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Münch J, Goodyer PR, Wagner CA. Tubular Diseases and Stones Seen From Pediatric and Adult Nephrology Perspectives. Semin Nephrol 2023; 43:151437. [PMID: 37968178 DOI: 10.1016/j.semnephrol.2023.151437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2023]
Abstract
The tubular system of the kidneys is a complex series of morphologic and functional units orchestrating the content of tubular fluid as it flows along the nephron and collecting ducts. Renal tubules maintain body water, regulate electrolytes and acid-base balance, reabsorb precious organic solutes, and eliminate specific metabolites, toxins, and drugs. In addition, decisive mechanisms to adjust blood pressure are governed by the renal tubules. Genetic as well as acquired disorders of these tubular functions may cause serious diseases that manifest both in childhood and adulthood. This article addresses a selection of tubulopathies and the underlying pathomechanisms, while highlighting the important differences in pediatric and adult nephrology care. These range from rare monogenic conditions such as nephrogenic diabetes insipidus, cystinosis, and Bartter syndrome that present in childhood, to the genetic and acquired tubular pathologies causing hypertension or nephrolithiasis that are more prevalent in adults. Both pediatric and adult nephrologists must be aware of these conditions and the age-dependent manifestations that warrant close interaction between the two subspecialties.
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Affiliation(s)
- Johannes Münch
- Institute of Physiology, University of Zurich, Zurich, Switzerland; Institute of Human Genetics, University of Zurich, Zurich, Switzerland; National Center of Competence in Research, NCCR Kidney.CH, Switzerland
| | - Paul R Goodyer
- McGill University Health Centre, Montreal, Quebec, Canada
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland; National Center of Competence in Research, NCCR Kidney.CH, Switzerland.
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2
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Levin-Konigsberg R, Mitra K, Nigam A, Spees K, Hivare P, Liu K, Kundaje A, Krishnan Y, Bassik MC. SLC12A9 is a lysosome-detoxifying ammonium - chloride co-transporter. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.22.541801. [PMID: 37292735 PMCID: PMC10245881 DOI: 10.1101/2023.05.22.541801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Ammonia is a ubiquitous, toxic by-product of cell metabolism. Its high membrane permeability and proton affinity causes ammonia to accumulate inside acidic lysosomes in its poorly membrane-permeant form: ammonium (NH 4 + ). Ammonium buildup compromises lysosomal function, suggesting the existence of mechanisms that protect cells from ammonium toxicity. Here, we identified SLC12A9 as a lysosomal ammonium exporter that preserves lysosomal homeostasis. SLC12A9 knockout cells showed grossly enlarged lysosomes and elevated ammonium content. These phenotypes were reversed upon removal of the metabolic source of ammonium or dissipation of the lysosomal pH gradient. Lysosomal chloride increased in SLC12A9 knockout cells and chloride binding by SLC12A9 was required for ammonium transport. Our data indicate that SLC12A9 is a chloride-driven ammonium co-transporter that is central in an unappreciated, fundamental mechanism of lysosomal physiology that may have special relevance in tissues with elevated ammonia, such as tumors.
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3
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Mattison KA, Tossing G, Mulroe F, Simmons C, Butler KM, Schreiber A, Alsadah A, Neilson DE, Naess K, Wedell A, Wredenberg A, Sorlin A, McCann E, Burghel GJ, Menendez B, Hoganson GE, Botto LD, Filloux FM, Aledo-Serrano Á, Gil-Nagel A, Tatton-Brown K, Verbeek NE, van der Zwaag B, Aleck KA, Fazenbaker AC, Balciuniene J, Dubbs HA, Marsh ED, Garber K, Ek J, Duno M, Hoei-Hansen CE, Deardorff MA, Raca G, Quindipan C, van Hirtum-Das M, Breckpot J, Hammer TB, Møller RS, Whitney A, Douglas AGL, Kharbanda M, Brunetti-Pierri N, Morleo M, Nigro V, May HJ, Tao JX, Argilli E, Sherr EH, Dobyns WB, Baines RA, Warwicker J, Parker JA, Banka S, Campeau PM, Escayg A. ATP6V0C variants impair V-ATPase function causing a neurodevelopmental disorder often associated with epilepsy. Brain 2023; 146:1357-1372. [PMID: 36074901 PMCID: PMC10319782 DOI: 10.1093/brain/awac330] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 07/29/2022] [Accepted: 08/14/2022] [Indexed: 11/14/2022] Open
Abstract
The vacuolar H+-ATPase is an enzymatic complex that functions in an ATP-dependent manner to pump protons across membranes and acidify organelles, thereby creating the proton/pH gradient required for membrane trafficking by several different types of transporters. We describe heterozygous point variants in ATP6V0C, encoding the c-subunit in the membrane bound integral domain of the vacuolar H+-ATPase, in 27 patients with neurodevelopmental abnormalities with or without epilepsy. Corpus callosum hypoplasia and cardiac abnormalities were also present in some patients. In silico modelling suggested that the patient variants interfere with the interactions between the ATP6V0C and ATP6V0A subunits during ATP hydrolysis. Consistent with decreased vacuolar H+-ATPase activity, functional analyses conducted in Saccharomyces cerevisiae revealed reduced LysoSensor fluorescence and reduced growth in media containing varying concentrations of CaCl2. Knockdown of ATP6V0C in Drosophila resulted in increased duration of seizure-like behaviour, and the expression of selected patient variants in Caenorhabditis elegans led to reduced growth, motor dysfunction and reduced lifespan. In summary, this study establishes ATP6V0C as an important disease gene, describes the clinical features of the associated neurodevelopmental disorder and provides insight into disease mechanisms.
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Affiliation(s)
- Kari A Mattison
- Genetics and Molecular Biology Graduate Program, Graduate Division of Biological and Biomedical Sciences, Laney Graduate School, Emory University, Atlanta, GA, USA
- Department of Human Genetics, Emory University, Atlanta, GA, USA
| | - Gilles Tossing
- Department of Neuroscience, University of Montreal, Montreal, QC, Canada
| | - Fred Mulroe
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Center, Manchester, UK
| | - Callum Simmons
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Center, Manchester, UK
| | - Kameryn M Butler
- Department of Human Genetics, Emory University, Atlanta, GA, USA
- Greenwood Genetics Center, Greenwood, SC, USA
| | - Alison Schreiber
- Center for Personalized Genetic Healthcare, Cleveland Clinic, Cleveland, OH, USA
| | - Adnan Alsadah
- Center for Personalized Genetic Healthcare, Cleveland Clinic, Cleveland, OH, USA
| | - Derek E Neilson
- Division of Genetics and Metabolism, Department of Child Health, The University of Arizona College of Medicine, Phoenix, AZ, USA
- Department of Genetics and Metabolism, Phoenix Children’s Hospital, Phoenix Children’s Medical Group, Phoenix, AZ, USA
| | - Karin Naess
- Center for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Anna Wedell
- Center for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden
- Deparment of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden
| | - Anna Wredenberg
- Center for Inherited Metabolic Diseases, Karolinska University Hospital, Stockholm, Sweden
- Department of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm, Sweden
| | - Arthur Sorlin
- National Center of Genetics, Laboratoire National de Santé, Dudelange, Luxembourg
| | - Emma McCann
- Liverpool Center for Genomic Medicine, Liverpool Women’s Hospital, Liverpool, UK
| | - George J Burghel
- Genomic Diagnostic Laboratory, St. Mary’s Hospital, Manchester University NHS Foundation Trust, Manchester, UK
| | | | - George E Hoganson
- Division of Genetics, Department of Pediatrics, University of Illinois College of Medicine, Chicago, IL, USA
| | - Lorenzo D Botto
- Division of Medical Genetics, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Francis M Filloux
- Division of Pediatric Neurology, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Ángel Aledo-Serrano
- Genetic Epilepsy Program, Department of Neurology, Ruber International Hospital, Madrid, Spain
| | - Antonio Gil-Nagel
- Genetic Epilepsy Program, Department of Neurology, Ruber International Hospital, Madrid, Spain
| | - Katrina Tatton-Brown
- Medical Genetics, St. George’s University Hospitals NHS Foundation Trust and Institute for Molecular and Cell Sciences, St. George’s, University of London, London, UK
| | - Nienke E Verbeek
- Department of Genetics, University Medical Center Utrecht, Member of the ERN EpiCARE, Utrecht, The Netherlands
| | - Bert van der Zwaag
- Department of Genetics, University Medical Center Utrecht, Member of the ERN EpiCARE, Utrecht, The Netherlands
| | - Kyrieckos A Aleck
- Division of Genetics and Metabolism, Department of Child Health, The University of Arizona College of Medicine, Phoenix, AZ, USA
- Department of Genetics and Metabolism, Phoenix Children’s Hospital, Phoenix Children’s Medical Group, Phoenix, AZ, USA
| | - Andrew C Fazenbaker
- Department of Genetics and Metabolism, Phoenix Children’s Hospital, Phoenix Children’s Medical Group, Phoenix, AZ, USA
| | - Jorune Balciuniene
- Divison of Genomic Diagnostics, Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, Philadelphia, PA, USA
- PerkinElmer Genomics, Pittsburgh, PA, USA
| | - Holly A Dubbs
- Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Eric D Marsh
- Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Kathryn Garber
- Department of Human Genetics, Emory University, Atlanta, GA, USA
| | - Jakob Ek
- Department of Clinical Genetics, University Hospital of Copenhagen, Copenhagen, Denmark
| | - Morten Duno
- Department of Clinical Genetics, University Hospital of Copenhagen, Copenhagen, Denmark
| | - Christina E Hoei-Hansen
- Department of Pediatrics, University Hospital of Copenhagen, Copenhagen, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Matthew A Deardorff
- Department of Pathology and Laboratory Medicine, Children’s Hospital Los Angeles, Los Angeles, CA, USA
- Department of Pediatrics, Division of Medical Genetics, Children’s Hospital Los Angeles, Los Angeles, CA, USA
- Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Gordana Raca
- Department of Pathology and Laboratory Medicine, Children’s Hospital Los Angeles, Los Angeles, CA, USA
- Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Catherine Quindipan
- Center for Personalized Medicine, Children’s Hospital Los Angeles, Los Angeles, CA, USA
| | - Michele van Hirtum-Das
- Department of Pediatrics, Division of Medical Genetics, Children’s Hospital Los Angeles, Los Angeles, CA, USA
- Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Jeroen Breckpot
- Center for Human Genetics, University Hospitals Leuven, Leuven, Belgium
| | - Trine Bjørg Hammer
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Fildelfia, Dianalund, Denmark
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Medicine, Danish Epilepsy Center, Fildelfia, Dianalund, Denmark
- Insititue for Regional Health Services Research, University of Southern Denmark, Odense, Denmark
| | - Andrea Whitney
- Pediatric Neurology, University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - Andrew G L Douglas
- Wessex Clinical Genetics Service, University of Southampton, Southampton, UK
- Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Mira Kharbanda
- Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Nicola Brunetti-Pierri
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
- Department of Translational Medicine, Federico II University of Naples, Naples, Italy
| | - Manuela Morleo
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
- Department of Precision Medicine, University of Campania ‘Luigi Vanvitelli’, Naples, Italy
| | - Vincenzo Nigro
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
- Department of Precision Medicine, University of Campania ‘Luigi Vanvitelli’, Naples, Italy
| | - Halie J May
- Institute for Genomic Medicine, Columbia University Irving Medical Center, New York, NY, USA
| | - James X Tao
- Department of Neurology, University of Chicago, Chicago, IL, USA
| | - Emanuela Argilli
- Department of Neurology, University of California, San Francisco, San Francisco, CA, USA
- Pediatrics Institute of Human Genetics and Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
| | - Elliot H Sherr
- Department of Neurology, University of California, San Francisco, San Francisco, CA, USA
- Pediatrics Institute of Human Genetics and Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, USA
| | - William B Dobyns
- Department of Pediatrics, Division of Genetics and Metabolism, University of Minnesota, Minneapolis, MN, USA
| | | | - Richard A Baines
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Center, Manchester, UK
| | - Jim Warwicker
- School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Institute of Biotechnology, University of Manchester, Manchester, UK
| | - J Alex Parker
- Department of Neuroscience, University of Montreal, Montreal, QC, Canada
| | - Siddharth Banka
- Division of Evolution, Infection, and Genomics, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | | | - Andrew Escayg
- Department of Human Genetics, Emory University, Atlanta, GA, USA
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Girard M, Bellefeuille SD, Eiselt É, Arguin G, Longpré JM, Sarret P, Gendron FP. Ligand-dependent intracellular trafficking of the G protein-coupled P2Y 6 receptor. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119476. [PMID: 37059189 DOI: 10.1016/j.bbamcr.2023.119476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 03/28/2023] [Accepted: 04/05/2023] [Indexed: 04/16/2023]
Abstract
Endosomal trafficking is intricately linked to G protein-coupled receptors (GPCR) fate and signaling. Extracellular uridine diphosphate (UDP) acts as a signaling molecule by selectively activating the GPCR P2Y6. Despite the recent interest for this receptor in pathologies, such as gastrointestinal and neurological diseases, there is sparse information on the endosomal trafficking of P2Y6 receptors in response to its endogenous agonist UDP and synthetic selective agonist 5-iodo-UDP (MRS2693). Confocal microscopy and cell surface ELISA revealed delayed internalization kinetics in response to MRS2693 vs. UDP stimulation in AD293 and HCT116 cells expressing human P2Y6. Interestingly, UDP induced clathrin-dependent P2Y6 internalization, whereas receptor stimulation by MRS2693 endocytosis appeared to be associated with a caveolin-dependent mechanism. Internalized P2Y6 was associated with Rab4, 5, and 7 positive vesicles independent of the agonist. We have measured a higher frequency of receptor expression co-occurrence with Rab11-vesicles, the trans-Golgi network, and lysosomes in response to MRS2693. Interestingly, a higher agonist concentration reversed the delayed P2Y6 internalization and recycling kinetics in the presence of MRS2693 stimulation without changing its caveolin-dependent internalization. This work showed a ligand-dependent effect affecting the P2Y6 receptor internalization and endosomal trafficking. These findings could guide the development of bias ligands that could influence P2Y6 signaling.
