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Miyaki T, Homma N, Kawasaki Y, Kishi M, Yamaguchi J, Kakuta S, Shindo T, Sugiura M, Oliva Trejo JA, Kaneda H, Omotehara T, Takechi M, Negishi-Koga T, Ishijima M, Aoto K, Iseki S, Kitamura K, Muto S, Amagasa M, Hotchi S, Ogura K, Shibata S, Sakai T, Suzuki Y, Ichimura K. Ultrastructural analysis of whole glomeruli using array tomography. J Cell Sci 2024; 137:jcs262154. [PMID: 39171439 DOI: 10.1242/jcs.262154] [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: 03/28/2024] [Accepted: 08/09/2024] [Indexed: 08/23/2024] Open
Abstract
The renal glomerulus produces primary urine from blood plasma by ultrafiltration. The ultrastructure of the glomerulus is closely related to filtration function and disease development. The ultrastructure of glomeruli has mainly been evaluated using transmission electron microscopy; however, the volume that can be observed using transmission electron microscopy is extremely limited relative to the total volume of the glomerulus. Consequently, observing structures that exist in only one location in each glomerulus, such as the vascular pole, and evaluating low-density or localized lesions are challenging tasks. Array tomography (AT) is a technique used to analyze the ultrastructure of tissues and cells via scanning electron microscopy of serial sections. In this study, we present an AT workflow that is optimized for observing complete serial sections of the whole glomerulus, and we share several analytical examples that use the optimized AT workflow, demonstrating the usefulness of this approach. Overall, this AT workflow can be a powerful tool for structural and pathological evaluation of the glomerulus. This workflow is also expected to provide new insights into the ultrastructure of the glomerulus and its constituent cells.
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Affiliation(s)
- Takayuki Miyaki
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Nozomi Homma
- Department of Nephrology, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Yuto Kawasaki
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Mami Kishi
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Junji Yamaguchi
- Laboratory of Morphology and Image Analysis, Research Core Facilities , Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Soichiro Kakuta
- Laboratory of Morphology and Image Analysis, Research Core Facilities , Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Tomoko Shindo
- Electron Microscope Laboratory, Keio University School of Medicine, Tokyo 160-0016, Japan
| | - Makoto Sugiura
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Juan Alejandro Oliva Trejo
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Hisako Kaneda
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Takuya Omotehara
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Masaki Takechi
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Takako Negishi-Koga
- Department of Medicine for Orthopedics and Motor Organ, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
- Department of Community Medicine and Research for Bone and Joint Diseases, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Muneaki Ishijima
- Department of Medicine for Orthopedics and Motor Organ, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
- Department of Community Medicine and Research for Bone and Joint Diseases, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Kazushi Aoto
- Central Laboratory, Graduate School of Biomedical and Health Sciences , Hiroshima University, Hiroshima 734-8551, Japan
| | - Sachiko Iseki
- Department of Molecular Craniofacial Embryology and Oral Histology, Graduate School of Medical and Dental Sciences , Tokyo Medical and Dental University, Tokyo 113-8510, Japan
| | - Kosuke Kitamura
- Department of Urology, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Satoru Muto
- Department of Urology, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Mao Amagasa
- Department of Human Pathology, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Shiori Hotchi
- Department of Human Pathology, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Kanako Ogura
- Department of Human Pathology, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Shinsuke Shibata
- Electron Microscope Laboratory, Keio University School of Medicine, Tokyo 160-0016, Japan
- Division of Microscopic Anatomy, Graduate School of Medical and Dental Sciences , Niigata University, Niigata City 951-8510, Japan
| | - Tatsuo Sakai
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Yusuke Suzuki
- Department of Nephrology, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
| | - Koichiro Ichimura
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
- Laboratory of Morphology and Image Analysis, Research Core Facilities , Juntendo University Graduate School of Medicine, Tokyo 113-8421, Japan
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2
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Meliambro K, He JC, Campbell KN. Podocyte-targeted therapies - progress and future directions. Nat Rev Nephrol 2024; 20:643-658. [PMID: 38724717 DOI: 10.1038/s41581-024-00843-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/19/2024] [Indexed: 09/14/2024]
Abstract
Podocytes are the key target cells for injury across the spectrum of primary and secondary proteinuric kidney disorders, which account for up to 90% of cases of kidney failure worldwide. Seminal experimental and clinical studies have established a causative link between podocyte depletion and the magnitude of proteinuria in progressive glomerular disease. However, no substantial advances have been made in glomerular disease therapies, and the standard of care for podocytopathies relies on repurposed immunosuppressive drugs. The past two decades have seen a remarkable expansion in understanding of the mechanistic basis of podocyte injury, with prospects increasing for precision-based treatment approaches. Dozens of disease-causing genes with roles in the pathogenesis of clinical podocytopathies have been identified, as well as a number of putative glomerular permeability factors. These achievements, together with the identification of novel targets of podocyte injury, the development of potential approaches to harness the endogenous podocyte regenerative potential of progenitor cell populations, ongoing clinical trials of podocyte-specific pharmacological agents and the development of podocyte-directed drug delivery systems, contribute to an optimistic outlook for the future of glomerular disease therapy.
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Affiliation(s)
- Kristin Meliambro
- Department of Medicine, Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - John C He
- Department of Medicine, Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Kirk N Campbell
- Department of Medicine, Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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3
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Wang P, Yang J, Dai S, Gao P, Qi Y, Zhao X, Liu J, Wang Y, Gao Y. miRNA-193a-mediated WT1 suppression triggers podocyte injury through activation of the EZH2/β-catenin/NLRP3 pathway in children with diabetic nephropathy. Exp Cell Res 2024; 442:114238. [PMID: 39251057 DOI: 10.1016/j.yexcr.2024.114238] [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: 03/04/2024] [Revised: 08/19/2024] [Accepted: 09/04/2024] [Indexed: 09/11/2024]
Abstract
Diabetic nephropathy (DN), an eminent etiology of renal disease in patients with diabetes, involves intricate molecular mechanisms. Recent investigations have elucidated microRNA-193a (miR-193a) as a pivotal modulator in DN, although its precise function in podocyte impairment remains obscure. The present study investigated the role of miR-193a in podocyte injury via the WT1/EZH2/β-catenin/NLRP3 pathway. This study employed a comprehensive experimental approach involving both in vitro and in vivo analyses. We utilized human podocyte cell lines and renal biopsy samples from pediatric patients with DN. The miR-193a expression levels in podocytes and glomeruli were quantified via qRT‒PCR. Western blotting and immunofluorescence were used to assess the expression of WT1, EZH2, β-catenin, and NLRP3 inflammasome components. Additionally, the study used luciferase reporter assays to confirm the interaction between miR-193a and WT1. The impact of miR-193a manipulation was observed by overexpressing WT1 and inhibiting miR-193a in podocytes, followed by analysis of downstream pathway activation and inflammatory markers. We found upregulated miR-193a in podocytes and glomeruli, which directly targeted and suppressed WT1, a crucial podocyte transcription factor. WT1 suppression, in turn, activated the EZH2/β-catenin/NLRP3 pathway, leading to inflammasome assembly and proinflammatory cytokine production. Overexpression of WT1 or inhibition of miR-193a attenuated these effects, protecting podocytes from injury. This study identified a novel mechanism by which miR-193a-mediated WT1 suppression triggers podocyte injury in DN via the EZH2/β-catenin/NLRP3 pathway. Targeting this pathway or inhibiting miR-193a may be potential therapeutic strategies for DN.
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Affiliation(s)
- Peng Wang
- Pediatrics Department, Nanyang Second General Hospital, Nanyang, 473000, Henan, PR China
| | - Jing Yang
- Department of Infection, Children's Hospital of Nanjing Medical University, Nanjing, Jiangsu, 210000, PR China
| | - Shasha Dai
- Department of Infection, Children's Hospital of Nanjing Medical University, Nanjing, Jiangsu, 210000, PR China
| | - Pinli Gao
- Pediatrics Department, Nanyang Second General Hospital, Nanyang, 473000, Henan, PR China
| | - Ying Qi
- Pediatrics Department, Nanyang Second General Hospital, Nanyang, 473000, Henan, PR China
| | - Xiaowei Zhao
- Pediatrics Department, Nanyang Second General Hospital, Nanyang, 473000, Henan, PR China
| | - Juan Liu
- Pediatrics Department, Nanyang Second General Hospital, Nanyang, 473000, Henan, PR China
| | - Yingying Wang
- Pediatrics Department, Nanyang Second General Hospital, Nanyang, 473000, Henan, PR China
| | - Yang Gao
- Pediatrics Department, Nanyang Second General Hospital, Nanyang, 473000, Henan, PR China.
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4
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Bărar AA, Pralea IE, Maslyennikov Y, Munteanu R, Berindan-Neagoe I, Pîrlog R, Rusu I, Nuțu A, Rusu CC, Moldovan DT, Potra AR, Tirinescu D, Ticala M, Elec FI, Iuga CA, Kacso IM. Minimal Change Disease: Pathogenetic Insights from Glomerular Proteomics. Int J Mol Sci 2024; 25:5613. [PMID: 38891801 PMCID: PMC11171934 DOI: 10.3390/ijms25115613] [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: 03/15/2024] [Revised: 05/13/2024] [Accepted: 05/15/2024] [Indexed: 06/21/2024] Open
Abstract
The mechanism underlying podocyte dysfunction in minimal change disease (MCD) remains unknown. This study aimed to shed light on the potential pathophysiology of MCD using glomerular proteomic analysis. Shotgun proteomics using label-free quantitative mass spectrometry was performed on formalin-fixed, paraffin-embedded (FFPE) renal biopsies from two groups of samples: control (CTR) and MCD. Glomeruli were excised from FFPE renal biopsies using laser capture microdissection (LCM), and a single-pot solid-phase-enhanced sample preparation (SP3) digestion method was used to improve yield and protein identifications. Principal component analysis (PCA) revealed a distinct separation between the CTR and MCD groups. Forty-eight proteins with different abundance between the two groups (p-value ≤ 0.05 and |FC| ≥ 1.5) were identified. These may represent differences in podocyte structure, as well as changes in endothelial or mesangial cells and extracellular matrix, and some were indeed found in several of these structures. However, most differentially expressed proteins were linked to the podocyte cytoskeleton and its dynamics. Some of these proteins are known to be involved in focal adhesion (NID1 and ITGA3) or slit diaphragm signaling (ANXA2, TJP1 and MYO1C), while others are structural components of the actin and microtubule cytoskeleton of podocytes (ACTR3 and NES). This study suggests the potential of mass spectrometry-based shotgun proteomic analysis with LCM glomeruli to yield valuable insights into the pathogenesis of podocytopathies like MCD. The most significantly dysregulated proteins in MCD could be attributable to cytoskeleton dysfunction or may be a compensatory response to cytoskeleton malfunction caused by various triggers.
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Affiliation(s)
- Andrada Alina Bărar
- Department of Nephrology, Faculty of Medicine, “Iuliu Hațieganu” University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania; (A.A.B.); (Y.M.); (C.C.R.); (D.T.M.); (A.R.P.); (D.T.); (M.T.); (I.M.K.)
| | - Ioana-Ecaterina Pralea
- Department of Proteomics and Metabolomics, Research Center for Advanced Medicine–MedFuture, “Iuliu Hațieganu” University of Medicine and Pharmacy Cluj-Napoca, Louis Pasteur Street 4-6, 400349 Cluj-Napoca, Romania;
| | - Yuriy Maslyennikov
- Department of Nephrology, Faculty of Medicine, “Iuliu Hațieganu” University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania; (A.A.B.); (Y.M.); (C.C.R.); (D.T.M.); (A.R.P.); (D.T.); (M.T.); (I.M.K.)
| | - Raluca Munteanu
- Department of In Vivo Studies, Research Center for Advanced Medicine–MedFuture, “Iuliu Hațieganu” University of Medicine and Pharmacy Cluj-Napoca, Louis Pasteur Street 6, 400349 Cluj-Napoca, Romania;
| | - Ioana Berindan-Neagoe
- Research Center for Functional Genomics, Biomedicine and Translational Medicine, “Iuliu Hațieganu” University of Medicine and Pharmacy, 400337 Cluj-Napoca, Romania; (I.B.-N.); (R.P.); (A.N.)
| | - Radu Pîrlog
- Research Center for Functional Genomics, Biomedicine and Translational Medicine, “Iuliu Hațieganu” University of Medicine and Pharmacy, 400337 Cluj-Napoca, Romania; (I.B.-N.); (R.P.); (A.N.)
| | - Ioana Rusu
- Department of Pathology, Regional Institute of Gastroenterology and Hepatology, 400394 Cluj-Napoca, Romania;
| | - Andreea Nuțu
- Research Center for Functional Genomics, Biomedicine and Translational Medicine, “Iuliu Hațieganu” University of Medicine and Pharmacy, 400337 Cluj-Napoca, Romania; (I.B.-N.); (R.P.); (A.N.)
| | - Crina Claudia Rusu
- Department of Nephrology, Faculty of Medicine, “Iuliu Hațieganu” University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania; (A.A.B.); (Y.M.); (C.C.R.); (D.T.M.); (A.R.P.); (D.T.); (M.T.); (I.M.K.)
| | - Diana Tania Moldovan
- Department of Nephrology, Faculty of Medicine, “Iuliu Hațieganu” University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania; (A.A.B.); (Y.M.); (C.C.R.); (D.T.M.); (A.R.P.); (D.T.); (M.T.); (I.M.K.)
| | - Alina Ramona Potra
- Department of Nephrology, Faculty of Medicine, “Iuliu Hațieganu” University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania; (A.A.B.); (Y.M.); (C.C.R.); (D.T.M.); (A.R.P.); (D.T.); (M.T.); (I.M.K.)
| | - Dacian Tirinescu
- Department of Nephrology, Faculty of Medicine, “Iuliu Hațieganu” University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania; (A.A.B.); (Y.M.); (C.C.R.); (D.T.M.); (A.R.P.); (D.T.); (M.T.); (I.M.K.)
| | - Maria Ticala
- Department of Nephrology, Faculty of Medicine, “Iuliu Hațieganu” University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania; (A.A.B.); (Y.M.); (C.C.R.); (D.T.M.); (A.R.P.); (D.T.); (M.T.); (I.M.K.)
| | - Florin Ioan Elec
- Department of Urology, Faculty of Medicine, “Iuliu Hațieganu” University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania;
| | - Cristina Adela Iuga
- Department of Proteomics and Metabolomics, Research Center for Advanced Medicine–MedFuture, “Iuliu Hațieganu” University of Medicine and Pharmacy Cluj-Napoca, Louis Pasteur Street 4-6, 400349 Cluj-Napoca, Romania;
- Department of Pharmaceutical Analysis, Faculty of Pharmacy, “Iuliu Hațieganu” University of Medicine and Pharmacy, 400349 Cluj-Napoca, Romania
| | - Ina Maria Kacso
- Department of Nephrology, Faculty of Medicine, “Iuliu Hațieganu” University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania; (A.A.B.); (Y.M.); (C.C.R.); (D.T.M.); (A.R.P.); (D.T.); (M.T.); (I.M.K.)
