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Gustafsson JK, Johansson MEV. The role of goblet cells and mucus in intestinal homeostasis. Nat Rev Gastroenterol Hepatol 2022; 19:785-803. [PMID: 36097076 DOI: 10.1038/s41575-022-00675-x] [Citation(s) in RCA: 123] [Impact Index Per Article: 61.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/04/2022] [Indexed: 12/08/2022]
Abstract
The intestinal tract faces numerous challenges that require several layers of defence. The tight epithelium forms a physical barrier that is further protected by a mucus layer, which provides various site-specific protective functions. Mucus is produced by goblet cells, and as a result of single-cell RNA sequencing identifying novel goblet cell subpopulations, our understanding of their various contributions to intestinal homeostasis has improved. Goblet cells not only produce mucus but also are intimately linked to the immune system. Mucus and goblet cell development is tightly regulated during early life and synchronized with microbial colonization. Dysregulation of the developing mucus systems and goblet cells has been associated with infectious and inflammatory conditions and predisposition to chronic disease later in life. Dysfunctional mucus and altered goblet cell profiles are associated with inflammatory conditions in which some mucus system impairments precede inflammation, indicating a role in pathogenesis. In this Review, we present an overview of the current understanding of the role of goblet cells and the mucus layer in maintaining intestinal health during steady-state and how alterations to these systems contribute to inflammatory and infectious disease.
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Affiliation(s)
- Jenny K Gustafsson
- Department of Physiology, Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden
| | - Malin E V Johansson
- Department of Medical Biochemisty and Cell biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden.
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2
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Recent Development of the Molecular and Cellular Mechanisms of Hydrogen Sulfide Gasotransmitter. Antioxidants (Basel) 2022; 11:antiox11091788. [PMID: 36139861 PMCID: PMC9495975 DOI: 10.3390/antiox11091788] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 09/04/2022] [Accepted: 09/06/2022] [Indexed: 11/16/2022] Open
Abstract
Hydrogen sulfide has been recently identified as the third biological gasotransmitter, along with the more well studied nitric oxide (NO) and carbon monoxide (CO). Intensive studies on its potential as a therapeutic agent for cardiovascular, inflammatory, infectious and neuropathological diseases have been undertaken. Here we review the possible direct targets of H2S in mammals. H2S directly interacts with reactive oxygen/nitrogen species and is involved in redox signaling. H2S also reacts with hemeproteins and modulates metal-containing complexes. Once being oxidized, H2S can persulfidate proteins by adding -SSH to the amino acid cysteine. These direct modifications by H2S have significant impact on cell structure and many cellular functions, such as tight junctions, autophagy, apoptosis, vesicle trafficking, cell signaling, epigenetics and inflammasomes. Therefore, we conclude that H2S is involved in many important cellular and physiological processes. Compounds that donate H2S to biological systems can be developed as therapeutics for different diseases.
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3
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More than a simple epithelial layer: multifunctional role of echinoderm coelomic epithelium. Cell Tissue Res 2022; 390:207-227. [PMID: 36083358 DOI: 10.1007/s00441-022-03678-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 08/23/2022] [Indexed: 11/02/2022]
Abstract
In echinoderms, the coelomic epithelium (CE) is reportedly the source of new circulating cells (coelomocytes) as well as the provider of molecular factors such as immunity-related molecules. However, its overall functions have been scarcely studied in detail. In this work, we used an integrated approach based on both microscopy (light and electron) and proteomic analyses to investigate the arm CE in the starfish Marthasterias glacialis during different physiological conditions (i.e., non-regenerating and/or regenerating). Our results show that CE cells share both ultrastructural and proteomic features with circulating coelomocytes (echinoderm immune cells). Additionally, microscopy and proteomic analyses indicate that CE cells are actively involved in protein synthesis and processing, and membrane trafficking processes such as phagocytosis (particularly of myocytes) and massive secretion phenomena. The latter might provide molecules (e.g., immune factors) and fluids for proper arm growth/regrowth. No stem cell marker was identified and no pre-existing stem cell was observed within the CE. Rather, during regeneration, CE cells undergo dedifferentiation and epithelial-mesenchymal transition to deliver progenitor cells for tissue replacement. Overall, our work underlines that echinoderm CE is not a "simple epithelial lining" and that instead it plays multiple functions which span from immunity-related roles as well as being a source of regeneration-competent cells for arm growth/regrowth.
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An Updated View of the Importance of Vesicular Trafficking and Transport and Their Role in Immune-Mediated Diseases: Potential Therapeutic Interventions. MEMBRANES 2022; 12:membranes12060552. [PMID: 35736259 PMCID: PMC9230090 DOI: 10.3390/membranes12060552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 05/21/2022] [Accepted: 05/23/2022] [Indexed: 11/16/2022]
Abstract
Cellular trafficking is the set of processes of distributing different macromolecules by the cell. This process is highly regulated in cells, involving a system of organelles (endomembranous system), among which are a great variety of vesicles that can be secreted from the cell, giving rise to different types of extracellular vesicles (EVs) that can be captured by other cells to modulate their function. The cells of the immune system are especially sensitive to this cellular traffic, producing and releasing different classes of EVs, especially in disease states. There is growing interest in this field due to the therapeutic and translational possibilities it offers. Different ways of taking advantage of the understanding of cell trafficking and EVs are being investigated, and their use as biomarkers or therapeutic targets is being investigated. The objective of this review is to collect the latest results and knowledge in this area with a specific focus on immune-mediated diseases. Although some promising results have been obtained, further knowledge is still needed, at both the basic and translational levels, to understand and modulate cellular traffic and EVs for better clinical management of these patients.
