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Wang S, Wang J, Lu X, Liu M, Liu Y, Li M, Kong X, Wu L, Guan Q, Zhang W. Design, synthesis and biological evaluation of novel tubulin-targeting agents with a dual-mechanism for polymerization inhibition and protein degradation. Eur J Med Chem 2024; 272:116458. [PMID: 38703557 DOI: 10.1016/j.ejmech.2024.116458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2024] [Revised: 04/12/2024] [Accepted: 04/25/2024] [Indexed: 05/06/2024]
Abstract
Microtubules are recognized as one of the most vital and attractive targets in anticancer therapy. The development of novel tubulin-targeting agents with a new action mechanism is imperative. Based on the hydrophobic tagging strategy, the molecular scaffold of tirbanibulin was selected as tubulin target-binding moiety, subsequent to which a series of target compounds were rationally designed by selecting various combinations of linkers and hydrophobic tags. A set of novel molecules were synthesized and most of them exhibited potent antiproliferative activity against tumor cells in vitro. The most active compound 14b inhibited polymerization of purified recombinant tubulin and induced degradation of α- and β-tubulin in MCF-7 cells. Notably, following treatment with compound 14b, an unexpected phenomenon of "microtubules fragmentation" was observed via immunofluorescence staining. Furthermore, compound 14b possessed antitumor activity in the 4T1 allograft models with TGI of 74.27 % without significant toxicity. In this work, we report the discovery of novel dual-mechanism tubulin-targeting agents.
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Affiliation(s)
- Sibo Wang
- Key Laboratory of Structure-Based Drug Design and Discovery, Ministry of Education, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenhe District, Shenyang, 110016, China
| | - Jiahao Wang
- Key Laboratory of Structure-Based Drug Design and Discovery, Ministry of Education, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenhe District, Shenyang, 110016, China
| | - Xiankun Lu
- School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenhe District, Shenyang, 110016, China
| | - Meitong Liu
- School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenhe District, Shenyang, 110016, China
| | - Yue Liu
- School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenhe District, Shenyang, 110016, China
| | - Mi Li
- School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenhe District, Shenyang, 110016, China
| | - Xuejie Kong
- Department of Geratology, The First Affiliated Hospital, Chinese Medical University, Shenyang, 110001, China
| | - Lan Wu
- Department of Geratology, The First Affiliated Hospital, Chinese Medical University, Shenyang, 110001, China.
| | - Qi Guan
- School of Pharmaceutical Engineering, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenhe District, Shenyang, 110016, China.
| | - Weige Zhang
- Key Laboratory of Structure-Based Drug Design and Discovery, Ministry of Education, Shenyang Pharmaceutical University, 103 Wenhua Road, Shenhe District, Shenyang, 110016, China.
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2
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Pugliese LA, De Lorenzi V, Bernardi M, Ghignoli S, Tesi M, Marchetti P, Pesce L, Cardarelli F. Unveiling nanoscale optical signatures of cytokine-induced β-cell dysfunction. Sci Rep 2023; 13:13342. [PMID: 37587148 PMCID: PMC10432522 DOI: 10.1038/s41598-023-40272-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 08/08/2023] [Indexed: 08/18/2023] Open
Abstract
Pro-inflammatory cytokines contribute to β-cell failure in both Type-1 and Type-2 Diabetes. Data collected so far allowed to dissect the genomic, transcriptomic, proteomic and biochemical landscape underlying cytokine-induced β-cell progression through dysfunction. Yet, no report thus far complemented such molecular information with the direct optical nanoscopy of the β-cell subcellular environment. Here we tackle this issue in Insulinoma 1E (INS-1E) β-cells by label-free fluorescence lifetime imaging microscopy (FLIM) and fluorescence-based super resolution imaging by expansion microscopy (ExM). It is found that 24-h exposure to IL-1β and IFN-γ is associated with a neat modification of the FLIM signature of cell autofluorescence due to the increase of either enzyme-bound NAD(P)H molecules and of oxidized lipid species. At the same time, ExM-based direct imaging unveils neat alteration of mitochondrial morphology (i.e. ~ 80% increase of mitochondrial circularity), marked degranulation (i.e. ~ 40% loss of insulin granules, with mis-localization of the surviving pool), appearance of F-actin-positive membrane blebs and an hitherto unknown extensive fragmentation of the microtubules network (e.g. ~ 37% reduction in the number of branches). Reported observations provide an optical-microscopy framework to interpret the amount of molecular information collected so far on β-cell dysfunction and pave the way to future ex-vivo and in-vivo investigations.
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Affiliation(s)
- Licia Anna Pugliese
- NEST Laboratory - Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, Italy.
| | - Valentina De Lorenzi
- NEST Laboratory - Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, Italy
| | - Mario Bernardi
- NEST Laboratory - Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, Italy
| | - Samuele Ghignoli
- NEST Laboratory - Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, Italy
| | - Marta Tesi
- Department of Clinical and Experimental Medicine, Islet Cell Laboratory, University of Pisa, Pisa, Italy
| | - Piero Marchetti
- Department of Clinical and Experimental Medicine, Islet Cell Laboratory, University of Pisa, Pisa, Italy
| | - Luca Pesce
- NEST Laboratory - Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, Italy.
| | - Francesco Cardarelli
- NEST Laboratory - Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, Italy.
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3
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Fye MA, Kaverina I. Insulin secretion hot spots in pancreatic β cells as secreting adhesions. Front Cell Dev Biol 2023; 11:1211482. [PMID: 37305687 PMCID: PMC10250740 DOI: 10.3389/fcell.2023.1211482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 05/18/2023] [Indexed: 06/13/2023] Open
Abstract
Pancreatic β cell secretion of insulin is crucial to the maintenance of glucose homeostasis and prevention of diseases related to glucose regulation, including diabetes. Pancreatic β cells accomplish efficient insulin secretion by clustering secretion events at the cell membrane facing the vasculature. Regions at the cell periphery characterized by clustered secretion are currently termed insulin secretion hot spots. Several proteins, many associated with the microtubule and actin cytoskeletons, are known to localize to and serve specific functions at hot spots. Among these proteins are the scaffolding protein ELKS, the membrane-associated proteins LL5β and liprins, the focal adhesion-associated protein KANK1, and other factors typically associated with the presynaptic active zone in neurons. These hot spot proteins have been shown to contribute to insulin secretion, but many questions remain regarding their organization and dynamics at hot spots. Current studies suggest microtubule- and F-actin are involved in regulation of hot spot proteins and their function in secretion. The hot spot protein association with the cytoskeleton networks also suggests a potential role for mechanical regulation of these proteins and hot spots in general. This perspective summarizes the existing knowledge of known hot spot proteins, their cytoskeletal-mediated regulation, and discuss questions remaining regarding mechanical regulation of pancreatic beta cell hot spots.
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Affiliation(s)
| | - Irina Kaverina
- Kaverina Lab, Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, United States
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4
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Lodato M, Plaisance V, Pawlowski V, Kwapich M, Barras A, Buissart E, Dalle S, Szunerits S, Vicogne J, Boukherroub R, Abderrahmani A. Venom Peptides, Polyphenols and Alkaloids: Are They the Next Antidiabetics That Will Preserve β-Cell Mass and Function in Type 2 Diabetes? Cells 2023; 12:cells12060940. [PMID: 36980281 PMCID: PMC10047094 DOI: 10.3390/cells12060940] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 03/09/2023] [Accepted: 03/17/2023] [Indexed: 03/22/2023] Open
Abstract
Improvement of insulin secretion by pancreatic β-cells and preservation of their mass are the current challenges that future antidiabetic drugs should meet for achieving efficient and long-term glycemic control in patients with type 2 diabetes (T2D). The successful development of glucagon-like peptide 1 (GLP-1) analogues, derived from the saliva of a lizard from the Helodermatidae family, has provided the proof of concept that antidiabetic drugs directly targeting pancreatic β-cells can emerge from venomous animals. The literature reporting on the antidiabetic effects of medicinal plants suggests that they contain some promising active substances such as polyphenols and alkaloids, which could be active as insulin secretagogues and β-cell protectors. In this review, we discuss the potential of several polyphenols, alkaloids and venom peptides from snake, frogs, scorpions and cone snails. These molecules could contribute to the development of new efficient antidiabetic medicines targeting β-cells, which would tackle the progression of the disease.
