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Oda K, Katayama K, Zang L, Toda M, Tanoue A, Saiki R, Yasuma T, D’Alessandro-Gabazza CN, Shimada Y, Mori M, Suzuki Y, Murata T, Hirai T, Tryggvason K, Gabazza EC, Dohi K. The Protective Role of KANK1 in Podocyte Injury. Int J Mol Sci 2024; 25:5808. [PMID: 38891998 PMCID: PMC11172089 DOI: 10.3390/ijms25115808] [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: 04/24/2024] [Revised: 05/21/2024] [Accepted: 05/25/2024] [Indexed: 06/21/2024] Open
Abstract
Approximately 30% of steroid-resistant nephrotic syndromes are attributed to monogenic disorders that involve 27 genes. Mutations in KANK family members have also been linked to nephrotic syndrome; however, the precise mechanism remains elusive. To investigate this, podocyte-specific Kank1 knockout mice were generated to examine phenotypic changes. In the initial assessment under normal conditions, Kank1 knockout mice showed no significant differences in the urinary albumin-creatinine ratio, blood urea nitrogen, serum creatinine levels, or histological features compared to controls. However, following kidney injury with adriamycin, podocyte-specific Kank1 knockout mice exhibited a significantly higher albumin-creatinine ratio and a significantly greater sclerotic index than control mice. Electron microscopy revealed more extensive foot process effacement in the knockout mice than in control mice. In addition, KANK1-deficient human podocytes showed increased detachment and apoptosis following adriamycin exposure. These findings suggest that KANK1 may play a protective role in mitigating podocyte damage under pathological conditions.
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Affiliation(s)
- Keiko Oda
- Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, Tsu 514-8507, Mie, Japan; (K.O.); (A.T.); (R.S.); (M.M.); (Y.S.); (T.M.); (K.D.)
| | - Kan Katayama
- Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, Tsu 514-8507, Mie, Japan; (K.O.); (A.T.); (R.S.); (M.M.); (Y.S.); (T.M.); (K.D.)
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 171 77 Stockholm, Sweden;
| | - Liqing Zang
- Graduate School of Regional Innovation Studies, Mie University, Tsu 514-8507, Mie, Japan;
| | - Masaaki Toda
- Department of Immunology, Mie University Graduate School of Medicine, Tsu 514-8507, Mie, Japan; (M.T.); (T.Y.); (C.N.D.-G.); (E.C.G.)
| | - Akiko Tanoue
- Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, Tsu 514-8507, Mie, Japan; (K.O.); (A.T.); (R.S.); (M.M.); (Y.S.); (T.M.); (K.D.)
| | - Ryosuke Saiki
- Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, Tsu 514-8507, Mie, Japan; (K.O.); (A.T.); (R.S.); (M.M.); (Y.S.); (T.M.); (K.D.)
| | - Taro Yasuma
- Department of Immunology, Mie University Graduate School of Medicine, Tsu 514-8507, Mie, Japan; (M.T.); (T.Y.); (C.N.D.-G.); (E.C.G.)
| | - Corina N. D’Alessandro-Gabazza
- Department of Immunology, Mie University Graduate School of Medicine, Tsu 514-8507, Mie, Japan; (M.T.); (T.Y.); (C.N.D.-G.); (E.C.G.)
| | - Yasuhito Shimada
- Department of Integrative Pharmacology, Mie University Graduate School of Medicine, Tsu 514-8507, Mie, Japan;
| | - Mutsuki Mori
- Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, Tsu 514-8507, Mie, Japan; (K.O.); (A.T.); (R.S.); (M.M.); (Y.S.); (T.M.); (K.D.)
| | - Yasuo Suzuki
- Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, Tsu 514-8507, Mie, Japan; (K.O.); (A.T.); (R.S.); (M.M.); (Y.S.); (T.M.); (K.D.)
| | - Tomohiro Murata
- Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, Tsu 514-8507, Mie, Japan; (K.O.); (A.T.); (R.S.); (M.M.); (Y.S.); (T.M.); (K.D.)
| | - Toshinori Hirai
- Department of Pharmacy, Faculty of Medicine, Mie University Hospital, Tsu 514-8507, Mie, Japan;
| | - Karl Tryggvason
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, 171 77 Stockholm, Sweden;
| | - Esteban C. Gabazza
- Department of Immunology, Mie University Graduate School of Medicine, Tsu 514-8507, Mie, Japan; (M.T.); (T.Y.); (C.N.D.-G.); (E.C.G.)
| | - Kaoru Dohi
- Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, Tsu 514-8507, Mie, Japan; (K.O.); (A.T.); (R.S.); (M.M.); (Y.S.); (T.M.); (K.D.)
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Yang Q, Tang D, Gan C, Bai M, Song X, Jiang W, Li Q, Chen Y, Zhang A, Wang M. Novel variants in CRB2 targeting the malfunction of slit diaphragm related to focal segmental glomerulosclerosis. Pediatr Nephrol 2024; 39:149-165. [PMID: 37452832 DOI: 10.1007/s00467-023-06087-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 06/01/2023] [Accepted: 06/29/2023] [Indexed: 07/18/2023]
Abstract
BACKGROUND Focal segmental glomerulosclerosis (FSGS) is a leading cause of steroid-resistant nephrotic syndrome (SRNS) that predominantly affects the podocytes. While mutations in genes causing pediatric SRNS have enhanced our understanding of FSGS, the disease's etiology remains complex and poorly understood. METHODS Whole exome sequencing (WES) was performed on a 9-year-old girl with SRNS associated with FSGS (SRNS-FSGS). We analyzed the expression of CRB2, slit diaphragm (SD)-associated proteins, and sphingosine 1-phosphate receptor 1 (S1PR1) in the proband and CRB2 knock-down podocytes. RESULTS In this study, we identified two novel compound heterozygous mutations in the Crumbs homolog 2 (CRB2) gene (c.2905delinsGCCACCTCGCGCTGGCTG, p.T969Afs*179 and c.3268C > G, p.R1090G) in a family with early-onset SRNS-FSGS. Our findings demonstrate that these CRB2 abnormalities were the underlying cause of SRNS-FSGS. CRB2 defects led to the dysfunction of podocyte SD-related proteins, including podocin, nephrin, and zonula occludens-1 (ZO-1), by reducing the phosphorylation level of S1PR1. Interestingly, the podocytic cytoskeleton remained unaffected, as demonstrated by normal expression and localization of synaptopodin. Our study also revealed a secondary decrease in CRB2 expression in idiopathic FSGS patients, indicating that CRB2 mutations may cause FSGS through a previously unknown mechanism involving SD-related proteins. CONCLUSIONS Overall, our findings shed new light on the pathogenesis of SRNS-FSGS and revealed that the novel pathogenic mutations in CRB2 contribute to the development of FSGS through a previously unknown mechanism involving SD-related proteins. A higher resolution version of the Graphical abstract is available as Supplementary information.
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Affiliation(s)
- Qing Yang
- Pediatric Research Institute, Department of Nephrology Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Chongqing Key Laboratory of Pediatrics, Chongqing Key Laboratory of Child Infection and Immunity, Children's Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Dan Tang
- Department of Pediatrics, The Third Hospital of Mianyang, Sichuan Mental Health Center, Mianyang, 621000, Sichuan, China
| | - Chun Gan
- Pediatric Research Institute, Department of Nephrology Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Chongqing Key Laboratory of Pediatrics, Chongqing Key Laboratory of Child Infection and Immunity, Children's Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Mi Bai
- Department of Nephrology, State Key Laboratory of Reproductive Medicine, Children's Hospital of Nanjing Medical University, 72 Guangzhou Road, Nanjing, 210008, China
| | - Xiaomei Song
- Pediatric Research Institute, Department of Nephrology Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Chongqing Key Laboratory of Pediatrics, Chongqing Key Laboratory of Child Infection and Immunity, Children's Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Wei Jiang
- Pediatric Research Institute, Department of Nephrology Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Chongqing Key Laboratory of Pediatrics, Chongqing Key Laboratory of Child Infection and Immunity, Children's Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Qiu Li
- Pediatric Research Institute, Department of Nephrology Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Chongqing Key Laboratory of Pediatrics, Chongqing Key Laboratory of Child Infection and Immunity, Children's Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Yaxi Chen
- Centre for Lipid Research & Key Laboratory of Molecular Biology for Infectious Diseases (Ministry of Education), Institute for Viral Hepatitis, Department of Infectious Diseases, the Second Affiliated Hospital, Chongqing Medical University, Chongqing, People's Republic of China
| | - Aihua Zhang
- Department of Nephrology, State Key Laboratory of Reproductive Medicine, Children's Hospital of Nanjing Medical University, 72 Guangzhou Road, Nanjing, 210008, China
| | - Mo Wang
- Pediatric Research Institute, Department of Nephrology Children's Hospital of Chongqing Medical University, National Clinical Research Center for Child Health and Disorders, Ministry of Education Key Laboratory of Child Development and Disorders, China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Chongqing Key Laboratory of Pediatrics, Chongqing Key Laboratory of Child Infection and Immunity, Children's Hospital of Chongqing Medical University, Chongqing, People's Republic of China.
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Nguyen TK, Petrikas M, Chambers BE, Wingert RA. Principles of Zebrafish Nephron Segment Development. J Dev Biol 2023; 11:jdb11010014. [PMID: 36976103 PMCID: PMC10052950 DOI: 10.3390/jdb11010014] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 03/08/2023] [Accepted: 03/15/2023] [Indexed: 03/29/2023] Open
Abstract
Nephrons are the functional units which comprise the kidney. Each nephron contains a number of physiologically unique populations of specialized epithelial cells that are organized into discrete domains known as segments. The principles of nephron segment development have been the subject of many studies in recent years. Understanding the mechanisms of nephrogenesis has enormous potential to expand our knowledge about the basis of congenital anomalies of the kidney and urinary tract (CAKUT), and to contribute to ongoing regenerative medicine efforts aimed at identifying renal repair mechanisms and generating replacement kidney tissue. The study of the zebrafish embryonic kidney, or pronephros, provides many opportunities to identify the genes and signaling pathways that control nephron segment development. Here, we describe recent advances of nephron segment patterning and differentiation in the zebrafish, with a focus on distal segment formation.
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Affiliation(s)
- Thanh Khoa Nguyen
- Department of Biological Sciences, Center for Stem Cells and Regenerative Medicine, Center for Zebrafish Research, Boler-Parseghian Center for Rare and Neglected Diseases, Warren Center for Drug Discovery, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Madeline Petrikas
- Department of Biological Sciences, Center for Stem Cells and Regenerative Medicine, Center for Zebrafish Research, Boler-Parseghian Center for Rare and Neglected Diseases, Warren Center for Drug Discovery, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Brooke E Chambers
- Department of Biological Sciences, Center for Stem Cells and Regenerative Medicine, Center for Zebrafish Research, Boler-Parseghian Center for Rare and Neglected Diseases, Warren Center for Drug Discovery, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Rebecca A Wingert
- Department of Biological Sciences, Center for Stem Cells and Regenerative Medicine, Center for Zebrafish Research, Boler-Parseghian Center for Rare and Neglected Diseases, Warren Center for Drug Discovery, University of Notre Dame, Notre Dame, IN 46556, USA
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4
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Möller-Kerutt A, Schönhoff B, Rellmann Y, George B, Braun DA, Pavenstädt H, Weide T. Loss of surface transport is a main cellular pathomechanism of CRB2 variants causing podocytopathies. Life Sci Alliance 2023; 6:6/3/e202201649. [PMID: 36549870 PMCID: PMC9780758 DOI: 10.26508/lsa.202201649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022] Open
Abstract
Crumbs2 (CRB2) is a central component of the renal filtration barrier and part of the slit diaphragm, a unique cell contact formed by glomerular podocytes. Some CRB2 variants cause recessive inherited forms of steroid-resistant nephrotic syndrome. However, the disease-causing potential of numerous CRB2 variants remains unknown. Here, we report the establishment of a live-cell imaging-based assay, allowing a quantitative evaluation of the pathogenic potential of so far non-categorized CRB2 variants. Based on in silico data analysis and protein prediction software, putative disease-associated CRB2 missense variants were selected, expressed as CRB2-GFP fusion proteins, and analyzed in reporter cell lines with BFP-labeled plasma membrane. We found that in comparison with PM-localized WT, disease-associated CRB2 variants remained predominantly at the ER. Accumulation at the ER was also present for several non-characterized CRB2 variants and variants in which putative disulfide bridge-forming cysteines were replaced. Strikingly, WT CRB2 retained inside the ER in cells lacking protein disulfide isomerase A3, indicating that posttranslational modification, especially the formation of disulfide bridges, is a crucial step for the CRB2 PM transport.
