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Cassandri M, Porrazzo A, Pomella S, Noce B, Zwergel C, Aiello FA, Vulcano F, Milazzo L, Camero S, Pajalunga D, Spada M, Manzi V, Gravina GL, Codenotti S, Piccione M, Tomaciello M, Signore M, Barillari G, Marchese C, Fanzani A, De Angelis B, Quintarelli C, Vakoc CR, Chen EY, Megiorni F, Locatelli F, Valente S, Mai A, Rota R, Marampon F. HDAC3 genetic and pharmacologic inhibition radiosensitizes fusion positive rhabdomyosarcoma by promoting DNA double-strand breaks. Cell Death Discov 2024; 10:351. [PMID: 39107280 PMCID: PMC11303816 DOI: 10.1038/s41420-024-02115-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 07/16/2024] [Accepted: 07/29/2024] [Indexed: 08/09/2024] Open
Abstract
Radiotherapy (RT) plays a critical role in the management of rhabdomyosarcoma (RMS), the prevalent soft tissue sarcoma in childhood. The high risk PAX3-FOXO1 fusion-positive subtype (FP-RMS) is often resistant to RT. We have recently demonstrated that inhibition of class-I histone deacetylases (HDACs) radiosensitizes FP-RMS both in vitro and in vivo. However, HDAC inhibitors exhibited limited success on solid tumors in human clinical trials, at least in part due to the presence of off-target effects. Hence, identifying specific HDAC isoforms that can be targeted to radiosensitize FP-RMS is imperative. We, here, found that only HDAC3 silencing, among all class-I HDACs screened by siRNA, radiosensitizes FP-RMS cells by inhibiting colony formation. Thus, we dissected the effects of HDAC3 depletion using CRISPR/Cas9-dependent HDAC3 knock-out (KO) in FP-RMS cells, which resulted in Endoplasmatic Reticulum Stress activation, ERK inactivation, PARP1- and caspase-dependent apoptosis and reduced stemness when combined with irradiation compared to single treatments. HDAC3 loss-of-function increased DNA damage in irradiated cells augmenting H2AX phosphorylation and DNA double-strand breaks (DSBs) and counteracting irradiation-dependent activation of ATM and DNA-Pkcs as well as Rad51 protein induction. Moreover, HDAC3 depletion hampers FP-RMS tumor growth in vivo and maximally inhibits the growth of irradiated tumors compared to single approaches. We, then, developed a new HDAC3 inhibitor, MC4448, which showed specific cell anti-tumor effects and mirrors the radiosensitizing effects of HDAC3 depletion in vitro synergizing with ERKs inhibition. Overall, our findings dissect the pro-survival role of HDAC3 in FP-RMS and suggest HDAC3 genetic or pharmacologic inhibition as a new promising strategy to overcome radioresistance in this tumor.
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Affiliation(s)
- Matteo Cassandri
- Department of Radiotherapy, Policlinico Umberto I, "Sapienza" University of Rome, Rome, Italy
- Department of Hematology/Oncology, Cell and Gene Therapy, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Antonella Porrazzo
- Department of Radiotherapy, Policlinico Umberto I, "Sapienza" University of Rome, Rome, Italy
- Department of Hematology/Oncology, Cell and Gene Therapy, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Silvia Pomella
- Department of Hematology/Oncology, Cell and Gene Therapy, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
- Department of Clinical Sciences and Translational Medicine, University of Rome Tor Vergata, Rome, Italy
| | - Beatrice Noce
- Department of Drug Chemistry and Technologies, "Sapienza" University of Rome, Rome, Italy
| | - Clemens Zwergel
- Department of Drug Chemistry and Technologies, "Sapienza" University of Rome, Rome, Italy
| | - Francesca Antonella Aiello
- Department of Hematology/Oncology, Cell and Gene Therapy, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Francesca Vulcano
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy
| | - Luisa Milazzo
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy
| | - Simona Camero
- Department of Life Sciences, Health and Health Professions, Link Campus University, Rome, Italy
- Department of Experimental Medicine, "Sapienza" University of Rome, Rome, Italy
| | - Deborah Pajalunga
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy
| | - Massimo Spada
- Center of Animal Research and Welfare, Istituto Superiore di Sanità, Rome, Italy
| | - Valeria Manzi
- Department of Radiotherapy, Policlinico Umberto I, "Sapienza" University of Rome, Rome, Italy
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy
| | - Giovanni Luca Gravina
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Silvia Codenotti
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Michela Piccione
- Confocal Microscopy Core Facility, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - Miriam Tomaciello
- Department of Radiotherapy, Policlinico Umberto I, "Sapienza" University of Rome, Rome, Italy
| | - Michele Signore
- RPPA Unit, Proteomics Area, Core Facilities, Istituto Superiore di Sanità, Rome, Italy
| | - Giovanni Barillari
- Department of Clinical Sciences and Translational Medicine, University of Rome Tor Vergata, Rome, Italy
| | - Cinzia Marchese
- Department of Experimental Medicine, "Sapienza" University of Rome, Rome, Italy
| | - Alessandro Fanzani
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Biagio De Angelis
- Department of Hematology/Oncology, Cell and Gene Therapy, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Concetta Quintarelli
- Department of Hematology/Oncology, Cell and Gene Therapy, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | | | - Eleanor Y Chen
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
| | - Francesca Megiorni
- Department of Experimental Medicine, "Sapienza" University of Rome, Rome, Italy
| | - Franco Locatelli
- Department of Hematology/Oncology, Cell and Gene Therapy, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
- Department of Life Sciences and Public Health, Catholic University of the Sacred Heart, Rome, Italy
| | - Sergio Valente
- Department of Drug Chemistry and Technologies, "Sapienza" University of Rome, Rome, Italy
| | - Antonello Mai
- Department of Drug Chemistry and Technologies, "Sapienza" University of Rome, Rome, Italy
- Pasteur Institute, Cenci-Bolognetti Foundation, "Sapienza" University of Rome, Rome, Italy
| | - Rossella Rota
- Department of Hematology/Oncology, Cell and Gene Therapy, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Francesco Marampon
- Department of Radiotherapy, Policlinico Umberto I, "Sapienza" University of Rome, Rome, Italy.
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2
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Feizy N, Leuchtenberg SF, Steiner C, Würtz B, Fliegner L, Huber A. In vivo identification of Drosophila rhodopsin interaction partners by biotin proximity labeling. Sci Rep 2024; 14:1986. [PMID: 38263196 PMCID: PMC10805788 DOI: 10.1038/s41598-024-52041-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 01/12/2024] [Indexed: 01/25/2024] Open
Abstract
Proteins exert their function through protein-protein interactions. In Drosophila, G protein-coupled receptors like rhodopsin (Rh1) interact with a G protein to activate visual signal transduction and with arrestins to terminate activation. Also, membrane proteins like Rh1 engage in protein-protein interactions during folding within the endoplasmic reticulum, during their vesicular transport and upon removal from the cell surface and degradation. Here, we expressed a Rh1-TurboID fusion protein (Rh1::TbID) in Drosophila photoreceptors to identify in vivo Rh1 interaction partners by biotin proximity labeling. We show that Rh1::TbID forms a functional rhodopsin that mediates biotinylation of arrestin 2 in conditions where arrestin 2 interacts with rhodopsin. We also observed biotinylation of Rh1::TbID and native Rh1 as well as of most visual signal transduction proteins. These findings indicate that the signaling components in the rhabdomere approach rhodopsin closely, within a range of ca. 10 nm. Furthermore, we have detected proteins engaged in the maturation of rhodopsin and elements responsible for the trafficking of membrane proteins, resembling potential interaction partners of Rh1. Among these are chaperons of the endoplasmic reticulum, proteins involved in Clathrin-mediated endocytosis as well as previously unnoticed contributors to rhodopsin transportation, such as Rab32, Vap33, or PIP82.
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Affiliation(s)
- Nilofar Feizy
- Department of Biochemistry, Institute of Biology, University of Hohenheim, Stuttgart, Germany
| | | | - Christine Steiner
- Department of Biochemistry, Institute of Biology, University of Hohenheim, Stuttgart, Germany
| | - Berit Würtz
- Mass Spectrometry Unit, Core Facility Hohenheim, University of Hohenheim, Stuttgart, Germany
| | - Leo Fliegner
- Department of Biochemistry, Institute of Biology, University of Hohenheim, Stuttgart, Germany
| | - Armin Huber
- Department of Biochemistry, Institute of Biology, University of Hohenheim, Stuttgart, Germany.
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3
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Gaspar CJ, Gomes T, Martins JC, Melo MN, Adrain C, Cordeiro TN, Domingos PM. Xport-A functions as a chaperone by stabilizing the first five transmembrane domains of rhodopsin-1. iScience 2023; 26:108309. [PMID: 38025784 PMCID: PMC10663829 DOI: 10.1016/j.isci.2023.108309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 04/21/2023] [Accepted: 10/20/2023] [Indexed: 12/01/2023] Open
Abstract
Rhodopsin-1 (Rh1), the main photosensitive protein of Drosophila, is a seven-transmembrane domain protein, which is inserted co-translationally in the endoplasmic reticulum (ER) membrane. Biogenesis of Rh1 occurs in the ER, where various chaperones interact with Rh1 to aid in its folding and subsequent transport from the ER to the rhabdomere, the light-sensing organelle of the photoreceptors. Xport-A has been proposed as a chaperone/transport factor for Rh1, but the exact molecular mechanism for Xport-A activity upon Rh1 is unknown. Here, we propose a model where Xport-A functions as a chaperone during the biogenesis of Rh1 in the ER by stabilizing the first five transmembrane domains (TMDs) of Rh1.
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Affiliation(s)
- Catarina J. Gaspar
- Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa (ITQB-NOVA), Av. da República, 2780-157 Oeiras, Portugal
- Membrane Traffic Lab, Instituto Gulbenkian de Ciência (IGC), 2780-156 Oeiras, Portugal
| | - Tiago Gomes
- Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa (ITQB-NOVA), Av. da República, 2780-157 Oeiras, Portugal
| | - Joana C. Martins
- Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa (ITQB-NOVA), Av. da República, 2780-157 Oeiras, Portugal
| | - Manuel N. Melo
- Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa (ITQB-NOVA), Av. da República, 2780-157 Oeiras, Portugal
| | - Colin Adrain
- Membrane Traffic Lab, Instituto Gulbenkian de Ciência (IGC), 2780-156 Oeiras, Portugal
- Patrick G Johnston Centre for Cancer Research, Queen’s University Belfast, 97 Lisburn Road, BT9 7AE Belfast, UK
| | - Tiago N. Cordeiro
- Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa (ITQB-NOVA), Av. da República, 2780-157 Oeiras, Portugal
| | - Pedro M. Domingos
- Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa (ITQB-NOVA), Av. da República, 2780-157 Oeiras, Portugal
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Lüningschrör P, Andreska T, Veh A, Wolf D, Giridhar NJ, Moradi M, Denzel A, Sendtner M. Calnexin controls TrkB cell surface transport and ER-phagy in mouse cerebral cortex development. Dev Cell 2023; 58:1733-1747.e6. [PMID: 37506696 DOI: 10.1016/j.devcel.2023.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 05/23/2023] [Accepted: 07/05/2023] [Indexed: 07/30/2023]
Abstract
Transactivation of Tropomyosin receptor kinase B (TrkB) by EGF leads to cell surface transport of TrkB, promoting its signaling responsiveness to brain-derived neurotrophic factor (BDNF), a critical process for proper cortical plate development. However, the mechanisms that regulate the transport of TrkB to the cell surface are not fully understood. Here, we identified Calnexin as a regulator for targeting TrkB either to the cell surface or toward autophagosomal processing. Calnexin-deficient mouse embryos show impaired cortical plate formation and elevated levels of transactivated TrkB. In Calnexin-depleted mouse neuronal precursor cells, we detected an impaired cell surface transport of TrkB in response to EGF and an impaired delivery to autophagosomes. Mechanistically, we show that Calnexin facilitates the interaction of TrkB with the ER-phagy receptor Fam134b, thereby targeting TrkB to ER-phagy. This mechanism appears as a critical process for fine-tuning the sensitivity of neurons to BDNF.
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Affiliation(s)
- Patrick Lüningschrör
- Institute of Clinical Neurobiology, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany
| | - Thomas Andreska
- Institute of Clinical Neurobiology, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany
| | - Alexander Veh
- Institute of Clinical Neurobiology, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany
| | - Daniel Wolf
- Institute of Clinical Neurobiology, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany
| | - Neha Jadhav Giridhar
- Institute of Clinical Neurobiology, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany
| | - Mehri Moradi
- Institute of Clinical Neurobiology, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany
| | - Angela Denzel
- Imperial Cancer Research Fund now Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Michael Sendtner
- Institute of Clinical Neurobiology, University Hospital Würzburg, Versbacher Str. 5, 97078 Würzburg, Germany.
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5
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Calnexin, More Than Just a Molecular Chaperone. Cells 2023; 12:cells12030403. [PMID: 36766745 PMCID: PMC9913998 DOI: 10.3390/cells12030403] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 01/17/2023] [Accepted: 01/17/2023] [Indexed: 01/26/2023] Open
Abstract
Calnexin is a type I integral endoplasmic reticulum (ER) membrane protein with an N-terminal domain that resides in the lumen of the ER and a C-terminal domain that extends into the cytosol. Calnexin is commonly referred to as a molecular chaperone involved in the folding and quality control of membrane-associated and secreted proteins, a function that is attributed to its ER- localized domain with a structure that bears a strong resemblance to another luminal ER chaperone and Ca2+-binding protein known as calreticulin. Studies have discovered that the cytosolic C-terminal domain of calnexin undergoes distinct post-translational modifications and interacts with a variety of proteins. Here, we discuss recent findings and hypothesize that the post-translational modifications of the calnexin C-terminal domain and its interaction with specific cytosolic proteins play a role in coordinating ER functions with events taking place in the cytosol and other cellular compartments.
