urine, the biological fluid that is easily collected without invasive procedures, proteomic analysis of the glomerulus, the tissue most proximal to the disease loci, is the most straightforward approach. In this review, we attempt to outline the current status of clinical proteomics of the glomerulus and provide a perspective of protein biomarker discovery of glomerular diseases.
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Affiliation(s)
- Yutaka Yoshida
- Department of Structural Pathology, Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.
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Fan X, Li Q, Pisarek-Horowitz A, Rasouly HM, Wang X, Bonegio RG, Wang H, McLaughlin M, Mangos S, Kalluri R, Holzman LB, Drummond IA, Brown D, Salant DJ, Lu W. Inhibitory effects of Robo2 on nephrin: a crosstalk between positive and negative signals regulating podocyte structure. Cell Rep 2012; 2:52-61. [PMID: 22840396 DOI: 10.1016/j.celrep.2012.06.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 03/05/2012] [Accepted: 06/05/2012] [Indexed: 11/20/2022] Open
Abstract
Robo2 is the cell surface receptor for the repulsive guidance cue Slit and is involved in axon guidance and neuronal migration. Nephrin is a podocyte slit-diaphragm protein that functions in the kidney glomerular filtration barrier. Here, we report that Robo2 is expressed at the basal surface of mouse podocytes and colocalizes with nephrin. Biochemical studies indicate that Robo2 forms a complex with nephrin in the kidney through adaptor protein Nck. In contrast to the role of nephrin that promotes actin polymerization, Slit2-Robo2 signaling inhibits nephrin-induced actin polymerization. In addition, the amount of F-actin associated with nephrin is increased in Robo2 knockout mice that develop an altered podocyte foot process structure. Genetic interaction study further reveals that loss of Robo2 alleviates the abnormal podocyte structural phenotype in nephrin null mice. These results suggest that Robo2 signaling acts as a negative regulator on nephrin to influence podocyte foot process architecture.
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Affiliation(s)
- Xueping Fan
- Renal Section, Department of Medicine, Boston University Medical Center, Boston, MA 02118, USA
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Sahali D, Audard V, Rémy P, Lang P. [Pathogenesis and treatment of idiopathic nephrotic syndrome in adults]. Nephrol Ther 2012; 8:180-92. [PMID: 22425458 DOI: 10.1016/j.nephro.2011.11.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Idiopathic nephrotic syndrome is the most frequent glomerular disease in children and in young adults. While genetic analyses have provided new insights into disease pathogenesis through the discovery of several podocyte genes mutated in distinct forms of inherited nephrotic syndrome, the molecular bases of minimal change nephrotic syndrome and focal and segmental glomerulosclerosis with relapses remain unclear. Although immune cell disorders, which may involve both innate and adaptive immunity, appear to play a role in the pathogenesis of steroid sensitive minimal change nephrotic syndrome, the mechanisms by which they induce podocyte dysfunction remain unresolved. It was postulated that podocyte injury results from a circulating factor secreted by abnormal T cells, but the possibility that bipolarity of the disease results from a functional disorder shared by both immune cells and the podocytes is not excluded. Minimal change nephrotic syndrome relapses are associated with an expansion of T and B cell compartments and production of growth factors as well as many cytokines. Dysfunction of T cells is supported by several findings including, inhibition of a type IV hypersensitivity reaction and unclassical T helper polarization, resulting from transcriptional interference between Th1 and Th2 transcriptional factors. A low serum level of some IgG fractions is frequently observed suggesting a defect in T-B cell cooperation, which remains to be explored. In this review, we discuss recent advances in the pathogenesis and the therapy of idiopathic nephrotic syndrome.
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Affiliation(s)
- Dil Sahali
- Service de néphrologie, centre hospitalier universitaire Henri-Mondor, Créteil, France.