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Affiliation(s)
- Mélissa Girard
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada; Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Canada
| | - Steve Dagenais Bellefeuille
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Émilie Eiselt
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Canada; Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Canada
| | - Guillaume Arguin
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Jean-Michel Longpré
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Canada; Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Canada
| | - Philippe Sarret
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Canada; Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Canada
| | - Fernand-Pierre Gendron
- Department of Immunology and Cell Biology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada; Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Canada.
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5
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Lee D, Son E, Kim YH. Transferrin-mediated increase of labile iron Pool following simulated ischemia causes lipid peroxidation during the early phase of reperfusion. Free Radic Res 2022; 56:713-729. [PMID: 36794395 DOI: 10.1080/10715762.2023.2169683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Heart ischemia/reperfusion (I/R) injury is related to iron content. However, the occurrence and mechanism of changes in labile iron pool (LIP) during I/R is debatable. Moreover, the identity of the iron form dominant in LIP during I/R is unclear. Herein, we measured changes of LIP during simulated ischemia (SI) and reperfusion (SR), in which ischemia was simulated in vitro with lactic acidosis and hypoxia. Total LIP did not change in lactic acidosis, whereas LIP, especially Fe3+, increased in hypoxia. Under SI, accompanied by hypoxia with acidosis, both Fe2+ and Fe3+ were significantly increased. Increased total LIP was maintained at 1 h post-SR. However, the Fe2+ and Fe3+ portion was changed. The increased Fe2+ was decreased, and conversely the Fe3+ was increased. BODIPY oxidized signal increased and through the time-course these changes correlated with blebbing of cell membrane and SR-induced LDH release. These data suggested lipid peroxidation occurred via Fenton's reaction. The experiments using bafilomycin A1 and zinc protoporphyrin suggested no role of ferritinophagy or heme oxidation in the increase of LIP during SI. The extracellular source, transferrin assessed using serum transferrin bound iron (TBI) saturation showed that the depletion of TBI reduced SR-induced cell damages and additive saturation of TBI accelerated SR-induced lipid peroxidation. Furthermore, Apo-Tf dramatically blocked the increase of LIP and SR-induced damages. In conclusion, Tf-mediated iron induces the increase of LIP during SI, and it causes Fenton reaction-mediated lipid peroxidation during the early phase of SR.
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Affiliation(s)
- Dongju Lee
- Department of Pharmacology, University of Ulsan College of Medicine, Seoul, Korea.,Bio-medical Institute of Technology, University of Ulsan, Songpa-gu, Korea.,Department of Medical Science, Asan Medical Institute of Convergence Science and Technology, Asan Medical Center, University of Ulsan, Songpa-gu, Korea
| | - Euncheol Son
- Department of Pharmacology, University of Ulsan College of Medicine, Seoul, Korea.,Bio-medical Institute of Technology, University of Ulsan, Songpa-gu, Korea.,Stem Cell Immunomodulation Research Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Young-Hoon Kim
- Department of Pharmacology, University of Ulsan College of Medicine, Seoul, Korea.,Bio-medical Institute of Technology, University of Ulsan, Songpa-gu, Korea
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6
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Wüstner D. Image segmentation and separation of spectrally similar dyes in fluorescence microscopy by dynamic mode decomposition of photobleaching kinetics. BMC Bioinformatics 2022; 23:334. [PMID: 35962314 PMCID: PMC9373304 DOI: 10.1186/s12859-022-04881-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 08/03/2022] [Indexed: 12/03/2022] Open
Abstract
Background Image segmentation in fluorescence microscopy is often based on spectral separation of fluorescent probes (color-based segmentation) or on significant intensity differences in individual image regions (intensity-based segmentation). These approaches fail, if dye fluorescence shows large spectral overlap with other employed probes or with strong cellular autofluorescence. Results Here, a novel model-free approach is presented which determines bleaching characteristics based on dynamic mode decomposition (DMD) and uses the inferred photobleaching kinetics to distinguish different probes or dye molecules from autofluorescence. DMD is a data-driven computational method for detecting and quantifying dynamic events in complex spatiotemporal data. Here, DMD is first used on synthetic image data and thereafter used to determine photobleaching characteristics of a fluorescent sterol probe, dehydroergosterol (DHE), compared to that of cellular autofluorescence in the nematode Caenorhabditis elegans. It is shown that decomposition of those dynamic modes allows for separating probe from autofluorescence without invoking a particular model for the bleaching process. In a second application, DMD of dye-specific photobleaching is used to separate two green-fluorescent dyes, an NBD-tagged sphingolipid and Alexa488-transferrin, thereby assigning them to different cellular compartments. Conclusions Data-based decomposition of dynamic modes can be employed to analyze spatially varying photobleaching of fluorescent probes in cells and tissues for spatial and temporal image segmentation, discrimination of probe from autofluorescence and image denoising. The new method should find wide application in analysis of dynamic fluorescence imaging data. Supplementary Information The online version contains supplementary material available at 10.1186/s12859-022-04881-x.
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Affiliation(s)
- Daniel Wüstner
- Department of Biochemistry and Molecular Biology and Physics of Life Sciences (PhyLife) Center, University of Southern Denmark, Campusvej 55, DK-5230, Odense, Denmark.
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Jeitner TM, Babich JW, Kelly JM. Advances in PSMA theranostics. Transl Oncol 2022; 22:101450. [PMID: 35597190 PMCID: PMC9123266 DOI: 10.1016/j.tranon.2022.101450] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 05/04/2022] [Accepted: 05/08/2022] [Indexed: 12/15/2022] Open
Abstract
PSMA is an appealing target for theranostic because it is a transmembrane protein with a known substrate that is overexpessed on prostate cancer cells and internalizes upon ligand binding. There are a number of PSMA theranostic ligands in clinical evaluation, clinical trial, or clinically approved. PSMA theranostic ligands increase progression-free survival, overall survival, and pain in patients with metastatic castration resistant prostate cancer. A major obstacle to PSMA-targeted radioligand therapy is off-target toxicity in salivary glands.
The validation of prostate specific membrane antigen (PSMA) as a molecular target in metastatic castration-resistant prostate cancer has stimulated the development of multiple classes of theranostic ligands that specifically target PSMA. Theranostic ligands are used to image disease or selectively deliver cytotoxic radioactivity to cells expressing PSMA according to the radioisotope conjugated to the ligand. PSMA theranostics is a rapidly advancing field that is now integrating into clinical management of prostate cancer patients. In this review we summarize published research describing the biological role(s) and activity of PSMA, highlight the most clinically advanced PSMA targeting molecules and biomacromolecules, and identify next generation PSMA ligands that aim to further improve treatment efficacy. The goal of this review is to provide a comprehensive assessment of the current state-of-play and a roadmap to achieving further advances in PSMA theranostics.
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Affiliation(s)
- Thomas M Jeitner
- Molecular Imaging Innovations Institute, Department of Radiology, Weill Cornell Medicine, Belfer Research Building, 413 East 69th Street, Room BB-1604, New York, NY 10021, USA
| | - John W Babich
- Molecular Imaging Innovations Institute, Department of Radiology, Weill Cornell Medicine, Belfer Research Building, 413 East 69th Street, Room BB-1604, New York, NY 10021, USA; Weill Cornell Medicine, Sandra and Edward Meyer Cancer Center, New York, NY 10021, USA; Weill Cornell Medicine, Citigroup Biomedical Imaging Center, New York, NY 10021, USA
| | - James M Kelly
- Molecular Imaging Innovations Institute, Department of Radiology, Weill Cornell Medicine, Belfer Research Building, 413 East 69th Street, Room BB-1604, New York, NY 10021, USA; Weill Cornell Medicine, Citigroup Biomedical Imaging Center, New York, NY 10021, USA.
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8
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Fote GM, Geller NR, Efstathiou NE, Hendricks N, Vavvas DG, Reidling JC, Thompson LM, Steffan JS. Isoform-dependent lysosomal degradation and internalization of apolipoprotein E requires autophagy proteins. J Cell Sci 2022; 135:jcs258687. [PMID: 34982109 PMCID: PMC8917355 DOI: 10.1242/jcs.258687] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 12/17/2021] [Indexed: 12/09/2022] Open
Abstract
The human apolipoprotein E4 isoform (APOE4) is the strongest genetic risk factor for late-onset Alzheimer's disease (AD), and lysosomal dysfunction has been implicated in AD pathogenesis. We found, by examining cells stably expressing each APOE isoform, that APOE4 increases lysosomal trafficking, accumulates in enlarged lysosomes and late endosomes, alters autophagic flux and the abundance of autophagy proteins and lipid droplets, and alters the proteomic contents of lysosomes following internalization. We investigated APOE-related lysosomal trafficking further in cell culture, and found that APOE from the post-Golgi compartment is degraded through autophagy. We found that this autophagic process requires the lysosomal membrane protein LAMP2 in immortalized neuron-like and hepatic cells, and in mouse brain tissue. Several macroautophagy-associated proteins were also required for autophagic degradation and internalization of APOE in hepatic cells. The dysregulated autophagic flux and lysosomal trafficking of APOE4 that we observed suggest a possible novel mechanism that might contribute to AD pathogenesis. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Gianna M. Fote
- UC Irvine Department of Biological Chemistry, 825 Health Sciences Road, Medical Sciences I, Room D240, UC Irvine School of Medicine, Irvine, CA 92697-1700, USA
| | - Nicolette R. Geller
- UC Irvine Department of Psychiatry and Human Behavior, Neuropsychiatric Center, UC Irvine Medical Center, 101 The City Drive South, Building 3, Route 88, Orange, CA 92868, USA
| | - Nikolaos E. Efstathiou
- Harvard Medical School Department of Ophthalmology, 243 Charles Street, Boston, MA 02114, USA
| | - Nathan Hendricks
- Institute for Integrative Genome Biology, UC Riverside, Eucalyptus Drive, Riverside, CA 92521, USA
| | - Demetrios G. Vavvas
- Harvard Medical School Department of Ophthalmology, 243 Charles Street, Boston, MA 02114, USA
| | - Jack C. Reidling
- UC Irvine MIND Institute, 2642 Biological Sciences III, Irvine, CA 92697-4545, USA
| | - Leslie M. Thompson
- UC Irvine Department of Biological Chemistry, 825 Health Sciences Road, Medical Sciences I, Room D240, UC Irvine School of Medicine, Irvine, CA 92697-1700, USA
- UC Irvine Department of Psychiatry and Human Behavior, Neuropsychiatric Center, UC Irvine Medical Center, 101 The City Drive South, Building 3, Route 88, Orange, CA 92868, USA
- UC Irvine MIND Institute, 2642 Biological Sciences III, Irvine, CA 92697-4545, USA
- UC Irvine Department of Neurobiology and Behavior, 2205 McGaugh Hall, Irvine, CA 92697, USA
| | - Joan S. Steffan
- UC Irvine Department of Psychiatry and Human Behavior, Neuropsychiatric Center, UC Irvine Medical Center, 101 The City Drive South, Building 3, Route 88, Orange, CA 92868, USA
- UC Irvine MIND Institute, 2642 Biological Sciences III, Irvine, CA 92697-4545, USA
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9
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Extracellular vesicles mediated exocytosis of antisense peptide nucleic acids. MOLECULAR THERAPY. NUCLEIC ACIDS 2021; 25:302-315. [PMID: 34458012 PMCID: PMC8379631 DOI: 10.1016/j.omtn.2021.07.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 07/27/2021] [Indexed: 12/19/2022]
Abstract
Peptide nucleic acids (PNAs), a synthetic DNA mimic, have been extensively utilized for antisense- and antigene-based biomedical applications. Significant efforts have been made to increase the cellular uptake of PNAs, but here we examined relatively unexplored aspects of intracellular trafficking and endocytic recycling of PNAs. For proof-of-concept, we used anti-microRNA (miR) PNA targeting miR-155. The sub-cellular localization of PNA was studied via confocal and flow-cytometry-based assays in HeLa cells. A comprehensive characterization of PNA-containing extracellular vesicles revealed spherical morphology, negative surface charge density, and the presence of tetraspanin markers. Most importantly, we investigated rab11a and rab27b GTPases' role in regulating the exocytosis of PNAs. Organelle staining, followed by confocal imaging, showed higher localization of PNA in lysosomes. Gene-expression analysis established the enhanced functional activity of PNA after inhibition of endocytic recycling. Multiple studies report the exocytosis of single-stranded oligonucleotides, short interfering RNAs (siRNAs), and nanocarriers. To our knowledge, this is the first mechanistic study to establish that PNA undergoes endocytic recycling and exocytosis out of tumor cells. The results presented here can serve as a platform to develop and optimize strategies for improving the therapeutic efficacy of PNAs by avoiding the recycling pathways.
