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Armoza-Eilat S, Malis Y, Caspi M, Shomron O, Hirschberg K, Rosin-Arbesfeld R. Title: The C-terminal amphipathic helix of Carboxypeptidase E mediates export from the ER and secretion via lysosomes. J Mol Biol 2023:168171. [PMID: 37285900 DOI: 10.1016/j.jmb.2023.168171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 05/29/2023] [Accepted: 05/30/2023] [Indexed: 06/09/2023]
Abstract
Carboxypeptidase E (CPE), an essential enzyme in the biosynthetic production line of most peptide hormones and neuropeptides, is predominantly expressed in endocrine tissues and in the nervous system. CPE is active in acidic environments where it cleaves the C'-terminal basic residues of peptide precursors to generate their bioactive form. Consequently, this highly conserved enzyme regulates numerous fundamental biological processes. Here, we combined live-cell microscopy and molecular analysis to examine the intracellular distribution and secretion dynamics of fluorescently tagged CPE. We show that, in non-endocrine cells, tagged-CPE is a soluble luminal protein that is efficiently exported from the ER via the Golgi apparatus to lysosomes. The C'-terminal conserved amphipathic helix serves as a lysosomal and secretory granule targeting and a secretion motif. Following secretion, CPE may be reinternalized into the lysosomes of neighboring cells.
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Affiliation(s)
- Shir Armoza-Eilat
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Yehonathan Malis
- Department of Pathology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Michal Caspi
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Olga Shomron
- Department of Pathology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Koret Hirschberg
- Department of Pathology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Rina Rosin-Arbesfeld
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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2
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Riachy L, Ferrand T, Chasserot-Golaz S, Galas L, Alexandre S, Montero-Hadjadje M. Advanced Imaging Approaches to Reveal Molecular Mechanisms Governing Neuroendocrine Secretion. Neuroendocrinology 2023; 113:107-119. [PMID: 34915491 DOI: 10.1159/000521457] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 12/09/2021] [Indexed: 11/19/2022]
Abstract
Identification of the molecular mechanisms governing neuroendocrine secretion and resulting intercellular communication is one of the great challenges of cell biology to better understand organism physiology and neurosecretion disruption-related pathologies such as hypertension, neurodegenerative, or metabolic diseases. To visualize molecule distribution and dynamics at the nanoscale, many imaging approaches have been developed and are still emerging. In this review, we provide an overview of the pioneering studies using transmission electron microscopy, atomic force microscopy, total internal reflection microscopy, and super-resolution microscopy in neuroendocrine cells to visualize molecular mechanisms driving neurosecretion processes, including exocytosis and associated fusion pores, endocytosis and associated recycling vesicles, and protein-protein or protein-lipid interactions. Furthermore, the potential and the challenges of these different advanced imaging approaches for application in the study of neuroendocrine cell biology are discussed, aiming to guide researchers to select the best approach for their specific purpose around the crucial but not yet fully understood neurosecretion process.
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Affiliation(s)
- Lina Riachy
- Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale de Normandie, Normandie University, UNIROUEN, INSERM, U1239, Rouen, France
| | - Thomas Ferrand
- Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale de Normandie, Normandie University, UNIROUEN, INSERM, U1239, Rouen, France
| | - Sylvette Chasserot-Golaz
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Strasbourg University, Strasbourg, France
| | - Ludovic Galas
- Normandie University, UNIROUEN, INSERM, PRIMACEN, Rouen, France
| | - Stéphane Alexandre
- Polymères, Biopolymères, Surfaces Laboratory, CNRS, Normandie University, UNIROUEN, UMR 6270, Rouen, France
| | - Maité Montero-Hadjadje
- Laboratoire de Différenciation et Communication Neuronale et Neuroendocrine, Institut de Recherche et d'Innovation Biomédicale de Normandie, Normandie University, UNIROUEN, INSERM, U1239, Rouen, France
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3