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5
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CMOS Perceptron for Vesicle Fusion Classification. ELECTRONICS 2022. [DOI: 10.3390/electronics11060843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Edge computing (processing data close to its source) is one of the fastest developing areas of modern electronics and hardware information technology. This paper presents the implementation process of an analog CMOS preprocessor for use in a distributed environment for processing medical data close to the source. The task of the circuit is to analyze signals of vesicle fusion, which is the basis of life processes in multicellular organisms. The functionality of the preprocessor is based on a classifier of full and partial fusions. The preprocessor is dedicated to operate in amperometric systems, and the analyzed signals are data from carbon nanotube electrodes. The accuracy of the classifier is at the level of 93.67%. The implementation was performed in the 65 nm CMOS technology with a 0.3 V power supply. The circuit operates in the weak-inversion mode and is dedicated to be powered by thermal cells of the human energy harvesting class. The maximum power consumption of the circuit equals 416 nW, which makes it possible to use it as an implantable chip. The results can be used, among others, in the diagnosis of precancerous conditions.
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6
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Clyburn C, Andresen MC, Ingram SL, Habecker BA. Untangling Peripheral Sympathetic Neurocircuits. Front Cardiovasc Med 2022; 9:842656. [PMID: 35224065 PMCID: PMC8866570 DOI: 10.3389/fcvm.2022.842656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 01/19/2022] [Indexed: 11/13/2022] Open
Abstract
The sympathetic nervous system plays a critical role in regulating many autonomic functions, including cardiac rhythm. The postganglionic neurons in the sympathetic chain ganglia are essential components that relay sympathetic signals to target tissues and disruption of their activity leads to poor health outcomes. Despite this importance, the neurocircuitry within sympathetic ganglia is poorly understood. Canonically, postganglionic sympathetic neurons are thought to simply be activated by monosynaptic inputs from preganglionic cholinergic neurons of the intermediolateral cell columns of the spinal cord. Early electrophysiological studies of sympathetic ganglia where the peripheral nerve trunks were electrically stimulated identified excitatory cholinergic synaptic events in addition to retrograde action potentials, leading some to speculate that excitatory collateral projections are present. However, this seemed unlikely since sympathetic postganglionic neurons were known to synthesize and release norepinephrine and expression of dual neurochemical phenotypes had not been well recognized. In vitro studies clearly established the capacity of cultured sympathetic neurons to express and release acetylcholine and norepinephrine throughout development and even in pathophysiological conditions. Given this insight, we believe that the canonical view of ganglionic transmission needs to be reevaluated and may provide a mechanistic understanding of autonomic imbalance in disease. Further studies likely will require genetic models manipulating neurochemical phenotypes within sympathetic ganglia to resolve the function of cholinergic collateral projections between postganglionic neurons. In this perspective article, we will discuss the evidence for collateral projections in sympathetic ganglia, determine if current laboratory techniques could address these questions, and discuss potential obstacles and caveats.
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Affiliation(s)
- Courtney Clyburn
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, United States
| | - Michael C. Andresen
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, United States
| | - Susan L. Ingram
- Department of Neurological Surgery, Oregon Health and Science University, Portland, OR, United States
| | - Beth A. Habecker
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, United States
- *Correspondence: Beth A. Habecker
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7
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Apartsin E, Venyaminova A, Majoral JP, Caminade AM. Dendriplex-Impregnated Hydrogels With Programmed Release Rate. Front Chem 2022; 9:780608. [PMID: 35071182 PMCID: PMC8766751 DOI: 10.3389/fchem.2021.780608] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 12/13/2021] [Indexed: 12/24/2022] Open
Abstract
Hydrogels are biocompatible matrices for local delivery of nucleic acids; however, functional dopants are required to provide efficient delivery into cells. In particular, dendrimers, known as robust nucleic acid carriers, can be used as dopants. Herein, we report the first example of impregnating neutral hydrogels with siRNA-dendrimer complexes. The surface chemistry of dendrimers allows adjusting the release rate of siRNA-containing complexes. This methodology can bring new materials for biomedical applications.
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Affiliation(s)
- Evgeny Apartsin
- Laboratoire de Chimie de Coordination, CNRS, Toulouse, France.,LCC-CNRS, Université de Toulouse, CNRS, Toulouse, France.,Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk, Russia.,Novosibirsk State University, Novosibirsk, Russia
| | - Alya Venyaminova
- Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk, Russia
| | - Jean-Pierre Majoral
- Laboratoire de Chimie de Coordination, CNRS, Toulouse, France.,LCC-CNRS, Université de Toulouse, CNRS, Toulouse, France
| | - Anne-Marie Caminade
- Laboratoire de Chimie de Coordination, CNRS, Toulouse, France.,LCC-CNRS, Université de Toulouse, CNRS, Toulouse, France
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8
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He X, Ewing AG. Concentration of stimulant regulates initial exocytotic molecular plasticity at single cells. Chem Sci 2022; 13:1815-1822. [PMID: 35282618 PMCID: PMC8826951 DOI: 10.1039/d1sc05278k] [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: 09/23/2021] [Accepted: 01/20/2022] [Indexed: 11/21/2022] Open
Abstract
