1
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Adamowski M, Matijević I, Friml J. Developmental patterning function of GNOM ARF-GEF mediated from the cell periphery. eLife 2024; 13:e68993. [PMID: 38381485 PMCID: PMC10881123 DOI: 10.7554/elife.68993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 02/05/2024] [Indexed: 02/22/2024] Open
Abstract
The GNOM (GN) Guanine nucleotide Exchange Factor for ARF small GTPases (ARF-GEF) is among the best studied trafficking regulators in plants, playing crucial and unique developmental roles in patterning and polarity. The current models place GN at the Golgi apparatus (GA), where it mediates secretion/recycling, and at the plasma membrane (PM) presumably contributing to clathrin-mediated endocytosis (CME). The mechanistic basis of the developmental function of GN, distinct from the other ARF-GEFs including its closest homologue GNOM-LIKE1 (GNL1), remains elusive. Insights from this study largely extend the current notions of GN function. We show that GN, but not GNL1, localizes to the cell periphery at long-lived structures distinct from clathrin-coated pits, while CME and secretion proceed normally in gn knockouts. The functional GN mutant variant GNfewerroots, absent from the GA, suggests that the cell periphery is the major site of GN action responsible for its developmental function. Following inhibition by Brefeldin A, GN, but not GNL1, relocates to the PM likely on exocytic vesicles, suggesting selective molecular associations en route to the cell periphery. A study of GN-GNL1 chimeric ARF-GEFs indicates that all GN domains contribute to the specific GN function in a partially redundant manner. Together, this study offers significant steps toward the elucidation of the mechanism underlying unique cellular and development functions of GNOM.
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Affiliation(s)
- Maciek Adamowski
- Institute of Science and Technology AustriaKlosterneuburgAustria
- Plant Breeding and Acclimatization Institute – National Research InstituteBłoniePoland
| | - Ivana Matijević
- Institute of Science and Technology AustriaKlosterneuburgAustria
| | - Jiří Friml
- Institute of Science and Technology AustriaKlosterneuburgAustria
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2
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Wu LG, Chan CY. Membrane transformations of fusion and budding. Nat Commun 2024; 15:21. [PMID: 38167896 PMCID: PMC10761761 DOI: 10.1038/s41467-023-44539-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 12/15/2023] [Indexed: 01/05/2024] Open
Abstract
Membrane fusion and budding mediate fundamental processes like intracellular trafficking, exocytosis, and endocytosis. Fusion is thought to open a nanometer-range pore that may subsequently close or dilate irreversibly, whereas budding transforms flat membranes into vesicles. Reviewing recent breakthroughs in real-time visualization of membrane transformations well exceeding this classical view, we synthesize a new model and describe its underlying mechanistic principles and functions. Fusion involves hemi-to-full fusion, pore expansion, constriction and/or closure while fusing vesicles may shrink, enlarge, or receive another vesicle fusion; endocytosis follows exocytosis primarily by closing Ω-shaped profiles pre-formed through the flat-to-Λ-to-Ω-shape transition or formed via fusion. Calcium/SNARE-dependent fusion machinery, cytoskeleton-dependent membrane tension, osmotic pressure, calcium/dynamin-dependent fission machinery, and actin/dynamin-dependent force machinery work together to generate fusion and budding modes differing in pore status, vesicle size, speed and quantity, controls release probability, synchronization and content release rates/amounts, and underlies exo-endocytosis coupling to maintain membrane homeostasis. These transformations, underlying mechanisms, and functions may be conserved for fusion and budding in general.
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Affiliation(s)
- Ling-Gang Wu
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA.
| | - Chung Yu Chan
- National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
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3
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Lazki-Hagenbach P, Kleeblatt E, Fukuda M, Ali H, Sagi-Eisenberg R. The Underlying Rab Network of MRGPRX2-Stimulated Secretion Unveils the Impact of Receptor Trafficking on Secretory Granule Biogenesis and Secretion. Cells 2024; 13:93. [PMID: 38201297 PMCID: PMC10778293 DOI: 10.3390/cells13010093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Revised: 12/18/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
MRGPRX2, the human member of the MAS-related G-protein-coupled receptors (GPCRs), mediates the immunoglobulin E (IgE)-independent responses of a subset of mast cells (MCs) that are associated with itch, pain, neurogenic inflammation, and pseudoallergy to drugs. The mechanisms underlying the responses of MRGPRX2 to its multiple and diverse ligands are still not completely understood. Given the close association between GPCR location and function, and the key role played by Rab GTPases in controlling discrete steps along vesicular trafficking, we aimed to reveal the vesicular pathways that directly impact MRGPRX2-mediated exocytosis by identifying the Rabs that influence this process. For this purpose, we screened 43 Rabs for their functional and phenotypic impacts on MC degranulation in response to the synthetic MRGPRX2 ligand compound 48/80 (c48/80), which is often used as the gold standard of MRGPRX2 ligands, or to substance P (SP), an important trigger of neuroinflammatory MC responses. Results of this study highlight the important roles played by macropinocytosis and autophagy in controlling MRGPRX2-mediated exocytosis, demonstrating a close feedback control between the internalization and post-endocytic trafficking of MRGPRX2 and its triggered exocytosis.
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Affiliation(s)
- Pia Lazki-Hagenbach
- Department of Cell and Developmental Biology, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel; (P.L.-H.); (E.K.)
| | - Elisabeth Kleeblatt
- Department of Cell and Developmental Biology, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel; (P.L.-H.); (E.K.)
| | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Integrative Life Sciences, Graduate School of Life Sciences, Tohoku University, Aobayama, Aoba-ku, Sendai 980-8578, Miyagi, Japan;
| | - Hydar Ali
- Department of Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA;
| | - Ronit Sagi-Eisenberg
- Department of Cell and Developmental Biology, Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel; (P.L.-H.); (E.K.)
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
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4
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Erofeeva LM, Mnikhovich MV, Bezuglova TB. Morphofunctional Parameters of Mast Cell Population in Experimentally Induced Breast Cancer in Rats. Bull Exp Biol Med 2023; 175:513-518. [PMID: 37776399 DOI: 10.1007/s10517-023-05897-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Indexed: 10/02/2023]
Abstract
Structural and functional parameters of mast cells (MC) in rat mammary glands during experimentally provoked breast cancer were studied by the cytogram, index of cell saturation with secretory products, and degranulation index. The cytogram was calculated in histological sections stained with toluidine blue. The functional conditions of MC were determined by electron microscopy. The study revealed expansion of MC population and activation of their functional state evidenced by significant prevalence of cells with high degranulation degree and reduced saturation index. At the ultrastructural level, MC were characterized by deformation, polymorphism, paleness of secretory granules, and elevation of the number of lacunae in the cytoplasm. The study showed that MC are active players in tumor microenvironment. Remembering heteromorphism of MC, further study of their role in pathogenesis of various tumor diseases seems promising.
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Affiliation(s)
- L M Erofeeva
- A. P. Avtsyn Research Institute of Human Morphology, B. V. Pet-rovsky Russian Research Center of Surgery, Moscow, Russia.
| | - M V Mnikhovich
- A. P. Avtsyn Research Institute of Human Morphology, B. V. Pet-rovsky Russian Research Center of Surgery, Moscow, Russia
| | - T B Bezuglova
- A. P. Avtsyn Research Institute of Human Morphology, B. V. Pet-rovsky Russian Research Center of Surgery, Moscow, Russia
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5
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Elías-Sáenz I, Rodríguez-Otero N, Fernández-Lozano C, Bartolomé-Zavala B, González-de-Olano D. Zymogen granule protein 16-like and carboxypeptidase B, new allergens in hedgehog hypersensitivity. Ann Allergy Asthma Immunol 2023; 131:273-274. [PMID: 37253408 DOI: 10.1016/j.anai.2023.05.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 05/22/2023] [Accepted: 05/23/2023] [Indexed: 06/01/2023]
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6
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Ramírez-Ponce MP, Flores JA, Barrella L, Alés E. Ketotifen is a microglial stabilizer by inhibiting secretory vesicle acidification. Life Sci 2023; 319:121537. [PMID: 36868401 DOI: 10.1016/j.lfs.2023.121537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 02/22/2023] [Accepted: 02/24/2023] [Indexed: 03/05/2023]
Abstract
AIMS Microglia survey the brain environment by sensing alarm signals to provide the first line of defense against injury or infection after which they acquire an activated phenotype, but they also respond to chemical signals sent from brain mast cells, sentinels of the immune system, when these are degranulated in response to noxious agents. Nevertheless, excessive microglia activation damages the surrounding healthy neural tissue causing progressive loss of neurons and inducing chronic inflammation. Thus, it would be of intense interest the development and application of agents which prevent mast cell mediator release and inhibit the actions of such mediators once released on microglia. MAIN METHODS Fluorescence measurements of fura-2 and quinacrine were used to measure intracellular Ca2+ signaling and exocytotic vesicle fusion in resting and activated microglia. KEY FINDINGS We show that treatment of microglia with a cocktail of mast cell mediators induces microglia activation, phagocytosis, and exocytosis, and reveal by the first-time microglia undergo a phase of vesicular acidification just before the exocytotic fusion occurs. This acidification is an important process for vesicular maturation and contributes with ∼25 % to the content that the vesicle can store and later release by exocytosis. Pre-incubation with ketotifen, a mast cell stabilizer and H1R antagonist completely abolished histamine-mediated calcium signaling and acidification of microglial organelles, and concomitantly reduced the discharge of vesicle contents. SIGNIFICANCE These results highlight a key role for vesicle acidification in microglial physiology and provide a potential therapeutic target for diseases related to mast cell and microglia-mediated neuroinflammation.
