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Watanabe D, Nishi M, Liu F, Bian Y, Takeshima H. Ca 2+ storage function is altered in the sarcoplasmic reticulum of skeletal muscle lacking mitsugumin 23. Am J Physiol Cell Physiol 2024; 326:C795-C809. [PMID: 38223925 DOI: 10.1152/ajpcell.00440.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 12/26/2023] [Accepted: 01/05/2024] [Indexed: 01/16/2024]
Abstract
Mitsugumin 23 (MG23) has been identified as a ball-shaped cation channel in the sarcoplasmic reticulum (SR) but its physiological role remains unclear. This study aimed to examine the contribution of MG23 to Ca2+ storage function in skeletal muscle by using Mg23-knockout (Mg23-/-) mice. There was no difference in the isometric specific force of the extensor digitorum longus (EDL) and soleus (SOL) muscles between Mg23-/- and wild-type (Wt) mice. In Mg23-/- mice, the calsequestrin 2 content in the EDL muscle and SR Ca2+-ATPase 2 content in the SOL were increased. We have examined SR and myofibril functions using mechanically skinned fibers and determined their fiber types based on the response to Sr2+, which showed that Mg23-/- mice, compared with Wt, had: 1) elevated total Ca2+ content in the membranous components including SR, mitochondria, and transverse tubular system referred to as endogenous Ca2+ content, in both type I and II fibers of the EDL and SOL; 2) increased maximal Ca2+ content in both type I and II fibers of the EDL and SOL; 3) decreased SR Ca2+ leakage in type I fibers of the SOL; and 4) enhanced SR Ca2+ uptake in type I fibers of the SOL, although myofibril function was not different in both type I and II fibers of the SOL and EDL muscles. These results suggest that MG23 decreases SR Ca2+ storage in both type I and type II fibers, likely due to increased SR Ca2+ leakage.NEW & NOTEWORTHY The function of calcium storage within sarcoplasmic reticulum (SR) plays a pivotal role in influencing the health and disease states of skeletal muscle. In the present study, we demonstrated that mitsgumin 23, a novel non-selective cation channel, modifies SR Ca2+ storage in skeletal muscle fibers. These findings provide valuable insights into the physiological regulation of Ca2+ in skeletal muscle, offering significant potential for uncovering the mechanisms underlying muscle fatigue, muscle adaptation, and muscle diseases.
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Affiliation(s)
- Daiki Watanabe
- Graduate School of Sport and Health Sciences, Osaka University of Health and Sport Sciences, Osaka, Japan
| | - Miyuki Nishi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Feng Liu
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Yuhan Bian
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Hiroshi Takeshima
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
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2
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Khamis H, Cohen O. Coupled action potential and calcium dynamics underlie robust spontaneous firing in dopaminergic neurons. Phys Biol 2024; 21:026005. [PMID: 38382117 DOI: 10.1088/1478-3975/ad2bd4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 02/21/2024] [Indexed: 02/23/2024]
Abstract
Dopaminergic neurons are specialized cells in the substantia nigra, tasked with dopamine secretion. This secretion relies on intracellular calcium signaling coupled to neuronal electrical activity. These neurons are known to display spontaneous calcium oscillationsin-vitroandin-vivo, even in synaptic isolation, controlling the basal dopamine levels. Here we outline a kinetic model for the ion exchange across the neuronal plasma membrane. Crucially, we relax the assumption of constant, cytoplasmic sodium and potassium concentration. We show that sodium-potassium dynamics are strongly coupled to calcium dynamics and are essential for the robustness of spontaneous firing frequency. The model predicts several regimes of electrical activity, including tonic and 'burst' oscillations, and predicts the switch between those in response to perturbations. 'Bursting' correlates with increased calcium amplitudes, while maintaining constant average, allowing for a vast change in the calcium signal responsible for dopamine secretion. All the above traits provide the flexibility to create rich action potential dynamics that are crucial for cellular function.
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Affiliation(s)
- Hadeel Khamis
- Gateway Institute for Brain Research, Fort Lauderdale, FL 33314, United States of America
| | - Ohad Cohen
- Gateway Institute for Brain Research, Fort Lauderdale, FL 33314, United States of America
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3
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Nakamura M, Parkhurst SM. Calcium influx rapidly establishes distinct spatial recruitments of Annexins to cell wounds. bioRxiv 2023:2023.12.03.569799. [PMID: 38105960 PMCID: PMC10723296 DOI: 10.1101/2023.12.03.569799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
To survive daily damage, the formation of actomyosin ring at the wound periphery is required to rapidly close cell wounds. Calcium influx is one of the start signals for these cell wound repair events. Here, we find that rapid recruitment of all three Drosophila calcium responding and phospholipid binding Annexin proteins (AnxB9, AnxB10, AnxB11) to distinct regions around the wound are regulated by the quantity of calcium influx rather than their binding to specific phospholipids. The distinct recruitment patterns of these Annexins regulate the subsequent recruitment of RhoGEF2 and RhoGEF3 through actin stabilization to form a robust actomyosin ring. Surprisingly, we find that reduced extracellular calcium and depletion of intracellular calcium affect cell wound repair differently, despite these two conditions exhibiting similar GCaMP signals. Thus, our results suggest that, in addition to initiating repair events, both the quantity and sources of calcium influx are important for precise Annexin spatiotemporal protein recruitment to cell wounds and efficient wound repair.
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Affiliation(s)
- Mitsutoshi Nakamura
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA 98109
| | - Susan M. Parkhurst
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA 98109
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4
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Chou SM, Yen YH, Yuan F, Zhang SC, Chong CM. Neuronal Senescence in the Aged Brain. Aging Dis 2023; 14:1618-1632. [PMID: 37196117 PMCID: PMC10529744 DOI: 10.14336/ad.2023.0214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 02/14/2023] [Indexed: 05/19/2023] Open
Abstract
Cellular senescence is a highly complicated cellular state that occurs throughout the lifespan of an organism. It has been well-defined in mitotic cells by various senescent features. Neurons are long-lived post-mitotic cells with special structures and functions. With age, neurons display morphological and functional changes, accompanying alterations in proteostasis, redox balance, and Ca2+ dynamics; however, it is ambiguous whether these neuronal changes belong to the features of neuronal senescence. In this review, we strive to identify and classify changes that are relatively specific to neurons in the aging brain and define them as features of neuronal senescence through comparisons with common senescent features. We also associate them with the functional decline of multiple cellular homeostasis systems, proposing the possibility that these systems are the main drivers of neuronal senescence. We hope this summary will serve as a steppingstone for further inputs on a comprehensive but relatively specific list of phenotypes for neuronal senescence and in particular their underlying molecular events during aging. This will in turn shine light on the association between neuronal senescence and neurodegeneration and lead to the development of strategies to perturb the processes.
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Affiliation(s)
- Shu-Min Chou
- Program in Neuroscience & Behavioral Disorders, Duke-NUS Medical School, 169857 Singapore, Singapore.
| | - Yu-Hsin Yen
- Program in Neuroscience & Behavioral Disorders, Duke-NUS Medical School, 169857 Singapore, Singapore.
| | - Fang Yuan
- Program in Neuroscience & Behavioral Disorders, Duke-NUS Medical School, 169857 Singapore, Singapore.
| | - Su-Chun Zhang
- Program in Neuroscience & Behavioral Disorders, Duke-NUS Medical School, 169857 Singapore, Singapore.
- Department of Neuroscience, Department of Neurology, Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA.
| | - Cheong-Meng Chong
- State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China.
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5
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Shrestha AP, Rameshkumar N, Boff JM, Rajmanna R, Chandrasegaran T, Frederick CE, Zenisek D, Vaithianathan T. The Effects of Aging on Rod Bipolar Cell Ribbon Synapses. Cells 2023; 12:2385. [PMID: 37830599 PMCID: PMC10572008 DOI: 10.3390/cells12192385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 09/20/2023] [Accepted: 09/27/2023] [Indexed: 10/14/2023] Open
Abstract
The global health concern posed by age-related visual impairment highlights the need for further research focused on the visual changes that occur during the process of aging. To date, multiple sensory alterations related to aging have been identified, including morphological and functional changes in inner hair cochlear cells, photoreceptors, and retinal ganglion cells. While some age-related morphological changes are known to occur in rod bipolar cells in the retina, their effects on these cells and on their connection to other cells via ribbon synapses remain elusive. To investigate the effects of aging on rod bipolar cells and their ribbon synapses, we compared synaptic calcium currents, calcium dynamics, and exocytosis in zebrafish (Danio rerio) that were middle-aged (MA,18 months) or old-aged (OA, 36 months). The bipolar cell terminal in OA zebrafish exhibited a two-fold reduction in number of synaptic ribbons, an increased ribbon length, and a decrease in local Ca2+ signals at the tested ribbon location, with little change in the overall magnitude of the calcium current or exocytosis in response to brief pulses. Staining of the synaptic ribbons with antibodies specific for PKCa revealed shortening of the inner nuclear and plexiform layers (INL and IPL). These findings shed light on age-related changes in the retina that are related to synaptic ribbons and calcium signals.
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Affiliation(s)
- Abhishek P. Shrestha
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Nirujan Rameshkumar
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Johane M. Boff
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Rhea Rajmanna
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | | | - Courtney E. Frederick
- Department of Molecular and Cellular Physiology, Yale University School of Medicine, New Haven, CT 06510, USA (D.Z.)
| | - David Zenisek
- Department of Molecular and Cellular Physiology, Yale University School of Medicine, New Haven, CT 06510, USA (D.Z.)
| | - Thirumalini Vaithianathan
- Department of Pharmacology, Addiction Science, and Toxicology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
- Department of Ophthalmology, Hamilton Eye Institute, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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6
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Gupta A, Manchanda R. Computational modeling of stretch induced calcium signaling at the apical membrane domain in umbrella cells. Comput Methods Biomech Biomed Engin 2023; 26:1368-1377. [PMID: 36062946 DOI: 10.1080/10255842.2022.2117549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 08/17/2022] [Accepted: 08/22/2022] [Indexed: 11/03/2022]
Abstract
The urinary bladder epithelium comprises a specialised population of superficially placed cells called the umbrella cells. The apical membrane domain of umbrella cells has several intriguing morphological properties and is the site for various signaling activities. A key function of umbrella cells is to sense mechanical stimuli as the bladder stretches in response to filling. More specifically, the mechanotransduction of stretch into subcellular signals is brought about by the activation of Piezo1 channels that mediate calcium into the cell interior. The incoming calcium is critical to several aspects of umbrella cell signaling, including regulation of exocytosis, ATP release and downstream purinergic signaling. We report here a computational framework that models stretch-induced mechanotransduction via Piezo1 channels and the resulting calcium signaling in umbrella cells factoring in morphological details of subcellular compartment volumes. Our results show the following: (i) activation of Piezo1 conductance in response to stretch; (ii) development of varying Piezo1 mediated [Ca2+] profiles in subcellular compartments, namely, the apical sub-plasma membrane space, cytosol and mitochondria. The varying calcium amplitudes and temporal profiles in the subcellular compartments indicate highly specialised roles for stretch-mediated calcium in umbrella cells, including its potential effect on the energetics of mitochondria and the regulation of exocytosis.
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Affiliation(s)
- Amritanshu Gupta
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Rohit Manchanda
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai, India
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7
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Laasmaa M, Branovets J, Stolova J, Shen X, Rätsepso T, Balodis MJ, Grahv C, Hendrikson E, Louch WE, Birkedal R, Vendelin M. Cardiomyocytes from female compared to male mice have larger ryanodine receptor clusters and higher calcium spark frequency. J Physiol 2023; 601:4033-4052. [PMID: 37561554 DOI: 10.1113/jp284515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 07/07/2023] [Indexed: 08/11/2023] Open
Abstract
Sex differences in cardiac physiology are receiving increased attention as it has become clear that men and women have different aetiologies of cardiac disease and require different treatments. There are experimental data suggesting that male cardiomyocytes exhibit larger Ca2+ transients due to larger Ca2+ sparks and a higher excitation-contraction coupling gain; in addition, they exhibit a larger response to adrenergic stimulation with isoprenaline (ISO). Here, we studied whether there are sex differences relating to structural organization of the transverse tubular network and ryanodine receptors (RyRs). Surprisingly, we found that female cardiomyocytes exhibited a higher spark frequency in a range of spark magnitudes. While overall RyR expression and phosphorylation were the same, female cardiomyocytes had larger but fewer RyR clusters. The density of transverse t-tubules was the same, but male cardiomyocytes had more longitudinal t-tubules. The Ca2+ transients were similar in male and female cardiomyocytes under control conditions and in the presence of ISO. The synchrony of the Ca2+ transients was similar between sexes as well. Overall, our data suggest subtle sex differences in the Ca2+ influx and efflux pathways and their response to ISO, but these differences are balanced, resulting in similar Ca2+ transients in field-stimulated male and female cardiomyocytes. The higher spark frequency in female cardiomyocytes is related to the organization of RyRs into larger, but fewer clusters. KEY POINTS: During a heartbeat, the force of contraction depends on the amplitude of the calcium transient, which in turn depends on the amount of calcium released as calcium sparks through ryanodine receptors in the sarcoplasmic reticulum. Previous studies suggest that cardiomyocytes from male compared to female mice exhibit larger calcium sparks, larger sarcoplasmic reticulum calcium release and greater response to adrenergic stimulation triggering a fight-or-flight response. In contrast, we show that cardiomyocytes from female mice have a higher spark frequency during adrenergic stimulation and similar spark morphology. The higher spark frequency is related to the organization of ryanodine receptors into fewer, but larger clusters in female compared to male mouse cardiomyocytes. Despite subtle sex differences in cardiomyocyte structure and calcium fluxes, the differences are balanced, leading to similar calcium transients in cardiomyocytes from male and female mice.