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Alkafaas SS, Abdallah AM, Ghosh S, Loutfy SA, Elkafas SS, Abdel Fattah NF, Hessien M. Insight into the role of clathrin-mediated endocytosis inhibitors in SARS-CoV-2 infection. Rev Med Virol 2023; 33:e2403. [PMID: 36345157 PMCID: PMC9877911 DOI: 10.1002/rmv.2403] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 10/08/2022] [Accepted: 10/10/2022] [Indexed: 11/10/2022]
Abstract
Emergence of SARS-CoV-2 variants warrants sustainable efforts to upgrade both the diagnostic and therapeutic protocols. Understanding the details of cellular and molecular basis of the virus-host cell interaction is essential for developing variant-independent therapeutic options. The internalization of SARS-CoV-2, into lung epithelial cells, is mediated by endocytosis, especially clathrin-mediated endocytosis (CME). Although vaccination is the gold standard strategy against viral infection, selective inhibition of endocytic proteins, complexes, and associated adaptor proteins may present a variant-independent therapeutic strategy. Although clathrin and/or dynamins are the most important proteins involved in CME, other endocytic mechanisms are clathrin and/or dynamin independent and rely on other proteins. Moreover, endocytosis implicates some subcellular structures, like plasma membrane, actin and lysosomes. Also, physiological conditions, such as pH and ion concentrations, represent an additional factor that mediates these events. Accordingly, endocytosis related proteins are potential targets for small molecules that inhibit endocytosis-mediated viral entry. This review summarizes the potential of using small molecules, targeting key proteins, participating in clathrin-dependent and -independent endocytosis, as variant-independent antiviral drugs against SARS-CoV-2 infection. The review takes two approaches. The first outlines the potential role of endocytic inhibitors in preventing endocytosis-mediated viral entry and its mechanism of action, whereas in the second computational analysis was implemented to investigate the selectivity of common inhibitors against endocytic proteins in SARS-CoV-2 endocytosis. The analysis revealed that remdesivir, methyl-β-cyclodextrin, rottlerin, and Bis-T can effectively inhibit clathrin, HMG-CoA reductase, actin, and dynamin I GTPase and are more potent in inhibiting SARS-CoV-2 than chloroquine. CME inhibitors for SARS-CoV-2 infection remain understudied.
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Affiliation(s)
- Samar Sami Alkafaas
- Molecular Cell Biology UniteDivision of BiochemistryDepartment of ChemistryFaculty of ScienceTanta UniversityTantaEgypt
| | - Abanoub Mosaad Abdallah
- Narcotic Research DepartmentNational Center for Social and Criminological Research (NCSCR)GizaEgypt
| | - Soumya Ghosh
- Department of GeneticsFaculty of Natural and Agricultural SciencesUniversity of the Free StateBloemfonteinSouth Africa
| | - Samah A. Loutfy
- Virology and Immunology UnitCancer Biology DepartmentNational Cancer Institute (NCI)Cairo UniversityCairoEgypt
- Nanotechnology Research CenterBritish UniversityCairoEgypt
| | - Sara Samy Elkafas
- Production Engineering and Mechanical Design DepartmentFaculty of EngineeringMenofia UniversityMenofiaEgypt
| | - Nasra F. Abdel Fattah
- Virology and Immunology UnitCancer Biology DepartmentNational Cancer Institute (NCI)Cairo UniversityCairoEgypt
| | - Mohamed Hessien
- Molecular Cell Biology UniteDivision of BiochemistryDepartment of ChemistryFaculty of ScienceTanta UniversityTantaEgypt
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4
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Wu S, Huang Y, Huang X, Dai X. Lipopolysaccharide Accelerates Neuropilin-1 Protein Degradation by Activating the Large GTPase Dynamin-1 in Macrophages. Inflammation 2022; 45:1162-1173. [DOI: 10.1007/s10753-021-01610-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 12/07/2021] [Accepted: 12/08/2021] [Indexed: 12/23/2022]
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5
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Tse A, Lee AK, Takahashi N, Gong A, Kasai H, Tse FW. Strong stimulation triggers full fusion exocytosis and very slow endocytosis of the small dense core granules in carotid glomus cells. J Neurogenet 2018; 32:267-278. [PMID: 30484390 DOI: 10.1080/01677063.2018.1497629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Chemosensory glomus cells of the carotid bodies release transmitters, including ATP and dopamine mainly via the exocytosis of small dense core granules (SDCGs, vesicular diameter of ∼100 nm). Using carbon-fiber amperometry, we showed previously that with a modest uniform elevation in cytosolic Ca2+ concentration ([Ca2+]i of ∼0.5 µM), SDCGs of rat glomus cells predominantly underwent a "kiss-and-run" mode of exocytosis. Here, we examined whether a larger [Ca2+]i rise