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Affiliation(s)
- Michele Lodato
- University Lille, CNRS, Centrale Lille, University Polytechnique Hauts-de-France, UMR 8520, IEMN, F-59000 Lille, France
| | - Valérie Plaisance
- University Lille, CNRS, Centrale Lille, University Polytechnique Hauts-de-France, UMR 8520, IEMN, F-59000 Lille, France
| | - Valérie Pawlowski
- University Lille, CNRS, Centrale Lille, University Polytechnique Hauts-de-France, UMR 8520, IEMN, F-59000 Lille, France
| | - Maxime Kwapich
- University Lille, CNRS, Centrale Lille, University Polytechnique Hauts-de-France, UMR 8520, IEMN, F-59000 Lille, France
- Service de Diabétologie et d’Endocrinologie, CH Dunkerque, 59385 Dunkirk, France
| | - Alexandre Barras
- University Lille, CNRS, Centrale Lille, University Polytechnique Hauts-de-France, UMR 8520, IEMN, F-59000 Lille, France
| | - Emeline Buissart
- University Lille, CNRS, Centrale Lille, University Polytechnique Hauts-de-France, UMR 8520, IEMN, F-59000 Lille, France
| | - Stéphane Dalle
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094 Montpellier, France
| | - Sabine Szunerits
- University Lille, CNRS, Centrale Lille, University Polytechnique Hauts-de-France, UMR 8520, IEMN, F-59000 Lille, France
| | - Jérôme Vicogne
- University Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019-UMR 9017-CIIL-Center for Infection and Immunity of Lille, F-59000 Lille, France
| | - Rabah Boukherroub
- University Lille, CNRS, Centrale Lille, University Polytechnique Hauts-de-France, UMR 8520, IEMN, F-59000 Lille, France
| | - Amar Abderrahmani
- University Lille, CNRS, Centrale Lille, University Polytechnique Hauts-de-France, UMR 8520, IEMN, F-59000 Lille, France
- Correspondence: ; Tel.: +33-362531704
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5
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Bracey KM, Gu G, Kaverina I. Microtubules in Pancreatic β Cells: Convoluted Roadways Toward Precision. Front Cell Dev Biol 2022; 10:915206. [PMID: 35874834 PMCID: PMC9305484 DOI: 10.3389/fcell.2022.915206] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 06/14/2022] [Indexed: 11/18/2022] Open
Abstract
Pancreatic islet β cells regulate glucose homeostasis via glucose-stimulated insulin secretion (GSIS). Cytoskeletal polymers microtubules (MTs) serve as tracks for the transport and positioning of secretory insulin granules. MT network in β cells has unique morphology with several distinct features, which support granule biogenesis (via Golgi-derived MT array), net non-directional transport (via interlocked MT mesh), and control availability of granules at secretion sites (via submembrane MT bundle). The submembrane MT array, which is parallel to the plasma membrane and serves to withdraw excessive granules from the secretion hot spots, is destabilized and fragmented downstream of high glucose stimulation, allowing for regulated secretion. The origin of such an unusual MT network, the features that define its functionality, and metabolic pathways that regulate it are still to a large extent elusive and are a matter of active investigation and debate. Besides the MT network itself, it is important to consider the interplay of molecular motors that drive and fine-tune insulin granule transport. Importantly, activity of kinesin-1, which is the major MT-dependent motor in β cells, transports insulin granules, and has a capacity to remodel MT network, is also regulated by glucose. We discuss yet unknown potential avenues toward understanding how MT network and motor proteins provide control for secretion in coordination with other GSIS-regulating mechanisms.
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Müller A, Schmidt D, Xu CS, Pang S, D’Costa JV, Kretschmar S, Münster C, Kurth T, Jug F, Weigert M, Hess HF, Solimena M. 3D FIB-SEM reconstruction of microtubule-organelle interaction in whole primary mouse β cells. J Cell Biol 2021; 220:e202010039. [PMID: 33326005 PMCID: PMC7748794 DOI: 10.1083/jcb.202010039] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 11/14/2020] [Accepted: 11/18/2020] [Indexed: 11/22/2022] Open
Abstract
Microtubules play a major role in intracellular trafficking of vesicles in endocrine cells. Detailed knowledge of microtubule organization and their relation to other cell constituents is crucial for understanding cell function. However, their role in insulin transport and secretion is under debate. Here, we use FIB-SEM to image islet β cells in their entirety with unprecedented resolution. We reconstruct mitochondria, Golgi apparati, centrioles, insulin secretory granules, and microtubules of seven β cells, and generate a comprehensive spatial map of microtubule-organelle interactions. We find that microtubules form nonradial networks that are predominantly not connected to either centrioles or endomembranes. Microtubule number and length, but not microtubule polymer density, vary with glucose stimulation. Furthermore, insulin secretory granules are enriched near the plasma membrane, where they associate with microtubules. In summary, we provide the first 3D reconstructions of complete microtubule networks in primary mammalian cells together with evidence regarding their importance for insulin secretory granule positioning and thus their supportive role in insulin secretion.
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Affiliation(s)
- Andreas Müller
- Molecular Diabetology, University Hospital and Faculty of Medicine, Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the University Hospital and Faculty of Medicine, Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany
| | - Deborah Schmidt
- Center for Systems Biology Dresden, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - C. Shan Xu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Song Pang
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Joyson Verner D’Costa
- Molecular Diabetology, University Hospital and Faculty of Medicine, Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the University Hospital and Faculty of Medicine, Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany
| | - Susanne Kretschmar
- Center for Molecular and Cellular Bioengineering, Technology Platform, Technische Universität Dresden, Dresden, Germany
| | - Carla Münster
- Molecular Diabetology, University Hospital and Faculty of Medicine, Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the University Hospital and Faculty of Medicine, Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany
| | - Thomas Kurth
- Center for Molecular and Cellular Bioengineering, Technology Platform, Technische Universität Dresden, Dresden, Germany
| | - Florian Jug
- Center for Systems Biology Dresden, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- Fondazione Human Technopole, Milano, Italy
| | - Martin Weigert
- Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Harald F. Hess
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - Michele Solimena
- Molecular Diabetology, University Hospital and Faculty of Medicine, Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Paul Langerhans Institute Dresden of the Helmholtz Center Munich at the University Hospital and Faculty of Medicine, Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- German Center for Diabetes Research (DZD e.V.), Neuherberg, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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7
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Ho KH, Yang X, Osipovich AB, Cabrera O, Hayashi ML, Magnuson MA, Gu G, Kaverina I. Glucose Regulates Microtubule Disassembly and the Dose of Insulin Secretion via Tau Phosphorylation. Diabetes 2020; 69:1936-1947. [PMID: 32540877 PMCID: PMC7458041 DOI: 10.2337/db19-1186] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 06/07/2020] [Indexed: 12/16/2022]
Abstract
The microtubule cytoskeleton of pancreatic islet β-cells regulates glucose-stimulated insulin secretion (GSIS). We have reported that the microtubule-mediated movement of insulin vesicles away from the plasma membrane limits insulin secretion. High glucose-induced remodeling of microtubule network facilitates robust GSIS. This remodeling involves disassembly of old microtubules and nucleation of new microtubules. Here, we examine the mechanisms whereby glucose stimulation decreases microtubule lifetimes in β-cells. Using real-time imaging of photoconverted microtubules, we demonstrate that high levels of glucose induce rapid microtubule disassembly preferentially in the periphery of individual β-cells, and this process is mediated by the phosphorylation of microtubule-associated protein tau. Specifically, high glucose induces tau hyper-phosphorylation via glucose-responsive kinases GSK3, PKA, PKC, and CDK5. This causes dissociation of tau from and subsequent destabilization of microtubules. Consequently, tau knockdown in mouse islet β-cells facilitates microtubule turnover, causing increased basal insulin secretion, depleting insulin vesicles from the cytoplasm, and impairing GSIS. More importantly, tau knockdown uncouples microtubule destabilization from glucose stimulation. These findings suggest that tau suppresses peripheral microtubules turning over to restrict insulin oversecretion in basal conditions and preserve the insulin pool that can be released following stimulation; high glucose promotes tau phosphorylation to enhance microtubule disassembly to acutely enhance GSIS.
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Affiliation(s)
- Kung-Hsien Ho
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
- Program of Developmental Biology and Vanderbilt Center for Stem Cell Biology, Vanderbilt University, Nashville, TN
| | - Xiaodun Yang
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
- Program of Developmental Biology and Vanderbilt Center for Stem Cell Biology, Vanderbilt University, Nashville, TN
| | - Anna B Osipovich
- Program of Developmental Biology and Vanderbilt Center for Stem Cell Biology, Vanderbilt University, Nashville, TN
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | | | | | - Mark A Magnuson
- Program of Developmental Biology and Vanderbilt Center for Stem Cell Biology, Vanderbilt University, Nashville, TN
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Guoqiang Gu
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
- Program of Developmental Biology and Vanderbilt Center for Stem Cell Biology, Vanderbilt University, Nashville, TN
| | - Irina Kaverina
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
- Program of Developmental Biology and Vanderbilt Center for Stem Cell Biology, Vanderbilt University, Nashville, TN
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Bracey KM, Ho KH, Yampolsky D, Gu G, Kaverina I, Holmes WR. Microtubules Regulate Localization and Availability of Insulin Granules in Pancreatic Beta Cells. Biophys J 2019; 118:193-206. [PMID: 31839261 DOI: 10.1016/j.bpj.2019.10.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 10/15/2019] [Accepted: 10/21/2019] [Indexed: 11/18/2022] Open
Abstract
Two key prerequisites for glucose-stimulated insulin secretion (GSIS) in β cells are the proximity of insulin granules to the plasma membrane and their anchoring or docking to the plasma membrane (PM). Although recent evidence has indicated that both of these factors are altered in the context of diabetes, it is unclear what regulates localization of insulin granules and their interactions with the PM within single cells. Here, we demonstrate that microtubule (MT)-motor-mediated transport dynamics have a critical role in regulating both factors. Super-resolution imaging shows that whereas the MT cytoskeleton resembles a random meshwork in the cells' interior, MTs near the cell surface are preferentially aligned with the PM. Computational modeling suggests two consequences of this alignment. First, this structured MT network preferentially withdraws granules from the PM. Second, the binding and transport of insulin granules by MT motors prevents their stable anchoring to the PM. These findings suggest the MT cytoskeleton may negatively regulate GSIS by both limiting the amount of insulin proximal to the PM and preventing or breaking interactions between the PM and the remaining nearby insulin granules. These results predict that altering MT network structure in β cells can be used to tune GSIS. Thus, our study points to the potential of an alternative therapeutic strategy for diabetes by targeting specific MT regulators.
