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Luo J, Chen L, Huang F, Gao P, Zhao H, Wang Y, Han S. Intraorganellar calcium imaging in Arabidopsis seedling roots using the GCaMP variants GCaMP6m and R-CEPIA1er. JOURNAL OF PLANT PHYSIOLOGY 2020; 246-247:153127. [PMID: 32007728 DOI: 10.1016/j.jplph.2020.153127] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 01/14/2020] [Accepted: 01/14/2020] [Indexed: 05/26/2023]
Abstract
Ca2+ acts as a universal second messenger in eukaryotes. In animals, a wide variety of environmental and developmental stimuli trigger Ca2+ dynamics in organelles, such as the cytoplasm, nucleus, and endoplasmic reticulum (ER). However, ER Ca2+ ([Ca2+]er) homeostasis and its contributions in cytosolic and/or nucleosolic Ca2+ dynamics in plants remain elusive. GCaMPs are comprised of a circularly permutated form of enhanced green fluorescent protein fused to calmodulin and myosin light-chain kinase M13 and used for monitoring Ca2+ dynamics in mammalian cells. Here, we targeted a high-affinity variant of GCaMP with nuclear export signal in the cytoplasm (NES-GCaMP6m), with a nuclear-localised signal in the nucleus (NLS-GCaMP6m), and a low-affinity variant of GCaMP, also known as calcium-measuring organelle-entrapped protein indicators (CEPIA), with a signal peptide sequence of the ER-localised protein Calreticulin 1a in the ER lumen (CRT1a-R-CEPIA1er) for intraorganellar Ca2+ imaging in Arabidopsis. We found that cytosolic Ca2+ ([Ca2+]cyt) increases induced by 250 mM sorbitol as an osmotic stress stimulus, 50 μM abscisic acid (ABA), or 1 mM carbachol (CCh) were mainly due to extracellular Ca2+ influx, whereas nucleosolic Ca2+ ([Ca2+]nuc) increases triggered by osmotic stress, ABA, or CCh were contributed by [Ca2+]er release. In addition, [Ca2+]er dynamics presented specific patterns in response to different stimuli such as osmotic stress, ABA, or CCh, indicating that Ca2+ signalling occurs in the ER in plants. These results provide valuable insights into subcellular Ca2+ dynamics in response to different stresses in Arabidopsis root cells and prove that GCaMP imaging is a useful tool for furthering our understanding of plant organelle functions.
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Affiliation(s)
- Jin Luo
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Lvli Chen
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Feifei Huang
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Ping Gao
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Heping Zhao
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Yingdian Wang
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Shengcheng Han
- Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Sciences, Beijing Normal University, Beijing 100875, China.
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Danese A, Marchi S, Vitto VAM, Modesti L, Leo S, Wieckowski MR, Giorgi C, Pinton P. Cancer-Related Increases and Decreases in Calcium Signaling at the Endoplasmic Reticulum-Mitochondria Interface (MAMs). Rev Physiol Biochem Pharmacol 2020; 185:153-193. [PMID: 32789789 DOI: 10.1007/112_2020_43] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Endoplasmic reticulum (ER)-mitochondria regions are specialized subdomains called also mitochondria-associated membranes (MAMs). MAMs allow regulation of lipid synthesis and represent hubs for ion and metabolite signaling. As these two organelles can module both the amplitude and the spatiotemporal patterns of calcium (Ca2+) signals, this particular interaction controls several Ca2+-dependent pathways well known for their contribution to tumorigenesis, such as metabolism, survival, sensitivity to cell death, and metastasis. Mitochondria-mediated apoptosis arises from mitochondrial Ca2+ overload, permeabilization of the mitochondrial outer membrane, and the release of mitochondrial apoptotic factors into the cytosol. Decreases in Ca2+ signaling at the ER-mitochondria interface are being studied in depth as failure of apoptotic-dependent cell death is one of the predominant characteristics of cancer cells. However, some recent papers that linked MAMs Ca2+ crosstalk-related upregulation to tumor onset and progression have aroused the interest of the scientific community.In this review, we will describe how different MAMs-localized proteins modulate the effectiveness of Ca2+-dependent apoptotic stimuli by causing both increases and decreases in the ER-mitochondria interplay and, specifically, by modulating Ca2+ signaling.