influenced the mode of exocytosis. Activation of voltage-gated Ca2+ channels by a train of voltage-clamped depolarizations which elevated [Ca2+]i to ∼1.6 μM increased the cell membrane capacitance by ∼2.5%. At 30 s after such a stimulus, only 5% of the added membrane was retrieved. Flash photolysis of caged-Ca2+ (which elevated [Ca2+]i to ∼16 μM) increased cell membrane capacitance by ∼13%, and only ∼30% of the added membrane was retrieved at 30 s after the UV flash. When exocytosis and endocytosis were monitored using the two-photon excitation and extracellular polar tracer (TEP) imaging of FM1-43 fluorescence in conjunction with photolysis of caged Ca2+, almost uniform exocytosis was detected over the cell's entire surface and it was followed by slow endocytosis. Immunocytochemistry showed that the cytoplasmic densities of dynamin I, II and clathrin (key proteins that mediate endocytosis) in glomus cells were less than half of those in adrenal chromaffin cells, suggesting that a lower expression of endocytotic machinery may underlie the slow endocytosis in glomus cells. An analysis of the relative change in the signals from two fluorescent dyes that simultaneously monitored the addition of vesicular volume and plasma membrane surface area, suggested that with an intense stimulus, SDCGs of glomus cells underwent full fusion without any significant "compound" exocytosis. Therefore, during a severe hypoxic challenge, glomus granules undergo full fusion for a more complete release of transmitters.
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Affiliation(s)
- Amy Tse
- a Department of Pharmacology and Neuroscience and Metal Health Institute , University of Alberta , Edmonton , Canada
| | - Andy K Lee
- a Department of Pharmacology and Neuroscience and Metal Health Institute , University of Alberta , Edmonton , Canada
| | - Noriko Takahashi
- b Department of Physiology , Kitasato University School of Medicine , Sagamihara , Japan
| | - Alex Gong
- a Department of Pharmacology and Neuroscience and Metal Health Institute , University of Alberta , Edmonton , Canada
| | - Haruo Kasai
- c Laboratory of Structural Physiology, Center for Disease Biology and Integrative Medicine, Faculty of Medicine , The University of Tokyo , Bunkyo-ku , Japan.,d International Research Center for Neurointelligence (WPI-IRCN), UTIAS, The University of Tokyo , Bunkyo-ku , Japan
| | - Frederick W Tse
- a Department of Pharmacology and Neuroscience and Metal Health Institute , University of Alberta , Edmonton , Canada
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6
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Cellular fluorescein hyperfluorescence is dynamin-dependent and increased by Tetronic 1107 treatment. Int J Biochem Cell Biol 2018; 101:54-63. [PMID: 29800726 DOI: 10.1016/j.biocel.2018.05.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 05/04/2018] [Accepted: 05/21/2018] [Indexed: 11/22/2022]
Abstract
Sodium fluorescein ('fluorescein') staining of the ocular surface is frequently an indicator of compromised ocular health, and increases in the presence of certain contact lens multi-purpose solutions (MPS), a phenomenon known as solution induced corneal staining (SICS). The mechanism(s) underpinning fluorescein hyperfluorescence are uncertain, though may reflect increased cellular uptake of fluorescein by corneal epithelial cells. We have developed an in vitro model to study fluorescein uptake in both 'generic' mammalian cells (murine fibroblasts) and human corneal cells. Fluorescein hyperfluorescence increased after treatment with two MPS associated with clinical corneal fluorescein staining, yet there was no cellular hyperfluorescence for two MPS that do not cause this staining. Increased fluorescein uptake did not correlate with presence of a necrotic or an apoptotic marker (propidium iodide and caspase-3 respectively). Incubation of MPS-treated cells with dynasore (an inhibitor of dynamin, implicated in endocytic pathways) reduced fluorescein uptake irrespective of MPS treatment. The non-ionic surfactant Tetronic 1107 (present in both MPS associated with corneal fluorescein staining) increased uptake of fluorescein for both cell types, whereas an unrelated surfactant (Triton X-100) did not. We conclude that the clinical hyperfluorescence profile observed after exposure to four MPS can be reproduced using a simple model of cellular fluorescein uptake, suggesting this is the biological basis for SICS. Fluorescein entry does not correlate with necrosis or apoptosis, but instead involves a dynamin-dependent active process. Moreover the surfactant Tetronic 1107 appears to be a key MPS constituent triggering increased fluorescein entry, and may be the major factor responsible for SICS.
