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Ren L, Xu P, Yao J, Wang Z, Shi K, Han W, Wang H. Targeting the Mitochondria with Pseudo-Stealthy Nanotaxanes to Impair Mitochondrial Biogenesis for Effective Cancer Treatment. ACS NANO 2022; 16:10242-10259. [PMID: 35820199 DOI: 10.1021/acsnano.1c08008] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The clinical success of anticancer therapy is usually limited by drug resistance and the metastatic dissemination of cancer cells. Mitochondria are essential generators of cellular energy and play a crucial role in sustaining cell survival and metastatic escape. Selective drug strategies targeting mitochondria are able to rewire mitochondrial metabolism and may provide an alternative paradigm to treat many aggressive cancers with high efficiency and low toxicity. Here, we present a pseudo-stealthy mitochondria-targeted pro-nanotaxane and test it against recurrent and metastatic tumor xenografts. The nanoparticle encapsulates a mitochondria-targetable pro-taxane agent, which can be converted into the chemically unmodified cabazitaxel drug, with further surface cloaking with a low-density lipophilic triphenylphosphonium cation. The resultant nanotaxane could be effectively taken up by cells and consequently specifically localized to the mitochondria. The in situ activated cabazitaxel causes mitochondrial dysfunction and ultimately results in potent cell apoptosis. After intravenous administration to animals, pro-nanotaxane mimics the stealthy behavior of polyethylene glycol-cloaked nanoparticles to provide a long circulation time. The antitumor efficacy of this mitochondria-targeted system was validated in multiple preclinical drug-resistant tumor models. Notably, in a patient-derived metastatic melanoma model that was initially pretreated with cabazitaxel, nanotaxane administration not only produced durable tumor reduction but also substantially suppressed metastatic recurrence. Taken together, these results demonstrate that this combination of a pseudo-stealthy platform with a rationally designed pro-drug is an attractive approach to target mitochondria and enhance drug efficacy.
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Affiliation(s)
- Lulu Ren
- NHC Key Laboratory of Combined Multi-Organ Transplantation, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003, People's Republic of China
- Jinan Microecological Biomedicine Shandong Laboratory, Jinan, Shandong 250117, People's Republic of China
- Department of Medical Oncology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310016, People's Republic of China
| | - Peirong Xu
- NHC Key Laboratory of Combined Multi-Organ Transplantation, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003, People's Republic of China
- Department of Chemical Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China
| | - Jie Yao
- NHC Key Laboratory of Combined Multi-Organ Transplantation, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003, People's Republic of China
- Department of Chemical Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, People's Republic of China
| | - Zihan Wang
- College of Animal Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, People's Republic of China
| | - Kewei Shi
- NHC Key Laboratory of Combined Multi-Organ Transplantation, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003, People's Republic of China
| | - Weidong Han
- Department of Medical Oncology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310016, People's Republic of China
| | - Hangxiang Wang
- NHC Key Laboratory of Combined Multi-Organ Transplantation, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003, People's Republic of China
- Jinan Microecological Biomedicine Shandong Laboratory, Jinan, Shandong 250117, People's Republic of China
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2
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Cheung CY, Huang TT, Chow N, Zhang S, Zhao Y, Chau MP, Chan WC, Wong CCL, Boassa D, Phan S, Ellisman MH, Yates JR, Xu S, Yu Z, Zhang Y, Zhang R, Ng LL, Ko BCB. Unconventional tonicity-regulated nuclear trafficking of NFAT5 mediated by KPNB1, XPOT and RUVBL2. J Cell Sci 2022; 135:275560. [PMID: 35635291 PMCID: PMC9377714 DOI: 10.1242/jcs.259280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 05/20/2022] [Indexed: 11/20/2022] Open
Abstract
NFAT5 is the only known mammalian tonicity-responsive transcription factor with essential role in cellular adaptation to hypertonic stress. It is also implicated in diverse physiological and pathological processes. NFAT5 activity is tightly regulated by extracellular tonicity, but the underlying mechanisms remain elusive. We demonstrated that NFAT5 enters the nucleus via the nuclear pore complex. We found that NFAT5 utilizes a unique nuclear localization signal (NFAT5-NLS) for nuclear import. siRNA screening revealed that only karyopherin β1 (KPNB1), but not karyopherin alpha, is responsible for the nuclear import of NFAT5 via direct interaction with the NFAT5-NLS. Proteomics analysis and siRNA screening further revealed that nuclear export of NFAT5 under hypotonicity is driven by Exportin-T, where the process requires RuvB-Like AAA type ATPase 2 (RUVBL2) as an indispensable chaperone. Our findings have identified an unconventional tonicity-dependent nucleocytoplasmic trafficking pathway for NFAT5, a critical step in orchestrating rapid cellular adaptation to change in extracellular tonicity. These findings offer an opportunity for the development of novel NFAT5 targeting strategies that are potentially useful for the treatment of diseases associated with NFAT5 dysregulation.
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Affiliation(s)
- Chris Y Cheung
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, China.,State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hong Kong, China
| | - Ting-Ting Huang
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, China.,State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hong Kong, China
| | - Ning Chow
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, China.,State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hong Kong, China
| | - Shuqi Zhang
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, China.,State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hong Kong, China
| | - Yanxiang Zhao
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, China.,State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hong Kong, China
| | - Mary P Chau
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, China.,State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hong Kong, China
| | - Wing Cheung Chan
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, China.,State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hong Kong, China
| | - Catherine C L Wong
- Center for Precision Medicine Muti-Omics Research, Health Science Center, Peking University, China Clinical Laboratory Department, The Cancer Hospital of the University of Chinese Academy of Sciences, Beijing, China
| | - Daniela Boassa
- Department of Neurosciences, University of California, San Diego, USA.,Center for Research in Biological Systems, National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, California, USA
| | - Sebastien Phan
- Department of Neurosciences, University of California, San Diego, USA.,Center for Research in Biological Systems, National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, California, USA
| | - Mark H Ellisman
- Department of Neurosciences, University of California, San Diego, USA.,Center for Research in Biological Systems, National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, California, USA
| | - John R Yates
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California, USA
| | - SongXiao Xu
- The Clinical Laboratory Department, The Cancer Hospital of the University of Chinese Academy of Sciences (Zhejiang Cancer Hospital), Institute of Basic Medicine and Cancer, Chinese Academy of Sciences, Hangzhou, Zhejiang, China
| | - Zicheng Yu
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, China.,State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hong Kong, China
| | - Yajing Zhang
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, China.,State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hong Kong, China
| | - Rui Zhang
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, China.,State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hong Kong, China
