1
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Chen C, Xiong K, Li K, Zhou B, Cheng J, Zhu B, Zheng L, Zhao J. Identification of key genes involved in collagen hydrogel-induced chondrogenic differentiation of mesenchymal stem cells through transcriptome analysis: the role of m6A modification. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2024; 35:43. [PMID: 39073623 PMCID: PMC11286723 DOI: 10.1007/s10856-024-06801-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Accepted: 05/16/2024] [Indexed: 07/30/2024]
Abstract
Collagen hydrogel has been shown promise as an inducer for chondrogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), contributing to the repair of cartilage defects. However, the precise molecular mechanism underlying this phenomenon remains poorly elucidated. Here, we induced chondrogenic differentiation of BMSCs using collagen hydrogel and identified 4451 differentially expressed genes (DEGs) through transcriptomic sequencing. Our analysis revealed that DEGs were enriched in the focal adhesion pathway, with a notable decrease in expression levels in the collagen hydrogel group compared to the control group. Protein-protein interaction network analysis suggested that actinin alpha 1 (ACTN1) and actinin alpha 4 (ACTN4), two proteins also involved in cytoskeletal recombination, may be crucial in collagen hydrogel-induced chondrogenic differentiation of BMSCs. Additionally, we found that N6-methyladenosine RNA methylation (m6A) modification was involved in collagen hydrogel-mediated chondrogenic differentiation, with fat mass and obesity-associated protein (FTO) implicated in regulating the expression of ACTN1 and ACTN4. These findings suggest that collagen hydrogel might regulate focal adhesion and actin cytoskeletal signaling pathways through down-regulation of ACTN1 and ACTN4 mRNA via FTO-mediated m6A modification, ultimately driving chondrogenic differentiation of BMSCs. In conclusion, our study provides valuable insights into the molecular mechanisms of collagen hydrogel-induced chondrogenic differentiation of BMSCs, which may aid in developing more effective strategies for cartilage regeneration.
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Affiliation(s)
- Chaotao Chen
- Guangxi Engineering Center in Biomedical Materials for Tissue and Organ Regeneration, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China
- Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-constructed by the Province and Ministry, Guangxi Medical University, Nanning, 530021, China
- Department of Orthopaedics Trauma and HandSurgery, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China
| | - Kai Xiong
- Guangxi Engineering Center in Biomedical Materials for Tissue and Organ Regeneration, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China
- Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-constructed by the Province and Ministry, Guangxi Medical University, Nanning, 530021, China
- Department of Orthopaedics Trauma and HandSurgery, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China
- Department of Orthopaedics Trauma and HandSurgery, The Third Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530031, China
| | - Kanglu Li
- Guangxi Engineering Center in Biomedical Materials for Tissue and Organ Regeneration, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China
- Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-constructed by the Province and Ministry, Guangxi Medical University, Nanning, 530021, China
- Department of Orthopaedics Trauma and HandSurgery, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China
| | - Bo Zhou
- Guangxi Engineering Center in Biomedical Materials for Tissue and Organ Regeneration, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China
- Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-constructed by the Province and Ministry, Guangxi Medical University, Nanning, 530021, China
| | - Jianwen Cheng
- Guangxi Engineering Center in Biomedical Materials for Tissue and Organ Regeneration, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China.
- Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-constructed by the Province and Ministry, Guangxi Medical University, Nanning, 530021, China.
- Department of Orthopaedics Trauma and HandSurgery, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China.
| | - Bo Zhu
- Guangxi Engineering Center in Biomedical Materials for Tissue and Organ Regeneration, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China.
- Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-constructed by the Province and Ministry, Guangxi Medical University, Nanning, 530021, China.
- International Joint Laboratory of Ministry of Education for Regeneration of Bone and Soft Tissues, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China.
- Guangxi Key Laboratory of Regenerative Medicine, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China.
| | - Li Zheng
- Guangxi Engineering Center in Biomedical Materials for Tissue and Organ Regeneration, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China.
- Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-constructed by the Province and Ministry, Guangxi Medical University, Nanning, 530021, China.
- International Joint Laboratory of Ministry of Education for Regeneration of Bone and Soft Tissues, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China.
| | - Jinmin Zhao
- Guangxi Engineering Center in Biomedical Materials for Tissue and Organ Regeneration, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China
- Collaborative Innovation Centre of Regenerative Medicine and Medical BioResource Development and Application Co-constructed by the Province and Ministry, Guangxi Medical University, Nanning, 530021, China
- Department of Orthopaedics Trauma and HandSurgery, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China
- International Joint Laboratory of Ministry of Education for Regeneration of Bone and Soft Tissues, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China
- Guangxi Key Laboratory of Regenerative Medicine, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, 530021, China
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2
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Batool L, Hariharan K, Xu Y, Kaßmann M, Tsvetkov D, Gohlke BO, Kaden S, Gossen M, Nürnberg B, Kurtz A, Gollasch M. An inactivating human TRPC6 channel mutation without focal segmental glomerulosclerosis. Cell Mol Life Sci 2023; 80:265. [PMID: 37615749 PMCID: PMC10449997 DOI: 10.1007/s00018-023-04901-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 07/27/2023] [Accepted: 07/28/2023] [Indexed: 08/25/2023]
Abstract
Transient receptor potential cation channel-6 (TRPC6) gene mutations cause familial focal segmental glomerulosclerosis (FSGS), which is inherited as an autosomal dominant disease. In patients with TRPC6-related FSGS, all mutations map to the N- or C-terminal TRPC6 protein domains. Thus far, the majority of TRPC6 mutations are missense resulting in increased or decreased calcium influx; however, the fundamental molecular mechanisms causing cell injury and kidney pathology are unclear. We report a novel heterozygous TRPC6 mutation (V691Kfs*) in a large kindred with no signs of FSGS despite a largely truncated TRPC6 protein. We studied the molecular effects of V691Kfs* TRPC6 mutant using the tridimensional cryo-EM structure of the tetrameric TRPC6 protein. The results indicated that V691 is localized at the pore-forming transmembrane region affecting the ion conduction pathway, and predicted that V691Kfs* causes closure of the ion-conducting pathway leading to channel inactivation. We assessed the impact of V691Kfs* and two previously reported TRPC6 disease mutants (P112Q and G757D) on calcium influx in cells. Our data show that the V691Kfs* fully inactivated the TRCP6 channel-specific calcium influx consistent with a complete loss-of-function phenotype. Furthermore, the V691Kfs* truncation exerted a dominant negative effect on the full-length TRPC6 proteins. In conclusion, the V691Kfs* non-functional truncated TRPC6 is not sufficient to cause FSGS. Our data corroborate recently characterized TRPC6 loss-of-function and gain-of-function mutants suggesting that one defective TRPC6 gene copy is not sufficient to cause FSGS. We underscore the importance of increased rather than reduced calcium influx through TRPC6 for podocyte cell death.
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Affiliation(s)
- Lilas Batool
- BIH Center for Regenerative Therapies (BCRT), Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
| | - Krithika Hariharan
- BIH Center for Regenerative Therapies (BCRT), Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
- Fraunhofer-Institute for Biomedical Engineering (IBMT), Fraunhofer Project Center for Stem Cell Process Engineering, Würzburg, Germany
| | - Yao Xu
- Klinik und Poliklinik für Innere Medizin D-Geriatrie, Universitätsmedizin Greifswald, Ferdinand-Sauerbruch-Straße, Greifswald, Germany
| | - Mario Kaßmann
- Klinik und Poliklinik für Innere Medizin D-Geriatrie, Universitätsmedizin Greifswald, Ferdinand-Sauerbruch-Straße, Greifswald, Germany
| | - Dmitry Tsvetkov
- Klinik und Poliklinik für Innere Medizin D-Geriatrie, Universitätsmedizin Greifswald, Ferdinand-Sauerbruch-Straße, Greifswald, Germany
| | - Björn-Oliver Gohlke
- Department of Information Technology, Science-IT, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Sylvia Kaden
- Electron Microscopy Core Facility, German Cancer Research Center, Heidelberg, Germany
| | - Manfred Gossen
- BIH Center for Regenerative Therapies (BCRT), Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
- Institut für Aktive Polymere, Hereon TeltowAbteilung Stammzellmodifikation und Biomaterialien, Teltow, Germany
| | - Bernd Nürnberg
- Department of Pharmacology, Experimental Therapy and Toxicology, Institute of Experimental and Clinical Pharmacology and Pharmacogenomics, University of Tübingen, Tübingen, Germany
| | - Andreas Kurtz
- BIH Center for Regenerative Therapies (BCRT), Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany.
- Biomedical Data and Bioethics, Fraunhofer-Institute for Biomedical Engineering (IBMT), Berlin, Germany.
| | - Maik Gollasch
- Klinik und Poliklinik für Innere Medizin D-Geriatrie, Universitätsmedizin Greifswald, Ferdinand-Sauerbruch-Straße, Greifswald, Germany.
- Klinik für Nephrologie und Internistische Intensivmedizin, Charité-Universitätsmedizin Berlin, Berlin, Germany.
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3
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Staruschenko A, Ma R, Palygin O, Dryer SE. Ion channels and channelopathies in glomeruli. Physiol Rev 2023; 103:787-854. [PMID: 36007181 PMCID: PMC9662803 DOI: 10.1152/physrev.00013.2022] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 08/15/2022] [Accepted: 08/21/2022] [Indexed: 11/22/2022] Open
Abstract
An essential step in renal function entails the formation of an ultrafiltrate that is delivered to the renal tubules for subsequent processing. This process, known as glomerular filtration, is controlled by intrinsic regulatory systems and by paracrine, neuronal, and endocrine signals that converge onto glomerular cells. In addition, the characteristics of glomerular fluid flow, such as the glomerular filtration rate and the glomerular filtration fraction, play an important role in determining blood flow to the rest of the kidney. Consequently, disease processes that initially affect glomeruli are the most likely to lead to end-stage kidney failure. The cells that comprise the glomerular filter, especially podocytes and mesangial cells, express many different types of ion channels that regulate intrinsic aspects of cell function and cellular responses to the local environment, such as changes in glomerular capillary pressure. Dysregulation of glomerular ion channels, such as changes in TRPC6, can lead to devastating glomerular diseases, and a number of channels, including TRPC6, TRPC5, and various ionotropic receptors, are promising targets for drug development. This review discusses glomerular structure and glomerular disease processes. It also describes the types of plasma membrane ion channels that have been identified in glomerular cells, the physiological and pathophysiological contexts in which they operate, and the pathways by which they are regulated and dysregulated. The contributions of these channels to glomerular disease processes, such as focal segmental glomerulosclerosis (FSGS) and diabetic nephropathy, as well as the development of drugs that target these channels are also discussed.
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Affiliation(s)
- Alexander Staruschenko
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida
- Hypertension and Kidney Research Center, University of South Florida, Tampa, Florida
- James A. Haley Veterans Hospital, Tampa, Florida
| | - Rong Ma
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Oleg Palygin
- Division of Nephrology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina
| | - Stuart E Dryer
- Department of Biology and Biochemistry, University of Houston, Houston, Texas
- Department of Biomedical Sciences, Tilman J. Fertitta Family College of Medicine, University of Houston, Houston, Texas
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4
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Tseng CC, Zheng RH, Lin TW, Chou CC, Shih YC, Liang SW, Lee HH. α-Actinin-4 recruits Shp2 into focal adhesions to potentiate ROCK2 activation in podocytes. Life Sci Alliance 2022; 5:5/11/e202201557. [PMID: 36096674 PMCID: PMC9468603 DOI: 10.26508/lsa.202201557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 08/20/2022] [Accepted: 08/22/2022] [Indexed: 11/24/2022] Open
Abstract
α-Actinin-4 is crucial in the regulation of Shp2 FA targeting to enhance ROCK2-mediated actomyosin contractility and thereby strengthening cell adhesion and cytoskeletal architecture in podocytes. Cell–matrix adhesions are mainly provided by integrin-mediated focal adhesions (FAs). We previously found that Shp2 is essential for FA maturation by promoting ROCK2 activation at FAs. In this study, we further delineated the role of α-actinin-4 in the FA recruitment and activation of Shp2. We used the conditional immortalized mouse podocytes to examine the role of α-actinin-4 in the regulation of Shp2 and ROCK2 signaling. After the induction of podocyte differentiation, Shp2 and ROCK2 were strongly activated, concomitant with the formation of matured FAs, stress fibers, and interdigitating intracellular junctions in a ROCK-dependent manner. Gene knockout of α-actinin-4 abolished the Shp2 activation and subsequently reduced matured FAs in podocytes. We also demonstrated that gene knockout of ROCK2 impaired the generation of contractility and interdigitating intercellular junctions. Our results reveal the role of α-actinin-4 in the recruitment of Shp2 at FAs to potentiate ROCK2 activation for the maintenance of cellular contractility and cytoskeletal architecture in the cultured podocytes.