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Affiliation(s)
| | - Juan Antonio Flores
- Dpto. de Bioquímica Médica y Biología Molecular e Inmunología, Facultad de Medicina, Universidad de Sevilla, Spain
| | - Lorenzo Barrella
- Dpto. de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Spain
| | - Eva Alés
- Dpto. de Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Spain.
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7
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Tan X, Xiao GY, Wang S, Shi L, Zhao Y, Liu X, Yu J, Russell WK, Creighton CJ, Kurie JM. EMT-activated secretory and endocytic vesicular trafficking programs underlie a vulnerability to PI4K2A antagonism in lung cancer. J Clin Invest 2023; 133:e165863. [PMID: 36757799 PMCID: PMC10065074 DOI: 10.1172/jci165863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 02/07/2023] [Indexed: 02/10/2023] Open
Abstract
Hypersecretory malignant cells underlie therapeutic resistance, metastasis, and poor clinical outcomes. However, the molecular basis for malignant hypersecretion remains obscure. Here, we showed that epithelial-mesenchymal transition (EMT) initiates exocytic and endocytic vesicular trafficking programs in lung cancer. The EMT-activating transcription factor zinc finger E-box-binding homeobox 1 (ZEB1) executed a PI4KIIIβ-to-PI4KIIα (PI4K2A) dependency switch that drove PI4P synthesis in the Golgi and endosomes. EMT enhanced the vulnerability of lung cancer cells to PI4K2A small-molecule antagonists. PI4K2A formed a MYOIIA-containing protein complex that facilitated secretory vesicle biogenesis in the Golgi, thereby establishing a hypersecretory state involving osteopontin (SPP1) and other prometastatic ligands. In the endosomal compartment, PI4K2A accelerated recycling of SPP1 receptors to complete an SPP1-dependent autocrine loop and interacted with HSP90 to prevent lysosomal degradation of AXL receptor tyrosine kinase, a driver of cell migration. These results show that EMT coordinates exocytic and endocytic vesicular trafficking to establish a therapeutically actionable hypersecretory state that drives lung cancer progression.
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Affiliation(s)
- Xiaochao Tan
- Department of Thoracic/Head and Neck Medical Oncology, The University of Texas–MD Anderson Cancer Center, Houston, Texas, USA
| | - Guan-Yu Xiao
- Department of Thoracic/Head and Neck Medical Oncology, The University of Texas–MD Anderson Cancer Center, Houston, Texas, USA
| | - Shike Wang
- Department of Thoracic/Head and Neck Medical Oncology, The University of Texas–MD Anderson Cancer Center, Houston, Texas, USA
| | - Lei Shi
- Department of Thoracic/Head and Neck Medical Oncology, The University of Texas–MD Anderson Cancer Center, Houston, Texas, USA
| | - Yanbin Zhao
- Department of Thoracic/Head and Neck Medical Oncology, The University of Texas–MD Anderson Cancer Center, Houston, Texas, USA
- Department of Internal Medical Oncology, Harbin Medical University Cancer Hospital, Harbin, Heilongjiang Province, China
| | - Xin Liu
- Department of Thoracic/Head and Neck Medical Oncology, The University of Texas–MD Anderson Cancer Center, Houston, Texas, USA
| | - Jiang Yu
- Department of Thoracic/Head and Neck Medical Oncology, The University of Texas–MD Anderson Cancer Center, Houston, Texas, USA
| | - William K. Russell
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, Texas, USA
| | - Chad J. Creighton
- Department of Medicine and Dan L Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Bioinformatics and Computational Biology, The University of Texas–MD Anderson Cancer Center, Houston, Texas, USA
| | - Jonathan M. Kurie
- Department of Thoracic/Head and Neck Medical Oncology, The University of Texas–MD Anderson Cancer Center, Houston, Texas, USA
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8
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Majdi S, Lima AS, Ewing AG. Vesicle Collision Protocols for the Study of Quantum Size and Exocytotic Fraction Released. Methods Mol Biol 2023; 2565:223-237. [PMID: 36205898 DOI: 10.1007/978-1-0716-2671-9_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We review the methods of vesicle impact electrochemical cytometry, intracellular impact electrochemical cytometry, and single cell amperometry and their application to measuring the storage of neurotransmitters in cellular vesicles. We provide protocols to measure vesicle content, the release of catecholamines, and from there the fraction of transmitter released in each exocytosis event. The focus here has been a combination of methods to evaluate factors related to neuronal function at the cellular level and implications in, for example, cognition.
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Affiliation(s)
- Soodabeh Majdi
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Alex S Lima
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Andrew G Ewing
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden.
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9
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Chen PC, Wang CT. Rat Pheochromocytoma PC12 Cells in Culture. Methods Mol Biol 2023; 2565:3-15. [PMID: 36205883 DOI: 10.1007/978-1-0716-2671-9_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
PC12 cells serve as a secretory cell model, especially suitable for studying the molecular mechanisms underlying fusion pore kinetics in regulated exocytosis of dense-core vesicles (DCVs). In this chapter, we describe a series of PC12 cell culture procedures optimized for real-time functional assays such as single-vesicle amperometry. In addition, these conditions have been widely used for single-cell biochemical assays such as the proximity ligation assay with immunostaining.
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Affiliation(s)
- Pin-Chun Chen
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan
| | - Chih-Tien Wang
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan.
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10
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Guyer P, Arribas-Layton D, Manganaro A, Speake C, Lord S, Eizirik DL, Kent SC, Mallone R, James EA. Recognition of mRNA Splice Variant and Secretory Granule Epitopes by CD4+ T Cells in Type 1 Diabetes. Diabetes 2023; 72:85-96. [PMID: 36201618 PMCID: PMC9797322 DOI: 10.2337/db22-0191] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 10/02/2022] [Indexed: 01/19/2023]
Abstract
A recent discovery effort resulted in identification of novel splice variant and secretory granule antigens within the HLA class I peptidome of human islets and documentation of their recognition by CD8+ T cells from peripheral blood and human islets. In the current study, we applied a systematic discovery process to identify novel CD4+ T cell epitopes derived from these candidate antigens. We predicted 145 potential epitopes spanning unique splice junctions and within conventional secretory granule antigens and measured their in vitro binding to DRB1*04:01. We generated HLA class II tetramers for the 35 peptides with detectable binding and used these to assess immunogenicity and isolate T cell clones. Tetramers corresponding to peptides with verified immunogenicity were then used to label T cells specific for these putative epitopes in peripheral blood. T cells that recognize distinct epitopes derived from a cyclin I splice variant, neuroendocrine convertase 2, and urocortin-3 were detected at frequencies that were similar to those of an immunodominant proinsulin epitope. Cells specific for these novel epitopes predominantly exhibited a Th1-like surface phenotype. Among the three epitopes, responses to the cyclin I peptide exhibited a distinct memory profile. Responses to neuroendocrine convertase 2 were detected among pancreatic infiltrating T cells. These results further establish the contribution of unconventional antigens to the loss of tolerance in autoimmune diabetes.
