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Li T, Sun W, Zhu S, He C, Chang T, Zhang J, Chen Y. T-2 Toxin-Mediated β-Arrestin-1 O-GlcNAcylation Exacerbates Glomerular Podocyte Injury via Regulating Histone Acetylation. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2307648. [PMID: 38083975 PMCID: PMC10870076 DOI: 10.1002/advs.202307648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 11/22/2023] [Indexed: 02/17/2024]
Abstract
T-2 toxin causes renal dysfunction with proteinuria and glomerular podocyte damage. This work explores the role of metabolic disorder/reprogramming-mediated epigenetic modification in the progression of T-2 toxin-stimulated podocyte injury. A metabolomics experiment is performed to assess metabolic responses to T-2 toxin infection in human podocytes. Roles of protein O-linked-N-acetylglucosaminylation (O-GlcNAcylation) in regulating T-2 toxin-stimulated podocyte injury in mouse and podocyte models are assessed. O-GlcNAc target proteins are recognized by mass spectrometry and co-immunoprecipitation experiments. Moreover, histone acetylation and autophagy levels are measured. T-2 toxin infection upregulates glucose transporter type 1 (GLUT1) expression and enhances hexosamine biosynthetic pathway in glomerular podocytes, resulting in a significant increase in β-arrestin-1 O-GlcNAcylation. Decreasing β-arrestin-1 or O-GlcNAc transferase (OGT) effectively prevents T-2 toxin-induced renal dysfunction and podocyte injury. Mechanistically, O-GlcNAcylation of β-arrestin-1 stabilizes β-arrestin-1 to activate the mammalian target of rapamycin (mTOR) pathway as well as to inhibit autophagy during podocyte injury by promoting H4K16 acetylation. To sum up, OGT-mediated β-arrestin-1 O-GlcNAcylation is a vital regulator in the development of T-2 toxin-stimulated podocyte injury via activating the mTOR pathway to suppress autophagy. Targeting β-arrestin-1 or OGT can be a potential therapy for T-2 toxin infection-associated glomerular injury, especially podocyte injury.
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Affiliation(s)
- Tushuai Li
- School of Biology and Food EngineeringChangshu Institute of TechnologySuzhou215500P.R. China
- Wuxi School of MedicineJiangnan UniversityWuxi214013P.R. China
- Wuxi Translational Medicine Research Center and Jiangsu Translational Medicine Research Institute Wuxi BranchWuxi214013P.R. China
| | - Wenxue Sun
- Translational Pharmaceutical LaboratoryJining First People's HospitalShandong First Medical UniversityJining272000P.R. China
- Postdoctoral of Shandong University of Traditional Chinese MedicineJi'nan250355P.R. China
- Institute of Translational PharmacyJining Medical Research AcademyJining272000P.R. China
| | - Shenglong Zhu
- Wuxi School of MedicineJiangnan UniversityWuxi214013P.R. China
- Wuxi Translational Medicine Research Center and Jiangsu Translational Medicine Research Institute Wuxi BranchWuxi214013P.R. China
| | - Chengsheng He
- School of Biology and Food EngineeringChangshu Institute of TechnologySuzhou215500P.R. China
| | - Tong Chang
- School of Biology and Food EngineeringChangshu Institute of TechnologySuzhou215500P.R. China
| | - Jie Zhang
- School of Biology and Food EngineeringChangshu Institute of TechnologySuzhou215500P.R. China
| | - Yongquan Chen
- Wuxi School of MedicineJiangnan UniversityWuxi214013P.R. China
- Wuxi Translational Medicine Research Center and Jiangsu Translational Medicine Research Institute Wuxi BranchWuxi214013P.R. China
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Xi G, Lamba SA, Mysh M, Poulton JS. Oxidative Stress Contributes to Slit Diaphragm Defects Caused by Disruption of Endocytosis. Kidney Int Rep 2024; 9:451-463. [PMID: 38344712 PMCID: PMC10851022 DOI: 10.1016/j.ekir.2023.11.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 10/27/2023] [Accepted: 11/20/2023] [Indexed: 03/04/2024] Open
Abstract
Introduction Podocyte slit diaphragms are an important component of the glomerular filtration barrier. Podocyte injury frequently includes defects in slit diaphragms, and various mechanisms for these defects have been described, including altered endocytic trafficking of slit diaphragm proteins or oxidative stress. However, the potential relationship between endocytosis and oxidative stress in the context of slit diaphragm integrity has not been extensively considered. Methods To examine the potential relationships between endocytosis, oxidative stress, and slit diaphragm integrity, we induced genetic or pharmacological disruption of endocytosis in Drosophila nephrocytes (the insect orthologue of podocytes) and cultured human podocytes. We then employed immunofluorescence microscopy to analyze protein localization and levels, and to quantify signal from reactive oxygen species (ROS) dyes. Immunoprecipitation from podocyte cell lysates was used to examine effects on slit diaphragm protein complex formation (i.e., nephrin/podocin and nephrin/ZO-1). Results Disruption of endocytosis in nephrocytes and podocytes led to slit diaphragm defects, elevated levels of ROS (oxidative stress), and activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant pathway. In nephrocytes with defective endocytosis, perturbation of Nrf2 signaling exacerbated slit diaphragm defects. Conversely, overexpression of Nrf2 target genes catalase or glucose-6-phosphate dehydrogenase (G6PD) significantly ameliorated slit diaphragm defects caused by disruption of endocytosis. Conclusion Oxidative stress is an important consequence of defective endocytosis and contributes to the defects in slit diaphragm integrity associated with disruption of endocytic trafficking.
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Affiliation(s)
- Gang Xi
- UNC Kidney Center, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Sajan A. Lamba
- UNC Kidney Center, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Michael Mysh
- UNC Kidney Center, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - John S. Poulton
- UNC Kidney Center, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Singh RK, Kumar S, Kumar S, Shukla A, Kumar N, Patel AK, Yadav LK, Kaushalendra, Antiwal M, Acharya A. Potential implications of protein kinase Cα in pathophysiological conditions and therapeutic interventions. Life Sci 2023; 330:121999. [PMID: 37536614 DOI: 10.1016/j.lfs.2023.121999] [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: 03/23/2023] [Revised: 07/31/2023] [Accepted: 07/31/2023] [Indexed: 08/05/2023]
Abstract
PKCα is a molecule with many functions that play an important role in cell survival and death to maintain cellular homeostasis. Alteration in the normal functioning of PKCα is responsible for the complicated etiology of many pathologies, including cancer, cardiovascular diseases, kidney complications, neurodegenerative diseases, diabetics, and many others. Several studies have been carried out over the years on this kinase's function, and regulation in normal physiology and pathological conditions. A lot of data with antithetical results have therefore accumulated over time to create a complex framework of physiological implications connected to the PKCα function that needs comprehensive elucidation. In light of this information, we critically analyze the multiple roles played by PKCα in basic cellular processes and their molecular mechanism during various pathological conditions. This review further discusses the current approaches to manipulating PKCα signaling amplitude in the patient's favour and proposed PKCα as a therapeutic target to reverse pathological states.
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Affiliation(s)
- Rishi Kant Singh
- Lab of Hematopoiesis and Leukemia, KSBS, Indian Institute of Technology, Delhi, New Delhi 110016, India; Cancer Immunology Lab, Department of Zoology, Banaras Hindu University, Varanasi 221005, India
| | - Sanjay Kumar
- Cancer Immunology Lab, Department of Zoology, Banaras Hindu University, Varanasi 221005, India
| | - Sandeep Kumar
- Cancer Immunology Lab, Department of Zoology, Banaras Hindu University, Varanasi 221005, India
| | - Alok Shukla
- Cancer Immunology Lab, Department of Zoology, Banaras Hindu University, Varanasi 221005, India
| | - Naveen Kumar
- Cancer Immunology Lab, Department of Zoology, Banaras Hindu University, Varanasi 221005, India
| | - Anand Kumar Patel
- Cancer Immunology Lab, Department of Zoology, Banaras Hindu University, Varanasi 221005, India
| | - Lokesh Kumar Yadav
- Cancer Immunology Lab, Department of Zoology, Banaras Hindu University, Varanasi 221005, India
| | - Kaushalendra
- Department of Zoology, Pachhunga University College Campus, Mizoram University, Aizawl 796001, India
| | - Meera Antiwal
- Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India
| | - Arbind Acharya
- Cancer Immunology Lab, Department of Zoology, Banaras Hindu University, Varanasi 221005, India.
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Bouslama R, Dumont V, Lindfors S, Paavolainen L, Tienari J, Nisen H, Mirtti T, Saleem MA, Gordin D, Groop PH, Suetsugu S, Lehtonen S. Phosphorylation of PACSIN2 at S313 Regulates Podocyte Architecture in Coordination with N-WASP. Cells 2023; 12:1487. [PMID: 37296607 PMCID: PMC10252800 DOI: 10.3390/cells12111487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 05/16/2023] [Accepted: 05/23/2023] [Indexed: 06/12/2023] Open
Abstract
Changes in the dynamic architecture of podocytes, the glomerular epithelial cells, lead to kidney dysfunction. Previous studies on protein kinase C and casein kinase 2 substrates in neurons 2 (PACSIN2), a known regulator of endocytosis and cytoskeletal organization, reveal a connection between PACSIN2 and kidney pathogenesis. Here, we show that the phosphorylation of PACSIN2 at serine 313 (S313) is increased in the glomeruli of rats with diabetic kidney disease. We found that phosphorylation at S313 is associated with kidney dysfunction and increased free fatty acids rather than with high glucose and diabetes alone. Phosphorylation of PACSIN2 emerged as a dynamic process that fine-tunes cell morphology and cytoskeletal arrangement, in cooperation with the regulator of the actin cytoskeleton, Neural Wiskott-Aldrich syndrome protein (N-WASP). PACSIN2 phosphorylation decreased N-WASP degradation while N-WASP inhibition triggered PACSIN2 phosphorylation at S313. Functionally, pS313-PACSIN2 regulated actin cytoskeleton rearrangement depending on the type of cell injury and the signaling pathways involved. Collectively, this study indicates that N-WASP induces phosphorylation of PACSIN2 at S313, which serves as a mechanism whereby cells regulate active actin-related processes. The dynamic phosphorylation of S313 is needed to regulate cytoskeletal reorganization.
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Affiliation(s)
- Rim Bouslama
- Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
| | - Vincent Dumont
- Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
| | - Sonja Lindfors
- Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
| | - Lassi Paavolainen
- Institute for Molecular Medicine Finland (FIMM), Helsinki Institute of Life Science (HiLIFE), University of Helsinki, 00290 Helsinki, Finland
| | - Jukka Tienari
- Department of Pathology, University of Helsinki, Helsinki, and Helsinki University Hospital, 05850 Hyvinkää, Finland
| | - Harry Nisen
- Department of Urology, Helsinki University Hospital, 00029 HUS, Finland
| | - Tuomas Mirtti
- Department of Pathology, Helsinki University Hospital, 00290 Helsinki, Finland
- Research Program in Systems Oncology, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
| | - Moin A. Saleem
- Children’s Renal Unit, Bristol Medical School, University of Bristol, Bristol BS8 1TS, UK
| | - Daniel Gordin
- Minerva Foundation Institute for Medical Research, 00290 Helsinki, Finland
- Abdominal Center, Nephrology, University of Helsinki and Helsinki University Hospital, 00290 Helsinki, Finland
- Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
| | - Per-Henrik Groop
- Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland
- Department of Nephrology, University of Helsinki, Helsinki, and Helsinki University Hospital, 00290 Helsinki, Finland
- Department of Diabetes, Central Clinical School, Monash University, Melbourne, VIC 3800, Australia
| | - Shiro Suetsugu
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma 630-0192, Japan
- Data Science Center, Nara Institute of Science and Technology, Ikoma 630-0192, Japan
- Center for Digital Green-Innovation, Nara Institute of Science and Technology, Ikoma 630-0192, Japan
| | - Sanna Lehtonen
- Research Program for Clinical and Molecular Metabolism, Faculty of Medicine, University of Helsinki, 00290 Helsinki, Finland
- Department of Pathology, University of Helsinki, 00290 Helsinki, Finland
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Sun H, Weidner J, Allamargot C, Piper RC, Misurac J, Nester C. Dynein-Mediated Trafficking: A New Mechanism of Diabetic Podocytopathy. KIDNEY360 2023; 4:162-176. [PMID: 36821608 PMCID: PMC10103215 DOI: 10.34067/kid.0006852022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 11/21/2022] [Indexed: 12/12/2022]
Abstract
Key Points The expression of dynein is increased in human and rodent models of diabetic nephropathy (DN), eliciting a new dynein-driven pathogenesis. Uncontrolled dynein impairs the molecular sieve of kidney by remodeling the postendocytic triage and homeostasis of nephrin. The delineation of the dynein-driven pathogenesis promises a broad spectrum of new therapeutic targets for human DN. Background Diabetic nephropathy (DN) is characterized by increased endocytosis and degradation of nephrin, a protein that comprises the molecular sieve of the glomerular filtration barrier. While nephrin internalization has been found activated in diabetes-stressed podocytes, the postinternalization trafficking steps that lead to the eventual depletion of nephrin and the development of DN are unclear. Our work on an inherited podocytopathy uncovered that dysregulated dynein could compromise nephrin trafficking, leading us to test whether and how dynein mediates the pathogenesis of DN. Methods We analyzed the transcription of dynein components in public DN databases, using the Nephroseq platform. We verified altered dynein transcription in diabetic podocytopathy by quantitative PCR. Dynein-mediated trafficking and degradation of nephrin was investigated using an in vitro nephrin trafficking model and was demonstrated in a mouse model with streptozotocin (STZ)-induced DN and in human kidney biopsy sections. Results Our transcription analysis revealed increased expression of dynein in human DN and diabetic mouse kidney, correlated significantly with the severity of hyperglycemia and DN. In diabetic podocytopathy, we observed that dynein-mediated postendocytic sorting of nephrin was upregulated, resulting in accelerated nephrin degradation and disrupted nephrin recycling. In hyperglycemia-stressed podocytes, Dynll1 , one of the most upregulated dynein components, is required for the recruitment of dynein complex that mediates the postendocytic sorting of nephrin. This was corroborated by observing enhanced Dynll1-nephrin colocalization in podocytes of diabetic patients, as well as dynein-mediated trafficking and degradation of nephrin in STZ-induced diabetic mice with hyperglycemia. Knockdown of Dynll1 attenuated lysosomal degradation of nephrin and promoted its recycling, suggesting the essential role of Dynll1 in dynein-mediated mistrafficking. Conclusions Our studies show that hyperglycemia stimulates dynein-mediated trafficking of nephrin to lysosomes by inducing its expression. The decoding of dynein-driven pathogenesis of diabetic podocytopathy offers a spectrum of new dynein-related therapeutic targets for DN.
