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Stefano G, Brandizzi F. Advances in Plant ER Architecture and Dynamics. PLANT PHYSIOLOGY 2018; 176:178-186. [PMID: 28986423 PMCID: PMC5761816 DOI: 10.1104/pp.17.01261] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 10/01/2017] [Indexed: 05/18/2023]
Abstract
Recent advances highlight mechanisms that enable the morphological integrity of the plant ER in relation to the other organelles and the cytoskeleton.
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Affiliation(s)
- Giovanni Stefano
- MSU-DOE Plant Research Lab and Plant Biology Department, Michigan State University, East Lansing, Michigan 48824
| | - Federica Brandizzi
- MSU-DOE Plant Research Lab and Plant Biology Department, Michigan State University, East Lansing, Michigan 48824
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Sun L, Yau HY, Lau OC, Huang Y, Yao X. Effect of hydrogen peroxide and superoxide anions on cytosolic Ca2+: comparison of endothelial cells from large-sized and small-sized arteries. PLoS One 2011; 6:e25432. [PMID: 21966527 PMCID: PMC3180448 DOI: 10.1371/journal.pone.0025432] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Accepted: 09/05/2011] [Indexed: 11/18/2022] Open
Abstract
We compared the Ca2+ responses to reactive oxygen species (ROS) between mouse endothelial cells derived from large-sized arteries, aortas (aortic ECs), and small-sized arteries, mesenteric arteries (MAECs). Application of hydrogen peroxide (H2O2) caused an increase in cytosolic Ca2+ levels ([Ca2+]i) in both cell types. The [Ca2+]i rises diminished in the presence of U73122, a phospholipase C inhibitor, or Xestospongin C (XeC), an inhibitor for inositol-1,4,5-trisphosphate (IP3) receptors. Removal of Ca2+ from the bath also decreased the [Ca2+]i rises in response to H2O2. In addition, treatment of endothelial cells with H2O2 reduced the [Ca2+]i responses to subsequent challenge of ATP. The decreased [Ca2+]i responses to ATP were resulted from a pre-depletion of intracellular Ca2+ stores by H2O2. Interestingly, we also found that Ca2+ store depletion was more sensitive to H2O2 treatment in endothelial cells of mesenteric arteries than those of aortas. Hypoxanthine-xanthine oxidase (HX-XO) was also found to induce [Ca2+]i rises in both types of endothelial cells, the effect of which was mediated by superoxide anions and H2O2 but not by hydroxyl radical. H2O2 contribution in HX-XO-induced [Ca2+]i rises were more significant in endothelial cells from mesenteric arteries than those from aortas. In summary, H2O2 could induce store Ca2+ release via phospholipase C-IP3 pathway in endothelial cells. Resultant emptying of intracellular Ca2+ stores contributed to the reduced [Ca2+]i responses to subsequent ATP challenge. The [Ca2+]i responses were more sensitive to H2O2 in endothelial cells of small-sized arteries than those of large-sized arteries.
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Affiliation(s)
- Lei Sun
- School of Biomedical Sciences and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Ho-Yan Yau
- School of Biomedical Sciences and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - On-Chai Lau
- School of Biomedical Sciences and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Yu Huang
- School of Biomedical Sciences and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Xiaoqiang Yao
- School of Biomedical Sciences and Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China
- * E-mail:
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Kucharz K, Wieloch T, Toresson H. Potassium-induced structural changes of the endoplasmic reticulum in pyramidal neurons in murine organotypic hippocampal slices. J Neurosci Res 2011; 89:1150-9. [PMID: 21538461 DOI: 10.1002/jnr.22646] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Revised: 02/08/2011] [Accepted: 02/09/2011] [Indexed: 12/15/2022]
Abstract
The endoplasmic reticulum (ER) structure is of central importance for the regulation of cellular anabolism, stress response, and signal transduction. Generally continuous, the ER can temporarily undergo dramatic structural rearrangements resulting in a fragmented appearance. In this study we assess the dynamic nature of ER fission in pyramidal neurons in organotypic hippocampal slice cultures stimulated by depolarizing concentration of potassium (50 mM). The slices were obtained from transgenic mice expressing fluorescent ER-targeted DsRed2 protein. We employed live tissue confocal microscopy imaging with fluorescence recovery after photobleaching (FRAP) to monitor the extent of structural rearrangements of the ER. In control slices, the ER structure was continuous. Potassium stimulation resulted in extensive fragmentation (fission), whereas return to basal potassium levels (2.5 mM) led to ER fusion and normalization of ER structure. This ER fission/fusion could be repeated several times in the same neuron, demonstrating the reversibility of the process. Blockade of the N-methyl-D-aspartate receptor (NMDAR) with the antagonist D-AP5 or removal of extracellular Ca(2+) prevented depolarization-induced ER fission. ER fission is sensitive to temperature, and decreasing temperature from 35°C to 30°C augments fission, implying that the altering of ER continuity may be a protective response against damage. We conclude that events that generate membrane depolarisation in brain tissue lead to the release of endogenous glutamate that may regulate neuronal ER continuity. The rapid and reversible NMDAR-mediated changes in ER structure reflect an adaptive, innate property of the ER for synaptic activation as well as response to tissue stress, injury, and disease.