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6
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Wei W, Lu H, Dai W, Zheng X, Dong H. Multiplexed Organelles Portrait Barcodes for Subcellular MicroRNA Array Detection in Living Cells. ACS NANO 2022; 16:20329-20339. [PMID: 36410732 DOI: 10.1021/acsnano.2c06252] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Multiplexed profiling of microRNAs' subcellular expression and distribution is essential to understand their spatiotemporal function information, but it remains a crucial challenge. Herein, we report an encoding approach that leverages combinational fluorescent dye barcodes, organelle targeting elements, and an independent quantification signal, termed Multiplexed Organelles Portrait Barcodes (MOPB), for high-throughput profiling of miRNAs from organelles. The MOPB barcodes consist of heterochromatic fluorescent dye-loaded shell-core mesoporous silica nanoparticles modified with organelle targeting peptides and molecular beacon detection probes. Using mitochondria and endoplasmic reticulum as models, we encoded four Cy3/AMCA ER-MOPB and four Cy5/AMCA Mito-MOPB by varying the Cy3 and Cy5 intensity for distinguishing eight organelles' miRNAs. Significantly, the MOPB strategy successfully and accurately profiled eight subcellular organelle miRNAs' alterations in the drug-induced Ca2+ homeostasis breakdown. The approach should allow more widespread application of subcellular miRNAs and multiplexed subcellular protein biomarkers' monitoring for drug discovery, cellular metabolism, signaling transduction, and gene expression regulation readout.
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Affiliation(s)
- Wei Wei
- Marshall Laboratory of Biomedical Engineering, Research Center for Biosensor and Nanotheranostic, School of Biomedical Engineering, Shenzhen University, 3688 Nanhai Road, Shenzhen, Guangdong518060, China
- Beijing Key Laboratory for Bioengineering and Sensing Technology, School of Chemistry and Bioengineering, University of Science and Technology Beijing30 Xueyuan Road, 100083, Beijing, China
| | - Huiting Lu
- Department of Chemistry, School of Chemistry and Bioengineering, University of Science and Technology Beijing, 30 Xueyuan Road, Beijing100083, China
| | - Wenhao Dai
- Beijing Key Laboratory for Bioengineering and Sensing Technology, School of Chemistry and Bioengineering, University of Science and Technology Beijing30 Xueyuan Road, 100083, Beijing, China
| | - Xiaonan Zheng
- Beijing Key Laboratory for Bioengineering and Sensing Technology, School of Chemistry and Bioengineering, University of Science and Technology Beijing30 Xueyuan Road, 100083, Beijing, China
| | - Haifeng Dong
- Marshall Laboratory of Biomedical Engineering, Research Center for Biosensor and Nanotheranostic, School of Biomedical Engineering, Shenzhen University, 3688 Nanhai Road, Shenzhen, Guangdong518060, China
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7
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Bloemeke N, Meighen‐Berger K, Hitzenberger M, Bach NC, Parr M, Coelho JPL, Frishman D, Zacharias M, Sieber SA, Feige MJ. Intramembrane client recognition potentiates the chaperone functions of calnexin. EMBO J 2022; 41:e110959. [PMID: 36314723 PMCID: PMC9753464 DOI: 10.15252/embj.2022110959] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 10/11/2022] [Accepted: 10/13/2022] [Indexed: 11/06/2022] Open
Abstract
One-third of the human proteome is comprised of membrane proteins, which are particularly vulnerable to misfolding and often require folding assistance by molecular chaperones. Calnexin (CNX), which engages client proteins via its sugar-binding lectin domain, is one of the most abundant ER chaperones, and plays an important role in membrane protein biogenesis. Based on mass spectrometric analyses, we here show that calnexin interacts with a large number of nonglycosylated membrane proteins, indicative of additional nonlectin binding modes. We find that calnexin preferentially bind misfolded membrane proteins and that it uses its single transmembrane domain (TMD) for client recognition. Combining experimental and computational approaches, we systematically dissect signatures for intramembrane client recognition by calnexin, and identify sequence motifs within the calnexin TMD region that mediate client binding. Building on this, we show that intramembrane client binding potentiates the chaperone functions of calnexin. Together, these data reveal a widespread role of calnexin client recognition in the lipid bilayer, which synergizes with its established lectin-based substrate binding. Molecular chaperones thus can combine different interaction modes to support the biogenesis of the diverse eukaryotic membrane proteome.
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Affiliation(s)
- Nicolas Bloemeke
- Department of Bioscience, Center for Functional Protein Assemblies (CPA), TUM School of Natural SciencesTechnical University of MunichGarchingGermany
| | - Kevin Meighen‐Berger
- Department of Bioscience, Center for Functional Protein Assemblies (CPA), TUM School of Natural SciencesTechnical University of MunichGarchingGermany
| | - Manuel Hitzenberger
- Department of Bioscience, Center for Functional Protein Assemblies (CPA), TUM School of Natural SciencesTechnical University of MunichGarchingGermany
| | - Nina C Bach
- Department of Bioscience, Center for Functional Protein Assemblies (CPA), TUM School of Natural SciencesTechnical University of MunichGarchingGermany
| | - Marina Parr
- Department of Bioinformatics, TUM School of Life SciencesTechnical University of MunichFreisingGermany
| | - Joao PL Coelho
- Department of Bioscience, Center for Functional Protein Assemblies (CPA), TUM School of Natural SciencesTechnical University of MunichGarchingGermany
| | - Dmitrij Frishman
- Department of Bioinformatics, TUM School of Life SciencesTechnical University of MunichFreisingGermany
| | - Martin Zacharias
- Department of Bioscience, Center for Functional Protein Assemblies (CPA), TUM School of Natural SciencesTechnical University of MunichGarchingGermany
| | - Stephan A Sieber
- Department of Bioscience, Center for Functional Protein Assemblies (CPA), TUM School of Natural SciencesTechnical University of MunichGarchingGermany
| | - Matthias J Feige
- Department of Bioscience, Center for Functional Protein Assemblies (CPA), TUM School of Natural SciencesTechnical University of MunichGarchingGermany
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8
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Vitamin A Deficiency Alters the Phototransduction Machinery and Distinct Non-Vision-Specific Pathways in the Drosophila Eye Proteome. Biomolecules 2022; 12:biom12081083. [PMID: 36008977 PMCID: PMC9405971 DOI: 10.3390/biom12081083] [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: 07/14/2022] [Revised: 08/01/2022] [Accepted: 08/03/2022] [Indexed: 11/25/2022] Open
Abstract
The requirement of vitamin A for the synthesis of the visual chromophore and the light-sensing pigments has been studied in vertebrate and invertebrate model organisms. To identify the molecular mechanisms that orchestrate the ocular response to vitamin A deprivation, we took advantage of the fact that Drosophila melanogaster predominantly requires vitamin A for vision, but not for development or survival. We analyzed the impacts of vitamin A deficiency on the morphology, the lipidome, and the proteome of the Drosophila eye. We found that chronic vitamin A deprivation damaged the light-sensing compartments and caused a dramatic loss of visual pigments, but also decreased the molar abundance of most phototransduction proteins that amplify and transduce the visual signal. Unexpectedly, vitamin A deficiency also decreased the abundances of specific subunits of mitochondrial TCA cycle and respiratory chain components but increased the levels of cuticle- and lens-related proteins. In contrast, we found no apparent effects of vitamin A deficiency on the ocular lipidome. In summary, chronic vitamin A deficiency decreases the levels of most components of the visual signaling pathway, but also affects molecular pathways that are not vision-specific and whose mechanistic connection to vitamin A remains to be elucidated.
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9
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Ulloa-Aguirre A, Zariñán T, Gutiérrez-Sagal R, Tao YX. Targeting trafficking as a therapeutic avenue for misfolded GPCRs leading to endocrine diseases. Front Endocrinol (Lausanne) 2022; 13:934685. [PMID: 36093106 PMCID: PMC9452723 DOI: 10.3389/fendo.2022.934685] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 07/13/2022] [Indexed: 02/05/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are plasma membrane proteins associated with an array of functions. Mutations in these receptors lead to a number of genetic diseases, including diseases involving the endocrine system. A particular subset of loss-of-function mutant GPCRs are misfolded receptors unable to traffic to their site of function (i.e. the cell surface plasma membrane). Endocrine disorders in humans caused by GPCR misfolding include, among others, hypo- and hyper-gonadotropic hypogonadism, morbid obesity, familial hypocalciuric hypercalcemia and neonatal severe hyperparathyroidism, X-linked nephrogenic diabetes insipidus, congenital hypothyroidism, and familial glucocorticoid resistance. Several in vitro and in vivo experimental approaches have been employed to restore function of some misfolded GPCRs linked to endocrine disfunction. The most promising approach is by employing pharmacological chaperones or pharmacoperones, which assist abnormally and incompletely folded proteins to refold correctly and adopt a more stable configuration to pass the scrutiny of the cell's quality control system, thereby correcting misrouting. This review covers the most important aspects that regulate folding and traffic of newly synthesized proteins, as well as the experimental approaches targeted to overcome protein misfolding, with special focus on GPCRs involved in endocrine diseases.
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Affiliation(s)
- Alfredo Ulloa-Aguirre
- Red de Apoyo a la Investigación (RAI), National University of Mexico and Instituto Nacional de Ciencias Médicas y Nutrición SZ, Mexico City, Mexico
- *Correspondence: Alfredo Ulloa-Aguirre,
| | - Teresa Zariñán
- Red de Apoyo a la Investigación (RAI), National University of Mexico and Instituto Nacional de Ciencias Médicas y Nutrición SZ, Mexico City, Mexico
| | - Rubén Gutiérrez-Sagal
- Red de Apoyo a la Investigación (RAI), National University of Mexico and Instituto Nacional de Ciencias Médicas y Nutrición SZ, Mexico City, Mexico
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology & Pharmacology, Auburn University College of Veterinary Medicine, Auburn, AL, United States
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10
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Dewett D, Labaf M, Lam-Kamath K, Zarringhalam K, Rister J. Vitamin A deficiency affects gene expression in the Drosophila melanogaster head. G3 (BETHESDA, MD.) 2021; 11:jkab297. [PMID: 34849795 PMCID: PMC8527478 DOI: 10.1093/g3journal/jkab297] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 08/13/2021] [Indexed: 12/13/2022]
Abstract
Insufficient dietary intake of vitamin A causes various human diseases. For instance, chronic vitamin A deprivation causes blindness, slow growth, impaired immunity, and an increased risk of mortality in children. In contrast to these diverse effects of vitamin A deficiency (VAD) in mammals, chronic VAD in flies neither causes obvious developmental defects nor lethality. As in mammals, VAD in flies severely affects the visual system: it impairs the synthesis of the retinal chromophore, disrupts the formation of the visual pigments (Rhodopsins), and damages the photoreceptors. However, the molecular mechanisms that respond to VAD remain poorly understood. To identify genes and signaling pathways that are affected by VAD, we performed RNA-sequencing and differential gene expression analysis in Drosophila melanogaster. We found an upregulation of genes that are essential for the synthesis of the retinal chromophore, specific aminoacyl-tRNA synthetases, and major nutrient reservoir proteins. We also discovered that VAD affects several genes that are required for the termination of the light response: for instance, we found a downregulation of both arrestin genes that are essential for the inactivation of Rhodopsin. A comparison of the VAD-responsive genes with previously identified blue light stress-responsive genes revealed that the two types of environmental stress trigger largely nonoverlapping transcriptome responses. Yet, both stresses increase the expression of seven genes with poorly understood functions. Taken together, our transcriptome analysis offers insights into the molecular mechanisms that respond to environmental stresses.
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Affiliation(s)
- Deepshe Dewett
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA
| | - Maryam Labaf
- Department of Mathematics, University of Massachusetts Boston, Boston, MA 02125, USA
| | - Khanh Lam-Kamath
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA
| | - Kourosh Zarringhalam
- Department of Mathematics, University of Massachusetts Boston, Boston, MA 02125, USA
| | - Jens Rister
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA
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11
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Huang HW, Ryoo HD. Drosophila fabp is required for light-dependent Rhodopsin-1 clearance and photoreceptor survival. PLoS Genet 2021; 17:e1009551. [PMID: 34714826 PMCID: PMC8580249 DOI: 10.1371/journal.pgen.1009551] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 11/10/2021] [Accepted: 10/20/2021] [Indexed: 12/30/2022] Open
Abstract
Rhodopsins are light-detecting proteins coupled with retinal chromophores essential for visual function. Coincidentally, dysfunctional Rhodopsin homeostasis underlies retinal degeneration in humans and model organisms. Drosophila ninaEG69D mutant is one such example, where the encoded Rh1 protein imposes endoplasmic reticulum (ER) stress and causes light-dependent retinal degeneration. The underlying reason for such light-dependency remains unknown. Here, we report that Drosophila fatty acid binding protein (fabp) is a gene induced in ninaEG69D/+ photoreceptors, and regulates light-dependent Rhodopsin-1 (Rh1) protein clearance and photoreceptor survival. Specifically, our photoreceptor-specific gene expression profiling study in ninaEG69D/+ flies revealed increased expression of fabp together with other genes that control light-dependent Rh1 protein degradation. fabp induction in ninaEG69D photoreceptors required vitamin A and its transporter genes. In flies reared under light, loss of fabp caused an accumulation of Rh1 proteins in cytoplasmic vesicles. The increase in Rh1 levels under these conditions was dependent on Arrestin2 that mediates feedback inhibition of light-activated Rh1. fabp mutants exhibited light-dependent retinal degeneration, a phenotype also found in other mutants that block light-induced Rh1 degradation. These observations reveal a previously unrecognized link between light-dependent Rh1 proteostasis and the ER-stress imposing ninaEG69D mutant that cause retinal degeneration.