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7
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Shen F, Gai J, Xing J, Guan J, Fu L, Li Q. Dynasore suppresses proliferation and induces apoptosis of the non-small-cell lung cancer cell line A549. Biochem Biophys Res Commun 2017; 495:1158-1166. [PMID: 29175207 DOI: 10.1016/j.bbrc.2017.11.109] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 11/15/2017] [Accepted: 11/17/2017] [Indexed: 01/09/2023]
Abstract
Lung cancer is the leading cause of cancer death worldwide, and most of all cases are non-small-cell lung cancer. Lung cancer is associated with dysregulation of mitochondrial fusion and fission, and inhibition of the fission regulator Dynamin-related protein 1 (Drp1) reduces proliferation and increases apoptosis of lung cancer cells. Dynasore is a small molecule non-selective inhibitor of the GTPase activity of dynamin 1, dynamin 2, and Drp1 in vivo and in vitro. Here, we investigated the effects of dynasore on the proliferation and apoptosis of A549 lung cancer cells, alone and in combination with the chemotherapeutic drug cisplatin. We found that cisplatin increased mitochondrial fission and dynamin 2 expression, whereas dynasore had the opposite effects. However, both cisplatin and dynasore independently induced mitochondrial oxidative stress, leading to mitochondrial dysfunction, reduced cell proliferation, and enhanced apoptosis. Importantly, dynasore significantly augmented the anti-cancer effects of cisplatin. To the best of our knowledge, this is the first report that dynasore inhibits proliferation and induces apoptosis of lung cancer cells, and enhances the inhibitory effects of cisplatin.
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Affiliation(s)
- Feifei Shen
- Department of Pathology, College of Basic Medical Sciences, China Medical University, Shenyang, China
| | - Junda Gai
- Department of Pathology, College of Basic Medical Sciences, China Medical University, Shenyang, China
| | - Jilin Xing
- Department of Pathology, College of Basic Medical Sciences, China Medical University, Shenyang, China
| | - Jingqian Guan
- Department of Pathology, College of Basic Medical Sciences, China Medical University, Shenyang, China
| | - Lin Fu
- Department of Pathology, College of Basic Medical Sciences, China Medical University, Shenyang, China
| | - Qingchang Li
- Department of Pathology, College of Basic Medical Sciences, China Medical University, Shenyang, China.
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8
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Dynasore Improves Motor Function Recovery via Inhibition of Neuronal Apoptosis and Astrocytic Proliferation after Spinal Cord Injury in Rats. Mol Neurobiol 2016; 54:7471-7482. [PMID: 27822712 DOI: 10.1007/s12035-016-0252-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 10/23/2016] [Indexed: 01/02/2023]
Abstract
Spinal cord injury (SCI) is a common and devastating central nervous system insult which lacks efficient treatment. Our previous experimental findings indicated that dynamin-related protein 1 (Drp1) mediates mitochondrial fission during SCI, and inhibition of Drp1 plays a significant protective effect after SCI in rats. Dynasore inhibits GTPase activity at both the plasma membrane (dynamin 1, 2) and the mitochondria membrane (Drp1). The aim of the present study was to investigate the beneficial effects of dynasore on SCI and its underlying mechanism in a rat model. Sprague-Dawley rats were randomly assigned to sham, SCI, and 1, 10, and 30 mg dynasore groups. The rat model of SCI was established using an established Allen's model. Dynasore was administered via intraperitoneal injection immediately. Results of motor functional test indicated that dynasore ameliorated the motor dysfunction greatly at 3, 7, and 10 days after SCI in rats (P < 0.05). Results of western blot showed that dynasore has remarkably reduced the expressions of Drp1, dynamin 1, and dynamin 2 and, moreover, decreased the Bax, cytochrome C, and active Caspase-3 expressions, but increased the expressions of Bcl-2 at 3 days after SCI (P < 0.05). Notably, the upregulation of proliferating cell nuclear antigen (PCNA) and glial fibrillary acidic protein (GAFP) are inhibited by dynasore at 3 days after SCI (P < 0.05). Results of immunofluorescent double labeling showed that there were less apoptotic neurons and proliferative astrocytes in the dynasore groups compared with SCI group (P < 0.05). Finally, histological assessment via Nissl staining demonstrated that the dynasore groups exhibited a significantly greater number of surviving neurons compared with the SCI group (P < 0.05). This neuroprotective effect was dose-dependent (P < 0.05). To our knowledge, this is the first study to indicate that dynasore significantly enhances motor function which may be by inhibiting the activation of neuronal mitochondrial apoptotic pathway and astrocytic proliferation in rats after SCI.
