1
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Baltar J, Miranda RM, Cabral M, Rebelo S, Grahammer F, Huber TB, Reguenga C, Monteiro FA. Neph1 is required for neurite branching and is negatively regulated by the PRRXL1 homeodomain factor in the developing spinal cord dorsal horn. Neural Dev 2024; 19:13. [PMID: 39049046 PMCID: PMC11271021 DOI: 10.1186/s13064-024-00190-6] [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: 05/16/2024] [Accepted: 07/05/2024] [Indexed: 07/27/2024] Open
Abstract
The cell-adhesion molecule NEPH1 is required for maintaining the structural integrity and function of the glomerulus in the kidneys. In the nervous system of Drosophila and C. elegans, it is involved in synaptogenesis and axon branching, which are essential for establishing functional circuits. In the mammalian nervous system, the expression regulation and function of Neph1 has barely been explored. In this study, we provide a spatiotemporal characterization of Neph1 expression in mouse dorsal root ganglia (DRGs) and spinal cord. After the neurogenic phase, Neph1 is broadly expressed in the DRGs and in their putative targets at the dorsal horn of the spinal cord, comprising both GABAergic and glutamatergic neurons. Interestingly, we found that PRRXL1, a homeodomain transcription factor that is required for proper establishment of the DRG-spinal cord circuit, prevents a premature expression of Neph1 in the superficial laminae of the dorsal spinal cord at E14.5, but has no regulatory effect on the DRGs or on either structure at E16.5. By chromatin immunoprecipitation analysis of the dorsal spinal cord, we identified four PRRXL1-bound regions within the Neph1 introns, suggesting that PRRXL1 directly regulates Neph1 transcription. We also showed that Neph1 is required for branching, especially at distal neurites. Together, our work showed that Prrxl1 prevents the early expression of Neph1 in the superficial dorsal horn, suggesting that Neph1 might function as a downstream effector gene for proper assembly of the DRG-spinal nociceptive circuit.
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Affiliation(s)
- João Baltar
- Unidade de Biologia Experimental, Departamento de Biomedicina, FMUP - Faculdade de Medicina da Universidade do Porto, Porto, Portugal
- Pain Neurobiology, IBMC - Instituto de Biologia Celular e Molecular, Porto, Portugal
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Rafael Mendes Miranda
- Unidade de Biologia Experimental, Departamento de Biomedicina, FMUP - Faculdade de Medicina da Universidade do Porto, Porto, Portugal
- Pain Neurobiology, IBMC - Instituto de Biologia Celular e Molecular, Porto, Portugal
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Maria Cabral
- Unidade de Biologia Experimental, Departamento de Biomedicina, FMUP - Faculdade de Medicina da Universidade do Porto, Porto, Portugal
- Pain Neurobiology, IBMC - Instituto de Biologia Celular e Molecular, Porto, Portugal
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Sandra Rebelo
- Unidade de Biologia Experimental, Departamento de Biomedicina, FMUP - Faculdade de Medicina da Universidade do Porto, Porto, Portugal
- Pain Neurobiology, IBMC - Instituto de Biologia Celular e Molecular, Porto, Portugal
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Departamento de Patologia Clínica, Centro Hospitalar Universitário São João, Porto, Portugal
| | - Florian Grahammer
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Hamburg Center for Kidney Health (HCKH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Tobias B Huber
- III. Department of Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Hamburg Center for Kidney Health (HCKH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Carlos Reguenga
- Unidade de Biologia Experimental, Departamento de Biomedicina, FMUP - Faculdade de Medicina da Universidade do Porto, Porto, Portugal
- Pain Neurobiology, IBMC - Instituto de Biologia Celular e Molecular, Porto, Portugal
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - Filipe Almeida Monteiro
- Unidade de Biologia Experimental, Departamento de Biomedicina, FMUP - Faculdade de Medicina da Universidade do Porto, Porto, Portugal.
- Pain Neurobiology, IBMC - Instituto de Biologia Celular e Molecular, Porto, Portugal.
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
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2
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Lee MS, Devi S, He JC, Zhou W. A zebrafish model of congenital nephrotic syndrome of the Finnish type. Front Cell Dev Biol 2022; 10:976043. [PMID: 36187478 PMCID: PMC9515793 DOI: 10.3389/fcell.2022.976043] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 08/12/2022] [Indexed: 11/13/2022] Open
Abstract
Nephrotic syndrome (NS) is a disease characterized by proteinuria and subsequent hypoalbuminemia, hyperlipidemia and edema due to the defective renal glomerular filtration barrier (GFB). Mutations of NPHS1, encoding NEPHRIN, a podocyte protein essential for normal GFB, cause congenital nephrotic syndrome (CNS) of the Finnish type (CNF), which accounts for about 50% of CNS cases. We generated zebrafish nphs1 mutants by using CRISPR/Cas9. These mutants completely lack nephrin proteins in podocytes and develop progressive peri-orbital and whole-body edema after 5 days post fertilization. Ultra-structurally, loss of nephrin results in absence of slit-diaphragms and progressive foot process effacement in zebrafish pronephric glomeruli, similar to the pathological changes in human CNF patients. Interestingly, some nphs1 mutants are viable to adulthood despite ultra-structural defects in renal glomeruli. Using a reporter line Tg (l-fabp:VDBP-GFP) expressing GFP-tagged vitamin-D-binding protein in the blood plasma, we observed a reduction of intravascular GFP fluorescence in the nphs1 mutants, a hypoalbuminemia-like phenotype. In addition, we detected excretion of GFP by the nphs1 mutants, reminiscent of proteinuria. Therefore, we have demonstrated that the nphs1 mutant zebrafish recapitulate the human NS phenotypes and provide a novel and relevant animal model useful for screening therapeutical agents for this disease.