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Affiliation(s)
- Huai-Wei Huang
- Department of Cell Biology NYU Grossman School of Medicine New York, New York, United States of America
| | - Hyung Don Ryoo
- Department of Cell Biology NYU Grossman School of Medicine New York, New York, United States of America
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12
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Chen P, De Schutter K, Van Damme EJM, Smagghe G. Can Plant Lectins Help to Elucidate Insect Lectin-Mediated Immune Response? INSECTS 2021; 12:insects12060497. [PMID: 34071763 PMCID: PMC8226959 DOI: 10.3390/insects12060497] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 05/23/2021] [Accepted: 05/25/2021] [Indexed: 12/25/2022]
Abstract
Simple Summary Lectins are proteins that can recognize and selectively bind specific sugar structures. These proteins are present in all kingdoms of life, including plants, animals, fungi and microorganisms and play a role in a broad range of processes. The interactions between lectins and their target carbohydrates play a primordial role in plant and animal immune systems. Despite being the largest and most diverse taxa on earth, the study of lectins and their functions in insects is lagging behind. To study the role of insect lectins in the immune response, plant lectins could provide an interesting tool. Plant lectins have been well characterized and many of them possess immunomodulatory properties in vertebrate cells. The increasing knowledge on the immunomodulatory effects of plant lectins could complement the missing knowledge on the endogenous insect lectins and contribute to understanding the processes and mechanisms by which lectins participate in insect immunity. This review summarizes existing studies of immune responses stimulated by endogenous or exogenous lectins. Abstract Lectins are carbohydrate-binding proteins that recognize and selectively bind to specific sugar structures. This group of proteins is widespread in plants, animals, and microorganisms, and exerts a broad range of functions. Many plant lectins were identified as exogenous stimuli of vertebrate immunity. Despite being the largest and most diverse taxon on earth, the study of lectins and their functions in insects is lagging behind. In insects, research on lectins and their biological importance has mainly focused on the C-type lectin (CTL) family, limiting our global understanding of the function of insect lectins and their role in insect immunity. In contrast, plant lectins have been well characterized and the immunomodulatory effects of several plant lectins have been documented extensively in vertebrates. This information could complement the missing knowledge on endogenous insect lectins and contribute to understanding of the processes and mechanisms by which lectins participate in insect immunity. This review summarizes existing studies of immune responses stimulated by endogenous or exogenous lectins. Understanding how lectins modulate insect immune responses can provide insight which, in turn, can help to elaborate novel ideas applicable for the protection of beneficial insects and the development of novel pest control strategies.
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Affiliation(s)
- Pengyu Chen
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, 9000 Ghent, Belgium; (P.C.); (K.D.S.)
- Department of Biotechnology, Faculty of Bioscience Engineering, Ghent University, 9000 Ghent, Belgium;
| | - Kristof De Schutter
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, 9000 Ghent, Belgium; (P.C.); (K.D.S.)
| | - Els J. M. Van Damme
- Department of Biotechnology, Faculty of Bioscience Engineering, Ghent University, 9000 Ghent, Belgium;
| | - Guy Smagghe
- Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, 9000 Ghent, Belgium; (P.C.); (K.D.S.)
- Correspondence:
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13
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Doğan C, Hänniger S, Heckel DG, Coutu C, Hegedus DD, Crubaugh L, Groves RL, Bayram Ş, Toprak U. Two calcium-binding chaperones from the fat body of the Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae) involved in diapause. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2021; 106:e21755. [PMID: 33118236 DOI: 10.1002/arch.21755] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/13/2020] [Accepted: 10/19/2020] [Indexed: 06/11/2023]
Abstract
Molecular chaperones are crucial for the correct folding of newly synthesized polypeptides, in particular, under stress conditions. Various studies have revealed the involvement of molecular chaperones, such as heat shock proteins, in diapause maintenance and starvation; however, the role of other chaperones in diapause and starvation relatively is unknown. In the current study, we identified two lectin-type chaperones with calcium affinity, a calreticulin (LdCrT) and a calnexin (LdCnX), that were present in the fat body of the Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae) during diapause. Both proteins possessed an N-globular domain, a P-arm domain, and a highly charged C-terminal domain, while an additional transmembrane domain was present in LdCnX. Phylogenetic analysis revealed distinction at the order level. Both genes were expressed in multiple tissues in larval and adult stages, and constitutively throughout development, though a starvation response was detected only for LdCrT. In females, diapause-related expression analysis in the whole body revealed an upregulation of both genes by post-diapause, but a downregulation by diapause only for LdCrT. By contrast, males revealed no alteration in their diapause-related expression pattern in the entire body for both genes. Fat body-specific expression analysis of both genes in relation to diapause revealed the same expression pattern with no alteration in females and downregulation in males by post-diapause. This study suggests that calcium-binding chaperones play similar and possibly gender-specific roles during diapause.
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Affiliation(s)
- Cansu Doğan
- Molecular Entomology Lab, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany
- Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, Saskatchewan, Canada
- Department of Entomology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Sabine Hänniger
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - David G Heckel
- Department of Entomology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Cathy Coutu
- Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, Saskatchewan, Canada
| | - Dwayne D Hegedus
- Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, Saskatchewan, Canada
| | - Linda Crubaugh
- Department of Entomology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Russell L Groves
- Department of Entomology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Şerife Bayram
- Molecular Entomology Lab, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
| | - Umut Toprak
- Molecular Entomology Lab, Department of Plant Protection, Faculty of Agriculture, Ankara University, Ankara, Turkey
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14
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Abstract
Folding of proteins is essential so that they can exert their functions. For proteins that transit the secretory pathway, folding occurs in the endoplasmic reticulum (ER) and various chaperone systems assist in acquiring their correct folding/subunit formation. N-glycosylation is one of the most conserved posttranslational modification for proteins, and in eukaryotes it occurs in the ER. Consequently, eukaryotic cells have developed various systems that utilize N-glycans to dictate and assist protein folding, or if they consistently fail to fold properly, to destroy proteins for quality control and the maintenance of homeostasis of proteins in the ER.
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15
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Fujii S, Kurokawa K, Tago T, Inaba R, Takiguchi A, Nakano A, Satoh T, Satoh AK. Sec71 separates Golgi stacks in Drosophila S2 cells. J Cell Sci 2020; 133:jcs245571. [PMID: 33262309 PMCID: PMC10668125 DOI: 10.1242/jcs.245571] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 11/18/2020] [Indexed: 01/19/2023] Open
Abstract
Golgi stacks are the basic structural units of the Golgi. Golgi stacks are separated from each other and scattered in the cytoplasm of Drosophila cells. Here, we report that the ARF-GEF inhibitor Brefeldin A (BFA) induces the formation of BFA bodies, which are aggregates of Golgi stacks, trans-Golgi networks and recycling endosomes. Recycling endosomes are located in the centers of BFA bodies, while Golgi stacks surround them on their trans sides. Live imaging of S2 cells revealed that Golgi stacks repeatedly merged and separated on their trans sides, and BFA caused successive merger by inhibiting separation, forming BFA bodies. S2 cells carrying genome-edited BFA-resistant mutant Sec71M717L did not form BFA bodies at high concentrations of BFA; S2 cells carrying genome-edited BFA-hypersensitive mutant Sec71F713Y produced BFA bodies at low concentrations of BFA. These results indicate that Sec71 is the sole BFA target for BFA body formation and controls Golgi stack separation. Finally, we showed that impairment of Sec71 in fly photoreceptors induces BFA body formation, with accumulation of both apical and basolateral cargoes, resulting in inhibition of polarized transport.
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Affiliation(s)
- Syara Fujii
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Kazuo Kurokawa
- Live Cell Super-Resolution Imaging Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Tatsuya Tago
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Ryota Inaba
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Arata Takiguchi
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Akihiko Nakano
- Live Cell Super-Resolution Imaging Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Takunori Satoh
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
| | - Akiko K Satoh
- Program of Life and Environmental Science, Graduate School of Integral Science for Life, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan
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16
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Zhao H, Wang T. PE homeostasis rebalanced through mitochondria-ER lipid exchange prevents retinal degeneration in Drosophila. PLoS Genet 2020; 16:e1009070. [PMID: 33064773 PMCID: PMC7592913 DOI: 10.1371/journal.pgen.1009070] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 10/28/2020] [Accepted: 08/21/2020] [Indexed: 02/06/2023] Open
Abstract
The major glycerophospholipid phosphatidylethanolamine (PE) in the nervous system is essential for neural development and function. There are two major PE synthesis pathways, the CDP-ethanolamine pathway in the endoplasmic reticulum (ER) and the phosphatidylserine decarboxylase (PSD) pathway in mitochondria. However, the role played by mitochondrial PE synthesis in maintaining cellular PE homeostasis is unknown. Here, we show that Drosophila pect (phosphoethanolamine cytidylyltransferase) mutants lacking the CDP-ethanolamine pathway, exhibited alterations in phospholipid composition, defective phototransduction, and retinal degeneration. Induction of the PSD pathway fully restored levels and composition of cellular PE, thus rescued the retinal degeneration and defective visual responses in pect mutants. Disrupting lipid exchange between mitochondria and ER blocked the ability of PSD to rescue pect mutant phenotypes. These findings provide direct evidence that the synthesis of PE in mitochondria contributes to cellular PE homeostasis, and suggest the induction of mitochondrial PE synthesis as a promising therapeutic approach for disorders associated with PE deficiency.
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Affiliation(s)
- Haifang Zhao
- National Institute of Biological Sciences, Beijing, China
| | - Tao Wang
- National Institute of Biological Sciences, Beijing, China
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, China
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17
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Rapid Release of Ca 2+ from Endoplasmic Reticulum Mediated by Na +/Ca 2+ Exchange. J Neurosci 2020; 40:3152-3164. [PMID: 32156830 DOI: 10.1523/jneurosci.2675-19.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 02/04/2020] [Accepted: 02/12/2020] [Indexed: 11/21/2022] Open
Abstract
Phototransduction in Drosophila is mediated by phospholipase C (PLC) and Ca2+-permeable TRP channels, but the function of endoplasmic reticulum (ER) Ca2+ stores in this important model for Ca2+ signaling remains obscure. We therefore expressed a low affinity Ca2+ indicator (ER-GCaMP6-150) in the ER, and measured its fluorescence both in dissociated ommatidia and in vivo from intact flies of both sexes. Blue excitation light induced a rapid (tau ∼0.8 s), PLC-dependent decrease in fluorescence, representing depletion of ER Ca2+ stores, followed by a slower decay, typically reaching ∼50% of initial dark-adapted levels, with significant depletion occurring under natural levels of illumination. The ER stores refilled in the dark within 100-200 s. Both rapid and slow store depletion were largely unaffected in InsP3 receptor mutants, but were much reduced in trp mutants. Strikingly, rapid (but not slow) depletion of ER stores was blocked by removing external Na+ and in mutants of the Na+/Ca2+ exchanger, CalX, which we immuno-localized to ER membranes in addition to its established localization in the plasma membrane. Conversely, overexpression of calx greatly enhanced rapid depletion. These results indicate that rapid store depletion is mediated by Na+/Ca2+ exchange across the ER membrane induced by Na+ influx via the light-sensitive channels. Although too slow to be involved in channel activation, this Na+/Ca2+ exchange-dependent release explains the decades-old observation of a light-induced rise in cytosolic Ca2+ in photoreceptors exposed to Ca2+-free solutions.SIGNIFICANCE STATEMENT Phototransduction in Drosophila is mediated by phospholipase C, which activates TRP cation channels by an unknown mechanism. Despite much speculation, it is unknown whether endoplasmic reticulum (ER) Ca2+ stores play any role. We therefore engineered flies expressing a genetically encoded Ca2+ indicator in the photoreceptor ER. Although NCX Na+/Ca2+ exchangers are classically believed to operate only at the plasma membrane, we demonstrate a rapid light-induced depletion of ER Ca2+ stores mediated by Na+/Ca2+ exchange across the ER membrane. This NCX-dependent release was too slow to be involved in channel activation, but explains the decades-old observation of a light-induced rise in cytosolic Ca2+ in photoreceptors bathed in Ca2+-free solutions.
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18
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Sharaf A, Mensching L, Keller C, Rading S, Scheffold M, Palkowitsch L, Djogo N, Rezgaoui M, Kestler HA, Moepps B, Failla AV, Karsak M. Systematic Affinity Purification Coupled to Mass Spectrometry Identified p62 as Part of the Cannabinoid Receptor CB2 Interactome. Front Mol Neurosci 2019; 12:224. [PMID: 31616248 PMCID: PMC6763791 DOI: 10.3389/fnmol.2019.00224] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Accepted: 09/03/2019] [Indexed: 01/29/2023] Open
Abstract
The endocannabinoid system (ECS) consists particularly of cannabinoid receptors 1 and 2 (CB1 and CB2), their endogenous ligands, and enzymes that synthesize and degrade their ligands. It acts in a variety of organs and disease states ranging from cancer progression over neuropathic pain to neurodegeneration. Protein components engaged in the signaling, trafficking, and homeostasis machinery of the G-protein coupled CB2, are however largely unknown. It is therefore important to identify further interaction partners to better understand CB2 receptor functions in physiology and pathophysiology. For this purpose, we used an affinity purification and mass spectrometry-based proteomics approach of Strep-HA-CB2 receptor in HEK293 cells. After subtraction of background interactions and protein frequency library assessment we could identify 83 proteins that were classified by the identification of minimally 2 unique peptides as highly probable interactors. A functional protein association network analysis obtained an interaction network with a significant enrichment of proteins functionally involved in protein metabolic process, in endoplasmic reticulum, response to stress but also in lipid metabolism and membrane organization. The network especially contains proteins involved in biosynthesis and trafficking like calnexin, Sec61A, tubulin chains TUBA1C and TUBB2B, TMED2, and TMED10. Six proteins that were only expressed in stable CB2 expressing cells were DHC24, DHRS7, GGT7, HECD3, KIAA2013, and PLS1. To exemplify the validity of our approach, we chose a candidate having a relatively low number of edges in the network to increase the likelihood of a direct protein interaction with CB2 and focused on the scaffold/phagosomal protein p62/SQSTM1. Indeed, we independently confirmed the interaction by co-immunoprecipitation and immunocytochemical colocalization studies. 3D reconstruction of confocal images furthermore showed CB2 localization in close proximity to p62 positive vesicles at the cell membrane. In summary, we provide a comprehensive repository of the CB2 interactome in HEK293 cells identified by a systematic unbiased approach, which can be used in future experiments to decipher the signaling and trafficking complex of this cannabinoid receptor. Future studies will have to analyze the exact mechanism of the p62-CB2 interaction as well as its putative role in disease pathophysiology.