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Cogoi S, Zorzet S, Shchekotikhin AE, Xodo LE. Potent Apoptotic Response Induced by Chloroacetamidine Anthrathiophenediones in Bladder Cancer Cells. J Med Chem 2015; 58:5476-85. [DOI: 10.1021/acs.jmedchem.5b00409] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Susanna Cogoi
- Department
of Medical and Biological Sciences, University of Udine, P.le Kolbe
4, 33100 Udine, Italy
| | - Sonia Zorzet
- Department
of Life Science, University of Trieste, Via Giorgieri 7-9, 34100 Trieste, Italy
| | | | - Luigi E. Xodo
- Department
of Medical and Biological Sciences, University of Udine, P.le Kolbe
4, 33100 Udine, Italy
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Abstract
The encoding of auditory information with indefatigable precision requires efficient resupply of vesicles at inner hair cell (IHC) ribbon synapses. Otoferlin, a transmembrane protein responsible for deafness in DFNB9 families, has been postulated to act as a calcium sensor for exocytosis as well as to be involved in rapid vesicle replenishment of IHCs. However, the molecular basis of vesicle recycling in IHCs is largely unknown. In the present study, we used high-resolution liquid chromatography coupled with mass spectrometry to copurify otoferlin interaction partners in the mammalian cochlea. We identified multiple subunits of the adaptor protein complex AP-2 (CLAP), an essential component of clathrin-mediated endocytosis, as binding partners of otoferlin in rats and mice. The interaction between otoferlin and AP-2 was confirmed by coimmunoprecipitation. We also found that AP-2 interacts with myosin VI, another otoferlin binding partner important for clathrin-mediated endocytosis (CME). The expression of AP-2 in IHCs was verified by reverse transcription PCR. Confocal microscopy experiments revealed that the expression of AP-2 and its colocalization with otoferlin is confined to mature IHCs. When CME was inhibited by blocking dynamin action, real-time changes in membrane capacitance showed impaired synaptic vesicle replenishment in mature but not immature IHCs. We suggest that an otoferlin-AP-2 interaction drives Ca(2+)- and stimulus-dependent compensating CME in mature IHCs.
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Cogoi S, Shchekotikhin AE, Membrino A, Sinkevich YB, Xodo LE. Guanidino Anthrathiophenediones as G-Quadruplex Binders: Uptake, Intracellular Localization, and Anti-Harvey-ras Gene Activity in Bladder Cancer Cells. J Med Chem 2013; 56:2764-78. [DOI: 10.1021/jm3019063] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Susanna Cogoi
- Department of Medical and Biological
Science, P.le Kolbe 4, School of Medicine, 33100 Udine, Italy
| | - Andrey E. Shchekotikhin
- Gause
Institute of New Antibiotics, Russian Academy of Medical Sciences, B. Pirogovskaya,
11, Moscow 119021, Russia
| | - Alexandro Membrino
- Department of Medical and Biological
Science, P.le Kolbe 4, School of Medicine, 33100 Udine, Italy
| | - Yuri B. Sinkevich
- Mendeleyev University of Chemical Technology, 9 Miusskaya Square, Moscow 125190,
Russia
| | - Luigi E. Xodo
- Department of Medical and Biological
Science, P.le Kolbe 4, School of Medicine, 33100 Udine, Italy
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12
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Bulk-like endocytosis plays an important role in the recycling of insulin granules in pancreatic beta cells. Protein Cell 2012; 3:618-26. [PMID: 22729398 DOI: 10.1007/s13238-012-2938-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2012] [Accepted: 05/10/2012] [Indexed: 10/28/2022] Open
Abstract
Although bulk endocytosis has been found in a number of neuronal and endocrine cells, the molecular mechanism and physiological function of bulk endocytosis remain elusive. In pancreatic beta cells, we have observed bulk-like endocytosis evoked both by flash photolysis and trains of depolarization. Bulk-like endocytosis is a clathrin-independent process that is facilitated by enhanced extracellular Ca(2+) entry and suppressed by the inhibition of dynamin function. Moreover, defects in bulk-like endocytosis are accompanied by hyperinsulinemia in primary beta cells dissociated from diabetic KKAy mice, which suggests that bulk-like endocytosis plays an important role in maintaining the exo-endocytosis balance and beta cell secretory capability.