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Affiliation(s)
- Chien-Chun Tseng
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Ru-Hsuan Zheng
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Ting-Wei Lin
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Chih-Chiang Chou
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yu-Chia Shih
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Shao-Wei Liang
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Hsiao-Hui Lee
- Department of Life Sciences and Institute of Genome Sciences, National Yang Ming Chiao Tung University, Taipei, Taiwan .,Center for Intelligent Drug Systems and Smart Bio-Devices (IDS2B), National Yang Ming Chiao Tung University, Taipei, Taiwan
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5
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Odenthal J, Dittrich S, Ludwig V, Merz T, Reitmeier K, Reusch B, Höhne M, Cosgun ZC, Hohenadel M, Putnik J, Göbel H, Rinschen MM, Altmüller J, Koehler S, Schermer B, Benzing T, Beck BB, Brinkkötter PT, Habbig S, Bartram MP. Modeling of ACTN4-Based Podocytopathy Using Drosophila Nephrocytes. Kidney Int Rep 2022; 8:317-329. [PMID: 36815115 PMCID: PMC9939316 DOI: 10.1016/j.ekir.2022.10.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/17/2022] [Accepted: 10/24/2022] [Indexed: 11/06/2022] Open
Abstract
Introduction Genetic disorders are among the most prevalent causes leading to progressive glomerular disease and, ultimately, end-stage renal disease (ESRD) in children and adolescents. Identification of underlying genetic causes is indispensable for targeted treatment strategies and counseling of affected patients and their families. Methods Here, we report on a boy who presented at 4 years of age with proteinuria and biopsy-proven focal segmental glomerulosclerosis (FSGS) that was temporarily responsive to treatment with ciclosporin A. Molecular genetic testing identified a novel mutation in alpha-actinin-4 (p.M240T). We describe a feasible and efficient experimental approach to test its pathogenicity by combining in silico, in vitro, and in vivo analyses. Results The de novo p.M240T mutation led to decreased alpha-actinin-4 stability as well as protein mislocalization and actin cytoskeleton rearrangements. Transgenic expression of wild-type human alpha-actinin-4 in Drosophila melanogaster nephrocytes was able to ameliorate phenotypes associated with the knockdown of endogenous actinin. In contrast, p.M240T, as well as other established disease variants p.W59R and p.K255E, failed to rescue these phenotypes, underlining the pathogenicity of the novel alpha-actinin-4 variant. Conclusion Our data highlight that the newly identified alpha-actinin-4 mutation indeed encodes for a disease-causing variant of the protein and promote the Drosophila model as a simple and convenient tool to study monogenic kidney disease in vivo.
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Affiliation(s)
- Johanna Odenthal
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Sebastian Dittrich
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Vivian Ludwig
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Tim Merz
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Katrin Reitmeier
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Björn Reusch
- Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany,Institute of Human Genetics, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Martin Höhne
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Zülfü C. Cosgun
- Department of Pediatrics, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Maximilian Hohenadel
- Department of Pediatrics, Division of Pediatric Nephrology, University of Bonn, Bonn, Germany
| | - Jovana Putnik
- Mother and Child Health Care Institute of Serbia “Dr Vukan Čupić,” Department of Nephrology, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Heike Göbel
- Institute of Pathology, University Hospital of Cologne, Cologne, Germany
| | - Markus M. Rinschen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark,Aarhus Institute of Advanced Studies, Aarhus University, Aarhus, Denmark,III Medical Clinic, University Hospital Hamburg Eppendorf, Hamburg, Germany
| | - Janine Altmüller
- Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Max Delbrück Center for Molecular Medicine, Berlin, Germany,Cologne Center for Genomics, University of Cologne, Cologne, Germany
| | - Sybille Koehler
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Bernhard Schermer
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Thomas Benzing
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Bodo B. Beck
- Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany,Institute of Human Genetics, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Paul T. Brinkkötter
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany,Correspondence: Paul T. Brinkkoetter, Department II of Internal Medicine, Faculty of Medicine, University of Cologne, University Hospital Cologne, Kerpener Street 62, Cologne 50935, Germany.
| | - Sandra Habbig
- Department of Pediatrics, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Malte P. Bartram
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
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6
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Brown BJ, Boekell KL, Stotter BR, Talbot BE, Schlondorff JS. Gain-of-function, focal segmental glomerulosclerosis Trpc6 mutation minimally affects susceptibility to renal injury in several mouse models. PLoS One 2022; 17:e0272313. [PMID: 35913909 PMCID: PMC9342776 DOI: 10.1371/journal.pone.0272313] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 07/18/2022] [Indexed: 11/18/2022] Open
Abstract
Mutations in TRPC6 are a cause of autosomal dominant focal segmental glomerulosclerosis in humans. Many of these mutations are known to have a gain-of-function effect on the non-specific cation channel function of TRPC6. In vitro studies have suggested these mutations affect several signaling pathways, but in vivo studies have largely compared wild-type and Trpc6-deficient rodents. We developed mice carrying a gain-of-function Trpc6 mutation encoding an E896K amino acid change, corresponding to a known FSGS mutation in TRPC6. Homozygous mutant Trpc6 animals have no appreciable renal pathology, and do not develop albuminuria until very advanced age. The Trpc6E896K mutation does not impart susceptibility to PAN nephrosis. The animals show a slight delay in recovery from the albumin overload model. In response to chronic angiotensin II infusion, Trpc6E896K/E896K mice have slightly greater albuminuria initially compared to wild-type animals, an effect that is lost at later time points, and a statistically non-significant trend toward more glomerular injury. This phenotype is nearly opposite to that of Trpc6-deficient animals previously described. The Trpc6 mutation does not appreciably impact renal interstitial fibrosis in response to either angiotensin II infusion, or folate-induced kidney injury. TRPC6 protein and TRPC6-agonist induced calcium influx could not be detected in glomeruli. In sum, these findings suggest that a gain-of-function Trpc6 mutation confers only a mild susceptibility to glomerular injury in the mouse.
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Affiliation(s)
- Brittney J. Brown
- Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Kimber L. Boekell
- Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Brian R. Stotter
- Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Division of Nephrology, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Brianna E. Talbot
- Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Johannes S. Schlondorff
- Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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7
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Li Y, Gong W, Liu J, Chen X, Suo Y, Yang H, Gao X. Angiopoietin-like protein 4 promotes hyperlipidemia-induced renal injury by down-regulating the expression of ACTN4. Biochem Biophys Res Commun 2022; 595:69-75. [PMID: 35101665 DOI: 10.1016/j.bbrc.2022.01.061] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 01/05/2022] [Accepted: 01/15/2022] [Indexed: 11/02/2022]
Abstract
OBJECTIVE The molecular mechanism of in hyperlipidemia-induced renal injury has not been elucidated. Angiogenin-like protein 4 (ANGPTL4) is a key regulator of lipid metabolism. The role of ANGPTL4 hyperlipidemia-induced renal injury has not been reported. METHODS Wild type C57 mice and gene angptl4 knockout mice were fed with 60% high fat diet or normal diet respectively. The serum lipid, urinary albumin and renal pathology were tested at the 9th, 13th, 17th and 21st week with high fat diet. RESULTS Elevated blood lipids in the wild-type mice with high-fat diet were found at 9th week. At the 17th week, the level of urinary albumin in high-fat fed wild type mice were significantly higher than which with normal diet, correspondingly, segmental fusion of podocyte foot process in kidney could be observed in these hyperlipidemia mice. IHC showed that the expression of ANGPTL4 in glomeruli of high-fat fed wild type mice began significant elevated since the 9th week. When given high fat diet, compared to the wild type, the gene angptl4 knockout mice showed significantly alleviated the levels of hyperlipidemia, proteinuria and effacement of podocyte foot process. Finally, the expression of ACTN4 showed remarkably lower in glomeruli podocyte of wild type mice fed high fat diet than that of wild type mice with normal diet at each time-point (P < 0.01). Differently, the expression of ACTN4 in gene angptl4 knockout mice did not happen significantly weaken when given the same dose of high fat diet. CONCLUSION ANGPTL4 could play a role in hyperlipidemic-induced renal injury via down-regulating the expression of ACTN4 in kidney podocyte.
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Affiliation(s)
- Yue Li
- Nephrology Department, Guangzhou Women and Children's Medical Center, Guangzhou, 510000, China
| | - Wangqiu Gong
- Nephrology Department, Guangzhou Women and Children's Medical Center, Guangzhou, 510000, China
| | - Jing Liu
- Pediatric Department, Gansu Province People's Hospital, Lanzhou City, 730000, China
| | - Xingxing Chen
- Pediatric Department, Gansu Province People's Hospital, Lanzhou City, 730000, China
| | - Yanhong Suo
- Pediatric Department, Gansu Province People's Hospital, Lanzhou City, 730000, China
| | - Huabing Yang
- Nephrology Department, Guangzhou Women and Children's Medical Center, Guangzhou, 510000, China
| | - Xia Gao
- Nephrology Department, Guangzhou Women and Children's Medical Center, Guangzhou, 510000, China.
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8
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Agarwal S, Sudhini YR, Polat OK, Reiser J, Altintas MM. Renal cell markers: lighthouses for managing renal diseases. Am J Physiol Renal Physiol 2021; 321:F715-F739. [PMID: 34632812 DOI: 10.1152/ajprenal.00182.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Kidneys, one of the vital organs in our body, are responsible for maintaining whole body homeostasis. The complexity of renal function (e.g., filtration, reabsorption, fluid and electrolyte regulation, and urine production) demands diversity not only at the level of cell types but also in their overall distribution and structural framework within the kidney. To gain an in depth molecular-level understanding of the renal system, it is imperative to discern the components of kidney and the types of cells residing in each of the subregions. Recent developments in labeling, tracing, and imaging techniques have enabled us to mark, monitor, and identify these cells in vivo with high efficiency in a minimally invasive manner. In this review, we summarize different cell types, specific markers that are uniquely associated with those cell types, and their distribution in the kidney, which altogether make kidneys so special and different. Cellular sorting based on the presence of certain proteins on the cell surface allowed for the assignment of multiple markers for each cell type. However, different studies using different techniques have found contradictions in cell type-specific markers. Thus, the term "cell marker" might be imprecise and suboptimal, leading to uncertainty when interpreting the data. Therefore, we strongly believe that there is an unmet need to define the best cell markers for a cell type. Although the compendium of renal-selective marker proteins presented in this review is a resource that may be useful to researchers, we acknowledge that the list may not be necessarily exhaustive.
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Affiliation(s)
- Shivangi Agarwal
- Department of Internal Medicine, Rush University, Chicago, Illinois
| | | | - Onur K Polat
- Department of Internal Medicine, Rush University, Chicago, Illinois
| | - Jochen Reiser
- Department of Internal Medicine, Rush University, Chicago, Illinois
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9
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Daehn IS, Duffield JS. The glomerular filtration barrier: a structural target for novel kidney therapies. Nat Rev Drug Discov 2021; 20:770-788. [PMID: 34262140 PMCID: PMC8278373 DOI: 10.1038/s41573-021-00242-0] [Citation(s) in RCA: 93] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/28/2021] [Indexed: 12/19/2022]
Abstract
Loss of normal kidney function affects more than 10% of the population and contributes to morbidity and mortality. Kidney diseases are currently treated with immunosuppressive agents, antihypertensives and diuretics with partial but limited success. Most kidney disease is characterized by breakdown of the glomerular filtration barrier (GFB). Specialized podocyte cells maintain the GFB, and structure-function experiments and studies of intercellular communication between the podocytes and other GFB cells, combined with advances from genetics and genomics, have laid the groundwork for a new generation of therapies that directly intervene at the GFB. These include inhibitors of apolipoprotein L1 (APOL1), short transient receptor potential channels (TRPCs), soluble fms-like tyrosine kinase 1 (sFLT1; also known as soluble vascular endothelial growth factor receptor 1), roundabout homologue 2 (ROBO2), endothelin receptor A, soluble urokinase plasminogen activator surface receptor (suPAR) and substrate intermediates for coenzyme Q10 (CoQ10). These molecular targets converge on two key components of GFB biology: mitochondrial function and the actin-myosin contractile machinery. This Review discusses therapies and developments focused on maintaining GFB integrity, and the emerging questions in this evolving field.
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Affiliation(s)
- Ilse S Daehn
- Department of Medicine, Division of Nephrology, The Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Jeremy S Duffield
- Research and Development, Prime Medicine, Cambridge, MA, USA. .,Department of Medicine, University of Washington, Seattle, WA, USA. .,Department of Medicine, Massachusetts General Hospital, Boston, MA, USA.