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Affiliation(s)
- Ahmed Sharaf
- Neuronal and Cellular Signal Transduction, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Leonore Mensching
- Neuronal and Cellular Signal Transduction, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christina Keller
- Neuronal and Cellular Signal Transduction, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sebastian Rading
- Neuronal and Cellular Signal Transduction, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Marina Scheffold
- Neuronal and Cellular Signal Transduction, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Institute of Pharmacology and Toxicology, Ulm University, Ulm, Germany
| | | | - Nevena Djogo
- Neuronal and Cellular Signal Transduction, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Meriem Rezgaoui
- Institute for Biochemistry and Molecular Biology, University of Hamburg, Hamburg, Germany
| | - Hans A Kestler
- Institute of Medical Systems Biology, Ulm University, Ulm, Germany
| | - Barbara Moepps
- Institute of Pharmacology and Toxicology, Ulm University, Ulm, Germany
| | | | - Meliha Karsak
- Neuronal and Cellular Signal Transduction, Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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19
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Xiong L, Zhang L, Yang Y, Li N, Lai W, Wang F, Zhu X, Wang T. ER complex proteins are required for rhodopsin biosynthesis and photoreceptor survival in Drosophila and mice. Cell Death Differ 2019; 27:646-661. [PMID: 31263175 PMCID: PMC7206144 DOI: 10.1038/s41418-019-0378-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 06/11/2019] [Accepted: 06/13/2019] [Indexed: 12/17/2022] Open
Abstract
Defective rhodopsin homeostasis is one of the major causes of retinal degeneration, including the disease Retinitis pigmentosa. To identify cellular factors required for the biosynthesis of rhodopsin, we performed a genome-wide genetic screen in Drosophila for mutants with reduced levels of rhodopsin. We isolated loss-of-function alleles in endoplasmic reticulum membrane protein complex 3 (emc3), emc5, and emc6, each of which exhibited defective phototransduction and photoreceptor cell degeneration. EMC3, EMC5, and EMC6 were essential for rhodopsin synthesis independent of the ER associated degradation (ERAD) pathway, which eliminates misfolded proteins. We generated null mutations for all EMC subunits, and further demonstrated that different EMC subunits play roles in different cellular functions. Conditional knockout of the Emc3 gene in mice led to mislocalization of rhodopsin protein and death of cone and rod photoreceptor cells. These data indicate conserved roles for EMC subunits in maintaining rhodopsin homeostasis and photoreceptor function, and suggest that retinal degeneration may also be caused by defects in early biosynthesis of rhodopsin.
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Affiliation(s)
- Liangyao Xiong
- Peking University-Tsinghua University-National Institute of Biological Sciences Joint Graduate Program, School of Life Sciences, Peking University, Beijing, 100871, China.,National Institute of Biological Sciences, Beijing, 102206, China
| | - Lin Zhang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610072, China
| | - Yeming Yang
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610072, China
| | - Na Li
- Southwest Jiaotong University, Chengdu, Sichuan, China
| | - Wenjia Lai
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, China
| | - Fengchao Wang
- National Institute of Biological Sciences, Beijing, 102206, China.,Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, 100871, China
| | - Xianjun Zhu
- Sichuan Provincial Key Laboratory for Human Disease Gene Study, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, Sichuan, 610072, China. .,Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China. .,Chinese Academy of Sciences Sichuan Translational Medicine Hospital, Chengdu, China. .,Department of Ophthalmology, First People's Hospital of Shangqiu, Shangqiu, Henan, China.
| | - Tao Wang
- National Institute of Biological Sciences, Beijing, 102206, China. .,Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing, 100871, China.
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20
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Ashe S, Yadav S. Maintenance of Rhodopsin levels in Drosophila photoreceptor and phototransduction requires Protein Kinase D. Fly (Austin) 2019; 12:164-173. [PMID: 30663936 DOI: 10.1080/19336934.2019.1565256] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
During Drosophila phototransduction, the G protein coupled receptor (GPCR) Rhodopsin (Rh1) transduces photon absorption into electrical signal via G-protein coupled activation of phospholipase C (PLC). Rh1 levels in the plasma membrane are critical for normal sensitivity to light. In this study, we report that Protein Kinase D (dPKD) regulates Rh1 homeostasis in adult photoreceptors. Although eye development and retinal structure are unaffected in the dPKD hypomorph (dPKDH), it exhibited elevated levels of Rh1. Surprisingly, despite having elevated levels of Rh1, no defect was observed in the electrical response to light in these flies. By contrast the levels of another transmembrane protein of the photoreceptor plasma membrane, Transient receptor potential (TRP) was not altered in dPKDH. Our results indicate that dPKD is dispensable for eye development but is required for maintaining Rh1 levels in adult photoreceptors.
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Affiliation(s)
- Sudipta Ashe
- a National Centre for Biological Sciences-TIFR, GKVK Campus, Bellary Road , Bangalore , 560065 , India.,b Manipal Academy of Higher Education , Manipal , Karnataka , 576104 , India
| | - Shweta Yadav
- a National Centre for Biological Sciences-TIFR, GKVK Campus, Bellary Road , Bangalore , 560065 , India
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21
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Gaspar P, Almudi I, Nunes MDS, McGregor AP. Human eye conditions: insights from the fly eye. Hum Genet 2018; 138:973-991. [PMID: 30386938 DOI: 10.1007/s00439-018-1948-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 10/20/2018] [Indexed: 12/22/2022]
Abstract
The fruit fly Drosophila melanogaster has served as an excellent model to study and understand the genetics of many human diseases from cancer to neurodegeneration. Studying the regulation of growth, determination and differentiation of the compound eyes of this fly, in particular, have provided key insights into a wide range of diseases. Here we review the regulation of the development of fly eyes in light of shared aspects with human eye development. We also show how understanding conserved regulatory pathways in eye development together with the application of tools for genetic screening and functional analyses makes Drosophila a powerful model to diagnose and characterize the genetics underlying many human eye conditions, such as aniridia and retinitis pigmentosa. This further emphasizes the importance and vast potential of basic research to underpin applied research including identifying and treating the genetic basis of human diseases.
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Affiliation(s)
- Pedro Gaspar
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK
| | - Isabel Almudi
- Centro Andaluz de Biología del Desarrollo, CSIC/ Universidad Pablo de Olavide, Carretera de Utrera Km1, 41013, Sevilla, Spain
| | - Maria D S Nunes
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK
| | - Alistair P McGregor
- Department of Biological and Medical Sciences, Oxford Brookes University, Gipsy Lane, Oxford, OX3 0BP, UK.
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22
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Moehlman AT, Casey AK, Servage K, Orth K, Krämer H. Adaptation to constant light requires Fic-mediated AMPylation of BiP to protect against reversible photoreceptor degeneration. eLife 2018; 7:e38752. [PMID: 30015618 PMCID: PMC6066327 DOI: 10.7554/elife.38752] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 07/16/2018] [Indexed: 12/13/2022] Open
Abstract
In response to environmental, developmental, and pathological stressors, cells engage homeostatic pathways to maintain their function. Among these pathways, the Unfolded Protein Response protects cells from the accumulation of misfolded proteins in the ER. Depending on ER stress levels, the ER-resident Fic protein catalyzes AMPylation or de-AMPylation of BiP, the major ER chaperone and regulator of the Unfolded Protein Response. This work elucidates the importance of the reversible AMPylation of BiP in maintaining the Drosophila visual system in response to stress. After 72 hr of constant light, photoreceptors of fic-null and AMPylation-resistant BiPT366A mutants, but not wild-type flies, display loss of synaptic function, disintegration of rhabdomeres, and excessive activation of ER stress reporters. Strikingly, this phenotype is reversible: photoreceptors regain their structure and function within 72 hr once returned to a standard light:dark cycle. These findings show that Fic-mediated AMPylation of BiP is required for neurons to adapt to transient stress demands.
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Affiliation(s)
- Andrew T Moehlman
- Department of NeuroscienceUT Southwestern Medical CenterDallasUnited States
| | - Amanda K Casey
- Department of Molecular BiologyUT Southwestern Medical CenterDallasUnited States
| | - Kelly Servage
- Department of Molecular BiologyUT Southwestern Medical CenterDallasUnited States
- Department of BiochemistryUT Southwestern Medical CenterDallasUnited States
- Howard Hughes Medical InstituteDallasUnited States
| | - Kim Orth
- Department of Molecular BiologyUT Southwestern Medical CenterDallasUnited States
- Department of BiochemistryUT Southwestern Medical CenterDallasUnited States
- Howard Hughes Medical InstituteDallasUnited States
| | - Helmut Krämer
- Department of NeuroscienceUT Southwestern Medical CenterDallasUnited States
- Department of Cell BiologyUT Southwestern Medical CenterDallasUnited States
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23
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Zhao H, Wang J, Wang T. The V-ATPase V1 subunit A1 is required for rhodopsin anterograde trafficking in Drosophila. Mol Biol Cell 2018; 29:1640-1651. [PMID: 29742016 PMCID: PMC6080656 DOI: 10.1091/mbc.e17-09-0546] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Synthesis and maturation of the light sensor, rhodopsin, are critical for the maintenance of light sensitivity and for photoreceptor homeostasis. In Drosophila, the main rhodopsin, Rh1, is synthesized in the endoplasmic reticulum and transported to the rhabdomere through the secretory pathway. In an unbiased genetic screen for factors involved in rhodopsin homeostasis, we identified mutations in vha68-1, which encodes the vacuolar proton-translocating ATPase (V-ATPase) catalytic subunit A isoform 1 of the V1 component. Loss of vha68-1 in photoreceptor cells disrupted post-Golgi anterograde trafficking of Rh1, reduced light sensitivity, increased secretory vesicle pH, and resulted in incomplete Rh1 deglycosylation. In addition, vha68-1 was required for activity-independent photoreceptor cell survival. Importantly, vha68-1 mutants exhibited phenotypes similar to those exhibited by mutations in the V0 component of V-ATPase, vha100-1. These data demonstrate that the V1 and V0 components of V-ATPase play key roles in post-Golgi trafficking of Rh1 and that Drosophila may represent an important animal model system for studying diseases associated with V-ATPase dysfunction.
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Affiliation(s)
- Haifang Zhao
- School of Life Sciences, Tsinghua University, Beijing 100084, China.,National Institute of Biological Sciences, Beijing 102206, China
| | - Jing Wang
- National Institute of Biological Sciences, Beijing 102206, China
| | - Tao Wang
- National Institute of Biological Sciences, Beijing 102206, China
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24
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Global Transcriptome Sequencing Reveals Molecular Profiles of Summer Diapause Induction Stage of Onion Maggot, Delia antiqua (Diptera: Anthomyiidae). G3-GENES GENOMES GENETICS 2018; 8:207-217. [PMID: 29158334 PMCID: PMC5765349 DOI: 10.1534/g3.117.300393] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The onion maggot, Delia antiqua, is a worldwide subterranean pest and can enter diapause during the summer and winter seasons. The molecular regulation of the ontogenesis transition remains largely unknown. Here we used high-throughput RNA sequencing to identify candidate genes and processes linked to summer diapause (SD) induction by comparing the transcriptome differences between the most sensitive larval developmental stage of SD and nondiapause (ND). Nine pairwise comparisons were performed, and significantly differentially regulated transcripts were identified. Several functional terms related to lipid, carbohydrate, and energy metabolism, environmental adaption, immune response, and aging were enriched during the most sensitive SD induction period. A subset of genes, including circadian clock genes, were expressed differentially under diapause induction conditions, and there was much more variation in the most sensitive period of ND- than SD-destined larvae. These expression variations probably resulted in a deep restructuring of metabolic pathways. Potential regulatory elements of SD induction including genes related to lipid, carbohydrate, energy metabolism, and environmental adaption. Collectively, our results suggest the circadian clock is one of the key drivers for integrating environmental signals into the SD induction. Our transcriptome analysis provides insight into the fundamental role of the circadian clock in SD induction in this important model insect species, and contributes to the in-depth elucidation of the molecular regulation mechanism of insect diapause induction.
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25
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Ma JH, Shen S, Wang JJ, He Z, Poon A, Li J, Qu J, Zhang SX. Comparative Proteomic Analysis of the Mitochondria-associated ER Membrane (MAM) in a Long-term Type 2 Diabetic Rodent Model. Sci Rep 2017; 7:2062. [PMID: 28522876 PMCID: PMC5437025 DOI: 10.1038/s41598-017-02213-1] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 04/06/2017] [Indexed: 12/24/2022] Open
Abstract
The mitochondria-associated ER membrane (MAM) plays a critical role in cellular energetics and calcium homeostasis; however, how MAM is affected under diabetic condition remains elusive. This study presented a comprehensive proteome profiling of isolated brain MAM from long-term type 2 diabetic mice vs. non-diabetic controls. MAM protein was extracted efficiently by a surfactant-aided precipitation/on-pellet digestion (SOD) method, and MAM proteome was quantified by an ion-current-based MS1 method combined with nanoLC-MS/MS. A total of 1,313 non-redundant proteins of MAM were identified, among which 144 proteins were found significantly altered by diabetes. In-depth IPA analysis identified multiple disease-relevant signaling pathways associated with the MAM proteome changes in diabetes, most significantly the unfolded protein response (UPR), p53, hypoxia-related transcription factors, and methyl CpG binding protein 2. Using immunofluorescence labeling we confirmed the activation of three UPR branches and increased ERp29 and calreticulin in diabetic retinas. Moreover, we found GRP75, a key MAM tethering protein, was drastically reduced by long-term diabetes. In vitro, acute high glucose treatment reduces ER-mitochondrial contact in retinal endothelial cells. This study provides first insight into the significant alterations in MAM proteome associated with activation of the UPR in diabetes, which may serve as novel benchmarks for the future studies of diabetic complications.