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13
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Tsai CC, Hung HH, Liu CP, Chen YT, Pan CY. Changes in plasma membrane surface potential of PC12 cells as measured by Kelvin probe force microscopy. PLoS One 2012; 7:e33849. [PMID: 22506008 PMCID: PMC3323603 DOI: 10.1371/journal.pone.0033849] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 02/19/2012] [Indexed: 01/08/2023] Open
Abstract
The plasma membrane of a cell not only works as a physical barrier but also mediates the signal relay between the extracellular milieu and the cell interior. Various stimulants may cause the redistribution of molecules, like lipids, proteins, and polysaccharides, on the plasma membrane and change the surface potential (Φs). In this study, the Φss of PC12 cell plasma membranes were measured by atomic force microscopy in Kelvin probe mode (KPFM). The skewness values of the Φss distribution histogram were found to be mostly negative, and the incorporation of negatively charged phosphatidylserine shifted the average skewness values to positive. After being treated with H2O2, dopamine, or Zn2+, phosphatidylserine was found to be translocated to the membrane outer leaflet and the averaged skewness values were changed to positive values. These results demonstrated that KPFM can be used to monitor cell physiology status in response to various stimulants with high spatial resolution.
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Affiliation(s)
- Chia-Chang Tsai
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
| | - Hui-Hsing Hung
- Institute of Zoology, National Taiwan University, Taipei, Taiwan
| | - Chien-Pang Liu
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
| | - Yit-Tsong Chen
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
- * E-mail: (YTC); (CYP)
| | - Chien-Yuan Pan
- Institute of Zoology, National Taiwan University, Taipei, Taiwan
- Department of Life Science, National Taiwan University, Taipei, Taiwan
- * E-mail: (YTC); (CYP)
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14
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Reduced release probability prevents vesicle depletion and transmission failure at dynamin mutant synapses. Proc Natl Acad Sci U S A 2012; 109:E515-23. [PMID: 22308498 DOI: 10.1073/pnas.1121626109] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Endocytic recycling of synaptic vesicles after exocytosis is critical for nervous system function. At synapses of cultured neurons that lack the two "neuronal" dynamins, dynamin 1 and 3, smaller excitatory postsynaptic currents are observed due to an impairment of the fission reaction of endocytosis that results in an accumulation of arrested clathrin-coated pits and a greatly reduced synaptic vesicle number. Surprisingly, despite a smaller readily releasable vesicle pool and fewer docked vesicles, a strong facilitation, which correlated with lower vesicle release probability, was observed upon action potential stimulation at such synapses. Furthermore, although network activity in mutant cultures was lower, Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) activity was unexpectedly increased, consistent with the previous report of an enhanced state of synapsin 1 phosphorylation at CaMKII-dependent sites in such neurons. These changes were partially reversed by overnight silencing of synaptic activity with tetrodotoxin, a treatment that allows progression of arrested endocytic pits to synaptic vesicles. Facilitation was also counteracted by CaMKII inhibition. These findings reveal a mechanism aimed at preventing synaptic transmission failure due to vesicle depletion when recycling vesicle traffic is backed up by a defect in dynamin-dependent endocytosis and provide new insight into the coupling between endocytosis and exocytosis.
