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Schreurs G, Maudsley S, Nast C, Praet M, Da Silva Fernandes S, Boor P, D'Haese P, De Broe ME, Vervaet BA. Chronic dehydration induces injury pathways in rats, but does not mimic histopathology of chronic interstitial nephritis in agricultural communities. Sci Rep 2023; 13:18119. [PMID: 37872220 PMCID: PMC10593944 DOI: 10.1038/s41598-023-43567-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 09/26/2023] [Indexed: 10/25/2023] Open
Abstract
CINAC-patients present renal proximal tubular cell lysosomal lesions which are also observed in patients experiencing calcineurin inhibitor (CNI) nephrotoxicity, suggesting that CINAC is a toxin-induced nephropathy. An alternative hypothesis advocates chronic dehydration as a major etiological factor for CINAC. Here, we evaluated histological and molecular changes in dehydrated versus toxin exposed rats. Wistar rats were divided in 3 groups. Group 1 (n = 6) had free access to drinking water (control group). Group 2 (n = 8) was water deprived for 10 h per 24 h, 5 days/week and placed in an incubator (37 °C) for 30 min/h during water deprivation. Group 3 (n = 8) underwent daily oral gavage with cyclosporine (40 mg/kg body weight). After 28 days, renal function, histopathology and proteomic signatures were analysed. Cyclosporine-treated rats developed focal regions of atrophic proximal tubules with associated tubulo-interstitial fibrosis. PASM staining revealed enlarged argyrophilic granules in affected proximal tubules, identified as lysosomes by immunofluorescent staining. Electron microscopy confirmed the enlarged and dysmorphic phenotype of the lysosomes. Overall, these kidney lesions resemble those that have been previously documented in farmers with CINAC. Dehydration resulted in none of the above histopathological features. Proteomic analysis revealed that dehydration and cyclosporine both induce injury pathways, yet of a clear distinct nature with a signature of toxicity only for the cyclosporine group. In conclusion, both cyclosporine and dehydration are injurious to the kidney. However, dehydration alone does not result in kidney histopathology as observed in CINAC patients, whereas cyclosporine administration does. The histopathological analogy between CINAC and calcineurin inhibitor nephrotoxicity in rats and humans supports the involvement of an as-yet-unidentified environmental toxin in CINAC etiology.
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Affiliation(s)
- Gerd Schreurs
- Laboratory of Pathophysiology, University of Antwerp, Universiteitsplein 1, 2610, Antwerp, Belgium
| | - Stuart Maudsley
- Receptor Biology Lab, Department of Biomedical Science, University of Antwerp, Antwerp, Belgium
| | | | - Marleen Praet
- Department of Pathology, Ghent University Hospital, Ghent, Belgium
| | | | - Peter Boor
- Institute of Pathology, Electron Microscopy Facility and Division of Nephrology and Immunology, RWTH Aachen University Hospital, Aachen, Germany
| | - Patrick D'Haese
- Laboratory of Pathophysiology, University of Antwerp, Universiteitsplein 1, 2610, Antwerp, Belgium
| | - Marc E De Broe
- Laboratory of Pathophysiology, University of Antwerp, Universiteitsplein 1, 2610, Antwerp, Belgium
| | - Benjamin A Vervaet
- Laboratory of Pathophysiology, University of Antwerp, Universiteitsplein 1, 2610, Antwerp, Belgium.
- Institute of Pathology, RWTH Aachen University Hospital, Aachen, Germany.
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2
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Liu S, Liu P, Fei X, Zhu C, Hou J, Wang X, Pan Y. Analysis and validation of the potential of the MYO1E gene in pancreatic adenocarcinoma based on a bioinformatics approach. Oncol Lett 2023; 26:285. [PMID: 37274465 PMCID: PMC10236097 DOI: 10.3892/ol.2023.13871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 03/22/2023] [Indexed: 06/06/2023] Open
Abstract
Pancreatic adenocarcinoma (PAAD) is a common digestive cancer, and its prognosis is poor. Myosin 1E (MYO1E) is a class I myosin family member whose expression and function have not been reported in PAAD. In the present study, bioinformatics analysis was used to explore the expression levels of MYO1E in PAAD and its prognostic value, and the immunological role of MYO1E in PAAD was analyzed. The study revealed that a variety of malignancies have substantially increased MYO1E expression. Further investigation demonstrated that PAAD tissues exhibited greater levels of MYO1E mRNA and protein expression than normal tissues. High MYO1E expression is associated with poor prognosis in patients with PAAD. MYO1E expression was also associated with pathological stage in patients with PAAD. Functional enrichment analysis demonstrated that MYO1E was linked to multiple tumor-related mechanisms in PAAD. The pancreatic adenocarcinoma tumor microenvironment (TME) was analyzed and it was revealed that MYO1E expression was positively associated with tumor immune cell infiltration. In addition, MYO1E was closely associated with some tumor chemokines/receptors and immune checkpoints. In vitro experiments revealed that the suppression of MYO1E expression could inhibit pancreatic adenocarcinoma cell proliferation, invasion and migration. Through preliminary analysis, the present study evaluated the potential function of MYO1E in PAAD and its function in TME, and MYO1E may become a potential biomarker for PAAD.