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Affiliation(s)
- Krzysztof Kucharz
- Laboratory for Experimental Brain Research, Department of Clinical Sciences Lund, Lund University, Lund, Sweden
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Kucharz K, Krogh M, Ng AN, Toresson H. NMDA receptor stimulation induces reversible fission of the neuronal endoplasmic reticulum. PLoS One 2009; 4:e5250. [PMID: 19381304 PMCID: PMC2668765 DOI: 10.1371/journal.pone.0005250] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Accepted: 03/19/2009] [Indexed: 12/02/2022] Open
Abstract
With few exceptions the endoplasmic reticulum (ER) is considered a continuous system of endomembranes within which proteins and ions can move. We have studied dynamic structural changes of the ER in hippocampal neurons in primary culture and organotypic slices. Fluorescence recovery after photobleaching (FRAP) was used to quantify and model ER structural dynamics. Ultrastructure was assessed by electron microscopy. In live cell imaging experiments we found that, under basal conditions, the ER of neuronal soma and dendrites was continuous. The smooth and uninterrupted appearance of the ER changed dramatically after glutamate stimulation. The ER fragmented into isolated vesicles in a rapid fission reaction that occurred prior to overt signs of neuronal damage. ER fission was found to be independent of ER calcium levels. Apart from glutamate, the calcium ionophore ionomycin was able to induce ER fission. The N-methyl, D-aspartate (NMDA) receptor antagonist MK-801 inhibited ER fission induced by glutamate as well as by ionomycin. Fission was not blocked by either ifenprodil or kinase inhibitors. Interestingly, sub-lethal NMDA receptor stimulation caused rapid ER fission followed by fusion. Hence, ER fission is not strictly associated with cellular damage or death. Our results thus demonstrate that neuronal ER structure is dynamically regulated with important consequences for protein mobility and ER luminal calcium tunneling.
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Affiliation(s)
- Krzysztof Kucharz
- Laboratory for Experimental Brain Research, Wallenberg Neuroscience Centre, Department of Clinical Sciences Lund, Lund University, Lund, Sweden
| | - Morten Krogh
- Computational Biology and Biological Physics, Department of Theoretical Physics, Lund University, Lund, Sweden
| | - Ai Na Ng
- Laboratory for Experimental Brain Research, Wallenberg Neuroscience Centre, Department of Clinical Sciences Lund, Lund University, Lund, Sweden
| | - Håkan Toresson
- Laboratory for Experimental Brain Research, Wallenberg Neuroscience Centre, Department of Clinical Sciences Lund, Lund University, Lund, Sweden
- * E-mail:
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Dawson LJ, Stanbury J, Venn N, Hasdimir B, Rogers SN, Smith PM. Antimuscarinic antibodies in primary Sjögren's syndrome reversibly inhibit the mechanism of fluid secretion by human submandibular salivary acinar cells. ACTA ACUST UNITED AC 2006; 54:1165-73. [PMID: 16572451 DOI: 10.1002/art.21764] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Sjögren's syndrome (SS) is an autoimmune condition affecting salivary glands, for which a clearly defined pathogenic autoantibody has yet to be identified. Autoantibodies that bind to the muscarinic M3 receptors (M3R), which regulate fluid secretion in salivary glands, have been proposed in this context. However, there are no previous data that directly show antisecretory activity. This study was undertaken to investigate and characterize the antisecretory activity of anti-M3R. METHODS Microfluorimetric Ca2+ imaging and patch clamp electrophysiologic techniques were used to measure the secretagogue-evoked increase in [Ca2+]i and consequent activation of Ca2+-dependent ion channels in individual mouse and human submandibular acinar cells. Together, these techniques form a sensitive bioassay that was used to determine whether IgG isolated from patients with primary SS and from control subjects has antisecretory activity. RESULTS IgG (2 mg/ml) from patients with primary SS reduced the carbachol-evoked increase in [Ca2+]i in both mouse and human acinar cells by approximately 50%. IgG from control subjects had no effect on the Ca2+ signal. Furthermore, the inhibitory action of primary SS patient IgG on the Ca2+ signal was acutely reversible. We repeated our observations using rabbit serum containing antibodies raised against the second extracellular loop of M3R and found an identical pattern of acutely reversible inhibition. Anti-M3R-positive serum had no effect on Ca2+-dependent ion channel activation evoked by the direct intracellular infusion of inositol 1,4,5-triphosphate. CONCLUSION These observations show for the first time that IgG from patients with primary SS contains autoantibodies capable of damaging saliva production and contributing to xerostomia. The unusual but not unprecedented acute reversibility of the effects of anti-M3 autoantibodies is the subject of further research.