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Saito K, Yokawa S, Kurihara H, Yaoita E, Mizuta S, Tada K, Oda M, Hatakeyama H, Ohta Y. FilGAP controls cell-extracellular matrix adhesion and process formation of kidney podocytes. FASEB J 2024; 38:e23504. [PMID: 38421271 DOI: 10.1096/fj.202301691rr] [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: 08/21/2023] [Revised: 01/17/2024] [Accepted: 02/07/2024] [Indexed: 03/02/2024]
Abstract
The function of kidney podocytes is closely associated with actin cytoskeleton regulated by Rho small GTPases. Loss of actin-driven cell adhesions and processes is connected to podocyte dysfunction, proteinuria, and kidney diseases. FilGAP, a GTPase-activating protein for Rho small GTPase Rac1, is abundantly expressed in kidney podocytes, and its gene is linked to diseases in a family with focal segmental glomerulosclerosis. In this study, we have studied the role of FilGAP in podocytes in vitro. Depletion of FilGAP in cultured podocytes induced loss of actin stress fibers and increased Rac1 activity. Conversely, forced expression of FilGAP increased stress fiber formation whereas Rac1 activation significantly reduced its formation. FilGAP localizes at the focal adhesion (FA), an integrin-based protein complex closely associated with stress fibers, that mediates cell-extracellular matrix (ECM) adhesion, and FilGAP depletion decreased FA formation and impaired attachment to the ECM. Moreover, in unique podocyte cell cultures capable of inducing the formation of highly organized processes including major processes and foot process-like projections, FilGAP depletion or Rac1 activation decreased the formation of these processes. The reduction of FAs and process formations in FilGAP-depleted podocyte cells was rescued by inhibition of Rac1 or P21-activated kinase 1 (PAK1), a downstream effector of Rac1, and PAK1 activation inhibited their formations. Thus, FilGAP contributes to both cell-ECM adhesion and process formation of podocytes by suppressing Rac1/PAK1 signaling.
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Affiliation(s)
- Koji Saito
- Division of Cell Biology, Department of Biosciences, School of Science, Kitasato University, Sagamihara, Kanagawa, Japan
| | - Seiji Yokawa
- Division of Cell Biology, Department of Biosciences, School of Science, Kitasato University, Sagamihara, Kanagawa, Japan
| | - Hidetake Kurihara
- Department of Physical Therapy, Faculty of Health Sciences, Aino University, Osaka, Ibaraki, Japan
| | - Eishin Yaoita
- Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Niigata, Japan
| | - Sari Mizuta
- Division of Cell Biology, Department of Biosciences, School of Science, Kitasato University, Sagamihara, Kanagawa, Japan
| | - Kanae Tada
- Division of Cell Biology, Department of Biosciences, School of Science, Kitasato University, Sagamihara, Kanagawa, Japan
| | - Moemi Oda
- Division of Cell Biology, Department of Biosciences, School of Science, Kitasato University, Sagamihara, Kanagawa, Japan
| | - Hiroyasu Hatakeyama
- Department of Physiology, School of Medicine, Kitasato University, Sagamihara, Kanagawa, Japan
| | - Yasutaka Ohta
- Division of Cell Biology, Department of Biosciences, School of Science, Kitasato University, Sagamihara, Kanagawa, Japan
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6
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Vickery JM, Toperzer JD, Raab JE, Lenz LL, Colgan SP, Russo BC. Synaptopodin is necessary for Shigella flexneri intercellular spread. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.25.537990. [PMID: 37163027 PMCID: PMC10168286 DOI: 10.1101/2023.04.25.537990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
For many intracellular pathogens, their virulence depends on an ability to spread between cells of an epithelial layer. For intercellular spread to occur, these pathogens deform the plasma membrane into a protrusion structure that is engulfed by the neighboring cell. Although the polymerization of actin is essential for spread, how these pathogens manipulate the actin cytoskeleton in a manner that enables protrusion formation is still incompletely understood. Here, we identify the mammalian actin binding protein synaptopodin as required for efficient intercellular spread. Using a model cytosolic pathogen, Shigella flexneri , we show that synaptopodin contributes to organization of actin around bacteria and increases the length of the actin tail at the posterior pole of the bacteria. We show that synaptopodin presence enables protrusions to form and to resolve at a greater rate, indicating that greater stability of the actin tail enables the bacteria to push against the membrane with greater force. We demonstrate that synaptopodin recruitment around bacteria requires the bacterial protein IcsA, and we show that this recruitment is further enhanced in a type 3 secretion system dependent manner. These data establish synaptopodin as required for intracellular bacteria to reprogram the actin cytoskeleton in a manner that enables efficient protrusion formation and enhance our understanding of the cellular function of synaptopodin. Authors Summary Intercellular spread is essential for many cytosolic dwelling pathogens during their infectious life cycle. Despite knowing the steps required for intercellular spread, relatively little is known about the host-pathogen interactions that enable these steps to occur. Here, we identify a requirement for the actin binding protein synaptopodin during intercellular spread by cytosolic bacteria. We show synaptopodin is necessary for the stability and recruitment of polymerized actin around bacteria. We also demonstrate synaptopodin is necessary to form plasma membrane structures known as protrusions that are necessary for the movement of these bacteria between cells. Thus, these findings implicate synaptopodin as an important actin-binding protein for the virulence of intracellular pathogens that require the actin cytoskeleton for their spread between cells.
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7
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Burt MA, Kalejaiye TD, Bhattacharya R, Dimitrakakis N, Musah S. Adriamycin-Induced Podocyte Injury Disrupts the YAP-TEAD1 Axis and Downregulates Cyr61 and CTGF Expression. ACS Chem Biol 2022; 17:3341-3351. [PMID: 34890187 DOI: 10.1021/acschembio.1c00678] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The most severe forms of kidney diseases are often associated with irreversible damage to the glomerular podocytes, the highly specialized epithelial cells that encase glomerular capillaries and regulate the removal of toxins and waste from the blood. Several studies revealed significant changes to podocyte cytoskeletal structure during disease onset, suggesting possible roles of cellular mechanosensing in podocyte responses to injury. Still, this topic remains underexplored partly due to the lack of appropriate in vitro models that closely recapitulate human podocyte biology. Here, we leveraged our previously established method for the derivation of mature podocytes from human induced pluripotent stem cells (hiPSCs) to help uncover the roles of yes-associated protein (YAP), a transcriptional coactivator and mechanosensor, in podocyte injury response. We found that while the total expression levels of YAP remain relatively unchanged during Adriamycin (ADR)-induced podocyte injury, the YAP target genes connective tissue growth factor (CTGF) and cysteine-rich angiogenic inducer 61 (Cyr61) are significantly downregulated. Intriguingly, TEAD1 is significantly downregulated in podocytes injured with ADR. By examining multiple independent modes of cellular injury, we found that CTGF and Cyr61 expression are downregulated only when podocytes were exposed to molecules known to disrupt the cell's mechanical integrity or cytoskeletal structure. To our knowledge, this is the first report that the YAP-TEAD1 signaling axis is disrupted when stem cell-derived human podocytes experience biomechanical injury. Together, these results could help improve the understanding of kidney disease mechanisms and highlight CTGF and Cyr61 as potential therapeutic targets or biomarkers for patient stratification.
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Affiliation(s)
- Morgan A Burt
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
| | - Titilola D Kalejaiye
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
| | - Rohan Bhattacharya
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
- Center for Biomolecular and Tissue Engineering, Duke University, Durham, North Carolina 27708, United States
| | - Nikolaos Dimitrakakis
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts 02115, United States
| | - Samira Musah
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
- Center for Biomolecular and Tissue Engineering, Duke University, Durham, North Carolina 27708, United States
- Department of Medicine, Division of Nephrology, Duke University School of Medicine, Durham, North Carolina 27710, United States
- Department of Cell Biology, Duke University, Durham, North Carolina 27710, United States
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8
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Wang S, Zhang X, Wang Q, Wang R. Histone modification in podocyte injury of diabetic nephropathy. J Mol Med (Berl) 2022; 100:1373-1386. [PMID: 36040515 DOI: 10.1007/s00109-022-02247-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 07/31/2022] [Accepted: 08/17/2022] [Indexed: 11/24/2022]
Abstract
Diabetic nephropathy (DN), an important complication of diabetic microvascular disease, is one of the leading causes of end-stage renal disease (ESRD), which brings heavy burdens to the whole society. Podocytes are terminally differentiated glomerular cells, which act as a pivotal component of glomerular filtration barrier. When podocytes are injured, glomerular filtration barrier is damaged, and proteinuria would occur. Dysfunction of podocytes contributes to DN. And degrees of podocyte injury influence prognosis of DN. Growing evidences have shown that epigenetics does a lot in the evolvement of podocyte injury. Epigenetics includes DNA methylation, histone modification, and non-coding RNA. Among them, histone modification plays an indelible role. Histone modification includes histone methylation, histone acetylation, and other modifications such as histone phosphorylation, histone ubiquitination, histone ADP-ribosylation, histone crotonylation, and histone β-hydroxybutyrylation. It can affect chromatin structure and regulate gene transcription to exert its function. This review is to summarize documents about pathogenesis of podocyte injury, most importantly, histone modification of podocyte injury in DN recently to provide new ideas for further molecular research, diagnosis, and treatment.
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Affiliation(s)
- Simeng Wang
- Department of Nephrology, Shandong Provincial Hospital, Shandong University, Jinan, 250012, Shandong, China
| | - Xinyu Zhang
- Department of Nephrology, Shandong Provincial Hospital, Shandong University, Jinan, 250012, Shandong, China
| | - Qinglian Wang
- Department of Nephrology, Shandong Provincial Hospital, Shandong University, Jinan, 250012, Shandong, China. .,Department of Nephrology, Shandong Provincial Hospital, Shandong First Medical University, No. 324 Jingwu Street, Jinan, 250021, Shandong, China.
| | - Rong Wang
- Department of Nephrology, Shandong Provincial Hospital, Shandong University, Jinan, 250012, Shandong, China. .,Department of Nephrology, Shandong Provincial Hospital, Shandong First Medical University, No. 324 Jingwu Street, Jinan, 250021, Shandong, China.
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9
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Mason WJ, Jafree DJ, Pomeranz G, Kolatsi-Joannou M, Rottner AK, Pacheco S, Moulding DA, Wolf A, Kupatt C, Peppiatt-Wildman C, Papakrivopoulou E, Riley PR, Long DA, Vasilopoulou E. Systemic gene therapy with thymosin β4 alleviates glomerular injury in mice. Sci Rep 2022; 12:12172. [PMID: 35842494 PMCID: PMC9288454 DOI: 10.1038/s41598-022-16287-z] [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: 03/08/2022] [Accepted: 07/07/2022] [Indexed: 11/17/2022] Open
Abstract
Plasma ultrafiltration in the kidney occurs across glomerular capillaries, which are surrounded by epithelial cells called podocytes. Podocytes have a unique shape maintained by a complex cytoskeleton, which becomes disrupted in glomerular disease resulting in defective filtration and albuminuria. Lack of endogenous thymosin β4 (TB4), an actin sequestering peptide, exacerbates glomerular injury and disrupts the organisation of the podocyte actin cytoskeleton, however, the potential of exogenous TB4 therapy to improve podocyte injury is unknown. Here, we have used Adriamycin (ADR), a toxin which injures podocytes and damages the glomerular filtration barrier leading to albuminuria in mice. Through interrogating single-cell RNA-sequencing data of isolated glomeruli we demonstrate that ADR injury results in reduced levels of podocyte TB4. Administration of an adeno-associated viral vector encoding TB4 increased the circulating level of TB4 and prevented ADR-induced podocyte loss and albuminuria. ADR injury was associated with disorganisation of the podocyte actin cytoskeleton in vitro, which was ameliorated by treatment with exogenous TB4. Collectively, we propose that systemic gene therapy with TB4 prevents podocyte injury and maintains glomerular filtration via protection of the podocyte cytoskeleton thus presenting a novel treatment strategy for glomerular disease.
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Affiliation(s)
- William J Mason
- Division of Natural Sciences, Medway School of Pharmacy, University of Kent, Chatham, Kent, UK.,Developmental Biology and Cancer Programme, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Daniyal J Jafree
- Developmental Biology and Cancer Programme, UCL Great Ormond Street Institute of Child Health, London, UK.,UCL MB/PhD Programme, Faculty of Medical Science, University College London, London, UK
| | - Gideon Pomeranz
- Developmental Biology and Cancer Programme, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Maria Kolatsi-Joannou
- Developmental Biology and Cancer Programme, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Antje K Rottner
- Developmental Biology and Cancer Programme, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Sabrina Pacheco
- Developmental Biology and Cancer Programme, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Dale A Moulding
- Developmental Biology and Cancer Programme, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Anja Wolf
- Medizinische Klinik und Poliklinik I, University Clinic Rechts der Isar, TUM Munich, Munich, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Munich Heart Alliance, Munich, Germany
| | - Christian Kupatt
- Medizinische Klinik und Poliklinik I, University Clinic Rechts der Isar, TUM Munich, Munich, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Munich Heart Alliance, Munich, Germany
| | | | - Eugenia Papakrivopoulou
- Developmental Biology and Cancer Programme, UCL Great Ormond Street Institute of Child Health, London, UK.,Department of Internal Medicine and Nephrology, Clinique Saint Jean, Brussels, Belgium
| | - Paul R Riley
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - David A Long
- Developmental Biology and Cancer Programme, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Elisavet Vasilopoulou
- Division of Natural Sciences, Medway School of Pharmacy, University of Kent, Chatham, Kent, UK. .,Developmental Biology and Cancer Programme, UCL Great Ormond Street Institute of Child Health, London, UK. .,Comparative Biomedical Sciences, The Royal Veterinary College, Royal College Street, London, NW1 0TU, UK.
