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Lee SK, Hong WJ, Silva J, Kim EJ, Park SK, Jung KH, Kim YJ. Global Identification of ANTH Genes Involved in Rice Pollen Germination and Functional Characterization of a Key Member, OsANTH3. FRONTIERS IN PLANT SCIENCE 2021; 12:609473. [PMID: 33927731 PMCID: PMC8076639 DOI: 10.3389/fpls.2021.609473] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 03/22/2021] [Indexed: 06/02/2023]
Abstract
Pollen in angiosperms plays a critical role in double fertilization by germinating and elongating pollen tubes rapidly in one direction to deliver sperm. In this process, the secretory vesicles deliver cell wall and plasma membrane materials, and excessive materials are sequestered via endocytosis. However, endocytosis in plants is poorly understood. AP180 N-terminal homology (ANTH) domain-containing proteins function as adaptive regulators for clathrin-mediated endocytosis in eukaryotic systems. Here, we identified 17 ANTH domain-containing proteins from rice based on a genome-wide investigation. Motif and phylogenomic analyses revealed seven asparagine-proline-phenylalanine (NPF)-rich and 10 NPF-less subgroups of these proteins, as well as various clathrin-mediated endocytosis-related motifs in their C-terminals. To investigate their roles in pollen germination, we performed meta-expression analysis of all genes encoding ANTH domain-containing proteins in Oryza sativa (OsANTH genes) in anatomical samples, including pollen, and identified five mature pollen-preferred OsANTH genes. The subcellular localization of four OsANTH proteins that were preferentially expressed in mature pollen can be consistent with their role in endocytosis in the plasma membrane. Of them, OsANTH3 represented the highest expression in mature pollen. Functional characterization of OsANTH3 using T-DNA insertional knockout and gene-edited mutants revealed that a mutation in OsANTH3 decreased seed fertility by reducing the pollen germination percentage in rice. Thus, our study suggests OsANTH3-mediated endocytosis is important for rice pollen germination.
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Affiliation(s)
- Su Kyoung Lee
- Graduate School of Biotechnology, Crop Biotech Institute, Kyung Hee University, Yongin, South Korea
| | - Woo-Jong Hong
- Graduate School of Biotechnology, Crop Biotech Institute, Kyung Hee University, Yongin, South Korea
| | - Jeniffer Silva
- Graduate School of Biotechnology, Crop Biotech Institute, Kyung Hee University, Yongin, South Korea
| | - Eui-Jung Kim
- Graduate School of Biotechnology, Crop Biotech Institute, Kyung Hee University, Yongin, South Korea
| | - Soon Ki Park
- School of Applied Biosciences, Kyungpook National University, Daegu, South Korea
| | - Ki-Hong Jung
- Graduate School of Biotechnology, Crop Biotech Institute, Kyung Hee University, Yongin, South Korea
| | - Yu-Jin Kim
- Department of Life Science and Environmental Biochemistry, Life and Industry Convergence Research Institute, Pusan National University, Miryang, South Korea
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2
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Kaneda M, van Oostende-Triplet C, Chebli Y, Testerink C, Bednarek SY, Geitmann A. Plant AP180 N-Terminal Homolog Proteins Are Involved in Clathrin-Dependent Endocytosis during Pollen Tube Growth in Arabidopsis thaliana. PLANT & CELL PHYSIOLOGY 2019; 60:1316-1330. [PMID: 30796435 DOI: 10.1093/pcp/pcz036] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Accepted: 02/18/2019] [Indexed: 05/05/2023]
Abstract
Polarized cell growth in plants is maintained under the strict control and exquisitely choreographed balance of exocytic and endocytic membrane trafficking. The pollen tube has become a model system for rapid polar growth in which delivery of cell wall material and membrane recycling are controlled by membrane trafficking. Endocytosis plays an important role that is poorly understood. The plant AP180 N-Terminal Homolog (ANTH) proteins are putative homologs of Epsin 1 that recruits clathrin to phosphatidylinositol 4, 5-bisphosphate (PIP2) containing membranes to facilitate vesicle budding during endocytosis. Two Arabidopsis ANTH encoded by the genes AtAP180 and AtECA2 are highly expressed in pollen tubes. Pollen tubes from T-DNA inserted knockout mutant lines display significant morphological defects and unique pectin deposition. Fluorescent tagging reveals organization into dynamic foci located at the lateral flanks of the pollen tube. This precisely defined subapical domain coincides which clathrin-mediated endocytosis (CME) and PIP2 localization. Using a liposome-protein binding test, we showed that AtECA2 protein and ANTH domain recombinant proteins have strong affinity to PIP2 and phosphatidic acid containing liposomes in vitro. Taken together these data suggest that Arabidopsis ANTH proteins may play an important role in CME, proper cell wall assembly and morphogenesis.
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Affiliation(s)
- Minako Kaneda
- Institut de recherche en biologie v�g�tale, Universit� de Montr�al, 4101 Rue Sherbrooke Est, Montr�al, QC, Canada
| | - Chloï van Oostende-Triplet
- Institut de recherche en biologie v�g�tale, Universit� de Montr�al, 4101 Rue Sherbrooke Est, Montr�al, QC, Canada
- Present address: Cell Biology and Image Acquisition Core Facility, Faculty of Medicine, University of Ottawa, RGN 3171, 451 Smyth Road, Ottawa, ON, Canada
| | - Youssef Chebli
- Department of Plant Science, McGill University, Macdonald Campus, 21111 Lakeshore, Ste-Anne-de-Bellevue, Qu�bec, Canada
| | - Christa Testerink
- Section of Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, Amsterdam, The Netherlands
- Present address: Laboratory of Plant Physiology, Wageningen University and Research, PB Wageningen, The Netherlands
| | | | - Anja Geitmann
- Institut de recherche en biologie v�g�tale, Universit� de Montr�al, 4101 Rue Sherbrooke Est, Montr�al, QC, Canada
- Department of Plant Science, McGill University, Macdonald Campus, 21111 Lakeshore, Ste-Anne-de-Bellevue, Qu�bec, Canada
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3
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Kaempf N, Maritzen T. Safeguards of Neurotransmission: Endocytic Adaptors as Regulators of Synaptic Vesicle Composition and Function. Front Cell Neurosci 2017; 11:320. [PMID: 29085282 PMCID: PMC5649181 DOI: 10.3389/fncel.2017.00320] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 09/26/2017] [Indexed: 11/13/2022] Open
Abstract
Communication between neurons relies on neurotransmitters which are released from synaptic vesicles (SVs) upon Ca2+ stimuli. To efficiently load neurotransmitters, sense the rise in intracellular Ca2+ and fuse with the presynaptic membrane, SVs need to be equipped with a stringently controlled set of transmembrane proteins. In fact, changes in SV protein composition quickly compromise neurotransmission and most prominently give rise to epileptic seizures. During exocytosis SVs fully collapse into the presynaptic membrane and consequently have to be replenished to sustain neurotransmission. Therefore, surface-stranded SV proteins have to be efficiently retrieved post-fusion to be used for the generation of a new set of fully functional SVs, a process in which dedicated endocytic sorting adaptors play a crucial role. The question of how the precise reformation of SVs is achieved is intimately linked to how SV membranes are retrieved. For a long time both processes were believed to be two sides of the same coin since Clathrin-mediated endocytosis (CME), the proposed predominant SV recycling mode, will jointly retrieve SV membranes and proteins. However, with the recent proposal of Clathrin-independent SV recycling pathways SV membrane retrieval and SV reformation turn into separable events. This review highlights the progress made in unraveling the molecular mechanisms mediating the high-fidelity retrieval of SV proteins and discusses how the gathered knowledge about SV protein recycling fits in with the new notions of SV membrane endocytosis.