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Affiliation(s)
| | | | - Dmitry Yampolsky
- Vanderbilt University, Nashville, Tennessee; University of Massachusetts Boston, Boston, Massachusetts
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9
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Rodríguez‐Sevilla P, Sanz‐Rodríguez F, Peláez RP, Delgado‐Buscalioni R, Liang L, Liu X, Jaque D. Upconverting Nanorockers for Intracellular Viscosity Measurements During Chemotherapy. ACTA ACUST UNITED AC 2019; 3:e1900082. [DOI: 10.1002/adbi.201900082] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 07/22/2019] [Indexed: 11/06/2022]
Affiliation(s)
| | - Francisco Sanz‐Rodríguez
- Fluorescence Imaging Group Departamento de Biología Facultad de CienciasUniversidad Autónoma de Madrid 28049 Madrid Spain
- Nanobiology GroupInstituto Ramón y Cajal de Investigación Sanitaria Hospital Ramón y Cajal. Ctra. De Colmenar Viejo Km. 9100 28034 Madrid Spain
| | - Raúl P. Peláez
- Departamento de Física Teórica de la Materia Condensada Facultad de CienciasUniversidad Autónoma de Madrid 28049 Madrid Spain
| | - Rafael Delgado‐Buscalioni
- Departamento de Física Teórica de la Materia Condensada Facultad de CienciasUniversidad Autónoma de Madrid 28049 Madrid Spain
| | - Liangliang Liang
- Department of ChemistryNational University of Singapore Science Drive 3 Singapore 117543 Singapore
| | - Xiaogang Liu
- Department of ChemistryNational University of Singapore Science Drive 3 Singapore 117543 Singapore
| | - Daniel Jaque
- Nanobiology GroupInstituto Ramón y Cajal de Investigación Sanitaria Hospital Ramón y Cajal. Ctra. De Colmenar Viejo Km. 9100 28034 Madrid Spain
- Fluorescence Imaging Group Departamento de Fisica de MaterialesUniversidad Autónoma de Madrid 28049 Madrid Spain
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Locally Triggered Release of the Chemokine CCL21 Promotes Dendritic Cell Transmigration across Lymphatic Endothelia. Cell Rep 2018; 19:902-909. [PMID: 28467903 PMCID: PMC5437727 DOI: 10.1016/j.celrep.2017.04.027] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 03/21/2017] [Accepted: 04/10/2017] [Indexed: 01/29/2023] Open
Abstract
Trafficking cells frequently transmigrate through epithelial and endothelial monolayers. How monolayers cooperate with the penetrating cells to support their transit is poorly understood. We studied dendritic cell (DC) entry into lymphatic capillaries as a model system for transendothelial migration. We find that the chemokine CCL21, which is the decisive guidance cue for intravasation, mainly localizes in the trans-Golgi network and intracellular vesicles of lymphatic endothelial cells. Upon DC transmigration, these Golgi deposits disperse and CCL21 becomes extracellularly enriched at the sites of endothelial cell-cell junctions. When we reconstitute the transmigration process in vitro, we find that secretion of CCL21-positive vesicles is triggered by a DC contact-induced calcium signal, and selective calcium chelation in lymphatic endothelium attenuates transmigration. Altogether, our data demonstrate a chemokine-mediated feedback between DCs and lymphatic endothelium, which facilitates transendothelial migration. DC entry into lymphatic capillary induces CCL21 secretion to endothelial junctions Chemokine CCL21 secretion is triggered by calcium fluxes Direct contact by DC induces calcium signaling in LECs Dynamic rather than pre-patterned chemokine CCL21 cues promote DC transmigration
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11
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Wijesekara N, Gonçalves RA, Ahrens R, De Felice FG, Fraser PE. Tau ablation in mice leads to pancreatic β cell dysfunction and glucose intolerance. FASEB J 2018; 32:3166-3173. [DOI: 10.1096/fj.201701352] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Nadeeja Wijesekara
- Tanz Centre for Research in Neurodegenerative DiseasesUniversity of Toronto Toronto Ontario Canada
| | - Rafaella Araujo Gonçalves
- Tanz Centre for Research in Neurodegenerative DiseasesUniversity of Toronto Toronto Ontario Canada
- Department of Medical BiophysicsUniversity of Toronto Toronto Ontario Canada
| | - Rosemary Ahrens
- Tanz Centre for Research in Neurodegenerative DiseasesUniversity of Toronto Toronto Ontario Canada
| | - Fernanda G. De Felice
- Department of Medical BiophysicsUniversity of Toronto Toronto Ontario Canada
- Institute of Medical Biochemistry Leopoldo de MeisFederal University of Rio de Janeiro Rio de Janeiro Brazil
| | - Paul E. Fraser
- Tanz Centre for Research in Neurodegenerative DiseasesUniversity of Toronto Toronto Ontario Canada
- Department of Biomedical and Molecular SciencesCentre for Neuroscience StudiesQueen's University Kingston Ontario Canada
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12
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Margolis G, Hertzberg-Bigelman E, Levy R, Ben-Shoshan J, Keren G, Entin-Meer M. Differential Effects of Colchicine on Cardiac Cell Viability in an in vitro Model Simulating Myocardial Infarction. Cardiology 2016; 134:57-64. [PMID: 26882242 DOI: 10.1159/000443369] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 12/15/2015] [Indexed: 11/19/2022]
Abstract
OBJECTIVES We aimed to examine the effects of colchicine, currently in clinical trials for acute myocardial infarction (AMI), on the viability of cardiac cells using a cell line model of AMI. METHODS HL-1, a murine cardiomyocyte cell line, and H9C2, a rat cardiomyoblast cell line, were incubated with TNFα or sera derived from rats that underwent AMI or sham operation followed by addition of colchicine. In another experiment, HL-1/H9C2 cells were exposed to anoxia with or without subsequent addition of colchicine. Cell morphology and viability were assessed by light microscopy, flow cytometry and Western blot analyses for apoptotic markers. RESULTS Cellular viability was similar in both sera; however, exposing both cell lines to anoxia reduced their viability. Adding colchicine to anoxic H9C2, but not to anoxic HL-1, further increased their mortality, at least in part via enhanced apoptosis. Under any condition, colchicine induced detachment of H9C2 cells from their culture plates. This phenomenon did not apply to HL-1 cells. CONCLUSIONS Colchicine enhanced cardiomyoblast mortality under in vitro conditions mimicking AMI and reduced their adherence capability. HL-1 was not affected by colchicine; nevertheless, no salvage effect was observed. We thus conclude that colchicine may not inhibit myocardial apoptosis following AMI.
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Affiliation(s)
- Gilad Margolis
- Department of Internal Medicine H, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
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Microtubules Negatively Regulate Insulin Secretion in Pancreatic β Cells. Dev Cell 2016; 34:656-68. [PMID: 26418295 DOI: 10.1016/j.devcel.2015.08.020] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Revised: 06/04/2015] [Accepted: 08/26/2015] [Indexed: 01/06/2023]
Abstract
For glucose-stimulated insulin secretion (GSIS), insulin granules have to be localized close to the plasma membrane. The role of microtubule-dependent transport in granule positioning and GSIS has been debated. Here, we report that microtubules, counterintuitively, restrict granule availability for secretion. In β cells, microtubules originate at the Golgi and form a dense non-radial meshwork. Non-directional transport along these microtubules limits granule dwelling at the cell periphery, restricting granule availability for secretion. High glucose destabilizes microtubules, decreasing their density; such local microtubule depolymerization is necessary for GSIS, likely because granule withdrawal from the cell periphery becomes inefficient. Consistently, microtubule depolymerization by nocodazole blocks granule withdrawal, increases their concentration at exocytic sites, and dramatically enhances GSIS in vitro and in mice. Furthermore, glucose-driven MT destabilization is balanced by new microtubule formation, which likely prevents over-secretion. Importantly, microtubule density is greater in dysfunctional β cells of diabetic mice.
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14
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Fan F, Ji C, Wu Y, Ferguson SM, Tamarina N, Philipson LH, Lou X. Dynamin 2 regulates biphasic insulin secretion and plasma glucose homeostasis. J Clin Invest 2015; 125:4026-41. [PMID: 26413867 DOI: 10.1172/jci80652] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 08/20/2015] [Indexed: 12/18/2022] Open
Abstract
Alterations in insulin granule exocytosis and endocytosis are paramount to pancreatic β cell dysfunction in diabetes mellitus. Here, using temporally controlled gene ablation specifically in β cells in mice, we identified an essential role of dynamin 2 GTPase in preserving normal biphasic insulin secretion and blood glucose homeostasis. Dynamin 2 deletion in β cells caused glucose intolerance and substantial reduction of the second phase of glucose-stimulated insulin secretion (GSIS); however, mutant β cells still maintained abundant insulin granules, with no signs of cell surface expansion. Compared with control β cells, real-time capacitance measurements demonstrated that exocytosis-endocytosis coupling was less efficient but not abolished; clathrin-mediated endocytosis (CME) was severely impaired at the step of membrane fission, which resulted in accumulation of clathrin-coated endocytic intermediates on the plasma membrane. Moreover, dynamin 2 ablation in β cells led to striking reorganization and enhancement of actin filaments, and insulin granule recruitment and mobilization were impaired at the later stage of GSIS. Together, our results demonstrate that dynamin 2 regulates insulin secretory capacity and dynamics in vivo through a mechanism depending on CME and F-actin remodeling. Moreover, this study indicates a potential pathophysiological link between endocytosis and diabetes mellitus.