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Affiliation(s)
- Hua Sun
- Division of Nephrology, Stead Family Department of Pediatrics, The University of Iowa, Iowa City, Iowa
- Carver College of Medicine, The University of Iowa, Iowa City, Iowa
| | - Jillian Weidner
- Division of Nephrology, Stead Family Department of Pediatrics, The University of Iowa, Iowa City, Iowa
- Carver College of Medicine, The University of Iowa, Iowa City, Iowa
| | - Chantal Allamargot
- Central Microscopy Research Facility, The University of Iowa, Iowa City, Iowa
| | - Robert C. Piper
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, The University of Iowa, Iowa City, Iowa
| | - Jason Misurac
- Division of Nephrology, Stead Family Department of Pediatrics, The University of Iowa, Iowa City, Iowa
- Carver College of Medicine, The University of Iowa, Iowa City, Iowa
| | - Carla Nester
- Division of Nephrology, Stead Family Department of Pediatrics, The University of Iowa, Iowa City, Iowa
- Carver College of Medicine, The University of Iowa, Iowa City, Iowa
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The Role of Diacylglycerol Kinase in the Amelioration of Diabetic Nephropathy. Molecules 2022; 27:molecules27206784. [PMID: 36296376 PMCID: PMC9607625 DOI: 10.3390/molecules27206784] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 10/05/2022] [Accepted: 10/07/2022] [Indexed: 12/02/2022] Open
Abstract
The drastic increase in the number of patients with diabetes and its complications is a global issue. Diabetic nephropathy, the leading cause of chronic kidney disease, significantly affects patients’ quality of life and medical expenses. Furthermore, there are limited drugs for treating diabetic nephropathy patients. Impaired lipid signaling, especially abnormal protein kinase C (PKC) activation by de novo-synthesized diacylglycerol (DG) under high blood glucose, is one of the causes of diabetic nephropathy. DG kinase (DGK) is an enzyme that phosphorylates DG and generates phosphatidic acid, i.e., DGK can inhibit PKC activation under diabetic conditions. Indeed, it has been proven that DGK activation ameliorates diabetic nephropathy. In this review, we summarize the involvement of PKC and DGK in diabetic nephropathy as therapeutic targets, and its mechanisms, by referring to our recent study.
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Navarro-Betancourt JR, Cybulsky AV. The IRE1α pathway in glomerular diseases: The unfolded protein response and beyond. FRONTIERS IN MOLECULAR MEDICINE 2022; 2:971247. [PMID: 39086958 PMCID: PMC11285563 DOI: 10.3389/fmmed.2022.971247] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 09/07/2022] [Indexed: 08/02/2024]
Abstract
Endoplasmic reticulum (ER) function is vital for protein homeostasis ("proteostasis"). Protein misfolding in the ER of podocytes (glomerular visceral epithelial cells) is an important contributor to the pathogenesis of human glomerular diseases. ER protein misfolding causes ER stress and activates a compensatory signaling network called the unfolded protein response (UPR). Disruption of the UPR, in particular deletion of the UPR transducer, inositol-requiring enzyme 1α (IRE1α) in mouse podocytes leads to podocyte injury and albuminuria in aging, and exacerbates injury in glomerulonephritis. The UPR may interact in a coordinated manner with autophagy to relieve protein misfolding and its consequences. Recent studies have identified novel downstream targets of IRE1α, which provide new mechanistic insights into proteostatic pathways. Novel pathways of IRE1α signaling involve reticulophagy, mitochondria, metabolism, vesicular trafficking, microRNAs, and others. Mechanism-based therapies for glomerulopathies are limited, and development of non-invasive ER stress biomarkers, as well as targeting ER stress with pharmacological compounds may represent a therapeutic opportunity for preventing or attenuating progression of chronic kidney disease.
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Affiliation(s)
| | - Andrey V. Cybulsky
- Department of Medicine, McGill University Health Centre Research Institute, McGill University, Montreal, QC, Canada
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8
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Grochowalska K, Pikul P, Piwkowska A. Insights into the regulation of podocyte and glomerular function by lactate and its metabolic sensor G-protein-coupled receptor 81. J Cell Physiol 2022; 237:4097-4111. [PMID: 36084306 DOI: 10.1002/jcp.30874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 08/04/2022] [Accepted: 08/25/2022] [Indexed: 11/10/2022]
Abstract
Podocytes and their foot processes are an important cellular layer of the renal filtration barrier that is involved in regulating glomerular permeability. Disturbances of podocyte function play a central role in the development of proteinuria in diabetic nephropathy. The retraction and effacement of podocyte foot processes that form slit diaphragms are a common feature of proteinuria. Correlations between the retraction of foot processes and the development of proteinuria are not well understood. Unraveling peculiarities of podocyte energy metabolism notably under diabetic conditions will provide insights into the pathogenesis of diabetic nephropathy. Intracellular metabolism in the cortical area of podocytes is regulated by glycolysis, whereas energy balance in the central area is controlled by oxidative phosphorylation and glycolysis. High glucose concentrations were recently reported to force podocytes to switch from mitochondrial oxidative phosphorylation to glycolysis, resulting in lactic acidosis. In this review, we hypothesize that the lactate receptor G-protein-coupled receptor 81 (also known as hydroxycarboxylic acid receptor 81) may contribute to the control of podocyte function in both health and disease.
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Affiliation(s)
- Klaudia Grochowalska
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Gdansk, Poland
| | - Piotr Pikul
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Gdansk, Poland
| | - Agnieszka Piwkowska
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Gdansk, Poland.,Department of Molecular Biotechnology, Faculty of Chemistry, University of Gdansk, Gdansk, Poland
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9
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Kotewicz M, Krauze-Baranowska M, Daca A, Płoska A, Godlewska S, Kalinowski L, Lewko B. Urolithins Modulate the Viability, Autophagy, Apoptosis, and Nephrin Turnover in Podocytes Exposed to High Glucose. Cells 2022; 11:cells11162471. [PMID: 36010548 PMCID: PMC9406555 DOI: 10.3390/cells11162471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/29/2022] [Accepted: 08/06/2022] [Indexed: 12/02/2022] Open
Abstract
Urolithins are bioactive compounds generated in human and animal intestines because of the bacterial metabolism of dietary ellagitannins (and their constituent, ellagic acid). Due to their multidirectional effects, including anti-inflammatory, antioxidant, anti-cancer, neuroprotective, and antiglycative properties, urolithins are potential novel therapeutic agents. In this study, while considering the future possibility of using urolithins to improve podocyte function in diabetes, we assessed the results of exposing mouse podocytes cultured in normal (NG, 5.5 mM) and high (HG, 25 mM) glucose concentrations to urolithin A (UA) and urolithin B (UB). Podocytes metabolized UA to form glucuronides in a time-dependent manner; however, in HG conditions, the metabolism was lower than in NG conditions. In HG milieu, UA improved podocyte viability more efficiently than UB and reduced the reactive oxygen species level. Both types of urolithins showed cytotoxic activity at high (100 µM) concentration. The UA upregulated total and surface nephrin expression, which was paralleled by enhanced nephrin internalization. Regulation of nephrin turnover was independent of ambient glucose concentration. We conclude that UA affects podocytes in different metabolic and functional aspects. With respect to its pro-survival effects in HG-induced toxicity, UA could be considered as a potent therapeutic candidate against diabetic podocytopathy.
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Affiliation(s)
- Milena Kotewicz
- Department of Pharmaceutical Pathophysiology, Faculty of Pharmacy, Medical University of Gdansk, 80-210 Gdansk, Poland
| | | | - Agnieszka Daca
- Department of Pathology and Experimental Rheumatology, Faculty of Medicine, Medical University of Gdansk, 80-210 Gdansk, Poland
| | - Agata Płoska
- Department of Medical Laboratory Diagnostics-Fahrenheit Biobank BBMRI, Faculty of Pharmacy, Medical University of Gdansk, 80-210 Gdansk, Poland
| | - Sylwia Godlewska
- Department of Pharmacognosy, Faculty of Pharmacy, Medical University of Gdansk, 80-210 Gdansk, Poland
| | - Leszek Kalinowski
- Department of Medical Laboratory Diagnostics-Fahrenheit Biobank BBMRI, Faculty of Pharmacy, Medical University of Gdansk, 80-210 Gdansk, Poland
- BioTechMed Centre, Department of Mechanics of Materials and Structures, Gdansk University of Technology, 80-233 Gdansk, Poland
| | - Barbara Lewko
- Department of Pharmaceutical Pathophysiology, Faculty of Pharmacy, Medical University of Gdansk, 80-210 Gdansk, Poland
- Correspondence:
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Lang K, Milosavljevic J, Heinkele H, Chen M, Gerstner L, Spitz D, Kayser S, Helmstädter M, Walz G, Köttgen M, Spracklen A, Poulton J, Hermle T. Selective endocytosis controls slit diaphragm maintenance and dynamics in Drosophila nephrocytes. eLife 2022; 11:79037. [PMID: 35876643 PMCID: PMC9355562 DOI: 10.7554/elife.79037] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 07/24/2022] [Indexed: 11/28/2022] Open
Abstract
The kidneys generate about 180 l of primary urine per day by filtration of plasma. An essential part of the filtration barrier is the slit diaphragm, a multiprotein complex containing nephrin as major component. Filter dysfunction typically manifests with proteinuria and mutations in endocytosis regulating genes were discovered as causes of proteinuria. However, it is unclear how endocytosis regulates the slit diaphragm and how the filtration barrier is maintained without either protein leakage or filter clogging. Here, we study nephrin dynamics in podocyte-like nephrocytes of Drosophila and show that selective endocytosis either by dynamin- or flotillin-mediated pathways regulates a stable yet highly dynamic architecture. Short-term manipulation of endocytic functions indicates that dynamin-mediated endocytosis of ectopic nephrin restricts slit diaphragm formation spatially while flotillin-mediated turnover of nephrin within the slit diaphragm is needed to maintain filter permeability by shedding of molecules bound to nephrin in endosomes. Since slit diaphragms cannot be studied in vitro and are poorly accessible in mouse models, this is the first analysis of their dynamics within the slit diaphragm multiprotein complex. Identification of the mechanisms of slit diaphragm maintenance will help to develop novel therapies for proteinuric renal diseases that are frequently limited to symptomatic treatment.
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Affiliation(s)
- Konrad Lang
- Department of Medicine, University of Freiburg, Freiburg, Germany
| | | | - Helena Heinkele
- Department of Medicine, University of Freiburg, Freiburg, Germany
| | - Mengmeng Chen
- Department of Medicine, University of Freiburg, Freiburg, Germany
| | - Lea Gerstner
- Department of Medicine, University of Freiburg, Freiburg, Germany
| | - Dominik Spitz
- Department of Medicine, University of Freiburg, Freiburg, Germany
| | - Severine Kayser
- Department of Medicine, University of Freiburg, Freiburg, Germany
| | | | - Gerd Walz
- Department of Medicine, University of Freiburg, Freiburg, Germany
| | - Michael Köttgen
- Department of Medicine, University of Freiburg, Freiburg, Germany
| | - Andrew Spracklen
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - John Poulton
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Tobias Hermle
- Department of Medicine, University of Freiburg, Freiburg, Germany
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11
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Woznowski MP, Potthoff SA, Königshausen E, Haase R, Hoch H, Meyer-Schwesinger C, Wiech T, Stegbauer J, Rump LC, Sellin L, Quack I. Inhibition of p38 MAPK decreases hyperglycemia-induced nephrin endocytosis and attenuates albuminuria. J Mol Med (Berl) 2022; 100:781-795. [PMID: 35451598 PMCID: PMC9110524 DOI: 10.1007/s00109-022-02184-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 01/20/2022] [Accepted: 02/22/2022] [Indexed: 11/26/2022]
Abstract
Abstract Chronic hyperglycemia, as in diabetes mellitus, may cause glomerular damage with microalbuminuria as an early sign. Noteworthy, even acute hyperglycemia can increase glomerular permeability before structural damage of the glomerular filter can be detected. Despite intensive research, specific antiproteinuric therapy is not available so far. Thus, a deeper understanding of the molecular mechanisms of albuminuria is desirable. P38 MAPK signaling is involved in the development of hyperglycemia-induced albuminuria. However, the mechanism of increased p38 MAPK activity leading to increased permeability and albuminuria remained unclear. Recently, we demonstrated that acute hyperglycemia triggers endocytosis of nephrin, the key molecule of the slit diaphragm, and induces albuminuria. Here, we identify p38 MAPK as a pivotal regulator of hyperglycemia-induced nephrin endocytosis. Activated p38 MAPK phosphorylates the nephrin c-terminus at serine 1146, facilitating the interaction of PKCα with nephrin. PKCα phosphorylates nephrin at threonine residues 1120 and 1125, mediating the binding of β-arrestin2 to nephrin. β-arrestin2 triggers endocytosis of nephrin by coupling it to the endocytic machinery, leading to increased glomerular permeability. Pharmacological inhibition of p38 MAPK preserves nephrin surface expression and significantly attenuates albuminuria. Key messages Acute hyperglycemia triggers endocytosis of nephrin. Activated p38 MAPK phosphorylates the nephrin c-terminus at serine 1146, facilitating the interaction of PKCα with nephrin. PKCα phosphorylates nephrin at threonine residues 1120 and 1125, mediating the binding of β-arrestin2 to nephrin. β-arrestin2 triggers endocytosis of nephrin by coupling it to the endocytic machinery, leading to a leaky glomerular filter. Pharmacological inhibition of p38 MAPK preserves nephrin surface expression and significantly attenuates albuminuria under hyperglycemic conditions.
