1
|
Salfi G, Casiraghi F, Remuzzi G. Current understanding of the molecular mechanisms of circulating permeability factor in focal segmental glomerulosclerosis. Front Immunol 2023; 14:1247606. [PMID: 37795085 PMCID: PMC10546017 DOI: 10.3389/fimmu.2023.1247606] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 09/05/2023] [Indexed: 10/06/2023] Open
Abstract
The pathogenetic mechanisms underlying the onset and the post-transplant recurrence of primary focal segmental glomerulosclerosis (FSGS) are complex and remain yet to be fully elucidated. However, a growing body of evidence emphasizes the pivotal role of the immune system in both initiating and perpetuating the disease. Extensive investigations, encompassing both experimental models and patient studies, have implicated T cells, B cells, and complement as crucial actors in the pathogenesis of primary FSGS, with various molecules being proposed as potential "circulating factors" contributing to the disease and its recurrence post kidney-transplantation. In this review, we critically assessed the existing literature to identify essential pathways for a comprehensive characterization of the pathogenesis of FSGS. Recent discoveries have shed further light on the intricate interplay between these mechanisms. We present an overview of the current understanding of the engagement of distinct molecules and immune cells in FSGS pathogenesis while highlighting critical knowledge gaps that require attention. A thorough characterization of these intricate immune mechanisms holds the potential to identify noninvasive biomarkers that can accurately identify patients at high risk of post-transplant recurrence. Such knowledge can pave the way for the development of targeted and personalized therapeutic approaches in the management of FSGS.
Collapse
Affiliation(s)
| | - Federica Casiraghi
- Istituto di Ricerche Farmacologiche Mario Negri Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Bergamo, Italy
| | | |
Collapse
|
2
|
Zárybnický T, Heikkinen A, Kangas SM, Karikoski M, Martínez-Nieto GA, Salo MH, Uusimaa J, Vuolteenaho R, Hinttala R, Sipilä P, Kuure S. Modeling Rare Human Disorders in Mice: The Finnish Disease Heritage. Cells 2021; 10:cells10113158. [PMID: 34831381 PMCID: PMC8621025 DOI: 10.3390/cells10113158] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 11/04/2021] [Accepted: 11/06/2021] [Indexed: 12/31/2022] Open
Abstract
The modification of genes in animal models has evidently and comprehensively improved our knowledge on proteins and signaling pathways in human physiology and pathology. In this review, we discuss almost 40 monogenic rare diseases that are enriched in the Finnish population and defined as the Finnish disease heritage (FDH). We will highlight how gene-modified mouse models have greatly facilitated the understanding of the pathological manifestations of these diseases and how some of the diseases still lack proper models. We urge the establishment of subsequent international consortiums to cooperatively plan and carry out future human disease modeling strategies. Detailed information on disease mechanisms brings along broader understanding of the molecular pathways they act along both parallel and transverse to the proteins affected in rare diseases, therefore also aiding understanding of common disease pathologies.
Collapse
Affiliation(s)
- Tomáš Zárybnický
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, P.O. Box 63, 00014 Helsinki, Finland;
| | - Anne Heikkinen
- Biocenter Oulu, University of Oulu, P.O. Box 5000, 90014 Oulu, Finland; (A.H.); (S.M.K.); (M.H.S.); (R.V.)
- Oulu Center for Cell-Matrix Research, Faculty of Biochemistry and Molecular Medicine, University of Oulu, P.O. Box 8000, 90014 Oulu, Finland
| | - Salla M. Kangas
- Biocenter Oulu, University of Oulu, P.O. Box 5000, 90014 Oulu, Finland; (A.H.); (S.M.K.); (M.H.S.); (R.V.)
- PEDEGO Research Unit, University of Oulu, P.O. Box 8000, 90014 Oulu, Finland;
- Medical Research Center, Oulu University Hospital, University of Oulu, P.O. Box 5000, 90014 Oulu, Finland
| | - Marika Karikoski
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, 20520 Turku, Finland; (M.K.); (G.A.M.-N.)
| | - Guillermo Antonio Martínez-Nieto
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, 20520 Turku, Finland; (M.K.); (G.A.M.-N.)
- Turku Center for Disease Modelling (TCDM), Institute of Biomedicine, University of Turku, 20520 Turku, Finland
| | - Miia H. Salo
- Biocenter Oulu, University of Oulu, P.O. Box 5000, 90014 Oulu, Finland; (A.H.); (S.M.K.); (M.H.S.); (R.V.)
- PEDEGO Research Unit, University of Oulu, P.O. Box 8000, 90014 Oulu, Finland;
- Medical Research Center, Oulu University Hospital, University of Oulu, P.O. Box 5000, 90014 Oulu, Finland
| | - Johanna Uusimaa
- PEDEGO Research Unit, University of Oulu, P.O. Box 8000, 90014 Oulu, Finland;
- Medical Research Center, Oulu University Hospital, University of Oulu, P.O. Box 5000, 90014 Oulu, Finland
- Clinic for Children and Adolescents, Division of Pediatric Neurology, Oulu University Hospital, P.O. Box 20, 90029 Oulu, Finland
| | - Reetta Vuolteenaho
- Biocenter Oulu, University of Oulu, P.O. Box 5000, 90014 Oulu, Finland; (A.H.); (S.M.K.); (M.H.S.); (R.V.)
| | - Reetta Hinttala
- Biocenter Oulu, University of Oulu, P.O. Box 5000, 90014 Oulu, Finland; (A.H.); (S.M.K.); (M.H.S.); (R.V.)
- PEDEGO Research Unit, University of Oulu, P.O. Box 8000, 90014 Oulu, Finland;
- Medical Research Center, Oulu University Hospital, University of Oulu, P.O. Box 5000, 90014 Oulu, Finland
- Correspondence: (R.H.); (P.S.); (S.K.)
| | - Petra Sipilä
- Research Centre for Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, 20520 Turku, Finland; (M.K.); (G.A.M.-N.)
- Turku Center for Disease Modelling (TCDM), Institute of Biomedicine, University of Turku, 20520 Turku, Finland
- Correspondence: (R.H.); (P.S.); (S.K.)
| | - Satu Kuure
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, P.O. Box 63, 00014 Helsinki, Finland;
- GM-Unit, Laboratory Animal Center, Helsinki Institute of Life Science, University of Helsinki, 00790 Helsinki, Finland
- Correspondence: (R.H.); (P.S.); (S.K.)
| |
Collapse
|
3
|
Afsar B, Afsar RE, Demiray A, Covic A, Kanbay M. Deciphering nutritional interventions for podocyte structure and function. Pharmacol Res 2021; 172:105852. [PMID: 34450318 DOI: 10.1016/j.phrs.2021.105852] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 08/22/2021] [Accepted: 08/22/2021] [Indexed: 12/11/2022]
Abstract
Despite increasing awareness and therapeutic options chronic kidney disease (CKD) is still and important health problem and glomerular diseases constitute and important percentage of CKD. Proteinuria/albuminuria is not just a marker; but it also plays a direct pathogenic role in renal disease progression of CKD. Glomerular filtration barrier (GFB) which consists of fenestrated endothelial cells, fused basal membrane and interdigitating podocyte foot process and filtration slits between foot process is the major barrier for proteinuria/albuminuria. Many glomerular diseases are characterized by disruption of GFB podocytes, foot process and slit diaphragm. Many proteinuric diseases are non-specifically targeted by therapeutic agents such as steroids and calcineurin inhibitors with systemic side effects. Thus, there is unmet need for more efficient and less toxic therapeutic options to treat glomerular diseases. In recent years, modification of dietary intake, has been gained to treat pathologic processes introducing the concept of 'food as a medicine'. The effect of various nutritional products on podocyte function and structure is also trending, especially in recent years. In the current review, we summarized the effect of nutritional interventions on podocyte function and structure.
Collapse
Affiliation(s)
- Baris Afsar
- Division of Nephrology, Department of Nephrology, Suleyman Demirel University School of Medicine, Isparta, Turkey.
| | - Rengin Elsurer Afsar
- Division of Nephrology, Department of Nephrology, Suleyman Demirel University School of Medicine, Isparta, Turkey
| | - Atalay Demiray
- Department of Medicine, Koc University School of Medicine, Istanbul, Turkey
| | - Adrian Covic
- Department of Nephrology, Grigore T. Popa' University of Medicine, Iasi, Romania
| | - Mehmet Kanbay
- Division of Nephrology, Department of Medicine, Koc University School of Medicine, Istanbul, Turkey
| |
Collapse
|
4
|
Solanki AK, Arif E, Srivastava P, Furcht CM, Rahman B, Wen P, Singh A, Holzman LB, Fitzgibbon WR, Budisavljevic MN, Lobo GP, Kwon SH, Han Z, Lazzara MJ, Lipschutz JH, Nihalani D. Phosphorylation of slit diaphragm proteins NEPHRIN and NEPH1 upon binding of HGF promotes podocyte repair. J Biol Chem 2021; 297:101079. [PMID: 34391780 PMCID: PMC8429977 DOI: 10.1016/j.jbc.2021.101079] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 08/02/2021] [Accepted: 08/11/2021] [Indexed: 12/22/2022] Open
Abstract
Phosphorylation (activation) and dephosphorylation (deactivation) of the slit diaphragm proteins NEPHRIN and NEPH1 are critical for maintaining the kidney epithelial podocyte actin cytoskeleton and, therefore, proper glomerular filtration. However, the mechanisms underlying these events remain largely unknown. Here we show that NEPHRIN and NEPH1 are novel receptor proteins for hepatocyte growth factor (HGF) and can be phosphorylated independently of the mesenchymal epithelial transition receptor in a ligand-dependent fashion through engagement of their extracellular domains by HGF. Furthermore, we demonstrate SH2 domain–containing protein tyrosine phosphatase-2–dependent dephosphorylation of these proteins. To establish HGF as a ligand, purified baculovirus-expressed NEPHRIN and NEPH1 recombinant proteins were used in surface plasma resonance binding experiments. We report high-affinity interactions of NEPHRIN and NEPH1 with HGF, although NEPHRIN binding was 20-fold higher than that of NEPH1. In addition, using molecular modeling we constructed peptides that were used to map specific HGF-binding regions in the extracellular domains of NEPHRIN and NEPH1. Finally, using an in vitro model of cultured podocytes and an ex vivo model of Drosophila nephrocytes, as well as chemically induced injury models, we demonstrated that HGF-induced phosphorylation of NEPHRIN and NEPH1 is centrally involved in podocyte repair. Taken together, this is the first study demonstrating a receptor-based function for NEPHRIN and NEPH1. This has important biological and clinical implications for the repair of injured podocytes and the maintenance of podocyte integrity.
Collapse
Affiliation(s)
- Ashish K Solanki
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Ehtesham Arif
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Pankaj Srivastava
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Christopher M Furcht
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Bushra Rahman
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Pei Wen
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Avinash Singh
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Lawrence B Holzman
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Wayne R Fitzgibbon
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Milos N Budisavljevic
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Glenn P Lobo
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Sang-Ho Kwon
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, Georgia, USA
| | - Zhe Han
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Matthew J Lazzara
- Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia, USA
| | - Joshua H Lipschutz
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA; Department of Medicine, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina, USA.
| | - Deepak Nihalani
- Division of Kidney, Urologic and Hematologic Diseases, National Institutes of Health, Bethesda, Maryland, USA
| |
Collapse
|
5
|
Laorodphun P, Arjinajarn P, Thongnak L, Promsan S, Swe MT, Thitisut P, Mahatheeranont S, Jaturasitha S, Lungkaphin A. Anthocyanin-rich fraction from black rice, Oryza sativa L. var. indica "Luem Pua," bran extract attenuates kidney injury induced by high-fat diet involving oxidative stress and apoptosis in obese rats. Phytother Res 2021; 35:5189-5202. [PMID: 34327741 DOI: 10.1002/ptr.7188] [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: 11/10/2020] [Revised: 04/22/2021] [Accepted: 05/06/2021] [Indexed: 12/12/2022]
Abstract
Obesity is acknowledged as being a world health problem and increases the risk of several chronic diseases including chronic kidney disease. High-fat diet consumption and obesity-related renal disease show a close correlation with increased oxidative stress. Black rice bran extract, (BRE) Oryza sativa L. variety "Luem Pua" contains a high anthocyanin content. This study evaluated the effects of an anthocyanin-rich fraction from BRE on renal function and oxidative stress in obese rats. Male Wistar rats were fed a normal diet (ND) or high-fat diet (HF) for 16 weeks. After this, the rats were given either vehicle (HF), BRE 100 (HF100) or BRE 200 mg/kg/day (HF200) orally for 8 weeks. The HF rats had increased body weight, visceral fat weight, plasma glucose, cholesterol and triglycerides. These parameters were normalized following HF100 administration and showed a decreasing trend with HF200. Serum creatinine and renal cortical MDA were increased in the HF group but these effects were attenuated by BRE. Negative kidney injury and histopathology changes were observed following a HF, but treatment with BRE reversed these deleterious effects. These results suggest that BRE could be used as a food supplement to improve metabolic disturbance and prevent kidney dysfunction in cases of obesity.