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Affiliation(s)
- Mi-Sun Lee
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, United States
| | - Sulochana Devi
- Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, United States
| | - John Cijiang He
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- *Correspondence: John Cijiang He, ; Weibin Zhou,
| | - Weibin Zhou
- Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, United States
- *Correspondence: John Cijiang He, ; Weibin Zhou,
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3
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Djenoune L, Tomar R, Dorison A, Ghobrial I, Schenk H, Hegermann J, Beverly-Staggs L, Hidalgo-Gonzalez A, Little MH, Drummond IA. Autonomous Calcium Signaling in Human and Zebrafish Podocytes Controls Kidney Filtration Barrier Morphogenesis. J Am Soc Nephrol 2021; 32:1697-1712. [PMID: 33911000 PMCID: PMC8425667 DOI: 10.1681/asn.2020101525] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 02/12/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Podocytes are critical to maintaining the glomerular filtration barrier, and mutations in nephrotic syndrome genes are known to affect podocyte calcium signaling. However, the role of calcium signaling during podocyte development remains unknown. METHODS We undertook live imaging of calcium signaling in developing podocytes, using zebrafish larvae and human kidney organoids. To evaluate calcium signaling during development and in response to channel blockers and genetic defects, the calcium biosensor GCaMP6s was expressed in zebrafish podocytes. We used electron microscopy to evaluate filtration barrier formation in zebrafish, and Fluo-4 to detect calcium signals in differentiating podocytes in human kidney organoids. RESULTS Immature zebrafish podocytes (2.5 days postfertilization) generated calcium transients that correlated with interactions with forming glomerular capillaries. Calcium transients persisted until 4 days postfertilization, and were absent after glomerular barrier formation was complete. We detected similar calcium transients in maturing human organoid glomeruli, suggesting a conserved mechanism. In both models, inhibitors of SERCA or IP3 receptor calcium-release channels blocked calcium transients in podocytes, whereas lanthanum was ineffective, indicating the calcium source is from intracellular podocyte endoplasmic-reticulum stores. Calcium transients were not affected by blocking heartbeat or by blocking development of endothelium or endoderm, and they persisted in isolated glomeruli, suggesting podocyte-autonomous calcium release. Inhibition of expression of phospholipase C-γ1, but not nephrin or phospholipase C-ε1, led to significantly decreased calcium activity. Finally, blocking calcium release affected glomerular shape and podocyte foot process formation, supporting the critical role of calcium signaling in glomerular morphogenesis. CONCLUSIONS These findings establish podocyte cell-autonomous calcium signaling as a prominent and evolutionarily conserved feature of podocyte differentiation and demonstrate its requirement for podocyte foot process formation.
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Affiliation(s)
- Lydia Djenoune
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Charlestown, Massachusetts
| | - Ritu Tomar
- Nephrology Division, Department of Medicine, Massachusetts General Hospital, Charlestown, Massachusetts
| | - Aude Dorison
- Murdoch Children’s Research Institute, The Royal Children’s Hospital, Parkville, Victoria, Australia
| | - Irene Ghobrial
- Murdoch Children’s Research Institute, The Royal Children’s Hospital, Parkville, Victoria, Australia
| | - Heiko Schenk
- Department of Medicine/Nephrology, Hannover Medical School, Hannover, Germany,Research Core Unit Electron Microscopy, Hannover Medical School, Hannover, Germany
| | - Jan Hegermann
- Research Core Unit Electron Microscopy, Hannover Medical School, Hannover, Germany
| | - Lynne Beverly-Staggs
- Davis Center for Regenerative Biology and Aging, Mount Desert Island Biological Laboratory, Bar Harbor, Maine
| | | | - Melissa H. Little
- Murdoch Children’s Research Institute, The Royal Children’s Hospital, Parkville, Victoria, Australia,Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, Victoria, Australia,Department of Anatomy and Neuroscience, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Victoria, Australia
| | - Iain A. Drummond
- Davis Center for Regenerative Biology and Aging, Mount Desert Island Biological Laboratory, Bar Harbor, Maine
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Molecular evidence for a single origin of ultrafiltration-based excretory organs. Curr Biol 2021; 31:3629-3638.e2. [PMID: 34166606 DOI: 10.1016/j.cub.2021.05.057] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 04/14/2021] [Accepted: 05/26/2021] [Indexed: 01/14/2023]
Abstract
Excretion is an essential physiological process, carried out by all living organisms, regardless of their size or complexity.1-3 Both protostomes (e.g., flies and flatworms) and deuterostomes (e.g., humans and sea urchins) possess specialized excretory organs serving that purpose. Those organs exhibit an astonishing diversity, ranging from units composed of just few distinct cells (e.g., protonephridia) to complex structures, built by millions of cells of multiple types with divergent morphology and function (e.g., vertebrate kidneys).4,5 Although some molecular similarities between the development of kidneys of vertebrates and the regeneration of the protonephridia of flatworms have been reported,6,7 the molecular underpinnings of the development of excretory organs have never been systematically studied in a comparative context.4 Here, we show that a set of transcription factors (eya, six1/2, pou3, sall, lhx1/5, and osr) and structural proteins (nephrin, kirre, and zo1) is expressed in the excretory organs of a phoronid, brachiopod, annelid, onychophoran, priapulid, and hemichordate that represent major protostome lineages and non-vertebrate deuterostomes. We demonstrate that the molecular similarity observed in the vertebrate kidney and flatworm protonephridia6,7 is also seen in the developing excretory organs of those animals. Our results show that all types of ultrafiltration-based excretory organs are patterned by a conserved set of developmental genes, an observation that supports their homology. We propose that the last common ancestor of protostomes and deuterostomes already possessed an ultrafiltration-based organ that later gave rise to the vast diversity of extant excretory organs, including both proto- and metanephridia.