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Prabhakara C, Godbole R, Sil P, Jahnavi S, Gulzar SEJ, van Zanten TS, Sheth D, Subhash N, Chandra A, Shivaraj A, Panikulam P, U I, Nuthakki VK, Puthiyapurayil TP, Ahmed R, Najar AH, Lingamallu SM, Das S, Mahajan B, Vemula P, Bharate SB, Singh PP, Vishwakarma R, Guha A, Sundaramurthy V, Mayor S. Strategies to target SARS-CoV-2 entry and infection using dual mechanisms of inhibition by acidification inhibitors. PLoS Pathog 2021; 17:e1009706. [PMID: 34252168 PMCID: PMC8297935 DOI: 10.1371/journal.ppat.1009706] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 07/22/2021] [Accepted: 06/10/2021] [Indexed: 12/14/2022] Open
Abstract
Many viruses utilize the host endo-lysosomal network for infection. Tracing the endocytic itinerary of SARS-CoV-2 can provide insights into viral trafficking and aid in designing new therapeutic strategies. Here, we demonstrate that the receptor binding domain (RBD) of SARS-CoV-2 spike protein is internalized via the pH-dependent CLIC/GEEC (CG) endocytic pathway in human gastric-adenocarcinoma (AGS) cells expressing undetectable levels of ACE2. Ectopic expression of ACE2 (AGS-ACE2) results in RBD traffic via both CG and clathrin-mediated endocytosis. Endosomal acidification inhibitors like BafilomycinA1 and NH4Cl, which inhibit the CG pathway, reduce the uptake of RBD and impede Spike-pseudoviral infection in both AGS and AGS-ACE2 cells. The inhibition by BafilomycinA1 was found to be distinct from Chloroquine which neither affects RBD uptake nor alters endosomal pH, yet attenuates Spike-pseudovirus entry. By screening a subset of FDA-approved inhibitors for functionality similar to BafilomycinA1, we identified Niclosamide as a SARS-CoV-2 entry inhibitor. Further validation using a clinical isolate of SARS-CoV-2 in AGS-ACE2 and Vero cells confirmed its antiviral effect. We propose that Niclosamide, and other drugs which neutralize endosomal pH as well as inhibit the endocytic uptake, could provide broader applicability in subverting infection of viruses entering host cells via a pH-dependent endocytic pathway.
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Affiliation(s)
| | - Rashmi Godbole
- National Centre for Biological Sciences (TIFR), Bengaluru, India
- University of Trans-Disciplinary Health Sciences and Technology (TDU), Bengaluru, India
| | - Parijat Sil
- National Centre for Biological Sciences (TIFR), Bengaluru, India
| | - Sowmya Jahnavi
- National Centre for Biological Sciences (TIFR), Bengaluru, India
| | - Shah-e-Jahan Gulzar
- National Centre for Biological Sciences (TIFR), Bengaluru, India
- SASTRA University, Thanjavur, India
| | | | - Dhruv Sheth
- National Centre for Biological Sciences (TIFR), Bengaluru, India
| | - Neeraja Subhash
- National Centre for Biological Sciences (TIFR), Bengaluru, India
- SASTRA University, Thanjavur, India
| | - Anchal Chandra
- National Centre for Biological Sciences (TIFR), Bengaluru, India
| | | | | | - Ibrahim U
- National Centre for Biological Sciences (TIFR), Bengaluru, India
| | | | | | - Riyaz Ahmed
- CSIR—Indian Institute of Integrative Medicine, Jammu, India
| | | | - Sai Manoz Lingamallu
- Institute for Stem Cell Science and Regenerative Medicine (inSTEM), Bengaluru, India
- Manipal Academy of Higher Education (MAHE), Madhav Nagar, Manipal, Karnataka, India
| | - Snigdhadev Das
- National Centre for Biological Sciences (TIFR), Bengaluru, India
| | | | - Praveen Vemula
- Institute for Stem Cell Science and Regenerative Medicine (inSTEM), Bengaluru, India
| | | | | | | | - Arjun Guha
- Institute for Stem Cell Science and Regenerative Medicine (inSTEM), Bengaluru, India
| | | | - Satyajit Mayor
- National Centre for Biological Sciences (TIFR), Bengaluru, India
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11
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Pesaola F, Quassollo G, Venier AC, De Paul AL, Noher I, Bisbal M. The neuronal ceroid lipofuscinosis-related protein CLN8 regulates endo-lysosomal dynamics and dendritic morphology. Biol Cell 2021; 113:419-437. [PMID: 34021618 DOI: 10.1111/boc.202000016] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 05/18/2021] [Accepted: 05/22/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND INFORMATION The endo-lysosomal system (ELS) comprises a set of membranous organelles responsible for transporting intracellular and extracellular components within cells. Defects in lysosomal proteins usually affect a large variety of processes and underlie many diseases, most of them with a strong neuronal impact. Mutations in the endoplasmic reticulum-resident CLN8 protein cause CLN8 disease. This condition is one of the 14 known neuronal ceroid lipofuscinoses (NCLs), a group of inherited diseases characterised by accumulation of lipofuscin-like pigments within lysosomes. Besides mediating the transport of soluble lysosomal proteins, recent research suggested a role for CLN8 in the transport of vesicles and lipids, and autophagy. However, the consequences of CLN8 deficiency on ELS structure and activity, as well as the potential impact on neuronal development, remain poorly characterised. Therefore, we performed CLN8 knockdown in neuronal and non-neuronal cell models to analyse structural, dynamic and functional changes in the ELS and to assess the impact of CLN8 deficiency on axodendritic development. RESULTS CLN8 knockdown increased the size of the Golgi apparatus, the number of mobile vesicles and the speed of endo-lysosomes. Using the fluorescent fusion protein mApple-LAMP1-pHluorin, we detected significant lysosomal alkalisation in CLN8-deficient cells. In turn, experiments in primary rat hippocampal neurons showed that CLN8 deficiency decreased the complexity and size of the somatodendritic compartment. CONCLUSIONS Our results suggest the participation of CLN8 in vesicular distribution, lysosomal pH and normal development of the dendritic tree. We speculate that the defects triggered by CLN8 deficiency on ELS structure and dynamics underlie morphological alterations in neurons, which ultimately lead to the characteristic neurodegeneration observed in this NCL. SIGNIFICANCE This is, to our knowledge, the first characterisation of the effects of CLN8 dysfunction on the structure and dynamics of the ELS. Moreover, our findings suggest a novel role for CLN8 in somatodendritic development, which may account at least in part for the neuropathological manifestations associated with CLN8 disease.
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Affiliation(s)
- Favio Pesaola
- Programa de Investigación Translacional de Lipofuscinosis Ceroidea Neuronal, Hospital de Niños de Córdoba, Córdoba, 5014, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Investigaciones Médicas "Mercedes y Martin Ferreyra"- IMMF-UNC-CONICET, Laboratorio de Neurobiología, Av. Friuli 2434, 5016 Córdoba, Argentina, Universidad Nacional de Córdoba, Córdoba, 5000, Argentina
| | - Gonzalo Quassollo
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Investigaciones Médicas "Mercedes y Martin Ferreyra"- IMMF-UNC-CONICET, Laboratorio de Neurobiología, Av. Friuli 2434, 5016 Córdoba, Argentina, Universidad Nacional de Córdoba, Córdoba, 5000, Argentina
| | - Ana Clara Venier
- Programa de Investigación Translacional de Lipofuscinosis Ceroidea Neuronal, Hospital de Niños de Córdoba, Córdoba, 5014, Argentina.,Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Investigación en Ciencias de la Salud (INICSA), Bv. de la Reforma y Enfermera Gordillo, Ciudad Universitaria, Córdoba, 5016, Argentina
| | - Ana Lucía De Paul
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Investigación en Ciencias de la Salud (INICSA), Bv. de la Reforma y Enfermera Gordillo, Ciudad Universitaria, Córdoba, 5016, Argentina.,Universidad Nacional de Córdoba, Facultad de Ciencias Médicas, Centro de Microscopía Electrónica, Bv. de la Reforma y Enfermera Gordillo, Ciudad Universitaria, Córdoba, 5016, Argentina
| | - Ines Noher
- Programa de Investigación Translacional de Lipofuscinosis Ceroidea Neuronal, Hospital de Niños de Córdoba, Córdoba, 5014, Argentina
| | - Mariano Bisbal
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Investigaciones Médicas "Mercedes y Martin Ferreyra"- IMMF-UNC-CONICET, Laboratorio de Neurobiología, Av. Friuli 2434, 5016 Córdoba, Argentina, Universidad Nacional de Córdoba, Córdoba, 5000, Argentina.,Instituto Universitario de Ciencias Biomédicas Córdoba, Córdoba, 5016, Argentina
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12
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Calciprotein particle-induced cytotoxicity via lysosomal dysfunction and altered cholesterol distribution in renal epithelial HK-2 cells. Sci Rep 2020; 10:20125. [PMID: 33208865 PMCID: PMC7676272 DOI: 10.1038/s41598-020-77308-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 11/10/2020] [Indexed: 12/24/2022] Open
Abstract
Dietary phosphate overload induces chronic kidney disease (CKD), and calciprotein particles (CPPs), a form of nanoparticle comprising calcium phosphate and serum proteins, has been proposed to cause renal toxicity. However, the mechanism of CPP cytotoxicity in renal tubular cells is unknown. Here we show that in renal proximal tubular epithelial HK-2 cells, endocytosed CPPs accumulate in late endosomes/lysosomes (LELs) and increase their luminal pH by ~ 1.0 unit. This results in a decrease in lysosomal hydrolase activity and autophagic flux blockage without lysosomal rupture and reactive oxygen species generation. CPP treatment led to vulnerability to H2O2-induced oxidative stress and plasma membrane injury, probably because of autophagic flux blockage and decreased plasma membrane cholesterol, respectively. CPP-induced disruption of lysosomal homeostasis, autophagy flux and plasma membrane integrity might trigger a vicious cycle, leading to progressive nephron loss.
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Toth AE, Holst MR, Nielsen MS. Vesicular Transport Machinery in Brain Endothelial Cells: What We Know and What We Do not. Curr Pharm Des 2020; 26:1405-1416. [PMID: 32048959 DOI: 10.2174/1381612826666200212113421] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 12/03/2019] [Indexed: 12/20/2022]
Abstract
The vesicular transport machinery regulates numerous essential functions in cells such as cell polarity, signaling pathways, and the transport of receptors and their cargoes. From a pharmaceutical perspective, vesicular transport offers avenues to facilitate the uptake of therapeutic agents into cells and across cellular barriers. In order to improve receptor-mediated transcytosis of biologics across the blood-brain barrier and into the diseased brain, a detailed understanding of intracellular transport mechanisms is essential. The vesicular transport machinery is a highly complex network and involves an array of protein complexes, cytosolic adaptor proteins, and the subcellular structures of the endo-lysosomal system. The endo-lysosomal system includes several types of vesicular entities such as early, late, and recycling endosomes, exosomes, ectosomes, retromer-coated vesicles, lysosomes, trans-endothelial channels, and tubules. While extensive research has been done on the trafficking system in many cell types, little is known about vesicular trafficking in brain endothelial cells. Consequently, assumptions on the transport system in endothelial cells are based on findings in polarised epithelial cells, although recent studies have highlighted differences in the endothelial system. This review highlights aspects of the vesicular trafficking machinery in brain endothelial cells, including recent findings, limitations, and opportunities for further studies.