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Affiliation(s)
- Martin Laasmaa
- Laboratory of Systems Biology, Department of Cybernetics, Tallinn University of Technology, Tallinn, Estonia
- Institute for Experimental Medical Research, University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Jelena Branovets
- Laboratory of Systems Biology, Department of Cybernetics, Tallinn University of Technology, Tallinn, Estonia
| | - Jekaterina Stolova
- Laboratory of Systems Biology, Department of Cybernetics, Tallinn University of Technology, Tallinn, Estonia
| | - Xin Shen
- Institute for Experimental Medical Research, University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Triinu Rätsepso
- Laboratory of Systems Biology, Department of Cybernetics, Tallinn University of Technology, Tallinn, Estonia
| | - Mihkel Jaan Balodis
- Laboratory of Systems Biology, Department of Cybernetics, Tallinn University of Technology, Tallinn, Estonia
| | - Cärolin Grahv
- Laboratory of Systems Biology, Department of Cybernetics, Tallinn University of Technology, Tallinn, Estonia
| | - Eliise Hendrikson
- Laboratory of Systems Biology, Department of Cybernetics, Tallinn University of Technology, Tallinn, Estonia
| | - William Edward Louch
- Institute for Experimental Medical Research, University of Oslo, Oslo, Norway
- K.G. Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Rikke Birkedal
- Laboratory of Systems Biology, Department of Cybernetics, Tallinn University of Technology, Tallinn, Estonia
| | - Marko Vendelin
- Laboratory of Systems Biology, Department of Cybernetics, Tallinn University of Technology, Tallinn, Estonia
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8
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Liang Q, Chen Z, Chen X, Huang Q, Sun T. Network Bursts in 3D Neuron Clusters Cultured on Microcontact-Printed Substrates. Micromachines (Basel) 2023; 14:1703. [PMID: 37763866 PMCID: PMC10534818 DOI: 10.3390/mi14091703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 08/29/2023] [Accepted: 08/29/2023] [Indexed: 09/29/2023]
Abstract
Microcontact printing (CP) is widely used to guide neurons to form 2D networks for neuroscience research. However, it is still difficult to establish 3D neuronal cultures on the CP substrate even though 3D neuronal structures are able to recapitulate critical aspects of native tissue. Here, we demonstrate that the reduced cell-substrate adhesion caused by the CP substrate could conveniently facilitate the aggregate formation of large-scale 3D neuron cluster networks. Furthermore, based on the quantitative analysis of the calcium activity of the resulting cluster networks, the effect of cell seeding density and local restriction of the CP substrate on network dynamics was investigated in detail. The results revealed that cell aggregation degree, rather than cell number, could take on the main role of the generation of synchronized network-wide calcium oscillation (network bursts) in the 3D neuron cluster networks. This finding may provide new insights for easy and cell-saving construction of in vitro 3D pathological models of epilepsy, and into deciphering the onset and evolution of network bursts in developmental nerve systems.
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Affiliation(s)
- Qian Liang
- Intelligent Robotics Institute, School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China; (Q.L.); (X.C.); (Q.H.)
| | - Zhe Chen
- School of Medical Technology, Beijing Institute of Technology, Beijing 100081, China;
| | - Xie Chen
- Intelligent Robotics Institute, School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China; (Q.L.); (X.C.); (Q.H.)
| | - Qiang Huang
- Intelligent Robotics Institute, School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China; (Q.L.); (X.C.); (Q.H.)
| | - Tao Sun
- Intelligent Robotics Institute, School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, China; (Q.L.); (X.C.); (Q.H.)
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Postić S, Sarikas S, Pfabe J, Pohorec V, Križančić Bombek L, Sluga N, Skelin Klemen M, Dolenšek J, Korošak D, Stožer A, Evans-Molina C, Johnson JD, Slak Rupnik M. High-resolution analysis of the cytosolic Ca 2+ events in β cell collectives in situ. Am J Physiol Endocrinol Metab 2023; 324:E42-E55. [PMID: 36449570 PMCID: PMC9829482 DOI: 10.1152/ajpendo.00165.2022] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 11/15/2022] [Accepted: 11/22/2022] [Indexed: 12/02/2022]
Abstract
The release of peptide hormones is predominantly regulated by a transient increase in cytosolic Ca2+ concentration ([Ca2+]c). To trigger exocytosis, Ca2+ ions enter the cytosol from intracellular Ca2+ stores or from the extracellular space. The molecular events of late stages of exocytosis, and their dependence on [Ca2+]c, were extensively described in isolated single cells from various endocrine glands. Notably, less work has been done on endocrine cells in situ to address the heterogeneity of [Ca2+]c events contributing to a collective functional response of a gland. For this, β cell collectives in a pancreatic islet are particularly well suited as they are the smallest, experimentally manageable functional unit, where [Ca2+]c dynamics can be simultaneously assessed on both cellular and collective level. Here, we measured [Ca2+]c transients across all relevant timescales, from a subsecond to a minute time range, using high-resolution imaging with a low-affinity Ca2+ sensor. We quantified the recordings with a novel computational framework for automatic image segmentation and [Ca2+]c event identification. Our results demonstrate that under physiological conditions the duration of [Ca2+]c events is variable, and segregated into three reproducible modes, subsecond, second, and tens of seconds time range, and are a result of a progressive temporal summation of the shortest events. Using pharmacological tools we show that activation of intracellular Ca2+ receptors is both sufficient and necessary for glucose-dependent [Ca2+]c oscillations in β cell collectives, and that a subset of [Ca2+]c events could be triggered even in the absence of Ca2+ influx across the plasma membrane. In aggregate, our experimental and analytical platform was able to readily address the involvement of intracellular Ca2+ receptors in shaping the heterogeneity of [Ca2+]c responses in collectives of endocrine cells in situ.NEW & NOTEWORTHY Physiological glucose or ryanodine stimulation of β cell collectives generates a large number of [Ca2+]c events, which can be rapidly assessed with our newly developed automatic image segmentation and [Ca2+]c event identification pipeline. The event durations segregate into three reproducible modes produced by a progressive temporal summation. Using pharmacological tools, we show that activation of ryanodine intracellular Ca2+ receptors is both sufficient and necessary for glucose-dependent [Ca2+]c oscillations in β cell collectives.
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Affiliation(s)
- Sandra Postić
- Center for physiology and pharmacology, Medical University of Vienna, Vienna, Austria
| | - Srdjan Sarikas
- Center for physiology and pharmacology, Medical University of Vienna, Vienna, Austria
| | - Johannes Pfabe
- Center for physiology and pharmacology, Medical University of Vienna, Vienna, Austria
| | - Viljem Pohorec
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | | | - Nastja Sluga
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Maša Skelin Klemen
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Jurij Dolenšek
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Dean Korošak
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Faculty of Civil Engineering, Transportation Engineering and Architecture, University of Maribor, Maribor, Slovenia
| | - Andraž Stožer
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Carmella Evans-Molina
- Center for Diabetes and Metabolic Diseases and the Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
- Richard L. Roudebush VA Medical Center, Indianapolis, Indiana
| | - James D Johnson
- Diabetes Research Group, Life Sciences Institute, Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Marjan Slak Rupnik
- Center for physiology and pharmacology, Medical University of Vienna, Vienna, Austria
- Institute of Physiology, Faculty of Medicine, University of Maribor, Maribor, Slovenia
- Alma Mater Europaea-European Center Maribor, Maribor, Slovenia
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10
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Sneyd J, Rugis J, Su S, Suresh V, Wahl AM, Yule DI. Simulation of Calcium Dynamics in Realistic Three-Dimensional Domains. Biomolecules 2022; 12:1455. [PMID: 36291663 PMCID: PMC9599163 DOI: 10.3390/biom12101455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 10/01/2022] [Accepted: 10/04/2022] [Indexed: 11/16/2022] Open
Abstract
The cytosolic concentration of free calcium ions ([Ca2+]) is an important intracellular messenger in most cell types, and the spatial distribution of [Ca2+] is often critical. In a salivary gland acinar cell, a polarised epithelial cell, whose principal function is to transport water and thus secrete saliva, [Ca2+] controls the secretion of primary saliva, but increases in [Ca2+] are localised to the apical regions of the cell. Hence, any quantitative explanation of how [Ca2+] controls saliva secretion must take into careful account the spatial distribution of the various Ca2+ sources, Ca2+ sinks, and Ca2+-sensitive ion channels. Based on optical slices, we have previously constructed anatomically accurate three-dimensional models of seven salivary gland acinar cells, and thus shown that a model in which Ca2+ responses are confined to the apical regions of the cell is sufficient to provide a quantitative and predictive explanation of primary saliva secretion. However, reconstruction of such anatomically accurate cells is extremely time consuming and inefficient. Here, we present an alternative, mostly automated method of constructing three-dimensional cells that are approximately anatomically accurate and show that the new construction preserves the quantitative accuracy of the model.
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Affiliation(s)
- James Sneyd
- Department of Mathematics, University of Auckland, Auckland 1142, New Zealand
| | - John Rugis
- Department of Mathematics, University of Auckland, Auckland 1142, New Zealand
| | - Shan Su
- Department of Mathematics, University of Auckland, Auckland 1142, New Zealand
| | - Vinod Suresh
- Department of Engineering Science, University of Auckland, Auckland 1142, New Zealand
| | - Amanda M. Wahl
- Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14642, USA
| | - David I. Yule
- Department of Pharmacology and Physiology, University of Rochester, Rochester, NY 14642, USA
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11
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Li G, LeFebre R, Starman A, Chappell P, Mugler A, Sun B. Temporal signals drive the emergence of multicellular information networks. Proc Natl Acad Sci U S A 2022; 119:e2202204119. [PMID: 36067282 PMCID: PMC9477235 DOI: 10.1073/pnas.2202204119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 07/18/2022] [Indexed: 11/18/2022] Open
Abstract
Coordinated responses to environmental stimuli are critical for multicellular organisms. To overcome the obstacles of cell-to-cell heterogeneity and noisy signaling dynamics within individual cells, cells must effectively exchange information with peers. However, the dynamics and mechanisms of collective information transfer driven by external signals are poorly understood. Here we investigate the calcium dynamics of neuronal cells that form confluent monolayers and respond to cyclic ATP stimuli in microfluidic devices. Using Granger inference to reconstruct the underlying causal relations between the cells, we find that the cells self-organize into spatially decentralized and temporally stationary networks to support information transfer via gap junction channels. The connectivity of the causal networks depends on the temporal profile of the external stimuli, where short periods, or long periods with small duty fractions, lead to reduced connectivity and fractured network topology. We build a theoretical model based on communicating excitable units that reproduces our observations. The model further predicts that connectivity of the causal network is maximal at an optimal communication strength, which is confirmed by the experiments. Together, our results show that information transfer between neuronal cells is externally regulated by the temporal profile of the stimuli and internally regulated by cell-cell communication.
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Affiliation(s)
- Guanyu Li
- Department of Physics, Oregon State University, Corvallis, OR 97331
| | - Ryan LeFebre
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260
| | - Alia Starman
- Department of Biomedical Sciences, Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331
| | - Patrick Chappell
- Department of Biomedical Sciences, Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331
| | - Andrew Mugler
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260
| | - Bo Sun
- Department of Physics, Oregon State University, Corvallis, OR 97331
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12
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Victor MB, Leary N, Luna X, Meharena HS, Scannail AN, Bozzelli PL, Samaan G, Murdock MH, von Maydell D, Effenberger AH, Cerit O, Wen HL, Liu L, Welch G, Bonner M, Tsai LH. Lipid accumulation induced by APOE4 impairs microglial surveillance of neuronal-network activity. Cell Stem Cell 2022; 29:1197-1212.e8. [PMID: 35931030 DOI: 10.1016/j.stem.2022.07.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 05/31/2022] [Accepted: 07/13/2022] [Indexed: 01/02/2023]
Abstract
Apolipoprotein E4 (APOE4) is the greatest known genetic risk factor for developing sporadic Alzheimer's disease. How the interaction of APOE4 microglia with neurons differs from microglia expressing the disease-neutral APOE3 allele remains unknown. Here, we employ CRISPR-edited induced pluripotent stem cells (iPSCs) to dissect the impact of APOE4 in neuron-microglia communication. Our results reveal that APOE4 induces a lipid-accumulated state that renders microglia weakly responsive to neuronal activity. By examining the transcriptional signatures of APOE3 versus APOE4 microglia in response to neuronal conditioned media, we established that neuronal cues differentially induce a lipogenic program in APOE4 microglia that exacerbates pro-inflammatory signals. Through decreased uptake of extracellular fatty acids and lipoproteins, we identified that APOE4 microglia disrupts the coordinated activity of neuronal ensembles. These findings suggest that abnormal neuronal network-level disturbances observed in Alzheimer's disease patients harboring APOE4 may in part be triggered by impairment in lipid homeostasis in non-neuronal cells.
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13
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Guan Q, Queisser G. Modeling calcium dynamics in neurons with endoplasmic reticulum: existence, uniqueness and an implicit-explicit finite element scheme. Commun Nonlinear Sci Numer Simul 2022; 109:106354. [PMID: 35340896 PMCID: PMC8954672 DOI: 10.1016/j.cnsns.2022.106354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Like many other biological processes, calcium dynamics in neurons containing an endoplasmic reticulum is governed by diffusion-reaction equations on interface-separated domains. Interface conditions are typically described by systems of ordinary differential equations that provide fluxes across the interfaces. Using the calcium model as an example of this class of ODE-flux boundary interface problems, we prove the existence, uniqueness and boundedness of the solution by applying comparison theorem, fundamental solution of the parabolic operator and a strategy used in Picard's existence theorem. Then we propose and analyze an efficient implicit-explicit finite element scheme which is implicit for the parabolic operator and explicit for the nonlinear terms. We show that the stability does not depend on the spatial mesh size. Also the optimal convergence rate in H 1 norm is obtained. Numerical experiments illustrate the theoretical results.
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Affiliation(s)
| | - Gillian Queisser
- Department of Mathematics, Temple University, Philadelphia, PA 19122, USA
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14
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Pierantozzi E, Szentesi P, Paolini C, Dienes B, Fodor J, Oláh T, Colombini B, Rassier DE, Rubino EM, Lange S, Rossi D, Csernoch L, Bagni MA, Reggiani C, Sorrentino V. Impaired Intracellular Ca 2+ Dynamics, M-Band and Sarcomere Fragility in Skeletal Muscles of Obscurin KO Mice. Int J Mol Sci 2022; 23:1319. [PMID: 35163243 PMCID: PMC8835721 DOI: 10.3390/ijms23031319] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/19/2022] [Accepted: 01/20/2022] [Indexed: 12/16/2022] Open
Abstract
Obscurin is a giant sarcomeric protein expressed in striated muscles known to establish several interactions with other proteins of the sarcomere, but also with proteins of the sarcoplasmic reticulum and costameres. Here, we report experiments aiming to better understand the contribution of obscurin to skeletal muscle fibers, starting with a detailed characterization of the diaphragm muscle function, which we previously reported to be the most affected muscle in obscurin (Obscn) KO mice. Twitch and tetanus tension were not significantly different in the diaphragm of WT and Obscn KO mice, while the time to peak (TTP) and half relaxation time (HRT) were prolonged. Differences in force-frequency and force-velocity relationships and an enhanced fatigability are observed in an Obscn KO diaphragm with respect to WT controls. Voltage clamp experiments show that a sarcoplasmic reticulum's Ca2+ release and SERCA reuptake rates were decreased in muscle fibers from Obscn KO mice, suggesting that an impairment in intracellular Ca2+ dynamics could explain the observed differences in the TTP and HRT in the diaphragm. In partial contrast with previous observations, Obscn KO mice show a normal exercise tolerance, but fiber damage, the altered sarcomere ultrastructure and M-band disarray are still observed after intense exercise.