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Affiliation(s)
- Perrin Guyer
- Center for Translational Immunology, Benaroya Research Institute, Virginia Mason Medical Center, Seattle, WA
| | - David Arribas-Layton
- Center for Translational Immunology, Benaroya Research Institute, Virginia Mason Medical Center, Seattle, WA
| | - Anthony Manganaro
- Division of Diabetes, Diabetes Center of Excellence, Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA
| | - Cate Speake
- Diabetes Clinical Research Program and Center for Interventional Immunology, Benaroya Research Institute, Virginia Mason Medical Center, Seattle, WA
| | - Sandra Lord
- Diabetes Clinical Research Program and Center for Interventional Immunology, Benaroya Research Institute, Virginia Mason Medical Center, Seattle, WA
| | - Decio L. Eizirik
- ULB Center for Diabetes Research, Université Libre de Bruxelles, Brussels, Belgium
| | - Sally C. Kent
- Division of Diabetes, Diabetes Center of Excellence, Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA
| | - Roberto Mallone
- INSERM, CNRS, Institut Cochin, Université de Paris, Paris, France
- Service de Diabétologie et Immunologie Clinique, Cochin Hospital, Hôpitaux Universitaires Paris Centre, Assistance Publique–Hôpitaux de Paris, Paris, France
| | - Eddie A. James
- Center for Translational Immunology, Benaroya Research Institute, Virginia Mason Medical Center, Seattle, WA
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11
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Kesimer M. Mucins MUC5AC and MUC5B in the Airways: MUCing around Together. Am J Respir Crit Care Med 2022; 206:1055-1057. [PMID: 35938865 PMCID: PMC9704829 DOI: 10.1164/rccm.202208-1459ed] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- Mehmet Kesimer
- Marsico Lung Institute and Department of Pathology and Laboratory Medicine The University of North Carolina at Chapel Hill Chapel Hill, North Carolina
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12
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Shi C, Wang D, Guan Y, Qu H. Dissection and ultramicroscopic observation of an apical pollen tube of Pyrus. Plant Reprod 2022; 35:1-8. [PMID: 34731307 DOI: 10.1007/s00497-021-00433-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 10/25/2021] [Indexed: 06/13/2023]
Abstract
The pollen tube is ideal for studying cell polar growth, and observing the ultrastructure of the pollen tube tip using transmission electron microscopy (TEM) is the primary method for studying pollen tube growth. The preparation of ultrathin sections of the pollen tube tip sample is important for its successful microscopic observation. The direction of pollen tube growth in vitro is irregular, and it is difficult to dissect the tip of the pollen tube during ultrathin sectioning. Here, we used two methods to efficiently obtain an ultrathin section of the pollen tube tip of Pyrus. In the first method, laser micro-cutting was used to obtain the pollen tube tip, followed by ultrathin sectioning. In the other method, the pollen tubes were cultured in the same growth direction, followed by ultrathin sectioning. Ultrathin sections, which were observed via TEM, showed typical characteristics of the pollen tube tip, such as dense vesicles, numerous mitochondria, and secretory vesicles of the Golgi. We concluded that these two methods are effective in pollen tube tip sample preparation for ultrathin sectioning and provide the foundation for observing the ultrastructure of pollen tube tips.
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Affiliation(s)
- Chenxi Shi
- College of Horticulture, Qingdao Agricultural University, No. 700 Changcheng Road, Qingdao City, 266109, Shandong Province, China
| | - Demian Wang
- College of Horticulture, Qingdao Agricultural University, No. 700 Changcheng Road, Qingdao City, 266109, Shandong Province, China
| | - Yaqin Guan
- College of Horticulture, Qingdao Agricultural University, No. 700 Changcheng Road, Qingdao City, 266109, Shandong Province, China
| | - Haiyong Qu
- College of Horticulture, Qingdao Agricultural University, No. 700 Changcheng Road, Qingdao City, 266109, Shandong Province, China.
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13
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Cai Y. Leading the way out: how a plant myosin facilitates vesicle tethering during exocytosis. Plant Cell 2021; 33:2104-2105. [PMID: 35233601 PMCID: PMC8364227 DOI: 10.1093/plcell/koab111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 04/14/2021] [Indexed: 06/14/2023]
Affiliation(s)
- Yingqi Cai
- Biology Department, Brookhaven National Laboratory, Upton, NY, USA
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14
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Podraza-Farhanieh A, Natarajan B, Raj D, Kao G, Naredi P. ENPL-1, the Caenorhabditis elegans homolog of GRP94, promotes insulin secretion via regulation of proinsulin processing and maturation. Development 2020; 147:dev190082. [PMID: 33037039 PMCID: PMC10666919 DOI: 10.1242/dev.190082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 09/28/2020] [Indexed: 12/27/2022]
Abstract
Insulin/IGF signaling in Caenorhabditis elegans is crucial for proper development of the dauer larva and growth control. Mutants disturbing insulin processing, secretion and downstream signaling perturb this process and have helped identify genes that affect progression of type 2 diabetes. Insulin maturation is required for its proper secretion by pancreatic β cells. The role of the endoplasmic reticulum (ER) chaperones in insulin processing and secretion needs further study. We show that the C. elegans ER chaperone ENPL-1/GRP94 (HSP90B1), acts in dauer development by promoting insulin secretion and signaling. Processing of a proinsulin likely involves binding between the two proteins via a specific domain. We show that, in enpl-1 mutants, an unprocessed insulin exits the ER lumen and is found in dense core vesicles, but is not secreted. The high ER stress in enpl-1 mutants does not cause the secretion defect. Importantly, increased ENPL-1 levels result in increased secretion. Taken together, our work indicates that ENPL-1 operates at the level of insulin availability and is an essential modulator of insulin processing and secretion.
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Affiliation(s)
- Agnieszka Podraza-Farhanieh
- Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, SE413 45 Gothenburg, Sweden
| | | | - Dorota Raj
- Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, SE413 45 Gothenburg, Sweden
| | - Gautam Kao
- Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, SE413 45 Gothenburg, Sweden
| | - Peter Naredi
- Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, SE413 45 Gothenburg, Sweden
- Department of Surgery, Sahlgrenska University Hospital, SE413 45 Gothenburg, Sweden
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15
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Labadie T, Roy P. A non-enveloped arbovirus released in lysosome-derived extracellular vesicles induces super-infection exclusion. PLoS Pathog 2020; 16:e1009015. [PMID: 33075107 PMCID: PMC7595637 DOI: 10.1371/journal.ppat.1009015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 10/29/2020] [Accepted: 09/25/2020] [Indexed: 12/11/2022] Open
Abstract
Recent developments on extracellular vesicles (EVs) containing multiple virus particles challenge the rigid definition of non-enveloped viruses. However, how non-enveloped viruses hijack cell machinery to promote non-lytic release in EVs, and their functional roles, remain to be clarified. Here we used Bluetongue virus (BTV) as a model of a non-enveloped arthropod-borne virus and discovered that the majority of viruses are released in EVs. Based on the cellular proteins detected in these EVs, and use of inhibitors targeting the cellular degradation process, we demonstrated that these extracellular vesicles are derived from secretory lysosomes, in which the acidic pH is neutralized upon the infection. Moreover, we report that secreted EVs are more efficient than free-viruses for initiating infections, but that they trigger super-infection exclusion that only free-viruses can overcome. Recent discoveries of non-enveloped virus secreted in EVs opened the door to new developments in our understanding of the transmission and pathogenicity of these viruses. In particular, how these viruses hijack the host cellular secretion machinery, and the role of these EVs compared with free-virus particles remained to be explored. Here, we tackled these two aspects, by studying BTV, an emerging arthropod-borne virus causing epidemics worldwide. We showed that this virus is mainly released in EVs, and that inhibition of the cell degradation machinery decreases the release of infectious EVs, but not free-virus particles. We found that BTV must neutralize the pH of lysosomes, which are important organelles of the cell degradation machinery, for efficient virus release in EVs. Our results highlight unique features for a virus released in EVs, explaining how BTV transits in lysosomes without being degraded. Interestingly, we observed that EVs are more infectious than free-virus particles, but only free-viruses are able to overcome the super-infection exclusion, which is a common cellular defense mechanism. In conclusion, our study stresses the dual role played by both forms, free and vesicular, in the virus life cycle.
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Affiliation(s)
- Thomas Labadie
- Department of Pathogen Molecular Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, United Kingdom
| | - Polly Roy
- Department of Pathogen Molecular Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, United Kingdom
- * E-mail:
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Smith KA, Prantzalos ER, Anantharam A. Integrating Optical and Electrochemical Approaches to Assess the Actions of Dynamin at the Fusion Pore. Methods Mol Biol 2020; 2159:163-178. [PMID: 32529370 DOI: 10.1007/978-1-0716-0676-6_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Of the techniques currently available to monitor dense core granule exocytosis in adrenal chromaffin cells, two have proven particularly useful: carbon-fiber amperometry and total internal reflection fluorescence (TIRF) microscopy. Amperometry enables the detection of oxidizable catecholamines escaping a fusion pore with millisecond time resolution. TIRF microscopy, and its variant polarized-TIRF (pTIRF) microscopy, provides information on the characteristics of fusion pores at temporally later stages. Used in conjunction, amperometry and TIRF microscopy allow an investigator to follow the fate of a fusion pore from its formation to expansion or reclosure. The properties of fusion pores, including their structure and dynamics, have been shown by multiple groups to be modified by the dynamin GTPase (Dyn1). In this chapter, we describe how amperometry and TIRF microscopy enable insights into dynamin-dependent effects on exocytosis in primary cultures of bovine adrenal chromaffin cells.
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Affiliation(s)
- Katherine A Smith
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | | | - Arun Anantharam
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA.
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17
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McCormack JJ, Harrison‐Lavoie KJ, Cutler DF. Human endothelial cells size-select their secretory granules for exocytosis to modulate their functional output. J Thromb Haemost 2020; 18:243-254. [PMID: 31519030 PMCID: PMC7155122 DOI: 10.1111/jth.14634] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 09/02/2019] [Accepted: 09/05/2019] [Indexed: 12/18/2022]
Abstract
BACKGROUND The secretory granules of endothelial cells, Weibel-Palade bodies, are released in response to numerous extracellular signals. Their cargo is critical to many vascular functions including hemostasis and inflammation. This presents a fundamental problem: how can these cells initiate tailor-made responses from the release of a single type of organelle, each with similar cargo? Each cell contains Weibel-Palade bodies in a wide range of sizes, and we have shown that experimentally shortening these organelles disproportionately reduces their ability to initiate hemostasis in vitro, leaving leukocyte recruitment unaffected. Could the production of this range of sizes underpin differential responses? OBJECTIVES To determine whether different agonists drive the exocytosis of different sizes of Weibel-Palade bodies. METHODS We used a high-throughput automated unbiased imaging workflow to analyze the sizes of Weibel-Palade bodies within human umbilical vein endothelial cells (HUVECs) before and after agonist activation to determine changes in organelle size distributions. RESULTS We found that a subset of agonists differentially evoke the release of the longest, most pro-hemostatic organelles. Inhibiting the release of these longest organelles by just 15% gives a fall of 60% in an assay of secreted von Willebrand factor (vWF) function. CONCLUSIONS The size-selection of granules for exocytosis represents a novel layer of control, allowing endothelial cells to provide diverse responses to different signals via the release of a single type of organelle.