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Affiliation(s)
- Jacey Hongjie Ma
- Department of Ophthalmology and Ross Eye Institute, University at Buffalo, State University of New York, Buffalo, NY, USA
- SUNY Eye Institute, State University of New York, New York, NY, USA
- Aier School of Ophthalmology, Central South University, Changsha, China
| | - Shichen Shen
- Department of Biochemistry, University at Buffalo, State University of New York, Buffalo, NY, USA
- New York State Center of Excellence in Bioinformatics and Life Sciences, 701 Ellicott Street, Buffalo, NY, USA
| | - Joshua J Wang
- Department of Ophthalmology and Ross Eye Institute, University at Buffalo, State University of New York, Buffalo, NY, USA
- SUNY Eye Institute, State University of New York, New York, NY, USA
| | - Zhanwen He
- Department of Biochemistry, University at Buffalo, State University of New York, Buffalo, NY, USA
- Department of Pediatrics, Sun Yat-Sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Amanda Poon
- Department of Biochemistry, University at Buffalo, State University of New York, Buffalo, NY, USA
| | - Jun Li
- New York State Center of Excellence in Bioinformatics and Life Sciences, 701 Ellicott Street, Buffalo, NY, USA
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, State University of New York, Buffalo, NY, USA
| | - Jun Qu
- New York State Center of Excellence in Bioinformatics and Life Sciences, 701 Ellicott Street, Buffalo, NY, USA
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, State University of New York, Buffalo, NY, USA
| | - Sarah X Zhang
- Department of Ophthalmology and Ross Eye Institute, University at Buffalo, State University of New York, Buffalo, NY, USA.
- SUNY Eye Institute, State University of New York, New York, NY, USA.
- Department of Biochemistry, University at Buffalo, State University of New York, Buffalo, NY, USA.
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26
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Kamalesh K, Trivedi D, Toscano S, Sharma S, Kolay S, Raghu P. Phosphatidylinositol 5-phosphate 4-kinase regulates early endosomal dynamics during clathrin-mediated endocytosis. J Cell Sci 2017; 130:2119-2133. [PMID: 28507272 PMCID: PMC5536888 DOI: 10.1242/jcs.202259] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 05/09/2017] [Indexed: 12/19/2022] Open
Abstract
Endocytic turnover is essential for the regulation of the protein composition and function of the plasma membrane, and thus affects the plasma membrane levels of many receptors. In Drosophila melanogaster photoreceptors, photon absorption by the G-protein-coupled receptor (GPCR) rhodopsin 1 (Rh1; also known as NinaE) triggers its endocytosis through clathrin-mediated endocytosis (CME). We find that CME of Rh1 is regulated by phosphatidylinositol 5 phosphate 4-kinase (PIP4K). Flies lacking PIP4K show mislocalization of Rh1 on expanded endomembranes within the cell body. This mislocalization of Rh1 was dependent on the formation of an expanded Rab5-positive compartment. The Rh1-trafficking defect in PIP4K-depleted cells could be suppressed by downregulating Rab5 function or by selectively reconstituting PIP4K in the PI3P-enriched early endosomal compartment of photoreceptors. We also found that loss of PIP4K was associated with increased CME and an enlarged Rab5-positive compartment in cultured Drosophila cells. Collectively, our findings define PIP4K as a novel regulator of early endosomal homeostasis during CME.
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Affiliation(s)
- Kumari Kamalesh
- National Centre for Biological Sciences-TIFR, GKVK Campus, Bellary Road, Bangalore 560065, India.,Department of Biological Sciences, Tata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai 400005, India
| | - Deepti Trivedi
- National Centre for Biological Sciences-TIFR, GKVK Campus, Bellary Road, Bangalore 560065, India
| | - Sarah Toscano
- Inositide Laboratory, Babraham Institute, Cambridge CB22 3AT, UK
| | - Sanjeev Sharma
- National Centre for Biological Sciences-TIFR, GKVK Campus, Bellary Road, Bangalore 560065, India
| | - Sourav Kolay
- National Centre for Biological Sciences-TIFR, GKVK Campus, Bellary Road, Bangalore 560065, India.,Manipal University, Madhav Nagar, Manipal, Karnataka 576104, India
| | - Padinjat Raghu
- National Centre for Biological Sciences-TIFR, GKVK Campus, Bellary Road, Bangalore 560065, India
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27
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Xiao X, Chen C, Yu TM, Ou J, Rui M, Zhai Y, He Y, Xue L, Ho MS. Molecular Chaperone Calnexin Regulates the Function of Drosophila Sodium Channel Paralytic. Front Mol Neurosci 2017; 10:57. [PMID: 28326013 PMCID: PMC5339336 DOI: 10.3389/fnmol.2017.00057] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 02/20/2017] [Indexed: 12/20/2022] Open
Abstract
Neuronal activity mediated by voltage-gated channels provides the basis for higher-order behavioral tasks that orchestrate life. Chaperone-mediated regulation, one of the major means to control protein quality and function, is an essential route for controlling channel activity. Here we present evidence that Drosophila ER chaperone Calnexin colocalizes and interacts with the α subunit of sodium channel Paralytic. Co-immunoprecipitation analysis indicates that Calnexin interacts with Paralytic protein variants that contain glycosylation sites Asn313, 325, 343, 1463, and 1482. Downregulation of Calnexin expression results in a decrease in Paralytic protein levels, whereas overexpression of the Calnexin C-terminal calcium-binding domain triggers an increase reversely. Genetic analysis using adult climbing, seizure-induced paralysis, and neuromuscular junction indicates that lack of Calnexin expression enhances Paralytic-mediated locomotor deficits, suppresses Paralytic-mediated ghost bouton formation, and regulates minature excitatory junction potentials (mEJP) frequency and latency time. Taken together, our findings demonstrate a need for chaperone-mediated regulation on channel activity during locomotor control, providing the molecular basis for channlopathies such as epilepsy.
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Affiliation(s)
- Xi Xiao
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of MedicineShanghai, China; Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of MedicineShanghai, China; Department of Anatomy and Neurobiology, Tongji University School of MedicineShanghai, China
| | - Changyan Chen
- Shanghai Key Laboratory of Signaling and Diseases Research, School of Life Science and Technology, Institute of Intervention Vessel, Shanghai 10th People's Hospital, Tongji University Shanghai, China
| | - Tian-Ming Yu
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of MedicineShanghai, China; Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of MedicineShanghai, China; Department of Anatomy and Neurobiology, Tongji University School of MedicineShanghai, China
| | - Jiayao Ou
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of MedicineShanghai, China; Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of MedicineShanghai, China; Department of Anatomy and Neurobiology, Tongji University School of MedicineShanghai, China
| | - Menglong Rui
- Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University Nanjing, China
| | - Yuanfen Zhai
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of MedicineShanghai, China; Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of MedicineShanghai, China; Department of Anatomy and Neurobiology, Tongji University School of MedicineShanghai, China
| | - Yijing He
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of MedicineShanghai, China; Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of MedicineShanghai, China; Department of Anatomy and Neurobiology, Tongji University School of MedicineShanghai, China
| | - Lei Xue
- Shanghai Key Laboratory of Signaling and Diseases Research, School of Life Science and Technology, Institute of Intervention Vessel, Shanghai 10th People's Hospital, Tongji University Shanghai, China
| | - Margaret S Ho
- Research Center for Translational Medicine, Shanghai East Hospital, Tongji University School of MedicineShanghai, China; Key Laboratory of Arrhythmias of the Ministry of Education of China, Shanghai East Hospital, Tongji University School of MedicineShanghai, China; Department of Anatomy and Neurobiology, Tongji University School of MedicineShanghai, China
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28
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Vu KV, Nguyen NT, Jeong CY, Lee YH, Lee H, Hong SW. Systematic deletion of the ER lectin chaperone genes reveals their roles in vegetative growth and male gametophyte development in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 89:972-983. [PMID: 27888524 DOI: 10.1111/tpj.13435] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 11/18/2016] [Accepted: 11/21/2016] [Indexed: 05/27/2023]
Abstract
Calnexin (CNX) and calreticulin (CRT) are homologous lectin chaperones in the endoplasmic reticulum (ER) that facilitate glycoprotein folding and retain folding intermediates to prevent their transit via the secretary pathway. The Arabidopsis genome has two CNX (CNX1 and CNX2) and three CRT (CRT1, CRT2 and CRT3) homologs. Despite growing evidence of the biological roles of CNXs and CRTs, little is understood about their function in Arabidopsis growth and development under normal conditions. Here, we report that the deletion of CNX1, but not of CNX2, in the crt1 crt2 crt3 triple mutation background had an adverse effect on pollen viability and pollen tube growth, leading to a significant reduction in fertility. The cnx1 crt1 crt2 crt3 quadruple mutation also conferred severe defects in growth and development, including a shortened primary root, increased root hair length and density, and reduced plant height. Disruption of all five members of the CNX/CRT family was revealed to be lethal. Finally, the abnormal phenotype of the cnx1 crt1 crt2 crt3 quadruple mutants was completely rescued by either the CNX1 or CNX2 cDNA under the control of the CNX1 promoter, suggesting functional redundancy between CNX1 and CNX2. Taken together, these results provide genetic evidence that CNX and CRT play essential and overlapping roles during vegetative growth and male gametophyte development in Arabidopsis.
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Affiliation(s)
- Kien Van Vu
- Department of Molecular Biotechnology, College of Agriculture and Life Sciences, Bioenergy Research Institute, Chonnam National University, Gwangju, Korea
| | - Ngoc Trinh Nguyen
- Department of Molecular Biotechnology, College of Agriculture and Life Sciences, Bioenergy Research Institute, Chonnam National University, Gwangju, Korea
| | - Chan Young Jeong
- Department of Molecular Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Korea
| | - Yong-Hwa Lee
- National Institute of Crop Science, Bioenergy Crop Research Center, Muan, Jeonnam, Korea
| | - Hojoung Lee
- Department of Molecular Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul, Korea
| | - Suk-Whan Hong
- Department of Molecular Biotechnology, College of Agriculture and Life Sciences, Bioenergy Research Institute, Chonnam National University, Gwangju, Korea
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29
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Schopf K, Huber A. Membrane protein trafficking in Drosophila photoreceptor cells. Eur J Cell Biol 2016; 96:391-401. [PMID: 27964885 DOI: 10.1016/j.ejcb.2016.11.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 11/21/2016] [Accepted: 11/28/2016] [Indexed: 10/20/2022] Open
Abstract
Membrane protein trafficking occurs throughout the lifetime of neurons and includes the initial protein synthesis and anterograde transport to the plasma membrane as well as internalization, degradation, and recycling of plasma membrane proteins. Defects in protein trafficking can result in neuronal degeneration and underlie blinding diseases such as retinitis pigmentosa as well as other neuronal disorders. Drosophila photoreceptor cells have emerged as a model system for identifying the components and mechanisms involved in membrane protein trafficking in neurons. Here we summarize the current knowledge about trafficking of three Drosophila phototransduction proteins, the visual pigment rhodopsin and the two light-activated ion channels TRP (transient receptor potential) and TRPL (TRP-like). Despite some common requirements shared by rhodopsin and TRP, details in the trafficking of these proteins differ considerably, suggesting the existence of several trafficking pathways for these photoreceptor proteins.
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Affiliation(s)
- Krystina Schopf
- University of Hohenheim, Institute of Physiology, Department of Biosensorics, Stuttgart, Germany
| | - Armin Huber
- University of Hohenheim, Institute of Physiology, Department of Biosensorics, Stuttgart, Germany.
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30
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Satoh T, Nakamura Y, Satoh AK. The roles of Syx5 in Golgi morphology and Rhodopsin transport in Drosophila photoreceptors. Biol Open 2016; 5:1420-1430. [PMID: 27591190 PMCID: PMC5087674 DOI: 10.1242/bio.020958] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
SNAREs (SNAP receptors) are the key components of protein complexes that drive membrane fusion. Here, we report the function of a SNARE, Syntaxin 5 (Syx5), in the development of photoreceptors in Drosophila. In wild-type photoreceptors, Syx5 localizes to cis-Golgi, along with cis-Golgi markers: Rab1 and GM130. We observed that Syx5-deficient photoreceptors show notable accumulation of these cis-Golgi markers accompanying drastic accumulation of vesicles between endoplasmic reticulum (ER) and Golgi cisternae. Extensive analysis of Rh1 (rhodopsin 1) trafficking revealed that in Syx5-deficient photoreceptors, Rh1 is exported from the ER with normal kinetics, retained in the cis-Golgi region along with GM130 for a prolonged period, and then subsequently degraded presumably by endoplasmic reticulum-associated protein degradation (ERAD) after retrieval to the ER. Unlike our previous report of Rab6-deficient photoreceptors – where two apical transport pathways are specifically inhibited – vesicle transport pathways to all plasma membrane domains are inhibited in Syx5-deficient photoreceptors, implying that Rab6 and Syx5 are acting in different steps of intra-Golgi transport. These results indicate that Syx5 is crucial for membrane protein transport, presumably during ER-derived vesicle fusion to form cis-Golgi cisternae. Summary: Unlike Rab6-deficiency which affects only apical transport pathways, Syx5-deficiency inhibits all of polarized transport pathways, implying that these two genes are working in distinct stages of intra-Golgi transport.