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Affiliation(s)
- L J Dawson
- The University of Liverpool, and Aintree Hospitals, Liverpool, UK.
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Dawson LJ, Fox PC, Smith PM. Sjögrens syndrome—the non-apoptotic model of glandular hypofunction. Rheumatology (Oxford) 2006; 45:792-8. [PMID: 16595520 DOI: 10.1093/rheumatology/kel067] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Affiliation(s)
- L J Dawson
- Oral Surgery, University of Liverpool Dental School, Room 1.10, Edwards Building, Daulby Street, Liverpool L69 3GN, UK.
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Brough D, Sim Y, Thorn P, Irvine RF. The structural integrity of the endoplasmic reticulum, and its possible regulation by inositol 1,3,4,5-tetrakisphosphate. Cell Calcium 2005; 38:153-9. [PMID: 16023721 DOI: 10.1016/j.ceca.2005.05.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2005] [Revised: 04/25/2005] [Accepted: 05/10/2005] [Indexed: 11/17/2022]
Abstract
The endoplasmic reticulum (ER) is a dynamic organelle thought to consist of a single interconnected network of membranes. Using fluorescence recovery after photobleaching (FRAP) of HEK-293 cells dually transfected with soluble fluorescent proteins targeted to the ER (GFP) and mitochondria (DsRed), we have confirmed this continuity, which contrasts that of the mitochondria, which behave as a population of discrete organelles. The degree of ER integrity (interconnected versus fragmented) has been suggested to be regulated in some cells by inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P(4)). In HEK-293 and freshly isolated murine lacrimal acinar cells, we manipulated ER structure by disrupting cellular Ca(2+) homeostasis with the Ca(2+) ionophore ionomycin, and by permeabilisation of the plasma membrane, protocols known to cause ER fragmentation. However, we were subsequently unable to detect by FRAP any significant effect of Ins(1,3,4,5)P(4) on ER integrity.
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Dawson L, Tobin A, Smith P, Gordon T. Antimuscarinic antibodies in Sjögren's syndrome: Where are we, and where are we going? ACTA ACUST UNITED AC 2005; 52:2984-95. [PMID: 16200578 DOI: 10.1002/art.21347] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Luke Dawson
- University of Liverpool, Liverpool Merseyside, UK.
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Harmer AR, Smith PM, Gallacher DV. Local and global calcium signals and fluid and electrolyte secretion in mouse submandibular acinar cells. Am J Physiol Gastrointest Liver Physiol 2005; 288:G118-24. [PMID: 15308468 DOI: 10.1152/ajpgi.00096.2004] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Polarized Ca(2+) signals that originate at and spread from the apical pole have been shown to occur in acinar cells from lacrimal, parotid, and pancreatic glands. However, "local" Ca(2+) signals, that are restricted to the apical pole of the cell, have been previously demonstrated only in pancreatic acinar cells in which the primary function of the Ca(2+) signal is to regulate exocytosis. We show that submandibular acinar cells, in which the primary function of the Ca(2+) signal is to drive fluid and electrolyte secretion, are capable of both Ca(2+) waves and local Ca(2+) signals. The generally accepted model for fluid and electrolyte secretion requires simultaneous Ca(2+)-activation of basally located K(+) channels and apically located Cl(-) channels. Whereas a propagated cell-wide Ca(2+) signal is clearly consistent with this model, a local Ca(2+) signal is not, because there is no increase in intracellular Ca(2+) concentration at the basal pole of the cell. Our data provide the first direct demonstration, in submandibular acinar cells, of the apical and basal location of the Cl(-) and K(+) channels, respectively, and confirm that local Ca(2+) signals do not Ca(2+)-activate K(+) channels. We reevaluate the model for fluid and electrolyte secretion and demonstrate that Ca(2+)-activation of the Cl(-) channels is sufficient to voltage-activate the K(+) channels and thus demonstrate that local Ca(2+) signals are sufficient to support fluid secretion.