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Affiliation(s)
- Alberto Danese
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Saverio Marchi
- Department of Clinical and Molecular Sciences, Marche Polytechnic University, Ancona, Italy
| | - Veronica Angela Maria Vitto
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Lorenzo Modesti
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Sara Leo
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Mariusz R Wieckowski
- Laboratory of Mitochondrial Biology and Metabolism, Nencki Institute of Experimental Biology of Polish Academy of Sciences, Warsaw, Poland
| | - Carlotta Giorgi
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy
| | - Paolo Pinton
- Department of Medical Sciences, Laboratory for Technologies of Advanced Therapies (LTTA), University of Ferrara, Ferrara, Italy.
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Félix-Martínez GJ, Gil A, Segura J, Villanueva J, Gutíerrez LM. Modeling the influence of co-localized intracellular calcium stores on the secretory response of bovine chromaffin cells. Comput Biol Med 2018; 100:165-175. [PMID: 30015013 DOI: 10.1016/j.compbiomed.2018.06.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 06/26/2018] [Accepted: 06/27/2018] [Indexed: 11/19/2022]
Abstract
Catecholamines secretion from chromaffin cells is mediated by a Ca2+-dependent process in the submembrane space where the exocytotic machinery is located and high-Ca2+ microdomains (HCMDs) are formed by the coordinated activity of a functional triad composed of Ca2+ channels, endoplasmic reticulum (ER) and mitochondria. It has been observed experimentally that subpopulations of cortical mitochondria and ER associate to secretory sites in bovine chromaffin cells. Here, we study the effect of the geometrical distribution of the co-localized cortical organelles both in the formation of HCMDs in the vicinity of Ca2+ channels and on the secretory activity of bovine chromaffin cells in response to a single voltage pulse. Our simulations indicate that co-localized organelles have a dual role in the formation of HCMDs, having, on the one hand, an amplification effect due to the Ca2+-induced Ca2+-release mechanism from the ER and, on the other, acting as physical barriers to Ca2+ diffusion. In addition, our simulations suggest that the increased levels of Ca2+ in the microdomain enhances the secretion of the vesicles co-localized to the Ca2+ channels. As a whole, our results support the idea that the functional triads formed by Ca2+ channels, subplasmalemma ER and mitochondria have a positive effect on the secretion of catecholamines in bovine chromaffin cells.
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Affiliation(s)
- Gerardo J Félix-Martínez
- Depto. de Matemática Aplicada y Ciencias de la Computación, Universidad de Cantabria, 39005, Santander, Spain; Depto. de Ingeniería Eléctrica, Universidad Autónoma Metropolitana, 09340, Mexico City, Mexico.
| | - Amparo Gil
- Depto. de Matemática Aplicada y Ciencias de la Computación, Universidad de Cantabria, 39005, Santander, Spain.
| | - Javier Segura
- Depto. de Matemáticas, Estadística y Computación, Universidad de Cantabria, 39005, Santander, Spain.
| | - José Villanueva
- Instituto de Neurociencias, Centro Mixto Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant, 03550, Alicante, Spain.
| | - Luis M Gutíerrez
- Instituto de Neurociencias, Centro Mixto Universidad Miguel Hernández-CSIC, Sant Joan d'Alacant, 03550, Alicante, Spain.