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15
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Ciliary dysfunction impairs beta-cell insulin secretion and promotes development of type 2 diabetes in rodents. Nat Commun 2014; 5:5308. [PMID: 25374274 DOI: 10.1038/ncomms6308] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 09/18/2014] [Indexed: 11/08/2022] Open
Abstract
Type 2 diabetes mellitus is affecting more than 382 million people worldwide. Although much progress has been made, a comprehensive understanding of the underlying disease mechanism is still lacking. Here we report a role for the β-cell primary cilium in type 2 diabetes susceptibility. We find impaired glucose handling in young Bbs4(-/-) mice before the onset of obesity. Basal body/ciliary perturbation in murine pancreatic islets leads to impaired first phase insulin release ex and in vivo. Insulin receptor is recruited to the cilium of stimulated β-cells and ciliary/basal body integrity is required for activation of downstream targets of insulin signalling. We also observe a reduction in the number of ciliated β-cells along with misregulated ciliary/basal body gene expression in pancreatic islets in a diabetic rat model. We suggest that ciliary function is implicated in insulin secretion and insulin signalling in the β-cell and that ciliary dysfunction could contribute to type 2 diabetes susceptibility.
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16
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Pottekat A, Becker S, Spencer KR, Yates JR, Manning G, Itkin-Ansari P, Balch WE. Insulin biosynthetic interaction network component, TMEM24, facilitates insulin reserve pool release. Cell Rep 2013; 4:921-30. [PMID: 24012759 DOI: 10.1016/j.celrep.2013.07.050] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 07/16/2013] [Accepted: 07/31/2013] [Indexed: 12/31/2022] Open
Abstract
Insulin homeostasis in pancreatic β cells is now recognized as a critical element in the progression of obesity and type II diabetes (T2D). Proteins that interact with insulin to direct its sequential synthesis, folding, trafficking, and packaging into reserve granules in order to manage release in response to elevated glucose remain largely unknown. Using a conformation-based approach combined with mass spectrometry, we have generated the insulin biosynthetic interaction network (insulin BIN), a proteomic roadmap in the β cell that describes the sequential interacting partners of insulin along the secretory axis. The insulin BIN revealed an abundant C2 domain-containing transmembrane protein 24 (TMEM24) that manages glucose-stimulated insulin secretion from a reserve pool of granules, a critical event impaired in patients with T2D. The identification of TMEM24 in the context of a comprehensive set of sequential insulin-binding partners provides a molecular description of the insulin secretory pathway in β cells.
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Affiliation(s)
- Anita Pottekat
- Department of Cell and Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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17
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Abstract
The impact that nanotechnology may have on life and medical sciences is immense and includes novel therapies as much as novel diagnostic and imaging tools, often offering the possibility to combine the two. It is, therefore, of the essence to understand and control the interactions that nanomaterials can have with cells, first at an individual level, focusing on, e.g., binding and internalization events, and then at a tissue level, where diffusion and long-range transport add further complications. Here, we present experimental methods based on selective labeling techniques and the use of effectors for a qualitative and quantitative evaluation of endocytic phenomena involving nanoparticles. The understanding of the cell-material interactions arising from these tests can then form the basis for a model-based evaluation of nanoparticles behavior in 3D tissues.
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18
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Cameron RS, Arvan P, Castle JD. Secretory Membranes and the Exocrine Storage Compartment. Compr Physiol 2011. [DOI: 10.1002/cphy.cp060307] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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19
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Cui J, Wang Z, Cheng Q, Lin R, Zhang XM, Leung PS, Copeland NG, Jenkins NA, Yao KM, Huang JD. Targeted inactivation of kinesin-1 in pancreatic β-cells in vivo leads to insulin secretory deficiency. Diabetes 2011; 60:320-30. [PMID: 20870970 PMCID: PMC3012189 DOI: 10.2337/db09-1078] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Suppression of Kinesin-1 by antisense oligonucleotides, or overexpression of dominant-negative acting kinesin heavy chain, has been reported to affect the sustained phase of glucose-stimulated insulin secretion in β-cells in vitro. In this study, we examined the in vivo physiological role of Kinesin-1 in β-cell development and function. RESEARCH DESIGN AND METHODS A Cre-LoxP strategy was used to generate conditional knockout mice in which the Kif5b gene is specifically inactivated in pancreatic β-cells. Physiological and histological analyses were carried out in Kif5b knockout mice as well as littermate controls. RESULTS Mice with β-cell specific deletion of Kif5b (Kif5b(fl/)⁻:RIP2-Cre) displayed significantly retarded growth as well as slight hyperglycemia in both nonfasting and 16-h fasting conditions compared with control littermates. In addition, Kif5b(fl/)⁻:RIP2-Cre mice displayed significant glucose intolerance, which was not due to insulin resistance but was related to an insulin secretory defect in response to glucose challenge. These defects of β-cell function in mutant mice were not coupled with observable changes in islet morphology, islet cell composition, or β-cell size. However, compared with controls, pancreas of Kif5b(fl/)⁻:RIP2-Cre mice exhibited both reduced islet size and increased islet number, concomitant with an increased insulin vesicle density in β-cells. CONCLUSIONS In addition to being essential for maintaining glucose homeostasis and regulating β-cell function, Kif5b may be involved in β-cell development by regulating β-cell proliferation and insulin vesicle synthesis.
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Affiliation(s)
- Ju Cui
- Department of Biochemistry, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Zai Wang
- Department of Biochemistry, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Qianni Cheng
- Department of Physiology, The Chinese University of Hong Kong, Hong Kong
| | - Raozhou Lin
- Department of Biochemistry, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Xin-Mei Zhang
- Department of Biochemistry, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
| | - Po Sing Leung
- Department of Physiology, The Chinese University of Hong Kong, Hong Kong
| | - Neal G. Copeland
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore
| | - Nancy A. Jenkins
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore
| | - Kwok-Ming Yao
- Department of Biochemistry, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
- Corresponding author: Jian-Dong Huang, , or Kwok-Ming Yao,
| | - Jian-Dong Huang
- Department of Biochemistry, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong
- Corresponding author: Jian-Dong Huang, , or Kwok-Ming Yao,
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20
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Zaki NM, Tirelli N. Gateways for the intracellular access of nanocarriers: a review of receptor-mediated endocytosis mechanisms and of strategies in receptor targeting. Expert Opin Drug Deliv 2010; 7:895-913. [PMID: 20629604 DOI: 10.1517/17425247.2010.501792] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
IMPORTANCE OF THE FIELD The last 10 years have seen a dramatic growth in understanding and controlling how complex, drug-loaded (nano)structures, as well as pathogens, or biopharmaceuticals can gather access to the cytoplasm, which is a key step to increasing the effectiveness of their action. AREAS COVERED IN THIS REVIEW The review offers an updated overview of the current knowledge of endocytic processes; furthermore, the cell surface receptors most commonly used in drug delivery are here discussed on the basis of their reported internalization mechanisms, with examples of their use as nanocarrier targets taken from the most recent scientific literature. WHAT THE READER WILL GAIN Knowledge of molecular biology details is increasingly necessary for a rational design of drug delivery systems. Here, the aim is to provide the reader with an attempt to link a mechanistic knowledge of endocytic mechanisms with the identification of appropriate targets (internalization receptors) for nanocarriers. TAKE HOME MESSAGE Much advance is still needed to create a complete and coherent biological picture of endocytosis, but current knowledge already allows individuation of a good number of targetable groups for a predetermined intracellular fate of nanocarriers.
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Affiliation(s)
- Noha M Zaki
- Ain Shams University, Department of Pharmaceutics, Faculty of Pharmacy, Monazamet El Wehda El Afrikia St, El Abbassia, Cairo, Egypt
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21
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Affiliation(s)
- Brad J Marsh
- Institute for Molecular Bioscience, Queensland Bioscience Precinct, The University of Queensland, Brisbane, Queensland, Australia
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22
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Hernández-Martínez S, Román-Martínez U, Martínez-Barnetche J, Garrido E, Rodríguez MH, Lanz-Mendoza H. Induction of DNA synthesis in Anopheles albimanus tissue cultures in response to a Saccharomyces cerevisiae challenge. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2006; 63:147-58. [PMID: 17103404 DOI: 10.1002/arch.20150] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
DNA synthesis was detected by the incorporation of 5-bromo-2' deoxy-uridine (BrdU) in adult Anopheles albimanus organs in culture in response to a challenge with Saccharomyces cerevisiae. Abdomens of mosquitoes inoculated with Roswell Park Memorial Institute medium (RPMI, control) or yeast were cultivated in RPMI plus ConA and BrdU for 5 days. DNA was obtained by phenolic extraction and the incorporated BrdU was quantified by ELISA using anti-BrdU peroxidase-labeled antibodies. Abdomen tissues of mosquitoes inoculated with yeast showed higher DNA synthesis than controls. Organs from untreated mosquitoes cultured in the presence of zymosan also synthesized DNA but at a lower level than tissues from yeast-inoculated mosquitoes. In similar experiments, DNA synthesis was inhibited by the addition of colchicine. DNA synthesis, evidenced by epifluorescence using an anti-BrdU fluorescein-labeled antibody, occurred in fat body, epithelial cells in pleural membranes, and the dorsal vessel. Pleural membranes showed the highest number of labeled cells. These tissues were also labeled with anti-PCNA (proliferating cell nuclear antigen) antibodies, two of which were able to produce polytene chromosomes under yeast stimulation. These results demonstrate that different An. albimanus tissues undergo DNA synthesis in response to foreign particles.