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Affiliation(s)
- Songbai Liu
- School of Clinical Medicine, Guizhou Medical University, Guiyang, Guizhou 550000, P.R. China
| | - Peng Liu
- School of Clinical Medicine, Guizhou Medical University, Guiyang, Guizhou 550000, P.R. China
- Department of Hepatobiliary Surgery, The Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou 550000, P.R. China
| | - Xiaobin Fei
- School of Clinical Medicine, Guizhou Medical University, Guiyang, Guizhou 550000, P.R. China
| | - Changhao Zhu
- Department of Hepatobiliary Surgery, The Affiliated Cancer Hospital of Guizhou Medical University, Guiyang, Guizhou 550000, P.R. China
| | - Junyi Hou
- School of Clinical Medicine, Guizhou Medical University, Guiyang, Guizhou 550000, P.R. China
| | - Xing Wang
- School of Clinical Medicine, Guizhou Medical University, Guiyang, Guizhou 550000, P.R. China
- Department of Hepatobiliary Surgery, The Affiliated Cancer Hospital of Guizhou Medical University, Guiyang, Guizhou 550000, P.R. China
| | - Yaozhen Pan
- School of Clinical Medicine, Guizhou Medical University, Guiyang, Guizhou 550000, P.R. China
- Department of Hepatobiliary Surgery, The Affiliated Cancer Hospital of Guizhou Medical University, Guiyang, Guizhou 550000, P.R. China
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3
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Ye Q, Li Y, Liu H, Mao J, Jiang H. Machine learning models for predicting steroid-resistant of nephrotic syndrome. Front Immunol 2023; 14:1090241. [PMID: 36776850 PMCID: PMC9911108 DOI: 10.3389/fimmu.2023.1090241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Accepted: 01/09/2023] [Indexed: 01/28/2023] Open
Abstract
Background In the absence of effective measures to predict steroid responsiveness, patients with nonhereditary steroid-resistant nephrotic syndrome (SRNS) have a significantly increased risk of progression to end-stage renal disease. In view of the poor outcomes of SRNS, it is urgent to identify the steroid responsiveness of idiopathic nephrotic syndrome (INS) early. Methods To build a prediction model for SRNS, we collected 91 subjects; 57 of them had steroid-sensitive nephrotic syndrome, and the others had SRNS. For each subject, 87 clinical variables were measured. In general, only a small part of these variables is informative to SRNS. Thus, we proposed a new variable selection framework including a penalized regression approach (named MLR+TLP) to select variables having a linear effect on the SRNS and a nonparametric screening method (MAC) to select variables having a nonlinear marginal (joint) effect on the SRNS. Thereafter, considering the correlation between selected clinical variables, we used a stepwise method to build our final model for predicting SRNS. In addition, a statistical testing procedure is proposed to test the overfitting of the proposed model. Results Twenty-six clinical variables were selected to be informative to SRNS, and an SVM model was built to predict SRNS with a leave-one-out cross-validation (LOO-CV) accuracy of 95.2% (overfitting p value<0.005). To make the model more useful, we incorporate prior medical information into the model and consider the correlation between selected variables. Then, a reduced SVM model including only eight clinical variables (erythrocyte sedimentation rate, urine occult blood, percentage of neutrophils, immunoglobulin A, cholesterol, vinculin autoantibody, aspartate aminotransferase, and prolonged prothrombin time) was built to have a LOO-CV accuracy of 92.8% (overfitting p value<0.005). The validation cohort showed that the reduced model obtained an accuracy of 94.0% (overfitting p value<0.005), with a sensitivity of 90.0% and a specificity of 96.7%. Notably, vinculin autoantibody is the only podocyte autoantibody included in this model. It is linearly related to steroid responsiveness. Finally, our model is freely available as a user-friendly web tool at https://datalinkx.shinyapps.io/srns/. Conclusion The SRNS prediction model constructed in this study comprehensively and objectively evaluates the internal conditions and disease status of INS patients and will provide scientific guidance for selecting treatment methods for children with nonhereditary SRNS.
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Affiliation(s)
- Qing Ye
- Department of Clinical Laboratory, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, National Children's Regional Medical Center, Hangzhou, China
| | - Yuzhou Li
- Center for Data Science, Zhejiang University, Hangzhou, China.,School of Mathematical Sciences, Zhejiang University, Hangzhou, China
| | - Huihui Liu
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, National Children's Regional Medical Center, Hangzhou, China
| | - Jianhua Mao
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, National Children's Regional Medical Center, Hangzhou, China
| | - Hangjin Jiang
- Center for Data Science, Zhejiang University, Hangzhou, China
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4
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Ye Q, Lan B, Liu H, Persson PB, Lai EY, Mao J. A critical role of the podocyte cytoskeleton in the pathogenesis of glomerular proteinuria and autoimmune podocytopathies. Acta Physiol (Oxf) 2022; 235:e13850. [PMID: 35716094 DOI: 10.1111/apha.13850] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/23/2022] [Accepted: 06/13/2022] [Indexed: 01/19/2023]
Abstract
Selective glomerular filtration relies on the membrane separating the glomerular arterioles from the Bowman space. As a major component of the glomerular filtration barrier, podocytes form foot processes by the actin cytoskeleton, which dynamically adjusts in response to environmental changes to maintain filtration barrier integrity. The slit diaphragms bridge the filtration slits between neighboring foot processes and act as signaling hubs interacting with the actin cytoskeleton. Focal adhesions relay signals to regulate actin dynamics while allowing podocyte adherence to the basement membrane. Mutations in actin regulatory and signaling proteins may disrupt the actin cytoskeleton, resulting in foot process retraction, effacement, and proteinuria. Large-scale gene expression profiling platforms, transgenic animal models, and other in vivo gene delivery methods now enhance our understanding of the interactions among podocyte focal adhesions, slit diaphragms, and actin dynamics. In addition, our team found that at least 66% of idiopathic nephrotic syndrome (INS) children have podocyte autoantibodies, which was defined as a new disease subgroup-, autoimmune podocytopathies. This review outlines the pathophysiological mechanisms of podocyte cytoskeleton protein interactions in proteinuria and glomerular podocytopathy.