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Affiliation(s)
- Annika Möller-Kerutt
- University Hospital of Muenster (UKM), Internal Medicine (MedD), Muenster, Germany
| | - Birgit Schönhoff
- University Hospital of Muenster (UKM), Internal Medicine (MedD), Muenster, Germany
| | - Yvonne Rellmann
- Institute of Physiological Chemistry and Pathobiochemistry, University of Muenster, Muenster, Germany
| | - Britta George
- University Hospital of Muenster (UKM), Internal Medicine (MedD), Muenster, Germany
| | - Daniela Anne Braun
- University Hospital of Muenster (UKM), Internal Medicine (MedD), Muenster, Germany
| | - Hermann Pavenstädt
- University Hospital of Muenster (UKM), Internal Medicine (MedD), Muenster, Germany
| | - Thomas Weide
- University Hospital of Muenster (UKM), Internal Medicine (MedD), Muenster, Germany
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5
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Drummond BE, Ercanbrack WS, Wingert RA. Modeling Podocyte Ontogeny and Podocytopathies with the Zebrafish. J Dev Biol 2023; 11:jdb11010009. [PMID: 36810461 PMCID: PMC9944608 DOI: 10.3390/jdb11010009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 02/11/2023] [Accepted: 02/17/2023] [Indexed: 02/22/2023] Open
Abstract
Podocytes are exquisitely fashioned kidney cells that serve an essential role in the process of blood filtration. Congenital malformation or damage to podocytes has dire consequences and initiates a cascade of pathological changes leading to renal disease states known as podocytopathies. In addition, animal models have been integral to discovering the molecular pathways that direct the development of podocytes. In this review, we explore how researchers have used the zebrafish to illuminate new insights about the processes of podocyte ontogeny, model podocytopathies, and create opportunities to discover future therapies.
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A Missense Variant in PDK1 Associated with Severe Neurodevelopmental Delay and Epilepsy. Biomedicines 2022; 10:biomedicines10123171. [PMID: 36551928 PMCID: PMC9775741 DOI: 10.3390/biomedicines10123171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 12/02/2022] [Accepted: 12/04/2022] [Indexed: 12/13/2022] Open
Abstract
The pyruvate dehydrogenase complex (PDC) is responsible for the conversion of pyruvate into acetyl-CoA, which is used for energy conversion in cells. PDC activity is regulated by phosphorylation via kinases and phosphatases (PDK/PDP). Variants in all subunits of the PDC and in PDK3 have been reported, with varying phenotypes including lactic acidosis, neurodevelopmental delay, peripheral neuropathy, or seizures. Here, we report a de novo heterozygous missense variant in PDK1 (c.1139G > A; p.G380D) in a girl with developmental delay and early onset severe epilepsy. To investigate the role of PDK1G380D in energy metabolism and neuronal development, we used a zebrafish model. In zebrafish embryos we show a reduced number of cells with mitochondria with membrane potential, reduced movements, and a delay in neuronal development. Furthermore, we observe a reduction in the phosphorylation of PDH-E1α by PDKG380D, which suggests a disruption in the regulation of PDC activity. Finally, in patient fibroblasts, a mild reduction in the ratio of phosphorylated PDH over total PDH-E1α was detected. In summary, our findings support the notion that this aberrant PDK1 activity is the cause of clinical symptoms in the patient.
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Hada I, Shimizu A, Takematsu H, Nishibori Y, Kimura T, Fukutomi T, Kudo A, Ito-Nitta N, Kiuchi Z, Patrakka J, Mikami N, Leclerc S, Akimoto Y, Hirayama Y, Mori S, Takano T, Yan K. A Novel Mouse Model of Idiopathic Nephrotic Syndrome Induced by Immunization with the Podocyte Protein Crb2. J Am Soc Nephrol 2022; 33:2008-2025. [PMID: 35985815 PMCID: PMC9678040 DOI: 10.1681/asn.2022010070] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 07/25/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The cause of podocyte injury in idiopathic nephrotic syndrome (INS) remains unknown. Although recent evidence points to the role of B cells and autoimmunity, the lack of animal models mediated by autoimmunity limits further research. We aimed to establish a mouse model mimicking human INS by immunizing mice with Crb2, a transmembrane protein expressed at the podocyte foot process. METHODS C3H/HeN mice were immunized with the recombinant extracellular domain of mouse Crb2. Serum anti-Crb2 antibody, urine protein-to-creatinine ratio, and kidney histology were studied. For signaling studies, a Crb2-expressing mouse podocyte line was incubated with anti-Crb2 antibody. RESULTS Serum anti-Crb2 autoantibodies and significant proteinuria were detected 4 weeks after the first immunization. The proteinuria reached nephrotic range at 9-13 weeks and persisted up to 29 weeks. Initial kidney histology resembled minimal change disease in humans, and immunofluorescence staining showed delicate punctate IgG staining in the glomerulus, which colocalized with Crb2 at the podocyte foot process. A subset of mice developed features resembling FSGS after 18 weeks. In glomeruli of immunized mice and in Crb2-expressing podocytes incubated with anti-Crb2 antibody, phosphorylation of ezrin, which connects Crb2 to the cytoskeleton, increased, accompanied by altered Crb2 localization and actin distribution. CONCLUSION The results highlight the causative role of anti-Crb2 autoantibody in podocyte injury in mice. Crb2 immunization could be a useful model to study the immunologic pathogenesis of human INS, and may support the role of autoimmunity against podocyte proteins in INS.
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Affiliation(s)
- Ichiro Hada
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
| | - Akira Shimizu
- Department of Analytic Human Pathology, Nippon Medical School, Tokyo, Japan
| | - Hiromu Takematsu
- Department of Molecular Cell Biology, Faculty of Medical Technology, Graduate School of Health Sciences, Fujita Health University, Toyoake, Japan
| | - Yukino Nishibori
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
| | - Toru Kimura
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Tokyo, Japan
| | - Toshiyuki Fukutomi
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Tokyo, Japan
| | - Akihiko Kudo
- Department of Microscopic Anatomy, Kyorin University School of Medicine, Tokyo, Japan
| | - Noriko Ito-Nitta
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
| | - Zentaro Kiuchi
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
| | - Jaakko Patrakka
- KI/AZ Integrated Cardio Metabolic Center, Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital, Stockholm, Sweden
| | - Naoaki Mikami
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
| | - Simon Leclerc
- Department of Medicine, Division of Nephrology, Research Institute of the McGill University Health Centre, Montreal, Canada
| | - Yoshihiro Akimoto
- Department of Microscopic Anatomy, Kyorin University School of Medicine, Tokyo, Japan
| | - Yoshiaki Hirayama
- Vaccine & Reagent, R&D Department, Denka Co., Ltd, Gosen-City, Japan
| | - Satoka Mori
- Denka Innovation Center, Denka Co., Ltd, Machida, Japan
| | - Tomoko Takano
- Department of Medicine, Division of Nephrology, Research Institute of the McGill University Health Centre, Montreal, Canada
| | - Kunimasa Yan
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
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8
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Identification and characterization of Crumbs polarity complex proteins in Caenorhabditis elegans. J Biol Chem 2022; 298:101786. [PMID: 35247383 PMCID: PMC9006659 DOI: 10.1016/j.jbc.2022.101786] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 02/12/2022] [Accepted: 02/16/2022] [Indexed: 11/23/2022] Open
Abstract
Crumbs proteins are evolutionarily conserved transmembrane proteins with essential roles in promoting the formation of the apical domain in epithelial cells. The short intracellular tail of Crumbs proteins are known to interact with several proteins, including the scaffolding protein PALS1 (protein associated with LIN7, Stardust in Drosophila). PALS1 in turn binds to a second scaffolding protein PATJ (PALS1-associated tight junction protein) to form the core Crumbs/PALS1/PATJ complex. While essential roles in epithelial organization have been shown for Crumbs proteins in Drosophila and mammalian systems, the three Caenorhabditis elegans crumbs genes are dispensable for epithelial polarization and development. Here, we investigated the presence and function of PALS1 and PATJ orthologs in C. elegans. We identified MAGU-2 as the C. elegans ortholog of PALS1 and show that MAGU-2 interacts with all three Crumbs proteins and localizes to the apical membrane domain of intestinal epithelial cells in a Crumbs-dependent fashion. Similar to crumbs mutants, magu-2 deletion showed no epithelial polarity defects. We also identified MPZ-1 as a candidate ortholog of PATJ based on the physical interaction with MAGU-2 and sequence similarity with PATJ proteins. However, MPZ-1 is not broadly expressed in epithelial tissues and, therefore, not likely a core component of the C. elegans Crumbs complex. Finally, we show overexpression of the Crumbs proteins EAT-20 or CRB-3 can lead to apical membrane expansion in the intestine. Our results shed light on the composition of the C. elegans Crumbs complex and indicate that the role of Crumbs proteins in promoting apical domain formation is conserved.
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9
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Koehler S, Odenthal J, Ludwig V, Jess DU, Höhne M, Jüngst C, Grawe F, Helmstädter M, Janku JL, Bergmann C, Hoyer PF, Hagmann HHH, Walz G, Bloch W, Niessen C, Schermer B, Wodarz A, Denholm B, Benzing T, Iden S, Brinkkoetter PT. Scaffold polarity proteins Par3A and Par3B share redundant functions while Par3B acts independent of atypical protein kinase C/Par6 in podocytes to maintain the kidney filtration barrier. Kidney Int 2021; 101:733-751. [PMID: 34929254 DOI: 10.1016/j.kint.2021.11.030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 11/08/2021] [Accepted: 11/22/2021] [Indexed: 10/19/2022]
Abstract
Glomerular diseases are a major cause for chronic kidney disorders. In most cases podocyte injury is causative for disease development. Cytoskeletal rearrangements and morphological changes are hallmark features of podocyte injury and result in dedifferentiation and loss of podocytes. Here, we establish a link between the Par3 polarity complex and actin regulators necessary to establish and maintain podocyte architecture by utilizing mouse and Drosophila models to characterize the functional role of Par3A and Par3B and its fly homologue Bazooka in vivo. Only simultaneous inactivation of both Par3 proteins caused a severe disease phenotype. Rescue experiments in Drosophila nephrocytes revealed atypical protein kinase C (aPKC)-Par6 dependent and independent effects. While Par3A primarily acts via aPKC-Par6, Par3B function was independent of Par6. Actin-associated synaptopodin protein levels were found to be significantly upregulated upon loss of Par3A/B in mouse podocytes. Tropomyosin2, which shares functional similarities with synaptopodin, was also elevated in Bazooka depleted nephrocytes. The simultaneous depletion of Bazooka and Tropomyosin2 resulted in a partial rescue of the Bazooka knockdown phenotype and prevented increased Rho1, a member of a GTPase protein family regulating the cytoskeleton. The latter contribute to the nephrocyte phenotype observed upon loss of Bazooka. Thus, we demonstrate that Par3 proteins share a high functional redundancy but also have specific functions. Par3A acts in an aPKC-Par6 dependent way and regulates RhoA-GTP levels, while Par3B exploits Par6 independent functions influencing synaptopodin localization. Hence, Par3A and Par3B link elements of polarity signaling and actin regulators to maintain podocyte architecture.
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Affiliation(s)
- Sybille Koehler
- Department II of Internal Medicine; Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Biomedical Sciences, University of Edinburgh, Edinburgh, Scotland, UK.
| | - Johanna Odenthal
- Department II of Internal Medicine; Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Vivian Ludwig
- Department II of Internal Medicine; Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - David Unnersjö Jess
- Department II of Internal Medicine; Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Martin Höhne
- Department II of Internal Medicine; Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Christian Jüngst
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Ferdi Grawe
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany; Molecular Cell Biology, Institute I for Anatomy, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Martin Helmstädter
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Johanna L Janku
- Department II of Internal Medicine; Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Carsten Bergmann
- Medizinische Genetik Mainz, Limbach Genetics, Mainz, Germany; Department of Medicine, Nephrology, University Hospital Freiburg, Germany
| | - Peter F Hoyer
- Klinik für Kinderheilkunde 2, Zentrum für Kinder- und Jugendmedizin, Universitätsklinikum Essen, Essen, Germany
| | - H H Henning Hagmann
- Department II of Internal Medicine; Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Gerd Walz
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Wilhelm Bloch
- Department of Molecular and Cellular Sport Medicine, Institute of Cardiovascular Research and Sport Medicine, German Sport University Cologne, Cologne, Germany
| | - Carien Niessen
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany; Department of Dermatology, University Hospital of Cologne, Cologne, Germany
| | - Bernhard Schermer
- Department II of Internal Medicine; Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Andreas Wodarz
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany; Molecular Cell Biology, Institute I for Anatomy, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
| | - Barry Denholm
- Biomedical Sciences, University of Edinburgh, Edinburgh, Scotland, UK
| | - Thomas Benzing
- Department II of Internal Medicine; Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Sandra Iden
- Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany; Institute for Cell and Developmental Biology, Saarland University, Homburg/Saar, Germany
| | - Paul T Brinkkoetter
- Department II of Internal Medicine; Center for Molecular Medicine Cologne (CMMC), University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany.