Collapse
Affiliation(s)
- Pongrapee Laorodphun
- Graduate Master's Degree Program in Biology, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand
| | - Phatchawan Arjinajarn
- Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand
| | - Laongdao Thongnak
- Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Sasivimon Promsan
- Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Myat Theingi Swe
- Department of Physiology, University of Medicine 2, Yangon, Myanmar
| | - Pasin Thitisut
- Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand
| | - Sugunya Mahatheeranont
- Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand.,Center of Excellence for Innovation in Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand
| | - Sanchai Jaturasitha
- Science and Technology Research Institute, Chiang Mai University, Chiang Mai, Thailand
| | - Anusorn Lungkaphin
- Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Functional Food Research Center for Well-Being, Chiang Mai University, Chiang Mai, Thailand
| |
Collapse
|
6
|
Bhargava R, Lehoux S, Maeda K, Tsokos MG, Krishfield S, Ellezian L, Pollak M, Stillman IE, Cummings RD, Tsokos GC. Aberrantly glycosylated IgG elicits pathogenic signaling in podocytes and signifies lupus nephritis. JCI Insight 2021; 6:147789. [PMID: 33784256 PMCID: PMC8262331 DOI: 10.1172/jci.insight.147789] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 03/25/2021] [Indexed: 12/27/2022] Open
Abstract
Lupus nephritis (LN) is a serious complication occurring in 50% of patients with systemic lupus erythematosus (SLE) for which there is a lack of biomarkers, a lack of specific medications, and a lack of a clear understanding of its pathogenesis. The expression of calcium/calmodulin kinase IV (CaMK4) is increased in podocytes of patients with LN and lupus-prone mice, and its podocyte-targeted inhibition averts the development of nephritis in mice. Nephrin is a key podocyte molecule essential for the maintenance of the glomerular slit diaphragm. Here, we show that the presence of fucose on N-glycans of IgG induces, whereas the presence of galactose ameliorates, podocyte injury through CaMK4 expression. Mechanistically, CaMK4 phosphorylates NF-κB, upregulates the transcriptional repressor SNAIL, and limits the expression of nephrin. In addition, we demonstrate that increased expression of CaMK4 in biopsy specimens and in urine podocytes from people with LN is linked to active kidney disease. Our data shed light on the role of IgG glycosylation in the development of podocyte injury and propose the development of “liquid kidney biopsy” approaches to diagnose LN.
Collapse
Affiliation(s)
| | - Sylvain Lehoux
- Department of Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA.,Beth Israel Deaconess Medical Center Glycomics Core, Boston, Massachusetts, USA
| | | | | | | | | | | | - Isaac E Stillman
- Department of Pathology, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Richard D Cummings
- Department of Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA.,Beth Israel Deaconess Medical Center Glycomics Core, Boston, Massachusetts, USA
| | | |
Collapse
|
7
|
Dhandapani MC, Venkatesan V, Pricilla C. MicroRNAs in childhood nephrotic syndrome. J Cell Physiol 2021; 236:7186-7210. [PMID: 33819345 DOI: 10.1002/jcp.30374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 02/16/2021] [Accepted: 03/12/2021] [Indexed: 11/11/2022]
Abstract
The discovery of microRNAs (miRNAs) has opened up new avenues of research to understand the molecular basis of a number of diseases. Because of their conservative feature in evolution and important role in the physiological function, microRNAs could be treated as predictors for disease classification and clinical process based on the specific expression. The identification of novel miRNAs and their target genes can be considered as potential targets for novel drugs. Furthermore, currently, the circulatory and urinary exosomal miRNAs are gaining increasing attention as their expression profiles are often associated with specific diseases, and they exhibit great potential as noninvasive or minimally invasive biomarkers for the diagnosis of various diseases. The remarkable stability of these extracellular miRNAs circulating in the blood or excreted in the urine underscored their key importance as biomarkers of certain diseases. There is voluminous literature concerning the role of microRNAs in other diseases, such as cardiovascular diseases, diabetic nephropathy, and so forth. However, little is known about their diagnostic ability for the pediatric nephrotic syndrome (NS). The present review article highlights the recent advances in the role of miRNAs in the pathogenesis and molecular basis of NS with an aim to bring new insights into further research applications for the development of new therapeutic agents for NS.
Collapse
Affiliation(s)
- Mohanapriya C Dhandapani
- Department of Central Research Facility, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
| | - Vettriselvi Venkatesan
- Department of Human Genetics, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
| | - Charmine Pricilla
- Department of Central Research Facility, Sri Ramachandra Institute of Higher Education and Research, Chennai, India
| |
Collapse
|
8
|
Yoshida S, Wei X, Zhang G, O'Connor CL, Torres M, Zhou Z, Lin L, Menon R, Xu X, Zheng W, Xiong Y, Otto E, Tang CHA, Hua R, Verma R, Mori H, Zhang Y, Hu CCA, Liu M, Garg P, Hodgin JB, Sun S, Bitzer M, Qi L. Endoplasmic reticulum-associated degradation is required for nephrin maturation and kidney glomerular filtration function. J Clin Invest 2021; 131:143988. [PMID: 33591954 DOI: 10.1172/jci143988] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 02/11/2021] [Indexed: 02/06/2023] Open
Abstract
Podocytes are key to the glomerular filtration barrier by forming a slit diaphragm between interdigitating foot processes; however, the molecular details and functional importance of protein folding and degradation in the ER remain unknown. Here, we show that the SEL1L-HRD1 protein complex of ER-associated degradation (ERAD) is required for slit diaphragm formation and glomerular filtration function. SEL1L-HRD1 ERAD is highly expressed in podocytes of both mouse and human kidneys. Mice with podocyte-specific Sel1L deficiency develop podocytopathy and severe congenital nephrotic syndrome with an impaired slit diaphragm shortly after weaning and die prematurely, with a median lifespan of approximately 3 months. We show mechanistically that nephrin, a type 1 membrane protein causally linked to congenital nephrotic syndrome, is an endogenous ERAD substrate. ERAD deficiency attenuated the maturation of nascent nephrin, leading to its retention in the ER. We also show that various autosomal-recessive nephrin disease mutants were highly unstable and broken down by SEL1L-HRD1 ERAD, which attenuated the pathogenicity of the mutants toward the WT allele. This study uncovers a critical role of SEL1L-HRD1 ERAD in glomerular filtration barrier function and provides insights into the pathogenesis associated with autosomal-recessive disease mutants.
Collapse
Affiliation(s)
- Sei Yoshida
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA.,State Key Laboratory of Medical Chemical Biology, College of Life Sciences, Frontiers Science Center for Cell Responses, Nankai University, Tianjin, China
| | - Xiaoqiong Wei
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Gensheng Zhang
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Christopher L O'Connor
- Division of Nephrology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Mauricio Torres
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Zhangsen Zhou
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Liangguang Lin
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Rajasree Menon
- Division of Nephrology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Xiaoxi Xu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Wenyue Zheng
- State Key Laboratory of Medical Chemical Biology, College of Life Sciences, Frontiers Science Center for Cell Responses, Nankai University, Tianjin, China
| | - Yi Xiong
- Center for Molecular Medicine and Genetics, Department of Biochemistry, Microbiology and Immunology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Edgar Otto
- Division of Nephrology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Chih-Hang Anthony Tang
- Houston Methodist Cancer Center, Houston Methodist Academic Institute, Houston, Texas, USA
| | - Rui Hua
- State Key Laboratory of Medical Chemical Biology, College of Life Sciences, Frontiers Science Center for Cell Responses, Nankai University, Tianjin, China
| | - Rakesh Verma
- Division of Nephrology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Hiroyuki Mori
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Yang Zhang
- Department of Computational Medicine and Bioinformatics and Department of Biological Chemistry and
| | - Chih-Chi Andrew Hu
- Houston Methodist Cancer Center, Houston Methodist Academic Institute, Houston, Texas, USA
| | - Ming Liu
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China
| | - Puneet Garg
- Division of Nephrology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | | | - Shengyi Sun
- Center for Molecular Medicine and Genetics, Department of Biochemistry, Microbiology and Immunology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Markus Bitzer
- Division of Nephrology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Ling Qi
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA.,Division of Metabolism, Endocrinology & Diabetes, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
| |
Collapse
|
9
|
Dlugos CP, Picciotto C, Lepa C, Krakow M, Stöber A, Eddy ML, Weide T, Jeibmann A, P Krahn M, Van Marck V, Klingauf J, Ricker A, Wedlich-Söldner R, Pavenstädt H, Klämbt C, George B. Nephrin Signaling Results in Integrin β1 Activation. J Am Soc Nephrol 2019; 30:1006-1019. [PMID: 31097607 DOI: 10.1681/asn.2018040362] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Accepted: 03/18/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Patients with certain mutations in the gene encoding the slit diaphragm protein Nephrin fail to develop functional slit diaphragms and display severe proteinuria. Many adult-onset glomerulopathies also feature alterations in Nephrin expression and function. Nephrin signals from the podocyte slit diaphragm to the Actin cytoskeleton by recruiting proteins that can interact with C3G, a guanine nucleotide exchange factor of the small GTPase Rap1. Because Rap activity affects formation of focal adhesions, we hypothesized that Nephrin transmits signals to the Integrin receptor complex, which mediates podocyte adhesion to the extracellular matrix. METHODS To investigate Nephrin's role in transmitting signals to the Integrin receptor complex, we conducted genetic studies in Drosophila nephrocytes and validated findings from Drosophila in a cultured human podocyte model. RESULTS Drosophila nephrocytes form a slit diaphragm-like filtration barrier and express the Nephrin ortholog Sticks and stones (Sns). A genetic screen identified c3g as necessary for nephrocyte function. In vivo, nephrocyte-specific gene silencing of sns or c3g compromised nephrocyte filtration and caused nephrocyte diaphragm defects. Nephrocytes with impaired Sns or C3G expression displayed an altered localization of Integrin and the Integrin-associated protein Talin. Furthermore, gene silencing of c3g partly rescued nephrocyte diaphragm defects of an sns overexpression phenotype, pointing to genetic interaction of sns and c3g in nephrocytes. We also found that activated Nephrin recruited phosphorylated C3G and resulted in activation of Integrin β1 in cultured podocytes. CONCLUSIONS Our findings suggest that Nephrin can mediate a signaling pathway that results in activation of Integrin β1 at focal adhesions, which may affect podocyte attachment to the extracellular matrix.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | - Christian Klämbt
- Neurobiology, Westfälische-Wilhelms University Münster, Münster, Germany
| | | |
Collapse
|
10
|
Yu SMW, Nissaisorakarn P, Husain I, Jim B. Proteinuric Kidney Diseases: A Podocyte's Slit Diaphragm and Cytoskeleton Approach. Front Med (Lausanne) 2018; 5:221. [PMID: 30255020 PMCID: PMC6141722 DOI: 10.3389/fmed.2018.00221] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/18/2018] [Indexed: 01/19/2023] Open
Abstract
Proteinuric kidney diseases are a group of disorders with diverse pathological mechanisms associated with significant losses of protein in the urine. The glomerular filtration barrier (GFB), comprised of the three important layers, the fenestrated glomerular endothelium, the glomerular basement membrane (GBM), and the podocyte, dictates that disruption of any one of these structures should lead to proteinuric disease. Podocytes, in particular, have long been considered as the final gatekeeper of the GFB. This specialized visceral epithelial cell contains a complex framework of cytoskeletons forming foot processes and mediate important cell signaling to maintain podocyte health. In this review, we will focus on slit diaphragm proteins such as nephrin, podocin, TRPC6/5, as well as cytoskeletal proteins Rho/small GTPases and synaptopodin and their respective roles in participating in the pathogenesis of proteinuric kidney diseases. Furthermore, we will summarize the potential therapeutic options targeting the podocyte to treat this group of kidney diseases.
Collapse
Affiliation(s)
- Samuel Mon-Wei Yu
- Department of Medicine, Jacobi Medical Center, Bronx, NY, United States
| | | | - Irma Husain
- Department of Medicine, James J. Peters VA Medical Center, Bronx, NY, United States
| | - Belinda Jim
- Department of Medicine, Jacobi Medical Center, Bronx, NY, United States.,Renal Division, Jacobi Medical Center, Bronx, NY, United States
| |
Collapse
|
11
|
Empitu MA, Kadariswantiningsih IN, Aizawa M, Asanuma K. MAGI-2 and scaffold proteins in glomerulopathy. Am J Physiol Renal Physiol 2018; 315:F1336-F1344. [PMID: 30110567 DOI: 10.1152/ajprenal.00292.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
In many cells and tissues, including the glomerular filtration barrier, scaffold proteins are critical in optimizing signal transduction by enhancing structural stability and functionality of their ligands. Recently, mutations in scaffold protein membrane-associated guanylate kinase inverted 2 (MAGI-2) encoding gene were identified among the etiology of steroid-resistant nephrotic syndrome. MAGI-2 interacts with core proteins of multiple pathways, such as transforming growth factor-β signaling, planar cell polarity pathway, and Wnt/β-catenin signaling in podocyte and slit diaphragm. Through the interaction with its ligand, MAGI-2 modulates the regulation of apoptosis, cytoskeletal reorganization, and glomerular development. This review aims to summarize recent findings on the role of MAGI-2 and some other scaffold proteins, such as nephrin and synaptopodin, in the underlying mechanisms of glomerulopathy.