| | - Ling Ling Ng
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, China.,State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hong Kong, China
| | - Ben C B Ko
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, China.,State Key Laboratory of Chemical Biology and Drug Discovery, The Hong Kong Polytechnic University, Hong Kong, China
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3
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de Los Ángeles Juricic Urzúa M, Gallardo Rojas J, Couve Correa A, Cerda M, Härtel Gründler S, González-Silva C. The Dendritic Ergic: Microtubule And Actin Cytoskeletons Participate In Stop-And-Go Movement Of Mobile Carriers Between Stable Structures. Traffic 2022; 23:174-187. [PMID: 35075729 DOI: 10.1111/tra.12832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 12/30/2021] [Accepted: 01/20/2022] [Indexed: 11/29/2022]
Abstract
The ER-to-Golgi intermediate compartment (ERGIC) is a membranous organelle that mediates protein transport between the endoplasmic reticulum (ER) and the Golgi apparatus. In neurons, clusters of these vesiculotubular structures are situated throughout the cell in proximity to the ER, passing cargo to the cis-Golgi cisternae, located mainly in the perinuclear region. Although ERGIC markers have been identified in neurons, the distribution and dynamics of neuronal ERGIC structures have not been characterized yet. Here, we show that long-distance ERGIC transport occurs via an intermittent mechanism in dendrites, with mobile elements moving between stationary structures. Slow and fast live-cell imaging have captured stable ERGIC structures remaining in place over long periods of time, as well as mobile ERGIC structures advancing very short distances along dendrites. These short distances have been consistent with the lengths between the stationary ERGIC structures. Kymography revealed ERGIC elements that moved intermittently, emerging from and fusing with stationary ERGIC structures. Interestingly, this movement apparently depends not only on the integrity of the microtubule cytoskeleton, as previously reported, but on the actin cytoskeleton as well. Our results indicate that the dendritic ERGIC has a dual nature, with both stationary and mobile structures. The neural ERGIC network transports proteins via a stop-and-go movement in which both the microtubule and the actin cytoskeletons participate. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- María de Los Ángeles Juricic Urzúa
- Neuroscience Department, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute (BNI), Santiago, Chile
| | - Javiera Gallardo Rojas
- Neuroscience Department, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute (BNI), Santiago, Chile
| | - Andrés Couve Correa
- Neuroscience Department, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute (BNI), Santiago, Chile
| | - Mauricio Cerda
- Biomedical Neuroscience Institute (BNI), Santiago, Chile.,Integrative Biology Program, Institute of Biomedical Sciences (ICBM), Center for Medical Informatics and Telemedicine (CIMT), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Steffen Härtel Gründler
- Biomedical Neuroscience Institute (BNI), Santiago, Chile.,Integrative Biology Program, Institute of Biomedical Sciences (ICBM), Center for Medical Informatics and Telemedicine (CIMT), Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Carolina González-Silva
- Neuroscience Department, Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute (BNI), Santiago, Chile
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4
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Abstract
In plants, GABA plays a critical role in sexual plant reproduction; however, GABA receptors and the associated detailed signaling mechanisms remain to be elucidated. Our experiments show that the proposed technique is reliable and convenient for probing GABA-binding proteins and could be applicable in similar projects by covalently immobilizing the free carboxylic group of GABA on magnetic beads (SiMAG-Carboxyl). New probes produced by covalently immobilizing the free carboxylic group of GABA on magnetic beads (SiMAG-Carboxyl) can obtain useful information on GABA receptors in plants.
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Affiliation(s)
- Jie Zou
- Guiyang College of Traditional Chinese Medicine, Guiyang, China
| | - Jingzhe Guo
- College of Life Science, State Key Laboratory of Plant Hybrid Rice, Wuhan University, Wuhan, China
| | - Shisheng Li
- Key Laboratories of Economic Forest Germplasm Improvement and Comprehensive Resources Utilization of Hubei Province, College of Life Science, Huanggang Normal University, Huanggang, China
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5
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Ca 2+ signals initiate at immobile IP 3 receptors adjacent to ER-plasma membrane junctions. Nat Commun 2017; 8:1505. [PMID: 29138405 PMCID: PMC5686115 DOI: 10.1038/s41467-017-01644-8] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 10/06/2017] [Indexed: 11/08/2022] Open
Abstract
IP3 receptors (IP3Rs) release Ca2+ from the ER when they bind IP3 and Ca2+. The spatial organization of IP3Rs determines both the propagation of Ca2+ signals between IP3Rs and the selective regulation of cellular responses. Here we use gene editing to fluorescently tag endogenous IP3Rs, and super-resolution microscopy to determine the geography of IP3Rs and Ca2+ signals within living cells. We show that native IP3Rs cluster within ER membranes. Most IP3R clusters are mobile, moved by diffusion and microtubule motors. Ca2+ signals are generated by a small population of immobile IP3Rs. These IP3Rs are licensed to respond, but they do not readily mix with mobile IP3Rs. The licensed IP3Rs reside alongside ER-plasma membrane junctions where STIM1, which regulates store-operated Ca2+ entry, accumulates after depletion of Ca2+ stores. IP3Rs tethered close to ER-plasma membrane junctions are licensed to respond and optimally placed to be activated by endogenous IP3 and to regulate Ca2+ entry. IP3 receptors mediate Ca2+ release from the endoplasmic reticulum. Here the authors show that only a small fraction of IP3 receptors initiate Ca2+ signals; these immobile IP3 receptors adjacent to the plasma membrane are optimally placed to control STIM1-dependent Ca2+ entry.
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6
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Lelieveld SH, Wiel L, Venselaar H, Pfundt R, Vriend G, Veltman JA, Brunner HG, Vissers LE, Gilissen C. Spatial Clustering of de Novo Missense Mutations Identifies Candidate Neurodevelopmental Disorder-Associated Genes. Am J Hum Genet 2017; 101:478-484. [PMID: 28867141 DOI: 10.1016/j.ajhg.2017.08.004] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 08/04/2017] [Indexed: 10/19/2022] Open
Abstract
Haploinsufficiency (HI) is the best characterized mechanism through which dominant mutations exert their effect and cause disease. Non-haploinsufficiency (NHI) mechanisms, such as gain-of-function and dominant-negative mechanisms, are often characterized by the spatial clustering of mutations, thereby affecting only particular regions or base pairs of a gene. Variants leading to haploinsufficency might occasionally cluster as well, for example in critical domains, but such clustering is on the whole less pronounced with mutations often spread throughout the gene. Here we exploit this property and develop a method to specifically identify genes with significant spatial clustering patterns of de novo mutations in large cohorts. We apply our method to a dataset of 4,061 de novo missense mutations from published exome studies of trios with intellectual disability and developmental disorders (ID/DD) and successfully identify 15 genes with clustering mutations, including 12 genes for which mutations are known to cause neurodevelopmental disorders. For 11 out of these 12, NHI mutation mechanisms have been reported. Additionally, we identify three candidate ID/DD-associated genes of which two have an established role in neuronal processes. We further observe a higher intolerance to normal genetic variation of the identified genes compared to known genes for which mutations lead to HI. Finally, 3D modeling of these mutations on their protein structures shows that 81% of the observed mutations are unlikely to affect the overall structural integrity and that they therefore most likely act through a mechanism other than HI.