Activity-induced synaptic plasticity has been intensively studied, but is not yet well understood. We examined the temporal and concentration effects of exocytotic molecular plasticity during and immediately after chemical stimulation (30 s K+ stimulation) via single cell amperometry. Here the first and the second 15 s event periods from individual event traces were compared. Remarkably, we found that the amount of catecholamine release and release dynamics depend on the stimulant concentration. No changes were observed at 10 mM K+ stimulation, but changes observed at 30 and 50 mM (i.e., potentiation, increased number of molecules) were opposite to those at 100 mM (i.e., depression, decreased number of events), revealing changes in exocytotic plasticity based on the concentration of the stimulant solution. These results show that molecular changes initiating exocytotic plasticity can be regulated by the concentration strength of the stimulant solution. These different effects on early plasticity offer a possible link between stimulation intensity and synaptic (or adrenal) plasticity. Amperometric measurement of exocytosis (SCA) and vesicle content (IVIEC) over 15 s intervals reveals plasticity (none, potentiation, or depression), that is regulated by the concentration of stimulant solution (e.g., 30 s 10, 30, 50, and 100 mM K+).![]()
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Affiliation(s)
- Xiulan He
- Department of Chemistry and Molecular Biology, University of Gothenburg 412 96 Gothenburg Sweden
| | - Andrew G Ewing
- Department of Chemistry and Molecular Biology, University of Gothenburg 412 96 Gothenburg Sweden
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9
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Hall D, Foster AS. Practical considerations for feature assignment in high-speed AFM of live cell membranes. Biophys Physicobiol 2022; 19:1-21. [PMID: 35797405 PMCID: PMC9173863 DOI: 10.2142/biophysico.bppb-v19.0016] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 04/13/2022] [Indexed: 12/01/2022] Open
Affiliation(s)
- Damien Hall
- WPI Nano Life Science Institute, Kanazawa University
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10
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Atienza-Manuel A, Castillo-Mancho V, De Renzis S, Culi J, Ruiz-Gómez M. Endocytosis mediated by an atypical CUBAM complex modulates slit diaphragm dynamics in nephrocytes. Development 2021; 148:272711. [PMID: 34738617 PMCID: PMC8710305 DOI: 10.1242/dev.199894] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 10/22/2021] [Indexed: 01/14/2023]
Abstract
The vertebrate endocytic receptor CUBAM, consisting of three cubilin monomers complexed with a single amnionless molecule, plays a major role in protein reabsorption in the renal proximal tubule. Here, we show that Drosophila CUBAM is a tripartite complex composed of Amnionless and two cubilin paralogues, Cubilin and Cubilin2, and that it is required for nephrocyte slit diaphragm (SD) dynamics. Loss of CUBAM-mediated endocytosis induces dramatic morphological changes in nephrocytes and promotes enlarged ingressions of the external membrane and SD mislocalisation. These phenotypes result in part from an imbalance between endocytosis, which is strongly impaired in CUBAM mutants, and exocytosis in these highly active cells. Of note, rescuing receptor-mediated endocytosis by Megalin/LRP2 or Rab5 expression only partially restores SD positioning in CUBAM mutants, suggesting a specific requirement of CUBAM in SD degradation and/or recycling. This finding and the reported expression of CUBAM in podocytes suggest a possible unexpected conserved role for this endocytic receptor in vertebrate SD remodelling. Summary: A genetic study revealing that endocytosis mediated by an atypical CUBAM endocytic receptor, composed of Amnionless and two Cubilin paralogues, regulates slit diaphragm remodelling in Drosophila nephrocytes.
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Affiliation(s)
- Alexandra Atienza-Manuel
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Nicolás Cabrera 1, Cantoblanco 28049, Madrid, Spain
| | - Vicente Castillo-Mancho
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Nicolás Cabrera 1, Cantoblanco 28049, Madrid, Spain
| | - Stefano De Renzis
- European Molecular Biology Laboratory (EMBL), Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Joaquim Culi
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Nicolás Cabrera 1, Cantoblanco 28049, Madrid, Spain
| | - Mar Ruiz-Gómez
- Centro de Biología Molecular Severo Ochoa, CSIC and UAM, Nicolás Cabrera 1, Cantoblanco 28049, Madrid, Spain
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11
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Cifuentes F, Morales MA. Functional Implications of Neurotransmitter Segregation. Front Neural Circuits 2021; 15:738516. [PMID: 34720888 PMCID: PMC8548464 DOI: 10.3389/fncir.2021.738516] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 09/21/2021] [Indexed: 11/13/2022] Open
Abstract
Here, we present and discuss the characteristics and properties of neurotransmitter segregation, a subtype of neurotransmitter cotransmission. We review early evidence of segregation and discuss its properties, such as plasticity, while placing special emphasis on its probable functional implications, either in the central nervous system (CNS) or the autonomic nervous system. Neurotransmitter segregation is a process by which neurons separately route transmitters to independent and distant or to neighboring neuronal processes; it is a plastic phenomenon that changes according to synaptic transmission requirements and is regulated by target-derived signals. Distant neurotransmitter segregation in the CNS has been shown to be related to an autocrine/paracrine function of some neurotransmitters. In retinal amacrine cells, segregation of acetylcholine (ACh) and GABA, and glycine and glutamate to neighboring terminals has been related to the regulation of the firing rate of direction-selective ganglion cells. In the rat superior cervical ganglion, segregation of ACh and GABA to neighboring varicosities shows a heterogeneous regional distribution, which is correlated to a similar regional distribution in transmission strength. We propose that greater segregation of ACh and GABA produces less GABAergic inhibition, strengthening ganglionic transmission. Segregation of ACh and GABA varies in different physiopathological conditions; specifically, segregation increases in acute sympathetic hyperactivity that occurs in cold stress, does not vary in chronic hyperactivity that occurs in hypertension, and rises in early ages of normotensive and hypertensive rats. Given this, we propose that variations in the extent of transmitter segregation may contribute to the alteration of neural activity that occurs in some physiopathological conditions and with age.
