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Zhu JY, Fu Y, van de Leemput J, Yu Y, Li J, Ray PE, Han Z. HIV-1 Nef acts in synergy with APOL1-G1 to induce nephrocyte cell death in a new Drosophila model of HIV-related kidney diseases. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.08.584069. [PMID: 38496548 PMCID: PMC10942446 DOI: 10.1101/2024.03.08.584069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Background: People carrying two APOL1 risk alleles (RA) G1 or G2 are at greater risk of developing HIV-associated nephropathy (HIVAN). Studies in transgenic mice showed that the expression of HIV-1 genes in podocytes, and nef in particular, led to HIVAN. However, it remains unclear whether APOL1-RA and HIV-1 Nef interact to induce podocyte cell death. Method: We generated transgenic (Tg) flies that express APOL1-G1 (derived from a child with HIVAN) and HIV-1 nef specifically in the nephrocytes, the fly equivalent of mammalian podocytes, and assessed their individual and combined effects on the nephrocyte filtration structure and function. Results: We found that HIV-1 Nef acts in synergy with APOL1-G1 resulting in nephrocyte structural and functional defects. Specifically, HIV-1 Nef itself can induce endoplasmic reticulum (ER) stress without affecting autophagy. Furthermore, Nef exacerbates the organelle acidification defects and autophagy reduction induced by APOL1-G1. The synergy between HIV-1 Nef and APOL1-G1 is built on their joint effects on elevating ER stress, triggering nephrocyte dysfunction and ultimately cell death. Conclusions: Using a new Drosophila model of HIV-1-related kidney diseases, we identified ER stress as the converging point for the synergy between HIV-1 Nef and APOL1-G1 in inducing nephrocyte cell death. Given the high relevance between Drosophila nephrocytes and human podocytes, this finding suggests ER stress as a new therapeutic target for HIV-1 and APOL1-associated nephropathies.
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Koehler S, Hengel FE, Dumoulin B, Damashek L, Holzman LB, Susztak K, Huber TB. The 14th International Podocyte Conference 2023: from podocyte biology to glomerular medicine. Kidney Int 2024; 105:935-952. [PMID: 38447880 DOI: 10.1016/j.kint.2024.01.042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 12/11/2023] [Accepted: 01/02/2024] [Indexed: 03/08/2024]
Abstract
The 14th International Podocyte Conference took place in Philadelphia, Pennsylvania, USA from May 23 to 26, 2023. It commenced with an early-career researchers' meeting on May 23, providing young scientists with a platform to present and discuss their research findings. Throughout the main conference, 29 speakers across 9 sessions shared their insights on podocyte biology, glomerular medicine, novel technologic advancements, and translational approaches. Additionally, the event featured 3 keynote lectures addressing engineered chimeric antigen receptor T cell- and mRNA-based therapies and the use of biobanks for enhanced disease comprehension. Furthermore, 4 brief oral abstract sessions allowed scientists to present their findings to a broad audience. The program also included a panel discussion addressing the challenges of conducting human research within the American Black community. Remarkably, after a 5-year hiatus from in-person conferences, the 14th International Podocyte Conference successfully convened scientists from around the globe, fostering the presentation and discussion of crucial research findings, as summarized in this review. Furthermore, to ensure continuous and sustainable education, research, translation, and trial medicine related to podocyte and glomerular diseases for the benefit of patients, the International Society of Glomerular Disease was officially launched during the conference.
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Affiliation(s)
- Sybille Koehler
- III. Department of Medicine and Hamburg Center for Kidney Health (HCKH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Felicitas E Hengel
- III. Department of Medicine and Hamburg Center for Kidney Health (HCKH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Bernhard Dumoulin
- III. Department of Medicine and Hamburg Center for Kidney Health (HCKH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany; Renal, Electrolyte, and Hypertension Division, Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Laurel Damashek
- International Society of Glomerular Disease, Florence, Massachusetts, USA
| | - Lawrence B Holzman
- Renal, Electrolyte, and Hypertension Division, Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Katalin Susztak
- Renal, Electrolyte, and Hypertension Division, Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA; Institute of Diabetes, Obesity and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA; Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Tobias B Huber
- III. Department of Medicine and Hamburg Center for Kidney Health (HCKH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany; International Society of Glomerular Disease, Florence, Massachusetts, USA.
