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Grampp S, Kraus A, Skoczynski K, Schiffer M, Krüger R, Naas S, Schödel J, Buchholz B. Hypoxia induces polycystin-1 expression in the renal epithelium. ROYAL SOCIETY OPEN SCIENCE 2023; 10:220992. [PMID: 37206967 PMCID: PMC10189600 DOI: 10.1098/rsos.220992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 04/28/2023] [Indexed: 05/21/2023]
Abstract
Mutations in polycystin-1 which is encoded by the PKD1 gene are the main causes for the development of autosomal dominant polycystic kidney disease. However, only little is known about the physiological function of polycystin-1 and even less about the regulation of its expression. Here, we show that expression of PKD1 is induced by hypoxia and compounds that stabilize the hypoxia-inducible transcription factor (HIF) 1α in primary human tubular epithelial cells. Knockdown of HIF subunits confirms HIF-1α-dependent regulation of polycystin-1 expression. Furthermore, HIF ChIP-seq reveals that HIF interacts with a regulatory DNA element within the PKD1 gene in renal tubule-derived cells. HIF-dependent expression of polycystin-1 can also be demonstrated in vivo in kidneys of mice treated with substances that stabilize HIF. Polycystin-1 and HIF-1α have been shown to promote epithelial branching during kidney development. In line with these findings, we show that expression of polycystin-1 within mouse embryonic ureteric bud branches is regulated by HIF. Our finding links expression of one of the main regulators of accurate renal development with the hypoxia signalling pathway and provides additional insight into the pathophysiology of polycystic kidney disease.
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Affiliation(s)
- Steffen Grampp
- Department of Nephrology and Hypertension, Uniklinikum Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Andre Kraus
- Department of Nephrology and Hypertension, Uniklinikum Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Kathrin Skoczynski
- Department of Nephrology and Hypertension, Uniklinikum Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Mario Schiffer
- Department of Nephrology and Hypertension, Uniklinikum Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - René Krüger
- Department of Nephrology and Hypertension, Uniklinikum Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Stephanie Naas
- Department of Nephrology and Hypertension, Uniklinikum Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Johannes Schödel
- Department of Nephrology and Hypertension, Uniklinikum Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Bjoern Buchholz
- Department of Nephrology and Hypertension, Uniklinikum Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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2
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Spix B, Castiglioni AJ, Remis NN, Flores EN, Wartenberg P, Wyatt A, Boehm U, Gudermann T, Biel M, García-Añoveros J, Grimm C. Whole-body analysis of TRPML3 (MCOLN3) expression using a GFP-reporter mouse model reveals widespread expression in secretory cells and endocrine glands. PLoS One 2022; 17:e0278848. [PMID: 36520788 PMCID: PMC10045552 DOI: 10.1371/journal.pone.0278848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 11/27/2022] [Indexed: 12/23/2022] Open
Abstract
TRPML3 (mucolipin 3, MCOLN3) is an endolysosomal cation channel belonging to the TRPML subfamily of transient receptor potential channels. Gain-of-function mutations in the Trpml3 gene cause deafness, circling behavior and coat color dilution in mice due to cell death of TRPML3-expressing hair cells of the inner ear or skin melanocytes, respectively. Furthermore, TRPML3 was found to play a role in the long term survival of cochlear hair cells (its absence contributing to presbycusis), in specialized giant lysosomes that neonatal (birth to weaning) enterocytes used for the uptake and digestion of maternal milk nutrients, and in the expulsion of exosome-encased bacteria such as uropathogenic E. coli, infecting bladder epithelial cells. Recently, TRPML3 was found to be expressed at high levels in alveolar macrophages and loss of TRPML3 results in a lung emphysema phenotype, confirmed in two independently engineered Trpml3 knockout lines. TRPML3 is not ubiquitously expressed like its relative TRPML1 and thus cellular expression of TRPML3 on a whole-tissue level remains, with the exceptions mentioned above, largely elusive. To overcome this problem, we generated a τGFP reporter mouse model for TRPML3 and compared expression data obtained from this model by immunofluorescence on tissue sections with immunohistochemistry using TRPML3 antibodies and in situ hybridization. We thus uncovered expression in several organs and distinct cell types. We confirmed TRPML3 expression in both neonatal and adult alveolar macrophages, in melanocytes of hair follicles and glabrous skin, in principle cells of the collecting duct of the neonatal and adult kidney, and in olfactory sensory neurons of the olfactory epithelium, including its fibres protruding to the glomeruli of the olfactory bulb. Additionally, we localized TRPML3 in several glands including parathyroid, thyroid, salivary, adrenal, and pituitary gland, testes and ovaries, suggestive of potential roles for the channel in secretion or uptake of different hormones.
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Affiliation(s)
- Barbara Spix
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-University, Munich, Germany
| | - Andrew J. Castiglioni
- Department of Anesthesiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Natalie N. Remis
- Department of Anesthesiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Integrated Graduate Program in the Life Sciences (IGP), Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Emma N. Flores
- Department of Anesthesiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Northwestern University Interdepartmental Neuroscience (NUIN) graduate program, Chicago, Illinois, United States of America
| | - Philipp Wartenberg
- Center for Molecular Signaling (PZMS), Experimental Pharmacology, Saarland University, Homburg, Germany
| | - Amanda Wyatt
- Center for Molecular Signaling (PZMS), Experimental Pharmacology, Saarland University, Homburg, Germany
| | - Ulrich Boehm
- Center for Molecular Signaling (PZMS), Experimental Pharmacology, Saarland University, Homburg, Germany
| | - Thomas Gudermann
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-University, Munich, Germany
| | - Martin Biel
- Department of Pharmacy, Ludwig-Maximilians-University, Munich, Germany
| | - Jaime García-Añoveros
- Department of Anesthesiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Integrated Graduate Program in the Life Sciences (IGP), Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Northwestern University Interdepartmental Neuroscience (NUIN) graduate program, Chicago, Illinois, United States of America
- Departments of Neurology and Neuroscience, and Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Christian Grimm
- Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, Ludwig-Maximilians-University, Munich, Germany
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Choudhury MI, Benson MA, Sun SX. Trans-epithelial fluid flow and mechanics of epithelial morphogenesis. Semin Cell Dev Biol 2022; 131:146-159. [PMID: 35659163 DOI: 10.1016/j.semcdb.2022.05.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 05/22/2022] [Accepted: 05/23/2022] [Indexed: 12/14/2022]
Abstract
Active fluid transport across epithelial monolayers is emerging as a major driving force of tissue morphogenesis in a variety of healthy and diseased systems, as well as during embryonic development. Cells use directional transport of ions and osmotic gradients to drive fluid flow across the cell surface, in the process also building up fluid pressure. The basic physics of this process is described by the osmotic engine model, which also underlies actin-independent cell migration. Recently, the trans-epithelial fluid flux and the hydraulic pressure gradient have been explicitly measured for a variety of cellular and tissue model systems across various species. For the kidney, it was shown that tubular epithelial cells behave as active mechanical fluid pumps: the trans-epithelial fluid flux depends on the hydraulic pressure difference across the epithelial layer. When a stall pressure is reached, the fluid flux vanishes. Hydraulic forces generated from active fluid pumping are important in tissue morphogenesis and homeostasis, and could also underlie multiple morphogenic events seen in other developmental contexts. In this review, we highlight findings that examined the role of trans-epithelial fluid flux and hydraulic pressure gradient in driving tissue-scale morphogenesis. We also review organ pathophysiology due to impaired fluid pumping and the loss of hydraulic pressure sensing at the cellular scale. Finally, we draw an analogy between cellular fluidic pumps and a connected network of water pumps in a city. The dynamics of fluid transport in an active and adaptive network is determined globally at the systemic level, and transport in such a network is best when each pump is operating at its optimal efficiency.
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Affiliation(s)
- Mohammad Ikbal Choudhury
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, United States; Institute of NanoBioTechnology, Johns Hopkins University, Baltimore, MD 21218, United States; Department of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, United States
| | - Morgan A Benson
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, United States; Institute of NanoBioTechnology, Johns Hopkins University, Baltimore, MD 21218, United States
| | - Sean X Sun
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, United States; Institute of NanoBioTechnology, Johns Hopkins University, Baltimore, MD 21218, United States; Center for Cell Dynamics, Johns Hopkins University, Baltimore, MD 21218, United States.
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4
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Hellenthal KEM, Brabenec L, Gross ER, Wagner NM. TRP Channels as Sensors of Aldehyde and Oxidative Stress. Biomolecules 2021; 11:biom11101401. [PMID: 34680034 PMCID: PMC8533644 DOI: 10.3390/biom11101401] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 09/20/2021] [Accepted: 09/22/2021] [Indexed: 12/15/2022] Open
Abstract
The transient receptor potential (TRP) cation channel superfamily comprises more than 50 channels that play crucial roles in physiological processes. TRP channels are responsive to several exogenous and endogenous biomolecules, with aldehydes emerging as a TRP channel trigger contributing to a cellular cascade that can lead to disease pathophysiology. The body is not only exposed to exogenous aldehydes via tobacco products or alcoholic beverages, but also to endogenous aldehydes triggered by lipid peroxidation. In response to lipid peroxidation from inflammation or organ injury, polyunsaturated fatty acids undergo lipid peroxidation to aldehydes, such as 4-hydroxynonenal. Reactive aldehydes activate TRP channels via aldehyde-induced protein adducts, leading to the release of pro-inflammatory mediators driving the pathophysiology caused by cellular injury, including inflammatory pain and organ reperfusion injury. Recent studies have outlined how aldehyde dehydrogenase 2 protects against aldehyde toxicity through the clearance of toxic aldehydes, indicating that targeting the endogenous aldehyde metabolism may represent a novel treatment strategy. An addition approach can involve targeting specific TRP channel regions to limit the triggering of a cellular cascade induced by aldehydes. In this review, we provide a comprehensive summary of aldehydes, TRP channels, and their interactions, as well as their role in pathological conditions and the different therapeutical treatment options.
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Affiliation(s)
- Katharina E. M. Hellenthal
- Department of Anesthesiology, Intensive Care and Pain Medicine, University Hospital Muenster, 48149 Muenster, Germany; (K.E.M.H.); (L.B.)
| | - Laura Brabenec
- Department of Anesthesiology, Intensive Care and Pain Medicine, University Hospital Muenster, 48149 Muenster, Germany; (K.E.M.H.); (L.B.)
| | - Eric R. Gross
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University, Stanford, CA 94305, USA;
| | - Nana-Maria Wagner
- Department of Anesthesiology, Intensive Care and Pain Medicine, University Hospital Muenster, 48149 Muenster, Germany; (K.E.M.H.); (L.B.)
