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Castillo-Mancho V, Atienza-Manuel A, Sarmiento-Jiménez J, Ruiz-Gómez M, Culi J. Phospholipid scramblase 1: an essential component of the nephrocyte slit diaphragm. Cell Mol Life Sci 2024; 81:261. [PMID: 38878170 DOI: 10.1007/s00018-024-05287-z] [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: 12/14/2023] [Revised: 05/03/2024] [Accepted: 05/20/2024] [Indexed: 06/29/2024]
Abstract
Blood ultrafiltration in nephrons critically depends on specialized intercellular junctions between podocytes, named slit diaphragms (SDs). Here, by studying a homologous structure found in Drosophila nephrocytes, we identify the phospholipid scramblase Scramb1 as an essential component of the SD, uncovering a novel link between membrane dynamics and SD formation. In scramb1 mutants, SDs fail to form. Instead, the SD components Sticks and stones/nephrin, Polychaetoid/ZO-1, and the Src-kinase Src64B/Fyn associate in cortical foci lacking the key SD protein Dumbfounded/NEPH1. Scramb1 interaction with Polychaetoid/ZO-1 and Flotillin2, the presence of essential putative palmitoylation sites and its capacity to oligomerize, suggest a function in promoting SD assembly within lipid raft microdomains. Furthermore, Scramb1 interactors as well as its functional sensitivity to temperature, suggest an active involvement in membrane remodeling processes during SD assembly. Remarkably, putative Ca2+-binding sites in Scramb1 are essential for its activity raising the possibility that Ca2+ signaling may control the assembly of SDs by impacting on Scramb1 activity.
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Affiliation(s)
- Vicente Castillo-Mancho
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Nicolás Cabrera 1, Cantoblanco, Madrid, 28049, Spain
| | - Alexandra Atienza-Manuel
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Nicolás Cabrera 1, Cantoblanco, Madrid, 28049, Spain
| | - Jorge Sarmiento-Jiménez
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Nicolás Cabrera 1, Cantoblanco, Madrid, 28049, Spain
| | - Mar Ruiz-Gómez
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Nicolás Cabrera 1, Cantoblanco, Madrid, 28049, Spain.
| | - Joaquim Culi
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Nicolás Cabrera 1, Cantoblanco, Madrid, 28049, Spain.
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2
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Leroy C, Lang K, Spitz D, Milosavljevic J, Heinkele H, Kayser S, Helmstädter M, Walz G, Ulbrich MH, Hermle T. Linking Basement Membrane and Slit Diaphragm in Drosophila Nephrocytes. J Am Soc Nephrol 2024:00001751-990000000-00329. [PMID: 38776165 DOI: 10.1681/asn.0000000000000400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 05/17/2024] [Indexed: 05/24/2024] Open
Abstract
Key Points
Drosophila nephrocytes feature a special basement membrane that may serve to model joint function of the glomerular filtration barrier.Silencing of Drosophila laminin and collagen IV genes reduced the density of slit diaphragms in nephrocytes, showing a direct effect of the matrix.Matrix receptor silencing phenocopied basement membrane disruption, indicating that the matrix guides slit diaphragm position through matrix receptors.
Background
The glomerular basement membrane and the slit diaphragm are essential parts of the filtration barrier. How these layers collaborate remains unclear. The podocyte-like nephrocytes in Drosophila harbor both a slit diaphragm and a basement membrane, serving as a model to address this critical question.
Methods
Basement membrane components and matrix receptors were silenced using RNA interference in nephrocytes. Slit diaphragms were analyzed using immunofluorescence, followed by automated quantification. Tracer endocytosis was applied for functional readouts.
Results
Immunofluorescence indicated a significant reduction in slit diaphragm density upon loss of laminin and collagen IV components. This was accompanied by reduced expression of fly nephrin and shallower membrane invaginations. Tracer studies revealed that the basement membrane defines properties of the nephrocyte filtration barrier. Acute enzymatic disruption of the basement membrane via collagenase rapidly caused slit diaphragm mislocalization and disintegration, which was independent of cell death. Loss of matrix-interacting receptors, particularly integrins mys and mew, phenocopied basement membrane disruption. Integrins and nephrin colocalized at the slit diaphragm in nephrocytes in a mutually dependent manner, interacting genetically. Human integrin α3 interacted physically with nephrin.
Conclusions
The glomerular basement membrane model in Drosophila nephrocytes reveals that matrix receptor–mediated cues ensure correct positioning of the slit diaphragm and the overall filtration barrier architecture.
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Grants
- HE 7456/4-1, HE 7456/7-1, and project-ID 431984000 â€" SFB 1453 Deutsche Forschungsgemeinschaft
- HE 7456/6-1 Deutsche Forschungsgemeinschaft
- HE 7456/4-1, HE 7456/7-1, and project-ID 431984000 - SFB 1453 Deutsche Forschungsgemeinschaft
- HE 7456/4-1, HE 7456/7-1, and project-ID 431984000 - SFB 1453 Deutsche Forschungsgemeinschaft
- HE 7456/4-1, HE 7456/7-1, and project-ID 431984000 - SFB 1453 Deutsche Forschungsgemeinschaft
- HE 7456/4-1, HE 7456/7-1, and project-ID 431984000 - SFB 1453 Deutsche Forschungsgemeinschaft
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Affiliation(s)
- Claire Leroy
- 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
| | - Dominik Spitz
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
| | - Julian Milosavljevic
- 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
| | - Séverine Kayser
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
- EMcore, Renal Division, Department of Medicine, University Hospital Freiburg, University Faculty of Medicine, Freiburg, Germany
| | - Martin Helmstädter
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
- EMcore, Renal Division, Department of Medicine, University Hospital Freiburg, University Faculty of Medicine, 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, Freiburg, Germany
| | - Maximilian H Ulbrich
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Tobias Hermle
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center - University of Freiburg, Freiburg, Germany
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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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4
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Zhu H, Ludington WB, Spradling AC. Cellular and molecular organization of the Drosophila foregut. Proc Natl Acad Sci U S A 2024; 121:e2318760121. [PMID: 38442150 PMCID: PMC10945768 DOI: 10.1073/pnas.2318760121] [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: 11/03/2023] [Accepted: 01/23/2024] [Indexed: 03/07/2024] Open
Abstract
The animal foregut is the first tissue to encounter ingested food, bacteria, and viruses. We characterized the adult Drosophila foregut using transcriptomics to better understand how it triages consumed items for digestion or immune response and manages resources. Cell types were assigned and validated using GFP-tagged and Gal4 reporter lines. Foregut-associated neuroendocrine cells play a major integrative role by coordinating gut activity with nutrition, the microbiome, and circadian cycles; some express clock genes. Multiple epithelial cell types comprise the proventriculus, the central foregut organ that secretes the peritrophic matrix (PM) lining the gut. Analyzing cell types synthesizing individual PM layers revealed abundant mucin production close to enterocytes, similar to the mammalian intestinal mucosa. The esophagus and salivary gland express secreted proteins likely to line the esophageal surface, some of which may generate a foregut commensal niche housing specific gut microbiome species. Overall, our results imply that the foregut coordinates dietary sensing, hormonal regulation, and immunity in a manner that has been conserved during animal evolution.
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Affiliation(s)
- Haolong Zhu
- Biosphere Sciences and Engineering, Carnegie Institution for Science, Baltimore, MD21218
- Department of Biology, Johns Hopkins University, Baltimore, MD21218
| | - William B. Ludington
- Biosphere Sciences and Engineering, Carnegie Institution for Science, Baltimore, MD21218
- Department of Biology, Johns Hopkins University, Baltimore, MD21218
| | - Allan C. Spradling
- Biosphere Sciences and Engineering, Carnegie Institution for Science, Baltimore, MD21218
- Department of Biology, Johns Hopkins University, Baltimore, MD21218
- HHMI, Baltimore, MD21218
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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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Reynolds CJ, Gillen CM, Burke R, Tsering Y, Loucks E, Judd-Mole S, Dow JA, Romero MF. Drosophila ClC-c Is a Homolog of Human CLC-5 and a New Model for Dent Disease Type 1. KIDNEY360 2024; 5:414-426. [PMID: 38233994 PMCID: PMC11000744 DOI: 10.34067/kid.0000000000000352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 01/04/2024] [Indexed: 01/19/2024]
Abstract
Key Points Drosophila can be a model for Dent Disease type 1. Drosophila Clc-C mutations function similar to human CLC-5 Dent 1 mutations. Background Drosophila serve as exceptional alternative models for in vivo and ex vivo research and may provide an avenue for in-depth investigation for human ClC-5 and Dent disease type 1 (DD1). The Drosophila ClC-c (CG5284) has sequence homology with human ClC-5 and is hypothesized to encompass similar functional and phenotypical roles with ClC-5 and variants that cause DD1. Methods Ion transport function and activity of Drosophila ClC-c and homologous DD1 variants were assessed by voltage clamp electrophysiology. Membrane localization was demonstrated in Drosophila expressing a GFP-labeled construct of ClC-c. Genetic expression of an RNAi against ClC-c mRNA was used to generate a knockdown fly that serves as a DD1 disease model. Tubule secretion of cations and protein were assessed, as well as the crystal formation in the Malpighian tubules. Results Voltage clamp experiments demonstrate that ClC-c is voltage-gated with Cl−-dependent and pH-sensitive currents. Inclusion of homologous DD1 mutations pathogenic variants (S393L, R494W, and Q777X) impairs ClC-c ion transport activity. In vivo expression of ClC-c-eGFP in Malpighian tubules reveals that the membrane transporter localizes to the apical membrane and nearby cytosolic regions. RNAi knockdown of ClC-c (48% decreased mRNA expression) causes increased secretion of both urinary protein and Ca2+ and increased occurrence of spontaneous tubule crystals. Conclusions Drosophila ClC-c shows orthologous function and localization to human ClC-5. Thus, Drosophila and ClC-c regulation may be useful for future investigations of Cl− transport, Ca2+ homeostasis, and urinary protein loss in DD1.
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Affiliation(s)
- Carmen J. Reynolds
- Physiology & Biomedical Engineering, Mayo Clinic College of Medicine & Science, Rochester, Minnesota
| | | | - Richard Burke
- School of Biological Sciences, Monash University, Melbourne, Victoria, Australia
| | - Yula Tsering
- Physiology & Biomedical Engineering, Mayo Clinic College of Medicine & Science, Rochester, Minnesota
- University of Minnesota-Rochester, Rochester, Minnesota
| | - Emi Loucks
- Department of Biology, Kenyon College, Gambier, Ohio
| | - Sebastian Judd-Mole
- School of Biological Sciences, Monash University, Melbourne, Victoria, Australia
| | - Julian A.T. Dow
- School of Molecular Biosciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Michael F. Romero
- Physiology & Biomedical Engineering, Mayo Clinic College of Medicine & Science, Rochester, Minnesota
- Nephrology and Hypertension, Mayo Clinic College of Medicine & Science, Rochester, Minnesota
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7
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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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8
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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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9
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Carrasco-Rando M, Culi J, Campuzano S, Ruiz-Gómez M. An acytokinetic cell division creates PIP2-enriched membrane asymmetries leading to slit diaphragm assembly in Drosophila nephrocytes. Development 2023; 150:dev201708. [PMID: 37681291 PMCID: PMC10546876 DOI: 10.1242/dev.201708] [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: 02/16/2023] [Accepted: 08/31/2023] [Indexed: 09/09/2023]
Abstract
Vertebrate podocytes and Drosophila nephrocytes display slit diaphragms, specialised cell junctions that are essential for the execution of the basic excretory function of ultrafiltration. To elucidate the mechanisms of slit diaphragm assembly we have studied their formation in Drosophila embryonic garland nephrocytes. These cells of mesenchymal origin lack overt apical-basal polarity. We find that their initial membrane symmetry is broken by an acytokinetic cell division that generates PIP2-enriched domains at their equator. The PIP2-enriched equatorial cortex becomes a favourable domain for hosting slit diaphragm proteins and the assembly of the first slit diaphragms. Indeed, when this division is either prevented or forced to complete cytokinesis, the formation of diaphragms is delayed to larval stages. Furthermore, although apical polarity determinants also accumulate at the equatorial cortex, they do not appear to participate in the recruitment of slit diaphragm proteins. The mechanisms we describe allow the acquisition of functional nephrocytes in embryos, which may confer on them a biological advantage similar to the formation of the first vertebrate kidney, the pronephros.
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Affiliation(s)
- Marta Carrasco-Rando
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Nicolás Cabrera 1, Cantoblanco 28049, Madrid, Spain
| | - Joaquim Culi
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Nicolás Cabrera 1, Cantoblanco 28049, Madrid, Spain
| | - Sonsoles Campuzano
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Nicolás Cabrera 1, Cantoblanco 28049, Madrid, Spain
| | - Mar Ruiz-Gómez
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Nicolás Cabrera 1, Cantoblanco 28049, Madrid, Spain
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10
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Kılıç K, Topuz D. The evaluation of potentially toxic elements using artificial neural networks and fuzzy linear regression analysis methods in cappadocian volcanic ash soils of Turkey. Heliyon 2023; 9:e19448. [PMID: 37681186 PMCID: PMC10481309 DOI: 10.1016/j.heliyon.2023.e19448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 08/09/2023] [Accepted: 08/23/2023] [Indexed: 09/09/2023] Open
Abstract
The aim of this study is to determine the relationships between some potentially toxic elements (PTE) (Cu, Mn, Ni, Zn) in human stomach and intestinal tissues and toxic element contents in soil, vegetables and fruits. This study was conducted in the eastern of Erciyes Strato volcano, an area of 2400 km2 in Turkey. Tissue samples taken from the stomach and intestines of people living in the study area, soils, vegetables, and fruits were used as material. In the study, tissue samples of 26 people's stomach and intestines, 576 soil samples from 192 points and 3 different depths (0-30 cm, 30-60 cm, and 60-90 cm) and vegetable and fruit samples from 137 sampling points were taken. Cu, Mn, Ni, and Zn contents of human tissue samples, soil samples, vegetable and fruit samples were determined. Artificial Neural Networks method (ANN) and Fuzzy Linear Regression Analysis (FLRA) methods were used to determine the relationships between PTE contents in human tissue samples and soils, vegetables, and fruits. Root Mean squared error (RMSE) and coefficient of determination (R2) indices were used as the test criteria for goodness of fit. When compared with ANN method, it was determined that PTE values in stomach and intestinal tissue estimated by FLRA method had the lowest error and high R2 values. It was found that the most effective variable in estimating the average PTE value in stomach and intestinal tissue is PTE values in soil. It was determined that the FLRA regression analysis method has a better predictive power than the ANN method. Using FLRA and ANN regression methods, it was determined that there is a statistically high relationship between PTE contents in soils and stomach and intestinal tissues. It is recommended to make the study findings more meaningful with effective and reliable service planning by using different regression analysis methods in ecological and clinical studies.