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Affiliation(s)
- Natalie Kaempf
- Molecular Physiology and Cell Biology Section, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Tanja Maritzen
- Molecular Physiology and Cell Biology Section, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
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4
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Fullard JF, Giambartolomei C, Hauberg ME, Xu K, Voloudakis G, Shao Z, Bare C, Dudley JT, Mattheisen M, Robakis NK, Haroutunian V, Roussos P. Open chromatin profiling of human postmortem brain infers functional roles for non-coding schizophrenia loci. Hum Mol Genet 2017; 26:1942-1951. [PMID: 28335009 DOI: 10.1093/hmg/ddx103] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Accepted: 03/10/2017] [Indexed: 01/03/2023] Open
Abstract
Open chromatin provides access to DNA-binding proteins for the correct spatiotemporal regulation of gene expression. Mapping chromatin accessibility has been widely used to identify the location of cis regulatory elements (CREs) including promoters and enhancers. CREs show tissue- and cell-type specificity and disease-associated variants are often enriched for CREs in the tissues and cells that pertain to a given disease. To better understand the role of CREs in neuropsychiatric disorders we applied the Assay for Transposase Accessible Chromatin followed by sequencing (ATAC-seq) to neuronal and non-neuronal nuclei isolated from frozen postmortem human brain by fluorescence-activated nuclear sorting (FANS). Most of the identified open chromatin regions (OCRs) are differentially accessible between neurons and non-neurons, and show enrichment with known cell type markers, promoters and enhancers. Relative to those of non-neurons, neuronal OCRs are more evolutionarily conserved and are enriched in distal regulatory elements. Transcription factor (TF) footprinting analysis identifies differences in the regulome between neuronal and non-neuronal cells and ascribes putative functional roles to a number of non-coding schizophrenia (SCZ) risk variants. Among the identified variants is a Single Nucleotide Polymorphism (SNP) proximal to the gene encoding SNX19. In vitro experiments reveal that this SNP leads to an increase in transcriptional activity. As elevated expression of SNX19 has been associated with SCZ, our data provide evidence that the identified SNP contributes to disease. These results represent the first analysis of OCRs and TF-binding sites in distinct populations of postmortem human brain cells and further our understanding of the regulome and the impact of neuropsychiatric disease-associated genetic risk variants.
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Affiliation(s)
- John F Fullard
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Claudia Giambartolomei
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Mads E Hauberg
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.,Department of Biomedicine.,Centre for Integrative Sequencing (iSEQ), Aarhus University, Aarhus, Denmark.,The Lundbeck Foundation Initiative of Integrative Psychiatric Research (iPSYCH), Denmark
| | - Ke Xu
- Department of Genetics and Genomic Science and Institute for Multiscale Biology
| | - Georgios Voloudakis
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Zhiping Shao
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.,Department of Neuroscience.,Center for Molecular Biology and Genetics of Neurodegeneration
| | - Christopher Bare
- Flow Cytometry Center of Research Excellence, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Joel T Dudley
- Department of Genetics and Genomic Science and Institute for Multiscale Biology
| | - Manuel Mattheisen
- Department of Biomedicine.,Centre for Integrative Sequencing (iSEQ), Aarhus University, Aarhus, Denmark.,The Lundbeck Foundation Initiative of Integrative Psychiatric Research (iPSYCH), Denmark
| | - Nikolaos K Robakis
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.,Department of Neuroscience.,Center for Molecular Biology and Genetics of Neurodegeneration
| | - Vahram Haroutunian
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.,Department of Neuroscience.,Mental Illness Research, Education, and Clinical Center (VISN 2 South), James J. Peters VA Medical Center, Bronx, NY, USA
| | - Panos Roussos
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.,Department of Genetics and Genomic Science and Institute for Multiscale Biology.,Mental Illness Research, Education, and Clinical Center (VISN 2 South), James J. Peters VA Medical Center, Bronx, NY, USA
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5
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Genome-wide identification of splicing QTLs in the human brain and their enrichment among schizophrenia-associated loci. Nat Commun 2017; 8:14519. [PMID: 28240266 PMCID: PMC5333373 DOI: 10.1038/ncomms14519] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 01/06/2017] [Indexed: 12/13/2022] Open
Abstract
Detailed analyses of transcriptome have revealed complexity in regulation of alternative splicing (AS). These AS events often undergo modulation by genetic variants. Here we analyse RNA-sequencing data of prefrontal cortex from 206 individuals in combination with their genotypes and identify cis-acting splicing quantitative trait loci (sQTLs) throughout the genome. These sQTLs are enriched among exonic and H3K4me3-marked regions. Moreover, we observe significant enrichment of sQTLs among disease-associated loci identified by GWAS, especially in schizophrenia risk loci. Closer examination of each schizophrenia-associated loci revealed four regions (each encompasses NEK4, FXR1, SNAP91 or APOPT1), where the index SNP in GWAS is in strong linkage disequilibrium with sQTL SNP(s), suggesting dysregulation of AS as the underlying mechanism of the association signal. Our study provides an informative resource of sQTL SNPs in the human brain, which can facilitate understanding of the genetic architecture of complex brain disorders such as schizophrenia. Alternative splicing of mRNAs occurs in tissue specific manners and may be modulated by genetic variations. Here, Takata and colleagues perform splicing quantitative trait loci analysis (sQTL) of human brain and show significant enrichment of sQTLs among neurological disease-associated loci.