Supplementary Information The online version contains supplementary material available at 10.1007/s00109-022-02184-5.
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Affiliation(s)
| | | | - Eva Königshausen
- Department of Nephrology, Medical Faculty, Heinrich-Heine University, 40225, Düsseldorf, Germany
| | - Raphael Haase
- Department of Nephrology, Medical Faculty, Heinrich-Heine University, 40225, Düsseldorf, Germany
| | - Henning Hoch
- Department of Nephrology, Medical Faculty, Heinrich-Heine University, 40225, Düsseldorf, Germany
| | - Catherine Meyer-Schwesinger
- Institute of Cellular and Integrative Physiology, University Clinic Hamburg-Eppendorf, 20246, Hamburg, Germany
| | - Thorsten Wiech
- Institute of Pathology, Nephropathology Section, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany
| | - Johannes Stegbauer
- Department of Nephrology, Medical Faculty, Heinrich-Heine University, 40225, Düsseldorf, Germany
| | - Lars Christian Rump
- Department of Nephrology, Medical Faculty, Heinrich-Heine University, 40225, Düsseldorf, Germany
| | - Lorenz Sellin
- Department of Nephrology, Medical Faculty, Heinrich-Heine University, 40225, Düsseldorf, Germany
| | - Ivo Quack
- Emergency Department, Klinikum Konstanz, 78464, Konstanz, Germany
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12
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Lane BM, Chryst-Stangl M, Wu G, Shalaby M, El Desoky S, Middleton CC, Huggins K, Sood A, Ochoa A, Malone AF, Vancini R, Miller SE, Hall G, Kim SY, Howell DN, Kari JA, Gbadegesin R. Steroid-sensitive nephrotic syndrome candidate gene CLVS1 regulates podocyte oxidative stress and endocytosis. JCI Insight 2022; 7:e152102. [PMID: 34874915 PMCID: PMC9018043 DOI: 10.1172/jci.insight.152102] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 12/01/2021] [Indexed: 11/17/2022] Open
Abstract
We performed next-generation sequencing in patients with familial steroid-sensitive nephrotic syndrome (SSNS) and identified a homozygous segregating variant (p.H310Y) in the gene encoding clavesin-1 (CLVS1) in a consanguineous family with 3 affected individuals. Knockdown of the clavesin gene in zebrafish (clvs2) produced edema phenotypes due to disruption of podocyte structure and loss of glomerular filtration barrier integrity that could be rescued by WT CLVS1 but not the p.H310Y variant. Analysis of cultured human podocytes with CRISPR/Cas9-mediated CLVS1 knockout or homozygous H310Y knockin revealed deficits in clathrin-mediated endocytosis and increased susceptibility to apoptosis that could be rescued with corticosteroid treatment, mimicking the steroid responsiveness observed in patients with SSNS. The p.H310Y variant also disrupted binding of clavesin-1 to α-tocopherol transfer protein, resulting in increased reactive oxygen species (ROS) accumulation in CLVS1-deficient podocytes. Treatment of CLVS1-knockout or homozygous H310Y-knockin podocytes with pharmacological ROS inhibitors restored viability to control levels. Taken together, these data identify CLVS1 as a candidate gene for SSNS, provide insight into therapeutic effects of corticosteroids on podocyte cellular dynamics, and add to the growing evidence of the importance of endocytosis and oxidative stress regulation to podocyte function.
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Affiliation(s)
- Brandon M. Lane
- Department of Pediatrics, Division of Nephrology, and Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, North Carolina, USA
| | - Megan Chryst-Stangl
- Department of Pediatrics, Division of Nephrology, and Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, North Carolina, USA
| | - Guanghong Wu
- Department of Pediatrics, Division of Nephrology, and Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, North Carolina, USA
| | - Mohamed Shalaby
- Pediatric Department, Pediatric Nephrology Center of Excellence, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Sherif El Desoky
- Pediatric Department, Pediatric Nephrology Center of Excellence, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Claire C. Middleton
- Department of Pediatrics, Division of Nephrology, and Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, North Carolina, USA
| | - Kinsie Huggins
- Department of Pediatrics, Division of Nephrology, and Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, North Carolina, USA
| | - Amika Sood
- Department of Biostatistics and Bioinformatics and Duke Center for Statistical Genetics and Genomics, Duke University, Durham, North Carolina, USA
| | - Alejandro Ochoa
- Department of Biostatistics and Bioinformatics and Duke Center for Statistical Genetics and Genomics, Duke University, Durham, North Carolina, USA
| | - Andrew F. Malone
- Department of Medicine, Division of Nephrology, Washington University School of Medicine in St. Louis, St. Louis, Missouri, USA
| | | | | | - Gentzon Hall
- Department of Pediatrics, Division of Nephrology, and Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Division of Nephrology; and
| | - So Young Kim
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, USA
| | | | - Jameela A. Kari
- Pediatric Department, Pediatric Nephrology Center of Excellence, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Rasheed Gbadegesin
- Department of Pediatrics, Division of Nephrology, and Duke Molecular Physiology Institute, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Division of Nephrology; and
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13
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Dong QQ, Li ZF, Zhang H, Shu HP, Tu YC, Liao QQ, Yao LJ. Serum and Glucocorticoid-Inducible Kinase 3/Nedd4-2 Signaling Pathway Participates in Podocyte Injury by Regulating the Stability of Nephrin. Front Physiol 2022; 12:810473. [PMID: 35126185 PMCID: PMC8811367 DOI: 10.3389/fphys.2021.810473] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 12/13/2021] [Indexed: 11/26/2022] Open
Abstract
Serum and glucocorticoid-inducible kinase 3 (SGK3) is involved in maintaining podocyte function by regulating the protein levels of podocin and CD2-associated protein. Nephrin is also one of the slit diaphragm proteins of podocytes, but whether SGK3 participates in podocyte injury by regulating the levels of nephrin remains unclear. In this study, we focused on whether SGK3 affects nephrin levels and the mechanisms involved in the same. In the kidneys of adriamycin (ADR)-induced podocyte injury mouse model, the protein levels of SGK3 and nephrin were significantly decreased. Furthermore, the expression of SGK3 was negatively correlated with the output of proteinuria, and positively correlated with the levels of nephrin. In ADR-treated conditionally immortalized mouse podocyte cells (MPCs), the protein levels of nephrin and SGK3 were inhibited, while the constitutive expression of SGK3 reversed the ADR-induced decline in nephrin protein levels. Furthermore, ADR treatment or SGK3 inactivation enhanced the ubiquitin-proteasome degradation of nephrin in MPCs, and dramatically activated downstream effector proteins of SGK3, neural precursor cells expressing developmentally downregulated protein 4 subtype 2 (Nedd4-2) and glycogen synthase kinase-3 β (GSK3β). Similarly, Nedd4-2 or GSK3β overexpression resulted in increased activity of Nedd4-2 or GSK3β, and significantly downregulated nephrin levels. Interestingly, ubiquitin-mediated protein degradation of nephrin was regulated by Nedd4-2, rather than by GSK3β. In summary, SGK3 inactivation downregulated the levels of nephrin by increasing Nedd4-2 and GSK3β activity in ADR-induced podocyte injury model; in particular, the SGK3/Nedd4-2 signaling pathway was found to be involved in ubiquitin-mediated proteasome degradation of nephrin.
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Affiliation(s)
- Qing-Qing Dong
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zi-Fang Li
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Blood Purification Center, Hubei No. 3 People’ Hospital of Jianghan University, Wuhan, China
| | - Hui Zhang
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hua-Pan Shu
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yu-Chi Tu
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qian-Qian Liao
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Li-Jun Yao
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- *Correspondence: Li-Jun Yao,
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14
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Abstract
Renal injury resulting from obesity is a growing concern caused by the global obesity epidemic. We discuss the glomerular structure, obesity-related glomerular changes, and diagnostic pathologic criteria for obesity-related glomerulopathy. The three main hypothesized mechanisms of podocyte injury are mechanical stress on the podocytes, metabolic derangement, and genetic/molecular factors. Weight loss, renin-angiotensin-aldosterone system inhibitors, and improved insulin resistance may slow the progression. A more comprehensive understanding of obesity-related glomerulopathy will help in developing more effective therapies.
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Affiliation(s)
- Gabriel Giannini
- Department of Pathology, Johns Hopkins School of Medicine, Baltimore, MD
| | - Jeffrey B Kopp
- Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Avi Z Rosenberg
- Department of Pathology, Johns Hopkins School of Medicine, Baltimore, MD; Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD.
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15
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Du JJ, Sun JC, Li N, Li XQ, Sun WY, Wei W. β-Arrestin2 deficiency attenuates oxidative stress in mouse hepatic fibrosis through modulation of NOX4. Acta Pharmacol Sin 2021; 42:1090-1100. [PMID: 33116250 PMCID: PMC8209231 DOI: 10.1038/s41401-020-00545-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 09/21/2020] [Indexed: 02/06/2023] Open
Abstract
Hepatic fibrosis is a disease characterized by excessive deposition of extracellular matrix (ECM) in the liver. Activation of hepatic stellate cells (HSCs) is responsible for most of ECM production. Oxidative stress and reactive oxygen species (ROS) may be important factors leading to liver fibrosis. NADPH oxidase 4 (NOX4) is the main source of ROS in hepatic fibrosis, but the mechanism by which NOX4 regulates oxidative stress is not fully understood. β-Arrestin2 is a multifunctional scaffold protein that regulates receptor endocytosis, signaling and trafficking. In this study, we investigated whether β-arrestin2 regulated oxidative stress in hepatic fibrosis. Both β-arrestin2 knockout (Arrb2 KO) mice and wild-type mice were intraperitoneally injected with carbon tetrachloride (CCl4) to induce hepatic fibrosis. Arrb2 KO mice showed significantly attenuated liver fibrosis, decreased ROS levels and NOX4 expression, and reduced collagen levels in their livers. In vitro, NOX4 knockdown significantly inhibited ROS production, and decreased expression of alpha-smooth muscle actin in angiotensin II-stimulated human HSC cell line LX-2. Through overexpression or depletion of β-arrestin2 in LX-2 cells, we revealed that decreased β-arrestin2 inhibited ROS levels and NOX4 expression, and reduced collagen production; it also inhibited activation of ERK and JNK signaling pathways. These results demonstrate that β-arrestin2 deficiency protects against liver fibrosis by downregulating ROS production through NOX4. This effect appears to be mediated by ERK and JNK signaling pathways. Thus, targeted inhibition of β-arrestin2 might reduce oxidative stress and inhibit the progression of liver fibrosis.
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Affiliation(s)
- Jia-Jia Du
- Institute of Clinical Pharmacology, Anhui Medical University, Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Hefei, 230032, China
| | - Jia-Chang Sun
- Institute of Clinical Pharmacology, Anhui Medical University, Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Hefei, 230032, China
| | - Nan Li
- Institute of Clinical Pharmacology, Anhui Medical University, Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Hefei, 230032, China
| | - Xiu-Qin Li
- Institute of Clinical Pharmacology, Anhui Medical University, Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Hefei, 230032, China
| | - Wu-Yi Sun
- Institute of Clinical Pharmacology, Anhui Medical University, Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Hefei, 230032, China.
| | - Wei Wei
- Institute of Clinical Pharmacology, Anhui Medical University, Key Laboratory of Anti-inflammatory and Immune Medicine, Ministry of Education, Anhui Collaborative Innovation Center of Anti-inflammatory and Immune Medicine, Hefei, 230032, China.
