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Tsai YM, Jones F, Mullen P, Porter KE, Steele D, Peers C, Gamper N. Vascular Kv7 channels control intracellular Ca 2+ dynamics in smooth muscle. Cell Calcium 2020; 92:102283. [PMID: 32950876 PMCID: PMC7695684 DOI: 10.1016/j.ceca.2020.102283] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 08/21/2020] [Accepted: 08/26/2020] [Indexed: 01/23/2023]
Abstract
Voltage-gated Kv7 (or KCNQ) channels control activity of excitable cells, including vascular smooth muscle cells (VSMCs), by setting their resting membrane potential and controlling other excitability parameters. Excitation-contraction coupling in muscle cells is mediated by Ca2+ but until now, the exact role of Kv7 channels in cytosolic Ca2+ dynamics in VSMCs has not been fully elucidated. We utilised microfluorimetry to investigate the impact of Kv7 channel activity on intracellular Ca2+ levels and electrical activity of rat A7r5 VSMCs and primary human internal mammary artery (IMA) SMCs. Both, direct (XE991) and G protein coupled receptor mediated (vasopressin, AVP) Kv7 channel inhibition induced robust Ca2+ oscillations, which were significantly reduced in the presence of Kv7 channel activator, retigabine, L-type Ca2+ channel inhibitor, nifedipine, or T-type Ca2+ channel inhibitor, NNC 55-0396, in A7r5 cells. Membrane potential measured using FluoVolt exhibited a slow depolarisation followed by a burst of sharp spikes in response to XE991; spikes were temporally correlated with Ca2+ oscillations. Phospholipase C inhibitor (edelfosine) reduced AVP-induced, but not XE991-induced Ca2+ oscillations. AVP and XE991 induced a large increase of [Ca2+]i in human IMA, which was also attenuated with retigabine, nifedipine and NNC 55-0396. RT-PCR, immunohistochemistry and electrophysiology suggested that Kv7.5 was the predominant Kv7 subunit in both rat and human arterial SMCs; CACNA1C (Cav1.2; L-type) and CACNA1 G (Cav3.1; T-type) were the most abundant voltage-gated Ca2+ channel gene transcripts in both types of VSMCs. This study establishes Kv7 channels as key regulators of Ca2+ signalling in VSMCs with Kv7.5 playing a dominant role.
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Affiliation(s)
- Yuan-Ming Tsai
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom; Division of Thoracic Surgery, Department of Surgery, Tri-Service General Hospital, National Defence Medical Centre, Taipei 11490, Taiwan.
| | - Frederick Jones
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Pierce Mullen
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Karen E Porter
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine and Health, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Derek Steele
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Chris Peers
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine and Health, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Nikita Gamper
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom.
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53
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Bornschein G, Eilers J, Schmidt H. Neocortical High Probability Release Sites Are Formed by Distinct Ca 2+ Channel-to-Release Sensor Topographies during Development. Cell Rep 2020; 28:1410-1418.e4. [PMID: 31390556 DOI: 10.1016/j.celrep.2019.07.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 05/29/2019] [Accepted: 06/28/2019] [Indexed: 01/10/2023] Open
Abstract
Coupling distances between Ca2+ channels and release sensors regulate vesicular release probability (pv). Tight coupling is thought to provide a framework for high pv and loose coupling for high plasticity at low pv. At synapses investigated during development, coupling distances decrease, thereby increasing pv and transmission fidelity. We find that neocortical high-fidelity synapses deviate from these rules. Paired recordings from pyramidal neurons with "slow" and "fast" Ca2+ chelators combined with experimentally constrained simulations suggest that coupling tightens significantly during development. However, fluctuation analysis revealed that neither pv (∼0.63) nor the number of release sites (∼8) changes concomitantly. Moreover, the amplitude and time course of presynaptic Ca2+ transients are not different between age groups. These results are explained by high-pv release sites with Ca2+ microdomains in young synapses and nanodomains in mature synapses. Thus, at neocortical synapses, a developmental reorganization of the active zone leaves pv unaffected, emphasizing developmental and functional synaptic diversity.
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Affiliation(s)
- Grit Bornschein
- Carl-Ludwig-Institute for Physiology, Medical Faculty, University of Leipzig, Liebigstrasse 27a, 04103 Leipzig, Germany.
| | - Jens Eilers
- Carl-Ludwig-Institute for Physiology, Medical Faculty, University of Leipzig, Liebigstrasse 27a, 04103 Leipzig, Germany
| | - Hartmut Schmidt
- Carl-Ludwig-Institute for Physiology, Medical Faculty, University of Leipzig, Liebigstrasse 27a, 04103 Leipzig, Germany.
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54
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Carichino L, Olson SD. Emergent three-dimensional sperm motility: coupling calcium dynamics and preferred curvature in a Kirchhoff rod model. MATHEMATICAL MEDICINE AND BIOLOGY-A JOURNAL OF THE IMA 2020; 36:439-469. [PMID: 30325451 DOI: 10.1093/imammb/dqy015] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 09/11/2018] [Accepted: 09/17/2018] [Indexed: 11/15/2022]
Abstract
Changes in calcium concentration along the sperm flagellum regulate sperm motility and hyperactivation, characterized by an increased flagellar bend amplitude and beat asymmetry, enabling the sperm to reach and penetrate the ovum (egg). The signalling pathways by which calcium increases within the flagellum are well established. However, the exact mechanisms of how calcium regulates flagellar bending are still under investigation. We extend our previous model of planar flagellar bending by developing a fluid-structure interaction model that couples the 3D motion of the flagellum in a viscous Newtonian fluid with the evolving calcium concentration. The flagellum is modelled as a Kirchhoff rod: an elastic rod with preferred curvature and twist. The calcium dynamics are represented as a 1D reaction-diffusion model on a moving domain, the flagellum. The two models are coupled assuming that the preferred curvature and twist of the sperm flagellum depend on the local calcium concentration. To investigate the effect of calcium on sperm motility, we compare model results of flagellar bend amplitude and swimming speed for three cases: planar, helical (spiral with equal amplitude in both directions), and quasi-planar (spiral with small amplitude in one direction). We observe that for the same parameters, the planar swimmer is faster and a turning motion is more clearly observed when calcium coupling is accounted for in the model. In the case of flagellar bending coupled to the calcium concentration, we observe emergent trajectories that can be characterized as a hypotrochoid for both quasi-planar and helical bending.
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Affiliation(s)
- Lucia Carichino
- Department of Mathematical Sciences, Worcester Polytechnic Institute, 100 Institute Rd, Worcester, MA, USA
| | - Sarah D Olson
- Department of Mathematical Sciences, Worcester Polytechnic Institute, 100 Institute Rd, Worcester, MA, USA
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Stasiak SE, Jamieson RR, Bouffard J, Cram EJ, Parameswaran H. Intercellular communication controls agonist-induced calcium oscillations independently of gap junctions in smooth muscle cells. SCIENCE ADVANCES 2020; 6:eaba1149. [PMID: 32821820 PMCID: PMC7406377 DOI: 10.1126/sciadv.aba1149] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 06/18/2020] [Indexed: 06/11/2023]
Abstract
In this study, we report the existence of a communication system among human smooth muscle cells that uses mechanical forces to frequency modulate long-range calcium waves. An important consequence of this mechanical signaling is that changes in stiffness of the underlying extracellular matrix can interfere with the frequency modulation of Ca2+ waves, causing smooth muscle cells from healthy human donors to falsely perceive a much higher agonist dose than they actually received. This aberrant sensing of contractile agonist dose on stiffer matrices is completely absent in isolated smooth muscle cells, although the isolated cells can sense matrix rigidity. We show that the intercellular communication that enables this collective Ca2+ response in smooth muscle cells does not involve transport across gap junctions or extracellular diffusion of signaling molecules. Instead, our data support a collective model in which mechanical signaling among smooth muscle cells regulates their response to contractile agonists.
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Affiliation(s)
- S. E. Stasiak
- Department of Bioengineering, Northeastern University, Boston, MA 02115, USA
| | - R. R. Jamieson
- Department of Bioengineering, Northeastern University, Boston, MA 02115, USA
| | - J. Bouffard
- Department of Bioengineering, Northeastern University, Boston, MA 02115, USA
- Department of Biology, Northeastern University, Boston, MA 02115, USA
| | - E. J. Cram
- Department of Bioengineering, Northeastern University, Boston, MA 02115, USA
- Department of Biology, Northeastern University, Boston, MA 02115, USA
| | - H. Parameswaran
- Department of Bioengineering, Northeastern University, Boston, MA 02115, USA
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Mechanosensitivity Is a Characteristic Feature of Cultured Suburothelial Interstitial Cells of the Human Bladder. Int J Mol Sci 2020; 21:ijms21155474. [PMID: 32751838 PMCID: PMC7432121 DOI: 10.3390/ijms21155474] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/24/2020] [Accepted: 07/29/2020] [Indexed: 12/11/2022] Open
Abstract
Bladder dysfunction is characterized by urgency, frequency (pollakisuria, nocturia), and dysuria and may lead to urinary incontinence. Most of these symptoms can be attributed to disturbed bladder sensitivity. There is growing evidence that, besides the urothelium, suburothelial interstitial cells (suICs) are involved in bladder afferent signal processing. The massive expansion of the bladder during the filling phase implicates mechanical stress delivered to the whole bladder wall. Little is known about the reaction of suICs upon mechanical stress. Therefore, we investigated the effects of mechanical stimulation in cultured human suICs. We used fura-2 calcium imaging as a major physiological readout. We found spontaneous intracellular calcium activity in 75 % of the cultured suICs. Defined local pressure application via a glass micropipette led to local increased calcium activity in all stimulated suICs, spreading over the whole cell. A total of 51% of the neighboring cells in a radius of up to 100 µm from the stimulated cell showed an increased activity. Hypotonic ringer and shear stress also induced calcium transients. We found an 18-times increase in syncytial activity compared to unstimulated controls, resulting in an amplification of the primary calcium signal elicited in single cells by 50%. Our results speak in favor of a high sensitivity of suICs for mechanical stress and support the view of a functional syncytium between suICs, which can amplify and distribute local stimuli. Previous studies of connexin expression in the human bladder suggest that this mechanism could also be relevant in normal and pathological function of the bladder in vivo.
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Barak P, Parekh AB. Signaling through Ca 2+ Microdomains from Store-Operated CRAC Channels. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a035097. [PMID: 31358516 DOI: 10.1101/cshperspect.a035097] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Calcium (Ca2+) ion microdomains are subcellular regions of high Ca2+ concentration that develop rapidly near open Ca2+ channels in the plasma membrane or internal stores and generate local regions of high Ca2+ concentration. These microdomains are remarkably versatile in that they activate a range of responses that differ enormously in both their temporal and spatial profile. In this review, we describe how Ca2+ microdomains generated by store-operated calcium channels, a widespread and conserved Ca2+ entry pathway, stimulate different signaling pathways, and how the spatial extent of a Ca2+ microdomain can be influenced by Ca2+ ATPase pumps.