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6
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Dergai M, Iershov A, Novokhatska O, Pankivskyi S, Rynditch A. Evolutionary Changes on the Way to Clathrin-Mediated Endocytosis in Animals. Genome Biol Evol 2016; 8:588-606. [PMID: 26872775 PMCID: PMC4824007 DOI: 10.1093/gbe/evw028] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Endocytic pathways constitute an evolutionarily ancient system that significantly contributed to the eukaryotic cell architecture and to the diversity of cell type-specific functions and signaling cascades, in particular of metazoans. Here we used comparative proteomic studies to analyze the universal internalization route in eukaryotes, clathrin-mediated endocytosis (CME), to address the issues of how this system evolved and what are its specific features. Among 35 proteins crucially required for animal CME, we identified a subset of 22 proteins common to major eukaryotic branches and 13 gradually acquired during evolution. Based on exploration of structure-function relationship between conserved homologs in sister, distantly related and early diverged branches, we identified novel features acquired during evolution of endocytic proteins on the way to animals: Elaborated way of cargo recruitment by multiple sorting proteins, structural changes in the core endocytic complex AP2, the emergence of the Fer/Cip4 homology domain-only protein/epidermal growth factor receptor substrate 15/intersectin functional complex as an additional interaction hub and activator of AP2, as well as changes in late endocytic stages due to recruitment of dynamin/sorting nexin 9 complex and involvement of the actin polymerization machinery. The evolutionary reconstruction showed the basis of the CME process and its subsequent step-by-step development. Documented changes imply more precise regulation of the pathway, as well as CME specialization for the uptake of specific cargoes and cell type-specific functions.
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Affiliation(s)
- Mykola Dergai
- Department of Functional Genomics, Institute of Molecular Biology and Genetics, NASU, Kyiv, Ukraine
| | - Anton Iershov
- Department of Biosynthesis of Nucleic Acids, Institute of Molecular Biology and Genetics, NASU, Kyiv, Ukraine
| | - Olga Novokhatska
- Department of Functional Genomics, Institute of Molecular Biology and Genetics, NASU, Kyiv, Ukraine
| | - Serhii Pankivskyi
- Department of Functional Genomics, Institute of Molecular Biology and Genetics, NASU, Kyiv, Ukraine
| | - Alla Rynditch
- Department of Functional Genomics, Institute of Molecular Biology and Genetics, NASU, Kyiv, Ukraine
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7
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The Stress-Induced Atf3-Gelsolin Cascade Underlies Dendritic Spine Deficits in Neuronal Models of Tuberous Sclerosis Complex. J Neurosci 2015. [PMID: 26224859 DOI: 10.1523/jneurosci.4796-14.2015] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
UNLABELLED Hyperactivation of the mechanistic target of rapamycin (mTOR) kinase, as a result of loss-of-function mutations in tuberous sclerosis complex 1 (TSC1) or TSC2 genes, causes protein synthesis dysregulation, increased cell size, and aberrant neuronal connectivity. Dysregulated synthesis of synaptic proteins has been implicated in the pathophysiology of autism spectrum disorder (ASD) associated with TSC and fragile X syndrome. However, cell type-specific translational profiles in these disease models remain to be investigated. Here, we used high-fidelity and unbiased Translating Ribosome Affinity Purification (TRAP) methodology to purify ribosome-associated mRNAs and identified translational alterations in a rat neuronal culture model of TSC. We find that expression of many stress and/or activity-dependent proteins is highly induced while some synaptic proteins are repressed. Importantly, transcripts for the activating transcription factor-3 (Atf3) and mitochondrial uncoupling protein-2 (Ucp2) are highly induced in Tsc2-deficient neurons, as well as in a neuron-specific Tsc1 conditional knock-out mouse model, and show differential responses to the mTOR inhibitor rapamycin. Gelsolin, a known target of Atf3 transcriptional activity, is also upregulated. shRNA-mediated block of Atf3 induction suppresses expression of gelsolin, an actin-severing protein, and rescues spine deficits found in Tsc2-deficient neurons. Together, our data demonstrate that a cell-autonomous program consisting of a stress-induced Atf3-gelsolin cascade affects the change in dendritic spine morphology following mTOR hyperactivation. This previously unidentified molecular cascade could be a therapeutic target for treating mTORopathies. SIGNIFICANCE STATEMENT Tuberous sclerosis complex (TSC) is a genetic disease associated with epilepsy and autism. Dysregulated protein synthesis has been implicated as a cause of this disease. However, cell type-specific translational profiles that are aberrant in this disease are unknown. Here we show that expression of many stress and/or activity-dependent proteins is highly induced while some synaptic proteins are repressed in neurons missing the Tsc2 gene expression. Identification of genes whose translation is abnormal in TSC may provide insights to previously unidentified therapeutic targets.
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Narayanan B, Ethridge LE, O'Neil K, Dunn S, Mathew I, Tandon N, Calhoun VD, Ruaño G, Kocherla M, Windemuth A, Clementz BA, Tamminga CA, Sweeney JA, Keshavan MS, Pearlson GD. Genetic Sources of Subcomponents of Event-Related Potential in the Dimension of Psychosis Analyzed From the B-SNIP Study. Am J Psychiatry 2015; 172:466-78. [PMID: 25615564 PMCID: PMC4455958 DOI: 10.1176/appi.ajp.2014.13101411] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECTIVE Biological risk factors underlying psychosis are poorly understood. Biological underpinnings of the dimension of psychosis can be derived using genetic associations with intermediate phenotypes such as subcomponents of auditory event-related potentials (ERPs). Various ERP subcomponent abnormalities in schizophrenia and psychotic bipolar disorder are heritable and are expressed in unaffected relatives, although studies investigating genetic contributions to ERP abnormalities are limited. The authors used a novel parallel independent component analysis (para-ICA) to determine which empirically derived gene clusters are associated with data-driven ERP subcomponents, assuming a complex etiology underlying psychosis. METHOD The authors examined the multivariate polygenic association of ERP subcomponents from 64-channel auditory oddball data in 144 individuals with schizophrenia, 210 psychotic bipolar disorder probands, and 95 healthy individuals from the multisite Bipolar-Schizophrenia Network on Intermediate Phenotypes study. Data were reduced by principal components analysis to two target and one standard ERP waveforms. Multivariate association of compressed ERP waveforms with a set of 20,329 single-nucleotide polymorphisms (SNPs) (reduced from a 1-million-SNP array) was examined using para-ICA. Genes associated with SNPs were further examined using pathway analysis tools. RESULTS Para-ICA identified four ERP components that were significantly correlated with three genetic components. Enrichment analysis revealed complement immune response pathway and multiple processes that significantly mediate ERP abnormalities in psychosis, including synaptic cell adhesion, axon guidance, and neurogenesis. CONCLUSIONS This study identified three genetic components comprising multiple genes mediating ERP subcomponent abnormalities in schizophrenia and psychotic bipolar disorder. The data suggest a possible polygenic structure comprising genes influencing key neurodevelopmental processes, neural circuitry, and brain function mediating biological pathways plausibly associated with psychosis.