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Duan J, Wen P, Zhao Y, van de Leemput J, Lai Yee J, Fermin D, Warady BA, Furth SL, Ng DK, Sampson MG, Han Z. A Drosophila model to screen Alport syndrome COL4A5 variants for their functional pathogenicity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.06.583697. [PMID: 38559272 PMCID: PMC10979928 DOI: 10.1101/2024.03.06.583697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Alport syndrome is a hereditary chronic kidney disease, attributed to rare pathogenic variants in either of three collagen genes (COL4A3/4/5) with most localized in COL4A5. Trimeric type IV Collagen α3α4α5 is essential for the glomerular basement membrane that forms the kidney filtration barrier. A means to functionally assess the many candidate variants and determine pathogenicity is urgently needed. We used Drosophila, an established model for kidney disease, and identify Col4a1 as the functional homolog of human COL4A5 in the fly nephrocyte (equivalent of human podocyte). Fly nephrocytes deficient for Col4a1 showed an irregular and thickened basement membrane and significantly reduced nephrocyte filtration function. This phenotype was restored by expressing human reference (wildtype) COL4A5, but not by COL4A5 carrying any of three established pathogenic patient-derived variants. We then screened seven additional patient COL4A5 variants; their ClinVar classification was either likely pathogenic or of uncertain significance. The findings support pathogenicity for four of these variants; the three others were found benign. Thus, demonstrating the effectiveness of this Drosophila in vivo kidney platform in providing the urgently needed variant-level functional validation.
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Affiliation(s)
- Jianli Duan
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, MD 21201, USA
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, MD 21201, USA
| | - Pei Wen
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, MD 21201, USA
| | - Yunpo Zhao
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, MD 21201, USA
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, MD 21201, USA
| | - Joyce van de Leemput
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, MD 21201, USA
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, MD 21201, USA
| | - Jennifer Lai Yee
- Division of Nephrology, Department of Pediatric, University of Michigan School of Medicine, Ann Arbor, MI 48105, USA
| | - Damian Fermin
- Division of Nephrology, Department of Internal Medicine, University of Michigan School of Medicine, Ann Arbor, MI 48105, USA
| | - Bradley A Warady
- Division of Pediatric Nephrology, Children’s Mercy Kansas City, Kansas City, MO 64108, USA
| | - Susan L Furth
- Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
- Division of Nephrology, Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Derek K Ng
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, MD 21205, USA
| | - Matthew G Sampson
- Division of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Boston, MA 02115, USA
- Harvard Medical School Boston, MA 02115, USA
- Kidney Disease Initiative, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Zhe Han
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, MD 21201, USA
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, MD 21201, USA
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Sachs W, Blume L, Loreth D, Schebsdat L, Hatje F, Koehler S, Wedekind U, Sachs M, Zieliniski S, Brand J, Conze C, Florea BI, Heppner F, Krüger E, Rinschen MM, Kretz O, Thünauer R, Meyer-Schwesinger C. The proteasome modulates endocytosis specifically in glomerular cells to promote kidney filtration. Nat Commun 2024; 15:1897. [PMID: 38429282 PMCID: PMC10907641 DOI: 10.1038/s41467-024-46273-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 02/16/2024] [Indexed: 03/03/2024] Open
Abstract
Kidney filtration is ensured by the interaction of podocytes, endothelial and mesangial cells. Immunoglobulin accumulation at the filtration barrier is pathognomonic for glomerular injury. The mechanisms that regulate filter permeability are unknown. Here, we identify a pivotal role for the proteasome in a specific cell type. Combining genetic and inhibitor-based human, pig, mouse, and Drosophila models we demonstrate that the proteasome maintains filtration barrier integrity, with podocytes requiring the constitutive and glomerular endothelial cells the immunoproteasomal activity. Endothelial immunoproteasome deficiency as well as proteasome inhibition disrupt the filtration barrier in mice, resulting in pathologic immunoglobulin deposition. Mechanistically, we observe reduced endocytic activity, which leads to altered membrane recycling and endocytic receptor turnover. This work expands the concept of the (immuno)proteasome as a control protease orchestrating protein degradation and antigen presentation and endocytosis, providing new therapeutic targets to treat disease-associated glomerular protein accumulations.