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5
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Orchard P, White JS, Thomas PE, Mychalowych A, Kiseleva A, Hensley J, Allen B, Parker SCJ, Keegan CE. Genome-wide chromatin accessibility and transcriptome profiling show minimal epigenome changes and coordinated transcriptional dysregulation of hedgehog signaling in Danforth's short tail mice. Hum Mol Genet 2019; 28:736-750. [PMID: 30380057 PMCID: PMC6381317 DOI: 10.1093/hmg/ddy378] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 10/23/2018] [Accepted: 10/26/2018] [Indexed: 12/20/2022] Open
Abstract
Danforth's short tail (Sd) mice provide an excellent model for investigating the underlying etiology of human caudal birth defects, which affect 1 in 10 000 live births. Sd animals exhibit aberrant axial skeleton, urogenital and gastrointestinal development similar to human caudal malformation syndromes including urorectal septum malformation, caudal regression, vertebral-anal-cardiac-tracheo-esophageal fistula-renal-limb (VACTERL) association and persistent cloaca. Previous studies have shown that the Sd mutation results from an endogenous retroviral (ERV) insertion upstream of the Ptf1a gene resulting in its ectopic expression at E9.5. Though the genetic lesion has been determined, the resulting epigenomic and transcriptomic changes driving the phenotype have not been investigated. Here, we performed ATAC-seq experiments on isolated E9.5 tailbud tissue, which revealed minimal changes in chromatin accessibility in Sd/Sd mutant embryos. Interestingly, chromatin changes were localized to a small interval adjacent to the Sd ERV insertion overlapping a known Ptf1a enhancer region, which is conserved in mice and humans. Furthermore, mRNA-seq experiments revealed increased transcription of Ptf1a target genes and, importantly, downregulation of hedgehog pathway genes. Reduced sonic hedgehog (SHH) signaling was confirmed by in situ hybridization and immunofluorescence suggesting that the Sd phenotype results, in part, from downregulated SHH signaling. Taken together, these data demonstrate substantial transcriptome changes in the Sd mouse, and indicate that the effect of the ERV insertion on Ptf1a expression may be mediated by increased chromatin accessibility at a conserved Ptf1a enhancer. We propose that human caudal dysgenesis disorders may result from dysregulation of hedgehog signaling pathways.
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Affiliation(s)
- Peter Orchard
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - James S White
- Department of Pediatrics, Division of Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Peedikayil E Thomas
- Department of Pediatrics, Division of Genetics, University of Michigan, Ann Arbor, MI, USA
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Anna Mychalowych
- Department of Pediatrics, Division of Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Anya Kiseleva
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - John Hensley
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - Benjamin Allen
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Stephen C J Parker
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
| | - Catherine E Keegan
- Department of Pediatrics, Division of Genetics, University of Michigan, Ann Arbor, MI, USA
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, USA
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6
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Völker LA, Maar BA, Pulido Guevara BA, Bilkei-Gorzo A, Zimmer A, Brönneke H, Dafinger C, Bertsch S, Wagener JR, Schweizer H, Schermer B, Benzing T, Hoehne M. Neph2/Kirrel3 regulates sensory input, motor coordination, and home-cage activity in rodents. GENES BRAIN AND BEHAVIOR 2018; 17:e12516. [DOI: 10.1111/gbb.12516] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 07/22/2018] [Accepted: 08/17/2018] [Indexed: 11/30/2022]
Affiliation(s)
- Linus A. Völker
- Department II of Internal Medicine and Center for Molecular Medicine Cologne; University of Cologne; Cologne Germany
| | - Barbara A. Maar
- Department II of Internal Medicine and Center for Molecular Medicine Cologne; University of Cologne; Cologne Germany
| | - Barbara A. Pulido Guevara
- Department II of Internal Medicine and Center for Molecular Medicine Cologne; University of Cologne; Cologne Germany
| | - Andras Bilkei-Gorzo
- Institute of Molecular Psychiatry; Medical Faculty of the University of Bonn; Bonn Germany
| | - Andreas Zimmer
- Institute of Molecular Psychiatry; Medical Faculty of the University of Bonn; Bonn Germany
| | - Hella Brönneke
- Mouse Phenotyping Core Facility; Cologne Excellence Cluster on Cellular Stress Responses (CECAD); 50931 Cologne Germany
| | - Claudia Dafinger
- Department II of Internal Medicine and Center for Molecular Medicine Cologne; University of Cologne; Cologne Germany
| | - Sabine Bertsch
- Department II of Internal Medicine and Center for Molecular Medicine Cologne; University of Cologne; Cologne Germany
| | - Jan-Robin Wagener
- Institute for Neuroanatomy, Universitätsmedizin Göttingen; Georg-August-University Göttingen; Göttingen Germany
| | - Heiko Schweizer
- Renal Division; University Hospital Freiburg; Freiburg Germany
| | - Bernhard Schermer
- Department II of Internal Medicine and Center for Molecular Medicine Cologne; University of Cologne; Cologne Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD); University of Cologne; Cologne Germany
- Systems Biology of Ageing Cologne (Sybacol); University of Cologne; Cologne Germany
| | - Thomas Benzing
- Department II of Internal Medicine and Center for Molecular Medicine Cologne; University of Cologne; Cologne Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD); University of Cologne; Cologne Germany
- Systems Biology of Ageing Cologne (Sybacol); University of Cologne; Cologne Germany
| | - Martin Hoehne
- Department II of Internal Medicine and Center for Molecular Medicine Cologne; University of Cologne; Cologne Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD); University of Cologne; Cologne Germany