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Affiliation(s)
- Pradeep Barak
- Department of Physiology, Anatomy, and Genetics, Oxford University, Oxford OX1 3PT, United Kingdom
| | - Anant B Parekh
- Department of Physiology, Anatomy, and Genetics, Oxford University, Oxford OX1 3PT, United Kingdom
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58
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Areco VA, Kohan R, Talamoni G, Tolosa de Talamoni NG, Peralta López ME. Intestinal Ca 2+ absorption revisited: A molecular and clinical approach. World J Gastroenterol 2020; 26:3344-3364. [PMID: 32655262 PMCID: PMC7327788 DOI: 10.3748/wjg.v26.i24.3344] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 05/11/2020] [Accepted: 06/10/2020] [Indexed: 02/06/2023] Open
Abstract
Ca2+ has an important role in the maintenance of the skeleton and is involved in the main physiological processes. Its homeostasis is controlled by the intestine, kidney, bone and parathyroid glands. The intestinal Ca2+ absorption occurs mainly via the paracellular and the transcellular pathways. The proteins involved in both ways are regulated by calcitriol and other hormones as well as dietary factors. Fibroblast growth factor 23 (FGF-23) is a strong antagonist of vitamin D action. Part of the intestinal Ca2+ movement seems to be vitamin D independent. Intestinal Ca2+ absorption changes according to different physiological conditions. It is promoted under high Ca2+ demands such as growth, pregnancy, lactation, dietary Ca2+ deficiency and high physical activity. In contrast, the intestinal Ca2+ transport decreases with aging. Oxidative stress inhibits the intestinal Ca2+ absorption whereas the antioxidants counteract the effects of prooxidants leading to the normalization of this physiological process. Several pathologies such as celiac disease, inflammatory bowel diseases, Turner syndrome and others occur with inhibition of intestinal Ca2+ absorption, some hypercalciurias show Ca2+ hyperabsorption, most of these alterations are related to the vitamin D endocrine system. Further research work should be accomplished in order not only to know more molecular details but also to detect possible therapeutic targets to ameliorate or avoid the consequences of altered intestinal Ca2+ absorption.
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Affiliation(s)
- Vanessa A Areco
- Laboratorio “Dr. Fernando Cañas”, Cátedra de Bioquímica y Biología Molecular, Facultad de Ciencias Médicas, INICSA (CONICET-Universidad Nacional de Córdoba), Córdoba 5000, Argentina
| | - Romina Kohan
- Laboratorio “Dr. Fernando Cañas”, Cátedra de Bioquímica y Biología Molecular, Facultad de Ciencias Médicas, INICSA (CONICET-Universidad Nacional de Córdoba), Córdoba 5000, Argentina
| | - Germán Talamoni
- Laboratorio “Dr. Fernando Cañas”, Cátedra de Bioquímica y Biología Molecular, Facultad de Ciencias Médicas, INICSA (CONICET-Universidad Nacional de Córdoba), Córdoba 5000, Argentina
| | - Nori G Tolosa de Talamoni
- Laboratorio “Dr. Fernando Cañas”, Cátedra de Bioquímica y Biología Molecular, Facultad de Ciencias Médicas, INICSA (CONICET-Universidad Nacional de Córdoba), Córdoba 5000, Argentina
| | - María E Peralta López
- Laboratorio “Dr. Fernando Cañas”, Cátedra de Bioquímica y Biología Molecular, Facultad de Ciencias Médicas, INICSA (CONICET-Universidad Nacional de Córdoba), Córdoba 5000, Argentina
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59
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Shah SI, Ullah G. The Function of Mitochondrial Calcium Uniporter at the Whole-Cell and Single Mitochondrion Levels in WT, MICU1 KO, and MICU2 KO Cells. Cells 2020; 9:E1520. [PMID: 32580385 PMCID: PMC7349584 DOI: 10.3390/cells9061520] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 06/15/2020] [Accepted: 06/16/2020] [Indexed: 01/05/2023] Open
Abstract
Mitochondrial Ca2+ ([Ca2+]M) uptake through its Ca2+ uniporter (MCU) is central to many cell functions such as bioenergetics, spatiotemporal organization of Ca2+ signals, and apoptosis. MCU activity is regulated by several intrinsic proteins including MICU1, MICU2, and EMRE. While significant details about the role of MICU1, MICU2, and EMRE in MCU function have emerged recently, a key challenge for the future experiments is to investigate how these regulatory proteins modulate mitochondrial Ca2+ influx through MCU in intact cells under pathophysiological conditions. This is further complicated by the fact that several variables affecting MCU function change dynamically as cell functions. To overcome this void, we develop a data-driven model that closely replicates the behavior of MCU under a wide range of cytosolic Ca2+ ([Ca2+]C), [Ca2+]M, and mitochondrial membrane potential values in WT, MICU1 knockout (KO), and MICU2 KO cells at the single mitochondrion and whole-cell levels. The model is extended to investigate how MICU1 or MICU2 KO affect mitochondrial function. Moreover, we show how Ca2+ buffering proteins, the separation between mitochondrion and Ca2+-releasing stores, and the duration of opening of Ca2+-releasing channels affect mitochondrial function under different conditions. Finally, we demonstrate an easy extension of the model to single channel function of MCU.
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Affiliation(s)
| | - Ghanim Ullah
- Department of Physics, University of South Florida, Tampa, FL 33647, USA;
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Abstract
The junctional SRs (JSR) in skeletal and cardiac muscle in general, including extended junctional SR (EJSR) in avian hearts, are morphologic and functional homologies as shown by biochemical and morphometric evidence, including the recent demonstration that EJSR contains ryanodine receptors and binds [3H]-Ryanodine. Bird hearts have two aberrant membrane features: 1. absence of transverse tu-bules (TT) and, 2. extension of JSRs (thus: E-JSR) from peripheral couplings into the interior of the myocytes forming EJSR Z-retes that both surround and pervade Z-discs. Absence of TT calls for an alternative mechanism for global muscle activation in bird hearts for which EJSR may provide the anatomical substratum, a possibility supported by both experimental evidence, and recent theoretical considerations. Propagated calcium-induced calcium release (CICR) has been difficult to reconcile with the graded response of cardiac muscle to stimulation.2,cf.5Propagation of an action potential along the Z-retes can be excluded. In the absence of TT, saltatory CICR as an alternative to propagated cardiac activation, is made plausible by the existence of EJSR which, (a) is demonstrably calcium-sensitive, (b) is well within < than 0.5μm of the regulatory proteins of cardiac myocytes and, (c) carries rows of proven, vicinal calcium release channels.
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61
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Naik PA. Modeling the mechanics of calcium regulation in T lymphocyte: A finite element method approach. INT J BIOMATH 2020. [DOI: 10.1142/s1793524520500382] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Changes in cellular Ca[Formula: see text] concentration control a variety of physiological activities including hormone and neurotransmitter release, muscular contraction, synaptic plasticity, ionic channel permeability, apoptosis, enzyme activity, gene transcription and reproduction process. Spatial–temporal Ca[Formula: see text] dynamics due to Ca[Formula: see text] release, buffering and re-uptaking plays a central role in studying the Ca[Formula: see text] regulation in T lymphocytes. In most cases, Ca[Formula: see text] has its major signaling function when it is elevated in the cytosolic compartment. In this paper, a two-dimensional mathematical model to study spatiotemporal variations of intracellular Ca[Formula: see text] concentration in T lymphocyte cell is proposed and investigated. The cell is assumed to be a circular shaped geometrical domain for the representation of properties of Ca[Formula: see text] dynamics within the cell including important parameters. Ca[Formula: see text] binding proteins for the dynamics of Ca[Formula: see text] are itself buffer and other physiological parameters located in Ca[Formula: see text] stores. The model incorporates the important biophysical processes like diffusion, reaction, voltage-gated Ca[Formula: see text] channel, leak from endoplasmic reticulum (ER), efflux from cytosol to ER via sarco–ER Ca[Formula: see text] adenosine triphosphate (SERCA) pumps, buffers and Na[Formula: see text] exchanger. The proposed mathematical model is solved using a finite difference method and the finite element method. Appropriate initial and boundary conditions are incorporated in the model based on biophysical conditions of the problem. Computer simulations in MATLAB R2019b are employed to investigate mathematical models of reaction–diffusion equation. The effect of source, buffer, Na[Formula: see text]/Ca[Formula: see text] exchanger, etc. on spatial and temporal patterns of Ca[Formula: see text] in T lymphocyte has been studied with the help of numerical results. From the obtained results, it is observed that, the coordinated combination of the incorporated parameters plays a significant role in Ca[Formula: see text] regulation in T lymphocytes. ER leak and voltage-gated Ca[Formula: see text] channel provides the necessary Ca[Formula: see text] to the cell when required for its proper functioning, while on the other side buffers, SERCA pump and Na[Formula: see text]/Ca[Formula: see text] exchanger makes balance in the Ca[Formula: see text] concentration, so as to prevent the cell from death as higher concentration for longer time is harmful for the cell and can cause cell death.
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Affiliation(s)
- Parvaiz Ahmad Naik
- School of Mathematics and Statistics, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, P. R. China
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62
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Lock JT, Parker I. IP 3 mediated global Ca 2+ signals arise through two temporally and spatially distinct modes of Ca 2+ release. eLife 2020; 9:e55008. [PMID: 32396066 PMCID: PMC7253181 DOI: 10.7554/elife.55008] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 05/12/2020] [Indexed: 12/13/2022] Open
Abstract
The 'building-block' model of inositol trisphosphate (IP3)-mediated Ca2+ liberation posits that cell-wide cytosolic Ca2+ signals arise through coordinated activation of localized Ca2+ puffs generated by stationary clusters of IP3 receptors (IP3Rs). Here, we revise this hypothesis, applying fluctuation analysis to resolve Ca2+ signals otherwise obscured during large Ca2+ elevations. We find the rising phase of global Ca2+ signals is punctuated by a flurry of puffs, which terminate before the peak by a mechanism involving partial ER Ca2+ depletion. The continuing rise in Ca2+, and persistence of global signals even when puffs are absent, reveal a second mode of spatiotemporally diffuse Ca2+ signaling. Puffs make only small, transient contributions to global Ca2+ signals, which are sustained by diffuse release of Ca2+ through a functionally distinct process. These two modes of IP3-mediated Ca2+ liberation have important implications for downstream signaling, imparting spatial and kinetic specificity to Ca2+-dependent effector functions and Ca2+ transport.