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15
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Rosa JM, Conde M, Nanclares C, Orozco A, Colmena I, de Pascual R, García AG, Gandía L. Paradoxical facilitation of exocytosis by inhibition of L-type calcium channels of bovine chromaffin cells. Biochem Biophys Res Commun 2011; 410:307-11. [PMID: 21663733 DOI: 10.1016/j.bbrc.2011.05.138] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 05/26/2011] [Indexed: 11/24/2022]
Abstract
Ca(2+) entry through the L-subtype (α(1D), Ca(v)1,3) of voltage-dependent calcium channels (VDCCs) seems to selectively regulate the endocytotic response after the application of a single depolarizing pulse to voltage-clamped bovine chromaffin cells. Here we have found that L channel blockade with nifedipine transformed the exocytotic responses elicited by a double-pulse protocol, from depression to facilitation. This apparent paradoxical effect was mimicked by pharmacological interventions that directly block endocytosis namely, dynasore, calmidazolium, GTP-γS and GDP-βS. This reinforces our view that Ca(2+) entry through PQ channels (α(1A); Ca(v)2.1) regulates fast exocytosis while Ca(2+) entry through L channels preferentially controls rapid endocytosis.
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Affiliation(s)
- Juliana M Rosa
- Instituto Teófilo Hernando, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain
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16
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Frequency-dependent modes of synaptic vesicle endocytosis and exocytosis at adult mouse neuromuscular junctions. J Neurosci 2011; 31:1093-105. [PMID: 21248134 DOI: 10.1523/jneurosci.2800-10.2011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
During locomotion, adult rodent lumbar motoneurons fire in high-frequency (80-100 Hz) 1-2 s bursts every several seconds, releasing between 10,000 and 20,000 vesicles per burst. The estimated total vesicle pool size indicates that all vesicles would be used within 30 s; thus, a mechanism for rapid endocytosis and vesicle recycling is necessary to maintain effective transmission and motor behavior. However, whether such rapid recycling exists at mouse neuromuscular junctions (NMJs) or how it is regulated has been unclear. Here, we show that much less FM1-43 dye is lost per stimulus with 100 Hz stimulation than with 10 Hz stimulation even when the same number of vesicles undergo exocytosis. Electrophysiological data using folimycin show this lesser amount of dye loss is caused in part by the rapid reuse of vesicles. We showed previously that a myosin light chain kinase (MLCK)-myosin II pathway was required for effective transmission at 100 Hz. Here, we confirm the activation of MLCK, based on increased nerve terminal phospho-MLC immunostaining, with 100 Hz but not with 10 Hz stimulation. We further demonstrate that activation of MLCK, by increased extracellular Ca(2+), by PKC (protein kinase C) activation, or by a MLCK agonist peptide, reduces the amount of dye lost even with 10 Hz stimulation. MLCK activation at 10 Hz also resulted in more vesicles being rapidly reused. Thus, MLCK activation by 100 Hz stimulation switches the mechanism of vesicle cycling to a rapid-reuse mode and is required to sustain effective transmission in adult mouse NMJs.
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Cabeza JM, Acosta J, Alés E. Dynamics and regulation of endocytotic fission pores: role of calcium and dynamin. Traffic 2010; 11:1579-90. [PMID: 20840456 DOI: 10.1111/j.1600-0854.2010.01120.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Although endocytosis involves the fission pore, a transient structure that produces the scission between vesicle and plasma membranes, the dimensions and dynamics of fission pores remain unclear. Here we report that the pore resistance changes proceed in three distinct phases: an initial phase where the resistance increases at 31.7 ± 2.9 GΩ/second, a slower linear phase with an overall slope of 11.7 ± 1.9 GΩ/second and a final increase in resistance more steeply (1189 ± 136 GΩ/second). The kinetics of these changes was calcium dependent. These sequential stages of the fission pore may be interpreted in terms of pore geometry as changes, first in pore diameter and then in pore length, according to which, before fission, the pore diameter consistently decreased to a value near 4 nm, whereas the pore length ranged between 20 and 300 nm. Dynamin, a mechanochemical GTPase, plays an important role in accelerating the fission event, preferentially in endocytotic vesicles of regular size, by increasing the rates of pore closure during the first and second phases of the fission pore, but hardly affected larger and longer-lived endocytotic events. These results suggest that fission pores are dynamic structures that form thin and long membrane necks regulated by intracellular calcium. Between calcium mediators, dynamin functions as a catalyst to increase the speed of single vesicle endocytosis.