Collapse
Affiliation(s)
- Maulana A Empitu
- Department of Nephrology, Graduate School of Medicine, Chiba University , Chiba , Japan.,Department of Pharmacology and Therapeutics, Faculty of Medicine, Universitas Airlangga , Surabaya , Indonesia
| | - Ika N Kadariswantiningsih
- Department of Nephrology, Graduate School of Medicine, Chiba University , Chiba , Japan.,Department of Medical Microbiology, Faculty of Medicine, Universitas Airlangga , Surabaya , Indonesia
| | - Masashi Aizawa
- Department of Nephrology, Graduate School of Medicine, Chiba University , Chiba , Japan
| | - Katsuhiko Asanuma
- Department of Nephrology, Graduate School of Medicine, Chiba University , Chiba , Japan
| |
Collapse
|
12
|
Sato Y, Tsukaguchi H, Morita H, Higasa K, Tran MTN, Hamada M, Usui T, Morito N, Horita S, Hayashi T, Takagi J, Yamaguchi I, Nguyen HT, Harada M, Inui K, Maruta Y, Inoue Y, Koiwa F, Sato H, Matsuda F, Ayabe S, Mizuno S, Sugiyama F, Takahashi S, Yoshimura A. A mutation in transcription factor MAFB causes Focal Segmental Glomerulosclerosis with Duane Retraction Syndrome. Kidney Int 2018; 94:396-407. [PMID: 29779709 DOI: 10.1016/j.kint.2018.02.025] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 01/24/2018] [Accepted: 02/08/2018] [Indexed: 01/02/2023]
Abstract
Focal segmental glomerulosclerosis (FSGS) is a leading cause of end-stage renal disease in children and adults. Genetic factors significantly contribute to early-onset FSGS, but the etiologies of most adult cases remain unknown. Genetic studies of monogenic syndromic FSGS exhibiting extra-renal manifestations have uncovered an unexpected biological role for genes in the development of both podocytes and other cellular lineages. To help define these roles, we studied two unrelated families with FSGS associated with Duane Retraction Syndrome, characterized by impaired horizontal eye movement due to cranial nerve malformation. All four affected individuals developed FSGS and Duane Retraction Syndrome in their first to second decade of life, manifested as restricted abduction together with globe retraction and narrowed palpebral fissure on attempted adduction. Hypoplasia of the abducens nerves and hearing impairment occurred in severely affected individuals. Genetic analyses revealed that affected individuals harbor a rare heterozygous substitution (p.Leu239Pro) in MAFB, a leucine zipper transcription factor. Luciferase assays with cultured monocytes indicated that the substitution significantly reduced transactivation of the F4/80 promoter, the known MAFB recognition element. Additionally, immunohistochemistry indicated reduced MAFB expression in the podocytes of patients. Structural modeling suggested that the p.Leu239Pro substitution in the DNA-binding domain possibly interferes with the stability of the adjacent zinc finger. Lastly, podocytes in neonatal mice with p.Leu239Pro displayed impaired differentiation. Thus, MAFB mutations impair development and/or maintenance of podocytes, abducens neurons and the inner ear. The interactions between MAFB and regulatory elements in these developing organs are likely highly specific based on spatiotemporal requirements.
Collapse
Affiliation(s)
- Yoshinori Sato
- Division of Nephrology, Department of Medicine, Showa University Fujigaoka Hospital, Fujigaoka, Japan
| | - Hiroyasu Tsukaguchi
- Second Department of Internal Medicine, Kansai Medical University, Hirakata, Japan.
| | - Hiroyuki Morita
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Aichi Medical University School of Medicine, Nagakute, Japan
| | - Koichiro Higasa
- Center for Genomic Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Mai Thi Nhu Tran
- Department of Anatomy and Embryology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Michito Hamada
- Department of Anatomy and Embryology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Toshiaki Usui
- Department of Anatomy and Embryology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan; Department of Nephrology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Naoki Morito
- Department of Nephrology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Shoichiro Horita
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Takao Hayashi
- Department of Ophthalmology, School of Medicine, Teikyo University, Tokyo, Japan
| | - Junko Takagi
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Aichi Medical University School of Medicine, Nagakute, Japan
| | - Izumi Yamaguchi
- Center for Genomic Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Huan Thanh Nguyen
- Second Department of Internal Medicine, Kansai Medical University, Hirakata, Japan
| | - Masayo Harada
- Department of Clinical Anatomy, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kiyoko Inui
- Division of Nephrology, Department of Medicine, Showa University Fujigaoka Hospital, Fujigaoka, Japan
| | - Yuichi Maruta
- Division of Nephrology, Department of Medicine, Showa University Fujigaoka Hospital, Fujigaoka, Japan
| | - Yoshihiko Inoue
- Division of Nephrology, Department of Medicine, Showa University Fujigaoka Hospital, Fujigaoka, Japan
| | - Fumihiko Koiwa
- Division of Nephrology, Department of Medicine, Showa University Fujigaoka Hospital, Fujigaoka, Japan
| | - Hiroshi Sato
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Fumihiko Matsuda
- Center for Genomic Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Shinya Ayabe
- Experimental Animal Division, RIKEN BioResource Center, Tsukuba, Japan
| | - Seiya Mizuno
- Laboratory Animal Resource Center, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Fumihiro Sugiyama
- Laboratory Animal Resource Center, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Satoru Takahashi
- Department of Anatomy and Embryology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan; Laboratory Animal Resource Center, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan; International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Japan; Life Science Center of Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Japan
| | - Ashio Yoshimura
- Division of Nephrology, Department of Medicine, Showa University Fujigaoka Hospital, Fujigaoka, Japan
| |
Collapse
|
13
|
Yang JW, Dettmar AK, Kronbichler A, Gee HY, Saleem M, Kim SH, Shin JI. Recent advances of animal model of focal segmental glomerulosclerosis. Clin Exp Nephrol 2018; 22:752-763. [PMID: 29556761 DOI: 10.1007/s10157-018-1552-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Accepted: 02/26/2018] [Indexed: 12/15/2022]
Abstract
In the last decade, great advances have been made in understanding the genetic basis for focal segmental glomerulosclerosis (FSGS). Animal models using specific gene disruption of the slit diaphragm and cytoskeleton of the foot process mirror the etiology of the human disease. Many animal models have been developed to understand the complex pathophysiology of FSGS. Therefore, we need to know the usefulness and exact methodology of creating animal models. Here, we review classic animal models and newly developed genetic animal models. Classic animal models of FSGS involve direct podocyte injury and indirect podocyte injury due to adaptive responses. However, the phenotype depends on the animal background. Renal ablation and direct podocyte toxin (PAN, adriamycin) models are leading animal models for FSGS, which have some limitations depending on mice background. A second group of animal models were developed using combinations of genetic mutation and toxin, such as NEP25, diphtheria toxin, and Thy1.1 models, which specifically injure podocytes. A third group of animal models involves genetic engineering techniques targeting podocyte expression molecules, such as podocin, CD2-associated protein, and TRPC6 channels. More detailed information about podocytopathy and FSGS can be expected in the coming decade. Different animal models should be used to study FSGS depending on the specific aim and sometimes should be used in combination.
Collapse
Affiliation(s)
- Jae Won Yang
- Department of Nephrology, Yonsei University Wonju College of Medicine, Wonju, Gangwon, Republic of Korea
| | - Anne Katrin Dettmar
- Pediatric Nephrology, Department of Pediatrics, Medical University Center Hamburg-Eppendorf, Hamburg, Germany
| | - Andreas Kronbichler
- Department of Internal Medicine IV (Nephrology and Hypertension), Universitätskliniken Innsbruck, Anichstraße 35, 6020, Innsbruck, Austria
| | - Heon Yung Gee
- Department of Pharmacology, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Moin Saleem
- Paediatric Renal Medicine, University of Bristol, Bristol, UK.,Children's Renal Unit, Bristol Royal Hospital for Children, Bristol, UK
| | - Seong Heon Kim
- Department of Pediatrics, Pusan National University Children's Hospital, Yangsan, Republic of Korea. .,Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea.
| | - Jae Il Shin
- Department of Pediatrics, Yonsei University College of Medicine, 50 Yonsei-Ro, Seodaemun-gu, Seoul, 120-752, Republic of Korea.
| |
Collapse
|
14
|
Martin CE, Jones N. Nephrin Signaling in the Podocyte: An Updated View of Signal Regulation at the Slit Diaphragm and Beyond. Front Endocrinol (Lausanne) 2018; 9:302. [PMID: 29922234 PMCID: PMC5996060 DOI: 10.3389/fendo.2018.00302] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 05/22/2018] [Indexed: 12/11/2022] Open
Abstract
Podocytes are a major component of the glomerular blood filtration barrier, and alterations to the morphology of their unique actin-based foot processes (FP) are a common feature of kidney disease. Adjacent FP are connected by a specialized intercellular junction known as the slit diaphragm (SD), which serves as the ultimate barrier to regulate passage of macromolecules from the blood. While the link between SD dysfunction and reduced filtration selectivity has been recognized for nearly 50 years, our understanding of the underlying molecular circuitry began only 20 years ago, sparked by the identification of NPHS1, encoding the transmembrane protein nephrin. Nephrin not only functions as the core component of the extracellular SD filtration network but also as a signaling scaffold via interactions at its short intracellular region. Phospho-regulation of several conserved tyrosine residues in this region influences signal transduction pathways which control podocyte cell adhesion, shape, and survival, and emerging studies highlight roles for nephrin phospho-dynamics in mechanotransduction and endocytosis. The following review aims to summarize the last 5 years of advancement in our knowledge of how signaling centered at nephrin directs SD barrier formation and function. We further provide insight on promising frontiers in podocyte biology, which have implications for SD signaling in the healthy and diseased kidney.
Collapse
|
15
|
Tabatabaeifar M, Wlodkowski T, Simic I, Denc H, Mollet G, Weber S, Moyers JJ, Brühl B, Randles MJ, Lennon R, Antignac C, Schaefer F. An inducible mouse model of podocin-mutation-related nephrotic syndrome. PLoS One 2017; 12:e0186574. [PMID: 29049388 PMCID: PMC5648285 DOI: 10.1371/journal.pone.0186574] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 09/10/2017] [Indexed: 12/03/2022] Open
Abstract
Mutations in the NPHS2 gene, encoding podocin, cause hereditary nephrotic syndrome. The most common podocin mutation, R138Q, is associated with early disease onset and rapid progression to end-stage renal disease. Knock-in mice carrying a R140Q mutation, the mouse analogue of human R138Q, show developmental arrest of podocytes and lethal renal failure at neonatal age. Here we created a conditional podocin knock-in model named NPHS2R140Q/-, using a tamoxifen-inducible Cre recombinase, which permits to study the effects of the mutation in postnatal life. Within the first week of R140Q hemizygosity induction the animals developed proteinuria, which peaked after 4–5 weeks. Subsequently the animals developed progressive renal failure, with a median survival time of 12 (95% CI: 11–13) weeks. Foot process fusion was observed within one week, progressing to severe and global effacement in the course of the disease. The number of podocytes per glomerulus gradually diminished to 18% compared to healthy controls 12–16 weeks after induction. The fraction of segmentally sclerosed glomeruli was 25%, 85% and 97% at 2, 4 and 8 weeks, respectively. Severe tubulointerstitial fibrosis was present at later disease stage and was correlated quantitatively with the level of proteinuria at early disease stages. While R140Q podocin mRNA expression was elevated, protein abundance was reduced by more than 50% within one week following induction. Whereas miRNA21 expression persistently increased during the first 4 weeks, miRNA-193a expression peaked 2 weeks after induction. In conclusion, the inducible R140Q-podocin mouse model is an auspicious model of the most common genetic cause of human nephrotic syndrome, with a spontaneous disease course strongly reminiscent of the human disorder. This model constitutes a valuable tool to test the efficacy of novel pharmacological interventions aimed to improve podocyte function and viability and attenuate proteinuria, glomerulosclerosis and progressive renal failure.