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Affiliation(s)
- Takunori Satoh
- Division of Life Science, Graduate School of Integral Arts and Science, Hiroshima University, 1-7-1, Kagamiyama, Higashi-hiroshima 739-8521, Japan
| | - Yuri Nakamura
- Division of Life Science, Graduate School of Integral Arts and Science, Hiroshima University, 1-7-1, Kagamiyama, Higashi-hiroshima 739-8521, Japan
| | - Akiko K Satoh
- Division of Life Science, Graduate School of Integral Arts and Science, Hiroshima University, 1-7-1, Kagamiyama, Higashi-hiroshima 739-8521, Japan
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31
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Cehofski LJ, Kruse A, Bøgsted M, Magnusdottir SO, Stensballe A, Honoré B, Vorum H. Retinal proteome changes following experimental branch retinal vein occlusion and intervention with ranibizumab. Exp Eye Res 2016; 152:49-56. [PMID: 27619476 DOI: 10.1016/j.exer.2016.09.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 08/07/2016] [Accepted: 09/08/2016] [Indexed: 01/28/2023]
Abstract
Animal models of experimental branch retinal vein occlusion (BRVO) provide a unique opportunity to study protein changes directly in retinal tissue. Results from these experimental models suggest that experimental BRVO is associated with an upregulation of extracellular matrix remodeling and adhesion signaling processes. To study whether these processes could be blocked by inhibition of VEGF-A, a porcine model of experimental BRVO was combined with proteomic analyses. In six Danish Landrace pigs experimental BRVO was induced with argon laser in both eyes. After 24 h an injection of 0.05 mL ranibizumab was given in the right eyes of the animals while left eyes received an injection of 0.05 mL 9 mg/mL sodium chloride water. Retinas were dissected three days after BRVO and the retinal samples were analyzed with label-free quantification as well as tandem mass tag based proteomics. In retinas treated with ranibizumab five proteins exhibited statistically significant changes in content with both proteomic techniques. These five proteins, which were all decreased in content, included integrin β-1, peroxisomal 3-ketoacyl-CoA thiolase, OCIA domain-containing protein 1, calnexin and 40S ribosomal protein S5. As anti-integrin therapies are under development for inhibition of angiogenesis in retinal diseases it is interesting that inhibition of VEGF-A in itself resulted in a small decrease in the content of integrin β-1. The decreased content of integrin β-1 indicates that extracellular matrix remodeling and adhesion processes associated with BRVO are at least partly reversed through inhibition of VEGF-A.
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Affiliation(s)
- Lasse Jørgensen Cehofski
- Department of Ophthalmology, Aalborg University Hospital, Aalborg, Denmark; Biomedical Research Laboratory, Aalborg University Hospital, Aalborg, Denmark; Department of Clinical Medicine, Aalborg University, Aalborg, Denmark.
| | - Anders Kruse
- Department of Ophthalmology, Aalborg University Hospital, Aalborg, Denmark
| | - Martin Bøgsted
- Department of Clinical Medicine, Aalborg University, Aalborg, Denmark; Department of Haematology, Aalborg University Hospital, Aalborg, Denmark
| | | | - Allan Stensballe
- Department of Health Science and Technology, Aalborg University, Denmark
| | - Bent Honoré
- Department of Clinical Medicine, Aalborg University, Aalborg, Denmark; Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Henrik Vorum
- Department of Ophthalmology, Aalborg University Hospital, Aalborg, Denmark; Department of Clinical Medicine, Aalborg University, Aalborg, Denmark
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32
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Riedel F, Gillingham AK, Rosa-Ferreira C, Galindo A, Munro S. An antibody toolkit for the study of membrane traffic in Drosophila melanogaster. Biol Open 2016; 5:987-92. [PMID: 27256406 PMCID: PMC4958275 DOI: 10.1242/bio.018937] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The use of Drosophila melanogaster as a model organism has been pivotal to understanding the developmental processes of metazoans. However, the use of flies for studying subcellular organization is hampered by a paucity of reliable reagents to label specific organelles. Here, we describe the generation of mouse monoclonal antibodies against a set of markers of the secretory and endocytic pathways, along with goat polyclonal antibodies against two Golgi proteins. We show that the monoclonal antibodies are highly specific and sufficiently sensitive to detect endogenous proteins in crude extracts by immunoblotting with little background staining. By immunofluorescence the major compartments of the membrane traffic system (including the endoplasmic reticulum, the Golgi, and early and late endosomes) are labeled by at least one antibody. Moreover, the antibodies can be used to label organelles in fly tissues including salivary glands and wing imaginal discs. We anticipate that these antibodies will provide a useful tool kit to facilitate the investigation of how the endomembrane system functions and varies in the diverse tissue types of metazoans. Summary: We report the generation and characterization of set of monoclonal and polyclonal antibodies for labeling the major compartments of the secretory and endocytic pathways in Drosophila melanogaster.
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Affiliation(s)
- Falko Riedel
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Alison K Gillingham
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Cláudia Rosa-Ferreira
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Antonio Galindo
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Sean Munro
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
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33
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Abstract
Endoplasmic Reticulum (ER) is an organelle where most secretory and membrane proteins are synthesized, folded, and undergo further maturation. As numerous conditions can perturb such ER function, eukaryotic cells are equipped with responsive signaling pathways, widely referred to as the Unfolded Protein Response (UPR). Chronic conditions of ER stress that cannot be fully resolved by UPR, or conditions that impair UPR signaling itself, are associated with many metabolic and degenerative diseases. In recent years, Drosophila has been actively employed to study such connections between UPR and disease. Notably, the UPR pathways are largely conserved between Drosophila and humans, and the mediating genes are essential for development in both organisms, indicating their requirement to resolve inherent stress. By now, many Drosophila mutations are known to impose stress in the ER, and a number of these appear similar to those that underlie human diseases. In addition, studies have employed the strategy of overexpressing human mutations in Drosophila tissues to perform genetic modifier screens. The fact that the basic UPR pathways are conserved, together with the availability of many human disease models in this organism, makes Drosophila a powerful tool for studying human disease mechanisms. [BMB Reports 2015; 48(8): 445-453]
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Affiliation(s)
- Hyung Don Ryoo
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
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34
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Garcia-Huerta P, Bargsted L, Rivas A, Matus S, Vidal RL. ER chaperones in neurodegenerative disease: Folding and beyond. Brain Res 2016; 1648:580-587. [PMID: 27134034 DOI: 10.1016/j.brainres.2016.04.070] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 04/27/2016] [Accepted: 04/28/2016] [Indexed: 12/13/2022]
Abstract
Proteins along the secretory pathway are co-translationally translocated into the lumen of the endoplasmic reticulum (ER) as unfolded polypeptide chains. Afterwards, they are usually modified with N-linked glycans, correctly folded and stabilized by disulfide bonds. ER chaperones and folding enzymes control these processes. The accumulation of unfolded proteins in the ER activates a signaling response, termed the unfolded protein response (UPR). The hallmark of this response is the coordinated transcriptional up-regulation of ER chaperones and folding enzymes. In order to discuss the importance of the proper folding of certain substrates we will address the role of ER chaperones in normal physiological conditions and examine different aspects of its contribution in neurodegenerative disease. This article is part of a Special Issue entitled SI:ER stress.
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Affiliation(s)
- Paula Garcia-Huerta
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile; Center for Geroscience, Brain Health and Metabolism, Santiago, Chile; Program of Cellular and Molecular Biology, Center for Molecular Studies of the Cell Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Leslie Bargsted
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile; Center for Geroscience, Brain Health and Metabolism, Santiago, Chile; Program of Cellular and Molecular Biology, Center for Molecular Studies of the Cell Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Alexis Rivas
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile; Center for Geroscience, Brain Health and Metabolism, Santiago, Chile; Program of Cellular and Molecular Biology, Center for Molecular Studies of the Cell Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Soledad Matus
- Neurounion Biomedical Foundation, Santiago, Chile; Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile; CENPAR, Santiago, Chile; Center for Geroscience, Brain Health and Metabolism, Santiago, Chile.
| | - Rene L Vidal
- Neurounion Biomedical Foundation, Santiago, Chile; Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile; CENPAR, Santiago, Chile; Center for Geroscience, Brain Health and Metabolism, Santiago, Chile.
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The GTP- and Phospholipid-Binding Protein TTD14 Regulates Trafficking of the TRPL Ion Channel in Drosophila Photoreceptor Cells. PLoS Genet 2015; 11:e1005578. [PMID: 26509977 PMCID: PMC4624897 DOI: 10.1371/journal.pgen.1005578] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 09/15/2015] [Indexed: 01/04/2023] Open
Abstract
Recycling of signaling proteins is a common phenomenon in diverse signaling pathways. In photoreceptors of Drosophila, light absorption by rhodopsin triggers a phospholipase Cβ-mediated opening of the ion channels transient receptor potential (TRP) and TRP-like (TRPL) and generates the visual response. The signaling proteins are located in a plasma membrane compartment called rhabdomere. The major rhodopsin (Rh1) and TRP are predominantly localized in the rhabdomere in light and darkness. In contrast, TRPL translocates between the rhabdomeral plasma membrane in the dark and a storage compartment in the cell body in the light, from where it can be recycled to the plasma membrane upon subsequent dark adaptation. Here, we identified the gene mutated in trpl translocation defective 14 (ttd14), which is required for both TRPL internalization from the rhabdomere in the light and recycling of TRPL back to the rhabdomere in the dark. TTD14 is highly conserved in invertebrates and binds GTP in vitro. The ttd14 mutation alters a conserved proline residue (P75L) in the GTP-binding domain and abolishes binding to GTP. This indicates that GTP binding is essential for TTD14 function. TTD14 is a cytosolic protein and binds to PtdIns(3)P, a lipid enriched in early endosome membranes, and to phosphatidic acid. In contrast to TRPL, rhabdomeral localization of the membrane proteins Rh1 and TRP is not affected in the ttd14P75L mutant. The ttd14P75L mutation results in Rh1-independent photoreceptor degeneration and larval lethality suggesting that other processes are also affected by the ttd14P75L mutation. In conclusion, TTD14 is a novel regulator of TRPL trafficking, involved in internalization and subsequent sorting of TRPL into the recycling pathway that enables this ion channel to return to the plasma membrane. Protein trafficking in neurons occurs throughout the lifetime of a cell and includes the internalization and redistribution of plasma membrane proteins. Regulated protein trafficking controls the equipment of the plasma membrane with receptors and ion channels and thereby attenuates or enhances neuronal function. Defects in recycling of plasma membrane proteins can cause detrimental neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease and Down´s syndrome. In Drosophila photoreceptors, the TRPL ion channel, together with the TRP channel, mediates vision and light-dependently shuttles between an endomembrane storage compartment and the apical plasma membrane. Here, we report the identification of a mutation in the ttd14 gene that inhibits TRPL-trafficking in both directions and also results in photoreceptor degeneration. The TTD14 protein contains a region with weak homology to a PX-domain, which is also found in proteins that sort cargo in the endosome and enable protein recycling. We characterize TTD14 as a new regulator of photoreceptor maintenance and ion channel trafficking that binds to GTP and PtdIns(3)P, a phospholipid enriched in early endosomes.
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TRP and Rhodopsin Transport Depends on Dual XPORT ER Chaperones Encoded by an Operon. Cell Rep 2015; 13:573-584. [PMID: 26456832 DOI: 10.1016/j.celrep.2015.09.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 07/30/2015] [Accepted: 09/04/2015] [Indexed: 11/24/2022] Open
Abstract
TRP channels and G protein-coupled receptors (GPCRs) play critical roles in sensory reception. However, the identities of the chaperones that assist GPCRs in translocating from the endoplasmic reticulum (ER) are limited, and TRP ER chaperones are virtually unknown. The one exception for TRPs is Drosophila XPORT. Here, we show that the xport locus is bicistronic and encodes unrelated transmembrane proteins, which enable the signaling proteins that initiate and culminate phototransduction, rhodopsin 1 (Rh1) and TRP, to traffic to the plasma membrane. XPORT-A and XPORT-B are ER proteins, and loss of either has a profound impact on TRP and Rh1 targeting to the light-sensing compartment of photoreceptor cells. XPORT-B complexed in vivo with the Drosophila homolog of the mammalian HSP70 protein, GRP78/BiP, which, in turn, associated with Rh1. Our work highlights a coordinated network of chaperones required for the biosynthesis of the TRP channel and rhodopsin in Drosophila photoreceptor cells.
