1
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Stamellou E, Agrawal S, Siegerist F, Buse M, Kuppe C, Lange T, Buhl EM, Alam J, Strieder T, Boor P, Ostendorf T, Gröne HJ, Floege J, Smoyer WE, Endlich N, Moeller MJ. Inhibition of the glucocorticoid receptor attenuates proteinuric kidney diseases in multiple species. Nephrol Dial Transplant 2024; 39:1181-1193. [PMID: 38037533 PMCID: PMC11210988 DOI: 10.1093/ndt/gfad254] [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: 06/23/2023] [Indexed: 12/02/2023] Open
Abstract
BACKGROUND Glucocorticoids are the treatment of choice for proteinuric patients with minimal change disease (MCD) and primary focal segmental glomerulosclerosis (FSGS). Immunosuppressive as well as direct effects on podocytes are believed to mediate their actions. In this study, we analyzed the anti-proteinuric effects of inhibition of the glucocorticoid receptor (GR) in glomerular epithelial cells, including podocytes. METHODS We employed genetic and pharmacological approaches to inhibit the GR. Genetically, we used Pax8-Cre/GRfl/fl mice to specifically inactivate the GR in kidney epithelial cells. Pharmacologically, we utilized a glucocorticoid antagonist called mifepristone. RESULTS Genetic inactivation of GR, specifically in kidney epithelial cells, using Pax8-Cre/GRfl/fl mice, ameliorated proteinuria following protein overload. We further tested the effects of pharmacological GR inhibition in three models and species: the puromycin aminonucleoside-induced nephrosis model in rats, the protein overload model in mice and the inducible transgenic NTR/MTZ zebrafish larvae with specific and reversible podocyte injury. In all three models, both pharmacological GR activation and inhibition consistently and significantly ameliorated proteinuria. Additionally, we translated our findings to humans, where three nephrotic adult patients with MCD or primary FSGS with contraindications or insufficient responses to corticosteroids were treated with mifepristone. This treatment resulted in a clinically relevant reduction of proteinuria. CONCLUSIONS Thus, across multiple species and proteinuria models, both genetic and pharmacological GR inhibition was at least as effective as pronounced GR activation. While the mechanism remains perplexing, GR inhibition may be a novel and targeted therapeutic approach to treat glomerular proteinuria potentially bypassing adverse actions of steroids.
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MESH Headings
- Animals
- Receptors, Glucocorticoid/metabolism
- Receptors, Glucocorticoid/antagonists & inhibitors
- Mice
- Proteinuria/drug therapy
- Proteinuria/etiology
- Proteinuria/metabolism
- Humans
- Rats
- Podocytes/metabolism
- Podocytes/drug effects
- Podocytes/pathology
- Zebrafish
- Male
- Mifepristone/pharmacology
- Disease Models, Animal
- Glomerulosclerosis, Focal Segmental/drug therapy
- Glomerulosclerosis, Focal Segmental/metabolism
- Glomerulosclerosis, Focal Segmental/pathology
- Female
- Kidney Diseases/drug therapy
- Kidney Diseases/etiology
- Kidney Diseases/metabolism
- Puromycin Aminonucleoside
- Hormone Antagonists/pharmacology
- Nephrosis, Lipoid/drug therapy
- Nephrosis, Lipoid/metabolism
- Mice, Inbred C57BL
- Mice, Transgenic
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Affiliation(s)
- Eleni Stamellou
- Division of Nephrology and Clinical Immunology, RWTH Aachen University, Aachen, Germany
- Institute of Pathology and Electron Microscopy Facility, RWTH University of Aachen, Aachen, Germany
- Department of Nephrology, Medical School, University of Ioannina, Ioannina, Greece
| | - Shipra Agrawal
- Division of Nephrology and Hypertension, Department of Medicine, Renaissance School of Medicine, Stony Brook University, Stony Brook, NY, USA
| | - Florian Siegerist
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Marc Buse
- Division of Nephrology and Clinical Immunology, RWTH Aachen University, Aachen, Germany
| | - Christoph Kuppe
- Division of Nephrology and Clinical Immunology, RWTH Aachen University, Aachen, Germany
- Institute of Experimental Medicine and Systems Biology, RWTH Aachen University, Aachen, Germany
| | - Tim Lange
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Eva Miriam Buhl
- Institute of Pathology and Electron Microscopy Facility, RWTH University of Aachen, Aachen, Germany
| | - Jessica Alam
- Division of Nephrology and Clinical Immunology, RWTH Aachen University, Aachen, Germany
| | - Thiago Strieder
- Division of Nephrology and Clinical Immunology, RWTH Aachen University, Aachen, Germany
| | - Peter Boor
- Division of Nephrology and Clinical Immunology, RWTH Aachen University, Aachen, Germany
- Institute of Pathology and Electron Microscopy Facility, RWTH University of Aachen, Aachen, Germany
| | - Tammo Ostendorf
- Division of Nephrology and Clinical Immunology, RWTH Aachen University, Aachen, Germany
| | | | - Jürgen Floege
- Division of Nephrology and Clinical Immunology, RWTH Aachen University, Aachen, Germany
| | - William E Smoyer
- Center for Clinical and Translational Research, Abigail Wexner Research Institute at Nationwide Children's Hospital, and Department of Pediatrics, The Ohio State University, College of Medicine, Columbus, OH, USA
| | - Nicole Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
- NIPOKA, Greifswald, Germany
| | - Marcus J Moeller
- Division of Nephrology and Clinical Immunology, RWTH Aachen University, Aachen, Germany
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2
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Schindler M, Endlich N. Zebrafish as a model for podocyte research. Am J Physiol Renal Physiol 2024; 326:F369-F381. [PMID: 38205541 DOI: 10.1152/ajprenal.00335.2023] [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: 10/18/2023] [Revised: 12/25/2023] [Accepted: 12/25/2023] [Indexed: 01/12/2024] Open
Abstract