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Affiliation(s)
- Fredy Cifuentes
- Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Miguel Angel Morales
- Departamento de Biología Celular y Fisiología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
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12
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Gustafsson JK, Davis JE, Rappai T, McDonald KG, Kulkarni DH, Knoop KA, Hogan SP, Fitzpatrick JAJ, Lencer WI, Newberry RD. Intestinal goblet cells sample and deliver lumenal antigens by regulated endocytic uptake and transcytosis. eLife 2021; 10:e67292. [PMID: 34677124 PMCID: PMC8594945 DOI: 10.7554/elife.67292] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 10/20/2021] [Indexed: 12/12/2022] Open
Abstract
Intestinal goblet cells maintain the protective epithelial barrier through mucus secretion and yet sample lumenal substances for immune processing through formation of goblet cell associated antigen passages (GAPs). The cellular biology of GAPs and how these divergent processes are balanced and regulated by goblet cells remains unknown. Using high-resolution light and electron microscopy, we found that in mice, GAPs were formed by an acetylcholine (ACh)-dependent endocytic event remarkable for delivery of fluid-phase cargo retrograde into the trans-golgi network and across the cell by transcytosis - in addition to the expected transport of fluid-phase cargo by endosomes to multi-vesicular bodies and lysosomes. While ACh also induced goblet cells to secrete mucins, ACh-induced GAP formation and mucin secretion were functionally independent and mediated by different receptors and signaling pathways, enabling goblet cells to differentially regulate these processes to accommodate the dynamically changing demands of the mucosal environment for barrier maintenance and sampling of lumenal substances.
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Affiliation(s)
- Jenny K Gustafsson
- Department of Neuroscience and Physiology, University of GothenburgGothenburgSweden
- Department of Internal Medicine, Washington University School of MedicineSt LouisUnited States
| | - Jazmyne E Davis
- Department of Internal Medicine, Washington University School of MedicineSt LouisUnited States
| | - Tracy Rappai
- Center for Cellular Imaging, Washington University School of MedicineSt LouisUnited States
| | - Keely G McDonald
- Department of Internal Medicine, Washington University School of MedicineSt LouisUnited States
| | - Devesha H Kulkarni
- Department of Internal Medicine, Washington University School of MedicineSt LouisUnited States
| | - Kathryn A Knoop
- Department of Internal Medicine, Washington University School of MedicineSt LouisUnited States
| | - Simon P Hogan
- Mary H. Weiser Food Allergy Center, University of Michigan School of Medicine,Ann ArborUnited States
| | - James AJ Fitzpatrick
- Center for Cellular Imaging, Washington University School of MedicineSt LouisUnited States
- Department of Cell Biology &Physiology, Washington University School of MedicineSt LouisUnited States
- Department of Neuroscience, Washington University School of MedicineSt LouisUnited States
- Department of Biomedical Engineering, Washington University in St. LouisSt. LouisUnited States
| | - Wayne I Lencer
- Department of Pediatrics, Harvard Medical SchoolBostonUnited States
- Division of Gastroenterology, Nutrition and Hepatology, Boston Children’s HospitalBostonUnited States
- Harvard Digestive Disease Center, Harvard Medical SchoolBostonUnited States
| | - Rodney D Newberry
- Department of Internal Medicine, Washington University School of MedicineSt LouisUnited States
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13
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Limits of temperature adaptation and thermopreferendum. Cell Biosci 2021; 11:69. [PMID: 33823918 PMCID: PMC8025563 DOI: 10.1186/s13578-021-00574-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 03/18/2021] [Indexed: 11/10/2022] Open
Abstract
Background Managing the limits of temperature adaptation is relevant both in medicine and in biotechnology. There are numerous scattered publications on the identification of the temperature limits of existence for various organisms and using different methods. Dmitry Petrovich Kharakoz gave a general explanation for many of these experimental results. The hypothesis implied that each cycle of synaptic exocytosis includes reversible phase transitions of lipids of the presynaptic membrane due to the entry and subsequent removal of calcium ions from the synaptic terminal. The correspondence of the times of phase transitions has previously been experimentally shown on isolated lipids in vitro. In order to test the hypothesis of D.P. Kharakoz in vivo, we investigated the influence of the temperature of long-term acclimatization on the temperature of heat and cold shock, as well as on the kinetics of temperature adaptation in zebrafish. Testing the hypothesis included a comparison of our experimental results with the results of other authors obtained on various models from invertebrates to humans. Results The viability polygon for Danio rerio was determined by the minimum temperature of cold shock (about 6 °C), maximum temperature of heat shock (about 43 °C), and thermopreferendum temperature (about 27 °C). The ratio of the temperature range of cold shock to the temperature range of heat shock was about 1.3. These parameters obtained for Danio rerio describe with good accuracy those for the planarian Girardia tigrina, the ground squirrel Sermophilus undulatus, and for Homo sapiens. Conclusions The experimental values of the temperatures of cold shock and heat shock and the temperature of the thermal preferendum correspond to the temperatures of phase transitions of the lipid-protein composition of the synaptic membrane between the liquid and solid states. The viability range for zebrafish coincides with the temperature range, over which enzymes function effectively and also coincides with the viability polygons for the vast majority of organisms. The boundaries of the viability polygon are characteristic biological constants. The viability polygon of a particular organism is determined not only by the genome, but also by the physicochemical properties of lipids that make up the membrane structures of synaptic endings. The limits of temperature adaptation of any biological species are determined by the temperature range of the functioning of its nervous system.
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14
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Xing J, Zhang L, Duan Z, Lin J. Coordination of Phospholipid-Based Signaling and Membrane Trafficking in Plant Immunity. TRENDS IN PLANT SCIENCE 2021; 26:407-420. [PMID: 33309101 DOI: 10.1016/j.tplants.2020.11.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 11/12/2020] [Accepted: 11/16/2020] [Indexed: 05/26/2023]
Abstract
In plants, defense-associated signal transduction involves key membrane-related processes, such as phospholipid-based signaling and membrane trafficking. Coordination of these processes occurs in the lipid bilayer of plasma membrane (PM) and luminal/extracellular membranes. Deciphering the spatiotemporal organization of phospholipids and lipid-protein interactions provides crucial information on the mechanisms that link phospholipid-based signaling and membrane trafficking in plant immunity. In this review, we summarize recent advances in our understanding of these connections, including deployment of key enzymes and molecules in phospholipid pathways, and roles of lipid diversity in membrane trafficking. We highlight the mechanisms that mediate feedback between phospholipid-based signaling and membrane trafficking to regulate plant immunity, including their novel roles in balancing endocytosis and exocytosis.