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Affiliation(s)
- Kenan Kılıç
- Department of Environmental Engineering, Engineering Faculty, Niğde Ömer Halisdemir University, 51240, Niğde, Turkey
| | - Derviş Topuz
- Department of Health Services Science, Niğde Zübeyde Hanım Vocational School of Health Services, Niğde Ömer Halisdemir University, 51200, Niğde, Turkey
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11
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Maruzs T, Feil-Börcsök D, Lakatos E, Juhász G, Blastyák A, Hargitai D, Jean S, Lőrincz P, Juhász G. Interaction of the sorting nexin 25 homologue Snazarus with Rab11 balances endocytic and secretory transport and maintains the ultrafiltration diaphragm in nephrocytes. Mol Biol Cell 2023; 34:ar87. [PMID: 37314856 PMCID: PMC10398886 DOI: 10.1091/mbc.e22-09-0421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 06/05/2023] [Accepted: 06/06/2023] [Indexed: 06/15/2023] Open
Abstract
Proper balance of exocytosis and endocytosis is important for the maintenance of plasma membrane lipid and protein homeostasis. This is especially critical in human podocytes and the podocyte-like Drosophila nephrocytes that both use a delicate diaphragm system with evolutionarily conserved components for ultrafiltration. Here, we show that the sorting nexin 25 homologue Snazarus (Snz) binds to Rab11 and localizes to Rab11-positive recycling endosomes in Drosophila nephrocytes, unlike in fat cells where it is present in plasma membrane/lipid droplet/endoplasmic reticulum contact sites. Loss of Snz leads to redistribution of Rab11 vesicles from the cell periphery and increases endocytic activity in nephrocytes. These changes are accompanied by defects in diaphragm protein distribution that resemble those seen in Rab11 gain-of-function cells. Of note, co-overexpression of Snz rescues diaphragm defects in Rab11 overexpressing cells, whereas snz knockdown in Rab11 overexpressing nephrocytes or simultaneous knockdown of snz and tbc1d8b encoding a Rab11 GTPase-activating protein (GAP) leads to massive expansion of the lacunar system that contains mislocalized diaphragm components: Sns and Pyd/ZO-1. We find that loss of Snz enhances while its overexpression impairs secretion, which, together with genetic epistasis analyses, suggest that Snz counteracts Rab11 to maintain the diaphragm via setting the proper balance of exocytosis and endocytosis.
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Affiliation(s)
- Tamás Maruzs
- Institute of Genetics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, H-6726 Hungary
| | - Dalma Feil-Börcsök
- Institute of Genetics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, H-6726 Hungary
- Doctoral School of Biology, University of Szeged, Szeged, H-6726 Hungary
| | - Enikő Lakatos
- Institute of Genetics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, H-6726 Hungary
- Doctoral School of Biology, University of Szeged, Szeged, H-6726 Hungary
| | - Gábor Juhász
- Institute of Genetics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, H-6726 Hungary
| | - András Blastyák
- Institute of Genetics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, H-6726 Hungary
| | - Dávid Hargitai
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, H-1117 Hungary
| | - Steve Jean
- Department of Anatomy and Cell Biology, University of Sherbrooke, Sherbrooke, J1E 4K8 Canada
| | - Péter Lőrincz
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, H-1117 Hungary
| | - Gábor Juhász
- Institute of Genetics, Biological Research Centre, Eötvös Loránd Research Network, Szeged, H-6726 Hungary
- Department of Anatomy, Cell and Developmental Biology, Eötvös Loránd University, Budapest, H-1117 Hungary
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12
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Gilhaus K, Cepok C, Kamm D, Surmann B, Nedvetsky PI, Emich J, Sundukova A, Saatkamp K, Nüsse H, Klingauf J, Wennmann DO, George B, Krahn MP, Pavenstädt HJ, Vollenbröker BA. Activation of Hippo Pathway Damages Slit Diaphragm by Deprivation of Ajuba Proteins. J Am Soc Nephrol 2023; 34:1039-1055. [PMID: 36930055 PMCID: PMC10278832 DOI: 10.1681/asn.0000000000000107] [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: 07/22/2022] [Accepted: 02/06/2023] [Indexed: 03/18/2023] Open
Abstract
SIGNIFICANCE STATEMENT Nuclear exclusion of the cotranscription factor YAP, which is a consequence of activation of the Hippo signaling pathway, leads to FSGS and podocyte apoptosis. Ajuba proteins play an important role in the glomerular filtration barrier by keeping the Hippo pathway inactive. In nephrocytes from Drosophila melanogaster , a well-established model system for podocyte research, Ajuba proteins ensure slit diaphragm (SD) formation and function. Hippo pathway activation leads to mislocalization of Ajuba proteins, decreased SD formation, rearrangement of the actin cytoskeleton, and increased SD permeability. Targeting the kinases of the Hippo pathway with specific inhibitors in the glomerulus could, therefore, be a promising strategy for therapy of FSGS. BACKGROUND The highly conserved Hippo pathway, which regulates organ growth and cell proliferation by inhibiting transcriptional cofactors YAP/TAZ, plays a special role in podocytes, where activation of the pathway leads to apoptosis. The Ajuba family proteins (Ajuba, LIM domain-containing protein 1 (LIMD1) and Wilms tumor protein 1-interacting protein [WTIP]) can bind and inactivate large tumor suppressor kinases 1 and 2, (LATS1/2) two of the Hippo pathway key kinases. WTIP, furthermore, connects the slit diaphragm (SD), the specialized cell-cell junction between podocytes, with the actin cytoskeleton. METHODS We used garland cell nephrocytes of Drosophila melanogaster to monitor the role of Ajuba proteins in Hippo pathway regulation and structural integrity of the SD. Microscopy and functional assays analyzed the interplay between Ajuba proteins and LATS2 regarding expression, localization, interaction, and effects on the functionality of the SD. RESULTS In nephrocytes, the Ajuba homolog Djub recruited Warts (LATS2 homolog) to the SD. Knockdown of Djub activated the Hippo pathway. Reciprocally, Hippo activation reduced the Djub level. Both Djub knockdown and Hippo activation led to morphological changes in the SD, rearrangement of the cortical actin cytoskeleton, and increased SD permeability. Knockdown of Warts or overexpression of constitutively active Yki prevented these effects. In podocytes, Hippo pathway activation or knockdown of YAP also decreased the level of Ajuba proteins. CONCLUSIONS Ajuba proteins regulate the structure and function of the SD in nephrocytes, connecting the SD protein complex to the actin cytoskeleton and maintaining the Hippo pathway in an inactive state. Hippo pathway activation directly influencing Djub expression suggests a self-amplifying feedback mechanism.
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Affiliation(s)
- Kevin Gilhaus
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - Claudia Cepok
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - David Kamm
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - Beate Surmann
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - Pavel I. Nedvetsky
- Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - Jana Emich
- Institute of Reproductive Genetics, University Hospital of Münster, Münster, Germany
| | - Alina Sundukova
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - Katharina Saatkamp
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - Harald Nüsse
- Institute of Medical Physics and Biophysics, Westfälische-Wilhelms University Münster, Münster, Germany
| | - Jürgen Klingauf
- Institute of Medical Physics and Biophysics, Westfälische-Wilhelms University Münster, Münster, Germany
| | - Dirk O. Wennmann
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - Britta George
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | - Michael P. Krahn
- Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Münster, Germany
| | | | - Beate A. Vollenbröker
- Molecular Nephrology, Medical Clinic D, University Hospital of Münster, Münster, Germany
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13
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Krausel V, Pund L, Nüsse H, Bachir H, Ricker A, Klingauf J, Weide T, Pavenstädt H, Krahn MP, Braun DA. The transcription factor ATF4 mediates endoplasmic reticulum stress-related podocyte injury and slit diaphragm defects. Kidney Int 2022; 103:872-885. [PMID: 36587794 DOI: 10.1016/j.kint.2022.11.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Revised: 10/25/2022] [Accepted: 11/17/2022] [Indexed: 12/30/2022]
Abstract
Mutations in OSGEP and four other genes that encode subunits of the KEOPS complex cause Galloway-Mowat syndrome, a severe, inherited kidney-neurological disease. The complex catalyzes an essential posttranscriptional modification of tRNA and its loss of function induces endoplasmic reticulum (ER) stress. Here, using Drosophila melanogaster garland nephrocytes and cultured human podocytes, we aimed to elucidate the molecular pathogenic mechanisms of KEOPS-related glomerular disease and to test pharmacological inhibition of ER stress-related signaling as a therapeutic principle. We found that ATF4, an ER stress-mediating transcription factor, or its fly orthologue Crc, were upregulated in both fly nephrocytes and human podocytes. Knockdown of Tcs3, a fly orthologue of OSGEP, caused slit diaphragm defects, recapitulating the human kidney phenotype. OSGEP cDNA with mutations found in patients lacked the capacity for rescue. Genetic interaction studies in Tcs3-deficient nephrocytes revealed that Crc mediates not only cell injury, but surprisingly also slit diaphragm defects, and that genetic or pharmacological inhibition of Crc activation attenuates both phenotypes. These findings are conserved in human podocytes where ATF4 inhibition improved the viability of podocytes with OSGEP knockdown, with chemically induced ER stress, and where ATF4 target genes and pro-apoptotic gene clusters are upregulated upon OSGEP knockdown. Thus, our data identify ATF4-mediated signaling as a molecular link among ER stress, slit diaphragm defects, and podocyte injury, and our data suggest that modulation of ATF4 signaling may be a potential therapeutic target for certain podocyte diseases.
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Affiliation(s)
- Vanessa Krausel
- Department D of Internal Medicine, University Hospital of Munster, Munster, Germany
| | - Lisanne Pund
- Department D of Internal Medicine, University Hospital of Munster, Munster, Germany
| | - Harald Nüsse
- Institute of Medical Physics and Biophysics, University of Munster, Munster, Germany
| | - Hussein Bachir
- Department D of Internal Medicine, University Hospital of Munster, Munster, Germany
| | - Andrea Ricker
- Institute of Medical Physics and Biophysics, University of Munster, Munster, Germany
| | - Jürgen Klingauf
- Institute of Medical Physics and Biophysics, University of Munster, Munster, Germany
| | - Thomas Weide
- Department D of Internal Medicine, University Hospital of Munster, Munster, Germany
| | - Hermann Pavenstädt
- Department D of Internal Medicine, University Hospital of Munster, Munster, Germany
| | - Michael P Krahn
- Department D of Internal Medicine, University Hospital of Munster, Munster, Germany
| | - Daniela A Braun
- Department D of Internal Medicine, University Hospital of Munster, Munster, Germany.
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14
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Sivakumar S, Miellet S, Clarke C, Hartley PS. Insect nephrocyte function is regulated by a store operated calcium entry mechanism controlling endocytosis and Amnionless turnover. JOURNAL OF INSECT PHYSIOLOGY 2022; 143:104453. [PMID: 36341969 DOI: 10.1016/j.jinsphys.2022.104453] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/22/2022] [Accepted: 10/21/2022] [Indexed: 05/26/2023]
Abstract
Insect nephrocytes are ultrafiltration cells that remove circulating proteins and exogenous toxins from the haemolymph. Experimental disruption of nephrocyte development or function leads to systemic impairment of insect physiology as evidenced by cardiomyopathy, chronic activation of immune signalling and shortening of lifespan. The genetic and structural basis of the nephrocyte's ultrafiltration mechanism is conserved between arthropods and mammals, making them an attractive model for studying human renal function and systemic clearance mechanisms in general. Although dynamic changes to intracellular calcium are fundamental to the function of many cell types, there are currently no studies of intracellular calcium signalling in nephrocytes. In this work we aimed to characterise calcium signalling in the pericardial nephrocytes of Drosophila melanogaster. To achieve this, a genetically encoded calcium reporter (GCaMP6) was expressed in nephrocytes to monitor intracellular calcium both in vivo within larvae and in vitro within dissected adults. Larval nephrocytes exhibited stochastically timed calcium waves. A calcium signal could be initiated in preparations of adult nephrocytes and abolished by EGTA, or the store operated calcium entry (SOCE) blocker 2-APB, as well as RNAi mediated knockdown of the SOCE genes Stim and Orai. Neither the presence of calcium-free buffer nor EGTA affected the binding of the endocytic cargo albumin to nephrocytes but they did impair the subsequent accumulation of albumin within nephrocytes. Pre-treatment with EGTA, calcium-free buffer or 2-APB led to significantly reduced albumin binding. Knock-down of Stim and Orai was non-lethal, caused an increase to nephrocyte size and reduced albumin binding, reduced the abundance of the endocytic cargo receptor Amnionless and disrupted the localisation of Dumbfounded at the filtration slit diaphragm. These data indicate that pericardial nephrocytes exhibit stochastically timed calcium waves in vivo and that SOCE mediates the localisation of the endocytic co-receptor Amnionless. Identifying the signals both up and downstream of SOCE may highlight mechanisms relevant to the renal and excretory functions of a broad range of species, including humans.
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Affiliation(s)
- Shruthi Sivakumar
- Department of Life and Environmental Sciences, Faculty of Science and Technology, Bournemouth University, Dorset BH12 5BB, UK
| | - Sara Miellet
- Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia; Molecular Horizons, University of Wollongong, NSW, Australia
| | - Charlotte Clarke
- Department of Life and Environmental Sciences, Faculty of Science and Technology, Bournemouth University, Dorset BH12 5BB, UK
| | - Paul S Hartley
- Department of Life and Environmental Sciences, Faculty of Science and Technology, Bournemouth University, Dorset BH12 5BB, UK.