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7
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Woehlbier U, Colombo A, Saaranen MJ, Pérez V, Ojeda J, Bustos FJ, Andreu CI, Torres M, Valenzuela V, Medinas DB, Rozas P, Vidal RL, Lopez-Gonzalez R, Salameh J, Fernandez-Collemann S, Muñoz N, Matus S, Armisen R, Sagredo A, Palma K, Irrazabal T, Almeida S, Gonzalez-Perez P, Campero M, Gao FB, Henny P, van Zundert B, Ruddock LW, Concha ML, Henriquez JP, Brown RH, Hetz C. ALS-linked protein disulfide isomerase variants cause motor dysfunction. EMBO J 2016; 35:845-65. [PMID: 26869642 PMCID: PMC4972141 DOI: 10.15252/embj.201592224] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Revised: 12/27/2015] [Accepted: 01/05/2016] [Indexed: 12/11/2022] Open
Abstract
Disturbance of endoplasmic reticulum (ER) proteostasis is a common feature of amyotrophic lateral sclerosis (ALS). Protein disulfide isomerases (PDIs) areERfoldases identified as possibleALSbiomarkers, as well as neuroprotective factors. However, no functional studies have addressed their impact on the disease process. Here, we functionally characterized fourALS-linked mutations recently identified in two majorPDIgenes,PDIA1 andPDIA3/ERp57. Phenotypic screening in zebrafish revealed that the expression of thesePDIvariants induce motor defects associated with a disruption of motoneuron connectivity. Similarly, the expression of mutantPDIs impaired dendritic outgrowth in motoneuron cell culture models. Cellular and biochemical studies identified distinct molecular defects underlying the pathogenicity of thesePDImutants. Finally, targetingERp57 in the nervous system led to severe motor dysfunction in mice associated with a loss of neuromuscular synapses. This study identifiesERproteostasis imbalance as a risk factor forALS, driving initial stages of the disease.
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Affiliation(s)
- Ute Woehlbier
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile Program of Cellular and Molecular Biology, Center for Molecular Studies of the Cell, Institute of Biomedical Sciences, University of Chile, Santiago, Chile Center for Genomics and Bioinformatics, Universidad Mayor, Santiago, Chile
| | - Alicia Colombo
- Program of Anatomy and Developmental Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile Department of Pathological Anatomy, Hospital Clínico, University of Chile, Santiago, Chile
| | - Mirva J Saaranen
- Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Viviana Pérez
- Department of Cell Biology, Faculty of Biological Sciences, Millennium Nucleus of Regenerative Biology, Center for Advanced Microscopy (CMA Bio-Bio), Universidad de Concepción, Concepción, Chile
| | - Jorge Ojeda
- Department of Cell Biology, Faculty of Biological Sciences, Millennium Nucleus of Regenerative Biology, Center for Advanced Microscopy (CMA Bio-Bio), Universidad de Concepción, Concepción, Chile
| | - Fernando J Bustos
- Faculty of Biological Sciences and Faculty of Medicine, Center for Biomedical Research, Universidad Andres Bello, Santiago, Chile
| | - Catherine I Andreu
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile Program of Cellular and Molecular Biology, Center for Molecular Studies of the Cell, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Mauricio Torres
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile Program of Cellular and Molecular Biology, Center for Molecular Studies of the Cell, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Vicente Valenzuela
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile Program of Cellular and Molecular Biology, Center for Molecular Studies of the Cell, Institute of Biomedical Sciences, University of Chile, Santiago, Chile Center for Geroscience, Brain Health and Metabolism, Santiago, Chile
| | - Danilo B Medinas
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile Program of Cellular and Molecular Biology, Center for Molecular Studies of the Cell, Institute of Biomedical Sciences, University of Chile, Santiago, Chile Center for Geroscience, Brain Health and Metabolism, Santiago, Chile
| | - Pablo Rozas
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile Program of Cellular and Molecular Biology, Center for Molecular Studies of the Cell, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Rene L Vidal
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile Center for Geroscience, Brain Health and Metabolism, Santiago, Chile Neurounion Biomedical Foundation, CENPAR, Santiago, Chile
| | | | - Johnny Salameh
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA
| | | | - Natalia Muñoz
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile Center for Geroscience, Brain Health and Metabolism, Santiago, Chile Neurounion Biomedical Foundation, CENPAR, Santiago, Chile
| | - Soledad Matus
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile Center for Geroscience, Brain Health and Metabolism, Santiago, Chile Neurounion Biomedical Foundation, CENPAR, Santiago, Chile
| | - Ricardo Armisen
- Program of Cellular and Molecular Biology, Center for Molecular Studies of the Cell, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Alfredo Sagredo
- Program of Cellular and Molecular Biology, Center for Molecular Studies of the Cell, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Karina Palma
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile Program of Cellular and Molecular Biology, Center for Molecular Studies of the Cell, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Thergiory Irrazabal
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile Program of Cellular and Molecular Biology, Center for Molecular Studies of the Cell, Institute of Biomedical Sciences, University of Chile, Santiago, Chile
| | - Sandra Almeida
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Paloma Gonzalez-Perez
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Mario Campero
- Department of Neurology and Neurosurgery, Faculty of Medicine, University of Chile, Santiago, Chile Faculty of Medicine, Clínica Alemana, Universidad del Desarrollo, Santiago, Chile
| | - Fen-Biao Gao
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Pablo Henny
- Department of Anatomy, Medical School, Universidad Católica de Chile, Santiago, Chile
| | - Brigitte van Zundert
- Faculty of Biological Sciences and Faculty of Medicine, Center for Biomedical Research, Universidad Andres Bello, Santiago, Chile
| | - Lloyd W Ruddock
- Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Miguel L Concha
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile Program of Anatomy and Developmental Biology, Institute of Biomedical Sciences, University of Chile, Santiago, Chile Center for Geroscience, Brain Health and Metabolism, Santiago, Chile
| | - Juan P Henriquez
- Department of Cell Biology, Faculty of Biological Sciences, Millennium Nucleus of Regenerative Biology, Center for Advanced Microscopy (CMA Bio-Bio), Universidad de Concepción, Concepción, Chile
| | - Robert H Brown
- Department of Neurology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Claudio Hetz
- Biomedical Neuroscience Institute, Faculty of Medicine, University of Chile, Santiago, Chile Program of Cellular and Molecular Biology, Center for Molecular Studies of the Cell, Institute of Biomedical Sciences, University of Chile, Santiago, Chile Center for Geroscience, Brain Health and Metabolism, Santiago, Chile Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA, USA
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8
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Axons provide the secretory machinery for trafficking of voltage-gated sodium channels in peripheral nerve. Proc Natl Acad Sci U S A 2016; 113:1823-8. [PMID: 26839409 DOI: 10.1073/pnas.1514943113] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
The regulation of the axonal proteome is key to generate and maintain neural function. Fast and slow axoplasmic waves have been known for decades, but alternative mechanisms to control the abundance of axonal proteins based on local synthesis have also been identified. The presence of the endoplasmic reticulum has been documented in peripheral axons, but it is still unknown whether this localized organelle participates in the delivery of axonal membrane proteins. Voltage-gated sodium channels are responsible for action potentials and are mostly concentrated in the axon initial segment and nodes of Ranvier. Despite their fundamental role, little is known about the intracellular trafficking mechanisms that govern their availability in mature axons. Here we describe the secretory machinery in axons and its contribution to plasma membrane delivery of sodium channels. The distribution of axonal secretory components was evaluated in axons of the sciatic nerve and in spinal nerve axons after in vivo electroporation. Intracellular protein trafficking was pharmacologically blocked in vivo and in vitro. Axonal voltage-gated sodium channel mRNA and local trafficking were examined by RT-PCR and a retention-release methodology. We demonstrate that mature axons contain components of the endoplasmic reticulum and other biosynthetic organelles. Axonal organelles and sodium channel localization are sensitive to local blockade of the endoplasmic reticulum to Golgi transport. More importantly, secretory organelles are capable of delivering sodium channels to the plasma membrane in isolated axons, demonstrating an intrinsic capacity of the axonal biosynthetic route in regulating the axonal proteome in mammalian axons.