Collapse
Affiliation(s)
- Mansoureh Tabatabaeifar
- Division of Pediatric Nephrology, Center for Pediatrics and Adolescent Medicine, University of Heidelberg, Heidelberg, Germany
| | - Tanja Wlodkowski
- Division of Pediatric Nephrology, Center for Pediatrics and Adolescent Medicine, University of Heidelberg, Heidelberg, Germany
| | - Ivana Simic
- Division of Pediatric Nephrology, Center for Pediatrics and Adolescent Medicine, University of Heidelberg, Heidelberg, Germany
| | - Helga Denc
- Division of Pediatric Nephrology, Center for Pediatrics and Adolescent Medicine, University of Heidelberg, Heidelberg, Germany
| | - Geraldine Mollet
- INSERM, U1163, Imagine Institute, Laboratory of Hereditary Kidney Diseases, Paris, France
- Paris Descartes-Sorbonne Paris Cité University, Paris, France
| | - Stefanie Weber
- Pediatric Nephrology, Center for Pediatrics and Adolescent Medicine, Philipps-University Marburg, Marburg, Germany
| | | | - Barbara Brühl
- Institute for Anatomy and Cell Biology, University of Heidelberg, Heidelberg, Germany
| | - Michael Joseph Randles
- Wellcome Trust Centre for Cell Matrix Research, University of Manchester, Manchester, United Kingdom
- Faculty of Biology Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Rachel Lennon
- Wellcome Trust Centre for Cell Matrix Research, University of Manchester, Manchester, United Kingdom
- Faculty of Biology Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Corinne Antignac
- INSERM, U1163, Imagine Institute, Laboratory of Hereditary Kidney Diseases, Paris, France
- Paris Descartes-Sorbonne Paris Cité University, Paris, France
- Department of Genetics, Necker Hospital, Assistance Publique—Hôpitaux de Paris, Paris, France
| | - Franz Schaefer
- Division of Pediatric Nephrology, Center for Pediatrics and Adolescent Medicine, University of Heidelberg, Heidelberg, Germany
- * E-mail:
| |
Collapse
|
16
|
A functional variant in NEPH3 gene confers high risk of renal failure in primary hematuric glomerulopathies. Evidence for predisposition to microalbuminuria in the general population. PLoS One 2017; 12:e0174274. [PMID: 28334007 PMCID: PMC5363870 DOI: 10.1371/journal.pone.0174274] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 03/06/2017] [Indexed: 01/06/2023] Open
Abstract
Background Recent data emphasize that thin basement membrane nephropathy (TBMN) should not be viewed as a form of benign familial hematuria since chronic renal failure (CRF) and even end-stage renal disease (ESRD), is a possible development for a subset of patients on long-term follow-up, through the onset of focal and segmental glomerulosclerosis (FSGS). We hypothesize that genetic modifiers may explain this variability of symptoms. Methods We looked in silico for potentially deleterious functional SNPs, using very strict criteria, in all the genes significantly expressed in the slit diaphragm (SD). Two variants were genotyped in a cohort of well-studied adult TBMN patients from 19 Greek-Cypriot families, with a homogeneous genetic background. Patients were categorized as “Severe” or “Mild”, based on the presence or not of proteinuria, CRF and ESRD. A larger pooled cohort (HEMATURIA) of 524 patients, including IgA nephropathy patients, was used for verification. Additionally, three large general population cohorts [Framingham Heart Study (FHS), KORAF4 and SAPHIR] were used to investigate if the NEPH3-V353M variant has any renal effect in the general population. Results and conclusions Genotyping for two high-scored variants in 103 TBMN adult patients with founder mutations who were classified as mildly or severely affected, pointed to an association with variant NEPH3-V353M (filtrin). This promising result prompted testing in the larger pooled cohort (HEMATURIA), indicating an association of the 353M variant with disease severity under the dominant model (p = 3.0x10-3, OR = 6.64 adjusting for gender/age; allelic association: p = 4.2x10-3 adjusting for patients’ kinships). Subsequently, genotyping 6,531 subjects of the Framingham Heart Study (FHS) revealed an association of the homozygous 353M/M genotype with microalbuminuria (p = 1.0x10-3). Two further general population cohorts, KORAF4 and SAPHIR confirmed the association, and a meta-analysis of all three cohorts (11,258 individuals) was highly significant (p = 1.3x10-5, OR = 7.46). Functional studies showed that Neph3 homodimerization and Neph3-Nephrin heterodimerization are disturbed by variant 353M. Additionally, 353M was associated with differential activation of the unfolded protein response pathway, when overexpressed in stressed cultured undifferentiated podocyte cells, thus attesting to its functional significance. Genetics and functional studies support a “rare variant-strong effect” role for NEPH3-V353M, by exerting a negative modifier effect on primary glomerular hematuria. Additionally, genetics studies provide evidence for a role in predisposing homozygous subjects of the general population to micro-albuminuria.
Collapse
|
17
|
Huang G, Zou B, Lv J, Li T, Huai G, Xiang S, Lu S, Luo H, Zhang Y, Jin Y, Wang Y. Notoginsenoside R1 attenuates glucose-induced podocyte injury via the inhibition of apoptosis and the activation of autophagy through the PI3K/Akt/mTOR signaling pathway. Int J Mol Med 2017; 39:559-568. [PMID: 28112381 PMCID: PMC5360354 DOI: 10.3892/ijmm.2017.2864] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Accepted: 01/11/2017] [Indexed: 12/26/2022] Open
Abstract
Injury to terminally differentiated podocytes contributes ignificantly to proteinuria and glomerulosclerosis. The aim of this study was to examine the protective effects of notoginsenoside R1 (NR1) on the maintenance of podocyte number and foot process architecture via the inhibition of apoptosis, the induction of autophagy and the maintenance pf podocyte biology in target cells. The effects of NR1 on conditionally immortalized human podocytes under high glucose conditions were evaluated by determining the percentage apoptosis, the percentage autophagy and the expression levels of slit diaphragm proteins. Our results revealed that NR1 protected the podocytes against high glucose-induced injury by decreasing apoptosis, increasing autophagy and by promoting cytoskeletal recovery. The phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway was further investigated in order to elucidate the mechanisms responsible for the protective effects of NR1 on podocytes. Our data indicated that treatment with NR increased the phosphorylation levels of PI3K, Akt and mTOR, leading to the activation of the PI3K/Akt/mTOR signaling pathway in podocytes. To the best of our knowledge, this is the first in vitro study to demonstrate that NR1 protects podocytes by activating the PI3K/Akt/mTOR pathway.
Collapse
Affiliation(s)
- Guodong Huang
- Department of Nephrology, Ruikang Hospital Affiliated to Guangxi University of Chinese Medicine, Nanning, Guangxi 530011, P.R. China
| | - Bingyu Zou
- Department of Gynecology, Sichuan Academy of Medical Science and Sichuan Provincial People's Hospital, Chengdu, Sichuan 610072, P.R. China
| | - Jianzhen Lv
- School of Basic Medical Science, Guangxi University of Chinese Medicine, Nanning, Guangxi 530001, P.R. China
| | - Tongyu Li
- School of Basic Medical Science, Guangxi University of Chinese Medicine, Nanning, Guangxi 530001, P.R. China
| | - Guoli Huai
- Department of Biomedical Engineering, Medical School of University of Electronic Science and Technology of China, Chengdu, Sichuan 610054, P.R. China
| | - Shaowei Xiang
- Department of Nephrology, Ruikang Hospital Affiliated to Guangxi University of Chinese Medicine, Nanning, Guangxi 530011, P.R. China
| | - Shilong Lu
- School of Basic Medical Science, Guangxi University of Chinese Medicine, Nanning, Guangxi 530001, P.R. China
| | - Huan Luo
- Department of Nephrology, Ruikang Hospital Affiliated to Guangxi University of Chinese Medicine, Nanning, Guangxi 530011, P.R. China
| | - Yaping Zhang
- Department of Nephrology, Ruikang Hospital Affiliated to Guangxi University of Chinese Medicine, Nanning, Guangxi 530011, P.R. China
| | - Yi Jin
- Center for Perinatal Research, Research Institute at Nationwide Children's Hospital, Columbus, OH 43215, USA
| | - Yi Wang
- Department of Biomedical Engineering, Medical School of University of Electronic Science and Technology of China, Chengdu, Sichuan 610054, P.R. China
| |
Collapse
|
18
|
Huang G, Lv J, Li T, Huai G, Li X, Xiang S, Wang L, Qin Z, Pang J, Zou B, Wang Y. Notoginsenoside R1 ameliorates podocyte injury in rats with diabetic nephropathy by activating the PI3K/Akt signaling pathway. Int J Mol Med 2016; 38:1179-89. [PMID: 27571993 PMCID: PMC5029967 DOI: 10.3892/ijmm.2016.2713] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 08/11/2016] [Indexed: 01/15/2023] Open
Abstract
The present study was designed to examine the protective effect of notoginsenoside R1 (NR1) on podocytes in a rat model of streptozotocin (STZ)-induced diabetic nephropathy (DN), and to explore the mechanism responsible for NR1-induced renal protection. Diabetes was induced by a single injection of STZ, and NR1 was administered daily at a dose of 5 mg/kg (low dose), 10 mg/kg (medium) and 20 mg/kg (high) for 16 weeks in Sprague-Dawley rats. Blood glucose levels, body weight and proteinuria were measured every 4 weeks, starting on the day that the rats received NR1. Furthermore, on the day of sacrifice, blood, urine and kidneys were collected in order to assess renal function according to general parameters. Pathological staining was performed to evaluate the renal protective effect of NR1, and the expression of the key slit diaphragm proteins, namely neprhin, podocin and desmin, were evaluated. In addition, the serum levels of inflammatory cytokines [tumor necrosis factor-α (TNF-α), tumor growth factor-β1 (TGF-β1), interleukin (IL)-1 and IL-6] as well as an anti-inflammatory cytokine (IL-10) were assessed, and the apoptosis of podocytes was quantified. Finally, the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway and the involvement of nuclear factor-κB (NF-κB) inactivation was further analyzed. In this study, NR1 improved renal function by ameliorating histological alterations, increasing the expression of nephrin and podocin, decreasing the expression of desmin, and inhibiting both the inflammatory response as well as the apoptosis of podocytes. Furthermore, NR1 treatment increased the phosphorylation of both PI3K (p85) and Akt, indicating that activation of the PI3K/Akt signaling pathway was involved. Moreover, NR1 treatment decreased the phosphorylation of NF-κB (p65), suggesting the downregulation of NF-κB. This is the first study to the best of our knowledge, to clearly demonstrate that NR1 treatment ameliorates podocyte injury by inhibiting both inflammation and apoptosis through the PI3K/Akt signaling pathway.
Collapse
Affiliation(s)
- Guodong Huang
- Ruikang Hospital Affiliated to Guangxi University of Chinese Medicine, Nanning, Guangxi 530011, P.R. China
| | - Jianzhen Lv
- Guangxi University of Chinese Medicine, Nanning, Guangxi 530001, P.R. China
| | - Tongyu Li
- Guangxi University of Chinese Medicine, Nanning, Guangxi 530001, P.R. China
| | - Guoli Huai
- Department of Biomedical Engineering, Medical School of the University of Electronic Science and Technology of China, Chengdu, Sichuan 610054, P.R. China
| | - Xiang Li
- Department of Biomedical Engineering, Medical School of the University of Electronic Science and Technology of China, Chengdu, Sichuan 610054, P.R. China
| | - Shaowei Xiang
- Ruikang Hospital Affiliated to Guangxi University of Chinese Medicine, Nanning, Guangxi 530011, P.R. China
| | - Longlong Wang
- Guangxi University of Chinese Medicine, Nanning, Guangxi 530001, P.R. China
| | - Zhenlin Qin
- Guangxi University of Chinese Medicine, Nanning, Guangxi 530001, P.R. China
| | - Jianli Pang
- Ruikang Hospital Affiliated to Guangxi University of Chinese Medicine, Nanning, Guangxi 530011, P.R. China
| | - Bingyu Zou
- Department of Gynecology, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan 610072, P.R. China
| | - Yi Wang
- Department of Pharmacy, Sichuan Academy of Medical Sciences and Sichuan Provincial People's Hospital, Chengdu, Sichuan 610072, P.R. China
| |
Collapse
|
19
|
Grahammer F, Wigge C, Schell C, Kretz O, Patrakka J, Schneider S, Klose M, Kind J, Arnold SJ, Habermann A, Bräuniger R, Rinschen MM, Völker L, Bregenzer A, Rubbenstroth D, Boerries M, Kerjaschki D, Miner JH, Walz G, Benzing T, Fornoni A, Frangakis AS, Huber TB. A flexible, multilayered protein scaffold maintains the slit in between glomerular podocytes. JCI Insight 2016; 1:86177. [PMID: 27430022 DOI: 10.1172/jci.insight.86177] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Vertebrate life critically depends on renal filtration and excretion of low molecular weight waste products. This process is controlled by a specialized cell-cell contact between podocyte foot processes: the slit diaphragm (SD). Using a comprehensive set of targeted KO mice of key SD molecules, we provided genetic, functional, and high-resolution ultrastructural data highlighting a concept of a flexible, dynamic, and multilayered architecture of the SD. Our data indicate that the mammalian SD is composed of NEPHRIN and NEPH1 molecules, while NEPH2 and NEPH3 do not participate in podocyte intercellular junction formation. Unexpectedly, homo- and heteromeric NEPHRIN/NEPH1 complexes are rarely observed. Instead, single NEPH1 molecules appear to form the lower part of the junction close to the glomerular basement membrane with a width of 23 nm, while single NEPHRIN molecules form an adjacent junction more apically with a width of 45 nm. In both cases, the molecules are quasiperiodically spaced 7 nm apart. These structural findings, in combination with the flexibility inherent to the repetitive Ig folds of NEPHRIN and NEPH1, indicate that the SD likely represents a highly dynamic cell-cell contact that forms an adjustable, nonclogging barrier within the renal filtration apparatus.