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Affiliation(s)
- Jeffrey T Lock
- Department of Neurobiology & Behavior, UC IrvineIrvineUnited States
| | - Ian Parker
- Department of Neurobiology & Behavior, UC IrvineIrvineUnited States
- Department of Physiology & Biophysics, UC IrvineIrvineUnited States
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63
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Naik PA, Zu J. Modeling and simulation of spatial-temporal calcium distribution in T lymphocyte cell by using a reaction-diffusion equation. J Bioinform Comput Biol 2020; 18:2050013. [PMID: 32372713 DOI: 10.1142/s0219720020500134] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
T lymphocytes are white blood cells that play a central role in cell-mediated immunity. Ca2+ has its major signaling function when it is elevated in the cytosolic compartment. The free cytosolic Ca2+ dynamics plays a very important role in the activation, and fate decision process in the T lymphocytes. Here, we develop a quantitative spatio-temporal Ca2+ dynamic model which includes, the Ca2+ releasing channels ER leak and voltage-gated Ca2+ channel, buffering and re-uptaking mechanism in the T lymphocytes. In this model, the cell is represented as a circular-shaped geometrical domain. This representation introduces modeling flexibility needed for detailed representation of the properties of Ca2+ dynamics in the cell including important parameters. The proposed mathematical model is solved using a finite difference method and the finite element method. Appropriate initial and boundary conditions are incorporated in the model based on biophysical conditions of the problem. Computer simulations in MATLAB R2010a are employed to investigate mathematical models of reaction-diffusion equation. The estimation is based on reaction-diffusion equation associated with biophysical and biochemical reactions taking place in the cell. From our results, it is observed that, the coordinated combination of the incorporated parameters plays a significant role in Ca2+ regulation in T lymphocytes. ER leak and voltage-gated Ca2+ channel provides the necessary Ca2+ to the cell when required for its proper functioning, while on the other side buffers and Na+/Ca2+ exchanger makes balance in the Ca2+ concentration, so as to prevent the cell from death as higher concentration for longer time is harmful for the cell and can cause cell death. These results have been used to study the relationship of Ca2+ concentration with parameters like VGCC, Na+/Ca2+ exchanger, ER leak and buffers. The significance of the study reveals that there is a significant variation in Ca2+ profiles due to the effect of VGCC, Na+/Ca2+ exchanger, ER leak, and buffers. The results give us better insights of coordinated effect of VGCC, Na+/Ca2+ exchanger, ER leak, and buffers on Ca2+ distribution in T lymphocytes. T lymphocytes are the primary host cells to receive the viral infections which transmits the signal then to other cell types. The proper quantity of Ca2+ concentration makes T lymphocytes more active and healthier to fight the infection properly and can protect the immune system from various fatal viral infections. Thus, the application of the study lies in the field of immunology to protect a susceptible from various viral infectious diseases like HIV, HBV, HINI, etc. by strengthening the immune system. The outcomes of the study reveal that the applied finite element method is computationally very strong and effective to analyze differential equations that arise in Ca2+ dynamics.
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Affiliation(s)
- Parvaiz Ahmad Naik
- School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P. R. China
| | - Jian Zu
- School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, P. R. China
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64
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Lemmey HAL, Garland CJ, Dora KA. Intrinsic regulation of microvascular tone by myoendothelial feedback circuits. CURRENT TOPICS IN MEMBRANES 2020; 85:327-355. [PMID: 32402644 DOI: 10.1016/bs.ctm.2020.01.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The endothelium is an important regulator of arterial vascular tone, acting to release nitric oxide (NO) and open Ca2+-activated K+ (KCa) channels to relax vascular smooth muscle cells (VSMCs). While agonists acting at endothelial cell (EC) receptors are widely used to assess the ability of the endothelium to reduce vascular tone, the intrinsic EC-dependent mechanisms are less well characterized. In small resistance arteries and arterioles, the presence of heterocellular gap junctions termed myoendothelial gap junctions (MEGJs) allows the passage of not only current, but small molecules including Ca2+ and inositol trisphosphate (IP3). When stimulated to contract, the increase in VSM Ca2+ and IP3 can therefore potentially pass through MEGJs to activate adjacent ECs. This activation releases NO and opens KCa channels, which act to limit contraction. This myoendothelial feedback (MEF) is amplified by EC Ca2+ influx and release pathways, and is dynamically modulated by processes regulating gap junction conductance. There is a remarkable localization of key signaling and regulatory proteins within the EC projection toward VSM, and the intrinsic EC-dependent signaling pathways occurring with this highly specialized microdomain are reviewed.
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Affiliation(s)
- Hamish A L Lemmey
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | | | - Kim A Dora
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom.
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65
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Kobbersmed JR, Grasskamp AT, Jusyte M, Böhme MA, Ditlevsen S, Sørensen JB, Walter AM. Rapid regulation of vesicle priming explains synaptic facilitation despite heterogeneous vesicle:Ca 2+ channel distances. eLife 2020; 9:51032. [PMID: 32077852 PMCID: PMC7145420 DOI: 10.7554/elife.51032] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 02/14/2020] [Indexed: 12/27/2022] Open
Abstract
Chemical synaptic transmission relies on the Ca2+-induced fusion of transmitter-laden vesicles whose coupling distance to Ca2+ channels determines synaptic release probability and short-term plasticity, the facilitation or depression of repetitive responses. Here, using electron- and super-resolution microscopy at the Drosophila neuromuscular junction we quantitatively map vesicle:Ca2+ channel coupling distances. These are very heterogeneous, resulting in a broad spectrum of vesicular release probabilities within synapses. Stochastic simulations of transmitter release from vesicles placed according to this distribution revealed strong constraints on short-term plasticity; particularly facilitation was difficult to achieve. We show that postulated facilitation mechanisms operating via activity-dependent changes of vesicular release probability (e.g. by a facilitation fusion sensor) generate too little facilitation and too much variance. In contrast, Ca2+-dependent mechanisms rapidly increasing the number of releasable vesicles reliably reproduce short-term plasticity and variance of synaptic responses. We propose activity-dependent inhibition of vesicle un-priming or release site activation as novel facilitation mechanisms. Cells in the nervous system of all animals communicate by releasing and sensing chemicals at contact points named synapses. The ‘talking’ (or pre-synaptic) cell stores the chemicals close to the synapse, in small spheres called vesicles. When the cell is activated, calcium ions flow in and interact with the release-ready vesicles, which then spill the chemicals into the synapse. In turn, the ‘listening’ (or post-synaptic) cell can detect the chemicals and react accordingly. When the pre-synaptic cell is activated many times in a short period, it can release a greater quantity of chemicals, allowing a bigger reaction in the post-synaptic cell. This phenomenon is known as facilitation, but it is still unclear how exactly it can take place. This is especially the case when many of the vesicles are not ready to respond, for example when they are too far from where calcium flows into the cell. Computer simulations have been created to model facilitation but they have assumed that all vesicles are placed at the same distance to the calcium entry point: Kobbersmed et al. now provide evidence that this assumption is incorrect. Two high-resolution imaging techniques were used to measure the actual distances between the vesicles and the calcium source in the pre-synaptic cells of fruit flies: this showed that these distances are quite variable – some vesicles sit much closer to the source than others. This information was then used to create a new computer model to simulate facilitation. The results from this computing work led Kobbersmed et al. to suggest that facilitation may take place because a calcium-based mechanism in the cell increases the number of vesicles ready to release their chemicals. This new model may help researchers to better understand how the cells in the nervous system work. Ultimately, this can guide experiments to investigate what happens when information processing at synapses breaks down, for example in diseases such as epilepsy.
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Affiliation(s)
- Janus Rl Kobbersmed
- Department of Mathematical Sciences, University of Copenhagen, København, Denmark.,Department of Neuroscience, University of Copenhagen, København, Denmark
| | - Andreas T Grasskamp
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, FMP im CharitéCrossOver, Berlin, Germany
| | - Meida Jusyte
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, FMP im CharitéCrossOver, Berlin, Germany.,Einstein Center for Neuroscience, Berlin, Germany
| | - Mathias A Böhme
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, FMP im CharitéCrossOver, Berlin, Germany
| | - Susanne Ditlevsen
- Department of Mathematical Sciences, University of Copenhagen, København, Denmark
| | | | - Alexander M Walter
- Molecular and Theoretical Neuroscience, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, FMP im CharitéCrossOver, Berlin, Germany.,Einstein Center for Neuroscience, Berlin, Germany
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66
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Li L, Lai M, Cole S, Le Novère N, Edelstein SJ. Neurogranin stimulates Ca2+/calmodulin-dependent kinase II by suppressing calcineurin activity at specific calcium spike frequencies. PLoS Comput Biol 2020; 16:e1006991. [PMID: 32049957 PMCID: PMC7041932 DOI: 10.1371/journal.pcbi.1006991] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 02/25/2020] [Accepted: 11/18/2019] [Indexed: 11/18/2022] Open
Abstract
Calmodulin sits at the center of molecular mechanisms underlying learning and memory. Its complex and sometimes opposite influences, mediated via the binding to various proteins, are yet to be fully understood. Calcium/calmodulin-dependent protein kinase II (CaMKII) and calcineurin (CaN) both bind open calmodulin, favoring Long-Term Potentiation (LTP) or Depression (LTD) respectively. Neurogranin binds to the closed conformation of calmodulin and its impact on synaptic plasticity is less clear. We set up a mechanistic computational model based on allosteric principles to simulate calmodulin state transitions and its interactions with calcium ions and the three binding partners mentioned above. We simulated calcium spikes at various frequencies and show that neurogranin regulates synaptic plasticity along three modalities. At low spike frequencies, neurogranin inhibits the onset of LTD by limiting CaN activation. At intermediate frequencies, neurogranin facilitates LTD, but limits LTP by precluding binding of CaMKII with calmodulin. Finally, at high spike frequencies, neurogranin promotes LTP by enhancing CaMKII autophosphorylation. While neurogranin might act as a calmodulin buffer, it does not significantly preclude the calmodulin opening by calcium. On the contrary, neurogranin synchronizes the opening of calmodulin's two lobes and promotes their activation at specific frequencies. Neurogranin suppresses basal CaN activity, thus increasing the chance of CaMKII trans-autophosphorylation at high-frequency calcium spikes. Taken together, our study reveals dynamic regulatory roles played by neurogranin on synaptic plasticity, which provide mechanistic explanations for opposing experimental findings.
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Affiliation(s)
- Lu Li
- Babraham Institute, Cambridge, United Kingdom
| | - Massimo Lai
- Quantitative Systems Pharmacology, CERTARA, Canterbury, United Kingdom
| | - Stephen Cole
- Cambridge Systems Biology Centre, University of Cambridge, Cambridge, United Kingdom
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67
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Lagos-Cabré R, Burgos-Bravo F, Avalos AM, Leyton L. Connexins in Astrocyte Migration. Front Pharmacol 2020; 10:1546. [PMID: 32009957 PMCID: PMC6974553 DOI: 10.3389/fphar.2019.01546] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 11/29/2019] [Indexed: 12/18/2022] Open
Abstract
Astrocytes have long been considered the supportive cells of the central nervous system, but during the last decades, they have gained much more attention because of their active participation in the modulation of neuronal function. For example, after brain damage, astrocytes become reactive and undergo characteristic morphological and molecular changes, such as hypertrophy and increase in the expression of glial fibrillary acidic protein (GFAP), in a process known as astrogliosis. After severe damage, astrocytes migrate to the lesion site and proliferate, which leads to the formation of a glial scar. At this scar-forming stage, astrocytes secrete many factors, such as extracellular matrix proteins, cytokines, growth factors and chondroitin sulfate proteoglycans, stop migrating, and the process is irreversible. Although reactive gliosis is a normal physiological response that can protect brain cells from further damage, it also has detrimental effects on neuronal survival, by creating a hostile and non-permissive environment for axonal repair. The transformation of astrocytes from reactive to scar-forming astrocytes highlights migration as a relevant regulator of glial scar formation, and further emphasizes the importance of efficient communication between astrocytes in order to orchestrate cell migration. The coordination between astrocytes occurs mainly through Connexin (Cx) channels, in the form of direct cell-cell contact (gap junctions, GJs) or contact between the extracellular matrix and the astrocytes (hemichannels, HCs). Reactive astrocytes increase the expression levels of several proteins involved in astrocyte migration, such as αvβ3 Integrin, Syndecan-4 proteoglycan, the purinergic receptor P2X7, Pannexin1, and Cx43 HCs. Evidence has indicated that Cx43 HCs play a role in regulating astrocyte migration through the release of small molecules to the extracellular space, which then activate receptors in the same or adjacent cells to continue the signaling cascades required for astrocyte migration. In this review, we describe the communication of astrocytes through Cxs, the role of Cxs in inflammation and astrocyte migration, and discuss the molecular mechanisms that regulate Cx43 HCs, which may provide a therapeutic window of opportunity to control astrogliosis and the progression of neurodegenerative diseases.