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Affiliation(s)
- José María Cabeza
- Departamento Fisiología Médica y Biofísica, Facultad de Medicina, Universidad de Sevilla, Av. Sánchez Pizjuán 4, 41009 Sevilla, Spain
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Rosa JM, Gandía L, García AG. Permissive role of sphingosine on calcium-dependent endocytosis in chromaffin cells. Pflugers Arch 2010; 460:901-14. [PMID: 20640579 DOI: 10.1007/s00424-010-0861-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Accepted: 06/22/2010] [Indexed: 01/09/2023]
Abstract
Sphingosine has been shown to modulate neurotransmitter release. Because membrane fusion and fission involve lipid metabolism, we asked here whether sphingosine had a role in regulating endocytosis. To explore this hypothesis, we monitored changes of membrane capacitance (Cm) to study the effects of intracellular sphingosine on membrane retrieval after chromaffin cell stimulation with depolarising pulses (DPs). We found that: (1) sphingosine dialysis through the patch-clamp pipette (SpD) using the whole-cell configuration of the patch-clamp technique (WCC) favours the appearance of a pronounced endocytotic response; (2) SpD-elicited endocytosis was Ca(2+)-dependent but Ba(2+) did not substitute Ca(2+); (3) under WCC, such endocytotic response disappeared with repetitive DPs; (4) in cells preincubated with sphingomyelinase to augment endogenous sphingosine synthesis, and then voltage-clamped under the perforated-patch configuration of the patch-clamp technique (PPC), endocytosis decayed little with repeated stimulation; (5) sphingosine-1-phosphate (S1P), a metabolite of sphingosine, had a meagre effect on endocytosis; and (6) neither dynamin inhibitor dynasore nor calmodulin blocker calmidazolium affected the sphingosine elicited endocytosis. We believe this is the first report showing that sphingosine plays a permissive role in activating Ca(2+)-dependent endocytosis during cell depolarisation. This effect requires high subplasmalemmal cytosolic Ca(2+) concentrations and a cytosolic factor(s) that is dialysed with the pipette solution. Independence of dynamin and calmodulin suggests that sphingosine-dependent endocytosis could be a novel, more direct pathway for vesicle recycling under mild depolarisation stimuli.
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Affiliation(s)
- Juliana M Rosa
- Instituto Teófilo Hernando Facultad de Medicina, Universidad Autónoma de Madrid, Arzobispo Morcillo, 4, 28029, Madrid, Spain
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Liu J, Bauer H, Callahan J, Kopecková P, Pan H, Kopecek J. Endocytic uptake of a large array of HPMA copolymers: Elucidation into the dependence on the physicochemical characteristics. J Control Release 2010; 143:71-9. [PMID: 20043962 DOI: 10.1016/j.jconrel.2009.12.022] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2009] [Accepted: 12/19/2009] [Indexed: 01/27/2023]
Abstract
Endocytic uptake and subcellular trafficking of a large array of HPMA (N-(2-hydroxypropyl)methacrylamide) based copolymers possessing positively or negatively charged residues, or hydrophobic groups were evaluated by flow cytometry and living cell confocal microscopy in cultured prostate cancer cells. The degrees of cellular uptake of various copolymer fractions with narrow polydispersities were quantified. The copolymer charge was the predominant physicochemical feature in terms of cellular uptake. Fast and efficient uptake occurred in positively charged copolymers due to non-specific adsorptive endocytosis, whereas slow uptake of negatively charged copolymers was observed. The uptake of copolymers was also molecular weight dependent. The copolymers were internalized into the cells through multiple endocytic pathways: positively charged copolymers robustly engaged clathrin-mediated endocytosis, macropinocytosis and dynamin-dependent endocytosis, while weakly negatively charged copolymers weakly employed these pathways; strongly negatively charged copolymers only mobilized macropinocytosis. HPMA copolymer possessing 4 mol% of moderately hydrophobic functional groups did not show preferential uptake. All copolymers ultimately localized in late endosomes/lysosomes via early endosomes; with varying kinetics among the copolymers. This study indicates that cell entry and subsequent intracellular trafficking of polymeric drug carriers are strongly dependent on the physicochemical characteristics of the nanocarrier, such as charge and molecular weight.
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Affiliation(s)
- Jihua Liu
- Department of Pharmaceutics and Pharmaceutical Chemistry/CCCD, University of Utah, Salt Lake City, UT 84112, USA
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