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Sekiguchi S, Suzuki A, Asano S, Nishiwaki-Yasuda K, Shibata M, Nagao S, Yamamoto N, Matsuyama M, Sato Y, Yan K, Yaoita E, Itoh M. Phosphate overload induces podocyte injury via type III Na-dependent phosphate transporter. Am J Physiol Renal Physiol 2011; 300:F848-56. [PMID: 21307129 DOI: 10.1152/ajprenal.00334.2010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Uptake of P(i) at the cellular membrane is essential for the maintenance of cell viability. However, phosphate overload is also stressful for cells and can result in cellular damage. In the present study, we investigated the effects of the transgenic overexpression of type III P(i) transporter Pit-1 to explore the role of extracellular P(i) in glomerular sclerosis during chronic renal disease. Pit-1 transgenic (TG) rats showed progressive proteinuria associated with hypoalbuminemia and dyslipidemia. Ultrastructural analysis of TG rat kidney by transmission electron microscopy showed a diffuse effacement of the foot processes of podocytes and a thickening of the glomerular basement membrane, which were progressively exhibited since 8 wk after birth. TG rats died at 32 wk of age due to cachexia. At this time, more thickening of the glomerular basement membrane and segmental sclerosis were observed in glomeruli of the TG rats. Immunohistochemical examination using anti-connexin 43 and anti-desmin antibodies suggested the progressive injury of podocytes in TG rats. TG rats showed higher P(i) uptake in podocytes than wild-type rats, especially under low P(i) concentration. When 8-wk-old wild-type and TG rats were fed a 0.6% normal phosphate (NP) or 1.2% phosphate (HP) diet for 12 wk, HP diet-treated TG rats showed more progressive proteinuria and higher serum creatinine levels than NP diet-treated TG rats. In conclusion, our findings suggest that overexpression of Pit-1 in rats induces phosphate-dependent podocyte injury and damage to the glomerular barrier, which result in the progression of glomerular sclerosis in the kidney.
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Affiliation(s)
- Sahoko Sekiguchi
- Div. of Endocrinology and Metabolism, Dept. of Internal Medicine, Fujita Health Univ., Kutsukake, Toyoake, Aichi 470-1192, Japan.
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Saito A, Miyauchi N, Hashimoto T, Karasawa T, Han GD, Kayaba M, Sumi T, Tomita M, Ikezumi Y, Suzuki K, Koitabashi Y, Shimizu F, Kawachi H. Neurexin-1, a presynaptic adhesion molecule, localizes at the slit diaphragm of the glomerular podocytes in kidneys. Am J Physiol Regul Integr Comp Physiol 2010; 300:R340-8. [PMID: 21048075 DOI: 10.1152/ajpregu.00640.2009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The slit diaphragm connecting the adjacent foot processes of glomerular epithelial cells (podocytes) is the final barrier of the glomerular capillary wall and serves to prevent proteinuria. Podocytes are understood to be terminally differentiated cells and share some common features with neurons. Neurexin is a presynaptic adhesion molecule that plays a role in synaptic differentiation. Although neurexin has been understood to be specifically expressed in neuronal tissues, we found that neurexin was expressed in several organs. Several forms of splice variants of neurexin-1α were detected in the cerebrum, but only one form of neurexin-1α was detected in glomeruli. Immunohistochemical study showed that neurexin restrictedly expressed in the podocytes in kidneys. Dual-labeling analyses showed that neurexin was colocalized with CD2AP, an intracellular component of the slit diaphragm. Immunoprecipitation assay using glomerular lysate showed that neurexin interacted with CD2AP and CASK. These observations indicated that neurexin localized at the slit diaphragm area. The staining intensity of neurexin in podocytes was clearly lowered, and their staining pattern shifted to a more discontinuous patchy pattern in the disease models showing severe proteinuria. The expression and localization of neurexin in these models altered more clearly and rapidly than that of other slit diaphragm components. We propose that neurexin is available as an early diagnostic marker to detect podocyte injury. Neurexin coincided with nephrin, a key molecule of the slit diaphragm detected in a presumptive podocyte of the developing glomeruli and in the glomeruli for which the slit diaphragm is repairing injury. These observations suggest that neurexin is involved in the formation of the slit diaphragm and the maintenance of its function.