- Systems Biology of Ageing Cologne (Sybacol); University of Cologne; Cologne Germany
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7
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Martin CE, Jones N. Nephrin Signaling in the Podocyte: An Updated View of Signal Regulation at the Slit Diaphragm and Beyond. Front Endocrinol (Lausanne) 2018; 9:302. [PMID: 29922234 PMCID: PMC5996060 DOI: 10.3389/fendo.2018.00302] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 05/22/2018] [Indexed: 12/11/2022] Open
Abstract
Podocytes are a major component of the glomerular blood filtration barrier, and alterations to the morphology of their unique actin-based foot processes (FP) are a common feature of kidney disease. Adjacent FP are connected by a specialized intercellular junction known as the slit diaphragm (SD), which serves as the ultimate barrier to regulate passage of macromolecules from the blood. While the link between SD dysfunction and reduced filtration selectivity has been recognized for nearly 50 years, our understanding of the underlying molecular circuitry began only 20 years ago, sparked by the identification of NPHS1, encoding the transmembrane protein nephrin. Nephrin not only functions as the core component of the extracellular SD filtration network but also as a signaling scaffold via interactions at its short intracellular region. Phospho-regulation of several conserved tyrosine residues in this region influences signal transduction pathways which control podocyte cell adhesion, shape, and survival, and emerging studies highlight roles for nephrin phospho-dynamics in mechanotransduction and endocytosis. The following review aims to summarize the last 5 years of advancement in our knowledge of how signaling centered at nephrin directs SD barrier formation and function. We further provide insight on promising frontiers in podocyte biology, which have implications for SD signaling in the healthy and diseased kidney.
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8
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Grahammer F, Wigge C, Schell C, Kretz O, Patrakka J, Schneider S, Klose M, Kind J, Arnold SJ, Habermann A, Bräuniger R, Rinschen MM, Völker L, Bregenzer A, Rubbenstroth D, Boerries M, Kerjaschki D, Miner JH, Walz G, Benzing T, Fornoni A, Frangakis AS, Huber TB. A flexible, multilayered protein scaffold maintains the slit in between glomerular podocytes. JCI Insight 2016; 1:86177. [PMID: 27430022 DOI: 10.1172/jci.insight.86177] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Vertebrate life critically depends on renal filtration and excretion of low molecular weight waste products. This process is controlled by a specialized cell-cell contact between podocyte foot processes: the slit diaphragm (SD). Using a comprehensive set of targeted KO mice of key SD molecules, we provided genetic, functional, and high-resolution ultrastructural data highlighting a concept of a flexible, dynamic, and multilayered architecture of the SD. Our data indicate that the mammalian SD is composed of NEPHRIN and NEPH1 molecules, while NEPH2 and NEPH3 do not participate in podocyte intercellular junction formation. Unexpectedly, homo- and heteromeric NEPHRIN/NEPH1 complexes are rarely observed. Instead, single NEPH1 molecules appear to form the lower part of the junction close to the glomerular basement membrane with a width of 23 nm, while single NEPHRIN molecules form an adjacent junction more apically with a width of 45 nm. In both cases, the molecules are quasiperiodically spaced 7 nm apart. These structural findings, in combination with the flexibility inherent to the repetitive Ig folds of NEPHRIN and NEPH1, indicate that the SD likely represents a highly dynamic cell-cell contact that forms an adjustable, nonclogging barrier within the renal filtration apparatus.
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Affiliation(s)
- Florian Grahammer
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Christoph Wigge
- Buchmann Institute for Molecular Life Sciences and Institute for Biophysics, Goethe University Frankfurt, Frankfurt, Germany
| | - Christoph Schell
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine.,Faculty of Biology, and
| | - Oliver Kretz
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,BIOSS Center for Biological Signalling Studies, Albert-Ludwigs University of Freiburg, Freiburg, Germany.,Institute of Anatomy, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jaakko Patrakka
- KI/AZ Integrated Cardio-Metabolic Center (ICMC), Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Simon Schneider
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Martin Klose
- Institute of Molecular Medicine and Cell Research, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium and.,German Cancer Research Center, Heidelberg, Germany
| | - Julia Kind
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Sebastian J Arnold
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,BIOSS Center for Biological Signalling Studies, Albert-Ludwigs University of Freiburg, Freiburg, Germany.,Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Anja Habermann
- Buchmann Institute for Molecular Life Sciences and Institute for Biophysics, Goethe University Frankfurt, Frankfurt, Germany
| | - Ricarda Bräuniger
- Buchmann Institute for Molecular Life Sciences and Institute for Biophysics, Goethe University Frankfurt, Frankfurt, Germany
| | - Markus M Rinschen
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Linus Völker
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Andreas Bregenzer
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Dennis Rubbenstroth
- Institute of Virology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany
| | - Melanie Boerries
- Institute of Molecular Medicine and Cell Research, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium and.,German Cancer Research Center, Heidelberg, Germany
| | | | - Jeffrey H Miner