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15
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Bierzynska A, Bull K, Miellet S, Dean P, Neal C, Colby E, McCarthy HJ, Hegde S, Sinha MD, Bugarin Diz C, Stirrups K, Megy K, Mapeta R, Penkett C, Marsh S, Forrester N, Afzal M, Stark H, BioResource NIHR, Williams M, Welsh GI, Koziell AB, Hartley PS, Saleem MA. Exploring the relevance of NUP93 variants in steroid-resistant nephrotic syndrome using next generation sequencing and a fly kidney model. Pediatr Nephrol 2022; 37:2643-2656. [PMID: 35211795 PMCID: PMC9489583 DOI: 10.1007/s00467-022-05440-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 12/10/2021] [Accepted: 12/21/2021] [Indexed: 10/24/2022]
Abstract
BACKGROUND Variants in genes encoding nuclear pore complex (NPC) proteins are a newly identified cause of paediatric steroid-resistant nephrotic syndrome (SRNS). Recent reports describing NUP93 variants suggest these could be a significant cause of paediatric onset SRNS. We report NUP93 cases in the UK and demonstrate in vivo functional effects of Nup93 depletion in a fly (Drosophila melanogaster) nephrocyte model. METHODS Three hundred thirty-seven paediatric SRNS patients from the National cohort of patients with Nephrotic Syndrome (NephroS) were whole exome and/or whole genome sequenced. Patients were screened for over 70 genes known to be associated with Nephrotic Syndrome (NS). D. melanogaster Nup93 knockdown was achieved by RNA interference using nephrocyte-restricted drivers. RESULTS Six novel homozygous and compound heterozygous NUP93 variants were detected in 3 sporadic and 2 familial paediatric onset SRNS characterised histologically by focal segmental glomerulosclerosis (FSGS) and progressing to kidney failure by 12 months from clinical diagnosis. Silencing of the two orthologs of human NUP93 expressed in D. melanogaster, Nup93-1, and Nup93-2 resulted in significant signal reduction of up to 82% in adult pericardial nephrocytes with concomitant disruption of NPC protein expression. Additionally, nephrocyte morphology was highly abnormal in Nup93-1 and Nup93-2 silenced flies surviving to adulthood. CONCLUSION We expand the spectrum of NUP93 variants detected in paediatric onset SRNS and demonstrate its incidence within a national cohort. Silencing of either D. melanogaster Nup93 ortholog caused a severe nephrocyte phenotype, signaling an important role for the nucleoporin complex in podocyte biology. A higher resolution version of the Graphical abstract is available as Supplementary information.
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Affiliation(s)
- Agnieszka Bierzynska
- Bristol Renal and Children’s Renal Unit, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY UK
| | - Katherine Bull
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Sara Miellet
- Department of Life and Environmental Science, Bournemouth University, Talbot Campus, Fern Barrow, Poole, Dorset BH12 5BB England, UK
- Illawarra Health and Medical Research Institute, Molecular Horizons and School of Medicine, University of Wollongong, Wollongong, Australia
| | - Philip Dean
- Bristol Genetics Laboratory, North Bristol National Health Service Trust, Bristol, UK
| | - Chris Neal
- Bristol Renal and Children’s Renal Unit, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY UK
| | - Elizabeth Colby
- Bristol Renal and Children’s Renal Unit, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY UK
| | - Hugh J. McCarthy
- Bristol Renal and Children’s Renal Unit, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY UK
- School of Medicine, University of Sydney and Children’s Hospital at Westmead, Westmead, Australia
| | - Shivaram Hegde
- Children’s Kidney Centre, University Hospital of Wales, Cardiff, UK
| | - Manish D. Sinha
- Department of Paediatric Nephrology, Evelina London Children’s Hospital, Guy’s and St, Thomas’ Hospital, London, UK
| | - Carmen Bugarin Diz
- School of Immunology and Microbial Sciences, Faculty of Life Sciences and Medicine, King’s College London, London, SE1 7EH UK
| | - Kathleen Stirrups
- NIHR BioResource, Cambridge University Hospitals, Cambridge Biomedical Campus, Cambridge, CB2 0QQ UK
| | - Karyn Megy
- NIHR BioResource, Cambridge University Hospitals, Cambridge Biomedical Campus, Cambridge, CB2 0QQ UK
- Centre for Genomics Research, Discovery Sciences, BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | - Rutendo Mapeta
- NIHR BioResource, Cambridge University Hospitals, Cambridge Biomedical Campus, Cambridge, CB2 0QQ UK
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA UK
| | - Chris Penkett
- NIHR BioResource, Cambridge University Hospitals, Cambridge Biomedical Campus, Cambridge, CB2 0QQ UK
| | - Sarah Marsh
- Bristol Genetics Laboratory, North Bristol National Health Service Trust, Bristol, UK
| | - Natalie Forrester
- Illawarra Health and Medical Research Institute, Molecular Horizons and School of Medicine, University of Wollongong, Wollongong, Australia
| | - Maryam Afzal
- Bristol Renal and Children’s Renal Unit, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY UK
| | - Hannah Stark
- NIHR BioResource, Cambridge University Hospitals, Cambridge Biomedical Campus, Cambridge, CB2 0QQ UK
| | - NIHR BioResource
- NIHR BioResource, Cambridge University Hospitals, Cambridge Biomedical Campus, Cambridge, CB2 0QQ UK
| | - Maggie Williams
- Bristol Genetics Laboratory, North Bristol National Health Service Trust, Bristol, UK
| | - Gavin I. Welsh
- Bristol Renal and Children’s Renal Unit, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY UK
| | - Ania B. Koziell
- Department of Paediatric Nephrology, Evelina London Children’s Hospital, Guy’s and St, Thomas’ Hospital, London, UK
- School of Immunology and Microbial Sciences, Faculty of Life Sciences and Medicine, King’s College London, London, SE1 7EH UK
| | - Paul S. Hartley
- Department of Life and Environmental Science, Bournemouth University, Talbot Campus, Fern Barrow, Poole, Dorset BH12 5BB England, UK
| | - Moin A. Saleem
- Bristol Renal and Children’s Renal Unit, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY UK
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16
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Odenthal J, Dittrich S, Ludwig V, Merz T, Reitmeier K, Reusch B, Höhne M, Cosgun ZC, Hohenadel M, Putnik J, Göbel H, Rinschen MM, Altmüller J, Koehler S, Schermer B, Benzing T, Beck BB, Brinkkötter PT, Habbig S, Bartram MP. Modeling of ACTN4-Based Podocytopathy Using Drosophila Nephrocytes. Kidney Int Rep 2022; 8:317-329. [PMID: 36815115 PMCID: PMC9939316 DOI: 10.1016/j.ekir.2022.10.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/17/2022] [Accepted: 10/24/2022] [Indexed: 11/06/2022] Open
Abstract
Introduction Genetic disorders are among the most prevalent causes leading to progressive glomerular disease and, ultimately, end-stage renal disease (ESRD) in children and adolescents. Identification of underlying genetic causes is indispensable for targeted treatment strategies and counseling of affected patients and their families. Methods Here, we report on a boy who presented at 4 years of age with proteinuria and biopsy-proven focal segmental glomerulosclerosis (FSGS) that was temporarily responsive to treatment with ciclosporin A. Molecular genetic testing identified a novel mutation in alpha-actinin-4 (p.M240T). We describe a feasible and efficient experimental approach to test its pathogenicity by combining in silico, in vitro, and in vivo analyses. Results The de novo p.M240T mutation led to decreased alpha-actinin-4 stability as well as protein mislocalization and actin cytoskeleton rearrangements. Transgenic expression of wild-type human alpha-actinin-4 in Drosophila melanogaster nephrocytes was able to ameliorate phenotypes associated with the knockdown of endogenous actinin. In contrast, p.M240T, as well as other established disease variants p.W59R and p.K255E, failed to rescue these phenotypes, underlining the pathogenicity of the novel alpha-actinin-4 variant. Conclusion Our data highlight that the newly identified alpha-actinin-4 mutation indeed encodes for a disease-causing variant of the protein and promote the Drosophila model as a simple and convenient tool to study monogenic kidney disease in vivo.
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Affiliation(s)
- Johanna Odenthal
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Sebastian Dittrich
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Vivian Ludwig
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Tim Merz
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Katrin Reitmeier
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Björn Reusch
- Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany,Institute of Human Genetics, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Martin Höhne
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Zülfü C. Cosgun
- Department of Pediatrics, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Maximilian Hohenadel
- Department of Pediatrics, Division of Pediatric Nephrology, University of Bonn, Bonn, Germany
| | - Jovana Putnik
- Mother and Child Health Care Institute of Serbia “Dr Vukan Čupić,” Department of Nephrology, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Heike Göbel
- Institute of Pathology, University Hospital of Cologne, Cologne, Germany
| | - Markus M. Rinschen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark,Aarhus Institute of Advanced Studies, Aarhus University, Aarhus, Denmark,III Medical Clinic, University Hospital Hamburg Eppendorf, Hamburg, Germany
| | - Janine Altmüller
- Berlin Institute of Health at Charité-Universitätsmedizin Berlin, Max Delbrück Center for Molecular Medicine, Berlin, Germany,Cologne Center for Genomics, University of Cologne, Cologne, Germany
| | - Sybille Koehler
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Bernhard Schermer
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Thomas Benzing
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Bodo B. Beck
- Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany,Institute of Human Genetics, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Paul T. Brinkkötter
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany,Correspondence: Paul T. Brinkkoetter, Department II of Internal Medicine, Faculty of Medicine, University of Cologne, University Hospital Cologne, Kerpener Street 62, Cologne 50935, Germany.
| | - Sandra Habbig
- Department of Pediatrics, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
| | - Malte P. Bartram
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, Faculty of Medicine, University of Cologne, University Hospital Cologne, Cologne, Germany
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17
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Meyer C, Breitsprecher L, Bataille L, Vincent AJM, Drechsler M, Meyer H, Paululat A. Formation and function of a highly specialised type of organelle in cardiac valve cells. Development 2022; 149:276991. [DOI: 10.1242/dev.200701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 08/23/2022] [Indexed: 11/06/2022]
Abstract
ABSTRACT
Within a cell, vesicles play a crucial role in the transport of membrane material and proteins to a given target membrane, and thus regulate a variety of cellular functions. Vesicular transport occurs by means of, among others, endocytosis, where cargoes are taken up by the cell and are processed further upon vesicular trafficking, i.e. transported back to the plasma membrane via recycling endosomes or the degraded by fusion of the vesicles with lysosomes. During evolution, a variety of vesicles with individual functions arose, with some of them building up highly specialised subcellular compartments. In this study, we have analysed the biosynthesis of a new vesicular compartment present in the valve cells of Drosophila melanogaster. We show that the compartment is formed by invaginations of the plasma membrane and grows via re-routing of the recycling endosomal pathway. This is achieved by inactivation of other membrane-consuming pathways and a plasma membrane-like molecular signature of the compartment in these highly specialised heart cells.
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Affiliation(s)
- Christian Meyer
- University of Osnabrück 1 , Department of Biology and Chemistry, Zoology and Developmental Biology, Barbarastraße 11, 49076 Osnabrück , Germany
| | - Leonhard Breitsprecher
- University of Osnabrück 1 , Department of Biology and Chemistry, Zoology and Developmental Biology, Barbarastraße 11, 49076 Osnabrück , Germany
- Center of Cellular Nanoanalytics (CellNanOs), integrated Bioimaging Facility (iBiOs), University of Osnabrück 2 , Barbarastrasse 11, 49076 Osnabrück , Germany
| | - Laetitia Bataille
- Unité de Biologie Moléculaire et Cellulaire et du Développement (MCD), Centre de Biologie Intégrative (CBI) 3 , Université de Toulouse UMR 5077/CNRS, F-31062 Toulouse , France
| | - Alain J. M. Vincent
- Unité de Biologie Moléculaire et Cellulaire et du Développement (MCD), Centre de Biologie Intégrative (CBI) 3 , Université de Toulouse UMR 5077/CNRS, F-31062 Toulouse , France
| | - Maik Drechsler
- University of Osnabrück 1 , Department of Biology and Chemistry, Zoology and Developmental Biology, Barbarastraße 11, 49076 Osnabrück , Germany
| | - Heiko Meyer
- University of Osnabrück 1 , Department of Biology and Chemistry, Zoology and Developmental Biology, Barbarastraße 11, 49076 Osnabrück , Germany
- Center of Cellular Nanoanalytics (CellNanOs), integrated Bioimaging Facility (iBiOs), University of Osnabrück 2 , Barbarastrasse 11, 49076 Osnabrück , Germany
| | - Achim Paululat
- University of Osnabrück 1 , Department of Biology and Chemistry, Zoology and Developmental Biology, Barbarastraße 11, 49076 Osnabrück , Germany
- Center of Cellular Nanoanalytics (CellNanOs), integrated Bioimaging Facility (iBiOs), University of Osnabrück 2 , Barbarastrasse 11, 49076 Osnabrück , Germany
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18
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Koehler S, Huber TB, Denholm B. A protective role for <i>Drosophila</i> Filamin in nephrocytes via Yorkie mediated hypertrophy. Life Sci Alliance 2022; 5:e202101281. [PMID: 35922155 PMCID: PMC9351128 DOI: 10.26508/lsa.202101281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 07/15/2022] [Accepted: 07/18/2022] [Indexed: 11/24/2022] Open
Abstract
Podocytes are specialized epithelial cells of the kidney glomerulus and are an essential part of the filtration barrier. Because of their position, they are exposed to constant biomechanical forces such as shear stress and hydrostatic pressure. These forces increase during disease, resulting in podocyte injury. It is likely podocytes have adaptative responses to help buffer against deleterious mechanical force and thus reduce injury. However, these responses remain largely unknown. Here, using the <i>Drosophila</i> model, we show the mechanosensor Cheerio (dFilamin) provides a key protective role in nephrocytes. We found expression of an activated mechanosensitive variant of Cheerio rescued filtration function and induced compensatory and hypertrophic growth in nephrocytes depleted of the nephrocyte diaphragm proteins Sns or Duf. Delineating the protective pathway downstream of Cheerio we found repression of the Hippo pathway induces nephrocyte hypertrophy, whereas Hippo activation reversed the Cheerio-mediated hypertrophy. Furthermore, we find Yorkie was activated upon expression of active Cheerio. Taken together, our data suggest that Cheerio acts via the Hippo pathway to induce hypertrophic growth, as a protective response in abnormal nephrocytes.