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Affiliation(s)
- Wiebke Sachs
- Institute of Cellular and Integrative Physiology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Hamburg Center of Kidney Health, Hamburg, Germany
| | - Lukas Blume
- Institute of Cellular and Integrative Physiology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Hamburg Center of Kidney Health, Hamburg, Germany
| | - Desiree Loreth
- Institute of Cellular and Integrative Physiology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Hamburg Center of Kidney Health, Hamburg, Germany
| | - Lisa Schebsdat
- Institute of Cellular and Integrative Physiology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Hamburg Center of Kidney Health, Hamburg, Germany
| | - Favian Hatje
- Institute of Cellular and Integrative Physiology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Hamburg Center of Kidney Health, Hamburg, Germany
| | - Sybille Koehler
- Hamburg Center of Kidney Health, Hamburg, Germany
- Nephrology, III Medical Clinic, Department of Internal Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Uta Wedekind
- Institute of Cellular and Integrative Physiology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Hamburg Center of Kidney Health, Hamburg, Germany
| | - Marlies Sachs
- Institute of Cellular and Integrative Physiology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Hamburg Center of Kidney Health, Hamburg, Germany
| | - Stephanie Zieliniski
- Institute of Cellular and Integrative Physiology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Hamburg Center of Kidney Health, Hamburg, Germany
| | - Johannes Brand
- Institute of Cellular and Integrative Physiology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Hamburg Center of Kidney Health, Hamburg, Germany
| | | | - Bogdan I Florea
- Bio-Organic Synthesis Group, Leiden University, Leiden, The Netherlands
| | - Frank Heppner
- Institute of Neuropathology, Charité, Berlin, Germany
| | - Elke Krüger
- Institute of Medical Biochemistry and Molecular Biology, University Medicine Greifswald, Greifswald, Germany
| | - Markus M Rinschen
- Hamburg Center of Kidney Health, Hamburg, Germany
- Nephrology, III Medical Clinic, Department of Internal Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Oliver Kretz
- Hamburg Center of Kidney Health, Hamburg, Germany
- Nephrology, III Medical Clinic, Department of Internal Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Roland Thünauer
- Leibniz Institute of Virology, Hamburg, Germany
- Technology Platform Light Microscopy (TPLM), University Hamburg, Hamburg, Germany
- Advanced Light and Fluorescence Microscopy (ALFM) Facility at the Centre for Structural Systems Biology (CSSB), Hamburg, Germany
| | - Catherine Meyer-Schwesinger
- Institute of Cellular and Integrative Physiology, Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
- Hamburg Center of Kidney Health, Hamburg, Germany.
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Xi G, Lamba SA, Mysh M, Poulton JS. Oxidative Stress Contributes to Slit Diaphragm Defects Caused by Disruption of Endocytosis. Kidney Int Rep 2024; 9:451-463. [PMID: 38344712 PMCID: PMC10851022 DOI: 10.1016/j.ekir.2023.11.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 10/27/2023] [Accepted: 11/20/2023] [Indexed: 03/04/2024] Open
Abstract
Introduction Podocyte slit diaphragms are an important component of the glomerular filtration barrier. Podocyte injury frequently includes defects in slit diaphragms, and various mechanisms for these defects have been described, including altered endocytic trafficking of slit diaphragm proteins or oxidative stress. However, the potential relationship between endocytosis and oxidative stress in the context of slit diaphragm integrity has not been extensively considered. Methods To examine the potential relationships between endocytosis, oxidative stress, and slit diaphragm integrity, we induced genetic or pharmacological disruption of endocytosis in Drosophila nephrocytes (the insect orthologue of podocytes) and cultured human podocytes. We then employed immunofluorescence microscopy to analyze protein localization and levels, and to quantify signal from reactive oxygen species (ROS) dyes. Immunoprecipitation from podocyte cell lysates was used to examine effects on slit diaphragm protein complex formation (i.e., nephrin/podocin and nephrin/ZO-1). Results Disruption of endocytosis in nephrocytes and podocytes led to slit diaphragm defects, elevated levels of ROS (oxidative stress), and activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant pathway. In nephrocytes with defective endocytosis, perturbation of Nrf2 signaling exacerbated slit diaphragm defects. Conversely, overexpression of Nrf2 target genes catalase or glucose-6-phosphate dehydrogenase (G6PD) significantly ameliorated slit diaphragm defects caused by disruption of endocytosis. Conclusion Oxidative stress is an important consequence of defective endocytosis and contributes to the defects in slit diaphragm integrity associated with disruption of endocytic trafficking.