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9
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Epigenetic regulation of dorsal raphe GABA B1a associated with isolation-induced abnormal responses to social stimulation in mice. Neuropharmacology 2016; 101:1-12. [DOI: 10.1016/j.neuropharm.2015.09.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 09/05/2015] [Accepted: 09/09/2015] [Indexed: 01/12/2023]
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10
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Valenzuela JI, Perez F. Diversifying the secretory routes in neurons. Front Neurosci 2015; 9:358. [PMID: 26500481 PMCID: PMC4595659 DOI: 10.3389/fnins.2015.00358] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 09/18/2015] [Indexed: 12/23/2022] Open
Abstract
Nervous system homeostasis and synaptic function need dedicated mechanisms to locally regulate the molecular composition of the neuronal plasma membrane and allow the development, maintenance and plastic modification of the neuronal morphology. The cytoskeleton and intracellular trafficking lies at the core of all these processes. In most mammalian cells, the Golgi apparatus (GA) is at the center of the biosynthetic pathway, located in the proximity of the microtubule-organizing center. In addition to this central localization, the somatic GA in neurons is complemented by satellite Golgi outposts (GOPs) in dendrites, which are essential for dendritic morphogenesis and are emerging like local stations of membranes trafficking to synapses. Largely, GOPs participation in post-ER trafficking has been determined by imaging the transport of the exogenous protein VSVG. Here we review the diversity of neuronal cargoes that traffic through GOPs and the assortment of different biosynthetic routes to synapses. We also analyze the recent advances in understanding the role of cytoskeleton and Golgi matrix proteins in the biogenesis of GOPs and how the diversity of secretory routes can be generated.
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Affiliation(s)
- José I Valenzuela
- Cell Biology Department, Institut Curie, PSL Research University, UMR144 Paris, France ; Dynamics of Intracellular Organisation, Centre National de la Recherche Scientifique -UMR144 Paris, France
| | - Franck Perez
- Cell Biology Department, Institut Curie, PSL Research University, UMR144 Paris, France ; Dynamics of Intracellular Organisation, Centre National de la Recherche Scientifique -UMR144 Paris, France
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11
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Zhang XM, Yan XY, Zhang B, Yang Q, Ye M, Cao W, Qiang WB, Zhu LJ, Du YL, Xu XX, Wang JS, Xu F, Lu W, Qiu S, Yang W, Luo JH. Activity-induced synaptic delivery of the GluN2A-containing NMDA receptor is dependent on endoplasmic reticulum chaperone Bip and involved in fear memory. Cell Res 2015; 25:818-36. [PMID: 26088419 DOI: 10.1038/cr.2015.75] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 03/02/2015] [Accepted: 05/04/2015] [Indexed: 11/09/2022] Open
Abstract
The N-methyl-D-aspartate receptor (NMDAR) in adult forebrain is a heterotetramer mainly composed of two GluN1 subunits and two GluN2A and/or GluN2B subunits. The synaptic expression and relative numbers of GluN2A- and GluN2B-containing NMDARs play critical roles in controlling Ca(2+)-dependent signaling and synaptic plasticity. Previous studies have suggested that the synaptic trafficking of NMDAR subtypes is differentially regulated, but the precise molecular mechanism is not yet clear. In this study, we demonstrated that Bip, an endoplasmic reticulum (ER) chaperone, selectively interacted with GluN2A and mediated the neuronal activity-induced assembly and synaptic incorporation of the GluN2A-containing NMDAR from dendritic ER. Furthermore, the GluN2A-specific synaptic trafficking was effectively disrupted by peptides interrupting the interaction between Bip and GluN2A. Interestingly, fear conditioning in mice was disrupted by intraperitoneal injection of the interfering peptide before training. In summary, we have uncovered a novel mechanism for the activity-dependent supply of synaptic GluN2A-containing NMDARs, and demonstrated its relevance to memory formation.
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Affiliation(s)
- Xiao-min Zhang
- 1] Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China [2] Department of Physiology, Kunming Medical University, Kunming, Yunnan 650500, China
| | - Xun-yi Yan
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Bin Zhang
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Qian Yang
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Mao Ye
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Wei Cao
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Wen-bin Qiang
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Li-jun Zhu
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Yong-lan Du
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Xing-xing Xu
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Jia-sheng Wang
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Fei Xu
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Wei Lu
- Key Laboratory of Developmental Genes and Human Disease (Ministry of Education of China), Institute of Life Sciences, Southeast University, Nanjing, Jiangsu 211189, China
| | - Shuang Qiu
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Wei Yang
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Jian-hong Luo
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Collaborative Innovation Center for Brain Science, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
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Benke D, Balakrishnan K, Zemoura K. Regulation of Cell Surface GABAB Receptors. DIVERSITY AND FUNCTIONS OF GABA RECEPTORS: A TRIBUTE TO HANNS MÖHLER, PART B 2015; 73:41-70. [DOI: 10.1016/bs.apha.2014.11.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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13
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Valenzuela JI, Jaureguiberry-Bravo M, Salas DA, Ramírez OA, Cornejo VH, Lu HE, Blanpied TA, Couve A. Transport along the dendritic endoplasmic reticulum mediates the trafficking of GABAB receptors. J Cell Sci 2014; 127:3382-95. [PMID: 24895402 DOI: 10.1242/jcs.151092] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In neurons, secretory organelles within the cell body are complemented by the dendritic endoplasmic reticulum (ER) and Golgi outposts (GOPs), whose role in neurotransmitter receptor trafficking is poorly understood. γ-aminobutyric acid (GABA) type B metabotropic receptors (GABABRs) regulate the efficacy of synaptic transmission throughout the brain. Their plasma membrane availability is controlled by mechanisms involving an ER retention motif and assembly-dependent ER export. Thus, they constitute an ideal molecular model to study ER trafficking, but the extent to which the dendritic ER participates in GABABR biosynthesis has not been thoroughly explored. Here, we show that GABAB1 localizes preferentially to the ER in dendrites and moves long distances within this compartment. Not only diffusion but also microtubule and dynein-dependent mechanisms control dendritic ER transport. GABABRs insert throughout the somatodendritic plasma membrane but dendritic post-ER carriers containing GABABRs do not fuse selectively with GOPs. This study furthers our understanding of the spatial selectivity of neurotransmitter receptors for dendritic organelles.