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Affiliation(s)
- Sybille Koehler
- Biomedical Sciences, University of Edinburgh, Edinburgh, UK
- III Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tobias B Huber
- III Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Barry Denholm
- Biomedical Sciences, University of Edinburgh, Edinburgh, UK
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19
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Lang K, Milosavljevic J, Heinkele H, Chen M, Gerstner L, Spitz D, Kayser S, Helmstädter M, Walz G, Köttgen M, Spracklen A, Poulton J, Hermle T. Selective endocytosis controls slit diaphragm maintenance and dynamics in Drosophila nephrocytes. eLife 2022; 11:79037. [PMID: 35876643 PMCID: PMC9355562 DOI: 10.7554/elife.79037] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 07/24/2022] [Indexed: 11/28/2022] Open
Abstract
The kidneys generate about 180 l of primary urine per day by filtration of plasma. An essential part of the filtration barrier is the slit diaphragm, a multiprotein complex containing nephrin as major component. Filter dysfunction typically manifests with proteinuria and mutations in endocytosis regulating genes were discovered as causes of proteinuria. However, it is unclear how endocytosis regulates the slit diaphragm and how the filtration barrier is maintained without either protein leakage or filter clogging. Here, we study nephrin dynamics in podocyte-like nephrocytes of Drosophila and show that selective endocytosis either by dynamin- or flotillin-mediated pathways regulates a stable yet highly dynamic architecture. Short-term manipulation of endocytic functions indicates that dynamin-mediated endocytosis of ectopic nephrin restricts slit diaphragm formation spatially while flotillin-mediated turnover of nephrin within the slit diaphragm is needed to maintain filter permeability by shedding of molecules bound to nephrin in endosomes. Since slit diaphragms cannot be studied in vitro and are poorly accessible in mouse models, this is the first analysis of their dynamics within the slit diaphragm multiprotein complex. Identification of the mechanisms of slit diaphragm maintenance will help to develop novel therapies for proteinuric renal diseases that are frequently limited to symptomatic treatment.
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Affiliation(s)
- Konrad Lang
- Department of Medicine, University of Freiburg, Freiburg, Germany
| | | | - Helena Heinkele
- Department of Medicine, University of Freiburg, Freiburg, Germany
| | - Mengmeng Chen
- Department of Medicine, University of Freiburg, Freiburg, Germany
| | - Lea Gerstner
- Department of Medicine, University of Freiburg, Freiburg, Germany
| | - Dominik Spitz
- Department of Medicine, University of Freiburg, Freiburg, Germany
| | - Severine Kayser
- Department of Medicine, University of Freiburg, Freiburg, Germany
| | | | - Gerd Walz
- Department of Medicine, University of Freiburg, Freiburg, Germany
| | - Michael Köttgen
- Department of Medicine, University of Freiburg, Freiburg, Germany
| | - Andrew Spracklen
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - John Poulton
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Tobias Hermle
- Department of Medicine, University of Freiburg, Freiburg, Germany
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20
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Spitz D, Comas M, Gerstner L, Kayser S, Helmstädter M, Walz G, Hermle T. mTOR-Dependent Autophagy Regulates Slit Diaphragm Density in Podocyte-like Drosophila Nephrocytes. Cells 2022; 11:cells11132103. [PMID: 35805186 PMCID: PMC9265458 DOI: 10.3390/cells11132103] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 06/24/2022] [Accepted: 06/28/2022] [Indexed: 02/04/2023] Open
Abstract
Both mTOR signaling and autophagy are important modulators of podocyte homeostasis, regeneration, and aging and have been implicated in glomerular diseases. However, the mechanistic role of these pathways for the glomerular filtration barrier remains poorly understood. We used Drosophila nephrocytes as an established podocyte model and found that inhibition of mTOR signaling resulted in increased spacing between slit diaphragms. Gain-of-function of mTOR signaling did not affect spacing, suggesting that additional cues limit the maximal slit diaphragm density. Interestingly, both activation and inhibition of mTOR signaling led to decreased nephrocyte function, indicating that a fine balance of signaling activity is needed for proper function. Furthermore, mTOR positively controlled cell size, survival, and the extent of the subcortical actin network. We also showed that basal autophagy in nephrocytes is required for survival and limits the expression of the sns (nephrin) but does not directly affect slit diaphragm formation or endocytic activity. However, using a genetic rescue approach, we demonstrated that excessive, mTOR-dependent autophagy is primarily responsible for slit diaphragm misspacing. In conclusion, we established this invertebrate podocyte model for mechanistic studies on the role of mTOR signaling and autophagy, and we discovered a direct mTOR/autophagy-dependent regulation of the slit diaphragm architecture.
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Affiliation(s)
- Dominik Spitz
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, 79106 Freiburg, Germany; (D.S.); (L.G.); (S.K.); (M.H.); (G.W.)
| | - Maria Comas
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, 79106 Freiburg, Germany; (D.S.); (L.G.); (S.K.); (M.H.); (G.W.)
- Correspondence: (M.C.); (T.H.); Tel.: +49-0761-270-63046 (M.C.); +49-761-270-33630 (T.H.)
| | - Lea Gerstner
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, 79106 Freiburg, Germany; (D.S.); (L.G.); (S.K.); (M.H.); (G.W.)
| | - Séverine Kayser
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, 79106 Freiburg, Germany; (D.S.); (L.G.); (S.K.); (M.H.); (G.W.)
| | - Martin Helmstädter
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, 79106 Freiburg, Germany; (D.S.); (L.G.); (S.K.); (M.H.); (G.W.)
| | - Gerd Walz
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, 79106 Freiburg, Germany; (D.S.); (L.G.); (S.K.); (M.H.); (G.W.)
- CIBSS—Centre for Integrative Biological Signalling Studies, 79106 Freiburg, Germany
| | - Tobias Hermle
- Renal Division, Department of Medicine, Faculty of Medicine and Medical Center, University of Freiburg, 79106 Freiburg, Germany; (D.S.); (L.G.); (S.K.); (M.H.); (G.W.)
- Correspondence: (M.C.); (T.H.); Tel.: +49-0761-270-63046 (M.C.); +49-761-270-33630 (T.H.)
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21
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Dow JAT, Simons M, Romero MF. Drosophila melanogaster: a simple genetic model of kidney structure, function and disease. Nat Rev Nephrol 2022; 18:417-434. [PMID: 35411063 DOI: 10.1038/s41581-022-00561-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/07/2022] [Indexed: 12/27/2022]
Abstract
Although the genetic basis of many kidney diseases is being rapidly elucidated, their experimental study remains problematic owing to the lack of suitable models. The fruitfly Drosophila melanogaster provides a rapid, ethical and cost-effective model system of the kidney. The unique advantages of D. melanogaster include ease and low cost of maintenance, comprehensive availability of genetic mutants and powerful transgenic technologies, and less onerous regulation, as compared with mammalian systems. Renal and excretory functions in D. melanogaster reside in three main tissues - the transporting renal (Malpighian) tubules, the reabsorptive hindgut and the endocytic nephrocytes. Tubules contain multiple cell types and regions and generate a primary urine by transcellular transport rather than filtration, which is then subjected to selective reabsorption in the hindgut. By contrast, the nephrocytes are specialized for uptake of macromolecules and equipped with a filtering slit diaphragm resembling that of podocytes. Many genes with key roles in the human kidney have D. melanogaster orthologues that are enriched and functionally relevant in fly renal tissues. This similarity has allowed investigations of epithelial transport, kidney stone formation and podocyte and proximal tubule function. Furthermore, a range of unique quantitative phenotypes are available to measure function in both wild type and disease-modelling flies.
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Affiliation(s)
- Julian A T Dow
- Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
| | - Matias Simons
- INSERM UMR1163, Laboratory of Epithelial Biology and Disease, Imagine Institute, Université de Paris, Hôpital Necker-Enfants Malades, Paris, France
- Institute of Human Genetics, University Hospital Heidelberg, Heidelberg, Germany
| | - Michael F Romero
- Department of Physiology and Biomedical Engineering, Division of Nephrology and Hypertension, Mayo Clinic College of Medicine and Science, Rochester, MN, USA
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22
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Xu J, Liu Y, Li H, Tarashansky AJ, Kalicki CH, Hung RJ, Hu Y, Comjean A, Kolluru SS, Wang B, Quake SR, Luo L, McMahon AP, Dow JAT, Perrimon N. Transcriptional and functional motifs defining renal function revealed by single-nucleus RNA sequencing. Proc Natl Acad Sci U S A 2022; 119:e2203179119. [PMID: 35696569 PMCID: PMC9231607 DOI: 10.1073/pnas.2203179119] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 05/11/2022] [Indexed: 01/09/2023] Open
Abstract
Recent advances in single-cell sequencing provide a unique opportunity to gain novel insights into the diversity, lineage, and functions of cell types constituting a tissue/organ. Here, we performed a single-nucleus study of the adult Drosophila renal system, consisting of Malpighian tubules and nephrocytes, which shares similarities with the mammalian kidney. We identified 11 distinct clusters representing renal stem cells, stellate cells, regionally specific principal cells, garland nephrocyte cells, and pericardial nephrocytes. Characterization of the transcription factors specific to each cluster identified fruitless (fru) as playing a role in stem cell regeneration and Hepatocyte nuclear factor 4 (Hnf4) in regulating glycogen and triglyceride metabolism. In addition, we identified a number of genes, including Rho guanine nucleotide exchange factor at 64C (RhoGEF64c), Frequenin 2 (Frq2), Prip, and CG1093 that are involved in regulating the unusual star shape of stellate cells. Importantly, the single-nucleus dataset allows visualization of the expression at the organ level of genes involved in ion transport and junctional permeability, providing a systems-level view of the organization and physiological roles of the tubules. Finally, a cross-species analysis allowed us to match the fly kidney cell types to mouse kidney cell types and planarian protonephridia, knowledge that will help the generation of kidney disease models. Altogether, our study provides a comprehensive resource for studying the fly kidney.
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Affiliation(s)
- Jun Xu
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115
| | - Yifang Liu
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115
| | - Hongjie Li
- Department of Biology, Stanford University, Stanford, CA 94305
- HHMI, Stanford University, Stanford, CA 94305
| | - Alexander J. Tarashansky
- Department of Bioengineering, Stanford University, Stanford, CA 94305
- Chan Zuckerberg Biohub, San Francisco, CA 94158
| | - Colin H. Kalicki
- Department of Bioengineering, Stanford University, Stanford, CA 94305
| | - Ruei-Jiun Hung
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115
| | - Yanhui Hu
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115
| | - Aram Comjean
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115
| | - Sai Saroja Kolluru
- Department of Bioengineering, Stanford University, Stanford, CA 94305
- Chan Zuckerberg Biohub, San Francisco, CA 94158
| | - Bo Wang
- Department of Bioengineering, Stanford University, Stanford, CA 94305
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA 94305
| | - Stephen R. Quake
- Department of Bioengineering, Stanford University, Stanford, CA 94305
- Chan Zuckerberg Biohub, San Francisco, CA 94158
| | - Liqun Luo
- Department of Biology, Stanford University, Stanford, CA 94305
- HHMI, Stanford University, Stanford, CA 94305
| | - Andrew P. McMahon
- Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, Keck School of Medicine of the University of Southern California, Los Angeles, CA 90089
| | - Julian A. T. Dow
- Institute of Molecular, Cell & Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Norbert Perrimon
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Harvard University, Boston, MA 02115
- HHMI, Harvard University, Boston, MA 02115
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23
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PI(4,5)P2 controls slit diaphragm formation and endocytosis in Drosophila nephrocytes. Cell Mol Life Sci 2022; 79:248. [PMID: 35437696 PMCID: PMC9016003 DOI: 10.1007/s00018-022-04273-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 03/01/2022] [Accepted: 03/24/2022] [Indexed: 12/03/2022]
Abstract
Drosophila nephrocytes are an emerging model system for mammalian podocytes and proximal tubules as well as for the investigation of kidney diseases. Like podocytes, nephrocytes exhibit characteristics of epithelial cells, but the role of phospholipids in polarization of these cells is yet unclear. In epithelia, phosphatidylinositol(4,5)bisphosphate (PI(4,5)P2) and phosphatidylinositol(3,4,5)-trisphosphate (PI(3,4,5)P3) are asymmetrically distributed in the plasma membrane and determine apical–basal polarity. Here, we demonstrate that both phospholipids are present in the plasma membrane of nephrocytes, but only PI(4,5)P2 accumulates at slit diaphragms. Knockdown of Skittles, a phosphatidylinositol(4)phosphate 5-kinase, which produces PI(4,5)P2, abolished slit diaphragm formation and led to strongly reduced endocytosis. Notably, reduction in PI(3,4,5)P3 by overexpression of PTEN or expression of a dominant-negative phosphatidylinositol-3-kinase did not affect nephrocyte function, whereas enhanced formation of PI(3,4,5)P3 by constitutively active phosphatidylinositol-3-kinase resulted in strong slit diaphragm and endocytosis defects by ectopic activation of the Akt/mTOR pathway. Thus, PI(4,5)P2 but not PI(3,4,5)P3 is essential for slit diaphragm formation and nephrocyte function. However, PI(3,4,5)P3 has to be tightly controlled to ensure nephrocyte development.
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24
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Bali N, Lee HK(P, Zinn K. Sticks and Stones, a conserved cell surface ligand for the Type IIa RPTP Lar, regulates neural circuit wiring in Drosophila. eLife 2022; 11:e71469. [PMID: 35356892 PMCID: PMC9000958 DOI: 10.7554/elife.71469] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 03/31/2022] [Indexed: 11/13/2022] Open
Abstract
Type IIa receptor-like protein tyrosine phosphatases (RPTPs) are essential for neural development. They have cell adhesion molecule (CAM)-like extracellular domains that interact with cell-surface ligands and coreceptors. We identified the immunoglobulin superfamily CAM Sticks and Stones (Sns) as a new partner for the Drosophila Type IIa RPTP Lar. Lar and Sns bind to each other in embryos and in vitro, and the human Sns ortholog, Nephrin, binds to human Type IIa RPTPs. Genetic analysis shows that Lar and Sns function together to regulate larval neuromuscular junction development, axon guidance in the mushroom body (MB), and innervation of the optic lobe (OL) medulla by R7 photoreceptors. In the neuromuscular system, Lar and Sns are both required in motor neurons, and may function as coreceptors. In the MB and OL, however, the relevant Lar-Sns interactions are in trans (between neurons), so Sns functions as a Lar ligand in these systems.