- Renal Division, Washington University, St. Louis, Missouri, USA
| | - Gerd Walz
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Thomas Benzing
- Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany
| | - Alessia Fornoni
- Division of Nephrology and Katz Family Drug Discovery Center, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Achilleas S Frangakis
- Buchmann Institute for Molecular Life Sciences and Institute for Biophysics, Goethe University Frankfurt, Frankfurt, Germany
| | - Tobias B Huber
- Department of Medicine, Division of Nephrology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Spemann Graduate School of Biology and Medicine.,BIOSS Center for Biological Signalling Studies, Albert-Ludwigs University of Freiburg, Freiburg, Germany.,FRIAS, Freiburg Institute for Advanced Studies and ZBSA, Center for Biological System Analysis, Albert-Ludwigs-University of Freiburg, Germany
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9
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Yaoita E, Nishimura H, Nameta M, Yoshida Y, Takimoto H, Fujinaka H, Kawachi H, Magdeldin S, Zhang Y, Xu B, Oyama T, Nakamura F, Yamamoto T. Avian Podocytes, Which Lack Nephrin, Use Adherens Junction Proteins at Intercellular Junctions. J Histochem Cytochem 2015; 64:67-76. [PMID: 26416242 DOI: 10.1369/0022155415611708] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 09/19/2015] [Indexed: 12/14/2022] Open
Abstract
Nephrin, a major intercellular junction (ICJ) molecule of mammalian podocytes in the renal glomerulus, is absent in the avian genome. We hypothesized that birds use ICJ molecules other than nephrin in their podocytes. Therefore, in the present study, we examined the possible involvement of adherens junction (AJ) proteins in the ICJs of avian podocytes. We found the AJ proteins N-cadherin and α- and β-catenins in podocytes of quail and chickens but not in those of rats, pigs or humans. The AJ proteins were prominent in avian glomerulus-rich fractions in immunoblot analyses, and in immunofluorescence microscopy analyses, they were localized along glomerular capillary walls appearing in at least two staining patterns: weakly diffuse and distinctly granular. Immunoelectron microscopy demonstrated that the significant accumulation of immunogold particles for the AJ proteins were especially evident in avian slit diaphragms and AJs. Furthermore, N-cadherin was found to be expressed in all nephron cells in the early developmental stage but became confined to podocytes during maturation. These results indicate that avian slit diaphragms clearly express AJ proteins as compared with that in the mammal-where AJ proteins are suppressed to an extremely low level-and that avian podocytes are interconnected by AJs per se in addition to slit diaphragms.
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Affiliation(s)
- Eishin Yaoita
- Department of Structural Pathology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan (EY, YY, HT, SM, YZ, BX, TO, FN, TY)
| | - Hiroko Nishimura
- Department of Health Informatics, Niigata University of Health and Welfare, Niigata, Japan (HN)
| | - Masaaki Nameta
- Cooperative Laboratory of Electron Microscopy, Niigata University, Niigata, Japan (MN)
| | - Yutaka Yoshida
- Department of Structural Pathology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan (EY, YY, HT, SM, YZ, BX, TO, FN, TY)
| | - Hiroki Takimoto
- Department of Structural Pathology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan (EY, YY, HT, SM, YZ, BX, TO, FN, TY)
| | - Hidehiko Fujinaka
- Institute for Clinical Research, Niigata National Hospital, Niigata, Japan (HF)
| | - Hiroshi Kawachi
- Department of Cell Biology (HK), Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Sameh Magdeldin
- Department of Structural Pathology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan (EY, YY, HT, SM, YZ, BX, TO, FN, TY)
| | - Ying Zhang
- Department of Structural Pathology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan (EY, YY, HT, SM, YZ, BX, TO, FN, TY)
| | - Bo Xu
- Department of Structural Pathology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan (EY, YY, HT, SM, YZ, BX, TO, FN, TY)
| | - Tomizo Oyama
- Department of Structural Pathology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan (EY, YY, HT, SM, YZ, BX, TO, FN, TY)
| | - Fujio Nakamura
- Department of Structural Pathology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan (EY, YY, HT, SM, YZ, BX, TO, FN, TY)
| | - Tadashi Yamamoto
- Department of Structural Pathology, Institute of Nephrology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan (EY, YY, HT, SM, YZ, BX, TO, FN, TY)
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An update: the role of Nephrin inside and outside the kidney. SCIENCE CHINA-LIFE SCIENCES 2015; 58:649-57. [PMID: 25921941 DOI: 10.1007/s11427-015-4844-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 02/27/2015] [Indexed: 12/18/2022]
Abstract
Nephrin is a key molecule in podocytes to maintain normal slit diaphragm structure. Nephin interacts with many other podocyte and slit diaphragm protein and also mediates important cell signaling pathways in podocytes. Loss of nephrin during the development leads to the congenital nephrotic syndrome in children. Reduction of nephrin expression is often observed in adult kidney diseases including diabetic nephropathy and HIV-associated nephropathy. The critical role of nephrin has been confirmed by different animal models with nephrin knockout and knockdown. Recent studies demonstrate that knockdown of nephrin expression in adult mice aggravates the progression of unilateral nephrectomy and Adriamycin-induced kidney disease. In addition to its critical role in maintaining normal glomerular filtration unit in the kidney, nephrin is also expressed in other organs. However, the exact role of nephrin in kidney and extra-renal organs has not been well characterized. Future studies are required to determine whether nephrin could be developed as a drug target to treat patients with kidney disease.