Collapse
Affiliation(s)
- Florian Grahammer
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Christoph Wigge
- Buchmann Institute for Molecular Life Sciences and Institute for Biophysics, Goethe University Frankfurt, Frankfurt, Germany
| | - Christoph Schell
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine.,Faculty of Biology, and
| | - Oliver Kretz
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,BIOSS Center for Biological Signalling Studies, Albert-Ludwigs University of Freiburg, Freiburg, Germany.,Institute of Anatomy, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jaakko Patrakka
- KI/AZ Integrated Cardio-Metabolic Center (ICMC), Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Simon Schneider
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Martin Klose
- Institute of Molecular Medicine and Cell Research, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium and.,German Cancer Research Center, Heidelberg, Germany
| | - Julia Kind
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Sebastian J Arnold
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,BIOSS Center for Biological Signalling Studies, Albert-Ludwigs University of Freiburg, Freiburg, Germany.,Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Anja Habermann
- Buchmann Institute for Molecular Life Sciences and Institute for Biophysics, Goethe University Frankfurt, Frankfurt, Germany
| | - Ricarda Bräuniger
- Buchmann Institute for Molecular Life Sciences and Institute for Biophysics, Goethe University Frankfurt, Frankfurt, Germany
| | - Markus M Rinschen
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Linus Völker
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Andreas Bregenzer
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Dennis Rubbenstroth
- Institute of Virology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany
| | - Melanie Boerries
- Institute of Molecular Medicine and Cell Research, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium and.,German Cancer Research Center, Heidelberg, Germany
| | | | - Jeffrey H Miner
- Renal Division, Washington University, St. Louis, Missouri, USA
| | - Gerd Walz
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Thomas Benzing
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Alessia Fornoni
- Division of Nephrology and Katz Family Drug Discovery Center, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Achilleas S Frangakis
- Buchmann Institute for Molecular Life Sciences and Institute for Biophysics, Goethe University Frankfurt, Frankfurt, Germany
| | - Tobias B Huber
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine.,BIOSS Center for Biological Signalling Studies, Albert-Ludwigs University of Freiburg, Freiburg, Germany.,FRIAS, Freiburg Institute for Advanced Studies and ZBSA, Center for Biological System Analysis, Albert-Ludwigs-University of Freiburg, Germany
| |
Collapse
|
20
|
Xiao L, Liu C, Chen X, Yang Z. Zinc oxide nanoparticles induce renal toxicity through reactive oxygen species. Food Chem Toxicol 2016; 90:76-83. [DOI: 10.1016/j.fct.2016.02.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2015] [Revised: 01/17/2016] [Accepted: 02/02/2016] [Indexed: 10/22/2022]
|
21
|
New LA, Martin CE, Scott RP, Platt MJ, Keyvani Chahi A, Stringer CD, Lu P, Samborska B, Eremina V, Takano T, Simpson JA, Quaggin SE, Jones N. Nephrin Tyrosine Phosphorylation Is Required to Stabilize and Restore Podocyte Foot Process Architecture. J Am Soc Nephrol 2016; 27:2422-35. [PMID: 26802179 DOI: 10.1681/asn.2015091048] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 11/17/2015] [Indexed: 11/03/2022] Open
Abstract
Podocytes are specialized epithelial cells of the kidney blood filtration barrier that contribute to permselectivity via a series of interdigitating actin-rich foot processes. Positioned between adjacent projections is a unique cell junction known as the slit diaphragm, which is physically connected to the actin cytoskeleton via the transmembrane protein nephrin. Evidence indicates that tyrosine phosphorylation of the intracellular tail of nephrin initiates signaling events, including recruitment of cytoplasmic adaptor proteins Nck1 and Nck2 that regulate actin cytoskeletal dynamics. Nephrin tyrosine phosphorylation is altered in human and experimental renal diseases characterized by pathologic foot process remodeling, prompting the hypothesis that phosphonephrin signaling directly influences podocyte morphology. To explore this possibility, we generated and analyzed knockin mice with mutations that disrupt nephrin tyrosine phosphorylation and Nck1/2 binding (nephrin(Y3F/Y3F) mice). Homozygous nephrin(Y3F/Y3F) mice developed progressive proteinuria accompanied by structural changes in the filtration barrier, including podocyte foot process effacement, irregular thickening of the glomerular basement membrane, and dilated capillary loops, with a similar but later onset phenotype in heterozygous animals. Furthermore, compared with wild-type mice, nephrin(Y3F/Y3F) mice displayed delayed recovery in podocyte injury models. Profiling of nephrin tyrosine phosphorylation dynamics in wild-type mice subjected to podocyte injury indicated site-specific differences in phosphorylation at baseline, injury, and recovery, which correlated with loss of nephrin-Nck1/2 association during foot process effacement. Our results define an essential requirement for nephrin tyrosine phosphorylation in stabilizing podocyte morphology and suggest a model in which dynamic changes in phosphotyrosine-based signaling confer plasticity to the podocyte actin cytoskeleton.
Collapse
Affiliation(s)
- Laura A New
- Departments of Molecular and Cellular Biology and
| | | | - Rizaldy P Scott
- The Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada; Feinberg Cardiovascular Research Institute and Division of Nephrology and Hypertension, Northwestern University, Chicago, Illinois; and
| | - Mathew J Platt
- Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | | | | | - Peihua Lu
- Departments of Molecular and Cellular Biology and
| | | | - Vera Eremina
- The Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Tomoko Takano
- Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Jeremy A Simpson
- Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Susan E Quaggin
- The Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada; Feinberg Cardiovascular Research Institute and Division of Nephrology and Hypertension, Northwestern University, Chicago, Illinois; and
| | - Nina Jones
- Departments of Molecular and Cellular Biology and
| |
Collapse
|
22
|
Yesildag B, Bock T, Herrmanns K, Wollscheid B, Stoffel M. Kin of IRRE-like Protein 2 Is a Phosphorylated Glycoprotein That Regulates Basal Insulin Secretion. J Biol Chem 2015; 290:25891-906. [PMID: 26324709 DOI: 10.1074/jbc.m115.684704] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Indexed: 12/17/2022] Open
Abstract
Direct interactions among pancreatic β-cells via cell surface proteins inhibit basal and enhance stimulated insulin secretion. Here, we functionally and biochemically characterized Kirrel2, an immunoglobulin superfamily protein with β-cell-specific expression in the pancreas. Our results show that Kirrel2 is a phosphorylated glycoprotein that co-localizes and interacts with the adherens junction proteins E-cadherin and β-catenin in MIN6 cells. We further demonstrate that the phosphosites Tyr(595-596) are functionally relevant for the regulation of Kirrel2 stability and localization. Analysis of the extracellular and intracellular domains of Kirrel2 revealed that it is cleaved and shed from MIN6 cells and that the remaining membrane spanning cytoplasmic domain is processed by γ-secretase complex. Kirrel2 knockdown with RNA interference in MIN6 cells and ablation of Kirrel2 from mice with genetic deletion resulted in increased basal insulin secretion from β-cells, with no immediate influence on stimulated insulin secretion, total insulin content, or whole body glucose metabolism. Our results show that in pancreatic β-cells Kirrel2 localizes to adherens junctions, is regulated by multiple post-translational events, including glycosylation, extracellular cleavage, and phosphorylation, and engages in the regulation of basal insulin secretion.
Collapse
Affiliation(s)
- Burcak Yesildag
- From the Department of Biology, Institute of Molecular Health Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Otto-Stern-Weg 7, 8093 Zurich
| | - Thomas Bock
- the Department of Health Sciences and Technology, Institute of Molecular Systems Biology, Swiss Federal Institute of Technology Zurich, Auguste-Piccard-Hof 1, 8093 Zurich, and
| | - Karolin Herrmanns
- From the Department of Biology, Institute of Molecular Health Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Otto-Stern-Weg 7, 8093 Zurich
| | - Bernd Wollscheid
- the Department of Health Sciences and Technology, Institute of Molecular Systems Biology, Swiss Federal Institute of Technology Zurich, Auguste-Piccard-Hof 1, 8093 Zurich, and
| | - Markus Stoffel
- From the Department of Biology, Institute of Molecular Health Sciences, Swiss Federal Institute of Technology (ETH) Zurich, Otto-Stern-Weg 7, 8093 Zurich, the Department of Health Sciences and Technology, Institute of Molecular Systems Biology, Swiss Federal Institute of Technology Zurich, Auguste-Piccard-Hof 1, 8093 Zurich, and the Faculty of Medicine, University of Zurich, 8091 Zurich, Switzerland
| |
Collapse
|
23
|
An update: the role of Nephrin inside and outside the kidney. SCIENCE CHINA-LIFE SCIENCES 2015; 58:649-57. [PMID: 25921941 DOI: 10.1007/s11427-015-4844-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 02/27/2015] [Indexed: 12/18/2022]
Abstract
Nephrin is a key molecule in podocytes to maintain normal slit diaphragm structure. Nephin interacts with many other podocyte and slit diaphragm protein and also mediates important cell signaling pathways in podocytes. Loss of nephrin during the development leads to the congenital nephrotic syndrome in children. Reduction of nephrin expression is often observed in adult kidney diseases including diabetic nephropathy and HIV-associated nephropathy. The critical role of nephrin has been confirmed by different animal models with nephrin knockout and knockdown. Recent studies demonstrate that knockdown of nephrin expression in adult mice aggravates the progression of unilateral nephrectomy and Adriamycin-induced kidney disease. In addition to its critical role in maintaining normal glomerular filtration unit in the kidney, nephrin is also expressed in other organs. However, the exact role of nephrin in kidney and extra-renal organs has not been well characterized. Future studies are required to determine whether nephrin could be developed as a drug target to treat patients with kidney disease.
Collapse
|
24
|
Li X, Chuang PY, D'Agati VD, Dai Y, Yacoub R, Fu J, Xu J, Taku O, Premsrirut PK, Holzman LB, He JC. Nephrin Preserves Podocyte Viability and Glomerular Structure and Function in Adult Kidneys. J Am Soc Nephrol 2015; 26:2361-77. [PMID: 25644109 DOI: 10.1681/asn.2014040405] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 11/19/2014] [Indexed: 01/12/2023] Open
Abstract
Nephrin is required during kidney development for the maturation of podocytes and formation of the slit diaphragm junctional complex. Because nephrin expression is downregulated in acquired glomerular diseases, nephrin deficiency is considered a pathologic feature of glomerular injury. However, whether nephrin deficiency exacerbates glomerular injury in glomerular diseases has not been experimentally confirmed. Here, we generated mice with inducible RNA interference-mediated nephrin knockdown. Short-term nephrin knockdown (6 weeks), starting after the completion of kidney development at 5 weeks of age, did not affect glomerular structure or function. In contrast, mice with long-term nephrin knockdown (20 weeks) developed mild proteinuria, foot process effacement, filtration slit narrowing, mesangial hypercellularity and sclerosis, glomerular basement membrane thickening, subendothelial zone widening, and podocyte apoptosis. When subjected to an acquired glomerular insult induced by unilateral nephrectomy or doxorubicin, mice with short-term nephrin knockdown developed more severe glomerular injury compared with mice without nephrin knockdown. Additionally, nephrin-knockdown mice developed more exaggerated glomerular enlargement when subjected to unilateral nephrectomy and more podocyte apoptosis and depletion after doxorubicin challenge. AKT phosphorylation, which is a slit diaphragm-mediated and nephrin-dependent pathway in the podocyte, was markedly reduced in mice with long-term or short-term nephrin knockdown challenged with uninephrectomy or doxorubicin. Taken together, our data establish that under the basal condition and in acquired glomerular diseases, nephrin is required to maintain slit diaphragm integrity and slit diaphragm-mediated signaling to preserve glomerular function and podocyte viability in adult mice.
Collapse
Affiliation(s)
- Xuezhu Li
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Nephrology; Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Peter Y Chuang
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York;
| | - Vivette D D'Agati
- Department of Pathology, College of Physicians and Surgeons, Columbia University, New York, New York
| | - Yan Dai
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Nephrology, Shanghai First Municipal Hospital, Shanghai Jiaotao University School of Medicine; Shanghai, China
| | - Rabi Yacoub
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jia Fu
- Research Institute of Nephrology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
| | - Jin Xu
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Oltjon Taku
- State University of New York at University at Binghamton, Binghamton, New York
| | | | - Lawrence B Holzman
- Renal Electrolyte and Hypertension Division, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania; and
| | - John Cijiang He
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York; Renal Section, James J Peter Veterans Administration Medical Center, Bronx, New York
| |
Collapse
|
25
|
Arif E, Rathore YS, Kumari B, Ashish F, Wong HN, Holzman LB, Nihalani D. Slit diaphragm protein Neph1 and its signaling: a novel therapeutic target for protection of podocytes against glomerular injury. J Biol Chem 2014; 289:9502-18. [PMID: 24554715 DOI: 10.1074/jbc.m113.505743] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Podocytes are specialized epithelial cells that are critical components of the glomerular filtration barrier, and their dysfunction leads to proteinuria and renal failure. Therefore, preserving podocyte function is therapeutically significant. In this study, we identified Neph1 signaling as a therapeutic target that upon inhibition prevented podocyte damage from a glomerular injury-inducing agent puromycin aminonucleoside (PAN). To specifically inhibit Neph1 signaling, we used a protein transduction approach, where the cytoplasmic domain of Neph1 (Neph1CD) tagged with a protein transduction domain trans-activator of transcription was transduced in cultured podocytes prior to treatment with PAN. The PAN-induced Neph1 phosphorylation was significantly reduced in Neph1CD-transduced cells; in addition, these cells were resistant to PAN-induced cytoskeletal damage. The biochemical analysis using subfractionation studies showed that unlike control cells Neph1 was retained in the lipid raft fractions in the transduced cells following treatment with PAN, indicating that transduction of Neph1CD in podocytes prevented PAN-induced mislocalization of Neph1. In accordance, the immunofluorescence analysis further suggested that Neph1CD-transduced cells had increased ability to retain endogenous Neph1 at the membrane in response to PAN-induced injury. Similar results were obtained when angiotensin was used as an injury-inducing agent. Consistent with these observations, maintaining high levels of Neph1 at the membrane using a podocyte cell line overexpressing chimeric Neph1 increased the ability of podocytes to resist PAN-induced injury and PAN-induced albumin leakage. Using a zebrafish in vivo PAN and adriamycin injury models, we further demonstrated the ability of transduced Neph1CD to preserve glomerular function. Collectively, these results support the conclusion that inhibiting Neph1 signaling is therapeutically significant in preventing podocyte damage from glomerular injury.