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10
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Liu W, Li Y, Xu L, Wang G, Ma X, Wang Y. Biomimic Heterostructured Graphene Oxide Membranes via Supramolecular-Mediated Intercalation Assembly for Efficient Water Transport. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2200461. [PMID: 35384313 DOI: 10.1002/smll.202200461] [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: 01/21/2022] [Revised: 03/13/2022] [Indexed: 06/14/2023]
Abstract
Two-dimensional (2D) lamellar membranes have attracted increasing attention for efficient water purification. However, the low water-permeability, structural failure in aqua and high production cost have significantly restricted their practical large-scale applications. Inspired by the structures of glomerular filtration barrier (GFB) and nacre, a high-performance biomimic membrane via supramolecular-mediated intercalation assembly is reported, where rod-shaped cyclodextrin (CD) functionalized attapulgite (ATP-CD) is intercalated into CD-modified graphene oxide (GO-CD) lamellar channels, followed by locking adjacent ATP-CD and GO-CD through tannic acid (TA) and CD supramolecular networks. The formed GFB-like heterostructure endows the membrane with excellent water transport capability and the bionic "brick and mortar" nacre configuration boosts its anti-swelling stability simultaneously. The heterostructured GO membranes (≈100 nm) fabricated in this way exhibit a good water permeability of 55.6 L m-2 h-1 bar-1 (≈20-fold higher than GO membrane) maintaining excellent dye rejection of >99% during 480 h immersion. Given the low-cost materials (ATP, CD, and TA) and the modification generality, this economic strategy can hopefully achieve large-scale membrane fabrication and afford high applicability, which promotes the practical engineering applications of such 2D material membranes.
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Affiliation(s)
- Wei Liu
- Department of Chemistry, School of Science, Tianjin University, Tianjin, 300072, China
| | - Yuan Li
- Department of Chemistry, School of Science, Tianjin University, Tianjin, 300072, China
| | - Linlin Xu
- Department of Chemical Engineering, University College London, London, WC1E 7JE, UK
| | - Gang Wang
- School of Chemistry and Chemical Engineering, Qinghai Nationalities University, Qinghai, 810007, China
| | - Xiaofei Ma
- Department of Chemistry, School of Science, Tianjin University, Tianjin, 300072, China
| | - Yong Wang
- Department of Chemistry, School of Science, Tianjin University, Tianjin, 300072, China
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11
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Chen J, Wang X, He Q, Harris RC. TAZ is important for maintenance of the integrity of podocytes. Am J Physiol Renal Physiol 2022; 322:F419-F428. [PMID: 35157550 PMCID: PMC8934679 DOI: 10.1152/ajprenal.00426.2021] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 02/01/2022] [Accepted: 02/07/2022] [Indexed: 11/22/2022] Open
Abstract
The podocyte is an important component of the glomerular filtration barrier, and maintenance of the integrity of its highly specified structure and function is critical for normal kidney function. Yes-associated protein (YAP)/transcriptional coactivator with PDZ-binding motif (TAZ) are two crucial effectors of the Hippo signaling pathway, and recent studies have shown that podocyte-specific YAP deletion causes podocyte apoptosis and the development of focal segmental glomerulosclerosis followed by progressive renal failure. In the present study, we investigated a potential role of the YAP paralog TAZ in podocytes. TAZ was found to be constitutively active in podocytes, and mice with podocyte-specific deletion of TAZ (TazpodKO) developed proteinuria starting at 4 wk of age and had increased podocyte apoptosis. Using primary cultured podocytes or immortalized mouse podocytes from Tazflox/flox mice, we found that TAZ is a transcriptional activator for TEAD-dependent expression of synaptopodin, zonula occludens-1, and zonula occludens-2. This is the first study to determine that TAZ plays an important role in the maintenance of the structure and function of podocytes.NEW & NOTEWORTHY Podocytes play an important role in maintaining the integrity of the structure and function of the kidney. We observed that mice with selective deletion of transcriptional coactivator with PDZ-binding motif (TAZ) in podocytes developed proteinuria. TAZ is constitutively active and critical for expression of synaptopodin, zonula occludens-1, and zonula occludens-2 in podocytes. The findings of this study implicate TAZ as an important mediator of podocyte structural integrity and provide further insights into the role of Hippo-Yes-associated protein/TAZ in podocyte biology.
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Affiliation(s)
- Jianchun Chen
- United States Department of Veterans Affairs, Nashville, Tennessee
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
- Vanderbilt Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Xiaoyong Wang
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Qian He
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Raymond C Harris
- United States Department of Veterans Affairs, Nashville, Tennessee
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
- Vanderbilt Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, Tennessee
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee
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12
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Greiten JK, Kliewe F, Schnarre A, Artelt N, Schröder S, Rogge H, Amann K, Daniel C, Lindenmeyer MT, Cohen CD, Endlich K, Endlich N. The role of filamins in mechanically stressed podocytes. FASEB J 2021; 35:e21560. [PMID: 33860543 DOI: 10.1096/fj.202001179rr] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 02/26/2021] [Accepted: 03/15/2021] [Indexed: 11/11/2022]
Abstract
Glomerular hypertension induces mechanical load to podocytes, often resulting in podocyte detachment and the development of glomerulosclerosis. Although it is well known that podocytes are mechanosensitive, the mechanosensors and mechanotransducers are still unknown. Since filamin A, an actin-binding protein, is already described to be a mechanosensor and mechanotransducer, we hypothesized that filamins could be important for the outside-in signaling as well as the actin cytoskeleton of podocytes under mechanical stress. In this study, we demonstrate that filamin A is the main isoform of the filamin family that is expressed in cultured podocytes. Together with filamin B, filamin A was significantly up-regulated during mechanical stretch (3 days, 0.5 Hz, and 5% extension). To study the role of filamin A in cultured podocytes under mechanical stress, filamin A was knocked down (Flna KD) by specific siRNA. Additionally, we established a filamin A knockout podocyte cell line (Flna KO) by CRISPR/Cas9. Knockdown and knockout of filamin A influenced the expression of synaptopodin, a podocyte-specific protein, focal adhesions as well as the morphology of the actin cytoskeleton. Moreover, the cell motility of Flna KO podocytes was significantly increased. Since the knockout of filamin A has had no effect on cell adhesion of podocytes during mechanical stress, we simultaneously knocked down the expression of filamin A and B. Thereby, we observed a significant loss of podocytes during mechanical stress indicating a compensatory mechanism. Analyzing hypertensive mice kidneys as well as biopsies of patients suffering from diabetic nephropathy, we found an up-regulation of filamin A in podocytes in contrast to the control. In summary, filamin A and B mediate matrix-actin cytoskeleton interactions which are essential for the adaptation of cultured podocyte to mechanical stress.
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Affiliation(s)
- Jonas K Greiten
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Felix Kliewe
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Annabel Schnarre
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Nadine Artelt
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Sindy Schröder
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Henrik Rogge
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Kerstin Amann
- Department of Nephropathology, Friedrich-Alexander University (FAU) Erlangen-Nuremberg, Erlangen, Germany
| | - Christoph Daniel
- Department of Nephropathology, Friedrich-Alexander University (FAU) Erlangen-Nuremberg, Erlangen, Germany
| | - Maja T Lindenmeyer
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Clemens D Cohen
- Nephrological Center, Medical Clinic and Policlinic IV, University of Munich, Munich, Germany
| | - Karlhans Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
| | - Nicole Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
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13
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Liern M, Colazo A, Vallejo G, Zotta E. Antiproteinuric action of amiloride in paediatric patient with corticoresistant nephrotic syndrome. Nefrologia 2021; 41:304-310. [PMID: 36166246 DOI: 10.1016/j.nefroe.2021.08.005] [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: 07/26/2020] [Accepted: 11/19/2020] [Indexed: 06/16/2023] Open
Abstract
INTRODUCCION In nephrotic syndrome, increased podocyturia accompanies pathologic proteinuria. The therapeutic regimen with enalapril, losartan and amiloride could reduce both variables. OBJETIVES Evaluate the anti-proteinuric effect of 2 non-immunological therapeutic regimens, the quantitative relationship between podocyturia and proteinuria. MATERIAL AND METHODS We included children aged 4-12 years with corticoresistant nephrotic syndrome, using 2 different schemes: group A, enalapril + losartan, and group B, enalapril + losartan + amiloride. RESULTS In group A, 17 patients completed the study, the initial mean proteinuria was 39 mg/m2/h and mean proteinuria at the end was 24 mg/m2/h, while in group B 14 patients were treated and the initial average proteinuria was 36 mg/m2/h and the end average proteinuria was 13 mg/m2/h. The paired T test showed significant differences in the decrease in proteinuria, for patients in group B without variation in podocyturia. The 2 factors associated with an increase in proteinuria were podocyturia and the time elapsed from the diagnosis of cortico-resistant nephrotic syndrome to the start of treatment anti-proteinuric. CONCLUSIONS The use of amiloride decreased proteinuria, without significantly modifying podocyturia; we did not observe a positive relationship between both variables.
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Affiliation(s)
- Miguel Liern
- Unidad de Nefrología, Hospital General de Niños Ricardo Gutiérrez, Buenos Aires, Argentina.
| | - Anabella Colazo
- Unidad de Nefrología, Hospital General de Niños Ricardo Gutiérrez, Buenos Aires, Argentina
| | - Graciela Vallejo
- Unidad de Nefrología, Hospital General de Niños Ricardo Gutiérrez, Buenos Aires, Argentina
| | - Elsa Zotta
- Departamento de Ciencias Fisiológicas IFIBIO Houssay, CONICET, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina; Cátedra de Fisiopatología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
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14
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Fukusumi Y, Yasuda H, Zhang Y, Kawachi H. Nephrin-Ephrin-B1-Na +/H + Exchanger Regulatory Factor 2-Ezrin-Actin Axis Is Critical in Podocyte Injury. THE AMERICAN JOURNAL OF PATHOLOGY 2021; 191:1209-1226. [PMID: 33887216 DOI: 10.1016/j.ajpath.2021.04.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 03/13/2021] [Accepted: 04/05/2021] [Indexed: 10/21/2022]
Abstract
Ephrin-B1 is one of the critical components of the slit diaphragm of kidney glomerular podocyte. However, the precise function of ephrin-B1 is unclear. To clarify the function of ephrin-B1, ephrin-B1-associated molecules were studied. RNA-sequencing analysis suggested that Na+/H+ exchanger regulatory factor 2 (NHERF2), a scaffolding protein, is associated with ephrin-B1. NHERF2 was expressed at the apical area and the slit diaphragm, and interacted with the nephrin-ephrin-B1 complex at the slit diaphragm. The nephrin-ephrin-B1-NHERF2 complex interacted with ezrin bound to F-actin. NHERF2 bound ephrin-B1 via its first postsynaptic density protein-95/disks large/zonula occludens-1 domain, and podocalyxin via its second postsynaptic density protein-95/disks large/zonula occludens-1 domain. Both in vitro analyses with human embryonic kidney 293 cells and in vivo study with rat nephrotic model showed that stimulaiton of the slit diaphragm, phosphorylation of nephrin and ephrin-B1, and dephosphorylation of NHERF2 and ezrin, disrupted the linkages of ephrin-B1-NHERF2 and NHERF2-ezrin. It is conceivable that the linkage of nephrin-ephrin-B1-NHERF2-ezrin-actin is a novel critical axis in the podocytes. Ephrin-B1 phosphorylation also disrupted the linkage of an apical transmembrane protein, podocalyxin, with NHERF2-ezrin-actin. The phosphorylation of ephrin-B1 and the consequent dephosphorylation of NHERF2 are critical initiation events leading to podocyte injury.
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Affiliation(s)
- Yoshiyasu Fukusumi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Hidenori Yasuda
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Ying Zhang
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Hiroshi Kawachi
- Department of Cell Biology, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
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15
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Liern M, Colazo A, Vallejo G, Zotta E. [Antiproteinuric action of amiloride in paediatric patient with corticoresistant nephrotic syndrome]. Nefrologia 2021; 41:304-310. [PMID: 33722403 DOI: 10.1016/j.nefro.2020.11.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 10/06/2020] [Accepted: 11/19/2020] [Indexed: 10/21/2022] Open
Abstract
INTRODUCCION In nephrotic syndrome, increased podocyturia accompanies pathologic proteinuria. The therapeutic regimen with enalapril, losartan and amiloride could reduce both variables. OBJETIVES Evaluate the anti-proteinuric effect of 2 non-immunological therapeutic regimens, the quantitative relationship between podocyturia and proteinuria. MATERIAL AND METHODS We included children aged 4 to 12 years with corticoresistant nephrotic syndrome, using 2 different schemes: group A, enalapril+losartan, and group B, enalapril+losartan+amiloride. RESULTS In group A, 17 patients completed the study, the initial mean proteinuria was 39mg/m2/h and mean proteinuria at the end was 24mg/m2/h, while in group B 14 patients were treated and the initial average proteinuria was 36mg/m2/h and the end average proteinuria was 13mg/m2/h. The paired T test showed significant differences in the decrease in proteinuria, for patients in group B without variation in podocyturia. The 2 factors associated with an increase in proteinuria were podocyturia and the time elapsed from the diagnosis of cortico-resistant nephrotic syndrome to the start of treatment anti-proteinuric. CONCLUSIONS The use of amiloride decreased proteinuria, without significantly modifying podocyturia; we did not observe a positive relationship between both variables.