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10
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Tanoue A, Katayama K, Ito Y, Joh K, Toda M, Yasuma T, D'Alessandro-Gabazza CN, Kawachi H, Yan K, Ito M, Gabazza EC, Tryggvason K, Dohi K. Podocyte-specific Crb2 knockout mice develop focal segmental glomerulosclerosis. Sci Rep 2021; 11:20556. [PMID: 34654837 PMCID: PMC8519956 DOI: 10.1038/s41598-021-00159-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 10/07/2021] [Indexed: 11/15/2022] Open
Abstract
Crb2 is a cell polarity-related type I transmembrane protein expressed in the apical membrane of podocytes. Knockdown of crb2 causes glomerular permeability defects in zebrafish, and its complete knockout causes embryonic lethality in mice. There are also reports of Crb2 mutations in patients with steroid-resistant nephrotic syndrome, although the precise mechanism is unclear. The present study demonstrated that podocyte-specific Crb2 knockout mice develop massive albuminuria and microhematuria 2-month after birth and focal segmental glomerulosclerosis and tubulointerstitial fibrosis with hemosiderin-laden macrophages at 6-month of age. Transmission and scanning electron microscopic studies demonstrated injury and foot process effacement of podocytes in 6-month aged podocyte-specific Crb2 knockout mice. The number of glomerular Wt1-positive cells and the expressions of Nphs2, Podxl, and Nphs1 were reduced in podocyte-specific Crb2 knockout mice compared to negative control mice. Human podocytes lacking CRB2 had significantly decreased F-actin positive area and were more susceptible to apoptosis than their wild-type counterparts. Overall, this study's results suggest that the specific deprivation of Crb2 in podocytes induces altered actin cytoskeleton reorganization associated with dysfunction and accelerated apoptosis of podocytes that ultimately cause focal segmental glomerulosclerosis.
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Affiliation(s)
- Akiko Tanoue
- Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Mie, 514-8507, Japan
| | - Kan Katayama
- Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Mie, 514-8507, Japan.
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden.
| | - Yugo Ito
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
| | - Kensuke Joh
- Department of Pathology, The Jikei University School of Medicine, Tokyo, Japan
| | - Masaaki Toda
- Department of Immunology, Mie University Graduate School of Medicine, Mie, Japan
| | - Taro Yasuma
- Department of Immunology, Mie University Graduate School of Medicine, Mie, Japan
| | | | - Hiroshi Kawachi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Kunimasa Yan
- Department of Pediatrics, Kyorin University School of Medicine, Tokyo, Japan
| | - Masaaki Ito
- Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Mie, 514-8507, Japan
| | - Esteban C Gabazza
- Department of Immunology, Mie University Graduate School of Medicine, Mie, Japan
| | - Karl Tryggvason
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, Singapore, Singapore
| | - Kaoru Dohi
- Department of Cardiology and Nephrology, Mie University Graduate School of Medicine, 2-174 Edobashi, Tsu, Mie, 514-8507, Japan
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11
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Mysh M, Poulton JS. The Basolateral Polarity Module Promotes Slit Diaphragm Formation in Drosophila Nephrocytes, a Model of Vertebrate Podocytes. J Am Soc Nephrol 2021; 32:1409-1424. [PMID: 33795424 PMCID: PMC8259641 DOI: 10.1681/asn.2020071050] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 02/12/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Podocyte slit diaphragms (SDs) are intercellular junctions that function as size-selective filters, excluding most proteins from urine. Abnormalities in SDs cause proteinuria and nephrotic syndrome. Podocytes exhibit apicobasal polarity, which can affect fundamental aspects of cell biology, including morphology, intercellular junction formation, and asymmetric protein distribution along the plasma membrane. Apical polarity protein mutations cause nephrotic syndrome, and data suggest apical polarity proteins regulate SD formation. However, there is no evidence that basolateral polarity proteins regulate SDs. Thus, the role of apicobasal polarity in podocytes remains unclear. METHODS Genetic manipulations and transgenic reporters determined the effects of disrupting apicobasal polarity proteins in Drosophila nephrocytes, which have SDs similar to those of mammalian podocytes. Confocal and electron microscopy were used to characterize SD integrity after loss of basolateral polarity proteins, and genetic-interaction studies illuminated relationships among apicobasal polarity proteins. RESULTS The study identified four novel regulators of nephrocyte SDs: Dlg, Lgl, Scrib, and Par-1. These proteins comprise the basolateral polarity module and its effector kinase. The data suggest these proteins work together, with apical polarity proteins, to regulate SDs by promoting normal endocytosis and trafficking of SD proteins. CONCLUSIONS Given the recognized importance of apical polarity proteins and SD protein trafficking in podocytopathies, the findings connecting basolateral polarity proteins to these processes significantly advance our understanding of SD regulation.
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Affiliation(s)
- Michael Mysh
- Department of Biology, UNC Kidney Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - John S. Poulton
- Division of Nephrology and Hypertension, Department of Medicine, UNC Kidney Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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12
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Möller-Kerutt A, Rodriguez-Gatica JE, Wacker K, Bhatia R, Siebrasse JP, Boon N, Van Marck V, Boor P, Kubitscheck U, Wijnholds J, Pavenstädt H, Weide T. Crumbs2 Is an Essential Slit Diaphragm Protein of the Renal Filtration Barrier. J Am Soc Nephrol 2021; 32:1053-1070. [PMID: 33687977 PMCID: PMC8259666 DOI: 10.1681/asn.2020040501] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 12/28/2020] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Crumbs2 is expressed at embryonic stages as well as in the retina, brain, and glomerular podocytes. Recent studies identified CRB2 mutations as a novel cause of steroid-resistant nephrotic syndrome (SRNS). METHODS To study the function of Crb2 at the renal filtration barrier, mice lacking Crb2 exclusively in podocytes were generated. Gene expression and histologic studies as well as transmission and scanning electron microscopy were used to analyze these Crb2podKO knockout mice and their littermate controls. Furthermore, high-resolution expansion microscopy was used to investigate Crb2 distribution in murine glomeruli. For pull-down experiments, live cell imaging, and transcriptome analyses, cell lines were applied that inducibly express fluorescent protein-tagged CRB2 wild type and mutants. RESULTS Crb2podKO mice developed proteinuria directly after birth that preceded a prominent development of disordered and effaced foot processes, upregulation of renal injury and inflammatory markers, and glomerulosclerosis. Pull-down assays revealed an interaction of CRB2 with Nephrin, mediated by their extracellular domains. Expansion microscopy showed that in mice glomeruli, Crb2 and Nephrin are organized in adjacent clusters. SRNS-associated CRB2 protein variants and a mutant that lacks a putative conserved O-glycosylation site were not transported to the cell surface. Instead, mutants accumulated in the ER, showed altered glycosylation pattern, and triggered an ER stress response. CONCLUSIONS Crb2 is an essential component of the podocyte's slit diaphragm, interacting with Nephrin. Loss of slit diaphragm targeting and increasing ER stress are pivotal factors for onset and progression of CRB2-related SRNS.
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Affiliation(s)
- Annika Möller-Kerutt
- Internal Medicine D, Department of Molecular Nephrology, University Hospital of Muenster, Muenster, Germany
| | - Juan E. Rodriguez-Gatica
- Institute of Physical and Theoretical Chemistry, Department of Biophysical Chemistry, Rheinische Friedrich Wilhelms University Bonn, Bonn, Germany
| | - Karin Wacker
- Internal Medicine D, Department of Molecular Nephrology, University Hospital of Muenster, Muenster, Germany
| | - Rohan Bhatia
- Institute of Physical and Theoretical Chemistry, Department of Biophysical Chemistry, Rheinische Friedrich Wilhelms University Bonn, Bonn, Germany
| | - Jan-Peter Siebrasse
- Institute of Physical and Theoretical Chemistry, Department of Biophysical Chemistry, Rheinische Friedrich Wilhelms University Bonn, Bonn, Germany
| | - Nanda Boon
- Leiden University Medical Center, Department of Ophthalmology, Leiden, The Netherlands
| | - Veerle Van Marck
- Gerhard-Domagk Institute of Pathology, University Hospital of Muenster, Muenster, Germany
| | - Peter Boor
- Institute of Pathology, Department of Nephrology and Immunology, RWTH Aachen University Hospital, Aachen, Germany,The Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Ulrich Kubitscheck
- Institute of Physical and Theoretical Chemistry, Department of Biophysical Chemistry, Rheinische Friedrich Wilhelms University Bonn, Bonn, Germany
| | - Jan Wijnholds
- Leiden University Medical Center, Department of Ophthalmology, Leiden, The Netherlands
| | - Hermann Pavenstädt
- Internal Medicine D, Department of Molecular Nephrology, University Hospital of Muenster, Muenster, Germany
| | - Thomas Weide
- Internal Medicine D, Department of Molecular Nephrology, University Hospital of Muenster, Muenster, Germany
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13
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Zhu B, Cao A, Li J, Young J, Wong J, Ashraf S, Bierzynska A, Menon MC, Hou S, Sawyers C, Campbell KN, Saleem MA, He JC, Hildebrandt F, D'Agati VD, Peng W, Kaufman L. Disruption of MAGI2-RapGEF2-Rap1 signaling contributes to podocyte dysfunction in congenital nephrotic syndrome caused by mutations in MAGI2. Kidney Int 2019; 96:642-655. [PMID: 31171376 PMCID: PMC7259463 DOI: 10.1016/j.kint.2019.03.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Revised: 03/03/2019] [Accepted: 03/14/2019] [Indexed: 11/21/2022]
Abstract
The essential role of membrane associated guanylate kinase 2 (MAGI2) in podocytes is indicated by the phenotypes of severe glomerulosclerosis of both MAGI2 knockout mice and in patients with congenital nephrotic syndrome (CNS) caused by mutations in MAGI2. Here, we show that MAGI2 forms a complex with the Rap1 guanine nucleotide exchange factor, RapGEF2, and that this complex is lost when expressing MAGI2 CNS variants. Co-expression of RapGEF2 with wild-type MAGI2, but not MAGI2 CNS variants, enhanced activation of the small GTPase Rap1, a central signaling node in podocytes. In mice, podocyte-specific RapGEF2 deletion resulted in spontaneous glomerulosclerosis, with qualitative glomerular features comparable to MAGI2 knockout mice. Knockdown of RapGEF2 or MAGI2 in human podocytes caused similar reductions in levels of Rap1 activation and Rap1-mediated downstream signaling. Furthermore, human podocytes expressing MAGI2 CNS variants show severe abnormalities of cellular morphology and dramatic loss of actin cytoskeletal organization, features completely rescued by pharmacological activation of Rap1 via a non-MAGI2 dependent upstream pathway. Finally, immunostaining of kidney sections from patients with congenital nephrotic syndrome and MAGI2 mutations showed reduced podocyte Rap1-mediated signaling. Thus, MAGI2-RapGEF2-Rap1 signaling is essential for normal podocyte function. Hence, disruption of this pathway is an important cause of the renal phenotype induced by MAGI2 CNS mutations.
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Affiliation(s)
- Bingbing Zhu
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA; Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Aili Cao
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA; Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Jianhua Li
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - James Young
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Jenny Wong
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Shazia Ashraf
- Division of Nephrology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Agnieszka Bierzynska
- University of Bristol, Children's Renal Unit and Bristol Renal, Bristol, United Kingdom
| | - Madhav C Menon
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Steven Hou
- National Cancer Institute, Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - Charles Sawyers
- Human Oncology and Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | - Kirk N Campbell
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Moin A Saleem
- University of Bristol, Children's Renal Unit and Bristol Renal, Bristol, United Kingdom
| | - John C He
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Friedhelm Hildebrandt
- Division of Nephrology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Vivette D D'Agati
- Renal Pathology Laboratory, Columbia University Medical Center, New York, New York, USA
| | - Wen Peng
- Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
| | - Lewis Kaufman
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
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14
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Khalil R, Lalai RA, Wiweger MI, Avramut CM, Koster AJ, Spaink HP, Bruijn JA, Hogendoorn PCW, Baelde HJ. Glomerular permeability is not affected by heparan sulfate glycosaminoglycan deficiency in zebrafish embryos. Am J Physiol Renal Physiol 2019; 317:F1211-F1216. [PMID: 31461353 DOI: 10.1152/ajprenal.00126.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Proteinuria develops when specific components in the glomerular filtration barrier have impaired function. Although the precise components involved in maintaining this barrier have not been fully identified, heparan sulfate proteoglycans are believed to play an essential role in maintaining glomerular filtration. Although in situ studies have shown that a loss of heparan sulfate glycosaminoglycans increases the permeability of the glomerular filtration barrier, recent studies using experimental models have shown that podocyte-specific deletion of heparan sulfate glycosaminoglycan assembly does not lead to proteinuria. However, tubular reabsorption of leaked proteins might have masked an increase in glomerular permeability in these models. Furthermore, not only podocytes but also glomerular endothelial cells are involved in heparan sulfate synthesis in the glomerular filtration barrier. Therefore, we investigated the effect of a global heparan sulfate glycosaminoglycan deficiency on glomerular permeability. We used a zebrafish embryo model carrying a homozygous germline mutation in the ext2 gene. Glomerular permeability was assessed with a quantitative dextran tracer injection method. In this model, we accounted for tubular reabsorption. Loss of anionic sites in the glomerular basement membrane was measured using polyethyleneimine staining. Although mutant animals had significantly fewer negatively charged areas in the glomerular basement membrane, glomerular permeability was unaffected. Moreover, heparan sulfate glycosaminoglycan-deficient embryos had morphologically intact podocyte foot processes. Glomerular filtration remains fully functional despite a global reduction of heparan sulfate.