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Affiliation(s)
- Jingjing Xing
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Liang Zhang
- College of Life Science, Henan Normal University, Xinxiang 453007, China
| | - Zhikun Duan
- State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Jinxing Lin
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing 100083, China; College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China; Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
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15
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Brill SE, Maraslioglu A, Kurz C, Kramer F, Fuhr MF, Singh A, Friauf E. Glycinergic Transmission in the Presence and Absence of Functional GlyT2: Lessons From the Auditory Brainstem. Front Synaptic Neurosci 2021; 12:560008. [PMID: 33633558 PMCID: PMC7900164 DOI: 10.3389/fnsyn.2020.560008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 12/01/2020] [Indexed: 12/20/2022] Open
Abstract
Synaptic transmission is controlled by re-uptake systems that reduce transmitter concentrations in the synaptic cleft and recycle the transmitter into presynaptic terminals. The re-uptake systems are thought to ensure cytosolic concentrations in the terminals that are sufficient for reloading empty synaptic vesicles (SVs). Genetic deletion of glycine transporter 2 (GlyT2) results in severely disrupted inhibitory neurotransmission and ultimately to death. Here we investigated the role of GlyT2 at inhibitory glycinergic synapses in the mammalian auditory brainstem. These synapses are tuned for resilience, reliability, and precision, even during sustained high-frequency stimulation when endocytosis and refilling of SVs probably contribute substantially to efficient replenishment of the readily releasable pool (RRP). Such robust synapses are formed between MNTB and LSO neurons (medial nucleus of the trapezoid body, lateral superior olive). By means of patch-clamp recordings, we assessed the synaptic performance in controls, in GlyT2 knockout mice (KOs), and upon acute pharmacological GlyT2 blockade. Via computational modeling, we calculated the reoccupation rate of empty release sites and RRP replenishment kinetics during 60-s challenge and 60-s recovery periods. Control MNTB-LSO inputs maintained high fidelity neurotransmission at 50 Hz for 60 s and recovered very efficiently from synaptic depression. During 'marathon-experiments' (30,600 stimuli in 20 min), RRP replenishment accumulated to 1,260-fold. In contrast, KO inputs featured severe impairments. For example, the input number was reduced to ~1 (vs. ~4 in controls), implying massive functional degeneration of the MNTB-LSO microcircuit and a role of GlyT2 during synapse maturation. Surprisingly, neurotransmission did not collapse completely in KOs as inputs still replenished their small RRP 80-fold upon 50 Hz | 60 s challenge. However, they totally failed to do so for extended periods. Upon acute pharmacological GlyT2 inactivation, synaptic performance remained robust, in stark contrast to KOs. RRP replenishment was 865-fold in marathon-experiments, only ~1/3 lower than in controls. Collectively, our empirical and modeling results demonstrate that GlyT2 re-uptake activity is not the dominant factor in the SV recycling pathway that imparts indefatigability to MNTB-LSO synapses. We postulate that additional glycine sources, possibly the antiporter Asc-1, contribute to RRP replenishment at these high-fidelity brainstem synapses.
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Affiliation(s)
- Sina E Brill
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Ayse Maraslioglu
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Catharina Kurz
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Florian Kramer
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Martin F Fuhr
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Abhyudai Singh
- Electrical & Computer Engineering, University of Delaware, Newark, DE, United States
| | - Eckhard Friauf
- Animal Physiology Group, Department of Biology, University of Kaiserslautern, Kaiserslautern, Germany
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16
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Veerana M, Mitra S, Ki S, Kim S, Choi E, Lee T, Park G. Plasma-mediated enhancement of enzyme secretion in Aspergillus oryzae. Microb Biotechnol 2021; 14:262-276. [PMID: 33151631 PMCID: PMC7888467 DOI: 10.1111/1751-7915.13696] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 09/08/2020] [Accepted: 10/19/2020] [Indexed: 02/06/2023] Open
Abstract
Technical bottlenecks in protein production and secretion often limit the efficient and robust industrial use of microbial enzymes. The potential of non-thermal atmospheric pressure plasma to overcome these technical barriers was examined. Spores of the fermenting fungus Aspergillus oryzae (A. oryzae) were submerged in potato dextrose broth (PDB) (5 × 106 per ml) and treated with micro dielectric barrier discharge plasma at an input voltage of 1.2 kV and current of 50 to 63 mA using nitrogen as the feed gas. The specific activity of α-amylase in the broth was increased by 7.4 to 9.3% after 24 and 48 h of plasma treatment. Long-lived species, such as NO2 - and NO3 - , generated in PDB after plasma treatment may have contributed to the elevated secretion of α-amylase. Observations after 24 h of plasma treatment also included increased accumulation of vesicles at the hyphal tip, hyphal membrane depolarization and higher intracellular Ca2+ levels. These results suggest that long-lived nitrogen species generated in PDB after plasma treatment can enhance the secretion of α-amylase from fungal hyphae by depolarizing the cell membrane and activating Ca2+ influx into hyphal cells, eventually leading to the accumulation of secretory vesicles near the hyphal tips.