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Affiliation(s)
- Miguel Liern
- Unidad de Nefrología, Hospital General de Niños Ricardo Gutiérrez, Buenos Aires, Argentina. Jliern@%20yahoo.com
| | - Anabella Colazo
- Unidad de Nefrología, Hospital General de Niños Ricardo Gutiérrez, Buenos Aires, Argentina
| | - Graciela Vallejo
- Unidad de Nefrología, Hospital General de Niños Ricardo Gutiérrez, Buenos Aires, Argentina
| | - Elsa Zotta
- Departamento de Ciencias Fisiológicas IFIBIO Houssay, CONICET, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina; Cátedra de Fisiopatología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
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16
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Kawasaki Y, Hosoyamada Y, Miyaki T, Yamaguchi J, Kakuta S, Sakai T, Ichimura K. Three-Dimensional Architecture of Glomerular Endothelial Cells Revealed by FIB-SEM Tomography. Front Cell Dev Biol 2021; 9:653472. [PMID: 33777962 PMCID: PMC7991748 DOI: 10.3389/fcell.2021.653472] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 02/04/2021] [Indexed: 11/29/2022] Open
Abstract
Focused-ion beam-scanning electron microscopic (FIB-SEM) tomography enables easier acquisition of a series of ultrastructural, sectional images directly from resin-embedded biological samples. In this study, to clarify the three-dimensional (3D) architecture of glomerular endothelial cells (GEnCs) in adult rats, we manually extracted GEnCs from serial FIB-SEM images and reconstructed them on an Amira reconstruction software. The luminal and basal surface structures were clearly visualized in the reconstructed GEnCs, although only the luminal surface structures could be observed by conventional SEM. The luminal surface visualized via the reconstructed GEnCs was quite similar to that observed through conventional SEM, indicating that 3D reconstruction could be performed with high accuracy. Thus, we successfully described the 3D architecture of normal GEnCs in adult rats more clearly and precisely than ever before. The GEnCs were found to consist of three major subcellular compartments, namely, the cell body, cytoplasmic ridges, and sieve plates, in addition to two associated subcellular compartments, namely, the globular protrusions and reticular porous structures. Furthermore, most individual GEnCs made up a “seamless” tubular shape, and some of them formed an autocellular junction to make up a tubular shape. FIB-SEM tomography with reconstruction is a powerful approach to better understand the 3D architecture of GEnCs. Moreover, the morphological information revealed in this study will be valuable for the 3D pathologic evaluation of GEnCs in animal and human glomerular diseases and the structural analysis of developmental processes in the glomerular capillary system.
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Affiliation(s)
- Yuto Kawasaki
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Yasue Hosoyamada
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo, Japan.,Department of Nutrition, Faculty of Health Care Sciences, Chiba Prefectural University of Health Sciences, Chiba, Japan
| | - Takayuki Miyaki
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Junji Yamaguchi
- Laboratory of Morphology and Image Analysis, Research Support Center, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Soichiro Kakuta
- Laboratory of Morphology and Image Analysis, Research Support Center, 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, Research Support Center, Juntendo University Graduate School of Medicine, Tokyo, Japan
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17
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Yamada N, Doi T, Sato J, Inoue T, Tsuchitani M, Kobayashi Y. Morphological analyses of nephrin expression in progressive glomerulonephropathy of common marmosets. J Toxicol Pathol 2020; 34:83-88. [PMID: 33627947 PMCID: PMC7890167 DOI: 10.1293/tox.2020-0056] [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: 08/07/2020] [Accepted: 10/27/2020] [Indexed: 11/19/2022] Open
Abstract
In this study, we focused on nephrin, one of the key molecules within the slit diaphragm of podocytes, as although there have been reports on its expression in humans and rats, their presence in common marmosets has not been reported. We investigated nephrin expression and changes in glomeruli, depending on the development of spontaneous progressive glomerulonephropathy in common marmosets. Nineteen common marmosets at two to ten years of age were evaluated. The kidney was examined by microscopy with hematoxylin and eosin and immunohistochemical staining for nephrin. The lesions were classified into three grades according to a renal lesion grading system reported previously. The nephrin-positive area was measured by morphometric analysis, and the nephrin-positive ratio was calculated. Nephrin expression was observed along the glomerular capillary loop in a continuous linear pattern in renal lesion grades 0 to 2 and either discontinuous linear or coarse granular pattern in grade 3. Nephrin expression tended to decrease significantly depending on the grade of renal lesions. Alteration in nephrin expression has been suggested to play an important role in the progression of renal lesions.
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Affiliation(s)
- Naoaki Yamada
- Pathology Department, Kashima Laboratories, LSIM Safety Institute Corporation, 14-1 Sunayama, Kamisu-shi, Ibaraki, 314-0255, Japan
| | - Takuya Doi
- Pathology Department, Kashima Laboratories, LSIM Safety Institute Corporation, 14-1 Sunayama, Kamisu-shi, Ibaraki, 314-0255, Japan
| | - Junko Sato
- Pathology Department, Kashima Laboratories, LSIM Safety Institute Corporation, 14-1 Sunayama, Kamisu-shi, Ibaraki, 314-0255, Japan
| | - Takeshi Inoue
- Marmoset Research Department, Central Institute for Experimental Animals, 3-25-12 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa, 210-0821, Japan
| | - Minoru Tsuchitani
- Pathology Department, Kashima Laboratories, LSIM Safety Institute Corporation, 14-1 Sunayama, Kamisu-shi, Ibaraki, 314-0255, Japan
| | - Yoshiyasu Kobayashi
- Laboratory of Veterinary Pathology, Division of Pathological Science, Department of Basic Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, 2-11 Inada-cho, Obihiro, Hokkaido 080-8555, Japan
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18
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Kwiatkowska E, Stefańska K, Zieliński M, Sakowska J, Jankowiak M, Trzonkowski P, Marek-Trzonkowska N, Kwiatkowski S. Podocytes-The Most Vulnerable Renal Cells in Preeclampsia. Int J Mol Sci 2020; 21:ijms21145051. [PMID: 32708979 PMCID: PMC7403979 DOI: 10.3390/ijms21145051] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/14/2020] [Accepted: 07/14/2020] [Indexed: 12/24/2022] Open
Abstract
Preeclampsia (PE) is a disorder that affects 3–5% of normal pregnancies. It was believed for a long time that the kidney, similarly to all vessels in the whole system, only sustained endothelial damage. The current knowledge gives rise to a presumption that the main role in the development of proteinuria is played by damage to the podocytes and their slit diaphragm. The podocyte damage mechanism in preeclampsia is connected to free VEGF and nitric oxide (NO) deficiency, and an increased concentration of endothelin-1 and oxidative stress. From national cohort studies, we know that women who had preeclampsia in at least one pregnancy carried five times the risk of developing end-stage renal disease (ESRD) when compared to women with physiological pregnancies. The focal segmental glomerulosclerosis (FSGS) is the dominant histopathological lesion in women with a history of PE. The kidney’s podocytes are not subject to replacement or proliferation. Podocyte depletion exceeding 20% resulted in FSGS, which is a reason for the later development of ESRD. In this review, we present the mechanism of kidney (especially podocytes) injury in preeclampsia. We try to explain how this damage affects further changes in the morphology and function of the kidneys after pregnancy.
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Affiliation(s)
- Ewa Kwiatkowska
- Clinical Department of Nephrology, Transplantology and Internal Medicine, Pomeranian Medical University, 70-111 Szczecin, Poland;
| | - Katarzyna Stefańska
- Department of Obstetrics, Medical University of Gdańsk, 80-210 Gdańsk, Poland
- Correspondence:
| | - Maciej Zieliński
- Department of Medical Immunology, Medical University of Gdańsk, 80-210 Gdańsk, Poland; (M.Z.); (J.S.); (M.J.); (P.T.)
| | - Justyna Sakowska
- Department of Medical Immunology, Medical University of Gdańsk, 80-210 Gdańsk, Poland; (M.Z.); (J.S.); (M.J.); (P.T.)
| | - Martyna Jankowiak
- Department of Medical Immunology, Medical University of Gdańsk, 80-210 Gdańsk, Poland; (M.Z.); (J.S.); (M.J.); (P.T.)
| | - Piotr Trzonkowski
- Department of Medical Immunology, Medical University of Gdańsk, 80-210 Gdańsk, Poland; (M.Z.); (J.S.); (M.J.); (P.T.)
| | - Natalia Marek-Trzonkowska
- International Centre for Cancer Vaccine Science Cancer Immunology Group, University of Gdansk, 80-822 Gdańsk, Poland;
- Laboratory of Immunoregulation and Cellular Therapies, Department of Family Medicine, Medical University of Gdańsk, 80-210 Gdańsk, Poland
| | - Sebastian Kwiatkowski
- Department of Obstetrics and Gynecology, Pomeranian Medical University, 70-111 Szczecin, Poland;
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van der Vlag J, Buijsers B. Heparanase in Kidney Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1221:647-667. [PMID: 32274730 DOI: 10.1007/978-3-030-34521-1_26] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The primary filtration of blood occurs in the glomerulus in the kidney. Destruction of any of the layers of the glomerular filtration barrier might result in proteinuric disease. The glomerular endothelial cells and especially its covering layer, the glycocalyx, play a pivotal role in development of albuminuria. One of the main sulfated glycosaminoglycans in the glomerular endothelial glycocalyx is heparan sulfate. The endoglycosidase heparanase degrades heparan sulfate, thereby affecting glomerular barrier function, immune reactivity and inflammation. Increased expression of glomerular heparanase correlates with loss of glomerular heparan sulfate in many glomerular diseases. Most importantly, heparanase knockout in mice prevented the development of albuminuria after induction of experimental diabetic nephropathy and experimental glomerulonephritis. Therefore, heparanase could serve as a pharmacological target for glomerular diseases. Several factors that regulate heparanase expression and activity have been identified and compounds aiming to inhibit heparanase activity are currently explored.
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Affiliation(s)
- Johan van der Vlag
- Department of Nephrology (480), Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands.
| | - Baranca Buijsers
- Department of Nephrology (480), Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
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20
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Akimoto Y, Yan K, Miura Y, Tsumoto H, Toda T, Fukutomi T, Sugahara D, Kudo A, Arai T, Chiba Y, Kaname S, Hart GW, Endo T, Kawakami H. O-GlcNAcylation and phosphorylation of β-actin Ser 199 in diabetic nephropathy. Am J Physiol Renal Physiol 2019; 317:F1359-F1374. [PMID: 31566433 PMCID: PMC6879942 DOI: 10.1152/ajprenal.00566.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 08/28/2019] [Accepted: 09/08/2019] [Indexed: 12/18/2022] Open
Abstract
The function of actin is regulated by various posttranslational modifications. We have previously shown that in the kidneys of nonobese type 2 diabetes model Goto-Kakizaki rats, increased O-GlcNAcylation of β-actin protein is observed. It has also been reported that both O-GlcNAcylation and phosphorylation occur on Ser199 of β-actin. However, their roles are not known. To elucidate their roles in diabetic nephropathy, we examined the rat kidney for changes in O-GlcNAcylation of Ser199 (gS199)-actin and in the phosphorylation of Ser199 (pS199)-actin. Both gS199- and pS199-actin molecules had an apparent molecular weight of 40 kDa and were localized as nonfilamentous actin in both the cytoplasm and nucleus. Compared with the normal kidney, the immunostaining intensity of gS199-actin increased in podocytes of the glomeruli and in proximal tubules of the diabetic kidney, whereas that of pS199-actin did not change in podocytes but decreased in proximal tubules. We confirmed that the same results could be observed in the glomeruli of the human diabetic kidney. In podocytes of glomeruli cultured in the presence of the O-GlcNAcase inhibitor Thiamet G, increased O-GlcNAcylation was accompanied by a concomitant decrease in the amount of filamentous actin and in morphological changes. Our present results demonstrate that dysregulation of O-GlcNAcylation and phosphorylation of Ser199 occurred in diabetes, which may contribute partially to the causes of the morphological changes in the glomeruli and tubules. gS199- and pS199-actin will thus be useful for the pathological evaluation of diabetic nephropathy.
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Affiliation(s)
- Yoshihiro Akimoto
- Department of Anatomy, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Kunimasa Yan
- Department of Pediatrics, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Yuri Miura
- Research Team for Mechanism of Aging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| | - Hiroki Tsumoto
- Research Team for Mechanism of Aging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| | - Tosifusa Toda
- Research Team for Mechanism of Aging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| | - Toshiyuki Fukutomi
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Daisuke Sugahara
- Department of Anatomy, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Akihiko Kudo
- Department of Anatomy, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Tomio Arai
- Department of Pathology, Tokyo Metropolitan Geriatric Hospital, Itabashi, Tokyo, Japan
| | - Yuko Chiba
- Department of Diabetes, Metabolism and Endocrinology, Tokyo Metropolitan Geriatric Hospital, Itabashi, Tokyo, Japan
| | - Shinya Kaname
- Department of Nephrology and Rheumatology, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Gerald W Hart
- Center for Complex Carbohydrates, University of Georgia, Athens, Georgia
| | - Tamao Endo
- Research Team for Mechanism of Aging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| | - Hayato Kawakami
- Department of Anatomy, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
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21
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Korolj A, Laschinger C, James C, Hu E, Velikonja C, Smith N, Gu I, Ahadian S, Willette R, Radisic M, Zhang B. Curvature facilitates podocyte culture in a biomimetic platform. LAB ON A CHIP 2018; 18:3112-3128. [PMID: 30264844 DOI: 10.1039/c8lc00495a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Most kidney diseases begin with abnormalities in glomerular podocytes, motivating the need for podocyte models to study pathophysiological mechanisms and new treatment options. However, podocytes cultured in vitro face a limited ability to maintain appreciable extents of differentiation hallmarks, raising concerns over the relevance of study results. Many key properties such as nephrin expression and morphology reach plateaus that are far from the in vivo levels. Here, we demonstrate that a biomimetic topography, consisting of microhemispheres arrayed over the cell culture substrate, promotes podocyte differentiation in vitro. We define new methods for fabricating microscale curvature on various substrates, including a thin porous membrane. By growing podocytes on our topographic substrates, we found that these biophysical cues augmented nephrin gene expression, supported full-size nephrin protein expression, encouraged structural arrangement of F-actin and nephrin within the cell, and promoted process formation and even interdigitation compared to the flat substrates. Furthermore, the topography facilitated nephrin localization on curved structures while nuclei lay in the valleys between them. The improved differentiation was also evidenced by tracking barrier function to albumin over time using our custom topomembranes. Overall, our work presents accessible methods for incorporating microcurvature on various common substrates, and demonstrates the importance of biophysical stimulation in supporting higher-fidelity podocyte cultivation in vitro.
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Affiliation(s)
- Anastasia Korolj
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Canada.
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22
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Yu SMW, Nissaisorakarn P, Husain I, Jim B. Proteinuric Kidney Diseases: A Podocyte's Slit Diaphragm and Cytoskeleton Approach. Front Med (Lausanne) 2018; 5:221. [PMID: 30255020 PMCID: PMC6141722 DOI: 10.3389/fmed.2018.00221] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/18/2018] [Indexed: 01/19/2023] Open
Abstract
Proteinuric kidney diseases are a group of disorders with diverse pathological mechanisms associated with significant losses of protein in the urine. The glomerular filtration barrier (GFB), comprised of the three important layers, the fenestrated glomerular endothelium, the glomerular basement membrane (GBM), and the podocyte, dictates that disruption of any one of these structures should lead to proteinuric disease. Podocytes, in particular, have long been considered as the final gatekeeper of the GFB. This specialized visceral epithelial cell contains a complex framework of cytoskeletons forming foot processes and mediate important cell signaling to maintain podocyte health. In this review, we will focus on slit diaphragm proteins such as nephrin, podocin, TRPC6/5, as well as cytoskeletal proteins Rho/small GTPases and synaptopodin and their respective roles in participating in the pathogenesis of proteinuric kidney diseases. Furthermore, we will summarize the potential therapeutic options targeting the podocyte to treat this group of kidney diseases.