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Affiliation(s)
- Qing Ye
- Department of Clinical Laboratory, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, National Children's Regional Medical Center, Hangzhou, China
| | - Bing Lan
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, National Children's Regional Medical Center, Hangzhou, China
| | - Huihui Liu
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, National Children's Regional Medical Center, Hangzhou, China
| | - Pontus B Persson
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Translational Physiology, Berlin, Germany
| | - En Yin Lai
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Institute of Translational Physiology, Berlin, Germany.,Department of Physiology, School of Basic Medical Sciences, Zhejiang University School of Medicine, Hangzhou, China
| | - Jianhua Mao
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, National Children's Regional Medical Center, Hangzhou, China
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5
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Seven novel podocyte autoantibodies were identified to diagnosis a new disease subgroup-autoimmune Podocytopathies. Clin Immunol 2021; 232:108869. [PMID: 34600127 DOI: 10.1016/j.clim.2021.108869] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 09/26/2021] [Accepted: 09/27/2021] [Indexed: 01/09/2023]
Abstract
Children with idiopathic nephrotic syndrome (INS) usually have podocyte injury, and recent studies suggest a B cell dysfunction in INS. Therefore, this study attempts to screen and identify the podocyte autoantibodies in patients. Two-dimensional electrophoresis and mass spectrometry were used to screen and identify the pathogenic podocyte autoantibodies in children with INS. The positive rate, expression pattern, and clinical correlation of these podocyte autoantibodies in children with INS were determined by clinical study. At least 66% of INS children have podocyte autoantibodies. Seven podocyte autoantibodies closely related to INS were screened and identified for the first time in this study. These podocyte autoantibodies are positively correlated with proteinuria, and its titer will decrease rapidly after effective treatment. In this study, a group of new disease subgroup-"autoimmune podocytes" were identified by podocyte autoantibodies.
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6
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Bondue T, Arcolino FO, Veys KRP, Adebayo OC, Levtchenko E, van den Heuvel LP, Elmonem MA. Urine-Derived Epithelial Cells as Models for Genetic Kidney Diseases. Cells 2021; 10:cells10061413. [PMID: 34204173 PMCID: PMC8230018 DOI: 10.3390/cells10061413] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 05/28/2021] [Accepted: 06/02/2021] [Indexed: 12/11/2022] Open
Abstract
Epithelial cells exfoliated in human urine can include cells anywhere from the urinary tract and kidneys; however, podocytes and proximal tubular epithelial cells (PTECs) are by far the most relevant cell types for the study of genetic kidney diseases. When maintained in vitro, they have been proven extremely valuable for discovering disease mechanisms and for the development of new therapies. Furthermore, cultured patient cells can individually represent their human sources and their specific variants for personalized medicine studies, which are recently gaining much interest. In this review, we summarize the methodology for establishing human podocyte and PTEC cell lines from urine and highlight their importance as kidney disease cell models. We explore the well-established and recent techniques of cell isolation, quantification, immortalization and characterization, and we describe their current and future applications.
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Affiliation(s)
- Tjessa Bondue
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
| | - Fanny O. Arcolino
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
| | - Koenraad R. P. Veys
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
- Department of Pediatrics, Division of Pediatric Nephrology, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Oyindamola C. Adebayo
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
- Centre for Molecular and Vascular Biology, Department of Cardiovascular Sciences, KU Leuven, 3000 Leuven, Belgium
| | - Elena Levtchenko
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
- Department of Pediatrics, Division of Pediatric Nephrology, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Lambertus P. van den Heuvel
- Department of Development and Regeneration, KU Leuven, 3000 Leuven, Belgium; (T.B.); (F.O.A.); (K.R.P.V.); (O.C.A.); (E.L.); (L.P.v.d.H.)
- Department of Pediatric Nephrology, Radboud University Medical Center, 6500 Nijmegen, The Netherlands
| | - Mohamed A. Elmonem
- Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo 11628, Egypt
- Correspondence:
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7
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Zhang Y, Xu C, Ye Q, Tong L, Jiang H, Zhu X, Huang L, Lin W, Fu H, Wang J, Persson PB, Lai EY, Mao J. Podocyte apoptosis in diabetic nephropathy by BASP1 activation of the p53 pathway via WT1. Acta Physiol (Oxf) 2021; 232:e13634. [PMID: 33615732 DOI: 10.1111/apha.13634] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 02/05/2021] [Accepted: 02/18/2021] [Indexed: 12/20/2022]
Abstract
AIMS Diabetic nephropathy (DN) is a leading cause of end-stage renal disease. BASP1 (brain acid-soluble protein) is up-regulated in podocyte-specific protein phosphatase 2A knockout mice (Pod-PP2A-KO) that develop kidney dysfunction. Here, we explore the role of BASP1 for podocytes in DN. METHODS BASP1 was assessed in kidneys from DN patients and DN mouse models, podocyte specific BASP1 knockout mice (Pod-BASP1-KO mice) were generated and studied in vivo. Furthermore, podocyte injury and apoptosis were measured after BASP1 knockdown and overexpression in a mouse podocyte cell line (MPC5). Potential signalling pathways involved in podocyte apoptosis were detected. RESULTS BASP1 expression was up-regulated in DN patients compared to normal controls. BASP1 specific deletion in podocytes protected against podocyte injury by reducing the loss of expression of slit diaphragm molecules and foot process effacement in the DN model. BASP1 promoted actin cytoskeleton rearrangements and apoptosis in the MPC5 podocyte line. Molecules involved in the p53 pathway were down-regulated in BASP1 knockdown podocytes treated with high glucose compared to controls. BASP1 promoted podocyte apoptosis and P53 pathway activation through co-repression with Wilms' tumour 1 transcription factor (WT1). CONCLUSION BASP1 activates the p53 pathway through modulation of WT1 to induce podocyte apoptosis in diabetic nephropathy.