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Affiliation(s)
- Mayura Veerana
- Department of Plasma Bioscience and DisplayKwangwoon UniversitySeoul01897Korea
| | - Sarmistha Mitra
- Department of Plasma Bioscience and DisplayKwangwoon UniversitySeoul01897Korea
| | - Se‐Hoon Ki
- Department of Electrical and Biological PhysicsKwangwoon UniversitySeoul01897Korea
| | - Soo‐Min Kim
- Department of Chemical EngineeringKwangwoon UniversitySeoul01897Korea
| | - Eun‐Ha Choi
- Department of Plasma Bioscience and DisplayKwangwoon UniversitySeoul01897Korea
- Department of Electrical and Biological PhysicsKwangwoon UniversitySeoul01897Korea
| | - Taek Lee
- Department of Chemical EngineeringKwangwoon UniversitySeoul01897Korea
| | - Gyungsoon Park
- Department of Plasma Bioscience and DisplayKwangwoon UniversitySeoul01897Korea
- Department of Electrical and Biological PhysicsKwangwoon UniversitySeoul01897Korea
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17
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Guille-Collignon M, Lemaître F. Overview and outlook of the strategies devoted to electrofluorescence surveys: Application to single cell secretion analysis. Trends Analyt Chem 2020. [DOI: 10.1016/j.trac.2020.116055] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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18
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Xu X, Cao W, Sun W, Wang Z, Chen H, Zheng Z, Yang X. Knockdown Of CCDC132 Attenuates Gastric Cancer Cells Proliferation And Tumorigenesis By Facilitating DNA Damage Signaling. Cancer Manag Res 2019; 11:9585-9597. [PMID: 31814760 PMCID: PMC6858810 DOI: 10.2147/cmar.s215631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 10/15/2019] [Indexed: 11/23/2022] Open
Abstract
Background Aberrant endocytic recycling has fundamental functions on plasma membrane component turnover. Recent studies have identified an uncharacterized protein, CCDC132, in the endosome-associated recycling protein complex. Besides, our preliminary data first showed that CCDC132 was elevated in malignant neoplasms, especially in esophagus/stomach cancers. However, the functions and the underlying mechanisms of CCDC132 in gastric cancer (GC) biology remain unclear. Methods The CCDC132 mRNA expression in 4 GC cell lines and normal gastric epithelial cell lines was detected by qRT-PCR. Then, CCDC132 was downregulated in AGS and MGC-803 cells by lentivirus-induced RNA interfere, and cell viability assay, clone formation assay and apoptosis assay were carried out. The mechanism of CCDC132 on cell proliferation and apoptosis activation was explored using PathScan® Stress, apoptosis signaling arrays and Western blot. We further investigated the pro-oncogenesis of CCDC132 in vivo. Meanwhile, immunohistochemistry was utilized to analyze the association between CCDC132 expression and clinicopathological features and prognosis. Finally, the correlation between CCDC132 and p53 was analyzed by Spearman’s rank correlation analysis. Results In this study, knockdown of CCDC132 significantly decreased cell proliferation and clone formation ability and facilitated apoptosis, and increased phosphorylation of p53 and Chk2 and protein levels of γ-H2AX, 53BP1, cleaved Caspase 3 and cleaved PARP. Additionally, knockdown of CCDC132 attenuated tumorigenesis and tumor growth of MGC-803 cell xenografts. CCDC132 expression was significantly higher in GC tissues compared with that in adjacent normal tissues and was positively correlated with nodal metastasis and TNM stage and negatively associated with prognosis. The survival rate of CCDC132 positive patients was lower than that of CCDC132-negative patients. Furthermore, CCDC132 expression was negatively related to p53. Conclusion This study unravels that knockdown of CCDC132 attenuates GC cell proliferation and tumorigenesis by facilitating DNA damage signaling, indicating that CCDC132 may serve as a potential target for GC therapy.
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Affiliation(s)
- Xiaowu Xu
- Department of General Surgery, The Second Affiliated Hospital and Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325027, People's Republic of China
| | - Weilang Cao
- Department of General Surgery, The Second Affiliated Hospital and Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325027, People's Republic of China
| | - Wei Sun
- Department of Pharmacy, The Second Affiliated Hospital and Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325027, People's Republic of China
| | - Zhaohong Wang
- Department of General Surgery, The Second Affiliated Hospital and Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325027, People's Republic of China
| | - Hui Chen
- Department of General Surgery, The Second Affiliated Hospital and Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325027, People's Republic of China
| | - Zhiqiang Zheng
- Department of General Surgery, The Second Affiliated Hospital and Children's Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325027, People's Republic of China
| | - Xiaomin Yang
- Department of Pathology, Wenzhou People's Hospital, Wenzhou, Zhejiang 325000, People's Republic of China
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19
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Zhang L, Xing J, Lin J. At the intersection of exocytosis and endocytosis in plants. THE NEW PHYTOLOGIST 2019; 224:1479-1489. [PMID: 31230354 DOI: 10.1111/nph.16018] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 06/03/2019] [Indexed: 05/18/2023]
Abstract
Vesicle exocytosis and endocytosis control the activities and turnover of plasma membrane proteins required for signaling triggering or attenuating at the cell surface. In recent years, the diverse exocytic and endocytic trafficking pathways have been uncovered in plants. The balance between conventional and unconventional protein secretion provides an efficient strategy to respond to stress conditions. Similarly, clathrin-dependent and -independent endocytosis cooperatively regulate the dynamics of membrane proteins in response to environmental cues. In fact, many aspects of plant growth and development, such as tip growth, immune response, and protein polarity establishment, involve the tight deployment of exo-endocytic trafficking. However, our understanding of their intersection is limited. Here, we discuss recent advances in the molecular factors coupling plant exo-endocytic trafficking and the biological significance of balance between exocytosis and endocytosis in plants.