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Affiliation(s)
- Raúl Lagos-Cabré
- Cellular Communication Laboratory, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Advanced Center for Chronic Diseases (ACCDiS), Center for Studies on Exercise, Metabolism and Cancer (CEMC), Facultad de Medicina, Instituto de Ciencias Biomédicas (ICBM), Universidad de Chile, Santiago, Chile
| | - Francesca Burgos-Bravo
- Cellular Communication Laboratory, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Advanced Center for Chronic Diseases (ACCDiS), Center for Studies on Exercise, Metabolism and Cancer (CEMC), Facultad de Medicina, Instituto de Ciencias Biomédicas (ICBM), Universidad de Chile, Santiago, Chile
| | - Ana María Avalos
- Facultad de Ciencias de la Salud, Instituto de Ciencias Biomédicas, Universidad Autónoma de Chile, Santiago, Chile
| | - Lisette Leyton
- Cellular Communication Laboratory, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas (ICBM), Facultad de Medicina, Universidad de Chile, Santiago, Chile.,Advanced Center for Chronic Diseases (ACCDiS), Center for Studies on Exercise, Metabolism and Cancer (CEMC), Facultad de Medicina, Instituto de Ciencias Biomédicas (ICBM), Universidad de Chile, Santiago, Chile
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68
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Schwaller B. Cytosolic Ca 2+ Buffers Are Inherently Ca 2+ Signal Modulators. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a035543. [PMID: 31308146 DOI: 10.1101/cshperspect.a035543] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
For precisely regulating intracellular Ca2+ signals in a time- and space-dependent manner, cells make use of various components of the "Ca2+ signaling toolkit," including Ca2+ entry and Ca2+ extrusion systems. A class of cytosolic Ca2+-binding proteins termed Ca2+ buffers serves as modulators of such, mostly short-lived Ca2+ signals. Prototypical Ca2+ buffers include parvalbumins (α and β isoforms), calbindin-D9k, calbindin-D28k, and calretinin. Although initially considered to function as pure Ca2+ buffers, that is, as intracellular Ca2+ signal modulators controlling the shape (amplitude, decay, spread) of Ca2+ signals, evidence has accumulated that calbindin-D28k and calretinin have additional Ca2+ sensor functions. These other functions are brought about by direct interactions with target proteins, thereby modulating their targets' function/activity. Dysregulation of Ca2+ buffer expression is associated with several neurologic/neurodevelopmental disorders including autism spectrum disorder (ASD) and schizophrenia. In some cases, the presence of these proteins is presumed to confer a neuroprotective effect, as evidenced in animal models of Parkinson's or Alzheimer's disease.
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Affiliation(s)
- Beat Schwaller
- Department of Anatomy, Section of Medicine, University of Fribourg, CH-1700 Fribourg, Switzerland
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69
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Mackrill JJ, Shiels HA. Evolution of Excitation-Contraction Coupling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:281-320. [DOI: 10.1007/978-3-030-12457-1_12] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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70
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Calpain Activation by Ca2+ and Its Role in Phagocytosis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1246:129-151. [DOI: 10.1007/978-3-030-40406-2_8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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71
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Gilabert JA. Cytoplasmic Calcium Buffering: An Integrative Crosstalk. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:163-182. [PMID: 31646510 DOI: 10.1007/978-3-030-12457-1_7] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Calcium (Ca2+) buffering is part of an integrative crosstalk between different mechanisms and elements involved in the control of free Ca2+ ions persistence in the cytoplasm and hence, in the Ca2+-dependence of many intracellular processes. Alterations of Ca2+ homeostasis and signaling from systemic to subcellular levels also play a pivotal role in the pathogenesis of many diseases.Compared with Ca2+ sequestration towards intracellular Ca2+ stores, Ca2+ buffering is a rapid process occurring in a subsecond scale. Any molecule (or binding site) with the ability to bind Ca2+ ions could be considered, at least in principle, as a buffer. However, the term Ca2+ buffer is applied only to a small subset of Ca2+ binding proteins containing acidic side-chain residues.Ca2+ buffering in the cytoplasm mainly relies on mobile and immobile or fixed buffers controlling the diffusion of free Ca2+ ions inside the cytosol both temporally and spatially. Mobility of buffers depends on their molecular weight, but other parameters as their concentration, affinity for Ca2+ or Ca2+ binding and dissociation kinetics next to their diffusional mobility also contribute to make Ca2+ signaling one of the most complex signaling activities of the cell.The crosstalk between all the elements involved in the intracellular Ca2+ dynamics is a process of extreme complexity due to the diversity of structural and molecular elements involved but permit a highly regulated spatiotemporal control of the signal mediated by Ca2+ ions. The basis of modeling tools to study Ca2+ dynamics are also presented.
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Affiliation(s)
- Juan A Gilabert
- Department of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Complutense University of Madrid, Madrid, Spain.
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72
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Tonic Activation of Extrasynaptic NMDA Receptors Decreases Intrinsic Excitability and Promotes Bistability in a Model of Neuronal Activity. Int J Mol Sci 2019; 21:ijms21010206. [PMID: 31892239 PMCID: PMC6982144 DOI: 10.3390/ijms21010206] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 12/20/2019] [Accepted: 12/24/2019] [Indexed: 01/22/2023] Open
Abstract
NMDA receptors (NMDA-R) typically contribute to excitatory synaptic transmission in the central nervous system. While calcium influx through NMDA-R plays a critical role in synaptic plasticity, experimental evidence indicates that NMDAR-mediated calcium influx also modifies neuronal excitability through the activation of calcium-activated potassium channels. This mechanism has not yet been studied theoretically. Our theoretical model provides a simple description of neuronal electrical activity that takes into account the tonic activity of extrasynaptic NMDA receptors and a cytosolic calcium compartment. We show that calcium influx mediated by the tonic activity of NMDA-R can be coupled directly to the activation of calcium-activated potassium channels, resulting in an overall inhibitory effect on neuronal excitability. Furthermore, the presence of tonic NMDA-R activity promotes bistability in electrical activity by dramatically increasing the stimulus interval where both a stable steady state and repetitive firing can coexist. These results could provide an intrinsic mechanism for the constitution of memory traces in neuronal circuits. They also shed light on the way by which β-amyloids can alter neuronal activity when interfering with NMDA-R in Alzheimer’s disease and cerebral ischemia.
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73
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Bradshaw-Hajek BH, Broadbridge P. Analytic solutions for calcium ion fertilisation waves on the surface of eggs. MATHEMATICAL MEDICINE AND BIOLOGY-A JOURNAL OF THE IMA 2019; 36:549-562. [PMID: 30767020 DOI: 10.1093/imammb/dqz002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 12/12/2018] [Accepted: 12/12/2019] [Indexed: 11/15/2022]
Abstract
The evolution of calcium fertilisation waves on the cortex of amphibian eggs can be described by a nonlinear reaction-diffusion process on the surface of a sphere. Here, we use the nonclassical symmetry technique to find an exact analytic solution that describes the evolution of the calcium concentration. The solutions presented compare well with published experimental results. The analytic solution can be used to give insight into the processes governing the fertilisation wave, such as the flow of calcium ions from the sperm entry point. By finding a spiral solution to an approximate equation linearised near saturation, we also demonstrate how solutions with other properties may be constructed using this technique.
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Affiliation(s)
- Bronwyn H Bradshaw-Hajek
- School of Information Technology and Mathematical Sciences, University of South Australia, Mawson Lakes, SA, Australia
| | - Philip Broadbridge
- Department of Mathematics and Statistics, La Trobe University, Victoria, Australia
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74
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Cao X, Chen J, Li D, Xie P, Xu M, Lin W, Li S, Pan G, Tang Y, Xu J, Olkkonen VM, Yan D, Zhong W. ORP4L couples IP 3 to ITPR1 in control of endoplasmic reticulum calcium release. FASEB J 2019; 33:13852-13865. [PMID: 31648575 DOI: 10.1096/fj.201900933rr] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Oxysterol-binding protein-related protein (ORP) 4L acts as a scaffold protein assembling CD3-ε, G-αq/11, and PLC-β3 into a complex at the plasma membrane that mediates inositol (1,4,5)-trisphosphate (IP3)-induced endoplasmic reticulum (ER) Ca2+ release and oxidative phosphorylation in T-cell acute lymphoblastic leukemia cells. Here, we offer new evidence that ORP4L interacts with the carboxyl terminus of the IP3 receptor type 1 (ITPR1) in Jurkat T cells. ORP4L enables IP3 binding to ITPR1; a truncated construct that lacks the ITPR1-binding region retains the ability to increase IP3 production but fails to mediate IP3 and ITPR1 binding. In association with this ability of ORP4L, it enhances Ca2+ release from the ER and subsequent cytosolic and mitochondrial parallel Ca2+ spike oscillations that stimulate mitochondrial energetics and thus maintains cell survival. These data support a novel model in which ORP4L is a cofactor of ITPR1, which increases ITPR1 sensitivity to IP3 and enables ER Ca2+ release.-Cao, X., Chen, J., Li, D., Xie, P., Xu, M., Lin, W., Li, S., Pan, G., Tang, Y., Xu, J., Olkkonen, V. M., Yan, D., Zhong, W. ORP4L couples IP3 to ITPR1 in control of endoplasmic reticulum calcium release.