Collapse
Affiliation(s)
- Ehtesham Arif
- From the Renal Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, Pennsylvania 19104 and
| | | | | | | | | | | | | |
Collapse
|
26
|
Animal models of nephrotic syndrome. Pediatr Nephrol 2013; 28:2079-88. [PMID: 23250714 DOI: 10.1007/s00467-012-2376-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 10/25/2012] [Accepted: 10/25/2012] [Indexed: 12/28/2022]
Abstract
Animal models of proteinuria and nephrotic syndrome are essential tools for studying the mechanisms of action of abnormalities in individual components of the podocyte and glomerular basement membrane. In recent years a variety of in vivo models have been developed to elucidate the function of specific podocyte proteins and their role in the pathogenesis of proteinuria and glomerulosclerosis. In this overview of the animal models currently available we discuss their contribution to our mechanistic understanding and their potential use in screening for novel targeted therapies of steroid-resistant nephrotic syndrome.
Collapse
|
27
|
Functions of the podocyte proteins nephrin and Neph3 and the transcriptional regulation of their genes. Clin Sci (Lond) 2013; 126:315-28. [DOI: 10.1042/cs20130258] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nephrin and Neph-family proteins [Neph1–3 (nephrin-like 1–3)] belong to the immunoglobulin superfamily of cell-adhesion receptors and are expressed in the glomerular podocytes. Both nephrin and Neph-family members function in cell adhesion and signalling, and thus regulate the structure and function of podocytes and maintain normal glomerular ultrafiltration. The expression of nephrin and Neph3 is altered in human proteinuric diseases emphasizing the importance of studying the transcriptional regulation of the nephrin and Neph3 genes NPHS1 (nephrosis 1, congenital, Finnish type) and KIRREL2 (kin of IRRE-like 2) respectively. The nephrin and Neph3 genes form a bidirectional gene pair, and they share transcriptional regulatory mechanisms. In the present review, we summarize the current knowledge of the functions of nephrin and Neph-family proteins and transcription factors and agents that control nephrin and Neph3 gene expression.
Collapse
|
28
|
Grahammer F, Schell C, Huber TB. Molecular understanding of the slit diaphragm. Pediatr Nephrol 2013; 28:1957-62. [PMID: 23233041 DOI: 10.1007/s00467-012-2375-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 10/16/2012] [Accepted: 10/17/2012] [Indexed: 11/30/2022]
Abstract
Glomerular filtration has always attracted the interest of nephrologists and renal researchers alike. Although several key questions on the structure and function of the kidney filter may have been answered within the last 40 years of intense research, there still remain crucial questions to be solved. The following article attempts to give a brief overview of recent developments in glomerular research highlighting particular advances in our understanding of the slit diaphragm.
Collapse
Affiliation(s)
- Florian Grahammer
- Renal Division, University Hospital Freiburg, Hugstetter Strasse 55, Freiburg 79106, Germany
| | | | | |
Collapse
|
29
|
Grahammer F, Schell C, Huber TB. The podocyte slit diaphragm--from a thin grey line to a complex signalling hub. Nat Rev Nephrol 2013; 9:587-98. [PMID: 23999399 DOI: 10.1038/nrneph.2013.169] [Citation(s) in RCA: 173] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The architectural design of our kidneys is amazingly complex, and culminates in the 3D structure of the glomerular filter. During filtration, plasma passes through a sieve consisting of a fenestrated endothelium and a broad basement membrane before it reaches the most unique part, the slit diaphragm, a specialized type of intercellular junction that connects neighbouring podocyte foot processes. When podocytes become stressed, irrespective of the causative stimulus, they undergo foot process effacement and loss of slit diaphragms--two key steps leading to proteinuria. Thus, proteinuria is the unifying denominator of a broad spectrum of podocytopathies. With the rising prevalence of chronic kidney disease and the fact that glomerular diseases account for the majority of patients with end-stage renal disease, further investigation and elucidation of this unique structure is of paramount importance. This Review recounts how perception of the slit diaphragm has changed over time as a result of intense research, from its first anatomical description as a thin intercellular connection, to an appreciation of its role as a dynamic signalling hub. These observations led to the introduction of novel concepts in podocyte biology, which could pave the way to development of highly desired, specific therapeutic strategies for glomerular diseases.
Collapse
Affiliation(s)
- Florian Grahammer
- Renal Division, University Hospital Freiburg, Hugstetter Strasse 55, Freiburg 79106, Germany
| | | | | |
Collapse
|
30
|
Arif E, Kumari B, Wagner MC, Zhou W, Holzman LB, Nihalani D. Myo1c is an unconventional myosin required for zebrafish glomerular development. Kidney Int 2013; 84:1154-65. [PMID: 23715127 PMCID: PMC3844053 DOI: 10.1038/ki.2013.201] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Revised: 03/14/2013] [Accepted: 03/21/2013] [Indexed: 12/17/2022]
Abstract
The targeting and organization of podocyte slit diaphragm proteins nephrin and neph1 is critical for development and maintenance of a functional glomerular filtration barrier. Myo1c is a non-muscle myosin motor protein that interacts directly with nephrin and neph1 and mediates their intracellular transport to the podocyte intercellular junction. Here we investigated the necessity of Myo1c in podocyte development using zebrafish as a model system. Immunofluorescence microscopy and in situ RNA hybridization analysis of zebrafish embryos showed that Myo1c is widely expressed in various tissues including the zebrafish glomerulus. Knockdown of the Myo1c gene in zebrafish using antisense morpholino derivatives resulted in an abnormal developmental phenotype that included pericardial edema and dilated renal tubules. Ultra-structural analysis of the glomerulus in Myo1c depleted zebrafish showed abnormal podocyte morphology and absence of the slit diaphragm. Consistent with these observations, the glomerular filter permeability appeared altered in zebrafish in which Myo1c expression was attenuated. The specificity of Myo1c knockdown was confirmed by a rescue experiment in which co-injection of Myo1c morpholino derivatives with orthologous Myo1c mRNA prepared from mouse cDNA lessened phenotypic abnormalities including edema in Myo1c morphants. Thus, our results demonstrate that Myo1c is necessary for podocyte morphogenesis.
Collapse
Affiliation(s)
- Ehtesham Arif
- Renal Electrolyte and Hypertension Division, Perlman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | | | | | | | | |
Collapse
|
31
|
Focal segmental glomerulosclerosis is induced by microRNA-193a and its downregulation of WT1. Nat Med 2013; 19:481-7. [PMID: 23502960 DOI: 10.1038/nm.3142] [Citation(s) in RCA: 173] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 02/16/2013] [Indexed: 02/08/2023]
Abstract
Focal segmental glomerulosclerosis (FSGS) is a frequent and severe glomerular disease characterized by destabilization of podocyte foot processes. We report that transgenic expression of the microRNA miR-193a in mice rapidly induces FSGS with extensive podocyte foot process effacement. Mechanistically, miR-193a inhibits the expression of the Wilms' tumor protein (WT1), a transcription factor and master regulator of podocyte differentiation and homeostasis. Decreased expression levels of WT1 lead to downregulation of its target genes PODXL (podocalyxin) and NPHS1 (nephrin), as well as several other genes crucial for the architecture of podocytes, initiating a catastrophic collapse of the entire podocyte-stabilizing system. We found upregulation of miR-193a in isolated glomeruli from individuals with FSGS compared to normal kidneys or individuals with other glomerular diseases. Thus, upregulation of miR-193a provides a new pathogenic mechanism for FSGS and is a potential therapeutic target.
Collapse
|
32
|
Kriz W, Shirato I, Nagata M, LeHir M, Lemley KV. The podocyte's response to stress: the enigma of foot process effacement. Am J Physiol Renal Physiol 2013; 304:F333-47. [DOI: 10.1152/ajprenal.00478.2012] [Citation(s) in RCA: 196] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Progressive loss of podocytes is the most frequent cause accounting for end-stage renal failure. Podocytes are complex, terminally differentiated cells incapable of replicating. Thus lost podocytes cannot be replaced by proliferation of neighboring undamaged cells. Moreover, podocytes occupy a unique position as epithelial cells, adhering to the glomerular basement membrane (GBM) only by their processes, whereas their cell bodies float within the filtrate in Bowman's space. This exposes podocytes to the danger of being lost by detachment as viable cells from the GBM. Indeed, podocytes are continually excreted as viable cells in the urine, and the rate of excretion dramatically increases in glomerular diseases. Given this situation, it is likely that evolution has developed particular mechanisms whereby podocytes resist cell detachment. Podocytes respond to stress and injury by undergoing tremendous changes in shape. Foot process effacement is the most prominent and, yet in some ways, the most enigmatic of those changes. This review summarizes the various structural responses of podocytes to injury, focusing on foot process effacement and detachment. We raise the hypothesis that foot process effacement represents a protective response of podocytes to escape detachment from the GBM.
Collapse
Affiliation(s)
- Wilhelm Kriz
- Centre for Biomedicine and Medical Technology Mannheim (CBTM), Anatomy and Developmental Biology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Isao Shirato
- Division of Nephrology, Department of Internal Medicine, Juntendo University, School of Medicine, Tokyo, Japan
| | - Michio Nagata
- Kidney and Vascular Pathology, Faculty of Medicine, University of Tsukuba, Tsukuba-City, Japan
| | - Michel LeHir
- Institute of Anatomy, University of Zurich, Zurich, Switzerland; and
| | - Kevin V. Lemley
- Division of Nephrology, Children's Hospital Los Angeles, Los Angeles, California
| |
Collapse
|
33
|
Chang JH, Paik SY, Mao L, Eisner W, Flannery PJ, Wang L, Tang Y, Mattocks N, Hadjadj S, Goujon JM, Ruiz P, Gurley SB, Spurney RF. Diabetic kidney disease in FVB/NJ Akita mice: temporal pattern of kidney injury and urinary nephrin excretion. PLoS One 2012; 7:e33942. [PMID: 22496773 PMCID: PMC3319540 DOI: 10.1371/journal.pone.0033942] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Accepted: 02/23/2012] [Indexed: 11/24/2022] Open
Abstract
Akita mice are a genetic model of type 1 diabetes. In the present studies, we investigated the phenotype of Akita mice on the FVB/NJ background and examined urinary nephrin excretion as a marker of kidney injury. Male Akita mice were compared with non-diabetic controls for functional and structural characteristics of renal and cardiac disease. Podocyte number and apoptosis as well as urinary nephrin excretion were determined in both groups. Male FVB/NJ Akita mice developed sustained hyperglycemia and albuminuria by 4 and 8 weeks of age, respectively. These abnormalities were accompanied by a significant increase in systolic blood pressure in 10-week old Akita mice, which was associated with functional, structural and molecular characteristics of cardiac hypertrophy. By 20 weeks of age, Akita mice developed a 10-fold increase in albuminuria, renal and glomerular hypertrophy and a decrease in the number of podocytes. Mild-to-moderate glomerular mesangial expansion was observed in Akita mice at 30 weeks of age. In 4-week old Akita mice, the onset of hyperglycemia was accompanied by increased podocyte apoptosis and enhanced excretion of nephrin in urine before the development of albuminuria. Urinary nephrin excretion was also significantly increased in albuminuric Akita mice at 16 and 20 weeks of age and correlated with the albumin excretion rate. These data suggest that: 1. FVB/NJ Akita mice have phenotypic characteristics that may be useful for studying the mechanisms of kidney and cardiac injury in diabetes, and 2. Enhanced urinary nephrin excretion is associated with kidney injury in FVB/NJ Akita mice and is detectable early in the disease process.