Podocytes, specialized postmitotic cells, are central players in various kidney-related diseases. Zebrafish have become a valuable model system for studying podocyte biology because they are genetically easy to manipulate, transparent, and their glomerular structure is similar to that of mammals. This review provides an overview of the knowledge of podocyte biology in zebrafish larvae, with particular focus on their essential contribution to understanding the mechanisms that underlie kidney diseases as well as supporting drug development. In addition, special attention is given to advances in live-imaging techniques allowing the observation of dynamic processes, including podocyte motility, podocyte process behavior, and glomerulus maturation. The review further addresses the functional aspects of podocytes in zebrafish larvae. This includes topics such as glomerular filtration, ultrastructural analyses, and evaluation of podocyte response to nephrotoxic insults. Studies presented in this context have provided important insights into the maintenance and resistance of the glomerular filtration barrier in zebrafish larvae and explored the potential transferability of these findings to mammals such as mice, rats, and most importantly, humans. The recent ability to identify potential therapeutic targets represents a promising new way to identify drugs that could effectively treat podocyte-associated glomerulopathies in humans. In summary, this review gives an overview about the importance of zebrafish as a model for podocyte-related disease and targeted drug development. It also highlights the key role of advanced imaging techniques in transparent zebrafish larvae, improving our understanding of glomerular diseases and the significant potential for translation of these findings to humans.
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Affiliation(s)
- Maximilian Schindler
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Nicole Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
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3
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Schindler M, Siegerist F, Lange T, Simm S, Bach SM, Klawitter M, Gehrig J, Gul S, Endlich N. A Novel High-Content Screening Assay Identified Belinostat as Protective in a FSGS-Like Zebrafish Model. J Am Soc Nephrol 2023; 34:1977-1990. [PMID: 37752628 PMCID: PMC10703078 DOI: 10.1681/asn.0000000000000235] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 09/11/2023] [Indexed: 09/28/2023] Open
Abstract
BACKGROUND FSGS affects the complex three-dimensional morphology of podocytes, resulting in loss of filtration barrier function and the development of sclerotic lesions. Therapies to treat FSGS are limited, and podocyte-specific drugs are unavailable. To address the need for treatments to delay or stop FSGS progression, researchers are exploring the repurposing of drugs that have been approved by the US Food and Drug Administration (FDA) for other purposes. METHODS To identify drugs with potential to treat FSGS, we used a specific zebrafish screening strain to combine a high-content screening (HCS) approach with an in vivo model. This zebrafish screening strain expresses nitroreductase and the red fluorescent protein mCherry exclusively in podocytes (providing an indicator for podocyte depletion), as well as a circulating 78 kDa vitamin D-binding enhanced green fluorescent protein fusion protein (as a readout for proteinuria). To produce FSGS-like lesions in the zebrafish, we added 80 µ M metronidazole into the fish water. We used a specific screening microscope in conjunction with advanced image analysis methods to screen a library of 138 drugs and compounds (including some FDA-approved drugs) for podocyte-protective effects. Promising candidates were validated to be suitable for translational studies. RESULTS After establishing this novel in vivo HCS assay, we identified seven drugs or compounds that were protective in our FSGS-like model. Validation experiments confirmed that the FDA-approved drug belinostat was protective against larval FSGS. Similar pan-histone deacetylase inhibitors also showed potential to reproduce this effect. CONCLUSIONS Using an FSGS-like zebrafish model, we developed a novel in vivo HCS assay that identified belinostat and related pan-histone deacetylase inhibitors as potential candidates for treating FSGS.
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Affiliation(s)
- Maximilian Schindler
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Florian Siegerist
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Tim Lange
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Stefan Simm
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Hamburg, Germany
| | - Sophia-Marie Bach
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Marianne Klawitter
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | | | - Sheraz Gul
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Hamburg, Germany
- Fraunhofer Cluster of Excellence for Immune-Mediated Diseases CIMD, Hamburg, Germany
| | - Nicole Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
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4
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Michalik S, Siegerist F, Palankar R, Franzke K, Schindler M, Reder A, Seifert U, Cammann C, Wesche J, Steil L, Hentschker C, Gesell-Salazar M, Reisinger E, Beer M, Endlich N, Greinacher A, Völker U. Comparative analysis of ChAdOx1 nCoV-19 and Ad26.COV2.S SARS-CoV-2 vector vaccines. Haematologica 2022; 107:947-957. [PMID: 35045692 PMCID: PMC8968905 DOI: 10.3324/haematol.2021.280154] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 01/05/2021] [Indexed: 11/26/2022] Open
Abstract
Vector-based SARS-CoV-2 vaccines have been associated with vaccine- induced thrombosis with thrombocytopenia syndrome (VITT/TTS), but the causative factors are still unresolved. We comprehensively analyzed the ChAdOx1 nCoV-19 (AstraZeneca) and Ad26.COV2.S (Johnson and Johnson) vaccines. ChAdOx1 nCoV-19 contains significant amounts of host cell protein impurities, including functionally active proteasomes, and adenoviral proteins. A much smaller amount of impurities was found in Ad26.COV2.S. Platelet factor 4 formed complexes with ChAdOx1 nCoV-19 constituents, but not with purified virions from ChAdOx1 nCoV-19 or with Ad26.COV2.S. Vascular hyperpermeability was induced by ChAdOx nCoV-19 but not by Ad26.COV2.S. These differences in impurities together with EDTAinduced capillary leakage might contribute to the higher incidence rate of VITT associated with ChAdOx1 nCoV-19 compared to Ad26.COV2.S.