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Affiliation(s)
- Balaji Narayanan
- Olin Neuropsychiatry Research Center, Institute of Living, Hartford, CT-06106
| | - Lauren E. Ethridge
- Department of Psychiatry, UT Southwestern Medical School, Dallas, TX-75390
| | - Kasey O'Neil
- Olin Neuropsychiatry Research Center, Institute of Living, Hartford, CT-06106
| | - Sabra Dunn
- Olin Neuropsychiatry Research Center, Institute of Living, Hartford, CT-06106
| | - Ian Mathew
- Department of Psychiatry, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA-02215 and
| | - Neeraj Tandon
- Department of Psychiatry, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA-02215 and
| | - Vince D. Calhoun
- Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, NM, 87131,The Mind Research Network, Albuquerque, NM-87106,Departments of Psychiatry & Neurobiology, Yale University School of Medicine, New Haven, CT-06520
| | - Gualberto Ruaño
- Genetics Research Center, Hartford Hospital, Hartford, CT-06106,Genomas Inc, Hartford, CT-06106
| | - Mohan Kocherla
- Genetics Research Center, Hartford Hospital, Hartford, CT-06106,Genomas Inc, Hartford, CT-06106
| | | | | | - Carol A. Tamminga
- Department of Psychiatry, UT Southwestern Medical School, Dallas, TX-75390
| | - John A. Sweeney
- Department of Psychiatry, UT Southwestern Medical School, Dallas, TX-75390
| | - Matcheri S. Keshavan
- Department of Psychiatry, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA-02215 and
| | - Godfrey D. Pearlson
- Olin Neuropsychiatry Research Center, Institute of Living, Hartford, CT-06106,Departments of Psychiatry & Neurobiology, Yale University School of Medicine, New Haven, CT-06520
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9
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Ando K, Brion JP, Stygelbout V, Suain V, Authelet M, Dedecker R, Chanut A, Lacor P, Lavaur J, Sazdovitch V, Rogaeva E, Potier MC, Duyckaerts C. Clathrin adaptor CALM/PICALM is associated with neurofibrillary tangles and is cleaved in Alzheimer's brains. Acta Neuropathol 2013; 125:861-78. [PMID: 23589030 DOI: 10.1007/s00401-013-1111-z] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2012] [Revised: 02/20/2013] [Accepted: 03/24/2013] [Indexed: 02/07/2023]
Abstract
PICALM, a clathrin adaptor protein, plays important roles in clathrin-mediated endocytosis in all cell types. Recently, genome-wide association studies identified single nucleotide polymorphisms in PICALM gene as genetic risk factors for late-onset Alzheimer disease (LOAD). We analysed by western blotting with several anti-PICALM antibodies the pattern of expression of PICALM in human brain extracts. We found that PICALM was abnormally cleaved in AD samples and that the level of the uncleaved 65-75 kDa full-length PICALM species was significantly decreased in AD brains. Cleavage of human PICALM after activation of endogenous calpain or caspase was demonstrated in vitro. Immunohistochemistry revealed that PICALM was associated in situ with neurofibrillary tangles, co-localising with conformationally abnormal and hyperphosphorylated tau in LOAD, familial AD and Down syndrome cases. PHF-tau proteins co-immunoprecipitated with PICALM. PICALM was highly expressed in microglia in LOAD. These observations suggest that PICALM is associated with the development of AD tau pathology. PICALM cleavage could contribute to endocytic dysfunction in AD.
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Affiliation(s)
- Kunie Ando
- Laboratoire de Neuropathologie Escourolle, Hôpital de la Pitié-Salpêtrière, AP-HP, Paris, France
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10
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Crish SD, Dapper JD, MacNamee SE, Balaram P, Sidorova TN, Lambert WS, Calkins DJ. Failure of axonal transport induces a spatially coincident increase in astrocyte BDNF prior to synapse loss in a central target. Neuroscience 2012; 229:55-70. [PMID: 23159315 DOI: 10.1016/j.neuroscience.2012.10.069] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 10/04/2012] [Accepted: 10/24/2012] [Indexed: 01/07/2023]
Abstract
Failure of anterograde transport to distal targets in the brain is a common feature of neurodegenerative diseases. We have demonstrated in rodent models of glaucoma, the most common optic neuropathy, early loss of anterograde transport along the retinal ganglion cell (RGC) projection to the superior colliculus (SC) is retinotopic and followed by a period of persistence of RGC axon terminals and synapses through unknown molecular pathways. Here we use the DBA/2J mouse model of hereditary glaucoma and an acute rat model to demonstrate that retinotopically focal transport deficits in the SC are accompanied by a spatially coincident increase in brain-derived neurotrophic factor (BDNF), especially in hypertrophic astrocytes. These neurochemical changes occur prior to loss of RGC synapses in the DBA/2J SC. In contrast to BDNF protein, levels of Bdnf mRNA decreased with transport failure, even as mRNA encoding synaptic structures remained unchanged. In situ hybridization signal for Bdnf mRNA was the strongest in SC neurons, and labeling for the immature precursor pro-BDNF was very limited. Subcellular fractionation of SC indicated that membrane-bound BDNF decreased with age in the DBA/2J, while BDNF released from vesicles remained high. These results suggest that in response to diminished axonal function, activated astrocytes in the brain may sequester mature BDNF released from target neurons to counter stressors that otherwise would challenge survival of projection synapses.
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Affiliation(s)
- S D Crish
- The Vanderbilt Eye Institute, Vanderbilt University Medical Center, 11425 Langford Medical Research Building IV, 2213 Garland Avenue, Nashville, TN 37232, USA.
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Goes FS, Hamshere ML, Seifuddin F, Pirooznia M, Belmonte-Mahon P, Breuer R, Schulze T, Nöthen M, Cichon S, Rietschel M, Holmans P, Zandi PP, Craddock N, Potash JB. Genome-wide association of mood-incongruent psychotic bipolar disorder. Transl Psychiatry 2012; 2:e180. [PMID: 23092984 PMCID: PMC3565814 DOI: 10.1038/tp.2012.106] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 09/06/2012] [Indexed: 11/09/2022] Open
Abstract
Mood-incongruent psychotic features (MICP) are familial symptoms of bipolar disorder (BP) that also occur in schizophrenia (SZ), and may represent manifestations of shared etiology between the major psychoses. In this study we have analyzed three large samples of BP with imputed genome-wide association data and have performed a meta-analysis of 2196 cases with MICP and 8148 controls. We found several regions with suggestive evidence of association (P<10(-6)), although no marker met genome-wide significance criteria. The top associations were on chromosomes: 6q14.2 within the PRSS35/SNAP91 gene complex (rs1171113, P=9.67 × 10(-8)); 3p22.2 downstream of TRANK/LBA1 (rs9834970, P=9.71 × 10(-8)); and 14q24.2 in an intron of NUMB (rs2333194, P=7.03 × 10(-7)). These associations were present in all three samples, and both rs1171113 and rs2333194 were found to be overrepresented in an analysis of MICP cases compared with all other BP cases. To test the relationship of MICP with SZ, we performed polygenic analysis using the Psychiatric GWAS Consortium SZ results and found evidence of association between SZ polygenes and the presence of MICP in BP cases (meta-analysis P=0.003). In summary, our analysis of the MICP phenotype in BP has provided suggestive evidence for association of common variants in several genes expressed in the nervous system. The results of our polygenic analysis provides support for a modest degree of genetic overlap between BP with MICP and SZ, highlighting that phenotypic correlations across syndromes may be due to the influence of polygenic risk factors.