- Correspondence: ; Tel.: +49-251-83-46837
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5
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Role of the AMPK/ACC Signaling Pathway in TRPP2-Mediated Head and Neck Cancer Cell Proliferation. BIOMED RESEARCH INTERNATIONAL 2020; 2020:4375075. [PMID: 33274210 PMCID: PMC7683127 DOI: 10.1155/2020/4375075] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 09/21/2020] [Accepted: 11/02/2020] [Indexed: 12/24/2022]
Abstract
Transient receptor potential polycystic 2 (TRPP2) exerts vital roles in various types of cancer; however, its underlying mechanisms remain largely unknown. This study is aimed at investigating whether knockdown of TRPP2 affected the AMP-activated protein kinase (AMPK)/acetyl-CoA carboxylase (ACC) signaling pathway and the proliferation of HN-4, cell line originating from human oral and hypopharyngeal squamous cell carcinoma. In addition, the interactions among AMPK/ACC, AMPK/protein kinase RNA-like endoplasmic reticulum kinase (PERK)/eukaryotic initiation factor 2α (eIF2α) and TRPP2/PERK/eIF2α signaling pathways, and their association with cell proliferation were also explored. The results showed that the relative expression levels of phosphorylated (p)-ACC, p-PERK, and p-eIF2α in HN-4 cells were significantly increased following treatment with 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) and significantly decreased in cells treated with compound C. Therefore, consistent with previous studies, the AMPK/ACC and AMPK/PERK/eIF2α signaling pathways were upregulated and downregulated following treatment with an AMPK agonist and inhibitor, respectively. Furthermore, TRPP2 knockdown decreased p-PERK and p-eIF2α expression levels and increased those of p-AMPK and p-ACC. Additionally, knockdown of TRPP2 increased HN-4 cell proliferation, while treatment with an AMPK inhibitor or agonist increased or inhibited TRPP2-specific siRNA-mediated cell proliferation, respectively. In conclusion, silencing of TRPP2 expression increased HN-4 cell proliferation via inhibiting the PERK/eIF2α signaling pathway, while the AMPK/ACC signaling pathway was possibly activated by a feedback mechanism to reduce enhanced cell proliferation.
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Peña-Oyarzun D, Batista-Gonzalez A, Kretschmar C, Burgos P, Lavandero S, Morselli E, Criollo A. New emerging roles of Polycystin-2 in the regulation of autophagy. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2020; 354:165-186. [PMID: 32475472 DOI: 10.1016/bs.ircmb.2020.02.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Polycystin-2 (PC2) is a calcium channel that can be found in the endoplasmic reticulum, the plasmatic membrane, and the primary cilium. The structure of PC2 is characterized by a highly ordered C-terminal tail with an EF-motif (calcium-binding domain) and a canonical coiled-coil domain (CCD; interaction domain), and its activity is regulated by interacting partners and post-translational modifications. Calcium mobilization into the cytosol by PC2 has been mainly associated with cell growth and differentiation, and therefore mutations or dysfunction of PC2 lead to renal and cardiac consequences. Interestingly, PC2-related pathologies are usually treated with rapamycin, an autophagy stimulator. Autophagy is an intracellular degradation process where recycling material is sequestered into autophagosomes and then hydrolyzed by fusion with a lysosome. Interestingly, several studies have provided evidence that PC2 may be required for autophagy, suggesting that PC2 maintains a physiologic catabolic state.
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Affiliation(s)
- Daniel Peña-Oyarzun
- Instituto de Investigación en Ciencias Odontológicas (ICOD), Facultad de Odontología, Universidad de Chile, Santiago, Chile; Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Ana Batista-Gonzalez
- Instituto de Investigación en Ciencias Odontológicas (ICOD), Facultad de Odontología, Universidad de Chile, Santiago, Chile; Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Catalina Kretschmar
- Instituto de Investigación en Ciencias Odontológicas (ICOD), Facultad de Odontología, Universidad de Chile, Santiago, Chile; Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Paulina Burgos
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Sergio Lavandero
- Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile; Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile; Cardiology Division, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Eugenia Morselli
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
| | - Alfredo Criollo
- Instituto de Investigación en Ciencias Odontológicas (ICOD), Facultad de Odontología, Universidad de Chile, Santiago, Chile; Advanced Center for Chronic Diseases (ACCDiS), Facultad de Ciencias Químicas y Farmacéuticas & Facultad de Medicina, Universidad de Chile, Santiago, Chile.
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7
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Futel M, Le Bouffant R, Buisson I, Umbhauer M, Riou JF. Characterization of potential TRPP2 regulating proteins in early Xenopus embryos. J Cell Biochem 2018; 119:10338-10350. [PMID: 30171710 DOI: 10.1002/jcb.27376] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 07/02/2018] [Indexed: 11/10/2022]
Abstract
Transient receptor potential cation channel-2 (TRPP2) is a nonspecific Ca2+ -dependent cation channel with versatile functions including control of extracellular calcium entry at the plasma membrane, release of intracellular calcium ([Ca2+ ]i) from internal stores of endoplasmic reticulum, and calcium-dependent mechanosensation in the primary cilium. In early Xenopus embryos, TRPP2 is expressed in cilia of the gastrocoel roof plate (GRP) involved in the establishment of left-right asymmetry, and in nonciliated kidney field (KF) cells, where it plays a central role in early specification of nephron tubule cells dependent on [Ca2+ ]i signaling. Identification of proteins binding to TRPP2 in embryo cells can provide interesting clues about the mechanisms involved in its regulation during these various processes. Using mass spectrometry, we have therefore characterized proteins from late gastrula/early neurula stage embryos coimmunoprecipitating with TRPP2. Binding of three of these proteins, golgin A2, protein kinase-D1, and disheveled-2 has been confirmed by immunoblotting analysis of TRPP2-coprecipitated proteins. Expression analysis of the genes, respectively, encoding these proteins, golga2, prkd1, and dvl2 indicates that they are likely to play a role in these two regions. Golga2 and prkd1 are expressed at later stage in the developing pronephric tubule where golgin A2 and protein kinase-D1 might also interact with TRPP2. Colocalization experiments using exogenously expressed fluorescent versions of TRPP2 and dvl2 in GRP and KF reveal that these two proteins are generally not coexpressed, and only colocalized in discrete region of cells. This was observed in KF cells, but does not appear to occur in the apical ciliated region of GRP cells.
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Affiliation(s)
- Mélinée Futel
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, IBPS, Laboratoire de Biologie du Développement, UMR7622, 9 quai Saint-Bernard, Paris F-75005, France
| | - Ronan Le Bouffant
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, IBPS, Laboratoire de Biologie du Développement, UMR7622, 9 quai Saint-Bernard, Paris F-75005, France
| | - Isabelle Buisson
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, IBPS, Laboratoire de Biologie du Développement, UMR7622, 9 quai Saint-Bernard, Paris F-75005, France
| | - Muriel Umbhauer
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, IBPS, Laboratoire de Biologie du Développement, UMR7622, 9 quai Saint-Bernard, Paris F-75005, France
| | - Jean-François Riou
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, IBPS, Laboratoire de Biologie du Développement, UMR7622, 9 quai Saint-Bernard, Paris F-75005, France
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8
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Hofherr A, Seger C, Fitzpatrick F, Busch T, Michel E, Luan J, Osterried L, Linden F, Kramer-Zucker A, Wakimoto B, Schütze C, Wiedemann N, Artati A, Adamski J, Walz G, Kunji ERS, Montell C, Watnick T, Köttgen M. The mitochondrial transporter SLC25A25 links ciliary TRPP2 signaling and cellular metabolism. PLoS Biol 2018; 16:e2005651. [PMID: 30080851 PMCID: PMC6095617 DOI: 10.1371/journal.pbio.2005651] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 08/16/2018] [Accepted: 07/27/2018] [Indexed: 02/02/2023] Open
Abstract
Cilia are organelles specialized in movement and signal transduction. The ciliary transient receptor potential ion channel polycystin-2 (TRPP2) controls elementary cilia-mediated physiological functions ranging from male fertility and kidney development to left-right patterning. However, the molecular components translating TRPP2 channel-mediated Ca2+ signals into respective physiological functions are unknown. Here, we show that the Ca2+-regulated mitochondrial ATP-Mg/Pi solute carrier 25 A 25 (SLC25A25) acts downstream of TRPP2 in an evolutionarily conserved metabolic signaling pathway. We identify SLC25A25 as an essential component in this cilia-dependent pathway using a genome-wide forward genetic screen in Drosophila melanogaster, followed by a targeted analysis of SLC25A25 function in zebrafish left-right patterning. Our data suggest that TRPP2 ion channels regulate mitochondrial SLC25A25 transporters via Ca2+ establishing an evolutionarily conserved molecular link between ciliary signaling and mitochondrial metabolism.
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Affiliation(s)
- Alexis Hofherr
- Renal Division, Department of Medicine, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
- Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg im Breisgau, Germany
- Faculty of Biology, University of Freiburg, Freiburg im Breisgau, Germany
| | - Claudia Seger
- Renal Division, Department of Medicine, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Fiona Fitzpatrick
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Tilman Busch
- Renal Division, Department of Medicine, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Elisabeth Michel
- Renal Division, Department of Medicine, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Jingting Luan
- Renal Division, Department of Medicine, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Lea Osterried
- Renal Division, Department of Medicine, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Frieder Linden
- Renal Division, Department of Medicine, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Albrecht Kramer-Zucker
- Renal Division, Department of Medicine, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Barbara Wakimoto
- Department of Biology, University of Washington, Seattle, Washington, United States of America
| | - Conny Schütze
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Nils Wiedemann
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg im Breisgau, Germany
| | - Anna Artati
- Institute of Experimental Genetics, Genome Analysis Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Jerzy Adamski
- Institute of Experimental Genetics, Genome Analysis Center, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Lehrstuhl für Experimentelle Genetik, Technische Universität München, Freising-Weihenstephan, Germany
- German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Gerd Walz
- Renal Division, Department of Medicine, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg im Breisgau, Germany
| | - Edmund R. S. Kunji
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge, United Kingdom
| | - Craig Montell
- Neuroscience Research Institute and Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, California, United States of America
| | - Terry Watnick
- Division of Nephrology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Michael Köttgen
- Renal Division, Department of Medicine, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
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9
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System analysis of gene mutations and clinical phenotype in Chinese patients with autosomal-dominant polycystic kidney disease. Sci Rep 2016; 6:35945. [PMID: 27782177 PMCID: PMC5080601 DOI: 10.1038/srep35945] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 10/07/2016] [Indexed: 02/05/2023] Open
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disorder mainly caused by mutation in PKD1/PKD2. However, ethnic differences in mutations, the association between mutation genotype/clinical phenotype, and the clinical applicable value of mutation detection are poorly understood. We made systematically analysis of Chinese ADPKD patients based on a next-generation sequencing platform. Among 148 ADPKD patients enrolled, 108 mutations were detected in 127 patients (85.8%). Compared with mutations in Caucasian published previously, the PKD2 mutation detection rate was lower, and patients carrying the PKD2 mutation invariably carried the PKD1 mutation. The definite pathogenic mutation detection rate was lower, whereas the multiple mutations detection rate was higher in Chinese patients. Then, we correlated PKD1/PKD2 mutation data and clinical data: patients with mutation exhibited a more severe phenotype; patients with >1 mutations exhibited a more severe phenotype; patients with pathogenic mutations exhibited a more severe phenotype. Thus, the PKD1/PKD2 mutation status differed by ethnicity, and the PKD1/PKD2 genotype may affect the clinical phenotype of ADPKD. Furthermore, it makes sense to detect PKD1/PKD2 mutation status for early diagnosis and prognosis, perhaps as early as the embryo/zygote stage, to facilitate early clinical intervention and family planning.