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Affiliation(s)
- Enrico Pierantozzi
- Department of Molecular and Developmental Medicine, Molecular Medicine Section, University of Siena, 53100 Siena, Italy; (E.P.); (E.M.R.); (D.R.)
| | - Péter Szentesi
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4002 Debrecen, Hungary; (P.S.); (B.D.); (J.F.); (T.O.); (L.C.)
| | - Cecilia Paolini
- Department of Neuroscience, Imaging and Clinical Sciences, University Gabriele d’ Annunzio of Chieti, 66100 Chieti, Italy;
| | - Beatrix Dienes
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4002 Debrecen, Hungary; (P.S.); (B.D.); (J.F.); (T.O.); (L.C.)
| | - János Fodor
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4002 Debrecen, Hungary; (P.S.); (B.D.); (J.F.); (T.O.); (L.C.)
| | - Tamás Oláh
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4002 Debrecen, Hungary; (P.S.); (B.D.); (J.F.); (T.O.); (L.C.)
| | - Barbara Colombini
- Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy; (B.C.); (M.A.B.)
| | - Dilson E. Rassier
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC H2W 1S4, Canada;
| | - Egidio Maria Rubino
- Department of Molecular and Developmental Medicine, Molecular Medicine Section, University of Siena, 53100 Siena, Italy; (E.P.); (E.M.R.); (D.R.)
| | - Stephan Lange
- Biomedical Research Facility 2, School of Medicine, University of California, La Jolla, CA 92093, USA;
- Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, 413 45 Gothenburg, Sweden
| | - Daniela Rossi
- Department of Molecular and Developmental Medicine, Molecular Medicine Section, University of Siena, 53100 Siena, Italy; (E.P.); (E.M.R.); (D.R.)
| | - László Csernoch
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4002 Debrecen, Hungary; (P.S.); (B.D.); (J.F.); (T.O.); (L.C.)
| | - Maria Angela Bagni
- Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy; (B.C.); (M.A.B.)
| | - Carlo Reggiani
- Department of Biomedical Science, University of Padova, 35121 Padova, Italy;
- Science and Research Center Koper, Institute for Kinesiology Research, 6000 Koper, Slovenia
| | - Vincenzo Sorrentino
- Department of Molecular and Developmental Medicine, Molecular Medicine Section, University of Siena, 53100 Siena, Italy; (E.P.); (E.M.R.); (D.R.)
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15
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Tabuchi A, Tanaka Y, Takagi R, Shirakawa H, Shibaguchi T, Sugiura T, Poole DC, Kano Y. Ryanodine receptors mediate high intracellular Ca 2+ and some myocyte damage following eccentric contractions in rat fast-twitch skeletal muscle. Am J Physiol Regul Integr Comp Physiol 2022; 322:R14-R27. [PMID: 34755549 DOI: 10.1152/ajpregu.00166.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 11/05/2021] [Indexed: 11/22/2022]
Abstract
Eccentric contractions (ECC) facilitate cytosolic calcium ion (Ca2+) release from the sarcoplasmic reticulum (SR) and Ca2+ influx from the extracellular space. Ca2+ is a vital signaling messenger that regulates multiple cellular processes via its spatial and temporal concentration ([Ca2+]i) dynamics. We hypothesized that 1) a specific pattern of spatial/temporal intramyocyte Ca2+ dynamics portends muscle damage following ECC and 2) these dynamics would be regulated by the ryanodine receptor (RyR). [Ca2+]i in the tibialis anterior muscles of anesthetized adult Wistar rats was measured by ratiometric (i.e., ratio, R, 340/380 nm excitation) in vivo bioimaging with Fura-2 pre-ECC and at 5 and 24 h post-ECC (5 × 40 contractions). Separate groups of rats received RyR inhibitor dantrolene (DAN; 10 mg/kg ip) immediately post-ECC (+DAN). Muscle damage was evaluated by histological analysis on hematoxylin-eosin stained muscle sections. Compared with control (CONT, no ECC), [Ca2+]i distribution was heterogeneous with increased percent total area of high [Ca2+]i sites (operationally defined as R ≥ 1.39, i.e., ≥1 SD of mean control) 5 h post-ECC (CONT, 14.0 ± 8.0; ECC5h: 52.0 ± 7.4%, P < 0.01). DAN substantially reduced the high [Ca2+]i area 5 h post-ECC (ECC5h + DAN: 6.4 ± 3.1%, P < 0.01) and myocyte damage (ECC24h, 63.2 ± 1.0%; ECC24h + DAN: 29.1 ± 2.2%, P < 0.01). Temporal and spatially amplified [Ca2+]i fluctuations occurred regardless of DAN (ECC vs. ECC + DAN, P > 0.05). These results suggest that the RyR-mediated local high [Ca2+]i itself is related to the magnitude of muscle damage, whereas the [Ca2+]i fluctuation is an RyR-independent phenomenon.
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Affiliation(s)
- Ayaka Tabuchi
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Chofu, Japan
- Research Fellowship for Young Scientists, Japan Society for the Promotion of Science, Tokyo, Japan
| | - Yoshinori Tanaka
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Chofu, Japan
- Center for Neuroscience and Biomedical Engineering, University of Electro-Communications, Chofu, Japan
| | - Ryo Takagi
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Chofu, Japan
- Research Fellowship for Young Scientists, Japan Society for the Promotion of Science, Tokyo, Japan
| | - Hideki Shirakawa
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Chofu, Japan
| | - Tsubasa Shibaguchi
- Institute of Liberal Arts and Science, Kanazawa University, Kanazawa, Japan
| | - Takao Sugiura
- Department of Exercise and Health Sciences, Faculty of Education, Yamaguchi University, Yamaguchi, Japan
| | - David C Poole
- Departments of Anatomy & Physiology and Kinesiology, Kansas State University, Manhattan, Kansas
| | - Yutaka Kano
- Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Chofu, Japan
- Center for Neuroscience and Biomedical Engineering, University of Electro-Communications, Chofu, Japan
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16
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Verma A, Manchel A, Narayanan R, Hoek JB, Ogunnaike BA, Vadigepalli R. A Spatial Model of Hepatic Calcium Signaling and Glucose Metabolism Under Autonomic Control Reveals Functional Consequences of Varying Liver Innervation Patterns Across Species. Front Physiol 2021; 12:748962. [PMID: 34899380 PMCID: PMC8662697 DOI: 10.3389/fphys.2021.748962] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 10/11/2021] [Indexed: 11/25/2022] Open
Abstract
Rapid breakdown of hepatic glycogen stores into glucose plays an important role during intense physical exercise to maintain systemic euglycemia. Hepatic glycogenolysis is governed by several different liver-intrinsic and systemic factors such as hepatic zonation, circulating catecholamines, hepatocellular calcium signaling, hepatic neuroanatomy, and the central nervous system (CNS). Of the factors regulating hepatic glycogenolysis, the extent of lobular innervation varies significantly between humans and rodents. While rodents display very few autonomic nerve terminals in the liver, nearly every hepatic layer in the human liver receives neural input. In the present study, we developed a multi-scale, multi-organ model of hepatic metabolism incorporating liver zonation, lobular scale calcium signaling, hepatic innervation, and direct and peripheral organ-mediated communication between the liver and the CNS. We evaluated the effect of each of these governing factors on the total hepatic glucose output and zonal glycogenolytic patterns within liver lobules during simulated physical exercise. Our simulations revealed that direct neuronal stimulation of the liver and an increase in circulating catecholamines increases hepatic glucose output mediated by mobilization of intracellular calcium stores and lobular scale calcium waves. Comparing simulated glycogenolysis between human-like and rodent-like hepatic innervation patterns (extensive vs. minimal) suggested that propagation of calcium transients across liver lobules acts as a compensatory mechanism to improve hepatic glucose output in sparsely innervated livers. Interestingly, our simulations suggested that catecholamine-driven glycogenolysis is reduced under portal hypertension. However, increased innervation coupled with strong intercellular communication can improve the total hepatic glucose output under portal hypertension. In summary, our modeling and simulation study reveals a complex interplay of intercellular and multi-organ interactions that can lead to differing calcium dynamics and spatial distributions of glycogenolysis at the lobular scale in the liver.
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Affiliation(s)
- Aalap Verma
- Department of Biomedical Engineering, University of Delaware, Newark, DE, United States.,Daniel Baugh Institute for Functional Genomics and Computational Biology, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Alexandra Manchel
- Daniel Baugh Institute for Functional Genomics and Computational Biology, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Rahul Narayanan
- Daniel Baugh Institute for Functional Genomics and Computational Biology, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Jan B Hoek
- Daniel Baugh Institute for Functional Genomics and Computational Biology, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA, United States
| | - Babatunde A Ogunnaike
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, United States
| | - Rajanikanth Vadigepalli
- Daniel Baugh Institute for Functional Genomics and Computational Biology, Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA, United States
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17
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Deng X, Yao XQ, Berglund K, Dong B, Ouedraogo D, Ghane MA, Zhuo Y, McBean C, Wei ZZ, Gozem S, Yu SP, Wei L, Fang N, Mabb AM, Gadda G, Hamelberg D, Yang JJ. Tuning Protein Dynamics to Sense Rapid Endoplasmic-Reticulum Calcium Dynamics. Angew Chem Int Ed Engl 2021; 60:23289-23298. [PMID: 34436811 DOI: 10.1002/anie.202108443] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Indexed: 11/11/2022]
Abstract
Multi-scale calcium (Ca2+ ) dynamics, exhibiting wide-ranging temporal kinetics, constitutes a ubiquitous mode of signal transduction. We report a novel endoplasmic-reticulum (ER)-targeted Ca2+ indicator, R-CatchER, which showed superior kinetics in vitro (koff ≥2×103 s-1 , kon ≥7×106 M-1 s-1 ) and in multiple cell types. R-CatchER captured spatiotemporal ER Ca2+ dynamics in neurons and hotspots at dendritic branchpoints, enabled the first report of ER Ca2+ oscillations mediated by calcium sensing receptors (CaSRs), and revealed ER Ca2+ -based functional cooperativity of CaSR. We elucidate the mechanism of R-CatchER and propose a principle to rationally design genetically encoded Ca2+ indicators with a single Ca2+ -binding site and fast kinetics by tuning rapid fluorescent-protein dynamics and the electrostatic potential around the chromophore. The design principle is supported by the development of G-CatchER2, an upgrade of our previous (G-)CatchER with improved dynamic range. Our work may facilitate protein design, visualizing Ca2+ dynamics, and drug discovery.
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Affiliation(s)
- Xiaonan Deng
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, 50 Decatur Street, 552 NSC, Atlanta, GA, 30303, USA
| | - Xin-Qiu Yao
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, 50 Decatur Street, 552 NSC, Atlanta, GA, 30303, USA
| | - Ken Berglund
- Department of Neurosurgery, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Bin Dong
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, 50 Decatur Street, 552 NSC, Atlanta, GA, 30303, USA
| | - Daniel Ouedraogo
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, 50 Decatur Street, 552 NSC, Atlanta, GA, 30303, USA
| | - Mohammad A Ghane
- Neuroscience Institute, Georgia State University, Atlanta, GA, 30303, USA.,Center for Behavioral Neuroscience, Georgia State University, Atlanta, GA, 30303, USA
| | - You Zhuo
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, 50 Decatur Street, 552 NSC, Atlanta, GA, 30303, USA
| | - Cheyenne McBean
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, 50 Decatur Street, 552 NSC, Atlanta, GA, 30303, USA
| | - Zheng Zachory Wei
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Samer Gozem
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, 50 Decatur Street, 552 NSC, Atlanta, GA, 30303, USA
| | - Shan P Yu
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Ling Wei
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Ning Fang
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, 50 Decatur Street, 552 NSC, Atlanta, GA, 30303, USA
| | - Angela M Mabb
- Neuroscience Institute, Georgia State University, Atlanta, GA, 30303, USA.,Center for Behavioral Neuroscience, Georgia State University, Atlanta, GA, 30303, USA
| | - Giovanni Gadda
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, 50 Decatur Street, 552 NSC, Atlanta, GA, 30303, USA
| | - Donald Hamelberg
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, 50 Decatur Street, 552 NSC, Atlanta, GA, 30303, USA
| | - Jenny J Yang
- Department of Chemistry, Center for Diagnostics and Therapeutics, Advanced Translational Imaging Facility, Georgia State University, 50 Decatur Street, 552 NSC, Atlanta, GA, 30303, USA
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18
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Staege S, Kutschenko A, Baumann H, Glaß H, Henkel L, Gschwendtberger T, Kalmbach N, Klietz M, Hermann A, Lohmann K, Seibler P, Wegner F. Reduced Expression of GABA A Receptor Alpha2 Subunit Is Associated With Disinhibition of DYT-THAP1 Dystonia Patient-Derived Striatal Medium Spiny Neurons. Front Cell Dev Biol 2021; 9:650586. [PMID: 34095114 PMCID: PMC8176025 DOI: 10.3389/fcell.2021.650586] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 04/08/2021] [Indexed: 12/18/2022] Open
Abstract
DYT-THAP1 dystonia (formerly DYT6) is an adolescent-onset dystonia characterized by involuntary muscle contractions usually involving the upper body. It is caused by mutations in the gene THAP1 encoding for the transcription factor Thanatos-associated protein (THAP) domain containing apoptosis-associated protein 1 and inherited in an autosomal-dominant manner with reduced penetrance. Alterations in the development of striatal neuronal projections and synaptic function are known from transgenic mice models. To investigate pathogenetic mechanisms, human induced pluripotent stem cell (iPSC)-derived medium spiny neurons (MSNs) from two patients and one family member with reduced penetrance carrying a mutation in the gene THAP1 (c.474delA and c.38G > A) were functionally characterized in comparison to healthy controls. Calcium imaging and quantitative PCR analysis revealed significantly lower Ca2+ amplitudes upon GABA applications and a marked downregulation of the gene encoding the GABAA receptor alpha2 subunit in THAP1 MSNs indicating a decreased GABAergic transmission. Whole-cell patch-clamp recordings showed a significantly lower frequency of miniature postsynaptic currents (mPSCs), whereas the frequency of spontaneous action potentials (APs) was elevated in THAP1 MSNs suggesting that decreased synaptic activity might have resulted in enhanced generation of APs. Our molecular and functional data indicate that a reduced expression of GABAA receptor alpha2 subunit could eventually lead to limited GABAergic synaptic transmission, neuronal disinhibition, and hyperexcitability of THAP1 MSNs. These data give pathophysiological insight and may contribute to the development of novel treatment strategies for DYT-THAP1 dystonia.