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Affiliation(s)
- Akira Saito
- Dept. of Cell Biology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata, 951-8510, Japan
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Yousefipour Z, Oyekan A, Newaz M. Interaction of oxidative stress, nitric oxide and peroxisome proliferator activated receptor gamma in acute renal failure. Pharmacol Ther 2010; 125:436-45. [PMID: 20117134 DOI: 10.1016/j.pharmthera.2009.12.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Accepted: 12/24/2009] [Indexed: 01/23/2023]
Abstract
Oxidative stress has been reported to play a critical role in the pathology of acute renal failure (ARF). An interaction between different reactive species and/or their sources have been the focus of extensive studies. The exact sources of reactive species generated in biological systems under different disease states are always elusive because they are also a part of physiological processes. Exaggerated involvement of different oxidation pathways including NAD(P)H oxidase has been proposed in different models of ARF. An interaction between oxygen species and nitrogen species has drawn extensive attention because of the deleterious effects of peroxynitrite and their possible effects on antioxidant systems. Recent advances in molecular biology have allowed us to understand glomerular function more precisely, especially the organization and importance of the slit diaphragm. Identification of slit diaphragm proteins came as a breakthrough and a possibility of therapeutic manipulation in ARF is encouraging. Transcriptional regulation of the expression of slit diaphragm protein is of particular importance because their presence is crucial in the maintenance of glomerular function. This review highlights the involvement of oxidative stress in ARF, sources of these reactive species, a possible interaction between different reactive species, and involvement of PPARgamma, a nuclear transcription factor in this process.
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Affiliation(s)
- Zivar Yousefipour
- Center for Cardiovascular Diseases, Texas Southern University, Houston, Texas, United States
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Lo WY, Chen SY, Wang HJ, Shih HC, Chen CH, Tsai CH, Tsai FJ. Association between genetic polymorphisms of the NPHS1 gene and membranous glomerulonephritis in the Taiwanese population. Clin Chim Acta 2010; 411:714-8. [PMID: 20138859 DOI: 10.1016/j.cca.2010.02.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 02/01/2010] [Accepted: 02/01/2010] [Indexed: 11/26/2022]
Abstract
BACKGROUND Membranous glomerulonephritis (MGN) is one of the most common causes of nephrotic syndrome in adults. NPHS1 encoding nephrin is a transmembrane protein of the immunoglobulin family. We clarified the relationship between NPHS1 gene polymorphisms and the susceptibility or progression of MGN. METHODS We recruited a cohort of 132 biopsy-diagnosed MGN patients and 257 healthy subjects. Genotyping of three SNPs (rs401824, rs437168 and rs3814995) at chromosome positions 41034749 (5'UTR), 41026259(exon17) and 41034052 (exon 3) was performed using a Taqman SNP genotyping assay. RESULTS There was a significant difference in genotype frequency distribution of rs437168 polymorphism between MGN patients and controls. The results also showed that the frequency of the G allele was significantly higher in the patient group. Among the polymorphisms rs437168, rs401824 and rs3814995, no significant haplotype was shown in MGN patients. A stratified analysis revealed that a high disease progression in the AA genotype of rs401824 and GG genotype of rs437168 patients were associated with a low rate of remission. CONCLUSIONS The presence of the different genotypes of NPHS1 was associated with susceptibility of MGN and the remission of proteinuria during disease progression after the therapy.
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Affiliation(s)
- Wan-Yu Lo
- Graduate Institute of Integrated Medicine, China Medical University, Taichung, Taiwan.
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Zhang Y, Yoshida Y, Nameta M, Xu B, Taguchi I, Ikeda T, Fujinaka H, Magdeldin S, Mohamed SM, Tsukaguchi H, Harita Y, Yaoita E, Yamamoto T. Glomerular proteins related to slit diaphragm and matrix adhesion in the foot processes are highly tyrosine phosphorylated in the normal rat kidney. Nephrol Dial Transplant 2010; 25:1785-95. [PMID: 20067908 DOI: 10.1093/ndt/gfp697] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Tyrosine phosphorylation of proteins has been a focus of extensive studies since it plays crucial roles in regulation of diverse biological reactions. To understand the involvement of tyrosine phosphorylation in kidney functions, a comprehensive proteomic study for tyrosine-phosphorylated proteins was performed in the normal rat kidney. METHODS Two-dimensional gel electrophoresis and immunoprecipitation using anti-phosphotyrosine antibodies were employed to detect tyrosine-phosphorylated proteins. The proteins were analysed by mass spectrometry and validated by immunological analyses using specific antibodies. RESULTS Most of tyrosine-phosphorylated proteins were confined to the glomerulus and predominantly localized along the glomerular capillary wall, especially in the foot processes of podocytes. Our systematic proteomic analysis identified nephrin, SHPS-1 (tyrosine-protein phosphatase non-receptor-type substrate 1), FAK1 and paxillin as major tyrosine-phosphorylated proteins and Neph1, talin and vinculin as minor tyrosine-phosphorylated proteins. In the present study, SHPS-1 was identified as a novel tyrosine-phosphorylated protein in the glomerulus and was also predominantly localized at the foot processes. Mass spectrometric analysis identified in vivo phosphorylation sites of SHPS-1 on Y460, Y477 and Y501. CONCLUSION This study identified tyrosine-phosphorylated proteins in normal rat kidney, which were prominently rich in the glomerulus and localized at the podocyte foot processes. These proteins were categorized as cell-to-cell or cell-to-matrix adhesion complex-related molecules, suggesting their pivotal roles in the glomerular ultrafiltration.