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Wheeler DG, Groth RD, Ma H, Barrett CF, Owen SF, Safa P, Tsien RW. Ca(V)1 and Ca(V)2 channels engage distinct modes of Ca(2+) signaling to control CREB-dependent gene expression. Cell 2012; 149:1112-24. [PMID: 22632974 DOI: 10.1016/j.cell.2012.03.041] [Citation(s) in RCA: 183] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2009] [Revised: 11/11/2011] [Accepted: 03/07/2012] [Indexed: 12/23/2022]
Abstract
Activity-dependent gene expression triggered by Ca(2+) entry into neurons is critical for learning and memory, but whether specific sources of Ca(2+) act distinctly or merely supply Ca(2+) to a common pool remains uncertain. Here, we report that both signaling modes coexist and pertain to Ca(V)1 and Ca(V)2 channels, respectively, coupling membrane depolarization to CREB phosphorylation and gene expression. Ca(V)1 channels are advantaged in their voltage-dependent gating and use nanodomain Ca(2+) to drive local CaMKII aggregation and trigger communication with the nucleus. In contrast, Ca(V)2 channels must elevate [Ca(2+)](i) microns away and promote CaMKII aggregation at Ca(V)1 channels. Consequently, Ca(V)2 channels are ~10-fold less effective in signaling to the nucleus than are Ca(V)1 channels for the same bulk [Ca(2+)](i) increase. Furthermore, Ca(V)2-mediated Ca(2+) rises are preferentially curbed by uptake into the endoplasmic reticulum and mitochondria. This source-biased buffering limits the spatial spread of Ca(2+), further attenuating Ca(V)2-mediated gene expression.
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Affiliation(s)
- Damian G Wheeler
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305-5345, USA
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Mitochondria and chromaffin cell function. Pflugers Arch 2012; 464:33-41. [PMID: 22278417 DOI: 10.1007/s00424-012-1074-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 01/05/2012] [Accepted: 01/09/2012] [Indexed: 10/14/2022]
Abstract
Chromaffin cells are an excellent model for stimulus-secretion coupling. Ca(2+) entry through plasma membrane voltage-operated Ca(2+) channels (VOCC) is the trigger for secretion, but the intracellular organelles contribute subtle nuances to the Ca(2+) signal. The endoplasmic reticulum amplifies the cytosolic Ca(2+) ([Ca(2+)](C)) signal by Ca(2+)-induced Ca(2+) release (CICR) and helps generation of microdomains with high [Ca(2+)](C) (HCMD) at the subplasmalemmal region. These HCMD induce exocytosis of the docked secretory vesicles. Mitochondria close to VOCC take up large amounts of Ca(2+) from HCMD and stop progression of the Ca(2+) wave towards the cell core. On the other hand, the increase of [Ca(2+)] at the mitochondrial matrix stimulates respiration and tunes energy production to the increased needs of the exocytic activity. At the end of stimulation, [Ca(2+)](C) decreases rapidly and mitochondria release the Ca(2+) accumulated in the matrix through the Na(+)/Ca(2+) exchanger. VOCC, CICR sites and nearby mitochondria form functional triads that co-localize at the subplasmalemmal area, where secretory vesicles wait ready for exocytosis. These triads optimize stimulus-secretion coupling while avoiding propagation of the Ca(2+) signal to the cell core. Perturbation of their functioning in neurons may contribute to the genesis of excitotoxicity, ageing mental retardation and/or neurodegenerative disorders.