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Affiliation(s)
- Andrea E Toth
- Department of Biomedicine, Faculty of Health, Aarhus University, Høegh-Guldberg Gade 10, 8000 Aarhus C, Denmark
| | - Mikkel R Holst
- Department of Biomedicine, Faculty of Health, Aarhus University, Høegh-Guldberg Gade 10, 8000 Aarhus C, Denmark
| | - Morten S Nielsen
- Department of Biomedicine, Faculty of Health, Aarhus University, Høegh-Guldberg Gade 10, 8000 Aarhus C, Denmark
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14
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Two-pore and TRPML cation channels: Regulators of phagocytosis, autophagy and lysosomal exocytosis. Pharmacol Ther 2020; 220:107713. [PMID: 33141027 DOI: 10.1016/j.pharmthera.2020.107713] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 10/19/2020] [Indexed: 02/07/2023]
Abstract
The old Greek saying "Panta Rhei" ("everything flows") is true for all life and all living things in general. It also becomes nicely evident when looking closely into cells. There, material from the extracellular space is taken up by endocytic processes and transported to endosomes where it is sorted either for recycling or degradation. Cargo is also packaged for export through exocytosis involving the Golgi network, lysosomes and other organelles. Everything in this system is in constant motion and many proteins are necessary to coordinate transport along the different intracellular pathways to avoid chaos. Among these proteins are ion channels., in particular TRPML channels (mucolipins) and two-pore channels (TPCs) which reside on endosomal and lysosomal membranes to speed up movement between organelles, e.g. by regulating fusion and fission; they help readjust pH and osmolarity changes due to such processes, or they promote exocytosis of export material. Pathophysiologically, these channels are involved in neurodegenerative, metabolic, retinal and infectious diseases, cancer, pigmentation defects, and immune cell function, and thus have been proposed as novel pharmacological targets, e.g. for the treatment of lysosomal storage disorders, Duchenne muscular dystrophy, or different types of cancer. Here, we discuss the similarities but also differences of TPCs and TRPMLs in regulating phagocytosis, autophagy and lysosomal exocytosis, and we address the contradictions and open questions in the field relating to the roles TPCs and TRPMLs play in these different processes.
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15
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Endothelin-converting enzyme-1 regulates glucagon-like peptide-1 receptor signalling and resensitisation. Biochem J 2019; 476:513-533. [PMID: 30626614 DOI: 10.1042/bcj20180853] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 01/07/2019] [Accepted: 01/08/2019] [Indexed: 02/08/2023]
Abstract
Following nutrient ingestion, glucagon-like peptide 1 (GLP-1) is secreted from intestinal L-cells and mediates anti-diabetic effects, most notably stimulating glucose-dependent insulin release from pancreatic β-cells but also inhibiting glucagon release, promoting satiety and weight reduction and potentially enhancing or preserving β-cell mass. These effects are mediated by the GLP-1 receptor (GLP-1R), which is a therapeutic target in type 2 diabetes. Although agonism at the GLP-1R has been well studied, desensitisation and resensitisation are perhaps less well explored. An understanding of these events is important, particularly in the design and use of novel receptor ligands. Here, using either HEK293 cells expressing the recombinant human GLP-1R or the pancreatic β-cell line, INS-1E with endogenous expressesion of the GLP-1R, we demonstrate GLP-1R desensitisation and subsequent resensitisation following removal of extracellular GLP-1 7-36 amide. Resensitisation is dependent on receptor internalisation, endosomal acidification and receptor recycling. Resensitisation is also regulated by endothelin-converting enzyme-1 (ECE-1) activity, most likely through proteolysis of GLP-1 in endosomes and the facilitation of GLP-1R dephosphorylation and recycling. Inhibition of ECE-1 activity also increases GLP-1-induced activation of extracellular signal-regulated kinase and generation of cAMP, suggesting processes dependent upon the lifetime of the internalised ligand-receptor complex.
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16
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A potential gain-of-function variant of SLC9A6 leads to endosomal alkalinization and neuronal atrophy associated with Christianson Syndrome. Neurobiol Dis 2019; 121:187-204. [DOI: 10.1016/j.nbd.2018.10.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 09/18/2018] [Accepted: 10/03/2018] [Indexed: 11/24/2022] Open
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Narayana YV, Gadgil C, Mote RD, Rajan R, Subramanyam D. Clathrin-Mediated Endocytosis Regulates a Balance between Opposing Signals to Maintain the Pluripotent State of Embryonic Stem Cells. Stem Cell Reports 2018; 12:152-164. [PMID: 30554918 PMCID: PMC6335602 DOI: 10.1016/j.stemcr.2018.11.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 11/16/2018] [Accepted: 11/19/2018] [Indexed: 12/12/2022] Open
Abstract
Endocytosis is implicated in the maintenance of embryonic stem cell (ESC) pluripotency, although its exact role and the identity of molecular players remain poorly understood. Here, we show that the clathrin heavy chain (CLTC), involved in clathrin-mediated endocytosis (CME), is vital for maintaining mouse ESC (mESC) pluripotency. Knockdown of Cltc resulted in a loss of pluripotency accompanied by reduced E-cadherin (E-CAD) levels and increased levels of transforming growth factor β (TGF-β) and extracellular signal-regulated kinase (ERK) signaling. We demonstrate that both E-CAD and TGF-β receptor type 1 (TGF-βR1) are internalized through CME in mESCs. While E-CAD is recycled, TGF-βR1 is targeted for lysosomal degradation thus maintaining inverse levels of these molecules. Finally, we show that E-CAD interacts with ERK, and that the decreased pluripotency upon CME loss can be rescued by inhibiting TGF-βR, MEK, and GSK3β, or overexpressing E-CAD. Our results demonstrate that CME is critical for balancing signaling outputs to regulate ESC pluripotency, and possibly cell fate choices in early development. Knockdown of Cltc results in loss of mESC pluripotency CME regulates E-CAD and TGF-βR1 trafficking in mESCs ESCs lacking CME can be rescued by TGF-βR1/MEK inhibition or E-CAD overexpression CME balances opposing signaling outputs to maintain ESC pluripotency
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Affiliation(s)
- Yadavalli V Narayana
- National Centre for Cell Science, SP Pune University, Ganeshkhind, Pune 411007, India; Savitribai Phule Pune University, Ganeshkhind, Pune 411007, India
| | - Chetan Gadgil
- Chemical Engineering Department, National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411008, India
| | - Ridim D Mote
- National Centre for Cell Science, SP Pune University, Ganeshkhind, Pune 411007, India
| | - Raghav Rajan
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, NCL Colony, Pune 411008, India
| | - Deepa Subramanyam
- National Centre for Cell Science, SP Pune University, Ganeshkhind, Pune 411007, India.
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18
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Sherman HG, Jovanovic C, Stolnik S, Baronian K, Downard AJ, Rawson FJ. New Perspectives on Iron Uptake in Eukaryotes. Front Mol Biosci 2018; 5:97. [PMID: 30510932 PMCID: PMC6254016 DOI: 10.3389/fmolb.2018.00097] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 10/23/2018] [Indexed: 12/20/2022] Open
Abstract
All eukaryotic organisms require iron to function. Malfunctions within iron homeostasis have a range of physiological consequences, and can lead to the development of pathological conditions that can result in an excess of non-transferrin bound iron (NTBI). Despite extensive understanding of iron homeostasis, the links between the “macroscopic” transport of iron across biological barriers (cellular membranes) and the chemistry of redox changes that drive these processes still needs elucidating. This review draws conclusions from the current literature, and describes some of the underlying biophysical and biochemical processes that occur in iron homeostasis. By first taking a broad view of iron uptake within the gut and subsequent delivery to tissues, in addition to describing the transferrin and non-transferrin mediated components of these processes, we provide a base of knowledge from which we further explore NTBI uptake. We provide concise up-to-date information of the transplasma electron transport systems (tPMETSs) involved within NTBI uptake, and highlight how these systems are not only involved within NTBI uptake for detoxification but also may play a role within the reduction of metabolic stress through regeneration of intracellular NAD(P)H/NAD(P)+ levels. Furthermore, we illuminate the thermodynamics that governs iron transport, namely the redox potential cascade and electrochemical behavior of key components of the electron transport systems that facilitate the movement of electrons across the plasma membrane to the extracellular compartment. We also take account of kinetic changes that occur to transport iron into the cell, namely membrane dipole change and their consequent effects within membrane structure that act to facilitate transport of ions.
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Affiliation(s)
- Harry G Sherman
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
| | | | - Snow Stolnik
- Division of Molecular Therapeutics and Formulation, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
| | - Kim Baronian
- School of Biological Sciences, University of Canterbury, Christchurch, New Zealand
| | - Alison J Downard
- MacDiarmid Institute for Advanced Materials and Nanotechnology, School of Physical and Chemical Sciences, University of Canterbury, Christchurch, New Zealand
| | - Frankie J Rawson
- Division of Regenerative Medicine and Cellular Therapies, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
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Zhao C, Gao Y, Zhao L, Li Y, Zhang Y, Wang S, Zhang H, Lu G, Guo X. The expression and function of the neonatal Fc receptor in thyrocytes of Hashimoto's thyroiditis. Int Immunopharmacol 2017; 44:53-60. [PMID: 28081504 DOI: 10.1016/j.intimp.2016.12.032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 12/29/2016] [Accepted: 12/30/2016] [Indexed: 10/20/2022]
Abstract
OBJECTIVE Thyroglobulin (Tg) and thyroid peroxidase (TPO) antibodies (TgAb and TPOAb), which are primarily of the immunoglobulin G (IgG) class, can mediate antibody-dependent cell-mediated cytotoxicity in vitro. However, it is unclear whether any thyrocyte molecules can facilitate the transport and elimination of TgAb and TPOAb. The IgG transport receptor neonatal Fc receptor (FcRn) is a candidate mediator of these processes. In this study, we aimed to evaluate FcRn expression and function in normal and Hashimoto's thyroiditis (HT) thyrocytes. METHODS FcRn expression in primary thyrocyte cultures (four normal and four HT groups) was examined by polymerase chain reaction (PCR) and Western blotting. Localization of FcRn was demonstrated by immunoelectron microscopy. A double immunofluorescence staining method was adopted to detect FcRn and internalized human TgAb IgG. Stimulation experiments were performed to assess the regulation of FcRn expression by T helper cell 1 (Th1) (IFN-γ and TNF-α) and Th2 cytokines (IL-10 and IL-4). RESULTS FcRn expression was lower in HT thyrocytes than in normal thyrocytes. FcRn was located in the cytoplasm, membranes, mitochondria and transport vesicles of thyrocytes. Both human IgG and TgAb IgG were internalized by thyrocytes in a pH-dependent manner and co-localized with FcRn in thyrocytes. FcRn expression was downregulated by Th1 and Th2 cytokines in both normal and HT thyrocytes in a dose-dependent manner. CONCLUSIONS Our results suggest that FcRn may be associated with the transport and metabolism of IgG in thyrocytes and that transport is independent of IgG type. FcRn may be involved in HT pathogenesis.
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Affiliation(s)
- Chenxu Zhao
- Department of Endocrinology, Peking University First Hospital, No. 8 Xi Shi Ku Street, Xi Cheng District, Beijing 100034, China
| | - Ying Gao
- Department of Endocrinology, Peking University First Hospital, No. 8 Xi Shi Ku Street, Xi Cheng District, Beijing 100034, China
| | - Lanlan Zhao
- Department of Endocrinology, Civil Aviation General Hospital, No. 1 Gao Jing Jia Street, Chao Yang District, Beijing 100123, China
| | - Yuan Li
- Department of Endocrinology, Peking University First Hospital, No. 8 Xi Shi Ku Street, Xi Cheng District, Beijing 100034, China
| | - Yang Zhang
- Department of Endocrinology, Peking University First Hospital, No. 8 Xi Shi Ku Street, Xi Cheng District, Beijing 100034, China.
| | - Suxia Wang
- Department of Pathology, Peking University First Hospital, No. 8 Xi Shi Ku Street, Xi Cheng District, Beijing 100034, China
| | - Hong Zhang
- Department of Endocrinology, Peking University First Hospital, No. 8 Xi Shi Ku Street, Xi Cheng District, Beijing 100034, China
| | - Guizhi Lu
- Department of Endocrinology, Peking University First Hospital, No. 8 Xi Shi Ku Street, Xi Cheng District, Beijing 100034, China
| | - Xiaohui Guo
- Department of Endocrinology, Peking University First Hospital, No. 8 Xi Shi Ku Street, Xi Cheng District, Beijing 100034, China
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Johnson DE, Ostrowski P, Jaumouillé V, Grinstein S. The position of lysosomes within the cell determines their luminal pH. J Cell Biol 2016; 212:677-92. [PMID: 26975849 PMCID: PMC4792074 DOI: 10.1083/jcb.201507112] [Citation(s) in RCA: 370] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Analysis of luminal lysosomal pH in combination with heterologous expression of lysosomal-associated proteins indicates that peripheral lysosomes are more alkaline than juxtanuclear ones and that depletion of Rab7 and its effector, RILP, are associated with and can account for the reduced acidification. We examined the luminal pH of individual lysosomes using quantitative ratiometric fluorescence microscopy and report an unappreciated heterogeneity: peripheral lysosomes are less acidic than juxtanuclear ones despite their comparable buffering capacity. An increased passive (leak) permeability to protons, together with reduced vacuolar H+–adenosine triphosphatase (V-ATPase) activity, accounts for the reduced acidifying ability of peripheral lysosomes. The altered composition of peripheral lysosomes is due, at least in part, to more limited access to material exported by the biosynthetic pathway. The balance between Rab7 and Arl8b determines the subcellular localization of lysosomes; more peripheral lysosomes have reduced Rab7 density. This in turn results in decreased recruitment of Rab-interacting lysosomal protein (RILP), an effector that regulates the recruitment and stability of the V1G1 component of the lysosomal V-ATPase. Deliberate margination of lysosomes is associated with reduced acidification and impaired proteolytic activity. The heterogeneity in lysosomal pH may be an indication of a broader functional versatility.