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Affiliation(s)
- Xiuye Cao
- Department of Biology, Jinan University, Guangzhou, China
| | - Jianuo Chen
- Department of Biology, Jinan University, Guangzhou, China
| | - Dan Li
- Department of Biology, Jinan University, Guangzhou, China
| | - Peipei Xie
- Department of Biology, Jinan University, Guangzhou, China
| | - Mengyang Xu
- Department of Biology, Jinan University, Guangzhou, China
| | - Weize Lin
- Department of Biology, Jinan University, Guangzhou, China
| | - Shiqian Li
- Department of Biology, Jinan University, Guangzhou, China
| | - Guoping Pan
- Department of Biology, Jinan University, Guangzhou, China
| | - Yong Tang
- Department of Biology, Jinan University, Guangzhou, China
| | - Jun Xu
- Research Center for Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, China
| | - Vesa M Olkkonen
- Minerva Foundation Institute for Medical Research, Biomedicum Helsinki 2U, Helsinki, Finland
| | - Daoguang Yan
- Department of Biology, Jinan University, Guangzhou, China
| | - Wenbin Zhong
- Department of Biology, Jinan University, Guangzhou, China
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75
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Nakamura Y. EGTA Can Inhibit Vesicular Release in the Nanodomain of Single Ca 2+ Channels. Front Synaptic Neurosci 2019; 11:26. [PMID: 31632263 PMCID: PMC6779814 DOI: 10.3389/fnsyn.2019.00026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 09/02/2019] [Indexed: 01/21/2023] Open
Abstract
The exogenous Ca2+ chelator EGTA (ethylene glycol tetraacetic acid) has been widely used to probe the coupling distance between Ca2+ channels and vesicular Ca2+ sensors for neurotransmitter release. Because of its slow forward rate for binding, EGTA is thought to not capture calcium ions in very proximity to a channel, whereas it does capture calcium ions at the remote distance. However, in this study, our reaction diffusion simulations (RDSs) of Ca2+ combined with a release calculation using vesicular sensor models indicate that a high concentration of EGTA decreases Ca2+ and vesicular release in the nanodomain of single channels. We found that a key determinant of the effect of EGTA on neurotransmitter release is the saturation of the vesicular sensor. When the sensor is saturated, the reduction in the Ca2+ concentration by EGTA is masked. By contrast, when the sensor is in a linear range, even a small reduction in Ca2+ by EGTA can decrease vesicular release. In proximity to a channel, the vesicular sensor is often saturated for a long voltage step, but not for a brief Ca2+ influx typically evoked by an action potential. Therefore, when EGTA is used as a diagnostic tool to probe the coupling distance, care must be taken regarding the presynaptic Ca2+ entry duration as well as the property of the vesicular Ca2+ sensor.
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Affiliation(s)
- Yukihiro Nakamura
- Department of Pharmacology, Jikei University School of Medicine, Tokyo, Japan
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76
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Quantitation and Simulation of Single Action Potential-Evoked Ca 2+ Signals in CA1 Pyramidal Neuron Presynaptic Terminals. eNeuro 2019; 6:ENEURO.0343-19.2019. [PMID: 31551250 PMCID: PMC6800293 DOI: 10.1523/eneuro.0343-19.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 09/10/2019] [Indexed: 01/07/2023] Open
Abstract
Presynaptic Ca2+ evokes exocytosis, endocytosis, and synaptic plasticity. However, Ca2+ flux and interactions at presynaptic molecular targets are difficult to quantify because fluorescence imaging has limited resolution. In rats of either sex, we measured single varicosity presynaptic Ca2+ using Ca2+ dyes as buffers, and constructed models of Ca2+ dispersal. Action potentials evoked Ca2+ transients with little variation when measured with low-affinity dye (peak amplitude 789 ± 39 nM, within 2 ms of stimulation; decay times, 119 ± 10 ms). Endogenous Ca2+ buffering capacity, action potential-evoked free [Ca2+]i, and total Ca2+ amounts entering terminals were determined using Ca2+ dyes as buffers. These data constrained Monte Carlo (MCell) simulations of Ca2+ entry, buffering, and removal. Simulations of experimentally-determined Ca2+ fluxes, buffered by simulated calbindin28K well fit data, and were consistent with clustered Ca2+ entry followed within 4 ms by diffusion throughout the varicosity. Repetitive stimulation caused free varicosity Ca2+ to sum. However, simulated in nanometer domains, its removal by pumps and buffering was negligible, while local diffusion dominated. Thus, Ca2+ within tens of nanometers of entry, did not accumulate. A model of synaptotagmin1 (syt1)-Ca2+ binding indicates that even with 10 µM free varicosity evoked Ca2+, syt1 must be within tens of nanometers of channels to ensure occupation of all its Ca2+-binding sites. Repetitive stimulation, evoking short-term synaptic enhancement, does not modify probabilities of Ca2+ fully occupying syt1’s C2 domains, suggesting that enhancement is not mediated by Ca2+-syt1 interactions. We conclude that at spatiotemporal scales of fusion machines, Ca2+ necessary for their activation is diffusion dominated.
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77
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Verkhratsky A, Parpura V, Vardjan N, Zorec R. Physiology of Astroglia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1175:45-91. [PMID: 31583584 DOI: 10.1007/978-981-13-9913-8_3] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Astrocytes are principal cells responsible for maintaining the brain homeostasis. Additionally, these glial cells are also involved in homocellular (astrocyte-astrocyte) and heterocellular (astrocyte-other cell types) signalling and metabolism. These astroglial functions require an expression of the assortment of molecules, be that transporters or pumps, to maintain ion concentration gradients across the plasmalemma and the membrane of the endoplasmic reticulum. Astrocytes sense and balance their neurochemical environment via variety of transmitter receptors and transporters. As they are electrically non-excitable, astrocytes display intracellular calcium and sodium fluctuations, which are not only used for operative signalling but can also affect metabolism. In this chapter we discuss the molecules that achieve ionic gradients and underlie astrocyte signalling.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK. .,Faculty of Health and Medical Sciences, Center for Basic and Translational Neuroscience, University of Copenhagen, 2200, Copenhagen, Denmark. .,Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain.
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Nina Vardjan
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
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78
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Dingreville F, Panthu B, Thivolet C, Ducreux S, Gouriou Y, Pesenti S, Chauvin MA, Chikh K, Errazuriz-Cerda E, Van Coppenolle F, Rieusset J, Madec AM. Differential Effect of Glucose on ER-Mitochondria Ca 2+ Exchange Participates in Insulin Secretion and Glucotoxicity-Mediated Dysfunction of β-Cells. Diabetes 2019; 68:1778-1794. [PMID: 31175102 DOI: 10.2337/db18-1112] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 06/04/2019] [Indexed: 11/13/2022]
Abstract
Glucotoxicity-induced β-cell dysfunction in type 2 diabetes is associated with alterations of mitochondria and the endoplasmic reticulum (ER). Both organelles interact at contact sites, defined as mitochondria-associated membranes (MAMs), which were recently implicated in the regulation of glucose homeostasis. The role of MAMs in β-cells is still largely unknown, and their implication in glucotoxicity-associated β-cell dysfunction remains to be defined. Here, we report that acute glucose treatment stimulated ER-mitochondria interactions and calcium (Ca2+) exchange in INS-1E cells, whereas disruption of MAMs altered glucose-stimulated insulin secretion (GSIS). Conversely, chronic incubations with high glucose of either INS-1E cells or human pancreatic islets altered GSIS and concomitantly reduced ER Ca2+ store, increased basal mitochondrial Ca2+, and reduced ATP-stimulated ER-mitochondria Ca2+ exchanges, despite an increase of organelle interactions. Furthermore, glucotoxicity-induced perturbations of Ca2+ signaling are associated with ER stress, altered mitochondrial respiration, and mitochondria fragmentation, and these organelle stresses may participate in increased organelle tethering as a protective mechanism. Last, sustained induction of ER-mitochondria interactions using a linker reduced organelle Ca2+ exchange, induced mitochondrial fission, and altered GSIS. Therefore, dynamic organelle coupling participates in GSIS in β-cells, and over time, disruption of organelle Ca2+ exchange might be a novel mechanism contributing to glucotoxicity-induced β-cell dysfunction.
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Affiliation(s)
- Florian Dingreville
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
| | - Baptiste Panthu
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
| | - Charles Thivolet
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
- Department of Endocrinology and Diabetes, Hospices Civils de Lyon, Hopital Lyon Sud, Pierre-Bénite, France
| | - Sylvie Ducreux
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
| | - Yves Gouriou
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
| | - Sandra Pesenti
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
| | - Marie-Agnès Chauvin
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
| | - Karim Chikh
- Department of Endocrinology and Diabetes, Hospices Civils de Lyon, Hopital Lyon Sud, Pierre-Bénite, France
| | | | - Fabien Van Coppenolle
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
| | - Jennifer Rieusset
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
| | - Anne-Marie Madec
- CarMeN Laboratory, INSERM, INRA, INSA, Université Claude Bernard Lyon 1, Oullins, France
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79
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Cugno A, Bartol TM, Sejnowski TJ, Iyengar R, Rangamani P. Geometric principles of second messenger dynamics in dendritic spines. Sci Rep 2019; 9:11676. [PMID: 31406140 PMCID: PMC6691135 DOI: 10.1038/s41598-019-48028-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 07/29/2019] [Indexed: 01/27/2023] Open
Abstract
Dendritic spines are small, bulbous protrusions along dendrites in neurons and play a critical role in synaptic transmission. Dendritic spines come in a variety of shapes that depend on their developmental state. Additionally, roughly 14-19% of mature spines have a specialized endoplasmic reticulum called the spine apparatus. How does the shape of a postsynaptic spine and its internal organization affect the spatio-temporal dynamics of short timescale signaling? Answers to this question are central to our understanding the initiation of synaptic transmission, learning, and memory formation. In this work, we investigated the effect of spine and spine apparatus size and shape on the spatio-temporal dynamics of second messengers using mathematical modeling using reaction-diffusion equations in idealized geometries (ellipsoids, spheres, and mushroom-shaped). Our analyses and simulations showed that in the short timescale, spine size and shape coupled with the spine apparatus geometries govern the spatiotemporal dynamics of second messengers. We show that the curvature of the geometries gives rise to pseudo-harmonic functions, which predict the locations of maximum and minimum concentrations along the spine head. Furthermore, we showed that the lifetime of the concentration gradient can be fine-tuned by localization of fluxes on the spine head and varying the relative curvatures and distances between the spine apparatus and the spine head. Thus, we have identified several key geometric determinants of how the spine head and spine apparatus may regulate the short timescale chemical dynamics of small molecules that control synaptic plasticity.
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Affiliation(s)
- Andrea Cugno
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, 92093-0411, CA, United States
| | - Thomas M Bartol
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Terrence J Sejnowski
- Howard Hughes Medical Institute, Salk Institute for Biological Studies, La Jolla, CA, USA
- Division of Biological Sciences, University of California, San Diego, San Diego, CA, USA
| | - Ravi Iyengar
- Department of Pharmacological Sciences and Systems Biology Center New York, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, 92093-0411, CA, United States.