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16
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Imeri F, Stepanovska Tanturovska B, Schwalm S, Saha S, Zeng-Brouwers J, Pavenstädt H, Pfeilschifter J, Schaefer L, Huwiler A. Loss of sphingosine kinase 2 enhances Wilm's tumor suppressor gene 1 and nephrin expression in podocytes and protects from streptozotocin-induced podocytopathy and albuminuria in mice. Matrix Biol 2021; 98:32-48. [PMID: 34015468 DOI: 10.1016/j.matbio.2021.05.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 05/10/2021] [Accepted: 05/10/2021] [Indexed: 12/11/2022]
Abstract
The sphingosine 1-phosphate (S1P) is a bioactive sphingolipid that is now appreciated as key regulatory factor for various cellular functions in the kidney, including matrix remodeling. It is generated by two sphingosine kinases (Sphk), Sphk1 and Sphk2, which are ubiquitously expressed, but have distinct enzymatic activities and subcellular localizations. In this study, we have investigated the role of Sphk2 in podocyte function and its contribution to diabetic nephropathy. We show that streptozotocin (STZ)-induced nephropathy and albuminuria in mice is prevented by genetic depletion of Sphk2. This protection correlated with an increased protein expression of the transcription factor Wilm's tumor suppressor gene 1 (WT1) and its target gene nephrin, and a reduced macrophage infiltration in immunohistochemical renal sections of STZ-treated Sphk2-/- mice compared to STZ-treated wildtype mice. To investigate changes on the cellular level, we used an immortalized human podocyte cell line and generated a stable knockdown of Sphk2 (Sphk2-kd) by a lentiviral transduction method. These Sphk2-kd cells accumulated sphingosine as a consequence of the knockdown, and showed enhanced nephrin and WT1 mRNA and protein expressions similar to the finding in Sphk2 knockout mice. Treatment of wildtype podocytes with the highly selective Sphk2 inhibitor SLM6031434 caused a similar upregulation of nephrin and WT1 expression. Furthermore, exposing cells to the profibrotic mediator transforming growth factor β (TGFβ) resulted on the one side in reduced nephrin and WT1 expression, but on the other side, in upregulation of various profibrotic marker proteins, including connective tissue growth factor (CTGF), fibronectin (FN) and plasminogen activator inhibitor (PAI) 1. All these effects were reverted by Sphk2-kd and SLM6031434. Mechanistically, the protection by Sphk2-kd may depend on accumulated sphingosine and inhibited PKC activity, since treatment of cells with exogenous sphingosine not only reduced the phosphorylation pattern of PKC substrates, but also increased WT1 protein expression. Moreover, the selective stable knockdown of PKCδ increased WT1 expression, suggesting the involvement of this PKC isoenzyme in WT1 regulation. The glucocorticoid dexamethasone, which is a treatment option in many glomerular diseases and is known to mediate a nephroprotection, not only downregulated Sphk2 and enhanced cellular sphingosine, but also enhanced WT1 and nephrin expressions, thus, suggesting that parts of the nephroprotective effect of dexamethasone is mediated by Sphk2 downregulation. Altogether, our data demonstrated that loss of Sphk2 is protective in diabetes-induced podocytopathy and can prevent proteinuria, which is a hallmark of many glomerular diseases. Thus, Sphk2 could serve as a new attractive pharmacological target to treat proteinuric kidney diseases.
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Affiliation(s)
- Faik Imeri
- Institute of Pharmacology, University of Bern, Inselspital, INO-F, Bern CH-3010, Switzerland
| | | | - Stephanie Schwalm
- Institute of Pharmacology and Toxicology, Goethe University, Frankfurt am Main D-60590, Germany
| | - Sarbari Saha
- Institute of Pharmacology and Toxicology, Goethe University, Frankfurt am Main D-60590, Germany
| | - Jinyang Zeng-Brouwers
- Institute of Pharmacology and Toxicology, Goethe University, Frankfurt am Main D-60590, Germany
| | - Herrmann Pavenstädt
- Medizinische Klinik D, University Hospital Münster, Münster D-48149, Germany
| | - Josef Pfeilschifter
- Institute of Pharmacology and Toxicology, Goethe University, Frankfurt am Main D-60590, Germany
| | - Liliana Schaefer
- Institute of Pharmacology and Toxicology, Goethe University, Frankfurt am Main D-60590, Germany.
| | - Andrea Huwiler
- Institute of Pharmacology, University of Bern, Inselspital, INO-F, Bern CH-3010, Switzerland.
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17
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Nephrotic syndrome in a 7-year-old girl with atypical hemolytic uremic syndrome relapse: Answers. Pediatr Nephrol 2021; 36:843-847. [PMID: 32666367 DOI: 10.1007/s00467-020-04700-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 06/24/2020] [Indexed: 10/23/2022]
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18
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Nakamichi R, Hayashi K, Itoh H. Effects of High Glucose and Lipotoxicity on Diabetic Podocytes. Nutrients 2021; 13:nu13010241. [PMID: 33467659 PMCID: PMC7830342 DOI: 10.3390/nu13010241] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/11/2020] [Accepted: 01/11/2021] [Indexed: 01/19/2023] Open
Abstract
Glomerular podocytes are highly differentiated cells that cover glomerular capillaries from the outside and have a characteristic morphology with numerous foot processes. The formation of slit membranes between the foot processes serves as a final filtration barrier for urine filtration from the blood. Podocyte damage causes disruption of the slit membrane, subsequent proteinuria and finally glomerulosclerosis, which is a common pathway in various types of chronic kidney disease (CKD). In recent years, there has been an increase in diabetes, due to rapid lifestyle changes, which is the main cause of CKD. Therefore, understanding the effect of diabetic status on podocytes is of great importance to establish a strategy for preventing CKD progression. In this review, we summarize altered glucose and lipid metabolism in diabetic podocytes and also discuss the reversibility of the changes in podocyte phenotype.
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Affiliation(s)
| | - Kaori Hayashi
- Correspondence: ; Tel.: +81-3-5363-3796; Fax: +81-3-3359-2745
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19
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Feng D. Phosphorylation of key podocyte proteins and the association with proteinuric kidney disease. Am J Physiol Renal Physiol 2020; 319:F284-F291. [PMID: 32686524 DOI: 10.1152/ajprenal.00002.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Podocyte dysfunction contributes to proteinuric chronic kidney disease. A number of key proteins are essential for podocyte function, including nephrin, podocin, CD2-associated protein (CD2AP), synaptopodin, and α-actinin-4 (ACTN4). Although most of these proteins were first identified through genetic studies associated with human kidney disease, subsequent studies have identified phosphorylation of these proteins as an important posttranslational event that regulates their function. In this review, a brief overview of the function of these key podocyte proteins is provided. Second, the role of phosphorylation in regulating the function of these proteins is described. Third, the association between these phosphorylation pathways and kidney disease is reviewed. Finally, challenges and future directions in studying phosphorylation are discussed. Better characterization of these phosphorylation pathways and others yet to be discovered holds promise for translating this knowledge into new therapies for patients with proteinuric chronic kidney disease.
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Affiliation(s)
- Di Feng
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
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20
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Blaine J, Dylewski J. Regulation of the Actin Cytoskeleton in Podocytes. Cells 2020; 9:cells9071700. [PMID: 32708597 PMCID: PMC7408282 DOI: 10.3390/cells9071700] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 06/30/2020] [Accepted: 07/07/2020] [Indexed: 12/13/2022] Open
Abstract
Podocytes are an integral part of the glomerular filtration barrier, a structure that prevents filtration of large proteins and macromolecules into the urine. Podocyte function is dependent on actin cytoskeleton regulation within the foot processes, structures that link podocytes to the glomerular basement membrane. Actin cytoskeleton dynamics in podocyte foot processes are complex and regulated by multiple proteins and other factors. There are two key signal integration and structural hubs within foot processes that regulate the actin cytoskeleton: the slit diaphragm and focal adhesions. Both modulate actin filament extension as well as foot process mobility. No matter what the initial cause, the final common pathway of podocyte damage is dysregulation of the actin cytoskeleton leading to foot process retraction and proteinuria. Disruption of the actin cytoskeleton can be due to acquired causes or to genetic mutations in key actin regulatory and signaling proteins. Here, we describe the major structural and signaling components that regulate the actin cytoskeleton in podocytes as well as acquired and genetic causes of actin dysregulation.
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Affiliation(s)
- Judith Blaine
- Renal Division, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA;
| | - James Dylewski
- Renal Division, University of Colorado Anschutz Medical Campus and Denver Health Medical Center, Aurora, CO 80045, USA
- Correspondence: ; Tel.: +303-724-4841
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21
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Hayashi D, Wang L, Ueda S, Yamanoue M, Ashida H, Shirai Y. The mechanisms of ameliorating effect of a green tea polyphenol on diabetic nephropathy based on diacylglycerol kinase α. Sci Rep 2020; 10:11790. [PMID: 32678222 PMCID: PMC7366667 DOI: 10.1038/s41598-020-68716-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 06/16/2020] [Indexed: 12/19/2022] Open
Abstract
Significant efforts have been made to ameliorate diabetic nephropathy (DN) by inhibiting protein kinase C. However, these efforts have not been successful in human trials, suggesting that novel therapeutic strategies are required. Thus far, it has been reported that green tea polyphenol epigallocatechin gallate (EGCg) improved albuminuria in DN in a human trial. Our previous study revealed that activation of diacylglycerol kinase α (DGKα) plays a crucial role in the amelioration of DN and that EGCg activates DGKα. Here, we investigated whether and how DGKα contributes to the amelioration of DN upon stimulation by EGCg by using streptozotocin-induced type 1 diabetic model mice. Our results revealed that EGCg ameliorated albuminuria in DN through DGKα in vivo, and methylated EGCg, which has higher absorption in the plasma improved albuminuria in DN effectively. Additionally, we showed that c-Src mediated EGCg-induced DGKα translocation and colocalized with the 67 kDa laminin receptor, which is an EGCg receptor. Furthermore, EGCg attenuated the loss of podocytes in DN by preventing a decrease in focal adhesion under high glucose conditions. Our results indicate that the DGKα pathway is an attractive therapeutic target and that activating this pathway is a novel strategy for treating DN.
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Affiliation(s)
- Daiki Hayashi
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Kobe University, Rokkodai-Cho 1-1, Nada-Ku, Kobe, 657-8501, Japan
| | - Liuqing Wang
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Kobe University, Rokkodai-Cho 1-1, Nada-Ku, Kobe, 657-8501, Japan
| | - Shuji Ueda
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Kobe University, Rokkodai-Cho 1-1, Nada-Ku, Kobe, 657-8501, Japan
| | - Minoru Yamanoue
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Kobe University, Rokkodai-Cho 1-1, Nada-Ku, Kobe, 657-8501, Japan
| | - Hitoshi Ashida
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Kobe University, Rokkodai-Cho 1-1, Nada-Ku, Kobe, 657-8501, Japan
| | - Yasuhito Shirai
- Department of Applied Chemistry in Bioscience, Graduate School of Agricultural Science, Kobe University, Rokkodai-Cho 1-1, Nada-Ku, Kobe, 657-8501, Japan.
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22
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Groener M, Wang Y, Cross E, Tian X, Ebenezer K, Baik E, Pedigo C, Schiffer M, Inoue K, Ishibe S. Identification of Podocyte Cargo Proteins by Proteomic Analysis of Clathrin-Coated Vesicles. KIDNEY360 2020; 1:480-490. [PMID: 35368594 PMCID: PMC8809311 DOI: 10.34067/kid.0000212020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 04/13/2020] [Indexed: 04/20/2023]
Abstract
Background Clathrin-mediated endocytosis (CME) plays a fundamental role in podocyte health. Genetic ablation of genes implicated in CME has been shown to cause severe proteinuria and foot process effacement in mice. However, little is known about the cargo of clathrin-coated vesicles (CCVs) in podocytes. The goal of this study was to isolate CCVs from podocytes and identify their cargo by proteomic analysis. Methods Glomeruli isolated from Podocin-Cre Rosa-DTRflox mouse kidneys were seeded and treated with diphtheria toxin to obtain pure primary podocyte cultures. CCVs were isolated by differential gradient ultracentrifugation, and enrichment of CCVs was assessed by immunoblotting and electron microscopy (EM). Liquid chromatography-mass spectrometry (LC-MS) was performed for proteomic analysis. Proteins with higher abundance than transferrin receptor protein 1 were evaluated for CCV cargo potential against previously published literature. Immunofluorescence staining of identified cargo proteins and CCVs was performed in podocytes for further verification. Results Immunoblotting for multiple protein markers of CME revealed enrichment in the CCV fraction. Enrichment of CCVs among other small vesicles was observed via EM. Proteomics yielded a total of >1200 significant proteins. Multiple-step data analysis revealed 36 CCV-associated proteins, of which 10 represent novel, highly abundant cargo proteins in podocytes. Colocalization of cargo proteins and CCVs on immunostaining was observed. Conclusions Our identification of podocyte CCV cargo proteins helps to elucidate the importance of endocytic trafficking for podocyte health and maintenance of the glomerular environment.
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Affiliation(s)
- Marwin Groener
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
- Department of Nephrology and Hypertension, University Hospital Erlangen, Erlangen, Germany
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Ying Wang
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Elizabeth Cross
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Xuefei Tian
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Karen Ebenezer
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Eunice Baik
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Christopher Pedigo
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Mario Schiffer
- Department of Nephrology and Hypertension, University Hospital Erlangen, Erlangen, Germany
- Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
- Mount Desert Island Biological Laboratories, Salisbury Cove, Maine
| | - Kazunori Inoue
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Shuta Ishibe
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
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23
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Shi Y, Wang C, Zhou X, Li Y, Ma Y, Zhang R, Li R. Downregulation of PTEN promotes podocyte endocytosis of lipids aggravating obesity-related glomerulopathy. Am J Physiol Renal Physiol 2020; 318:F589-F599. [PMID: 31813249 DOI: 10.1152/ajprenal.00392.2019] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
With the increasing prevalence of obesity in adults worldwide, the incidence of obesity-related glomerulopathy (ORG) has increased yearly, becoming one of the leading causes of end-stage renal disease. Studies have demonstrated significant correlations between hyperlipidemia and impaired renal function in patients with ORG, indicating that hyperlipidemia causes damage in kidney cells. In podocytes, the endocytosis of lipids triggers an intracellular oxidative stress response that disrupts cellular integrity, resulting in proteinuria and glomerular sclerosis. However, the specific molecular mechanisms through which podocytes endocytose lipids remain unclear. Here, we demonstrated the enhanced endocytosis of lipids by podocytes from patients with ORG. This response was associated with decreased expression of phosphatase and tensin homolog (PTEN). In vitro silencing of PTEN promoted the endocytosis of low-density lipoprotein in mouse podocytes. Conversely, overexpression of PTEN inhibited the endocytosis of lipoproteins in podocytes. PTEN directly dephosphorylates and activates the actin-depolymerizing factor cofilin-1, leading to depolymerization of filamentous actin (F-actin), which is necessary for endocytosis. Notably, inhibition of PTEN resulted in the phosphorylation and inactivation of cofilin-1, leading to F-actin formation that enhanced the endocytosis of lipoproteins in podocytes. When hyperlipidemia was induced in mice with podocyte-specific deletion of PTEN, these mice recapitulated the major pathophysiological features of ORG. Thus, PTEN downregulation in podocytes may contribute to the pathogenesis of ORG.