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Affiliation(s)
- Namrata Bali
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
| | - Hyung-Kook (Peter) Lee
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
| | - Kai Zinn
- Division of Biology and Biological Engineering, California Institute of TechnologyPasadenaUnited States
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25
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Maywald ML, Picciotto C, Lepa C, Bertgen L, Yousaf FS, Ricker A, Klingauf J, Krahn MP, Pavenstädt H, George B. Rap1 Activity Is Essential for Focal Adhesion and Slit Diaphragm Integrity. Front Cell Dev Biol 2022; 10:790365. [PMID: 35372328 PMCID: PMC8972170 DOI: 10.3389/fcell.2022.790365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 02/24/2022] [Indexed: 11/24/2022] Open
Abstract
Glomerular podocytes build, with their intercellular junctions, part of the kidney filter. The podocyte cell adhesion protein, nephrin, is essential for developing and maintaining slit diaphragms as functional loss in humans results in heavy proteinuria. Nephrin expression and function are also altered in many adult-onset glomerulopathies. Nephrin signals from the slit diaphragm to the actin cytoskeleton and integrin β1 at focal adhesions by recruiting Crk family proteins, which can interact with the Rap guanine nucleotide exchange factor 1 C3G. As Rap1 activity affects focal adhesion formation, we hypothesize that nephrin signals via Rap1 to integrin β. To address this issue, we combined Drosophila in vivo and mammalian cell culture experiments. We find that Rap1 is necessary for correct targeting of integrin β to focal adhesions in Drosophila nephrocytes, which also form slit diaphragm-like structures. In the fly, the Rap1 activity is important for signaling of the nephrin ortholog to integrin β, as well as for nephrin-dependent slit diaphragm integrity. We show by genetic interaction experiments that Rap1 functions downstream of nephrin signaling to integrin β and downstream of nephrin signaling necessary for slit diaphragm integrity. Similarly, in human podocyte culture, nephrin activation results in increased activation of Rap1. Thus, Rap1 is necessary for downstream signal transduction of nephrin to integrin β.
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Affiliation(s)
- Mee-Ling Maywald
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | - Cara Picciotto
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | - Carolin Lepa
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | - Luisa Bertgen
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
| | | | - Andrea Ricker
- Institute of Medical Physics and Biophysics, Westfälische Wilhelms-University Münster, Münster, Germany
| | - Jürgen Klingauf
- Institute of Medical Physics and Biophysics, Westfälische Wilhelms-University Münster, Münster, Germany
| | - Michael P. Krahn
- Medizinische Klinik D, Medical Cell Biology, University Hospital Münster, Münster, Germany
| | | | - Britta George
- Medizinische Klinik D, University Hospital Münster, Münster, Germany
- *Correspondence: Britta George,
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26
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van de Leemput J, Wen P, Han Z. Using Drosophila Nephrocytes to Understand the Formation and Maintenance of the Podocyte Slit Diaphragm. Front Cell Dev Biol 2022; 10:837828. [PMID: 35265622 PMCID: PMC8898902 DOI: 10.3389/fcell.2022.837828] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 02/01/2022] [Indexed: 12/12/2022] Open
Abstract
The podocyte slit diaphragm (SD) is an essential component of the glomerular filtration barrier and its disruption is a common cause of proteinuria and many types of kidney disease. Therefore, better understanding of the pathways and proteins that play key roles in SD formation and maintenance has been of great interest. Podocyte and SD biology have been mainly studied using mouse and other vertebrate models. However, vertebrates are limited by inherent properties and technically challenging in vivo access to the podocytes. Drosophila is a relatively new alternative model system but it has already made great strides. Past the initial obvious differences, mammalian podocytes and fly nephrocytes are remarkably similar at the genetic, molecular and functional levels. This review discusses SD formation and maintenance, and their dependence on cell polarity, the cytoskeleton, and endo- and exocytosis, as learned from studies in fly nephrocytes and mammalian podocytes. In addition, it reflects on the remaining gaps in our knowledge, the physiological implications for glomerular diseases and how we can leverage the advantages Drosophila has to offer to further our understanding.
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Affiliation(s)
- Joyce van de Leemput
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, United States.,Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Pei Wen
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, United States.,Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Zhe Han
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, United States.,Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, United States
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27
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Morin-Poulard I, Destalminil-Letourneau M, Bataillé L, Frendo JL, Lebreton G, Vanzo N, Crozatier M. Identification of Bipotential Blood Cell/Nephrocyte Progenitors in Drosophila: Another Route for Generating Blood Progenitors. Front Cell Dev Biol 2022; 10:834720. [PMID: 35237606 PMCID: PMC8883574 DOI: 10.3389/fcell.2022.834720] [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: 12/13/2021] [Accepted: 01/24/2022] [Indexed: 11/13/2022] Open
Abstract
The Drosophila lymph gland is the larval hematopoietic organ and is aligned along the anterior part of the cardiovascular system, composed of cardiac cells, that form the cardiac tube and its associated pericardial cells or nephrocytes. By the end of embryogenesis the lymph gland is composed of a single pair of lobes. Two additional pairs of posterior lobes develop during larval development to contribute to the mature lymph gland. In this study we describe the ontogeny of lymph gland posterior lobes during larval development and identify the genetic basis of the process. By lineage tracing we show here that each posterior lobe originates from three embryonic pericardial cells, thus establishing a bivalent blood cell/nephrocyte potential for a subset of embryonic pericardial cells. The posterior lobes of L3 larvae posterior lobes are composed of heterogeneous blood progenitors and their diversity is progressively built during larval development. We further establish that in larvae, homeotic genes and the transcription factor Klf15 regulate the choice between blood cell and nephrocyte fates. Our data underline the sequential production of blood cell progenitors during larval development.
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Affiliation(s)
- Ismaël Morin-Poulard
- Unité de Biologie Moléculaire et Cellulaire et du Développement (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse UMR 5077/CNRS, Toulouse, France
| | - Manon Destalminil-Letourneau
- Unité de Biologie Moléculaire et Cellulaire et du Développement (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse UMR 5077/CNRS, Toulouse, France
| | - Laetitia Bataillé
- Unité de Biologie Moléculaire et Cellulaire et du Développement (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse UMR 5077/CNRS, Toulouse, France.,CNRS, INSERM, IGDR (Institut de Génétique et Développement de Rennes), UMR6290, ERL U1305, Rennes, France
| | - Jean-Louis Frendo
- Unité de Biologie Moléculaire et Cellulaire et du Développement (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse UMR 5077/CNRS, Toulouse, France.,INSERM U1301, CNRS 5070, Université de Toulouse, Toulouse, France
| | - Gaëlle Lebreton
- Unité de Biologie Moléculaire et Cellulaire et du Développement (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse UMR 5077/CNRS, Toulouse, France
| | - Nathalie Vanzo
- Unité de Biologie Moléculaire et Cellulaire et du Développement (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse UMR 5077/CNRS, Toulouse, France
| | - Michèle Crozatier
- Unité de Biologie Moléculaire et Cellulaire et du Développement (MCD), Centre de Biologie Intégrative (CBI), Université de Toulouse UMR 5077/CNRS, Toulouse, France
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28
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Phenotyping of Drosophila melanogaster—A Nutritional Perspective. Biomolecules 2022; 12:biom12020221. [PMID: 35204721 PMCID: PMC8961528 DOI: 10.3390/biom12020221] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/15/2022] [Accepted: 01/20/2022] [Indexed: 02/01/2023] Open
Abstract
The model organism Drosophila melanogaster was increasingly applied in nutrition research in recent years. A range of methods are available for the phenotyping of D. melanogaster, which are outlined in the first part of this review. The methods include determinations of body weight, body composition, food intake, lifespan, locomotor activity, reproductive capacity and stress tolerance. In the second part, the practical application of the phenotyping of flies is demonstrated via a discussion of obese phenotypes in response to high-sugar diet (HSD) and high-fat diet (HFD) feeding. HSD feeding and HFD feeding are dietary interventions that lead to an increase in fat storage and affect carbohydrate-insulin homeostasis, lifespan, locomotor activity, reproductive capacity and stress tolerance. Furthermore, studies regarding the impacts of HSD and HFD on the transcriptome and metabolome of D. melanogaster are important for relating phenotypic changes to underlying molecular mechanisms. Overall, D. melanogaster was demonstrated to be a valuable model organism with which to examine the pathogeneses and underlying molecular mechanisms of common chronic metabolic diseases in a nutritional context.
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Valer FB, Spegiorim GC, Espreafico EM, Ramos RGP. The IRM cell adhesion molecules Hibris, Kin of irre and Roughest control egg morphology by modulating ovarian muscle contraction in Drosophila. JOURNAL OF INSECT PHYSIOLOGY 2022; 136:104344. [PMID: 34896373 DOI: 10.1016/j.jinsphys.2021.104344] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 12/03/2021] [Accepted: 12/06/2021] [Indexed: 06/14/2023]
Abstract
The Irre Cell Recognition Module (IRM) is an evolutionarily conserved group of transmembrane glycoproteins required for cell-cell recognition and adhesion in metazoan development. In Drosophila melanogaster ovaries, four members of this group - Roughest (Rst), Kin of irre (Kirre), Hibris (Hbs) and Sticks and stones (Sns) - play important roles in germ cell encapsulation and muscle sheath organization during early pupal stages, as well as in the progression to late oogenesis in the adult. Females carrying some of the mutant rst alleles are viable but sterile, and previous work from our laboratory had identified defects in the organization of the peritoneal and epithelial muscle sheaths of these mutants that could underlie their sterile phenotype. In this study, besides further characterizing the sterility phenotype associated with rst mutants, we investigated the role of the IRM molecules Rst, Kirre and Hbs in maintaining the functionality of the ovarian muscle sheaths. We found that knocking down any of the three genes in these structures, either individually or in double heterozygous combinations, not only decreases contraction frequency but also irregularly increases contraction amplitude. Furthermore, these alterations can significantly impact the morphology of eggs laid by IRM-depleted females demonstrating a hitherto unknown role of IRM molecules in egg morphogenesis.
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Affiliation(s)
- Felipe Berti Valer
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Giulia Covolo Spegiorim
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Enilza Maria Espreafico
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
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Atienza-Manuel A, Castillo-Mancho V, De Renzis S, Culi J, Ruiz-Gómez M. Endocytosis mediated by an atypical CUBAM complex modulates slit diaphragm dynamics in nephrocytes. Development 2021; 148:272711. [PMID: 34738617 PMCID: PMC8710305 DOI: 10.1242/dev.199894] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 10/22/2021] [Indexed: 01/14/2023]
Abstract
The vertebrate endocytic receptor CUBAM, consisting of three cubilin monomers complexed with a single amnionless molecule, plays a major role in protein reabsorption in the renal proximal tubule. Here, we show that Drosophila CUBAM is a tripartite complex composed of Amnionless and two cubilin paralogues, Cubilin and Cubilin2, and that it is required for nephrocyte slit diaphragm (SD) dynamics. Loss of CUBAM-mediated endocytosis induces dramatic morphological changes in nephrocytes and promotes enlarged ingressions of the external membrane and SD mislocalisation. These phenotypes result in part from an imbalance between endocytosis, which is strongly impaired in CUBAM mutants, and exocytosis in these highly active cells. Of note, rescuing receptor-mediated endocytosis by Megalin/LRP2 or Rab5 expression only partially restores SD positioning in CUBAM mutants, suggesting a specific requirement of CUBAM in SD degradation and/or recycling. This finding and the reported expression of CUBAM in podocytes suggest a possible unexpected conserved role for this endocytic receptor in vertebrate SD remodelling. Summary: A genetic study revealing that endocytosis mediated by an atypical CUBAM endocytic receptor, composed of Amnionless and two Cubilin paralogues, regulates slit diaphragm remodelling in Drosophila nephrocytes.
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Affiliation(s)
- Alexandra Atienza-Manuel
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Nicolás Cabrera 1, Cantoblanco 28049, Madrid, Spain
| | - Vicente Castillo-Mancho
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Nicolás Cabrera 1, Cantoblanco 28049, Madrid, Spain
| | - Stefano De Renzis
- European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Joaquim Culi
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Nicolás Cabrera 1, Cantoblanco 28049, Madrid, Spain
| | - Mar Ruiz-Gómez
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Nicolás Cabrera 1, Cantoblanco 28049, Madrid, Spain
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31
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Solanki AK, Arif E, Srivastava P, Furcht CM, Rahman B, Wen P, Singh A, Holzman LB, Fitzgibbon WR, Budisavljevic MN, Lobo GP, Kwon SH, Han Z, Lazzara MJ, Lipschutz JH, Nihalani D. Phosphorylation of slit diaphragm proteins NEPHRIN and NEPH1 upon binding of HGF promotes podocyte repair. J Biol Chem 2021; 297:101079. [PMID: 34391780 PMCID: PMC8429977 DOI: 10.1016/j.jbc.2021.101079] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 08/02/2021] [Accepted: 08/11/2021] [Indexed: 12/22/2022] Open
Abstract
Phosphorylation (activation) and dephosphorylation (deactivation) of the slit diaphragm proteins NEPHRIN and NEPH1 are critical for maintaining the kidney epithelial podocyte actin cytoskeleton and, therefore, proper glomerular filtration. However, the mechanisms underlying these events remain largely unknown. Here we show that NEPHRIN and NEPH1 are novel receptor proteins for hepatocyte growth factor (HGF) and can be phosphorylated independently of the mesenchymal epithelial transition receptor in a ligand-dependent fashion through engagement of their extracellular domains by HGF. Furthermore, we demonstrate SH2 domain–containing protein tyrosine phosphatase-2–dependent dephosphorylation of these proteins. To establish HGF as a ligand, purified baculovirus-expressed NEPHRIN and NEPH1 recombinant proteins were used in surface plasma resonance binding experiments. We report high-affinity interactions of NEPHRIN and NEPH1 with HGF, although NEPHRIN binding was 20-fold higher than that of NEPH1. In addition, using molecular modeling we constructed peptides that were used to map specific HGF-binding regions in the extracellular domains of NEPHRIN and NEPH1. Finally, using an in vitro model of cultured podocytes and an ex vivo model of Drosophila nephrocytes, as well as chemically induced injury models, we demonstrated that HGF-induced phosphorylation of NEPHRIN and NEPH1 is centrally involved in podocyte repair. Taken together, this is the first study demonstrating a receptor-based function for NEPHRIN and NEPH1. This has important biological and clinical implications for the repair of injured podocytes and the maintenance of podocyte integrity.