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Affiliation(s)
- José I Valenzuela
- Program of Physiology and Biophysics, ICBM, Faculty of Medicine, Universidad de Chile, Santiago CP8380453, Chile Biomedical Neuroscience Institute, BNI, Faculty of Medicine, Universidad de Chile, Santiago CP8380453, Chile
| | - Matías Jaureguiberry-Bravo
- Program of Physiology and Biophysics, ICBM, Faculty of Medicine, Universidad de Chile, Santiago CP8380453, Chile Biomedical Neuroscience Institute, BNI, Faculty of Medicine, Universidad de Chile, Santiago CP8380453, Chile
| | - Daniela A Salas
- Program of Physiology and Biophysics, ICBM, Faculty of Medicine, Universidad de Chile, Santiago CP8380453, Chile Biomedical Neuroscience Institute, BNI, Faculty of Medicine, Universidad de Chile, Santiago CP8380453, Chile
| | - Omar A Ramírez
- Program of Physiology and Biophysics, ICBM, Faculty of Medicine, Universidad de Chile, Santiago CP8380453, Chile Biomedical Neuroscience Institute, BNI, Faculty of Medicine, Universidad de Chile, Santiago CP8380453, Chile Program of Anatomy and Development, ICBM, Faculty of Medicine, Universidad de Chile, Santiago CP8380453, Chile
| | - Víctor H Cornejo
- Program of Physiology and Biophysics, ICBM, Faculty of Medicine, Universidad de Chile, Santiago CP8380453, Chile Biomedical Neuroscience Institute, BNI, Faculty of Medicine, Universidad de Chile, Santiago CP8380453, Chile
| | - Hsiangmin E Lu
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA Program in Molecular Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Thomas A Blanpied
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Andrés Couve
- Program of Physiology and Biophysics, ICBM, Faculty of Medicine, Universidad de Chile, Santiago CP8380453, Chile Biomedical Neuroscience Institute, BNI, Faculty of Medicine, Universidad de Chile, Santiago CP8380453, Chile
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Kantamneni S, Gonzàlez-Gonzàlez IM, Luo J, Cimarosti H, Jacobs SC, Jaafari N, Henley JM. Differential regulation of GABAB receptor trafficking by different modes of N-methyl-D-aspartate (NMDA) receptor signaling. J Biol Chem 2014; 289:6681-6694. [PMID: 24425870 PMCID: PMC3945329 DOI: 10.1074/jbc.m113.487348] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2013] [Revised: 12/24/2013] [Indexed: 12/31/2022] Open
Abstract
Inhibitory GABAB receptors (GABABRs) can down-regulate most excitatory synapses in the CNS by reducing postsynaptic excitability. Functional GABABRs are heterodimers of GABAB1 and GABAB2 subunits and here we show that the trafficking and surface expression of GABABRs is differentially regulated by synaptic or pathophysiological activation of NMDA receptors (NMDARs). Activation of synaptic NMDARs using a chemLTP protocol increases GABABR recycling and surface expression. In contrast, excitotoxic global activation of synaptic and extrasynaptic NMDARs by bath application of NMDA causes the loss of surface GABABRs. Intriguingly, exposing neurons to extreme metabolic stress using oxygen/glucose deprivation (OGD) increases GABAB1 but decreases GABAB2 surface expression. The increase in surface GABAB1 involves enhanced recycling and is blocked by the NMDAR antagonist AP5. The decrease in surface GABAB2 is also blocked by AP5 and by inhibiting degradation pathways. These results indicate that NMDAR activity is critical in GABABR trafficking and function and that the individual subunits can be separately controlled to regulate neuronal responsiveness and survival.
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Affiliation(s)
- Sriharsha Kantamneni
- School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom.
| | | | - Jia Luo
- School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Helena Cimarosti
- School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Susan C Jacobs
- School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Nadia Jaafari
- School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Jeremy M Henley
- School of Biochemistry, Medical Sciences Building, University of Bristol, Bristol BS8 1TD, United Kingdom.
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Murthy R, Kim J, Sun X, Giger RJ, Fink DJ, Mata M. Post-transcriptional regulation of GABAB receptor and GIRK1 channels by Nogo receptor 1. Mol Brain 2013; 6:30. [PMID: 23829864 PMCID: PMC3734105 DOI: 10.1186/1756-6606-6-30] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Accepted: 07/01/2013] [Indexed: 11/10/2022] Open
Abstract
Background Type B GABA receptors (GABA Rs) play a critical role in synaptic transmission. We carried out studies to determine whether neuronal cell surface expression of GABAB-Rs might be regulated by the Nogo receptor 1 (NgR1). Results siRNA knock-down of NgR1 resulted in a selective increase of GABAB R1 and GABAB R2 protein without altering the expression of GABAA receptor or GAD65. The increase in GABAB receptor subunits was unaccompanied by a change in mRNA, but inhibition of mTOR by rapamycin blocked the increase in GABAB protein. NgR1 siRNA also caused an increase in G protein coupled inwardly rectifying potassium channel (GIRK1). The increase in GABAB receptor and GIRK1 channel proteins was in the plasma membrane, determined by cell surface biotinylation. In NgR1 knockout mice, the amount of GABAB R2 and GIRK1 in hippocampus-derived synaptosomes was increased. Conclusions Together these findings suggest that NgR1 mediated modulation of synaptic transmission may be accomplished, at least in part, through modulation of G protein coupled receptors and channels.
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Affiliation(s)
- Rachana Murthy
- Department of Neurology, University of Michigan and VA Ann Arbor Healthcare System-Neurology and GRECC, 5027 BSRB, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
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16
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A noncanonical postsynaptic transport route for a GPCR belonging to the serotonin receptor family. J Neurosci 2013; 32:17998-8008. [PMID: 23238716 DOI: 10.1523/jneurosci.1804-12.2012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Postsynaptic receptor trafficking plays an essential role in tuning neurotransmission and signal plasticity and has emerged as a potential therapeutic target in neuropsychiatric disease. Using a novel application of fluorescence recovery after photobleaching in rat hippocampal neurons, we examined transport from the soma to dendrites of seven G-protein-coupled receptors (GPCRs) implicated in mood disorders. Most GPCRs were delivered to dendrites via lateral diffusion, but one GPCR, the serotonin 1B receptor (5-HT(1B)), was delivered to the dendrites in secretory vesicles. Within the dendrites, 5-HT(1B) were stored in a reservoir of accessible vesicles that were recruited to preferential sites in plasma membrane, as observed with superecliptic pHluorin labeling. After membrane recruitment, 5-HT(1B) transport via lateral diffusion and temporal confinement to inhibitory and excitatory synapses was monitored by single particle tracking. These results suggest an alternative mechanism for control of neuronal activity via a GPCR that has been implicated in mood regulation.