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Affiliation(s)
- Danielle E Johnson
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Philip Ostrowski
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Valentin Jaumouillé
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
| | - Sergio Grinstein
- Program in Cell Biology, Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada
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Schreij AMA, Fon EA, McPherson PS. Endocytic membrane trafficking and neurodegenerative disease. Cell Mol Life Sci 2016; 73:1529-45. [PMID: 26721251 PMCID: PMC11108351 DOI: 10.1007/s00018-015-2105-x] [Citation(s) in RCA: 110] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 10/26/2015] [Accepted: 11/26/2015] [Indexed: 12/11/2022]
Abstract
Neurodegenerative diseases are amongst the most devastating of human disorders. New technologies have led to a rapid increase in the identification of disease-related genes with an enhanced appreciation of the key roles played by genetics in the etiology of these disorders. Importantly, pinpointing the normal function of disease gene proteins leads to new understanding of the cellular machineries and pathways that are altered in the disease process. One such emerging pathway is membrane trafficking in the endosomal system. This key cellular process controls the localization and levels of a myriad of proteins and is thus critical for normal cell function. In this review we will focus on three neurodegenerative diseases; Parkinson disease, amyotrophic lateral sclerosis, and hereditary spastic paraplegias, for which a large number of newly discovered disease genes encode proteins that function in endosomal membrane trafficking. We will describe how alterations in these proteins affect endosomal function and speculate on the contributions of these disruptions to disease pathophysiology.
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Affiliation(s)
- Andrea M A Schreij
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, QC, H3A 2B4, Canada
| | - Edward A Fon
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, QC, H3A 2B4, Canada
| | - Peter S McPherson
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, QC, H3A 2B4, Canada.
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22
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Smith GA, Howell GJ, Phillips C, Muench SP, Ponnambalam S, Harrison MA. Extracellular and Luminal pH Regulation by Vacuolar H+-ATPase Isoform Expression and Targeting to the Plasma Membrane and Endosomes. J Biol Chem 2016; 291:8500-15. [PMID: 26912656 PMCID: PMC4861423 DOI: 10.1074/jbc.m116.723395] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Indexed: 01/02/2023] Open
Abstract
Plasma membrane vacuolar H+-ATPase (V-ATPase) activity of tumor cells is a major factor in control of cytoplasmic and extracellular pH and metastatic potential, but the isoforms involved and the factors governing plasma membrane recruitment remain uncertain. Here, we examined expression, distribution, and activity of V-ATPase isoforms in invasive prostate adenocarcinoma (PC-3) cells. Isoforms 1 and 3 were the most highly expressed forms of membrane subunit a, with a1 and a3 the dominant plasma membrane isoforms. Correlation between plasma membrane V-ATPase activity and invasiveness was limited, but RNAi knockdown of either a isoform did slow cell proliferation and inhibit invasion in vitro. Isoform a1 was recruited to the cell surface from the early endosome-recycling complex pathway, its knockdown arresting transferrin receptor recycling. Isoform a3 was associated with the late endosomal/lysosomal compartment. Both a isoforms associated with accessory protein Ac45, knockdown of which stalled transit of a1 and transferrin-transferrin receptor, decreased proton efflux, and reduced cell growth and invasiveness; this latter effect was at least partly due to decreased delivery of the membrane-bound matrix metalloproteinase MMP-14 to the plasma membrane. These data indicate that in prostatic carcinoma cells, a1 and a3 isoform populations predominate in different compartments where they maintain different luminal pH. Ac45 plays a central role in navigating the V-ATPase to the plasma membrane, and hence it is an important factor in expression of the invasive phenotype.
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Affiliation(s)
- Gina A Smith
- From the Endothelial Cell Biology Unit, School of Molecular and Cellular Biology and
| | - Gareth J Howell
- From the Endothelial Cell Biology Unit, School of Molecular and Cellular Biology and
| | - Clair Phillips
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Stephen P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
| | | | - Michael A Harrison
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom
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23
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Fan SHY, Numata Y, Numata M. Endosomal Na+/H+ exchanger NHE5 influences MET recycling and cell migration. Mol Biol Cell 2015; 27:702-15. [PMID: 26700318 PMCID: PMC4750928 DOI: 10.1091/mbc.e15-04-0257] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 12/18/2015] [Indexed: 12/17/2022] Open
Abstract
The neuron-enriched Na+/H+ exchanger NHE5 is expressed in C6 glioma cells, acidifies recycling endosomes, and modulates cell surface abundance of receptor tyrosine kinases MET and EGFR. NHE5 depletion impairs MET recycling and facilitates degradation, thereby impairing cell migration and polarity. Increased recycling and elevated cell surface expression of receptors serve as a mechanism for persistent receptor-mediated signaling. We show that the neuron-enriched Na+/H+ exchanger NHE5 is abundantly expressed in C6 glioma cells and plays an important part in regulating cell surface expression of the receptor tyrosine kinases MET and EGF receptor. NHE5 is associated with transferrin receptor (TfR)- and Rab11-positive recycling endosomal membranes, and NHE5 knockdown by short hairpin RNA significantly elevates pH of TfR-positive recycling endosomes. We present evidence that NHE5 facilitates MET recycling to the plasma membrane, protects MET from degradation, and modulates HGF-induced phosphatidylinositol-3-kinase and mitogen-activated protein kinase signaling. Moreover, NHE5 depletion abrogates Rac1 and Cdc42 signaling and actin cytoskeletal remodeling. We further show that NHE5 knockdown impairs directed cell migration and causes loss of cell polarity. Our study highlights a possible role of recycling endosomal pH in regulating receptor-mediated signaling through vesicular trafficking.
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Affiliation(s)
- Steven Hung-Yi Fan
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Yuka Numata
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Masayuki Numata
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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24
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Tsvetanova NG, von Zastrow M. Spatial encoding of cyclic AMP signaling specificity by GPCR endocytosis. Nat Chem Biol 2014; 10:1061-5. [PMID: 25362359 PMCID: PMC4232470 DOI: 10.1038/nchembio.1665] [Citation(s) in RCA: 209] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 09/05/2014] [Indexed: 12/11/2022]
Abstract
G protein-coupled receptors (GPCRs) are well known to signal via cyclic AMP (cAMP) production at the plasma membrane, but it is now clear that various GPCRs also signal after internalization. Apart from its temporal impact through prolonging the cellular response, we wondered whether the endosome-initiated signal encodes any discrete spatial information. Using the β2-adrenoceptor (β2-AR) as a model, we show that endocytosis is required for the full repertoire of downstream cAMP-dependent transcriptional control. Next, we describe an orthogonal optogenetic approach to definitively establish that the location of cAMP production is indeed the critical variable determining the transcriptional response. Finally, our results suggest that this spatial encoding scheme helps cells functionally discriminate chemically distinct β2-AR ligands according to differences in their ability to promote receptor endocytosis. These findings reveal a discrete principle for achieving cellular signaling specificity based on endosome-mediated spatial encoding of intracellular second messenger production and 'location-aware' downstream transcriptional control.
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Affiliation(s)
| | - Mark von Zastrow
- Department of Psychiatry, University of California, San Francisco CA, USA
- Department of Cellular & Molecular Pharmacology, University of California, San Francisco CA, USA
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25
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Nyasae LK, Schell MJ, Hubbard AL. Copper directs ATP7B to the apical domain of hepatic cells via basolateral endosomes. Traffic 2014; 15:1344-65. [PMID: 25243755 DOI: 10.1111/tra.12229] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 09/16/2014] [Indexed: 01/01/2023]
Abstract
Physiologic Cu levels regulate the intracellular location of the Cu ATPase ATP7B. Here, we determined the routes of Cu-directed trafficking of endogenous ATP7B in the polarized hepatic cell line WIF-B and in the liver in vivo. Copper (10 µm) caused ATP7B to exit the trans-Golgi network (TGN) in vesicles, which trafficked via large basolateral endosomes to the apical domain within 1 h. Although perturbants of luminal acidification had little effect on the TGN localization of ATP7B in low Cu, they blocked delivery to the apical membrane in elevated Cu. If the vesicular proton-pump inhibitor bafilomycin-A1 (Baf) was present with Cu, ATP7B still exited the TGN, but accumulated in large endosomes located near the coverslip, in the basolateral region. Baf washout restored ATP7B trafficking to the apical domain. If ATP7B was staged apically in high Cu, Baf addition promoted the accumulation of ATP7B in subapical endosomes, indicating a blockade of apical recycling, with concomitant loss of ATP7B at the apical membrane. The retrograde pathway to the TGN, induced by Cu removal, was far less affected by Baf than the anterograde (Cu-stimulated) case. Overall, loss of acidification-impaired Cu-regulated trafficking of ATP7B at two main sites: (i) sorting and exit from large basolateral endosomes and (ii) recycling via endosomes near the apical membrane.
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Affiliation(s)
- Lydia K Nyasae
- Department of Cell Biology, The Johns Hopkins School of Medicine, 725 N. Wolfe Street, Baltimore, MD, 20184, USA
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26
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Lane DJR, Richardson DR. The active role of vitamin C in mammalian iron metabolism: much more than just enhanced iron absorption! Free Radic Biol Med 2014; 75:69-83. [PMID: 25048971 DOI: 10.1016/j.freeradbiomed.2014.07.007] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 07/04/2014] [Accepted: 07/08/2014] [Indexed: 01/18/2023]
Abstract
Ascorbate is a cofactor in numerous metabolic reactions. Humans cannot synthesize ascorbate owing to inactivation of the gene encoding the enzyme l-gulono-γ-lactone oxidase, which is essential for ascorbate synthesis. Accumulating evidence strongly suggests that in addition to the known ability of dietary ascorbate to enhance nonheme iron absorption in the gut, ascorbate within mammalian systems can regulate cellular iron uptake and metabolism. Ascorbate modulates iron metabolism by stimulating ferritin synthesis, inhibiting lysosomal ferritin degradation, and decreasing cellular iron efflux. Furthermore, ascorbate cycling across the plasma membrane is responsible for ascorbate-stimulated iron uptake from low-molecular-weight iron-citrate complexes, which are prominent in the plasma of individuals with iron-overload disorders. Importantly, this iron-uptake pathway is of particular relevance to astrocyte brain iron metabolism and tissue iron loading in disorders such as hereditary hemochromatosis and β-thalassemia. Recent evidence also indicates that ascorbate is a novel modulator of the classical transferrin-iron uptake pathway, which provides almost all iron for cellular demands and erythropoiesis under physiological conditions. Ascorbate acts to stimulate transferrin-dependent iron uptake by an intracellular reductive mechanism, strongly suggesting that it may act to stimulate iron mobilization from the endosome. The ability of ascorbate to regulate transferrin iron uptake could help explain the metabolic defect that contributes to ascorbate-deficiency-induced anemia.
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Affiliation(s)
- Darius J R Lane
- Molecular Pharmacology and Pathology Program, Department of Pathology and Bosch Institute, University of Sydney, Sydney, NSW 2006, Australia.
| | - Des R Richardson
- Molecular Pharmacology and Pathology Program, Department of Pathology and Bosch Institute, University of Sydney, Sydney, NSW 2006, Australia.