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Li X, Chuang PY, D'Agati VD, Dai Y, Yacoub R, Fu J, Xu J, Taku O, Premsrirut PK, Holzman LB, He JC. Nephrin Preserves Podocyte Viability and Glomerular Structure and Function in Adult Kidneys. J Am Soc Nephrol 2015; 26:2361-77. [PMID: 25644109 DOI: 10.1681/asn.2014040405] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 11/19/2014] [Indexed: 01/12/2023] Open
Abstract
Nephrin is required during kidney development for the maturation of podocytes and formation of the slit diaphragm junctional complex. Because nephrin expression is downregulated in acquired glomerular diseases, nephrin deficiency is considered a pathologic feature of glomerular injury. However, whether nephrin deficiency exacerbates glomerular injury in glomerular diseases has not been experimentally confirmed. Here, we generated mice with inducible RNA interference-mediated nephrin knockdown. Short-term nephrin knockdown (6 weeks), starting after the completion of kidney development at 5 weeks of age, did not affect glomerular structure or function. In contrast, mice with long-term nephrin knockdown (20 weeks) developed mild proteinuria, foot process effacement, filtration slit narrowing, mesangial hypercellularity and sclerosis, glomerular basement membrane thickening, subendothelial zone widening, and podocyte apoptosis. When subjected to an acquired glomerular insult induced by unilateral nephrectomy or doxorubicin, mice with short-term nephrin knockdown developed more severe glomerular injury compared with mice without nephrin knockdown. Additionally, nephrin-knockdown mice developed more exaggerated glomerular enlargement when subjected to unilateral nephrectomy and more podocyte apoptosis and depletion after doxorubicin challenge. AKT phosphorylation, which is a slit diaphragm-mediated and nephrin-dependent pathway in the podocyte, was markedly reduced in mice with long-term or short-term nephrin knockdown challenged with uninephrectomy or doxorubicin. Taken together, our data establish that under the basal condition and in acquired glomerular diseases, nephrin is required to maintain slit diaphragm integrity and slit diaphragm-mediated signaling to preserve glomerular function and podocyte viability in adult mice.
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Affiliation(s)
- Xuezhu Li
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Nephrology; Shanghai East Hospital, Tongji University School of Medicine, Shanghai, China
| | - Peter Y Chuang
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York;
| | - Vivette D D'Agati
- Department of Pathology, College of Physicians and Surgeons, Columbia University, New York, New York
| | - Yan Dai
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Nephrology, Shanghai First Municipal Hospital, Shanghai Jiaotao University School of Medicine; Shanghai, China
| | - Rabi Yacoub
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jia Fu
- Research Institute of Nephrology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China
| | - Jin Xu
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Oltjon Taku
- State University of New York at University at Binghamton, Binghamton, New York
| | | | - Lawrence B Holzman
- Renal Electrolyte and Hypertension Division, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania; and
| | - John Cijiang He
- Department of Medicine/Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York; Renal Section, James J Peter Veterans Administration Medical Center, Bronx, New York
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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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Identification of novel Kirrel3 gene splice variants in adult human skeletal muscle. BMC PHYSIOLOGY 2014; 14:11. [PMID: 25488023 PMCID: PMC4269076 DOI: 10.1186/s12899-014-0011-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Accepted: 11/19/2014] [Indexed: 01/08/2023]
Abstract
Background Multiple cell types including trophoblasts, osteoclasts and myoblasts require somatic cell fusion events as part of their physiological functions. In Drosophila Melanogaster the paralogus type 1 transmembrane receptors and members of the immunoglobulin superfamily Kin of Irre (Kirre) and roughest (Rst) regulate myoblast fusion during embryonic development. Present within the human genome are three homologs to Kirre termed Kin of Irre like (Kirrel) 1, 2 and 3. Currently it is unknown if Kirrel3 is expressed in adult human skeletal muscle. Results We investigated (using PCR and Western blot) Kirrel3 in adult human skeletal muscle samples taken at rest and after mild exercise induced muscle damage. Kirrel3 mRNA expression was verified by sequencing and protein presence via blotting with 2 different anti-Kirrel3 protein antibodies. Evidence for three alternatively spliced Kirrel3 mRNA transcripts in adult human skeletal muscle was obtained. Kirrel3 mRNA in adult human skeletal muscle was detected at low or moderate levels, or not at all. This sporadic expression suggests that Kirrel3 is expressed in a pulsatile manner. Several anti Kirrel3 immunoreactive proteins were detected in all adult human skeletal muscle samples analysed and results suggest the presence of different isoforms or posttranslational modification, or both. Conclusion The results presented here demonstrate for the first time that there are at least 3 splice variants of Kirrel3 expressed in adult human skeletal muscle, two of which have never previously been identified in human muscle. Importantly, mRNA of all splice variants was not always present, a finding with potential physiological relevance. These initial discoveries highlight the need for more molecular and functional studies to understand the role of Kirrel3 in human skeletal muscle.
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Önel SF, Rust MB, Jacob R, Renkawitz-Pohl R. Tethering membrane fusion: common and different players in myoblasts and at the synapse. J Neurogenet 2014; 28:302-15. [PMID: 24957080 PMCID: PMC4245166 DOI: 10.3109/01677063.2014.936014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Drosophila Membrane fusion is essential for the communication of membrane-defined compartments, development of multicellular organisms and tissue homeostasis. Although membrane fusion has been studied extensively, still little is known about the molecular mechanisms. Especially the intercellular fusion of cells during development and tissue homeostasis is poorly understood. Somatic muscle formation in Drosophila depends on the intercellular fusion of myoblasts. In this process, myoblasts recognize each other and adhere, thereby triggering a protein machinery that leads to electron-dense plaques, vesicles and F-actin formation at apposing membranes. Two models of how local membrane stress is achieved to induce the merging of the myoblast membranes have been proposed: the electron-dense vesicles transport and release a fusogen and F-actin bends the plasma membrane. In this review, we highlight cell-adhesion molecules and intracellular proteins known to be involved in myoblast fusion. The cell-adhesion proteins also mediate the recognition and adhesion of other cell types, such as neurons that communicate with each other via special intercellular junctions, termed chemical synapses. At these synapses, neurotransmitters are released through the intracellular fusion of synaptic vesicles with the plasma membrane. As the targeting of electron-dense vesicles in myoblasts shares some similarities with the targeting of synaptic vesicle fusion, we compare molecules required for synaptic vesicle fusion to recently identified molecules involved in myoblast fusion.