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Affiliation(s)
- S Hernández-Martínez
- Centro de Investigaciones Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Cuernavaca, Morelos, México
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23
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Farah CA, Perreault S, Liazoghli D, Desjardins M, Anton A, Lauzon M, Paiement J, Leclerc N. Tau interacts with Golgi membranes and mediates their association with microtubules. ACTA ACUST UNITED AC 2006; 63:710-24. [PMID: 16960886 DOI: 10.1002/cm.20157] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Tau, a microtubule-associated protein enriched in the axon, is known to stabilize and promote the formation of microtubules during axonal outgrowth. Several studies have reported that tau was associated with membranes. In the present study, we further characterized the interaction of tau with membranous elements by examining its distribution in subfractions enriched in either Golgi or endoplasmic reticulum membranes isolated from rat brain. A subfraction enriched with markers of the medial Golgi compartment, MG160 and mannosidase II, presented a high tau content indicating that tau was associated with these membranes. Electron microscope morphometry confirmed the enrichment of this subfraction with Golgi membranes. Double-immunogold labeling experiments conducted on this subfraction showed the direct association of tau with vesicles labeled with either an antibody directed against MG160 or TGN38. The association of tau with the Golgi membranes was further confirmed by immunoisolating Golgi membranes with an anti-tau antibody. Immunogold labeling confirmed the presence of tau on the Golgi membranes in neurons in vivo. Overexpression of human tau in primary hippocampal neurons induced the formation of large Golgi vesicles that were found in close vicinity to tau-containing microtubules. This suggested that tau could serve as a link between Golgi membranes and microtubules. Such role for tau was demonstrated in an in vitro reconstitution assay. Finally, our results showed that some tau isoforms present in the Golgi subfraction were phosphorylated at the sites recognized by the phosphorylation-dependent antibodies PHF-1 and AT-8.
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Affiliation(s)
- Carole Abi Farah
- Département de Pathologie et Biologie Cellulaire, Université de Montréal, Montréal, Québec, Canada
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24
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Liazoghli D, Perreault S, Micheva KD, Desjardins M, Leclerc N. Fragmentation of the Golgi apparatus induced by the overexpression of wild-type and mutant human tau forms in neurons. THE AMERICAN JOURNAL OF PATHOLOGY 2005; 166:1499-514. [PMID: 15855649 PMCID: PMC1606403 DOI: 10.1016/s0002-9440(10)62366-8] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Tau is a microtubule-associated protein enriched in the axonal compartment. In several neurodegenerative diseases including Alzheimer's disease, hyperphosphorylated tau accumulates in the somatodendritic compartment, self-aggregates, and forms neurofibrillary tangles. A fragmentation of the neuronal Golgi apparatus (GA) was also observed in Alzheimer's disease. In the present study, we examined the effect of overexpressing human tau on the organization of the neuronal GA in rat hippocampal cultures and in JNPL3 mice expressing tau mutant P301L. GA fragmentation was noted in a significantly higher percentage of hippocampal neurons overexpressing wild-type human tau than in control neurons over-expressing green fluorescent protein (GFP) alone. Most importantly, in neurons overexpressing mutant forms of human tau (P301L, V337M, or R406W), the percentage of neurons with a fragmented GA was 10% higher than that of neurons overexpressing wild-type human tau. In JNPL3 mice, a significantly higher percentage of motor neurons presented a fragmented GA compared to control mice. Interestingly, fragmentation of the GA was more frequent in neurons containing an accumulation and aggregation of hyperphosphorylated tau in the cell body than in neurons without these features. In both primary hippocampal neurons and JNPL3 mice, the tau-induced GA fragmentation was not caused by apoptosis. The pre-sent results implicate tau in GA fragmentation and show that this event occurs before the formation of neurofibrillary tangles.
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Affiliation(s)
- Dalinda Liazoghli
- Département de Pathologie et Biologie Cellulaire, Université de Montréal, 2900, Boulevard Edouard-Montpetit, Montréal, Québec, Canada, H3T 1J4
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25
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Abstract
Blood glucose levels are sensed and controlled by the release of hormones from the islets of Langerhans in the pancreas. The beta-cell, the insulin-secreting cell in the islet, can detect subtle increases in circulating glucose levels and a cascade of molecular events spanning the initial depolarization of the beta-cell membrane culminates in exocytosis and optimal insulin secretion. Here we review these processes in the context of pharmacological agents that have been shown to directly interact with any stage of insulin secretion. Drugs that modulate insulin secretion do so by opening the K(ATP) channels, by interacting with cell-surface receptors, by altering second-messenger responses, by disrupting the beta-cell cytoskeletal framework, by influencing the molecular reactions at the stages of transcription and translation of insulin, and/or by perturbing exocytosis of the insulin secretory vesicles. Drugs acting primarily at the K(ATP) channels are the sulfonylureas, the benzoic acid derivatives, the imidazolines, and the quinolines, which are channel openers, and finally diazoxide, which closes these channels. Methylxanthines also work at the cell membrane level by antagonizing the purinergic receptors and thus increase insulin secretion. Other drugs have effects at multiple levels, such as the calcineurin inhibitors and somatostatin. Some drugs used extensively in research, e.g., colchicine, which is used to study vesicular transport, have no effect at the pharmacological doses used in clinical practice. We also briefly discuss those drugs that have been shown to disrupt beta-cell function in a clinical setting but for which there is scant information on their mechanism of action.
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Affiliation(s)
- Máire E Doyle
- Diabetes Section, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224, USA
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26
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Donelan MJ, Morfini G, Julyan R, Sommers S, Hays L, Kajio H, Briaud I, Easom RA, Molkentin JD, Brady ST, Rhodes CJ. Ca2+-dependent dephosphorylation of kinesin heavy chain on beta-granules in pancreatic beta-cells. Implications for regulated beta-granule transport and insulin exocytosis. J Biol Chem 2002; 277:24232-42. [PMID: 11978799 DOI: 10.1074/jbc.m203345200] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The specific biochemical steps required for glucose-regulated insulin exocytosis from beta-cells are not well defined. Elevation of glucose leads to increases in cytosolic [Ca2+]i and biphasic release of insulin from both a readily releasable and a storage pool of beta-granules. The effect of elevated [Ca2+]i on phosphorylation of isolated beta-granule membrane proteins was evaluated, and the phosphorylation of four proteins was found to be altered by [Ca2+]i. One (a 18/20-kDa doublet) was a Ca2+-dependent increase in phosphorylation, and, surprisingly, three others (138, 42, and 36 kDa) were Ca2+-dependent dephosphorylations. The 138-kDa beta-granule phosphoprotein was found to be kinesin heavy chain (KHC). At low levels of [Ca2+]i KHC was phosphorylated by casein kinase 2, but KHC was rapidly dephosphorylated by protein phosphatase 2B beta (PP2Bbeta) as [Ca2+]i increased. Inhibitors of PP2B specifically reduced the second, microtubule-dependent, phase of insulin secretion, suggesting that dephosphorylation of KHC was required for transport of beta-granules from the storage pool to replenish the readily releasable pool of beta-granules. This is distinct from synaptic vesicle exocytosis, because neurotransmitter release from synaptosomes did not require a Ca2+-dependent KHC dephosphorylation. These results suggest a novel mechanism for regulating KHC function and beta-granule transport in beta-cells that is mediated by casein kinase 2 and PP2B. They also implicate a novel regulatory role for PP2B/calcineurin in the control of insulin secretion downstream of a rise in [Ca2+]i.