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Affiliation(s)
- Ashish K Solanki
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Ehtesham Arif
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Pankaj Srivastava
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Christopher M Furcht
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Bushra Rahman
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Pei Wen
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Avinash Singh
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Lawrence B Holzman
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Wayne R Fitzgibbon
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Milos N Budisavljevic
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Glenn P Lobo
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Sang-Ho Kwon
- Department of Cellular Biology and Anatomy, Augusta University, Augusta, Georgia, USA
| | - Zhe Han
- Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Matthew J Lazzara
- Department of Chemical Engineering, University of Virginia, Charlottesville, Virginia, USA
| | - Joshua H Lipschutz
- Department of Medicine, Medical University of South Carolina, Charleston, South Carolina, USA; Department of Medicine, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina, USA.
| | - Deepak Nihalani
- Division of Kidney, Urologic and Hematologic Diseases, National Institutes of Health, Bethesda, Maryland, USA
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Selma-Soriano E, Casillas-Serra C, Artero R, Llamusi B, Navarro JA, Redón J. Rabphilin silencing causes dilated cardiomyopathy in a Drosophila model of nephrocyte damage. Sci Rep 2021; 11:15287. [PMID: 34315987 PMCID: PMC8316431 DOI: 10.1038/s41598-021-94710-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 07/14/2021] [Indexed: 11/10/2022] Open
Abstract
Heart failure (HF) and the development of chronic kidney disease (CKD) have a direct association. Both can be cause and consequence of the other. Many factors are known, such as diabetes or hypertension, which can lead to the appearance and/or development of these two conditions. However, it is suspected that other factors, namely genetic ones, may explain the differences in the manifestation and progression of HF and CKD among patients. One candidate factor is Rph, a gene expressed in the nervous and excretory system in mammals and Drosophila, encoding a Rab small GTPase family effector protein implicated in vesicular trafficking. We found that Rph is expressed in the Drosophila heart, and the silencing of Rph gene expression in this organ had a strong impact in the organization of fibers and functional cardiac parameters. Specifically, we observed a significant increase in diastolic and systolic diameters of the heart tube, which is a phenotype that resembles dilated cardiomyopathy in humans. Importantly, we also show that silencing of Rabphilin (Rph) expression exclusively in the pericardial nephrocytes, which are part of the flies' excretory system, brings about a non-cell-autonomous effect on the Drosophila cardiac system. In summary, in this work, we demonstrate the importance of Rph in the fly cardiac system and how silencing Rph expression in nephrocytes affects the Drosophila cardiac system.
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Affiliation(s)
- Estela Selma-Soriano
- INCLIVA Biomedical Research Institute, 46010, Valencia, Spain.,Department of Genetics, University of Valencia, 46100, Burjassot, Spain
| | - Carlos Casillas-Serra
- INCLIVA Biomedical Research Institute, 46010, Valencia, Spain.,Department of Genetics, University of Valencia, 46100, Burjassot, Spain
| | - Rubén Artero
- INCLIVA Biomedical Research Institute, 46010, Valencia, Spain. .,Institute for Biotechnology and Biomedicine (BIOTECMED), University of Valencia, 46100, Burjassot, Spain. .,CIPF-INCLIVA Joint Unit, Valencia, Spain.
| | - Beatriz Llamusi
- INCLIVA Biomedical Research Institute, 46010, Valencia, Spain.,Institute for Biotechnology and Biomedicine (BIOTECMED), University of Valencia, 46100, Burjassot, Spain.,CIPF-INCLIVA Joint Unit, Valencia, Spain
| | - Juan Antonio Navarro
- INCLIVA Biomedical Research Institute, 46010, Valencia, Spain.,Department of Genetics, University of Valencia, 46100, Burjassot, Spain
| | - Josep Redón
- INCLIVA Biomedical Research Institute, 46010, Valencia, Spain.,Hypertension Unit, Hospital Clínico Universitario, 46010, Valencia, Spain.,CIBERObn, Health Institute Carlos III, Madrid, Spain
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33
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Martinez-Arroyo O, Selma-Soriano E, Ortega A, Cortes R, Redon J. Small Rab GTPases in Intracellular Vesicle Trafficking: The Case of Rab3A/Raphillin-3A Complex in the Kidney. Int J Mol Sci 2021; 22:7679. [PMID: 34299299 PMCID: PMC8303874 DOI: 10.3390/ijms22147679] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/09/2021] [Accepted: 07/12/2021] [Indexed: 12/12/2022] Open
Abstract
Small Rab GTPases, the largest group of small monomeric GTPases, regulate vesicle trafficking in cells, which are integral to many cellular processes. Their role in neurological diseases, such as cancer and inflammation have been extensively studied, but their implication in kidney disease has not been researched in depth. Rab3a and its effector Rabphillin-3A (Rph3A) expression have been demonstrated to be present in the podocytes of normal kidneys of mice rats and humans, around vesicles contained in the foot processes, and they are overexpressed in diseases with proteinuria. In addition, the Rab3A knockout mice model induced profound cytoskeletal changes in podocytes of high glucose fed animals. Likewise, RphA interference in the Drosophila model produced structural and functional damage in nephrocytes with reduction in filtration capacities and nephrocyte number. Changes in the structure of cardiac fiber in the same RphA-interference model, open the question if Rab3A dysfunction would produce simultaneous damage in the heart and kidney cells, an attractive field that will require attention in the future.
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Affiliation(s)
- Olga Martinez-Arroyo
- Cardiometabolic and Renal Risk Research Group, INCLIVA Biomedical Research Institute, 46010 Valencia, Spain; (O.M.-A.); (R.C.)
| | - Estela Selma-Soriano
- Physiopathology of Cellular and Organic Oxidative Stress Group, University of Valencia, 46100 Valencia, Spain;
| | - Ana Ortega
- Cardiometabolic and Renal Risk Research Group, INCLIVA Biomedical Research Institute, 46010 Valencia, Spain; (O.M.-A.); (R.C.)
| | - Raquel Cortes
- Cardiometabolic and Renal Risk Research Group, INCLIVA Biomedical Research Institute, 46010 Valencia, Spain; (O.M.-A.); (R.C.)
| | - Josep Redon
- Cardiometabolic and Renal Risk Research Group, INCLIVA Biomedical Research Institute, 46010 Valencia, Spain; (O.M.-A.); (R.C.)
- CIBERObn, Carlos III Institute, 28029 Madrid, Spain
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34
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Mysh M, Poulton JS. The Basolateral Polarity Module Promotes Slit Diaphragm Formation in Drosophila Nephrocytes, a Model of Vertebrate Podocytes. J Am Soc Nephrol 2021; 32:1409-1424. [PMID: 33795424 PMCID: PMC8259641 DOI: 10.1681/asn.2020071050] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 02/12/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Podocyte slit diaphragms (SDs) are intercellular junctions that function as size-selective filters, excluding most proteins from urine. Abnormalities in SDs cause proteinuria and nephrotic syndrome. Podocytes exhibit apicobasal polarity, which can affect fundamental aspects of cell biology, including morphology, intercellular junction formation, and asymmetric protein distribution along the plasma membrane. Apical polarity protein mutations cause nephrotic syndrome, and data suggest apical polarity proteins regulate SD formation. However, there is no evidence that basolateral polarity proteins regulate SDs. Thus, the role of apicobasal polarity in podocytes remains unclear. METHODS Genetic manipulations and transgenic reporters determined the effects of disrupting apicobasal polarity proteins in Drosophila nephrocytes, which have SDs similar to those of mammalian podocytes. Confocal and electron microscopy were used to characterize SD integrity after loss of basolateral polarity proteins, and genetic-interaction studies illuminated relationships among apicobasal polarity proteins. RESULTS The study identified four novel regulators of nephrocyte SDs: Dlg, Lgl, Scrib, and Par-1. These proteins comprise the basolateral polarity module and its effector kinase. The data suggest these proteins work together, with apical polarity proteins, to regulate SDs by promoting normal endocytosis and trafficking of SD proteins. CONCLUSIONS Given the recognized importance of apical polarity proteins and SD protein trafficking in podocytopathies, the findings connecting basolateral polarity proteins to these processes significantly advance our understanding of SD regulation.
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Affiliation(s)
- Michael Mysh
- Department of Biology, UNC Kidney Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - John S. Poulton
- Division of Nephrology and Hypertension, Department of Medicine, UNC Kidney Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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35
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Wang L, Wen P, van de Leemput J, Zhao Z, Han Z. Slit diaphragm maintenance requires dynamic clathrin-mediated endocytosis facilitated by AP-2, Lap, Aux and Hsc70-4 in nephrocytes. Cell Biosci 2021; 11:83. [PMID: 33975644 PMCID: PMC8111712 DOI: 10.1186/s13578-021-00595-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/29/2021] [Indexed: 11/10/2022] Open
Abstract
Background The Slit diaphragm (SD) is the key filtration structure in human glomerular kidney that is affected in many types of renal diseases. SD proteins are known to undergo endocytosis and recycling to maintain the integrity of the filtration structure. However, the key components of this pathway remain unclear. Methods Using the Drosophila nephrocyte as a genetic screen platform, we screened most genes involved in endocytosis and cell trafficking, and identified the key components of the cell trafficking pathway required for SD protein endocytosis and recycling. Results We discovered that the SD protein endocytosis and recycling pathway contains clathrin, dynamin, AP-2 complex, like-AP180 (Lap), auxilin and Hsc70-4 (the endocytosis part) followed by Rab11 and the exocyst complex (the recycling part). Disrupting any component in this pathway led to disrupted SD on the cell surface and intracellular accumulation of mislocalized SD proteins. We also showed the first in vivo evidence of trapped SD proteins in clathrin-coated pits at the plasma membrane when this pathway is disrupted. Conclusions All genes in this SD protein endocytosis and recycling pathway, as well as SD proteins themselves, are highly conserved from flies to humans. Thus, our results suggest that the SD proteins in human kidney undergo the same endocytosis and recycling pathway to maintain the filtration structure, and mutations in any genes in this pathway could lead to abnormal SD and renal diseases. Supplementary Information The online version contains supplementary material available at 10.1186/s13578-021-00595-4.
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Affiliation(s)
- Luyao Wang
- Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe Eastern Road, Zhengzhou, 450052, Henan, China.,Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD, 21201, USA.,Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Pei Wen
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD, 21201, USA.,Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Joyce van de Leemput
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD, 21201, USA.,Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Zhanzheng Zhao
- Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, No. 1 Jianshe Eastern Road, Zhengzhou, 450052, Henan, China.
| | - Zhe Han
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, 670 West Baltimore Street, Baltimore, MD, 21201, USA. .,Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
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36
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Lubojemska A, Stefana MI, Sorge S, Bailey AP, Lampe L, Yoshimura A, Burrell A, Collinson L, Gould AP. Adipose triglyceride lipase protects renal cell endocytosis in a Drosophila dietary model of chronic kidney disease. PLoS Biol 2021; 19:e3001230. [PMID: 33945525 PMCID: PMC8121332 DOI: 10.1371/journal.pbio.3001230] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 05/14/2021] [Accepted: 04/13/2021] [Indexed: 12/13/2022] Open
Abstract
Obesity-related renal lipotoxicity and chronic kidney disease (CKD) are prevalent pathologies with complex aetiologies. One hallmark of renal lipotoxicity is the ectopic accumulation of lipid droplets in kidney podocytes and in proximal tubule cells. Renal lipid droplets are observed in human CKD patients and in high-fat diet (HFD) rodent models, but their precise role remains unclear. Here, we establish a HFD model in Drosophila that recapitulates renal lipid droplets and several other aspects of mammalian CKD. Cell type-specific genetic manipulations show that lipid can overflow from adipose tissue and is taken up by renal cells called nephrocytes. A HFD drives nephrocyte lipid uptake via the multiligand receptor Cubilin (Cubn), leading to the ectopic accumulation of lipid droplets. These nephrocyte lipid droplets correlate with endoplasmic reticulum (ER) and mitochondrial deficits, as well as with impaired macromolecular endocytosis, a key conserved function of renal cells. Nephrocyte knockdown of diglyceride acyltransferase 1 (DGAT1), overexpression of adipose triglyceride lipase (ATGL), and epistasis tests together reveal that fatty acid flux through the lipid droplet triglyceride compartment protects the ER, mitochondria, and endocytosis of renal cells. Strikingly, boosting nephrocyte expression of the lipid droplet resident enzyme ATGL is sufficient to rescue HFD-induced defects in renal endocytosis. Moreover, endocytic rescue requires a conserved mitochondrial regulator, peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC1α). This study demonstrates that lipid droplet lipolysis counteracts the harmful effects of a HFD via a mitochondrial pathway that protects renal endocytosis. It also provides a genetic strategy for determining whether lipid droplets in different biological contexts function primarily to release beneficial or to sequester toxic lipids.
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Affiliation(s)
- Aleksandra Lubojemska
- Physiology and Metabolism Laboratory, The Francis Crick Institute, London, United Kingdom
| | - M. Irina Stefana
- Physiology and Metabolism Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Sebastian Sorge
- Physiology and Metabolism Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Andrew P. Bailey
- Physiology and Metabolism Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Lena Lampe
- Physiology and Metabolism Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Azumi Yoshimura
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - Alana Burrell
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - Lucy Collinson
- Electron Microscopy Science Technology Platform, The Francis Crick Institute, London, United Kingdom
| | - Alex P. Gould
- Physiology and Metabolism Laboratory, The Francis Crick Institute, London, United Kingdom
- * E-mail:
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37
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Heiden S, Siwek R, Lotz ML, Borkowsky S, Schröter R, Nedvetsky P, Rohlmann A, Missler M, Krahn MP. Apical-basal polarity regulators are essential for slit diaphragm assembly and endocytosis in Drosophila nephrocytes. Cell Mol Life Sci 2021; 78:3657-3672. [PMID: 33651172 PMCID: PMC8038974 DOI: 10.1007/s00018-021-03769-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 01/11/2021] [Accepted: 01/16/2021] [Indexed: 12/02/2022]
Abstract
Apical-basal polarity is a key feature of most epithelial cells and it is regulated by highly conserved protein complexes. In mammalian podocytes, which emerge from columnar epithelial cells, this polarity is preserved and the tight junctions are converted to the slit diaphragms, establishing the filtration barrier. In Drosophila, nephrocytes show several structural and functional similarities with mammalian podocytes and proximal tubular cells. However, in contrast to podocytes, little is known about the role of apical-basal polarity regulators in these cells. In this study, we used expansion microscopy and found the apical polarity determinants of the PAR/aPKC and Crb-complexes to be predominantly targeted to the cell cortex in proximity to the nephrocyte diaphragm, whereas basolateral regulators also accumulate intracellularly. Knockdown of PAR-complex proteins results in severe endocytosis and nephrocyte diaphragm defects, which is due to impaired aPKC recruitment to the plasma membrane. Similar, downregulation of most basolateral polarity regulators disrupts Nephrin localization but had surprisingly divergent effects on endocytosis. Our findings suggest that morphology and slit diaphragm assembly/maintenance of nephrocytes is regulated by classical apical-basal polarity regulators, which have distinct functions in endocytosis.