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Affiliation(s)
- Yingying Zhang
- Department of Nephrology The Children Hospital of Zhejiang University School of MedicineNational Clinical Research Center for Child HealthNational Children’s Regional Medical Center Hangzhou China
| | - Chengxian Xu
- Department of Nephrology The Children Hospital of Zhejiang University School of MedicineNational Clinical Research Center for Child HealthNational Children’s Regional Medical Center Hangzhou China
| | - Qing Ye
- Department of Nephrology The Children Hospital of Zhejiang University School of MedicineNational Clinical Research Center for Child HealthNational Children’s Regional Medical Center Hangzhou China
| | - Lingxiao Tong
- Department of Nephrology The Children Hospital of Zhejiang University School of MedicineNational Clinical Research Center for Child HealthNational Children’s Regional Medical Center Hangzhou China
| | - Hong Jiang
- Kidney Disease Center The First Affiliated HospitalZhejiang University School of Medicine Hangzhou China
| | - Xiujuan Zhu
- Department of Nephrology The Children Hospital of Zhejiang University School of MedicineNational Clinical Research Center for Child HealthNational Children’s Regional Medical Center Hangzhou China
| | - Limin Huang
- Department of Nephrology The Children Hospital of Zhejiang University School of MedicineNational Clinical Research Center for Child HealthNational Children’s Regional Medical Center Hangzhou China
| | - Weiqiang Lin
- Institute of Translational Medicine Zhejiang University School of Medicine Hangzhou China
| | - Haidong Fu
- Department of Nephrology The Children Hospital of Zhejiang University School of MedicineNational Clinical Research Center for Child HealthNational Children’s Regional Medical Center Hangzhou China
| | - Jingjing Wang
- Department of Nephrology The Children Hospital of Zhejiang University School of MedicineNational Clinical Research Center for Child HealthNational Children’s Regional Medical Center Hangzhou China
| | - Pontus B. Persson
- Institute of Vegetative Physiology Charité–Universitätsmedizin Berlincorporate member of Freie Universität Berlin, Humboldt‐Universität zu Berlin, and Berlin Institute of Health Berlin Germany
| | - En Yin Lai
- Kidney Disease Center The First Affiliated HospitalZhejiang University School of Medicine Hangzhou China
- Institute of Vegetative Physiology Charité–Universitätsmedizin Berlincorporate member of Freie Universität Berlin, Humboldt‐Universität zu Berlin, and Berlin Institute of Health Berlin Germany
- Department of Physiology Zhejiang University School of Medicine Hangzhou China
| | - Jianhua Mao
- Department of Nephrology The Children Hospital of Zhejiang University School of MedicineNational Clinical Research Center for Child HealthNational Children’s Regional Medical Center Hangzhou China
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8
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Wlazlo E, Mehrad B, Morel L, Scindia Y. Iron Metabolism: An Under Investigated Driver of Renal Pathology in Lupus Nephritis. Front Med (Lausanne) 2021; 8:643686. [PMID: 33912577 PMCID: PMC8071941 DOI: 10.3389/fmed.2021.643686] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/10/2021] [Indexed: 12/13/2022] Open
Abstract
Nephritis is a common manifestation of systemic lupus erythematosus, a condition associated with inflammation and iron imbalance. Renal tubules are the work horse of the nephron. They contain a large number of mitochondria that require iron for oxidative phosphorylation, and a tight control of intracellular iron prevents excessive generation of reactive oxygen species. Iron supply to the kidney is dependent on systemic iron availability, which is regulated by the hepcidin-ferroportin axis. Most of the filtered plasma iron is reabsorbed in proximal tubules, a process that is controlled in part by iron regulatory proteins. This review summarizes tubulointerstitial injury in lupus nephritis and current understanding of how renal tubular cells regulate intracellular iron levels, highlighting the role of iron imbalance in the proximal tubules as a driver of tubulointerstitial injury in lupus nephritis. We propose a model based on the dynamic ability of iron to catalyze reactive oxygen species, which can lead to an accumulation of lipid hydroperoxides in proximal tubular epithelial cells. These iron-catalyzed oxidative species can also accentuate protein and autoantibody-induced inflammatory transcription factors leading to matrix, cytokine/chemokine production and immune cell infiltration. This could potentially explain the interplay between increased glomerular permeability and the ensuing tubular injury, tubulointerstitial inflammation and progression to renal failure in LN, and open new avenues of research to develop novel therapies targeting iron metabolism.