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Affiliation(s)
- Gang Xi
- UNC Kidney Center, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Sajan A. Lamba
- UNC Kidney Center, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Michael Mysh
- UNC Kidney Center, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - John S. Poulton
- UNC Kidney Center, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Koehler S, Huber TB. Insights into human kidney function from the study of Drosophila. Pediatr Nephrol 2023; 38:3875-3887. [PMID: 37171583 PMCID: PMC10584755 DOI: 10.1007/s00467-023-05996-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 04/13/2023] [Accepted: 04/18/2023] [Indexed: 05/13/2023]
Abstract
Biological and biomedical research using Drosophila melanogaster as a model organism has gained recognition through several Nobel prizes within the last 100 years. Drosophila exhibits several advantages when compared to other in vivo models such as mice and rats, as its life cycle is very short, animal maintenance is easy and inexpensive and a huge variety of transgenic strains and tools are publicly available. Moreover, more than 70% of human disease-causing genes are highly conserved in the fruit fly. Here, we explain the use of Drosophila in nephrology research and describe two kidney tissues, Malpighian tubules and the nephrocytes. The latter are the homologous cells to mammalian glomerular podocytes and helped to provide insights into a variety of signaling pathways due to the high morphological similarities and the conserved molecular make-up between nephrocytes and podocytes. In recent years, nephrocytes have also been used to study inter-organ communication as links between nephrocytes and the heart, the immune system and the muscles have been described. In addition, other tissues such as the eye and the reproductive system can be used to study the functional role of proteins being part of the kidney filtration barrier.
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Affiliation(s)
- Sybille Koehler
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
- Hamburg Center for Kidney Health (HCKH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | - Tobias B Huber
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Hamburg Center for Kidney Health (HCKH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Hermle T, Simons M. ER stress and slit diaphragms: is there a connection? Kidney Int 2023; 103:830-832. [PMID: 37085254 DOI: 10.1016/j.kint.2023.01.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 01/19/2023] [Accepted: 01/27/2023] [Indexed: 04/23/2023]
Abstract
Galloway-Mowat syndrome is a neurorenal syndrome that has been linked with defective transfer RNA and protein translation caused by variants in the multiprotein complex KEOPS. In the kidney, this syndrome seems to primarily affect the podocytes, but the pathogenesis has remained unclear. In this issue of Kidney International, Krausel et al. use Drosophila nephrocytes to link endoplasmic reticulum stress with defects in the slit diaphragm.
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Affiliation(s)
- Tobias Hermle
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany.
| | - Matias Simons
- Section Nephrogenetics, Institute of Human Genetics, University Hospital Heidelberg, Heidelberg, Germany.
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Lassén E, Daehn IS. Insights into glomerular function and disease pathogenesis. Nat Rev Nephrol 2023; 19:85-86. [PMID: 36536248 PMCID: PMC10821748 DOI: 10.1038/s41581-022-00667-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
More than three-quarters of cases of chronic kidney disease are caused by glomerular diseases with glomerulosclerosis, including diabetic kidney disease, hypertensive nephropathy and glomerulonephritis. Studies in 2022 provided insights into the molecular mechanisms that maintain dynamic glomerular structures and the responses of specific glomerular cell types during glomerular disease.
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Affiliation(s)
- Emelie Lassén
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Ilse S Daehn
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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9
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Yu C, Zhang H, Liu S, Li R, Zhao X, Chen Y, Li Z, Ma J, Wang W, Ye Z, Liang X, Zhang L, Shi W. Flot2 acts as a novel mediator of podocyte injury in proteinuric kidney disease. Int J Biol Sci 2023; 19:502-520. [PMID: 36632460 PMCID: PMC9830511 DOI: 10.7150/ijbs.78945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 11/30/2022] [Indexed: 12/23/2022] Open
Abstract
Podocyte injury is a common hallmark of chronic kidney disease (CKD). The podocin-nephrin complex localized in lipid rafts of podocyte is vital to reduce podocyte injury and proteinuria, however, the mechanism underlying its localization remains unclear. This study uncovers an important role of Flot2 in stabilizing the podocin-nephrin complex localized in lipid rafts. We first confirmed that Flot2 was expressed in podocyte and demenstrated that podocyte-specific Flot2 deletion worsen albuminuria, podocyte injury and glomerular pathology in LPS/ADR-induced nephropathy mouse models. Meanwhile, podocyte injury, albuminuria and pathologic aberrance were prevented in podocyte-specific Flot2 overexpression transgenic mice when challenged with LPS or ADR. Further found that Flot2 was vital to recruit podocin and nephrin into rafts and ameliorated podocyte injury. Flot2 and podocin directly interacted with each other via their SPFH domain. Meanwhile, we also showed that Flot-2 is a direct target of Krüppel-like factor (KLF15). Importanly, we observed that Flot2 was downregulated in renal biopsies from patients with podocytopathies and its expression negatively correlated with proteinuria and positively correlated with eGFR, indicating that Flot2 may be a novel therapeutic target for proteinuric kidney disease.