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Satoh T, Ohba A, Liu Z, Inagaki T, Satoh AK. dPob/EMC is essential for biosynthesis of rhodopsin and other multi-pass membrane proteins in Drosophila photoreceptors. eLife 2015; 4. [PMID: 25715730 PMCID: PMC4341237 DOI: 10.7554/elife.06306] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 01/26/2015] [Indexed: 12/22/2022] Open
Abstract
In eukaryotes, most integral membrane proteins are synthesized, integrated into the membrane, and folded properly in the endoplasmic reticulum (ER). We screened the mutants affecting rhabdomeric expression of rhodopsin 1 (Rh1) in the Drosophila photoreceptors and found that dPob/EMC3, EMC1, and EMC8/9, Drosophila homologs of subunits of ER membrane protein complex (EMC), are essential for stabilization of immature Rh1 in an earlier step than that at which another Rh1-specific chaperone (NinaA) acts. dPob/EMC3 localizes to the ER and associates with EMC1 and calnexin. Moreover, EMC is required for the stable expression of other multi-pass transmembrane proteins such as minor rhodopsins Rh3 and Rh4, transient receptor potential, and Na+K+-ATPase, but not for a secreted protein or type I single-pass transmembrane proteins. Furthermore, we found that dPob/EMC3 deficiency induces rhabdomere degeneration in a light-independent manner. These results collectively indicate that EMC is a key factor in the biogenesis of multi-pass transmembrane proteins, including Rh1, and its loss causes retinal degeneration. DOI:http://dx.doi.org/10.7554/eLife.06306.001 The membranes that surround cells contain many proteins, and those that span the entire width of the membrane are known as transmembrane proteins. Rhodopsin is one such transmembrane protein that is found in the light-sensitive ‘photoreceptor’ cells of the eye, where it plays an essential role in vision. Transmembrane proteins are made inside the cell and are inserted into the membrane surrounding a compartment called the endoplasmic reticulum. Here, they mature and ‘fold’ into their correct three-dimensional shape with help from chaperone proteins. Once correctly folded, the transmembrane proteins can be transported to the cell membrane. Incorrect folding of proteins can have severe consequences; if rhodopsin is incorrectly folded the photoreceptor cells can die, leading to blindness in humans and other animals. Experiments carried out in zebrafish have shown that the chaperone protein Pob is required for the survival of photoreceptor cells. Pob is part of a group or ‘complex’ of chaperone proteins in the endoplasmic reticulum called the EMC complex. This suggests that the EMC complex may be involved in folding rhodopsin, but the details remain unclear. Here, Satoh et al. studied the role of the EMC complex in the folding of rhodopsin in fruit flies. This involved examining hundreds of flies that carried a variety of genetic mutations and that also had low levels of rhodopsin. The experiments show that dPob—the fly version of Pob—and two other proteins in the EMC complex are required for newly-made rhodopsin to be stabilized. If photoreceptor cells are missing proteins from the complex, the light-sensitive structures in the eye degenerate. Rhodopsin is known as a ‘multi-pass’ membrane protein because it crosses the membrane multiple times. Satoh et al. found that the EMC complex is also required for the folding of other multi-pass membrane proteins in photoreceptor cells. The next challenge will be to reveal how the EMC complex is able to specifically target this type of transmembrane protein. DOI:http://dx.doi.org/10.7554/eLife.06306.002
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Affiliation(s)
- Takunori Satoh
- Graduate School of Integrated Arts and Science, Hiroshima University, Higashi-Hiroshima, Japan
| | - Aya Ohba
- Graduate School of Integrated Arts and Science, Hiroshima University, Higashi-Hiroshima, Japan
| | - Ziguang Liu
- Institute of Animal Husbandry, Heilongjiang Academy of Agricultural Sciences, Harbin, China
| | - Tsuyoshi Inagaki
- Graduate School of Integrated Arts and Science, Hiroshima University, Higashi-Hiroshima, Japan
| | - Akiko K Satoh
- Graduate School of Integrated Arts and Science, Hiroshima University, Higashi-Hiroshima, Japan
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Lee D, Kraus A, Prins D, Groenendyk J, Aubry I, Liu WX, Li HD, Julien O, Touret N, Sykes BD, Tremblay ML, Michalak M. UBC9-dependent association between calnexin and protein tyrosine phosphatase 1B (PTP1B) at the endoplasmic reticulum. J Biol Chem 2015; 290:5725-38. [PMID: 25586181 DOI: 10.1074/jbc.m114.635474] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Calnexin is a type I integral endoplasmic reticulum (ER) membrane protein, molecular chaperone, and a component of the translocon. We discovered a novel interaction between the calnexin cytoplasmic domain and UBC9, a SUMOylation E2 ligase, which modified the calnexin cytoplasmic domain by the addition of SUMO. We demonstrated that calnexin interaction with the SUMOylation machinery modulates an interaction with protein tyrosine phosphatase 1B (PTP1B), an ER-associated protein tyrosine phosphatase involved in the negative regulation of insulin and leptin signaling. We showed that calnexin and PTP1B form UBC9-dependent complexes, revealing a previously unrecognized contribution of calnexin to the retention of PTP1B at the ER membrane. This work shows that the SUMOylation machinery links two ER proteins from divergent pathways to potentially affect cellular protein quality control and energy metabolism.
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Affiliation(s)
- Dukgyu Lee
- From the Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada and
| | - Allison Kraus
- From the Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada and
| | - Daniel Prins
- From the Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada and
| | - Jody Groenendyk
- From the Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada and
| | - Isabelle Aubry
- McGill Cancer Centre, Department of Biochemistry, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - Wen-Xin Liu
- From the Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada and
| | - Hao-Dong Li
- From the Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada and
| | - Olivier Julien
- From the Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada and
| | - Nicolas Touret
- From the Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada and
| | - Brian D Sykes
- From the Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada and
| | - Michel L Tremblay
- McGill Cancer Centre, Department of Biochemistry, McGill University, Montreal, Quebec H3G 1Y6, Canada
| | - Marek Michalak
- McGill Cancer Centre, Department of Biochemistry, McGill University, Montreal, Quebec H3G 1Y6, Canada
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Rosenbaum EE, Vasiljevic E, Cleland SC, Flores C, Colley NJ. The Gos28 SNARE protein mediates intra-Golgi transport of rhodopsin and is required for photoreceptor survival. J Biol Chem 2014; 289:32392-409. [PMID: 25261468 PMCID: PMC4239595 DOI: 10.1074/jbc.m114.585166] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 09/24/2014] [Indexed: 11/06/2022] Open
Abstract
SNARE proteins play indispensable roles in membrane fusion events in many cellular processes, including synaptic transmission and protein trafficking. Here, we characterize the Golgi SNARE protein, Gos28, and its role in rhodopsin (Rh1) transport through Drosophila photoreceptors. Mutations in gos28 lead to defective Rh1 trafficking and retinal degeneration. We have pinpointed a role for Gos28 in the intra-Golgi transport of Rh1, downstream from α-mannosidase-II in the medial- Golgi. We have confirmed the necessity of key residues in Gos28's SNARE motif and demonstrate that its transmembrane domain is not required for vesicle fusion, consistent with Gos28 functioning as a t-SNARE for Rh1 transport. Finally, we show that human Gos28 rescues both the Rh1 trafficking defects and retinal degeneration in Drosophila gos28 mutants, demonstrating the functional conservation of these proteins. Our results identify Gos28 as an essential SNARE protein in Drosophila photoreceptors and provide mechanistic insights into the role of SNAREs in neurodegenerative disease.
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Affiliation(s)
- Erica E Rosenbaum
- From the Department of Ophthalmology and Visual Sciences, Department of Genetics and The McPherson Eye Research Institute, University of Wisconsin, Madison, Wisconsin 53792
| | - Eva Vasiljevic
- From the Department of Ophthalmology and Visual Sciences, Department of Genetics and The McPherson Eye Research Institute, University of Wisconsin, Madison, Wisconsin 53792
| | - Spencer C Cleland
- From the Department of Ophthalmology and Visual Sciences, Department of Genetics and The McPherson Eye Research Institute, University of Wisconsin, Madison, Wisconsin 53792
| | - Carlos Flores
- From the Department of Ophthalmology and Visual Sciences, Department of Genetics and The McPherson Eye Research Institute, University of Wisconsin, Madison, Wisconsin 53792
| | - Nansi Jo Colley
- From the Department of Ophthalmology and Visual Sciences, Department of Genetics and The McPherson Eye Research Institute, University of Wisconsin, Madison, Wisconsin 53792
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Tao YX, Conn PM. Chaperoning G protein-coupled receptors: from cell biology to therapeutics. Endocr Rev 2014; 35:602-47. [PMID: 24661201 PMCID: PMC4105357 DOI: 10.1210/er.2013-1121] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Accepted: 03/14/2014] [Indexed: 12/13/2022]
Abstract
G protein-coupled receptors (GPCRs) are membrane proteins that traverse the plasma membrane seven times (hence, are also called 7TM receptors). The polytopic structure of GPCRs makes the folding of GPCRs difficult and complex. Indeed, many wild-type GPCRs are not folded optimally, and defects in folding are the most common cause of genetic diseases due to GPCR mutations. Both general and receptor-specific molecular chaperones aid the folding of GPCRs. Chemical chaperones have been shown to be able to correct the misfolding in mutant GPCRs, proving to be important tools for studying the structure-function relationship of GPCRs. However, their potential therapeutic value is very limited. Pharmacological chaperones (pharmacoperones) are potentially important novel therapeutics for treating genetic diseases caused by mutations in GPCR genes that resulted in misfolded mutant proteins. Pharmacoperones also increase cell surface expression of wild-type GPCRs; therefore, they could be used to treat diseases that do not harbor mutations in GPCRs. Recent studies have shown that indeed pharmacoperones work in both experimental animals and patients. High-throughput assays have been developed to identify new pharmacoperones that could be used as therapeutics for a number of endocrine and other genetic diseases.
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Affiliation(s)
- Ya-Xiong Tao
- Department of Anatomy, Physiology, and Pharmacology (Y.-X.T.), College of Veterinary Medicine, Auburn University, Auburn, Alabama 36849-5519; and Departments of Internal Medicine and Cell Biology (P.M.C.), Texas Tech University Health Science Center, Lubbock, Texas 79430-6252
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41
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Athanasiou D, Bevilacqua D, Aguila M, McCulley C, Kanuga N, Iwawaki T, Chapple JP, Cheetham ME. The co-chaperone and reductase ERdj5 facilitates rod opsin biogenesis and quality control. Hum Mol Genet 2014; 23:6594-606. [PMID: 25055872 PMCID: PMC4240209 DOI: 10.1093/hmg/ddu385] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Mutations in rhodopsin, the light-sensitive protein of rod cells, are the most common cause of autosomal dominant retinitis pigmentosa (ADRP). Many rod opsin mutations, such as P23H, lead to misfolding of rod opsin with detrimental effects on photoreceptor function and viability. Misfolded P23H rod opsin and other mutations in the intradiscal domain are characterized by the formation of an incorrect disulphide bond between C185 and C187, as opposed to the correct and highly conserved C110–C187 disulphide bond. Therefore, we tested the hypothesis that incorrect disulphide bond formation might be a factor that affects the biogenesis of rod opsin by studying wild-type (WT) or P23H rod opsin in combination with amino acid substitutions that prevent the formation of incorrect disulphide bonds involving C185. These mutants had altered traffic dynamics, suggesting a requirement for regulation of disulphide bond formation/reduction during rod opsin biogenesis. Here, we show that the BiP co-chaperone and reductase protein ERdj5 (DNAJC10) regulates this process. ERdj5 overexpression promoted the degradation, improved the endoplasmic reticulum mobility and prevented the aggregation of P23H rod opsin. ERdj5 reduction by shRNA delayed rod opsin degradation and promoted aggregation. The reductase and co-chaperone activity of ERdj5 were both required for these effects on P23H rod opsin. Furthermore, mutations in these functional domains acted as dominant negatives that affected WT rod opsin biogenesis. Collectively, these data identify ERdj5 as a member of the proteostasis network that regulates rod opsin biogenesis and supports a role for disulphide bond formation/reduction in rod opsin biogenesis and disease.
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Affiliation(s)
| | | | | | | | | | - Takao Iwawaki
- Advanced Scientific Research Leaders Development Unit, Gunma University, Maebashi, Gunma 371-8511, Japan and
| | - J Paul Chapple
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, UK
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Rosenbaum EE, Vasiljevic E, Brehm KS, Colley NJ. Mutations in four glycosyl hydrolases reveal a highly coordinated pathway for rhodopsin biosynthesis and N-glycan trimming in Drosophila melanogaster. PLoS Genet 2014; 10:e1004349. [PMID: 24785692 PMCID: PMC4006722 DOI: 10.1371/journal.pgen.1004349] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 03/18/2014] [Indexed: 01/16/2023] Open
Abstract
As newly synthesized glycoproteins move through the secretory pathway, the asparagine-linked glycan (N-glycan) undergoes extensive modifications involving the sequential removal and addition of sugar residues. These modifications are critical for the proper assembly, quality control and transport of glycoproteins during biosynthesis. The importance of N-glycosylation is illustrated by a growing list of diseases that result from defects in the biosynthesis and processing of N-linked glycans. The major rhodopsin in Drosophila melanogaster photoreceptors, Rh1, is highly unique among glycoproteins, as the N-glycan appears to be completely removed during Rh1 biosynthesis and maturation. However, much of the deglycosylation pathway for Rh1 remains unknown. To elucidate the key steps in Rh1 deglycosylation in vivo, we characterized mutant alleles of four Drosophila glycosyl hydrolases, namely α-mannosidase-II (α-Man-II), α-mannosidase-IIb (α-Man-IIb), a β-N-acetylglucosaminidase called fused lobes (Fdl), and hexosaminidase 1 (Hexo1). We have demonstrated that these four enzymes play essential and unique roles in a highly coordinated pathway for oligosaccharide trimming during Rh1 biosynthesis. Our results reveal that α-Man-II and α-Man-IIb are not isozymes like their mammalian counterparts, but rather function at distinct stages in Rh1 maturation. Also of significance, our results indicate that Hexo1 has a biosynthetic role in N-glycan processing during Rh1 maturation. This is unexpected given that in humans, the hexosaminidases are typically lysosomal enzymes involved in N-glycan catabolism with no known roles in protein biosynthesis. Here, we present a genetic dissection of glycoprotein processing in Drosophila and unveil key steps in N-glycan trimming during Rh1 biosynthesis. Taken together, our results provide fundamental advances towards understanding the complex and highly regulated pathway of N-glycosylation in vivo and reveal novel insights into the functions of glycosyl hydrolases in the secretory pathway.
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Affiliation(s)
- Erica E. Rosenbaum
- Department of Ophthalmology & Visual Sciences and Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Eva Vasiljevic
- Department of Ophthalmology & Visual Sciences and Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Kimberley S. Brehm
- Department of Ophthalmology & Visual Sciences and Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Nansi Jo Colley
- Department of Ophthalmology & Visual Sciences and Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail:
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Wang S, Tan KL, Agosto MA, Xiong B, Yamamoto S, Sandoval H, Jaiswal M, Bayat V, Zhang K, Charng WL, David G, Duraine L, Venkatachalam K, Wensel TG, Bellen HJ. The retromer complex is required for rhodopsin recycling and its loss leads to photoreceptor degeneration. PLoS Biol 2014; 12:e1001847. [PMID: 24781186 PMCID: PMC4004542 DOI: 10.1371/journal.pbio.1001847] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 03/21/2014] [Indexed: 12/22/2022] Open
Abstract
Rhodopsin recycling via the retromer, rather than degradation through lysosomes, can alleviate light-induced photoreceptor degeneration in Drosophila. Rhodopsin mistrafficking can cause photoreceptor (PR) degeneration. Upon light exposure, activated rhodopsin 1 (Rh1) in Drosophila PRs is internalized via endocytosis and degraded in lysosomes. Whether internalized Rh1 can be recycled is unknown. Here, we show that the retromer complex is expressed in PRs where it is required for recycling endocytosed Rh1 upon light stimulation. In the absence of subunits of the retromer, Rh1 is processed in the endolysosomal pathway, leading to a dramatic increase in late endosomes, lysosomes, and light-dependent PR degeneration. Reducing Rh1 endocytosis or Rh1 levels in retromer mutants alleviates PR degeneration. In addition, increasing retromer abundance suppresses degenerative phenotypes of mutations that affect the endolysosomal system. Finally, expressing human Vps26 suppresses PR degeneration in Vps26 mutant PRs. We propose that the retromer plays a conserved role in recycling rhodopsins to maintain PR function and integrity. Upon light exposure, rhodopsins—light-sensing proteins in the eye—trigger visual transduction signaling to activate fly photoreceptor cells. After activation, rhodopsins can be internalized from the cell surface into endosomes and then degraded in lysosomes. This mechanism prevents constant activation of the visual transduction pathway, thereby maintaining the function and integrity of photoreceptor cells. It is not known, however, whether these internalized rhodopsins can be recycled. Here, we show that the retromer, an evolutionarily conserved protein complex, is required for the recycling of rhodopsins. We find that loss of key retromer subunits (Vps35 or Vps26) causes rhodopsin mislocalization in the photoreceptors and severe light-induced photoreceptor degeneration. Conversely, gain of retromer subunits can alleviate photoreceptor degeneration in some contexts. Human retromer components can stand in for depleted fruit fly retromer, suggesting that this complex plays a role in recycling light sensors in both vertebrate and invertebrate photoreceptors.