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Affiliation(s)
- Selma Staege
- Department of Neurology, Hannover Medical School, Hanover, Germany.,Center for Systems Neuroscience, Hanover, Germany
| | - Anna Kutschenko
- Department of Neurology, Hannover Medical School, Hanover, Germany
| | - Hauke Baumann
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
| | - Hannes Glaß
- Translational Neurodegeneration Section "Albrecht-Kossel", Department of Neurology, University of Rostock, Rostock, Germany
| | - Lisa Henkel
- Department of Neurology, Hannover Medical School, Hanover, Germany.,Center for Systems Neuroscience, Hanover, Germany
| | - Thomas Gschwendtberger
- Department of Neurology, Hannover Medical School, Hanover, Germany.,Center for Systems Neuroscience, Hanover, Germany
| | - Norman Kalmbach
- Department of Neurology, Hannover Medical School, Hanover, Germany
| | - Martin Klietz
- Department of Neurology, Hannover Medical School, Hanover, Germany
| | - Andreas Hermann
- Translational Neurodegeneration Section "Albrecht-Kossel", Department of Neurology, University of Rostock, Rostock, Germany.,German Center for Neurodegenerative Diseases Rostock/Greifswald, Rostock, Germany
| | - Katja Lohmann
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
| | - Philip Seibler
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
| | - Florian Wegner
- Department of Neurology, Hannover Medical School, Hanover, Germany.,Center for Systems Neuroscience, Hanover, Germany
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19
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Kutschenko A, Staege S, Grütz K, Glaß H, Kalmbach N, Gschwendtberger T, Henkel LM, Heine J, Grünewald A, Hermann A, Seibler P, Wegner F. Functional and Molecular Properties of DYT-SGCE Myoclonus-Dystonia Patient-Derived Striatal Medium Spiny Neurons. Int J Mol Sci 2021; 22:3565. [PMID: 33808167 PMCID: PMC8037318 DOI: 10.3390/ijms22073565] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 03/18/2021] [Accepted: 03/24/2021] [Indexed: 01/20/2023] Open
Abstract
Myoclonus-dystonia (DYT-SGCE, formerly DYT11) is characterized by alcohol-sensitive, myoclonic-like appearance of fast dystonic movements. It is caused by mutations in the SGCE gene encoding ε-sarcoglycan leading to a dysfunction of this transmembrane protein, alterations in the cerebello-thalamic pathway and impaired striatal plasticity. To elucidate underlying pathogenic mechanisms, we investigated induced pluripotent stem cell (iPSC)-derived striatal medium spiny neurons (MSNs) from two myoclonus-dystonia patients carrying a heterozygous mutation in the SGCE gene (c.298T>G and c.304C>T with protein changes W100G and R102X) in comparison to two matched healthy control lines. Calcium imaging showed significantly elevated basal intracellular Ca2+ content and lower frequency of spontaneous Ca2+ signals in SGCE MSNs. Blocking of voltage-gated Ca2+ channels by verapamil was less efficient in suppressing KCl-induced Ca2+ peaks of SGCE MSNs. Ca2+ amplitudes upon glycine and acetylcholine applications were increased in SGCE MSNs, but not after GABA or glutamate applications. Expression of voltage-gated Ca2+ channels and most ionotropic receptor subunits was not altered. SGCE MSNs showed significantly reduced GABAergic synaptic density. Whole-cell patch-clamp recordings displayed elevated amplitudes of miniature postsynaptic currents and action potentials in SGCE MSNs. Our data contribute to a better understanding of the pathophysiology and the development of novel therapeutic strategies for myoclonus-dystonia.
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Grants
- Karlheinz-Hartmann-Stiftung (Hannover, Germany), Ellen-Schmidt-Program (Hannover, Germany), Hermann and Lilly Schilling Stiftung für medizinische Forschung im Stifterverband, German Research Foundation (FOR2488) Karlheinz-Hartmann-Stiftung (Hannover, Germany), Ellen-Schmidt-Program (Hannover, Germany), Hermann and Lilly Schilling Stiftung für medizinische Forschung im Stifterverband, German Research Foundation (FOR2488)
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Affiliation(s)
- Anna Kutschenko
- Department of Neurology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany; (A.K.); (S.S.); (N.K.); (T.G.); (L.M.H.); (J.H.)
| | - Selma Staege
- Department of Neurology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany; (A.K.); (S.S.); (N.K.); (T.G.); (L.M.H.); (J.H.)
- Center for Systems Neuroscience, Bünteweg 2, 30559 Hannover, Germany
| | - Karen Grütz
- Institute of Neurogenetics, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany; (K.G.); (A.G.); (P.S.)
| | - Hannes Glaß
- Translational Neurodegeneration Section “Albrecht-Kossel“, Department of Neurology, University Medical Center, University of Rostock, Gehlsheimer Str. 20, 18147 Rostock, Germany; (H.G.); (A.H.)
| | - Norman Kalmbach
- Department of Neurology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany; (A.K.); (S.S.); (N.K.); (T.G.); (L.M.H.); (J.H.)
| | - Thomas Gschwendtberger
- Department of Neurology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany; (A.K.); (S.S.); (N.K.); (T.G.); (L.M.H.); (J.H.)
- Center for Systems Neuroscience, Bünteweg 2, 30559 Hannover, Germany
| | - Lisa M. Henkel
- Department of Neurology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany; (A.K.); (S.S.); (N.K.); (T.G.); (L.M.H.); (J.H.)
- Center for Systems Neuroscience, Bünteweg 2, 30559 Hannover, Germany
| | - Johanne Heine
- Department of Neurology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany; (A.K.); (S.S.); (N.K.); (T.G.); (L.M.H.); (J.H.)
| | - Anne Grünewald
- Institute of Neurogenetics, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany; (K.G.); (A.G.); (P.S.)
| | - Andreas Hermann
- Translational Neurodegeneration Section “Albrecht-Kossel“, Department of Neurology, University Medical Center, University of Rostock, Gehlsheimer Str. 20, 18147 Rostock, Germany; (H.G.); (A.H.)
- German Center for Neurodegenerative Diseases Rostock/Greifswald, 18147 Rostock, Germany
- Center for Transdisciplinary Neurosciences Rostock (CTNR), University Medical Center, University of Rostock, 18147 Rostock, Germany
| | - Philip Seibler
- Institute of Neurogenetics, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany; (K.G.); (A.G.); (P.S.)
| | - Florian Wegner
- Department of Neurology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany; (A.K.); (S.S.); (N.K.); (T.G.); (L.M.H.); (J.H.)
- Center for Systems Neuroscience, Bünteweg 2, 30559 Hannover, Germany
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20
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Affiliation(s)
- Shobana Subramanian
- Department of Internal Medicine, Section of Endocrinology, Yale University School of Medicine, New Haven, CT, USA
| | - Elizabeth A Jonas
- Department of Internal Medicine, Section of Endocrinology, Yale University School of Medicine, New Haven, CT, USA.,Marine Biological Laboratory, Woods Hole, MA, USA
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21
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Phillips KF, Deshpande LS. Calcium Hypothesis of Gulf War Illness: Role of Calcium Ions in Neurological Morbidities in a DFP-Based Rat Model for Gulf War Illness. Neurosci Insights 2020; 15:2633105520979841. [PMID: 33354668 PMCID: PMC7734545 DOI: 10.1177/2633105520979841] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 11/19/2020] [Indexed: 12/27/2022] Open
Abstract
Gulf War Illness (GWI) refers to a multi-system disorder that afflicts approximately 30% of First Gulf War (GW) veterans. Amongst the symptoms exhibited, mood and memory impairment are commonly reported by GW veterans. Exposure to organophosphate (OP) compounds which target the cholinergic system is considered a leading cause for GWI symptoms. It is hypothesized that chronic OP-based war-time stimulation of cholinergic signaling led to recruitment of excitatory glutamatergic signaling and other downstream signaling cascades leading to neuronal injury, neuroinflammation, generation of reactive oxygen species, oxidative stress, and mitochondrial damage within the central nervous system. These findings have been observed in both experimental models and GWI veterans. In this context the role of calcium (Ca2+) signaling in GWI has come to the forefront. Here we present our Ca2+ hypothesis of GWI that suggests sustained neuronal Ca2+ elevations serve as a molecular trigger for pathological synaptic plasticity that has allowed for the persistence of GWI symptoms. Subsequently we discuss that therapeutic targeting of Ca2+ homeostatic mechanisms provides novel targets for effective treatment of GWI-related neurological signs in our rodent model.
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Affiliation(s)
| | - Laxmikant S Deshpande
- Department of Neurology, School of Medicine, Virginia Commonwealth University, Richmond, USA.,Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond, USA
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22
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Álvarez-Illera P, García-Casas P, Fonteriz RI, Montero M, Alvarez J. Mitochondrial Ca 2+ Dynamics in MCU Knockout C. elegans Worms. Int J Mol Sci 2020; 21:ijms21228622. [PMID: 33207633 PMCID: PMC7696937 DOI: 10.3390/ijms21228622] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 11/04/2020] [Accepted: 11/13/2020] [Indexed: 01/16/2023] Open
Abstract
Mitochondrial [Ca2+] plays an important role in the regulation of mitochondrial function, controlling ATP production and apoptosis triggered by mitochondrial Ca2+ overload. This regulation depends on Ca2+ entry into the mitochondria during cell activation processes, which is thought to occur through the mitochondrial Ca2+ uniporter (MCU). Here, we have studied the mitochondrial Ca2+ dynamics in control and MCU-defective C. elegans worms in vivo, by using worms expressing mitochondrially-targeted YC3.60 yellow cameleon in pharynx muscle. Our data show that the small mitochondrial Ca2+ oscillations that occur during normal physiological activity of the pharynx were very similar in both control and MCU-defective worms, except for some kinetic differences that could mostly be explained by changes in neuronal stimulation of the pharynx. However, direct pharynx muscle stimulation with carbachol triggered a large and prolonged increase in mitochondrial [Ca2+] that was much larger in control worms than in MCU-defective worms. This suggests that MCU is necessary for the fast mitochondrial Ca2+ uptake induced by large cell stimulations. However, low-amplitude mitochondrial Ca2+ oscillations occurring under more physiological conditions are independent of the MCU and use a different Ca2+ pathway.
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23
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Guo J, Simmons DW, Ramahdita G, Munsell MK, Oguntuyo K, Kandalaft B, Rios B, Pear M, Schuftan D, Jiang H, Lake SP, Genin GM, Huebsch N. Elastomer-Grafted iPSC-Derived Micro Heart Muscles to Investigate Effects of Mechanical Loading on Physiology. ACS Biomater Sci Eng 2020; 7:2973-2989. [PMID: 34275296 DOI: 10.1021/acsbiomaterials.0c00318] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Mechanical loading plays a critical role in cardiac pathophysiology. Engineered heart tissues derived from human induced pluripotent stem cells (iPSCs) allow rigorous investigations of the molecular and pathophysiological consequences of mechanical cues. However, many engineered heart muscle models have complex fabrication processes and require large cell numbers, making it difficult to use them together with iPSC-derived cardiomyocytes to study the influence of mechanical loading on pharmacology and genotype-phenotype relationships. To address this challenge, simple and scalable iPSC-derived micro-heart-muscle arrays (μHM) have been developed. "Dog-bone-shaped" molds define the boundary conditions for tissue formation. Here, we extend the μHM model by forming these tissues on elastomeric substrates with stiffnesses spanning from 5 to 30 kPa. Tissue assembly was achieved by covalently grafting fibronectin to the substrate. Compared to μHM formed on plastic, elastomer-grafted μHM exhibited a similar gross morphology, sarcomere assembly, and tissue alignment. When these tissues were formed on substrates with different elasticity, we observed marked shifts in contractility. Increased contractility was correlated with increases in calcium flux and a slight increase in cell size. This afterload-enhanced μHM system enables mechanical control of μHM and real-time tissue traction force microscopy for cardiac physiology measurements, providing a dynamic tool for studying pathophysiology and pharmacology.
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Affiliation(s)
- Jingxuan Guo
- Department of Mechanical Engineering and Materials Science, Washington University in Saint Louis, University City, St. Louis, Missouri 63130, United States
| | - Daniel W Simmons
- Department of Biomedical Engineering, Washington University in Saint Louis, University City, St. Louis, Missouri 63130, United States.,NSF Science and Technology Center for Engineering Mechanobiology, McKelvey School of Engineering, 1 Brookings Dr., St. Louis, Missouri 63130, United States
| | - Ghiska Ramahdita
- Department of Mechanical Engineering and Materials Science, Washington University in Saint Louis, University City, St. Louis, Missouri 63130, United States.,NSF Science and Technology Center for Engineering Mechanobiology, McKelvey School of Engineering, 1 Brookings Dr., St. Louis, Missouri 63130, United States
| | - Mary K Munsell
- Department of Biomedical Engineering, Washington University in Saint Louis, University City, St. Louis, Missouri 63130, United States
| | - Kasoorelope Oguntuyo
- Department of Biomedical Engineering, Washington University in Saint Louis, University City, St. Louis, Missouri 63130, United States
| | - Brennan Kandalaft
- Department of Biomedical Engineering, Washington University in Saint Louis, University City, St. Louis, Missouri 63130, United States
| | - Brandon Rios
- Department of Biomedical Engineering, Washington University in Saint Louis, University City, St. Louis, Missouri 63130, United States
| | - Missy Pear
- Department of Biomedical Engineering, Washington University in Saint Louis, University City, St. Louis, Missouri 63130, United States
| | - David Schuftan
- Department of Biomedical Engineering, Washington University in Saint Louis, University City, St. Louis, Missouri 63130, United States
| | - Huanzhu Jiang
- Department of Biomedical Engineering, Washington University in Saint Louis, University City, St. Louis, Missouri 63130, United States
| | - Spencer P Lake
- Department of Mechanical Engineering and Materials Science, Washington University in Saint Louis, University City, St. Louis, Missouri 63130, United States
| | - Guy M Genin
- Department of Mechanical Engineering and Materials Science, Washington University in Saint Louis, University City, St. Louis, Missouri 63130, United States.,NSF Science and Technology Center for Engineering Mechanobiology, McKelvey School of Engineering, 1 Brookings Dr., St. Louis, Missouri 63130, United States
| | - Nathaniel Huebsch
- Department of Biomedical Engineering, Washington University in Saint Louis, University City, St. Louis, Missouri 63130, United States.,NSF Science and Technology Center for Engineering Mechanobiology, McKelvey School of Engineering, 1 Brookings Dr., St. Louis, Missouri 63130, United States.,Center for Cardiovascular Research, Center for Regenerative Medicine, Center for Investigation of Membrane Excitability Diseases, Washington University in Saint Louis, University City, St. Louis, Missouri 63130, United States
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24
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Povo-Retana A, Mojena M, Stremtan AB, Fernández-García VB, Gómez-Sáez A, Nuevo-Tapioles C, Molina-Guijarro JM, Avendaño-Ortiz J, Cuezva JM, López-Collazo E, Martínez-Leal JF, Boscá L. Specific Effects of Trabectedin and Lurbinectedin on Human Macrophage Function and Fate-Novel Insights. Cancers (Basel) 2020; 12:cancers12103060. [PMID: 33092171 PMCID: PMC7590144 DOI: 10.3390/cancers12103060] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 09/28/2020] [Accepted: 10/16/2020] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Tumor-associated macrophages (TAMs) play a crucial role in suppressing the immunosurveillance function of the immune system that prevents tumor growth. Indeed, macrophages can also be targeted by different chemotherapeutic agents improving the action over immune checkpoints to fight cancer. Here we describe the effect of trabectedin and lurbinectedin on human macrophage cell viability and function. METHODS Blood monocytes from healthy donors were differentiated into macrophages and exposed to different stimuli promoting functional polarization and differentiation into tumor-associated macrophages. Cells were challenged with the chemotherapeutic drugs and the effects on cell viability and function were analyzed. RESULTS Human macrophages exhibit at least two different profiles in response to these drugs. One-fourth of the blood donors assayed (164 individuals) were extremely sensitive to trabectedin and lurbinectedin, which promoted apoptotic cell death. Macrophages from other individuals retained viability but responded to the drugs increasing reactive oxygen production and showing a rapid intracellular calcium rise and a loss of mitochondrial oxygen consumption. Cell-membrane exposure of programmed-death ligand 1 (PD-L1) significantly decreased after treatment with therapeutic doses of these drugs, including changes in the gene expression profile of hypoxia-inducible factor 1 alpha (HIF-1α)-dependent genes, among other. CONCLUSIONS The results provide evidence of additional onco-therapeutic actions for these drugs.