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Affiliation(s)
- Ewa Wlazlo
- Department of Medicine, University of Virginia School of Medicine, Charlottesville, VA, United States
| | - Borna Mehrad
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Florida, Gainesville, FL, United States.,Department of Pathology, University of Florida, Gainesville, FL, United States
| | - Laurence Morel
- Department of Pathology, University of Florida, Gainesville, FL, United States
| | - Yogesh Scindia
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of Florida, Gainesville, FL, United States.,Department of Pathology, University of Florida, Gainesville, FL, United States.,Division of Nephrology, University of Florida, Gainesville, FL, United States
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9
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Chen Y, Wang Z, Li Q, Yu L, Zhu Y, Wang J, Sun S. oxLDL promotes podocyte migration by regulating CXCL16, ADAM10 and ACTN4. Mol Med Rep 2020; 22:1976-1984. [PMID: 32705248 PMCID: PMC7411416 DOI: 10.3892/mmr.2020.11292] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Accepted: 05/22/2020] [Indexed: 01/19/2023] Open
Abstract
Nephrotic syndrome (NS) is one of the most common causes of chronic kidney disease in the pediatric population. Hyperlipidemia is one of the main features of NS. The present study investigated the role of CXC motif chemokine ligand 16 (CXCL16) and ADAM metallopeptidase domain 10 (ADAM10) in oxidized low-density lipoprotein (oxLDL)-stimualted podocytes and the underlying mechanisms. CXCL16 and ADAM10 expression levels in oxLDL-treated podocytes were measured via reverse transcription-quantitative PCR and western blotting. Cell migration assays were conducted to assess the migration of oxLDL-treated podocytes. CXCL16 or ADAM10 overexpression and knockdown assays were conducted. The results indicated that oxLDL stimulation increased ADAM10 and CXCL16 expression levels, and enhanced podocyte migration compared with the control group. Moreover, CXCL16 and ADAM10 overexpression significantly increased podocyte migration and the expression of actinin-α4 (ACTN4) compared with the control groups. By contrast, CXCL16 and ADAM10 knockdown significantly reduced podocyte migration and the expression of ACTN4 compared with the control groups. The results suggested that oxLDL promoted podocyte migration by regulating CXCL16 and ADAM10 expression, as well as by modulating the actin cytoskeleton. Therefore, CXCL16 and ADAM10 may serve as novel therapeutic targets for primary nephrotic syndrome in children.
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Affiliation(s)
- Yuan Chen
- Department of Pediatrics, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250021, P.R. China
| | - Zhiyi Wang
- Department of Hepatobiliary Surgery, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong 250021, P.R. China
| | - Qian Li
- Department of Pediatrics, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong 250021, P.R. China
| | - Lichun Yu
- Department of Pediatrics, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong 250021, P.R. China
| | - Yanji Zhu
- Department of Pediatrics, People's Hospital of Rizhao, Rizhao, Shandong 276800, P.R. China
| | - Jing Wang
- Department of Pediatrics, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong 250021, P.R. China
| | - Shuzhen Sun
- Department of Pediatrics, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250021, P.R. China
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10
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Shen H, Bao Y, Feng C, Fu H, Mao J. Overexpression of Myo1e promotes albumin endocytosis by mouse glomerular podocytes mediated by Dynamin. PeerJ 2020; 8:e8599. [PMID: 32211226 PMCID: PMC7083160 DOI: 10.7717/peerj.8599] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 01/19/2020] [Indexed: 11/20/2022] Open
Abstract
Background As a fundamental process internalizing molecules from the plasma membrane, endocytosis plays a crucial role in podocyte biology. Our previous study has identified that overexpression of Myole may enhance podocyte endocytosis. However, its potential mechanism has been not well understand. Thus, we aimed to analyze whether albumin endocytosis by mouse glomerular podocytes is dependent on Myo1e expression. Also, we aimed to elucidate whether the underlying mechanism is mediated by Dynamin. Methods Firstly, mouse podocyte cells (MPC5) were treated with different concentrations of FITC-bovine serum albumin (BSA). The fluorescence intensity and cell viability were detected by flow cytometry and MTT assays, respectively. Afterwards, the optimal concentration of FITC-BSA was determined. Secondly, MPC5 cells were treated with Myole overexpression or knockdown. Cell morphology was observed under microscope. Immunofluorescence assay was used to determine the expression of F-actin. The protein expression of nephrin and podocin was detected by western blot. Flow cytometry was used to detect MPC5 cell apoptosis with annexin V. Finally, MPC5 cells were treated with Myole overexpression and/or Dynasore (a GTPase inhibitor of Dynamin). The fluorescence intensity was detected using flow cytometry assay. Results MPC5 endocytosis BSA was elevated with a concentration-dependent manner. MTT results showed that MPC5 cell viability was inhibited with a concentration-dependent manner. Myo1e overexpression promoted podocyte endocytic FITC-BSA, which was contrary to its knockdown. Under microscope, after inhibition of Myo1e, podocyte foot process fusion was observed. Myo1e overexpression promoted the expression of cytoskeleton F-actin and podocyte-specific molecules (nephrin and podocin) in podocyte endocytic FITC-BSA. Furthermore, we found that Myo1e promoted the apoptosis of podocytes. Dynasore attenuated the increase in endocytosis of FITC-BSA induced by Myo1e overexpression, suggesting that podocytes might mediate albumin endocytosis via Myo1e-Dynamin-Albumin. Conclusion Our findings revealed that overexpression of Myo1e promotes albumin endocytosis in mouse glomerular podocyte endocytic albumin mediated by Dynamin.
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Affiliation(s)
- Huijun Shen
- Department of Nephrology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Yu Bao
- Department of Nephrology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Chunyue Feng
- Department of Nephrology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Haidong Fu
- Department of Nephrology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Jianhua Mao
- Department of Nephrology, The Children's Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
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11
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Watts JA, Burdick J, Daigneault J, Zhu Z, Grunseich C, Bruzel A, Cheung VG. cis Elements that Mediate RNA Polymerase II Pausing Regulate Human Gene Expression. Am J Hum Genet 2019; 105:677-688. [PMID: 31495490 PMCID: PMC6817524 DOI: 10.1016/j.ajhg.2019.08.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 08/09/2019] [Indexed: 12/11/2022] Open
Abstract
Aberrant gene expression underlies many human diseases. RNA polymerase II (Pol II) pausing is a key regulatory step in transcription. Here, we mapped the locations of RNA Pol II in normal human cells and found that RNA Pol II pauses in a consistent manner across individuals and cell types. At more than 1,000 genes including MYO1E and SESN2, RNA Pol II pauses at precise nucleotide locations. Characterization of these sites shows that RNA Pol II pauses at GC-rich regions that are marked by a sequence motif. Sixty-five percent of the pause sites are cytosines. By differential allelic gene expression analysis, we showed in our samples and a population dataset from the Genotype-Tissue Expression (GTEx) consortium that genes with more paused polymerase have lower expression levels. Furthermore, mutagenesis of the pause sites led to a significant increase in promoter activities. Thus, our data uncover that RNA Pol II pauses precisely at sites with distinct sequence features that in turn regulate gene expression.