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Affiliation(s)
- Stephan Michalik
- Interfaculty Institute of Genetics and Functional Genomics, Department Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Florian Siegerist
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Raghavendra Palankar
- Institute of Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
| | - Kati Franzke
- Institute of Infectiology, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - Maximilian Schindler
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Alexander Reder
- Interfaculty Institute of Genetics and Functional Genomics, Department Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Ulrike Seifert
- Friedrich Loeffler-Institute of Medical Microbiology-Virology, University Medicine Greifswald, Greifswald, Germany
| | - Clemens Cammann
- Friedrich Loeffler-Institute of Medical Microbiology-Virology, University Medicine Greifswald, Greifswald, Germany
| | - Jan Wesche
- Institute of Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
| | - Leif Steil
- Interfaculty Institute of Genetics and Functional Genomics, Department Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Christian Hentschker
- Interfaculty Institute of Genetics and Functional Genomics, Department Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Manuela Gesell-Salazar
- Interfaculty Institute of Genetics and Functional Genomics, Department Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Emil Reisinger
- Division of Tropical Medicine and Infectious Diseases, Center of Internal Medicine II, Rostock University Medical Center, Rostock, Germany
| | - Martin Beer
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - Nicole Endlich
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Andreas Greinacher
- Institute of Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany.
| | - Uwe Völker
- Interfaculty Institute of Genetics and Functional Genomics, Department Functional Genomics, University Medicine Greifswald, Greifswald, Germany.
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5
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Evaluation of endogenous miRNA reference genes across different zebrafish strains, developmental stages and kidney disease models. Sci Rep 2021; 11:22894. [PMID: 34819534 PMCID: PMC8613261 DOI: 10.1038/s41598-021-00075-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 09/06/2021] [Indexed: 11/14/2022] Open
Abstract
The majority of kidney diseases arise from the loss of podocytes and from morphological changes of their highly complex foot process architecture, which inevitably leads to a reduced kidney filtration and total loss of kidney function. It could have been shown that microRNAs (miRs) play a pivotal role in the pathogenesis of podocyte-associated kidney diseases. Due to their fully functioning pronephric kidney, larval zebrafish have become a popular vertebrate model, to study kidney diseases in vivo. Unfortunately, there is no consensus about a proper normalization strategy of RT-qPCR-based miRNA expression data in zebrafish. In this study we analyzed 9 preselected candidates dre-miR-92a-3p, dre-miR-206-3p, dre-miR-99-1, dre-miR-92b-3p, dre-miR-363-3p, dre-let-7e, dre-miR-454a, dre-miR-30c-5p, dre-miR-126a-5p for their capability as endogenous reference genes in zebrafish experiments. Expression levels of potential candidates were measured in 3 different zebrafish strains, different developmental stages, and in different kidney disease models by RT-qPCR. Expression values were analyzed with NormFinder, BestKeeper, GeNorm, and DeltaCt and were tested for inter-group differences. All candidates show an abundant expression throughout all samples and relatively high stability. The most stable candidate without significant inter-group differences was dre-miR-92b-3p making it a suitable endogenous reference gene for RT-qPCR-based miR expression zebrafish studies.
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6
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van den Broek M, Smeets B, Schreuder MF, Jansen J. The podocyte as a direct target of glucocorticoids in nephrotic syndrome. Nephrol Dial Transplant 2021; 37:1808-1815. [PMID: 33515261 DOI: 10.1093/ndt/gfab016] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Indexed: 12/14/2022] Open
Abstract
Nephrotic syndrome (NS) is characterized by massive proteinuria; podocyte loss or altered function is a central event in its pathophysiology. Treatment with glucocorticoids is the mainstay of therapy. However, many patients experience one or multiple relapses and prolonged use may be associated with severe adverse effects. Recently, the beneficial effects of glucocorticoids have been attributed to a direct effect on podocytes in addition to the well-known immunosuppressive effects. The molecular effects of glucocorticoid action have been studied using animal and cell models of NS. This review provides a comprehensive overview of different molecular mediators regulated by glucocorticoids including an overview of the model systems that were used to study them. Glucocorticoids are described to stimulate podocyte recovery by restoring pro-survival signaling of slit diaphragm related proteins and limiting inflammatory responses. Of special interest is the effect of glucocorticoids on stabilizing the cytoskeleton of podocytes, since these effects are also described for other therapeutic agents used in NS, such as cyclosporin. Current models provide much insight, but do not fully recapitulate the human condition since the pathophysiology underlying NS is poorly understood. New and promising models include the glomerulus-on-a-chip and kidney organoids, which have the potential to be further developed into functional NS models in the future.