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Affiliation(s)
- Adrián Povo-Retana
- Instituto de Investigaciones Biomédicas Alberto Sols (Centro Mixto CSIC-UAM), 28029 Madrid, Spain; (A.P.-R.); (M.M.); (A.B.S.); (V.B.F.-G.); (A.G.-S.)
| | - Marina Mojena
- Instituto de Investigaciones Biomédicas Alberto Sols (Centro Mixto CSIC-UAM), 28029 Madrid, Spain; (A.P.-R.); (M.M.); (A.B.S.); (V.B.F.-G.); (A.G.-S.)
| | - Adrian B. Stremtan
- Instituto de Investigaciones Biomédicas Alberto Sols (Centro Mixto CSIC-UAM), 28029 Madrid, Spain; (A.P.-R.); (M.M.); (A.B.S.); (V.B.F.-G.); (A.G.-S.)
| | - Victoria B. Fernández-García
- Instituto de Investigaciones Biomédicas Alberto Sols (Centro Mixto CSIC-UAM), 28029 Madrid, Spain; (A.P.-R.); (M.M.); (A.B.S.); (V.B.F.-G.); (A.G.-S.)
| | - Ana Gómez-Sáez
- Instituto de Investigaciones Biomédicas Alberto Sols (Centro Mixto CSIC-UAM), 28029 Madrid, Spain; (A.P.-R.); (M.M.); (A.B.S.); (V.B.F.-G.); (A.G.-S.)
| | - Cristina Nuevo-Tapioles
- Centro de Biología Molecular (Centro Mixto CSIC-UAM), Nicolás Cabrera S/N, Ciudad Universitaria de Cantoblanco, 28049 Madrid, Spain; (C.N.-T.); (J.M.C.)
- Centro de Investigación Biomédica en Red en Enfermedades Raras (CIBERER), 28029 Madrid, Spain
| | | | - José Avendaño-Ortiz
- Instituto de Investigación Sanitaria La Paz (IdiPaz), Hospital Universitario La Paz, 28046 Madrid, Spain; (J.A.-O.); (E.L.-C.)
| | - José M. Cuezva
- Centro de Biología Molecular (Centro Mixto CSIC-UAM), Nicolás Cabrera S/N, Ciudad Universitaria de Cantoblanco, 28049 Madrid, Spain; (C.N.-T.); (J.M.C.)
- Centro de Investigación Biomédica en Red en Enfermedades Raras (CIBERER), 28029 Madrid, Spain
| | - Eduardo López-Collazo
- Instituto de Investigación Sanitaria La Paz (IdiPaz), Hospital Universitario La Paz, 28046 Madrid, Spain; (J.A.-O.); (E.L.-C.)
| | | | - Lisardo Boscá
- Instituto de Investigaciones Biomédicas Alberto Sols (Centro Mixto CSIC-UAM), 28029 Madrid, Spain; (A.P.-R.); (M.M.); (A.B.S.); (V.B.F.-G.); (A.G.-S.)
- Instituto de Investigación Sanitaria La Paz (IdiPaz), Hospital Universitario La Paz, 28046 Madrid, Spain; (J.A.-O.); (E.L.-C.)
- Centro de Investigación Biomédica en Red en Enfermedades Cardiovasculares (CIBERCV), 28029 Madrid, Spain
- Correspondence: ; Tel.: +34-9149-72747
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25
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Ribeiro ACR, Zhu J, Kronfol MM, Jahr FM, Younis RM, Hawkins E, McClay JL, Deshpande LS. Molecular mechanisms for the antidepressant-like effects of a low-dose ketamine treatment in a DFP-based rat model for Gulf War Illness. Neurotoxicology 2020; 80:52-59. [PMID: 32592718 DOI: 10.1016/j.neuro.2020.06.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 06/16/2020] [Accepted: 06/22/2020] [Indexed: 12/31/2022]
Abstract
Exposure to organophosphates (OP) during the First Gulf War is among one of the factors for Gulf War Illness (GWI) development in veterans and it has been challenging to treat GWI symptoms with existing therapies. Ketamine produces a rapid-onset and sustained antidepressant response, but there is no evidence whether ketamine treatment is effective for GWI depression. Repeated, low-dose exposure to diisopropyl fluorophosphate (DFP) mimic Gulf War related OP exposures and produces a chronic depressive state in rats. In this study, DFP-exposed rats treated with ketamine (10 mg/kg, i.p.) exhibited antidepressant-like effect on the Forced Swim Test at 1-h. This effect persisted at 24-h post ketamine, a time-point by which it is eliminated from the brain suggesting involvement of mechanisms that affect long-term synaptic plasticity. Western blot analysis showed significantly lower Brain-Derived Neurotrophic Factor (BDNF) levels in DFP rat brains. Ketamine produced a nonsignificant increase in BDNF expression at 1-h but produced a larger, significant (2.2-fold) increase at 24-h in DFP rats. We previously reported chronic hippocampal calcium elevations ([Ca2+]i) in DFP rats. Ketamine-treated DFP rats exhibited significantly lower [Ca2+]i at 1-h but not at 24-h. Interestingly, treatment with ANA-12, a TrkB-BDNF receptor antagonist, in DFP rats blunted ketamine's antidepressant-like effect at 24-h but not at 1-h. These experiments suggest that in a rat model of DFP-induced depression, inhibition of the NMDAR-Ca2+ contributes to the rapid-onset antidepressant effects of ketamine while the antidepressant actions that persisted at 24-h post ketamine administration involve upregulation of BDNF signaling.
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Affiliation(s)
- Ana C R Ribeiro
- Departments of Neurology, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - Jackie Zhu
- Department of Biology, College of Humanities & Sciences, Virginia Commonwealth University, Richmond, VA, USA
| | - Mohamad M Kronfol
- Department of Pharmacotherapy & Outcome Sciences, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, USA
| | - Fay M Jahr
- Department of Pharmacotherapy & Outcome Sciences, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, USA
| | - Rabha M Younis
- Department of Pharmacotherapy & Outcome Sciences, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, USA
| | - Elisa Hawkins
- Departments of Neurology, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - Joseph L McClay
- Department of Pharmacotherapy & Outcome Sciences, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, USA
| | - Laxmikant S Deshpande
- Departments of Neurology, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA; Pharmacology and Toxicology, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA.
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26
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Gordan R, Fefelova N, Gwathmey JK, Xie LH. Iron Overload, Oxidative Stress and Calcium Mishandling in Cardiomyocytes: Role of the Mitochondrial Permeability Transition Pore. Antioxidants (Basel) 2020; 9:E758. [PMID: 32824344 PMCID: PMC7465659 DOI: 10.3390/antiox9080758] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 08/10/2020] [Accepted: 08/13/2020] [Indexed: 12/12/2022] Open
Abstract
Iron (Fe) plays an essential role in many physiological processes. Hereditary hemochromatosis or frequent blood transfusions often cause iron overload (IO), which can lead to cardiomyopathy and arrhythmias; however, the underlying mechanism is not well defined. In the present study, we assess the hypothesis that IO promotes arrhythmias via reactive oxygen species (ROS) production, mitochondrial membrane potential (∆Ψm) depolarization, and disruption of cytosolic Ca dynamics. In ventricular myocytes isolated from wild type (WT) mice, both cytosolic and mitochondrial Fe levels were elevated following perfusion with the Fe3+/8-hydroxyquinoline (8-HQ) complex. IO promoted mitochondrial superoxide generation (measured using MitoSOX Red) and induced the depolarization of the ΔΨm (measured using tetramethylrhodamine methyl ester, TMRM) in a dose-dependent manner. IO significantly increased the rate of Ca wave (CaW) formation measured in isolated ventricular myocytes using Fluo-4. Furthermore, in ex-vivo Langendorff-perfused hearts, IO increased arrhythmia scores as evaluated by ECG recordings under programmed S1-S2 stimulation protocols. We also carried out similar experiments in cyclophilin D knockout (CypD KO) mice in which the mitochondrial permeability transition pore (mPTP) opening is impaired. While comparable cytosolic and mitochondrial Fe load, mitochondrial ROS production, and depolarization of the ∆Ψm were observed in ventricular myocytes isolated from both WT and CypD KO mice, the rate of CaW formation in isolated cells and the arrhythmia scores in ex-vivo hearts were significantly lower in CypD KO mice compared to those observed in WT mice under conditions of IO. The mPTP inhibitor cyclosporine A (CsA, 1 µM) also exhibited a protective effect. In conclusion, our results suggest that IO induces mitochondrial ROS generation and ∆Ψm depolarization, thus opening the mPTP, thereby promoting CaWs and cardiac arrhythmias. Conversely, the inhibition of mPTP ameliorates the proarrhythmic effects of IO.
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Affiliation(s)
| | | | | | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, Rutgers University-New Jersey Medical School, Newark, NJ 07103, USA; (R.G.); (N.F.); (J.K.G.)
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27
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Carichino L, Olson SD. Emergent three-dimensional sperm motility: coupling calcium dynamics and preferred curvature in a Kirchhoff rod model. Math Med Biol 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] [What about the content of this article? (0)] [Affiliation(s)] [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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28
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Ambrogini P, Lattanzi D, Di Palma M, Ciacci C, Savelli D, Galati C, Gioacchini AM, Pietrangelo L, Vallorani L, Protasi F, Cuppini R. Calsequestrin Deletion Facilitates Hippocampal Synaptic Plasticity and Spatial Learning in Post-Natal Development. Int J Mol Sci 2020; 21:E5473. [PMID: 32751833 DOI: 10.3390/ijms21155473] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 07/15/2020] [Accepted: 07/30/2020] [Indexed: 11/17/2022] Open
Abstract
Experimental evidence highlights the involvement of the endoplasmic reticulum (ER)-mediated Ca2+ signals in modulating synaptic plasticity and spatial memory formation in the hippocampus. Ca2+ release from the ER mainly occurs through two classes of Ca2+ channels, inositol 1,4,5-trisphosphate receptors (InsP3Rs) and ryanodine receptors (RyRs). Calsequestrin (CASQ) and calreticulin (CR) are the most abundant Ca2+-binding proteins allowing ER Ca2+ storage. The hippocampus is one of the brain regions expressing CASQ, but its role in neuronal activity, plasticity, and the learning processes is poorly investigated. Here, we used knockout mice lacking both CASQ type-1 and type-2 isoforms (double (d)CASQ-null mice) to: a) evaluate in adulthood the neuronal electrophysiological properties and synaptic plasticity in the hippocampal Cornu Ammonis 1 (CA1) field and b) study the performance of knockout mice in spatial learning tasks. The ablation of CASQ increased the CA1 neuron excitability and improved the long-term potentiation (LTP) maintenance. Consistently, (d)CASQ-null mice performed significantly better than controls in the Morris Water Maze task, needing a shorter time to develop a spatial preference for the goal. The Ca2+ handling analysis in CA1 pyramidal cells showed a decrement of Ca2+ transient amplitude in (d)CASQ-null mouse neurons, which is consistent with a decrease in afterhyperpolarization improving LTP. Altogether, our findings suggest that CASQ deletion affects activity-dependent ER Ca2+ release, thus facilitating synaptic plasticity and spatial learning in post-natal development.
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29
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Phillips KF, Santos E, Blair RE, Deshpande LS. Targeting Intracellular Calcium Stores Alleviates Neurological Morbidities in a DFP-Based Rat Model of Gulf War Illness. Toxicol Sci 2020; 169:567-578. [PMID: 30859209 PMCID: PMC6542335 DOI: 10.1093/toxsci/kfz070] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Gulf War Illness (GWI) is a chronic multi-symptom disorder afflicting the veterans of the First Gulf War, and includes neurological symptoms characterized by depression and memory deficits. Chronic exposure to organophosphates (OPs) is considered a leading cause for GWI, yet its pathobiology is not fully understood. We recently observed chronic elevations in neuronal Ca2+ levels ([Ca2+]i) in an OP-diisopropyl fluorophosphate (DFP)-based rat model for GWI. This study was aimed at identifying mechanisms underlying elevated [Ca2+]i in this DFP model and investigating whether their therapeutic targeting could improve GWI-like neurological morbidities. Male Sprague-Dawley rats (9 weeks) were exposed to DFP (0.5 mg/kg, s.c., 1×-daily for 5 days) and at 3 months postDFP exposure, behavior was assessed and rats were euthanized for protein estimations and ratiometric Fura-2 [Ca2+]i estimations in acutely dissociated hippocampal neurons. In DFP rats, a sustained elevation in intracellular Ca2+ levels occurred, and pharmacological blockade of Ca2+-induced Ca2+-release mechanisms significantly lowered elevated [Ca2+]i in DFP neurons. Significant reductions in the protein levels of the ryanodine receptor (RyR) stabilizing protein Calstabin2 were also noted. Such a posttranslational modification would render RyR “leaky” resulting in sustained DFP [Ca2+]i elevations. Antagonism of RyR with levetiracetam significantly lower elevated [Ca2+]i in DFP neurons and improved GWI-like behavioral symptoms. Since Ca2+ is a major second messenger molecule, such chronic increases in its levels could underlie pathological synaptic plasticity that expresses itself as GWI morbidities. Our studies show that treatment with drugs targeted at blocking intracellular Ca2+ release could be effective therapies for GWI neurological morbidities.