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Affiliation(s)
- Jason A Watts
- Department of Internal Medicine, Division of Nephrology, University of Michigan, Ann Arbor, MI, USA
| | | | | | - Zhengwei Zhu
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Christopher Grunseich
- National Institute of Neurological Disorders and Stroke, National Institute of Health, Bethesda, MD, USA
| | - Alan Bruzel
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Vivian G Cheung
- Howard Hughes Medical Institute, Chevy Chase, MD, USA; Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA; Department of Pediatrics, Division of Neurology, University of Michigan, Ann Arbor, MI, USA.
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12
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Abstract
Iron is an essential element that is indispensable for life. The delicate physiological body iron balance is maintained by both systemic and cellular regulatory mechanisms. The iron-regulatory hormone hepcidin assures maintenance of adequate systemic iron levels and is regulated by circulating and stored iron levels, inflammation and erythropoiesis. The kidney has an important role in preventing iron loss from the body by means of reabsorption. Cellular iron levels are dependent on iron import, storage, utilization and export, which are mainly regulated by the iron response element-iron regulatory protein (IRE-IRP) system. In the kidney, iron transport mechanisms independent of the IRE-IRP system have been identified, suggesting additional mechanisms for iron handling in this organ. Yet, knowledge gaps on renal iron handling remain in terms of redundancy in transport mechanisms, the roles of the different tubular segments and related regulatory processes. Disturbances in cellular and systemic iron balance are recognized as causes and consequences of kidney injury. Consequently, iron metabolism has become a focus for novel therapeutic interventions for acute kidney injury and chronic kidney disease, which has fuelled interest in the molecular mechanisms of renal iron handling and renal injury, as well as the complex dynamics between systemic and local cellular iron regulation.
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13
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Zhu X, Ye Y, Xu C, Gao C, Zhang Y, Zhou J, Lin W, Mao J. Protein phosphatase 2A modulates podocyte maturation and glomerular functional integrity in mice. Cell Commun Signal 2019; 17:91. [PMID: 31387591 PMCID: PMC6685276 DOI: 10.1186/s12964-019-0402-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 07/22/2019] [Indexed: 01/08/2023] Open
Abstract
Background Protein phosphorylation & dephosphorylation are ubiquitous cellular processes that allow for the nuanced and reversible regulation of protein activity. Protein phosphatase 2A (PP2A) is a multifunction phosphatase that is well expressed in all cell types of kidney during early renal development, though its functions in kidney remains to be elucidated. Methods PP2A conditional knock-out mice was generated with PP2A fl/fl mice that were crossed with Podocin-Cre mice. The phenotype of Pod-PP2A–KO mice (homozygous for the floxed PP2A allele with Podocin-Cre) and littermate PP2A fl/fl controls (homozygous for the PP2A allele but lacking Podocin-Cre) were further studied. Primary podocytes isolated from the Pod-PP2A-KO mice were cultured and they were then employed with sing label-free nano-LC − MS/MS technology on a Q-exactive followed by SIEVE processing to identify possible target molecular entities for the dephosphorylation effect of PP2A, in which Western blot and immunofluorescent staining were used to analyze further. Results Pod-PP2A–KO mice were developed with weight loss, growth retardation, proteinuria, glomerulopathy and foot process effacement, together with reduced expression of some slit diaphragm molecules and cytoskeleton rearrangement of podocytes. Y box protein 1 (YB-1) was identified to be the target molecule for dephosphorylation effect of PP2A. Furthermore, YB-1 phosphorylation was up-regulated in the Pod-PP2A–KO mice in contrast to the wild type controls, while total and un-phosphorylated YB-1 both was moderately down-regulated in podocytes from the Pod-PP2A-KO mice. Conclusion Our study revealed the important role of PP2A in regulating the development of foot processes and fully differentiated podocytes whereas fine-tuning of YB-1 via a post-translational modification by PP2A regulating its activity might be crucial for the functional integrity of podocytes and glomerular filtration barrier. Graphic abstract ![]()
Electronic supplementary material The online version of this article (10.1186/s12964-019-0402-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xiujuan Zhu
- Department of Nephrology, The Children Hospital of Zhejiang University School of Medicine, #57 Zhugan Lane, Hangzhou, 310003, Zhejiang Province, People's Republic of China
| | - Yuhong Ye
- Department of Nephrology, The Children Hospital of Zhejiang University School of Medicine, #57 Zhugan Lane, Hangzhou, 310003, Zhejiang Province, People's Republic of China
| | - Chengxian Xu
- Department of Nephrology, The Children Hospital of Zhejiang University School of Medicine, #57 Zhugan Lane, Hangzhou, 310003, Zhejiang Province, People's Republic of China
| | - Cunji Gao
- Chronic Disease Research Institute, Department of Nutrition and Food Hygiene, Zhejiang University School of Public Health, Hangzhou, 310058, Zhejiang Province, People's Republic of China
| | - Yingying Zhang
- Department of Nephrology, The Children Hospital of Zhejiang University School of Medicine, #57 Zhugan Lane, Hangzhou, 310003, Zhejiang Province, People's Republic of China
| | - Jing Zhou
- Harvard Center for Polycystic Kidney Disease Research and Renal Division, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA02115, USA
| | - Weiqiang Lin
- Institute of Translational Medicine, School of Medicine, Zhejiang University, Hangzhou, 310058, Zhejiang Province, People's Republic of China.
| | - Jianhua Mao
- Department of Nephrology, The Children Hospital of Zhejiang University School of Medicine, #57 Zhugan Lane, Hangzhou, 310003, Zhejiang Province, People's Republic of China.