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27
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Wüstner D, Christensen T, Solanko LM, Sage D. Photobleaching kinetics and time-integrated emission of fluorescent probes in cellular membranes. Molecules 2014; 19:11096-130. [PMID: 25076144 PMCID: PMC6271172 DOI: 10.3390/molecules190811096] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 07/04/2014] [Accepted: 07/10/2014] [Indexed: 12/02/2022] Open
Abstract
Since the pioneering work of Hirschfeld, it is known that time-integrated emission (TiEm) of a fluorophore is independent of fluorescence quantum yield and illumination intensity. Practical implementation of this important result for determining exact probe distribution in living cells is often hampered by the presence of autofluorescence. Using kinetic modelling of photobleaching combined with pixel-wise bleach rate fitting of decay models with an updated plugin to the ImageJ program, it is shown that the TiEm of a fluorophore in living cells can be determined exactly from the product of bleaching amplitude and time constant. This applies to mono-exponential bleaching from the first excited singlet and/or triplet state and to multi-exponential combinations of such processes. The TiEm can be used to correct for illumination shading and background autofluorescence without the need for fluorescent test layers or separate imaging of non-stained cells. We apply the method to simulated images and to images of cells, whose membranes were labelled with fluorescent sterols and sphingolipids. Our bleaching model can be extended to include a probability density function (PDF) of intrinsic bleach rate constants with a memory kernel. This approach results in a time-dependent bleach rate coefficient and is exemplified for fluorescent sterols in restricted intracellular environments, like lipid droplets. We show that for small deviations from the classical exponential bleaching, the TiEm of decay functions with rate coefficients remains largely independent of fluorescence lifetime and illumination, and thereby represents a faithful measure of probe distribution.
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Affiliation(s)
- Daniel Wüstner
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.
| | - Tanja Christensen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.
| | - Lukasz M Solanko
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark.
| | - Daniel Sage
- Biomedical Imaging Group, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
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28
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Brignone MS, Lanciotti A, Visentin S, De Nuccio C, Molinari P, Camerini S, Diociaiuti M, Petrini S, Minnone G, Crescenzi M, Laudiero LB, Bertini E, Petrucci TC, Ambrosini E. Megalencephalic leukoencephalopathy with subcortical cysts protein-1 modulates endosomal pH and protein trafficking in astrocytes: relevance to MLC disease pathogenesis. Neurobiol Dis 2014; 66:1-18. [PMID: 24561067 PMCID: PMC4003525 DOI: 10.1016/j.nbd.2014.02.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 01/20/2014] [Accepted: 02/10/2014] [Indexed: 11/28/2022] Open
Abstract
Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare leukodystrophy caused by mutations in the gene encoding MLC1, a membrane protein mainly expressed in astrocytes in the central nervous system. Although MLC1 function is unknown, evidence is emerging that it may regulate ion fluxes. Using biochemical and proteomic approaches to identify MLC1 interactors and elucidate MLC1 function we found that MLC1 interacts with the vacuolar ATPase (V-ATPase), the proton pump that regulates endosomal acidity. Because we previously showed that in intracellular organelles MLC1 directly binds Na, K-ATPase, which controls endosomal pH, we studied MLC1 endosomal localization and trafficking and MLC1 effects on endosomal acidity and function using human astrocytoma cells overexpressing wild-type (WT) MLC1 or MLC1 carrying pathological mutations. We found that WT MLC1 is abundantly expressed in early (EEA1(+), Rab5(+)) and recycling (Rab11(+)) endosomes and uses the latter compartment to traffic to the plasma membrane during hyposmotic stress. We also showed that WT MLC1 limits early endosomal acidification and influences protein trafficking in astrocytoma cells by stimulating protein recycling, as revealed by FITC-dextran measurement of endosomal pH and transferrin protein recycling assay, respectively. WT MLC1 also favors recycling to the plasma-membrane of the TRPV4 cation channel which cooperates with MLC1 to activate calcium influx in astrocytes during hyposmotic stress. Although MLC disease-causing mutations differentially affect MLC1 localization and trafficking, all the mutated proteins fail to influence endosomal pH and protein recycling. This study demonstrates that MLC1 modulates endosomal pH and protein trafficking suggesting that alteration of these processes contributes to MLC pathogenesis.
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Affiliation(s)
- Maria S Brignone
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Angela Lanciotti
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Sergio Visentin
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Chiara De Nuccio
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Paola Molinari
- Department of Pharmacology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Serena Camerini
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Marco Diociaiuti
- Department of Technology and Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Stefania Petrini
- Unit of Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Pediatric Research Hospital, Piazza S. Onofrio 4, 00165 Rome, Italy.
| | - Gaetana Minnone
- Unit of Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Pediatric Research Hospital, Piazza S. Onofrio 4, 00165 Rome, Italy.
| | - Marco Crescenzi
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Luisa Bracci Laudiero
- Unit of Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Pediatric Research Hospital, Piazza S. Onofrio 4, 00165 Rome, Italy; Institute of Translational Pharmacology, CNR, Via del Fosso Cavaliere 100, 00133 Rome, Italy.
| | - Enrico Bertini
- Unit of Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Pediatric Research Hospital, Piazza S. Onofrio 4, 00165 Rome, Italy.
| | - Tamara C Petrucci
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Elena Ambrosini
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
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29
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Diering GH, Numata Y, Fan S, Church J, Numata M. Endosomal acidification by Na+/H+ exchanger NHE5 regulates TrkA cell-surface targeting and NGF-induced PI3K signaling. Mol Biol Cell 2013; 24:3435-48. [PMID: 24006492 PMCID: PMC3814139 DOI: 10.1091/mbc.e12-06-0445] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Revised: 08/21/2013] [Accepted: 08/28/2013] [Indexed: 01/19/2023] Open
Abstract
To facilitate polarized vesicular trafficking and signal transduction, neuronal endosomes have evolved sophisticated mechanisms for pH homeostasis. NHE5 is a member of the Na(+)/H(+) exchanger family and is abundantly expressed in neurons and associates with recycling endosomes. Here we show that NHE5 potently acidifies recycling endosomes in PC12 cells. NHE5 depletion by plasmid-based short hairpin RNA significantly reduces cell surface abundance of TrkA, an effect similar to that observed after treatment with the V-ATPase inhibitor bafilomycin. A series of cell-surface biotinylation experiments suggests that anterograde trafficking of TrkA from recycling endosomes to plasma membrane is the likeliest target affected by NHE5 depletion. NHE5 knockdown reduces phosphorylation of Akt and Erk1/2 and impairs neurite outgrowth in response to nerve growth factor (NGF) treatment. Of interest, although both phosphoinositide 3-kinase-Akt and Erk signaling are activated by NGF-TrkA, NGF-induced Akt-phosphorylation appears to be more sensitively affected by perturbed endosomal pH. Furthermore, NHE5 depletion in rat cortical neurons in primary culture also inhibits neurite formation. These results collectively suggest that endosomal pH modulates trafficking of Trk-family receptor tyrosine kinases, neurotrophin signaling, and possibly neuronal differentiation.
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Affiliation(s)
- Graham H. Diering
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Yuka Numata
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Steven Fan
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - John Church
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Masayuki Numata
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
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30
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Juhász K, Thuenauer R, Spachinger A, Duda E, Horváth I, Vígh L, Sonnleitner A, Balogi Z. Lysosomal rerouting of Hsp70 trafficking as a potential immune activating tool for targeting melanoma. Curr Pharm Des 2013; 19:430-40. [PMID: 22920897 PMCID: PMC3531874 DOI: 10.2174/138161213804143644] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 08/15/2012] [Indexed: 12/17/2022]
Abstract
Tumor specific cell surface localization and release of the stress inducible heat shock protein 70 (Hsp70) stimulate the immune
system against cancer cells. A key immune stimulatory function of tumor-derived Hsp70 has been exemplified with the murine melanoma
cell model, B16 overexpressing exogenous Hsp70. Despite the therapeutic potential mechanism of Hsp70 transport to the surface
and release remained poorly understood. We investigated principles of Hsp70 trafficking in B16 melanoma cells with low and high level
of Hsp70. In cells with low level of Hsp70 apparent trafficking of Hsp70 was mediated by endosomes. Excess Hsp70 triggered a series of
changes such as a switch of Hsp70 trafficking from endosomes to lysosomes and a concomitant accumulation of Hsp70 in lysosomes.
Moreover, lysosomal rerouting resulted in an elevated concentration of surface Hsp70 and enabled active release of Hsp70. In fact, hyperthermia,
a clinically applicable approach triggered immediate active lysosomal release of soluble Hsp70 from cells with excess Hsp70.
Furthermore, excess Hsp70 enabled targeting of internalized surface Hsp70 to lysosomes, allowing in turn heat-induced secretion of surface
Hsp70. Altogether, we show that excess Hsp70 expressed in B16 melanoma cells diverts Hsp70 trafficking from endosomes to
lysosomes, thereby supporting its surface localization and lysosomal release. Controlled excess-induced lysosomal rerouting and secretion
of Hsp70 is proposed as a promising tool to stimulate anti-tumor immunity targeting melanoma.
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Affiliation(s)
- Kata Juhász
- Center for Advanced Bioanalysis GmbH, Gruberstr. 40-42, A-4020 Linz, Austria
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31
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Boissier P, Chen J, Huynh-Do U. EphA2 signaling following endocytosis: role of Tiam1. Traffic 2013; 14:1255-71. [PMID: 24112471 DOI: 10.1111/tra.12123] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 09/18/2013] [Accepted: 09/20/2013] [Indexed: 12/31/2022]
Abstract
Eph receptors and their membrane-bound ligands, the ephrins, represent a complex subfamily of receptor tyrosine kinases (RTKs). Eph/ephrin binding can lead to various and opposite cellular behaviors such as adhesion versus repulsion, or cell migration versus cell-adhesion. Recently, Eph endocytosis has been identified as one of the critical steps responsible for such diversity. Eph receptors, as many RTKs, are rapidly endocytosed following ligand-mediated activation and traffic through endocytic compartments prior to degradation. However, it is becoming obvious that endocytosis controls signaling in many different manners. Here we showed that activated EphA2 are degraded in the lysosomes and that about 35% of internalized receptors are recycled back to the plasma membrane. Our study is also the first to demonstrate that EphA2 retains the capacity to signal in endosomes. In particular, activated EphA2 interacted with the Rho family GEF Tiam1 in endosomes. This association led to Tiam1 activation, which in turn increased Rac1 activity and facilitated Eph/ephrin endocytosis. Disrupting Tiam1 function with RNA interference impaired both ephrinA1-dependent Rac1 activation and ephrinA1-induced EphA2 endocytosis. In summary, our findings shed new light on the regulation of EphA2 endocytosis, intracellular trafficking and signal termination and establish Tiam1 as an important modulator of EphA2 signaling.
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Affiliation(s)
- Pomme Boissier
- Department of Nephrology, Hypertension and Clinical Pharmacology, Inselspital, University of Bern, Bern, 3012, Switzerland
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32
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von Schwarzenberg K, Lajtos T, Simon L, Müller R, Vereb G, Vollmar AM. V-ATPase inhibition overcomes trastuzumab resistance in breast cancer. Mol Oncol 2013; 8:9-19. [PMID: 24055142 DOI: 10.1016/j.molonc.2013.08.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 08/23/2013] [Accepted: 08/26/2013] [Indexed: 12/20/2022] Open
Abstract
The HER2 oncogene targeting drug trastuzumab shows remarkable efficacy in patients overexpressing HER2. However acquired or primary resistance develops in most of the treated patients why alternative treatment strategies are strongly needed. As endosomal sorting and recycling are crucial steps for HER2 activity and the vacuolar H⁺-ATPase (V-ATPase) is an important regulator of endocytotic trafficking, we proposed that targeting V-ATPase opens a new therapeutic strategy against trastuzumab-resistant tumor cells in vitro and in vivo. V-ATPase inhibition with archazolid, a novel inhibitor of myxobacterial origin, results in growth inhibition, apoptosis and impaired HER2 pro-survival signaling of the trastuzumab-resistant cell line JIMT-1. This is accompanied by a decreased expression on the plasma membrane and accumulation of HER2 in the cytosol, where it colocalizes with endosomes, lysosomes and autophagosomes. Importantly, microscopic analysis of JIMT-1 xenograft tumor tissue of archazolid treated mice confirms the defect in HER2-recycling which leads to reduced tumor growth. These results suggest that V-ATPase inhibition by archazolid induces apoptosis and inhibits growth of trastuzumab-resistant tumor cells by retaining HER2 in dysfunctional vesicles of the recycling pathway and consequently abrogates HER2-signaling in vitro as well as in vivo. V-ATPase inhibition is thus suggested as a promising strategy for treatment of trastuzumab-resistant tumors.