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Affiliation(s)
- Yuanyuan Shi
- Nephrology Division, The Affiliated People's Hospital of Shanxi Medical University, Taiyuan, China
- Nephrology Division, Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Chen Wang
- Pathology Division, Second Hospital of Shanxi Medical University, Taiyuan, China
| | - Xiaoshuang Zhou
- Nephrology Division, The Affiliated People's Hospital of Shanxi Medical University, Taiyuan, China
| | - Yafeng Li
- Nephrology Division, The Affiliated People's Hospital of Shanxi Medical University, Taiyuan, China
| | - Yuehong Ma
- Nephrology Division, The Affiliated People's Hospital of Shanxi Medical University, Taiyuan, China
| | - Rui Zhang
- Nephrology Division, The Affiliated People's Hospital of Shanxi Medical University, Taiyuan, China
| | - Rongshan Li
- Nephrology Division, The Affiliated People's Hospital of Shanxi Medical University, Taiyuan, China
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24
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Kampf LL, Schneider R, Gerstner L, Thünauer R, Chen M, Helmstädter M, Amar A, Onuchic-Whitford AC, Loza Munarriz R, Berdeli A, Müller D, Schrezenmeier E, Budde K, Mane S, Laricchia KM, Rehm HL, MacArthur DG, Lifton RP, Walz G, Römer W, Bergmann C, Hildebrandt F, Hermle T. TBC1D8B Mutations Implicate RAB11-Dependent Vesicular Trafficking in the Pathogenesis of Nephrotic Syndrome. J Am Soc Nephrol 2019; 30:2338-2353. [PMID: 31732614 DOI: 10.1681/asn.2019040414] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 08/07/2019] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Mutations in about 50 genes have been identified as monogenic causes of nephrotic syndrome, a frequent cause of CKD. These genes delineated the pathogenetic pathways and rendered significant insight into podocyte biology. METHODS We used whole-exome sequencing to identify novel monogenic causes of steroid-resistant nephrotic syndrome (SRNS). We analyzed the functional significance of an SRNS-associated gene in vitro and in podocyte-like Drosophila nephrocytes. RESULTS We identified hemizygous missense mutations in the gene TBC1D8B in five families with nephrotic syndrome. Coimmunoprecipitation assays indicated interactions between TBC1D8B and active forms of RAB11. Silencing TBC1D8B in HEK293T cells increased basal autophagy and exocytosis, two cellular functions that are independently regulated by RAB11. This suggests that TBC1D8B plays a regulatory role by inhibiting endogenous RAB11. Coimmunoprecipitation assays showed TBC1D8B also interacts with the slit diaphragm protein nephrin, and colocalizes with it in immortalized cell lines. Overexpressed murine Tbc1d8b with patient-derived mutations had lower affinity for endogenous RAB11 and nephrin compared with wild-type Tbc1d8b protein. Knockdown of Tbc1d8b in Drosophila impaired function of the podocyte-like nephrocytes, and caused mistrafficking of Sns, the Drosophila ortholog of nephrin. Expression of Rab11 RNAi in nephrocytes entailed defective delivery of slit diaphragm protein to the membrane, whereas RAB11 overexpression revealed a partial phenotypic overlap to Tbc1d8b loss of function. CONCLUSIONS Novel mutations in TBC1D8B are monogenic causes of SRNS. This gene inhibits RAB11. Our findings suggest that RAB11-dependent vesicular nephrin trafficking plays a role in the pathogenesis of nephrotic syndrome.
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Affiliation(s)
- Lina L Kampf
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Ronen Schneider
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Lea Gerstner
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Roland Thünauer
- Signalling Research Centres BIOSS and CIBSS and Faculty of Biology, University of Freiburg, Freiburg, Germany.,Advanced Light and Fluorescence Microscopy Facility, Centre for Structural Systems Biology (CSSB) and University of Hamburg, Hamburg, Germany
| | - Mengmeng Chen
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Martin Helmstädter
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Ali Amar
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Ana C Onuchic-Whitford
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts.,Renal Division, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
| | | | - Afig Berdeli
- Department of Pediatrics, Molecular Medicine Laboratory, Ege University, Izmir, Turkey
| | - Dominik Müller
- Department of Pediatric Nephrology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Eva Schrezenmeier
- Department of Nephrology and Medical Intensive Care, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Klemens Budde
- Department of Nephrology and Medical Intensive Care, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Shrikant Mane
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut
| | - Kristen M Laricchia
- Broad Center for Mendelian Genomics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge
| | - Heidi L Rehm
- Broad Center for Mendelian Genomics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge
| | - Daniel G MacArthur
- Broad Center for Mendelian Genomics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge
| | - Richard P Lifton
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut.,Laboratory of Human Genetics and Genomics, The Rockefeller University, New York, New York
| | - Gerd Walz
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Winfried Römer
- Signalling Research Centres BIOSS and CIBSS and Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Carsten Bergmann
- Center for Human Genetics, Mainz, Germany.,Center for Human Genetics, Bioscientia, Ingelheim, Germany; and.,Department of Medicine, University Hospital Freiburg, Freiburg, Germany
| | - Friedhelm Hildebrandt
- Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts;
| | - Tobias Hermle
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany;
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25
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Jiang W, Xiao T, Han W, Xiong J, He T, Liu Y, Huang Y, Yang K, Bi X, Xu X, Yu Y, Li Y, Gu J, Zhang J, Huang Y, Zhang B, Zhao J. Klotho inhibits PKCα/p66SHC-mediated podocyte injury in diabetic nephropathy. Mol Cell Endocrinol 2019; 494:110490. [PMID: 31207271 DOI: 10.1016/j.mce.2019.110490] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 06/12/2019] [Accepted: 06/12/2019] [Indexed: 10/26/2022]
Abstract
Diabetic nephropathy (DN) is a progressive disease, the main pathogeny of which is podocyte injury. As a calcium-dependent serine/threonine protein kinase involved in podocyte injury, protein kinase C isoform α (PKCα) was reported to regulate the phosphorylation of p66SHC. However, the role of PKCα/p66SHC in DN remains unknown. Klotho, an anti-aging protein with critical roles in protecting kidney, is expressed predominantly in the kidney and secreted in the blood. Nonetheless, the mechanism underlying amelioration of podocyte injury by Klotho in DN remains unclear. Our data showed that Klotho was decreased in STZ-treated mice and was further declined in diabetic KL ± mice. As expected, Klotho deficiency aggravated diabetes-induced proteinuria and podocyte injury, accompanied by the activation of PKCα and p66SHC. In contrast, overexpression of Klotho partially ameliorated PKCα/p66SHC-mediated podocyte injury and proteinuria. In addition, in vitro experiments showed that activation of PKCα and subsequently increased intracellular reactive oxygen species (ROS) was involved in podocytic apoptosis induced by high glucose (HG), which could be partially reversed by Klotho. Hence, we conclude that Klotho might inhibit PKCα/p66SHC-mediated podocyte injury in diabetic nephropathy.
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Affiliation(s)
- Wei Jiang
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Tangli Xiao
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Wenhao Han
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Jiachuan Xiong
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Ting He
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Yong Liu
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Yinghui Huang
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Ke Yang
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Xianjin Bi
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Xinli Xu
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Yanlin Yu
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Yan Li
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Jun Gu
- State Key Laboratory of Protein and Plant Gene Research, College of Life Science, Peking University, Beijing, China
| | - Jingbo Zhang
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Yunjian Huang
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, China
| | - Bo Zhang
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, China.
| | - Jinghong Zhao
- Department of Nephrology, Institute of Nephrology of Chongqing and Kidney Center of PLA, Xinqiao Hospital, Third Military Medical University, Chongqing, China.
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26
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Abstract
The increasing global prevalence of type 2 diabetes mellitus (T2DM) and chronic kidney disease (CKD) has prompted research efforts to tackle the growing epidemic of diabetic kidney disease (DKD; also known as diabetic nephropathy). The limited success of much of this research might in part be due to the fact that not all patients diagnosed with DKD have renal dysfunction as a consequence of their diabetes mellitus. Patients who present with CKD and diabetes mellitus (type 1 or type 2) can have true DKD (wherein CKD is a direct consequence of their diabetes status), nondiabetic kidney disease (NDKD) coincident with diabetes mellitus, or a combination of both DKD and NDKD. Preclinical studies using models that more accurately mimic these three entities might improve the ability of animal models to predict clinical trial outcomes. Moreover, improved insights into the pathomechanisms that are shared by these entities - including sodium-glucose cotransporter 2 (SGLT2) and renin-angiotensin system-driven glomerular hyperfiltration and tubular hyper-reabsorption - as well as those that are unique to individual entities might lead to the identification of new treatment targets. Acknowledging that the clinical entity of CKD plus diabetes mellitus encompasses NDKD as well as DKD could help solve some of the urgent unmet medical needs of patients affected by these conditions.
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27
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IQGAP1 mediates podocyte injury in diabetic kidney disease by regulating nephrin endocytosis. Cell Signal 2019; 59:13-23. [DOI: 10.1016/j.cellsig.2019.03.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 03/07/2019] [Accepted: 03/08/2019] [Indexed: 01/02/2023]
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28
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Tossidou I, Teng B, Worthmann K, Müller-Deile J, Jobst-Schwan T, Kardinal C, Schroder P, Bolanos-Palmieri P, Haller H, Willerding J, Drost DM, de Jonge L, Reubold T, Eschenburg S, Johnson RI, Schiffer M. Tyrosine Phosphorylation of CD2AP Affects Stability of the Slit Diaphragm Complex. J Am Soc Nephrol 2019; 30:1220-1237. [PMID: 31235616 DOI: 10.1681/asn.2018080860] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 04/18/2019] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND CD2-associated protein (CD2AP), a slit diaphragm-associated scaffolding protein involved in survival and regulation of the cytoskeleton in podocytes, is considered a "stabilizer" of the slit diaphragm complex that connects the slit diaphragm protein nephrin to the cytoskeleton of the cell. Tyrosine phosphorylation of slit diaphragm molecules can influence their surface expression, but it is unknown whether tyrosine phosphorylation events of CD2AP are also physiologically relevant to slit diaphragm stability. METHODS We used isoelectric focusing, western blot analysis, and immunofluorescence to investigate phosphorylation of CD2AP, and phospho-CD2AP antibodies and site-directed mutagenesis to define the specific phosphorylated tyrosine residues. We used cross-species rescue experiments in Cd2apKD zebrafish and in Drosophila cindrRNAi mutants to define the physiologic relevance of CD2AP phosphorylation of the tyrosine residues. RESULTS We found that VEGF-A stimulation can induce a tyrosine phosphorylation response in CD2AP in podocytes, and that these phosphorylation events have an important effect on slit diaphragm protein localization and functionality in vivo. We demonstrated that tyrosine in position Y10 of the SH3-1 domain of CD2AP is indispensable for CD2AP function in vivo. We found that the binding affinity of nephrin to CD2AP is significantly enhanced in the absence of Y10; however, unexpectedly, this increased affinity leads not to stabilization but to functional impairment of the glomerular filtration barrier. CONCLUSIONS Our findings provide insight into CD2AP and its phosphorylation in the context of slit diaphragm functionality, and indicate a fine-tuned affinity balance of CD2AP and nephrin that is influenced by receptor tyrosine kinase stimulation.
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Affiliation(s)
- Irini Tossidou
- Division of Nephrology and Hypertension, Department of Medicine
| | - Beina Teng
- Department of Nephrology and Hypertension, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | | | - Janina Müller-Deile
- Division of Nephrology and Hypertension, Department of Medicine.,Department of Nephrology and Hypertension, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Tilman Jobst-Schwan
- Department of Nephrology and Hypertension, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | | | - Patricia Schroder
- Division of Nephrology and Hypertension, Department of Medicine.,Mount Desert Island Biological Laboratory, Salisbury Cove, Maine; and
| | - Patricia Bolanos-Palmieri
- Department of Nephrology and Hypertension, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Hermann Haller
- Division of Nephrology and Hypertension, Department of Medicine.,Mount Desert Island Biological Laboratory, Salisbury Cove, Maine; and
| | - Jonas Willerding
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Dana M Drost
- Department of Biology, Wesleyan University, Middletown, Connecticut
| | - Laura de Jonge
- Department of Biology, Wesleyan University, Middletown, Connecticut
| | - Thomas Reubold
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Susanne Eschenburg
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Ruth I Johnson
- Department of Biology, Wesleyan University, Middletown, Connecticut
| | - Mario Schiffer
- Division of Nephrology and Hypertension, Department of Medicine, .,Department of Nephrology and Hypertension, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.,Mount Desert Island Biological Laboratory, Salisbury Cove, Maine; and
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29
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Espiritu EB, Jiang H, Moreau-Marquis S, Sullivan M, Yan K, Beer Stolz D, Sampson MG, Hukriede NA, Swiatecka-Urban A. The human nephrin Y 1139RSL motif is essential for podocyte foot process organization and slit diaphragm formation during glomerular development. J Biol Chem 2019; 294:10773-10788. [PMID: 31152064 DOI: 10.1074/jbc.ra119.008235] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 05/16/2019] [Indexed: 11/06/2022] Open
Abstract
Nephrin is an immunoglobulin-type cell-adhesion molecule with a key role in the glomerular interpodocyte slit diaphragm. Mutations in the nephrin gene are associated with defects in the slit diaphragm, leading to early-onset nephrotic syndrome, typically resistant to treatment. Although the endocytic trafficking of nephrin is essential for the assembly of the slit diaphragm, nephrin's specific endocytic motifs remain unknown. To search for endocytic motifs, here we performed a multisequence alignment of nephrin and identified a canonical YXXØ-type motif, Y1139RSL, in the nephrin cytoplasmic tail, expressed only in primates. Using site-directed mutagenesis, various biochemical methods, single-plane illumination microscopy, a human podocyte line, and a human nephrin-expressing zebrafish model, we found that Y1139RSL is a novel endocytic motif and a structural element for clathrin-mediated nephrin endocytosis that functions as a phosphorylation-sensitive signal. We observed that Y1139RSL motif-mediated endocytosis helps to localize nephrin to specialized plasma membrane domains in podocytes and is essential for normal foot process organization into a functional slit diaphragm between neighboring foot processes in zebrafish. The importance of nephrin Y1139RSL for healthy podocyte development was supported by population-level analyses of genetic variations at this motif, revealing that such variations are very rare, suggesting that mutations in this motif have autosomal-recessive negative effects on kidney health. These findings expand our understanding of the mechanism underlying nephrin endocytosis and may lead to improved diagnostic tools or therapeutic strategies for managing early-onset, treatment-resistant nephrotic syndrome.