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10
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Function and regulation of TRPP2 ion channel revealed by a gain-of-function mutant. Proc Natl Acad Sci U S A 2016; 113:E2363-72. [PMID: 27071085 DOI: 10.1073/pnas.1517066113] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Mutations in polycystin-1 and transient receptor potential polycystin 2 (TRPP2) account for almost all clinically identified cases of autosomal dominant polycystic kidney disease (ADPKD), one of the most common human genetic diseases. TRPP2 functions as a cation channel in its homomeric complex and in the TRPP2/polycystin-1 receptor/ion channel complex. The activation mechanism of TRPP2 is unknown, which significantly limits the study of its function and regulation. Here, we generated a constitutively active gain-of-function (GOF) mutant of TRPP2 by applying a mutagenesis scan on the S4-S5 linker and the S5 transmembrane domain, and studied functional properties of the GOF TRPP2 channel. We found that extracellular divalent ions, including Ca(2+), inhibit the permeation of monovalent ions by directly blocking the TRPP2 channel pore. We also found that D643, a negatively charged amino acid in the pore, is crucial for channel permeability. By introducing single-point ADPKD pathogenic mutations into the GOF TRPP2, we showed that different mutations could have completely different effects on channel activity. The in vivo function of the GOF TRPP2 was investigated in zebrafish embryos. The results indicate that, compared with wild type (WT), GOF TRPP2 more efficiently rescued morphological abnormalities, including curly tail and cyst formation in the pronephric kidney, caused by down-regulation of endogenous TRPP2 expression. Thus, we established a GOF TRPP2 channel that can serve as a powerful tool for studying the function and regulation of TRPP2. The GOF channel may also have potential application for developing new therapeutic strategies for ADPKD.
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Calcium, TRPC channels, and regulation of the actin cytoskeleton in podocytes: towards a future of targeted therapies. Pediatr Nephrol 2016; 31:1047-54. [PMID: 26490951 PMCID: PMC4840088 DOI: 10.1007/s00467-015-3224-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 09/05/2015] [Accepted: 09/14/2015] [Indexed: 12/14/2022]
Abstract
With more than 6,000 new pediatric patients with treatment-resistant nephrotic syndrome in the US each year alone, the unmet need for novel, podocyte-specific therapies is substantial. Recently, the established therapeutic benefit of angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARB) was used as a starting point to gain insight into the pathomechanism of primary podocytopathies. A calcium (Ca(2+))-mediated pathway has been identified that connects the angiotensin type 1 receptor (AT1R) to podocyte cytoskeletal dynamics, essential for a functioning glomerular filtration barrier. This discovery provided an important missing piece in our understanding of the pathomechanism of filter barrier damage, revealing Ca(2+) signaling as critical for podocyte health and disease. The identification of the two Ca(2+) permeant channels TRPC5 and TRPC6 as mediators of this pathway not only bolstered the importance of podocyte cytoskeleton dynamics but also revealed promising drug targets for treatment-resistant nephrotic syndrome. This review will focus on this novel signaling pathway in primary podocytopathies and its implications for next-generation therapies for glomerular disease.
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12
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The functions of TRPP2 in the vascular system. Acta Pharmacol Sin 2016; 37:13-8. [PMID: 26725733 DOI: 10.1038/aps.2015.126] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 11/02/2015] [Indexed: 12/19/2022] Open
Abstract
TRPP2 (polycystin-2, PC2 or PKD2), encoded by the PKD2 gene, is a non-selective cation channel with a large single channel conductance and high Ca(2+) permeability. In cell membrane, TRPP2, along with polycystin-1, TRPV4 and TRPC1, functions as a mechanotransduction channel. In the endoplasmic reticulum, TRPP2 modulates intracellular Ca(2+) release associated with IP3 receptors and the ryanodine receptors. Noteworthily, TRPP2 is widely expressed in vascular endothelial and smooth muscle cells of all major vascular beds, and contributes to the regulation of vessel function. The mutation of the PKD2 gene is a major cause of autosomal dominant polycystic kidney disease (ADPKD), which is not only a common genetic disease of the kidney but also a systemic disorder associated with abnormalities in the vasculature; cardiovascular complications are the leading cause of mortality and morbidity in ADPKD patients. This review provides an overview of the current knowledge regarding the TRPP2 protein and its possible role in cardiovascular function and related diseases.
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13
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Moreau M, Néant I, Webb SE, Miller AL, Riou JF, Leclerc C. Ca(2+) coding and decoding strategies for the specification of neural and renal precursor cells during development. Cell Calcium 2015; 59:75-83. [PMID: 26744233 DOI: 10.1016/j.ceca.2015.12.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Revised: 12/07/2015] [Accepted: 12/11/2015] [Indexed: 01/03/2023]
Abstract
During embryogenesis, a rise in intracellular Ca(2+) is known to be a widespread trigger for directing stem cells towards a specific tissue fate, but the precise Ca(2+) signalling mechanisms involved in achieving these pleiotropic effects are still poorly understood. In this review, we compare the Ca(2+) signalling events that appear to be one of the first steps in initiating and regulating both neural determination (neural induction) and kidney development (nephrogenesis). We have highlighted the necessary and sufficient role played by Ca(2+) influx and by Ca(2+) transients in the determination and differentiation of pools of neural or renal precursors. We have identified new Ca(2+) target genes involved in neural induction and we showed that the same Ca(2+) early target genes studied are not restricted to neural tissue but are also present in other tissues, principally in the pronephros. In this review, we also described a mechanism whereby the transcriptional control of gene expression during neurogenesis and nephrogenesis might be directly controlled by Ca(2+) signalling. This mechanism involves members of the Kcnip family such that a change in their binding properties to specific DNA sites is a result of Ca(2+) binding to EF-hand motifs. The different functions of Ca(2+) signalling during these two events illustrate the versatility of Ca(2+) as a second messenger.
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Affiliation(s)
- Marc Moreau
- Université Toulouse 3, Centre de Biologie du Développement, 118 route de Narbonne, F31062 Toulouse Cedex 04, France; CNRS UMR5547, Toulouse F31062, France
| | - Isabelle Néant
- Université Toulouse 3, Centre de Biologie du Développement, 118 route de Narbonne, F31062 Toulouse Cedex 04, France; CNRS UMR5547, Toulouse F31062, France
| | - Sarah E Webb
- Division of Life Science & State Key Laboratory of Molecular Neuroscience, HKUST, Clear Water Bay, Hong Kong, People's Republic of China
| | - Andrew L Miller
- Division of Life Science & State Key Laboratory of Molecular Neuroscience, HKUST, Clear Water Bay, Hong Kong, People's Republic of China; MBL, Woods Hole, MA, USA
| | - Jean-François Riou
- Université Pierre et Marie Curie-Paris VI, Equipe "Signalisation et Morphogenèse", UMR7622-Biologie du Développement, 9, quai Saint-Bernard, 75005 Paris, France; CNRS, Equipe "Signalisation et Morphogenèse", UMR7622-Biologie du Développement, 9, quai Saint-Bernard, 75005 Paris, France
| | - Catherine Leclerc
- Université Toulouse 3, Centre de Biologie du Développement, 118 route de Narbonne, F31062 Toulouse Cedex 04, France; CNRS UMR5547, Toulouse F31062, France.
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14
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Cantero MDR, Velázquez IF, Streets AJ, Ong ACM, Cantiello HF. The cAMP Signaling Pathway and Direct Protein Kinase A Phosphorylation Regulate Polycystin-2 (TRPP2) Channel Function. J Biol Chem 2015; 290:23888-96. [PMID: 26269590 DOI: 10.1074/jbc.m115.661082] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Indexed: 11/06/2022] Open
Abstract
Polycystin-2 (PC2) is a TRP-type, Ca(2+)-permeable non-selective cation channel that plays an important role in Ca(2+) signaling in renal and non-renal cells. The effect(s) of the cAMP pathway and kinase mediated phosphorylation of PC2 seem to be relevant to PC2 trafficking and its interaction with polycystin-1. However, the role of PC2 phosphorylation in channel function is still poorly defined. Here we reconstituted apical membranes of term human syncytiotrophoblast (hST), containing endogenous PC2 (PC2hst), and in vitro translated channel protein (PC2iv). Addition of the catalytic subunit of PKA increased by 566% the spontaneous PC2hst channel activity in the presence of ATP. Interestingly, 8-Br-cAMP also stimulated spontaneous PC2hst channel activity in the absence of the exogenous kinase. Either stimulation was inhibited by addition of alkaline phosphatase, which in turn, was reversed by the phosphatase inhibitor vanadate. Neither maneuver modified the single channel conductance but instead increased channel mean open time. PKA directly phosphorylated PC2, which increased the mean open time but not the single channel conductance of the channel. PKA phosphorylation did not modify either R742X truncated or S829A-mutant PC2iv channel function. The data indicate that the cAMP pathway regulates PC2-mediated cation transport in the hST. The relevant PKA site for PC2 channel regulation centers on a single residue serine 829, in the carboxyl terminus.
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Affiliation(s)
- María del Rocío Cantero
- From the Cátedra de Biofísica, Facultad de Odontología, Universidad de Buenos Aires, C1122AAH Buenos Aires, Argentina and
| | - Irina F Velázquez
- From the Cátedra de Biofísica, Facultad de Odontología, Universidad de Buenos Aires, C1122AAH Buenos Aires, Argentina and
| | - Andrew J Streets
- Kidney Genetics Group, Academic Nephrology Unit, The Henry Wellcome Laboratories for Medical Research, University of Sheffield Medical School, Sheffield S10 2RX, United Kingdom
| | - Albert C M Ong
- Kidney Genetics Group, Academic Nephrology Unit, The Henry Wellcome Laboratories for Medical Research, University of Sheffield Medical School, Sheffield S10 2RX, United Kingdom
| | - Horacio F Cantiello
- From the Cátedra de Biofísica, Facultad de Odontología, Universidad de Buenos Aires, C1122AAH Buenos Aires, Argentina and
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15
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Evolutionary dynamics of metazoan TRP channels. Pflugers Arch 2015; 467:2043-53. [DOI: 10.1007/s00424-015-1705-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 03/19/2015] [Accepted: 03/19/2015] [Indexed: 10/23/2022]
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16
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Futel M, Leclerc C, Le Bouffant R, Buisson I, Néant I, Umbhauer M, Moreau M, Riou JF. TRPP2-dependent Ca2+ signaling in dorso-lateral mesoderm is required for kidney field establishment in Xenopus. J Cell Sci 2015; 128:888-99. [PMID: 25588842 DOI: 10.1242/jcs.155499] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
In Xenopus laevis embryos, kidney field specification is dependent on retinoic acid (RA) and coincides with a dramatic increase of Ca(2+) transients, but the role of Ca(2+) signaling in the kidney field is unknown. Here, we identify TRPP2, a member of the transient receptor potential (TRP) superfamily of channel proteins encoded by the pkd2 gene, as a central component of Ca(2+) signaling in the kidney field. TRPP2 is strongly expressed at the plasma membrane where it might regulate extracellular Ca(2+) entry. Knockdown of pkd2 in the kidney field results in the downregulation of pax8, but not of other kidney field genes (lhx1, osr1 and osr2). We further show that inhibition of Ca(2+) signaling with an inducible Ca(2+) chelator also causes downregulation of pax8, and that pkd2 knockdown results in a severe inhibition of Ca(2+) transients in kidney field explants. Finally, we show that disruption of RA results both in an inhibition of intracellular Ca(2+) signaling and of TRPP2 incorporation into the plasma membrane of kidney field cells. We propose that TRPP2-dependent Ca(2+) signaling is a key component of pax8 regulation in the kidney field downstream of RA-mediated non-transcriptional control of TRPP2.