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Affiliation(s)
- Martijn van den Broek
- Department of Pathology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.,Department of Pediatric Nephrology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Amalia Children's Hospital, Nijmegen, The Netherlands
| | - Bart Smeets
- Department of Pathology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands
| | - Michiel F Schreuder
- Department of Pediatric Nephrology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Amalia Children's Hospital, Nijmegen, The Netherlands
| | - Jitske Jansen
- Department of Pathology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Nijmegen, The Netherlands.,Department of Pediatric Nephrology, Radboud Institute for Molecular Life Sciences, Radboud university medical center, Amalia Children's Hospital, Nijmegen, The Netherlands
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7
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Adriamycin does not damage podocytes of zebrafish larvae. PLoS One 2020; 15:e0242436. [PMID: 33186381 PMCID: PMC7665694 DOI: 10.1371/journal.pone.0242436] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 11/03/2020] [Indexed: 11/19/2022] Open
Abstract
Podocytes are highly specialized epithelial cells that are essential for an intact glomerular filtration barrier in the kidney. Several glomerular diseases like focal segmental glomerulosclerosis (FSGS) are initially due to podocyte injury and loss. Since causative treatments for FSGS are not available until today, drug screening is of great relevance. In order to test a high number of drugs, FSGS needs to be reliably induced in a suitable animal model. The zebrafish larva is an ideal model for kidney research due to the vast amount of offsprings, the rapid development of a simple kidney and a remarkable homology to the mammalian glomerulus. Zebrafish larvae possess a size-selective glomerular filtration barrier at 4 days post fertilization including podocytes with interdigitating foot processes that are connected by a slit membrane. Adriamycin is an anthracycline which is often used in mice and rats to induce a FSGS-like phenotype. In this study, we aimed to induce a similar phenotype to zebrafish larvae by adding adriamycin to the tank water in different concentrations. Surprisingly, zebrafish larvae did not develop glomerular injury and displayed an intact filtration barrier after treatment with adriamycin. This was shown by (immuno-) histology, our filtration assay, in vivo imaging by 2-photon microcopy, RT-(q)PCR as well as transmission electron microscopy. To summarize, adriamycin is unable to induce a podocyte-related damage in zebrafish larvae and therefore major effort must be made to establish FSGS in zebrafish larvae to identify effective drugs by screenings.
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8
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Hansen KUI, Siegerist F, Daniel S, Schindler M, Iervolino A, Blumenthal A, Daniel C, Amann K, Zhou W, Endlich K, Endlich N. Prolonged podocyte depletion in larval zebrafish resembles mammalian focal and segmental glomerulosclerosis. FASEB J 2020; 34:15961-15974. [PMID: 33070374 DOI: 10.1096/fj.202000724r] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 09/15/2020] [Accepted: 09/21/2020] [Indexed: 12/12/2022]
Abstract
Focal and segmental glomerulosclerosis (FSGS) is a histological pattern frequently found in patients with nephrotic syndrome that often progress to end-stage kidney disease. The initial step in development of this histologically defined entity is injury and ultimately depletion of podocytes, highly arborized interdigitating cells on the glomerular capillaries with important function for the glomerular filtration barrier. Since there are still no causal therapeutic options, animal models are needed to develop new treatment strategies. Here, we present an FSGS-like model in zebrafish larvae, an eligible vertebrate model for kidney research. In a transgenic zebrafish strain, podocytes were depleted, and the glomerular response was investigated by histological and morphometrical analysis combined with immunofluorescence staining and ultrastructural analysis by transmission electron microscopy. By intravenous injection of fluorescent high-molecular weight dextran, we confirmed leakage of the size selective filtration barrier. Additionally, we observed severe podocyte foot process effacement of remaining podocytes, activation of proximal tubule-like parietal epithelial cells identified by ultrastructural cytomorphology, and expression of proximal tubule markers. These activated cells deposited extracellular matrix on the glomerular tuft which are all hallmarks of FSGS. Our findings indicate that glomerular response to podocyte depletion in larval zebrafish resembles human FSGS in several important characteristics. Therefore, this model will help to investigate the disease development and the effects of potential drugs in a living organism.
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Affiliation(s)
| | - Florian Siegerist
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Sophie Daniel
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Maximilian Schindler
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Anna Iervolino
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany.,Biogem Research Institute Gaetano Salvatore, Ariano Irpino, Italy
| | - Antje Blumenthal
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Christoph Daniel
- Department of Nephropathology, Institute of Pathology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Kerstin Amann
- Department of Nephropathology, Institute of Pathology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Weibin Zhou
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York City, NY, USA
| | - Karlhans Endlich
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Nicole Endlich
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
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9
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Persson PB. Upcoming Acta Physiologica Award of US$ 100,000.00. Acta Physiol (Oxf) 2019; 227:e13369. [PMID: 31446678 DOI: 10.1111/apha.13369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 08/21/2019] [Indexed: 11/29/2022]
Affiliation(s)
- Pontus B Persson
- Charité- Universitätsmedizin Berlin, Corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Institute of Vegetative Physiology, Berlin, Germany
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10
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Elmonem MA, Berlingerio SP, van den Heuvel LP, de Witte PA, Lowe M, Levtchenko EN. Genetic Renal Diseases: The Emerging Role of Zebrafish Models. Cells 2018; 7:cells7090130. [PMID: 30200518 PMCID: PMC6162634 DOI: 10.3390/cells7090130] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Revised: 08/27/2018] [Accepted: 08/29/2018] [Indexed: 12/14/2022] Open
Abstract
The structural and functional similarity of the larval zebrafish pronephros to the human nephron, together with the recent development of easier and more precise techniques to manipulate the zebrafish genome have motivated many researchers to model human renal diseases in the zebrafish. Over the last few years, great advances have been made, not only in the modeling techniques of genetic diseases in the zebrafish, but also in how to validate and exploit these models, crossing the bridge towards more informative explanations of disease pathophysiology and better designed therapeutic interventions in a cost-effective in vivo system. Here, we review the significant progress in these areas giving special attention to the renal phenotype evaluation techniques. We further discuss the future applications of such models, particularly their role in revealing new genetic diseases of the kidney and their potential use in personalized medicine.