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10
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Feng D, Kumar M, Muntel J, Gurley SB, Birrane G, Stillman IE, Ding L, Wang M, Ahmed S, Schlondorff J, Alper SL, Ferrante T, Marquez SL, Ng CF, Novak R, Ingber DE, Steen H, Pollak MR. Phosphorylation of ACTN4 Leads to Podocyte Vulnerability and Proteinuric Glomerulosclerosis. J Am Soc Nephrol 2020; 31:1479-1495. [PMID: 32540856 PMCID: PMC7351002 DOI: 10.1681/asn.2019101032] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 03/23/2020] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Genetic mutations in α-actinin-4 (ACTN4)-an important actin crosslinking cytoskeletal protein that provides structural support for kidney podocytes-have been linked to proteinuric glomerulosclerosis in humans. However, the effect of post-translational modifications of ACTN4 on podocyte integrity and kidney function is not known. METHODS Using mass spectrometry, we found that ACTN4 is phosphorylated at serine (S) 159 in human podocytes. We used phosphomimetic and nonphosphorylatable ACTN4 to comprehensively study the effects of this phosphorylation in vitro and in vivo. We conducted x-ray crystallography, F-actin binding and bundling assays, and immunofluorescence staining to evaluate F-actin alignment. Microfluidic organ-on-a-chip technology was used to assess for detachment of podocytes simultaneously exposed to fluid flow and cyclic strain. We then used CRISPR/Cas9 to generate mouse models and assessed for renal injury by measuring albuminuria and examining kidney histology. We also performed targeted mass spectrometry to determine whether high extracellular glucose or TGF-β levels increase phosphorylation of ACTN4. RESULTS Compared with the wild type ACTN4, phosphomimetic ACTN4 demonstrated increased binding and bundling activity with F-actin in vitro. Phosphomimetic Actn4 mouse podocytes exhibited more spatially correlated F-actin alignment and a higher rate of detachment under mechanical stress. Phosphomimetic Actn4 mice developed proteinuria and glomerulosclerosis after subtotal nephrectomy. Moreover, we found that exposure to high extracellular glucose or TGF-β stimulates phosphorylation of ACTN4 at S159 in podocytes. CONCLUSIONS These findings suggest that increased phosphorylation of ACTN4 at S159 leads to biochemical, cellular, and renal pathology that is similar to pathology resulting from human disease-causing mutations in ACTN4. ACTN4 may mediate podocyte injury as a consequence of both genetic mutations and signaling events that modulate phosphorylation.
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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,Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts
| | - Mukesh Kumar
- Department of Pathology, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts,F.M. Kirby Neurobiology Center, Department of Neurobiology, Boston Children’s Hospital, Boston, Massachusetts
| | | | - Susan B. Gurley
- Division of Nephrology and Hypertension, Oregon Health & Science University, Portland, Oregon
| | - Gabriel Birrane
- Division of Experimental Medicine, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - Isaac E. Stillman
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts,Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - Lai Ding
- NeuroTechnology Studio, Program for Interdisciplinary Neuroscience, Brigham and Women’s Hospital, Boston, Massachusetts
| | - Minxian Wang
- Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Saima Ahmed
- Department of Pathology, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Johannes Schlondorff
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - Seth L. Alper
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Tom Ferrante
- Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts
| | - Susan L. Marquez
- Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts
| | - Carlos F. Ng
- Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts
| | - Richard Novak
- Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts
| | - Donald E. Ingber
- Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, Massachusetts,Vascular Biology Program, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts,Department of Surgery, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts,Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge, Massachusetts
| | - Hanno Steen
- Department of Pathology, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Martin R. Pollak
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts,Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts
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11
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Blondelle J, Tallapaka K, Seto JT, Ghassemian M, Clark M, Laitila JM, Bournazos A, Singer JD, Lange S. Cullin-3 dependent deregulation of ACTN1 represents a new pathogenic mechanism in nemaline myopathy. JCI Insight 2019; 5:125665. [PMID: 30990797 PMCID: PMC6542616 DOI: 10.1172/jci.insight.125665] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 04/11/2019] [Indexed: 12/11/2022] Open
Abstract
Nemaline myopathy is a congenital neuromuscular disorder characterized by muscle weakness, fiber atrophy and presence of nemaline bodies within myofibers. However, the understanding of underlying pathomechanisms is lacking. Recently, mutations in KBTBD13, KLHL40 and KLHL41, three substrate adaptors for the E3-ubiquitin ligase Cullin-3, have been associated with early-onset nemaline myopathies. We hypothesized that deregulation of Cullin-3 and its muscle protein substrates may be responsible for the disease development. Using Cullin-3 knockout mice, we identified accumulation of non-muscle alpha-Actinins (ACTN1 and ACTN4) in muscles of these mice, which we also observed in KBTBD13 patients. Our data reveal that proper regulation of Cullin-3 activity and ACTN1 levels is essential for normal muscle and neuromuscular junction development. While ACTN1 is naturally downregulated during myogenesis, its overexpression in C2C12 myoblasts triggered defects in fusion, myogenesis and acetylcholine receptor clustering; features that we characterized in Cullin-3 deficient mice. Taken together, our data highlight the importance for Cullin-3 mediated degradation of ACTN1 for muscle development, and indicate a new pathomechanism for the etiology of myopathies seen in Cullin-3 knockout mice and nemaline myopathy patients.
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Affiliation(s)
- Jordan Blondelle
- Division of Cardiology, School of Medicine, UCSD, La Jolla, California, USA
| | - Kavya Tallapaka
- Division of Cardiology, School of Medicine, UCSD, La Jolla, California, USA
| | - Jane T. Seto
- Neuromuscular Research, Murdoch Children’s Research Institute, Royal Children’s Hospital, Parkville, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia
| | - Majid Ghassemian
- Department of Chemistry and Biochemistry. UCSD, La Jolla, California, USA
| | - Madison Clark
- Division of Cardiology, School of Medicine, UCSD, La Jolla, California, USA
| | - Jenni M. Laitila
- Folkhälsan Research Center and Medicum, University of Helsinki, Helsinki, Finland
| | - Adam Bournazos
- Kids Neuroscience Centre, Kids Research, Children’s Hospital at Westmead, Sydney, New South Wales, Australia
- Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Jeffrey D. Singer
- Department of Biology, Portland State University, Portland, Oregon, USA
| | - Stephan Lange
- Division of Cardiology, School of Medicine, UCSD, La Jolla, California, USA
- Wallenberg Laboratory, Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, Gothenburg, Sweden
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12
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He S, Liu X, Lin Z, Liu Y, Gu L, Zhou H, Tang W, Zuo J. Reversible SAHH inhibitor protects against glomerulonephritis in lupus-prone mice by downregulating renal α-actinin-4 expression and stabilizing integrin-cytoskeleton linkage. Arthritis Res Ther 2019; 21:40. [PMID: 30696480 PMCID: PMC6352376 DOI: 10.1186/s13075-019-1820-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 01/11/2019] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Glomerulonephritis is one of the major complications and causes of death in systemic lupus erythematosus (SLE) and is characterized by glomerulosclerosis, interstitial fibrosis, and tubular atrophy, along with severe persistent proteinuria. DZ2002 is a reversible S-adenosyl-L-homocysteine hydrolase (SAHH) inhibitor with potent therapeutic activity against lupus nephritis in mice. However, the molecular events underlying the renal protective effects of DZ2002 remained unclear. This study is designed to uncover the molecular mechanisms of DZ2002 on glomerulonephritis of lupus-prone mice. METHODS We conducted a twice-daily treatment of DZ2002 on the lupus-prone NZB/WF1 mice, and the progression of lupus nephritis and alteration of renal function were monitored. The LC-MS-based label-free quantitative (LFQ) proteomic approach was applied to analyze the kidney tissue samples from the normal C57BL/6 mice and the NZB/WF1 mice treated with DZ2002 or vehicle. KEGG pathway enrichment and direct protein-protein interaction (PPI) network analyses were used to map the pathways in which the significantly changed proteins (SCPs) are involved. The selected proteins from proteomic analysis were validated by Western blot analysis and immunohistochemistry in the kidney tissues. RESULTS The twice-daily regimen of DZ2002 administration significantly ameliorated the lupus nephritis and improved the renal function in NZB/WF1 mice. A total of 3275 proteins were quantified, of which 253 proteins were significantly changed across normal C57BL/6 mice and the NZB/WF1 mice treated with DZ2002 or vehicle. Pathway analysis revealed that 13 SCPs were involved in tight junction and focal adhesion process. Further protein expression validation demonstrated that DZ2002-treated NZB/WF1 mice exhibited downregulation of α-actinin-4 and integrin-linked kinase (ILK), as well as the restoration of β1-integrin activation in the kidney tissues compared with the vehicle-treated ones. CONCLUSIONS Our study demonstrated the first evidence for the molecular mechanism of SAHH inhibitor on glomerulonephritis in SLE via the modulation of α-actinin-4 expression and focal adhesion-associated signaling proteins in the kidney.
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Affiliation(s)
- Shijun He
- Laboratory of Immunopharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing, 100049, China
| | - Xing Liu
- Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Zemin Lin
- Laboratory of Immunopharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Yuting Liu
- Laboratory of Immunopharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing, 100049, China
| | - Lei Gu
- Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Hu Zhou
- University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing, 100049, China. .,Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
| | - Wei Tang
- Laboratory of Immunopharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China. .,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing, 100049, China.
| | - Jianping Zuo
- Laboratory of Immunopharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China. .,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing, 100049, China.
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13
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Gallazzini M, Pallet N. Endoplasmic reticulum stress and kidney dysfunction. Biol Cell 2018; 110:205-216. [DOI: 10.1111/boc.201800019] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 06/14/2018] [Accepted: 06/28/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Morgan Gallazzini
- INSERM U1151 - CNRS UMR 8253; Institut Necker Enfants Malades; Paris France
- INSERM U1147; Centre Universitaire des Saints Pères; Paris France
| | - Nicolas Pallet
- INSERM U1151 - CNRS UMR 8253; Institut Necker Enfants Malades; Paris France
- INSERM U1147; Centre Universitaire des Saints Pères; Paris France
- Université Paris Descartes; Paris France
- Service de Néphrologie; Hôpital Européen Georges Pompidou; Paris
- Service de Biochimie; Hôpital Européen Gorges Pompidou; Paris France
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14
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Yee A, Papillon J, Guillemette J, Kaufman DR, Kennedy CRJ, Cybulsky AV. Proteostasis as a therapeutic target in glomerular injury associated with mutant α-actinin-4. Am J Physiol Renal Physiol 2018; 315:F954-F966. [PMID: 29873512 DOI: 10.1152/ajprenal.00082.2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mutations in α-actinin-4 (actinin-4) result in hereditary focal segmental glomerulosclerosis (FSGS) in humans. Actinin-4 mutants induce podocyte injury because of dysregulation of the cytoskeleton and proteotoxicity. Injury may be associated with endoplasmic reticulum (ER) stress and polyubiquitination of proteins. We assessed if the chemical chaperone 4-phenylbutyrate (4-PBA) can ameliorate the proteotoxicity of an actinin-4 mutant. Actinin-4 K255E, which causes FSGS in humans (K256E in the mouse), showed enhanced ubiquitination, accelerated degradation, aggregate formation, and enhanced association with filamentous (F)-actin in glomerular epithelial cells (GECs). The mutant disrupted ER function and stimulated autophagy. 4-PBA reduced actinin-4 K256E aggregation and its tight association with F-actin. Transgenic mice that express actinin-4 K256E in podocytes develop podocyte injury, proteinuria, and FSGS in association with glomerular ER stress. Treatment of these mice with 4-PBA in the drinking water over a 10-wk period significantly reduced albuminuria and ER stress. Another drug, celastrol, which enhanced expression of ER and cytosolic chaperones in GECs, tended to reduce actinin-4 aggregation but did not decrease the tight association of actinin-4 K256E with F-actin and did not reduce albuminuria in actinin-4 K256E transgenic mice. Thus, chemical chaperones, such as 4-PBA, may represent a novel therapeutic approach to certain hereditary glomerular diseases.
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Affiliation(s)
- Albert Yee
- Department of Medicine, McGill University Health Centre Research Institute, McGill University , Montreal, Quebec , Canada
| | - Joan Papillon
- Department of Medicine, McGill University Health Centre Research Institute, McGill University , Montreal, Quebec , Canada
| | - Julie Guillemette
- Department of Medicine, McGill University Health Centre Research Institute, McGill University , Montreal, Quebec , Canada
| | - Daniel R Kaufman
- Department of Medicine, McGill University Health Centre Research Institute, McGill University , Montreal, Quebec , Canada
| | - Chris R J Kennedy
- Kidney Research Centre, Department of Medicine, The Ottawa Hospital, University of Ottawa , Ottawa, Ontario , Canada
| | - Andrey V Cybulsky
- Department of Medicine, McGill University Health Centre Research Institute, McGill University , Montreal, Quebec , Canada
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15
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Hsu CP, Moghadaszadeh B, Hartwig JH, Beggs AH. Sarcomeric and nonmuscle α-actinin isoforms exhibit differential dynamics at skeletal muscle Z-lines. Cytoskeleton (Hoboken) 2018; 75:213-228. [PMID: 29518289 PMCID: PMC5943145 DOI: 10.1002/cm.21442] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 03/02/2018] [Accepted: 03/05/2018] [Indexed: 01/12/2023]
Abstract
The α-actinin proteins are a highly conserved family of actin crosslinkers that mediate interactions between several cytoskeletal and sarcomeric proteins. Nonsarcomeric α-actinin-1 and α-actinin-4 crosslink actin filaments in the cytoskeleton, while sarcomeric α-actinin-2 and α-actinin-3 serve a crucial role in anchoring actin filaments to the muscle Z-line. To assess the difference in turnover dynamics and structure/function properties between the α-actinin isoforms at the sarcomeric Z-line, we used Fluorescence Recovery After Photobleaching (FRAP) in primary myofiber cultures. We found that the recovery kinetics of these proteins followed three distinct patterns: α-actinin-2/α-actinin-3 had the slowest turn over, α-actinin-1 recovered to an intermediate degree, and α-actinin-4 had the fastest recovery. Interestingly, the isoforms' patterns of recovery were reversed at adhesion plaques in fibroblasts. This disparity suggests that the different α-actinin isoforms have unique association kinetics in myofibers and that nonmuscle isoform interactions are more dynamic at the sarcomeric Z-line. Protein domain-specific investigations using α-actinin-2/4 chimeric proteins showed that differential dynamics between sarcomeric and nonmuscle isoforms are regulated by cooperative interactions between the N-terminal actin-binding domain, the spectrin-like linker region and the C-terminal calmodulin-like EF hand domain. Together, these findings demonstrate that α-actinin isoforms are unique in binding dynamics at the Z-line and suggest differentially evolved interactive and Z-line association capabilities of each functional domain.