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Affiliation(s)
- Karin von Schwarzenberg
- Department of Pharmacy, Pharmaceutical Biology, Ludwig-Maximilians-University Munich, Butenandtstr. 5-13, 81377 Munich, Germany.
| | - Tamás Lajtos
- Department of Biophysics and Cell Biology, University of Debrecen, Egyetem tér 1, 4032 Debrecen, Hungary
| | - Làszló Simon
- Department of Biophysics and Cell Biology, University of Debrecen, Egyetem tér 1, 4032 Debrecen, Hungary
| | - Rolf Müller
- Helmholtz Institute for Pharmaceutical Research Saarland, Helmholtz Centre for Infection Research and Department of Pharmaceutical Biotechnology, Saarland University, PO 151150, 66041 Saarbrücken, Germany
| | - György Vereb
- Department of Biophysics and Cell Biology, University of Debrecen, Egyetem tér 1, 4032 Debrecen, Hungary; MTA Cell Biology and Signaling Research Group, University of Debrecen, Egyetem tér 1, 4032 Debrecen, Hungary
| | - Angelika M Vollmar
- Department of Pharmacy, Pharmaceutical Biology, Ludwig-Maximilians-University Munich, Butenandtstr. 5-13, 81377 Munich, Germany
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Inside job: ligand-receptor pharmacology beneath the plasma membrane. Acta Pharmacol Sin 2013; 34:859-69. [PMID: 23685953 PMCID: PMC3703709 DOI: 10.1038/aps.2013.51] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 04/07/2013] [Indexed: 12/24/2022] Open
Abstract
Most drugs acting on the cell surface receptors are membrane permeable and thus able to engage their target proteins in different subcellular compartments. However, these drugs' effects on cell surface receptors have historically been studied on the plasma membrane alone. Increasing evidence suggests that small molecules may also modulate their targeted receptors through membrane trafficking or organelle-localized signaling inside the cell. These additional modes of interaction have been reported for functionally diverse ligands of GPCRs, ion channels, and transporters. Such intracellular drug-target engagements affect cell surface expression. Concurrent intracellular and cell surface signaling may also increase the complexity and therapeutic opportunities of small molecule modulation. Here we discuss examples of ligand-receptor interactions that are present in both intra- and extracellular sites, and the potential therapeutic opportunities presented by this phenomenon.
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Lawen A, Lane DJR. Mammalian iron homeostasis in health and disease: uptake, storage, transport, and molecular mechanisms of action. Antioxid Redox Signal 2013. [PMID: 23199217 DOI: 10.1089/ars.2011.4271] [Citation(s) in RCA: 155] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Iron is a crucial factor for life. However, it also has the potential to cause the formation of noxious free radicals. These double-edged sword characteristics demand a tight regulation of cellular iron metabolism. In this review, we discuss the various pathways of cellular iron uptake, cellular iron storage, and transport. Recent advances in understanding the reduction and uptake of non-transferrin-bound iron are discussed. We also discuss the recent progress in the understanding of transcriptional and translational regulation by iron. Furthermore, we discuss recent advances in the understanding of the regulation of cellular and systemic iron homeostasis and several key diseases resulting from iron deficiency and overload. We also discuss the knockout mice available for studying iron metabolism and the related human conditions.
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Affiliation(s)
- Alfons Lawen
- Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, Melbourne, Australia.
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35
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Modi S, Nizak C, Surana S, Halder S, Krishnan Y. Two DNA nanomachines map pH changes along intersecting endocytic pathways inside the same cell. NATURE NANOTECHNOLOGY 2013; 8:459-67. [PMID: 23708428 DOI: 10.1038/nnano.2013.92] [Citation(s) in RCA: 254] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 04/22/2013] [Indexed: 05/18/2023]
Abstract
DNA is a versatile scaffold for molecular sensing in living cells, and various cellular applications of DNA nanodevices have been demonstrated. However, the simultaneous use of different DNA nanodevices within the same living cell remains a challenge. Here, we show that two distinct DNA nanomachines can be used simultaneously to map pH gradients along two different but intersecting cellular entry pathways. The two nanomachines, which are molecularly programmed to enter cells via different pathways, can map pH changes within well-defined subcellular environments along both pathways inside the same cell. We applied these nanomachines to probe the pH of early endosomes and the trans-Golgi network, in real time. When delivered either sequentially or simultaneously, both nanomachines localized into and independently captured the pH of the organelles for which they were designed. The successful functioning of DNA nanodevices within living systems has important implications for sensing and therapies in a diverse range of contexts.
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Affiliation(s)
- Souvik Modi
- National Centre for Biological Sciences, TIFR, GKVK, Bellary Road, Bangalore 560065, India
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36
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Rankin CR, Hilgarth RS, Leoni G, Kwon M, Den Beste KA, Parkos CA, Nusrat A. Annexin A2 regulates β1 integrin internalization and intestinal epithelial cell migration. J Biol Chem 2013; 288:15229-39. [PMID: 23558678 DOI: 10.1074/jbc.m112.440909] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The gastrointestinal epithelium functions as an important barrier that separates luminal contents from the underlying tissue compartment and is vital in maintaining mucosal homeostasis. Mucosal wounds in inflammatory disorders compromise the critical epithelial barrier. In response to injury, intestinal epithelial cells (IECs) rapidly migrate to reseal wounds. We have previously observed that a membrane-associated, actin binding protein, annexin A2 (AnxA2), is up-regulated in migrating IECs and plays an important role in promoting wound closure. To identify the mechanisms by which AnxA2 promotes IEC movement and wound closure, we used a loss of function approach. AnxA2-specific shRNA was utilized to generate IECs with stable down-regulation of AnxA2. Loss of AnxA2 inhibited IEC migration while promoting enhanced cell-matrix adhesion. These functional effects were associated with increased levels of β1 integrin protein, which is reported to play an important role in mediating the cell-matrix adhesive properties of epithelial cells. Because cell migration requires dynamic turnover of integrin-based adhesions, we tested whether AnxA2 modulates internalization of cell surface β1 integrin required for forward cell movement. Indeed, pulse-chase biotinylation experiments in IECs lacking AnxA2 demonstrated a significant increase in cell surface β1 integrin that was accompanied by decreased β1 integrin internalization and degradation. These findings support an important role of AnxA2 in controlling dynamics of β1 integrin at the cell surface that in turn is required for the active turnover of cell-matrix associations, cell migration, and wound closure.
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Affiliation(s)
- Carl R Rankin
- Department of Pathology and Laboratory Medicine, Epithelial Pathobiology and Mucosal Inflammation Research Unit, Emory University, Atlanta, Georgia 30306, USA
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37
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Song I, Volynski K, Brenner T, Ushkaryov Y, Walker M, Semyanov A. Different transporter systems regulate extracellular GABA from vesicular and non-vesicular sources. Front Cell Neurosci 2013; 7:23. [PMID: 23494150 PMCID: PMC3595500 DOI: 10.3389/fncel.2013.00023] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 02/25/2013] [Indexed: 11/25/2022] Open
Abstract
Tonic GABA type A (GABAA) conductance is a key factor regulating neuronal excitability and computation in neuronal networks. The magnitude of the tonic GABAA conductance depends on the concentration of ambient GABA originating from vesicular and non-vesicular sources and is tightly regulated by GABA uptake. Here we show that the transport system regulating ambient GABA responsible for tonic GABAA conductances in hippocampal CA1 interneurons depends on its source. In mice, GABA from vesicular sources is regulated by mouse GABA transporter 1 (mGAT1), while that from non-vesicular sources by mouse GABA transporters 3/4 (mGAT3/4). This finding suggests that the two transporter systems do not just provide backup for each other, but regulate distinct signaling pathways. This allows individual tuning of the two signaling systems and indicates that drugs designed to act at specific transporters will have distinct therapeutic actions.
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Affiliation(s)
- Inseon Song
- RIKEN Brain Science Institute Wako-shi, Saitama, Japan
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38
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Ceresa BP. Spatial regulation of epidermal growth factor receptor signaling by endocytosis. Int J Mol Sci 2012; 14:72-87. [PMID: 23344022 DOI: 10.3390/ijms14010072] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 12/10/2012] [Accepted: 12/12/2012] [Indexed: 12/26/2022] Open
Abstract
Signaling by cell surface receptors appears to be relatively straight-forward: ligand binds to the extracellular domain of the receptor and biochemical changes are communicated into the cell. However, this process is more complex than it first seems due to the various mechanisms that regulate signaling. In order to effectively target these receptors for pharmacological purposes, a more complete understanding of how their signaling is regulated is needed. Here, how the endocytic pathway regulates receptor signaling is discussed, using the epidermal growth factor receptor (EGFR) as a model. In particular, the spatial regulation of signaling is examined. Areas of discussion include: how endocytic trafficking affects biology/pathology, varying approaches for studying the relationship between receptor endocytosis and signaling, and developments in how the endocytic pathway controls EGFR:effector communication and EGFR-mediated cell biology.
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Affiliation(s)
- Brian P Ceresa
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, KY 40202, USA.
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Productive entry pathways of human rhinoviruses. Adv Virol 2012; 2012:826301. [PMID: 23227049 PMCID: PMC3513715 DOI: 10.1155/2012/826301] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Accepted: 10/18/2012] [Indexed: 12/20/2022] Open
Abstract
Currently, complete or partial genome sequences of more than 150 human rhinovirus (HRV) isolates are known. Twelve species A use members of the low-density lipoprotein receptor family for cell entry, whereas the remaining HRV-A and all HRV-B bind ICAM-1. HRV-Cs exploit an unknown receptor. At least all A and B type viruses depend on receptor-mediated endocytosis for infection. In HeLa cells, they are internalized mainly by a clathrin- and dynamin-dependent mechanism. Upon uptake into acidic compartments, the icosahedral HRV capsid expands by ~4% and holes open at the 2-fold axes, close to the pseudo-3-fold axes and at the base of the star-shaped dome protruding at the vertices. RNA-protein interactions are broken and new ones are established, the small internal myristoylated capsid protein VP4 is expelled, and amphipathic N-terminal sequences of VP1 become exposed. The now hydrophobic subviral particle attaches to the inner surface of endosomes and transfers its genomic (+) ssRNA into the cytosol. The RNA leaves the virus starting with the poly(A) tail at its 3′-end and passes through a membrane pore contiguous with one of the holes in the capsid wall. Alternatively, the endosome is disrupted and the RNA freely diffuses into the cytoplasm.
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Toxicity mechanisms of amphotericin B and its neutralization by conjugation with arabinogalactan. Antimicrob Agents Chemother 2012; 56:5603-11. [PMID: 22908154 DOI: 10.1128/aac.00612-12] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Amphotericin B (AMB) is an effective antifungal agent. However, its therapeutic use is hampered by its toxicity, mainly due to channel formation across kidney cell membranes and the disruption of postendocytic trafficking. We previously described a safe injectable AMB-arabinogalactan (AG) conjugate with neutralized toxicity. Here we studied the mechanism of the toxicity of free AMB and its neutralization by conjugation with AG. AMB treatment of a kidney cell line modulated the trafficking of three receptors (C-X-C chemokine receptor type 4 [CXCR4], M1 receptor, and human transferrin receptor [hTfnR]) due to an increase in endosomal pH. Similar data were also obtained in yeast but with an increase in vacuolar pH and the perturbation of Hxt2-green fluorescent protein (GFP) trafficking. The conjugation of AMB with AG neutralized all elements of the toxic activity of AMB in mammalian but not in fungal cells. Based on these results, we provide an explanation of how the conjugation of AMB with AG neutralizes its toxicity in mammalian cells and add to the knowledge of the mechanism of action of free AMB in both fungal and mammalian cells.
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Riggs KA, Hasan N, Humphrey D, Raleigh C, Nevitt C, Corbin D, Hu C. Regulation of integrin endocytic recycling and chemotactic cell migration by syntaxin 6 and VAMP3 interaction. J Cell Sci 2012; 125:3827-39. [PMID: 22573826 DOI: 10.1242/jcs.102566] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Integrins are the primary receptors of cells adhering to the extracellular matrix, and play key roles in various cellular processes including migration, proliferation and survival. The expression and distribution of integrins at the cell surface is controlled by endocytosis and recycling. The present study examines the function of syntaxin 6 (STX6), a t-SNARE located in the trans-Golgi network, in integrin trafficking. STX6 is overexpressed in many types of human cancer. We show that depletion of STX6 inhibits chemotactic cell migration and the delivery of the laminin receptor α3β1 integrin to the cell surface, whereas STX6 overexpression stimulates chemotactic cell migration, integrin delivery, and integrin-initiated activation of focal adhesion kinase. These data indicate that STX6 plays a rate-limiting role in cell migration and integrin trafficking. In STX6-depleted cells, α3β1 integrin is accumulated in recycling endosomes that contain the v-SNARE VAMP3. Importantly, we show that STX6 and VAMP3 form a v-/t-SNARE complex, VAMP3 is required in α3β1 integrin delivery to the cell surface, and endocytosed α3β1 integrin traffics to both VAMP3 and STX6 compartments. Collectively, our data suggest a new integrin trafficking pathway in which endocytosed integrins are transported from VAMP3-containing recycling endosomes to STX6-containing trans-Golgi network before being recycled to the plasma membrane.