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Affiliation(s)
- Susanne Filiz Önel
- Developmental Biology, Philipps University of Marburg , 35043 Marburg , Germany
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Abstract
The description of the Rst protein by Karl-Friedrich Fischbach and colleagues was a milestone in the discovery of the irre cell recognition module (IRM). IRM proteins represent a family of immunoglobulin superfamily cell adhesion proteins that orchestrate intercellular adhesion and signaling events necessary for the development of various tissues. This review briefly summarizes the fundamental role of IRM proteins for neuronal wiring and filtration in organisms spanning the evolutionary distance from Drosophila (nephrocyte diaphragm) to humans (slit diaphragm).
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Costa MSA, Machado MCR, Vieceli FM, Amistá L, Baroneza JE, Yan CYI, Ramos RGP. The Rst-Neph family of cell adhesion molecules in Gallus gallus. J Neurogenet 2014; 28:270-81. [PMID: 24914768 DOI: 10.3109/01677063.2014.933220] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The Rst-Neph family comprises an evolutionarily conserved group of single-pass transmembrane glycoproteins that belong to the immunoglobulin superfamily and participate in a wide range of cell adhesion and recognition events in both vertebrates and invertebrates. In mammals and fish, three Rst-Neph members, named Neph1-3, are present. Besides being widely expressed in the embryo, particularly in the developing nervous system, they also contribute to the formation and integrity of the urine filtration apparatus in the slit diaphragm of kidney glomerular podocytes, where they form homodimers, as well as heterodimers with Nephrin, another immunoglobulin-like cell adhesion molecule. In mice, absence of Neph1 causes severe proteinuria, podocyte effacement and perinatal death, while in humans, a mutated form of Nephrin leads to congenital nephrotic syndrome of the Finnish type. Intriguingly, neither Nephrin nor Neph3 are present in birds, which nevertheless have typical vertebrate kidneys with mammalian-like slit diaphragms. These characteristics make, in principle, avian systems very helpful for understanding the evolution and functional significance of the complex interactions displayed by Rst-Neph proteins. To this end we have started a systematic study of chicken Neph embryonic and post-embryonic expression, both at mRNA and protein level. RT-qPCR mRNA quantification of the two Neph paralogues in adult tissues showed that both are expressed in heart, brain, and retina. Neph1 is additionally present in kidney, liver, pancreas, lungs, and testicles, while Neph2 mRNA is barely detected in kidney, testicles, pancreas and absent in liver and lungs. In embryos, mRNA from both genes can already be detected at as early as stage HH14, and remain expressed until at least HH28. Finally, we used a specific antibody to examine the spatial dynamics and subcellular distribution of ggNeph2 between stages HH20-28, particularly in the mesonephros, dermomyotomes, developing heart, and retina.
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Affiliation(s)
- Mara Silvia A Costa
- Department of Cell and Molecular Biology, Ribeirão Preto Medical School, University of São Paulo , Ribeirão Preto , Brazil
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Özkan E, Chia PH, Wang RR, Goriatcheva N, Borek D, Otwinowski Z, Walz T, Shen K, Garcia KC. Extracellular architecture of the SYG-1/SYG-2 adhesion complex instructs synaptogenesis. Cell 2014; 156:482-94. [PMID: 24485456 PMCID: PMC3962013 DOI: 10.1016/j.cell.2014.01.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 09/04/2013] [Accepted: 01/06/2014] [Indexed: 01/29/2023]
Abstract
SYG-1 and SYG-2 are multipurpose cell adhesion molecules (CAMs) that have evolved across all major animal taxa to participate in diverse physiological functions, ranging from synapse formation to formation of the kidney filtration barrier. In the crystal structures of several SYG-1 and SYG-2 orthologs and their complexes, we find that SYG-1 orthologs homodimerize through a common, bispecific interface that similarly mediates an unusual orthogonal docking geometry in the heterophilic SYG-1/SYG-2 complex. C. elegans SYG-1's specification of proper synapse formation in vivo closely correlates with the heterophilic complex affinity, which appears to be tuned for optimal function. Furthermore, replacement of the interacting domains of SYG-1 and SYG-2 with those from CAM complexes that assume alternative docking geometries or the introduction of segmental flexibility compromised synaptic function. These results suggest that SYG extracellular complexes do not simply act as "molecular velcro" and that their distinct structural features are important in instructing synaptogenesis. PAPERFLICK:
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Affiliation(s)
- Engin Özkan
- Department of Molecular and Cellular Physiology and Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Poh Hui Chia
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Ruiqi Rachel Wang
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Natalia Goriatcheva
- Department of Molecular and Cellular Physiology and Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Dominika Borek
- Departments of Biochemistry and Biophysics, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Zbyszek Otwinowski
- Departments of Biochemistry and Biophysics, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Thomas Walz
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Kang Shen
- Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - K Christopher Garcia
- Department of Molecular and Cellular Physiology and Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA.
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Periventricular nodular heterotopia and transverse limb reduction defect in a woman with interstitial 11q24 deletion in the Jacobsen syndrome region. Am J Med Genet A 2013; 164A:511-5. [DOI: 10.1002/ajmg.a.36292] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 09/16/2013] [Indexed: 11/07/2022]
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Functions of the podocyte proteins nephrin and Neph3 and the transcriptional regulation of their genes. Clin Sci (Lond) 2013; 126:315-28. [DOI: 10.1042/cs20130258] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nephrin and Neph-family proteins [Neph1–3 (nephrin-like 1–3)] belong to the immunoglobulin superfamily of cell-adhesion receptors and are expressed in the glomerular podocytes. Both nephrin and Neph-family members function in cell adhesion and signalling, and thus regulate the structure and function of podocytes and maintain normal glomerular ultrafiltration. The expression of nephrin and Neph3 is altered in human proteinuric diseases emphasizing the importance of studying the transcriptional regulation of the nephrin and Neph3 genes NPHS1 (nephrosis 1, congenital, Finnish type) and KIRREL2 (kin of IRRE-like 2) respectively. The nephrin and Neph3 genes form a bidirectional gene pair, and they share transcriptional regulatory mechanisms. In the present review, we summarize the current knowledge of the functions of nephrin and Neph-family proteins and transcription factors and agents that control nephrin and Neph3 gene expression.