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Affiliation(s)
- F S Goes
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - M L Hamshere
- Department of Psychological Medicine, MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
| | - F Seifuddin
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - M Pirooznia
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - P Belmonte-Mahon
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - R Breuer
- Department of Genetic Epidemiology in Psychiatry, Central Institute of Mental Health, Mannheim, Germany
| | - T Schulze
- Department of Psychiatry and Psychotherapy, University of Göttingen, Göttingen, Germany
| | - M Nöthen
- Department of Genomics, Life & Brain Center, University of Bonn, Bonn, Germany
| | - S Cichon
- Department of Genomics, Life & Brain Center, University of Bonn, Bonn, Germany
| | - M Rietschel
- Department of Genetic Epidemiology in Psychiatry, Central Institute of Mental Health, Mannheim, Germany
| | - P Holmans
- Department of Psychological Medicine, MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
| | - P P Zandi
- Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Bipolar Genome Study (BiGS)
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Psychological Medicine, MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
- Department of Genetic Epidemiology in Psychiatry, Central Institute of Mental Health, Mannheim, Germany
- Department of Psychiatry and Psychotherapy, University of Göttingen, Göttingen, Germany
- Department of Genomics, Life & Brain Center, University of Bonn, Bonn, Germany
- Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
- Department of Psychiatry, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - N Craddock
- Department of Psychological Medicine, MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, UK
| | - J B Potash
- Department of Psychiatry, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
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12
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Maritzen T, Koo SJ, Haucke V. Turning CALM into excitement: AP180 and CALM in endocytosis and disease. Biol Cell 2012; 104:588-602. [DOI: 10.1111/boc.201200008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 05/23/2012] [Indexed: 11/28/2022]
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13
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Schwartz CM, Cheng A, Mughal MR, Mattson MP, Yao PJ. Clathrin assembly proteins AP180 and CALM in the embryonic rat brain. J Comp Neurol 2010; 518:3803-18. [PMID: 20653035 DOI: 10.1002/cne.22425] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Clathrin-coated vesicles are known to play diverse and pivotal roles in cells. The proper formation of clathrin-coated vesicles is dependent on, and highly regulated by, a large number of clathrin assembly proteins. These assembly proteins likely determine the functional specificity of clathrin-coated vesicles, and together they control a multitude of intracellular trafficking pathways, including those involved in embryonic development. In this study, we focus on two closely related clathrin assembly proteins, AP180 and CALM (clathrin assembly lymphoid myeloid leukemia protein), in the developing embryonic rat brain. We find that AP180 begins to be expressed at embryonic day 14 (E14), but only in postmitotic cells that have acquired a neuronal fate. CALM, on the other hand, is expressed as early as E12, by both neural stem cells and postmitotic neurons. In vitro loss-of-function studies using RNA interference (RNAi) indicate that AP180 and CALM are dispensable for some aspects of embryonic neurogenesis but are required for the growth of postmitotic neurons. These results identify the developmental stage of AP180 and CALM expression and suggest that each protein has distinct functions in neural development.
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Affiliation(s)
- Catherine M Schwartz
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, Baltimore, Maryland 21224, USA
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14
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Wu F, Mattson MP, Yao PJ. Neuronal activity and the expression of clathrin-assembly protein AP180. Biochem Biophys Res Commun 2010; 402:297-300. [PMID: 20937255 DOI: 10.1016/j.bbrc.2010.10.018] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Accepted: 10/05/2010] [Indexed: 11/15/2022]
Abstract
The clathrin-assembly protein AP180 is known to promote the assembly of clathrin-coated vesicles in the neuron. However, it is unknown whether the expression of AP180 is influenced by neuronal activity. In this study, we report that chronic depolarization results in a reduction of AP180 from hippocampal neurons, while acute depolarization causes a dispersed synaptic distribution of AP180. Activity-induced effects are observed only for AP180, but not for the structurally-related clathrin-assembly proteins CALM, epsin1, or HIP1. These findings suggest that AP180 levels and synaptic distribution are highly sensitive to neuronal activity.
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Affiliation(s)
- Fangbai Wu
- Laboratory of Neurosciences, NIA/NIH, Baltimore, MD 21224, United States
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15
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Zanazzi G, Matthews G. The molecular architecture of ribbon presynaptic terminals. Mol Neurobiol 2009; 39:130-48. [PMID: 19253034 PMCID: PMC2701268 DOI: 10.1007/s12035-009-8058-z] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Accepted: 02/04/2009] [Indexed: 12/24/2022]
Abstract
The primary receptor neurons of the auditory, vestibular, and visual systems encode a broad range of sensory information by modulating the tonic release of the neurotransmitter glutamate in response to graded changes in membrane potential. The output synapses of these neurons are marked by structures called synaptic ribbons, which tether a pool of releasable synaptic vesicles at the active zone where glutamate release occurs in response to calcium influx through L-type channels. Ribbons are composed primarily of the protein, RIBEYE, which is unique to ribbon synapses, but cytomatrix proteins that regulate the vesicle cycle in conventional terminals, such as Piccolo and Bassoon, also are found at ribbons. Conventional and ribbon terminals differ, however, in the size, molecular composition, and mobilization of their synaptic vesicle pools. Calcium-binding proteins and plasma membrane calcium pumps, together with endomembrane pumps and channels, play important roles in calcium handling at ribbon synapses. Taken together, emerging evidence suggests that several molecular and cellular specializations work in concert to support the sustained exocytosis of glutamate that is a hallmark of ribbon synapses. Consistent with its functional importance, abnormalities in a variety of functional aspects of the ribbon presynaptic terminal underlie several forms of auditory neuropathy and retinopathy.