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Affiliation(s)
- Cynthia P Hsu
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Behzad Moghadaszadeh
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - John H Hartwig
- Translational Medicine Division, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Alan H Beggs
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
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16
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Yang JW, Dettmar AK, Kronbichler A, Gee HY, Saleem M, Kim SH, Shin JI. Recent advances of animal model of focal segmental glomerulosclerosis. Clin Exp Nephrol 2018; 22:752-763. [PMID: 29556761 DOI: 10.1007/s10157-018-1552-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 02/26/2018] [Indexed: 12/15/2022]
Abstract
In the last decade, great advances have been made in understanding the genetic basis for focal segmental glomerulosclerosis (FSGS). Animal models using specific gene disruption of the slit diaphragm and cytoskeleton of the foot process mirror the etiology of the human disease. Many animal models have been developed to understand the complex pathophysiology of FSGS. Therefore, we need to know the usefulness and exact methodology of creating animal models. Here, we review classic animal models and newly developed genetic animal models. Classic animal models of FSGS involve direct podocyte injury and indirect podocyte injury due to adaptive responses. However, the phenotype depends on the animal background. Renal ablation and direct podocyte toxin (PAN, adriamycin) models are leading animal models for FSGS, which have some limitations depending on mice background. A second group of animal models were developed using combinations of genetic mutation and toxin, such as NEP25, diphtheria toxin, and Thy1.1 models, which specifically injure podocytes. A third group of animal models involves genetic engineering techniques targeting podocyte expression molecules, such as podocin, CD2-associated protein, and TRPC6 channels. More detailed information about podocytopathy and FSGS can be expected in the coming decade. Different animal models should be used to study FSGS depending on the specific aim and sometimes should be used in combination.
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Affiliation(s)
- Jae Won Yang
- Department of Nephrology, Yonsei University Wonju College of Medicine, Wonju, Gangwon, Republic of Korea
| | - Anne Katrin Dettmar
- Pediatric Nephrology, Department of Pediatrics, Medical University Center Hamburg-Eppendorf, Hamburg, Germany
| | - Andreas Kronbichler
- Department of Internal Medicine IV (Nephrology and Hypertension), Universitätskliniken Innsbruck, Anichstraße 35, 6020, Innsbruck, Austria
| | - Heon Yung Gee
- Department of Pharmacology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Moin Saleem
- Paediatric Renal Medicine, University of Bristol, Bristol, UK.,Children's Renal Unit, Bristol Royal Hospital for Children, Bristol, UK
| | - Seong Heon Kim
- Department of Pediatrics, Pusan National University Children's Hospital, Yangsan, Republic of Korea. .,Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea.
| | - Jae Il Shin
- Department of Pediatrics, Yonsei University College of Medicine, 50 Yonsei-Ro, Seodaemun-gu, Seoul, 120-752, Republic of Korea.
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17
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Büscher AK, Celebi N, Hoyer PF, Klein HG, Weber S, Hoefele J. Mutations in INF2 may be associated with renal histology other than focal segmental glomerulosclerosis. Pediatr Nephrol 2018; 33:433-437. [PMID: 29038887 DOI: 10.1007/s00467-017-3811-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 09/07/2017] [Accepted: 09/12/2017] [Indexed: 11/30/2022]
Abstract
BACKGROUND In 2010, INF2 mutations were associated with autosomal-dominant focal segmental glomerulosclerosis (FSGS), clinically presenting with moderate proteinuria in adolescence. However, in the meantime, cases with more severe clinical courses have been described, including progression to end-stage renal disease (ESRD) during childhood. INF2 mutations in patients with isolated FSGS are clustered in exons 2 to 4, encoding the diaphanous inhibitory domain, involved in the regulation of the podocyte actin cytoskeleton. METHODS We report a family with 14 affected individuals (autosomal-dominant mode of inheritance), most of whom presented with nephrotic-range proteinuria, hypertension, and progressive renal failure. Four members received a kidney transplant without disease recurrence. Two patients underwent renal biopsy with the result of minimal-change glomerulopathy and IgA nephropathy respectively. We performed mutational analysis of ACTN4, CD2AP, COQ6, INF2, LAMB2, NPHS1, NPHS2, PLCE1, TRPC6, and WT1 in the index patient by next-generation sequencing. Additionally, in 6 affected and 2 unaffected family members target diagnostics were performed. RESULTS We identified a novel heterozygous mutation c.490G>C (p.(Ala164Pro) in exon 3 of the INF2 gene in the index patient and 6 additionally examined affected family members. In silico analysis predicted it as "probably damaging". Additionally, three patients and 2 unaffected relatives harbored a novel heterozygous variant in ACTN4 (c.1149C>G, p.(Ile383Met)) with uncertain pathogenicity. CONCLUSION Mutations in INF2 are associated with familial proteinuric diseases - irrespective of the presence of FSGS and in the case of rapid disease progression. Therefore, mutational analysis should be considered in patients with renal histology other than FSGS and severe renal phenotype.
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Affiliation(s)
- Anja K Büscher
- Pediatric Nephrology, Pediatrics II, University Children's Hospital Essen, Essen, Hufelandstrasse 55, 45122, Essen, Germany.
| | - Nora Celebi
- Department of Medicine IV, University Hospital Tübingen, Tübingen, Germany
| | - Peter F Hoyer
- Pediatric Nephrology, Pediatrics II, University Children's Hospital Essen, Essen, Hufelandstrasse 55, 45122, Essen, Germany
| | - Hanns-Georg Klein
- Center for Human Genetics and Laboratory Diagnostics Dr. Klein, Dr. Rost and Colleagues, Martinsried, Germany
| | | | - Julia Hoefele
- Institute of Human Genetics, Technical University of Munich, Munich, Germany
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18
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Disease-causing mutation in α-actinin-4 promotes podocyte detachment through maladaptation to periodic stretch. Proc Natl Acad Sci U S A 2018; 115:1517-1522. [PMID: 29378953 DOI: 10.1073/pnas.1717870115] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
α-Actinin-4 (ACTN4) bundles and cross-links actin filaments to confer mechanical resilience to the reconstituted actin network. How this resilience is built and dynamically regulated in the podocyte, and the cause of its failure in ACTN4 mutation-associated focal segmental glomerulosclerosis (FSGS), remains poorly defined. Using primary podocytes isolated from wild-type (WT) and FSGS-causing point mutant Actn4 knockin mice, we report responses to periodic stretch. While WT cells largely maintained their F-actin cytoskeleton and contraction, mutant cells developed extensive and irrecoverable reductions in these same properties. This difference was attributable to both actin material changes and a more spatially correlated intracellular stress in mutant cells. When stretched cells were further challenged using a cell adhesion assay, mutant cells were more likely to detach. Together, these data suggest a mechanism for mutant podocyte dysfunction and loss in FSGS-it is a direct consequence of mechanical responses of a cytoskeleton that is brittle.
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Pegoraro AF, Janmey P, Weitz DA. Mechanical Properties of the Cytoskeleton and Cells. Cold Spring Harb Perspect Biol 2017; 9:9/11/a022038. [PMID: 29092896 DOI: 10.1101/cshperspect.a022038] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
SUMMARYThe cytoskeleton is the major mechanical structure of the cell; it is a complex, dynamic biopolymer network comprising microtubules, actin, and intermediate filaments. Both the individual filaments and the entire network are not simple elastic solids but are instead highly nonlinear structures. Appreciating the mechanics of biopolymer networks is key to understanding the mechanics of cells. Here, we review the mechanical properties of cytoskeletal polymers and discuss the implications for the behavior of cells.
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Affiliation(s)
- Adrian F Pegoraro
- Department of Physics and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138
| | - Paul Janmey
- Institute for Medicine and Engineering and Department of Physiology, Perelman School of Medicine, and Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - David A Weitz
- Department of Physics and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138
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Cybulsky AV. Endoplasmic reticulum stress, the unfolded protein response and autophagy in kidney diseases. Nat Rev Nephrol 2017; 13:681-696. [DOI: 10.1038/nrneph.2017.129] [Citation(s) in RCA: 244] [Impact Index Per Article: 34.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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21
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Schenk LK, Möller-Kerutt A, Klosowski R, Wolters D, Schaffner-Reckinger E, Weide T, Pavenstädt H, Vollenbröker B. Angiotensin II regulates phosphorylation of actin-associated proteins in human podocytes. FASEB J 2017; 31:5019-5035. [PMID: 28768720 DOI: 10.1096/fj.201700142r] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 07/17/2017] [Indexed: 02/02/2023]
Abstract
Within the kidney, angiotensin II (AngII) targets different cell types in the vasculature, tubuli, and glomeruli. An important part of the renal filtration barrier is composed of podocytes with their actin-rich foot processes. In this study, we used stable isotope labeling with amino acids in cell culture coupled to mass spectrometry to characterize relative changes in the phosphoproteome of human podocytes in response to short-term treatment with AngII. In 4 replicates, we identified a total of 17,956 peptides that were traceable to 2081 distinct proteins. Bioinformatic analyses revealed that among the increasingly phosphorylated peptides are predominantly peptides that are related to actin filaments, cytoskeleton, lamellipodia, mammalian target of rapamycin, and MAPK signaling. Among others, this screening approach highlighted the increased phosphorylation of actin-bundling protein, l-plastin (LCP1). AngII-dependent phosphorylation of LCP1 in cultured podocytes was mediated by the kinases ERK, p90 ribosomal S6 kinase, PKA, or PKC. LCP1 phosphorylation increased filopodia formation. In addition, treatment with AngII led to LCP1 redistribution to the cell margins, membrane ruffling, and formation of lamellipodia. Our data highlight the importance of AngII-triggered actin cytoskeleton-associated signal transduction in podocytes.-Schenk, L. K., Möller-Kerutt, A., Klosowski, R., Wolters, D., Schaffner-Reckinger, E., Weide, T., Pavenstädt, H., Vollenbröker, B. Angiotensin II regulates phosphorylation of actin-associated proteins in human podocytes.
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Affiliation(s)
- Laura K Schenk
- Medizinischen Klinik und Poliklinik D, Universitätsklinikum Münster, Munster, Germany
| | - Annika Möller-Kerutt
- Medizinischen Klinik und Poliklinik D, Universitätsklinikum Münster, Munster, Germany
| | - Rafael Klosowski
- Analytische Chemie, Biomolekulare Massenspektrometrie, Ruhr-Universität Bochum, Bochum, Germany
| | - Dirk Wolters
- Analytische Chemie, Biomolekulare Massenspektrometrie, Ruhr-Universität Bochum, Bochum, Germany
| | - Elisabeth Schaffner-Reckinger
- Laboratory of Cytoskeleton and Cell Plasticity, Life Sciences Research Unit, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Thomas Weide
- Medizinischen Klinik und Poliklinik D, Universitätsklinikum Münster, Munster, Germany
| | - Hermann Pavenstädt
- Medizinischen Klinik und Poliklinik D, Universitätsklinikum Münster, Munster, Germany
| | - Beate Vollenbröker
- Medizinischen Klinik und Poliklinik D, Universitätsklinikum Münster, Munster, Germany;
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Boyer O, Dorval G, Servais A. Hereditary Podocytopathies in Adults: The Next Generation. KIDNEY DISEASES 2017; 3:50-56. [PMID: 28868292 DOI: 10.1159/000477243] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 04/28/2017] [Indexed: 01/15/2023]
Abstract
Idiopathic nephrotic syndrome may have two underlying mechanisms: either (1) an alteration of the immune system resulting in the production of a putative circulating factor of glomerular permeability; or (2) mutations in the structural genes of the glomerular filtration barrier in which case patients are typically multidrug resistant and do not recur after transplantation. The latter forms have been recently recognized as "hereditary podocytopathies." In the past few years, positional cloning approaches that allow the identification of gene mutations underlying diseases whose pathophysiology is unknown and animal models have helped decipher the pathophysiological mechanisms of the glomerular filtration process. Recently, the advent of next-generation sequencing (NGS) techniques has greatly facilitated the identification of numerous novel causative genes in hereditary podocytopathies. Moreover, it has revealed mutations in unexpected genes and has widened the phenotypes associated with podocyte gene mutations. The list of genes mutated in hereditary podocytopathies is constantly evolving and consists to date of more than 40 genes. However, the most recently identified genes are extremely rarely mutated and may concern only a couple of families worldwide. These discoveries provided crucial insight into the pathophysiological mechanisms linking podocyte proteins to kidney function. This review will focus on monogenic podocytopathies affecting adult patients.