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Affiliation(s)
- Stefanie Heiden
- Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Albert-Schweitzer Campus 1-A14, 48149, Münster, Germany
| | - Rebecca Siwek
- Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Albert-Schweitzer Campus 1-A14, 48149, Münster, Germany
| | - Marie-Luise Lotz
- Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Albert-Schweitzer Campus 1-A14, 48149, Münster, Germany
| | - Sarah Borkowsky
- Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Albert-Schweitzer Campus 1-A14, 48149, Münster, Germany
| | - Rita Schröter
- Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Albert-Schweitzer Campus 1-A14, 48149, Münster, Germany
| | - Pavel Nedvetsky
- Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Albert-Schweitzer Campus 1-A14, 48149, Münster, Germany
| | - Astrid Rohlmann
- Institute of Anatomy and Molecular Neurobiology, University of Münster, Vesaliusweg 2-4, 48149, Münster, Germany
| | - Markus Missler
- Institute of Anatomy and Molecular Neurobiology, University of Münster, Vesaliusweg 2-4, 48149, Münster, Germany
| | - Michael P Krahn
- Medical Cell Biology, Medical Clinic D, University Hospital of Münster, Albert-Schweitzer Campus 1-A14, 48149, Münster, Germany.
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38
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Kim K, Cha SJ, Choi HJ, Kang JS, Lee EY. Dysfunction of Mitochondrial Dynamics in Drosophila Model of Diabetic Nephropathy. Life (Basel) 2021; 11:life11010067. [PMID: 33477666 PMCID: PMC7831917 DOI: 10.3390/life11010067] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/15/2021] [Accepted: 01/16/2021] [Indexed: 01/05/2023] Open
Abstract
Although mitochondrial dysfunction is associated with the development and progression of diabetic nephropathy (DN), its mechanisms are poorly understood, and it remains debatable whether mitochondrial morphological change is a cause of DN. In this study, a Drosophila DN model was established by treating a chronic high-sucrose diet that exhibits similar phenotypes in animals. Results showed that flies fed a chronic high-sucrose diet exhibited a reduction in lifespan, as well as increased lipid droplets in fat body tissue. Furthermore, the chronic high-sucrose diet effectively induced the morphological abnormalities of nephrocytes in Drosophila. High-sucrose diet induced mitochondria fusion in nephrocytes by increasing Opa1 and Marf expression. These findings establish Drosophila as a useful model for studying novel regulators and molecular mechanisms for imbalanced mitochondrial dynamics in the pathogenesis of DN. Furthermore, understanding the pathology of mitochondrial dysfunction regarding morphological changes in DN would facilitate the development of novel therapeutics.
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Affiliation(s)
- Kiyoung Kim
- Department of Medical Biotechnology, Soonchunhyang University, Asan 31538, Korea
- Department of Medical Sciences, Soonchunhyang University, Asan 31538, Korea;
- Correspondence: (K.K.); (E.Y.L.); Tel.: +82-41-413-5024 (K.K.); +82-41-570-3684 (E.Y.L.); Fax: +82-41-413-5006 (K.K. & E.Y.L.)
| | - Sun Joo Cha
- Department of Medical Sciences, Soonchunhyang University, Asan 31538, Korea;
| | - Hyun-Jun Choi
- Department of Integrated Biomedical Sciences, Soonchunhyang University, Cheonan 31151, Korea;
| | - Jeong Suk Kang
- Division of Nephrology, Department of Internal Medicine, Soonchunhyang University Cheonan Hospital, Cheonan 31151, Korea;
- Institute of Tissue Regeneration, College of Medicine, Soonchunhyang University, Cheonan 31151, Korea
| | - Eun Young Lee
- Division of Nephrology, Department of Internal Medicine, Soonchunhyang University Cheonan Hospital, Cheonan 31151, Korea;
- Institute of Tissue Regeneration, College of Medicine, Soonchunhyang University, Cheonan 31151, Korea
- BK21 FOUR Project, College of Medicine, Soonchunhyang University, Cheonan 31151, Korea
- Correspondence: (K.K.); (E.Y.L.); Tel.: +82-41-413-5024 (K.K.); +82-41-570-3684 (E.Y.L.); Fax: +82-41-413-5006 (K.K. & E.Y.L.)
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Bayraktar S, Nehrig J, Menis E, Karli K, Janning A, Struk T, Halbritter J, Michgehl U, Krahn MP, Schuberth CE, Pavenstädt H, Wedlich-Söldner R. A Deregulated Stress Response Underlies Distinct INF2-Associated Disease Profiles. J Am Soc Nephrol 2021; 31:1296-1313. [PMID: 32444357 DOI: 10.1681/asn.2019111174] [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: 11/14/2019] [Accepted: 03/20/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Monogenic diseases provide favorable opportunities to elucidate the molecular mechanisms of disease progression and improve medical diagnostics. However, the complex interplay between genetic and environmental factors in disease etiologies makes it difficult to discern the mechanistic links between different alleles of a single locus and their associated pathophysiologies. Inverted formin 2 (INF2), an actin regulator, mediates a stress response-calcium mediated actin reset, or CaAR-that reorganizes the actin cytoskeleton of mammalian cells in response to calcium influx. It has been linked to the podocytic kidney disease focal segemental glomerulosclerosis (FSGS), as well as to cases of the neurologic disorder Charcot-Marie-Tooth disease that are accompanied by nephropathy, mostly FSGS. METHODS We used a combination of quantitative live cell imaging and validation in primary patient cells and Drosophila nephrocytes to systematically characterize a large panel of >50 autosomal dominant INF2 mutants that have been reported to cause either FSGS alone or with Charcot-Marie-Tooth disease. RESULTS We found that INF2 mutations lead to deregulated activation of formin and a constitutive stress response in cultured cells, primary patient cells, and Drosophila nephrocytes. We were able to clearly distinguish between INF2 mutations that were linked exclusively to FSGS from those that caused a combination of FSGS and Charcot-Marie-Tooth disease. Furthermore, we were able to identify distinct subsets of INF2 variants that exhibit varying degrees of activation. CONCLUSIONS Our results suggest that CaAR can be used as a sensitive assay for INF2 function and for robust evaluation of diseased-linked variants of formin. More broadly, these findings indicate that cellular profiling of disease-associated mutations has potential to contribute substantially to sequence-based phenotype predictions.
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Affiliation(s)
- Samet Bayraktar
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany.,Internal Medicine D, University Hospital Münster, Münster, Germany
| | - Julian Nehrig
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | - Ekaterina Menis
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | - Kevser Karli
- Medical Cell Biology, Internal Medicine D, University Hospital Münster, Münster, Germany
| | - Annette Janning
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | - Thaddäus Struk
- Internal Medicine D, University Hospital Münster, Münster, Germany
| | - Jan Halbritter
- Division of Nephrology, University of Leipzig, Leipzig, Germany
| | - Ulf Michgehl
- Internal Medicine D, University Hospital Münster, Münster, Germany
| | - Michael P Krahn
- Medical Cell Biology, Internal Medicine D, University Hospital Münster, Münster, Germany
| | - Christian E Schuberth
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | | | - Roland Wedlich-Söldner
- Institute of Cell Dynamics and Imaging and Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
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40
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Miyaki T, Kawasaki Y, Matsumoto A, Kakuta S, Sakai T, Ichimura K. Nephrocytes are part of the spectrum of filtration epithelial diversity. Cell Tissue Res 2020; 382:609-625. [PMID: 33191456 PMCID: PMC7683493 DOI: 10.1007/s00441-020-03313-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 09/24/2020] [Indexed: 12/15/2022]
Abstract
The excretory system produces urine by ultrafiltration via a filtration epithelium. Podocytes are widely found as filtration epithelial cells in eucoelomates. In some animal taxa, including insects and crustaceans, nephrocytes serve to separate toxic substances from the body fluid, in addition to podocytes. Drosophila nephrocytes have been recently utilized as a model system to study podocyte function and disease. However, functionality and cellular architecture are strikingly different between Drosophila nephrocytes and eucoelomate podocytes, and the phylogenetic relationship between these cells remains enigmatic. In this study, using focused-ion beam-scanning electron microscopy (FIB-SEM) tomography, we revealed three-dimensional architecture of decapod nephrocytes with unprecedented accuracy—they filled an enormous gap, which can be called “missing link,” in the evolutionary diversity of podocytes and nephrocytes. Thus, we concluded that nephrocytes are part of the spectrum of filtration epithelial diversity in animal phylogeny.
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Affiliation(s)
- Takayuki Miyaki
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Yuto Kawasaki
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Akira Matsumoto
- Department of Biology, Juntendo University School of Medicine, Inzai, Chiba, Japan
| | - Soichiro Kakuta
- Laboratory of Morphology and Image Analysis, Center for Biomedical Research Resources, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Tatsuo Sakai
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Koichiro Ichimura
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo, Japan. .,Laboratory of Morphology and Image Analysis, Center for Biomedical Research Resources, Juntendo University Graduate School of Medicine, Tokyo, Japan.
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41
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Marchesin V, Pérez-Martí A, Le Meur G, Pichler R, Grand K, Klootwijk ED, Kesselheim A, Kleta R, Lienkamp S, Simons M. Molecular Basis for Autosomal-Dominant Renal Fanconi Syndrome Caused by HNF4A. Cell Rep 2020; 29:4407-4421.e5. [PMID: 31875549 PMCID: PMC6941224 DOI: 10.1016/j.celrep.2019.11.066] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 10/08/2019] [Accepted: 11/15/2019] [Indexed: 12/26/2022] Open
Abstract
HNF4A is a nuclear hormone receptor that binds DNA as an obligate homodimer. While all known human heterozygous mutations are associated with the autosomal-dominant diabetes form MODY1, one particular mutation (p.R85W) in the DNA-binding domain (DBD) causes additional renal Fanconi syndrome (FRTS). Here, we find that expression of the conserved fly ortholog dHNF4 harboring the FRTS mutation in Drosophila nephrocytes caused nuclear depletion and cytosolic aggregation of a wild-type dHNF4 reporter protein. While the nuclear depletion led to mitochondrial defects and lipid droplet accumulation, the cytosolic aggregates triggered the expansion of the endoplasmic reticulum (ER), autophagy, and eventually cell death. The latter effects could be fully rescued by preventing nuclear export through interfering with serine phosphorylation in the DBD. Our data describe a genomic and a non-genomic mechanism for FRTS in HNF4A-associated MODY1 with important implications for the renal proximal tubule and the regulation of other nuclear hormone receptors. HNF4 controls lipid metabolism in Drosophila nephrocytes The kidney disease mutation R85W shows dominant-negative effects in nephrocytes Dephosphorylation at S87 prevents the dominant-negative effects R85W mutation causes mitochondrial dysfunction in reprogrammed renal epithelial cells
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Affiliation(s)
- Valentina Marchesin
- INSERM UMR1163, Laboratory of Epithelial Biology and Disease, Imagine Institute, Paris Descartes University, Sorbonne Paris Cité, Hôpital Necker-Enfants Malades, 75015 Paris, France
| | - Albert Pérez-Martí
- INSERM UMR1163, Laboratory of Epithelial Biology and Disease, Imagine Institute, Paris Descartes University, Sorbonne Paris Cité, Hôpital Necker-Enfants Malades, 75015 Paris, France
| | - Gwenn Le Meur
- INSERM UMR1163, Laboratory of Epithelial Biology and Disease, Imagine Institute, Paris Descartes University, Sorbonne Paris Cité, Hôpital Necker-Enfants Malades, 75015 Paris, France
| | - Roman Pichler
- Renal Division, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, 79098 Freiburg, Germany
| | - Kelli Grand
- Institute of Anatomy, University of Zurich, 8057 Zurich, Switzerland
| | - Enriko D Klootwijk
- Department of Renal Medicine, University College London, London NW3 2PF, UK
| | - Anne Kesselheim
- Department of Renal Medicine, University College London, London NW3 2PF, UK
| | - Robert Kleta
- Department of Renal Medicine, University College London, London NW3 2PF, UK
| | - Soeren Lienkamp
- Renal Division, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, 79098 Freiburg, Germany; Institute of Anatomy, University of Zurich, 8057 Zurich, Switzerland
| | - Matias Simons
- INSERM UMR1163, Laboratory of Epithelial Biology and Disease, Imagine Institute, Paris Descartes University, Sorbonne Paris Cité, Hôpital Necker-Enfants Malades, 75015 Paris, France.
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42
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Selma-Soriano E, Llamusi B, Fernández-Costa JM, Ozimski LL, Artero R, Redón J. Rabphilin involvement in filtration and molecular uptake in Drosophila nephrocytes suggests a similar role in human podocytes. Dis Model Mech 2020; 13:dmm041509. [PMID: 32680845 PMCID: PMC7522021 DOI: 10.1242/dmm.041509] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 07/07/2020] [Indexed: 02/04/2023] Open
Abstract
Drosophila nephrocytes share functional, structural and molecular similarities with human podocytes. It is known that podocytes express the rabphilin 3A (RPH3A)-RAB3A complex, and its expression is altered in mouse and human proteinuric disease. Furthermore, we previously identified a polymorphism that suggested a role for RPH3A protein in the development of urinary albumin excretion. As endocytosis and vesicle trafficking are fundamental pathways for nephrocytes, the objective of this study was to assess the role of the RPH3A orthologue in Drosophila, Rabphilin (Rph), in the structure and function of nephrocytes. We confirmed that Rph is required for the correct function of the endocytic pathway in pericardial Drosophila nephrocytes. Knockdown of Rph reduced the expression of the cubilin and stick and stones genes, which encode proteins that are involved in protein uptake and filtration. We also found that reduced Rph expression resulted in a disappearance of the labyrinthine channel structure and a reduction in the number of endosomes, which ultimately leads to changes in the number and volume of nephrocytes. Finally, we demonstrated that the administration of retinoic acid to IR-Rph nephrocytes rescued some altered aspects, such as filtration and molecular uptake, as well as the maintenance of cell fate. According to our data, Rph is crucial for nephrocyte filtration and reabsorption, and it is required for the maintenance of the ultrastructure, integrity and differentiation of the nephrocyte.