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Ramadan JW, Steiner SR, O'Neill CM, Nunemaker CS. The central role of calcium in the effects of cytokines on beta-cell function: implications for type 1 and type 2 diabetes. Cell Calcium 2011; 50:481-90. [PMID: 21944825 DOI: 10.1016/j.ceca.2011.08.005] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Revised: 07/20/2011] [Accepted: 08/16/2011] [Indexed: 12/29/2022]
Abstract
The appropriate regulation of intracellular calcium is a requirement for proper cell function and survival. This review focuses on the effects of proinflammatory cytokines on calcium regulation in the insulin-producing pancreatic beta-cell and how normal stimulus-secretion coupling, organelle function, and overall beta-cell viability are impacted. Proinflammatory cytokines are increasingly thought to contribute to beta-cell dysfunction not only in type 1 diabetes (T1D), but also in the progression of type 2 diabetes (T2D). Cytokine-induced disruptions in calcium handling result in reduced insulin release in response to glucose stimulation. Cytokines can alter intracellular calcium levels by depleting calcium from the endoplasmic reticulum (ER) and by increasing calcium influx from the extracellular space. Depleting ER calcium leads to protein misfolding and activation of the ER stress response. Disrupting intracellular calcium may also affect organelles, including the mitochondria and the nucleus. As a chronic condition, cytokine-induced calcium disruptions may lead to beta-cell death in T1D and T2D, although possible protective effects are also discussed. Calcium is thus central to both normal and pathological cell processes. Because the tight regulation of intracellular calcium is crucial to homeostasis, measuring the dynamics of calcium may serve as a good indicator of overall beta-cell function.
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Affiliation(s)
- James W Ramadan
- Department of Medicine, University of Virginia, Charlottesville, United States
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Bakayan A, Vaquero CF, Picazo F, Llopis J. Red fluorescent protein-aequorin fusions as improved bioluminescent Ca2+ reporters in single cells and mice. PLoS One 2011; 6:e19520. [PMID: 21589654 PMCID: PMC3092744 DOI: 10.1371/journal.pone.0019520] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Accepted: 04/08/2011] [Indexed: 11/18/2022] Open
Abstract
Bioluminescence recording of Ca(2+) signals with the photoprotein aequorin does not require radiative energy input and can be measured with a low background and good temporal resolution. Shifting aequorin emission to longer wavelengths occurs naturally in the jellyfish Aequorea victoria by bioluminescence resonance energy transfer (BRET) to the green fluorescent protein (GFP). This process has been reproduced in the molecular fusions GFP-aequorin and monomeric red fluorescent protein (mRFP)-aequorin, but the latter showed limited transfer efficiency. Fusions with strong red emission would facilitate the simultaneous imaging of Ca(2+) in various cell compartments. In addition, they would also serve to monitor Ca(2+) in living organisms since red light is able to cross animal tissues with less scattering. In this study, aequorin was fused to orange and various red fluorescent proteins to identify the best acceptor in red emission bands. Tandem-dimer Tomato-aequorin (tdTA) showed the highest BRET efficiency (largest energy transfer critical distance R(0)) and percentage of counts in the red band of all the fusions studied. In addition, red fluorophore maturation of tdTA within cells was faster than that of other fusions. Light output was sufficient to image ATP-induced Ca(2+) oscillations in single HeLa cells expressing tdTA. Ca(2+) rises caused by depolarization of mouse neuronal cells in primary culture were also recorded, and changes in fine neuronal projections were spatially resolved. Finally, it was also possible to visualize the Ca(2+) activity of HeLa cells injected subcutaneously into mice, and Ca(2+) signals after depositing recombinant tdTA in muscle or the peritoneal cavity. Here we report that tdTA is the brightest red bioluminescent Ca(2+) sensor reported to date and is, therefore, a promising probe to study Ca(2+) dynamics in whole organisms or tissues expressing the transgene.