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14
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Encinar Del Dedo J, Idrissi FZ, Fernandez-Golbano IM, Garcia P, Rebollo E, Krzyzanowski MK, Grötsch H, Geli MI. ORP-Mediated ER Contact with Endocytic Sites Facilitates Actin Polymerization. Dev Cell 2017; 43:588-602.e6. [PMID: 29173820 DOI: 10.1016/j.devcel.2017.10.031] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 09/11/2017] [Accepted: 10/27/2017] [Indexed: 11/18/2022]
Abstract
Oxysterol binding protein-related proteins (ORPs) are conserved lipid binding polypeptides, enriched at ER contacts sites. ORPs promote non-vesicular lipid transport and work as lipid sensors in the context of many cellular tasks, but the determinants of their distinct localization and function are not understood. Here, we demonstrate that the yeast endocytic invaginations associate with the ER and that this association specifically requires the ORPs Osh2 and Osh3, which bridge the endocytic myosin-I Myo5 to the ER integral-membrane VAMP-associated protein (VAP) Scs2. Disruption of the ER contact with endocytic sites using ORP, VAP, myosin-I, or reticulon mutants delays and weakens actin polymerization and interferes with vesicle scission. Finally, we provide evidence suggesting that ORP-dependent sterol transfer facilitates actin polymerization at endocytic sites.
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Affiliation(s)
- Javier Encinar Del Dedo
- Institute for Molecular Biology of Barcelona (CSIC), Baldiri Reixac 15, 08028 Barcelona, Spain
| | - Fatima-Zahra Idrissi
- Institute for Molecular Biology of Barcelona (CSIC), Baldiri Reixac 15, 08028 Barcelona, Spain
| | | | - Patricia Garcia
- Institute for Molecular Biology of Barcelona (CSIC), Baldiri Reixac 15, 08028 Barcelona, Spain
| | - Elena Rebollo
- Institute for Molecular Biology of Barcelona (CSIC), Baldiri Reixac 15, 08028 Barcelona, Spain
| | - Marek K Krzyzanowski
- Institute for Molecular Biology of Barcelona (CSIC), Baldiri Reixac 15, 08028 Barcelona, Spain
| | - Helga Grötsch
- Institute for Molecular Biology of Barcelona (CSIC), Baldiri Reixac 15, 08028 Barcelona, Spain
| | - Maria Isabel Geli
- Institute for Molecular Biology of Barcelona (CSIC), Baldiri Reixac 15, 08028 Barcelona, Spain.
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15
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Marusugi K, Nakano K, Sasaki H, Kimura J, Yanobu-Takanashi R, Okamura T, Sasaki N. Functional validation of tensin2 SH2-PTB domain by CRISPR/Cas9-mediated genome editing. J Vet Med Sci 2016; 78:1413-1420. [PMID: 27246398 PMCID: PMC5059368 DOI: 10.1292/jvms.16-0205] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Podocytes are terminally differentiated and highly specialized cells in the glomerulus,
and they form a crucial component of the glomerular filtration barrier. The ICGN mouse is
a model of glomerular dysfunction that shows gross morphological changes in the podocyte
foot process, accompanied by proteinuria. Previously, we demonstrated that proteinuria in
ICR-derived glomerulonephritis mouse ICGN mice might be caused by a deletion mutation in
the tensin2 (Tns2) gene (designated Tns2nph).
To test whether this mutation causes the mutant phenotype, we created knockout (KO) mice
carrying a Tns2 protein deletion in the C-terminal Src homology and phosphotyrosine
binding (SH2-PTB) domains (designated Tns2ΔC) via
CRISPR/Cas9-mediated genome editing.
Tns2nph/Tns2ΔC compound
heterozygotes and Tns2ΔC/Tns2ΔC
homozygous KO mice displayed podocyte abnormalities and massive proteinuria similar to
ICGN mice, indicating that these two mutations are allelic. Further, this result suggests
that the SH2-PTB domain of Tns2 is required for podocyte integrity. Tns2
knockdown in a mouse podocyte cell line significantly enhanced actin stress fiber
formation and cell migration. Thus, this study provides evidence that alteration of actin
remodeling resulting from Tns2 deficiency causes morphological changes in podocytes and
subsequent proteinuria.
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Affiliation(s)
- Kiyoma Marusugi
- Laboratory of Laboratory Animal Science and Medicine, School of Veterinary Medicine, Kitasato University, Towada, Aomori 034-8628, Japan
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16
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Lennon R, Stuart HM, Bierzynska A, Randles MJ, Kerr B, Hillman KA, Batra G, Campbell J, Storey H, Flinter FA, Koziell A, Welsh GI, Saleem MA, Webb NJA, Woolf AS. Coinheritance of COL4A5 and MYO1E mutations accentuate the severity of kidney disease. Pediatr Nephrol 2015; 30:1459-65. [PMID: 25739341 PMCID: PMC4536279 DOI: 10.1007/s00467-015-3067-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Revised: 02/02/2015] [Accepted: 02/06/2015] [Indexed: 12/11/2022]
Abstract
BACKGROUND Mutations in podocyte and basement membrane genes are associated with a growing spectrum of glomerular disease affecting adults and children. Investigation of familial cases has helped to build understanding of both normal physiology and disease. METHODS We investigated a consanguineous family with a wide clinical phenotype of glomerular disease using clinical, histological, and new genetic studies. RESULTS We report striking variability in severity of nephropathy within an X-linked Alport syndrome (XLAS) family. Four siblings each carried a mutant COL4A5 allele, p.(Gly953Val) and p.(Gly1033Arg). Two boys had signs limited to hematuria and mild/moderate proteinuria. In striking contrast, a sister presented with end-stage renal disease (ESRD) at 8 years of age and an infant brother presented with nephrotic syndrome, progressing to ESRD by 3 years of age. Both were subsequently found to have homozygous variants in MYO1E, p.(Lys118Glu) and p.(Thr876Arg). MYO1E is a gene implicated in focal segmental glomerulosclerosis and it encodes a podocyte-expressed non-muscle myosin. Bioinformatic modeling demonstrated that the collagen IV-alpha3,4,5 extracellular network connected via known protein-protein interactions to intracellular myosin 1E. CONCLUSIONS COL4A5 and MYO1E mutations may summate to perturb common signaling pathways, resulting in more severe disease than anticipated independently. We suggest screening for MYO1E and other non-COL4 'podocyte gene' mutations in XLAS when clinical nephropathy is more severe than expected for an individual's age and sex.