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Affiliation(s)
| | | | - Daniel F. Cutler
- MRC Laboratory of Molecular Cell BiologyUniversity College LondonLondonUK
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18
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Saeed B, Brillada C, Trujillo M. Dissecting the plant exocyst. Curr Opin Plant Biol 2019; 52:69-76. [PMID: 31509792 DOI: 10.1016/j.pbi.2019.08.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 07/12/2019] [Accepted: 08/08/2019] [Indexed: 06/10/2023]
Abstract
The exocyst is an evolutionary conserved complex that mediates tethering of post-Golgi vesicles derived from the conventional secretory pathway to the plasma membrane (PM), before SNARE-mediated fusion. Through its tethering function, connecting secretory vesicles to the PM, it mediates spatiotemporal regulation of exocytosis. As an integral element of the secretory machinery, the exocyst has been implicated in a large variety of processes. However, emerging evidence suggests that it may also cater for unconventional secretory pathways, as well as autophagy. The exocyst entertains a multitude of interactions with proteins and membrane phospholipids, reflecting its highly dynamic nature and the complex regulatory processes that hardwire it with cellular signalling networks. However, our molecular understanding of this essential complex remains fragmentary. Here we review recent work focusing on the molecular features that have revealed both commonalities with yeast and animals, as well as unique characteristics of the plant exocyst.
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Affiliation(s)
- Bushra Saeed
- Albert-Ludwigs-University Freiburg, Faculty of Biology, Institute of Biology II, 79104 Freiburg, Germany
| | - Carla Brillada
- Albert-Ludwigs-University Freiburg, Faculty of Biology, Institute of Biology II, 79104 Freiburg, Germany
| | - Marco Trujillo
- Albert-Ludwigs-University Freiburg, Faculty of Biology, Institute of Biology II, 79104 Freiburg, Germany.
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19
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Richman EB, Luo L. Suppressing Memories by Shrinking the Vesicle Pool. Neuron 2019; 101:5-7. [PMID: 30605657 DOI: 10.1016/j.neuron.2018.12.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The cohesin complex regulates cellular functions spanning cell division and neuronal morphogenesis. Now, Phan et al. uncover a role for the cohesin complex in regulating memory acquisition and the size of the synaptic and dense-core vesicle pool.
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Affiliation(s)
- Ethan B Richman
- Neurosciences Graduate Program, Stanford University, Stanford, CA 94305, USA; Department of Biology, Stanford University, Stanford, CA 94305, USA; Department of Bioengineering, Stanford University, Stanford, CA 94305, USA.
| | - Liqun Luo
- Department of Biology, Stanford University, Stanford, CA 94305, USA; Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
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Affiliation(s)
| | - Miroslav Strnad
- Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany AS CR and Palacký University, Olomouc, Czech Republic
| | - Stefano Mancuso
- Department of Plant, Soil, and Environmental Science and LINV, University of Florence, Sesto Fiorentino, Italy
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Abstract
Strict spatiotemporal control of trafficking events between organelles is critical for maintaining homeostasis and directing cellular responses. This regulation is particularly important in immune cells for mounting specialized immune defenses. By controlling the formation, transport and fusion of intracellular organelles, Rab GTPases serve as master regulators of membrane trafficking. In this review, we discuss the cellular and molecular mechanisms by which Rab GTPases regulate immunity and inflammation.
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Affiliation(s)
| | | | | | - Maximiliano G. Gutierrez
- Host-Pathogen Interactions in Tuberculosis Laboratory, Francis Crick Institute, London, United Kingdom
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22
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Dhanvantari S. Secretory Granules Tell (Almost) All in Enteroendocrine Cells. Endocrinology 2017; 158:2068-2070. [PMID: 28881871 DOI: 10.1210/en.2017-00459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 05/15/2017] [Indexed: 11/19/2022]
Affiliation(s)
- Savita Dhanvantari
- Lawson Health Research Institute and Western University, London, Ontario N6A 4V2, Canada
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23
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Wollam J, Mahata S, Riopel M, Hernandez-Carretero A, Biswas A, Bandyopadhyay GK, Chi NW, Eiden LE, Mahapatra NR, Corti A, Webster NJG, Mahata SK. Chromogranin A regulates vesicle storage and mitochondrial dynamics to influence insulin secretion. Cell Tissue Res 2017; 368:487-501. [PMID: 28220294 PMCID: PMC10843982 DOI: 10.1007/s00441-017-2580-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 01/16/2017] [Indexed: 01/01/2023]
Abstract
Chromogranin A (CgA) is a prohormone and a granulogenic factor that regulates secretory pathways in neuroendocrine tissues. In β-cells of the endocrine pancreas, CgA is a major cargo in insulin secretory vesicles. The impact of CgA deficiency on the formation and exocytosis of insulin vesicles is yet to be investigated. In addition, no literature exists on the impact of CgA on mitochondrial function in β-cells. Using three different antibodies, we demonstrate that CgA is processed to vasostatin- and catestatin-containing fragments in pancreatic islet cells. CgA deficiency in Chga-KO islets leads to compensatory overexpression of chromogranin B, secretogranin II, SNARE proteins and insulin genes, as well as increased insulin protein content. Ultrastructural studies of pancreatic islets revealed that Chga-KO β-cells contain fewer immature secretory granules than wild-type (WT) control but increased numbers of mature secretory granules and plasma membrane-docked vesicles. Compared to WT control, CgA-deficient β-cells exhibited increases in mitochondrial volume, numerical densities and fusion, as well as increased expression of nuclear encoded genes (Ndufa9, Ndufs8, Cyc1 and Atp5o). These changes in secretory vesicles and the mitochondria likely contribute to the increased glucose-stimulated insulin secretion observed in Chga-KO mice. We conclude that CgA is an important regulator for coordination of mitochondrial dynamics, secretory vesicular quanta and GSIS for optimal secretory functioning of β-cells, suggesting a strong, CgA-dependent positive link between mitochondrial fusion and GSIS.
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Affiliation(s)
- Joshua Wollam
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Sumana Mahata
- Division of Biology & Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Matthew Riopel
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | | | - Angshuman Biswas
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | | | - Nai-Wen Chi
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA
- VA San Diego Healthcare System, San Diego, CA, USA
| | - Lee E Eiden
- Section on Molecular Neuroscience, NIMH-IRP, Bethesda, MD, USA
| | - Nitish R Mahapatra
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai, 600036, India
| | - Angelo Corti
- IRCCS San Raffaele Scientific Institute, San Raffaele Vita-Salute University, Milan, Italy
| | - Nicholas J G Webster
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA
- VA San Diego Healthcare System, San Diego, CA, USA
| | - Sushil K Mahata
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA.
- VA San Diego Healthcare System, San Diego, CA, USA.
- Metabolic Physiology & Ultrastructural Biology Laboratory, Department of Medicine, University of California, San Diego (0732), 9500 Gilman Drive, La Jolla, CA, 92093-0732, USA.
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24
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Miyado K, Kang W, Yamatoya K, Hanai M, Nakamura A, Mori T, Miyado M, Kawano N. Exosomes versus microexosomes: Shared components but distinct functions. J Plant Res 2017; 130:479-483. [PMID: 28160150 DOI: 10.1007/s10265-017-0907-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 11/29/2016] [Indexed: 06/06/2023]
Abstract
In multicellular organisms, cellular components are constantly translocated within cells and are also transported exclusively between limited cells, regardless of their physical distance. Exosomes function as one of the key mediators of intercellular transportation. External vesicles were identified 50 years ago in plants and now reconsidered to be exosome-like vesicles. Meanwhile, a well-known exosomal component, tetraspanin CD9, regulates sperm-egg fusion in mammals. A number of Arabidopsis tetraspanins are also expressed in reproductive tissues at fertilization, and are localized at the plasma membrane of protoplasts. Moreover, CD9-containing structures (or 'microexosomes') are released from mouse eggs during their maturation and promote the sperm-egg fusion. This phenomenon implies that two types of shared-component intercellular carriers might be released from multiple types of plant and animal cells, which widely regulate biological phenomena. We herein highlight their discrete structures, formation processes, and functions.