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Affiliation(s)
- Eugenel B Espiritu
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201
| | - Huajun Jiang
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15224
| | - Sophie Moreau-Marquis
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
| | - Mara Sullivan
- Department of Nephrology, UPMC Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201
| | - Kunimasa Yan
- Department of Pediatrics, Kyorin University School of Medicine, Mitaka, Tokyo 181-8611, Japan, and
| | - Donna Beer Stolz
- Department of Nephrology, UPMC Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201
| | - Matthew G Sampson
- Department of Pediatrics-Nephrology University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Neil A Hukriede
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15201
| | - Agnieszka Swiatecka-Urban
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15224,.
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30
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Yu SMW, Nissaisorakarn P, Husain I, Jim B. Proteinuric Kidney Diseases: A Podocyte's Slit Diaphragm and Cytoskeleton Approach. Front Med (Lausanne) 2018; 5:221. [PMID: 30255020 PMCID: PMC6141722 DOI: 10.3389/fmed.2018.00221] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/18/2018] [Indexed: 01/19/2023] Open
Abstract
Proteinuric kidney diseases are a group of disorders with diverse pathological mechanisms associated with significant losses of protein in the urine. The glomerular filtration barrier (GFB), comprised of the three important layers, the fenestrated glomerular endothelium, the glomerular basement membrane (GBM), and the podocyte, dictates that disruption of any one of these structures should lead to proteinuric disease. Podocytes, in particular, have long been considered as the final gatekeeper of the GFB. This specialized visceral epithelial cell contains a complex framework of cytoskeletons forming foot processes and mediate important cell signaling to maintain podocyte health. In this review, we will focus on slit diaphragm proteins such as nephrin, podocin, TRPC6/5, as well as cytoskeletal proteins Rho/small GTPases and synaptopodin and their respective roles in participating in the pathogenesis of proteinuric kidney diseases. Furthermore, we will summarize the potential therapeutic options targeting the podocyte to treat this group of kidney diseases.
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Affiliation(s)
- Samuel Mon-Wei Yu
- Department of Medicine, Jacobi Medical Center, Bronx, NY, United States
| | | | - Irma Husain
- Department of Medicine, James J. Peters VA Medical Center, Bronx, NY, United States
| | - Belinda Jim
- Department of Medicine, Jacobi Medical Center, Bronx, NY, United States.,Renal Division, Jacobi Medical Center, Bronx, NY, United States
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31
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Hermle T, Schneider R, Schapiro D, Braun DA, van der Ven AT, Warejko JK, Daga A, Widmeier E, Nakayama M, Jobst-Schwan T, Majmundar AJ, Ashraf S, Rao J, Finn LS, Tasic V, Hernandez JD, Bagga A, Jalalah SM, El Desoky S, Kari JA, Laricchia KM, Lek M, Rehm HL, MacArthur DG, Mane S, Lifton RP, Shril S, Hildebrandt F. GAPVD1 and ANKFY1 Mutations Implicate RAB5 Regulation in Nephrotic Syndrome. J Am Soc Nephrol 2018; 29:2123-2138. [PMID: 29959197 PMCID: PMC6065084 DOI: 10.1681/asn.2017121312] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 05/24/2018] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Steroid-resistant nephrotic syndrome (SRNS) is a frequent cause of CKD. The discovery of monogenic causes of SRNS has revealed specific pathogenetic pathways, but these monogenic causes do not explain all cases of SRNS. METHODS To identify novel monogenic causes of SRNS, we screened 665 patients by whole-exome sequencing. We then evaluated the in vitro functional significance of two genes and the mutations therein that we discovered through this sequencing and conducted complementary studies in podocyte-like Drosophila nephrocytes. RESULTS We identified conserved, homozygous missense mutations of GAPVD1 in two families with early-onset NS and a homozygous missense mutation of ANKFY1 in two siblings with SRNS. GAPVD1 and ANKFY1 interact with the endosomal regulator RAB5. Coimmunoprecipitation assays indicated interaction between GAPVD1 and ANKFY1 proteins, which also colocalized when expressed in HEK293T cells. Silencing either protein diminished the podocyte migration rate. Compared with wild-type GAPVD1 and ANKFY1, the mutated proteins produced upon ectopic expression of GAPVD1 or ANKFY1 bearing the patient-derived mutations exhibited altered binding affinity for active RAB5 and reduced ability to rescue the knockout-induced defect in podocyte migration. Coimmunoprecipitation assays further demonstrated a physical interaction between nephrin and GAPVD1, and immunofluorescence revealed partial colocalization of these proteins in rat glomeruli. The patient-derived GAPVD1 mutations reduced nephrin-GAPVD1 binding affinity. In Drosophila, silencing Gapvd1 impaired endocytosis and caused mistrafficking of the nephrin ortholog. CONCLUSIONS Mutations in GAPVD1 and probably in ANKFY1 are novel monogenic causes of NS. The discovery of these genes implicates RAB5 regulation in the pathogenesis of human NS.
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Affiliation(s)
- Tobias Hermle
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
- Renal Division, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ronen Schneider
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - David Schapiro
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Daniela A Braun
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Amelie T van der Ven
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Jillian K Warejko
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Ankana Daga
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Eugen Widmeier
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Makiko Nakayama
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Tilman Jobst-Schwan
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Amar J Majmundar
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Shazia Ashraf
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Jia Rao
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Laura S Finn
- Department of Pathology, Seattle Children's Hospital, University of Washington, Seattle, Washington
| | - Velibor Tasic
- Department of Pediatric Nephrology, Medical Faculty Skopje, University Children's Hospital, Skopje, Macedonia
| | - Joel D Hernandez
- Department of Pediatric Nephrology, Providence Sacred Heart Medical Center and Children's Hospital, Spokane, Washington
| | - Arvind Bagga
- Division of Nephrology, All India Institute of Medical Sciences, New Delhi, India
| | | | - Sherif El Desoky
- Pediatric Nephrology Center of Excellence and Pediatric Department, Faculty of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Jameela A Kari
- Pediatric Nephrology Center of Excellence and Pediatric Department, Faculty of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Kristen M Laricchia
- Broad Center for Mendelian Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Monkol Lek
- Broad Center for Mendelian Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Heidi L Rehm
- Broad Center for Mendelian Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Daniel G MacArthur
- Broad Center for Mendelian Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Shrikant Mane
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut; and
| | - Richard P Lifton
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut; and
- Laboratory of Human Genetics and Genomics, The Rockefeller University, New York, New York
| | - Shirlee Shril
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Friedhelm Hildebrandt
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts;
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Wang Y, Li H, Song SP. β-Arrestin 1/2 Aggravates Podocyte Apoptosis of Diabetic Nephropathy via Wnt/β-Catenin Pathway. Med Sci Monit 2018; 24:1724-1732. [PMID: 29572435 PMCID: PMC5881455 DOI: 10.12659/msm.905642] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND β-arrestins have been shown to play a critical role in the progression of diabetic nephropathy. Nevertheless, the potential mechanism of β-arrestins on the regulation of podocyte apoptosis has rarely been discussed. This study aimed to elucidate the regulation of β-arrestin 1/2 on podocyte apoptosis through the Wnt/b-catenin pathway. MATERIAL AND METHODS This study structured β-arrestin 1/2 down-regulated and up-regulated expression by plasmid transfection. The protein levels were detected with Western blotting, and mRNA expression was detected with RT-qPCR. The apoptotic cells were measured by flow cytometry. RESULTS β-arrestin 1/2 expression levels of podocytes were up-regulated in high-glucose-induced podocytes. β-arrestin 1/2 overexpression inhibited the expression of nephrin and podocin protein. Up-regulated β-arrestin 1/2 promoted podocyte apoptosis and p53 pathway by increasing Bax, cleaved caspase-3, and p-p53 levels in high-glucose-induced podocytes. Flow cytometry showed that the apoptotic cells were markedly higher in the b-arrestin 1/2 up-regulated group compared with the scramble group. Expression of β-catenin was increased in the β-arrestin 1/2 up-regulated group, which indicated that the Wnt/b-catenin pathway was activated. Wnt/b-catenin pathway inhibitor (Dkk1) distinctly suppressed the apoptosis induced by β-arrestin 1/2 overexpression and high glucose. CONCLUSIONS These results provide a molecular pathomechanism of β-arrestin 1/2 and Wnt/β-catenin pathway on podocyte apoptosis and provide new ideas for the treatment of diabetic nephropathy, which paves the way for the future study of diabetic nephropathy and podocytes.
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Affiliation(s)
- Yao Wang
- Department of Endocrinology, Tianjin Hospital, Tianjin, China (mainland)
| | - Han Li
- Basic Medical College of Peking University, Tianjin, China (mainland)
| | - Shu-Ping Song
- Department of Endocrinology, Tianjin Hospital, Tianjin, China (mainland)
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Martin CE, Jones N. Nephrin Signaling in the Podocyte: An Updated View of Signal Regulation at the Slit Diaphragm and Beyond. Front Endocrinol (Lausanne) 2018; 9:302. [PMID: 29922234 PMCID: PMC5996060 DOI: 10.3389/fendo.2018.00302] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 05/22/2018] [Indexed: 12/11/2022] Open
Abstract
Podocytes are a major component of the glomerular blood filtration barrier, and alterations to the morphology of their unique actin-based foot processes (FP) are a common feature of kidney disease. Adjacent FP are connected by a specialized intercellular junction known as the slit diaphragm (SD), which serves as the ultimate barrier to regulate passage of macromolecules from the blood. While the link between SD dysfunction and reduced filtration selectivity has been recognized for nearly 50 years, our understanding of the underlying molecular circuitry began only 20 years ago, sparked by the identification of NPHS1, encoding the transmembrane protein nephrin. Nephrin not only functions as the core component of the extracellular SD filtration network but also as a signaling scaffold via interactions at its short intracellular region. Phospho-regulation of several conserved tyrosine residues in this region influences signal transduction pathways which control podocyte cell adhesion, shape, and survival, and emerging studies highlight roles for nephrin phospho-dynamics in mechanotransduction and endocytosis. The following review aims to summarize the last 5 years of advancement in our knowledge of how signaling centered at nephrin directs SD barrier formation and function. We further provide insight on promising frontiers in podocyte biology, which have implications for SD signaling in the healthy and diseased kidney.
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Xu H, Li Q, Liu J, Zhu J, Li L, Wang Z, Zhang Y, Sun Y, Sun J, Wang R, Yi F. β-Arrestin-1 deficiency ameliorates renal interstitial fibrosis by blocking Wnt1/β-catenin signaling in mice. J Mol Med (Berl) 2017; 96:97-109. [DOI: 10.1007/s00109-017-1606-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 10/13/2017] [Accepted: 10/25/2017] [Indexed: 12/20/2022]
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Li L, Zhang L, Binkley PF, Sadee W, Wang D. Regulatory Variants Modulate Protein Kinase C α (PRKCA) Gene Expression in Human Heart. Pharm Res 2017; 34:1648-1657. [PMID: 28120175 PMCID: PMC7315374 DOI: 10.1007/s11095-017-2102-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 01/06/2017] [Indexed: 11/26/2022]
Abstract
PURPOSE Protein kinase C α (PRKCA) is involved in multiple functions and has been implicated in heart failure risks and treatment outcomes. This study aims to identify regulatory variants affecting PRKCA expression in human heart, and evaluate attributable risk of heart disease. METHODS mRNA expression quantitative trait loci (eQTLs) were extracted from the Genotype and Tissue Expression Project (GTEx). Allelic mRNA ratios were measured in 51 human heart tissues to identify cis-acting regulatory variants. Potential regulatory regions were tested with luciferase reporter gene assays and further evaluated in GTEx and genome-wide association studies. RESULTS Located in a region with robust enhancer activity in luciferase reporter assays, rs9909004 (T > C, minor allele frequency =0.47) resides in a haplotype displaying strong eQTLs for PRKCA in heart (p = 1.2 × 10-23). The minor C allele is associated with both decreased PRKCA mRNA expression and decreased risk of phenotypes characteristic of heart failure in GWAS analyses (QT interval p = 3.0 × 10-14). While rs9909004 is the likely regulatory variant, other variants in high linkage disequilibrium cannot be excluded. Distinct regulatory variants appear to affect expression in other tissues. CONCLUSIONS The haplotype carrying rs9909004 influences PRKCA expression in the heart and is associated with traits linked to heart failure, potentially affecting therapy of heart failure.
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Affiliation(s)
- Liang Li
- Center for Pharmacogenomics and Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, 1005 BRT, 460 West 12th Ave, Columbus, Ohio, 43210, USA
| | - Lizhi Zhang
- Center for Pharmacogenomics and Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, 1005 BRT, 460 West 12th Ave, Columbus, Ohio, 43210, USA
| | - Philip F Binkley
- Department of Internal Medicine, College of Medicine, The Ohio State University, Columbus, Ohio, 43210, USA
| | - Wolfgang Sadee
- Center for Pharmacogenomics and Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, 1005 BRT, 460 West 12th Ave, Columbus, Ohio, 43210, USA
| | - Danxin Wang
- Center for Pharmacogenomics and Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, 1005 BRT, 460 West 12th Ave, Columbus, Ohio, 43210, USA.