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17
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Astorga G, Härtel S, Sanhueza M, Bacigalupo J. TRP, TRPL and cacophony channels mediate Ca2+ influx and exocytosis in photoreceptors axons in Drosophila. PLoS One 2012; 7:e44182. [PMID: 22952921 PMCID: PMC3432082 DOI: 10.1371/journal.pone.0044182] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 08/02/2012] [Indexed: 01/17/2023] Open
Abstract
In Drosophila photoreceptors Ca(2+)-permeable channels TRP and TRPL are the targets of phototransduction, occurring in photosensitive microvilli and mediated by a phospholipase C (PLC) pathway. Using a novel Drosophila brain slice preparation, we studied the distribution and physiological properties of TRP and TRPL in the lamina of the visual system. Immunohistochemical images revealed considerable expression in photoreceptors axons at the lamina. Other phototransduction proteins are also present, mainly PLC and protein kinase C, while rhodopsin is absent. The voltage-dependent Ca(2+) channel cacophony is also present there. Measurements in the lamina with the Ca(2+) fluorescent protein G-CaMP ectopically expressed in photoreceptors, revealed depolarization-induced Ca(2+) increments mediated by cacophony. Additional Ca(2+) influx depends on TRP and TRPL, apparently functioning as store-operated channels. Single synaptic boutons resolved in the lamina by FM4-64 fluorescence revealed that vesicle exocytosis depends on cacophony, TRP and TRPL. In the PLC mutant norpA bouton labeling was also impaired, implicating an additional modulation by this enzyme. Internal Ca(2+) also contributes to exocytosis, since this process was reduced after Ca(2+)-store depletion. Therefore, several Ca(2+) pathways participate in photoreceptor neurotransmitter release: one is activated by depolarization and involves cacophony; this is complemented by internal Ca(2+) release and the activation of TRP and TRPL coupled to Ca(2+) depletion of internal reservoirs. PLC may regulate the last two processes. TRP and TRPL would participate in two different functions in distant cellular regions, where they are opened by different mechanisms. This work sheds new light on the mechanism of neurotransmitter release in tonic synapses of non-spiking neurons.
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Affiliation(s)
- Guadalupe Astorga
- Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile
- Millennium Institute for Cell Dynamics and Biotechnology, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Steffen Härtel
- Laboratory for Scientific Image Analysis, (SCIAN-Lab), Biomedical Neuroscience Institute (BNI), ICBM, Program of Anatomy and Developmental Biology, Faculty of Medicine, University of Chile, Santiago, Chile
| | - Magdalena Sanhueza
- Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile
- Millennium Institute for Cell Dynamics and Biotechnology, Faculty of Sciences, University of Chile, Santiago, Chile
| | - Juan Bacigalupo
- Department of Biology, Faculty of Sciences, University of Chile, Santiago, Chile
- Millennium Institute for Cell Dynamics and Biotechnology, Faculty of Sciences, University of Chile, Santiago, Chile
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Valdés V, Valenzuela JI, Salas DA, Jaureguiberry-Bravo M, Otero C, Thiede C, Schmidt CF, Couve A. Endoplasmic reticulum sorting and kinesin-1 command the targeting of axonal GABAB receptors. PLoS One 2012; 7:e44168. [PMID: 22952914 PMCID: PMC3428321 DOI: 10.1371/journal.pone.0044168] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 07/30/2012] [Indexed: 12/17/2022] Open
Abstract
In neuronal cells the intracellular trafficking machinery controls the availability of neurotransmitter receptors at the plasma membrane, which is a critical determinant of synaptic strength. Metabotropic γ amino-butyric acid (GABA) type B receptors (GABABRs) are neurotransmitter receptors that modulate synaptic transmission by mediating the slow and prolonged responses to GABA. GABABRs are obligatory heteromers constituted by two subunits, GABABR1 and GABABR2. GABABR1a and GABABR1b are the most abundant subunit variants. GABABR1b is located in the somatodendritic domain whereas GABABR1a is additionally targeted to the axon. Sushi domains located at the N-terminus of GABABR1a constitute the only difference between both variants and are necessary and sufficient for axonal targeting. The precise targeting machinery and the organelles involved in sorting and transport have not been described. Here we demonstrate that GABABRs require the Golgi apparatus for plasma membrane delivery but that axonal sorting and targeting of GABABR1a operate in a pre-Golgi compartment. In the axon GABABR1a subunits are enriched in the endoplasmic reticulum (ER), and their dynamic behavior and colocalization with other secretory organelles like the ER-to-Golgi intermediate compartment (ERGIC) suggest that they employ a local secretory route. The transport of axonal GABABR1a is microtubule-dependent and kinesin-1, a molecular motor of the kinesin family, determines axonal localization. Considering that progression of GABABRs through the secretory pathway is regulated by an ER retention motif our data contribute to understand the role of the axonal ER in non-canonical sorting and targeting of neurotransmitter receptors.
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Affiliation(s)
- Viviana Valdés
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, Universidad de Chile, Santiago, Chile
- Program of Physiology and Biophysics, Institute of Biomedical Sciences (ICBM), Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - José Ignacio Valenzuela
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, Universidad de Chile, Santiago, Chile
- Program of Physiology and Biophysics, Institute of Biomedical Sciences (ICBM), Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Daniela A. Salas
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, Universidad de Chile, Santiago, Chile
- Program of Physiology and Biophysics, Institute of Biomedical Sciences (ICBM), Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Matías Jaureguiberry-Bravo
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, Universidad de Chile, Santiago, Chile
- Program of Physiology and Biophysics, Institute of Biomedical Sciences (ICBM), Faculty of Medicine, Universidad de Chile, Santiago, Chile
- School of Biochemistry, Faculty of Biological Science, Universidad Andrés Bello, Santiago, Chile
| | - Carolina Otero
- Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Christina Thiede
- Georg-August-Universität, Fakultät für Physik, Drittes Physikalisches Institut-Biophysik, Göttingen, Germany
| | - Christoph F. Schmidt
- Georg-August-Universität, Fakultät für Physik, Drittes Physikalisches Institut-Biophysik, Göttingen, Germany
| | - Andrés Couve
- Biomedical Neuroscience Institute (BNI), Faculty of Medicine, Universidad de Chile, Santiago, Chile
- Program of Physiology and Biophysics, Institute of Biomedical Sciences (ICBM), Faculty of Medicine, Universidad de Chile, Santiago, Chile
- * E-mail:
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Vidal RL, Fuentes P, Valenzuela JI, Alvarado-Diaz CP, Ramírez OA, Kukuljan M, Couve A. RNA interference of Marlin-1/Jakmip1 results in abnormal morphogenesis and migration of cortical pyramidal neurons. Mol Cell Neurosci 2012; 51:1-11. [DOI: 10.1016/j.mcn.2012.07.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 07/04/2012] [Accepted: 07/17/2012] [Indexed: 10/28/2022] Open
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Benke D, Zemoura K, Maier PJ. Modulation of cell surface GABA(B) receptors by desensitization, trafficking and regulated degradation. World J Biol Chem 2012; 3:61-72. [PMID: 22558486 PMCID: PMC3342575 DOI: 10.4331/wjbc.v3.i4.61] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2011] [Revised: 12/08/2011] [Accepted: 12/15/2011] [Indexed: 02/05/2023] Open
Abstract
Inhibitory neurotransmission ensures normal brain function by counteracting and integrating excitatory activity. γ-Aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the mammalian central nervous system, and mediates its effects via two classes of receptors: the GABA(A) and GABA(B) receptors. GABA(A) receptors are heteropentameric GABA-gated chloride channels and responsible for fast inhibitory neurotransmission. GABA(B) receptors are heterodimeric G protein coupled receptors (GPCR) that mediate slow and prolonged inhibitory transmission. The extent of inhibitory neurotransmission is determined by a variety of factors, such as the degree of transmitter release and changes in receptor activity by posttranslational modifications (e.g., phosphorylation), as well as by the number of receptors present in the plasma membrane available for signal transduction. The level of GABA(B) receptors at the cell surface critically depends on the residence time at the cell surface and finally the rates of endocytosis and degradation. In this review we focus primarily on recent advances in the understanding of trafficking mechanisms that determine the expression level of GABA(B) receptors in the plasma membrane, and thereby signaling strength.