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Affiliation(s)
- Olivia Boyer
- Néphrologie pédiatrique, Centre de référence MARHEA, Hôpital Necker - Enfants Malades, APHP, Paris, France.,Inserm U1163, Institut Imagine, Université Paris-Descartes Sorbonne Paris Cité, Paris, France
| | - Guillaume Dorval
- Néphrologie pédiatrique, Centre de référence MARHEA, Hôpital Necker - Enfants Malades, APHP, Paris, France.,Inserm U1163, Institut Imagine, Université Paris-Descartes Sorbonne Paris Cité, Paris, France
| | - Aude Servais
- Néphrologie, Centre de référence MARHEA, Hôpital Necker - Enfants Malades, APHP, Paris, France.,Inserm U1163, Institut Imagine, Université Paris-Descartes Sorbonne Paris Cité, Paris, France
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Zhao X, Khurana S, Charkraborty S, Tian Y, Sedor JR, Bruggman LA, Kao HY. α Actinin 4 (ACTN4) Regulates Glucocorticoid Receptor-mediated Transactivation and Transrepression in Podocytes. J Biol Chem 2016; 292:1637-1647. [PMID: 27998979 DOI: 10.1074/jbc.m116.755546] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 12/19/2016] [Indexed: 12/14/2022] Open
Abstract
Glucocorticoids are a general class of steroids that possess renoprotective activity in glomeruli through their interaction with the glucocorticoid receptor. However, the mechanisms by which glucocorticoids ameliorate proteinuria and glomerular disease are not well understood. In this study, we demonstrated that α actinin 4 (ACTN4), an actin-cross-linking protein known to coordinate cytoskeletal organization, interacts with the glucocorticoid receptor (GR) in the nucleus of human podocytes (HPCs), a key cell type in the glomerulus critical for kidney filtration function. The GR-ACTN4 complex enhances glucocorticoid response element (GRE)-driven reporter activity. Stable knockdown of ACTN4 by shRNA in HPCs significantly reduces dexamethasone-mediated induction of GR target genes and GRE-driven reporter activity without disrupting dexamethasone-induced nuclear translocation of GR. Synonymous mutations or protein expression losses in ACTN4 are associated with kidney diseases, including focal segmental glomerulosclerosis, characterized by proteinuria and podocyte injury. We found that focal segmental glomerulosclerosis-linked ACTN4 mutants lose their ability to bind liganded GR and support GRE-mediated transcriptional activity. Mechanistically, GR and ACTN4 interact in the nucleus of HPCs. Furthermore, disruption of the LXXLL nuclear receptor-interacting motif present in ACTN4 results in reduced GR interaction and dexamethasone-mediated transactivation of a GRE reporter while still maintaining its actin-binding activity. In contrast, an ACTN4 isoform, ACTN4 (Iso), that loses its actin-binding domain is still capable of potentiating a GRE reporter. Dexamethasone induces the recruitment of ACTN4 and GR to putative GREs in dexamethasone-transactivated promoters, SERPINE1, ANGPLT4, CCL20, and SAA1 as well as the NF-κB (p65) binding sites on GR-transrepressed promoters such as IL-1β, IL-6, and IL-8 Taken together, our data establish ACTN4 as a transcriptional co-regulator that modulates both dexamethasone-transactivated and -transrepressed genes in podocytes.
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Affiliation(s)
- Xuan Zhao
- From the Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Simran Khurana
- From the Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Sharmistha Charkraborty
- From the Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Yuqian Tian
- From the Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - John R Sedor
- Rammelkamp Center for Education and Research and Department of Medicine, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Leslie A Bruggman
- Rammelkamp Center for Education and Research and Department of Medicine, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Hung-Ying Kao
- From the Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106; Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106.
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24
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Feng D, Steinke JM, Krishnan R, Birrane G, Pollak MR. Functional Validation of an Alpha-Actinin-4 Mutation as a Potential Cause of an Aggressive Presentation of Adolescent Focal Segmental Glomerulosclerosis: Implications for Genetic Testing. PLoS One 2016; 11:e0167467. [PMID: 27977723 PMCID: PMC5158186 DOI: 10.1371/journal.pone.0167467] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 10/30/2016] [Indexed: 11/18/2022] Open
Abstract
Genetic testing in the clinic and research lab is becoming more routinely used to identify rare genetic variants. However, attributing these rare variants as the cause of disease in an individual patient remains challenging. Here, we report a patient who presented with nephrotic syndrome and focal segmental glomerulosclerosis (FSGS) with collapsing features at age 14. Despite treatment, her kidney disease progressed to end-stage within a year of diagnosis. Through genetic testing, an Y265H variant with unknown clinical significance in alpha-actinin-4 gene (ACTN4) was identified. This variant has not been seen previously in FSGS patients nor is it present in genetic databases. Her clinical presentation is different from previous descriptions of ACTN4 mediated FSGS, which is characterized by sub-nephrotic proteinuria and slow progression to end stage kidney disease. We performed in vitro and cellular assays to characterize this novel ACTN4 variant before attributing causation. We found that ACTN4 with either Y265H or K255E (a known disease-causing mutation) increased the actin bundling activity of ACTN4 in vitro, was associated with the formation of intracellular aggregates, and increased podocyte contractile force. Despite the absence of a familial pattern of inheritance, these similar biological changes caused by the Y265H and K255E amino acid substitutions suggest that this new variant is potentially the cause of FSGS in this patient. Our studies highlight that functional validation in complement with genetic testing may be required to confirm the etiology of rare disease, especially in the setting of unusual clinical presentations.
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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, United States of America
| | - Julia M. Steinke
- Division of Pediatric Nephrology and Transplantation, Helen DeVos Children's Hospital at Spectrum Health, Grand Rapids, Michigan, United States of America
| | - Ramaswamy Krishnan
- Department of Emergency Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Gabriel Birrane
- Division of Experimental Medicine, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Martin R. Pollak
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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25
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Riehle M, Büscher AK, Gohlke BO, Kaßmann M, Kolatsi-Joannou M, Bräsen JH, Nagel M, Becker JU, Winyard P, Hoyer PF, Preissner R, Krautwurst D, Gollasch M, Weber S, Harteneck C. TRPC6 G757D Loss-of-Function Mutation Associates with FSGS. J Am Soc Nephrol 2016; 27:2771-83. [PMID: 26892346 PMCID: PMC5004639 DOI: 10.1681/asn.2015030318] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 01/06/2016] [Indexed: 01/15/2023] Open
Abstract
FSGS is a CKD with heavy proteinuria that eventually progresses to ESRD. Hereditary forms of FSGS have been linked to mutations in the transient receptor potential cation channel, subfamily C, member 6 (TRPC6) gene encoding a nonselective cation channel. Most of these TRPC6 mutations cause a gain-of-function phenotype, leading to calcium-triggered podocyte cell death, but the underlying molecular mechanisms are unclear. We studied the molecular effect of disease-related mutations using tridimensional in silico modeling of tetrameric TRPC6. Our results indicated that G757 is localized in a domain forming a TRPC6-TRPC6 interface and predicted that the amino acid exchange G757D causes local steric hindrance and disruption of the channel complex. Notably, functional characterization of model interface domain mutants suggested a loss-of-function phenotype. We then characterized 19 human FSGS-related TRPC6 mutations, the majority of which caused gain-of-function mutations. However, five mutations (N125S, L395A, G757D, L780P, and R895L) caused a loss-of-function phenotype. Coexpression of wild-type TRPC6 and TRPC6 G757D, mimicking heterozygosity observed in patients, revealed a dominant negative effect of TRPC6 G757D. Our comprehensive analysis of human disease-causing TRPC6 mutations reveals loss of TRPC6 function as an additional concept of hereditary FSGS and provides molecular insights into the mechanism responsible for the loss-of-function phenotype of TRPC6 G757D in humans.
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Affiliation(s)
- Marc Riehle
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany
| | - Anja K Büscher
- Pediatric Nephrology, Pediatrics II, University of Duisburg-Essen, Essen, Germany
| | - Björn-Oliver Gohlke
- German Cancer Consortium, Heidelberg, Germany; Charité University Medicine Berlin, Structural Bioinformatics Group, Institute of Physiology and Experimental Clinical Research Center, Berlin, Germany
| | - Mario Kaßmann
- Nephrology/Intensive Care, Experimental and Clinical Research Center and Max Delbrück Center for Molecular Medicine, Charité University Medicine Berlin, Berlin, Germany
| | - Maria Kolatsi-Joannou
- Nephro-Urology Unit, University College London Institute of Child Health, London, United Kingdom
| | - Jan H Bräsen
- Institute of Pathology, University Hospital of Hannover, Hannover, Germany
| | - Mato Nagel
- Center of Nephrology and Metabolism, Weisswasser, Germany
| | - Jan U Becker
- Institute of Pathology, University Hospital of Cologne, Cologne, Germany; and
| | - Paul Winyard
- Nephro-Urology Unit, University College London Institute of Child Health, London, United Kingdom
| | - Peter F Hoyer
- Pediatric Nephrology, Pediatrics II, University of Duisburg-Essen, Essen, Germany
| | - Robert Preissner
- German Cancer Consortium, Heidelberg, Germany; Charité University Medicine Berlin, Structural Bioinformatics Group, Institute of Physiology and Experimental Clinical Research Center, Berlin, Germany
| | - Dietmar Krautwurst
- Deutsche Forschungsanstalt für Lebensmittelchemie, Molekulare Zellphysiologie und Chemorezeption, Freising, Germany
| | - Maik Gollasch
- Nephrology/Intensive Care, Experimental and Clinical Research Center and Max Delbrück Center for Molecular Medicine, Charité University Medicine Berlin, Berlin, Germany
| | - Stefanie Weber
- Pediatric Nephrology, Pediatrics II, University of Duisburg-Essen, Essen, Germany;
| | - Christian Harteneck
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany;
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26
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Bartram MP, Habbig S, Pahmeyer C, Höhne M, Weber LT, Thiele H, Altmüller J, Kottoor N, Wenzel A, Krueger M, Schermer B, Benzing T, Rinschen MM, Beck BB. Three-layered proteomic characterization of a novel ACTN4 mutation unravels its pathogenic potential in FSGS. Hum Mol Genet 2016; 25:1152-64. [PMID: 26740551 DOI: 10.1093/hmg/ddv638] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2015] [Accepted: 12/31/2015] [Indexed: 01/09/2023] Open
Abstract
Genetic diseases constitute the most important cause for end-stage renal disease in children and adolescents. Mutations in the ACTN4 gene, encoding the actin-binding protein α-actinin-4, are a rare cause of autosomal dominant familial focal segmental glomerulosclerosis (FSGS). Here, we report the identification of a novel, disease-causing ACTN4 mutation (p.G195D, de novo) in a sporadic case of childhood FSGS using next generation sequencing. Proteome analysis by quantitative mass spectrometry (MS) of patient-derived urinary epithelial cells indicated that ACTN4 levels were significantly decreased when compared with healthy controls. By resolving the peptide bearing the mutated residue, we could proof that the mutant protein is less abundant when compared with the wild-type protein. Further analyses revealed that the decreased stability of p.G195D is associated with increased ubiquitylation in the vicinity of the mutation site. We next defined the ACTN4 interactome, which was predominantly composed of cytoskeletal modulators and LIM domain-containing proteins. Interestingly, this entire group of proteins, including several highly specific ACTN4 interactors, was globally decreased in the patient-derived cells. Taken together, these data suggest a mechanistic link between ACTN4 instability and proteome perturbations of the ACTN4 interactome. Our findings advance the understanding of dominant effects exerted by ACTN4 mutations in FSGS. This study illustrates the potential of genomics and complementary, high-resolution proteomics analyses to study the pathogenicity of rare gene variants.