- Center for Pharmacogenomics and Department of Cancer Biology and Genetics, College of Medicine, The Ohio State University, 1005 BRT, 460 W 12th Avenue, Columbus, Ohio, 43210, USA.
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Haase R, Potthoff SA, Meyer-Schwesinger C, Frosch C, Wiech T, Panzer U, Königshausen E, Stegbauer J, Sellin L, Rump LC, Quack I, Woznowski M. A novel in vivo method to quantify slit diaphragm protein abundance in murine proteinuric kidney disease. PLoS One 2017; 12:e0179217. [PMID: 28604827 PMCID: PMC5467901 DOI: 10.1371/journal.pone.0179217] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 05/25/2017] [Indexed: 02/07/2023] Open
Abstract
Injury of the glomerular filter causes proteinuria by disrupting the sensitive interplay of the glomerular protein network. To date, studies of the expression and trafficking of glomerular proteins have been mostly limited to in vitro or histologic studies. Here, we report a novel in vivo biotinylation assay that allows the quantification of surface expression of glomerular proteins in mice. Kidneys were perfused in situ with biotin before harvest. Afterwards glomeruli were isolated and lyzed. The protein of interest was separated by immunoprecipitation and the amount of surface-expressed protein was quantified by Western blot analysis with streptavidin staining. As proof-of-concept, we examined the presence of nephrin in the slit diaphragm in two well-established murine models of proteinuric kidney disease: nephrotoxic nephritis and adriamycin nephropathy. In proteinuric animals, significantly less nephrin was detected in the slit diaphragm. When proteinuria decreased once again during the course of disease, the amount of surface nephrin returned to the baseline. Our present results suggest that our assay is a valuable tool to study the glomerular filter in proteinuric kidney diseases. Note that the assay is not limited to proteins expressed in the slit diaphragm, and all surface proteins that are accessible to biotin perfusion and immunoprecipitation qualify for this analysis.
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Affiliation(s)
- Raphael Haase
- Department of Nephrology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
| | | | | | - Clara Frosch
- Department of Nephrology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
| | - Thorsten Wiech
- Institute of Pathology, University Hospital Eppendorf, Hamburg, Germany
| | - Ulf Panzer
- III. Medical Clinic University Hospital Eppendorf, Hamburg, Germany
| | - Eva Königshausen
- Department of Nephrology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
| | - Johannes Stegbauer
- Department of Nephrology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
| | - Lorenz Sellin
- Department of Nephrology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
| | - Lars Christian Rump
- Department of Nephrology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
| | - Ivo Quack
- Department of Nephrology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
- * E-mail:
| | - Magdalena Woznowski
- Department of Nephrology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
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Diacylglycerol Kinase alpha is Involved in the Vitamin E-Induced Amelioration of Diabetic Nephropathy in Mice. Sci Rep 2017; 7:2597. [PMID: 28572624 PMCID: PMC5453949 DOI: 10.1038/s41598-017-02354-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 04/10/2017] [Indexed: 02/05/2023] Open
Abstract
Diabetic nephropathy (DN) is one of vascular complications of diabetes and is caused by abnormal protein kinase C activation as a result of increased diacylglycerol (DG) production in diabetic hyperglycaemia. Diacylglycerol kinase (DGK) converts DG into phosphatidic acid. Therefore, it is expected that the activation of DGK would ameliorate DN. Indeed, it has been reported that vitamin E (VtE) ameliorates DN in rat by activating DGK, and we recently reported that VtE specifically activates DGKα isoform in vitro. However, whether DGKα is involved in the VtE-induced amelioration of DN in vivo remains unknown. Therefore, we investigated the VtE-induced amelioration of DN in wild-type (DGKα+/+) and DGKα–deficient (DGKα−/−) mice in which diabetes was induced by streptozocin. Several symptoms of DN were ameliorated by VtE treatment in the DGKα+/+ mice but not in the DGKα−/− mice. Moreover, transmission electron microscopy of glomeruli and immunofluorescent staining of glomerular epithelial cells (podocytes) indicated that VtE ameliorates podocyte pathology and prevents podocyte loss in the DGKα+/+ mice but not in the DGKα−/− mice. We showed that VtE can ameliorate DN in mice and that DGKα is involved in the VtE-induced amelioration of DN in vivo, suggesting that DGKα is an attractive therapeutic target for DN.
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Dumont V, Tolvanen TA, Kuusela S, Wang H, Nyman TA, Lindfors S, Tienari J, Nisen H, Suetsugu S, Plomann M, Kawachi H, Lehtonen S. PACSIN2 accelerates nephrin trafficking and is up-regulated in diabetic kidney disease. FASEB J 2017; 31:3978-3990. [PMID: 28550045 PMCID: PMC5572687 DOI: 10.1096/fj.201601265r] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 05/01/2017] [Indexed: 01/07/2023]
Abstract
Nephrin is a core component of podocyte (glomerular epithelial cell) slit diaphragm and is required for kidney ultrafiltration. Down-regulation or mislocalization of nephrin has been observed in diabetic kidney disease (DKD), characterized by albuminuria. Here, we investigate the role of protein kinase C and casein kinase 2 substrate in neurons 2 (PACSIN2), a regulator of endocytosis and recycling, in the trafficking of nephrin and development of DKD. We observe that PACSIN2 is up-regulated and nephrin mislocalized in podocytes of obese Zucker diabetic fatty (ZDF) rats that have altered renal function. In cultured podocytes, PACSIN2 and nephrin colocalize and interact. We show that nephrin is endocytosed in PACSIN2-positive membrane regions and that PACSIN2 overexpression increases both nephrin endocytosis and recycling. We identify rabenosyn-5, which is involved in early endosome maturation and endosomal sorting, as a novel interaction partner of PACSIN2. Interestingly, rabenosyn-5 expression is increased in podocytes in obese ZDF rats, and, in vitro, its overexpression enhances the association of PACSIN2 and nephrin. We also show that palmitate, which is elevated in diabetes, enhances this association. Collectively, PACSIN2 is up-regulated and nephrin is abnormally localized in podocytes of diabetic ZDF rats. In vitro, PACSIN2 enhances nephrin turnover apparently via a mechanism involving rabenosyn-5. The data suggest that elevated PACSIN2 expression accelerates nephrin trafficking and associates with albuminuria.—Dumont, V., Tolvanen, T. A., Kuusela, S., Wang, H., Nyman, T. A., Lindfors, S., Tienari, J., Nisen, H., Suetsugu, S., Plomann, M., Kawachi, H., Lehtonen, S. PACSIN2 accelerates nephrin trafficking and is up-regulated in diabetic kidney disease.
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Affiliation(s)
- Vincent Dumont
- Department of Pathology, University of Helsinki, Helsinki, Finland
| | | | - Sara Kuusela
- Department of Pathology, University of Helsinki, Helsinki, Finland
| | - Hong Wang
- Department of Pathology, University of Helsinki, Helsinki, Finland
| | - Tuula A Nyman
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Sonja Lindfors
- Department of Pathology, University of Helsinki, Helsinki, Finland
| | - Jukka Tienari
- Department of Pathology, Helsinki University Hospital, Hyvinkää, Finland.,Department of Pathology, Helsinki University Hospital, Hyvinkää, Finland
| | - Harry Nisen
- Department of Urology, Helsinki University Hospital, Helsinki, Finland
| | - Shiro Suetsugu
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Japan
| | | | - Hiroshi Kawachi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Sanna Lehtonen
- Department of Pathology, University of Helsinki, Helsinki, Finland;
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Swiatecka-Urban A. Endocytic Trafficking at the Mature Podocyte Slit Diaphragm. Front Pediatr 2017; 5:32. [PMID: 28286744 PMCID: PMC5324021 DOI: 10.3389/fped.2017.00032] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 02/03/2017] [Indexed: 12/16/2022] Open
Abstract
Endocytic trafficking couples cell signaling with the cytoskeletal dynamics by organizing a crosstalk between protein networks in different subcellular compartments. Proteins residing in the plasma membrane are internalized and transported as cargo in endocytic vesicles (i.e., endocytosis). Subsequently, cargo proteins can be delivered to lysosomes for degradation or recycled back to the plasma membrane. The slit diaphragm is a modified tight junction connecting foot processes of the glomerular epithelial cells, podocytes. Signaling at the slit diaphragm plays a critical role in the kidney while its dysfunction leads to glomerular protein loss (proteinuria), manifesting as nephrotic syndrome, a rare condition with an estimated incidence of 2-4 new cases per 100,000 each year. Relatively little is known about the role of endocytic trafficking in podocyte signaling and maintenance of the slit diaphragm integrity. This review will focus on the role of endocytic trafficking at the mature podocyte slit diaphragm.
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Affiliation(s)
- Agnieszka Swiatecka-Urban
- Department of Nephrology, Children's Hospital of Pittsburgh, Pittsburgh, PA, USA; Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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Regulation of Nephrin Phosphorylation in Diabetes and Chronic Kidney Injury. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017. [PMID: 28639250 DOI: 10.1007/5584_2017_62] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Diabetes is the leading cause of microalbuminuria and end-stage renal failure in industrial countries. Disruption of the filtration barrier, seen in almost all nephrotic diseases and diabetes, is the result of the loss or effacement of the podocyte foot process, notably damage of proteins within the slit diaphragm such as nephrin. For many years, nephrin has been viewed as a structural component of the slit diaphragm. It is now well recognized that nephrin contains several tyrosine residues in its cytoplasmic domain, which influences the development of glomerular injury. In this review, we propose an overview of nephrin signaling pathways in kidney injury.
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Angiotensin II increases glomerular permeability by β-arrestin mediated nephrin endocytosis. Sci Rep 2016; 6:39513. [PMID: 28004760 PMCID: PMC5177899 DOI: 10.1038/srep39513] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 11/21/2016] [Indexed: 01/13/2023] Open
Abstract
Glomerular permeability and subsequent albuminuria are early clinical markers for glomerular injury in hypertensive nephropathy. Albuminuria predicts mortality and cardiovascular morbidity. AT1 receptor blockers protect from albuminuria, cardiovascular morbidity and mortality. A blood pressure independent, molecular mechanism for angiotensin II (Ang II) dependent albuminuria has long been postulated. Albuminuria results from a defective glomerular filter. Nephrin is a major structural component of the glomerular slit diaphragm and its endocytosis is mediated by β-arrestin2. Ang II stimulation increases nephrin-β-arrestin2 binding, nephrin endocytosis and glomerular permeability in mice. This Ang II effect is mediated by AT1-receptors. AT1-receptor mutants identified G-protein signaling to be essential for this Ang II effect. Gαq knockdown and phospholipase C inhibition block Ang II mediated enhanced nephrin endocytosis. Nephrin Y1217 is the critical residue controlling nephrin binding to β-arrestin under Ang II stimulation. Nephrin Y1217 also mediates cytoskeletal anchoring to actin via nck2. Ang II stimulation decreases nephrin nck2 binding. We conclude that Ang II weakens the structural integrity of the slit diaphragm by increased nephrin endocytosis and decreased nephrin binding to nck2, which leads to increased glomerular permeability. This novel molecular mechanism of Ang II supports the use of AT1-receptor blockers to prevent albuminuria even in normotensives.
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Nagai K, Doi T. CIN85: Implications for the Development of Proteinuria in Diabetic Nephropathy. Diabetes 2016; 65:3532-3534. [PMID: 27879403 DOI: 10.2337/dbi16-0051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Kojiro Nagai
- Department of Nephrology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Toshio Doi
- Department of Nephrology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
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Teng B, Schroder P, Müller-Deile J, Schenk H, Staggs L, Tossidou I, Dikic I, Haller H, Schiffer M. CIN85 Deficiency Prevents Nephrin Endocytosis and Proteinuria in Diabetes. Diabetes 2016; 65:3667-3679. [PMID: 27531950 PMCID: PMC5314701 DOI: 10.2337/db16-0081] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 07/31/2016] [Indexed: 12/12/2022]
Abstract
Diabetic nephropathy (DN) is the major cause of end-stage renal disease worldwide. Podocytes are important for glomerular filtration barrier function and maintenance of size selectivity in protein filtration in the kidney. Podocyte damage is the basis of many glomerular diseases characterized by loss of interdigitating foot processes and decreased expression of components of the slit diaphragm. Nephrin, a podocyte-specific protein, is the main component of the slit diaphragm. Loss of nephrin is observed in human and rodent models of diabetic kidney disease. The long isoform of CIN85 (RukL) is a binding partner of nephrin that mediates nephrin endocytosis via ubiquitination in podocytes. Here we demonstrate that the loss of nephrin expression and the onset of proteinuria in diabetic mice correlate with an increased accumulation of ubiquitinated proteins and expression of CIN85/RukL in podocytes. CIN85/RukL deficiency preserved nephrin surface expression on the slit diaphragm and reduced proteinuria in diabetic mice, whereas overexpression of CIN85 in zebrafish induced severe edema and disruption of the filtration barrier. Thus, CIN85/RukL is involved in endocytosis of nephrin in podocytes under diabetic conditions, causing podocyte depletion and promoting proteinuria. CIN85/RukL expression therefore shows potential to be a novel target for antiproteinuric therapy in diabetes.