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Affiliation(s)
- Kenji Miyado
- Department of Reproductive Biology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan.
| | - Woojin Kang
- Department of Reproductive Biology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan
- Department of Perinatal Medicine and Maternal Care, National Center for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan
| | - Kenji Yamatoya
- Department of Applied Biological Science, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba, 278-8510, Japan
| | - Maito Hanai
- Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki, Kanagawa, 214-8571, Japan
| | - Akihiro Nakamura
- Department of Reproductive Biology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan
- Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki, Kanagawa, 214-8571, Japan
| | - Toshiyuki Mori
- Department of Tropical Medicine and Parasitology, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Mami Miyado
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan
| | - Natsuko Kawano
- Department of Reproductive Biology, National Research Institute for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo, 157-8535, Japan.
- Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki, Kanagawa, 214-8571, Japan.
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Abstract
The release of chemical mediators is an essential element of cell-to-cell communication. Signaling molecules such as neurotransmitters and hormones are stored in membrane-bound organelles called secretory vesicles. Some of these organelles can store molecules at high concentrations, overcoming the osmotic shock that could burst the organelle. These organelles contain a proteinaceous matrix that traps the molecules and avoids high intravesicular osmotic pressure. The functional nanostructure and internal organization of the matrix is not well understood. A report by Lovrić et al. in this issue of ACS Nano provides insight into the storage of a small molecule-dopamine-within the intraluminal compartments of a secretory vesicle. Lovrić et al. used a powerful combination of high spatial resolution mass spectrometry and transmission electron microscopy in conjunction with amperometric measurements of exocytotic release to delineate the temporal and spatial fate of intravesicular dopamine and its interaction with the matrix.
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Affiliation(s)
- José Luis Nieto-González
- Instituto de Biomedicina de Sevilla (IBiS, HUVR/CSIC/Universidad de Sevilla) , Departamento de Fisiología Médica y Biofísica and CIBERNED, ES-41013 Seville, Spain
| | - Rafael Fernández-Chacón
- Instituto de Biomedicina de Sevilla (IBiS, HUVR/CSIC/Universidad de Sevilla) , Departamento de Fisiología Médica y Biofísica and CIBERNED, ES-41013 Seville, Spain
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Gendre D, Jonsson K, Boutté Y, Bhalerao RP. Journey to the cell surface--the central role of the trans-Golgi network in plants. Protoplasma 2015; 252:385-98. [PMID: 25187082 DOI: 10.1007/s00709-014-0693-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 08/21/2014] [Indexed: 05/11/2023]
Abstract
The secretion of proteins, lipids, and carbohydrates to the cell surface is essential for plant development and adaptation. Secreted substances synthesized at the endoplasmic reticulum pass through the Golgi apparatus and trans-Golgi network (TGN) en route to the plasma membrane via the conventional secretion pathway. The TGN is morphologically and functionally distinct from the Golgi apparatus. The TGN is located at the crossroads of many trafficking pathways and regulates a range of crucial processes including secretion to the cell surface, transport to the vacuole, and the reception of endocytic cargo. This review outlines the TGN's central role in cargo secretion, showing that its behavior is more complex and controlled than the bulk-flow hypothesis suggests. Its formation, structure, and maintenance are discussed along with the formation and release of secretory vesicles.
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Affiliation(s)
- Delphine Gendre
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden,
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Koseoglu S, Love SA, Haynes CL. Cholesterol effects on vesicle pools in chromaffin cells revealed by carbon-fiber microelectrode amperometry. Anal Bioanal Chem 2011; 400:2963-71. [PMID: 21523329 DOI: 10.1007/s00216-011-5002-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Revised: 03/31/2011] [Accepted: 04/08/2011] [Indexed: 11/25/2022]
Abstract
Cell-cell communication is often achieved via granular exocytosis, as in neurons during synaptic transmission or neuroendocrine cells during blood hormone control. Owing to its critical role in membrane properties and SNARE function, cholesterol is expected to play an important role in the highly conserved process of exocytosis. In this work, membrane cholesterol concentration is systematically varied in primary culture mouse chromaffin cells, and the change in secretion behavior of distinct vesicle pools as well as pool recovery following stimulation is measured using carbon-fiber microelectrode amperometry. Amperometric traces obtained from activation of the younger readily releasable and slowly releasable pool (RRP/SRP) vesicles at depleted cholesterol levels showed fewer sustained fusion pore features (6.1 ± 1.1% of spikes compared with 11.2 ± 1.0% for control), revealing that cholesterol content influences fusion pore formation and stability during exocytosis. Moreover, subsequent stimulation of RRP/SRP vesicles showed that cellular cholesterol level influences both the quantal recovery and kinetics of the later release events. Finally, diverging effects of cholesterol on RRP and the older reserve pool vesicle release suggest two different mechanisms for the release of these two vesicular pools.
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Affiliation(s)
- Secil Koseoglu
- Department of Chemistry, University of Minnesota, Minneapolis, 55455-0240, USA
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28
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Harper MT, Mason MJ, Sage SO, Harper AGS. Phorbol ester-evoked Ca2+ signaling in human platelets is via autocrine activation of P(2X1) receptors, not a novel non-capacitative Ca2+ entry. J Thromb Haemost 2010; 8:1604-13. [PMID: 20345709 DOI: 10.1111/j.1538-7836.2010.03867.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
SUMMARY BACKGROUND Platelets are reported to possess a protein kinase C (PKC)-dependent non-capacitative Ca(2+)entry (NCCE) pathway. The phorbol ester, phorbol, 12-myristate, 13-acetate (PMA) has been suggested to stimulate platelet NCCE. Recently we demonstrated important roles in store-operated Ca(2+)entry in human platelets for Na(+)/Ca(2+) exchangers (NCXs) and autocrine signaling between platelets after dense granule secretion. As PMA evokes dense granule secretion, we have investigated the role of NCXs and autocrine signaling in PMA-evoked Ca(2+)entry. OBJECTIVES To investigate the roles of NCXs and dense granule secretion in PMA-evoked Ca(2+)signaling in human platelets. METHODS Fura-2- or sodium-binding benzofuran isophthalate (SBFI)-loaded platelets were used to monitor cytosolic Ca(2+)or Na(+) concentrations. Dense granule secretion was monitored as ATP release using luciferin-luciferase. RESULTS The NCX inhibitors KB-R7943 or SN-6, and removal of extracellular Na(+), significantly reduced PMA-evoked Ca(2+)entry. PMA-evoked dense granule secretion was almost abolished by pretreatment with the PKC inhibitor Ro-31-8220 and significantly slowed by KB-R7943. The P(2X1) antagonists Ro-0437626 or MRS-2159, or desensitization of P(2X1) receptors by prior treatment with alpha,beta-Methylene-ATP or omitting apyrase from the medium, reduced PMA-evoked Ca(2+)entry. Ro-0437626 or chelation of extracellular Ca(2+) slowed but did not abolish PMA-evoked ATP release, indicating that PMA-evoked dense granule secretion does not require P(2X1) receptor activation but is accelerated by P(2X1)-mediated Ca(2+)entry. The presence of NCX3 in human platelets was demonstrated by Western blotting. CONCLUSION PMA-evoked Ca(2+)entry results from an NCX3-dependent dense granule secretion and subsequent P(2X1) receptor activation by secreted ATP, rather than activation of a novel NCCE pathway.
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Affiliation(s)
- M T Harper
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
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Nunomura S, Yoshimaru T, Ra C. Na-Tosyl-Phe chloromethyl ketone prevents granule movement and mast cell synergistic degranulation elicited by costimulation of antigen and adenosine. Life Sci 2008; 83:242-9. [PMID: 18634805 DOI: 10.1016/j.lfs.2008.06.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Revised: 05/08/2008] [Accepted: 06/07/2008] [Indexed: 12/11/2022]
Abstract
Adenosine has been shown to enhance mast cell degranulation when added together with an antigen. Such augmentation of mast cell activation is relevant to exacerbation of allergic asthma symptoms. Na-Tosyl-Phe chloromethyl ketone (TPCK) is a chymotrypsine-like chymase inhibitor, which has anti-inflammatory properties. In this study, we investigated the effects of TPCK on mast cell synergistic degranulation induced by antigen and adenosine. Here, we report that TPCK almost completely suppressed enhanced degranulation by inhibiting granule movement. Consistent with this, intraperitoneal administration of TPCK resulted in significant amelioration of passive cutaneous anaphylaxis in mice. Furthermore, we demonstrated that TPCK completely inhibited Thr308 phosphorylation of protein kinase B in mast cells stimulated with antigen and adenosine. These results provide a novel action of TPCK for the prevention of mast cell degranulation induced by antigen and adenosine.