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Affiliation(s)
- Ramzi Khalil
- Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
| | - Reshma A Lalai
- Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Cristina M Avramut
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Abraham J Koster
- Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, The Netherlands
| | - Herman P Spaink
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
| | - Jan A Bruijn
- Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Hans J Baelde
- Department of Pathology, Leiden University Medical Center, Leiden, The Netherlands
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15
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Abstract
The vertebrate kidney is comprised of functional units known as nephrons. Defects in nephron development or activity are a common feature of kidney disease. Current medical treatments are unable to ameliorate the dire consequences of nephron deficit or injury. Although there have been tremendous advancements in our understanding of nephron ontogeny and the response to damage, many significant knowledge gaps still remain. The zebrafish embryo kidney, or pronephros, is an ideal model for many renal development and regeneration studies because it is comprised of nephrons that share conserved features with the nephron units that comprise the mammalian metanephric kidney. In this chapter, we provide an overview about the benefits of using the zebrafish pronephros to study the mechanisms underlying nephrogenesis as well as epithelial repair and regeneration. We subsequently detail methods for the spatiotemporal assessment of gene and protein expression in zebrafish embryos that can be used to extend the understanding of nephron development and disease, and thereby create new opportunities to identify therapeutic strategies for regenerative medicine.
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16
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Kiselev A, Vaz R, Knyazeva A, Sergushichev A, Dmitrieva R, Khudiakov A, Jorholt J, Smolina N, Sukhareva K, Fomicheva Y, Mikhaylov E, Mitrofanova L, Predeus A, Sjoberg G, Rudenko D, Sejersen T, Lindstrand A, Kostareva A. Truncating Variant in Myof Gene Is Associated With Limb-Girdle Type Muscular Dystrophy and Cardiomyopathy. Front Genet 2019; 10:608. [PMID: 31297131 PMCID: PMC6607695 DOI: 10.3389/fgene.2019.00608] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 06/11/2019] [Indexed: 11/13/2022] Open
Abstract
Even though genetic studies of individuals with neuromuscular diseases have uncovered the molecular background of many cardiac disorders such as cardiomyopathies and inherited arrhythmic syndromes, the genetic cause of a proportion of cardiomyopathies associated with neuromuscular phenotype still remains unknown. Here, we present an individual with a combination of cardiomyopathy and limb-girdle type muscular dystrophy where whole exome sequencing identified myoferlin (MYOF)-a member of the Ferlin protein family and close homolog of DYSF-as the most likely candidate gene. The disease-causative role of the identified variant c.[2576delG; 2575G>C], p.G859QfsTer8 is supported by functional studies in vitro using the primary patient's skeletal muscle mesenchymal progenitor cells, including both RNA sequencing and morphological studies, as well as recapitulating the muscle phenotype in vivo in zebrafish. We provide the first evidence supporting a role of MYOF in human muscle disease.
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Affiliation(s)
- Artem Kiselev
- Department of Molecular Biology and Genetics, Almazov National Medical Research Centre, Saint Petersburg, Russia
| | - Raquel Vaz
- Department of Molecular Medicine and Surgery, Centre for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Anastasia Knyazeva
- Department of Molecular Biology and Genetics, Almazov National Medical Research Centre, Saint Petersburg, Russia
| | | | - Renata Dmitrieva
- Department of Molecular Biology and Genetics, Almazov National Medical Research Centre, Saint Petersburg, Russia
| | - Aleksandr Khudiakov
- Department of Molecular Biology and Genetics, Almazov National Medical Research Centre, Saint Petersburg, Russia
| | - John Jorholt
- Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
| | - Natalia Smolina
- Department of Molecular Biology and Genetics, Almazov National Medical Research Centre, Saint Petersburg, Russia.,Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
| | - Ksenia Sukhareva
- Department of Molecular Biology and Genetics, Almazov National Medical Research Centre, Saint Petersburg, Russia
| | - Yulia Fomicheva
- Department of Molecular Biology and Genetics, Almazov National Medical Research Centre, Saint Petersburg, Russia
| | - Evgeny Mikhaylov
- Arrhythmia Department, Almazov National Medical Research Centre, Saint Petersburg, Russia
| | - Lubov Mitrofanova
- Department of Molecular Biology and Genetics, Almazov National Medical Research Centre, Saint Petersburg, Russia
| | - Alexander Predeus
- Computer Technologies Laboratory, ITMO University, Saint Petersburg, Russia.,Bioinformatics Institute, Saint Petersburg, Russia
| | - Gunnar Sjoberg
- Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
| | - Dmitriy Rudenko
- Department of Molecular Biology and Genetics, Almazov National Medical Research Centre, Saint Petersburg, Russia
| | - Thomas Sejersen
- Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
| | - Anna Lindstrand
- Department of Molecular Medicine and Surgery, Centre for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.,Clinical Genetics, Karolinska University Laboratory, Karolinska University Hospital, Stockholm, Sweden
| | - Anna Kostareva
- Department of Molecular Biology and Genetics, Almazov National Medical Research Centre, Saint Petersburg, Russia.,Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
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17
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Cianciolo Cosentino C, Berto A, Pelletier S, Hari M, Loffing J, Neuhauss SCF, Doye V. Moderate Nucleoporin 133 deficiency leads to glomerular damage in zebrafish. Sci Rep 2019; 9:4750. [PMID: 30894603 PMCID: PMC6426968 DOI: 10.1038/s41598-019-41202-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 02/26/2019] [Indexed: 01/13/2023] Open
Abstract
Although structural nuclear pore proteins (nucleoporins) are seemingly required in every cell type to assemble a functional nuclear transport machinery, mutations or deregulation of a subset of them have been associated with specific human hereditary diseases. In particular, previous genetic studies of patients with nephrotic syndrome identified mutations in Nup107 that impaired the expression or the localization of its direct partner at nuclear pores, Nup133. In the present study, we characterized the zebrafish nup133 orthologous gene and its expression pattern during larval development. Using a morpholino-mediated gene knockdown, we show that partial depletion of Nup133 in zebrafish larvae leads to the formation of kidney cysts, a phenotype that can be rescued by co-injection of wild type mRNA. Analysis of different markers for tubular and glomerular development shows that the overall kidney development is not affected by nup133 knockdown. Likewise, no gross defect in nuclear pore complex assembly was observed in these nup133 morphants. On the other hand, nup133 downregulation results in proteinuria and moderate foot process effacement, mimicking some of the abnormalities typically featured by patients with nephrotic syndrome. These data indicate that nup133 is a new gene required for proper glomerular structure and function in zebrafish.
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Affiliation(s)
- Chiara Cianciolo Cosentino
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland.,Institute of Anatomy, University of Zurich, Zurich, Switzerland.,Fondazione RiMED, Palermo, Italy
| | - Alessandro Berto
- Institut Jacques Monod, UMR7592 CNRS-Université Paris Diderot, Sorbonne Paris Cité, F-75205, Paris, France.,Ecole Doctorale SDSV, Université Paris Sud, F-91405, Orsay, France
| | - Stéphane Pelletier
- Institut Jacques Monod, UMR7592 CNRS-Université Paris Diderot, Sorbonne Paris Cité, F-75205, Paris, France
| | - Michelle Hari
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | | | | | - Valérie Doye
- Institut Jacques Monod, UMR7592 CNRS-Université Paris Diderot, Sorbonne Paris Cité, F-75205, Paris, France.
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18
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Sivakumar A, Kurpios NA. Transcriptional regulation of cell shape during organ morphogenesis. J Cell Biol 2018; 217:2987-3005. [PMID: 30061107 PMCID: PMC6122985 DOI: 10.1083/jcb.201612115] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 06/11/2018] [Accepted: 07/17/2018] [Indexed: 02/07/2023] Open
Abstract
The emerging field of transcriptional regulation of cell shape changes aims to address the critical question of how gene expression programs produce a change in cell shape. Together with cell growth, division, and death, changes in cell shape are essential for organ morphogenesis. Whereas most studies of cell shape focus on posttranslational events involved in protein organization and distribution, cell shape changes can be genetically programmed. This review highlights the essential role of transcriptional regulation of cell shape during morphogenesis of the heart, lungs, gastrointestinal tract, and kidneys. We emphasize the evolutionary conservation of these processes across different model organisms and discuss perspectives on open questions and research avenues that may provide mechanistic insights toward understanding birth defects.
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Affiliation(s)
- Aravind Sivakumar
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - Natasza A Kurpios
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY
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19
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Elmonem MA, Berlingerio SP, van den Heuvel LP, de Witte PA, Lowe M, Levtchenko EN. Genetic Renal Diseases: The Emerging Role of Zebrafish Models. Cells 2018; 7:cells7090130. [PMID: 30200518 PMCID: PMC6162634 DOI: 10.3390/cells7090130] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Revised: 08/27/2018] [Accepted: 08/29/2018] [Indexed: 12/14/2022] Open
Abstract
The structural and functional similarity of the larval zebrafish pronephros to the human nephron, together with the recent development of easier and more precise techniques to manipulate the zebrafish genome have motivated many researchers to model human renal diseases in the zebrafish. Over the last few years, great advances have been made, not only in the modeling techniques of genetic diseases in the zebrafish, but also in how to validate and exploit these models, crossing the bridge towards more informative explanations of disease pathophysiology and better designed therapeutic interventions in a cost-effective in vivo system. Here, we review the significant progress in these areas giving special attention to the renal phenotype evaluation techniques. We further discuss the future applications of such models, particularly their role in revealing new genetic diseases of the kidney and their potential use in personalized medicine.
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Affiliation(s)
- Mohamed A Elmonem
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven-University of Leuven, Herestraat 49, Box 817, 3000 Leuven, Belgium.
- Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, 11628 Cairo, Egypt.
| | - Sante Princiero Berlingerio
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven-University of Leuven, Herestraat 49, Box 817, 3000 Leuven, Belgium.
| | - Lambertus P van den Heuvel
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven-University of Leuven, Herestraat 49, Box 817, 3000 Leuven, Belgium.
- Department of Pediatric Nephrology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands.
| | - Peter A de Witte
- Laboratory for Molecular Bio-Discovery, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven-University of Leuven, 3000 Leuven, Belgium.
| | - Martin Lowe
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PL, UK.
| | - Elena N Levtchenko
- Department of Pediatric Nephrology & Development and Regeneration, University Hospitals Leuven, KU Leuven-University of Leuven, Herestraat 49, Box 817, 3000 Leuven, Belgium.
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20
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Fan J, Fu R, Ren F, He J, Wang S, Gou M. A case report of CRB2 mutation identified in a Chinese boy with focal segmental glomerulosclerosis. Medicine (Baltimore) 2018; 97:e12362. [PMID: 30212996 PMCID: PMC6156060 DOI: 10.1097/md.0000000000012362] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
RATIONALE Focal segmental glomerulosclerosis (FSGS) is a common disease resulting in end-stage renal disease. The incidence of FSGS is increasing in Western countries. The clinical manifestations include proteinuria, hypoproteinemia, oedema, and hypertension. Single-gene heritable mutations are considered to be the source of FSGS pathogenicity according to recent in-depth studies on the pathogenesis. Here, we first reported the case of a Chinese boy whose histology presented with FSGS caused by a compound heterozygous mutation. PATIENT CONCERNS A 7-year-old Chinese boy was repeatedly admitted to our hospital for fever, cough, and proteinuria since he was 1.6 years old. DIAGNOSES FSGS was identified by renal biopsy. Whole exome sequencing (WES) showed that a novel mutation of crumbs homolog 2 (CRB2) was identified in a Chinese boy with FSGS. INTERVENTIONS Patient was treated with low-dose corticosteroid and mycophenolate mofetil for maintenance therapy. OUTCOMES At last follow-up, protein (+∼++) was observed in his urinalysis. LESSONS We identified a novel mutation of CRB2 in a Chinese boy with FSGS that had never been described in a previous report. These findings suggested that mutations in recessive disease genes are more frequent among early-onset disease.
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21
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Association of crumbs homolog-2 with mTORC1 in developing podocyte. PLoS One 2018; 13:e0202400. [PMID: 30125302 PMCID: PMC6101391 DOI: 10.1371/journal.pone.0202400] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 08/02/2018] [Indexed: 02/06/2023] Open
Abstract
The evidence that gene mutations in the polarity determinant Crumbs homologs-2 (CRB2) cause congenital nephrotic syndrome suggests the functional importance of this gene product in podocyte development. Because another isoform, CRB3, was reported to repress the mechanistic/mammalian target of the rapamycin complex 1 (mTORC1) pathway, we examined the role of CRB2 function in developing podocytes in relation to mTORC1. In HEK-293 and MDCK cells constitutively expressing CRB2, we found that the protein localized to the apicolateral side of the cell plasma membrane and that this plasma membrane assembly required N-glycosylation. Confocal microscopy of the neonate mouse kidney revealed that both the tyrosine-phosphorylated form and non-phosphorylated form of CRB2 commence at the S-shaped body stage at the apicolateral side of podocyte precursor cells and move to foot processes in a capillary tuft pattern. The pattern of phosphorylated mTOR in developing podocytes was similar to that of CRB2 tyrosine phosphorylation. Additionally, the lack of a tyrosine phosphorylation site on CRB2 led to the reduced sensitivity of mTORC1 activation in response to energy starvation. CRB2 may play an important role in the mechanistic pathway of developing podocytes through tyrosine phosphorylation by associating with mTORC1 activation.