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Affiliation(s)
- Malte P Bartram
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Sandra Habbig
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany, Department of Pediatrics
| | - Caroline Pahmeyer
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Martin Höhne
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Systems Biology of Ageing Cologne, University of Cologne, Cologne, Germany
| | | | | | | | | | | | - Marcus Krueger
- Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and
| | - Bernhard Schermer
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Systems Biology of Ageing Cologne, University of Cologne, Cologne, Germany
| | - Thomas Benzing
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Systems Biology of Ageing Cologne, University of Cologne, Cologne, Germany
| | - Markus M Rinschen
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany, Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD) and Systems Biology of Ageing Cologne, University of Cologne, Cologne, Germany
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Rapid progression to end-stage renal disease in a child with a sporadic ACTN4 mutation. Clin Nephrol Case Stud 2015; 3:14-18. [PMID: 29043128 PMCID: PMC5438006 DOI: 10.5414/cncs108616] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 07/16/2015] [Indexed: 01/17/2023] Open
Abstract
Mutations of ACTN4 cause an autosomal dominant form of focal segmental glomerulosclerosis (FSGS). Presentation usually occurs in the teenage years or later with symptoms of mild proteinuria and slowly progressive renal dysfunction leading to end-stage renal disease (ESRD). We report a 5-year-old female patient who was diagnosed with nephrotic syndrome and did not respond to 6 weeks of oral glucocorticoid therapy. Renal biopsy showed a collapsing variant of FSGS and genetic studies revealed a heterozygous disease-causing mutation in the ACTN4 gene (c.784C>T, p.Ser262Phe). No mutations were found in the NPHS2, TRPC6, and INF2 genes, nor did her parents have any mutations for FSGS. She developed ESRD 6 months after presentation. Although a disease-causing ACTN4 mutation was identified, the contribution of additional polymorphisms in other genes is not known. Such additional polymorphisms may represent yet unidentified epigenetic factors that contributed to the aggressive nature of this child’s disease progression. A literature review has revealed only two similar case reports.
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28
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Feng D, DuMontier C, Pollak MR. The role of alpha-actinin-4 in human kidney disease. Cell Biosci 2015; 5:44. [PMID: 26301083 PMCID: PMC4545552 DOI: 10.1186/s13578-015-0036-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 07/24/2015] [Indexed: 11/19/2022] Open
Abstract
Mutations in the Alpha-actinin-4 gene (ACTN4) cause a rare form of familial focal segmental glomerulosclerosis in humans. Individuals with kidney disease-associated ACTN4 mutations tend to have mild to moderate proteinuria, with many developing decreased kidney function progressing to end stage kidney disease. All of the disease-causing ACTN4 mutations identified to date are located within the actin-binding domain of the encoded protein, increasing its binding affinity to F-actin and leading to abnormal actin rich cellular aggregates. The identification of ACTN4 mutations as a cause of human kidney disease demonstrates a key cellular pathway by which alterations in cytoskeletal behavior can mediate kidney disease. Here we review the studies relevant to ACTN4 and its role in mediating kidney disease.
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Affiliation(s)
- Di Feng
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215 USA
| | - Clark DuMontier
- Department of Medicine, Boston University School of Medicine, Boston, MA 02118 USA
| | - Martin R Pollak
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215 USA
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29
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Mathieson PW. The podocyte cytoskeleton in health and in disease. Clin Kidney J 2015; 5:498-501. [PMID: 26069792 PMCID: PMC4400570 DOI: 10.1093/ckj/sfs153] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 09/27/2012] [Indexed: 11/18/2022] Open
Abstract
The podocyte is a key cell in the selective filtering action of the glomerular capillary wall. Podocyte injury is of pathogenetic and prognostic significance in human glomerular disease; podocyte repair and regeneration are important therapeutic targets. In particular, podocyte function is dependent on the cells' actin cytoskeleton: this maintains their complex structure. Alterations in the actin cytoskeleton arise from a variety of genetic and acquired causes. Therapeutic agents that are beneficial in proteinuric disease may act at least partly by restoring the cell shape via effects on the actin cytoskeleton. Recent studies of podocytes in vivo and in vitro are described, highlighting clinically relevant observations and those that help us understand the ways in which we may harness nature's own mechanisms to repair and/or renew these specialized glomerular cells, with a particular focus on their actin cytoskeleton. Drugs that have beneficial effects on podocytes can improve our ability to treat important renal diseases including diabetic nephropathy. Currently available agents can be applied in this way and the rapid progress in the study of podocytes is highlighting new therapeutic targets that can bring even more specificity.
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Affiliation(s)
- Peter W Mathieson
- Faculty of Medicine & Dentistry , University of Bristol, North Bristol NHS Trust , Bristol , UK ; Academic Renal Unit , Southmead Hospital , Bristol , UK
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30
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Pharmacological targeting of actin-dependent dynamin oligomerization ameliorates chronic kidney disease in diverse animal models. Nat Med 2015; 21:601-9. [PMID: 25962121 PMCID: PMC4458177 DOI: 10.1038/nm.3843] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 03/18/2015] [Indexed: 12/11/2022]
Abstract
Dysregulation of the actin cytoskeleton in podocytes represents a common pathway in the pathogenesis of proteinuria across a spectrum of chronic kidney diseases (CKD). The GTPase dynamin has been implicated in the maintenance of cellular architecture in podocytes through its direct interaction with actin. Furthermore, the propensity of dynamin to oligomerize into higher-order structures in an actin-dependent manner and to crosslink actin microfilaments into higher order structures have been correlated with increased actin polymerization and global organization of the actin cytoskeleton in the cell. We found that use of the small molecule Bis-T-23, which promotes actin-dependent dynamin oligomerization and thus increased actin polymerization in injured podocytes, was sufficient to improve renal health in diverse models of both transient kidney disease and of CKD. In particular, administration of Bis-T-23 in these renal disease models restored the normal ultrastructure of podocyte foot processes, lowered proteinuria, lowered collagen IV deposits in the mesangial matrix, diminished mesangial matrix expansion and extended lifespan. These results further establish that alterations in the actin cytoskeleton of kidney podocytes is a common hallmark of CKD, while also underscoring the significant regenerative potential of injured glomeruli and that targeting the oligomerization cycle of dynamin represents an attractive potential therapeutic target to treat CKD.
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31
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Hall G, Gbadegesin RA. Translating genetic findings in hereditary nephrotic syndrome: the missing loops. Am J Physiol Renal Physiol 2015; 309:F24-8. [PMID: 25810439 DOI: 10.1152/ajprenal.00683.2014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 03/14/2015] [Indexed: 12/28/2022] Open
Abstract
Nephrotic syndrome (NS) is a clinicopathological entity characterized by proteinuria, hypoalbuminemia, peripheral edema, and hyperlipidemia. It is the most common cause of glomerular disease in children and adults. Although the molecular pathogenesis of NS is not completely understood, data from the study of familial NS suggest that it is a "podocytopathy." Virtually all of the genes mutated in hereditary NS localize to the podocyte or its secreted products and the slit diaphragm. Since the completion of human genome sequence and the advent of next generation sequencing, at least 29 causes of single-gene NS have been identified. However, these findings have not been matched by therapeutic advances owing to suboptimal in vitro and in vivo models for the study of human glomerular disease and podocyte injury phenotypes. Multidisciplinary collaboration between clinicians, geneticists, cell biologists, and molecular physiologists has the potential to overcome this barrier and thereby speed up the translation of genetic findings into improved patient care.
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Affiliation(s)
- Gentzon Hall
- Department of Medicine and Duke Molecular Physiology Institute, Duke University Medical Center, Durham, North Carolina; and
| | - Rasheed A Gbadegesin
- Department of Pediatrics and Duke Molecular Physiology Institute, Duke University Medical Center, Durham, North Carolina
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32
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Genetic causes of proteinuria and nephrotic syndrome: impact on podocyte pathobiology. Pediatr Nephrol 2015; 30:221-33. [PMID: 24584664 PMCID: PMC4262721 DOI: 10.1007/s00467-014-2753-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 12/31/2013] [Accepted: 01/02/2014] [Indexed: 12/11/2022]
Abstract
In the past 20 years, multiple genetic mutations have been identified in patients with congenital nephrotic syndrome (CNS) and both familial and sporadic focal segmental glomerulosclerosis (FSGS). Characterization of the genetic basis of CNS and FSGS has led to the recognition of the importance of podocyte injury to the development of glomerulosclerosis. Genetic mutations induce injury due to effects on the podocyte's structure, actin cytoskeleton, calcium signaling, and lysosomal and mitochondrial function. Transgenic animal studies have contributed to our understanding of podocyte pathobiology. Podocyte endoplasmic reticulum stress response, cell polarity, and autophagy play a role in maintenance of podocyte health. Further investigations related to the effects of genetic mutations on podocytes may identify new pathways for targeting therapeutics for nephrotic syndrome.
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33
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Zhao X, Hsu KS, Lim JH, Bruggeman LA, Kao HY. α-Actinin 4 potentiates nuclear factor κ-light-chain-enhancer of activated B-cell (NF-κB) activity in podocytes independent of its cytoplasmic actin binding function. J Biol Chem 2014; 290:338-49. [PMID: 25411248 DOI: 10.1074/jbc.m114.597260] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Glomerular podocytes are highly specialized terminally differentiated cells that act as a filtration barrier in the kidney. Mutations in the actin-binding protein, α-actinin 4 (ACTN4), are linked to focal segmental glomerulosclerosis (FSGS), a chronic kidney disease characterized by proteinuria. Aberrant activation of NF-κB pathway in podocytes is implicated in glomerular diseases including proteinuria. We demonstrate here that stable knockdown of ACTN4 in podocytes significantly reduces TNFα-mediated induction of NF-κB target genes, including IL-1β and NPHS1, and activation of an NF-κB-driven reporter without interfering with p65 nuclear translocation. Overexpression of ACTN4 and an actin binding-defective variant increases the reporter activity. In contrast, an FSGS-linked ACTN4 mutant, K255E, which has increased actin binding activity and is predominantly cytoplasmic, fails to potentiate NF-κB activity. Mechanistically, IκBα blocks the association of ACTN4 and p65 in the cytosol. In response to TNFα, both NF-κB subunits p65 and p50 translocate to the nucleus, where they bind and recruit ACTN4 to their targeted promoters, IL-1β and IL-8. Taken together, our data identify ACTN4 as a novel coactivator for NF-κB transcription factors in podocytes. Importantly, this nuclear function of ACTN4 is independent of its actin binding activity in the cytoplasm.
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Affiliation(s)
| | | | | | - Leslie A Bruggeman
- Rammelkamp Center for Education and Research and Department of Medicine, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Hung-Ying Kao
- From the Department of Biochemistry, Case Comprehensive Cancer Center, and
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The Impact of Histologic Variants on FSGS Outcomes. INTERNATIONAL SCHOLARLY RESEARCH NOTICES 2014; 2014:913690. [PMID: 27437509 PMCID: PMC4897537 DOI: 10.1155/2014/913690] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Accepted: 09/04/2014] [Indexed: 01/25/2023]
Abstract
Focal segmental glomerulosclerosis (FSGS) is the most common glomerular disease leading to end-stage renal disease. The clinical course is highly variable with disparate responses to therapeutic intervention and rates of progression. Histologic variant subtype has been commonly used as a prognostic and therapeutic guide in the clinical management of FSGS. The tip lesion is widely considered to portend the most favorable prognosis and to be the most responsive to steroid therapy. Conversely, the collapsing lesion, more prevalent in patients of African descent, is associated with steroid resistance and higher risk of disease progression. In the 10 years since the Columbia classification system for FSGS was published, some retrospective and one prospective study explored the impact of histologic variants at the time of biopsy on FSGS outcomes. The results largely validate its clinical predictive value with respect to treatment response, though its utility in cases recurring after kidney transplantation is still unknown. Sampling and interpretation errors are additional sources of caution. More research is needed to fully define reproducible prognostic and therapeutic markers for this polymorphic disorder.
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35
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Hall G, Gbadegesin RA, Lavin P, Wu G, Liu Y, Oh EC, Wang L, Spurney RF, Eckel J, Lindsey T, Homstad A, Malone AF, Phelan PJ, Shaw A, Howell DN, Conlon PJ, Katsanis N, Winn MP. A novel missense mutation of Wilms' Tumor 1 causes autosomal dominant FSGS. J Am Soc Nephrol 2014; 26:831-43. [PMID: 25145932 DOI: 10.1681/asn.2013101053] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
FSGS is a clinical disorder characterized by focal scarring of the glomerular capillary tuft, podocyte injury, and nephrotic syndrome. Although idiopathic forms of FSGS predominate, recent insights into the molecular and genetic causes of FSGS have enhanced our understanding of disease pathogenesis. Here, we report a novel missense mutation of the transcriptional regulator Wilms' Tumor 1 (WT1) as the cause of nonsyndromic, autosomal dominant FSGS in two Northern European kindreds from the United States. We performed sequential genome-wide linkage analysis and whole-exome sequencing to evaluate participants from family DUK6524. Subsequently, whole-exome sequencing and direct sequencing were performed on proband DNA from family DUK6975. We identified multiple suggestive loci on chromosomes 6, 11, and 13 in family DUK6524 and identified a segregating missense mutation (R458Q) in WT1 isoform D as the cause of FSGS in this family. The identical mutation was found in family DUK6975. The R458Q mutation was not found in 1600 control chromosomes and was predicted as damaging by in silico simulation. We depleted wt1a in zebrafish embryos and observed glomerular injury and filtration defects, both of which were rescued with wild-type but not mutant human WT1D mRNA. Finally, we explored the subcellular mechanism of the mutation in vitro. WT1(R458Q) overexpression significantly downregulated nephrin and synaptopodin expression, promoted apoptosis in HEK293 cells and impaired focal contact formation in podocytes. Taken together, these data suggest that the WT1(R458Q) mutation alters the regulation of podocyte homeostasis and causes nonsyndromic FSGS.