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Affiliation(s)
- Satoshi Nunomura
- Division of Molecular Cell Immunology and Allergology, Nihon University Graduate School of Medical Science, Japan
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30
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Lopez I, Giner D, Ruiz-Nuño A, Fuentealba J, Viniegra S, Garcia AG, Davletov B, Gutiérrez LM. Tight coupling of the t-SNARE and calcium channel microdomains in adrenomedullary slices and not in cultured chromaffin cells. Cell Calcium 2007; 41:547-58. [PMID: 17112584 DOI: 10.1016/j.ceca.2006.10.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2006] [Revised: 09/26/2006] [Accepted: 10/12/2006] [Indexed: 10/23/2022]
Abstract
Regulated exocytosis involves calcium-dependent fusion of secretory vesicles with the plasma membrane with three SNARE proteins playing a central role: the vesicular synaptobrevin and the plasma membrane syntaxin1 and SNAP-25. Cultured bovine chromaffin cells possess defined plasma membrane microdomains that are specifically enriched in both syntaxin1 and SNAP-25. We now show that in both isolated cells and adrenal medulla slices these target SNARE (t-SNARE) patches quantitatively coincide with single vesicle secretory spots as detected by exposure of the intravesicular dopamine beta-hydroxylase onto the plasmalemma. During exocytosis, neither area nor density of the syntaxin1/SNAP-25 microdomains changes on the plasma membrane of both preparations confirming that preexisting clusters act as the sites for vesicle fusion. Our analysis reveals a high level of colocalization of L, N and P/Q type calcium channel clusters with SNAREs in adrenal slices; this close association is altered in individual cultured cells. Therefore, microdomains carrying syntaxin1/SNAP-25 and different types of calcium channels act as the sites for physiological granule fusion in "in situ" chromaffin cells. In the case of isolated cells, it is the t-SNAREs microdomains rather than calcium channels that define the sites of exocytosis.
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Affiliation(s)
- Inmaculada Lopez
- Instituto de Neurociencias, Centro Mixto CSIC-Universidad Miguel Hernández, Sant Joan d'Alacant, 03550 Alicante, and Instituto Teófilo Hernando, Servicio de Farmacología Clínica, Hospital de la Princesa, Madrid, Spain
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Gilicze A, Kohalmi B, Pocza P, Keszei M, Jaeger J, Gorbe E, Papp Z, Toth S, Falus A, Wiener Z. HtrA1 is a novel mast cell serine protease of mice and men. Mol Immunol 2007; 44:2961-8. [PMID: 17292962 DOI: 10.1016/j.molimm.2007.01.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2006] [Accepted: 01/03/2007] [Indexed: 11/28/2022]
Abstract
Mast cells are rich sources of proteases, such as tryptases and chymases that control many physiological and pathological processes, for example vascular permeability, smooth muscle cell proliferation or extracellular matrix remodeling. Murine mucosal mast cells mature under the influence of TGF-beta and play a role in asthmatic and anti-helminthic immune responses. In an attempt to identify novel genes that are highly upregulated during mucosal mast cell differentiation, we detected HtrA1 protease as a novel protein in mast cells by microarray experiments. HtrA1 level was much higher in murine mucosal than in connective tissue-type mast cells. Furthermore, HtrA1 is not localized in the secretory granules and is constitutively secreted by human mast cells. Although HtrA1 has been attributed a TGF-beta-inhibitory activity, it did not show any influence on TGF-beta-induced mucosal mast cell differentiation. As many extracellular target proteins have been suggested for HtrA1, this protease may participate in the mast cell-induced extracellular remodeling.
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Affiliation(s)
- Anna Gilicze
- Department of Genetics, Cell and Immunobiology, Semmelweis University, 1089 Budapest, Nagyvárad tér 4, Hungary
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32
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Shaw RM, Fay AJ, Puthenveedu MA, von Zastrow M, Jan YN, Jan LY. Microtubule plus-end-tracking proteins target gap junctions directly from the cell interior to adherens junctions. Cell 2007; 128:547-60. [PMID: 17289573 PMCID: PMC1955433 DOI: 10.1016/j.cell.2006.12.037] [Citation(s) in RCA: 363] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Revised: 06/20/2006] [Accepted: 12/06/2006] [Indexed: 10/23/2022]
Abstract
Gap junctions are intercellular channels that connect the cytoplasms of adjacent cells. For gap junctions to properly control organ formation and electrical synchronization in the heart and the brain, connexin-based hemichannels must be correctly targeted to cell-cell borders. While it is generally accepted that gap junctions form via lateral diffusion of hemichannels following microtubule-mediated delivery to the plasma membrane, we provide evidence for direct targeting of hemichannels to cell-cell junctions through a pathway that is dependent on microtubules; through the adherens-junction proteins N-cadherin and beta-catenin; through the microtubule plus-end-tracking protein (+TIP) EB1; and through its interacting protein p150(Glued). Based on live cell microscopy that includes fluorescence recovery after photobleaching (FRAP), total internal reflection fluorescence (TIRF), deconvolution, and siRNA knockdown, we propose that preferential tethering of microtubule plus ends at the adherens junction promotes delivery of connexin hemichannels directly to the cell-cell border. These findings support an unanticipated mechanism for protein delivery to points of cell-cell contact.
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Affiliation(s)
- Robin M. Shaw
- Cardiovascular Research Institute and Department of Medicine, University of California, San Francisco, CA 94143
| | - Alex J. Fay
- Graduate Group in Biophysics, University of California, San Francisco, CA 94143
| | - Manojkumar A. Puthenveedu
- Departments of Psychiatry and Cellular & Molecular Pharmacology, University of California, San Francisco, CA 94143
| | - Mark von Zastrow
- Departments of Psychiatry and Cellular & Molecular Pharmacology, University of California, San Francisco, CA 94143
| | - Yuh-Nung Jan
- Howard Hughes Medical Institute and Departments of Physiology and Biochemistry, University of California, San Francisco, CA 94143, USA
| | - Lily Y. Jan
- Howard Hughes Medical Institute and Departments of Physiology and Biochemistry, University of California, San Francisco, CA 94143, USA
- *Correspondence:
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Osanai K, Tsuchihara C, Hatta R, Oikawa T, Tsuchihara K, Iguchi M, Seki T, Takahashi M, Huang J, Toga H. Pulmonary surfactant transport in alveolar type II cells. Respirology 2006; 11 Suppl:S70-3. [PMID: 16423277 DOI: 10.1111/j.1440-1843.2006.00813.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pulmonary surfactant (PS) is a mixture of several lipids (mainly phosphatidylcholine; PC) and four apoproteins (A, B, C and D). The classical hypothesis of PS transport suggests that PS is synthesized in the endoplasmic reticulum and transported to the lamellar body (LB) via the Golgi apparatus. However, recent studies have raised questions regarding this single route. This study examined, independently, the intracellular trafficking route of three different components of PS, that is, PC, SP-A and SP-B. Alveolar type II cells were isolated from Sprague-Dawley rats or Japanese white rabbits. The cells were cultured with either [3H]choline or [35S]methionine/cysteine with or without brefeldin A, which disassembles the Golgi apparatus. LB was purified from disintegrated cells with sucrose density gradient centrifugation. [3H]PC was extracted from radiolabeled media, cells, and the LB fraction with Bligh-Dyer's method. [35S]SP-A or [35S]SP-B was immunoprecipitated from each sample with a specific antibody. [3H]PC was transported and stored to the LB via a Golgi-independent pathway. [35S]SP-A was transported to the Golgi apparatus, underwent glycosylation, and was then constitutively secreted. The secreted [35S]SP-A was re-uptaken into the LB. [35S]SP-B was transported and stored to the LB via the Golgi-dependent pathway. These results indicate that, rather than a single route, surfactant components take different pathways to reside in the LB. These different pathways may reflect the different nature and role of each surfactant component such as surface tension-lowering activity and innate host defense.
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Affiliation(s)
- Kazuhiro Osanai
- Department of Respiratory Medicine, Kanazawa Medical University, Ishikawa, Japan.
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34
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Churchward MA, Rogasevskaia T, Höfgen J, Bau J, Coorssen JR. Cholesterol facilitates the native mechanism of Ca2+-triggered membrane fusion. J Cell Sci 2005; 118:4833-48. [PMID: 16219690 DOI: 10.1242/jcs.02601] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The process of regulated exocytosis is defined by the Ca2+-triggered fusion of two apposed membranes, enabling the release of vesicular contents. This fusion step involves a number of energetically complex steps and requires both protein and lipid membrane components. The role of cholesterol has been investigated using isolated release-ready native cortical secretory vesicles to analyze the Ca2+-triggered fusion step of exocytosis. Cholesterol is a major component of vesicle membranes and we show here that selective removal from membranes, selective sequestering within membranes, or enzymatic modification causes a significant inhibition of the extent, Ca2+ sensitivity and kinetics of fusion. Depending upon the amount incorporated, addition of exogenous cholesterol to cholesterol-depleted membranes consistently recovers the extent, but not the Ca2+ sensitivity or kinetics of fusion. Membrane components of comparable negative curvature selectively recover the ability to fuse, but are unable to recover the kinetics and Ca2+ sensitivity of vesicle fusion. This indicates at least two specific positive roles for cholesterol in the process of membrane fusion: as a local membrane organizer contributing to the efficiency of fusion, and, by virtue of its intrinsic negative curvature, as a specific molecule working in concert with protein factors to facilitate the minimal molecular machinery for fast Ca2+-triggered fusion.