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22
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Hochapfel F, Denk L, Mendl G, Schulze U, Maaßen C, Zaytseva Y, Pavenstädt H, Weide T, Rachel R, Witzgall R, Krahn MP. Distinct functions of Crumbs regulating slit diaphragms and endocytosis in Drosophila nephrocytes. Cell Mol Life Sci 2017; 74:4573-4586. [PMID: 28717874 PMCID: PMC11107785 DOI: 10.1007/s00018-017-2593-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 06/26/2017] [Accepted: 07/13/2017] [Indexed: 10/19/2022]
Abstract
Mammalian podocytes, the key determinants of the kidney's filtration barrier, differentiate from columnar epithelial cells and several key determinants of apical-basal polarity in the conventional epithelia have been shown to regulate podocyte morphogenesis and function. However, little is known about the role of Crumbs, a conserved polarity regulator in many epithelia, for slit-diaphragm formation and podocyte function. In this study, we used Drosophila nephrocytes as model system for mammalian podocytes and identified a conserved function of Crumbs proteins for cellular morphogenesis, nephrocyte diaphragm assembly/maintenance, and endocytosis. Nephrocyte-specific knock-down of Crumbs results in disturbed nephrocyte diaphragm assembly/maintenance and decreased endocytosis, which can be rescued by Drosophila Crumbs as well as human Crumbs2 and Crumbs3, which were both expressed in human podocytes. In contrast to the extracellular domain, which facilitates nephrocyte diaphragm assembly/maintenance, the intracellular FERM-interaction motif of Crumbs is essential for regulating endocytosis. Moreover, Moesin, which binds to the FERM-binding domain of Crumbs, is essential for efficient endocytosis. Thus, we describe here a new mechanism of nephrocyte development and function, which is likely to be conserved in mammalian podocytes.
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Affiliation(s)
- Florian Hochapfel
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany
| | - Lucia Denk
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Gudrun Mendl
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Ulf Schulze
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany
| | - Christine Maaßen
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Yulia Zaytseva
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Hermann Pavenstädt
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany
| | - Thomas Weide
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany
| | - Reinhard Rachel
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Ralph Witzgall
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany
| | - Michael P Krahn
- Molecular and Cellular Anatomy, University of Regensburg, Universitätsstr. 31, 93053, Regensburg, Germany.
- Medizinische Klinik und Poliklinik D, Universitätsklinikum Münster, Domagkstr. 3a, 48149, Münster, Germany.
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23
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Dissecting the genetic components of a quantitative trait locus for blood pressure and renal pathology on rat chromosome 3. J Hypertens 2017; 35:319-329. [PMID: 27755386 PMCID: PMC5214373 DOI: 10.1097/hjh.0000000000001155] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND We have previously confirmed the importance of rat chromosome 3 (RNO3) genetic loci on blood pressure elevation, pulse pressure (PP) variability and renal pathology during salt challenge in the stroke-prone spontaneously hypertensive (SHRSP) rat. The aims of this study were to generate a panel of RNO3 congenic sub-strains to genetically dissect the implicated loci and identify positional candidate genes by microarray expression profiling and analysis of next-generation sequencing data. METHOD AND RESULTS A panel of congenic sub-strains were generated containing Wistar-Kyoto (WKY)-introgressed segments of varying size on the SHRSP genetic background, focused within the first 50 Mbp of RNO3. Haemodynamic profiling during salt challenge demonstrated significantly reduced systolic blood pressure, diastolic blood pressure and PP variability in SP.WKYGla3a, SP.WKYGla3c, SP.WKYGla3d and SP.WKYGla3e sub-strains. Only SBP and DBP were significantly reduced during salt challenge in SP.WKYGla3b and SP.WKYGla3f sub-strains, whereas SP.WKYGla3g rats did not differ in haemodynamic response to SHRSP. Those sub-strains demonstrating significantly reduced PP variability during salt challenge also demonstrated significantly reduced renal pathology and proteinuria. Microarray expression profiling prioritized two candidate genes for blood pressure regulation (Dnm1, Tor1b), localized within the common congenic interval shared by SP.WKYGla3d and SP.WKYGla3f strains, and one candidate gene for salt-induced PP variability and renal pathology (Rabgap1), located within the region unique to the SP.WKYGla3d strain. Comparison of next-generation sequencing data identified variants within additional positional genes that are likely to affect protein function. CONCLUSION This study has identified distinct intervals on RNO3-containing genes that may be important for blood pressure regulation and renal pathology during salt challenge.
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24
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Udagawa T, Jo T, Yanagihara T, Shimizu A, Mitsui J, Tsuji S, Morishita S, Onai R, Miura K, Kanda S, Kajiho Y, Tsurumi H, Oka A, Hattori M, Harita Y. Altered expression of Crb2 in podocytes expands a variation of CRB2 mutations in steroid-resistant nephrotic syndrome. Pediatr Nephrol 2017; 32:801-809. [PMID: 27942854 DOI: 10.1007/s00467-016-3549-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 11/02/2016] [Accepted: 11/08/2016] [Indexed: 10/20/2022]
Abstract
BACKGROUND Steroid-resistant nephrotic syndrome (SRNS) is a genetically heterogeneous disorder for which more than 25 single-gene hereditary causes have been identified. METHODS Whole exome sequencing was performed in a 3-year-old girl with SRNS. We analyzed the expression of Crb2 and slit diaphragm molecules in the patient's glomeruli, and compared it with that of controls or other nephrotic patients. RESULTS Whole-exome analysis identified novel compound heterozygous mutations in exons 10 and 12 of CRB2 (p.Trp1086ArgfsX64 and p.Asn1184Thr, each from different parents; Asn1184 within extracellular 15th EGF repeat domain). Renal pathology showed focal segmental glomerulosclerosis with effaced podocyte foot processes in a small area, with significantly decreased Crb2 expression. Molecules critical for slit diaphragm were well-expressed in this patient's podocytes. Crb2 expression was not altered in the other patients with congenital nephrotic syndrome with NPHS1 mutations. CONCLUSIONS These findings demonstrate that Crb2 abnormalities caused by these mutations are the mechanism of steroid-resistant NS. Although CRB2 mutations previously found in SRNS patients have been clustered within the extracellular tenth EGF-like domain of this protein, the present results expand the variation of CRB2 mutations that cause SRNS.
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Affiliation(s)
- Tomohiro Udagawa
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Tohaku Jo
- Department of Pediatrics, Nippon Medical School, Tokyo, Japan
| | | | - Akira Shimizu
- Department of Analytic Human Pathology, Nippon Medical School, Bunkyo-ku, Tokyo, Japan
| | - Jun Mitsui
- Department of Neurology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Shoji Tsuji
- Department of Neurology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Shinichi Morishita
- Department of Computational Biology and Medical Sciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, Japan
| | - Reiko Onai
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Kenichiro Miura
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Shoichiro Kanda
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Yuko Kajiho
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Haruko Tsurumi
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Akira Oka
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Motoshi Hattori
- Department of Pediatric Nephrology, Tokyo Women's Medical University, Sinjuku-ku, Tokyo, Japan
| | - Yutaka Harita
- Department of Pediatrics, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
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25
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Slavotinek AM. The Family of Crumbs Genes and Human Disease. Mol Syndromol 2016; 7:274-281. [PMID: 27867342 DOI: 10.1159/000448109] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/19/2016] [Indexed: 11/19/2022] Open
Abstract
The family of vertebrate Crumbs proteins, homologous to Drosophila Crumbs (Crb), share large extracellular domains with epidermal growth factor-like repeats and laminin-globular domains, a single transmembrane domain, and a short intracellular C-terminus containing a single membrane proximal 4.1/ezrin/radixin/moesin-binding domain and PSD-95/Discs large/ZO-1-binding motifs. There are 3 Crb genes in humans - Crumbs homolog-1 (CRB1), Crumbs homolog-2 (CRB2), and Crumbs homolog-3 (CRB3). Bilallelic loss-of-function mutations in CRB1 cause visual impairment, with Leber's congenital amaurosis and retinitis pigmentosa, whereas CRB2 mutations are associated with raised maternal serum and amniotic fluid alpha feto-protein levels, ventriculomegaly/hydrocephalus, and renal disease, ranging from focal segmental glomerulosclerosis to congenital Finnish nephrosis. CRB3 has not yet been associated with human disease. In this review, we summarize the phenotypic findings associated with deleterious sequence variants in CRB1 and CRB2. We discuss the mutational spectrum, animal models of loss of function for both genes and speculate on the likely mechanisms of disease.
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Affiliation(s)
- Anne M Slavotinek
- Department of Pediatrics, UCSF School of Medicine, University of California San Francisco, San Francisco, Calif., USA
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26
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Djuric I, Siebrasse JP, Schulze U, Granado D, Schlüter MA, Kubitscheck U, Pavenstädt H, Weide T. The C-terminal domain controls the mobility of Crumbs 3 isoforms. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:1208-17. [DOI: 10.1016/j.bbamcr.2016.03.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 03/07/2016] [Accepted: 03/08/2016] [Indexed: 01/12/2023]
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27
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Zhu X, Chen Z, Zeng C, Wang L, Xu F, Hou Q, Liu Z. Ultrastructural characterization of the pronephric glomerulus development in zebrafish. J Morphol 2016; 277:1104-12. [PMID: 27185367 DOI: 10.1002/jmor.20560] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 04/18/2016] [Accepted: 04/23/2016] [Indexed: 12/12/2022]
Affiliation(s)
- Xiaodong Zhu
- National Clinical Research Center of Kidney Disease; Jinling Hospital, Nanjing University School of Medicine; Nanjing China
| | - Zhaohong Chen
- National Clinical Research Center of Kidney Disease; Jinling Hospital, Nanjing University School of Medicine; Nanjing China
| | - Caihong Zeng
- National Clinical Research Center of Kidney Disease; Jinling Hospital, Nanjing University School of Medicine; Nanjing China
| | - Ling Wang
- National Clinical Research Center of Kidney Disease; Jinling Hospital, Nanjing University School of Medicine; Nanjing China
| | - Feng Xu
- National Clinical Research Center of Kidney Disease; Jinling Hospital, Nanjing University School of Medicine; Nanjing China
| | - Qing Hou
- National Clinical Research Center of Kidney Disease; Jinling Hospital, Nanjing University School of Medicine; Nanjing China
| | - Zhihong Liu
- National Clinical Research Center of Kidney Disease; Jinling Hospital, Nanjing University School of Medicine; Nanjing China
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28
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Koehler S, Tellkamp F, Niessen CM, Bloch W, Kerjaschki D, Schermer B, Benzing T, Brinkkoetter PT. Par3A is dispensable for the function of the glomerular filtration barrier of the kidney. Am J Physiol Renal Physiol 2016; 311:F112-9. [PMID: 27122542 DOI: 10.1152/ajprenal.00171.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 04/22/2016] [Indexed: 01/08/2023] Open
Abstract
Polarity signaling through the atypical PKC (aPKC)-Par polarity complex is essential for the development and maintenance of the podocyte architecture and the function of the glomerular filtration barrier of the kidney. To study the contribution of Par3A in this complex, we generated a novel Pard3 podocyte-specific knockout mouse model by targeting exon 6 of the Pard3 gene. Genetic deletion of Pard3a did not impair renal function, neither at birth nor later in life. Even challenging the animals did not result in glomerular disease. Despite its well-established role in aPKC-mediated signaling, Par3A appears to be dispensable for the function of the glomerular filtration barrier. Moreover, its homolog Pard3b, and not Pard3a, is the dominant Par3 gene expressed in podocytes and found at the basis of the slit diaphragm, where it partially colocalizes with podocin. In conclusion, Par3A function is either dispensable for slit diaphragm integrity, or compensatory mechanisms and a high redundancy of the different polarity proteins, including Par3B, Lgl, or PALS1, maintain the function of the glomerular filtration barrier, even in the absence of Par3A.