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80
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Denizot A, Arizono M, Nägerl UV, Soula H, Berry H. Simulation of calcium signaling in fine astrocytic processes: Effect of spatial properties on spontaneous activity. PLoS Comput Biol 2019; 15:e1006795. [PMID: 31425510 PMCID: PMC6726244 DOI: 10.1371/journal.pcbi.1006795] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 09/04/2019] [Accepted: 07/08/2019] [Indexed: 12/20/2022] Open
Abstract
Astrocytes, a glial cell type of the central nervous system, have emerged as detectors and regulators of neuronal information processing. Astrocyte excitability resides in transient variations of free cytosolic calcium concentration over a range of temporal and spatial scales, from sub-microdomains to waves propagating throughout the cell. Despite extensive experimental approaches, it is not clear how these signals are transmitted to and integrated within an astrocyte. The localization of the main molecular actors and the geometry of the system, including the spatial organization of calcium channels IP3R, are deemed essential. However, as most calcium signals occur in astrocytic ramifications that are too fine to be resolved by conventional light microscopy, most of those spatial data are unknown and computational modeling remains the only methodology to study this issue. Here, we propose an IP3R-mediated calcium signaling model for dynamics in such small sub-cellular volumes. To account for the expected stochasticity and low copy numbers, our model is both spatially explicit and particle-based. Extensive simulations show that spontaneous calcium signals arise in the model via the interplay between excitability and stochasticity. The model reproduces the main forms of calcium signals and indicates that their frequency crucially depends on the spatial organization of the IP3R channels. Importantly, we show that two processes expressing exactly the same calcium channels can display different types of calcium signals depending on the spatial organization of the channels. Our model with realistic process volume and calcium concentrations successfully reproduces spontaneous calcium signals that we measured in calcium micro-domains with confocal microscopy and predicts that local variations of calcium indicators might contribute to the diversity of calcium signals observed in astrocytes. To our knowledge, this model is the first model suited to investigate calcium dynamics in fine astrocytic processes and to propose plausible mechanisms responsible for their variability.
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Affiliation(s)
- Audrey Denizot
- INRIA, F-69603, Villeurbanne, France
- Univ Lyon, LIRIS, UMR5205 CNRS, F-69621, Villeurbanne, France
| | - Misa Arizono
- Interdisciplinary Institute for Neuroscience, Université de Bordeaux, Bordeaux, France
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France
| | - U. Valentin Nägerl
- Interdisciplinary Institute for Neuroscience, Université de Bordeaux, Bordeaux, France
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France
| | - Hédi Soula
- INRIA, F-69603, Villeurbanne, France
- Univ P&M Curie, CRC, INSERM UMRS 1138, F-75006, Paris, France
| | - Hugues Berry
- INRIA, F-69603, Villeurbanne, France
- Univ Lyon, LIRIS, UMR5205 CNRS, F-69621, Villeurbanne, France
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81
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Singh N, Adlakha N. A mathematical model for interdependent calcium and inositol 1,4,5-trisphosphate in cardiac myocyte. ACTA ACUST UNITED AC 2019. [DOI: 10.1007/s13721-019-0198-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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82
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Hu SW, Wang J, Zhang TT, Li XL, Chen HY, Xu JJ. Targeted Transmembrane Delivery of Ca 2+ via FA-Nanogel for Synergistically Enhanced Chemotherapy. ACS APPLIED MATERIALS & INTERFACES 2019; 11:16412-16420. [PMID: 30990307 DOI: 10.1021/acsami.9b04967] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Metal ion synergistically enhanced chemotherapy is a promising strategy for cancer treatment. However, targeting delivery of ions toward cancer cells remains challenging for decades. Herein, we developed a novel folic acid-nanogel (termed as FA-nanogel) with alkane chains as diffusion barriers for targeted transmembrane delivery of calcium ions into cancer cells. With the aid of hydrophobic diffusion barriers, the FA-nanogel showed a reduced and sustained speed for release of calcium ions, significantly prolonging the ion effect. Moreover, a pH-sensitive injectable hydrogel-loaded FA-nanogel and chemotherapeutic drug 5-fluorouracil (5-Fu) was synthesized for investigating the synergistic effect of nanogel on chemotherapy. Both in vitro and in vivo experiments confirmed that the intracellular calcium ions were continuously increased because of the targeted delivery ability and ion sustained release ability of the smart FA-nanogel, and the tumor growth was effectively inhibited by the ion synergistic chemotherapy. This study not only provides a powerful nanoplatform for sustained transmembrane delivery of ions into malignant cells but also creates better conditions for improving the therapeutic efficacy of chemotherapy.
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Affiliation(s)
- Shan-Wen Hu
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China
- Shandong Provincial Key Laboratory of Detection Technology for Tumor Markers, College of Chemistry and Chemical Engineering , Linyi University , Linyi 276005 , China
| | - Jin Wang
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Ting-Ting Zhang
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Xiang-Ling Li
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Hong-Yuan Chen
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China
| | - Jing-Juan Xu
- State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering , Nanjing University , Nanjing 210023 , China
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83
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Taylor CW, Machaca K. IP3 receptors and store-operated Ca2+ entry: a license to fill. Curr Opin Cell Biol 2019; 57:1-7. [DOI: 10.1016/j.ceb.2018.10.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 10/05/2018] [Indexed: 10/28/2022]
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84
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Prole DL, Taylor CW. Structure and Function of IP 3 Receptors. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a035063. [PMID: 30745293 DOI: 10.1101/cshperspect.a035063] [Citation(s) in RCA: 107] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Inositol 1,4,5-trisphosphate receptors (IP3Rs), by releasing Ca2+ from the endoplasmic reticulum (ER) of animal cells, allow Ca2+ to be redistributed from the ER to the cytosol or other organelles, and they initiate store-operated Ca2+ entry (SOCE). For all three IP3R subtypes, binding of IP3 primes them to bind Ca2+, which then triggers channel opening. We are now close to understanding the structural basis of IP3R activation. Ca2+-induced Ca2+ release regulated by IP3 allows IP3Rs to regeneratively propagate Ca2+ signals. The smallest of these regenerative events is a Ca2+ puff, which arises from the nearly simultaneous opening of a small cluster of IP3Rs. Ca2+ puffs are the basic building blocks for all IP3-evoked Ca2+ signals, but only some IP3 clusters, namely those parked alongside the ER-plasma membrane junctions where SOCE occurs, are licensed to respond. The location of these licensed IP3Rs may allow them to selectively regulate SOCE.
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Affiliation(s)
- David L Prole
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, United Kingdom
| | - Colin W Taylor
- Department of Pharmacology, University of Cambridge, Cambridge CB2 1PD, United Kingdom
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85
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Okubo Y, Iino M. Visualization of astrocytic intracellular Ca 2+ mobilization. J Physiol 2019; 598:1671-1681. [PMID: 30825213 DOI: 10.1113/jp277609] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Accepted: 02/06/2019] [Indexed: 11/08/2022] Open
Abstract
Astrocytes generate robust intracellular Ca2+ concentration changes (Ca2+ signals), which are assumed to regulate astrocytic functions that play crucial roles in the regulation of brain functions. One frequently used strategy for exploring the role of astrocytic Ca2+ signalling is the use of mice deficient in the type 2 inositol 1,4,5-trisphosphate receptor (IP3 R2). These IP3 R2-knockout (KO) mice are reportedly devoid of Ca2+ mobilization from the endoplasmic reticulum (ER) in astrocytes. However, they have shown no functional deficits in several studies, causing a heated debate as to the functional relevance of ER-mediated Ca2+ signalling in astrocytes. Recently, the assumption that Ca2+ mobilization from the ER is absent in IP3 R2-KO astrocytes has been re-evaluated using intraorganellar Ca2+ imaging techniques. The new results indicated that IP3 R2-independent Ca2+ release may generate Ca2+ nanodomains around the ER, which may help explain the absence of functional deficits in IP3 R2-KO mice.
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Affiliation(s)
- Yohei Okubo
- Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, Tokyo, 133-0033, Japan
| | - Masamitsu Iino
- Division of Cellular and Molecular Pharmacology, Nihon University School of Medicine, Tokyo, 173-8610, Japan
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86
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Fekete A, Nakamura Y, Yang YM, Herlitze S, Mark MD, DiGregorio DA, Wang LY. Underpinning heterogeneity in synaptic transmission by presynaptic ensembles of distinct morphological modules. Nat Commun 2019; 10:826. [PMID: 30778063 PMCID: PMC6379440 DOI: 10.1038/s41467-019-08452-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Accepted: 12/28/2018] [Indexed: 11/09/2022] Open
Abstract
Synaptic heterogeneity is widely observed but its underpinnings remain elusive. We addressed this issue using mature calyx of Held synapses whose numbers of bouton-like swellings on stalks of the nerve terminals inversely correlate with release probability (Pr). We examined presynaptic Ca2+ currents and transients, topology of fluorescently tagged knock-in Ca2+ channels, and Ca2+ channel-synaptic vesicle (SV) coupling distance using Ca2+ chelator and inhibitor of septin cytomatrix in morphologically diverse synapses. We found that larger clusters of Ca2+ channels with tighter coupling distance to SVs elevate Pr in stalks, while smaller clusters with looser coupling distance lower Pr in swellings. Septin is a molecular determinant of the differences in coupling distance. Supported by numerical simulations, we propose that varying the ensemble of two morphological modules containing distinct Ca2+ channel-SV topographies diversifies Pr in the terminal, thereby establishing a morpho-functional continuum that expands the coding capacity within a single synapse population.
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Affiliation(s)
- Adam Fekete
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, 555 University Ave, Toronto, ON, M5G 1X8, Canada
- Department of Physiology, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Yukihiro Nakamura
- Department of Pharmacology, Jikei University School of Medicine, Nishishinbashi, Minato-ku, Tokyo, 1058461, Japan
| | - Yi-Mei Yang
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, 555 University Ave, Toronto, ON, M5G 1X8, Canada
- Department of Physiology, University of Toronto, Toronto, ON, M5S 1A8, Canada
- Department of Biomedical Sciences, University of Minnesota Medical School, 1035 University Drive, Duluth, MN, 55812, USA
| | - Stefan Herlitze
- Department of General Zoology and Neurobiology, Ruhr-University Bochum, Universitätsstrasse 150, D-44780, Bochum, Germany
| | - Melanie D Mark
- Department of General Zoology and Neurobiology, Ruhr-University Bochum, Universitätsstrasse 150, D-44780, Bochum, Germany
| | - David A DiGregorio
- Unit of Dynamic Neuronal Imaging, Institut Pasteur, 25 rue du Dr Roux, 75724, Paris Cedex 15, France
- Centre National de la Recherche Scientifique (CNRS), UMR 3571, Genes, Synapses and Cognition, Institut Pasteur, 25 rue du Dr Roux, 75724, Paris Cedex 15, France
| | - Lu-Yang Wang
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, 555 University Ave, Toronto, ON, M5G 1X8, Canada.
- Department of Physiology, University of Toronto, Toronto, ON, M5S 1A8, Canada.
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87
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Lock JT, Smith IF, Parker I. Spatial-temporal patterning of Ca 2+ signals by the subcellular distribution of IP 3 and IP 3 receptors. Semin Cell Dev Biol 2019; 94:3-10. [PMID: 30703557 DOI: 10.1016/j.semcdb.2019.01.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 01/17/2019] [Accepted: 01/22/2019] [Indexed: 12/25/2022]
Abstract
The patterning of cytosolic Ca2+ signals in space and time underlies their ubiquitous ability to specifically regulate numerous cellular processes. Signals mediated by liberation of Ca2+ sequestered in the endoplasmic reticulum (ER) through inositol trisphosphate receptor (IP3R) channels constitute a hierarchy of events; ranging from openings of individual IP3 channels, through the concerted openings of several clustered IP3Rs to generate local Ca2+ puffs, to global Ca2+ waves and oscillations that engulf the entire cell. Here, we review recent progress in elucidating how this hierarchy is shaped by an interplay between the functional gating properties of IP3Rs and their spatial distribution within the cell. We focus in particular on the subset of IP3Rs that are organized in stationary clusters and are endowed with the ability to preferentially liberate Ca2+.