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Affiliation(s)
- Chunping Yu
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China.,State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China
| | - Hong Zhang
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Shuangxin Liu
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Ruizhao Li
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Xingchen Zhao
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Yuanhan Chen
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Zhuo Li
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Jianchao Ma
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Wenjian Wang
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Zhiming Ye
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China
| | - Xinling Liang
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China.,✉ Corresponding authors: Xinling Liang, Li Zhang, or Wei Shi. Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China. E-mail: ; ; ; Phone: +86 13802793488; +86 13202067354; +86 13808819770; Fax: +86-20-83827812-62027
| | - Li Zhang
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China.,✉ Corresponding authors: Xinling Liang, Li Zhang, or Wei Shi. Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China. E-mail: ; ; ; Phone: +86 13802793488; +86 13202067354; +86 13808819770; Fax: +86-20-83827812-62027
| | - Wei Shi
- Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China.,Department of Nephrology, Gaozhou People's Hospital, Gaozhou, P. R. China.,✉ Corresponding authors: Xinling Liang, Li Zhang, or Wei Shi. Department of Nephrology, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, 106 Zhongshan No. 2 Road, Guangzhou, 510080, China. E-mail: ; ; ; Phone: +86 13802793488; +86 13202067354; +86 13808819770; Fax: +86-20-83827812-62027
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Drummond IA. Slit Diaphragms: Junctions That Never Sleep. J Am Soc Nephrol 2022; 33:2127-2128. [PMID: 36332973 PMCID: PMC9731622 DOI: 10.1681/asn.2022101147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Iain A. Drummond
- Davis Center for Aging and Regenerative Biology, MDI Biological Laboratory, Bar Harbor, Maine
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11
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Milosavljevic J, Lempicki C, Lang K, Heinkele H, Kampf LL, Leroy C, Chen M, Gerstner L, Spitz D, Wang M, Knob AU, Kayser S, Helmstädter M, Walz G, Pollak MR, Hermle T. Nephrotic Syndrome Gene TBC1D8B Is Required for Endosomal Maturation and Nephrin Endocytosis in Drosophila. J Am Soc Nephrol 2022; 33:2174-2193. [PMID: 36137753 PMCID: PMC9731638 DOI: 10.1681/asn.2022030275] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 09/01/2022] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Variants in TBC1D8B cause nephrotic syndrome. TBC1D8B is a GTPase-activating protein for Rab11 (RAB11-GAP) that interacts with nephrin, but how it controls nephrin trafficking or other podocyte functions remains unclear. METHODS We generated a stable deletion in Tbc1d8b and used microhomology-mediated end-joining for genome editing. Ex vivo functional assays utilized slit diaphragms in podocyte-like Drosophila nephrocytes. Manipulation of endocytic regulators and transgenesis of murine Tbc1d8b provided a comprehensive functional analysis of Tbc1d8b. RESULTS A null allele of Drosophila TBC1D8B exhibited a nephrocyte-restricted phenotype of nephrin mislocalization, similar to patients with isolated nephrotic syndrome who have variants in the gene. The protein was required for rapid nephrin turnover in nephrocytes and for endocytosis of nephrin induced by excessive Rab5 activity. The protein expressed from the Tbc1d8b locus bearing the edited tag predominantly localized to mature early and late endosomes. Tbc1d8b was required for endocytic cargo processing and degradation. Silencing Hrs, a regulator of endosomal maturation, phenocopied loss of Tbc1d8b. Low-level expression of murine TBC1D8B rescued loss of the Drosophila gene, indicating evolutionary conservation. Excessive murine TBC1D8B selectively disturbed nephrin dynamics. Finally, we discovered four novel TBC1D8B variants within a cohort of 363 patients with FSGS and validated a functional effect of two variants in Drosophila, suggesting a personalized platform for TBC1D8B-associated FSGS. CONCLUSIONS Variants in TBC1D8B are not infrequent among patients with FSGS. TBC1D8B, functioning in endosomal maturation and degradation, is essential for nephrin trafficking.