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Affiliation(s)
- Mélinée Futel
- Université Pierre et Marie Curie-Paris VI, Equipe 'Signalisation et Morphogenèse', UMR7622-Biologie du Développement, 9, quai Saint-Bernard, 75005 Paris, France CNRS, Equipe 'Signalisation et Morphogenèse', UMR7622-Biologie du Développement, 9, quai Saint-Bernard, 75005 Paris, France
| | - Catherine Leclerc
- Université Toulouse 3, Centre de Biologie du Développement, 118 route de Narbonne, F31062 Toulouse, Cedex 04, France CNRS UMR5547, Toulouse F31062, France
| | - Ronan Le Bouffant
- Université Pierre et Marie Curie-Paris VI, Equipe 'Signalisation et Morphogenèse', UMR7622-Biologie du Développement, 9, quai Saint-Bernard, 75005 Paris, France CNRS, Equipe 'Signalisation et Morphogenèse', UMR7622-Biologie du Développement, 9, quai Saint-Bernard, 75005 Paris, France
| | - Isabelle Buisson
- Université Pierre et Marie Curie-Paris VI, Equipe 'Signalisation et Morphogenèse', UMR7622-Biologie du Développement, 9, quai Saint-Bernard, 75005 Paris, France CNRS, Equipe 'Signalisation et Morphogenèse', UMR7622-Biologie du Développement, 9, quai Saint-Bernard, 75005 Paris, France
| | - Isabelle Néant
- Université Toulouse 3, Centre de Biologie du Développement, 118 route de Narbonne, F31062 Toulouse, Cedex 04, France CNRS UMR5547, Toulouse F31062, France
| | - Muriel Umbhauer
- Université Pierre et Marie Curie-Paris VI, Equipe 'Signalisation et Morphogenèse', UMR7622-Biologie du Développement, 9, quai Saint-Bernard, 75005 Paris, France CNRS, Equipe 'Signalisation et Morphogenèse', UMR7622-Biologie du Développement, 9, quai Saint-Bernard, 75005 Paris, France
| | - Marc Moreau
- Université Toulouse 3, Centre de Biologie du Développement, 118 route de Narbonne, F31062 Toulouse, Cedex 04, France CNRS UMR5547, Toulouse F31062, France
| | - Jean-François Riou
- Université Pierre et Marie Curie-Paris VI, Equipe 'Signalisation et Morphogenèse', UMR7622-Biologie du Développement, 9, quai Saint-Bernard, 75005 Paris, France CNRS, Equipe 'Signalisation et Morphogenèse', UMR7622-Biologie du Développement, 9, quai Saint-Bernard, 75005 Paris, France
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17
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Villalta PC, Townsley MI. Transient receptor potential channels and regulation of lung endothelial permeability. Pulm Circ 2014; 3:802-15. [PMID: 25006396 DOI: 10.1086/674765] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 08/22/2013] [Indexed: 12/19/2022] Open
Abstract
This review highlights our current knowledge regarding expression of transient receptor potential (TRP) cation channels in lung endothelium and evidence for their involvement in regulation of lung endothelial permeability. Six mammalian TRP families have been identified and organized on the basis of sequence homology: TRPC (canonical), TRPV (vanilloid), TRPM (melastatin), TRPML (mucolipin), TRPP (polycystin), and TRPA (ankyrin). To date, only TRPC1/4, TRPC6, TRPV4, and TRPM2 have been extensively studied in lung endothelium. Calcium influx through each of these channels has been documented to increase lung endothelial permeability, although their channel-gating mechanisms, downstream signaling mechanisms, and impact on endothelial structure and barrier integrity differ. While other members of the TRPC, TRPV, and TRPM families may be expressed in lung endothelium, we have little or no evidence linking these to regulation of lung endothelial permeability. Further, neither the expression nor functional role(s) of any TRPML, TRPP, and TRPA family members has been studied in lung endothelium. In addition to this assessment organized by TRP channel family, we also discuss TRP channels and lung endothelial permeability from the perspective of lung endothelial heterogeneity, using outcomes of studies focused on TRPC1/4 and TRPV4 channels. The diversity within the TRP channel family and the relative paucity of information regarding roles of a number of these channels in lung endothelium make this field ripe for continued investigation.
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Affiliation(s)
- Patricia C Villalta
- Departments of Physiology and Medicine, Center for Lung Biology, University of South Alabama, Mobile, Alabama, USA
| | - Mary I Townsley
- Departments of Physiology and Medicine, Center for Lung Biology, University of South Alabama, Mobile, Alabama, USA
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18
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Peng G, Shi X, Kadowaki T. Evolution of TRP channels inferred by their classification in diverse animal species. Mol Phylogenet Evol 2014; 84:145-57. [PMID: 24981559 DOI: 10.1016/j.ympev.2014.06.016] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Revised: 06/05/2014] [Accepted: 06/17/2014] [Indexed: 12/11/2022]
Abstract
The functions of TRP channels have primarily been characterized in model organisms within a limited evolutionary context. We thus characterize the TRP channels in choanoflagellate, sponge, Cnidaria, Lophotrochozoa, and arthropods to understand how they emerged during early evolution of animals and have changed during diversification of various species. As previously reported, five metazoan TRP subfamily members (TRPA, TRPC, TRPM, TRPML, and TRPV) were identified in choanoflagellates, demonstrating that they evolved before the emergence of multicellular animals. TRPN was identified in Hydra magnipapillata, and therefore emerged in the last common ancestor of Cnidaria-Bilateria. A novel subfamily member (TRPVL) was identified in Cnidaria and Capitella teleta, indicating that it was present in the last common ancestor of Cnidaria-Bilateria but has since been lost in most bilaterians. The characterization of arthropod TRP channels revealed that Daphnia pulex and insects have specifically expanded the TRPA subfamily, which diverged from the ancient TRPA1 channel gene. The diversity of TRPA channels except TRPA1 was detectable even within a single insect family, namely the ant lineage. The present study demonstrates the evolutionary history of TRP channel genes, which may have diverged in conjunction with the specific habitats and life histories of individual species.
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Affiliation(s)
- Guangda Peng
- Department of Biological Sciences, Xi'an Jiaotong-Liverpool University, 111 Ren'ai Road, Suzhou Dushu Lake Higher Education Town, Jiangsu Province 215123, China
| | - Xiao Shi
- Department of Biological Sciences, Xi'an Jiaotong-Liverpool University, 111 Ren'ai Road, Suzhou Dushu Lake Higher Education Town, Jiangsu Province 215123, China
| | - Tatsuhiko Kadowaki
- Department of Biological Sciences, Xi'an Jiaotong-Liverpool University, 111 Ren'ai Road, Suzhou Dushu Lake Higher Education Town, Jiangsu Province 215123, China.
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Gowrisankar S, Lebo MS. Designing algorithms for determining significance of DNA missense changes. Methods Mol Biol 2014; 1168:251-62. [PMID: 24870140 DOI: 10.1007/978-1-4939-0847-9_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Humans differ from each other in their genomes by <1 %. This determines the difference in susceptibility to disease, phenotypes, and traits. Predominantly, when looking for causal disease mutations, protein-coding sequences are screened first since those have the highest probability of affecting the function of a protein. Recent technological advances have seen a rise in the number of experiments being conducted to study a variety of diseases from monogenic to complex traits. Several computational approaches have been developed to extract putative functional missense variants. In this chapter we review some of these approaches and describe a standard step-by-step procedure that can be used to classify variants for the purpose of clinical care. We also provide two examples demonstrating this approach, one for a patient with a dilated cardiomyopathy diagnosis, and the other for a patient with an unknown etiology undergoing whole-genome sequencing (WGS).
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Affiliation(s)
- Sivakumar Gowrisankar
- Novartis Institutes for Biomedical Research, 500 Technology Square, 840-14, Cambridge, MA, 02139, USA,
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20
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Abstract
It has been exciting times since the identification of polycystic kidney disease 1 (PKD1) and PKD2 as the genes mutated in autosomal dominant polycystic kidney disease (ADPKD). Biological roles of the encoded proteins polycystin-1 and TRPP2 have been deduced from phenotypes in ADPKD patients, but recent insights from vertebrate and invertebrate model organisms have significantly expanded our understanding of the physiological functions of these proteins. The identification of additional TRPP (TRPP3 and TRPP5) and polycystin-1-like proteins (PKD1L1, PKD1L2, PKD1L3, and PKDREJ) has added yet another layer of complexity to these fascinating cellular signalling units. TRPP proteins assemble with polycystin-1 family members to form receptor-channel complexes. These protein modules have important biological roles ranging from tubular morphogenesis to determination of left-right asymmetry. The founding members of the polycystin family, TRPP2 and polycystin-1, are a prime example of how studying human disease genes can provide insights into fundamental biological mechanisms using a so-called "reverse translational" approach (from bedside to bench). Here, we discuss the current literature on TRPP ion channels and polycystin-1 family proteins including expression, structure, physical interactions, physiology, and lessons from animal model systems and human disease.