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Affiliation(s)
- Jeffrey T Lock
- Department of Neurobiology & Behavior, UC Irvine, Irvine, CA, USA.
| | - Ian F Smith
- Department of Neurobiology & Behavior, UC Irvine, Irvine, CA, USA
| | - Ian Parker
- Department of Neurobiology & Behavior, UC Irvine, Irvine, CA, USA; Department of Physiology & Biophysics, UC Irvine, Irvine, CA, USA
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88
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Wacquier B, Voorsluijs V, Combettes L, Dupont G. Coding and decoding of oscillatory Ca 2+ signals. Semin Cell Dev Biol 2019; 94:11-19. [PMID: 30659886 DOI: 10.1016/j.semcdb.2019.01.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 01/11/2019] [Accepted: 01/14/2019] [Indexed: 01/08/2023]
Abstract
About 30 years after their first observation, Ca2+ oscillations are now recognised as a universal mechanism of signal transduction. These oscillations are driven by periodic cycles of release and uptake of Ca2+ between the cytoplasm and the endoplasmic reticulum. Their frequency often increases with the level of stimulation, which can be decoded by some molecules. However, it is becoming increasingly evident that the widespread core oscillatory mechanism is modulated in many ways, depending on the cell type and on the physiological conditions. Interplay with inositol 1,4,5-trisphosphate metabolism and with other Ca2+ stores as the extracellular medium or mitochondria can much affect the properties of these oscillations. In many cases, these finely tuned characteristics of Ca2+ oscillations impact the physiological response that is triggered by the signal. Moreover, oscillations are intrinsically irregular. This randomness can also be exploited by the cell. In this review, we discuss evidences of these additional manifestations of the versatility of Ca2+ signalling.
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Affiliation(s)
- Benjamin Wacquier
- Unit of Theoretical Chronobiology, Faculté des Sciences, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Valérie Voorsluijs
- Nonlinear Physical Chemistry Unit & Center for Nonlinear Phenomena and Complex Systems (CENOLI), Université Libre de Bruxelles (ULB), Brussels, Belgium
| | | | - Geneviève Dupont
- Unit of Theoretical Chronobiology, Faculté des Sciences, Université Libre de Bruxelles (ULB), Brussels, Belgium.
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89
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Lallouette J, De Pittà M, Berry H. Astrocyte Networks and Intercellular Calcium Propagation. SPRINGER SERIES IN COMPUTATIONAL NEUROSCIENCE 2019. [DOI: 10.1007/978-3-030-00817-8_7] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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90
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Singh N, Adlakha N. Three dimensional coupled reaction–diffusion modeling of calcium and inositol 1,4,5-trisphosphate dynamics in cardiomyocytes. RSC Adv 2019; 9:42459-42469. [PMID: 35542883 PMCID: PMC9076935 DOI: 10.1039/c9ra06929a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Accepted: 11/28/2019] [Indexed: 11/30/2022] Open
Abstract
Nanoparticles have shown great promise in improving cancer treatment efficacy by changing the intracellular calcium level through activation of intracellular mechanisms. One of the mechanisms of the killing of the cancerous cell by a nanoparticle is through elevation of the intracellular calcium level. Evidence accumulated over the past decade indicates a pivotal role for the IP3 receptor mediated Ca2+ release in the regulation of the cytosolic and the nuclear Ca2+ signals. There have been various studies done suggesting the role of IP3 receptors (IP3R) and IP3 production and degradation in cardiomyocytes. In the present work, we have proposed a three-dimensional unsteady-state mathematical model to describe the mechanism of cardiomyocytes which focuses on evaluation of various parameters that affect these coupled dynamics and elevate the cytosolic calcium concentration which can be helpful to search for novel therapies to cure these malignancies by targeting the complex calcium signaling process in cardiomyocytes. Our study suggests that there are other factors involved in this signaling which can increase the calcium level, which can help in finding treatment for cancer. The cytosolic calcium level may be controlled by IP3 signaling, leak, source influx of calcium (σ) and maximum production of IP3 (VP). We believe that the proposed model suggests new insight into finding treatment for cancer in cardiomyocytes through elevation of the cytosolic Ca2+ concentration by various parameters like leak, σ, VP and especially by other complex cell signaling dynamics, namely IP3 dynamics. We propose a three-dimensional unsteady-state mathematical model to describe the mechanism of cardiomyocytes.![]()
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Affiliation(s)
- Nisha Singh
- Applied Mathematics and Humanities Department
- SVNIT
- Surat
- India
| | - Neeru Adlakha
- Applied Mathematics and Humanities Department
- SVNIT
- Surat
- India
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91
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Abstract
Veins exhibit spontaneous contractile activity, a phenomenon generally termed vasomotion. This is mediated by spontaneous rhythmical contractions of mural cells (i.e. smooth muscle cells (SMCs) or pericytes) in the wall of the vessel. Vasomotion occurs through interconnected oscillators within and between mural cells, entraining their cycles. Pharmacological studies indicate that a key oscillator underlying vasomotion is the rhythmical calcium ion (Ca2+) release-refill cycle of Ca2+ stores. This occurs through opening of inositol 1,4,5-trisphosphate receptor (IP3R)- and/or ryanodine receptor (RyR)-operated Ca2+ release channels in the sarcoplasmic/endoplasmic (SR/ER) reticulum and refilling by the SR/ER reticulum Ca2+ATPase (SERCA). Released Ca2+ from stores near the plasma membrane diffuse through the cytosol to open Ca2+-activated chloride (Cl-) channels, this generating inward current through an efflux of Cl-. The resultant depolarisation leads to the opening of voltage-dependent Ca2+ channels and possibly increased production of IP3, which through Ca2+-induced Ca2+ release (CICR) of IP3Rs and/or RyRs and IP3R-mediated Ca2+ release provide a means by which store oscillators entrain their activity. Intercellular entrainment normally involves current flow through gap junctions that interconnect mural cells and in many cases this is aided by additional connectivity through the endothelium. Once entrainment has occurred the substantial Ca2+ entry that results from the near-synchronous depolarisations leads to rhythmical contractions of the mural cells, this often leading to vessel constriction. The basis for venous/venular vasomotion has yet to be fully delineated but could improve both venous drainage and capillary/venular absorption of blood plasma-associated fluids.
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92
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93
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Basak R, Narayanan R. Active dendrites regulate the spatiotemporal spread of signaling microdomains. PLoS Comput Biol 2018; 14:e1006485. [PMID: 30383745 PMCID: PMC6233924 DOI: 10.1371/journal.pcbi.1006485] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 11/13/2018] [Accepted: 09/03/2018] [Indexed: 12/24/2022] Open
Abstract
Microdomains that emerge from spatially constricted spread of biochemical signaling components play a central role in several neuronal computations. Although dendrites, endowed with several voltage-gated ion channels, form a prominent structural substrate for microdomain physiology, it is not known if these channels regulate the spatiotemporal spread of signaling microdomains. Here, we employed a multiscale, morphologically realistic, conductance-based model of the hippocampal pyramidal neuron that accounted for experimental details of electrical and calcium-dependent biochemical signaling. We activated synaptic N-Methyl-d-Aspartate receptors through theta-burst stimulation (TBS) or pairing (TBP) and assessed microdomain propagation along a signaling pathway that included calmodulin, calcium/calmodulin-dependent protein kinase II (CaMKII) and protein phosphatase 1. We found that the spatiotemporal spread of the TBS-evoked microdomain in phosphorylated CaMKII (pCaMKII) was amplified in comparison to that of the corresponding calcium microdomain. Next, we assessed the role of two dendritically expressed inactivating channels, one restorative (A-type potassium) and another regenerative (T-type calcium), by systematically varying their conductances. Whereas A-type potassium channels suppressed the spread of pCaMKII microdomains by altering the voltage response to TBS, T-type calcium channels enhanced this spread by modulating TBS-induced calcium influx without changing the voltage. Finally, we explored cross-dependencies of these channels with other model components, and demonstrated the heavy mutual interdependence of several biophysical and biochemical properties in regulating microdomains and their spread. Our conclusions unveil a pivotal role for dendritic voltage-gated ion channels in actively amplifying or suppressing biochemical signals and their spatiotemporal spread, with critical implications for clustered synaptic plasticity, robust information transfer and efficient neural coding. The spatiotemporal spread of biochemical signals in neurons and other cells regulate signaling specificity, tuning of signal propagation, along with specificity and clustering of adaptive plasticity. Theoretical and experimental studies have demonstrated a critical role for cellular morphology and the topology of signaling networks in regulating this spread. In this study, we add a significantly complex dimension to this narrative by demonstrating that voltage-gated ion channels on the plasma membrane could actively amplify or suppress the strength and spread of downstream signaling components. Given the expression of different ion channels with wide-ranging heterogeneity in gating kinetics, localization and density, our results point to an increase in complexity of and degeneracy in signaling spread, and unveil a powerful mechanism for regulating biochemical-signaling pathways across different cell types.
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Affiliation(s)
- Reshma Basak
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | - Rishikesh Narayanan
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
- * E-mail:
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94
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Dorman DB, Jędrzejewska-Szmek J, Blackwell KT. Inhibition enhances spatially-specific calcium encoding of synaptic input patterns in a biologically constrained model. eLife 2018; 7:e38588. [PMID: 30355449 PMCID: PMC6235562 DOI: 10.7554/elife.38588] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 10/24/2018] [Indexed: 11/13/2022] Open
Abstract
Synaptic plasticity, which underlies learning and memory, depends on calcium elevation in neurons, but the precise relationship between calcium and spatiotemporal patterns of synaptic inputs is unclear. Here, we develop a biologically realistic computational model of striatal spiny projection neurons with sophisticated calcium dynamics, based on data from rodents of both sexes, to investigate how spatiotemporally clustered and distributed excitatory and inhibitory inputs affect spine calcium. We demonstrate that coordinated excitatory synaptic inputs evoke enhanced calcium elevation specific to stimulated spines, with lower but physiologically relevant calcium elevation in nearby non-stimulated spines. Results further show a novel and important function of inhibition-to enhance the difference in calcium between stimulated and non-stimulated spines. These findings suggest that spine calcium dynamics encode synaptic input patterns and may serve as a signal for both stimulus-specific potentiation and heterosynaptic depression, maintaining balanced activity in a dendritic branch while inducing pattern-specific plasticity.