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Affiliation(s)
- Julian Milosavljevic
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Camille Lempicki
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Konrad Lang
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Helena Heinkele
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Lina L. Kampf
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Claire Leroy
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Mengmeng Chen
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Lea Gerstner
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Dominik Spitz
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Minxian Wang
- Division of Nephrology, Beth Israel Deaconess Medical Center, Boston, Massachusetts
- Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Andrea U. Knob
- Division of Nephrology, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Séverine Kayser
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Martin Helmstädter
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
| | - Gerd Walz
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
- CIBSS–Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Martin R. Pollak
- Division of Nephrology, Beth Israel Deaconess Medical Center, Boston, Massachusetts
- Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Tobias Hermle
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany
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12
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Liu PJ, Gunther LK, Garone ME, Zhang C, Perez D, Bi-Karchin J, Pellenz CD, Chase SE, Presti MF, Plante EL, Martin CE, Lovric S, Yengo CM, Hildebrandt F, Krendel M. Steroid-Resistant Nephrotic Syndrome-Associated MYO1E Mutations Have Differential Effects on Myosin 1e Localization, Dynamics, and Activity. J Am Soc Nephrol 2022; 33:1989-2007. [PMID: 36316095 PMCID: PMC9678034 DOI: 10.1681/asn.2021111505] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 08/22/2022] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Myo1e is a nonmuscle motor protein enriched in podocytes. Mutations in MYO1E are associated with steroid-resistant nephrotic syndrome (SRNS). Most of the MYO1E variants identified by genomic sequencing have not been functionally characterized. Here, we set out to analyze two mutations in the Myo1e motor domain, T119I and D388H, which were selected on the basis of protein sequence conservation. METHODS EGFP-tagged human Myo1e constructs were delivered into the Myo1e-KO mouse podocyte-derived cells via adenoviral infection to analyze Myo1e protein stability, Myo1e localization, and clathrin-dependent endocytosis, which is known to involve Myo1e activity. Furthermore, truncated Myo1e constructs were expressed using the baculovirus expression system and used to measure Myo1e ATPase and motor activity in vitro. RESULTS Both mutants were expressed as full-length proteins in the Myo1e-KO cells. However, unlike wild-type (WT) Myo1e, the T119I variant was not enriched at the cell junctions or clathrin-coated vesicles (CCVs). In contrast, D388H variant localization was similar to that of WT. The rate of dissociation of the D388H variant from cell-cell junctions and CCVs was decreased, suggesting this mutation affects Myo1e interactions with binding partners. ATPase activity and ability to translocate actin filaments were drastically reduced for the D388H mutant, supporting findings from cell-based experiments. CONCLUSIONS T119I and D388H mutations are deleterious to Myo1e functions. The experimental approaches used in this study can be applied to future characterization of novel MYO1E variants associated with SRNS.
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Affiliation(s)
- Pei-Ju Liu
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Laura K. Gunther
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, Hershey, Pennsylvania
| | - Michael E. Garone
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Chunling Zhang
- Department of Neuroscience and Physiology, State University of New York Upstate Medical University, Syracuse, New York
| | - Diana Perez
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Jing Bi-Karchin
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Christopher D. Pellenz
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Sharon E. Chase
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Maria F. Presti
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Eric L. Plante
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
| | - Claire E. Martin
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Sinai Health System, Toronto, Ontario, Canada
| | - Svjetlana Lovric
- Divison of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Christopher M. Yengo
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, Hershey, Pennsylvania
| | - Friedhelm Hildebrandt
- Divison of Nephrology, Department of Pediatrics, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Mira Krendel
- Department of Cell and Developmental Biology, State University of New York Upstate Medical University, Syracuse, New York
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13
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Wang M. In vivo slit diaphragm dynamics in Drosophila. Nat Rev Nephrol 2022; 18:605. [PMID: 36028617 DOI: 10.1038/s41581-022-00626-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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