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Affiliation(s)
- Mariam Semmo
- Renal Division, Department of Medicine, University Medical Centre Freiburg, Hugstetter Straße 55, 79106, Freiburg, Germany,
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21
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Vandewauw I, Owsianik G, Voets T. Systematic and quantitative mRNA expression analysis of TRP channel genes at the single trigeminal and dorsal root ganglion level in mouse. BMC Neurosci 2013; 14:21. [PMID: 23410158 PMCID: PMC3576292 DOI: 10.1186/1471-2202-14-21] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 01/31/2013] [Indexed: 11/30/2022] Open
Abstract
Background Somatosensory nerve fibres arising from cell bodies within the trigeminal ganglia (TG) in the head and from a string of dorsal root ganglia (DRG) located lateral to the spinal cord convey endogenous and environmental stimuli to the central nervous system. Although several members of the transient receptor potential (TRP) superfamily of cation channels have been implicated in somatosensation, the expression levels of TRP channel genes in the individual sensory ganglia have never been systematically studied. Results Here, we used quantitative real-time PCR to analyse and compare mRNA expression of all TRP channels in TG and individual DRGs from 27 anatomically defined segments of the spinal cord of the mouse. At the mRNA level, 17 of the 28 TRP channel genes, TRPA1, TRPC1, TRPC3, TRPC4, TRPC5, TRPM2, TRPM3, TRPM4, TRPM5, TRPM6, TRPM7, TRPM8, TRPV1, TRPV2, TRPV4, TRPML1 and TRPP2, were detectable in every tested ganglion. Notably, four TRP channels, TRPC4, TRPM4, TRPM8 and TRPV1, showed statistically significant variation in mRNA levels between DRGs from different segments, suggesting ganglion-specific regulation of TRP channel gene expression. These ganglion-to-ganglion differences in TRP channel transcript levels may contribute to the variability in sensory responses in functional studies. Conclusions We developed, compared and refined techniques to quantitatively analyse the relative mRNA expression of all TRP channel genes at the single ganglion level. This study also provides for the first time a comparative mRNA distribution profile in TG and DRG along the entire vertebral column for the mammalian TRP channel family.
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Affiliation(s)
- Ine Vandewauw
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine and TRP Research Platform Leuven, KU Leuven, Leuven, Belgium
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22
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Frank V, Habbig S, Bartram MP, Eisenberger T, Veenstra-Knol HE, Decker C, Boorsma RA, Göbel H, Nürnberg G, Griessmann A, Franke M, Borgal L, Kohli P, Völker LA, Dötsch J, Nürnberg P, Benzing T, Bolz HJ, Johnson C, Gerkes EH, Schermer B, Bergmann C. Mutations in NEK8 link multiple organ dysplasia with altered Hippo signalling and increased c-MYC expression. Hum Mol Genet 2013; 22:2177-85. [DOI: 10.1093/hmg/ddt070] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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23
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Irazabal MV, Torres VE. Experimental therapies and ongoing clinical trials to slow down progression of ADPKD. Curr Hypertens Rev 2013; 9:44-59. [PMID: 23971644 PMCID: PMC4067974 DOI: 10.2174/1573402111309010008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 10/19/2012] [Accepted: 11/30/2012] [Indexed: 12/19/2022]
Abstract
The improvement of imaging techniques over the years has contributed to the understanding of the natural history of autosomal dominant polycystic kidney disease, and facilitated the observation of its structural progression. Advances in molecular biology and genetics have made possible a greater understanding of the genetics, molecular, and cellular pathophysiologic mechanisms responsible for its development and have laid the foundation for the development of potential new therapies. Therapies targeting genetic mechanisms in ADPKD have inherent limitations. As a result, most experimental therapies at the present time are aimed at delaying the growth of the cysts and associated interstitial inflammation and fibrosis by targeting tubular epithelial cell proliferation and fluid secretion by the cystic epithelium. Several interventions affecting many of the signaling pathways disrupted in ADPKD have been effective in animal models and some are currently being tested in clinical trials.
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Affiliation(s)
- Maria V. Irazabal
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester MN, USA
| | - Vicente E. Torres
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester MN, USA
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24
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Mekahli D, Parys JB, Bultynck G, Missiaen L, De Smedt H. Polycystins and cellular Ca2+ signaling. Cell Mol Life Sci 2012; 70:2697-712. [PMID: 23076254 PMCID: PMC3708286 DOI: 10.1007/s00018-012-1188-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Revised: 10/01/2012] [Accepted: 10/02/2012] [Indexed: 12/19/2022]
Abstract
The cystic phenotype in autosomal dominant polycystic kidney disease is characterized by a profound dysfunction of many cellular signaling patterns, ultimately leading to an increase in both cell proliferation and apoptotic cell death. Disturbance of normal cellular Ca2+ signaling seems to be a primary event and is clearly involved in many pathways that may lead to both types of cellular responses. In this review, we summarize the current knowledge about the molecular and functional interactions between polycystins and multiple components of the cellular Ca2+-signaling machinery. In addition, we discuss the relevant downstream responses of the changed Ca2+ signaling that ultimately lead to increased proliferation and increased apoptosis as observed in many cystic cell types.
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Affiliation(s)
- D. Mekahli
- Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, KU Leuven, Campus Gasthuisberg O/N-I, B-802, Herestraat 49, 3000 Leuven, Belgium
| | - Jan B. Parys
- Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, KU Leuven, Campus Gasthuisberg O/N-I, B-802, Herestraat 49, 3000 Leuven, Belgium
| | - G. Bultynck
- Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, KU Leuven, Campus Gasthuisberg O/N-I, B-802, Herestraat 49, 3000 Leuven, Belgium
| | - L. Missiaen
- Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, KU Leuven, Campus Gasthuisberg O/N-I, B-802, Herestraat 49, 3000 Leuven, Belgium
| | - H. De Smedt
- Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, KU Leuven, Campus Gasthuisberg O/N-I, B-802, Herestraat 49, 3000 Leuven, Belgium
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The TRPP Signaling Module: TRPP2/Polycystin-1 and TRPP2/PKD1L1. METHODS IN PHARMACOLOGY AND TOXICOLOGY 2012. [DOI: 10.1007/978-1-62703-077-9_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Temmerman F, Missiaen L, Bammens B, Laleman W, Cassiman D, Verslype C, van Pelt J, Nevens F. Systematic review: the pathophysiology and management of polycystic liver disease. Aliment Pharmacol Ther 2011; 34:702-13. [PMID: 21790682 DOI: 10.1111/j.1365-2036.2011.04783.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Polycystic liver diseases (PCLD) represent a group of genetic disorders in which cysts occur solely in the liver, or together with renal cysts. Most of the patients with PCLD are asymptomatic, however, in some patients, expansion of liver cysts causes invalidating abdominal symptoms. AIM To provide a systemic review on the pathophysiology and management of PCLD. METHODS A PubMed search was undertaken to identify relevant literature using search terms including polycystic liver disease, pathophysiology, surgical and medical management. RESULTS The most common complication in patients with PCLD is extensive hepatomegaly, which may lead to malnutrition and can be lethal. Conservative surgical approaches are only partially effective and do not change the natural course of the disease. Liver transplantation has been successfully performed in PCLD, however, in an era of organ shortage, medical management needs to be evaluated. A better understanding of the pathophysiology and the availability of animal models have already identified promising drugs. Abnormalities in cholangiocyte proliferation/apoptosis and enhanced fluid secretion are key factors in the pathophysiology. It has been demonstrated in rodents and in humans that somatostatin analogues diminish liver volume. The role of the inhibitors of the mammalian target of rapamycin (mTOR) in the management of PCLD is still under investigation. CONCLUSIONS The exact pathophysiology of polycystic liver disease still remains unclear. In symptomatic patients, none of the currently available surgical options except liver transplantation have been shown to change the natural course of the disease. The use of somatostatin analogues has been shown to diminish liver volume.
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Affiliation(s)
- F Temmerman
- Department of Hepatology, UZ Gasthuisberg, K.U. Leuven, Leuven, Belgium
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Drosophila sperm swim backwards in the female reproductive tract and are activated via TRPP2 ion channels. PLoS One 2011; 6:e20031. [PMID: 21625494 PMCID: PMC3098850 DOI: 10.1371/journal.pone.0020031] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Accepted: 04/10/2011] [Indexed: 12/31/2022] Open
Abstract
Background Sperm have but one purpose, to fertilize an egg. In various species including
Drosophila melanogaster female sperm storage is a
necessary step in the reproductive process. Amo is a homolog of the human
transient receptor potential channel TRPP2 (also known as PKD2), which is
mutated in autosomal dominant polycystic kidney disease. In flies Amo is
required for sperm storage. Drosophila males with Amo
mutations produce motile sperm that are transferred to the uterus but they
do not reach the female storage organs. Therefore Amo appears to be a
mediator of directed sperm motility in the female reproductive tract but the
underlying mechanism is unknown. Methodology/Principal Findings Amo exhibits a unique expression pattern during spermatogenesis. In
spermatocytes, Amo is restricted to the endoplasmic reticulum (ER) whereas
in mature sperm, Amo clusters at the distal tip of the sperm tail. Here we
show that flagellar localization of Amo is required for sperm storage. This
raised the question of how Amo at the rear end of sperm regulates forward
movement into the storage organs. In order to address this question, we used
in vivo imaging of dual labelled sperm to demonstrate
that Drosophila sperm navigate backwards in the female
reproductive tract. In addition, we show that sperm exhibit hyperactivation
upon transfer to the uterus. Amo mutant sperm remain
capable of reverse motility but fail to display hyperactivation and directed
movement, suggesting that these functions are required for sperm storage in
flies. Conclusions/Significance Amo is part of a signalling complex at the leading edge of the sperm tail
that modulates flagellar beating and that guides a backwards path into the
storage organs. Our data support an evolutionarily conserved role for TRPP2
channels in cilia.
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Sweeney WE, Avner ED. Diagnosis and management of childhood polycystic kidney disease. Pediatr Nephrol 2011; 26:675-92. [PMID: 21046169 DOI: 10.1007/s00467-010-1656-1] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 08/17/2010] [Accepted: 08/27/2010] [Indexed: 01/31/2023]
Abstract
A number of syndromic disorders have renal cysts as a component of their phenotypes. These disorders can generally be distinguished from autosomal dominant polycystic kidney disease (ADPKD) and autosomal recessive polycystic kidney disease (ARPKD) by imaging studies of their characteristic, predominantly non-renal associated abnormalities. Therefore, a major distinction in the differential diagnosis of enlarge echogenic kidneys is delineating ARPKD from ADPKD. ADPKD and ARPKD can be diagnosed by imaging the kidney with ultrasound, computed tomography, or magnetic resonance imaging (MRI), although ultrasound is still the method of choice for diagnosis in utero and in young children due to ease of use, cost, and safety. Differences in ultrasound characteristics, the presence or absence of associated extrarenal abnormalities, and the screening of the parents >40 years of age usually allow the clinician to make an accurate diagnosis. Early diagnosis of ADPKD and ARPKD affords the opportunity for maximal anticipatory care (i.e. blood pressure control) and in the not-too-distant future, the opportunity to benefit from new therapies currently being developed. If results are equivocal, genetic testing is available for both ARPKD and ADPKD. Specialized centers are now offering preimplantation genetic diagnosis and in vitro fertilization for parents who have previously had a child with ARPKD. For ADPKD patients, a number of therapeutic interventions are currently in clinical trial and may soon be available.