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Affiliation(s)
| | | | | | - Laxmikant S Deshpande
- Departments of Neurology.,Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia 23298
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30
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Jacob S, Köhler M, Tröster P, Visa M, García-Prieto CF, Alanentalo T, Moede T, Leibiger B, Leibiger IB, Berggren PO. In vivo Ca 2+ dynamics in single pancreatic β cells. FASEB J 2019; 34:945-959. [PMID: 31914664 DOI: 10.1096/fj.201901302rr] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 10/25/2019] [Accepted: 11/05/2019] [Indexed: 11/11/2022]
Abstract
The dynamics of cytoplasmic free Ca2+ concentration ([Ca2+]i) in pancreatic β cells is central to our understanding of β-cell physiology and pathology. In this context, there are numerous in vitro studies available but existing in vivo data are scarce. We now critically evaluate the anterior chamber of the eye as an in vivo, non-invasive, imaging site for measuring [Ca2+]i dynamics longitudinally in three dimensions and at single-cell resolution. By applying a fluorescently labeled glucose analogue 2-(N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)Amino)-2-Deoxyglucose in vivo, we followed how glucose almost simultaneously distributes to all cells within the islet volume, resulting in [Ca2+]i changes. We found that almost all β cells in healthy mice responded to a glucose challenge, while in hyperinsulinemic, hyperglycemic mice about 80% of the β cells could not be further stimulated from fasting basal conditions. This finding indicates that our imaging modality can resolve functional heterogeneity within the β-cell population in terms of glucose responsiveness. Importantly, we demonstrate that glucose homeostasis is markedly affected using isoflurane compared to hypnorm/midazolam anesthetics, which has major implications for [Ca2+]i measurements. In summary, this setup offers a powerful tool to further investigate in vivo pancreatic β-cell [Ca2+]i response patterns at single-cell resolution in health and disease.
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Affiliation(s)
- Stefan Jacob
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Martin Köhler
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Philip Tröster
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Montse Visa
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Concha F García-Prieto
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Tomas Alanentalo
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Tilo Moede
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Barbara Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Ingo B Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
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31
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Gottschalk S, Degtyaruk O, Mc Larney B, Rebling J, Deán-Ben XL, Shoham S, Razansky D. Isolated Murine Brain Model for Large-Scale Optoacoustic Calcium Imaging. Front Neurosci 2019; 13:290. [PMID: 31068768 PMCID: PMC6491858 DOI: 10.3389/fnins.2019.00290] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 03/12/2019] [Indexed: 12/29/2022] Open
Abstract
Real-time visualization of large-scale neural dynamics in whole mammalian brains is hindered with existing neuroimaging methods having limited capacity when it comes to imaging large tissue volumes at high speeds. Optoacoustic imaging has been shown to be capable of real-time three-dimensional imaging of multiple cerebral hemodynamic parameters in rodents. However, optoacoustic imaging of calcium activity deep within the mammalian brain is hampered by strong blood absorption in the visible light spectrum as well as a lack of activity labels excitable in the near-infrared window. We have developed and validated an isolated whole mouse brain preparation labeled with genetically encoded calcium indicator GCaMP6f, which can closely resemble in vivo conditions. An optoacoustic imaging system coupled to a superfusion system was further designed and used for rapid volumetric monitoring of stimulus-evoked calcium dynamics in the brain. These new imaging setup and isolated preparation's protocols and characteristics are described here in detail. Our new technique captures calcium fluxes as true three-dimensional information across the entire brain with temporal resolution of 10 ms and spatial resolution of 150 μm, thus enabling large-scale neural recording at penetration depths and spatio-temporal resolution scales not covered with any existing neuroimaging techniques.
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Affiliation(s)
- Sven Gottschalk
- Institute for Biological and Medical Imaging, Helmholtz Center Munich, Neuherberg, Germany
| | - Oleksiy Degtyaruk
- Institute for Biological and Medical Imaging, Helmholtz Center Munich, Neuherberg, Germany
| | - Benedict Mc Larney
- Institute for Biological and Medical Imaging, Helmholtz Center Munich, Neuherberg, Germany
- Faculty of Medicine, Technical University of Munich, Munich, Germany
| | - Johannes Rebling
- Institute for Biological and Medical Imaging, Helmholtz Center Munich, Neuherberg, Germany
- Faculty of Medicine, Technical University of Munich, Munich, Germany
- Faculty of Medicine, Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Institute for Biomedical Engineering and Department of Information Technology and Electrical Engineering, ETH Zurich, Zurich, Switzerland
| | - Xosé Luis Deán-Ben
- Institute for Biological and Medical Imaging, Helmholtz Center Munich, Neuherberg, Germany
- Faculty of Medicine, Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Institute for Biomedical Engineering and Department of Information Technology and Electrical Engineering, ETH Zurich, Zurich, Switzerland
| | - Shy Shoham
- Tech4Health and Neuroscience Institutes and Department of Ophthalmology, New York University Langone Health, New York, NY, United States
| | - Daniel Razansky
- Institute for Biological and Medical Imaging, Helmholtz Center Munich, Neuherberg, Germany
- Faculty of Medicine, Technical University of Munich, Munich, Germany
- Faculty of Medicine, Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Institute for Biomedical Engineering and Department of Information Technology and Electrical Engineering, ETH Zurich, Zurich, Switzerland
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Pedersen MG, Tagliavini A, Henquin JC. Calcium signaling and secretory granule pool dynamics underlie biphasic insulin secretion and its amplification by glucose: experiments and modeling. Am J Physiol Endocrinol Metab 2019; 316:E475-E486. [PMID: 30620637 DOI: 10.1152/ajpendo.00380.2018] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Glucose-stimulated insulin secretion from pancreatic β-cells is controlled by a triggering pathway that culminates in calcium influx and regulated exocytosis of secretory granules, and by a less understood amplifying pathway that augments calcium-induced exocytosis. In response to an abrupt increase in glucose concentration, insulin secretion exhibits a first peak followed by a lower sustained second phase. This biphasic secretion pattern is disturbed in diabetes. It has been attributed to depletion and subsequent refilling of a readily releasable pool of granules or to the phasic cytosolic calcium dynamics induced by glucose. Here, we apply mathematical modeling to experimental data from mouse islets to investigate how calcium and granule pool dynamics interact to control dynamic insulin secretion. Experimental calcium traces are used as inputs in three increasingly complex models of pool dynamics, which are fitted to insulin secretory patterns obtained using a set of protocols of glucose and tolbutamide stimulation. New calcium and secretion data for so-called staircase protocols, in which the glucose concentration is progressively increased, are presented. These data can be reproduced without assuming any heterogeneity in the model, in contrast to previous modeling, because of nontrivial calcium dynamics. We find that amplification by glucose can be explained by increased mobilization and priming of granules. Overall, our results indicate that calcium dynamics contribute substantially to shaping insulin secretion kinetics, which implies that better insight into the events creating phasic calcium changes in human β-cells is needed to understand the cellular mechanisms that disturb biphasic insulin secretion in diabetes.
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Affiliation(s)
- Morten Gram Pedersen
- Department of Information Engineering, University of Padova , Padova , Italy
- Department of Mathematics "Tullio Levi-Civita, " University of Padova , Padova , Italy
- Padova Neuroscience Center, University of Padova , Padova , Italy
| | - Alessia Tagliavini
- Department of Information Engineering, University of Padova , Padova , Italy
| | - Jean-Claude Henquin
- Unit of Endocrinology and Metabolism, Faculty of Medicine, University of Louvain , Brussels , Belgium
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Chen B, Tjahja J, Malla S, Liebman C, Cho M. Astrocyte Viability and Functionality in Spatially Confined Microcavitation Zone. ACS Appl Mater Interfaces 2019; 11:4889-4899. [PMID: 30638362 DOI: 10.1021/acsami.8b21410] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Blast-induced traumatic brain injury (bTBI) can result in cell/tissue damage and lead to clinical and neuropsychiatric symptoms. Shock waves from a blast propagate through the brain and initiate cascades of mechanical and physiological events that can adversely affect the brain function. Although studies using animal models and brain slices have shown macroscale changes in the brain tissue in response to blast, systematic elucidation of coupling mechanisms is currently lacking. One mechanism that has been postulated and demonstrated repeatedly is the blast-induced generation and subsequent collapse of micron-size bubbles (i.e., microcavitation). Using a custom-designed exposure system, we have previously reported that upon collapsing of microbubbles, astrocytes exhibited changes in the cell viability, cellular biomechanics, production of reactive oxygen species, and activation of apoptotic signaling pathways. In this paper, we have applied microfabrication techniques and seeded astrocytes in a spatially controlled manner to determine the extent of cell damage from the site of the collapse of microbubbles. Such a novel experimental design is proven to facilitate our effort to examine the altered cell viability and functionality by monitoring the transient calcium spiking activity in real-time. We now report that the effect of microcavitation depends on the distance from which cells are seeded, and the cell functionality assessed by calcium dynamics is significantly diminished in the cells located within ∼800 μm of the collapsing microbubbles. Both calcium influx across the cell membrane via N-type calcium channels and intracellular calcium store are altered in response to microcavitation. Finally, the FDA-approved poloxamer 188 (P188) was used to reconstitute the compromised cell membrane and restore the cell's reparative capability. This finding may lead to a feasible treatment for partially mitigating the tissue damage associated with bTBI.
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Affiliation(s)
- Bo Chen
- Department of Bioengineering , University of Texas at Arlington , Arlington , Texas 76019 , United States
| | - Jessica Tjahja
- Department of Bioengineering , University of Texas at Arlington , Arlington , Texas 76019 , United States
| | - Sameep Malla
- Department of Bioengineering , University of Texas at Arlington , Arlington , Texas 76019 , United States
| | - Caleb Liebman
- Department of Bioengineering , University of Texas at Arlington , Arlington , Texas 76019 , United States
| | - Michael Cho
- Department of Bioengineering , University of Texas at Arlington , Arlington , Texas 76019 , United States
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Dowding S, Zakkaroff C, Moore S, David T. Coronary Smooth Muscle Cell Calcium Dynamics: Effects of Bifurcation Angle on Atheroprone Conditions. Front Physiol 2018; 9:1528. [PMID: 30429800 PMCID: PMC6220094 DOI: 10.3389/fphys.2018.01528] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 10/11/2018] [Indexed: 11/20/2022] Open
Abstract
This work investigates the effect of arterial bifurcation angulation on atherosclerosis development through in-silico simulations of coupled cell dynamics. The computational model presented here combines cellular pathways, fluid dynamics, and physiologically-realistic vessel geometries as observed in the human vasculature. The coupled cells model includes endothelial cells (ECs) and smooth muscle cells (SMCs) with ion dynamics, hetero and homotypic coupling, as well as electro-diffusive coupling. Three arterial bifurcation surface models were used in the coupled cells simulations. All three simulations showed propagating waves of Ca2+ in both the SMC and EC layers, following the introduction of a luminal agonist, in this case ATP. Immediately following the introduction of ATP concentration Ca2+ waves propagate from the area of high ATP toward the areas of low ATP concentration, forming complex patterns where waves interact with eachother, collide and fade. These dynamic phenomena are repeated with a series of waves of slower velocity. The underlying motivation of this research was to examine the macro-scale phenomena, given that the characteristic length scales of atherosclerotic plaques are much larger than a single cell. The micro-scale dynamics were modeled on macro-scale arterial bifurcation surfaces containing over one million cells. The results of the simulations presented here suggest that susceptibility to atherosclerosis development depends on the bifurcation angulation. In conjunction with findings reported in the literature, the simulation results demonstrate that arterial bifurcations containing wider angles have a more prominent influence on the coupled cells pathways associated with the development of atherosclerosis, by means of disturbed flow and lower SMC Ca2+ concentrations. The discussion of the results considers the findings of this research within the context of the potential link between information transport through frequency encoding of Ca2+ wave dynamics and development of atheroprone conditions.
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Affiliation(s)
- Stewart Dowding
- UC High Performance Computing Centre, University of Canterbury, Christchurch, New Zealand
| | - Constantine Zakkaroff
- Department of Accounting and Information Systems, University of Canterbury, Christchurch, New Zealand
| | | | - Tim David
- UC High Performance Computing Centre, University of Canterbury, Christchurch, New Zealand
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35
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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36
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Razlivanov I, Liew T, Moore EW, Al-Kathiri A, Bartram T, Kuvshinov D, Nikolaev A. Long-term imaging of calcium dynamics using genetically encoded calcium indicators and automatic tracking of cultured cells. Biotechniques 2018; 65:37-39. [PMID: 30014737 DOI: 10.2144/btn-2018-0024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Calcium dynamics is crucial for many signaling pathways and cell functions. Understanding how calcium regulates cell function often requires long-term imaging of calcium dynamics. Here we report a methodological approach of long-term (5-10 h) imaging of calcium dynamics in cultured cells. The approach links calcium imaging using genetically encoded calcium indicators and semi-automatic tracking of individual cells. It can be used in a large variety of situations, ranging from the role of calcium in biological processes to cell heterogeneity and screening of drugs modifying signaling pathways.