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Affiliation(s)
- A R Harmer
- Clinical Dental Sciences, The University of Liverpool, Liverpool L69 3GN, UK
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Dewaste V, Moreau C, De Smedt F, Bex F, De Smedt H, Wuytack F, Missiaen L, Erneux C. The three isoenzymes of human inositol-1,4,5-trisphosphate 3-kinase show specific intracellular localization but comparable Ca2+ responses on transfection in COS-7 cells. Biochem J 2003; 374:41-9. [PMID: 12747803 PMCID: PMC1223573 DOI: 10.1042/bj20021963] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2002] [Revised: 04/24/2003] [Accepted: 05/15/2003] [Indexed: 12/16/2022]
Abstract
Inositol 1,4,5-trisphosphate [Ins(1,4,5) P3] 3-kinase catalyses the phosphorylation of InsP3 to inositol 1,3,4,5-tetrakisphosphate. cDNAs encoding three human isoenzymes of InsP3 3-kinase (A, B and C) have been reported previously [Choi, Kim, Lee, Moon, Sim, Kim, Chung and Rhee (1990) Science 248, 64-66; Dewaste, Pouillon, Moreau, Shears, Takazawa and Erneux (2000) Biochem. J. 352, 343-351; Dewaste, Roymans, Moreau and Erneux (2002) Biochem. Biophys. Res. Commun. 291, 400-405; Takazawa, Perret, Dumont and Erneux (1991) Biochem. Biophys. Res. Commun. 174, 529-535]. The localization of InsP3 3-kinase isoenzymes fused at their N-terminus to the green fluorescent protein has been studied by confocal microscopy. The A isoform appeared to associate with the cytoskeleton, whereas the C isoform was totally cytoplasmic. The B isoform had a more complex localization: it appeared in the plasma membrane, cytoskeleton and in the endoplasmic reticulum. The three human isoenzymes of InsP3 3-kinase can thus be distinguished by their N-terminal sequence, sensitivity to Ca2+/calmodulin and localization on transfection in COS-7 cells. We have compared the cytosolic Ca2+ responses induced by ATP in COS-7 cells transfected with the three isoenzymes. Cells expressing high levels of any of the three isoforms no longer respond to ATP, whereas cells expressing low levels of each enzyme showed a reduced response consisting of one to three Ca2+ spikes in response to 100 microM ATP. These effects were seen only in wild-type InsP3 3-kinase-transfected cells. 3-Kinase-dead mutant cells behaved as vector-transfected cells. The results highlight the potential role of the three isoforms of InsP3 3-kinase as direct InsP3 metabolizing enzymes and direct regulators of Ca2+ responses to extracellular signals.
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Affiliation(s)
- Valérie Dewaste
- Institute of Interdisciplinary Research, Université Libre de Bruxelles, Campus Erasme, Bldg. C, 808 route de Lennik, B-1070 Brussels, Belgium
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Hodges RR, Dartt DA. Regulatory pathways in lacrimal gland epithelium. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 231:129-96. [PMID: 14713005 DOI: 10.1016/s0074-7696(03)31004-6] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Tears are a complex fluid that continuously cover the exposed surface of the eye, namely the cornea and conjunctiva. Tears are secreted in response to the multitude of environmental stresses that can harm the ocular surface such as cold, mechanical stimulation, physical injury, noxious chemicals, as well as infections from various organisms. Tears also provide nutrients and remove waste from cells of the ocular surface. Because of the varied function of tears, tears are complex and are secreted by several different tissues. Tear secretion is under tight neural control allowing tears to respond rapidly to changing environmental conditions. The lacrimal gland is the main contributor to the aqueous portion of the tear film and the regulation of secretion from this gland has been well studied. Despite multiple redundencies in pathways to stimulate secretion from the lacrimal gland, defects can occur resulting in dry eye syndromes. These diseases can have deleterious effects on vision. In this review, we summarize the latest information regarding the regulatory pathways, which control secretion from the lacrimal gland, and their roles in the pathogenesis of dry eye syndromes.
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Affiliation(s)
- Robin R Hodges
- Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114, USA
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