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Affiliation(s)
- Daniel B Dorman
- Interdisciplinary Program in NeuroscienceGeorge Mason UniversityFairfaxUnited States
| | | | - Kim T Blackwell
- Interdisciplinary Program in Neuroscience, Bioengineering DepartmentKrasnow Institute for Advanced Study, George Mason UniversityFairfaxUnited States
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95
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Breit M, Kessler M, Stepniewski M, Vlachos A, Queisser G. Spine-to-Dendrite Calcium Modeling Discloses Relevance for Precise Positioning of Ryanodine Receptor-Containing Spine Endoplasmic Reticulum. Sci Rep 2018; 8:15624. [PMID: 30353066 PMCID: PMC6199256 DOI: 10.1038/s41598-018-33343-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 09/18/2018] [Indexed: 12/15/2022] Open
Abstract
The endoplasmic reticulum (ER) forms a complex endomembrane network that reaches into the cellular compartments of a neuron, including dendritic spines. Recent work discloses that the spine ER is a dynamic structure that enters and leaves spines. While evidence exists that ER Ca2+ release is involved in synaptic plasticity, the role of spine ER morphology remains unknown. Combining a new 3D spine generator with 3D Ca2+ modeling, we addressed the relevance of ER positioning on spine-to-dendrite Ca2+ signaling. Our simulations, which account for Ca2+ exchange on the plasma membrane and ER, show that spine ER needs to be present in distinct morphological conformations in order to overcome a barrier between the spine and dendritic shaft. We demonstrate that RyR-carrying spine ER promotes spine-to-dendrite Ca2+ signals in a position-dependent manner. Our simulations indicate that RyR-carrying ER can initiate time-delayed Ca2+ reverberation, depending on the precise position of the spine ER. Upon spine growth, structural reorganization of the ER restores spine-to-dendrite Ca2+ communication, while maintaining aspects of Ca2+ homeostasis in the spine head. Our work emphasizes the relevance of precise positioning of RyR-containing spine ER in regulating the strength and timing of spine Ca2+ signaling, which could play an important role in tuning spine-to-dendrite Ca2+ communication and homeostasis.
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Affiliation(s)
- Markus Breit
- Goethe Center for Scientific Computing, Computational Neuroscience, Goethe University Frankfurt, Frankfurt, Germany
| | - Marcus Kessler
- Goethe Center for Scientific Computing, Computational Neuroscience, Goethe University Frankfurt, Frankfurt, Germany
| | - Martin Stepniewski
- Goethe Center for Scientific Computing, Computational Neuroscience, Goethe University Frankfurt, Frankfurt, Germany
| | - Andreas Vlachos
- Department of Neuroanatomy, Institute of Anatomy and Cell Biology, Faculty of Medicine, University of Freiburg, Freiburg, 79104, Germany. .,Bernstein Center Freiburg, University of Freiburg, Freiburg, 79104, Germany.
| | - Gillian Queisser
- Department of Mathematics, Temple University, Philadelphia, USA.
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96
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Verma A, Antony AN, Ogunnaike BA, Hoek JB, Vadigepalli R. Causality Analysis and Cell Network Modeling of Spatial Calcium Signaling Patterns in Liver Lobules. Front Physiol 2018; 9:1377. [PMID: 30337879 PMCID: PMC6180170 DOI: 10.3389/fphys.2018.01377] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 09/11/2018] [Indexed: 01/21/2023] Open
Abstract
Dynamics as well as localization of Ca2+ transients plays a vital role in liver function under homeostatic conditions, repair, and disease. In response to circulating hormonal stimuli, hepatocytes exhibit intracellular Ca2+ responses that propagate through liver lobules in a wave-like fashion. Although intracellular processes that control cell autonomous Ca2+ spiking behavior have been studied extensively, the intra- and inter-cellular signaling factors that regulate lobular scale spatial patterns and wave-like propagation of Ca2+ remain to be determined. To address this need, we acquired images of cytosolic Ca2+ transients in 1300 hepatocytes situated across several mouse liver lobules over a period of 1600 s. We analyzed this time series data using correlation network analysis, causal network analysis, and computational modeling, to characterize the spatial distribution of heterogeneity in intracellular Ca2+ signaling components as well as intercellular interactions that control lobular scale Ca2+ waves. Our causal network analysis revealed that hepatocytes are causally linked to multiple other co-localized hepatocytes, but these influences are not necessarily aligned uni-directionally along the sinusoids. Our computational model-based analysis showed that spatial gradients of intracellular Ca2+ signaling components as well as intercellular molecular exchange are required for lobular scale propagation of Ca2+ waves. Additionally, our analysis suggested that causal influences of hepatocytes on Ca2+ responses of multiple neighbors lead to robustness of Ca2+ wave propagation through liver lobules.
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Affiliation(s)
- Aalap Verma
- Department of Biomedical Engineering, University of Delaware, Newark, DE, United States.,Department of Pathology, Anatomy and Cell Biology, Daniel Baugh Institute for Functional Genomics and Computational Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Anil Noronha Antony
- Department of Pathology, Anatomy and Cell Biology, Daniel Baugh Institute for Functional Genomics and Computational Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Babatunde A Ogunnaike
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, United States
| | - Jan B Hoek
- Department of Pathology, Anatomy and Cell Biology, Daniel Baugh Institute for Functional Genomics and Computational Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Rajanikanth Vadigepalli
- Department of Pathology, Anatomy and Cell Biology, Daniel Baugh Institute for Functional Genomics and Computational Biology, Thomas Jefferson University, Philadelphia, PA, United States
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97
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Okubo Y, Kanemaru K, Suzuki J, Kobayashi K, Hirose K, Iino M. Inositol 1,4,5-trisphosphate receptor type 2-independent Ca2+
release from the endoplasmic reticulum in astrocytes. Glia 2018; 67:113-124. [DOI: 10.1002/glia.23531] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 08/13/2018] [Accepted: 08/15/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Yohei Okubo
- Department of Pharmacology; Graduate School of Medicine, The University of Tokyo; Tokyo Japan
| | - Kazunori Kanemaru
- Department of Pharmacology; Graduate School of Medicine, The University of Tokyo; Tokyo Japan
- Department of Cellular and Molecular Pharmacology; Nihon University School of Medicine; Tokyo Japan
| | - Junji Suzuki
- Department of Physiology; University of California San Francisco; San Francisco California
| | - Kenta Kobayashi
- Section of Viral Vector Development; National Institute for Physiological Sciences; Okazaki Japan
- The Graduate University for Advanced Studies (SOKENDAI); Hayama Japan
| | - Kenzo Hirose
- Department of Neurobiology; Graduate School of Medicine, The University of Tokyo; Tokyo Japan
| | - Masamitsu Iino
- Department of Cellular and Molecular Pharmacology; Nihon University School of Medicine; Tokyo Japan
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98
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Two-component latency distributions indicate two-step vesicular release at simple glutamatergic synapses. Nat Commun 2018; 9:3943. [PMID: 30258069 PMCID: PMC6158186 DOI: 10.1038/s41467-018-06336-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Accepted: 07/31/2018] [Indexed: 01/03/2023] Open
Abstract
It is often assumed that only stably docked synaptic vesicles can fuse following presynaptic action potential stimulation. However, during action potential trains docking sites are increasingly depleted, raising the question of the source of synaptic vesicles during sustained release. We have recently developed methods to reliably measure release latencies during high frequency trains at single synapses between parallel fibers and molecular layer interneurons. The latency distribution exhibits a single fast component at train onset but contains both a fast and a slow component later in the train. The contribution of the slow component increases with stimulation frequency and with release probability and decreases when blocking the docking step with latrunculin. These results suggest that the slow component reflects sequential docking and release in immediate succession. The transition from fast to slow component, as well as a later transition to asynchronous release, appear as successive adaptations of the synapse to maintain fidelity at the expense of time accuracy.
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99
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Burke KJ, Keeshen CM, Bender KJ. Two Forms of Synaptic Depression Produced by Differential Neuromodulation of Presynaptic Calcium Channels. Neuron 2018; 99:969-984.e7. [PMID: 30122380 PMCID: PMC7874512 DOI: 10.1016/j.neuron.2018.07.030] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 06/03/2018] [Accepted: 07/18/2018] [Indexed: 01/09/2023]
Abstract
Neuromodulators are important regulators of synaptic transmission throughout the brain. At the presynaptic terminal, neuromodulation of calcium channels (CaVs) can affect transmission not only by changing neurotransmitter release probability, but also by shaping short-term plasticity (STP). Indeed, changes in STP are often considered a requirement for defining a presynaptic site of action. Nevertheless, some synapses exhibit non-canonical forms of neuromodulation, where release probability is altered without a corresponding change in STP. Here, we identify biophysical mechanisms whereby both canonical and non-canonical presynaptic neuromodulation can occur at the same synapse. At a subset of glutamatergic terminals in prefrontal cortex, GABAB and D1/D5 dopamine receptors suppress release probability with and without canonical increases in short-term facilitation by modulating different aspects of presynaptic CaV function. These findings establish a framework whereby signaling from multiple neuromodulators can converge on presynaptic CaVs to differentially tune release dynamics at the same synapse.
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Affiliation(s)
- Kenneth J Burke
- Neuroscience Graduate Program, Department of Neurology, University of California, San Francisco, San Francisco, CA, USA
| | - Caroline M Keeshen
- Weill Institute for Neurosciences, Department of Neurology, University of California, San Francisco, San Francisco, CA, USA
| | - Kevin J Bender
- Neuroscience Graduate Program, Department of Neurology, University of California, San Francisco, San Francisco, CA, USA; Weill Institute for Neurosciences, Department of Neurology, University of California, San Francisco, San Francisco, CA, USA.
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100
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Gao H, Yang Z, Wang X, Qian P, Hong R, Chen X, Su XZ, Cui H, Yuan J. ISP1-Anchored Polarization of GCβ/CDC50A Complex Initiates Malaria Ookinete Gliding Motility. Curr Biol 2018; 28:2763-2776.e6. [PMID: 30146157 DOI: 10.1016/j.cub.2018.06.069] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 05/28/2018] [Accepted: 06/26/2018] [Indexed: 12/20/2022]
Abstract
Ookinete gliding motility is essential for penetration of the mosquito midgut wall and transmission of malaria parasites. Cyclic guanosine monophosphate (cGMP) signaling has been implicated in ookinete gliding. However, the upstream mechanism of how the parasites activate cGMP signaling and thus initiate ookinete gliding remains unknown. Using real-time imaging to visualize Plasmodium yoelii guanylate cyclase β (GCβ), we show that cytoplasmic GCβ translocates and polarizes to the parasite plasma membrane at "ookinete extrados site" (OES) during zygote-to-ookinete differentiation. The polarization of enzymatic active GCβ at OES initiates gliding of matured ookinete. Both the P4-ATPase-like domain and guanylate cyclase domain are required for GCβ polarization and ookinete gliding. CDC50A, a co-factor of P4-ATPase, binds to and stabilizes GCβ during ookinete development. Screening of inner membrane complex proteins identifies ISP1 as a key molecule that anchors GCβ/CDC50A complex at the OES of mature ookinetes. This study defines a spatial-temporal mechanism for the initiation of ookinete gliding, where GCβ polarization likely elevates local cGMP levels and activates cGMP-dependent protein kinase signaling.
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Affiliation(s)
- Han Gao
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signal Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Zhenke Yang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signal Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Xu Wang
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signal Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Pengge Qian
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signal Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Renjie Hong
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signal Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Xin Chen
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signal Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Xin-Zhuan Su
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892, USA
| | - Huiting Cui
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signal Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China
| | - Jing Yuan
- State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signal Network, School of Life Sciences, Xiamen University, Xiamen, Fujian 361102, China.
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