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Affiliation(s)
- Gentzon Hall
- Division of Nephrology, Departments of Medicine, Duke Molecular Physiology Institute
| | | | - Peter Lavin
- Department of Transplant, Urology and Nephrology, Beaumont Hospital, Dublin, Ireland
| | | | - Yangfan Liu
- Cell Biology, Center for Human Disease Modeling, Duke University Medical Center, Durham, North Carolina
| | - Edwin C Oh
- Cell Biology, Center for Human Disease Modeling, Duke University Medical Center, Durham, North Carolina
| | | | | | - Jason Eckel
- Division of Nephrology, Departments of Medicine
| | | | | | - Andrew F Malone
- Division of Nephrology, Departments of Medicine, Duke Molecular Physiology Institute
| | - Paul J Phelan
- Division of Nephrology, Departments of Medicine, Duke Molecular Physiology Institute
| | - Andrey Shaw
- Department of Pathology and Immunology, Washington University School of Medicine in St. Louis, St. Louis, Missouri; and
| | | | - Peter J Conlon
- Department of Transplant, Urology and Nephrology, Beaumont Hospital, Dublin, Ireland
| | - Nicholas Katsanis
- Departments of Medicine, Cell Biology, Center for Human Disease Modeling, Duke University Medical Center, Durham, North Carolina
| | - Michelle P Winn
- Division of Nephrology, Departments of Medicine, Duke Molecular Physiology Institute,
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36
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Discovery of new glomerular disease-relevant genes by translational profiling of podocytes in vivo. Kidney Int 2014; 86:1116-29. [PMID: 24940801 PMCID: PMC4245460 DOI: 10.1038/ki.2014.204] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 04/08/2014] [Accepted: 04/24/2014] [Indexed: 12/25/2022]
Abstract
Identifying new biomarkers and therapeutic targets for podocytopathies such as focal segmental glomerulosclerosis (FSGS) requires a detailed analysis of transcriptional changes in podocytes over the course of disease. Here we used translating ribosome affinity purification (TRAP) to isolate and profile podocyte-specific mRNA in two different models of FSGS. Expressed eGFP-tagged ribosomal protein L10a in podocytes under the control of the Collagen-1α1 promoter enabled podocyte-specific mRNA isolation in a one-step process over the course of disease. This TRAP protocol robustly enriched known podocyte-specific mRNAs. We crossed col1α1-L10a mice with the actn4−/− and actn4+/K256E models of FSGS and analyzed podocyte transcriptional profiles at 2, 6 and 44 weeks of age. Two upregulated podocyte genes in murine FSGS (CXCL1 and DMPK) were found to be upregulated at the protein level in biopsies from patients with FSGS, validating this approach. There was no dilution of podocyte-specific transcripts during disease. These are the first podocyte-specific RNA expression datasets during aging and in two models of FSGS. This approach identified new podocyte proteins that are upregulated in FSGS and help define novel biomarkers and therapeutic targets for human glomerular disease.
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37
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Read NC, Gutsol A, Holterman CE, Carter A, Coulombe J, Gray DA, Kennedy CRJ. Ubiquitin C-terminal hydrolase L1 deletion ameliorates glomerular injury in mice with ACTN4-associated focal segmental glomerulosclerosis. Biochim Biophys Acta Mol Basis Dis 2014; 1842:1028-40. [PMID: 24662305 DOI: 10.1016/j.bbadis.2014.03.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 03/13/2014] [Accepted: 03/15/2014] [Indexed: 11/19/2022]
Abstract
Renal ubiquitin C-terminal hydrolase L1 (UCHL1) is upregulated in a subset of human glomerulopathies, including focal segmental glomerulosclerosis (FSGS), where it may serve to promote ubiquitin pools for degradation of cytotoxic proteins. In the present study, we tested whether UCHL1 is expressed in podocytes of a mouse model of ACTN4-associated FSGS. Podocyte UCHL1 protein was detected in glomeruli of K256E-ACTN4(pod+)/UCHL1+/+ mice. UCHL1+/- mice were intercrossed with K256E-ACTN4(pod+) mice and monitored for features of glomerular disease. 10-week-old K256E-ACTN4(pod+)/UCHL1-/- mice exhibited significantly ameliorated albuminuria, glomerulosclerosis, tubular pathology and blood pressure. Interestingly, while UCHL1 deletion diminished both tubular and glomerular apoptosis, WT1-positive nuclei were unchanged. Finally, UCHL1 levels correlated positively with poly-ubiquitinated proteins but negatively with K256E-α-actinin-4 levels, implying reduced K256E-α-actinin-4 proteolysis in the absence of UCHL1. Our data suggest that UCHL1 upregulation in ACTN4-associated FSGS fuels the proteasome and that UCHL1 deletion may impair proteolysis and thereby preserve K256E/wt-α-actinin-4 heterodimers, maintaining podocyte cytoskeletal integrity and protecting the glomerular filtration barrier.
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Affiliation(s)
- Naomi C Read
- Kidney Research Centre, The Ottawa Hospital, Ottawa, Ontario, Canada; Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, Ontario, Canada; Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Alex Gutsol
- Kidney Research Centre, The Ottawa Hospital, Ottawa, Ontario, Canada; Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Chet E Holterman
- Kidney Research Centre, The Ottawa Hospital, Ottawa, Ontario, Canada; Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Anthony Carter
- Kidney Research Centre, The Ottawa Hospital, Ottawa, Ontario, Canada; Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Josée Coulombe
- Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Douglas A Gray
- Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, Ontario, Canada; Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Chris R J Kennedy
- Kidney Research Centre, The Ottawa Hospital, Ottawa, Ontario, Canada; Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, Ontario, Canada; Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada.
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38
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Tian X, Kim JJ, Monkley SM, Gotoh N, Nandez R, Soda K, Inoue K, Balkin DM, Hassan H, Son SH, Lee Y, Moeckel G, Calderwood DA, Holzman LB, Critchley DR, Zent R, Reiser J, Ishibe S. Podocyte-associated talin1 is critical for glomerular filtration barrier maintenance. J Clin Invest 2014; 124:1098-113. [PMID: 24531545 PMCID: PMC3934159 DOI: 10.1172/jci69778] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 12/05/2013] [Indexed: 12/28/2022] Open
Abstract
Podocytes are specialized actin-rich epithelial cells that line the kidney glomerular filtration barrier. The interface between the podocyte and the glomerular basement membrane requires integrins, and defects in either α3 or β1 integrin, or the α3β1 ligand laminin result in nephrotic syndrome in murine models. The large cytoskeletal protein talin1 is not only pivotal for integrin activation, but also directly links integrins to the actin cytoskeleton. Here, we found that mice lacking talin1 specifically in podocytes display severe proteinuria, foot process effacement, and kidney failure. Loss of talin1 in podocytes caused only a modest reduction in β1 integrin activation, podocyte cell adhesion, and cell spreading; however, the actin cytoskeleton of podocytes was profoundly altered by the loss of talin1. Evaluation of murine models of glomerular injury and patients with nephrotic syndrome revealed that calpain-induced talin1 cleavage in podocytes might promote pathogenesis of nephrotic syndrome. Furthermore, pharmacologic inhibition of calpain activity following glomerular injury substantially reduced talin1 cleavage, albuminuria, and foot process effacement. Collectively, these findings indicate that podocyte talin1 is critical for maintaining the integrity of the glomerular filtration barrier and provide insight into the pathogenesis of nephrotic syndrome.
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Affiliation(s)
- Xuefei Tian
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Jin Ju Kim
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Susan M. Monkley
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Nanami Gotoh
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Ramiro Nandez
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Keita Soda
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Kazunori Inoue
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Daniel M. Balkin
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Hossam Hassan
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Sung Hyun Son
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Yashang Lee
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Gilbert Moeckel
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - David A. Calderwood
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Lawrence B. Holzman
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - David R. Critchley
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Roy Zent
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Jochen Reiser
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
| | - Shuta Ishibe
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Miami, Miami, Florida, USA.
Department of Biochemistry, University of Leicester, Leicester, United Kingdom.
Department of Cell Biology,
Howard Hughes Medical Institute,
Program in Cellular Neuroscience, Neurodegeneration, and Repair,
Department of Pathology, and
Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, USA.
Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Medicine, Vanderbilt University and Veterans Affairs Hospital, Nashville, Tennessee, USA.
Department of Internal Medicine, Rush University Medical Center, Chicago, Illinois, USA
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39
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Manson JJ, Isenberg DA. The origin and pathogenic consequences of anti-dsDNA antibodies in systemic lupus erythematosus. Expert Rev Clin Immunol 2014; 2:377-85. [DOI: 10.1586/1744666x.2.3.377] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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40
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de Mik SML, Hoogduijn MJ, de Bruin RW, Dor FJMF. Pathophysiology and treatment of focal segmental glomerulosclerosis: the role of animal models. BMC Nephrol 2013; 14:74. [PMID: 23547922 PMCID: PMC3637050 DOI: 10.1186/1471-2369-14-74] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 03/20/2013] [Indexed: 12/24/2022] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is a kidney disease with progressive glomerular scarring and a clinical presentation of nephrotic syndrome. FSGS is a common primary glomerular disorder that causes renal dysfunction which progresses slowly over time to end-stage renal disease. Most cases of FSGS are idiopathic Although kidney transplantation is a potentially curative treatment, 40% of patients have recurrence of FSGS after transplantation. In this review a brief summary of the pathogenesis causing FSGS in humans is given, and a variety of animal models used to study FSGS is discussed. These animal models include the reduction of renal mass by resecting 5/6 of the kidney, reduction of renal mass due to systemic diseases such as hypertension, hyperlipidemia or SLE, drug-induced FSGS using adriamycin, puromycin or streptozotocin, virus-induced FSGS, genetically-induced FSGS such as via Mpv-17 inactivation and α-actinin 4 and podocin knockouts, and a model for circulating permeability factors. In addition, an animal model that spontaneously develops FSGS is discussed. To date, there is no exact understanding of the pathogenesis of idiopathic FSGS, and there is no definite curative treatment. One requirement facilitating FSGS research is an animal model that resembles human FSGS. Most animal models induce secondary forms of FSGS in an acute manner. The ideal animal model for primary FSGS, however, should mimic the human primary form in that it develops spontaneously and has a slow chronic progression. Such models are currently not available. We conclude that there is a need for a better animal model to investigate the pathogenesis and potential treatment options of FSGS.
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Affiliation(s)
- Sylvana M L de Mik
- Laboratory of Experimental Surgery, Department of Surgery, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
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Kunishima S, Okuno Y, Yoshida K, Shiraishi Y, Sanada M, Muramatsu H, Chiba K, Tanaka H, Miyazaki K, Sakai M, Ohtake M, Kobayashi R, Iguchi A, Niimi G, Otsu M, Takahashi Y, Miyano S, Saito H, Kojima S, Ogawa S. ACTN1 mutations cause congenital macrothrombocytopenia. Am J Hum Genet 2013; 92:431-8. [PMID: 23434115 DOI: 10.1016/j.ajhg.2013.01.015] [Citation(s) in RCA: 144] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Revised: 12/20/2012] [Accepted: 01/23/2013] [Indexed: 11/30/2022] Open
Abstract
Congenital macrothrombocytopenia (CMTP) is a heterogeneous group of rare platelet disorders characterized by a congenital reduction of platelet counts and abnormally large platelets, for which CMTP-causing mutations are only found in approximately half the cases. We herein performed whole-exome sequencing and targeted Sanger sequencing to identify mutations that cause CMTP, in which a dominant mode of transmission had been suspected but for which no known responsible mutations have been documented. In 13 Japanese CMTP-affected pedigrees, we identified six (46%) affected by ACTN1 variants cosegregating with CMTP. In the entire cohort, ACNT1 variants accounted for 5.5% of the dominant forms of CMTP cases and represented the fourth most common cause in Japanese individuals. Individuals with ACTN1 variants presented with moderate macrothrombocytopenia with anisocytosis but were either asymptomatic or had only a modest bleeding tendency. ACTN1 encodes α-actinin-1, a member of the actin-crosslinking protein superfamily that participates in the organization of the cytoskeleton. In vitro transfection experiments in Chinese hamster ovary cells demonstrated that altered α-actinin-1 disrupted the normal actin-based cytoskeletal structure. Moreover, transduction of mouse fetal liver-derived megakaryocytes with disease-associated ACTN1 variants caused a disorganized actin-based cytoskeleton in megakaryocytes, resulting in the production of abnormally large proplatelet tips, which were reduced in number. Our findings provide an insight into the pathogenesis of CMTP.