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Affiliation(s)
- Matthew A Churchward
- Department of Physiology and Biophysics, Hotchkiss Brain Institute, University of Calgary, Health Sciences Centre, Faculty of Medicine, Calgary, Alberta, T2N 4N1, Canada
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35
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Fan Z, Zhang Q. Molecular mechanisms of lymphocyte-mediated cytotoxicity. Cell Mol Immunol 2005; 2:259-64. [PMID: 16274623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023] Open
Abstract
Granule-mediated cytotoxicity is the major mechanism for lymphocytes to kill viruses, intracellular bacteria and tumors. The cytotoxic granules move to the immunological synapse by exocytosis after recognition of a killer cell. The contents of the granules are delivered into target cells with the help of perforin by endocytosis. A group of serine protease granzymes cleave their critical substrates to initiate DNA damage and cell death. The most abundant granzymes are granzyme A and B. They induce cell death through alternate and nonoverlapping pathways. The substrates and functions of the majority of the orphan granzymes have not yet been identified. It is possible that the diversity of granzymes provides fail-safe mechanisms for killing viruses and tumor cells.
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Affiliation(s)
- Zusen Fan
- National Laboratory of Biomacromolecules, Center for Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
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36
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Zysiak D. [Secreted proteins of Giardia duodenalis--characteristic and role in biology of the parasite]. Wiad Parazytol 2005; 51:15-9. [PMID: 16841684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The article presents the current knowledge on the proteines under question. The first analysed E-S products released by G. duodenalis was a polydisperse hydrophobic complex (16.5-225 kDa), protease VI sensitive, chloroform-methanol insoluble. Based on inhibition studies cysteine protease and metalloprotease were detected in the complex. The further analysis revealed that a 58 kDa heat stable as wall as protease sensitive glycoprotein secreted by G. duodenalis trophozoites is highly immunogenic for the hosts. Before encystation, G. duodenalis trophozoites secrete leucine-rich cyst wall proteins: CWP1, CWP2 and CWP3. Steady-state levels of CWPs gene transcripts are low in non-encysting trophozoites but increase more than 100-fold during encystation. Another protein, which expression also increases during encystation is gGSP (Giardia Granule-Specific Protein). The protein possesses typical strucutre of calcium-binding proteins. Inhibition of gGSP expression abolishes cyst wall formation, suggesting that this protein regulates Ca(2+)-dependent degranulation of encystation-specific secretory vesicles (ESVs) during cyst wall formation.
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Affiliation(s)
- Dorota Zysiak
- Zakład Parazytologii i Inwazjologii, Katedra Nauk Przedklinicznych, Wydział Medycyny Weterynaryjnej SGGW, ul. Ciszewskiego 8, 02-786 Warszawa
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Hansson M, Gao Y, Rosén H, Tapper H, Olsson I. Hematopoietic secretory granules as vehicles for the local delivery of cytokines and soluble cytokine receptors at sites of inflammation. Eur Cytokine Netw 2004; 15:167-76. [PMID: 15542440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
Cytokines play an important role in the regulation of homeostasis and inflammation. A de-regulated cytokine function can subsequently promote chronic inflammation. This is supported by clinical evidence showing the beneficial effect of inhibiting TNF-alpha through injection of antibodies and soluble receptor in disorders such as rheumatoid arthritis and Crohn's disease. Systemic anti-TNF-alpha therapy however is associated with infectious complications. We therefore suggest a concept for the local deposition of therapeutically active agents into areas of inflammation or malignancy, based on the use of hematopoietic storage and secretory granules as delivery vehicles. Hematopoietic cells are induced to express the therapeutically active protein and to store it in the secretory lysosomes. The cells migrate into a tumour or site of inflammation, where the cells become activated and release the contents of their secretory lysosomes resulting in the local delivery of the therapeutically active protein. In support of this concept, gene transfer and granule loading can be achieved using the soluble TNF-alpha receptor (sTNFR1) after cDNA expression in hematopoietic cell lines. Endoplasmic reticulum (ER)-export can be facilitated by the addition of a transmembrane domain, and constitutive secretion can be prevented by incorporating a cytosol-sorting signal resulting in secretory lysosome targeting. The sTNFR1 is released from the transmembrane domain by proteolytic cleavage and finally, regulated sTNFR1-secretion can be triggered by a calcium signal. In vivo investigations are currently determining the feasibility of local protein delivery at sites of inflammation.
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Affiliation(s)
- Markus Hansson
- Department of Hematology, C14, BMC, SE-221 84 Lund, Sweden.
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38
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Taverna S, Ghersi G, Ginestra A, Rigogliuso S, Pecorella S, Alaimo G, Saladino F, Dolo V, Dell'Era P, Pavan A, Pizzolanti G, Mignatti P, Presta M, Vittorelli ML. Shedding of Membrane Vesicles Mediates Fibroblast Growth Factor-2 Release from Cells. J Biol Chem 2003; 278:51911-9. [PMID: 14523006 DOI: 10.1074/jbc.m304192200] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Fibroblast growth factor-2 (FGF-2), a polypeptide with regulatory activity on cell growth and differentiation, lacks a conventional secretory signal sequence, and its mechanism of release from cells remains unclear. We characterized the role of extracellular vesicle shedding in FGF-2 release. Viable cells released membrane vesicles in the presence of serum. However, in serum-free medium vesicle shedding was dramatically down-regulated, and the cells did not release FGF-2 activity into their conditioned medium. Addition of serum to serum-starved cells rapidly induced intracellular FGF-2 clustering under the plasma membrane and into granules that colocalized with patches of the cell membrane with typical features of shed vesicle membranes. Shed vesicles carried three FGF-2 isoforms (18, 22, 24 kDa). Addition of vesicles to endothelial cells stimulated chemotaxis and urokinase plasminogen activator production, which were blocked by anti-FGF-2 antibodies. Treatment of intact vesicles with 2.0 m NaCl or heparinase, which release FGF-2 from membrane-bound proteoglycans, did not abolish their stimulatory effect on endothelial cells, indicating that FGF-2 is carried inside vesicles. The comparison of the stimulatory effects of shed vesicles and vesicle-free conditioned medium showed that vesicles represent a major reservoir of FGF-2. Thus, FGF-2 can be released from cells through vesicle shedding.
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Affiliation(s)
- Simona Taverna
- Dipartimento Biologia Cellulare e dello Sviluppo, Università di Palermo, Palermo 90128, Italy
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39
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Abstract
Epithelial and endothelial tubes form the basic structure of many organs and tissues in the fruit fly Drosophila melanogaster, the nematode Caenorhabditis elegans, zebrafish and mammals. Comparison of how tubes form during development defines several pathways that generate a single unbranched tube or dichotomously branching tubular networks. The formation of tubes can be induced directly by intrinsic signals within epithelial primordia or by inductive signaling between adjacent epithelia and the mesenchyme. Both processes are hierarchically controlled by master transcriptional regulators, growth factors and their receptors, directed cell migration and cellular reorganization, which is controlled by changes in the cytoskeleton and protein trafficking. This review provides a summary of these pathways based upon articles published in the Tube Morphogenesis Series in Trends in Cell Biology.
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Affiliation(s)
- W James Nelson
- Department of Molecular and Cellular Physiology, Beckman Center for Molecular and Genetic Medicine, Stanford University School of Medicine, Stanford, CA 94305-5435, USA.
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40
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Johnson GJ, Leis LA, Dunlop PC, Weir EK. The effect of the anorectic agent, d-fenfluramine, and its primary metabolite, d-norfenfluramine, on intact human platelet serotonin uptake and efflux. J Thromb Haemost 2003; 1:2663-8. [PMID: 14675103 DOI: 10.1046/j.1538-7836.2003.00474.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Dexfenfluramine, a drug formerly prescribed for treatment of obesity, caused heart valve damage and pulmonary hypertension in some people. The cause of the toxicity has not been defined, but 5-HT has been implicated. The objective of this study was to evaluate the effect of the anorectic agent, d-fenfluramine, and its major metabolite, d-norfenfluramine, on intact human platelet serotonin (5-HT) transport in vitro. The effects of d-fenfluramine and d-norfenfluramine on platelet uptake and efflux of 3H-5-HT were measured in buffer at pH 6.7, to optimize serotonin transporter (SERT) function, and at pH 7.4. Uptake of 3H-5-HT at pH 6.7 and 7.4 was inhibited by both agents at micro m concentrations (IC50, d-fenfluramine approximately 3 microM; d-norfenfluramine approximately 10 microM). However, no efflux of 3H-5-HT from labeled platelets at either pH 6.7 or 7.4 occurred at similar concentrations of d-fenfluramine or d-norfenfluramine. With inhibition of platelet dense granule 3H-5-HT uptake by reserpine, efflux of 3H-5-HT was observed at pH 6, but not at pH 7.4. Fluoxetine, a SERT inhibitor, was a more potent inhibitor of uptake (IC50 0.05 microM) than d-fenfluramine, but the anorectic agent, phentermine, had no effect. Therefore, d-fenfluramine and d-norfenfluramine inhibit human platelet uptake of 5-HT in vitro at tissue concentrations attainable in vivo, but they do not stimulate 5-HT efflux due to dense granule sequestration. Inhibition of platelet 5-HT uptake may play a role in the cardiopulmonary toxicity of d-fenfluramine, but other factors probably contribute, since similar toxicity has not been observed with fluoxetine.