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Affiliation(s)
- William E Sweeney
- Department of Pediatrics, Children's Hospital Health System of Wisconsin, Milwaukee, WI, USA
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Mechanoreception in motile flagella of Chlamydomonas. Nat Cell Biol 2011; 13:630-2. [PMID: 21478860 DOI: 10.1038/ncb2214] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Accepted: 01/20/2011] [Indexed: 01/23/2023]
Abstract
Ciliates and flagellates temporarily swim backwards on collision by generating a mechanoreceptor potential. Although this potential has been shown to be associated with cilia in Paramecium, the molecular entity of the mechanoreceptor has remained unknown. Here we show that Chlamydomonas cells express TRP11, a member of the TRP (transient receptor potential) subfamily V, in the proximal region of the flagella, and that suppression of TRP11 expression results in loss of the avoiding reaction. The results indicate that Chlamydomonas flagella exhibit mechanosensitivity, despite constant motility, by localizing the mechanoreceptor in the proximal region, where active bending is restricted.
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Lee K, Battini L, Gusella GL. Cilium, centrosome and cell cycle regulation in polycystic kidney disease. Biochim Biophys Acta Mol Basis Dis 2011; 1812:1263-71. [PMID: 21376807 DOI: 10.1016/j.bbadis.2011.02.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 01/10/2011] [Accepted: 02/16/2011] [Indexed: 12/19/2022]
Abstract
Polycystic kidney disease is the defining condition of a group of common life-threatening genetic disorders characterized by the bilateral formation and progressive expansion of renal cysts that lead to end stage kidney disease. Although a large body of information has been acquired in the past years about the cellular functions that characterize the cystic cells, the mechanisms triggering the cystogenic conversion are just starting to emerge. Recent findings link defects in ciliary functions, planar cell polarity pathway, and centrosome integrity in early cystic development. Many of the signals dysregulated during cystogenesis may converge on the centrosome for its central function as a structural support for cilia formation and a coordinator of protein trafficking, polarity, and cell division. Here, we will discuss the contribution of proliferation, cilium and planar cell polarity to the cystic signal and will analyze in particular the possible role that the basal bodies/centrosome may play in the cystogenetic mechanisms. This article is part of a Special Issue entitled: Polycystic Kidney Disease.
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Affiliation(s)
- Kyung Lee
- Department of Medicine, The Mount Sinai School of Medicine, New York, NY, USA
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31
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Fluid transport and cystogenesis in autosomal dominant polycystic kidney disease. Biochim Biophys Acta Mol Basis Dis 2011; 1812:1314-21. [PMID: 21255645 DOI: 10.1016/j.bbadis.2011.01.011] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2010] [Revised: 01/09/2011] [Accepted: 01/11/2011] [Indexed: 12/18/2022]
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) is the most frequent inherited nephropathy. The development and enlargement of cysts in ADPKD requires tubular cell proliferation, abnormalities in the extracellular matrix and transepithelial fluid secretion. Multiple studies have suggested that fluid secretion across ADPKD cyst-lining cells is driven by the transepithelial secretion of chloride, mediated by the apical CFTR channel and specific basolateral transporters. The whole secretory process is stimulated by increased levels of cAMP in the cells, probably reflecting modifications in the intracellular calcium homeostasis and abnormal stimulation of the vasopressin V2 receptor. This review will focus on the pathophysiology of fluid secretion in ADPKD cysts, starting with classic, morphological and physiological studies that were followed by investigations of the molecular mechanisms involved and therapeutic trials targeting these pathways in cellular and animal models and ADPKD patients. This article is part of a Special Issue entitled: Polycystic Kidney Disease.
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Abstract
Autosomal-dominant polycystic kidney disease (ADPKD) is the most common Mendelian disorder of the kidney and accounts for approximately 5% of end-stage renal disease in developed countries. It is characterized by focal and sporadic development of renal cysts that increase in number and size with age. Mutations of 2 genes (ie, PKD1 and PKD2) account for most of the cases. Although the clinical manifestations of both gene types overlap completely, PKD1 is associated with more severe disease than PKD2, with bigger kidneys and earlier onset of end-stage renal disease. In general, the diagnosis of ADPKD is commonly made by renal ultrasonography. Age-dependent ultrasound criteria have been established for both diagnosis and disease exclusion in subjects at risk of PKD1. However, the utility of these criteria in the clinic setting is unclear because their performance characteristics have not been defined for the milder PKD2 and the gene type for most test subjects is unknown. Recently, highly predictive ultrasound diagnostic criteria have been derived for at-risk subjects of unknown gene type. In addition, molecular genetic testing is now available for the diagnosis of ADPKD, especially in subjects with equivocal imaging results, with a negative or indeterminate family history, or in younger at-risk individuals with a negative ultrasound study being evaluated as potential living-related kidney donor. Here, we review the clinical utilities and limitations of these imaging- and molecular-based diagnostic tests, and outline our approach for the evaluation of individuals suspected to have ADPKD.
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Affiliation(s)
- Moumita Barua
- Division of Nephrology, University Health Network and University of Toronto, Toronto, Ontario, Canada
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Abstract
The founding member of the TRPP family, TRPP2, was identified as one of the disease genes causing autosomal dominant polycystic kidney disease (ADPKD). ADPKD is the most prevalent, potentially lethal, monogenic disorder in humans, with an average incidence of one in 400 to one in 1,000 individuals worldwide. Here we give an overview of TRPP ion channels and Polycystin-1 receptor proteins focusing on more recent studies. We include the Polycystin-1 family since these proteins are functionally linked to TRPP channels.
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Lyon-Roberts B, Strait KA, van Peursem E, Kittikulsuth W, Pollock JS, Pollock DM, Kohan DE. Flow regulation of collecting duct endothelin-1 production. Am J Physiol Renal Physiol 2010; 300:F650-6. [PMID: 21177779 DOI: 10.1152/ajprenal.00530.2010] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Collecting duct (CD) endothelin-1 (ET-1) is an important autocrine inhibitor of CD Na(+) reabsorption. Salt loading is thought to increase CD ET-1 production; however, definitive evidence of this, as well as understanding of the mechanisms transducing this effect, is lacking. Tubule fluid flow increases in response to Na(+) loading; hence, we studied flow modulation of CD ET-1 production. Three days of a high-salt diet increased mouse and rat inner medullary CD (IMCD) ET-1 mRNA expression. Acute furosemide infusion increased urinary ET-1 excretion in anesthetized rats. Primary cultures of mouse or rat IMCD detached in response to flow using a closed perfusion chamber, consequently a CD cell line (mpkCCDcl4) was examined. Flow increased ET-1 mRNA at shear stress rates exceeding 1 dyne/cm(2), with the maximal effect seen between 2 and 10 dyne/cm(2). Induction of ET-1 mRNA was first evident after 1 h, and most apparent after 2 h, of flow. Inhibition of calmodulin or dihydropyridine-sensitive Ca(2+) channels did not alter the flow response; however, chelation of intracellular Ca(2+) or removal of extracellular Ca(2+) largely prevented flow-stimulated ET-1 mRNA accumulation. Downregulation of protein kinase C (PKC) using phorbol 12-myristate 13-acetate, or PKC inhibition with calphostin C, markedly reduced flow-stimulated ET-1 mRNA levels. Flow-stimulated ET-1 mRNA accumulation was abolished by inhibition of phospholipase C (PLC). Taken together, these data indicate that flow increases CD ET-1 production and this is dependent on extracellular and intracellular Ca(2+), PKC, and PLC. These studies suggest a novel pathway for coupling alterations in extracellular fluid volume to CD ET-1 production and ultimately control of CD Na(+) reabsorption.
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Affiliation(s)
- Brianna Lyon-Roberts
- Division of Nephrology, University of Utah Health Sciences Center, Salt Lake City, Utah; and Vascular Biology Center, Medical College of Georgia, Augusta, Georgia, USA
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Sammels E, Devogelaere B, Mekahli D, Bultynck G, Missiaen L, Parys JB, De Smedt H. Unraveling the role of polycystin-2/inositol 1,4,5-trisphosphate receptor interaction in Ca signaling. Commun Integr Biol 2010; 3:530-2. [PMID: 21331231 DOI: 10.4161/cib.3.6.12751] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Accepted: 06/18/2010] [Indexed: 01/04/2023] Open
Abstract
Autosomal dominant polycystic kidney disease (ADPKD) arises as a consequence of mutations of the genes PKD1 and PKD2, encoding respectively the integral membrane proteins polycystin-1 and polycystin-2 (TRPP2), resulting in a disturbance in intracellular Ca(2+) signaling. Previously we investigated the interaction between TRPP2 and the inositol 1,4,5-trisphosphate (IP(3)) receptor (IP(3)R), an intracellular Ca(2+) channel in the endoplasmic reticulum (ER). We identified the molecular determinants of this interaction and observed an enhanced IP(3)-induced Ca(2+) release (IICR). Since we found that TRPP2 strongly bound to a cluster of positively charged amino acids in the N-terminal ligand-binding domain (LBD) of the IP(3)R, we now investigated whether TRPP2 would interfere with the binding of IP(3) to the IP(3)R. In in vitro experiments we observed that TRPP2 partially inhibited the binding of IP(3) to the LBD of the IP(3)R with an IC(50) of ∼350 nM. The suppressor domain, i.e., the N-terminal 225 amino acids of the LBD of the IP(3)R, mediated this inhibitory effect of TRPP2 on IP(3) binding. The observation that the interaction between the IP(3)R and TRPP2 decreased IP(3) binding is in apparent contrast to the increased IICR. The data can be explained however by a subsequent activation of Ca(2+)-induced Ca(2+) release (CICR) via TRPP2. Implications of this mechanism for cellular Ca(2+) signaling are discussed in this addendum.
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Affiliation(s)
- Eva Sammels
- Laboratory of Molecular and Cellular Signaling; Department of Molecular Cell Biology; K.U. Leuven, Leuven Belgium
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Woodward OM, Li Y, Yu S, Greenwell P, Wodarczyk C, Boletta A, Guggino WB, Qian F. Identification of a polycystin-1 cleavage product, P100, that regulates store operated Ca entry through interactions with STIM1. PLoS One 2010; 5:e12305. [PMID: 20808796 PMCID: PMC2925899 DOI: 10.1371/journal.pone.0012305] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Accepted: 07/27/2010] [Indexed: 11/19/2022] Open
Abstract
Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a genetic disorder resulting in large kidney cysts and eventual kidney failure. Mutations in either the PKD1 or PKD2/TRPP2 genes and their respective protein products, polycystin-1 (PC1) and polycystin-2 (PC2) result in ADPKD. PC2 is known to function as a non-selective cation channel, but PC1's function and the function of PC1 cleavage products are not well understood. Here we identify an endogenous PC1 cleavage product, P100, a 100 kDa fragment found in both wild type and epitope tagged PKD1 knock-in mice. Expression of full length human PC1 (FL PC1) and the resulting P100 and C-Terminal Fragment (CTF) cleavage products in both MDCK and CHO cells significantly reduces the store operated Ca(2+) entry (SOCE) resulting from thapsigargin induced store depletion. Exploration into the roles of P100 and CTF in SOCE inhibition reveal that P100, when expressed in Xenopus laevis oocytes, directly inhibits the SOCE currents but CTF does not, nor does P100 when containing the disease causing R4227X mutation. Interestingly, we also found that in PC1 expressing MDCK cells, translocation of the ER Ca(2+) sensor protein STIM1 to the cell periphery was significantly altered. In addition, P100 Co-immunoprecipitates with STIM1 but CTF does not. The expression of P100 in CHO cells recapitulates the STIM1 translocation inhibition seen with FL PC1. These data describe a novel polycystin-1 cleavage product, P100, which functions to reduce SOCE via direct inhibition of STIM1 translocation; a function with consequences for ADPKD.