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Affiliation(s)
- Matthew J Donelan
- Pacific Northwest Research Institute and Department of Pharmacology, University of Washington, Seattle, Washington 98112, USA
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27
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Vischer UM, Barth H, Wollheim CB. Regulated von Willebrand factor secretion is associated with agonist-specific patterns of cytoskeletal remodeling in cultured endothelial cells. Arterioscler Thromb Vasc Biol 2000; 20:883-91. [PMID: 10712417 DOI: 10.1161/01.atv.20.3.883] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
von Willebrand factor (vWF), an adhesive glycoprotein involved in primary hemostasis, is stored and released from endothelial secretory granules called Weibel-Palade bodies. Regulated secretion occurs in reaction either to [Ca(2+)](i)-raising agents (histamine or thrombin) or to cAMP-raising agents (epinephrine, adenosine, or forskolin). We investigated the pattern of release and the cytoskeletal requirements for secretion in response to these 2 classes of agonists. Secretion induced by [Ca(2+)](i)-raising agents involves peripheral and central granules and is inhibited by colchicine-induced microtubule disruption. It is accompanied by Rho-dependent stress fiber formation and cell retraction. Secretion and remodeling occur in the same individual cells. However, secretion is potentiated by cytochalasin E and C3 toxin, indicating that stress fiber formation antagonizes vWF secretion. In contrast, vWF secretion induced by cAMP-raising agents involves the release of only peripheral granules (implying less vWF release on a per cell basis) and is not inhibited by microtubule disruption. cAMP-mediated secretion is accompanied by disruption of stress fibers, strengthening of the cortical actin rim, and preservation of cell-cell contacts. It is unaffected by cytochalasins or C3 toxin. In contrast to [Ca(2+)](i)-raising agents, cAMP-raising agents induce secretion without cell retraction/intercellular gap formation. Thus, they are likely to play a physiological role in the regulation of endothelial vWF secretion and, therefore, of plasma vWF levels.
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Affiliation(s)
- U M Vischer
- Division de Biochimie Clinique, Department of Internal Medicine, Geneva, Switzerland.
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28
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Meng YX, Wilson GW, Avery MC, Varden CH, Balczon R. Suppression of the expression of a pancreatic beta-cell form of the kinesin heavy chain by antisense oligonucleotides inhibits insulin secretion from primary cultures of mouse beta-cells. Endocrinology 1997; 138:1979-87. [PMID: 9112396 DOI: 10.1210/endo.138.5.5139] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Granular/vesicular transport is thought to be supported by microtubule-based force-generating adenosine triphosphatases such as kinesin. Kinesin is a motor molecule that has been well studied in brain and other neuronal tissues. Although vesicular transport is important for pancreatic beta-cell secretory activities, the role of kinesin in beta-cell function has not been investigated. It is hypothesized that kinesin functions as a translocator that associates with both microtubules and insulin-containing granules in beta-cells and transports the secretory granules from deep within the cytoplasm, where insulin is synthesized and processed, to the surface of beta-cells upon secretory stimulation. To test this hypothesis, a mouse beta-cell kinesin heavy chain complementary DNA was cloned and sequenced. Kinesin expression in primary cultures of mouse beta-cells then was selectively suppressed by antimouse beta-cell kinesin heavy chain antisense oligonucleotide treatment. Analysis of insulin secretion determined that the basal level of insulin secretion from the treated cells was decreased by 50%. Furthermore, glucose-stimulated insulin release from treated beta-cells was reduced by almost 70% after suppression of kinesin expression by antisense treatment. The findings from this study provide the first direct evidence that kinesin, a microtubule-based motor protein, plays an important role in insulin secretion.
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Affiliation(s)
- Y X Meng
- Department of Structural and Cellular Biology, University of South Alabama, Mobile 36688, USA
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29
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Rubins HB, Robins SJ, Collins D. The Veterans Affairs High-Density Lipoprotein Intervention Trial: baseline characteristics of normocholesterolemic men with coronary artery disease and low levels of high-density lipoprotein cholesterol. Veterans Affairs Cooperative Studies Program High-Density Lipoprotein Intervention Trial Study Group. Am J Cardiol 1996; 78:572-5. [PMID: 8806347 DOI: 10.1016/s0002-9149(96)00369-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This report describes the baseline characteristics of the 2,531 patients with coronary artery disease enrolled in the Veterans Affairs Cooperative Studies Program High Density Lipoprotein Intervention Trial. The population is characterized by a large percentage of elderly patients, diabetic patients, and patients with the clinical characteristics of the insulin-resistance syndrome.
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Affiliation(s)
- H B Rubins
- Department of Medicine, Minneapolis VA Medical Center, Minnesota 55417, USA
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30
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Cole NB, Sciaky N, Marotta A, Song J, Lippincott-Schwartz J. Golgi dispersal during microtubule disruption: regeneration of Golgi stacks at peripheral endoplasmic reticulum exit sites. Mol Biol Cell 1996; 7:631-50. [PMID: 8730104 PMCID: PMC275914 DOI: 10.1091/mbc.7.4.631] [Citation(s) in RCA: 395] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Microtubule disruption has dramatic effects on the normal centrosomal localization of the Golgi complex, with Golgi elements remaining as competent functional units but undergoing a reversible "fragmentation" and dispersal throughout the cytoplasm. In this study we have analyzed this process using digital fluorescence image processing microscopy combined with biochemical and ultrastructural approaches. After microtubule depolymerization, Golgi membrane components were found to redistribute to a distinct number of peripheral sites that were not randomly distributed, but corresponded to sites of protein exit from the ER. Whereas Golgi enzymes redistributed gradually over several hours to these peripheral sites, ERGIC-53 (a protein which constitutively cycles between the ER and Golgi) redistributed rapidly (within 15 minutes) to these sites after first moving through the ER. Prior to this redistribution, Golgi enzyme processing of proteins exported from the ER was inhibited and only returned to normal levels after Golgi enzymes redistributed to peripheral ER exit sites where Golgi stacks were regenerated. Experiments examining the effects of microtubule disruption on the membrane pathways connecting the ER and Golgi suggested their potential role in the dispersal process. Whereas clustering of peripheral pre-Golgi elements into the centrosomal region failed to occur after microtubule disruption, Golgi-to-ER membrane recycling was only slightly inhibited. Moreover, conditions that impeded Golgi-to-ER recycling completely blocked Golgi fragmentation. Based on these findings we propose that a slow but constitutive flux of Golgi resident proteins through the same ER/Golgi cycling pathways as ERGIC-53 underlies Golgi Dispersal upon microtubule depolymerization. Both ERGIC-53 and Golgi proteins would accumulate at peripheral ER exit sites due to failure of membranes at these sites to cluster into the centrosomal region. Regeneration of Golgi stacks at these peripheral sites would re-establish secretory flow from the ER into the Golgi complex and result in Golgi dispersal.
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Affiliation(s)
- N B Cole
- Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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Mizuno M, Singer SJ. A possible role for stable microtubules in intracellular transport from the endoplasmic reticulum to the Golgi apparatus. J Cell Sci 1994; 107 ( Pt 5):1321-31. [PMID: 7929638 DOI: 10.1242/jcs.107.5.1321] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The intracellular transport of secretory proteins involves at an early stage the formation of vesicles from transitional elements of the endoplasmic reticulum (ER) containing these proteins and the transfer of these vesicles to the cis-face of the Golgi apparatus. We propose that the latter transfer process does not occur by random diffusion, but is instead mediated by tracking along stable microtubules. To test this proposal, we have carried out double immunoelectron microscopic labeling experiments on frozen sections of HepG2 hepatoma cells secreting the protein human serum albumin (HSA). By a cycloheximide treatment protocol, the stage during which the transfer of newly synthesized HSA from the ER to the Golgi apparatus occurs in vivo was determined. Sections of the cells were then double immunolabeled using primary antibodies to HSA and to glu-tubulin, the latter specifically detecting stable microtubules. We observed a significantly high frequency of HSA-containing structures between the ER and the Golgi apparatus with which stable microtubules were closely associated. These results support the proposal that stable microtubules may play a critical role in directing the transfer process from the ER to the Golgi apparatus.
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Affiliation(s)
- M Mizuno
- Department of Biology, University of California at San Diego, La Jolla 92037
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32
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Robin P, Rossignol B, Raymond MN. Are microtubules essential for the secretory process in rat parotid gland? CELL MOTILITY AND THE CYTOSKELETON 1994; 28:34-44. [PMID: 8044848 DOI: 10.1002/cm.970280104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The role of microtubules in the exocrine secretory process is not yet well established, and their disruption by anti-microtubule drugs leads to variable effects on intracellular transit and protein secretion. We investigated the involvement of microtubules in the regulated secretory process of rat parotid glands using microscopic techniques and pulse-chase experiments. We showed that 10 microM colchicine or nocodazole destroys the microtubule network in parotid acinar cells but only weakly reduces the release of newly synthesized proteins. The half-effect was obtained with 0.22 microM colchicine. Moreover, this small reduction was found to be independent of the nature of the drug (colchicine, colcemid, or nocodazole) and of the nature of the stimulation (beta-adrenergic or cholinergic pathways). Using nocodazole, we have been able to determine that the steps affected by the drug are very early events in the secretory pathway. Finally, we showed by kinetic analysis that microtubule disruption slows protein release only moderately but does not reduce the total amount of secreted protein. We conclude from this study that microtubule integrity is not essential for protein secretion in rat parotid gland.