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Affiliation(s)
- Samuel Mon-Wei Yu
- Department of Medicine, Jacobi Medical Center, Bronx, NY, United States
| | | | - Irma Husain
- Department of Medicine, James J. Peters VA Medical Center, Bronx, NY, United States
| | - Belinda Jim
- Department of Medicine, Jacobi Medical Center, Bronx, NY, United States.,Renal Division, Jacobi Medical Center, Bronx, NY, United States
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23
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Liern M, Collazo A, Valencia M, Fainboin A, Isse L, Costales-Collaguazo C, Ochoa F, Vallejo G, Zotta E. Podocyturia in paediatric patients with Fabry disease. Nefrologia 2018; 39:177-183. [PMID: 30139698 DOI: 10.1016/j.nefro.2018.05.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 04/11/2018] [Accepted: 05/14/2018] [Indexed: 01/17/2023] Open
Abstract
INTRODUCTION Fabry disease (FD) is a hereditary disorder caused by a deficiency of α-galactosidase A enzyme activity. The transmission of the disorder is linked to the X chromosome. OBJECTIVES The objectives of the study were: 1. To quantify the presence of podocytes in paediatric patients with FD and compare them with the value of the measured podocyturia in healthy controls. 2. To determine whether a greater podocyturia is related to the onset of pathological albuminuria in patients with FD. 3. To determine the risk factors associated with pathological albuminuria. METHODS We performed an analytical, observational study of Fabry and control subjects, which were separated into 2groups in accordance with the absence of the disease (control group) or the presence of the disease (Fabry group). RESULTS We studied 31 patients, 11 with FD and 20 controls, with a mean age of 11.6 years. The difference between the mean time elapsed from the diagnosis of FD to the measurement of podocyturia (40 months) and the onset of pathological albuminuria (34 months) was not significant (p=0.09). Podocytes were identified by staining for the presence of synaptopodin and the mean quantitative differences between both podocyturias were statistically significant (p=0.001). Albuminuria was physiological in 4 of the patients with FD and the relative risk to develop pathological albuminuria according to podocyturia was 1.1 in the control group and 3.9 in the Fabry group, with a coefficient of correlation between podocyturia and albuminuria in the Fabry group of 0.8354. Finally, the 2 risk factors associated with the development of pathological albuminuria were podocyturia (OR: 14) and being aged over 10 years (OR: 18). We found no significant risk with regard to glomerular filtrate renal (GFR) (OR: 0.5) or gender (OR: 1.3). The mean GFR remained within normal values. CONCLUSION The detection of podocyturia in paediatric patients with FD could be used as an early marker of renal damage, preceding and proportional to the occurrence of pathological albuminuria.
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Affiliation(s)
- Miguel Liern
- Unidad de Nefrología, Hospital General de Niños Ricardo Gutiérrez, Buenos Aires, Argentina.
| | - Anabella Collazo
- Unidad de Nefrología, Hospital General de Niños Ricardo Gutiérrez, Buenos Aires, Argentina
| | - Maylin Valencia
- Unidad de Nefrología, Hospital General de Niños Ricardo Gutiérrez, Buenos Aires, Argentina
| | - Alejandro Fainboin
- Unidad de Nefrología, Hospital General de Niños Ricardo Gutiérrez, Buenos Aires, Argentina
| | - Lorena Isse
- Unidad de Nefrología, Hospital General de Niños Ricardo Gutiérrez, Buenos Aires, Argentina
| | - Cristian Costales-Collaguazo
- Departamento de Ciencias Fisiológicas IFIBIO Houssay, CONICET, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina; Cátedra de Fisiopatología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Federico Ochoa
- Departamento de Ciencias Fisiológicas IFIBIO Houssay, CONICET, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Graciela Vallejo
- Unidad de Nefrología, Hospital General de Niños Ricardo Gutiérrez, Buenos Aires, Argentina
| | - Elsa Zotta
- Departamento de Ciencias Fisiológicas IFIBIO Houssay, CONICET, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina; Cátedra de Fisiopatología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
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24
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Abstract
Podocytes exhibit a unique cytoskeletal architecture that is fundamentally linked to their function in maintaining the kidney filtration barrier. The cytoskeleton regulates podocyte shape, structure, stability, slit diaphragm insertion, adhesion, plasticity, and dynamic response to environmental stimuli. Genetic mutations demonstrate that even slight impairment of the podocyte cytoskeletal apparatus results in proteinuria and glomerular disease. Moreover, mechanisms underpinning all acquired glomerular pathologies converge on disruption of the cytoskeleton, suggesting that this subcellular structure could be targeted for therapeutic purposes. This review summarizes our current understanding of the function of the cytoskeleton in podocytes and the associated implications for pathophysiology.
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Affiliation(s)
- Christoph Schell
- Institute of Surgical Pathology and.,Department of Medicine IV, Medical Center, University of Freiburg, Faculty of Medicine, University of Freiburg, Germany
| | - Tobias B Huber
- Department of Medicine IV, Medical Center, University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; .,III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; and.,BIOSS Centre for Biological Signalling Studies and Center for Biological Systems Analysis (ZBSA), Albert-Ludwigs-University, Freiburg, Germany
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25
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Endlich K, Kliewe F, Endlich N. Stressed podocytes-mechanical forces, sensors, signaling and response. Pflugers Arch 2017; 469:937-949. [PMID: 28687864 DOI: 10.1007/s00424-017-2025-8] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 06/22/2017] [Indexed: 02/07/2023]
Abstract
Increased glomerular capillary pressure (glomerular hypertension) and increased glomerular filtration rate (glomerular hyperfiltration) have been proven to cause glomerulosclerosis in animal models and are likely to be operative in patients. Since podocytes cover the glomerular basement membrane, they are exposed to tensile stress due to circumferential wall tension and to fluid shear stress arising from filtrate flow through the narrow filtration slits and through Bowman's space. In vitro evidence documents that podocytes respond to tensile stress as well as to fluid shear stress. Several proteins are discussed in this review that are expressed in podocytes and could act as mechanosensors converting mechanical force via a conformational change into a biochemical signal. The cation channels P2X4 and TRPC6 were shown to be involved in mechanosignaling in podocytes. P2X4 is activated by stretch-induced ATP release, while TRPC6 might be inherently mechanosensitive. Membrane, slit diaphragm and cell-matrix contact proteins are connected to the sublemmal actin network in podocytes via various linker proteins. Therefore, actin-associated proteins, like the proven mechanosensor filamin, are ideal candidates to sense forces in the podocyte cytoskeleton. Furthermore, podocytes express talin, p130Cas, and fibronectin that are known to undergo a conformational change in response to mechanical force exposing cryptic binding sites. Downstream of mechanosensors, experimental evidence suggests the involvement of MAP kinases, Ca2+ and COX2 in mechanosignaling and an emerging role of YAP/TAZ. In summary, our understanding of mechanotransduction in podocytes is still sketchy, but future progress holds promise to identify targets to alleviate conditions of increased mechanical load.
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Affiliation(s)
- Karlhans Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, 17489, Greifswald, Germany.
- Institut für Anatomie and Zellbiologie, Universitätsmedizin Greifswald, Friedrich-Loeffler-Str. 23c, 17489, Greifswald, Germany.
| | - Felix Kliewe
- Department of Anatomy and Cell Biology, University Medicine Greifswald, 17489, Greifswald, Germany
| | - Nicole Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, 17489, Greifswald, Germany
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26
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Abstract
Podocytes, the postmitotic and highly branched epithelial cells of the glomerulus, play a pivotal role for the function of the glomerular filtration barrier and the development of chronic kidney disease. It has long been discussed whether podocytes in vivo are motile and can laterally migrate in a coordinated way along the capillaries until they reach the position of naked glomerular basement membrane often found in podocytopathies. Such motility would also be the prerequisite for the replacement of lost podocytes by progenitor cells. Additionally, the change of the podocyte foot processes from a normal to an effaced morphology, like it is found in many kidney diseases, would require a dynamic behavior of podocytes. Since the actin cytoskeleton is expressed in podocytes in vitro and in vivo and the morphology of podocytes is highly dependent on actin, actin-associated, and actin-regulating proteins, it was assumed that podocytes are dynamic and motile. After earlier technical limitations had been overcome and novel microscopic techniques like multiphoton microscopy had been developed, it became possible to continuously study the behavior of podocytes in living rodents and zebrafish larvae under physiological and pathological conditions. Recent in vivo microscopic studies in different model organisms suggest that lateral migration of podocytes in situ is a very unlikely event and only dynamic apical cell protrusions can be observed under pathological conditions. This review discusses recent findings concerning different forms of motility (like lateral translocative (LTM), apical translocative (ATM), and stationary motility (SM)) and their role for podocytopathies.
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Affiliation(s)
- Nicole Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, 17487, Greifswald, Germany. .,Institut für Anatomie und Zellbiologie, Universitätsmedizin Greifswald, Friedrich-Loeffler-Str. 23c, 17487, Greifswald, Germany.
| | - Florian Siegerist
- Department of Anatomy and Cell Biology, University Medicine Greifswald, 17487, Greifswald, Germany
| | - Karlhans Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, 17487, Greifswald, Germany
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27
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Reiser J, Lee HW, Gupta V, Altintas MM. A High-Content Screening Technology for Quantitatively Studying Podocyte Dynamics. Adv Chronic Kidney Dis 2017; 24:183-188. [PMID: 28501082 DOI: 10.1053/j.ackd.2017.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Podocytes form the visceral layer of a kidney glomerulus and express a characteristic octopus-like cellular architecture specialized for the ultrafiltration of blood. The cytoskeletal dynamics and structural elasticity of podocytes rely on the self-organization of highly interconnected actin bundles, and the maintenance of these features is important for the intact glomerular filtration. Development of more differentiated podocytes in culture has dramatically increased our understanding of the molecular mechanisms regulating podocyte actin dynamics. Podocytes are damaged in a variety of kidney diseases, and therapies targeting podocytes are being investigated with increasing efforts. Association between podocyte damage and disease severity-or between podocyte recovery and the performance of therapeutic molecules-have been the venues of research for years. In this perspective, more standardized high--content screening has emerged as a powerful tool for visualization and analysis of podocyte morphology. This high-throughput fluorescence microscopy technique is based on an automated image analysis with simultaneous detection of various phenotypes (multiplexing) across multiple phenotypic parameters (multiparametric). Here, we review the principles of high-content screening technology and summarize efforts to carry out small compound screen using podocytes.
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28
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Falkenberg CV, Azeloglu EU, Stothers M, Deerinck TJ, Chen Y, He JC, Ellisman MH, Hone JC, Iyengar R, Loew LM. Fragility of foot process morphology in kidney podocytes arises from chaotic spatial propagation of cytoskeletal instability. PLoS Comput Biol 2017; 13:e1005433. [PMID: 28301477 PMCID: PMC5373631 DOI: 10.1371/journal.pcbi.1005433] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 03/30/2017] [Accepted: 03/01/2017] [Indexed: 12/22/2022] Open
Abstract
Kidney podocytes' function depends on fingerlike projections (foot processes) that interdigitate with those from neighboring cells to form the glomerular filtration barrier. The integrity of the barrier depends on spatial control of dynamics of actin cytoskeleton in the foot processes. We determined how imbalances in regulation of actin cytoskeletal dynamics could result in pathological morphology. We obtained 3-D electron microscopy images of podocytes and used quantitative features to build dynamical models to investigate how regulation of actin dynamics within foot processes controls local morphology. We find that imbalances in regulation of actin bundling lead to chaotic spatial patterns that could impair the foot process morphology. Simulation results are consistent with experimental observations for cytoskeletal reconfiguration through dysregulated RhoA or Rac1, and they predict compensatory mechanisms for biochemical stability. We conclude that podocyte morphology, optimized for filtration, is intrinsically fragile, whereby local transient biochemical imbalances may lead to permanent morphological changes associated with pathophysiology.
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Affiliation(s)
- Cibele V Falkenberg
- R. D. Berlin Center for Cell Analysis & Modeling, U. Connecticut School of Medicine, Farmington, CT, United States of America
| | - Evren U Azeloglu
- Department of Pharmacological Sciences, and Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
| | - Mark Stothers
- Department of Mechanical Engineering, Columbia University, New York, NY, United States of America
| | - Thomas J Deerinck
- National Center for Microscopy and Imaging Research, UCSD, San Diego, CA, United States of America
| | - Yibang Chen
- Department of Pharmacological Sciences, and Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
| | - John C He
- Department of Pharmacological Sciences, and Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
| | - Mark H Ellisman
- National Center for Microscopy and Imaging Research, UCSD, San Diego, CA, United States of America
| | - James C Hone
- Department of Mechanical Engineering, Columbia University, New York, NY, United States of America
| | - Ravi Iyengar
- Department of Pharmacological Sciences, and Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
| | - Leslie M Loew
- R. D. Berlin Center for Cell Analysis & Modeling, U. Connecticut School of Medicine, Farmington, CT, United States of America
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29
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Trimarchi H, Canzonieri R, Schiel A, Politei J, Stern A, Andrews J, Paulero M, Rengel T, Aráoz A, Forrester M, Lombi F, Pomeranz V, Iriarte R, Young P, Muryan A, Zotta E. Podocyturia is significantly elevated in untreated vs treated Fabry adult patients. J Nephrol 2016; 29:791-797. [PMID: 26842625 DOI: 10.1007/s40620-016-0271-z] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Accepted: 01/18/2016] [Indexed: 12/20/2022]
Abstract
BACKGROUND Proteinuria suggests kidney involvement in Fabry disease. We assessed podocyturia, an early biomarker, in controls and patients with and without enzyme therapy, correlating podocyturia with proteinuria and renal function. METHODS Cross-sectional study (n = 67): controls (Group 1, n = 30) vs. Fabry disease (Group 2, n = 37) subdivided into untreated (2A, n = 19) and treated (2B, n = 18). Variables evaluated: age, gender, creatinine, CKD-EPI, proteinuria, podocyte count/10 20× microscopy power fields, podocytes/100 ml urine, podocytes/g creatininuria (results expressed as median and range). RESULTS Group 1 vs. 2 did not differ concerning age, gender and CKD-EPI, but differed regarding proteinuria and podocyturia. Group 2A vs. 2B: age: 29 (18-74) vs. 43 (18-65) years (p = ns); gender: males n = 3 (16 %) vs. n = 9 (50 %). Proteinuria was significantly higher in Fabry treated patients, while CKD-EPI and podocyturia were significantly elevated in untreated individuals. Significant correlations: group 2A: age-proteinuria, ρ = 0.62 (p = 0.0044); age-CKD-EPI, ρ = -0.84 (p < 0.0001); podocyturia-podocytes/100 ml urine, ρ = 0.99 (p = 0.0001); podocyturia-podocytes/g creatininuria ρ = 0.86 (p = 0.0003), podocytes/100 ml urine-podocytes/g urinary creatinine, ρ = 0.84 (p = 0.0004); proteinuria-CKD-EPI, ρ = -0.68 (p = 0.0013). Group 2B: podocyturia-podocytes/100 ml urine, ρ = 0.88 (p < 0.0001); podocyturia-podocytes/g creatininuria, ρ = 0.84 (p < 0.0001); podocytes/100 ml urine-podocytes/g creatininuria, ρ = 0.94 (p < 0.0001); CKD-EPI-proteinuria, ρ = -0.66 (p = 0.0028). CONCLUSIONS Patients with Fabry disease display heavy podocyturia; those untreated present significantly higher podocyturia, lower proteinuria and better renal function than those who are treated, suggesting that therapy may be started at advanced stages. Podocyturia may antedate proteinuria, and enzyme therapy may protect against podocyte loss.