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Affiliation(s)
- Ying Zhang
- Department of Structural Pathology, Institute of Nephrology, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
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Aberrantly glycosylated IgA1 induces mesangial cells to produce platelet-activating factor that mediates nephrin loss in cultured podocytes. Kidney Int 2009; 77:417-27. [PMID: 20016469 DOI: 10.1038/ki.2009.473] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The reaction of mesangial cells with aberrantly glycosylated IgA1 has been implicated in the etiology of IgA nephropathy (IgAN). Tumor necrosis factor, which is assumed to mediate the interaction between mesangial cells and podocytes, also induces the expression of platelet-activating factor (PAF). In this study, we determined whether PAF affects the expression of nephrin (an adhesion molecule critical to glomerular permselectivity) and cytoskeletal F-actin organization in podocytes. We treated human mesangial cells with atypically glycosylated IgA1 either prepared in vitro or derived from the sera of patients with IgAN. We then prepared conditioned media from these cells and added them to cultured human podocytes in the presence of PAF receptor antagonists. Podocytes transfected to overexpress acetylhydrolase, the main catabolic enzyme of PAF, served as controls. Downregulation of nephrin expression and F-actin reorganization occurred when podocytes were cultured with mesangial cell-conditioned medium. Preincubation of podocytes with a PAF receptor antagonist prevented the loss and redistribution of nephrin. In control podocytes overexpressing acetylhydrolase, nephrin loss was abrogated. Our results suggest that atypically glycosylated IgA-induced PAF from mesangial cells is a mediator of podocyte changes, which, when more directly tested elsewhere, were found to be associated with proteinuria. Hence, it is possible that these in vitro findings may be relevant to the proteinuria of IgAN.
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Okada T, Sakaguchi T, Hatamura I, Saji F, Negi S, Otani H, Muragaki Y, Kawachi H, Shigematsu T. Tolvaptan, a selective oral vasopressin V2 receptor antagonist, ameliorates podocyte injury in puromycin aminonucleoside nephrotic rats. Clin Exp Nephrol 2009; 13:438-446. [PMID: 19452240 DOI: 10.1007/s10157-009-0196-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Accepted: 04/20/2009] [Indexed: 10/20/2022]
Abstract
BACKGROUND Proteinuria caused by glomerular disease is characterized by podocyte injury. Vasopressin V2 receptor antagonists are effective in reducing albuminuria, although their actions on glomerular podocytes have not been explored. The objective of this study was to evaluate the effects of tolvaptan, a selective oral V2 receptor antagonist, on podocytes in a puromycin aminonucleoside (PAN)-induced nephrosis rat model. METHODS Rats were allocated to a control, PAN nephrosis, or tolvaptan-treated PAN nephrosis group (n = 9 per group). Urinary protein excretion and serum levels of total protein, albumin, creatinine, and total cholesterol were measured on day 10. The influence of tolvaptan on podocytes was examined in renal tissues by immunofluorescence and electron microscopy. RESULTS PAN induced massive proteinuria and serum creatinine elevation on day 10, both of which were significantly ameliorated by tolvaptan. Immunofluorescence studies of the podocyte-associated proteins nephrin and podocin revealed granular staining patterns in PAN nephrosis rats. In tolvaptan-treated rats, nephrin and podocin expressions retained their normal linear pattern. Electron microscopy showed foot process effacement was ameliorated in tolvaptan-treated rats. CONCLUSIONS Tolvaptan is protective against podocyte damage and proteinuria in PAN nephrosis. This study indicates that tolvaptan exerts a renoprotective effect by affecting podocyte morphology and probably function in PAN nephrosis. Tolvaptan is a promising pharmacological tool in the treatment of renal edema.