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Affiliation(s)
- George Zanazzi
- Department of Neurobiology & Behavior, State Universtiy of New York, Stony Brook, NY 11794-5230, USA
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16
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Clathrin assembly protein AP180 and CALM differentially control axogenesis and dendrite outgrowth in embryonic hippocampal neurons. J Neurosci 2008; 28:10257-71. [PMID: 18842885 DOI: 10.1523/jneurosci.2471-08.2008] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Emerging data suggest that, much like epithelial cells, the polarized growth of neurons requires both the secretory and endocytic pathways. The clathrin assembly proteins AP180 and CALM (clathrin assembly lymphoid myeloid protein) are known to be involved in clathrin-mediated endocytosis, but their roles in mammalian neurons and, in particular, in developmental processes before synaptogenesis are unknown. Here we provide evidence that AP180 and CALM play critical roles in establishing the polarity and controlling the growth of axons and dendrites in embryonic hippocampal neurons. Knockdown of AP180 primarily impairs axonal development, whereas reducing CALM levels results in dendritic dystrophy. Conversely, neurons that overexpress AP180 or CALM generate multiple axons. Ultrastructural analysis shows that CALM affiliates with a wider range of intracellular trafficking organelles than does AP180. Functional analysis shows that endocytosis is reduced in both AP180-deficient and CALM-deficient neurons. Additionally, CALM-deficient neurons show disrupted secretory transport. Our data demonstrate previously unknown functions for AP180 and CALM in intracellular trafficking that are essential in the growth of neurons.
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17
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Petralia RS, Yao PJ. AP180 and CALM in the developing hippocampus: expression at the nascent synapse and localization to trafficking organelles. J Comp Neurol 2007; 504:314-27. [PMID: 17640037 DOI: 10.1002/cne.21454] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Genetic and biochemical evidence has established that clathrin assembly protein AP180 is required for the proper assembly of synaptic vesicles via clathrin-mediated endocytosis. The assembly protein CALM, the ubiquitously expressed homolog of AP180, also regulates the formation of clathrin-coated vesicles. In this study we found high expression levels of AP180 and CALM in hippocampal tissues as early as embryonic day 18, before the expression of synaptophysin. We also used immunoelectron microscopy to establish the distribution of AP180 and CALM in the developing hippocampal synapses. We found AP180 and CALM in synapses at all developmental stages and in nonsynaptic growing processes. In addition to localization on the plasma membrane and clathrin-coated vesicles that originated from the plasma membrane, we also report the presence of AP180 and CALM on other types of membrane structures. Our observations link AP180 and CALM to multiple vesicular organelles and raise the possibility that these proteins may play additional roles in developing neurons.
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Affiliation(s)
- Ronald S Petralia
- Laboratory of Neurochemistry, NIDCD/NIH, Bethesda, Maryland 20892, USA
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18
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Leshchyns'ka I, Sytnyk V, Richter M, Andreyeva A, Puchkov D, Schachner M. The Adhesion Molecule CHL1 Regulates Uncoating of Clathrin-Coated Synaptic Vesicles. Neuron 2006; 52:1011-25. [PMID: 17178404 DOI: 10.1016/j.neuron.2006.10.020] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2006] [Revised: 08/17/2006] [Accepted: 10/20/2006] [Indexed: 12/28/2022]
Abstract
In searching for binding partners of the intracellular domain of the immunoglobulin superfamily adhesion molecule CHL1, we identified the clathrin-uncoating ATPase Hsc70. CHL1 gene ablation resulted in reduced targeting of Hsc70 to the synaptic plasma membrane and synaptic vesicles, suggesting CHL1 as a synapse-targeting cue for Hsc70. CHL1 accumulates in presynaptic membranes and, in response to synapse activation, is targeted to synaptic vesicles by endocytosis. CHL1 deficiency or disruption of the CHL1/Hsc70 complex results in accumulation of abnormally high levels of clathrin-coated synaptic vesicles with a reduced ability to release clathrin. Generation of new clathrin-coated synaptic vesicles in an activity-dependent manner is inhibited when the CHL1/Hsc70 complex is disrupted, resulting in impaired uptake and release of FM dyes in synaptic boutons. Abnormalities in clathrin-dependent synaptic vesicle recycling may thus underlie brain malfunctions in humans and mice that carry mutations in the CHL1 gene.
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Affiliation(s)
- Iryna Leshchyns'ka
- Zentrum für Molekulare Neurobiologie, Universität Hamburg, Martinistrasse 52, 20246 Hamburg, Germany
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19
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Evergren E, Zotova E, Brodin L, Shupliakov O. Differential efficiency of the endocytic machinery in tonic and phasic synapses. Neuroscience 2006; 141:123-31. [PMID: 16675130 DOI: 10.1016/j.neuroscience.2006.03.038] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Revised: 03/16/2006] [Accepted: 03/22/2006] [Indexed: 11/29/2022]
Abstract
Efficient synaptic vesicle membrane recycling is one of the key factors required to sustain neurotransmission. We investigated potential differences in the compensatory endocytic machineries in two glutamatergic synapses with phasic and tonic patterns of activity in the lamprey spinal cord. Post-embedding immunocytochemistry demonstrated that proteins involved in synaptic vesicle recycling, including dynamin, intersectin, and synapsin, occur at higher levels (labeling per vesicle) in tonic dorsal column synapses than in phasic reticulospinal synapses. Synaptic vesicle protein 2 occurred at similar levels in the two types of synapse. After challenging the synapses with high potassium stimulation for 30 min the vesicle pool in the tonic synapse was maintained at a normal level, while that in the phasic synapse was partly depleted along with expansion of the plasma membrane and accumulation of clathrin-coated intermediates at the periactive zone. Thus, our results indicate that an increased efficiency of the endocytic machinery in a synapse may be one of the factors underlying the ability to sustain neurotransmission at high rates.
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Affiliation(s)
- E Evergren
- Department of Neuroscience, Center of Excellence in Developmental Biology, Karolinska Institutet, 171 77 Stockholm, Sweden
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20
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Conboy L, Murphy KJ, Regan CM. Amyloid precursor protein expression in the rat hippocampal dentate gyrus modulates during memory consolidation. J Neurochem 2005; 95:1677-88. [PMID: 16236032 DOI: 10.1111/j.1471-4159.2005.03484.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Despite advances in our understanding of the basic biology of amyloid precursor protein (APP), the normal physiological function(s) of APP in learning and memory remains unclear. Here we show increased APP degradation in the hippocampus to be associated with the consolidation of a passive avoidance response. Neurone-specific APP695 expression became transiently reduced 2-4 h post-training through association with endosomal adaptin proteins and enhanced internalization. By contrast, internalization of glial-associated APP containing a Kunitz protease inhibitor-like domain (APP-KPI) was dependent on the low-density lipoprotein receptor-related protein (LRP). In addition, LRP expression and association with apolipoprotein E increased in the 2-4 h post-training period. The LRP antagonist receptor-associated protein prevented the APP-KPI internalization and LRP-apolipoprotein E association and this resulted in amnesia. Degradation of APP695 and APP-KPI did not appear to be related to alpha-secretase activity, as no learning-associated increase of secreted APP was observed in the CSF. Moreover, as internalization of APP isoforms was observed only in dentate gyrus, it probably relates to the learning-associated restructuring of the perforant path terminals. Memory-associated APP processing in both neuronal and glial compartments points to a role for glial unsheathing of synaptic connections, an event required for the synaptic restructuring that accompanies memory consolidation. These observations may have a direct relevance to understanding the pathophysiology of Alzheimer's disease as beta/gamma-secretase-derived beta-amyloid is formed following internalization of cell surface APP into the endosomal compartment.