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Affiliation(s)
- Krista A Riggs
- Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, KY 40202, USA
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42
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Ejlerskov P, Christensen DP, Beyaie D, Burritt JB, Paclet MH, Gorlach A, van Deurs B, Vilhardt F. NADPH oxidase is internalized by clathrin-coated pits and localizes to a Rab27A/B GTPase-regulated secretory compartment in activated macrophages. J Biol Chem 2011; 287:4835-52. [PMID: 22157766 DOI: 10.1074/jbc.m111.293696] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Here, we report that activation of different types of tissue macrophages, including microglia, by lipopolysaccharide (LPS) or GM-CSF stimulation correlates with the quantitative redistribution of NADPH oxidase (cyt b(558)) from the plasma membrane to an intracellular stimulus-responsive storage compartment. Cryo-immunogold labeling of gp91(phox) and CeCl(3) cytochemistry showed the presence of gp91(phox) and oxidant production in numerous small (<100 nm) vesicles. Cell homogenization and sucrose gradient centrifugation in combination with transferrin-HRP/DAB ablation showed that more than half of cyt b(558) is present in fractions devoid of endosomal markers, which is supported by morphological evidence to show that the cyt b(558)-containing compartment is distinct from endosomes or biosynthetic organelles. Streptolysin-O-mediated guanosine 5'-3-O-(thio)triphosphate loading of Ra2 microglia caused exocytosis of a major complement of cyt b(558) under conditions where lysosomes or endosomes were not mobilized. We establish phagocytic particles and soluble mediators ATP, TNFα, and CD40L as physiological inducers of cyt b(558) exocytosis to the cell surface, and by shRNA knockdown, we identify Rab27A/B as positive or negative regulators of vesicular mobilization to the phagosome or the cell surface, respectively. Exocytosis was followed by clathrin-dependent internalization of cyt b(558), which could be blocked by a dominant negative mutant of the clathrin-coated pit-associated protein Eps15. Re-internalized cyt b(558) did not reach lysosomes but associated with recycling endosomes and undefined vesicular elements. In conclusion, cyt b(558) depends on clathrin for internalization, and in activated macrophages NADPH oxidase occupies a Rab27A/B-regulated secretory compartment, which allows rapid agonist-induced redistribution of superoxide production in the cell.
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Affiliation(s)
- Patrick Ejlerskov
- Department of Cellular and Molecular Medicine, Panum Institute, Faculty of Health Sciences, University of Copenhagen, Copenhagen 2200N, Denmark
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43
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Chimote AA, Kuras Z, Conforti L. Disruption of kv1.3 channel forward vesicular trafficking by hypoxia in human T lymphocytes. J Biol Chem 2011; 287:2055-67. [PMID: 22134923 DOI: 10.1074/jbc.m111.274209] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Hypoxia in solid tumors contributes to decreased immunosurveillance via down-regulation of Kv1.3 channels in T lymphocytes and associated T cell function inhibition. However, the mechanisms responsible for Kv1.3 down-regulation are not understood. We hypothesized that chronic hypoxia reduces Kv1.3 surface expression via alterations in membrane trafficking. Chronic hypoxia decreased Kv1.3 surface expression and current density in Jurkat T cells. Inhibition of either protein synthesis or degradation and endocytosis did not prevent this effect. Instead, blockade of clathrin-coated vesicle formation and forward trafficking prevented the Kv1.3 surface expression decrease in hypoxia. Confocal microscopy revealed an increased retention of Kv1.3 in the trans-Golgi during hypoxia. Expression of adaptor protein-1 (AP1), responsible for clathrin-coated vesicle formation at the trans-Golgi, was selectively down-regulated by hypoxia. Furthermore, AP1 down-regulation increased Kv1.3 retention in the trans-Golgi and reduced Kv1.3 currents. Our results indicate that hypoxia disrupts AP1/clathrin-mediated forward trafficking of Kv1.3 from the trans-Golgi to the plasma membrane thus contributing to decreased Kv1.3 surface expression in T lymphocytes.
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Affiliation(s)
- Ameet A Chimote
- Department of Internal Medicine, University of Cincinnati, Cincinnati, Ohio 45267, USA
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44
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Kotowski SJ, Hopf FW, Seif T, Bonci A, von Zastrow M. Endocytosis promotes rapid dopaminergic signaling. Neuron 2011; 71:278-90. [PMID: 21791287 DOI: 10.1016/j.neuron.2011.05.036] [Citation(s) in RCA: 144] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/11/2011] [Indexed: 12/12/2022]
Abstract
D(1) dopamine receptors are primary mediators of dopaminergic signaling in the CNS. These receptors internalize rapidly following agonist-induced activation, but the functional significance of this process is unknown. We investigated D(1) receptor endocytosis and signaling in HEK293 cells and cultured striatal neurons using real-time fluorescence imaging and cAMP biosensor technology. Agonist-induced activation of D(1) receptors promoted endocytosis of receptors with a time course overlapping that of acute cAMP accumulation. Inhibiting receptor endocytosis blunted acute D(1) receptor-mediated signaling in both dissociated cells and striatal slice preparations. Although endocytic inhibition markedly attenuated acute cAMP accumulation, inhibiting the subsequent recycling of receptors had no effect. Further, D(1) receptors localized in close proximity to endomembrane-associated trimeric G protein and adenylyl cyclase immediately after endocytosis. Together, these results suggest a previously unanticipated role of endocytosis, and the early endocytic pathway, in supporting rapid dopaminergic neurotransmission.
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Affiliation(s)
- Sarah J Kotowski
- Department of Psychiatry and Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, CA 94158, USA
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45
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Bacac M, Fusco C, Planche A, Santodomingo J, Demaurex N, Leemann-Zakaryan R, Provero P, Stamenkovic I. Securin and separase modulate membrane traffic by affecting endosomal acidification. Traffic 2011; 12:615-26. [PMID: 21272169 DOI: 10.1111/j.1600-0854.2011.01169.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Securin and separase play a key role in sister chromatid separation during anaphase. However, a growing body of evidence suggests that in addition to regulating chromosome segregation, securin and separase display functions implicated in membrane traffic in Caenorhabditis elegans and Drosophila. Here we show that in mammalian cells both securin and separase associate with membranes and that depletion of either protein causes robust swelling of the trans-Golgi network (TGN) along with the appearance of large endocytic vesicles in the perinuclear region. These changes are accompanied by diminished constitutive protein secretion as well as impaired receptor recycling and degradation. Unexpectedly, cells depleted of securin or separase display defective acidification of early endosomes and increased membrane recruitment of vacuolar (V-) ATPase complexes, mimicking the effect of the specific V-ATPase inhibitor Bafilomycin A1. Taken together, our findings identify a new functional role of securin and separase in the modulation of membrane traffic and protein secretion that implicates regulation of V-ATPase assembly and function.
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Affiliation(s)
- Marina Bacac
- Division of Experimental Pathology, Faculty of Biology and Medicine, Institute of Pathology, CHUV, University of Lausanne, Rue du Bugnon 25, Lausanne CH1011, Switzerland
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O'Reilly MK, Tian H, Paulson JC. CD22 is a recycling receptor that can shuttle cargo between the cell surface and endosomal compartments of B cells. THE JOURNAL OF IMMUNOLOGY 2010; 186:1554-63. [PMID: 21178016 DOI: 10.4049/jimmunol.1003005] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
CD22 is a member of the sialic acid-binding Ig-like lectin (Siglec) family that is known to be a regulator of B cell signaling. Its B cell-specific expression makes it an attractive target for immunotoxin-mediated B cell depletion therapy for the treatment of B cell lymphomas and autoimmune diseases. Although CD22 is well documented to be an endocytic receptor, it is believed that after internalization, it is targeted for degradation. We show in this study that CD22 is instead constitutively recycled to the cell surface. We also find that glycan ligand-based cargo is released from CD22 and accumulates intracellularly as CD22 recycles between the cell surface and endosomal compartments. In contrast, Abs to CD22 do not accumulate but remain bound to CD22 and recycle to the cell surface. The results have implications for development of agents that target CD22 as an endocytic receptor for delivery of cytotoxic cargo to B cells.
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Affiliation(s)
- Mary K O'Reilly
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, CA 92037, USA
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Maeda Y, Kinoshita T. The acidic environment of the Golgi is critical for glycosylation and transport. Methods Enzymol 2010; 480:495-510. [PMID: 20816224 DOI: 10.1016/s0076-6879(10)80022-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2023]
Abstract
Proteins and glycolipids are modified by various modes of glycosylation in the endoplasmic reticulum (ER) and the Golgi apparatus. It is well known that the lumen of the Golgi is acidic and compromising acidification by chemical compounds causes impaired glycosylation and transport of proteins (Axelsson et al., 2001; Chapman and Munro, 1994; Palokangas et al., 1994; Presley et al., 1997; Puri et al., 2002; Reaves and Banting, 1994; Rivinoja et al., 2006; Tartakoff et al., 1978). The mechanisms by which glycosylation and transport are regulated by an acidic pH remain largely unknown. Recent findings that the impaired regulation of an acidic environment may be implicated in the pathology of several diseases emphasize the importance of pH regulation (Jentsch, 2007; Kasper et al., 2005; Kornak et al., 2001; Kornak et al., 2008; Piwon et al., 2000; Stobrawa et al., 2001; Teichgraber et al., 2008). We recently established a mutant cell line in which Golgi acidification was selectively impaired and the raised luminal Golgi pH caused impaired transport and glycosylation of proteins and altered Golgi morphology (Maeda et al., 2008). As alkalinizing compounds nonselectively affect all acidic organelles including lysosomes, endosomes, and the Golgi, the mutant cell is thought to be useful in analyzing how the acidic environment of the Golgi regulates glycosylation. In this chapter, we have introduced how we established mutant cells with impaired Golgi acidification and methods for measuring Golgi pH.
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Affiliation(s)
- Yusuke Maeda
- Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan
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Yu Z, Zhao LX, Jiang CL, Duan Y, Wong L, Carver KC, Schuler LA, Shen B. Bafilomycins produced by an endophytic actinomycete Streptomyces sp. YIM56209. J Antibiot (Tokyo) 2010; 64:159-62. [PMID: 21102599 DOI: 10.1038/ja.2010.147] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Zhiguo Yu
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin-Madison, Madison, WI 53705-2222, USA
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Abstract
Targeted nanoparticles have the potential to improve drug delivery efficiencies by more than two orders of magnitude, from the ~ 0.1% which is common today. Most pharmacologically agents on the market today are small drug molecules, which diffuse across the body’s blood-tissue barriers and distribute not only into the lesion, but into almost all organs. Drug actions in the non-lesion organs are an inescapable part of the drug delivery principle, causing “side-effects” which limit the maximally tolerable doses and result in inadequate therapy of many lesions. Nanoparticles only cross barriers by design, so side-effects are not built into their mode of operation. Delivery rates of almost 90% have been reported. This review examines the significance of these statements and checks how far they need qualification. What type of targeting is required? Is a single targeting sufficient? What new types of clinical challenge, such as immunogenicity, might attend the use of targeted nanoparticles?
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50
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Anzinger JJ, Chang J, Xu Q, Buono C, Li Y, Leyva FJ, Park BC, Greene LE, Kruth HS. Native low-density lipoprotein uptake by macrophage colony-stimulating factor-differentiated human macrophages is mediated by macropinocytosis and micropinocytosis. Arterioscler Thromb Vasc Biol 2010; 30:2022-31. [PMID: 20634472 DOI: 10.1161/atvbaha.110.210849] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVE To examine the pinocytotic pathways mediating native low-density lipoprotein (LDL) uptake by human macrophage colony-stimulating factor-differentiated macrophages (the predominant macrophage phenotype in human atherosclerotic plaques). METHODS AND RESULTS We identified the kinase inhibitor SU6656 and the Rho GTPase inhibitor toxin B as inhibitors of macrophage fluid-phase pinocytosis of LDL. Assessment of macropinocytosis by time-lapse microscopy revealed that both drugs almost completely inhibited macropinocytosis, although LDL uptake and cholesterol accumulation by macrophages were only partially inhibited (approximately 40%) by these agents. Therefore, we investigated the role of micropinocytosis in mediating LDL uptake in macrophages and identified bafilomycin A1 as an additional partial inhibitor (approximately 40%) of macrophage LDL uptake that targeted micropinocytosis. When macrophages were incubated with both bafilomycin A1 and SU6656, inhibition of LDL uptake was additive (reaching 80%), showing that these inhibitors target different pathways. Microscopic analysis of fluid-phase uptake pathways in these macrophages confirmed that LDL uptake occurs through both macropinocytosis and micropinocytosis. CONCLUSIONS Our findings show that human macrophage colony-stimulating factor-differentiated macrophages take up native LDL by macropinocytosis and micropinocytosis, underscoring the importance of both pathways in mediating LDL uptake by these cells.
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Affiliation(s)
- Joshua J Anzinger
- Section of Experimental Atherosclerosis, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Md 20892-1422, USA
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