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Affiliation(s)
- Sybille Koehler
- Department II of Internal Medicine, University Hospital of Cologne, Cologne, Germany; Center for Molecular Medicine, University of Cologne, Cologne, Germany
| | - Frederik Tellkamp
- Center for Molecular Medicine, University of Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany; Department of Dermatology, University Hospital of Cologne, Cologne, Germany
| | - Carien M Niessen
- Center for Molecular Medicine, University of Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany; Department of Dermatology, University Hospital of Cologne, Cologne, Germany
| | - Wilhelm Bloch
- Department of Molecular and Cellular Sport Medicine, Institute of Cardiovascular Research and Sport Medicine, German Sport University Cologne, Cologne, Germany, and
| | - Dontscho Kerjaschki
- Clinical Institute of Pathology, Medical University of Vienna, Vienna, Austria
| | - Bernhard Schermer
- Department II of Internal Medicine, University Hospital of Cologne, Cologne, Germany; Center for Molecular Medicine, University of Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany; Systems Biology of Ageing Cologne (Sybacol), University of Cologne, Cologne, Germany
| | - Thomas Benzing
- Department II of Internal Medicine, University Hospital of Cologne, Cologne, Germany; Center for Molecular Medicine, University of Cologne, Cologne, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany; Systems Biology of Ageing Cologne (Sybacol), University of Cologne, Cologne, Germany
| | - Paul T Brinkkoetter
- Department II of Internal Medicine, University Hospital of Cologne, Cologne, Germany; Center for Molecular Medicine, University of Cologne, Cologne, Germany;
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Abstract
The kidney of the zebrafish shares many features with other vertebrate kidneys including the human kidney. Similar cell types and shared developmental and patterning mechanisms make the zebrafish pronephros a valuable model for kidney organogenesis. Here we review recent advances in studies of zebrafish pronephric development and provide experimental protocols to analyze kidney cell types and structures, measure nephron function, live image kidney cells in vivo, and probe mechanisms of kidney regeneration after injury.
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Affiliation(s)
- I A Drummond
- Massachusetts General Hospital, Charlestown, MA, United States
| | - A J Davidson
- The University of Auckland, Auckland, New Zealand
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30
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Rodriguez PQ, Oddsson A, Ebarasi L, He B, Hultenby K, Wernerson A, Betsholtz C, Tryggvason K, Patrakka J. Knockdown of Tmem234 in zebrafish results in proteinuria. Am J Physiol Renal Physiol 2015; 309:F955-66. [PMID: 26377798 DOI: 10.1152/ajprenal.00525.2014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 09/10/2015] [Indexed: 12/15/2022] Open
Abstract
Podocytes are highly specialized epithelial cells located at the outer aspects of the glomerular capillary tuft and critical components of the kidney filtration barrier. To maintain their unique features, podocytes express a number of proteins that are only sparsely found elsewhere in the body. In this study, we have identified four (Tmem234, Znf185, Lrrc49, and Slfn5) new highly podocyte-enriched proteins. The proteins are strongly expressed by podocytes, while other parts of the kidney show only weak or no expression. Tmem234, Slfn5, and Lrrc49 are located in foot processes, whereas Znf185 is found in both foot and major processes. Expressional studies in developing kidneys show that these proteins are first expressed at the capillary stage glomerulus, the same stage when the formation of major and foot processes begins. We identified zebrafish orthologs for Tmem234 and Znf185 genes and knocked down their expression using morpholino technology. Studies in zebrafish larvae indicate that Tmem234 is essential for the organization and functional integrity of the pronephric glomerulus filtration barrier, as inactivation of Tmem234 expression results in foot process effacement and proteinuria. In summary, we have identified four novel highly podocyte-enriched proteins and show that one of them, Tmem234, is essential for the normal filtration barrier in the zebrafish pronephric glomerulus. Identification of new molecular components of the kidney filtration barrier opens up possibilities to study their role in glomerulus biology and diseases.
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Affiliation(s)
- Patricia Q Rodriguez
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden; KI/AZ Integrated CardioMetabolic Center, Department of Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Asmundur Oddsson
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Lwaki Ebarasi
- KI/AZ Integrated CardioMetabolic Center, Department of Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Bing He
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Kjell Hultenby
- Clinical Research Center, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Annika Wernerson
- Division of Renal Medicine, Department of Clinical Science, Intervention, and Technology, Stockholm, Sweden; and
| | - Christer Betsholtz
- Division of Vascular Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden; Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden; and
| | - Karl Tryggvason
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden; Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School, Singapore
| | - Jaakko Patrakka
- KI/AZ Integrated CardioMetabolic Center, Department of Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden;
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31
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Abstract
The function of the kidney, filtering blood and concentrating metabolic waste into urine, takes place in an intricate and functionally elegant structure called the renal glomerulus. Normal glomerular function retains circulating cells and valuable macromolecular components of plasma in blood, resulting in urine with just trace amounts of proteins. Endothelial cells of glomerular capillaries, the podocytes wrapped around them, and the fused extracellular matrix these cells form altogether comprise the glomerular filtration barrier, a dynamic and highly selective filter that sieves on the basis of molecular size and electrical charge. Current understanding of the structural organization and the cellular and molecular basis of renal filtration draws from studies of human glomerular diseases and animal models of glomerular dysfunction.
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Affiliation(s)
- Rizaldy P Scott
- Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
| | - Susan E Quaggin
- Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
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32
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Perisic L, Rodriguez PQ, Hultenby K, Sun Y, Lal M, Betsholtz C, Uhlén M, Wernerson A, Hedin U, Pikkarainen T, Tryggvason K, Patrakka J. Schip1 is a novel podocyte foot process protein that mediates actin cytoskeleton rearrangements and forms a complex with Nherf2 and ezrin. PLoS One 2015; 10:e0122067. [PMID: 25807495 PMCID: PMC4373682 DOI: 10.1371/journal.pone.0122067] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 02/18/2015] [Indexed: 01/28/2023] Open
Abstract
Background Podocyte foot process effacement accompanied by actin cytoskeleton rearrangements is a cardinal feature of many progressive human proteinuric diseases. Results By microarray profiling of mouse glomerulus, SCHIP1 emerged as one of the most highly enriched transcripts. We detected Schip1 protein in the kidney glomerulus, specifically in podocytes foot processes. Functionally, Schip1 inactivation in zebrafish by morpholino knock-down results in foot process disorganization and podocyte loss leading to proteinuria. In cultured podocytes Schip1 localizes to cortical actin-rich regions of lamellipodia, where it forms a complex with Nherf2 and ezrin, proteins known to participate in actin remodeling stimulated by PDGFβ signaling. Mechanistically, overexpression of Schip1 in vitro causes accumulation of cortical F-actin with dissolution of transversal stress fibers and promotes cell migration in response to PDGF-BB stimulation. Upon actin disassembly by latrunculin A treatment, Schip1 remains associated with the residual F-actin-containing structures, suggesting a functional connection with actin cytoskeleton possibly via its interaction partners. A similar assay with cytochalasin D points to stabilization of cortical actin cytoskeleton in Schip1 overexpressing cells by attenuation of actin depolymerisation. Conclusions Schip1 is a novel glomerular protein predominantly expressed in podocytes, necessary for the zebrafish pronephros development and function. Schip1 associates with the cortical actin cytoskeleton network and modulates its dynamics in response to PDGF signaling via interaction with the Nherf2/ezrin complex. Its implication in proteinuric diseases remains to be further investigated.
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Affiliation(s)
- Ljubica Perisic
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
- Division of Vascular Surgery, Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden
| | - Patricia Q. Rodriguez
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Kjell Hultenby
- Clinical Research Center, Department of Laboratory Medicine, Karolinska Institute, Stockholm, Sweden
| | - Ying Sun
- Vascular Biology Division, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Mark Lal
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Christer Betsholtz
- Vascular Biology Division, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Mathias Uhlén
- Department of Biotechnology, Royal Institute of Technology, Stockholm, Sweden
| | - Annika Wernerson
- Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Karolinska Institute, Stockholm, Sweden
| | - Ulf Hedin
- Division of Vascular Surgery, Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden
| | - Timo Pikkarainen
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Karl Tryggvason
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Jaakko Patrakka
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
- * E-mail:
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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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Ebarasi L, Ashraf S, Bierzynska A, Gee H, McCarthy H, Lovric S, Sadowski C, Pabst W, Vega-Warner V, Fang H, Koziell A, Simpson M, Dursun I, Serdaroglu E, Levy S, Saleem M, Hildebrandt F, Majumdar A. Defects of CRB2 cause steroid-resistant nephrotic syndrome. Am J Hum Genet 2015; 96:153-61. [PMID: 25557779 DOI: 10.1016/j.ajhg.2014.11.014] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 11/21/2014] [Indexed: 01/15/2023] Open
Abstract
Nephrotic syndrome (NS), the association of gross proteinuria, hypoalbuminaemia, edema, and hyperlipidemia, can be clinically divided into steroid-sensitive (SSNS) and steroid-resistant (SRNS) forms. SRNS regularly progresses to end-stage renal failure. By homozygosity mapping and whole exome sequencing, we here identify recessive mutations in Crumbs homolog 2 (CRB2) in four different families affected by SRNS. Previously, we established a requirement for zebrafish crb2b, a conserved regulator of epithelial polarity, in podocyte morphogenesis. By characterization of a loss-of-function mutation in zebrafish crb2b, we now show that zebrafish crb2b is required for podocyte foot process arborization, slit diaphragm formation, and proper nephrin trafficking. Furthermore, by complementation experiments in zebrafish, we demonstrate that CRB2 mutations result in loss of function and therefore constitute causative mutations leading to NS in humans. These results implicate defects in podocyte apico-basal polarity in the pathogenesis of NS.
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Slavotinek A, Kaylor J, Pierce H, Cahr M, DeWard S, Schneidman-Duhovny D, Alsadah A, Salem F, Schmajuk G, Mehta L. CRB2 mutations produce a phenotype resembling congenital nephrosis, Finnish type, with cerebral ventriculomegaly and raised alpha-fetoprotein. Am J Hum Genet 2015; 96:162-9. [PMID: 25557780 DOI: 10.1016/j.ajhg.2014.11.013] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 11/21/2014] [Indexed: 12/17/2022] Open
Abstract
We report five fetuses and a child from three families who shared a phenotype comprising cerebral ventriculomegaly and echogenic kidneys with histopathological findings of congenital nephrosis. The presenting features were greatly elevated maternal serum alpha-fetoprotein (MSAFP) or amniotic fluid alpha-fetoprotein (AFAFP) levels or abnormalities visualized on ultrasound scan during the second trimester of pregnancy. Exome sequencing revealed deleterious sequence variants in Crumbs, Drosophila, Homolog of, 2 (CRB2) consistent with autosomal-recessive inheritance. Two fetuses with cerebral ventriculomegaly and renal microcysts were compound heterozygotes for p.Asn800Lys and p.Trp759Ter, one fetus with renal microcysts was a compound heterozygote for p.Glu643Ala and p.Asn800Lys, and one child with cerebral ventriculomegaly, periventricular heterotopias, echogenic kidneys, and renal failure was homozygous for p.Arg633Trp in CRB2. Examination of the kidneys in one fetus showed tubular cysts at the corticomedullary junction and diffuse effacement of the epithelial foot processes and microvillous transformation of the renal podocytes, findings that were similar to those reported in congenital nephrotic syndrome, Finnish type, that is caused by mutations in nephrin (NPHS1). Loss of function for crb2b and nphs1 in Danio rerio were previously shown to result in loss of the slit diaphragms of the podocytes, leading to the hypothesis that nephrosis develops from an inability to develop a functional glomerular barrier. We conclude that the phenotype associated with CRB2 mutations is pleiotropic and that the condition is an important consideration in the evaluation of high MSAFP/AFAFP where a renal cause is suspected.
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Glomerular development--shaping the multi-cellular filtration unit. Semin Cell Dev Biol 2014; 36:39-49. [PMID: 25153928 DOI: 10.1016/j.semcdb.2014.07.016] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 07/29/2014] [Accepted: 07/31/2014] [Indexed: 01/09/2023]
Abstract
The glomerulus represents a highly structured filtration unit, composed of glomerular endothelial cells, mesangial cells, podocytes and parietal epithelial cells. During glomerulogenesis an intricate network of signaling pathways involving transcription factors, secreted factors and cell-cell communication is required to guarantee accurate evolvement of a functional, complex 3-dimensional glomerular architecture. Here, we want to provide an overview on the critical steps and relevant signaling cascades of glomerular development.
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Kroeger PT, Wingert RA. Using zebrafish to study podocyte genesis during kidney development and regeneration. Genesis 2014; 52:771-92. [PMID: 24920186 DOI: 10.1002/dvg.22798] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 06/08/2014] [Accepted: 06/09/2014] [Indexed: 12/21/2022]
Abstract
During development, vertebrates form a progression of up to three different kidneys that are comprised of functional units termed nephrons. Nephron composition is highly conserved across species, and an increasing appreciation of the similarities between zebrafish and mammalian nephron cell types has positioned the zebrafish as a relevant genetic system for nephrogenesis studies. A key component of the nephron blood filter is a specialized epithelial cell known as the podocyte. Podocyte research is of the utmost importance as a vast majority of renal diseases initiate with the dysfunction or loss of podocytes, resulting in a condition known as proteinuria that causes nephron degeneration and eventually leads to kidney failure. Understanding how podocytes develop during organogenesis may elucidate new ways to promote nephron health by stimulating podocyte replacement in kidney disease patients. In this review, we discuss how the zebrafish model can be used to study kidney development, and how zebrafish research has provided new insights into podocyte lineage specification and differentiation. Further, we discuss the recent discovery of podocyte regeneration in adult zebrafish, and explore how continued basic research using zebrafish can provide important knowledge about podocyte genesis in embryonic and adult environments. genesis 52:771-792, 2014. © 2014 Wiley Periodicals, Inc.