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Affiliation(s)
- Owen M. Woodward
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Yun Li
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Shengqiang Yu
- Department of Medicine, Division of Nephrology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
| | - Patrick Greenwell
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Claas Wodarczyk
- Division of Genetics and Cell Biology, Dulbecco Telethon Institute, San Raffaele Scientific Institute, Milan, Italy
| | - Alessandra Boletta
- Division of Genetics and Cell Biology, Dulbecco Telethon Institute, San Raffaele Scientific Institute, Milan, Italy
| | - William B. Guggino
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail: (WBG); (FQ)
| | - Feng Qian
- Department of Medicine, Division of Nephrology, Johns Hopkins School of Medicine, Baltimore, Maryland, United States of America
- * E-mail: (WBG); (FQ)
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Identification of the structural motif responsible for trimeric assembly of the C-terminal regulatory domains of polycystin channels PKD2L1 and PKD2. Biochem J 2010; 429:171-83. [PMID: 20408813 DOI: 10.1042/bj20091843] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Polycystin 2-type cation channels PKD2 and PKD2L1 interact with polycystin 1-type proteins PKD1 and PKD1L3 respectively, to form receptor-cation-channel complexes. The PKD2L1-PKD1L3 complex perceives sour taste, whereas disruption of the PKD2-PKD1 complex, responsible for mechanosensation, leads to development of ADPKD (autosomal-dominant polycystic kidney disease). Besides modulating channel activity and related signalling events, the CRDs (C-terminal regulatory domains) of PKD2 and PKD2L1 play a central role in channel oligomerization. The present study investigates the aggregation state of purified full-length PKD2L1-CRD as well as truncations of CRDs from PKD2 channels. Far- and near-UV CD spectroscopy show that the full-length PKD2L1 CRD (PKD2L1-198) and the truncated PKD2 CRD (PKD2-244) are alpha-helical with no beta-sheet, the alpha-helix content agrees with sequence-based predictions, and some of its aromatic residues are in an asymmetric environment created at least by partially structured regions. Additionally, the CRD truncations exhibit an expected biochemical function by binding Ca2+ in a physiologically relevant range with Kd values of 2.8 muM for PKD2-244 and 0.51 muM for PKD2L1-198. Complimentary biophysical and biochemical techniques establish that truncations of the PKD2 and PKD2L1 CRDs are elongated molecules that assemble as trimers, and the trimeric aggregation state is independent of Ca2+ binding. Finally, we show that a common coiled-coil motif is sufficient and necessary to drive oligomerization of the PKD2 and PKD2L1 CRD truncations under study. Despite the moderate sequence identity (39%) between CRDs of PKD2 and PKD2L1, they both form trimers, implying that trimeric organization of CRDs may be true of all polycystin channels.
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Perico N, Antiga L, Caroli A, Ruggenenti P, Fasolini G, Cafaro M, Ondei P, Rubis N, Diadei O, Gherardi G, Prandini S, Panozo A, Bravo RF, Carminati S, De Leon FR, Gaspari F, Cortinovis M, Motterlini N, Ene-Iordache B, Remuzzi A, Remuzzi G. Sirolimus therapy to halt the progression of ADPKD. J Am Soc Nephrol 2010; 21:1031-40. [PMID: 20466742 DOI: 10.1681/asn.2009121302] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Activation of mammalian target of rapamycin (mTOR) pathways may contribute to uncontrolled cell proliferation and secondary cyst growth in patients with autosomal dominant polycystic kidney disease (ADPKD). To assess the effects of mTOR inhibition on disease progression, we performed a randomized, crossover study (The SIRENA Study) comparing a 6-month treatment with sirolimus or conventional therapy alone on the growth of kidney volume and its compartments in 21 patients with ADPKD and GFR>or=40 ml/min per 1.73 m2. In 10 of the 15 patients who completed the study, aphthous stomatitis complicated sirolimus treatment but was effectively controlled by topical therapy. Compared with pretreatment, posttreatment mean total kidney volume increased less on sirolimus (46+/-81 ml; P=0.047) than on conventional therapy (70+/-72 ml; P=0.002), but we did not detect a difference between the two treatments (P=0.45). Cyst volume was stable on sirolimus and increased by 55+/-75 ml (P=0.013) on conventional therapy, whereas parenchymal volume increased by 26+/-30 ml (P=0.005) on sirolimus and was stable on conventional therapy. Percentage changes in cyst and parenchyma volumes were significantly different between the two treatment periods. Sirolimus had no appreciable effects on intermediate volume and GFR. Albuminuria and proteinuria marginally but significantly increased during sirolimus treatment. In summary, sirolimus halted cyst growth and increased parenchymal volume in patients with ADPKD. Whether these effects translate into improved long-term outcomes requires further investigation.
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Affiliation(s)
- Norberto Perico
- Clinical Research Center for Rare Diseases, Aldo e Cele Daccò, Mario Negri Institute for Pharmacological Research, Bergamo, Italy
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Sammels E, Devogelaere B, Mekahli D, Bultynck G, Missiaen L, Parys JB, Cai Y, Somlo S, De Smedt H. Polycystin-2 activation by inositol 1,4,5-trisphosphate-induced Ca2+ release requires its direct association with the inositol 1,4,5-trisphosphate receptor in a signaling microdomain. J Biol Chem 2010; 285:18794-805. [PMID: 20375013 DOI: 10.1074/jbc.m109.090662] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Autosomal dominant polycystic kidney disease is characterized by the loss-of-function of a signaling complex involving polycystin-1 and polycystin-2 (TRPP2, an ion channel of the TRP superfamily), resulting in a disturbance in intracellular Ca(2+) signaling. Here, we identified the molecular determinants of the interaction between TRPP2 and the inositol 1,4,5-trisphosphate receptor (IP(3)R), an intracellular Ca(2+) channel in the endoplasmic reticulum. Glutathione S-transferase pulldown experiments combined with mutational analysis led to the identification of an acidic cluster in the C-terminal cytoplasmic tail of TRPP2 and a cluster of positively charged residues in the N-terminal ligand-binding domain of the IP(3)R as directly responsible for the interaction. To investigate the functional relevance of TRPP2 in the endoplasmic reticulum, we re-introduced the protein in TRPP2(-/-) mouse renal epithelial cells using an adenoviral expression system. The presence of TRPP2 resulted in an increased agonist-induced intracellular Ca(2+) release in intact cells and IP(3)-induced Ca(2+) release in permeabilized cells. Using pathological mutants of TRPP2, R740X and D509V, and competing peptides, we demonstrated that TRPP2 amplified the Ca(2+) signal by a local Ca(2+)-induced Ca(2+)-release mechanism, which only occurred in the presence of the TRPP2-IP(3)R interaction, and not via altered IP(3)R channel activity. Moreover, our results indicate that this interaction was instrumental in the formation of Ca(2+) microdomains necessary for initiating Ca(2+)-induced Ca(2+) release. The data strongly suggest that defects in this mechanism may account for the altered Ca(2+) signaling associated with pathological TRPP2 mutations and therefore contribute to the development of autosomal dominant polycystic kidney disease.
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Affiliation(s)
- Eva Sammels
- Department of Molecular Cell Biology, Laboratory of Molecular and Cellular Signaling, KU Leuven, Campus Gasthuisberg O&N1, Herestraat 49 bus 802, B-3000 Leuven, Belgium
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Transient receptor potential channelopathies. Pflugers Arch 2010; 460:437-50. [PMID: 20127491 DOI: 10.1007/s00424-010-0788-2] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Accepted: 01/12/2010] [Indexed: 12/31/2022]
Abstract
In the past years, several hereditary diseases caused by defects in transient receptor potential channels (TRP) genes have been described. This review summarizes our current knowledge about TRP channelopathies and their possible pathomechanisms. Based on available genetic indications, we will also describe several putative pathological conditions in which (mal)function of TRP channels could be anticipated.
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41
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Yu Y, Ulbrich MH, Li MH, Buraei Z, Chen XZ, Ong ACM, Tong L, Isacoff EY, Yang J. Structural and molecular basis of the assembly of the TRPP2/PKD1 complex. Proc Natl Acad Sci U S A 2009; 106:11558-63. [PMID: 19556541 PMCID: PMC2710685 DOI: 10.1073/pnas.0903684106] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Indexed: 01/20/2023] Open
Abstract
Mutations in PKD1 and TRPP2 account for nearly all cases of autosomal dominant polycystic kidney disease (ADPKD). These 2 proteins form a receptor/ion channel complex on the cell surface. Using a combination of biochemistry, crystallography, and a single-molecule method to determine the subunit composition of proteins in the plasma membrane of live cells, we find that this complex contains 3 TRPP2 and 1 PKD1. A newly identified coiled-coil domain in the C terminus of TRPP2 is critical for the formation of this complex. This coiled-coil domain forms a homotrimer, in both solution and crystal structure, and binds to a single coiled-coil domain in the C terminus of PKD1. Mutations that disrupt the TRPP2 coiled-coil domain trimer abolish the assembly of both the full-length TRPP2 trimer and the TRPP2/PKD1 complex and diminish the surface expression of both proteins. These results have significant implications for the assembly, regulation, and function of the TRPP2/PKD1 complex and the pathogenic mechanism of some ADPKD-producing mutations.
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Affiliation(s)
- Yong Yu
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - Maximilian H. Ulbrich
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Ming-Hui Li
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - Zafir Buraei
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - Xing-Zhen Chen
- Membrane Protein Research Group, Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada T6G 2H7; and
| | - Albert C. M. Ong
- Kidney Genetics Group, Academic Unit of Nephrology, Sheffield Kidney Institute, University of Sheffield Medical School, Sheffield S10 2RX, United Kingdom
| | - Liang Tong
- Department of Biological Sciences, Columbia University, New York, NY 10027
| | - Ehud Y. Isacoff
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- Material Science and Physical Bioscience Divisions, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
| | - Jian Yang
- Department of Biological Sciences, Columbia University, New York, NY 10027
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42
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Torres VE. Type II Calcimimetics and Polycystic Kidney Disease: Unanswered Questions. J Am Soc Nephrol 2009; 20:1421-5. [DOI: 10.1681/asn.2009050501] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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43
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Abstract
Autosomal dominant polycystic kidney disease is the most prevalent, potentially lethal monogenic disorder. It has large inter- and intra-familial variability explained to a large extent by its genetic heterogeneity and modifier genes. An increased understanding of its underlying genetic, molecular, and cellular mechanisms and a better appreciation of its progression and systemic manifestations have laid out the foundation for the development of clinical trials and potentially effective therapies. The purpose of this review is to update the core of knowledge in this area with recent publications that have appeared during 2006-2009.