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Affiliation(s)
- Dietmar Benke
- Dietmar Benke, Khaled Zemoura, Patrick J Maier, Institute of Pharmacology and Toxicology, University of Zürich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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Valenzuela JI, Jaureguiberry-Bravo M, Couve A. Neuronal protein trafficking: emerging consequences of endoplasmic reticulum dynamics. Mol Cell Neurosci 2011; 48:269-77. [PMID: 21782949 DOI: 10.1016/j.mcn.2011.07.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Revised: 06/23/2011] [Accepted: 07/07/2011] [Indexed: 01/16/2023] Open
Abstract
The highly polarized morphology and complex geometry of neurons is determined to a great extent by the structural and functional organization of the secretory pathway. It is intuitive to propose that the spatial arrangement of secretory organelles and their dynamic behavior impinge on protein trafficking and neuronal function, but these phenomena and their consequences are not well delineated. Here we analyze the architecture and motility of the archetypal endoplasmic reticulum (ER), and their relationship to the microtubule cytoskeleton and post-translational modifications of tubulin. We also review the dynamics of the ER in axons, dendrites and spines, and discuss the role of ER dynamics on protein mobility and trafficking in neurons.
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Affiliation(s)
- José Ignacio Valenzuela
- Programa de Fisiología y Biofísica, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
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The survival of motor neuron (SMN) protein interacts with the mRNA-binding protein HuD and regulates localization of poly(A) mRNA in primary motor neuron axons. J Neurosci 2011; 31:3914-25. [PMID: 21389246 DOI: 10.1523/jneurosci.3631-10.2011] [Citation(s) in RCA: 166] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Spinal muscular atrophy (SMA) results from reduced levels of the survival of motor neuron (SMN) protein, which has a well characterized function in spliceosomal small nuclear ribonucleoprotein assembly. Currently, it is not understood how deficiency of a housekeeping protein leads to the selective degeneration of spinal cord motor neurons. Numerous studies have shown that SMN is present in neuronal processes and has many interaction partners, including mRNA-binding proteins, suggesting a potential noncanonical role in axonal mRNA metabolism. In this study, we have established a novel technological approach using bimolecular fluorescence complementation (BiFC) and quantitative image analysis to characterize SMN-protein interactions in primary motor neurons. Consistent with biochemical studies on the SMN complex, BiFC analysis revealed that SMN dimerizes and interacts with Gemin2 in nuclear gems and axonal granules. In addition, using pull down assays, immunofluorescence, cell transfection, and BiFC, we characterized a novel interaction between SMN and the neuronal mRNA-binding protein HuD, which was dependent on the Tudor domain of SMN. A missense mutation in the SMN Tudor domain, which is known to cause SMA, impaired the interaction with HuD, but did not affect SMN axonal localization or self-association. Furthermore, time-lapse microscopy revealed SMN cotransport with HuD in live motor neurons. Importantly, SMN knockdown in primary motor neurons resulted in a specific reduction of both HuD protein and poly(A) mRNA levels in the axonal compartment. These findings reveal a noncanonical role for SMN whereby its interaction with mRNA-binding proteins may facilitate the localization of associated poly(A) mRNAs into axons.
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23
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Ramírez OA, Couve A. The endoplasmic reticulum and protein trafficking in dendrites and axons. Trends Cell Biol 2011; 21:219-27. [DOI: 10.1016/j.tcb.2010.12.003] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 11/24/2010] [Accepted: 12/02/2010] [Indexed: 12/12/2022]
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Riquelme D, Alvarez A, Leal N, Adasme T, Espinoza I, Valdés JA, Troncoso N, Hartel S, Hidalgo J, Hidalgo C, Carrasco MA. High-frequency field stimulation of primary neurons enhances ryanodine receptor-mediated Ca2+ release and generates hydrogen peroxide, which jointly stimulate NF-κB activity. Antioxid Redox Signal 2011; 14:1245-59. [PMID: 20836702 DOI: 10.1089/ars.2010.3238] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Neuronal electrical activity increases intracellular Ca(2+) concentration and generates reactive oxygen species. Here, we show that high frequency field stimulation of primary hippocampal neurons generated Ca(2+) signals with an early and a late component, and promoted hydrogen peroxide generation via a neuronal NADPH oxidase. Hydrogen peroxide generation required both Ca(2+) entry through N-methyl-D-aspartate receptors and Ca(2+) release mediated by ryanodine receptors (RyR). Field stimulation also enhanced nuclear translocation of the NF-κB p65 protein and NF-κB -dependent transcription, and increased c-fos mRNA and type-2 RyR protein content. Preincubation with inhibitory ryanodine or with the antioxidant N-acetyl L-cysteine abolished the increase in hydrogen peroxide generation and the late Ca(2+) signal component induced by electrical stimulation. Primary cortical cells behaved similarly as primary hippocampal cells. Exogenous hydrogen peroxide also activated NF-κB-dependent transcription in hippocampal neurons; inhibitory ryanodine prevented this effect. Selective inhibition of the NADPH oxidase or N-acetyl L-cysteine also prevented the enhanced translocation of p65 in hippocampal cells, while N-acetyl L-cysteine abolished the increase in RyR2 protein content induced by high frequency stimulation. In conclusion, the present results show that electrical stimulation induced reciprocal activation of ryanodine receptor-mediated Ca(2+) signals and hydrogen peroxide generation, which stimulated jointly NF-κB activity.
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Affiliation(s)
- Denise Riquelme
- Center of Molecular Studies of the Cell, Institute of Biomedical Sciences Programs, Universidad de Chile, Santiago, Chile
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Ramírez O, García A, Rojas R, Couve A, Härtel S. Confined displacement algorithm determines true and random colocalization in fluorescence microscopy. J Microsc 2010; 239:173-83. [PMID: 20701655 DOI: 10.1111/j.1365-2818.2010.03369.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The quantification of colocalizing signals in multichannel fluorescence microscopy images depends on the reliable segmentation of corresponding regions of interest, on the selection of appropriate colocalization coefficients, and on a robust statistical criterion to discriminate true from random colocalization. Here, we introduce a confined displacement algorithm based on image correlation spectroscopy in combination with Manders colocalization coefficients M1(ROI) and M2(ROI) to quantify true and random colocalization of a given florescence pattern. We show that existing algorithms based on block scrambling exaggerate the randomization of fluorescent patterns with resulting inappropriately narrow probability density functions and false significance of true colocalization in terms of p values. We further confine our approach to subcellular compartments and show that true and random colocalization can be analysed for model dendrites and for GABA(B) receptor subunits GABA(B)R1/2 in cultured hippocampal neurons. Together, we demonstrate that the confined displacement algorithm detects true colocalization of specific fluorescence patterns down to subcellular levels.