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Affiliation(s)
- Paul T Kroeger
- Department of Biological Sciences and Center for Zebrafish Research, University of Notre Dame, Notre Dame, Indiana, 46556
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Gee HY, Ashraf S, Wan X, Vega-Warner V, Esteve-Rudd J, Lovric S, Fang H, Hurd TW, Sadowski CE, Allen SJ, Otto EA, Korkmaz E, Washburn J, Levy S, Williams DS, Bakkaloglu SA, Zolotnitskaya A, Ozaltin F, Zhou W, Hildebrandt F. Mutations in EMP2 cause childhood-onset nephrotic syndrome. Am J Hum Genet 2014; 94:884-90. [PMID: 24814193 DOI: 10.1016/j.ajhg.2014.04.010] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 04/11/2014] [Indexed: 01/27/2023] Open
Abstract
Nephrotic syndrome (NS) is a genetically heterogeneous group of diseases that are divided into steroid-sensitive NS (SSNS) and steroid-resistant NS (SRNS). SRNS inevitably leads to end-stage kidney disease, and no curative treatment is available. To date, mutations in more than 24 genes have been described in Mendelian forms of SRNS; however, no Mendelian form of SSNS has been described. To identify a genetic form of SSNS, we performed homozygosity mapping, whole-exome sequencing, and multiplex PCR followed by next-generation sequencing. We thereby detected biallelic mutations in EMP2 (epithelial membrane protein 2) in four individuals from three unrelated families affected by SRNS or SSNS. We showed that EMP2 exclusively localized to glomeruli in the kidney. Knockdown of emp2 in zebrafish resulted in pericardial effusion, supporting the pathogenic role of mutated EMP2 in human NS. At the cellular level, we showed that knockdown of EMP2 in podocytes and endothelial cells resulted in an increased amount of CAVEOLIN-1 and decreased cell proliferation. Our data therefore identify EMP2 mutations as causing a recessive Mendelian form of SSNS.
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Affiliation(s)
- Heon Yung Gee
- Division of Nephrology, Department of Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Shazia Ashraf
- Division of Nephrology, Department of Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Xiaoyang Wan
- Department of Pediatrics, University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Julian Esteve-Rudd
- Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Svjetlana Lovric
- Division of Nephrology, Department of Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Humphrey Fang
- Division of Nephrology, Department of Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Toby W Hurd
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Carolin E Sadowski
- Division of Nephrology, Department of Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Susan J Allen
- Department of Pediatrics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Edgar A Otto
- Department of Pediatrics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Emine Korkmaz
- Nephrogenetics Laboratory, Faculty of Medicine, Hacettepe University, Ankara 06100, Turkey
| | - Joseph Washburn
- Biomedical Research Core Facilities, University of Michigan, Ann Arbor, MI 48109, USA
| | - Shawn Levy
- HudsonAlpha Institute for Biotechnology, 601 Genome Way, Huntsville, AL 35806, USA
| | - David S Williams
- Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Sevcan A Bakkaloglu
- Department of Pediatric Nephrology, Faculty of Medicine, Gazi University, Ankara 06570, Turkey
| | | | - Fatih Ozaltin
- Nephrogenetics Laboratory, Faculty of Medicine, Hacettepe University, Ankara 06100, Turkey; Department of Pediatric Nephrology, Faculty of Medicine, Hacettepe University, Ankara 06100, Turkey; Center for Biobanking and Genomics, Hacettepe University, Ankara 06100, Turkey
| | - Weibin Zhou
- Department of Pediatrics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Friedhelm Hildebrandt
- Division of Nephrology, Department of Medicine, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
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He B, Ebarasi L, Zhao Z, Guo J, Ojala JRM, Hultenby K, De Val S, Betsholtz C, Tryggvason K. Lmx1b and FoxC combinatorially regulate podocin expression in podocytes. J Am Soc Nephrol 2014; 25:2764-77. [PMID: 24854274 DOI: 10.1681/asn.2012080823] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Podocin is a key protein of the kidney podocyte slit diaphragm protein complex, an important part of the glomerular filtration barrier. Mutations in the human podocin gene NPHS2 cause familial or sporadic forms of renal disease owing to the disruption of filtration barrier integrity. The exclusive expression of NPHS2 in podocytes reflects its unique function and raises interesting questions about its transcriptional regulation. Here, we further define a 2.5-kb zebrafish nphs2 promoter fragment previously described and identify a 49-bp podocyte-specific transcriptional enhancer using Tol2-mediated G0 transgenesis in zebrafish. Within this enhancer, we identified a cis-acting element composed of two adjacent DNA-binding sites (FLAT-E and forkhead) bound by transcription factors Lmx1b and FoxC. In zebrafish, double knockdown of Lmx1b and FoxC orthologs using morpholino doses that caused no or minimal phenotypic changes upon individual knockdown completely disrupted podocyte development in 40% of injected embryos. Co-overexpression of the two genes potently induced endogenous nphs2 expression in zebrafish podocytes. We found that the NPHS2 promoter also contains a cis-acting Lmx1b-FoxC motif that binds LMX1B and FoxC2. Furthermore, a genome-wide search identified several genes that carry the Lmx1b-FoxC motif in their promoter regions. Among these candidates, motif-driven podocyte enhancer activity of CCNC and MEIS2 was functionally analyzed in vivo. Our results show that podocyte expression of some genes is combinatorially regulated by two transcription factors interacting synergistically with a common enhancer. This finding provides insights into transcriptional mechanisms required for normal and pathologic podocyte functions.
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Affiliation(s)
- Bing He
- Department of Medical Biochemistry and Biophysics, Division of Matrix Biology, and
| | - Lwaki Ebarasi
- Department of Medical Biochemistry and Biophysics, Division of Vascular Biology, and Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Zhe Zhao
- Ludwig Institute for Cancer Research, Oxford University, Oxford, United Kingdom; and
| | - Jing Guo
- Department of Medical Biochemistry and Biophysics, Division of Matrix Biology, and
| | - Juha R M Ojala
- Department of Medical Biochemistry and Biophysics, Division of Matrix Biology, and
| | - Kjell Hultenby
- Department of Laboratory Medicine, Division of Clinical Research Centre, Karolinska Institute, Stockholm, Sweden
| | - Sarah De Val
- Ludwig Institute for Cancer Research, Oxford University, Oxford, United Kingdom; and
| | - Christer Betsholtz
- Department of Medical Biochemistry and Biophysics, Division of Vascular Biology, and Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden
| | - Karl Tryggvason
- Department of Medical Biochemistry and Biophysics, Division of Matrix Biology, and Cardiovascular & Metabolic Disorders Program, Duke-NUS, Singapore
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Miceli R, Kroeger P, Wingert R. Molecular Mechanisms of Podocyte Development Revealed by Zebrafish Kidney Research. ACTA ACUST UNITED AC 2014; 3. [PMID: 25485314 PMCID: PMC4254692 DOI: 10.4172/2168-9296.1000138] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Elucidating the gene regulatory networks that control kidney development can provide information about the origins of renal birth defects and kidney disease, as well as insights relevant to the design of clinical interventions for these conditions. The kidney is composed of functional units termed nephrons. Renal malfunction often arises from damage to cells known as podocytes, which are highly specialized epithelial cells that comprise the blood filter, or glomerulus, located on each nephron. Podocytes interact with the vasculature to create an elaborate sieve that collects circulatory fluid, and this filtrate enters the nephron where it is modified to produce urine and balance water homeostasis. Podocytes are an essential cellular component of the glomerular filtration barrier, helping to protect nephrons from the entry of large proteins and circulatory cells. Podocyte loss has catastrophic consequences for renal function and overall health, as podocyte destruction leads to nephron damage and pathological conditions like chronic kidney disease. Despite their importance, there is still a rather limited understanding about the molecular pathways that control podocyte formation. In recent years, however, studies of podocyte development using the zebrafish embryonic kidney, or pronephros, have been an expanding area of nephrology research. Zebrafish form an anatomically simple pronephros comprised of two nephrons that share a single blood filter, and podocyte progenitors can be easily visualized throughout the process of glomerular development. The zebrafish is an especially useful system for studying the mechanisms that are essential for formation of nephron cell types like podocytes due to the high genetic conservation between vertebrate species, including humans. In this review, we discuss how research using the zebrafish has provided new insights into the molecular regulation of the podocyte lineage during kidney ontogeny, complementing contemporary research in other animal models.
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Affiliation(s)
- R Miceli
- Department of Biological Sciences and Center for Zebrafish Research, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Pt Kroeger
- Department of Biological Sciences, University of Notre, Dame, 100 Galvin Life Sciences, Notre Dame, USA
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41
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Fukuyo Y, Nakamura T, Bubenshchikova E, Powell R, Tsuji T, Janknecht R, Obara T. Nephrin and Podocin functions are highly conserved between the zebrafish pronephros and mammalian metanephros. Mol Med Rep 2013; 9:457-65. [PMID: 24337247 PMCID: PMC3896505 DOI: 10.3892/mmr.2013.1844] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Accepted: 11/22/2013] [Indexed: 01/28/2023] Open
Abstract
The slit diaphragm (SD) is a highly specialized intercellular junction between podocyte foot processes and is crucial in the formation of the filtration barrier in the renal glomeruli. Zebrafish Nephrin and Podocin are important in the formation of the podocyte SD and mutations in NEPHRIN and PODOCIN genes cause human nephrotic syndrome. In the present study, the zebrafish Podocin protein was observed to be predominantly localized in the pronephric glomerular podocytes, as previously reported for Nephrin. To understand the function of Podocin and Nephrin in zebrafish, splice-blocking morpholino antisense oligonucleotides were used. Knockdown of Podocin or Nephrin by this method induced pronephric glomerular hypoplasia with pericardial edema. Human NEPHRIN and PODOCIN mRNA rescued this glomerular phenotype, however, the efficacy of the rescues was greatly reduced when mRNA-encoding human disease-causing NEPHRIN-R1109X and PODOCIN-R138Q were used. Furthermore, an association between zebrafish Nephrin and Podocin proteins was observed. Notably, Podocin-R150Q, corresponding to human PODOCIN-R138Q, markedly interacted with NEPHRIN compared with wild-type PODOCIN, suggesting that this strong binding capacity of mutated PODOCIN impairs the transport of NEPHRIN and PODOCIN out of the endoplasmic reticulum. The results suggest that the functions of Nephrin and Podocin are highly conserved between the zebrafish pronephros and mammalian metanephros. Accordingly, the zebrafish pronephros may provide a useful tool for analyzing disease-causing gene mutations in human kidney disorders.
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Affiliation(s)
- Yayoi Fukuyo
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Tomomi Nakamura
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Ekaterina Bubenshchikova
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Rebecca Powell
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Takashi Tsuji
- Department of Biological Science and Technology, Graduate School of Industrial Science and Technology, Tokyo University of Science, Noda, Chiba 278‑8510, Japan
| | - Ralf Janknecht
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Tomoko Obara
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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Endlich N, Simon O, Göpferich A, Wegner H, Moeller MJ, Rumpel E, Kotb AM, Endlich K. Two-photon microscopy reveals stationary podocytes in living zebrafish larvae. J Am Soc Nephrol 2013; 25:681-6. [PMID: 24309184 DOI: 10.1681/asn.2013020178] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Podocytes are an essential component of the glomerular filtration barrier and cover the outer aspect of glomerular capillaries. They form a complex actin-based cytoskeleton in vivo and show prominent motility in vitro, but whether podocytes are stationary or mobile in vivo is debated. To address this question, the pronephros of translucent zebrafish larvae (casper) expressing enhanced green fluorescent protein (eGFP) specifically in podocytes (wt1a:eGFP larvae) was observed by intravital two-photon microscopy over extended periods of time. Podocyte cell bodies and the interdigitating branching pattern of major processes could be resolved with a resolution of approximately 1 µm in the xy-plane. Time-lapse imaging of zebrafish larvae at 5-7 days after fertilization demonstrated that podocytes neither migrated nor changed the branching pattern of their major processes over a time period of up to 23 hours. In summary, we show by extended intravital two-photon microscopy that podocytes are stationary cells in the intact glomerulus of a translucent zebrafish with fluorescently-labeled podocytes.