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Affiliation(s)
- Rachel Lennon
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Michael Smith Building, M13 9PT, Manchester, UK,
| | | | | | - Michael J. Randles
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Michael Smith Building, M13 9PT Manchester, UK ,Institute of Human Development, Faculty of Human Sciences, University of Manchester, Manchester, UK
| | - Bronwyn Kerr
- Manchester Centre for Genomic Medicine, Manchester, UK
| | | | - Gauri Batra
- Department of Paediatric Histopathology, CMFT, Manchester, UK
| | | | - Helen Storey
- Molecular Genetics, Viapath, Guy’s Hospital, London, UK
| | - Frances A. Flinter
- Clinical Genetics Department, Guy’s and St Thomas’ NHS Foundation Trust, London, UK
| | - Ania Koziell
- Guy’s and St Thomas’ NHS Foundation Trust and King’s College London, London, UK
| | | | | | - Nicholas J. A. Webb
- Department of Paediatric Nephrology, Central Manchester University Hospitals NHS Foundation Trust (CMFT), Manchester Academic Health Science Centre (MAHSC), Manchester, UK
| | - Adrian S. Woolf
- Institute of Human Development, Faculty of Human Sciences, University of Manchester, Manchester, UK ,Department of Paediatric Nephrology, Central Manchester University Hospitals NHS Foundation Trust (CMFT), Manchester Academic Health Science Centre (MAHSC), Manchester, UK
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18
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Lohmann F, Sachs M, Meyer TN, Sievert H, Lindenmeyer MT, Wiech T, Cohen CD, Balabanov S, Stahl RAK, Meyer-Schwesinger C. UCH-L1 induces podocyte hypertrophy in membranous nephropathy by protein accumulation. Biochim Biophys Acta Mol Basis Dis 2014; 1842:945-58. [PMID: 24583340 DOI: 10.1016/j.bbadis.2014.02.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Revised: 02/18/2014] [Accepted: 02/21/2014] [Indexed: 11/18/2022]
Abstract
Podocytes are terminally differentiated cells of the glomerular filtration barrier that react with hypertrophy in the course of injury such as in membranous nephropathy (MGN). The neuronal deubiquitinase ubiquitin C-terminal hydrolase L1 (UCH-L1) is expressed and activated in podocytes of human and rodent MGN. UCH-L1 regulates the mono-ubiquitin pool and induces accumulation of poly-ubiquitinated proteins in affected podocytes. Here, we investigated the role of UCH-L1 in podocyte hypertrophy and in the homeostasis of the hypertrophy associated "model protein" p27(Kip1). A better understanding of the basic mechanisms leading to podocyte hypertrophy is crucial for the development of specific therapies in MGN. In human and rat MGN, hypertrophic podocytes exhibited a simultaneous up-regulation of UCH-L1 and of cytoplasmic p27(Kip1) content. Functionally, inhibition of UCH-L1 activity and knockdown or inhibition of UCH-L1 attenuated podocyte hypertrophy by decreasing the total protein content in isolated glomeruli and in cultured podocytes. In contrast, UCH-L1 levels and activity increased podocyte hypertrophy and total protein content in culture, specifically of cytoplasmic p27(Kip1). UCH-L1 enhanced cytoplasmic p27(Kip1) levels by nuclear export and decreased poly-ubiquitination and proteasomal degradation of p27(Kip1). In parallel, UCH-L1 increased podocyte turnover, migration and cytoskeletal rearrangement, which are associated with known oncogenic functions of cytoplasmic p27(Kip1) in cancer. We propose that UCH-L1 induces podocyte hypertrophy in MGN by increasing the total protein content through altered degradation and accumulation of proteins such as p27(Kip1) in the cytoplasm of podocytes. Modification of both UCH-L1 activity and levels could be a new therapeutic avenue to podocyte hypertrophy in MGN.
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Affiliation(s)
- Frithjof Lohmann
- Department of Internal Medicine, Nephrology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Marlies Sachs
- Department of Internal Medicine, Nephrology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tobias N Meyer
- Department of Internal Medicine, Nephrology, Asklepios Klinikum Barmbek, Hamburg, Germany
| | - Henning Sievert
- Department of Oncology, Haematology and Bone Marrow Transplantation with Section Pneumology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Maja T Lindenmeyer
- Institute of Physiology and Division of Nephrology, University of Zurich, Switzerland
| | - Thorsten Wiech
- Department of Pathology, Division of Renal Pathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Clemens D Cohen
- Institute of Physiology and Division of Nephrology, University of Zurich, Switzerland
| | | | - R A K Stahl
- Department of Internal Medicine, Nephrology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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