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Affiliation(s)
- Vicente E Torres
- Division of Nephrology and Hypertension, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.
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44
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Tsiokas L. Function and regulation of TRPP2 at the plasma membrane. Am J Physiol Renal Physiol 2009; 297:F1-9. [PMID: 19244406 DOI: 10.1152/ajprenal.90277.2008] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The vast majority (approximately 99%) of all known cases of autosomal dominant polycystic kidney disease (ADPKD) are caused by naturally occurring mutations in two separate, but genetically interacting, loci, pkd1 and pkd2. pkd1 encodes a large multispanning membrane protein (PKD1) of unknown function, while pkd2 encodes a protein (TRPP2, polycystin-2, or PKD2) of the transient receptor potential (TRP) superfamily of ion channels. Biochemical, functional, and genetic studies support a model in which PKD1 physically interacts with TRPP2 to form an ion channel complex that conveys extracellular stimuli to ionic currents. However, the molecular identity of these extracellular stimuli remains elusive. Functional studies in cell culture show that TRPP2 can be activated in response to mechanical cues (fluid shear stress) and/or receptor tyrosine kinase (RTK) and G protein-coupled receptor (GPCR) activation at the cell surface. Recent genetic studies in Chlamydomonas reinhardtii show that CrPKD2 functions in a pathway linking cell-cell adhesion and Ca(2+) signaling. The mode of activation depends on protein-protein interactions with other channel subunits and auxiliary proteins. Therefore, understanding the mechanisms underlying the molecular makeup of TRPP2-containing complexes is critical in delineating the mechanisms of TRPP2 activation and, most importantly, the mechanisms by which naturally occurring mutations in pkd1 or pkd2 lead not only to ADPKD, but also to other defects reported in model organisms lacking functional TRPP2. This review focuses on the molecular assembly, function, and regulation of TRPP2 as a cell surface cation channel and discusses its potential role in Ca(2+) signaling and ADPKD pathophysiology.
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Affiliation(s)
- Leonidas Tsiokas
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
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45
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TRPP2 channels regulate apoptosis through the Ca2+ concentration in the endoplasmic reticulum. EMBO J 2009; 28:490-9. [PMID: 19153608 DOI: 10.1038/emboj.2008.307] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Accepted: 12/22/2008] [Indexed: 12/12/2022] Open
Abstract
Ca(2+) is an important signalling molecule that regulates multiple cellular processes, including apoptosis. Although Ca(2+) influx through transient receptor potential (TRP) channels in the plasma membrane is known to trigger cell death, the function of intracellular TRP proteins in the regulation of Ca(2+)-dependent signalling pathways and apoptosis has remained elusive. Here, we show that TRPP2, the ion channel mutated in autosomal dominant polycystic kidney disease (ADPKD), protects cells from apoptosis by lowering the Ca(2+) concentration in the endoplasmic reticulum (ER). ER-resident TRPP2 counteracts the activity of the sarcoendoplasmic Ca(2+) ATPase by increasing the ER Ca(2+) permeability. This results in diminished cytosolic and mitochondrial Ca(2+) signals upon stimulation of inositol 1,4,5-trisphosphate receptors and reduces Ca(2+) release from the ER in response to apoptotic stimuli. Conversely, knockdown of TRPP2 in renal epithelial cells increases ER Ca(2+) release and augments sensitivity to apoptosis. Our findings indicate an important function of ER-resident TRPP2 in the modulation of intracellular Ca(2+) signalling, and provide a molecular mechanism for the increased apoptosis rates in ADPKD upon loss of TRPP2 channel function.
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46
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Nielsen SK, Møllgård K, Clement CA, Veland IR, Awan A, Yoder BK, Novak I, Christensen ST. Characterization of primary cilia and Hedgehog signaling during development of the human pancreas and in human pancreatic duct cancer cell lines. Dev Dyn 2008; 237:2039-52. [PMID: 18629868 DOI: 10.1002/dvdy.21610] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Hedgehog (Hh) signaling controls pancreatic development and homeostasis; aberrant Hh signaling is associated with several pancreatic diseases. Here we investigated the link between Hh signaling and primary cilia in the human developing pancreatic ducts and in cultures of human pancreatic duct adenocarcinoma cell lines, PANC-1 and CFPAC-1. We show that the onset of Hh signaling from human embryogenesis to fetal development is associated with accumulation of Hh signaling components Smo and Gli2 in duct primary cilia and a reduction of Gli3 in the duct epithelium. Smo, Ptc, and Gli2 localized to primary cilia of PANC-1 and CFPAC-1 cells, which may maintain high levels of nonstimulated Hh pathway activity. These findings indicate that primary cilia are involved in pancreatic development and postnatal tissue homeostasis.
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Affiliation(s)
- Sonja K Nielsen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
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47
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Abstract
Studies of ion channels have for long been dominated by the animalcentric, if not anthropocentric, view of physiology. The structures and activities of ion channels had, however, evolved long before the appearance of complex multicellular organisms on earth. The diversity of ion channels existing in cellular membranes of prokaryotes is a good example. Although at first it may appear as a paradox that most of what we know about the structure of eukaryotic ion channels is based on the structure of bacterial channels, this should not be surprising given the evolutionary relatedness of all living organisms and suitability of microbial cells for structural studies of biological macromolecules in a laboratory environment. Genome sequences of the human as well as various microbial, plant, and animal organisms unambiguously established the evolutionary links, whereas crystallographic studies of the structures of major types of ion channels published over the last decade clearly demonstrated the advantage of using microbes as experimental organisms. The purpose of this review is not only to provide an account of acquired knowledge on microbial ion channels but also to show that the study of microbes and their ion channels may also hold a key to solving unresolved molecular mysteries in the future.
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Affiliation(s)
- Boris Martinac
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia.
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48
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Köttgen M, Buchholz B, Garcia-Gonzalez MA, Kotsis F, Fu X, Doerken M, Boehlke C, Steffl D, Tauber R, Wegierski T, Nitschke R, Suzuki M, Kramer-Zucker A, Germino GG, Watnick T, Prenen J, Nilius B, Kuehn EW, Walz G. TRPP2 and TRPV4 form a polymodal sensory channel complex. ACTA ACUST UNITED AC 2008; 182:437-47. [PMID: 18695040 PMCID: PMC2500130 DOI: 10.1083/jcb.200805124] [Citation(s) in RCA: 308] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The primary cilium has evolved as a multifunctional cellular compartment that decorates most vertebrate cells. Cilia sense mechanical stimuli in various organs, but the molecular mechanisms that convert the deflection of cilia into intracellular calcium transients have remained elusive. Polycystin-2 (TRPP2), an ion channel mutated in polycystic kidney disease, is required for cilia-mediated calcium transients but lacks mechanosensitive properties. We find here that TRPP2 utilizes TRPV4 to form a mechano- and thermosensitive molecular sensor in the cilium. Depletion of TRPV4 in renal epithelial cells abolishes flow-induced calcium transients, demonstrating that TRPV4, like TRPP2, is an essential component of the ciliary mechanosensor. Because TRPV4-deficient zebrafish and mice lack renal cysts, our findings challenge the concept that defective ciliary flow sensing constitutes the fundamental mechanism of cystogenesis.
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Affiliation(s)
- Michael Köttgen
- Renal Division, University Hospital Freiburg, 79106 Freiburg, Germany
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Fu X, Wang Y, Schetle N, Gao H, Pütz M, von Gersdorff G, Walz G, Kramer-Zucker AG. The subcellular localization of TRPP2 modulates its function. J Am Soc Nephrol 2008; 19:1342-51. [PMID: 18417723 DOI: 10.1681/asn.2007070730] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
TRPP2, also known as polycystin-2, is a calcium permeable nonselective cation channel that is mutated in autosomal dominant polycystic kidney disease but has also been implicated in the regulation of cardiac development, renal tubular differentiation, and left-to-right (L-R) axis determination. For obtaining further insight into how TRPP2 exerts tissue-specific functions, this study took advantage of PACS-dependent trafficking of TRPP2 in zebrafish larvae. PACS proteins recognize an acidic cluster within the carboxy-terminal domain of TRPP2 that undergoes phosphorylation and mediate retrieval of TRPP2 to the Golgi and endoplasmic reticulum (ER). The interaction of human TRPP2 with PACS proteins can be inhibited by a Ser812Ala mutation (TRPP2(S812A)), thereby allowing TRPP2 to reach other subcellular compartments, and enhanced by a Ser812Asp mutation (TRPP2(S812D)), thereby trapping TRPP2 in the ER. It was found that the TRPP2(S812A) mutant rescued cyst formation of TRPP2-deficient zebrafish larvae to the same degree as wild-type TRPP2, whereas the TRPP2(S812D) mutant was significantly more effective in normalizing the distorted body axis of TRPP2-deficient fish. Surprisingly, the TRPP2(S812D) mutant rescued the abnormalities of L-R asymmetry more effectively than either wild-type or TRPP2(S812A), suggesting that the ER localization of TRPP2 plays an important role in the development of normal L-R asymmetry. Taken together, these findings support the hypothesis that TRPP2 assumes distinct subcellular localizations to exert tissue-specific functions.
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Affiliation(s)
- Xiao Fu
- Renal Division, University Hospital Freiburg, Hugstetter Strasse 55, D-79106 Freiburg, Germany
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50
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Formation of a new receptor-operated channel by heteromeric assembly of TRPP2 and TRPC1 subunits. EMBO Rep 2008; 9:472-9. [PMID: 18323855 DOI: 10.1038/embor.2008.29] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2007] [Revised: 01/29/2008] [Accepted: 01/30/2008] [Indexed: 01/12/2023] Open
Abstract
Although several protein-protein interactions have been reported between transient receptor potential (TRP) channels, they are all known to occur exclusively between members of the same group. The only intergroup interaction described so far is that of TRPP2 and TRPC1; however, the significance of this interaction is unknown. Here, we show that TRPP2 and TRPC1 assemble to form a channel with a unique constellation of new and TRPP2/TRPC1-specific properties. TRPP2/TRPC1 is activated in response to G-protein-coupled receptor activation and shows a pattern of single-channel conductance, amiloride sensitivity and ion permeability distinct from that of TRPP2 or TRPC1 alone. Native TRPP2/TRPC1 activity is shown in kidney cells by complementary gain-of-function and loss-of-function experiments, and its existence under physiological conditions is supported by colocalization at the primary cilium and by co-immunoprecipitation from kidney membranes. Identification of the heteromultimeric TRPP2/TRPC1 channel has implications in mechanosensation and cilium-based Ca(2+) signalling.
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