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Grahammer F, Schell C, Huber TB. The podocyte slit diaphragm--from a thin grey line to a complex signalling hub. Nat Rev Nephrol 2013; 9:587-98. [PMID: 23999399 DOI: 10.1038/nrneph.2013.169] [Citation(s) in RCA: 173] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The architectural design of our kidneys is amazingly complex, and culminates in the 3D structure of the glomerular filter. During filtration, plasma passes through a sieve consisting of a fenestrated endothelium and a broad basement membrane before it reaches the most unique part, the slit diaphragm, a specialized type of intercellular junction that connects neighbouring podocyte foot processes. When podocytes become stressed, irrespective of the causative stimulus, they undergo foot process effacement and loss of slit diaphragms--two key steps leading to proteinuria. Thus, proteinuria is the unifying denominator of a broad spectrum of podocytopathies. With the rising prevalence of chronic kidney disease and the fact that glomerular diseases account for the majority of patients with end-stage renal disease, further investigation and elucidation of this unique structure is of paramount importance. This Review recounts how perception of the slit diaphragm has changed over time as a result of intense research, from its first anatomical description as a thin intercellular connection, to an appreciation of its role as a dynamic signalling hub. These observations led to the introduction of novel concepts in podocyte biology, which could pave the way to development of highly desired, specific therapeutic strategies for glomerular diseases.
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Affiliation(s)
- Florian Grahammer
- Renal Division, University Hospital Freiburg, Hugstetter Strasse 55, Freiburg 79106, Germany
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22
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Program specificity for Ptf1a in pancreas versus neural tube development correlates with distinct collaborating cofactors and chromatin accessibility. Mol Cell Biol 2013; 33:3166-79. [PMID: 23754747 DOI: 10.1128/mcb.00364-13] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The lineage-specific basic helix-loop-helix transcription factor Ptf1a is a critical driver for development of both the pancreas and nervous system. How one transcription factor controls diverse programs of gene expression is a fundamental question in developmental biology. To uncover molecular strategies for the program-specific functions of Ptf1a, we identified bound genomic regions in vivo during development of both tissues. Most regions bound by Ptf1a are specific to each tissue, lie near genes needed for proper formation of each tissue, and coincide with regions of open chromatin. The specificity of Ptf1a binding is encoded in the DNA surrounding the Ptf1a-bound sites, because these regions are sufficient to direct tissue-restricted reporter expression in transgenic mice. Fox and Sox factors were identified as potential lineage-specific modifiers of Ptf1a binding, since binding motifs for these factors are enriched in Ptf1a-bound regions in pancreas and neural tube, respectively. Of the Fox factors expressed during pancreatic development, Foxa2 plays a major role. Indeed, Ptf1a and Foxa2 colocalize in embryonic pancreatic chromatin and can act synergistically in cell transfection assays. Together, these findings indicate that lineage-specific chromatin landscapes likely constrain the DNA binding of Ptf1a, and they identify Fox and Sox gene families as part of this process.
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Prince JEA, Brignall AC, Cutforth T, Shen K, Cloutier JF. Kirrel3 is required for the coalescence of vomeronasal sensory neuron axons into glomeruli and for male-male aggression. Development 2013; 140:2398-408. [PMID: 23637329 DOI: 10.1242/dev.087262] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The accessory olfactory system controls social and sexual interactions in mice that are crucial for survival. Vomeronasal sensory neurons (VSNs) form synapses with dendrites of second order neurons in glomeruli of the accessory olfactory bulb (AOB). Axons of VSNs expressing the same vomeronasal receptor coalesce into multiple glomeruli within spatially conserved regions of the AOB. Here we examine the role of the Kirrel family of transmembrane proteins in the coalescence of VSN axons within the AOB. We find that Kirrel2 and Kirrel3 are differentially expressed in subpopulations of VSNs and that their expression is regulated by activity. Although Kirrel3 expression is not required for early axonal guidance events, such as fasciculation of the vomeronasal tract and segregation of apical and basal VSN axons in the AOB, it is necessary for proper coalescence of axons into glomeruli. Ablation of Kirrel3 expression results in disorganization of the glomerular layer of the posterior AOB and formation of fewer, larger glomeruli. Furthermore, Kirrel3(-/-) mice display a loss of male-male aggression in a resident-intruder assay. Taken together, our results indicate that differential expression of Kirrels on vomeronasal axons generates a molecular code that dictates their proper coalescence into glomeruli within the AOB.
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Affiliation(s)
- Janet E A Prince
- Montreal Neurological Institute, Centre for Neuronal Survival, 3801 University, Montréal, Québec, H3A 2B4, Canada
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Li M, Armelloni S, Edefonti A, Messa P, Rastaldi MP. Fifteen years of research on nephrin: what we still need to know. Nephrol Dial Transplant 2012; 28:767-70. [PMID: 23139403 DOI: 10.1093/ndt/gfs522] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Affiliation(s)
- Min Li
- Renal Research Laboratory, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico & Fondazione D'Amico per la Ricerca sulle Malattie Renali, Milano, Italy
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