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Affiliation(s)
- Mohamed A Elmonem
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven-University of Leuven, Herestraat 49, Box 817, 3000 Leuven, Belgium.
- Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, 11628 Cairo, Egypt.
| | - Sante Princiero Berlingerio
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven-University of Leuven, Herestraat 49, Box 817, 3000 Leuven, Belgium.
| | - Lambertus P van den Heuvel
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven-University of Leuven, Herestraat 49, Box 817, 3000 Leuven, Belgium.
- Department of Pediatric Nephrology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands.
| | - Peter A de Witte
- Laboratory for Molecular Bio-Discovery, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven-University of Leuven, 3000 Leuven, Belgium.
| | - Martin Lowe
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK.
| | - Elena N Levtchenko
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven-University of Leuven, Herestraat 49, Box 817, 3000 Leuven, Belgium.
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11
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Ackermann S, Mrowka R. Nephropathy: New aspects of mechanisms, diagnosis and therapy. Acta Physiol (Oxf) 2018; 224:e13162. [PMID: 29984559 DOI: 10.1111/apha.13162] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Susanne Ackermann
- Klinik für Innere Medizin III; AG Experimentelle Nephrologie; Universitätsklinikum Jena; Jena Germany
| | - Ralf Mrowka
- Klinik für Innere Medizin III; AG Experimentelle Nephrologie; Universitätsklinikum Jena; Jena Germany
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12
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Endlich N, Lange T, Kuhn J, Klemm P, Kotb AM, Siegerist F, Kindt F, Lindenmeyer MT, Cohen CD, Kuss AW, Nath N, Rettig R, Lendeckel U, Zimmermann U, Amann K, Stracke S, Endlich K. BDNF: mRNA expression in urine cells of patients with chronic kidney disease and its role in kidney function. J Cell Mol Med 2018; 22:5265-5277. [PMID: 30133147 PMCID: PMC6201371 DOI: 10.1111/jcmm.13762] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 05/30/2018] [Indexed: 12/21/2022] Open
Abstract
Podocyte loss and changes to the complex morphology are major causes of chronic kidney disease (CKD). As the incidence is continuously increasing over the last decades without sufficient treatment, it is important to find predicting biomarkers. Therefore, we measured urinary mRNA levels of podocyte genes NPHS1, NPHS2, PODXL and BDNF, KIM‐1, CTSL by qRT‐PCR of 120 CKD patients. We showed a strong correlation between BDNF and the kidney injury marker KIM‐1, which were also correlated with NPHS1, suggesting podocytes as a contributing source. In human biopsies, BDNF was localized in the cell body and major processes of podocytes. In glomeruli of diabetic nephropathy patients, we found a strong BDNF signal in the remaining podocytes. An inhibition of the BDNF receptor TrkB resulted in enhanced podocyte dedifferentiation. The knockdown of the orthologue resulted in pericardial oedema formation and lowered viability of zebrafish larvae. We found an enlarged Bowman's space, dilated glomerular capillaries, podocyte loss and an impaired glomerular filtration. We demonstrated that BDNF is essential for glomerular development, morphology and function and the expression of BDNF and KIM‐1 is highly correlated in urine cells of CKD patients. Therefore, BDNF mRNA in urine cells could serve as a potential CKD biomarker.