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Affiliation(s)
- Tadashi Okada
- Division of Nephrology and Blood Purification Medicine, Wakayama Medical University, 811-1, Kimiidera, Wakayama, 641-0012, Japan.
| | - Toshifumi Sakaguchi
- Division of Nephrology and Blood Purification Medicine, Wakayama Medical University, 811-1, Kimiidera, Wakayama, 641-0012, Japan
| | - Ikuji Hatamura
- First Department of Pathology, Wakayama Medical University, Wakayama, Japan
| | - Fumie Saji
- Division of Nephrology and Blood Purification Medicine, Wakayama Medical University, 811-1, Kimiidera, Wakayama, 641-0012, Japan
| | - Shigeo Negi
- Division of Nephrology and Blood Purification Medicine, Wakayama Medical University, 811-1, Kimiidera, Wakayama, 641-0012, Japan
| | - Haruhisa Otani
- Division of Nephrology and Blood Purification Medicine, Wakayama Medical University, 811-1, Kimiidera, Wakayama, 641-0012, Japan.,Ryoshukai Wakayama Kidney Disease Clinic, Wakayama, Japan
| | - Yasuteru Muragaki
- First Department of Pathology, Wakayama Medical University, Wakayama, Japan
| | - Hiroshi Kawachi
- Department of Cell Biology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Takashi Shigematsu
- Division of Nephrology and Blood Purification Medicine, Wakayama Medical University, 811-1, Kimiidera, Wakayama, 641-0012, Japan
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Tesař V, Zima T. Recent Progress in the Pathogenesis of Nephrotic Proteinuria. Crit Rev Clin Lab Sci 2008; 45:139-220. [DOI: 10.1080/10408360801934865] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Otaki Y, Miyauchi N, Higa M, Takada A, Kuroda T, Gejyo F, Shimizu F, Kawachi H. Dissociation of NEPH1 from nephrin is involved in development of a rat model of focal segmental glomerulosclerosis. Am J Physiol Renal Physiol 2008; 295:F1376-87. [PMID: 18715943 DOI: 10.1152/ajprenal.00075.2008] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is a disease showing severe proteinuria, and the disease progresses to end-stage kidney failure in many cases. However, the pathogenic mechanism of FSGS is not well understood. The slit diaphragm (SD), which bridges the neighboring foot processes of glomerular epithelial cells, is understood to function as a barrier of the glomerular capillary wall. To investigate the role of SD dysfunction in the development of FSGS, we analyzed the expression of SD-associated molecules in rat adriamycin-induced nephropathy, a mimic of FSGS. The staining of the SD molecules nephrin, podocin, and NEPH1 had already shifted to a discontinuous dotlike pattern at the initiation phase of the disease, when neither proteinuria nor any morphological alterations were detected yet. The alteration of NEPH1 expression was the most evident among the molecules examined, and NEPH1 was dissociated from nephrin at the initiation phase. On day 28, when severe proteinuria was detected and sclerotic changes were already observed, alteration of the expressions of nephrin, podocin, and NEPH1 worsened, but no alteration in the expression of other SD-associated molecules or other podocyte molecules was detected. It is postulated that the dissociation of NEPH1 from nephrin initiates proteinuria and that the SD alteration restricted in these molecules plays a critical role in the development of sclerotic changes in FSGS.