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Affiliation(s)
- Hernán Trimarchi
- Nephrology, Hospital Británico de Buenos Aires, Buenos Aires, Argentina.
- Servicio de Nefrología, Hospital Británico de Buenos Aires, Perdriel 74, 1280, Buenos Aires, Argentina.
| | - Romina Canzonieri
- Biochemistry Services, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Amalia Schiel
- Biochemistry Services, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Juan Politei
- Neurology Department, Fundación para el Estudio de las Enfermedades Metabólicas FESEN, Buenos Aires, Argentina
| | - Aníbal Stern
- Biochemistry Services, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - José Andrews
- Nephrology, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Matías Paulero
- Nephrology, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Tatiana Rengel
- Nephrology, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Alicia Aráoz
- IFIBIO Houssay, UBA CONICET Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Mariano Forrester
- Nephrology, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Fernando Lombi
- Nephrology, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Vanesa Pomeranz
- Nephrology, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Romina Iriarte
- Nephrology, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Pablo Young
- Internal Medicine, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Alexis Muryan
- Biochemistry Services, Hospital Británico de Buenos Aires, Buenos Aires, Argentina
| | - Elsa Zotta
- IFIBIO Houssay, UBA CONICET Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
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30
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Abstract
Podocytes are highly specialized cells of the kidney glomerulus that wrap around capillaries and that neighbor cells of the Bowman’s capsule. When it comes to glomerular filtration, podocytes play an active role in preventing plasma proteins from entering the urinary ultrafiltrate by providing a barrier comprising filtration slits between foot processes, which in aggregate represent a dynamic network of cellular extensions. Foot processes interdigitate with foot processes from adjacent podocytes and form a network of narrow and rather uniform gaps. The fenestrated endothelial cells retain blood cells but permit passage of small solutes and an overlying basement membrane less permeable to macromolecules, in particular to albumin. The cytoskeletal dynamics and structural plasticity of podocytes as well as the signaling between each of these distinct layers are essential for an efficient glomerular filtration and thus for proper renal function. The genetic or acquired impairment of podocytes may lead to foot process effacement (podocyte fusion or retraction), a morphological hallmark of proteinuric renal diseases. Here, we briefly discuss aspects of a contemporary view of podocytes in glomerular filtration, the patterns of structural changes in podocytes associated with common glomerular diseases, and the current state of basic and clinical research.
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Affiliation(s)
- Jochen Reiser
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
| | - Mehmet M Altintas
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
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31
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Ichimura K, Sakai T. Evolutionary morphology of podocytes and primary urine-producing apparatus. Anat Sci Int 2015; 92:161-172. [PMID: 26627098 PMCID: PMC5315740 DOI: 10.1007/s12565-015-0317-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 11/14/2015] [Indexed: 01/27/2023]
Abstract
Excretory organs were acquired in the early phase of metazoan evolution, and they play a crucial role in the maintenance of homeostasis of body fluids. In general, these organs consist of two functional components, the primary-urine producing apparatus and the modulating tubule. This basic organization of the excretory organs is conserved among most metazoans. Herein, we present an overview of the morphological evolution of the primary urine-producing apparatus in metazoans and describe the acquisition of the renal glomerulus—a specialized primary urine-producing apparatus—in vertebrates. We also describe the advancement of the glomerular structure and function in higher vertebrates.
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Affiliation(s)
- Koichiro Ichimura
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan.
| | - Tatsuo Sakai
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
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32
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Martínez-García C, Izquierdo-Lahuerta A, Vivas Y, Velasco I, Yeo TK, Chen S, Medina-Gomez G. Renal Lipotoxicity-Associated Inflammation and Insulin Resistance Affects Actin Cytoskeleton Organization in Podocytes. PLoS One 2015; 10:e0142291. [PMID: 26545114 PMCID: PMC4636358 DOI: 10.1371/journal.pone.0142291] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 10/19/2015] [Indexed: 01/01/2023] Open
Abstract
In the last few decades a change in lifestyle has led to an alarming increase in the prevalence of obesity and obesity-associated complications. Obese patients are at increased risk of developing hypertension, heart disease, insulin resistance (IR), dyslipidemia, type 2 diabetes and renal disease. The excess calories are stored as triglycerides in adipose tissue, but also may accumulate ectopically in other organs, including the kidney, which contributes to the damage through a toxic process named lipotoxicity. Recently, the evidence suggests that renal lipid accumulation leads to glomerular damage and, more specifically, produces dysfunction in podocytes, key cells that compose and maintain the glomerular filtration barrier. Our aim was to analyze the early mechanisms underlying the development of renal disease associated with the process of lipotoxicity in podocytes. Our results show that treatment of podocytes with palmitic acid produced intracellular accumulation of lipid droplets and abnormal glucose and lipid metabolism. This was accompanied by the development of inflammation, oxidative stress and endoplasmic reticulum stress and insulin resistance. We found specific rearrangements of the actin cytoskeleton and slit diaphragm proteins (Nephrin, P-Cadherin, Vimentin) associated with this insulin resistance in palmitic-treated podocytes. We conclude that lipotoxicity accelerates glomerular disease through lipid accumulation and inflammation. Moreover, saturated fatty acids specifically promote insulin resistance by disturbing the cytoarchitecture of podocytes. These data suggest that renal lipid metabolism and cytoskeleton rearrangements may serve as a target for specific therapies aimed at slowing the progression of podocyte failure during metabolic syndrome.
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Affiliation(s)
- Cristina Martínez-García
- Departamento de Ciencias Básicas de la Salud, Área de Bioquímica y Genética Molecular. Universidad Rey Juan Carlos, Avda. de Atenas s/n, Alcorcón, Madrid, Spain
| | - Adriana Izquierdo-Lahuerta
- Departamento de Ciencias Básicas de la Salud, Área de Bioquímica y Genética Molecular. Universidad Rey Juan Carlos, Avda. de Atenas s/n, Alcorcón, Madrid, Spain
| | - Yurena Vivas
- Departamento de Ciencias Básicas de la Salud, Área de Bioquímica y Genética Molecular. Universidad Rey Juan Carlos, Avda. de Atenas s/n, Alcorcón, Madrid, Spain
| | - Ismael Velasco
- Departamento de Ciencias Básicas de la Salud, Área de Bioquímica y Genética Molecular. Universidad Rey Juan Carlos, Avda. de Atenas s/n, Alcorcón, Madrid, Spain
| | - Tet-Kin Yeo
- Division of Nephrology/Hypertension, Northwestern University, Chicago, Illinois, United States of America
| | - Sheldon Chen
- Division of Nephrology/Hypertension, Northwestern University, Chicago, Illinois, United States of America
| | - Gema Medina-Gomez
- Departamento de Ciencias Básicas de la Salud, Área de Bioquímica y Genética Molecular. Universidad Rey Juan Carlos, Avda. de Atenas s/n, Alcorcón, Madrid, Spain
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Jeruschke S, Jeruschke K, DiStasio A, Karaterzi S, Büscher AK, Nalbant P, Klein-Hitpass L, Hoyer PF, Weiss J, Stottmann RW, Weber S. Everolimus Stabilizes Podocyte Microtubules via Enhancing TUBB2B and DCDC2 Expression. PLoS One 2015; 10:e0137043. [PMID: 26331477 PMCID: PMC4557973 DOI: 10.1371/journal.pone.0137043] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 08/12/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Glomerular podocytes are highly differentiated cells that are key components of the kidney filtration units. The podocyte cytoskeleton builds the basis for the dynamic podocyte cytoarchitecture and plays a central role for proper podocyte function. Recent studies implicate that immunosuppressive agents including the mTOR-inhibitor everolimus have a protective role directly on the stability of the podocyte actin cytoskeleton. In contrast, a potential stabilization of microtubules by everolimus has not been studied so far. METHODS To elucidate mechanisms underlying mTOR-inhibitor mediated cytoskeletal rearrangements, we carried out microarray gene expression studies to identify target genes and corresponding pathways in response to everolimus. We analyzed the effect of everolimus in a puromycin aminonucleoside experimental in vitro model of podocyte injury. RESULTS Upon treatment with puromycin aminonucleoside, microarray analysis revealed gene clusters involved in cytoskeletal reorganization, cell adhesion, migration and extracellular matrix composition to be affected. Everolimus was capable of protecting podocytes from injury, both on transcriptional and protein level. Rescued genes included tubulin beta 2B class IIb (TUBB2B) and doublecortin domain containing 2 (DCDC2), both involved in microtubule structure formation in neuronal cells but not identified in podocytes so far. Validating gene expression data, Western-blot analysis in cultured podocytes demonstrated an increase of TUBB2B and DCDC2 protein after everolimus treatment, and immunohistochemistry in healthy control kidneys confirmed a podocyte-specific expression. Interestingly, Tubb2bbrdp/brdp mice revealed a delay in glomerular podocyte development as showed by podocyte-specific markers Wilm's tumour 1, Podocin, Nephrin and Synaptopodin. CONCLUSIONS Taken together, our study suggests that off-target, non-immune mediated effects of the mTOR-inhibitor everolimus on the podocyte cytoskeleton might involve regulation of microtubules, revealing a potential novel role of TUBB2B and DCDC2 in glomerular podocyte development.
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Affiliation(s)
- Stefanie Jeruschke
- Pediatric Nephrology, Pediatrics II, University Hospital Essen, Essen, Germany
- * E-mail:
| | - Kay Jeruschke
- Institute of Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Duesseldorf, Germany
| | - Andrew DiStasio
- Divisions of Human Genetics and Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Sinem Karaterzi
- Pediatric Nephrology, Pediatrics II, University Hospital Essen, Essen, Germany
| | - Anja K. Büscher
- Pediatric Nephrology, Pediatrics II, University Hospital Essen, Essen, Germany
| | - Perihan Nalbant
- Center for Medical Biotechnology, Molecular Cell Biology, University of Duisburg-Essen, Essen, Germany
| | | | - Peter F. Hoyer
- Pediatric Nephrology, Pediatrics II, University Hospital Essen, Essen, Germany
| | - Jürgen Weiss
- Institute of Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Duesseldorf, Germany
| | - Rolf W. Stottmann
- Divisions of Human Genetics and Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, United States of America
| | - Stefanie Weber
- Pediatric Nephrology, Pediatrics II, University Hospital Essen, Essen, Germany
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Abstract
The function of the kidney, filtering blood and concentrating metabolic waste into urine, takes place in an intricate and functionally elegant structure called the renal glomerulus. Normal glomerular function retains circulating cells and valuable macromolecular components of plasma in blood, resulting in urine with just trace amounts of proteins. Endothelial cells of glomerular capillaries, the podocytes wrapped around them, and the fused extracellular matrix these cells form altogether comprise the glomerular filtration barrier, a dynamic and highly selective filter that sieves on the basis of molecular size and electrical charge. Current understanding of the structural organization and the cellular and molecular basis of renal filtration draws from studies of human glomerular diseases and animal models of glomerular dysfunction.
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Affiliation(s)
- Rizaldy P Scott
- Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
| | - Susan E Quaggin
- Feinberg School of Medicine, Northwestern University, Chicago, IL 60611
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35
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Saito K, Shiino T, Kurihara H, Harita Y, Hattori S, Ohta Y. Afadin regulates RhoA/Rho-associated protein kinase signaling to control formation of actin stress fibers in kidney podocytes. Cytoskeleton (Hoboken) 2015; 72:146-56. [PMID: 25712270 DOI: 10.1002/cm.21211] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 01/19/2015] [Accepted: 02/20/2015] [Indexed: 11/05/2022]
Abstract
The function of kidney podocytes is closely associated with actin cytoskeleton. Rho family small GTPase RhoA promotes stress fiber assembly through Rho-associated protein kinase (ROCK)-dependent myosin II phosphorylation and plays an important role in maintenance of actin stress fibers of podocytes. However, little is known how stress fiber assembly is regulated in podocytes. Here, we found that afadin, an actin filament-binding protein, is required for RhoA/ROCK-dependent formation of actin stress fibers in rat podocyte C7 cells. We show that depletion of afadin in C7 cells induced loss of actin stress fibers. Conversely, forced expression of afadin increased the formation of actin stress fibers. Depletion of afadin inactivated RhoA and reduced the phosphorylation of myosin II. Moreover, the DIL domain of afadin appears to be responsible for actin stress fiber formation. Thus, afadin mediates RhoA/ROCK signaling and contributes to the formation of actin stress fibers in podocyte cells.