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Affiliation(s)
- Nicole Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Tim Lange
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Jana Kuhn
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany.,Clinic for Diabetes and Metabolic Diseases, Karlsburg Hospital Dr. Guth GmbH & Co KG, Karlsburg, Germany
| | - Paul Klemm
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Ahmed M Kotb
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Florian Siegerist
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Frances Kindt
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Maja T Lindenmeyer
- Nephrological Center, Medical Clinic and Policlinic IV, University of Munich, Munich, Germany
| | - Clemens D Cohen
- Nephrological Center, Medical Clinic and Policlinic IV, University of Munich, Munich, Germany
| | - Andreas W Kuss
- Department of Functional Genomics, University Medicine Greifswald, Greifswald, Germany
| | - Neetika Nath
- Institute of Bioinformatics, University of Greifswald, Greifswald, Germany
| | - Rainer Rettig
- Department of Physiology, University of Greifswald, Karlsburg, Germany
| | - Uwe Lendeckel
- Department of Medical Biochemistry and Molecular Biology, University Medicine Greifswald, Greifswald, Germany
| | - Uwe Zimmermann
- Department of Urology, University Medicine Greifswald, Greifswald, Germany
| | - Kerstin Amann
- Department of Pathology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Sylvia Stracke
- Department of Internal Medicine A, University Medicine Greifswald, Greifswald, Germany
| | - Karlhans Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
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13
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Siegerist F, Endlich K, Endlich N. Novel Microscopic Techniques for Podocyte Research. Front Endocrinol (Lausanne) 2018; 9:379. [PMID: 30050501 PMCID: PMC6050355 DOI: 10.3389/fendo.2018.00379] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 06/22/2018] [Indexed: 01/16/2023] Open
Abstract
Together with endothelial cells and the glomerular basement membrane, podocytes form the size-specific filtration barrier of the glomerulus with their interdigitating foot processes. Since glomerulopathies are associated with so-called foot process effacement-a severe change of well-formed foot processes into flat and broadened processes-visualization of the three-dimensional podocyte morphology is a crucial part for diagnosis of nephrotic diseases. However, interdigitating podocyte foot processes are too narrow to be resolved by classic light microscopy due to Ernst Abbe's law making electron microscopy necessary. Although three dimensional electron microscopy approaches like serial block face and focused ion beam scanning electron microscopy and electron tomography allow volumetric reconstruction of podocytes, these techniques are very time-consuming and too specialized for routine use or screening purposes. During the last few years, different super-resolution microscopic techniques were developed to overcome the optical resolution limit enabling new insights into podocyte morphology. Super-resolution microscopy approaches like three dimensional structured illumination microscopy (3D-SIM), stimulated emission depletion microscopy (STED) and localization microscopy [stochastic optical reconstruction microscopy (STORM), photoactivated localization microscopy (PALM)] reach resolutions down to 80-20 nm and can be used to image and further quantify podocyte foot process morphology. Furthermore, in vivo imaging of podocytes is essential to study the behavior of these cells in situ. Therefore, multiphoton laser microscopy was a breakthrough for in vivo studies of podocytes in transgenic animal models like rodents and zebrafish larvae because it allows imaging structures up to several hundred micrometer in depth within the tissue. Additionally, along with multiphoton microscopy, lightsheet microscopy is currently used to visualize larger tissue volumes and therefore image complete glomeruli in their native tissue context. Alongside plain visualization of cellular structures, atomic force microscopy has been used to study the change of mechanical properties of podocytes in diseased states which has been shown to be a culprit in podocyte maintenance. This review discusses recent advances in the field of microscopic imaging and demonstrates their currently used and other possible applications for podocyte research.
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Affiliation(s)
| | | | - Nicole Endlich
- Institute for Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
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14
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Rider SA, Bruton FA, Collins RG, Conway BR, Mullins JJ. The Efficacy of Puromycin and Adriamycin for Induction of Glomerular Failure in Larval Zebrafish Validated by an Assay of Glomerular Permeability Dynamics. Zebrafish 2018; 15:234-242. [PMID: 29480793 PMCID: PMC5985910 DOI: 10.1089/zeb.2017.1527] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Defects in the glomerular filtration barrier (GFB) play a major role in the onset of human renal diseases. Highly ramified glomerular cells named podocytes are a critical component of the GFB. Injury to podocytes results in abnormal excretion of plasma proteins, which can lead to chronic kidney disease. The conserved paired nephron of larval zebrafish is an excellent model for assessing glomerular function and injury. The efficacy of two known podocyte toxins was tested to refine models of acute podocyte injury in larval zebrafish. The validated compound was then used to test a novel assay of the dynamics of abnormal protein excretion. Injected adriamycin was found to be unsuitable for induction of glomerular injury due to off-target cardiovascular toxicity. In contrast, puromycin treatment resulted in a loss of discriminative filtration, measured by excretion of 70 kDa dextran, and podocyte effacement confirmed by electron microscopy. The dynamics of dextran excretion during puromycin injury modeled the onset of glomerular damage within 24 hours postinjection. These data validate puromycin for induction of acute podocyte injury in zebrafish larvae and describe a semihigh-throughput assay for quantifying the dynamics of abnormal protein excretion.
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Affiliation(s)
- Sebastien Andrew Rider
- 1 Univeristy/BHF Centre for Cardiovascular Science, The Queen's Medical Research Institute, Little France, The University of Edinburgh , Edinburgh, United Kingdom
| | - Finnius Austin Bruton
- 1 Univeristy/BHF Centre for Cardiovascular Science, The Queen's Medical Research Institute, Little France, The University of Edinburgh , Edinburgh, United Kingdom
| | | | - Bryan Ronald Conway
- 1 Univeristy/BHF Centre for Cardiovascular Science, The Queen's Medical Research Institute, Little France, The University of Edinburgh , Edinburgh, United Kingdom
| | - John James Mullins
- 1 Univeristy/BHF Centre for Cardiovascular Science, The Queen's Medical Research Institute, Little France, The University of Edinburgh , Edinburgh, United Kingdom
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15
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Combined use of electron microscopy and intravital imaging captures morphological and functional features of podocyte detachment. Pflugers Arch 2017; 469:965-974. [PMID: 28664407 DOI: 10.1007/s00424-017-2020-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 06/13/2017] [Accepted: 06/14/2017] [Indexed: 12/12/2022]
Abstract
The development of podocyte injury and albuminuria in various glomerular pathologies is still incompletely understood due to technical limitations in studying the glomerular filtration barrier (GFB) in real-time. We aimed to directly visualize the early morphological and functional changes of the GFB during the development of focal segmental glomerulosclerosis (FSGS) using a combination of transmission electron microscopy (TEM) and in vivo multiphoton microscopy (MPM) in the rat puromycin aminonucleoside (PAN) model. We hypothesized that this combined TEM + MPM experimental approach would provide a major technical improvement that would benefit our mechanistic understanding of podocyte detachment. Male Sprague-Dawley (for TEM) or Munich-Wistar-Frömter (for MPM) rats were given a single dose of 100-150 mg/kg body weight PAN i.p. and were either sacrificed and the kidneys processed for TEM or surgically instrumented for in vivo MPM imaging at various times 2-14 days after PAN administration. Both techniques demonstrated hypertrophy and cystic dilatations of the subpodocyte space that developed as early as 2-3 days after PAN. Adhesions of the visceral epithelium to the parietal Bowman's capsule (synechiae) appeared at days 8-10. TEM provided unmatched resolution of podocyte foot process remodeling, while MPM revealed the rapid dynamics of pseudocyst filling, emptying, and rupture, as well as endothelial and podocyte injury, misdirected filtration, and podocyte shedding. Due to the complementary advantages of TEM and MPM, this combined approach can provide an unusally comprehensive and dynamic portrayal of the alterations in podocyte morphology and function during FSGS development. The results advance our understanding of the role and importance of the various cell types, hemodynamics, and mechanical forces in the development of glomerular pathology.