Collapse
Affiliation(s)
- Jae-Hyung Chang
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, North Carolina, United States of America
| | - Seung-Yeol Paik
- Chung-ang University Medical School, Seoul, Republic of Korea
| | - Lan Mao
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
| | - William Eisner
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, North Carolina, United States of America
| | - Patrick J. Flannery
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, North Carolina, United States of America
| | - Liming Wang
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, North Carolina, United States of America
| | - Yuping Tang
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, North Carolina, United States of America
| | - Natalie Mattocks
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, North Carolina, United States of America
| | - Samy Hadjadj
- INSERM U927, Poitiers, France and INSERM CIC 0802, Poitiers, France and CHU Poitiers, Endocrinologie, Poitiers, France
| | - Jean-Michel Goujon
- CHU Poitiers, Pathology Unit, Poitiers, France
- INSERM U927, Poitiers, France and INSERM CIC 0802, Poitiers, France and CHU Poitiers, Endocrinologie, Poitiers, France
| | - Phillip Ruiz
- Department of Surgery and Pathology, University of Miami, Miami, Florida, United States of America
| | - Susan B. Gurley
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, North Carolina, United States of America
| | - Robert F. Spurney
- Division of Nephrology, Department of Medicine, Duke University and Durham VA Medical Centers, Durham, North Carolina, United States of America
| |
Collapse
|
34
|
|
35
|
Abstract
Podocytes are highly differentiated cells that play an important role in maintaining glomerular filtration barrier integrity; a function regulated by small GTPase proteins of the Rho family. To investigate the role of Rho A in podocyte biology, we created transgenic mice expressing doxycycline-inducible constitutively active (V14 Rho) or dominant-negative Rho A (N19 Rho) in podocytes. Specific induction of either Rho A construct in podocytes caused albuminuria and foot process effacement along with disruption of the actin cytoskeleton as evidenced by decreased expression of the actin-associated protein synaptopodin. The mechanisms of these adverse effects, however, appeared to be different. Active V14 Rho enhanced actin polymerization, caused a reduction in nephrin mRNA and protein levels, promoted podocyte apoptosis, and decreased endogenous Rho A levels. In contrast, the dominant-negative N19 Rho caused a loss of podocyte stress fibers, did not alter the expression of either nephrin or Rho A, and did not cause podocyte apoptosis. Thus, our findings suggest that Rho A plays an important role in maintaining the integrity of the glomerular filtration barrier under basal conditions, but enhancement of Rho A activity above basal levels promotes podocyte injury.
Collapse
|
36
|
Venkatareddy M, Cook L, Abuarquob K, Verma R, Garg P. Nephrin regulates lamellipodia formation by assembling a protein complex that includes Ship2, filamin and lamellipodin. PLoS One 2011; 6:e28710. [PMID: 22194892 PMCID: PMC3237483 DOI: 10.1371/journal.pone.0028710] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 11/14/2011] [Indexed: 12/28/2022] Open
Abstract
Actin dynamics has emerged at the forefront of podocyte biology. Slit diaphragm junctional adhesion protein Nephrin is necessary for development of the podocyte morphology and transduces phosphorylation-dependent signals that regulate cytoskeletal dynamics. The present study extends our understanding of Nephrin function by showing in cultured podocytes that Nephrin activation induced actin dynamics is necessary for lamellipodia formation. Upon activation Nephrin recruits and regulates a protein complex that includes Ship2 (SH2 domain containing 5′ inositol phosphatase), Filamin and Lamellipodin, proteins important in regulation of actin and focal adhesion dynamics, as well as lamellipodia formation. Using the previously described CD16-Nephrin clustering system, Nephrin ligation or activation resulted in phosphorylation of the actin crosslinking protein Filamin in a p21 activated kinase dependent manner. Nephrin activation in cell culture results in formation of lamellipodia, a process that requires specialized actin dynamics at the leading edge of the cell along with focal adhesion turnover. In the CD16-Nephrin clustering model, Nephrin ligation resulted in abnormal morphology of actin tails in human podocytes when Ship2, Filamin or Lamellipodin were individually knocked down. We also observed decreased lamellipodia formation and cell migration in these knock down cells. These data provide evidence that Nephrin not only initiates actin polymerization but also assembles a protein complex that is necessary to regulate the architecture of the generated actin filament network and focal adhesion dynamics.
Collapse
Affiliation(s)
- Madhusudan Venkatareddy
- Division of Nephrology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Leslie Cook
- Division of Nephrology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Kamal Abuarquob
- Division of Nephrology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Rakesh Verma
- Division of Nephrology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Puneet Garg
- Division of Nephrology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail:
| |
Collapse
|
37
|
Azhibekov TA, Wu Z, Padiyar A, Bruggeman LA, Simske JS. TM4SF10 and ADAP interaction in podocytes: role in Fyn activity and nephrin phosphorylation. Am J Physiol Cell Physiol 2011; 301:C1351-9. [PMID: 21881001 DOI: 10.1152/ajpcell.00166.2011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
TM4SF10 [transmembrane tetra(4)-span family 10] is a claudin-like cell junction protein that is transiently expressed during podocyte development where its expression is downregulated in differentiating podocytes coincident with the appearance of nephrin at the slit diaphragm. In a yeast two-hybrid screen, we identified adhesion and degranulation-promoting adaptor protein (ADAP), a well-known Fyn substrate and Fyn binding partner, as a TM4SF10 interacting protein in mouse kidney. Using coimmunoprecipitation and immunohistochemistry experiments in cultured human podocytes, we show that TM4SF10 colocalizes with Fyn and ADAP but does not form a stable complex with Fyn. Cytoskeletal changes and phosphorylation events mediated by Fyn activity were reversed by TM4SF10 overexpression, including a decrease in the activating tyrosine phosphorylation of Fyn (Y(421)), suggesting TM4SF10 may have a regulatory role in suppressing Fyn activity. In addition, TM4SF10 was reexpressed following podocyte injury by puromycin aminonucleoside treatment, and its expression enhanced the abundance of high-molecular-weight forms of nephrin indicating it may participate in a mechanism controlling nephrin's appearance at the plasma membrane. Therefore, these studies have identified ADAP as another Fyn adapter protein expressed in podocytes, and that TM4SF10, possibly through ADAP, may regulate Fyn activity. Since TM4SF10 expression is temporally regulated during kidney development, these studies may help define a mechanism by which the slit diaphragm matures as a highly specialized cell junction during podocyte differentiation.
Collapse
Affiliation(s)
- Timur A Azhibekov
- Rammelkamp Center for Education and Research, Division of Neonatology, Department of Pediatrics, MetroHealth Medical Center, 2500 MetroHealth Dr., Cleveland, OH 44109, USA
| | | | | | | | | |
Collapse
|
38
|
Trans-interaction of nephrin and Neph1/Neph3 induces cell adhesion that associates with decreased tyrosine phosphorylation of nephrin. Biochem J 2011; 435:619-28. [PMID: 21306299 DOI: 10.1042/bj20101599] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Slit diaphragms are specialized junctions between glomerular epithelial cells (podocytes) that are crucial for glomerular ultrafiltration. The Ig superfamily members nephrin and Neph1 are essential components of the slit diaphragm, whereas the role of Neph1 homologue Neph3 in the slit diaphragm is unknown. In the present paper we show that Neph3 homodimerizes and heterodimerizes with nephrin and Neph1. We further investigated whether these interactions play a role in cell adhesion by using mouse L fibroblasts that lack endogenous cell-adhesion activity and found that Neph1 and Neph3 are able to induce cell adhesion alone, whereas nephrin needs to trans-interact with Neph1 or Neph3 in order to promote formation of cell-cell contacts. Tyrosine phosphorylation of nephrin was down-regulated after nephrin trans-interacted with either Neph1 or Neph3 leading to formation of cell-cell contacts. We further found that the expression of Neph3 was increased in nephrin-deficient mouse podocytes. The findings of the present paper show that nephrin and Neph1 or Neph3 trans-interactions promote cell-contact formation, suggesting that they may also function together in slit diaphragm assembly.
Collapse
|
39
|
El Hindi S, Reiser J. TRPC channel modulation in podocytes-inching toward novel treatments for glomerular disease. Pediatr Nephrol 2011; 26:1057-64. [PMID: 21161284 PMCID: PMC3098353 DOI: 10.1007/s00467-010-1718-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 10/29/2010] [Accepted: 11/05/2010] [Indexed: 11/08/2022]
Abstract
Glomerular kidney disease is a major healthcare burden and considered to represent a sum of disorders that evade a refined and effective treatment. Excellent biological and genetic studies have defined pathways that go awry in podocytes, which are the regulatory cells of the glomerular filter. The question now is how to define targets for novel improved therapies. In this review, we summarize critical points around targeting the TRPC6 channel in podocytes.
Collapse
Affiliation(s)
- Shafic El Hindi
- Department of Medicine, Division of Nephrology and Hypertension, Leonard Miller School of Medicine, University of Miami, Miami, FL USA
| | - Jochen Reiser
- Department of Medicine, Division of Nephrology and Hypertension, Leonard Miller School of Medicine, University of Miami, Miami, FL USA
- Department of Medicine, Miller School of Medicine, University of Miami, 1580 NW 10th Avenue, Batchelor Bldg, 6th Fl (R-762), Miami, FL 33136 USA
| |
Collapse
|
40
|
Ng DPK, Tai BC, Tan E, Leong H, Nurbaya S, Lim XL, Chia KS, Wong CS, Lim WY, Holthöfer H. Nephrinuria associates with multiple renal traits in type 2 diabetes. Nephrol Dial Transplant 2010; 26:2508-14. [PMID: 21196468 DOI: 10.1093/ndt/gfq738] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND The involvement of nephrin in controlling renal function is unclear with the literature only emphasizing its role in albuminuria. We therefore investigated the potential association between nephrinuria as evidenced by the appearance of urinary immunopositive nephrin fragments, with multiple renal traits. METHODS Western blot analysis of the urine samples from a cross-sectional study of 381 Chinese type 2 diabetic patients revealed four distinct protein fragments, indicative of nephrinuria. Albuminuria was measured in random spot urine samples using the albumin/creatinine ratio (ACR), while estimated glomerular filtration rate (eGFR) was calculated using the creatinine-based Modification of Diet in Renal Disease formula. RESULTS Each nephrin fragment was associated with a decline in eGFR (smallest P = 0.001). Even with the inclusion of logarithmic form of ACR (ln ACR) in the multivariate model, nephrinuria still remained significantly associated with lower eGFR (smallest P < 0.05). Nephrinuria was also strongly associated with lnACR and this finding was independent of eGFR (smallest P < 0.001). Thus, nephrinuria was independently associated with both renal traits in the form of lnACR and eGFR. Furthermore, nephrinuria was significantly associated with lower eGFR even among normoalbuminuric patients (ACR ≤ 30 mg/g) (smallest P = 0.002), potentially implicating nephrinuria in the development of normoalbuminuric renal insufficiency. Apart from the renal traits under investigation, the presence of nephrinuria did not associate with other patient clinical characteristics. CONCLUSIONS Nephrinuria was associated with multiple renal traits in type 2 diabetes even in normoalbuminuric patients who are traditionally perceived as having a low risk of chronic kidney disease.
Collapse
Affiliation(s)
- Daniel P K Ng
- Department of Epidemiology and Public Health, National University of Singapore
| | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Saito Y, Okamura M, Nakajima S, Hayakawa K, Huang T, Yao J, Kitamura M. Suppression of nephrin expression by TNF-alpha via interfering with the cAMP-retinoic acid receptor pathway. Am J Physiol Renal Physiol 2010; 298:F1436-44. [PMID: 20237236 DOI: 10.1152/ajprenal.00512.2009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Nephrin, a crucial component of the slit diaphragm, is downregulated in proteinuric glomerular diseases including glomerulonephritis. We previously reported that 1) expression of nephrin in cultured podocytes is reinforced by retinoic acid (RA) and 1,25-dihydroxyvitamin D(3), 2) these effects are mediated by retinoic acid receptor (RAR) and vitamin D receptor (VDR), and 3) basal and inducible expression of nephrin is downregulated by TNF-alpha. In the present investigation, we identified that TNF-alpha selectively represses activity of RAR but not VDR. To elucidate mechanisms underlying this observation, we tested involvement of downstream targets for TNF-alpha: nuclear factor-kappaB (NF-kappaB), mitogen-activated protein (MAP) kinases, phosphatidylinositol 3-kinase (PI3K)-Akt, and cAMP-protein kinase A (PKA). TNF-alpha caused activation of NF-kappaB, MAP kinases, and PI3K-Akt in podocytes, whereas blockade of these molecules did not affect inhibition of RAR by TNF-alpha. In contrast, TNF-alpha depressed activity of cAMP-PKA, and blockade of PKA inhibited basal and RA-induced activation of RAR. Furthermore, activity of RAR was significantly upregulated by cAMP, and the suppressive effect of TNF-alpha on RAR was reversed by cAMP-elevating agents. These results suggest that 1) expression of nephrin in podocytes is regulated by the cAMP-RAR pathway and 2) suppression of nephrin by TNF-alpha is caused, at least in part, through selective inhibition of this pathway.
Collapse
Affiliation(s)
- Yukinori Saito
- Department of Molecular Signaling, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi, Japan
| | | | | | | | | | | | | |
Collapse
|
42
|
Heikkilä E, Juhila J, Lassila M, Messing M, Perälä N, Lehtonen E, Lehtonen S, Sjef Verbeek J, Holthofer H. beta-Catenin mediates adriamycin-induced albuminuria and podocyte injury in adult mouse kidneys. Nephrol Dial Transplant 2010; 25:2437-46. [PMID: 20237062 DOI: 10.1093/ndt/gfq076] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Glomerular slit diaphragm (SD) represents a modified adherens junction composed of molecules belonging to both immunoglobulin and cadherin superfamilies. Cadherins associate with the cytosolic scaffolding protein beta-catenin, but the precise role of beta-catenin in mature or injured podocytes is not known. METHODS The conditional podocyte-specific beta-catenin-deficient mouse line was generated using the doxycycline-inducible Cre-loxP system. Expression of the beta-catenin-deficient gene was turned off at the age of 8 weeks by doxycycline treatment and the kidney phenotype was analysed. In addition, beta-catenin-deficient and control mice were treated with adriamycin (ADR) and analysed for albuminuria and morphological alterations. RESULTS Deletion of beta-catenin in mature podocytes did not change the morphology of podocytes nor did it lead to albuminuria. However, lack of beta-catenin attenuated albuminuria after ADR treatment. Electron microscopic examination showed increased podocyte foot process effacement associated with SD abnormalities in ADR-treated control mice compared to beta-catenin-deficient mice. CONCLUSIONS These results show that beta-catenin in podocytes is dispensable for adult mice, but appears to be important in modulating the SD during ADR-induced perturbation of the filtration barrier.