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Affiliation(s)
- Igor Razlivanov
- Department of Biomedical Sciences, The University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Teresa Liew
- Department of Biomedical Sciences, The University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Eira Watts Moore
- Department of Biomedical Sciences, The University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Alaa Al-Kathiri
- Department of Biomedical Sciences, The University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Tayma Bartram
- Department of Biomedical Sciences, The University of Sheffield, Western Bank, Sheffield, S10 2TN, UK.,Department of Oncology and Metabolism, The University of Sheffield, Medical School, Beech Hill Road, Sheffield, S10 2RX, UK
| | - Dmitriy Kuvshinov
- Department of Chemical Engineering, University of Hull, Cottingham Road, Hull, HU6 7RX, UK
| | - Anton Nikolaev
- Department of Biomedical Sciences, The University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
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37
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Sequerra EB, Goyal R, Castro PA, Levin JB, Borodinsky LN. NMDA Receptor Signaling Is Important for Neural Tube Formation and for Preventing Antiepileptic Drug-Induced Neural Tube Defects. J Neurosci 2018; 38:4762-73. [PMID: 29712790 DOI: 10.1523/JNEUROSCI.2634-17.2018] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 04/03/2018] [Accepted: 04/12/2018] [Indexed: 01/16/2023] Open
Abstract
Failure of neural tube closure leads to neural tube defects (NTDs), which can have serious neurological consequences or be lethal. Use of antiepileptic drugs (AEDs) during pregnancy increases the incidence of NTDs in offspring by unknown mechanisms. Here we show that during Xenopus laevis neural tube formation, neural plate cells exhibit spontaneous calcium dynamics that are partially mediated by glutamate signaling. We demonstrate that NMDA receptors are important for the formation of the neural tube and that the loss of their function induces an increase in neural plate cell proliferation and impairs neural cell migration, which result in NTDs. We present evidence that the AED valproic acid perturbs glutamate signaling, leading to NTDs that are rescued with varied efficacy by preventing DNA synthesis, activating NMDA receptors, or recruiting the NMDA receptor target ERK1/2. These findings may prompt mechanistic identification of AEDs that do not interfere with neural tube formation.SIGNIFICANCE STATEMENT Neural tube defects are one of the most common birth defects. Clinical investigations have determined that the use of antiepileptic drugs during pregnancy increases the incidence of these defects in the offspring by unknown mechanisms. This study discovers that glutamate signaling regulates neural plate cell proliferation and oriented migration and is necessary for neural tube formation. We demonstrate that the widely used antiepileptic drug valproic acid interferes with glutamate signaling and consequently induces neural tube defects, challenging the current hypotheses arguing that they are side effects of this antiepileptic drug that cause the increased incidence of these defects. Understanding the mechanisms of neurotransmitter signaling during neural tube formation may contribute to the identification and development of antiepileptic drugs that are safer during pregnancy.
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Abstract
Genetically encoded biosensors that directly interact with a molecule of interest were first introduced more than 20 years ago with fusion proteins that served as fluorescent indicators for calcium ions. Since then, the technology has matured into a diverse array of biosensors that have been deployed to improve our spatiotemporal understanding of molecules whose dynamics have profound influence on plant physiology and development. In this review, we address several types of biosensors with a focus on genetically encoded calcium indicators, which are now the most diverse and advanced group of biosensors. We then consider the discoveries in plant biology made by using biosensors for calcium, pH, reactive oxygen species, redox conditions, primary metabolites, phytohormones, and nutrients. These discoveries were dependent on the engineering, characterization, and optimization required to develop a successful biosensor; they were also dependent on the methodological developments required to express, detect, and analyze the readout of such biosensors.
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Affiliation(s)
- Ankit Walia
- Sainsbury Laboratory, Cambridge University, Cambridge CB2 1LR, United Kingdom;
| | - Rainer Waadt
- Centre for Organismal Studies, Ruprecht-Karls-Universität Heidelberg, Heidelberg 69120, Germany
| | - Alexander M Jones
- Sainsbury Laboratory, Cambridge University, Cambridge CB2 1LR, United Kingdom;
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Zhang XD, He CX, Cheng J, Wen J, Li PY, Wang N, Li G, Zeng XR, Cao JM, Yang Y. Sodium Tanshinone II-A Sulfonate (DS-201) Induces Vasorelaxation of Rat Mesenteric Arteries via Inhibition of L-Type Ca 2+ Channel. Front Pharmacol 2018; 9:62. [PMID: 29456510 PMCID: PMC5801295 DOI: 10.3389/fphar.2018.00062] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Accepted: 01/17/2018] [Indexed: 11/13/2022] Open
Abstract
Background: We previously have proved that sodium tanshinone II-A sulfonate (DS-201), a derivative of traditional Chinese medicinal herb Danshen (Salvia miltiorrhiza), is an opener and vasodilator of BKCa channel in the vascular smooth muscle cells (VSMCs). Vascular tension is closely associated with Ca2+ dynamics and activation of BKCa channel may not be the sole mechanism for the relaxation of the vascular tension by DS-201. Therefore, we hypothesized that the vasorelaxing effect of DS-20 may be also related to Ca2+ channel and cytoplasmic Ca2+ level in the VSMCs. Methods: Arterial tension was measured by Danish Myo Technology (DMT) myograph system in the mesentery vessels of rats, intracellular Ca2+ level by fluorescence imaging system in the VSMCs of rats, and L-type Ca2+ current by patch clamp technique in Ca2+ channels transfected human embryonic kidney 293 (HEK-293) cells. Results: DS-201 relaxed the endothelium-denuded artery rings pre-constricted with PE or high K+ and the vasorelaxation was reversible. Blockade of K+ channel did not totally block the effect of DS-201 on vasorelaxation. DS-201 suppressed [Ca2+]i transient induced by high K+ in a concentration-dependent manner in the VSMCs, including the amplitude of Ca2+ transient, the time for Ca2+ transient reaching to the [Ca2+]i peak and the time to remove Ca2+ from the cytoplasm. DS-201 inhibited L-type Ca2+ channel with an EC50 of 59.5 μM and at about 40% efficacy of inhibition. However, DS-201did not significantly affect the kinetics of Ca2+ channel. The effect of DS-201 on L-type Ca2+ channel was rate-independent. Conclusion: The effect of DS-201 on vasorelaxation was not only via activating BKCa channel, but also blocking Ca2+ channel and inhibiting Ca2+ influx in the VSMCs of rats. The results favor the use of DS-201 and Danshen in the treatment of cardiovascular diseases clinically.
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Affiliation(s)
- Xiao-Dong Zhang
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Chun-Xia He
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Jun Cheng
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Jing Wen
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Peng-Yun Li
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Na Wang
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Guang Li
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Xiao-Rong Zeng
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Ji-Min Cao
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Yan Yang
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease, Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
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Uzelac I, Ji YC, Hornung D, Schröder-Scheteling J, Luther S, Gray RA, Cherry EM, Fenton FH. Simultaneous Quantification of Spatially Discordant Alternans in Voltage and Intracellular Calcium in Langendorff-Perfused Rabbit Hearts and Inconsistencies with Models of Cardiac Action Potentials and Ca Transients. Front Physiol 2017; 8:819. [PMID: 29104543 PMCID: PMC5655020 DOI: 10.3389/fphys.2017.00819] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 10/05/2017] [Indexed: 02/03/2023] Open
Abstract
Rationale: Discordant alternans, a phenomenon in which the action potential duration (APDs) and/or intracellular calcium transient durations (CaDs) in different spatial regions of cardiac tissue are out of phase, present a dynamical instability for complex spatial dispersion that can be associated with long-QT syndrome (LQTS) and the initiation of reentrant arrhythmias. Because the use of numerical simulations to investigate arrhythmic effects, such as acquired LQTS by drugs is beginning to be studied by the FDA, it is crucial to validate mathematical models that may be used during this process. Objective: In this study, we characterized with high spatio-temporal resolution the development of discordant alternans patterns in transmembrane voltage (Vm) and intracellular calcium concentration ([Cai]+2) as a function of pacing period in rabbit hearts. Then we compared the dynamics to that of the latest state-of-the-art model for ventricular action potentials and calcium transients to better understand the underlying mechanisms of discordant alternans and compared the experimental data to the mathematical models representing Vm and [Cai]+2 dynamics. Methods and Results: We performed simultaneous dual optical mapping imaging of Vm and [Cai]+2 in Langendorff-perfused rabbit hearts with higher spatial resolutions compared with previous studies. The rabbit hearts developed discordant alternans through decreased pacing period protocols and we quantified the presence of multiple nodal points along the direction of wave propagation, both in APD and CaD, and compared these findings with results from theoretical models. In experiments, the nodal lines of CaD alternans have a steeper slope than those of APD alternans, but not as steep as predicted by numerical simulations in rabbit models. We further quantified several additional discrepancies between models and experiments. Conclusions: Alternans in CaD have nodal lines that are about an order of magnitude steeper compared to those of APD alternans. Current action potential models lack the necessary coupling between voltage and calcium compared to experiments and fail to reproduce some key dynamics such as, voltage amplitude alternans, smooth development of calcium alternans in time, conduction velocity and the steepness of the nodal lines of APD and CaD.
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Affiliation(s)
- Ilija Uzelac
- School of Physics, Georgia Institute of Technology, Atlanta, GA, United States
| | - Yanyan C. Ji
- School of Physics, Georgia Institute of Technology, Atlanta, GA, United States
| | - Daniel Hornung
- Max Planck Institute for Dynamics and Self-Organization, Gottingen, Germany
| | | | - Stefan Luther
- Max Planck Institute for Dynamics and Self-Organization, Gottingen, Germany
| | - Richard A. Gray
- Center for Device and Radiological Health, Food and Drug Administration, Silver Spring, MD, United States
| | - Elizabeth M. Cherry
- School of Mathematical Sciences, Rochester Institute of Technology, Rochester, NY, United States
| | - Flavio H. Fenton
- School of Physics, Georgia Institute of Technology, Atlanta, GA, United States
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Wang Y, Shi G, Miller DJ, Wang Y, Wang C, Broussard G, Wang Y, Tian L, Yu G. Automated Functional Analysis of Astrocytes from Chronic Time-Lapse Calcium Imaging Data. Front Neuroinform 2017; 11:48. [PMID: 28769780 PMCID: PMC5509822 DOI: 10.3389/fninf.2017.00048] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 06/30/2017] [Indexed: 01/12/2023] Open
Abstract
Recent discoveries that astrocytes exert proactive regulatory effects on neural information processing and that they are deeply involved in normal brain development and disease pathology have stimulated broad interest in understanding astrocyte functional roles in brain circuit. Measuring astrocyte functional status is now technically feasible, due to recent advances in modern microscopy and ultrasensitive cell-type specific genetically encoded Ca2+ indicators for chronic imaging. However, there is a big gap between the capability of generating large dataset via calcium imaging and the availability of sophisticated analytical tools for decoding the astrocyte function. Current practice is essentially manual, which not only limits analysis throughput but also risks introducing bias and missing important information latent in complex, dynamic big data. Here, we report a suite of computational tools, called Functional AStrocyte Phenotyping (FASP), for automatically quantifying the functional status of astrocytes. Considering the complex nature of Ca2+ signaling in astrocytes and low signal to noise ratio, FASP is designed with data-driven and probabilistic principles, to flexibly account for various patterns and to perform robustly with noisy data. In particular, FASP explicitly models signal propagation, which rules out the applicability of tools designed for other types of data. We demonstrate the effectiveness of FASP using extensive synthetic and real data sets. The findings by FASP were verified by manual inspection. FASP also detected signals that were missed by purely manual analysis but could be confirmed by more careful manual examination under the guidance of automatic analysis. All algorithms and the analysis pipeline are packaged into a plugin for Fiji (ImageJ), with the source code freely available online at https://github.com/VTcbil/FASP.
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Affiliation(s)
- Yinxue Wang
- Bradley Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State UniversityArlington, VA, United States
| | - Guilai Shi
- Department of Biochemistry and Molecular Medicine, University of California Davis School of MedicineDavis, CA, United States
| | - David J Miller
- Department of Electrical Engineering, School of Electrical Engineering and Computer Science, Pennsylvania State UniversityUniversity Park, PA, United States
| | - Yizhi Wang
- Bradley Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State UniversityArlington, VA, United States
| | - Congchao Wang
- Bradley Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State UniversityArlington, VA, United States
| | - Gerard Broussard
- Department of Biochemistry and Molecular Medicine, University of California Davis School of MedicineDavis, CA, United States
| | - Yue Wang
- Bradley Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State UniversityArlington, VA, United States
| | - Lin Tian
- Department of Biochemistry and Molecular Medicine, University of California Davis School of MedicineDavis, CA, United States
| | - Guoqiang Yu
- Bradley Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State UniversityArlington, VA, United States
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42
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Gattoni S, Røe ÅT, Aronsen JM, Sjaastad I, Louch WE, Smith NP, Niederer SA. Compensatory and decompensatory alterations in cardiomyocyte Ca 2+ dynamics in hearts with diastolic dysfunction following aortic banding. J Physiol 2017; 595:3867-3889. [PMID: 28542952 PMCID: PMC5471387 DOI: 10.1113/jp273879] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Accepted: 01/06/2017] [Indexed: 01/20/2023] Open
Abstract
Key points At the cellular level cardiac hypertrophy causes remodelling, leading to changes in ionic channel, pump and exchanger densities and kinetics. Previous studies have focused on quantifying changes in channels, pumps and exchangers without quantitatively linking these changes with emergent cellular scale functionality. Two biophysical cardiac cell models were created, parameterized and validated and are able to simulate electrophysiology and calcium dynamics in myocytes from control sham operated rats and aortic‐banded rats exhibiting diastolic dysfunction. The contribution of each ionic pathway to the calcium kinetics was calculated, identifying the L‐type Ca2+ channel and sarco/endoplasmic reticulum Ca2+ATPase as the principal regulators of systolic and diastolic Ca2+, respectively. Results show that the ability to dynamically change systolic Ca2+, through changes in expression of key Ca2+ modelling protein densities, is drastically reduced following the aortic banding procedure; however the cells are able to compensate Ca2+ homeostasis in an efficient way to minimize systolic dysfunction.
Abstract Elevated left ventricular afterload leads to myocardial hypertrophy, diastolic dysfunction, cellular remodelling and compromised calcium dynamics. At the cellular scale this remodelling of the ionic channels, pumps and exchangers gives rise to changes in the Ca2+ transient. However, the relative roles of the underlying subcellular processes and the positive or negative impact of each remodelling mechanism are not fully understood. Biophysical cardiac cell models were created to simulate electrophysiology and calcium dynamics in myocytes from control rats (SHAM) and aortic‐banded rats exhibiting diastolic dysfunction. The model parameters and framework were validated and the fitted parameters demonstrated to be unique for explaining our experimental data. The contribution of each ionic pathway to the calcium kinetics was calculated, identifying the L‐type Ca2+ channel (LCC) and the sarco/endoplasmic reticulum Ca2+‐ATPase (SERCA) as the principal regulators of systolic and diastolic Ca2+, respectively. In the aortic banding model, the sensitivity of systolic Ca2+ to LCC density and diastolic Ca2+ to SERCA density decreased by 16‐fold and increased by 23%, respectively, relative to the SHAM model. The energy cost of ionic homeostasis is maintained across the two models. The models predict that changes in ionic pathway densities in compensated aortic banding rats maintain Ca2+ function and efficiency. The ability to dynamically alter systolic function is significantly diminished, while the capacity to maintain diastolic Ca2+ is moderately increased. At the cellular level cardiac hypertrophy causes remodelling, leading to changes in ionic channel, pump and exchanger densities and kinetics. Previous studies have focused on quantifying changes in channels, pumps and exchangers without quantitatively linking these changes with emergent cellular scale functionality. Two biophysical cardiac cell models were created, parameterized and validated and are able to simulate electrophysiology and calcium dynamics in myocytes from control sham operated rats and aortic‐banded rats exhibiting diastolic dysfunction. The contribution of each ionic pathway to the calcium kinetics was calculated, identifying the L‐type Ca2+ channel and sarco/endoplasmic reticulum Ca2+ATPase as the principal regulators of systolic and diastolic Ca2+, respectively. Results show that the ability to dynamically change systolic Ca2+, through changes in expression of key Ca2+ modelling protein densities, is drastically reduced following the aortic banding procedure; however the cells are able to compensate Ca2+ homeostasis in an efficient way to minimize systolic dysfunction.