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Affiliation(s)
- Koji Saito
- Division of Cell Biology, Department of Biosciences, School of Science, Kitasato University, Kanagawa, Japan
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36
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Three-dimensional architecture of podocytes revealed by block-face scanning electron microscopy. Sci Rep 2015; 5:8993. [PMID: 25759085 PMCID: PMC4355681 DOI: 10.1038/srep08993] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 02/12/2015] [Indexed: 12/31/2022] Open
Abstract
Block-face imaging is a scanning electron microscopic technique which enables easier acquisition of serial ultrastructural images directly from the surface of resin-embedded biological samples with a similar quality to transmission electron micrographs. In the present study, we analyzed the three-dimensional architecture of podocytes using serial block-face imaging. It was previously believed that podocytes are divided into three kinds of subcellular compartment: cell body, primary process, and foot process, which are simply aligned in this order. When the reconstructed podocytes were viewed from their basal side, the foot processes were branched from a ridge-like prominence, which was formed on the basal surface of the primary process and was similar to the usual foot processes in structure. Moreover, from the cell body, the foot processes were also emerged via the ridge-like prominence, as found in the primary process. The ridge-like prominence anchored the cell body and primary process to the glomerular basement membrane, and connected the foot processes to the cell body and primary process. In conclusion, serial block-face imaging is a powerful tool for clear understanding the three-dimensional architecture of podocytes through its ability to reveal novel structures which were difficult to determine by conventional transmission and scanning electron microscopes alone.
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37
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Neal CR. Podocytes … What's Under Yours? (Podocytes and Foot Processes and How They Change in Nephropathy). Front Endocrinol (Lausanne) 2015; 6:9. [PMID: 25755650 PMCID: PMC4337384 DOI: 10.3389/fendo.2015.00009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 01/15/2015] [Indexed: 12/25/2022] Open
Abstract
Most of the described structures of podocytes in health and disease have been inferred from light and electron microscopic studies of rodent models. The variation in filtration barrier features is measured on micrographs, the aim being statistical significance. This is the technical campaign waged against kidney disease but this approach can be misleading. The signaling cascades and connectivity of the podocyte and foot processes (FPs) are inferred from in vitro studies that at best blurr the reality of the in vivo state. This review will outline actin signaling connectivity and the key differences in the structural and functional domains squeezed into the FPs and the relationship of these domains to other parts of the podocyte. It covers the changes in podocytes during nephropathy concentrating on FP and finally proposes an alternative interpretation of FP ultrastructure derived from articles published over the last 60 years.
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Affiliation(s)
- Chris R. Neal
- Bristol Renal, University of Bristol, Bristol, UK
- *Correspondence: Chris R. Neal, Bristol Renal, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol, BS1 3NY, UK e-mail:
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38
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Nakamura T, Takagi S, Matsumoto M, Tashiro F, Sakai T, Ichimura K. Expression of Nephrin Homologue in the Freshwater Planarian, Dugesia japonica. Acta Histochem Cytochem 2014; 47:303-10. [PMID: 25859064 PMCID: PMC4387267 DOI: 10.1267/ahc.14044] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 11/04/2014] [Indexed: 12/20/2022] Open
Abstract
Excretory organs contain epithelial cells that form a filtration membrane specialized for ultrafiltration to produce primary urine. In vertebrates, the filtration membrane is made up of slit diaphragm (SD) formed by glomerular podocytes. Basal metazoans such as flatworms are also known have filtration epithelial cells, called flame cells, which exhibit SD-like structures. The molecular components of podocyte SD have been studied in detail, while those of the SD-like structures in basal metazoans including flatworms remain to be clarified. To determine whether the SD-like structures in flatworms have molecular components common to the SD in vertebrate podocytes, we examined the expression of gene homologue for mammalian nephrin, which encodes an essential transmembrane protein that participates in the formation of the SD, in a species of flatworms, planarian (Dugesia japonica). Flame cells were distributed throughout the entire body of the planarian, but the nephrin-expressing cells identified by in situ hybridization were mainly detected at body periphery excluding head region. The distribution pattern of nephrin-expressing cells was similar to that of proliferating cell nuclear antigen-expressing neoblasts, which are pluripotent stem cells characteristic to planarians. These findings indicated that the SD-like structures can be formed without the Nephrin protein in planarian flame cells.
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Affiliation(s)
- Tomomi Nakamura
- Department of Biological Science and Technology, Graduate School of Industrial Science and Technology, Tokyo University of Science
- Department of Anatomy and Life Structure, Juntendo University School of Medicine
| | - Sota Takagi
- Department of Biological Sciences and Informatics, Keio University
| | - Midori Matsumoto
- Department of Biological Sciences and Informatics, Keio University
| | - Fumio Tashiro
- Department of Biological Science and Technology, Graduate School of Industrial Science and Technology, Tokyo University of Science
| | - Tatsuo Sakai
- Department of Anatomy and Life Structure, Juntendo University School of Medicine
| | - Koichiro Ichimura
- Department of Anatomy and Life Structure, Juntendo University School of Medicine
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39
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Blumenthal A, Giebel J, Warsow G, Li L, Ummanni R, Schordan S, Schordan E, Klemm P, Gretz N, Endlich K, Endlich N. Mechanical stress enhances CD9 expression in cultured podocytes. Am J Physiol Renal Physiol 2014; 308:F602-13. [PMID: 25503725 DOI: 10.1152/ajprenal.00190.2014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Elevated glomerular pressure represents a high risk for the development of severe kidney diseases and causes an increase in mechanical load to podocytes. In this study, we investigated whether mechanical stress alters gene expression in cultured podocytes using gene arrays. We found that tetraspanin CD9 is significantly upregulated in cultured podocytes after mechanical stress. The differential expression of CD9 was confirmed by RT-PCR and Western blotting under stretched and unstretched conditions. Furthermore, mechanical stress resulted in a relocalization of CD9. To get an insight into the functional role of CD9, podocytes were transfected with pEGFP-CD9. The expression of CD9 induced the formation of substratum-attached thin arborized protrusions. Ca(2+) depletion revealed that podocytes overexpressing CD9 possess altered adhesive properties in contrast to the control transfected cells. Finally, elevated CD9 expression increased migration of podocytes in a wound assay. In summary, our results suggest that upregulation of CD9 may play an important role in podocyte morphology, adhesion, and migration.
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Affiliation(s)
- A Blumenthal
- Department of Anatomy and Cell Biology, Universitätsmedizin Greifswald, Greifswald, Germany
| | - J Giebel
- Department of Anatomy and Cell Biology, Universitätsmedizin Greifswald, Greifswald, Germany;
| | - G Warsow
- Department of Anatomy and Cell Biology, Universitätsmedizin Greifswald, Greifswald, Germany
| | - L Li
- Department of Pathology, University Medical Center Göttingen, Göttingen, Germany
| | - R Ummanni
- Center for Chemical Biology, CSIR-Indian Institute of Chemical Technology, Hyderabad, India; and
| | - S Schordan
- Department of Anatomy and Cell Biology, Universitätsmedizin Greifswald, Greifswald, Germany
| | - E Schordan
- Department of Anatomy and Cell Biology, Universitätsmedizin Greifswald, Greifswald, Germany
| | - P Klemm
- Department of Anatomy and Cell Biology, Universitätsmedizin Greifswald, Greifswald, Germany
| | - N Gretz
- Medical Faculty Mannheim, Medical Research Center, University of Heidelberg, Mannheim, Germany
| | - K Endlich
- Department of Anatomy and Cell Biology, Universitätsmedizin Greifswald, Greifswald, Germany
| | - N Endlich
- Department of Anatomy and Cell Biology, Universitätsmedizin Greifswald, Greifswald, Germany
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40
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Motonishi S, Nangaku M, Wada T, Ishimoto Y, Ohse T, Matsusaka T, Kubota N, Shimizu A, Kadowaki T, Tobe K, Inagi R. Sirtuin1 Maintains Actin Cytoskeleton by Deacetylation of Cortactin in Injured Podocytes. J Am Soc Nephrol 2014; 26:1939-59. [PMID: 25424328 DOI: 10.1681/asn.2014030289] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 10/03/2014] [Indexed: 12/30/2022] Open
Abstract
Recent studies have highlighted the renoprotective effect of sirtuin1 (SIRT1), a deacetylase that contributes to cellular regulation. However, the pathophysiologic role of SIRT1 in podocytes remains unclear. Here, we investigated the function of SIRT1 in podocytes. We first established podocyte-specific Sirt1 knockout (SIRT1(pod-/-)) mice. We then induced glomerular disease by nephrotoxic serum injection. The increase in urinary albumin excretion and BUN and the severity of glomerular injury were all significantly greater in SIRT1(pod-/-) mice than in wild-type mice. Western blot analysis and immunofluorescence showed a significant decrease in podocyte-specific proteins in SIRT1(pod-/-) mice, and electron microscopy showed marked exacerbation of podocyte injury, including actin cytoskeleton derangement in SIRT1(pod-/-) mice compared with wild-type mice. Protamine sulfate-induced podocyte injury was also exacerbated by podocyte-specific SIRT1 deficiency. In vitro, actin cytoskeleton derangement in H2O2-treated podocytes became prominent when the cells were pretreated with SIRT1 inhibitors. Conversely, this H2O2-induced derangement was ameliorated by SIRT1 activation. Furthermore, SIRT1 activation deacetylated the actin-binding and -polymerizing protein cortactin in the nucleus and facilitated deacetylated cortactin localization in the cytoplasm. Cortactin knockdown or inhibition of the nuclear export of cortactin induced actin cytoskeleton derangement and dissociation of cortactin from F-actin, suggesting the necessity of cytoplasmic cortactin for maintenance of the actin cytoskeleton. Taken together, these findings indicate that SIRT1 protects podocytes and prevents glomerular injury by deacetylating cortactin and thereby, maintaining actin cytoskeleton integrity.
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Affiliation(s)
| | | | | | - Yu Ishimoto
- Divisions of Nephrology and Endocrinology and
| | | | - Taiji Matsusaka
- Department of Internal Medicine, Tokai University School of Medicine, Kanagawa, Japan
| | - Naoto Kubota
- Department of Diabetes and Metabolic Diseases, The University of Tokyo Graduate School of Medicine, Tokyo, Japan
| | - Akira Shimizu
- Department of Analytic Human Pathology, Nippon Medical School, Tokyo, Japan; and
| | - Takashi Kadowaki
- Department of Diabetes and Metabolic Diseases, The University of Tokyo Graduate School of Medicine, Tokyo, Japan
| | - Kazuyuki Tobe
- The First Department of Internal Medicine, Faculty of Medicine, University of Toyama, Toyama, Japan
| | - Reiko Inagi
- Divisions of Nephrology and Endocrinology and CKD Pathophysiology and
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41
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Finne K, Vethe H, Skogstrand T, Leh S, Dahl TD, Tenstad O, Berven FS, Reed RK, Vikse BE. Proteomic analysis of formalin-fixed paraffin-embedded glomeruli suggests depletion of glomerular filtration barrier proteins in two-kidney, one-clip hypertensive rats. Nephrol Dial Transplant 2014; 29:2217-27. [PMID: 25129444 PMCID: PMC4240179 DOI: 10.1093/ndt/gfu268] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Background It is well known that hypertension may cause glomerular damage, but the molecular mechanisms involved are still incompletely understood. Methods In the present study, we used formalin-fixed paraffin-embedded (FFPE) tissue to investigate changes in the glomerular proteome in the non-clipped kidney of two-kidney one-clip (2K1C) hypertensive rats, with special emphasis on the glomerular filtration barrier. 2K1C hypertension was induced in 6-week-old Wistar Hannover rats (n = 6) that were sacrificed 23 weeks later and compared with age-matched sham-operated controls (n = 6). Tissue was stored in FFPE tissue blocks and later prepared on tissue slides for laser microdissection. Glomeruli without severe morphological damage were isolated, and the proteomes were analysed using liquid chromatography–tandem mass spectrometry. Results 2K1C glomeruli showed reduced abundance of proteins important for slit diaphragm complex, such as nephrin, podocin and neph1. The podocyte foot process had a pattern of reduced abundance of transmembrane proteins but unchanged abundances of the podocyte cytoskeletal proteins synaptopodin and α-actinin-4. Lower abundance of important glomerular basement membrane proteins was seen. Possible glomerular markers of damage with increased abundance in 2K1C were transgelin, desmin and acyl-coenzyme A thioesterase 1. Conclusions Microdissection and tandem mass spectrometry could be used to investigate the proteome of isolated glomeruli from FFPE tissue. Glomerular filtration barrier proteins had reduced abundance in the non-clipped kidney of 2K1C hypertensive rats.
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Affiliation(s)
- Kenneth Finne
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Heidrun Vethe
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Trude Skogstrand
- Department of Clinical Medicine, University of Bergen, Bergen, Norway Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Sabine Leh
- Department of Clinical Medicine, University of Bergen, Bergen, Norway Department of Pathology, Haukeland University Hospital, Bergen, Norway
| | - Tone D Dahl
- Department of Clinical Medicine, University of Bergen, Bergen, Norway Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Olav Tenstad
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Frode S Berven
- Department of Biomedicine, University of Bergen, Bergen, Norway The Norwegian Multiple Sclerosis National Competence Centre, Department of Neurology, Haukeland University Hospital, Bergen, Norway
| | - Rolf K Reed
- Department of Biomedicine, University of Bergen, Bergen, Norway Centre for Cancer Biomarkers (CCBIO), University of Bergen, Bergen, Norway
| | - Bjørn Egil Vikse
- Department of Clinical Medicine, University of Bergen, Bergen, Norway Department of Medicine, Haukeland University Hospital, Bergen, Norway Department of Medicine, Haugesund Hospital, Haugesund, Norway
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Kokkinopoulou M, Güler MA, Lieb B, Barbeck M, Ghanaati S, Markl J. 3D-ultrastructure, functions and stress responses of gastropod (Biomphalaria glabrata) rhogocytes. PLoS One 2014; 9:e101078. [PMID: 24971744 PMCID: PMC4074132 DOI: 10.1371/journal.pone.0101078] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 06/03/2014] [Indexed: 11/18/2022] Open
Abstract
Rhogocytes are pore cells scattered among the connective tissue of different body parts of gastropods and other molluscs, with great variation in their number, shape and size. They are enveloped by a lamina of extracellular matrix. Their most characteristic feature is the "slit apparatus", local invaginations of the plasma membrane bridged by cytoplasmic bars, forming slits of ca. 20 nm width. A slit diaphragm creates a molecular sieve with permeation holes of 20×20 nm. In blue-blooded gastropods, rhogocytes synthesize and secrete the respiratory protein hemocyanin, and it has been proposed-though not proven-that in the rare red-blooded snail species they might synthesize and secrete the hemoglobin. However, the cellular secretion pathway for respiratory proteins, and the functional role(s) of the enigmatic rhogocyte slit apparatus are still unclear. Additional functions for rhogocytes have been proposed, notably a role in protein uptake and degradation, and in heavy metal detoxification. Here we provide new structural and functional information on the rhogocytes of the red-blooded freshwater snail Biomphalaria glabrata. By in situ hybridization of mantle tissues, we prove that rhogocytes indeed synthesize hemoglobin. By electron tomography, the first three dimensional (3D) reconstructions of the slit apparatus are provided, showing detail of highly dense material in the cytoplasmic bars close to the slits. By immunogold labelling, we collected evidence that a major component of this material is actin. By genome databank mining, the complete sequence of a B. glabrata nephrin was obtained, and localized to the rhogocytes by immunofluorescence microscopy. The presence of both proteins fit the ultrastructure-based hypothesis that rhogocytes are related to mammalian podocytes and insect nephrocytes. Reactions of the rhogocytes to deprivation of food and cadmium toxification are also documented, and a possible secretion pathway of newly synthesized respiratory proteins through the slit apparatus is discussed.