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Affiliation(s)
- P Robin
- Laboratoire de Biochimie des Transports Cellulaires, C.N.R.S., Université Paris XI, Orsay, France
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33
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Rubins HB, Robins SJ, Iwane MK, Boden WE, Elam MB, Fye CL, Gordon DJ, Schaefer EJ, Schectman G, Wittes JT. Rationale and design of the Department of Veterans Affairs High-Density Lipoprotein Cholesterol Intervention Trial (HIT) for secondary prevention of coronary artery disease in men with low high-density lipoprotein cholesterol and desirable low-density lipoprotein cholesterol. Am J Cardiol 1993; 71:45-52. [PMID: 8420235 DOI: 10.1016/0002-9149(93)90708-k] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Although a large body of epidemiologic evidence suggests that low levels of high-density lipoprotein (HDL) cholesterol are strongly associated with an increased risk of coronary artery disease (CAD), no large-scale clinical trials focusing on this association have been reported. This report describes the rationale and design of the Department of Veterans Affairs HDL Intervention Trial (HIT), a multicenter, randomized, controlled clinical trial designed to determine whether lipid therapy reduces the combined incidence of CAD death and nonfatal myocardial infarction in men with established CAD who have low levels of HDL cholesterol with "desirable" levels of low-density lipoprotein (LDL) cholesterol. Twenty-five hundred men with CAD and HDL cholesterol < or = 40 mg/dl, LDL cholesterol < or = 140 mg/dl, and triglycerides < or = 300 mg/dl are being recruited at 20 Department of Veterans Affairs medical centers, randomized to either gemfibrozil or placebo, and followed in a double-blind manner for an average of 6 years. In this population, gemfibrozil is expected to increase HDL cholesterol by 10 to 15%, have a negligible effect on LDL cholesterol, and lower triglycerides by 30 to 40%. Because an estimated 20 to 30% of patients with CAD have a low HDL cholesterol as their primary lipid abnormality, the results of this trial are expected to have far-reaching clinical implications.
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Affiliation(s)
- H B Rubins
- Veterans Administration Medical Center, Minneapolis, Minnesota 55417
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34
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Tooze SA, Flatmark T, Tooze J, Huttner WB. Characterization of the immature secretory granule, an intermediate in granule biogenesis. J Cell Biol 1991; 115:1491-503. [PMID: 1757459 PMCID: PMC2289211 DOI: 10.1083/jcb.115.6.1491] [Citation(s) in RCA: 186] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The events in the biogenesis of secretory granules after the budding of a dense-cored vesicle from the trans-Golgi network (TGN) were investigated in the neuroendocrine cell line PC12, using sulfate-labeled secretogranin II as a marker. The TGN-derived dense-cored vesicles, which we refer to as immature secretory granules, were found to be obligatory organellar intermediates in the biogenesis of the mature secretory granules which accumulate in the cell. Immature secretory granules were converted to mature secretory granules with a half-time of approximately 45 min. This conversion entailed an increase in their size, implying that the maturation of secretory granules includes a fusion event involving immature secretory granules. Pulse-chase labelling of PC12 cells followed by stimulation with high K+, which causes the release of secretogranin II, showed that not only mature, but also immature secretory granules were capable of undergoing regulated exocytosis. The kinetics of secretion of secretogranin II, as well as those of a constitutively secreted heparan sulfate proteoglycan, were reduced by treatment of PC12 cells with nocodazole, suggesting that both secretory granules and constitutive secretory vesicles are transported to the plasma membrane along microtubules. Our results imply that certain membrane proteins, e.g., those involved in the fusion of post-TGN vesicles with the plasma membrane, are sorted upon exit from the TGN, whereas other membrane proteins, e.g., those involved in the interaction of post-TGN vesicles with the cytoskeleton, may not be sorted.
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Affiliation(s)
- S A Tooze
- Cell Biology Programme, European Molecular Biology Laboratory, Heidelberg, Germany
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35
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Pape R, Kissmehl R, Glas-Albrecht R, Plattner H. Effects of anti-microtubule agents on Paramecium cell culture growth. Eur J Protistol 1991. [DOI: 10.1016/s0932-4739(11)80066-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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36
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Somatostatin inhibits insulin secretion by a G-protein-mediated decrease in Ca2+ entry through voltage-dependent Ca2+ channels in the beta cell. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(17)35249-3] [Citation(s) in RCA: 96] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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37
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Veel T, Buanes T, Grotmol T, Engeland E, Raeder MG. Colchicine blocks the effects of secretin on bile duct cell tubulovesicles and plasma membrane geometry and impairs ductular HCO3- secretion in the pig. ACTA PHYSIOLOGICA SCANDINAVICA 1990; 139:603-7. [PMID: 2248039 DOI: 10.1111/j.1748-1716.1990.tb08965.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Secretin causes the bile duct cells to secrete HCO3-. To examine whether the transformation of duct cell ultrastructure that follows secretin stimulation depends on microtubules and is important for ductular HCO3- secretion, we examined the effect of colchicine on ductular HCO3- secretion and on the morphology of cells lining bile ductules of anaesthetized pigs. Colchicine blocked secretin-dependent cytoplasmic clearance of tubulovesicles and prevented expansion of the basolateral plasma membrane in duct cells and reduced the ductular HCO3- secretory response from 132 +/- 25 mumol min-1 to 97 +/- 14 mumol min-1. In contrast, lumicolchicine did not affect secretin-dependent tubulovesicle clearance or plasma membrane geometry or ductular HCO3- secretion. Accordingly, secretin-dependent cytoplasmic clearance of tubulovesicles in bile duct cells appears to depend on microtubules and to be important for ductular HCO3- secretion.
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Affiliation(s)
- T Veel
- Institute for Experimental Medical Research, Ullevaal Hospital, Oslo, Norway
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38
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Veel T, Buanes T, Engeland E, Raeder MG. Colchicine inhibits the effects of secretin on pancreatic duct cell tubulovesicles and HCO3- secretion in the pig. ACTA PHYSIOLOGICA SCANDINAVICA 1990; 138:487-95. [PMID: 2162127 DOI: 10.1111/j.1748-1716.1990.tb08876.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Secretin stimulation clears the cytoplasm of intralobular pancreatic duct cells in pigs of tubulovesicles and causes these cells to secrete HCO3- into the pancreatic juice. To determine whether the clearance of cytoplasmic tubulovesicles involves the microtubule system and is important for initiation of HCO3- secretion, the effect of the microtubule poison colchicine on duct cell morphology and pancreatic HCO3- secretion was measured in anaesthetized pigs. Before colchicine, secretin reduced the density of tubulovesicles in the cytoplasm of pancreatic duct cells from 92 +/- 8 U to 8 +/- 2 U and initiated pancreatic secretion of 176 +/- 21 mumols min-1 HCO3-. After colchicine, secretin failed to lower duct cell tubulovesicle density and caused the secretion of only 77 +/- 14 mumols min-1 HCO3-. By contrast, lumicolchicine, an isomer of colchicine that does not affect microtubules, did not inhibit pancreatic HCO3- secretion. Colchicine did not reduce carbonic anhydrase or Na,K-ATPase activities in in-vitro assays. The clearance of tubulovesicles from the cytoplasm of pancreatic duct cells therefore seems to be microtubule-dependent and important for the pancreatic HCO3- secretion.
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Affiliation(s)
- T Veel
- University of Oslo, Institute for Experimental Medical Research, Norway
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39
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Sterle M, Pipan N. Influence of antimicrotubular drugs on the Golgi apparatus of stomach secretory mucoid cells and small intestine absorptive cells. VIRCHOWS ARCHIV. B, CELL PATHOLOGY INCLUDING MOLECULAR PATHOLOGY 1989; 58:317-22. [PMID: 1970696 DOI: 10.1007/bf02890087] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The effects of vinblastine and colchicine on the Golgi apparatus of stomach surface mucoid and absorptive intestinal cells were compared by cytochemical analysis. The two epithelial cells were chosen because of their different specific functions in the formation of secretory granules, the production of lysosomes and the intensity of membrane traffic in the cytoplasm. For the analysis, adult mice were injected with 1 mg/100 g b.w. of vinblastine and 1 mg/100 g b.w. of colchicine. For the demonstration of cis and trans cisternae of the Golgi apparatus, prolonged osmification, thiamine pyrophosphatase and acid phosphatase activity identification were applied. After treatment with vinblastine or colchicine, polarity of stacks in the Golgi apparatus of surface mucoid cells is preserved although the number of cisternae with thiamine pyrophosphatase or acid phosphatase activity decreases. However, the Golgi apparatus of intestinal absorptive cells completely disintegrates and only a few separated cis or trans cisternae can be identified. The main effect seems to be a reduction of vesicles which can be cytochemically identified as parts of the Golgi apparatus and an accumulation of vesicles which probably originate from budding ER. Communication between the ER and the Golgi apparatus seems to be interrupted.