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Affiliation(s)
- G J Johnson
- Hematology/Oncology Section, Medical Service, Minneapolis Veterans Affairs Medical Center, and Department of Medicine, University of Minnesota, Minneapolis, 55417, USA.
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41
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Affiliation(s)
- Andrew P Feranchak
- Department of Pediatrics, Children's Hospital and the University of Colorado Health Sciences Center, Denver, CO 80262, USA.
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42
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Abstract
Beta-thromboglobulin (beta-TG) is a platelet-specific protein present in the alpha-granules and secreted into the surrounding medium on cell activation. The sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of platelet releasate after inhibition of metalloproteinases with ethyleneglycol-bis-(beta-aminoethyl ether) N,N'-tetra acetic acid (EGTA) showed disappearance of an 8.0-kDa band. In the absence of the cation chelators, a 48-kDa band disappeared and concurrently, the 8.0-kDa band intensity increased suggesting that the former may be the immediate precursor of the latter. The Western blot stained using specific antibodies, isolated from single-cell clones of hybridoma, against 8.0 kDa protein recognized not only 48 and 8.0 kDa bands but few others too. The data suggests that one or more high molecular weight protein is released from alpha-granules and is broken down into smaller fragments after release to form beta-thromboglobulin (beta-TG)-like proteins by the action of metal dependent proteases.
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Affiliation(s)
- K R Resmi
- Thrombosis Research Unit, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, 695012 Trivandrum, India
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43
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Abstract
Bone marrow cells have been suggested to have multilineage plasticity including formation of cardiac tissue. We have established a cardiomyogenic (CMG) cell line from mouse bone marrow stromal cells that can be induced to differentiate into cardiomyocytes in vitro by 5-azacytidine treatment. A number of lines of evidence confirm the cardiomyocyte characteristics of CMG cells.
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Affiliation(s)
- K Fukuda
- Institute for Advanced Cardiac Therapeutics, Keio University School of Medicine, Shinanomachi, Shinjuku-ku, Tokyo, Japan
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44
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Abstract
Slp4-a (synaptotagmin-like protein 4-a)/granuphilin-a is specifically localized on dense-core vesicles in PC12 cells and negatively controls dense-core vesicle exocytosis through specific interaction with Rab27A via the N-terminal Slp homology domain (SHD) (Fukuda, M., Kanno, E., Saegusa, C., Ogata, Y., and Kuroda, T. S. (2002) J. Biol. Chem. 277, 39673-39678). However, the mechanism of the inhibition by Slp4-a has never been elucidated at the molecular level and is still a matter of controversy. In this study, I discovered an unexpected biochemical property of Slp4-a, that Slp4-a, but not other Rab27 effectors reported thus far, is capable of interacting with both Rab27A(T23N), a dominant negative form that mimics the GDP-bound form, and Rab27A(Q78L), a dominant active form that mimics the GTP-bound form, whereas Slp4-a specifically recognizes the GTP-bound form of Rab3A and Rab8A and does not recognize their GDP-bound form. I show by deletion and mutation analyses that the TGDWFY sequence in SHD2 is essential for Rab27A(T23N) binding, whereas SHD1 is involved in Rab27A(Q78L) binding. I further show by immunoprecipitation and cotransfection assays that Munc18-1, but not syntaxin IA, directly interacts with the C-terminal domain of Slp4-a in a Rab27A-independent manner. Expression of Slp4-a mutants that lack Rab27A(T23N) binding activity (i.e. specific binding to Rab27A(Q78L)) completely reverses the inhibitory effect of the wild-type Slp4-a on high KCl-dependent neuropeptide Y secretion in PC12 cells. The results strongly indicate that interaction of Slp4-a with the GDP-bound form of Rab27A, not with syntaxin IA or Munc18-1, is the primary reason that Slp4-a expression inhibits dense core vesicle exocytosis in PC12 cells.
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Affiliation(s)
- Mitsunori Fukuda
- Fukuda Initiative Research Unit, RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
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45
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Evgen'eva TP. Effect of androgenic stimulation of perineal cells from the masked palm civet (Paguma larvatus; Viveridae, Mammalia) during their growth in diffusion chambers on the dynamics of organotypic colony formation. Dokl Biol Sci 2003; 389:120-2. [PMID: 12854407 DOI: 10.1023/a:1023414707791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- T P Evgen'eva
- Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Leninskii pr. 33, Moscow, 117071 Russia
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46
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Abstract
Direct protein delivery is an emerging technology in vaccine development and gene therapy. We could previously show that subviral dense bodies (DB) of human cytomegalovirus (HCMV), a beta-herpesvirus, transport viral proteins into target cells by membrane fusion. Thus these non-infectious particles provide a candidate delivery system for the prophylactic and therapeutic application of proteins. Here we provide proof of principle that DB can be modified genetically. A 55 kDa fusion protein consisting of the green fluorescent protein and the neomycin phosphotransferase could be packed in and delivered into cells by recombinant DB in a functional fashion. Furthermore, transfer of protein into fibroblasts and dendritic cells by DB was efficient, leading to exogenous loading of the MHC-class I antigen presentation pathway. Thus, DB may be a promising basis for the development of novel vaccine strategies and therapeutics based on recombinant polypeptides.
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Affiliation(s)
- S Pepperl-Klindworth
- Institute for Virology, Johannes Gutenberg University of Mainz, Obere Zahlbacher Strasse 67, 55101 Mainz, Germany
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47
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Abstract
Type 2 diabetes mellitus results from a complex interaction between nutritional excess and multiple genes. Whereas pancreatic beta-cells normally respond to glucose challenge by rapid insulin release (first phase insulin secretion), there is a loss of this acute response in virtually all of the type 2 diabetes patients with significant fasting hyperglycemia. Our previous studies demonstrated that irreversible intracellular accumulation of a glucose metabolite, protein O-linked N-acetylglucosamine modification (O-GlcNAc), is associated with pancreatic beta-cell apoptosis. In the present study, we show that streptozotocin (STZ), a non-competitive chemical blocker of O-GlcNAcase, induces an insulin secretory defect in isolated rat islet cells. In contrast, transgenic mice with down-regulated glucose to glucosamine metabolism in beta-cells exhibited an enhanced insulin secretion capacity. Interestingly, the STZ blockade of O-GlcNAcase activity is also associated with a growth hormone secretory defect and impairment of intracellular secretory vesicle trafficking. These results provide evidence for the roles of O-GlcNAc in the insulin secretion and possible involvement of O-GlcNAc in general glucose-regulated hormone secretion pathways.
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Affiliation(s)
- Kan Liu
- Department of Medicine/Endocrinology, Cell Biology, University of Alabama at Birmingham, 1808 7th Avenue South, Rm 756, Birmingham, AL 35294, USA
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48
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Abstract
Does the Golgi apparatus proliferate by adding new material to a permanent template, or do Golgi structures form de novo by a process of self-organization? Recent work suggests that the Golgi is capable of forming de novo.
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49
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Abstract
With the completion of the Arabidopsis genome, many hypothetical proteins have been predicted without any information on their expression, subcellular localisation and function. We have performed proteomic analysis of proteins sequentially extracted from enriched Arabidopsis cell wall fractions and separated by two-dimensional gel electrophoresis (2-DE). The proteins were identified by peptide mass fingerprinting using matrix-assisted laser desorption/ionisation-time of flight (MALDI-TOF) mass spectrometry and genomic database searches. This is part of a targeted exercise to establish the entire Arabidopsis secretome database. We report evidence for new proteins of unknown function whose existence had been predicted from genomic sequences and, furthermore, localise them to the cell wall. In addition, we observed an unexpected presence in the cell wall preparations of proteins whose known biochemical activity has never been associated with this compartment hitherto. We discuss the implications of these findings and present results suggesting a possible involvement of cell wall kinases in plant responses to pathogen attack.
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Affiliation(s)
- Stephen Chivasa
- Creative Gene Technology Ltd., Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, University of Durham, Durham, UK
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50
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Abstract
With the completion of the Arabidopsis genome, many hypothetical proteins have been predicted without any information on their expression, subcellular localisation and function. We have performed proteomic analysis of proteins sequentially extracted from enriched Arabidopsis cell wall fractions and separated by two-dimensional gel electrophoresis (2-DE). The proteins were identified by peptide mass fingerprinting using matrix-assisted laser desorption/ionisation-time of flight (MALDI-TOF) mass spectrometry and genomic database searches. This is part of a targeted exercise to establish the entire Arabidopsis secretome database. We report evidence for new proteins of unknown function whose existence had been predicted from genomic sequences and, furthermore, localise them to the cell wall. In addition, we observed an unexpected presence in the cell wall preparations of proteins whose known biochemical activity has never been associated with this compartment hitherto. We discuss the implications of these findings and present results suggesting a possible involvement of cell wall kinases in plant responses to pathogen attack.
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Affiliation(s)
- Stephen Chivasa
- Creative Gene Technology Ltd., Integrative Cell Biology Laboratory, School of Biological and Biomedical Sciences, University of Durham, Durham, UK
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