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Affiliation(s)
- Adil Bakayan
- Facultad de Medicina and Centro Regional de Investigaciones Biomédicas (CRIB), University of Castilla-La Mancha, Albacete, Spain
| | - Cecilia F. Vaquero
- Facultad de Medicina and Centro Regional de Investigaciones Biomédicas (CRIB), University of Castilla-La Mancha, Albacete, Spain
| | - Fernando Picazo
- Facultad de Medicina and Centro Regional de Investigaciones Biomédicas (CRIB), University of Castilla-La Mancha, Albacete, Spain
| | - Juan Llopis
- Facultad de Medicina and Centro Regional de Investigaciones Biomédicas (CRIB), University of Castilla-La Mancha, Albacete, Spain
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Tracqui P, Ohayon J. An integrated formulation of anisotropic force-calcium relations driving spatio-temporal contractions of cardiac myocytes. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2009; 367:4887-4905. [PMID: 19884185 DOI: 10.1098/rsta.2009.0149] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Isolated cardiac myocytes exhibit spontaneous patterns of rhythmic contraction, driven by intracellular calcium waves. In order to study the coupling between spatio-temporal calcium dynamics and cell contraction in large deformation regimes, a new strain-energy function, describing the influence of sarcomere length on the calcium-dependent generation of active intracellular stresses, is proposed. This strain-energy function includes anisotropic passive and active contributions that were first validated separately from experimental stress-strain curves and stress-sarcomere length curves, respectively. An extended validation of this formulation was then conducted by considering this strain-energy function as the core of an integrated mechano-chemical three-dimensional model of cardiac myocyte contraction, where autocatalytic intracellular calcium dynamics were described by a representative two-variable model able to generate realistic intracellular calcium waves similar to those observed experimentally. Finite-element simulations of the three-dimensional cell model, conducted for different intracellular locations of triggering calcium sparks, explained very satisfactorily, both qualitatively and quantitatively, the contraction patterns of cardiac myocytes observed by time-lapse videomicroscopy. This integrative approach of the mechano-chemical couplings driving cardiac myocyte contraction provides a comprehensive framework for analysing active stress regulation and associated mechano-transduction processes that contribute to the efficiency of cardiac cell contractility in both physiological and pathological contexts.
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Affiliation(s)
- Philippe Tracqui
- Laboratoire Techniques de l'Ingéniere Médicale et da Complexité - Informatique, Mathématiques et Applications de Grenoble, Equipe DynaCell, Unité Mixte de Recherche, Centre National de Recherche Scientifique 5525, Institut d'Ingénierie et de l'Information de Santé (In3S), Université Joseph Fourier, Faculté de Médecine de Grenoble, 38706 La Tronche Cedex, France.
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Lur G, Haynes LP, Prior IA, Gerasimenko OV, Feske S, Petersen OH, Burgoyne RD, Tepikin AV. Ribosome-free terminals of rough ER allow formation of STIM1 puncta and segregation of STIM1 from IP(3) receptors. Curr Biol 2009; 19:1648-53. [PMID: 19765991 PMCID: PMC2887489 DOI: 10.1016/j.cub.2009.07.072] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Revised: 07/19/2009] [Accepted: 07/31/2009] [Indexed: 11/03/2022]
Abstract
Store-operated Ca(2+) entry is a ubiquitous mechanism that prevents the depletion of endoplasmic reticulum (ER) calcium. A reduction of ER calcium triggers translocation of STIM proteins, which serve as calcium sensors in the ER, to subplasmalemmal puncta where they interact with and activate Orai channels. In pancreatic acinar cells, inositol 1,4,5-trisphosphate (IP(3)) receptors populate the apical part of the ER. Here, however, we observe that STIM1 translocates exclusively to the lateral and basal regions following ER Ca(2+) loss. This finding is paradoxical because the basal and lateral regions of the acinar cells contain rough ER (RER); the size of the ribosomes that decorate RER is larger than the distance that can be spanned by a STIM-Orai complex, and STIM1 function should therefore not be possible. We resolve this paradox and characterize ribosome-free terminals of the RER that form junctions between the reticulum and the plasma membrane in the basal and lateral regions of the acinar cells. Our findings indicate that different ER compartments specialize in different calcium-handling functions (Ca(2+) release and Ca(2+) reloading) and that any potential interference between Ca(2+) release and Ca(2+) influx is minimized by the spatial separation of the two processes.
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Affiliation(s)
- Gyorgy Lur
- Department of Physiology, School of Biomedical Sciences, University of Liverpool, Liverpool L69 3BX, UK
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