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Affiliation(s)
- Shiuan Wang
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Kai Li Tan
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Melina A. Agosto
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Bo Xiong
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Shinya Yamamoto
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Human and Molecular Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas, United States of America
| | - Hector Sandoval
- Department of Human and Molecular Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Manish Jaiswal
- Department of Human and Molecular Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas, United States of America
| | - Vafa Bayat
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Ke Zhang
- Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Wu-Lin Charng
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Gabriela David
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Lita Duraine
- Department of Human and Molecular Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas, United States of America
| | - Kartik Venkatachalam
- Department of Integrative Biology and Pharmacology, University of Texas School of Medicine, Houston, Texas, United States of America
| | - Theodore G. Wensel
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Hugo J. Bellen
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Human and Molecular Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas, United States of America
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas, United States of America
- Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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Proteomic survey reveals altered energetic patterns and metabolic failure prior to retinal degeneration. J Neurosci 2014; 34:2797-812. [PMID: 24553922 DOI: 10.1523/jneurosci.2982-13.2014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Inherited mutations that lead to misfolding of the visual pigment rhodopsin (Rho) are a prominent cause of photoreceptor neuron (PN) degeneration and blindness. How Rho proteotoxic stress progressively impairs PN viability remains unknown. To identify the pathways that mediate Rho toxicity in PNs, we performed a comprehensive proteomic profiling of retinas from Drosophila transgenics expressing Rh1(P37H), the equivalent of mammalian Rho(P23H), the most common Rho mutation linked to blindness in humans. Profiling of young Rh1(P37H) retinas revealed a coordinated upregulation of energy-producing pathways and attenuation of energy-consuming pathways involving target of rapamycin (TOR) signaling, which was reversed in older retinas at the onset of PN degeneration. We probed the relevance of these metabolic changes to PN survival by using a combination of pharmacological and genetic approaches. Chronic suppression of TOR signaling, using the inhibitor rapamycin, strongly mitigated PN degeneration, indicating that TOR signaling activation by chronic Rh1(P37H) proteotoxic stress is deleterious for PNs. Genetic inactivation of the endoplasmic reticulum stress-induced JNK/TRAF1 axis as well as the APAF-1/caspase-9 axis, activated by damaged mitochondria, dramatically suppressed Rh1(P37H)-induced PN degeneration, identifying the mitochondria as novel mediators of Rh1(P37H) toxicity. We thus propose that chronic Rh1(P37H) proteotoxic stress distorts the energetic profile of PNs leading to metabolic imbalance, mitochondrial failure, and PN degeneration and therapies normalizing metabolic function might be used to alleviate Rh1(P37H) toxicity in the retina. Our study offers a glimpse into the intricate higher order interactions that underlie PN dysfunction and provides a useful resource for identifying other molecular networks that mediate Rho toxicity in PNs.
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Zhang B, Shen XL, Liang R, Li Y, Huang K, Zhao C, Luo Y, Xu W. Protective role of the mitochondrial Lon protease 1 in ochratoxin A-induced cytotoxicity in HEK293 cells. J Proteomics 2014; 101:154-68. [PMID: 24565693 DOI: 10.1016/j.jprot.2014.02.017] [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: 12/13/2013] [Revised: 01/29/2014] [Accepted: 02/15/2014] [Indexed: 11/26/2022]
Abstract
UNLABELLED Ochratoxin A (OTA) is a common kind of mycotoxin and food contaminant, which has various toxicological effects, especially nephrotoxicity. Our previous work about OTA-induced renal cytotoxicity indicated that mitochondrial Lon Protease 1 (Lonp1) might play a protective role. Lonp1 is a multifunctional ATP-dependent protease which mainly participates in mitochondrial proteolysis and protein quality control. The study aimed at probing how Lonp1 functioned in OTA-induced renal cytotoxicity. By means of RNA interference, we down-regulated the expression of Lonp1 in HEK293 cells. Cell viability results revealed that cells with Lonp1 deficiency were more vulnerable to OTA. Then we identified differentially expressed proteins between Lonp1 knock-down cells and scrambled control both in the absence and presence of OTA, using iTRAQ-based quantitative proteomics approach. Thirty-four proteins were differentially expressed as a result of Lonp1 deficiency, while forty-four proteins were differentially expressed in response to both Lonp1 deficiency and OTA treatment. By function summary and pathway analysis, we presumed that Lonp1 realized its protective function in the resistance to OTA-induced renal cytotoxicity via 4 processes: defensing against OTA-induced oxidative stress in the mitochondria; regulating protein synthesis, modification and repair; maintaining the balance of carbohydrate metabolism; and assisting in mtDNA maintenance. BIOLOGICAL SIGNIFICANCE OTA is a kind of mycotoxin that seriously threatens human health and has various toxicological effects. However, the mechanisms of its toxicity have not been exactly elucidated yet. The method of combination of RNAi and iTRAQ-based quantitative proteomics paves the way to gain a better understanding of the toxicity mechanisms of OTA. The present study, for the first time, verified the protective role of Lonp1 in OTA-induced renal cytotoxicity and clarified the defensive mechanism. Proteomic changes in Lonp1 deficient cells induced by OTA added new knowledge to OTA cytotoxicity.
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Affiliation(s)
- Boyang Zhang
- Laboratory of food safety and Molecular Biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, PR China
| | - Xiao Li Shen
- Laboratory of food safety and Molecular Biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, PR China; School of Public Health, Zunyi Medical University, Zunyi, Guizhou 563003, PR China
| | - Rui Liang
- Laboratory of food safety and Molecular Biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, PR China
| | - Yuzhe Li
- Laboratory of food safety and Molecular Biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, PR China
| | - Kunlun Huang
- Laboratory of food safety and Molecular Biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, PR China
| | - Changhui Zhao
- Department of Nutrition and Food Science, University of Maryland, College Park, MD 20742, USA
| | - Yunbo Luo
- Laboratory of food safety and Molecular Biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, PR China
| | - Wentao Xu
- Laboratory of food safety and Molecular Biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, PR China.
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Coelho DS, Cairrão F, Zeng X, Pires E, Coelho AV, Ron D, Ryoo HD, Domingos PM. Xbp1-independent Ire1 signaling is required for photoreceptor differentiation and rhabdomere morphogenesis in Drosophila. Cell Rep 2013; 5:791-801. [PMID: 24183663 PMCID: PMC3858604 DOI: 10.1016/j.celrep.2013.09.046] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 08/28/2013] [Accepted: 09/30/2013] [Indexed: 10/26/2022] Open
Abstract
The unfolded protein response (UPR) is composed by homeostatic signaling pathways that are activated by excessive protein misfolding in the endoplasmic reticulum. Ire1 signaling is an important mediator of the UPR, leading to the activation of the transcription factor Xbp1. Here, we show that Drosophila Ire1 mutant photoreceptors have defects in the delivery of rhodopsin-1 to the rhabdomere and in the secretion of Spacemaker/Eyes Shut into the interrhabdomeral space. However, these defects are not observed in Xbp1 mutant photoreceptors. Ire1 mutant retinas have higher mRNA levels for targets of regulated Ire1-dependent decay (RIDD), including for the fatty acid transport protein (fatp). Importantly, the downregulation of fatp by RNAi rescues the rhodopsin-1 delivery defects observed in Ire1 mutant photoreceptors. Our results show that the role of Ire1 during photoreceptor differentiation is independent of Xbp1 function and demonstrate the physiological relevance of the RIDD mechanism in this specific paradigm.
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Affiliation(s)
- Dina S. Coelho
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Fatima Cairrão
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Xiaomei Zeng
- Department of Cell Biology, New York University School of Medicine, 550 First Avenue, New York, New York 10016, USA
| | - Elisabete Pires
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Ana V. Coelho
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - David Ron
- University of Cambridge, Metabolic Research Laboratory and NIHR Cambridge Biomedical Research Centre, Addenbrooke’s Hospital, Cambridge CB2 0QQ, UK
| | - Hyung Don Ryoo
- Department of Cell Biology, New York University School of Medicine, 550 First Avenue, New York, New York 10016, USA
| | - Pedro M. Domingos
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
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Xiong B, Bellen HJ. Rhodopsin homeostasis and retinal degeneration: lessons from the fly. Trends Neurosci 2013; 36:652-60. [PMID: 24012059 DOI: 10.1016/j.tins.2013.08.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2013] [Revised: 08/02/2013] [Accepted: 08/12/2013] [Indexed: 11/16/2022]
Abstract
Rhodopsins (Rh) are G protein-coupled receptors that function as light-sensors in photoreceptors. In humans, Rh mutations cause retinitis pigmentosa (RP), a degenerative disease that ultimately results in blindness. Studies in Drosophila have provided many insights into basic Rh biology and have identified pathways that lead to retinal degeneration. It has been shown that, because Rh is very abundant in photoreceptors, its accumulation in numerous organelles induces severe stress and results in degeneration of these cells. Moreover, genetic lesions that affect proper activation of membrane-bound Rh lead to disruption in Ca(2+) homeostasis which also causes photoreceptor degeneration. We review here the molecular signals involved in Rh homeostasis and the mechanisms underlying retinal degeneration in flies, and discuss possible links to human diseases.
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Affiliation(s)
- Bo Xiong
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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Athanasiou D, Aguilà M, Bevilacqua D, Novoselov SS, Parfitt DA, Cheetham ME. The cell stress machinery and retinal degeneration. FEBS Lett 2013; 587:2008-17. [PMID: 23684651 PMCID: PMC4471140 DOI: 10.1016/j.febslet.2013.05.020] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 05/01/2013] [Accepted: 05/02/2013] [Indexed: 12/12/2022]
Abstract
Retinal degenerations are a group of clinically and genetically heterogeneous disorders characterised by progressive loss of vision due to neurodegeneration. The retina is a highly specialised tissue with a unique architecture and maintaining homeostasis in all the different retinal cell types is crucial for healthy vision. The retina can be exposed to a variety of environmental insults and stress, including light-induced damage, oxidative stress and inherited mutations that can lead to protein misfolding. Within retinal cells there are different mechanisms to cope with disturbances in proteostasis, such as the heat shock response, the unfolded protein response and autophagy. In this review, we discuss the multiple responses of the retina to different types of stress involved in retinal degenerations, such as retinitis pigmentosa, age-related macular degeneration and glaucoma. Understanding the mechanisms that maintain and re-establish proteostasis in the retina is important for developing new therapeutic approaches to fight blindness.
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Affiliation(s)
| | - Monica Aguilà
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
| | - Dalila Bevilacqua
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
| | | | - David A. Parfitt
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
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Chu B, Postma M, Hardie R. Fractional Ca(2+) currents through TRP and TRPL channels in Drosophila photoreceptors. Biophys J 2013; 104:1905-16. [PMID: 23663833 PMCID: PMC3647204 DOI: 10.1016/j.bpj.2013.03.047] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 03/05/2013] [Accepted: 03/25/2013] [Indexed: 01/29/2023] Open
Abstract
Light responses in Drosophila photoreceptors are mediated by two Ca(2+) permeable cation channels, transient receptor potential (TRP) and TRP-like (TRPL). Although Ca(2+) influx via these channels is critical for amplification, inactivation, and light adaptation, the fractional contribution of Ca(2+) to the currents (Pf) has not been measured. We describe a slow (τ ∼ 350 ms) tail current in voltage-clamped light responses and show that it is mediated by electrogenic Na(+)/Ca(2+) exchange. Assuming a 3Na:1Ca stoichiometry, we derive empirical estimates of Pf by comparing the charge integrals of the exchanger and light-induced currents. For TRPL channels, Pf was ∼17% as predicted by Goldman-Hodgkin-Katz (GHK) theory. Pf for TRP (29%) and wild-type flies (26%) was higher, but lower than the GHK prediction (45% and 42%). As predicted by GHK theory, Pf for both channels increased with extracellular [Ca(2+)], and was largely independent of voltage between -100 and -30 mV. A model incorporating intra- and extracellular geometry, ion permeation, diffusion, extrusion, and buffering suggested that the deviation from GHK predictions was largely accounted for by extracellular ionic depletion during the light-induced currents, and the time course of the Na(+)/Ca(2+) exchange current could be used to obtain estimates of cellular Ca(2+) buffering capacities.
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Affiliation(s)
- Brian Chu
- Department of Physiology, Development and Neuroscience, Cambridge University, Cambridge, UK
| | - Marten Postma
- Section of Molecular Cytology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Roger C. Hardie
- Department of Physiology, Development and Neuroscience, Cambridge University, Cambridge, UK
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Tian Y, Li T, Sun M, Wan D, Li Q, Li P, Zhang Z, Han J, Xie W. Neurexin Regulates Visual Function via Mediating Retinoid Transport to Promote Rhodopsin Maturation. Neuron 2013; 77:311-22. [DOI: 10.1016/j.neuron.2012.11.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/07/2012] [Indexed: 12/22/2022]
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