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Affiliation(s)
- Liang Zhang
- College of Life Science, Henan Normal University, Xinxiang, 453007, China
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Jingjing Xing
- Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- Key Laboratory of Plant Stress Biology, School of Life Sciences, Henan University, Kaifeng, 457001, China
| | - Jinxing Lin
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing, 100083, China
- College of Biological Sciences & Biotechnology, Beijing Forestry University, Beijing, 100083, China
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20
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Liu Y, Huo Y, Yao L, Xu Y, Meng F, Li H, Sun K, Zhou G, Kohane DS, Tao K. Transcytosis of Nanomedicine for Tumor Penetration. NANO LETTERS 2019; 19:8010-8020. [PMID: 31639306 DOI: 10.1021/acs.nanolett.9b03211] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The diffusion of nanomedicines used to treat tumors is severely hindered by the microenvironment, which is a challenge that has emerged as a bottleneck for the effective outcome of nanotherapies. Classical strategies for enhancing tumor penetration rely on passive movement in the extracellular matrix (ECM). Here, we demonstrate that nanomedicine also penetrates tumor lesions via an active trans-cell transportation process. This process was discovered by directly observing the movement of nanoparticles between cells, evaluating the intracellular trafficking pathway of nanoparticles via Rab protein labeling, comparing endocytosis-exocytosis between nanoparticles administered with inhibitors, and correlating the transcytosis process with the micro-CT distribution of nanomedicines. We also demonstrated that enhanced tumor penetration promotes the therapeutic efficacy of a photodynamic therapeutic nanomedicine. Our research thus suggests that transcytosis could be an important positive factor for designing cancer nanomedicines.
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Affiliation(s)
- Yan Liu
- State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering , Shanghai Jiao Tong University , Shanghai 200240 , P.R. China
| | - Yingying Huo
- Department of Plastic and Reconstructive Surgery , Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai 200235 , P.R. China
| | - Lin Yao
- Research Institute of Plastic Surgery , Wei Fang Medical College , Weifang , Shandong 261042 , P.R. China
| | - Yawen Xu
- Department of Plastic and Reconstructive Surgery , Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai 200235 , P.R. China
| | - Fanqiang Meng
- State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering , Shanghai Jiao Tong University , Shanghai 200240 , P.R. China
| | - Haifeng Li
- State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering , Shanghai Jiao Tong University , Shanghai 200240 , P.R. China
| | - Kang Sun
- State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering , Shanghai Jiao Tong University , Shanghai 200240 , P.R. China
| | - Guangdong Zhou
- Department of Plastic and Reconstructive Surgery , Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai 200235 , P.R. China
- Research Institute of Plastic Surgery , Wei Fang Medical College , Weifang , Shandong 261042 , P.R. China
| | - Daniel S Kohane
- Laboratory for Biomaterials and Drug Delivery, Department of Anesthesiology , Boston Children's Hospital, Harvard Medical School , Boston 02115 , Massachusetts United States
| | - Ke Tao
- State Key Lab of Metal Matrix Composites, School of Materials Science and Engineering , Shanghai Jiao Tong University , Shanghai 200240 , P.R. China
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21
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Zeng F, Wunderer J, Salvenmoser W, Hess MW, Ladurner P, Rothbächer U. Papillae revisited and the nature of the adhesive secreting collocytes. Dev Biol 2019; 448:183-198. [DOI: 10.1016/j.ydbio.2018.11.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 11/17/2018] [Accepted: 11/20/2018] [Indexed: 11/26/2022]
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22
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Xie B, Nguyen PM, Idevall-Hagren O. Feedback regulation of insulin secretion by extended synaptotagmin-1. FASEB J 2018; 33:4716-4728. [PMID: 30589572 DOI: 10.1096/fj.201801878r] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Endoplasmic reticulum (ER)-plasma membrane (PM) contacts are dynamic structures with important roles in the regulation of calcium (Ca2+) and lipid homeostasis. The extended synaptotagmins (E-Syts) are ER-localized lipid transport proteins that interact with PM phosphatidylinositol 4,5-bisphosphate in a Ca2+-dependent manner. E-Syts bidirectionally transfer glycerolipids, including diacylglycerol (DAG), between the 2 juxtaposed membranes, but the biologic significance of this transport is still unclear. Using insulin-secreting cells and live-cell imaging, we now show that Ca2+-triggered exocytosis of insulin granules is followed, in sequence, by PM DAG formation and E-Syt1 recruitment. E-Syt1 counteracted the depolarization-induced DAG formation through a mechanism that required both voltage-dependent Ca2+ influx and Ca2+ release from the ER. E-Syt1 knockdown resulted in prolonged accumulation of DAG in the PM, resulting in increased glucose-stimulated insulin secretion. We conclude that Ca2+-triggered exocytosis is temporally coupled to Ca2+-triggered E-Syt1 PM recruitment and removal of DAG to negatively regulate the same process.-Xie, B., Nguyen, P. M., Idevall-Hagren, O. Feedback regulation of insulin secretion by extended synaptotagmin-1.
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Affiliation(s)
- Beichen Xie
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Phuoc My Nguyen
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
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23
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Tarasova EO, Gaydukov AE, Balezina OP. Calcineurin and Its Role in Synaptic Transmission. BIOCHEMISTRY (MOSCOW) 2018; 83:674-689. [PMID: 30195324 DOI: 10.1134/s0006297918060056] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Calcineurin (CaN) is a serine/threonine phosphatase widely expressed in different cell types and structures including neurons and synapses. The most studied role of CaN is its involvement in the functioning of postsynaptic structures of central synapses. The role of CaN in the presynaptic structures of central and peripheral synapses is less understood, although it has generated a considerable interest and is a subject of a growing number of studies. The regulatory role of CaN in synaptic vesicle endocytosis in the synapse terminals is actively studied. In recent years, new targets of CaN have been identified and its role in the regulation of enzymes and neurotransmitter secretion in peripheral neuromuscular junctions has been revealed. CaN is the only phosphatase that requires calcium and calmodulin for activation. In this review, we present details of CaN molecular structure and give a detailed description of possible mechanisms of CaN activation involving calcium, enzymes, and endogenous and exogenous inhibitors. Known and newly discovered CaN targets at pre- and postsynaptic levels are described. CaN activity in synaptic structures is discussed in terms of functional involvement of this phosphatase in synaptic transmission and neurotransmitter release.