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Affiliation(s)
- Lisa Conboy
- Applied Neurotherapeutics Research Group, Department of Pharmacology, Conway Institute, University College Dublin, Belfield, Dublin, Ireland
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21
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Jockusch WJ, Praefcke GJK, McMahon HT, Lagnado L. Clathrin-dependent and clathrin-independent retrieval of synaptic vesicles in retinal bipolar cells. Neuron 2005; 46:869-78. [PMID: 15953416 DOI: 10.1016/j.neuron.2005.05.004] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2004] [Revised: 03/03/2005] [Accepted: 05/02/2005] [Indexed: 10/25/2022]
Abstract
Synaptic vesicles can be retrieved rapidly or slowly, but the molecular basis of these kinetic differences has not been defined. We now show that substantially different sets of molecules mediate fast and slow endocytosis in the synaptic terminal of retinal bipolar cells. Capacitance measurements of membrane retrieval were made in terminals in which peptides and protein domains were introduced to disrupt known interactions of clathrin, the AP2 adaptor complex, and amphiphysin. All these manipulations caused a selective inhibition of the slow phase of membrane retrieval (time constant approximately 10 s), leaving the fast phase (approximately 1 s) intact. Slow endocytosis after strong stimulation was therefore dependent on the formation of clathrin-coated membrane. Fast endocytosis occurring after weaker stimuli retrieves vesicle membrane in a clathrin-independent manner. All compensatory endocytosis required GTP hydrolysis, but only a subset of released vesicles were primed for fast, clathrin-independent endocytosis.
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Affiliation(s)
- Wolf J Jockusch
- Medical Research Council, Laboratory of Molecular Biology, Cambridge, United Kingdom
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22
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Burman JL, Wasiak S, Ritter B, de Heuvel E, McPherson PS. Aftiphilin is a component of the clathrin machinery in neurons. FEBS Lett 2005; 579:2177-84. [PMID: 15811338 DOI: 10.1016/j.febslet.2005.03.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2005] [Revised: 03/03/2005] [Accepted: 03/03/2005] [Indexed: 11/20/2022]
Abstract
Aftiphilin was identified through a database search for proteins containing binding motifs for the gamma-ear domain of clathrin adaptor protein 1 (AP-1). Here, we demonstrate that aftiphilin is expressed predominantly in brain where it is enriched on clathrin-coated vesicles. In addition to eight gamma-ear-binding motifs, aftiphilin contains two WXXF-acidic motifs that mediate binding to the alpha-ear of clathrin adaptor protein 2 (AP-2) and three FXXFXXF/L motifs that mediate binding to the alpha- and beta2-ear. We demonstrate that aftiphilin uses these motifs for interactions with AP-1 and AP-2 and that it immunoprecipitates these APs but not AP-3 or AP-4 from brain extracts. Aftiphilin demonstrates a brefeldin A sensitive localization to the trans-Golgi network in hippocampal neurons where it co-localizes with AP-1. Aftiphilin is also found at synapses where it co-localizes with synaptophysin and AP-2. Our data suggest a role for aftiphilin in clathrin-mediated trafficking in neurons.
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Affiliation(s)
- Jonathon L Burman
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, 3801 University Street, Montreal, Que., Canada H3A 2B4
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23
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Yao PJ, Petralia RS, Bushlin I, Wang Y, Furukawa K. Synaptic distribution of the endocytic accessory proteins AP180 and CALM. J Comp Neurol 2005; 481:58-69. [PMID: 15558718 DOI: 10.1002/cne.20362] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Clathrin-coated vesicles mediate a variety of endocytosis pathways in cells, including endocytic events at synapses. AP180 and clathrin assembly lymphoid myeloid leukemia protein (CALM) are clathrin accessory proteins that promote the formation of clathrin-coated vesicles. Both proteins bind to membrane lipids through their epsin N-terminal homology domains and interact with clathrin and related protein components through their carboxyl-terminal peptide motifs. We examine their neuronal expression and synaptic distribution. We show that both proteins are detected in synapses but demonstrate different distribution patterns. AP180 is located predominantly in presynaptic profiles, whereas CALM is found nonselectively in pre- and postsynaptic profiles and also in perisynaptic processes. These observations reveal an unexpected relationship between AP180 and the presumed non-neuronal homologue CALM. We propose that both AP180 and CALM function as endocytic accessory proteins at synapses, but each may regulate distinct clathrin pathways.
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Affiliation(s)
- Pamela J Yao
- Laboratory of Neurosciences, National Institute on Aging/National Institutes of Health, Baltimore, Maryland 21224, USA.
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24
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Hull C, von Gersdorff H. Fast endocytosis is inhibited by GABA-mediated chloride influx at a presynaptic terminal. Neuron 2005; 44:469-82. [PMID: 15504327 PMCID: PMC3572843 DOI: 10.1016/j.neuron.2004.10.010] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2003] [Revised: 06/24/2004] [Accepted: 09/13/2004] [Indexed: 10/26/2022]
Abstract
Although multiple kinetic components of synaptic vesicle endocytosis have been identified, it has remained unclear whether neurons can differentially modulate these components. Using membrane capacitance measurements from isolated goldfish bipolar cell terminals, we found that the kinetics of endocytosis in retinal slices (single exponential decay; tau > 10 s) were significantly slower than those in acutely dissociated terminals (double exponential decay; tau(fast) approximately 1-2 s; tau(slow) > 10 s). Surprisingly, GABA(A) and/or GABA(C) receptor antagonists restored the fast component of endocytosis to terminals in retinal slices. Blocking GABAergic feedback from reciprocal synapses or removing external Cl(-) ions also allowed for fast endocytosis. Elevating internal Cl(-) via the patch pipette invariably slowed endocytosis, even in terminals dialyzed with increased Ca(2+) buffer. These results suggest a new role for GABA and Cl(-) ions in blocking the trigger for fast endocytosis at this ribbon-type synapse.