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Affiliation(s)
- Beina Teng
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
| | | | - Janina Müller-Deile
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
| | - Heiko Schenk
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
| | - Lynne Staggs
- Mount Desert Island Biological Laboratory, Salisbury Cove, ME
| | - Irini Tossidou
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
| | - Ivan Dikic
- Institute of Biochemistry II, Goethe University Frankfurt, Frankfurt, Germany
| | - Hermann Haller
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
| | - Mario Schiffer
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
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Jha JC, Banal C, Chow BSM, Cooper ME, Jandeleit-Dahm K. Diabetes and Kidney Disease: Role of Oxidative Stress. Antioxid Redox Signal 2016; 25:657-684. [PMID: 26906673 PMCID: PMC5069735 DOI: 10.1089/ars.2016.6664] [Citation(s) in RCA: 395] [Impact Index Per Article: 49.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Intrarenal oxidative stress plays a critical role in the initiation and progression of diabetic kidney disease (DKD). Enhanced oxidative stress results from overproduction of reactive oxygen species (ROS) in the context of concomitant, insufficient antioxidant pathways. Renal ROS production in diabetes is predominantly mediated by various NADPH oxidases (NOXs), but a defective antioxidant system as well as mitochondrial dysfunction may also contribute. Recent Advances: Effective agents targeting the source of ROS generation hold the promise to rescue the kidney from oxidative damage and prevent subsequent progression of DKD. Critical Issues and Future Directions: In the present review, we summarize and critically analyze molecular and cellular mechanisms that have been demonstrated to be involved in NOX-induced renal injury in diabetes, with particular focus on the role of increased glomerular injury, the development of albuminuria, and tubulointerstitial fibrosis, as well as mitochondrial dysfunction. Furthermore, novel agents targeting NOX isoforms are discussed. Antioxid. Redox Signal. 25, 657-684.
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Affiliation(s)
- Jay C Jha
- 1 Diabetic Complications Division, JDRF Danielle Alberti Memorial Centre for Diabetic Complications, Baker IDI Heart and Diabetes Institute , Melbourne, Australia
| | - Claudine Banal
- 1 Diabetic Complications Division, JDRF Danielle Alberti Memorial Centre for Diabetic Complications, Baker IDI Heart and Diabetes Institute , Melbourne, Australia
| | - Bryna S M Chow
- 1 Diabetic Complications Division, JDRF Danielle Alberti Memorial Centre for Diabetic Complications, Baker IDI Heart and Diabetes Institute , Melbourne, Australia
| | - Mark E Cooper
- 1 Diabetic Complications Division, JDRF Danielle Alberti Memorial Centre for Diabetic Complications, Baker IDI Heart and Diabetes Institute , Melbourne, Australia .,2 Department of Medicine, Monash University , Melbourne, Australia
| | - Karin Jandeleit-Dahm
- 1 Diabetic Complications Division, JDRF Danielle Alberti Memorial Centre for Diabetic Complications, Baker IDI Heart and Diabetes Institute , Melbourne, Australia .,2 Department of Medicine, Monash University , Melbourne, Australia
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Abstract
Genetic studies of hereditary forms of nephrotic syndrome have identified several proteins that are involved in regulating the permselective properties of the glomerular filtration system. Further extensive research has elucidated the complex molecular basis of the glomerular filtration barrier and clearly established the pivotal role of podocytes in the pathophysiology of glomerular diseases. Podocyte architecture is centred on focal adhesions and slit diaphragms - multiprotein signalling hubs that regulate cell morphology and function. A highly interconnected actin cytoskeleton enables podocytes to adapt in order to accommodate environmental changes and maintain an intact glomerular filtration barrier. Actin-based endocytosis has now emerged as a regulator of podocyte integrity, providing an impetus for understanding the precise mechanisms that underlie the steady-state control of focal adhesion and slit diaphragm components. This Review outlines the role of actin dynamics and endocytosis in podocyte biology, and discusses how molecular heterogeneity in glomerular disorders could be exploited to deliver more rational therapeutic interventions, paving the way for targeted medicine in nephrology.
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Liu J, Li QX, Wang XJ, Zhang C, Duan YQ, Wang ZY, Zhang Y, Yu X, Li NJ, Sun JP, Yi F. β-Arrestins promote podocyte injury by inhibition of autophagy in diabetic nephropathy. Cell Death Dis 2016; 7:e2183. [PMID: 27054338 PMCID: PMC4855668 DOI: 10.1038/cddis.2016.89] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 03/01/2016] [Accepted: 03/03/2016] [Indexed: 11/16/2022]
Abstract
β-Arrestins are multifunctional proteins originally identified as negative adaptors of G protein-coupled receptors (GPCRs). Emerging evidence has also indicated that β-arrestins can activate signaling pathways independent of GPCR activation. This study was to elucidate the role of β-arrestins in diabetic nephropathy (DN) and hypothesized that β-arrestins contribute to diabetic renal injury by mediating podocyte autophagic process. We first found that both β-arrestin-1 and β-arrestin-2 were upregulated in the kidney from streptozotocin-induced diabetic mice, diabetic db/db mice and kidney biopsies from diabetic patients. We further revealed that either β-arrestin-1 or β-arrestin-2 deficiency (Arrb1−/− or Arrb2−/−) ameliorated renal injury in diabetic mice. In vitro, we observed that podocytes increased both β-arrestin-1 and β-arrestin-2 expression levels under hyperglycemia condition and further demonstrated that β-arrestin-1 and β-arrestin-2 shared common mechanisms to suppress podocyte autophagy by negative regulation of ATG12–ATG5 conjugation. Collectively, this study for the first time demonstrates that β-arrestin-1 and β-arrestin-2 mediate podocyte autophagic activity, indicating that β-arrestins are critical components of signal transduction pathways that link renal injury to reduce autophagy in DN. Modulation of these pathways may be an innovative therapeutic strategy for treating patients with DN.
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Affiliation(s)
- J Liu
- Department of Pharmacology, Shandong University School of Medicine, Jinan 250012, China
| | - Q X Li
- Department of Pharmacology, Shandong University School of Medicine, Jinan 250012, China
| | - X J Wang
- Department of Pharmacology, Shandong University School of Medicine, Jinan 250012, China
| | - C Zhang
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Y Q Duan
- Department of Pharmacology, Shandong University School of Medicine, Jinan 250012, China
| | - Z Y Wang
- Department of Pharmacology, Shandong University School of Medicine, Jinan 250012, China
| | - Y Zhang
- Department of Pharmacology, Shandong University School of Medicine, Jinan 250012, China
| | - X Yu
- Department of Physiology, Shandong University School of Medicine, Jinan 250012, China
| | - N J Li
- Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - J P Sun
- Department of Biochemistry and Molecular Biology, Shandong University School of Medicine, Jinan 250012, China
| | - F Yi
- Department of Pharmacology, Shandong University School of Medicine, Jinan 250012, China.,Institute of Nephrology, Shandong University, Jinan 250012, China
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Jha JC, Thallas-Bonke V, Banal C, Gray SP, Chow BSM, Ramm G, Quaggin SE, Cooper ME, Schmidt HHHW, Jandeleit-Dahm KA. Podocyte-specific Nox4 deletion affords renoprotection in a mouse model of diabetic nephropathy. Diabetologia 2016; 59:379-89. [PMID: 26508318 PMCID: PMC6450410 DOI: 10.1007/s00125-015-3796-0] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 10/01/2015] [Indexed: 12/13/2022]
Abstract
AIMS/HYPOTHESIS Changes in podocyte morphology and function are associated with albuminuria and progression of diabetic nephropathy. NADPH oxidase 4 (NOX4) is the main source of reactive oxygen species (ROS) in the kidney and Nox4 is upregulated in podocytes in response to high glucose. We assessed the role of NOX4-derived ROS in podocytes in vivo in a model of diabetic nephropathy using a podocyte-specific NOX4-deficient mouse, with a major focus on the development of albuminuria and ultra-glomerular structural damage. METHODS Streptozotocin-induced diabetes-associated changes in renal structure and function were studied in male floxedNox4 and podocyte-specific, NOX4 knockout (podNox4KO) mice. We assessed albuminuria, glomerular extracellular matrix accumulation and glomerulosclerosis, and markers of ROS and inflammation, as well as glomerular basement membrane thickness, effacement of podocytes and expression of the podocyte-specific protein nephrin. RESULTS Podocyte-specific Nox4 deletion in streptozotocin-induced diabetic mice attenuated albuminuria in association with reduced vascular endothelial growth factor (VEGF) expression and prevention of the diabetes-induced reduction in nephrin expression. In addition, podocyte-specific Nox4 deletion reduced glomerular accumulation of collagen IV and fibronectin, glomerulosclerosis and mesangial expansion, as well as glomerular basement membrane thickness. Furthermore, diabetes-induced increases in renal ROS, glomerular monocyte chemoattractant protein-1 (MCP-1) and protein kinase C alpha (PKC-α) were attenuated in podocyte-specific NOX4-deficient mice. CONCLUSIONS/INTERPRETATION Collectively, this study shows the deleterious effect of Nox4 expression in podocytes by promoting podocytopathy in association with albuminuria and extracellular matrix accumulation in experimental diabetes, emphasising the role of NOX4 as a target for new renoprotective agents.
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Affiliation(s)
- Jay C Jha
- Diabetes Complications Division, Baker IDI Heart & Diabetes Research Institute, PO Box 6492, St Kilda Rd, Melbourne, VIC, 8008, Australia
- Department of Medicine, Monash University, Melbourne, VIC, Australia
| | - Vicki Thallas-Bonke
- Diabetes Complications Division, Baker IDI Heart & Diabetes Research Institute, PO Box 6492, St Kilda Rd, Melbourne, VIC, 8008, Australia
| | - Claudine Banal
- Diabetes Complications Division, Baker IDI Heart & Diabetes Research Institute, PO Box 6492, St Kilda Rd, Melbourne, VIC, 8008, Australia
| | - Stephen P Gray
- Diabetes Complications Division, Baker IDI Heart & Diabetes Research Institute, PO Box 6492, St Kilda Rd, Melbourne, VIC, 8008, Australia
| | - Bryna S M Chow
- Diabetes Complications Division, Baker IDI Heart & Diabetes Research Institute, PO Box 6492, St Kilda Rd, Melbourne, VIC, 8008, Australia
| | - Georg Ramm
- Monash Micro-imaging, Monash University, Melbourne, VIC, Australia
| | | | - Mark E Cooper
- Diabetes Complications Division, Baker IDI Heart & Diabetes Research Institute, PO Box 6492, St Kilda Rd, Melbourne, VIC, 8008, Australia
- Department of Medicine, Monash University, Melbourne, VIC, Australia
| | - Harald H H W Schmidt
- Department of Pharmacology, Cardiovascular Research Institute Maastricht (CARIM), Faculty of Medicine, Health & Life Science, Maastricht University, Maastricht, the Netherlands
| | - Karin A Jandeleit-Dahm
- Diabetes Complications Division, Baker IDI Heart & Diabetes Research Institute, PO Box 6492, St Kilda Rd, Melbourne, VIC, 8008, Australia.
- Department of Medicine, Monash University, Melbourne, VIC, Australia.
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The emerging roles of β-arrestins in fibrotic diseases. Acta Pharmacol Sin 2015; 36:1277-87. [PMID: 26388156 DOI: 10.1038/aps.2015.74] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 06/29/2015] [Indexed: 02/06/2023] Open
Abstract
β-Arrestins and β-arrestin2 are important adaptor proteins and signal transduction proteins that are mainly involved in the desensitization and internalization of G-protein-coupled receptors. Fibrosis is characterized by accumulation of excess extracellular matrix (ECM) molecules caused by chronic tissue injury. If highly progressive, the fibrotic process leads to organ malfunction and, eventually, death. The incurable lung fibrosis, renal fibrosis and liver fibrosis are among the most common fibrotic diseases. Recent studies show that β-arrestins can activate signaling cascades independent of G-protein activation and scaffold many intracellular signaling networks by diverse types of signaling pathways, including the Hedgehog, Wnt, Notch and transforming growth factor-β pathways, as well as downstream kinases such as MAPK and PI3K. These signaling pathways are involved in the pathological process of fibrosis and fibrotic diseases. This β-arrestin-mediated regulation not only affects cell growth and apoptosis, but also the deposition of ECM, activation of inflammatory response and development of fibrotic diseases. In this review, we survey the involvement of β-arrestins in various signaling pathways and highlight different aspects of their regulation of fibrosis. We also discuss the important roles of β-arrestins in the process of fibrotic diseases by regulating the inflammation and deposit of ECM. It is becoming more evident that targeting β-arrestins may offer therapeutic potential for the treatment of fibrotic diseases.
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Lehtonen S, Jalanko H. Nephrin Trafficking beyond the Kidney--Role in Glucose-Stimulated Insulin Secretion in β Cells. J Am Soc Nephrol 2015; 27:965-8. [PMID: 26400568 DOI: 10.1681/asn.2015080960] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Sanna Lehtonen
- Department of Pathology, University of Helsinki, Helsinki, Finland; and
| | - Hannu Jalanko
- Children's Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
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50
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Inoue K, Ishibe S. Podocyte endocytosis in the regulation of the glomerular filtration barrier. Am J Physiol Renal Physiol 2015; 309:F398-405. [PMID: 26084928 DOI: 10.1152/ajprenal.00136.2015] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 06/15/2015] [Indexed: 02/06/2023] Open
Abstract
Severe defects in the glomerular filtration barrier result in nephrotic syndrome, which is characterized by massive proteinuria. The podocyte, a specialized epithelial cell with interdigitating foot processes separated by a slit diaphragm, plays a vital role in regulating the passage of proteins from the capillary lumen to Bowman's space. Recent findings suggest a critical role for endocytosis in podocyte biology as highlighted by genetic mouse models of disease and human genetic mutations that result in the loss of the integrity of the glomerular filtration barrier. In vitro podocyte studies have also unraveled a plethora of constituents that are differentially internalized to maintain homeostasis. These observations provide a framework and impetus for understanding the precise regulation of podocyte endocytic machinery in both health and disease.
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Affiliation(s)
- Kazunori Inoue
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
| | - Shuta Ishibe
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut
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