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Affiliation(s)
| | | | - Bernhard Lieb
- Institute of Zoology, Johannes Gutenberg University, Mainz, Germany
| | - Mike Barbeck
- Institute of Pathology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Shahram Ghanaati
- Institute of Pathology, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Jürgen Markl
- Institute of Zoology, Johannes Gutenberg University, Mainz, Germany
- * E-mail:
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Inoue R, Asanuma K, Seki T, Nagase M, Osafune K. [New therapeutic insights for chronic kidney disease provided by podocytology]. Nihon Yakurigaku Zasshi 2014; 143:27-33. [PMID: 24420134 DOI: 10.1254/fpj.143.27] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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He FF, Chen S, Su H, Meng XF, Zhang C. Actin-associated Proteins in the Pathogenesis of Podocyte Injury. Curr Genomics 2014; 14:477-84. [PMID: 24396279 PMCID: PMC3867723 DOI: 10.2174/13892029113146660014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Revised: 09/24/2013] [Accepted: 09/25/2013] [Indexed: 02/07/2023] Open
Abstract
Podocytes have a complex cellular architecture with interdigitating processes maintained by a precise organization of actin filaments. The actin-based foot processes of podocytes and the interposed slit diaphragm form the final barrier to proteinuria. The function of podocytes is largely based on the maintenance of the normal foot process structure with actin cytoskeleton. Cytoskeletal dynamics play important roles during normal podocyte development, in maintenance of the healthy glomerular filtration barrier, and in the pathogenesis of glomerular diseases. In this review, we focused on recent findings on the mechanisms of organization and reorganization of these actin-related molecules in the pathogenesis of podocyte injury and potential therapeutics targeting the regulation of actin cytoskeleton in podocytopathies.
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Affiliation(s)
- Fang-Fang He
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Shan Chen
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Hua Su
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Xian-Fang Meng
- Department of Neurobiology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Chun Zhang
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
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Merscher S, Fornoni A. Podocyte pathology and nephropathy - sphingolipids in glomerular diseases. Front Endocrinol (Lausanne) 2014; 5:127. [PMID: 25126087 PMCID: PMC4115628 DOI: 10.3389/fendo.2014.00127] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 07/14/2014] [Indexed: 01/10/2023] Open
Abstract
Sphingolipids are components of the lipid rafts in plasma membranes, which are important for proper function of podocytes, a key element of the glomerular filtration barrier. Research revealed an essential role of sphingolipids and sphingolipid metabolites in glomerular disorders of genetic and non-genetic origin. The discovery that glucocerebrosides accumulate in Gaucher disease in glomerular cells and are associated with clinical proteinuria initiated intensive research into the function of other sphingolipids in glomerular disorders. The accumulation of sphingolipids in other genetic diseases including Tay-Sachs, Sandhoff, Fabry, hereditary inclusion body myopathy 2, Niemann-Pick, and nephrotic syndrome of the Finnish type and its implications with respect to glomerular pathology will be discussed. Similarly, sphingolipid accumulation occurs in glomerular diseases of non-genetic origin including diabetic kidney disease (DKD), HIV-associated nephropathy, focal segmental glomerulosclerosis (FSGS), and lupus nephritis. Sphingomyelin metabolites, such as ceramide, sphingosine, and sphingosine-1-phosphate have also gained tremendous interest. We recently described that sphingomyelin phosphodiesterase acid-like 3b (SMPDL3b) is expressed in podocytes where it modulates acid sphingomyelinase activity and acts as a master modulator of danger signaling. Decreased SMPDL3b expression in post-reperfusion kidney biopsies from transplant recipients with idiopathic FSGS correlates with the recurrence of proteinuria in patients and in experimental models of xenotransplantation. Increased SMPDL3b expression is associated with DKD. The consequences of differential SMPDL3b expression in podocytes in these diseases with respect to their pathogenesis will be discussed. Finally, the role of sphingolipids in the formation of lipid rafts in podocytes and their contribution to the maintenance of a functional slit diaphragm in the glomerulus will be discussed.
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Affiliation(s)
- Sandra Merscher
- Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, Miami, FL, USA
- *Correspondence: Sandra Merscher, Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, 1580 NW 10th Avenue, Batchelor Building, Room 628, Miami, FL 33136, USA e-mail: ; Alessia Fornoni, Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, 1580 NW 10th Avenue, Batchelor Building, Room 633, Miami, FL 33136, USA e-mail:
| | - Alessia Fornoni
- Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, Miami, FL, USA
- *Correspondence: Sandra Merscher, Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, 1580 NW 10th Avenue, Batchelor Building, Room 628, Miami, FL 33136, USA e-mail: ; Alessia Fornoni, Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology, Department of Medicine, University of Miami, 1580 NW 10th Avenue, Batchelor Building, Room 633, Miami, FL 33136, USA e-mail:
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Worthmann K, Leitges M, Teng B, Sestu M, Tossidou I, Samson T, Haller H, Huber TB, Schiffer M. Def-6, a novel regulator of small GTPases in podocytes, acts downstream of atypical protein kinase C (aPKC) λ/ι. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 183:1945-1959. [PMID: 24096077 PMCID: PMC5707189 DOI: 10.1016/j.ajpath.2013.08.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 08/21/2013] [Accepted: 08/26/2013] [Indexed: 11/23/2022]
Abstract
The atypical protein kinase C (aPKC) isotypes PKCλ/ι and PKCζ are both expressed in podocytes; however, little is known about differences in their function. Previous studies in mice have demonstrated that podocyte-specific loss of PKCλ/ι leads to a severe glomerular phenotype, whereas mice deficient in PKCζ develop no renal phenotype. We analyzed various effects caused by PKCλ/ι and PKCζ deficiency in cultured murine podocytes. In contrast to PKCζ-deficient podocytes, PKCλ/ι-deficient podocytes exhibited a severe actin cytoskeletal phenotype, reduced cell size, decreased number of focal adhesions, and increased activation of small GTPases. Comparative microarray analysis revealed that the guanine nucleotide exchange factor Def-6 was specifically up-regulated in PKCλ/ι-deficient podocytes. In vivo Def-6 expression is significantly increased in podocytes of PKCλ/ι-deficient mice. Cultured PKCλ/ι-deficient podocytes exhibited an enhanced membrane association of Def-6, indicating enhanced activation. Overexpression of aPKCλ/ι in PKCλ/ι-deficient podocytes could reduce the membrane-associated expression of Def-6 and rescue the actin phenotype. In the present study, PKCλ/ι was identified as an important factor for actin cytoskeletal regulation in podocytes and Def-6 as a specific downstream target of PKCλ/ι that regulates the activity of small GTPases and subsequently the actin cytoskeleton of podocytes.
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Affiliation(s)
- Kirstin Worthmann
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
| | - Michael Leitges
- Biotechnology Centre of Oslo, University of Oslo, Oslo, Norway
| | - Beina Teng
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
| | - Marcello Sestu
- Faculty of Medicine, Interdisciplinary Centre for Clinical Research (IZKF) Leipzig, University of Leipzig, Leipzig, Germany
| | - Irini Tossidou
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
| | - Thomas Samson
- Department of Cell and Developmental Biology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina
| | - Hermann Haller
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany
| | - Tobias B Huber
- Renal Division, University Hospital Freiburg, Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-University, Freiburg, Germany
| | - Mario Schiffer
- Division of Nephrology, Department of Medicine, Hannover Medical School, Hannover, Germany.
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Li G, Li Y, Liu S, Shi Y, Chi Y, Liu G, Shan T. Gremlin aggravates hyperglycemia-induced podocyte injury by a TGFβ/smad dependent signaling pathway. J Cell Biochem 2013; 114:2101-13. [PMID: 23553804 DOI: 10.1002/jcb.24559] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 03/18/2013] [Indexed: 12/17/2022]
Abstract
Gremlin is a bone morphogenic protein (BMP) antagonist and is elevated in diabetic kidney tissues. In the early course of diabetic nephropathy (DN), podocyte are injured. We studied the protein and gene expression of gremlin in mice podocytes cultured in hyperglycemia ambient. The role of gremlin on podocyte injury and the likely signaling pathways involved were determined. Expression of gremlin was visualized by confocal microscopy. Recombinant mouse gremlin and small interfering RNA (siRNA) targeting to gremlin1 identified the role played by gremlin on podocytes. Study of canonical (smad2/3) and non-canonical (p38MAPK and JNK1/2) transforming growth factor beta (TGFβ)/smad mediated signaling revealed the putative signaling mechanisms involved. Smad2/3 siRNA and TGFβ receptor inhibition (SB431542) were used to probe canonical TGFβ/smad signaling in gremlin-induced podocyte injury. Apoptosis of podocytes was measured by TUNEL assay. Gremlin expression was enhanced in high glucose cultured mouse podocytes, and was localized predominantly in the cytoplasm and negligibly on the cell membrane. Not only expression of nephrin and synaptopodin were decreased on treatment with gremlin, but also synaptopodin rearrangement and nephrin relocalization were evident. Knockdown gremlin1 or smad2/3 by siRNA, and inhibition of TGFβR (SB431542) attenuated podocyte injury. Inhibition of canonical TGF-β signal blocked the injury of gremlin on podocytes. In conclusion, gremlin was clearly elevated in high glucose cultured mouse podocytes, and likely employed endogenous canonical TGFβ1/Smad signaling to induce podocyte injury. Knockdown gremlin1 by siRNA may be clinically useful in the attenuation of podocyte injury.
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Affiliation(s)
- Guiying Li
- Department of Nephrology, Third Hospital, Hebei Medical University, Shijiazhuang, 050051, China
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Ichimura K, Powell R, Nakamura T, Kurihara H, Sakai T, Obara T. Podocalyxin regulates pronephric glomerular development in zebrafish. Physiol Rep 2013; 1. [PMID: 24224085 PMCID: PMC3819108 DOI: 10.1002/phy2.74] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Vertebrate glomerular podocytes possess a highly sialylated transmembrane glycoprotein, Podocalyxin. In mammals, the sialic acid of Podocalyxin plays a crucial role in the formation of the characteristic podocyte architecture required for glomerular filtration. We examined the function of Podocalyxin in the developing zebrafish pronephros by disrupting the expression of podocalyxin through the use of morpholino antisense oligonucleotides. Podocalyxin was localized at the apical membrane of podocytes throughout pronephric glomerular development in zebrafish. Translational blocking of podocalyxin expression resulted in pericardial edema and a hypoplastic glomerulus. Whereas regular foot processes with a slit diaphragm covered 66.7 ± 7.8% of the urinary surface of glomerular basement membrane in control fish, only 14.4 ± 7.5% of this area was covered with regular foot processes in the translationally blocked morphants. Splice blocking of podocalyxin exon 2, which partially encodes the bulky mucin domain with extensive sialic acid-containing sugar chains, resulted in the deletion of 53% of mucin domain-coding sequence from podocalyxin mRNA. Approximately 40% of these splice-blocked morphants had mild pericardial edema. Although the pronephric glomerulus in the splice-blocked morphants exhibited almost normal appearance with developed glomerular capillaries and mesangium, they had only 36.3 ± 6.9% of the area covered with regular foot processes. In conclusion, Podocalyxin is predominantly expressed in the podocytes and plays a distinct role in the formation of the podocyte foot processes with a slit diaphragm during zebrafish pronephric development.
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Affiliation(s)
- Koichiro Ichimura
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA ; Department of Anatomy and Life Structure, Juntendo University School of Medicine, Tokyo, Japan
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Abstract
Glomerular hypertension (ie, increased glomerular capillary pressure), has been shown to cause podocyte damage progressing to glomerulosclerosis in animal models. Increased glomerular capillary pressure results in an increase in wall tension that acts primarily as circumferential tensile stress on the capillary wall. The elastic properties of the glomerular basement membrane (GBM) and the elastic as well as contractile properties of the cytoskeleton of the endothelium and of podocyte foot processes resist circumferential tensile stress. Whether the contractile forces generated by podocytes are able to equal circumferential tensile stress to effectively counteract wall tension is an open question. Mechanical stress is transmitted from the GBM to the actin cytoskeleton of podocyte foot processes via cell-matrix contacts that contain mainly integrin α3β1 and a variety of linker, scaffolding, and signaling proteins, which are not well characterized in podocytes. We know from in vitro studies that podocytes are sensitive to stretch, however, the crucial mechanosensor in podocytes remains unclear. On the other hand, in vitro studies have shown that in stretched podocytes specific signaling cascades are activated, the synthesis and secretion of various hormones and their receptors are increased, cell-cycle arrest is reinforced, cell adhesion is altered through secretion of matricellular proteins and changes in integrin expression, and the actin cytoskeleton is reorganized in a way that stress fibers are lost. In summary, current evidence suggests that in glomerular hypertension podocytes primarily aim to maintain the delicate architecture of interdigitating foot processes in the face of an expanding GBM area.
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Affiliation(s)
- Nicole Endlich
- Department of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany
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Abstract
Observations of hereditary glomerular disease support the contention that podocyte intercellular junction proteins are essential for junction formation and maintenance. Genetic deletion of most of these podocyte intercellular junction proteins results in foot process effacement and proteinuria. This review focuses on the current understanding of molecular mechanisms by which podocyte intercellular junction proteins such as the nephrin-neph1-podocin-receptor complex coordinate cytoskeletal dynamics and thus intercellular junction formation, maintenance, and injury-dependent remodeling.
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