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25
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Hosoya O, Tsutsui K, Tsutsui K. Localized expression of amphiphysin Ir, a retina-specific variant of amphiphysin I, in the ribbon synapse and its functional implication. Eur J Neurosci 2004; 19:2179-87. [PMID: 15090044 DOI: 10.1111/j.0953-816x.2004.03340.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the vertebrate retina, presynaptic terminals of photoreceptors and bipolar cells form ribbon synapses and release neurotransmitter continuously. Endocytic machinery in the ribbon synapse is likely to differ from that in conventional synapses because of the much higher rate of synaptic vesicle recycling. However, protein components of the ribbon synapse identified so far are quite similar to those of the conventional synapses. Recently we identified amphiphysin I splice variants, termed amphiphysin Ir, that are transcribed specifically in retina from the authentic amphiphysin I gene [Y. Terada et al. (2002) FEBS Lett., 519, 185-190]. Amphiphysin I is a nerve terminal-enriched protein, and involved in synaptic vesicle endocytosis as heterodimer with amphiphysin II, an isoform of amphiphysin I. We report here that the retina-specific amphiphysin Ir is expressed exclusively in the ribbon synapse and not in conventional synapses. This is the first endocytosis-related, ribbon synapse-specific protein identified in the retina. By immunoprecipitation and double-immunolabelling, amphiphysin Ir was shown to be associated not only with amphiphysin II, but also with dynamin, clathrin and alpha-adaptin that are involved in synaptic vesicle recycling. The results suggest that endocytosis of the synaptic vesicle membrane in retinal ribbon synapses proceeds through a pathway similar to the one that is used in conventional synapses, although amphiphysin Ir is substituted for amphiphysin I. Amphiphysin Ir may play an essential role in the avid endocytic activity of ribbon synapses by associating with yet unknown protein partner(s) through its large insertional domain, which is absent from the conventional amphiphysin I.
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Affiliation(s)
- Osamu Hosoya
- Department of Neuroanatomy and Neurobiology, Graduate School of Medicine and Dentistry, Okayama University, 2-5-1 Shikata-cho, Okayama 700-8558, Japan
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26
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Barth M, Holstein SEH. Identification and functional characterization of Arabidopsis AP180, a binding partner of plant alphaC-adaptin. J Cell Sci 2004; 117:2051-62. [PMID: 15054111 DOI: 10.1242/jcs.01062] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clathrin-mediated endocytosis is a well-studied uptake mechanism for nutrients and signalling receptors in mammalian cells that depends on the coordinated interaction of coat proteins and endocytic network proteins to perform the internalization. In this process AP180 promotes the assembly of clathrin triskelia into coated membrane patches at the plasma membrane, while alpha-adaptin interacts with various network proteins that are in turn required for the budding of the coated pits. The process of clathrin-mediated endocytosis in plants has not been dissected at the molecular level, nor have the members of an analogous uptake machinery been functionally described. In this respect, we have investigated the AP180 and alpha-adaptin orthologs from Arabidopsis thaliana: At-AP180 and At-alphaC-Ad. Both plant proteins display the same structural features as their mammalian counterparts and fulfill the same basic functions. To identify their interacting partners, the ear region of At-alphaC-Ad and the C-terminal region of At-AP180 were used as fusion proteins in pull-down experiments and plasmon-resonance measurements. At-alphaC-Ad binds several mammalian endocytic proteins, and its interaction with At-AP180 requires the DPF motif. At-AP180 functions as a clathrin assembly protein that promotes the formation of cages with an almost uniform size distribution. Deletion of the single DLL motif abolished the assembly activity of At-AP180 almost completely, but did not affect its binding to triskelia, suggesting the existence of additional binding determinants.
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Affiliation(s)
- Meike Barth
- University of Heidelberg, Department of Cell Biology, Heidelberg Institute for Plant Sciences, 69120 Heidelberg, Im Neuenheimer Feld 230, Germany
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27
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Yao PJ. Synaptic frailty and clathrin-mediated synaptic vesicle trafficking in Alzheimer's disease. Trends Neurosci 2004; 27:24-9. [PMID: 14698607 DOI: 10.1016/j.tins.2003.10.012] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Pamela J Yao
- Laboratory of Neurosciences, National Institute on Aging/NIH, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA.
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28
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Yao PJ, Zhang P, Mattson MP, Furukawa K. Heterogeneity of endocytic proteins: distribution of clathrin adaptor proteins in neurons and glia. Neuroscience 2003; 121:25-37. [PMID: 12946697 DOI: 10.1016/s0306-4522(03)00431-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Clathrin adaptor protein (AP)180 is a synaptic protein that regulates the assembly of clathrin-coated vesicles. Several endocytic proteins including AP2, CALM, and epsin 1 have functions or molecular structures similar to AP180. We determined if AP180 associates with functional synapses in cultured hippocampal neurons. We also compared the expression pattern of AP180 with the other endocytic proteins. The distribution of AP180 corresponded with the synaptic vesicle-associated protein synapsin I, and with functional presynaptic terminals labeled with the styryl dye FM1-43. Synaptic AP2 colocalized with AP180, but the distribution of AP2 was not limited to synapses of neurons and it was also expressed in glia. CLAM and epsin 1 immunoreactivities were also detected in both neurons and glia. Unlike AP180, the neuronal immunoreactivity of CALM was not intense in the synaptic puncta. Epsin 1 immunoreactivity was found in both synaptic and extrasynaptic sites, and its synaptic distribution only partially overlapped with that of AP180. These results support roles for AP180 in synaptic function in neurons. The findings also provide information on the distribution of AP2, CALM, and epsin 1 in cells of the nervous system that suggest different roles for these endocytic proteins in the biology of these cells.
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Affiliation(s)
- P J Yao
- Laboratory of Neurosciences, Gerontology Research Center, NIA/NIH, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA.
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29
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Yao PJ, Zhu M, Pyun EI, Brooks AI, Therianos S, Meyers VE, Coleman PD. Defects in expression of genes related to synaptic vesicle trafficking in frontal cortex of Alzheimer's disease. Neurobiol Dis 2003; 12:97-109. [PMID: 12667465 DOI: 10.1016/s0969-9961(02)00009-8] [Citation(s) in RCA: 172] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Loss of synapses correlates with cognitive decline in Alzheimer's disease (AD). However, molecular mechanisms underlying the synaptic dysfunction and loss are not well understood. In this study, microarray analysis of brain tissues from five AD cases revealed a reduced expression of a group of related genes, all of which are involved in synaptic vesicle (SV) trafficking. By contrast, several synaptic genes with functions other than vesicle trafficking remained unchanged. Quantitative RT-PCR confirmed and expanded the microarray findings. Furthermore, immunoblotting showed that the protein level of at least one of these gene products, dynamin I, correlated with its reduced transcript. Immunhistochemical analysis exhibited an altered distribution of dynamin I immunolabeling in AD neurons. Microarray analysis of transgenic mice with mutated amyloid precursor protein showed that although the transcript levels for some of the SV trafficking-related genes are also decreased, the change in dynamin did not replicate the AD pattern. The results suggest a link among SV vesicle-trafficking pathways, synaptic malfunction, and AD pathogenesis.
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Affiliation(s)
- Pamela J Yao
- Department of Neurobiology & Anatomy, Center for Aging & Developmental Biology, University of Rochester, Rochester, NY 14642, USA
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