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16
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Bachmann S. From fish to nephrology: modelling glomerular function in Danio rerio larvae. Acta Physiol (Oxf) 2017; 220:16-18. [PMID: 27860407 DOI: 10.1111/apha.12833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- S. Bachmann
- Department of Anatomy; Charité Universitätsmedizin; Berlin Germany
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17
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Assady S, Wanner N, Skorecki KL, Huber TB. New Insights into Podocyte Biology in Glomerular Health and Disease. J Am Soc Nephrol 2017; 28:1707-1715. [PMID: 28404664 DOI: 10.1681/asn.2017010027] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Podocyte and glomerular research is center stage for the development of improved preventive and therapeutic strategies for chronic progressive kidney diseases. Held April 3-6, 2016, the 11th International Podocyte Conference took place in Haifa and Jerusalem, Israel, where participants from all over the world presented their work on new developments in podocyte research. In this review, we briefly highlight the advances made in characterizing the mechanisms involved in podocyte development, metabolism, acquired injury, and repair, including progress in determining the roles of genetic variants and microRNA in particular, as well as the advances made in diagnostic techniques and therapeutics.
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Affiliation(s)
- Suheir Assady
- Department of Nephrology and Hypertension, Rambam Health Care Campus, Haifa, Israel.,Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Nicola Wanner
- Department of Medicine IV, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Karl L Skorecki
- Department of Nephrology and Hypertension, Rambam Health Care Campus, Haifa, Israel; .,Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Tobias B Huber
- Department of Medicine IV, Faculty of Medicine, University of Freiburg, Freiburg, Germany; .,BIOSS-Centre for Biological Signalling Studies and.,III. Medizinische Klinik, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany.,ZBSA-Center for Biological Systems Analysis, Albert Ludwigs University, Freiburg, Germany; and
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18
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Schenk H, Müller-Deile J, Kinast M, Schiffer M. Disease modeling in genetic kidney diseases: zebrafish. Cell Tissue Res 2017; 369:127-141. [PMID: 28331970 DOI: 10.1007/s00441-017-2593-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 02/22/2017] [Indexed: 01/07/2023]
Abstract
Growing numbers of translational genomics studies are based on the highly efficient and versatile zebrafish (Danio rerio) vertebrate model. The increasing types of zebrafish models have improved our understanding of inherited kidney diseases, since they not only display pathophysiological changes but also give us the opportunity to develop and test novel treatment options in a high-throughput manner. New paradigms in inherited kidney diseases have been developed on the basis of the distinct genome conservation of approximately 70 % between zebrafish and humans in terms of existing gene orthologs. Several options are available to determine the functional role of a specific gene or gene sets. Permanent genome editing can be induced via complete gene knockout by using the CRISPR/Cas-system, among others, or via transient modification by using various morpholino techniques. Cross-species rescues succeeding knockdown techniques are employed to determine the functional significance of a target gene or a specific mutation. This article summarizes the current techniques and discusses their perspectives.
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Affiliation(s)
- Heiko Schenk
- Department of Medicine/Nephrology, Hannover Medical School, Hannover, Germany
- Mount Desert Island Biological Laboratory, Salisbury Cove, Bar Harbor, Me., USA
| | - Janina Müller-Deile
- Department of Medicine/Nephrology, Hannover Medical School, Hannover, Germany
- Mount Desert Island Biological Laboratory, Salisbury Cove, Bar Harbor, Me., USA
| | - Mark Kinast
- Department of Medicine/Nephrology, Hannover Medical School, Hannover, Germany
- Mount Desert Island Biological Laboratory, Salisbury Cove, Bar Harbor, Me., USA
| | - Mario Schiffer
- Department of Medicine/Nephrology, Hannover Medical School, Hannover, Germany.
- Mount Desert Island Biological Laboratory, Salisbury Cove, Bar Harbor, Me., USA.