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Affiliation(s)
- Shinji Kunishima
- Department of Advanced Diagnosis, Clinical Research Center, National Hospital Organization Nagoya Medical Center, Nagoya, Japan.
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Che R, Zhang A. Mechanisms of Glucocorticoid Resistance in Idiopathic Nephrotic Syndrome. ACTA ACUST UNITED AC 2013; 37:360-78. [DOI: 10.1159/000350163] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2013] [Indexed: 11/19/2022]
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Bostrom MA, Perlegas P, Lu L, Hicks PJ, Hawkins G, Ng MCY, Langefeld CD, Freedman BI, Bowden DW. Relevance of the ACTN4 gene in African-Americans with non-diabetic end-stage renal disease. Am J Nephrol 2012; 36:252-60. [PMID: 22965004 DOI: 10.1159/000342205] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Accepted: 07/21/2012] [Indexed: 12/20/2022]
Abstract
BACKGROUND African-Americans (AAs) are predisposed to non-diabetic (non-DM) end-stage renal disease (ESRD), and studies have shown a genetic component to this risk. Rare mutations in ACTN4 (α-actinin-4), an actin-binding protein expressed in podocytes, cause familial focal segmental glomerulosclerosis. METHODS We assessed the contribution of coding variants in ACTN4 to non-DM ESRD risk in AAs. Nineteen exons, 2,800 bases of the promoter and 392 bases of the 3' untranslated region of ACTN4 were sequenced in 96 AA non-DM ESRD cases and 96 non-nephropathy controls (384 chromosomes). Sixty-seven single-nucleotide polymorphisms (SNPs) including 51 novel SNPs were identified. The SNPs comprised 33 intronic, 21 promoter, 12 exonic, and one 3' variant. Sixty-two of the SNPs were genotyped in 296 AA non-DM ESRD cases and 358 non-nephropathy controls. RESULTS One SNP, rs10404257, was associated with non-DM ESRD (p < 1.0E-4, odds ratio, OR = 0.76; confidence interval, CI = 0.59-0.98; additive model). Forty-seven SNPs had minor allele frequencies <5%. These SNPs were segregated into risk and protective SNPs, and each category was collapsed into a single marker, designated by the presence or absence of any rare allele. The presence of any rare allele at a risk SNP was significantly associated with non-DM ESRD (p = 0.001, dominant model). The SNPs with the strongest evidence for association (n = 20) were genotyped in an independent set of 467 non-DM ESRD cases and 279 controls. Although rs10404257 was not associated in this replication sample, when the samples were combined, rs10404257 was modestly associated (p = 0.032, OR = 0.78, CI = 0.63-0.98; dominant model). SNPs were tested for interaction with markers in the APOL1 gene, previously associated with non-DM ESRD in AAs, and rs10404257 was modestly associated (p = 0.0261, additive model). CONCLUSIONS This detailed evaluation of ACTN4 variation revealed limited evidence of association with non-DM ESRD in AAs.
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Abstract
PURPOSE OF REVIEW Focal segmental glomerulosclerosis (FSGS) is a major cause of nephrotic syndrome and renal failure. All forms of FSGS share podocyte injury and depletion as central mediators. This review focuses on new insights into pathogenesis from study of extrinsic toxins in experimental models, permeability factors in human disease, and novel genetic causes. RECENT FINDINGS Experimental toxin models have advanced our understanding of the threshold and dynamics of podocyte injury. Following initial podocyte depletion, spreading fields of podocyte injury through secondary mediators appear to be important in generating the segmental pathologic lesions. Proliferating glomerular epithelial cells are common in FSGS, although there are conflicting views about their identity. Evidence suggests potential contributions by mature parietal epithelial cells, facultative stem cells and podocytes. A number of novel candidate permeability factors that affect podocyte function and motility have been discovered in human FSGS and related podocytopathy minimal change disease. Exome capture has identified new monogenic causes of familial FSGS. Apolipoprotein L-1 (APOL1) is expressed in podocytes, and the prevalence of APOL1 risk alleles in patients of African descent with primary FSGS and HIV-associated nephropathy is high, implicating potential podocyte effects. SUMMARY FSGS is caused by a complex interplay of inherent genetic susceptibilities and external injurious factors acting on podocytes. Critical levels of podocyte stress eventuate in podocyte depletion, segmental glomerular scarring, and glomerular epithelial cell hyperplasia.
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Büscher AK, Weber S. Educational paper: the podocytopathies. Eur J Pediatr 2012; 171:1151-60. [PMID: 22237399 DOI: 10.1007/s00431-011-1668-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 12/20/2011] [Indexed: 02/07/2023]
Abstract
In the recent past, hereditary podocytopathies have increasingly been recognized to be involved in the development of steroid-resistant nephrotic syndrome (SRNS). Mutations in podocyte genes substantially alter the development and structural architecture of the podocyte including its interdigitating foot processes. These constitute the basis of the slit diaphragm which is an essential part of the glomerular filtration barrier. Depending on the affected protein, the clinical course is variable with respect to onset and severity of the disease as well as treatment options. In general, hereditary podocytopathies are associated with a poorer renal outcome than the non-genetic variants. In addition, they require a different approach with respect to the applied therapeutic strategies as most patients do not respond to immunosuppressive agents. Therefore, genetic testing of podocyte genes should be considered as a routine diagnostic tool for patients with SRNS because the identification of a genetic origin has a direct implication on clinical course, renal outcome, and genetic counseling. In this educational paper, we will give an overview over the podocyte genes identified so far to be involved into the pathophysiology of hereditary podocytopathies.
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Affiliation(s)
- Anja K Büscher
- Pediatric Nephrology, Pediatrics II, University-Children's Hospital Essen, Hufelandstraße 55, 45122 Essen, Germany.
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Tang VW, Brieher WM. α-Actinin-4/FSGS1 is required for Arp2/3-dependent actin assembly at the adherens junction. ACTA ACUST UNITED AC 2012; 196:115-30. [PMID: 22232703 PMCID: PMC3255975 DOI: 10.1083/jcb.201103116] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We have developed an in vitro assay to study actin assembly at cadherin-enriched cell junctions. Using this assay, we demonstrate that cadherin-enriched junctions can polymerize new actin filaments but cannot capture preexisting filaments, suggesting a mechanism involving de novo synthesis. In agreement with this hypothesis, inhibition of Arp2/3-dependent nucleation abolished actin assembly at cell-cell junctions. Reconstitution biochemistry using the in vitro actin assembly assay identified α-actinin-4/focal segmental glomerulosclerosis 1 (FSGS1) as an essential factor. α-Actinin-4 specifically localized to sites of actin incorporation on purified membranes and at apical junctions in Madin-Darby canine kidney cells. Knockdown of α-actinin-4 decreased total junctional actin and inhibited actin assembly at the apical junction. Furthermore, a point mutation of α-actinin-4 (K255E) associated with FSGS failed to support actin assembly and acted as a dominant negative to disrupt actin dynamics at junctional complexes. These findings demonstrate that α-actinin-4 plays an important role in coupling actin nucleation to assembly at cadherin-based cell-cell adhesive contacts.
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Affiliation(s)
- Vivian W Tang
- Department of Cell and Developmental Biology, University of Illinois, Urbana, IL 61801, USA
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Khurana S, Chakraborty S, Lam M, Liu Y, Su YT, Zhao X, Saleem MA, Mathieson PW, Bruggeman LA, Kao HY. Familial focal segmental glomerulosclerosis (FSGS)-linked α-actinin 4 (ACTN4) protein mutants lose ability to activate transcription by nuclear hormone receptors. J Biol Chem 2012; 287:12027-35. [PMID: 22351778 DOI: 10.1074/jbc.m112.345421] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Mutations in α-actinin 4 (ACTN4) are linked to familial forms of focal segmental glomerulosclerosis (FSGS), a kidney disease characterized by proteinuria due to podocyte injury. The mechanisms underlying ACTN4 mutant-associated FSGS are not completely understood. Although α-actinins are better known to cross-link actin filaments and modulate cytoskeletal organization, we have previously shown that ACTN4 interacts with transcription factors including estrogen receptor and MEF2s and potentiates their transcriptional activity. Nuclear receptors including retinoic acid receptor (RAR) have been proposed to play a protective role in podocytes. We show here that ACTN4 interacts with and enhances transcriptional activation by RARα. In addition, FSGS-linked ACTN4 mutants not only mislocalized to the cytoplasm, but also lost their ability to associate with nuclear receptors. Consequently, FSGS-linked ACTN4 mutants failed to potentiate transcriptional activation by nuclear hormone receptors in podocytes. In addition, overexpression of these mutants suppressed the transcriptional activity mediated by endogenous wild-type ACTN4 possibly by a cytoplasmic sequestration mechanism. Our data provide the first link between FSGS-linked ACTN4 mutants and transcriptional activation by nuclear receptor such as RARα and peroxisome proliferator-activated receptor γ.
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Affiliation(s)
- Simran Khurana
- Department of Biochemistry, School of Medicine, Case Western Reserve University and Research Institute of University Hospitals of Cleveland, Cleveland, Ohio 44106, USA
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Gupta V, Discenza M, Guyon JR, Kunkel LM, Beggs AH. α-Actinin-2 deficiency results in sarcomeric defects in zebrafish that cannot be rescued by α-actinin-3 revealing functional differences between sarcomeric isoforms. FASEB J 2012; 26:1892-908. [PMID: 22253474 DOI: 10.1096/fj.11-194548] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
α-Actinins are actin-binding proteins that can be broadly divided into Ca(2+)-sensitive cytoskeletal and Ca(2+)-insensitive sarcomeric isoforms. To date, little is known about functional differences between the isoforms due to their indistinguishable activities in most in vitro assays. To identify functional differences in vivo between sarcomeric isoforms, we employed computational and molecular approaches to characterize the zebrafish (Danio rerio) genome, which contains orthologoues of each human α-actinin gene, including duplicated copies of actn3. Each isoform exhibits a distinct and unique pattern of gene expression as assessed by mRNA in situ hybridization, largely sharing similar expression profiles as seen in humans. The spatial conservation of expression of these genes from lower invertebrates to humans suggests that regulation and subsequent functions of these genes are conserved during evolution. Morpholino-based knockdown of the sarcomeric isoform, actn2, leads to skeletal muscle, cardiac, and ocular defects evident over the first week of development. Remarkably, despite the high degree of sequence conservation between actn2 and actn3, the phenotypes of α-actinin-2 deficient zebrafish can be rescued by overexpression of α-actinin-2 but not by α-actinin-3 mRNAs from zebrafish or human. These data provide functional evidence that the primary sequences of α-actinin-2 and α-actinin-3 evolved differences to optimize their functions.
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Affiliation(s)
- Vandana Gupta
- Division of Genetics, Children's Hospital Boston, 300 Longwood Ave., Boston, MA 02115, USA
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Abstract
Therapeutic off-target activities are well recognized for small-molecule drugs. In contrast, monoclonal antibodies (mAbs) traditionally are believed to act specifically and lack off-target therapeutic effects. In this issue of Science Translational Medicine, Fornoni et al. show therapeutic benefit, through an off-target-mediated mechanism, of the mAb drug rituximab in recurrent focal segmental glomerulosclerosis (FSGS) after kidney transplantation. These data shed new light on FSGS pathogenesis and suggest new therapeutic interventions for proteinuric diseases.
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Affiliation(s)
- Andrew C Chan
- Research Department, Genentech, South San Francisco, CA 94080, USA.
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Podocyte Injury Associated with Mutant α-Actinin-4. JOURNAL OF SIGNAL TRANSDUCTION 2011; 2011:563128. [PMID: 21808733 PMCID: PMC3144672 DOI: 10.1155/2011/563128] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Accepted: 05/08/2011] [Indexed: 11/17/2022]
Abstract
Focal segmental glomerulosclerosis (FSGS) is an important cause of proteinuria and nephrotic syndrome in humans. The pathogenesis of FSGS may be associated with glomerular visceral epithelial cell (GEC; podocyte) injury, leading to apoptosis, detachment, and "podocytopenia", followed by glomerulosclerosis. Mutations in α-actinin-4 are associated with FSGS in humans. In cultured GECs, α-actinin-4 mediates adhesion and cytoskeletal dynamics. FSGS-associated α-actinin-4 mutants show increased binding to actin filaments, compared with the wild-type protein. Expression of an α-actinin-4 mutant in mouse podocytes in vivo resulted in proteinuric FSGS. GECs that express mutant α-actinin-4 show defective spreading and motility, and such abnormalities could alter the mechanical properties of the podocyte, contribute to cytoskeletal disruption, and lead to injury. The potential for mutant α-actinin-4 to injure podocytes is also suggested by the characteristics of this mutant protein to form microaggregates, undergo ubiquitination, impair the ubiquitin-proteasome system, enhance endoplasmic reticulum stress, and exacerbate apoptosis.
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