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Affiliation(s)
- Nicole Endlich
- Department of Anatomy and Cell Biology, Universitätsmedizin Greifswald, Greifswald, Germany
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Mao J, Wang D, Mataleena P, He B, Niu D, Katayama K, Xu X, Ojala JRM, Wang W, Shu Q, Du L, Liu A, Pikkarainen T, Patrakka J, Tryggvason K. Myo1e impairment results in actin reorganization, podocyte dysfunction, and proteinuria in zebrafish and cultured podocytes. PLoS One 2013; 8:e72750. [PMID: 23977349 PMCID: PMC3747079 DOI: 10.1371/journal.pone.0072750] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 07/12/2013] [Indexed: 02/04/2023] Open
Abstract
Background Podocytes serve as an important constituent of the glomerular filtration barrier. Recently, we and others identified Myo1e as a key molecular component of the podocyte cytoskeleton. Results Myo1e mRNA and protein was expressed in human and mouse kidney sections as determined by Northern blot and reverse transcriptase PCR, and its expression was more evident in podocytes by immunofluorescence. By specific knock-down of MYO1E in zebrafish, the injected larvae exhibited pericardial edema and pronephric cysts, consistent with the appearance of protein in condensed incubation supernate. Furthermore, specific inhibition of Myo1e expression in a conditionally immortalized podocyte cell line induced morphological changes, actin cytoskeleton rearrangement, and dysfunction in cell proliferation, migration, endocytosis, and adhesion with the glomerular basement membrane. Conclusions Our results revealed that Myo1e is a key component contributing to the functional integrity of podocytes. Its impairment may cause actin cytoskeleton re-organization, alteration of cell shape, and membrane transport, and podocyte drop-out from the glomerular basement membrane, which might eventually lead to an impaired glomerular filtration barrier and proteinuria.
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Affiliation(s)
- Jianhua Mao
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of Medicine, Hangzhou, P. R. China
- * E-mail: (JM); (KT)
| | - Dayan Wang
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of Medicine, Hangzhou, P. R. China
| | - Parikka Mataleena
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Bing He
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Dadi Niu
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Kan Katayama
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Xiangjun Xu
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Juha RM Ojala
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Wenjing Wang
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of Medicine, Hangzhou, P. R. China
| | - Qiang Shu
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of Medicine, Hangzhou, P. R. China
| | - Lizhong Du
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of Medicine, Hangzhou, P. R. China
| | - Aimin Liu
- Department of Nephrology, The Children’s Hospital of Zhejiang University School of Medicine, Hangzhou, P. R. China
| | - Timo Pikkarainen
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Jaakko Patrakka
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Karl Tryggvason
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
- * E-mail: (JM); (KT)
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Huang J, McKee M, Huang HD, Xiang A, Davidson AJ, Lu HAJ. A zebrafish model of conditional targeted podocyte ablation and regeneration. Kidney Int 2013; 83:1193-200. [PMID: 23466998 PMCID: PMC3672345 DOI: 10.1038/ki.2013.6] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Podocytes are specialized cells that contribute critically to the normal structure and function of the glomerular filtration barrier. Their depletion plays an important role in the pathogenesis of glomerulosclerosis. Here, we report generation of a genetic model of conditional podocyte ablation and regeneration in zebrafish using a bacterial nitroreductase strategy to convert a prodrug, Metronidazole, into a cytotoxic metabolite. A transgenic zebrafish line was generated that expresses a green fluorescence protein (GFP) and the nitroreductase fusion protein under the control of the podocin promoter Tg(podocin:nitroreductase-GFP). Treatment of these transgenic zebrafish with Metronidazole results in podocyte apoptosis, a loss of nephrin and podocin expression, foot process effacement, and a leaky glomerular filtration barrier. Following Metronidazole washout, proliferating cells were detected in the glomeruli of recovering transgenic fish with a restoration of nitroreductase-GFP fluorescence, nephrin and podocin expression, a reestablishment of normal foot process architecture and glomerular barrier function. Thus, our studies show that zebrafish podocytes are capable of regenerating following depletion and establish the Tg(podocin:NTR-GFP) fish as a new model to study podocyte injury and repair.
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Affiliation(s)
- Jianmin Huang
- Center for Systems Biology, Program in Membrane Biology, Division of Nephrology, Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA
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45
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Ichimura K, Fukuyo Y, Nakamura T, Powell R, Sakai T, Janknecht R, Obara T. Developmental localization of nephrin in zebrafish and medaka pronephric glomerulus. J Histochem Cytochem 2013; 61:313-24. [PMID: 23324868 DOI: 10.1369/0022155413477115] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Slit diaphragm (SD) is a highly specialized intercellular junction between podocyte foot processes and plays a crucial role in the formation of the filtration barrier. In this study, we examined the developmental localization of Nephrin, an essential component of SD, in the pronephric glomerulus of zebrafish and medaka. In the mature glomerulus of both fish, Nephrin is localized along the glomerular basement membrane as seen in mammals, indicating that Nephrin is localized at the SD. Interestingly, Nephrin was detected already in immature podocytes before the SD and foot processes started to form in both fish. Nephrin was localized along the cell surface of immature podocytes but as different localization patterns. In zebrafish, Nephrin signal bordered the lateral membrane of podocytes, which were columnar in shape, as in rat immature podocytes. However, in medaka immature podocytes, Nephrin was localized in a punctate pattern among podocyte cell bodies. These findings suggest that Nephrin needs to be integrated to the membrane before the formation of the SD and then moves to the proper site to form the SD. Furthermore, a podocyte-specific marker, such as Nephrin, should be a useful tool for the future analysis of pronephric glomerular development in fish mutants and morphants.
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Affiliation(s)
- Koichiro Ichimura
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
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46
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Ichimura K, Fukuyo Y, Nakamura T, Powell R, Sakai T, Obara T. Structural disorganization of pronephric glomerulus in zebrafish mpp5a/nagie oko mutant. Dev Dyn 2012; 241:1922-32. [PMID: 23027442 DOI: 10.1002/dvdy.23877] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2012] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND The podocyte slit diaphragm (SD) is an essential component of the selective filtration barrier in the glomerulus. Several structural proteins required for formation and maintenance of SD have been identified; however, molecular mechanisms regulating these proteins are still limited. RESULTS Here, we demonstrate that MAGUK p55 subfamily member 5a (Mpp5a)/Nagie oko, a component of the Crb multi-protein complex, was colocalized with an SD-associated protein ZO-1 in the zebrafish pronephric glomerulus. To characterize the function of Mpp5a, zebrafish mpp5a(m520) mutant embryos, which are known to have defects in cardiac and neuronal morphogenesis, were analyzed. These mutants failed to merge the bilateral glomerular primordia and to form the glomerular capillary and mesangium, but the foot processes and SD showed normal appearance. The structural disorganization in the mpp5a(m520) mutant glomerulus was quite similar to that of a cardiac troponin T2a/tnnt2a/silent heart knockdown zebrafish, which exhibited circulatory failure due to lack of heart beating. CONCLUSIONS Mpp5a is not prerequisite to form podocyte slit diaphragm in the pronephric glomerular development in zebrafish. The structural disorganization of the pronephric glomerulus in the mpp5a(m520) mutant is likely to result from circulatory failure, rather than the anomaly of Mpp5a protein in the glomerulus.
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Affiliation(s)
- Koichiro Ichimura
- Department of Cell Biology, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma 73104, USA
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47
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Gerlach GF, Wingert RA. Kidney organogenesis in the zebrafish: insights into vertebrate nephrogenesis and regeneration. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2012; 2:559-85. [PMID: 24014448 DOI: 10.1002/wdev.92] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Vertebrates form a progressive series of up to three kidney organs during development-the pronephros, mesonephros, and metanephros. Each kidney derives from the intermediate mesoderm and is comprised of conserved excretory units called nephrons. The zebrafish is a powerful model for vertebrate developmental genetics, and recent studies have illustrated that zebrafish and mammals share numerous similarities in nephron composition and physiology. The zebrafish embryo forms an architecturally simple pronephros that has two nephrons, and these eventually become a scaffold onto which a mesonephros of several hundred nephrons is constructed during larval stages. In adult zebrafish, the mesonephros exhibits ongoing nephrogenesis, generating new nephrons from a local pool of renal progenitors during periods of growth or following kidney injury. The characteristics of the zebrafish pronephros and mesonephros make them genetically tractable kidney systems in which to study the functions of renal genes and address outstanding questions about the mechanisms of nephrogenesis. Here, we provide an overview of the formation and composition of these zebrafish kidney organs, and discuss how various zebrafish mutants, gene knockdowns, and transgenic models have created frameworks in which to further delineate nephrogenesis pathways.
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Affiliation(s)
- Gary F Gerlach
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
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48
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Müller RU, Benzing T. A photo shoot of proteinuria: zebrafish models of inducible podocyte damage. J Am Soc Nephrol 2012; 23:969-71. [PMID: 22581995 DOI: 10.1681/asn.2012040395] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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49
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Hartleben B, Widmeier E, Wanner N, Schmidts M, Kim ST, Schneider L, Mayer B, Kerjaschki D, Miner JH, Walz G, Huber TB. Role of the polarity protein Scribble for podocyte differentiation and maintenance. PLoS One 2012; 7:e36705. [PMID: 22586490 PMCID: PMC3346764 DOI: 10.1371/journal.pone.0036705] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 04/05/2012] [Indexed: 11/19/2022] Open
Abstract
The kidney filter represents a unique assembly of podocyte epithelial cells that tightly enwrap the glomerular capillaries with their complex foot process network. While deficiency of the polarity proteins Crumbs and aPKC result in impaired podocyte foot process architecture, the function of basolateral polarity proteins for podocyte differentiation and maintenance remained unclear. Here we report, that Scribble is expressed in developing podocytes, where it translocates from the lateral aspects of immature podocytes to the basal cell membrane and foot processes of mature podocytes. Immunogold electron microscopy reveals membrane associated localisation of Scribble predominantly at the basolateral site of foot processes. To further study the role of Scribble for podocyte differentiation Scribble(flox/flox) mice were generated by introducing loxP-sites into the Scribble introns 1 and 8 and these mice were crossed to NPHS2.Cre mice and Cre deleter mice. Podocyte-specific Scribble knockout mice develop normally and display no histological, ultrastructural or clinical abnormalities up to 12 months of age. In addition, no increased susceptibility to glomerular stress could be detected in these mice. In contrast, constitutive Scribble knockout animals die during embryonic development indicating the fundamental importance of Scribble for embryogenesis. Like in podocyte-specific Scribble knockout mice, the development of podocyte foot processes and the slit diaphragm was unaffected in kidney cultures from constitutive Scribble knockout animals. In summary these results indicate that basolateral polarity signaling via Scribble is dispensable for podocyte function, highlighting the unique feature of podocyte development with its significant apical membrane expansions being dominated by apical polarity complexes rather than by basolateral polarity signaling.
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Affiliation(s)
- Björn Hartleben
- Renal Division, University Hospital Freiburg, Freiburg, Germany
| | - Eugen Widmeier
- Renal Division, University Hospital Freiburg, Freiburg, Germany
| | - Nicola Wanner
- Renal Division, University Hospital Freiburg, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Miriam Schmidts
- Renal Division, University Hospital Freiburg, Freiburg, Germany
| | - Sung Tae Kim
- Renal Division, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Lisa Schneider
- Renal Division, University Hospital Freiburg, Freiburg, Germany
| | - Britta Mayer
- Renal Division, University Hospital Freiburg, Freiburg, Germany
| | - Dontscho Kerjaschki
- Clinical Institute of Pathology, Medical University of Vienna, Vienna, Austria
| | - Jeffrey H. Miner
- Renal Division, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Gerd Walz
- Renal Division, University Hospital Freiburg, Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Tobias B. Huber
- Renal Division, University Hospital Freiburg, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, Albert-Ludwigs-University Freiburg, Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Freiburg, Germany
- * E-mail:
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50
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Zhou W, Hildebrandt F. Inducible podocyte injury and proteinuria in transgenic zebrafish. J Am Soc Nephrol 2012. [PMID: 22440901 DOI: 10.1691/asn.2011080776] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Damage or loss of podocytes causes glomerulosclerosis in murine models, and mutations in podocyte-specific genes cause nephrotic syndrome in humans. Zebrafish provide a valuable model for kidney research, but disruption of pronephroi leads to death within a few days, thereby preventing the study of CKD. In this study, we generated an inducible model of podocyte injury in zebrafish (pod::NTR-mCherry) by expressing a bacterial nitroreductase, which converts metronidazole to a cytotoxin, specifically in podocytes under the control of the zebrafish nphs2/podocin promoter. Application of the prodrug metronidazole to the transgenic fish induces acute damage to the podocytes in pronephroi of larval zebrafish and the mesonephroi of adult zebrafish, resulting in foot-process effacement and podocyte loss. We also developed a functional assay of the glomerular filtration barrier by creating transgenic zebrafish expressing green fluorescent protein (GFP)-tagged vitamin D-binding protein (VDBP) as a tracer for proteinuria. In the VDBP-GFP and pod::NTR-mCherry double-transgenic fish, induction of podocyte damage led to whole-body edema, and the proximal tubules reabsorbed and accumulated VDBP-GFP that leaked through the glomeruli, mimicking the phenotype of human nephrotic syndrome. Moreover, expression of wt1b::GFP, a marker for the developing nephron, extended into the Bowman capsule in response to podocyte injury, suggesting that zebrafish have a podocyte-specific repair process known to occur in mammalian metanephros. These data support the use of these transgenic zebrafish as a model system for studies of glomerular pathogenesis and podocyte regeneration.
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Affiliation(s)
- Weibin Zhou
- University of Michigan Medical School, 8240 MSRB III, 1150 West Medical Center Drive, Ann Arbor, MI 48109-5646, USA.
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