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Affiliation(s)
- E O Tarasova
- Lomonosov Moscow State University, Faculty of Biology, Moscow, 119991, Russia
| | - A E Gaydukov
- Lomonosov Moscow State University, Faculty of Biology, Moscow, 119991, Russia. .,Pirogov Russian National Research Medical University, Moscow, 117997, Russia
| | - O P Balezina
- Lomonosov Moscow State University, Faculty of Biology, Moscow, 119991, Russia
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24
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The remembrance of the things past: Conserved signalling pathways link protozoa to mammalian nervous system. Cell Calcium 2018; 73:25-39. [DOI: 10.1016/j.ceca.2018.04.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 04/01/2018] [Accepted: 04/01/2018] [Indexed: 12/13/2022]
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25
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Lou X. Sensing Exocytosis and Triggering Endocytosis at Synapses: Synaptic Vesicle Exocytosis-Endocytosis Coupling. Front Cell Neurosci 2018; 12:66. [PMID: 29593500 PMCID: PMC5861208 DOI: 10.3389/fncel.2018.00066] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 02/26/2018] [Indexed: 12/29/2022] Open
Abstract
The intact synaptic structure is critical for information processing in neural circuits. During synaptic transmission, rapid vesicle exocytosis increases the size of never terminals and endocytosis counteracts the increase. Accumulating evidence suggests that SV exocytosis and endocytosis are tightly connected in time and space during SV recycling, and this process is essential for synaptic function and structural stability. Research in the past has illustrated the molecular details of synaptic vesicle (SV) exocytosis and endocytosis; however, the mechanisms that timely connect these two fundamental events are poorly understood at central synapses. Here we discuss recent progress in SV recycling and summarize several emerging mechanisms by which synapses can “sense” the occurrence of exocytosis and timely initiate compensatory endocytosis. They include Ca2+ sensing, SV proteins sensing, and local membrane stress sensing. In addition, the spatial organization of endocytic zones adjacent to active zones provides a structural basis for efficient coupling between SV exocytosis and endocytosis. Through linking different endocytosis pathways with SV fusion, these mechanisms ensure necessary plasticity and robustness of nerve terminals to meet diverse physiological needs.
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Affiliation(s)
- Xuelin Lou
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, United States
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26
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Wen X, Saltzgaber GW, Thoreson WB. Kiss-and-Run Is a Significant Contributor to Synaptic Exocytosis and Endocytosis in Photoreceptors. Front Cell Neurosci 2017; 11:286. [PMID: 28979188 PMCID: PMC5611439 DOI: 10.3389/fncel.2017.00286] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 09/01/2017] [Indexed: 11/13/2022] Open
Abstract
Accompanying sustained release in darkness, rod and cone photoreceptors exhibit rapid endocytosis of synaptic vesicles. Membrane capacitance measurements indicated that rapid endocytosis retrieves at least 70% of the exocytotic membrane increase. One mechanism for rapid endocytosis is kiss-and-run fusion where vesicles briefly contact the plasma membrane through a small fusion pore. Release can also occur by full-collapse in which vesicles merge completely with the plasma membrane. We assessed relative contributions of full-collapse and kiss-and-run in salamander photoreceptors using optical techniques to measure endocytosis and exocytosis of large vs. small dye molecules. Incubation with small dyes (SR101, 1 nm; 3-kDa dextran-conjugated Texas Red, 2.3 nm) loaded rod and cone synaptic terminals much more readily than larger dyes (10-kDa Texas Red, 4.6 nm; 10-kDa pHrodo, 4.6 nm; 70-kDa Texas Red, 12 nm) consistent with significant uptake through 2.3–4.6 nm fusion pores. By using total internal reflection fluorescence microscopy (TIRFM) to image individual vesicles, when rods were incubated simultaneously with Texas Red and AlexaFluor-488 dyes conjugated to either 3-kDa or 10-kDa dextran, more vesicles loaded small molecules than large molecules. Using TIRFM to detect release by the disappearance of dye-loaded vesicles, we found that SR101 and 3-kDa Texas Red were released from individual vesicles more readily than 10-kDa and 70-kDa Texas Red. Although 10-kDa pHrodo was endocytosed poorly like other large dyes, the fraction of release events was similar to SR101 and 3-kDa Texas Red. We hypothesize that while 10-kDa pHrodo may not exit through a fusion pore, release of intravesicular protons can promote detection of fusion events by rapidly quenching fluorescence of this pH-sensitive dye. Assuming that large molecules can only be released by full-collapse whereas small molecules can be released by both modes, our results indicate that 50%–70% of release from rods involves kiss-and-run with 2.3–4.6 nm fusion pores. Rapid retrieval of vesicles by kiss-and-run may limit membrane disruption of release site function during ongoing release at photoreceptor ribbon synapses.
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Affiliation(s)
- Xiangyi Wen
- Department of Pharmacology & Experimental Neuroscience, University of Nebraska Medical CenterOmaha, NE, United States.,Ophthalmology & Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical CenterOmaha, NE, United States
| | - Grant W Saltzgaber
- Ophthalmology & Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical CenterOmaha, NE, United States
| | - Wallace B Thoreson
- Department of Pharmacology & Experimental Neuroscience, University of Nebraska Medical CenterOmaha, NE, United States.,Ophthalmology & Visual Sciences, Truhlsen Eye Institute, University of Nebraska Medical CenterOmaha, NE, United States
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