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Affiliation(s)
- O Ramírez
- Laboratory for Scientific Image Analysis (SCIAN-Lab) at the Anatomy and Developmental Biology Program, ICBM, Universidad de Chile, Santiago, Chile
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Padgett CL, Slesinger PA. GABAB receptor coupling to G-proteins and ion channels. ADVANCES IN PHARMACOLOGY 2010; 58:123-47. [PMID: 20655481 DOI: 10.1016/s1054-3589(10)58006-2] [Citation(s) in RCA: 161] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
GABA(B) receptors have been found to play a key role in regulating membrane excitability and synaptic transmission in the brain. The GABA(B) receptor is a G-protein coupled receptor (GPCR) that associates with a subset of G-proteins (pertussis toxin sensitive Gi/o family), that in turn regulate specific ion channels and trigger cAMP cascades. In this review, we describe the relationships between the GABA(B) receptor, its effectors and associated proteins that mediate GABA(B) receptor function within the brain. We discuss a unique feature of the GABA(B) receptor, the requirement for heterodimerization to produce functional receptors, as well as an increasing body of evidence that suggests GABA(B) receptors comprise a macromolecular signaling heterocomplex, critical for efficient targeting and function of the receptors. Within this complex, GABA(B) receptors associate specifically with Gi/o G-proteins that regulate voltage-gated Ca(2+) (Ca(V)) channels, G-protein activated inwardly rectifying K(+) (GIRK) channels, and adenylyl cyclase. Numerous studies have revealed that lipid rafts, scaffold proteins, targeting motifs in the receptor, and regulators of G-protein signaling (RGS) proteins also contribute to the function of GABA(B) receptors and affect cellular processes such as receptor trafficking and activity-dependent desensitization. This complex regulation of GABA(B) receptors in the brain may provide opportunities for new ways to regulate GABA-dependent inhibition in normal and diseased states of the nervous system.
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Affiliation(s)
- Claire L Padgett
- Peptide Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA, USA
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Prolonged activation of NMDA receptors promotes dephosphorylation and alters postendocytic sorting of GABAB receptors. Proc Natl Acad Sci U S A 2010; 107:13918-23. [PMID: 20643948 DOI: 10.1073/pnas.1000853107] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Slow and persistent synaptic inhibition is mediated by metabotropic GABAB receptors (GABABRs). GABABRs are responsible for the modulation of neurotransmitter release from presynaptic terminals and for hyperpolarization at postsynaptic sites. Postsynaptic GABABRs are predominantly found on dendritic spines, adjacent to excitatory synapses, but the control of their plasma membrane availability is still controversial. Here, we explore the role of glutamate receptor activation in regulating the function and surface availability of GABABRs in central neurons. We demonstrate that prolonged activation of NMDA receptors (NMDA-Rs) leads to endocytosis, a diversion from a recycling route, and subsequent lysosomal degradation of GABABRs. These sorting events are paralleled by a reduction in GABABR-dependent activation of inwardly rectifying K+ channel currents. Postendocytic sorting is critically dependent on phosphorylation of serine 783 (S783) within the GABABR2 subunit, an established substrate of AMP-dependent protein kinase (AMPK). NMDA-R activation leads to a rapid increase in phosphorylation of S783, followed by a slower dephosphorylation, which results from the activity of AMPK and protein phosphatase 2A, respectively. Agonist activation of GABABRs counters the effects of NMDA. Thus, NMDA-R activation alters the phosphorylation state of S783 and acts as a molecular switch to decrease the abundance of GABABRs at the neuronal plasma membrane. Such a mechanism may be of significance during synaptic plasticity or pathological conditions, such as ischemia or epilepsy, which lead to prolonged activation of glutamate receptors.
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28
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Abstract
GABA(B) receptors are the G-protein-coupled receptors for GABA, the main inhibitory neurotransmitter in the brain. Two receptor subtypes, GABA(B(1a,2)) and GABA(B(1b,2)), are formed by the assembly of GABA(B1a) and GABA(B1b) subunits with GABA(B2) subunits. The GABA(B1b) subunit is a shorter isoform of the GABA(B1a) subunit lacking two N-terminal protein interaction motifs, the sushi domains. Selectively GABA(B1a) protein traffics into the axons of glutamatergic neurons, whereas both the GABA(B1a) and GABA(B1b) proteins traffic into the dendrites. The mechanism(s) and targeting signal(s) responsible for the selective trafficking of GABA(B1a) protein into axons are unknown. Here, we provide evidence that the sushi domains are axonal targeting signals that redirect GABA(B1a) protein from its default dendritic localization to axons. Specifically, we show that mutations in the sushi domains preventing protein interactions preclude axonal localization of GABA(B1a). When fused to CD8alpha, the sushi domains polarize this uniformly distributed protein to axons. Likewise, when fused to mGluR1a the sushi domains redirect this somatodendritic protein to axons, showing that the sushi domains can override dendritic targeting information in a heterologous protein. Cell surface expression of the sushi domains is not required for axonal localization of GABA(B1a). Altogether, our findings are consistent with the sushi domains functioning as axonal targeting signals by interacting with axonally bound proteins along intracellular sorting pathways. Our data provide a mechanistic explanation for the selective trafficking of GABA(B(1a,2)) receptors into axons while at the same time identifying a well defined axonal delivery module that can be used as an experimental tool.
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Direct interaction of GABAB receptors with M2 muscarinic receptors enhances muscarinic signaling. J Neurosci 2010; 29:15796-809. [PMID: 20016095 DOI: 10.1523/jneurosci.4103-09.2009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Downregulation of G-protein-coupled receptors (GPCRs) provides an important mechanism for reducing neurotransmitter signaling during sustained stimulation. Chronic stimulation of M(2) muscarinic receptors (M(2)Rs) causes internalization of M(2)R and G-protein-activated inwardly rectifying potassium (GIRK) channels in neuronal PC12 cells, resulting in loss of function. Here, we show that coexpression of GABA(B) R2 receptors (GBR2s) rescues both surface expression and function of M(2)R, including M(2)R-induced activation of GIRKs and inhibition of cAMP production. GBR2 showed significant association with M(2)R at the plasma membrane but not other GPCRs (M(1)R, mu-opioid receptor), as detected by fluorescence resonance energy transfer measured with total internal reflection fluorescence microscopy. Unique regions of the proximal C-terminal domains of GBR2 and M(2)R mediate specific binding between M(2)R and GBR2. In the brain, GBR2, but not GBR1, biochemically coprecipitates with M(2)R and overlaps with M(2)R expression in cortical neurons. This novel heteromeric association between M(2)R and GBR2 provides a possible mechanism for altering muscarinic signaling in the brain and represents a previously unrecognized role for GBR2.
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Benke D. Mechanisms of GABAB receptor exocytosis, endocytosis, and degradation. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2010; 58:93-111. [PMID: 20655479 DOI: 10.1016/s1054-3589(10)58004-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
GABA(B) receptors belong to the family of G-protein-coupled receptors, which mediate slow inhibitory neurotransmission in the central nervous system. They are promising drug targets for a variety of neurological disorders and play important functions in regulating synaptic plasticity. Signaling strength is critically dependent on the availability of the receptors at the cell surface. Several distinct highly regulated trafficking mechanisms ensure the presence of adequate receptor numbers in the plasma membrane. The rate of exocytosis of newly synthesized receptors from the endoplasmic reticulum via the Golgi apparatus to the cell surface as well as the rates of their endocytosis and degradation determines the retention time of receptors at the cell surface. This chapter focuses on the recently emerged mechanisms of GABA(B) receptor exocytosis, endocytosis, recycling, and degradation.
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Affiliation(s)
- Dietmar Benke
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
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