Collapse
Affiliation(s)
- Eija Heikkilä
- Haartman Institute, Department of Bacteriology and Immunology, University of Helsinki, Finland
| | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Juhila J, Lassila M, Roozendaal R, Lehtonen E, Messing M, Langer B, Kerjaschki D, Verbeek JS, Holthofer H. Inducible nephrin transgene expression in podocytes rescues nephrin-deficient mice from perinatal death. THE AMERICAN JOURNAL OF PATHOLOGY 2009; 176:51-63. [PMID: 19948823 DOI: 10.2353/ajpath.2010.080843] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Mutations leading to nephrin loss result in massive proteinuria both in humans and mice. Early perinatal lethality of conventional nephrin knockout mice makes it impossible to determine the role of nephrin protein in the adult kidney and in extra-renal tissues. Herein, we studied whether podocyte-specific, doxycycline-inducible, rat nephrin expression can rescue nephrin-deficient mice from perinatal lethality. Fourteen littermates out of 72 lacked endogenous nephrin and expressed transgenic rat nephrin. Six of these rescued mice survived until 6 weeks of age, whereas the nephrin-deficient pups died before the age of 5 days. The rescued mice were smaller, developed proteinuria, and showed histological abnormalities in the kidney. Despite foot process effacement, slit diaphragms were observed. Importantly, the expression and localization of several proteins associated with the signaling capacity of nephrin or the regulation of the expression of nephrin were changed in the podocytes. Indeed, all rescued mice showed impaired locomotor activity and distinct histological abnormalities in the cerebellum, and the male mice were also infertile and showed genital malformations. These observations are consistent with normal nephrin expression in the testis and cerebellum. These observations indicate that podocyte-specific expression of rat nephrin can rescue nephrin-deficient mice from perinatal death, but is not sufficient for full complementation.
Collapse
Affiliation(s)
- Juuso Juhila
- Haartman Institute, Department of Bacteriology and Immunology, University of Helsinki, Helsinki, Finland
| | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Ristola M, Arpiainen S, Saleem MA, Mathieson PW, Welsh GI, Lehtonen S, Holthöfer H. Regulation of Neph3 gene in podocytes--key roles of transcription factors NF-kappaB and Sp1. BMC Mol Biol 2009; 10:83. [PMID: 19703278 PMCID: PMC2736951 DOI: 10.1186/1471-2199-10-83] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Accepted: 08/24/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Neph3 (filtrin) is expressed in the glomerular podocytes where it localizes at the specialized cell adhesion structures of the foot processes called slit diaphragms which form the outermost layer of the glomerular filtration barrier. Neph3 protein shows homology and structural similarity to Neph1, Neph2 and nephrin, which all are crucial for maintaining the normal glomerular ultrafiltration function. The exact function of Neph3 in the kidney is not known but we have previously shown that the level of Neph3 mRNA is decreased in proteinuric diseases. This suggests that Neph3 may play a role in the pathogenesis of kidney damage, and emphasizes the need to analyze the regulatory mechanisms of Neph3 gene. In this study we investigated the transcriptional regulation of Neph3 gene by identifying transcription factors that control Neph3 expression. RESULTS We cloned and characterized approximately 5 kb fragment upstream of the Neph3 gene. Neph3 proximal promoter near the transcription start site was found to be devoid of TATA and CAAT boxes, but to contain a highly GC-rich area. Using promoter reporter gene constructs, we localized the main activating regulatory region of Neph3 gene in its proximal promoter region from -105 to -57. Within this region, putative transcription factor binding sites for NF-kappaB and Sp1 were found by computational analysis. Mutational screening indicated that NF-kappaB and Sp1 response elements are essential for the basal transcriptional activity of the Neph3 promoter. Co-transfection studies further showed that NF-kappaB and Sp1 regulate Neph3 promoter activity. In addition, overexpression of NF-kappaB increased endogenous Neph3 gene expression. Chromatin immunoprecipitation assay using cultured human podocytes demonstrated that both NF-kappaB and Sp1 interact with the Neph3 promoter. CONCLUSION Our results show that NF-kappaB and Sp1 are key regulators of Neph3 expression at the basal level in podocytes, therefore providing new insight into the molecular mechanisms that contribute to the expression of Neph3 gene.
Collapse
Affiliation(s)
- Mervi Ristola
- Department of Bacteriology and Immunology, Haartman Institute, P,O, Box 21, 00014 University of Helsinki, Finland.
| | | | | | | | | | | | | |
Collapse
|
45
|
A role for nephrin, a renal protein, in vertebrate skeletal muscle cell fusion. Proc Natl Acad Sci U S A 2009; 106:9274-9. [PMID: 19470472 DOI: 10.1073/pnas.0904398106] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Skeletal muscle is formed via fusion of myoblasts, a well-studied process in Drosophila. In vertebrates however, this process is less well understood, and whether there is evolutionary conservation with the proteins studied in flies is under investigation. Sticks and stones (Sns), a cell surface protein found on Drosophila myoblasts, has structural homology to nephrin. Nephrin is a protein expressed in kidney that is part of the filtration barrier formed by podocytes. No previous study has established any role for nephrin in skeletal muscle. We show, using two models, zebrafish and mice, that the absence of nephrin results in poorly developed muscles and incompletely fused myotubes, respectively. Although nephrin-knockout (nephrin(KO)) myoblasts exhibit prolonged activation of MAPK/ERK pathway during myogenic differentiation, expression of myogenin does not seem to be altered. Nevertheless, MAPK pathway blockade does not rescue myoblast fusion. Co-cultures of unaffected human fetal myoblasts with nephrin(KO) myoblasts or myotubes restore the formation of mature myotubes; however, the contribution of nephrin(KO) myoblasts is minimal. These studies suggest that nephrin plays a role in secondary fusion of myoblasts into nascent myotubes, thus establishing a possible functional conservation with Drosophila Sns.
Collapse
|
46
|
Jones N, New LA, Fortino MA, Eremina V, Ruston J, Blasutig IM, Aoudjit L, Zou Y, Liu X, Yu GL, Takano T, Quaggin SE, Pawson T. Nck proteins maintain the adult glomerular filtration barrier. J Am Soc Nephrol 2009; 20:1533-43. [PMID: 19443634 DOI: 10.1681/asn.2009010056] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Within the glomerulus, the scaffolding protein nephrin bridges the actin-rich foot processes that extend from adjacent podocytes to form the slit diaphragm. Mutations affecting a number of slit diaphragm proteins, including nephrin, cause glomerular disease through rearrangement of the actin cytoskeleton and disruption of the filtration barrier. We recently established that the Nck family of Src homology 2 (SH2)/SH3 cytoskeletal adaptor proteins can mediate nephrin-dependent actin reorganization. Formation of foot processes requires expression of Nck in developing podocytes, but it is unknown whether Nck maintains podocyte structure and function throughout life. Here, we used an inducible transgenic strategy to delete Nck expression in adult mouse podocytes and found that loss of Nck expression rapidly led to proteinuria, glomerulosclerosis, and altered morphology of foot processes. We also found that podocyte injury reduced phosphorylation of nephrin in adult kidneys. These data suggest that Nck is required to maintain adult podocytes and that phosphotyrosine-based interactions with nephrin may occur in foot processes of resting, mature podocytes.
Collapse
Affiliation(s)
- Nina Jones
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Road East, New Science Complex, Guelph, Ontario, Canada.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Turgeon B, Meloche S. Interpreting neonatal lethal phenotypes in mouse mutants: insights into gene function and human diseases. Physiol Rev 2009; 89:1-26. [PMID: 19126753 DOI: 10.1152/physrev.00040.2007] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The mouse represents the model of choice to study the biological function of mammalian genes through mutation of its genome. However, the biggest challenge of mouse geneticists remains the phenotypic analysis of mouse mutants. A survey of mouse mutant databases reveals a surprisingly high number of gene mutations leading to neonatal death. These genetically modified mouse mutants have been instrumental in elucidating gene function and have become important models of congenital human diseases. The main complication when phenotyping mutant mice dying during the neonatal period is the large spectrum of physiological systems whose defects can challenge neonatal survival. Here, we present a comprehensive review of gene mutations leading to neonatal lethality and discuss the impact of these mutations on the major physiological processes critical to mouse newborn survival: parturition, breathing, suckling, and homeostasis. Selected examples of mouse mutants are highlighted to illustrate how the precise identification of the timing and cause of death associated with these physiological processes allows for a more profound understanding of the underlying cellular and molecular defects. This review provides a guide for the analysis of neonatal lethal phenotypes in mutant mice that will be helpful for dissecting out the function of specific genes during mouse development.
Collapse
Affiliation(s)
- Benjamin Turgeon
- Department of Pharmacology and Molecular Biology, Université de Montréal, Montreal, Quebec, Canada
| | | |
Collapse
|
48
|
Wang L, Ellis MJ, Fields TA, Howell DN, Spurney RF. Beneficial effects of the Rho kinase inhibitor Y27632 in murine puromycin aminonucleoside nephrosis. Kidney Blood Press Res 2008; 31:111-21. [PMID: 18367845 PMCID: PMC2821439 DOI: 10.1159/000121531] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Accepted: 01/08/2008] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND AND AIMS Rho kinase (ROCK) inhibition reduces systemic blood pressure (BP) and decreases renal damage in animal models of kidney disease. The aim of this study was to determine if ROCK inhibition might have beneficial effects in glomerular disease processes that are independent of systemic BP. METHODS We investigated the effects of the ROCK inhibitor Y27632 and hydralazine in murine puromycin aminonucleoside (PAN) nephrosis. RESULTS Treatment with either Y27632 or hydralazine similarly reduced systolic BP compared to vehicle-treated controls. Seven days after treatment with PAN, albuminuria, proteinuria and effacement of podocyte foot processes were significantly reduced in Y27632- and hydralazine-treated mice compared to vehicle-treated animals. Treatment with PAN significantly reduced expression of the podocyte proteins nephrin and Neph1, and the loss of glomerular nephrin was attenuated by treatment with Y27632 but not by treatment with hydralazine. In cultured podocytes, PAN potently activated both Rho and ROCK, and PAN-induced ROCK activation was prevented by Y27632. CONCLUSIONS The ROCK inhibitor Y27632 attenuated glomerular nephrin loss in murine PAN nephrosis independent of its effects on systemic BP.
Collapse
Affiliation(s)
- Liming Wang
- Division of Nephrology, Department of Medicine, and Durham VA Medical Centers, Durham, N.C., USA
| | - Mathew J. Ellis
- Division of Nephrology, Department of Medicine, and Durham VA Medical Centers, Durham, N.C., USA
| | - Timothy A. Fields
- Department of Pathology, Duke University and Durham VA Medical Centers, Durham, N.C., USA
| | - David N. Howell
- Department of Pathology, Duke University and Durham VA Medical Centers, Durham, N.C., USA
| | - Robert F. Spurney
- Division of Nephrology, Department of Medicine, and Durham VA Medical Centers, Durham, N.C., USA
| |
Collapse
|
49
|
Quaggin SE, Kreidberg JA. Development of the renal glomerulus: good neighbors and good fences. Development 2008; 135:609-20. [PMID: 18184729 DOI: 10.1242/dev.001081] [Citation(s) in RCA: 178] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The glomerulus of the mammalian kidney is an intricate structure that contains an unusual filtration barrier that retains higher molecular weight proteins and blood cells in the circulation. Recent studies have changed our conception of the glomerulus from a relatively static structure to a dynamic one, whose integrity depends on signaling between the three major cell lineages: podocytes, endothelial and mesangial cells. Research into the signaling pathways that control glomerular development and then maintain glomerular integrity and function has recently identified several genes, such as the nephrin and Wilms' tumor 1 genes, that are mutated in human kidney disease.
Collapse
Affiliation(s)
- Susan E Quaggin
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | | |
Collapse
|
50
|
Patrakka J, Tryggvason K. Nephrin--a unique structural and signaling protein of the kidney filter. Trends Mol Med 2007; 13:396-403. [PMID: 17766183 DOI: 10.1016/j.molmed.2007.06.006] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2007] [Revised: 06/12/2007] [Accepted: 06/13/2007] [Indexed: 12/23/2022]
Abstract
Since the discovery of nephrin, the first integral component of the slit diaphragm to be identified, the podocyte slit pore has become a major focus in research concerning the glomerular filtration barrier. Nephrin is a central component of the glomerular ultrafilter, with both structural and signaling functions. The extracellular domain of nephrin and other components of the slit diaphragm seem to form a porous molecular sieve. The intracellular domain of nephrin is associated with linker proteins, such as CD2-associated protein and Nck proteins that can connect nephrin to the actin cytoskeleton. Alterations in nephrin interactions with other proteins during development or injury can lead to complex signaling reactions aimed at establishing or restoring the filter function.
Collapse
Affiliation(s)
- Jaakko Patrakka
- Division of Matrix Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institute, 171 77 Stockholm, Sweden
| | | |
Collapse
|