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19
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Siegerist F, Blumenthal A, Zhou W, Endlich K, Endlich N. Acute podocyte injury is not a stimulus for podocytes to migrate along the glomerular basement membrane in zebrafish larvae. Sci Rep 2017; 7:43655. [PMID: 28252672 PMCID: PMC5333633 DOI: 10.1038/srep43655] [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: 10/13/2016] [Accepted: 01/26/2017] [Indexed: 12/28/2022] Open
Abstract
Podocytes have a unique 3D structure of major and interdigitating foot processes which is the prerequisite for renal blood filtration. Loss of podocytes leads to chronic kidney disease ending in end stage renal disease. Until now, the question if podocytes can be replaced by immigration of cells along the glomerular basement membrane (GBM) is under debate. We recently showed that in contrast to former theories, podocytes are stationary in the zebrafish pronephros and neither migrate nor change their branching pattern of major processes over 23 hours. However, it was still unclear whether podocytes are able to migrate during acute injury. To investigate this, we applied the nitroreductase/metronidazole zebrafish model of podocyte injury to in vivo two-photon microscopy. The application of metronidazole led to retractions of major processes associated with a reduced expression of podocyte-specific proteins and a formation of subpodocyte pseudocyst. Electron microscopy showed that broad areas of the capillaries became denuded. By 4D in vivo observation of single podocytes, we could show that the remaining podocytes did not walk along GBM during 24 h. This in vivo study reveals that podocytes are very stationary cells making regenerative processes by podocyte walking along the GBM very unlikely.
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Affiliation(s)
- Florian Siegerist
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Antje Blumenthal
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Weibin Zhou
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, Michigan, USA
| | - Karlhans Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Nicole Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
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20
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Thomasova D, Ebrahim M, Fleckinger K, Li M, Molnar J, Popper B, Liapis H, Kotb AM, Siegerist F, Endlich N, Anders HJ. MDM2 prevents spontaneous tubular epithelial cell death and acute kidney injury. Cell Death Dis 2016; 7:e2482. [PMID: 27882940 PMCID: PMC5260907 DOI: 10.1038/cddis.2016.390] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 10/21/2016] [Accepted: 10/25/2016] [Indexed: 12/24/2022]
Abstract
Murine double minute-2 (MDM2) is an E3-ubiquitin ligase and the main negative regulator of tumor suppressor gene p53. MDM2 has also a non-redundant function as a modulator of NF-kB signaling. As such it promotes proliferation and inflammation. MDM2 is highly expressed in the unchallenged tubular epithelial cells and we hypothesized that MDM2 is necessary for their survival and homeostasis. MDM2 knockdown by siRNA or by genetic depletion resulted in demise of tubular cells in vitro. This phenotype was completely rescued by concomitant knockdown of p53, thus suggesting p53 dependency. In vivo experiments in the zebrafish model demonstrated that the tubulus cells of the larvae undergo cell death after the knockdown of mdm2. Doxycycline-induced deletion of MDM2 in tubular cell-specific MDM2-knockout mice Pax8rtTa-cre; MDM2f/f caused acute kidney injury with increased plasma creatinine and blood urea nitrogen and sharp decline of glomerular filtration rate. Histological analysis showed massive swelling of renal tubular cells and later their loss and extensive tubular dilation, markedly in proximal tubules. Ultrastructural changes of tubular epithelial cells included swelling of the cytoplasm and mitochondria with the loss of cristae and their transformation in the vacuoles. The pathological phenotype of the tubular cell-specific MDM2-knockout mouse model was completely rescued by co-deletion of p53. Tubular epithelium compensates only partially for the cell loss caused by MDM2 depletion by proliferation of surviving tubular cells, with incomplete MDM2 deletion, but rather mesenchymal healing occurs. We conclude that MDM2 is a non-redundant survival factor for proximal tubular cells by protecting them from spontaneous p53 overexpression-related cell death.
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Affiliation(s)
- Dana Thomasova
- Nephrologisches Zentrum, Medizinische Klinik und Poliklinik IV, Klinikum der LMU München, Munich, Germany
| | - Martrez Ebrahim
- Nephrologisches Zentrum, Medizinische Klinik und Poliklinik IV, Klinikum der LMU München, Munich, Germany
| | - Kristina Fleckinger
- Nephrologisches Zentrum, Medizinische Klinik und Poliklinik IV, Klinikum der LMU München, Munich, Germany
| | - Moying Li
- Nephrologisches Zentrum, Medizinische Klinik und Poliklinik IV, Klinikum der LMU München, Munich, Germany
| | - Jakob Molnar
- Nephrologisches Zentrum, Medizinische Klinik und Poliklinik IV, Klinikum der LMU München, Munich, Germany
| | - Bastian Popper
- Department of Anatomy and Cell Biology, Ludwig-Maximilians Universität, Munich, Germany
| | - Helen Liapis
- Pathology & Immunology & Internal Medicine (Renal), Washington University, School of Medicine, St Louis, MO, USA
| | - Ahmed M Kotb
- Department of Anatomy and Cell Biology, Universitätsmedizin Greifswald, Greifswald, Germany
- Department of Anatomy and Histology, Faculty of Veterinary Medicine, Assiut University, Assiut, Egypt
| | - Florian Siegerist
- Department of Anatomy and Cell Biology, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Nicole Endlich
- Department of Anatomy and Cell Biology, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Hans-Joachim Anders
- Nephrologisches Zentrum, Medizinische Klinik und Poliklinik IV, Klinikum der LMU München, Munich, Germany
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