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Affiliation(s)
- Estela Selma-Soriano
- Translational Genomics Group, Incliva Health Research Institute, 46010 Valencia, Spain
- Interdisciplinary Research Structure for Biotechnology and Biomedicine (ERI BIOTECMED), University of Valencia, 46100 Valencia, Spain
- CIPF-INCLIVA Joint Unit, 46010 Valencia, Spain
| | - Beatriz Llamusi
- Translational Genomics Group, Incliva Health Research Institute, 46010 Valencia, Spain
- Interdisciplinary Research Structure for Biotechnology and Biomedicine (ERI BIOTECMED), University of Valencia, 46100 Valencia, Spain
- CIPF-INCLIVA Joint Unit, 46010 Valencia, Spain
| | - Juan Manuel Fernández-Costa
- Translational Genomics Group, Incliva Health Research Institute, 46010 Valencia, Spain
- Interdisciplinary Research Structure for Biotechnology and Biomedicine (ERI BIOTECMED), University of Valencia, 46100 Valencia, Spain
- CIPF-INCLIVA Joint Unit, 46010 Valencia, Spain
| | - Lauren Louise Ozimski
- Translational Genomics Group, Incliva Health Research Institute, 46010 Valencia, Spain
- Interdisciplinary Research Structure for Biotechnology and Biomedicine (ERI BIOTECMED), University of Valencia, 46100 Valencia, Spain
- CIPF-INCLIVA Joint Unit, 46010 Valencia, Spain
| | - Rubén Artero
- Translational Genomics Group, Incliva Health Research Institute, 46010 Valencia, Spain
- Interdisciplinary Research Structure for Biotechnology and Biomedicine (ERI BIOTECMED), University of Valencia, 46100 Valencia, Spain
- CIPF-INCLIVA Joint Unit, 46010 Valencia, Spain
| | - Josep Redón
- Hypertension Unit, Hospital Clínico Universitario, 46010 Valencia, Spain
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Lim HY, Bao H, Liu Y, Wang W. Select Septate Junction Proteins Direct ROS-Mediated Paracrine Regulation of Drosophila Cardiac Function. Cell Rep 2020; 28:1455-1470.e4. [PMID: 31390561 DOI: 10.1016/j.celrep.2019.07.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 04/18/2019] [Accepted: 06/27/2019] [Indexed: 12/27/2022] Open
Abstract
Septate junction (SJ) complex proteins act in unison to provide a paracellular barrier and maintain structural integrity. Here, we identify a non-barrier role of two individual SJ proteins, Coracle (Cora) and Kune-kune (Kune). Reactive oxygen species (ROS)-p38 MAPK signaling in non-myocytic pericardial cells (PCs) is important for maintaining normal cardiac physiology in Drosophila. However, the underlying mechanisms remain unknown. We find that in PCs, Cora and Kune are altered in abundance in response to manipulations of ROS-p38 signaling. Genetic analyses establish Cora and Kune as key effectors of ROS-p38 signaling in PCs on proper heart function. We further determine that Cora regulates normal Kune levels in PCs, which in turn modulates normal Kune levels in the cardiomyocytes essential for proper heart function. Our results thereby reveal select SJ proteins Cora and Kune as signaling mediators of the PC-derived ROS regulation of cardiac physiology.
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Affiliation(s)
- Hui-Ying Lim
- Department of Physiology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA.
| | - Hong Bao
- Department of Physiology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
| | - Ying Liu
- Department of Physiology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
| | - Weidong Wang
- Department of Medicine, Section of Endocrinology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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Zheng W, Ocorr K, Tatar M. Extracellular matrix induced by steroids and aging through a G-protein-coupled receptor in a Drosophila model of renal fibrosis. Dis Model Mech 2020; 13:dmm041301. [PMID: 32461236 PMCID: PMC7328168 DOI: 10.1242/dmm.041301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 04/17/2020] [Indexed: 12/20/2022] Open
Abstract
Aldosterone is produced by the mammalian adrenal cortex to modulate blood pressure and fluid balance; however, excessive, prolonged aldosterone promotes fibrosis and kidney failure. How aldosterone triggers disease may involve actions independent of its canonical mineralocorticoid receptor. Here, we present a Drosophila model of renal pathology caused by excess extracellular matrix formation, stimulated by exogenous aldosterone and by insect ecdysone. Chronic administration of aldosterone or ecdysone induces expression and accumulation of collagen-like Pericardin in adult nephrocytes - podocyte-like cells that filter circulating hemolymph. Excess Pericardin deposition disrupts nephrocyte (glomerular) filtration and causes proteinuria in Drosophila, hallmarks of mammalian kidney failure. Steroid-induced Pericardin production arises from cardiomyocytes associated with nephrocytes, potentially reflecting an analogous role of mammalian myofibroblasts in fibrotic disease. Remarkably, the canonical ecdysteroid nuclear hormone receptor, Ecdysone receptor (EcR), is not required for aldosterone or ecdysone to stimulate Pericardin production or associated renal pathology. Instead, these hormones require a cardiomyocyte-associated G-protein-coupled receptor, Dopamine-EcR (DopEcR), a membrane-associated receptor previously characterized in the fly brain to affect behavior. DopEcR in the brain is known to affect behavior through interactions with the Drosophila Epidermal growth factor receptor (Egfr), referred to as dEGFR. Here, we find that the steroids ecdysone and aldosterone require dEGFR in cardiomyocytes to induce fibrosis of the cardiac-renal system. In addition, endogenous ecdysone that becomes elevated with age is found to foster age-associated fibrosis, and to require both cardiomyocyte DopEcR and dEGFR. This Drosophila renal disease model reveals a novel signaling pathway through which steroids may modulate mammalian fibrosis through potential orthologs of DopEcR.
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Affiliation(s)
- Wenjing Zheng
- Department of Ecology and Evolutionary Biology, Division of Biology and Medicine, Brown University, Providence RI 02912, USA
| | - Karen Ocorr
- Development, Aging and Regeneration Program, SBP Medical Discovery Institute, La Jolla, CA 92037, USA
| | - Marc Tatar
- Department of Ecology and Evolutionary Biology, Division of Biology and Medicine, Brown University, Providence RI 02912, USA
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Molinari E, Sayer JA. Disease Modeling To Understand the Pathomechanisms of Human Genetic Kidney Disorders. Clin J Am Soc Nephrol 2020; 15:855-872. [PMID: 32139361 PMCID: PMC7274277 DOI: 10.2215/cjn.08890719] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The class of human genetic kidney diseases is extremely broad and heterogeneous. Accordingly, the range of associated disease phenotypes is highly variable. Many children and adults affected by inherited kidney disease will progress to ESKD at some point in life. Extensive research has been performed on various different disease models to investigate the underlying causes of genetic kidney disease and to identify disease mechanisms that are amenable to therapy. We review some of the research highlights that, by modeling inherited kidney disease, contributed to a better understanding of the underlying pathomechanisms, leading to the identification of novel genetic causes, new therapeutic targets, and to the development of new treatments. We also discuss how the implementation of more efficient genome-editing techniques and tissue-culture methods for kidney research is providing us with personalized models for a precision-medicine approach that takes into account the specificities of the patient and the underlying disease. We focus on the most common model systems used in kidney research and discuss how, according to their specific features, they can differentially contribute to biomedical research. Unfortunately, no definitive treatment exists for most inherited kidney disorders, warranting further exploitation of the existing disease models, as well as the implementation of novel, complex, human patient-specific models to deliver research breakthroughs.
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Affiliation(s)
- Elisa Molinari
- Faculty of Medical Sciences, Translational and Clinical Research Institute, International Centre for Life, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - John A. Sayer
- Faculty of Medical Sciences, Translational and Clinical Research Institute, International Centre for Life, Newcastle University, Newcastle upon Tyne, United Kingdom
- Renal Services, Newcastle Upon Tyne Hospitals National Health Service Trust, Newcastle upon Tyne, United Kingdom
- National Institute for Health Research Newcastle Biomedical Research Centre, Newcastle upon Tyne, United Kingdom
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Abstract
PURPOSE OF REVIEW Studies of the genetic model organism, Drosophila melanogaster, have unraveled molecular pathways relevant to human physiology and disease. The Malpighian tubule, the Drosophila renal epithelium, is described here, including tools available to study transport; conserved transporters, channels, and the signaling pathways regulating them; and fly models of kidney stone disease. RECENT FINDINGS Tools to measure Malpighian tubule transport continue to advance, including use of a transgenic sensor to quantify intracellular pH and proton fluxes. A recent study generated an RNA-sequencing-based atlas of tissue-specific gene expression, with resulting insights into Malpighian tubule gene expression of transporters and channels. Advances have been made in understanding the molecular physiology of the With No Lysine kinase-Ste20-related proline/alanine rich kinase/oxidative stress response kinase cascade that regulates epithelial ion transport in flies and mammals. New studies in Drosophila kidney stone models have characterized zinc transporters and used Malpighian tubules to study the efficacy of a plant metabolite in decreasing stone burden. SUMMARY Study of the Drosophila Malpighian tubule affords opportunities to better characterize the molecular physiology of epithelial transport mechanisms relevant to mammalian renal physiology.
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47
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Wen P, Zhang F, Fu Y, Zhu JY, Han Z. Exocyst Genes Are Essential for Recycling Membrane Proteins and Maintaining Slit Diaphragm in Drosophila Nephrocytes. J Am Soc Nephrol 2020; 31:1024-1034. [PMID: 32238475 DOI: 10.1681/asn.2019060591] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 02/17/2020] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Studies have linked mutations in genes encoding the eight-protein exocyst protein complex to kidney disease, but the underlying mechanism is unclear. Because Drosophila nephrocytes share molecular and structural features with mammalian podocytes, they provide an efficient model for studying this issue. METHODS We silenced genes encoding exocyst complex proteins specifically in Drosophila nephrocytes and studied the effects on protein reabsorption by lacuna channels and filtration by the slit diaphragm. We performed nephrocyte functional assays, carried out super-resolution confocal microscopy of slit diaphragm proteins, and used transmission electron microscopy to analyze ultrastructural changes. We also examined the colocalization of slit diaphragm proteins with exocyst protein Sec15 and with endocytosis and recycling regulators Rab5, Rab7, and Rab11. RESULTS Silencing exocyst genes in nephrocytes led to profound changes in structure and function. Abolition of cellular accumulation of hemolymph proteins with dramatically reduced lacuna channel membrane invaginations offered a strong indication of reabsorption defects. Moreover, the slit diaphragm's highly organized surface structure-essential for filtration-was disrupted, and key proteins were mislocalized. Ultrastructural analysis revealed that exocyst gene silencing led to the striking appearance of novel electron-dense structures that we named "exocyst rods," which likely represent accumulated membrane proteins following defective exocytosis or recycling. The slit diaphragm proteins partially colocalized with Sec15, Rab5, and Rab11. CONCLUSIONS Our findings suggest that the slit diaphragm of Drosophila nephrocytes requires balanced endocytosis and recycling to maintain its structural integrity and that impairment of the exocyst complex leads to disruption of the slit diaphragm and nephrocyte malfunction. This model may help identify therapeutic targets for treating kidney diseases featuring molecular defects in vesicle endocytosis, exocytosis, and recycling.
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Affiliation(s)
- Pei Wen
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland.,Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Fujian Zhang
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Yulong Fu
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Jun-Yi Zhu
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland.,Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Zhe Han
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland .,Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
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48
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Modeling Podocyte Biology Using Drosophila Nephrocytes. Methods Mol Biol 2019. [PMID: 31701442 DOI: 10.1007/978-1-4939-9841-8_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Vertebrate podocytes are kidney glomerular cells critically required for normal renal filtration. To fulfill their role, podocytes form molecular sieves known as slit diaphragms that contribute to the glomerular filtration barrier. The disruption of podocyte biology or slit diaphragm formation in humans is a precursor to albuminuria, renal failure, and cardiovascular morbidity. Due to genetic and functional similarities, the nephrocytes of Drosophila are increasingly used to model the genetic and metabolic basis of human podocyte biology. They have the advantage that they are a much quicker system to study compared to other murine transgenic models. In this chapter we present methods to modulate and study Drosophila nephrocyte function and diaphragm formation.
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Troha K, Nagy P, Pivovar A, Lazzaro BP, Hartley PS, Buchon N. Nephrocytes Remove Microbiota-Derived Peptidoglycan from Systemic Circulation to Maintain Immune Homeostasis. Immunity 2019; 51:625-637.e3. [DOI: 10.1016/j.immuni.2019.08.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 05/14/2019] [Accepted: 08/27/2019] [Indexed: 10/25/2022]
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50
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Carrasco-Rando M, Prieto-Sánchez S, Culi J, Tutor AS, Ruiz-Gómez M. A specific isoform of Pyd/ZO-1 mediates junctional remodeling and formation of slit diaphragms. J Cell Biol 2019; 218:2294-2308. [PMID: 31171632 PMCID: PMC6605796 DOI: 10.1083/jcb.201810171] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 03/21/2019] [Accepted: 05/14/2019] [Indexed: 12/18/2022] Open
Abstract
Podocyte slit diaphragms are key components of the glomerular filtration barrier. Using Drosophila nephrocytes, Carrasco-Rando et al. propose a conserved role for Pyd/ZO-1 in triggering junctional remodeling leading to the formation of slit diaphragms. The podocyte slit diaphragm (SD), responsible for blood filtration in vertebrates, is a major target of injury in chronic kidney disease. The damage includes severe morphological changes with destabilization of SDs and their replacement by junctional complexes between abnormally broadened foot processes. In Drosophila melanogaster, SDs are present in nephrocytes, which filter the fly's hemolymph. Here, we show that a specific isoform of Polychaetoid/ZO-1, Pyd-P, is essential for Drosophila SDs, since, in pyd mutants devoid of Pyd-P, SDs do not form and the SD component Dumbfounded accumulates at ectopic septate-like junctions between abnormally aggregated nephrocytes. Reintroduction of Pyd-P leads to junctional remodeling and their progressive normalization toward SDs. This transition requires the coiled-coil domain of Pyd-P and implies formation of nonclathrin vesicles containing SD components and their trafficking to the nephrocyte external membrane, where SDs assemble. Analyses in zebrafish suggest a conserved role for Tjp1a/ZO-1 in promoting junctional remodeling in podocytes.
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Affiliation(s)
- Marta Carrasco-Rando
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Silvia Prieto-Sánchez
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Joaquim Culi
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Antonio S Tutor
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
| | - Mar Ruiz-Gómez
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain
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