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Affiliation(s)
- Yasuhiro Otaki
- Department of Cell Biology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Niigata, 951-8510, Japan
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Koop K, Eikmans M, Wehland M, Baelde H, Ijpelaar D, Kreutz R, Kawachi H, Kerjaschki D, de Heer E, Bruijn JA. Selective loss of podoplanin protein expression accompanies proteinuria and precedes alterations in podocyte morphology in a spontaneous proteinuric rat model. THE AMERICAN JOURNAL OF PATHOLOGY 2008; 173:315-26. [PMID: 18599604 DOI: 10.2353/ajpath.2008.080063] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
To evaluate changes during the development of proteinuria, podocyte morphology and protein expression were evaluated in spontaneously proteinuric, Dahl salt-sensitive (Dahl SS) rats. Dahl SS rats on a low-salt diet were compared with spontaneously hypertensive rats (SHR) at age 2, 4, 6, 8, and 10 weeks. Blood pressure, urinary protein excretion, urinary albumin excretion, and podocyte morphology were evaluated. In addition, the expression of 11 podocyte-related proteins was determined by analyzing protein and mRNA levels. In Dahl SS rats, proteinuria became evident around week 5, increasing thereafter. SHR rats remained non-proteinuric. Dahl SS rats showed widespread foot process effacement at 10 weeks. At < or =8 weeks, expression and distribution of the podocyte proteins was similar between the two strains, except for the protein podoplanin. At 4 weeks, podoplanin began decreasing in the glomeruli of Dahl SS rats in a focal and segmental fashion. Podoplanin loss increased progressively and correlated with albuminuria (r = 0.8, P < 0.001). Double labeling experiments revealed increased expression of the podocyte stress marker desmin in glomerular areas where podoplanin was lost. Dahl SS rats did not show podoplanin gene mutations or decreased mRNA expression. Thus, podocyte morphology and the expression and distribution of most podocyte-specific proteins were normal in young Dahl SS rats, despite marked proteinuria. Our study suggests that decreased expression of podoplanin plays a role in the decrease of glomerular permselectivity.
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Affiliation(s)
- Klaas Koop
- Department of Pathology, Leiden University Medical Center, Building 1, L1-Q, PO BOX 9600, 2300 RC Leiden, The Netherlands.
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Collino F, Bussolati B, Gerbaudo E, Marozio L, Pelissetto S, Benedetto C, Camussi G. Preeclamptic sera induce nephrin shedding from podocytes through endothelin-1 release by endothelial glomerular cells. Am J Physiol Renal Physiol 2008; 294:F1185-94. [PMID: 18287402 DOI: 10.1152/ajprenal.00442.2007] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
In preeclampsia (PE), proteinuria has been associated with a reduced expression of nephrin by podocytes. In the present study, we investigated in vitro on human cultured podocytes the mechanism responsible for nephrin loss in PE. Sera from patients with PE did not directly downregulate the expression of nephrin. In contrast, conditioned medium obtained from glomerular endothelial cells incubated with PE sera induced loss of nephrin and synaptopodin, but not of podocin, from podocytes. Nephrin loss was related to a rapid shedding of the protein from the cell surface due to cleavage of its extracellular domain by proteases and to cytoskeleton redistribution. The absence of nephrin mRNA downregulation together with nephrin reexpression within 24 h confirm that the loss of nephrin was not related to a reduced synthesis. Studies with an endothelin-1 (ET-1) receptor antagonist that abrogated the loss of nephrin triggered by glomerular endothelial conditioned medium of PE sera indicated that ET-1 was the main effector of nephrin loss. Indeed, ET-1 was synthesized and released from glomerular endothelial cells when incubated with PE sera, and recombinant ET-1 triggered nephrin shedding from podocytes. Moreover, VEGF blockade induced ET-1 release from endothelial cells, and in turn the conditioned medium obtained triggered nephrin loss. In conclusion, the present study identifies a potential mechanism of nephrin loss in PE that may link endothelial injury with enhanced glomerular permeability.
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Affiliation(s)
- Federica Collino
- Department of Internal Medicine, Research Centre for Experimental Medicine and Molecular Biotechnology Center, University of Torino, Torino, Italy
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Kato T, Mizuno S, Taketo MM, Kurosawa TM. The possible involvement of tensin2 in the expression and extension of nephrin by glomerular podocytes in mice. Biomed Res 2008; 29:279-87. [DOI: 10.2220/biomedres.29.279] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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50
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Abstract
Despite significant advances in our understanding of the molecular structure and composition of the glomerular filtration barrier, the mechanisms underlying the presence of excess protein in the urine (proteinuria) in acquired human kidney diseases remain elusive. In a study appearing in this issue of the JCI, Sever and associates use a combination of biochemical, genetic, and in vivo approaches in mice to demonstrate a pivotal role of cathepsin L and its substrate the GTPase dynamin, in the induction of proteinuria and associated foot process effacement in glomerular podocytes (see the related article beginning on page 2095).
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Affiliation(s)
- Pierre Ronco
- INSERM UMR S 702, University Pierre et Marie Curie, and Department of Nephrology and Dialysis, Tenon Hospital, Paris, France.
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