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Affiliation(s)
- M Sterle
- Institute of Human Biology, Medical Faculty, University Edvard Kardelj, Lipiceva, Yugoslavia
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40
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Stults NL, Fechheimer M, Cummings RD. Relationship between Golgi Architecture and Glycoprotein Biosynthesis and Transport in Chinese Hamster Ovary Cells. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)47204-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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41
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Iida H, Barron WM, Page E. Monensin turns on microtubule-associated translocation of secretory granules in cultured rat atrial myocytes. Circ Res 1988; 62:1159-70. [PMID: 2968191 DOI: 10.1161/01.res.62.6.1159] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We have studied the effect of monensin on microtubule-associated translocation of atrial secretory granules in 5-7-day-old cultures of atrial myocytes from adult rats. Atrial granules and microtubules were localized by immunofluorescent microscopy of myocytes double-labeled with primary antibodies against atrial natriuretic polypeptide (ANP) and alpha-tubulin. In control myocytes, fluorescence due to atrial granules was predominantly localized to the perinuclear region containing the Golgi complex. After exposure for 30 minutes to monensin (0.5-5.0 microM), myocytes transiently contained conspicuous linear arrays of atrial granules associated with cytoplasmic microtubules. Thereafter, ANP fluorescence accumulated in subsarcolemmal foci at the cell periphery, while perinuclear ANP fluorescence faded. The monensin-induced redistribution of atrial granules was observable in both serum-containing and serum-free media and was unaffected by reducing external Ca2+ to low values, by inhibition of sarcoplasmic reticulum Ca2+ release with ryanodine, or by both. The redistribution was prevented by pretreatment with nocodazole, which fragmented microtubules and scattered Golgi complexes and the associated atrial granules throughout the cytoplasm. Radioimmunoassay showed that monensin seemingly decreased the rate of ANP secretion into the medium from 0.15 to 0.11 fmol/(hr.myocyte). These results suggest that monensin turns on microtubule-associated translocation of atrial granules from the perinuclear areas to the cell periphery by modifying the interaction between microtubules and atrial granules. Monensin also promotes movement of atrial granules along the microtubules but does not accelerate the release of ANP.
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Affiliation(s)
- H Iida
- Department of Medicine, University of Chicago, IL 60637
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42
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Niwa J, Minase T, Mori M, Hashi K. Immunohistochemical, electron microscopic, and morphometric studies of human prolactinomas after short-term bromocriptine treatment. SURGICAL NEUROLOGY 1987; 28:339-44. [PMID: 3660204 DOI: 10.1016/0090-3019(87)90055-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Two cases of human prolactinomas after short-term treatment with bromocriptine were studied by means of immunohistochemistry for prolactin, electron microscopy, and morphometry at the ultrastructural level. The results obtained showed an abundance of immunoreactive secretory granules in the tumor cells, a paucity in the electron microscopic images suggesting exocytosis of secretory granules, and no significant changes in the volume density of rough endoplasmic reticulum when compared with untreated (control) tumor cells. These findings strongly suggest that the effects of short-term bromocriptine treatment for lowering serum prolactin levels did not inhibit protein and secretory granule synthesis but rather caused a disturbance in the secretion of prolactin granules. The present morphometrical data suggest the possibility that a reduction in the number of cytoplasmic microtubules might be related to the disturbance of prolactin secretion.
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Affiliation(s)
- J Niwa
- Department of Neurosurgery, Sapporo Medical College, Japan
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43
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Dentler WL, Suprenant KA. Isolation of microtubule-secretory granule complexes from the anglerfish endocrine pancreas. Ann N Y Acad Sci 1986; 466:813-31. [PMID: 3524374 DOI: 10.1111/j.1749-6632.1986.tb38465.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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44
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Boyd AE, Hill RS, Oberwetter JM, Berg M. Calcium dependency and free calcium concentrations during insulin secretion in a hamster beta cell line. J Clin Invest 1986; 77:774-81. [PMID: 3081574 PMCID: PMC423463 DOI: 10.1172/jci112374] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Using a glucose-responsive beta cell line, we tested the hypothesis that the free cytosolic Ca2+ concentration ([Ca2+]i) is the primary signal that couples a stimulus to insulin secretion, and examined the involvement of the extracellular Ca2+ pool in this process. Glucose or depolarization of the beta cell with 40 mM K+ stimulated a monophasic release of insulin directly proportional to the extracellular Ca2+ concentration. 40 mM K+ increased 45Ca2+ uptake and increased [Ca2+]i, which was measured with quin 2, 4.7-fold, from 56 +/- 3 to 238 +/- 17 nM. With high glucose, 45Ca2+ uptake did not increase, and [Ca2+]i was unchanged or fell slightly. There was a striking correlation between inhibitory effects of verapamil, the Ca2+ channel blocker, on insulin secretion and the rise in [Ca2+]i evoked by K+. Higher concentrations of verapamil were required to inhibit glucose- than K+-stimulated insulin secretion (dose giving half-maximal effect of 1.4 X 10(-4) M vs. 6.0 X 10(-7) M). Incubation in Ca2+-free, 1 mM EGTA buffer for 30 min lowered [Ca2+]i to 14 +/- 2 nM, and inhibited acute insulin release to both secretagogues. If high glucose was present in the Ca2+-free period, reintroduction of 2.5 mM Ca2+ in high glucose restored insulin secretion only to the basal rate. However, if low glucose was present during the Ca2+-free period, high glucose and 2.5 mM Ca2+ triggered a full first-phase insulin response. These data suggest that high glucose generates a non-Ca2+ signal that turns over rapidly and provide direct evidence that K+ triggers insulin release by drawing extracellular Ca2+ into the beta cell through verapamil-sensitive Ca2+ channels. However, an increase [Ca2+]i is not the primary signal that evokes glucose-stimulated insulin release in this beta cell line.
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45
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Abstract
One of the central, unresolved problems in our understanding of insulin secretion is the way in which stimulus recognition and its associated metabolic events are translated into the mechanical processes of insulin-storage granule movement and extrusion from the cells by exocytosis. In the present article we have examined the structural organization of the B-cell cytoskeleton in detail and have reviewed how drugs that affect the cytoskeleton alter insulin secretion. Available information about the interactions of tubulin, actin, myosin, and actomyosin with insulin-secretory granules is summarized, and a tentative model is proposed to explain how stimulus-effector system coupling might be achieved.
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46
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Boyd AE, Hill RS, Nelson TY, Oberwetter JM, Berg M. The role of cytosolic calcium in insulin secretion from a hamster beta cell line. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1986; 211:305-16. [PMID: 3300188 DOI: 10.1007/978-1-4684-5314-0_27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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47
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Niwa J, Mori M, Minase T, Hashi K. Immunofluorescence demonstration of tubulin and actin in estrogen-induced rat prolactinoma cells in vitro. Alteration of their distribution after bromocriptine, colchicine and cytochalasin B treatments. Exp Cell Res 1985; 161:517-24. [PMID: 3905419 DOI: 10.1016/0014-4827(85)90106-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Cultured cells in vitro from estrogen-induced rat prolactin-secreting adenomas (prolactinomas) were examined by indirect immunofluorescence microscopy for the distribution of cytoskeletal proteins and alterations of cytoskeleton after treatment with bromocriptine, colchicine and cytochalasin B (CB). After 8 days in culture, prolactinoma cells were well expanded and developed cytoplasmic processes were seen. The cytoplasmic microtubules were observed as fine reticular networks radiating from perinuclear portions toward the cell periphery when decorated with an antibody against tubulin. On the other hand, the actin filaments showed diffuse and spotty distribution when detected with an anti-actin antibody. Contaminated fibroblasts showed a reticular distribution of microtubules and a parallel array of actin cables which corresponds to "stress fibers" throughout the cytoplasm. After treatment with bromocriptine, the reticular distribution of microtubules in prolactinoma cells changed into a coarse and sparse pattern, which was identical with the changes in the distribution of tubulin after treatment with colchicine. On the other hand, distribution of actin was not affected by bromocriptine. Bromocriptine treatment did not alter the distribution of microtubules and actin filaments in fibroblasts, whereas colchicine changed the distribution of microtubules in both prolactinoma cells and fibroblasts. CB treatment changed the localization of actin filaments in both kinds of cells. These in vitro studies indicated bromocriptine would selectively affect the cytoplasmic microtubular system of prolactinoma cells.
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Shiokawa K, Tashiro K, Misumi Y. Association of maternal and newly synthesized ribosomes with membranous noncytoskeletal structures in Xenopus laevis embryonic cells. THE JOURNAL OF EXPERIMENTAL ZOOLOGY 1985; 235:227-36. [PMID: 4056690 DOI: 10.1002/jez.1402350209] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In Xenopus laevis embryos a high concentration of both KCl and 0.5% DOC (sodium deoxycholate) is needed for maximal extraction of ribosomes and polysomes. We studied the nature of the structures that keep ribosomes and polysomes immobilized within the cytoplasm of embryonic cells at cleavage through tailbud stages, using various combinations of a low-salt buffer (20 mM KCl), a high-salt buffer (500 mM KCl), 0.5% DOC, and 0.5% Triton X-100. With a low-salt buffer and 0.5% DOC, but not Triton X-100, 80S ribosomal monomers and polysomes were liberated from the cytoplasmic rapidly sedimenting structures (RSS) to the soluble fraction. With a high-salt buffer (500 mM KCl), ribosomes were solubilized as 60S and 40S subunits together with about one-half of the total polysomes. When cells were homogenized in a low-salt buffer with added inhibitors of the cytoskeleton (cytochalasin B or colchicine), the majority of polysomes but not ribosomes were solubilized. These results provide evidence for the following conclusions. 1) Polysomes are bound to cytoskeletal structures in Xenopus embryos, but ribosomes, both maternal and newly synthesized, are associated with membranous noncytoskeletal structures. 2) The membranous structures consist of two compartments, one high-salt sensitive and the other high-salt resistant. 3) Ribosomes of the high-salt resistant group increase in amount with developmental stage and appear to be the precursor to the ribosomes of the high-salt sensitive group.
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49
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Walker PR, Whitfield JF. Cytoplasmic microtubules are essential for the formation of membrane-bound polyribosomes. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(20)71163-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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50
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