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Affiliation(s)
- Sara Gattoni
- King's College London, Department of Biomedical Engineering and Imaging Sciences, St Thomas' Hospital, 4th floor North Wing, The Rayne Institute, London, SE1 7EH, UK
| | - Åsmund Treu Røe
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,K. G. Jebsen Cardiac Research Centre and Centre for Heart Failure Research, University of Oslo, Oslo, Norway
| | | | - Ivar Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,K. G. Jebsen Cardiac Research Centre and Centre for Heart Failure Research, University of Oslo, Oslo, Norway
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,K. G. Jebsen Cardiac Research Centre and Centre for Heart Failure Research, University of Oslo, Oslo, Norway
| | - Nicolas P Smith
- King's College London, Department of Biomedical Engineering and Imaging Sciences, St Thomas' Hospital, 4th floor North Wing, The Rayne Institute, London, SE1 7EH, UK.,University of Auckland, Engineering School Block 1, Level 5, 20 Symonds St., Auckland, 101, New Zealand
| | - Steven A Niederer
- King's College London, Department of Biomedical Engineering and Imaging Sciences, St Thomas' Hospital, 4th floor North Wing, The Rayne Institute, London, SE1 7EH, UK
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43
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Affiliation(s)
- Ole H Petersen
- School of Biosciences, Sir Martin Evans Building, Cardiff University, Cardiff, UK.,Systems Immunity Research Institute, Cardiff University, Cardiff, UK
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44
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Abstract
Subcellular calcium signalling silencing is a novel and distinct cellular and molecular adaptive response to rapid cardiac activation. Calcium signalling silencing develops during short-term sustained rapid atrial activation as seen clinically during paroxysmal atrial fibrillation (AF). It is the first 'anti-arrhythmic' adaptive response in the setting of AF and appears to counteract the maladaptive changes that lead to intracellular Ca2+ signalling instability and Ca2+ -based arrhythmogenicity. Calcium signalling silencing results in a failed propagation of the [Ca2+ ]i signal to the myocyte centre both in patients with AF and in a rabbit model. This adaptive mechanism leads to a substantial reduction in the expression levels of calcium release channels (ryanodine receptors, RyR2) in the sarcoplasmic reticulum, and the frequency of Ca2+ sparks and arrhythmogenic Ca2+ waves remains low. Less Ca2+ release per [Ca2+ ]i transient, increased fast Ca2+ buffering strength, shortened action potentials and reduced L-type Ca2+ current contribute to a substantial reduction of intracellular [Na+ ]. These features of Ca2+ signalling silencing are distinct and in contrast to the changes attributed to Ca2+ -based arrhythmogenicity. Some features of Ca2+ signalling silencing prevail in human AF suggesting that the Ca2+ signalling 'phenotype' in AF is a sum of Ca2+ stabilizing (Ca2+ signalling silencing) and Ca2+ destabilizing (arrhythmogenic unstable Ca2+ signalling) factors. Calcium signalling silencing is a part of the mechanisms that contribute to the natural progression of AF and may limit the role of Ca2+ -based arrhythmogenicity after the onset of AF.
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Affiliation(s)
- Maura Greiser
- Center for Biomedical Engineering and Technology and Department of Physiology, University of Maryland School of Medicine, Baltimore, MD, USA
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Sikkel MB, Kumar S, Maioli V, Rowlands C, Gordon F, Harding SE, Lyon AR, MacLeod KT, Dunsby C. Erratum: High speed sCMOS-based oblique plane microscopy applied to the study of calcium dynamics in cardiac myocytes: [J. Biophotonics 9, No. 3, 311-323 (2016)]. J Biophotonics 2017; 10:744-745. [PMID: 28498628 PMCID: PMC6885920 DOI: 10.1002/jbio.201700062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In the article by M.B. Sikkel et al. (doi: 10.1002/jbio.201500193), published in J. Biophotonics 9, 311-323 (2016), an error occurred in the computer code that was used to generate Figure 3. This erratum is published to correct Figure 3, the calculated value of tgeom and the experimentally determined value of toptics in the text of the article.
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46
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Maleckar MM, Edwards AG, Louch WE, Lines GT. Studying dyadic structure-function relationships: a review of current modeling approaches and new insights into Ca 2+ (mis)handling. Clin Med Insights Cardiol 2017; 11:1179546817698602. [PMID: 28469494 PMCID: PMC5392018 DOI: 10.1177/1179546817698602] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 12/19/2016] [Indexed: 11/25/2022]
Abstract
Excitation–contraction coupling in cardiac myocytes requires calcium influx through L-type calcium channels in the sarcolemma, which gates calcium release through sarcoplasmic reticulum ryanodine receptors in a process known as calcium-induced calcium release, producing a myoplasmic calcium transient and enabling cardiomyocyte contraction. The spatio-temporal dynamics of calcium release, buffering, and reuptake into the sarcoplasmic reticulum play a central role in excitation–contraction coupling in both normal and diseased cardiac myocytes. However, further quantitative understanding of these cells’ calcium machinery and the study of mechanisms that underlie both normal cardiac function and calcium-dependent etiologies in heart disease requires accurate knowledge of cardiac ultrastructure, protein distribution and subcellular function. As current imaging techniques are limited in spatial resolution, limiting insight into changes in calcium handling, computational models of excitation–contraction coupling have been increasingly employed to probe these structure–function relationships. This review will focus on the development of structural models of cardiac calcium dynamics at the subcellular level, orienting the reader broadly towards the development of models of subcellular calcium handling in cardiomyocytes. Specific focus will be given to progress in recent years in terms of multi-scale modeling employing resolved spatial models of subcellular calcium machinery. A review of the state-of-the-art will be followed by a review of emergent insights into calcium-dependent etiologies in heart disease and, finally, we will offer a perspective on future directions for related computational modeling and simulation efforts.
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Affiliation(s)
- Mary M Maleckar
- Simula Research Laboratory, Center for Cardiological Innovation and Center for Biomedical Computing, Lysaker, Norway
| | - Andrew G Edwards
- Simula Research Laboratory, Center for Cardiological Innovation and Center for Biomedical Computing, Lysaker, Norway.,University of Oslo, Oslo, Norway
| | - William E Louch
- Institute for Experimental Medical Research (IEMR), Oslo University Hospital and the University of Oslo, Oslo, Norway
| | - Glenn T Lines
- Simula Research Laboratory, Center for Cardiological Innovation and Center for Biomedical Computing, Lysaker, Norway
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47
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Parikh J, Kapela A, Tsoukias NM. Can endothelial hemoglobin-α regulate nitric oxide vasodilatory signaling? Am J Physiol Heart Circ Physiol 2017; 312:H854-H866. [PMID: 28130333 DOI: 10.1152/ajpheart.00315.2016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 01/24/2017] [Accepted: 01/24/2017] [Indexed: 11/22/2022]
Abstract
We used mathematical modeling to investigate nitric oxide (NO)-dependent vasodilatory signaling in the arteriolar wall. Detailed continuum cellular models of calcium (Ca2+) dynamics and membrane electrophysiology in smooth muscle and endothelial cells (EC) were coupled with models of NO signaling and biotransport in an arteriole. We used this theoretical approach to examine the role of endothelial hemoglobin-α (Hbα) as a modulator of NO-mediated myoendothelial feedback, as previously suggested in Straub et al. (Nature 491: 473-477, 2012). The model considers enriched expression of inositol 1,4,5-triphosphate receptors (IP3Rs), endothelial nitric oxide synthase (eNOS) enzyme, Ca2+-activated potassium (KCa) channels and Hbα in myoendothelial projections (MPs) between the two cell layers. The model suggests that NO-mediated myoendothelial feedback is plausible if a significant percentage of eNOS is localized within or near the myoendothelial projection. Model results show that the ability of Hbα to regulate the myoendothelial feedback is conditional to its colocalization with eNOS near MPs at concentrations in the high nanomolar range (>0.2 μM or 24,000 molecules). Simulations also show that the effect of Hbα observed in in vitro experimental studies may overestimate its contribution in vivo, in the presence of blood perfusion. Thus, additional experimentation is required to quantify the presence and spatial distribution of Hbα in the EC, as well as to test that the strong effect of Hbα on NO signaling seen in vitro, translates also into a physiologically relevant response in vivo.NEW & NOTEWORTHY Mathematical modeling shows that although regulation of nitric oxide signaling by hemoglobin-α (Hbα) is plausible, it is conditional to its presence in significant concentrations colocalized with endothelial nitric oxide synthase in myoendothelial projections. Additional experimentation is required to test that the strong effect of Hbα seen in vitro translates into a physiologically relevant response in vivo.
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Affiliation(s)
- Jaimit Parikh
- Department of Biomedical Engineering, Florida International University, Miami, Florida; and
| | - Adam Kapela
- Department of Biomedical Engineering, Florida International University, Miami, Florida; and
| | - Nikolaos M Tsoukias
- Department of Biomedical Engineering, Florida International University, Miami, Florida; and .,School of Chemical Engineering, National Technical University of Athens, Athens, Greece
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48
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Huang F, Luo J, Ning T, Cao W, Jin X, Zhao H, Wang Y, Han S. Cytosolic and Nucleosolic Calcium Signaling in Response to Osmotic and Salt Stresses Are Independent of Each Other in Roots of Arabidopsis Seedlings. Front Plant Sci 2017; 8:1648. [PMID: 28983313 PMCID: PMC5613247 DOI: 10.3389/fpls.2017.01648] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 09/07/2017] [Indexed: 05/02/2023]
Abstract
Calcium acts as a universal second messenger in both developmental processes and responses to environmental stresses. Previous research has shown that a number of stimuli can induce [Ca2+] increases in both the cytoplasm and nucleus in plants. However, the relationship between cytosolic and nucleosolic calcium signaling remains obscure. Here, we generated transgenic plants containing a fusion protein, comprising rat parvalbumin (PV) with either a nuclear export sequence (PV-NES) or a nuclear localization sequence (NLS-PV), to selectively buffer the cytosolic or nucleosolic calcium. Firstly, we found that the osmotic stress-induced cytosolic [Ca2+] increase (OICIcyt) and the salt stress-induced cytosolic [Ca2+] increase (SICIcyt) were impaired in the PV-NES lines compared with the Arabidopsis wildtype (WT). Similarly, the osmotic stress-induced nucleosolic [Ca2+] increase (OICInuc) and salt stress-induced nucleosolic [Ca2+] increase (SICInuc) were also disrupted in the NLS-PV lines. These results indicate that PV can effectively buffer the increase of [Ca2+] in response to various stimuli in Arabidopsis. However, the OICIcyt and SICIcyt in the NLS-PV plants were similar to those in the WT, and the OICInuc and SICInuc in the PV-NES plants were also same as those in the WT, suggesting that the cytosolic and nucleosolic calcium dynamics are mutually independent. Furthermore, we found that osmotic stress- and salt stress-inhibited root growth was reduced dramatically in the PV-NES and NLS-PV lines, while the osmotic stress-induced increase of the lateral root primordia was higher in the PV-NES plants than either the WT or NLS-PV plants. In addition, several stress-responsive genes, namely CML37, DREB2A, MYB2, RD29A, and RD29B, displayed diverse expression patterns in response to osmotic and salt stress in the PV-NES and NLS-PV lines when compared with the WT. Together, these results imply that the cytosolic and nucleosolic calcium signaling coexist to play the pivotal roles in the growth and development of plants and their responses to environment stresses.
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49
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Chen ZZ, Gao ZM, Zeng DP, Liu B, Luan Y, Qin KR. A Y-Shaped Microfluidic Device to Study the Combined Effect of Wall Shear Stress and ATP Signals on Intracellular Calcium Dynamics in Vascular Endothelial Cells. Micromachines (Basel) 2016; 7:mi7110213. [PMID: 30404384 PMCID: PMC6190056 DOI: 10.3390/mi7110213] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 11/17/2016] [Accepted: 11/18/2016] [Indexed: 12/02/2022]
Abstract
The intracellular calcium dynamics in vascular endothelial cells (VECs) in response to wall shear stress (WSS) and/or adenosine triphosphate (ATP) have been commonly regarded as an important factor in regulating VEC function and behavior including proliferation, migration and apoptosis. However, the effects of time-varying ATP signals have been usually neglected in the past investigations in the field of VEC mechanobiology. In order to investigate the combined effects of WSS and dynamic ATP signals on the intracellular calcium dynamic in VECs, a Y-shaped microfluidic device, which can provide the cultured cells on the bottom of its mixing micro-channel with stimuli of WSS signal alone and different combinations of WSS and ATP signals in one single micro-channel, is proposed. Both numerical simulation and experimental studies verify the feasibility of its application. Cellular experimental results also suggest that a combination of WSS and ATP signals rather than a WSS signal alone might play a more significant role in VEC Ca2+ signal transduction induced by blood flow.
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Affiliation(s)
- Zong-Zheng Chen
- Department of Biomedical Engineering, Dalian University of Technology, Dalian 116024, China.
| | - Zheng-Ming Gao
- Department of Biomedical Engineering, Dalian University of Technology, Dalian 116024, China.
| | - De-Pei Zeng
- Department of Biomedical Engineering, Dalian University of Technology, Dalian 116024, China.
| | - Bo Liu
- Department of Biomedical Engineering, Dalian University of Technology, Dalian 116024, China.
| | - Yong Luan
- Department of Anesthesiology, The First Affiliated Hospital of Dalian Medical University, Dalian 116011, China.
| | - Kai-Rong Qin
- Department of Biomedical Engineering, Dalian University of Technology, Dalian 116024, China.
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50
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Boie S, Chen J, Sanderson MJ, Sneyd J. The relative contributions of store-operated and voltage-gated Ca 2+ channels to the control of Ca 2+ oscillations in airway smooth muscle. J Physiol 2016; 595:3129-3141. [PMID: 27502470 DOI: 10.1113/jp272996] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 08/03/2016] [Indexed: 02/02/2023] Open
Abstract
KEY POINTS Agonist-dependent oscillations in the concentration of free cytosolic calcium are a vital mechanism for the control of airway smooth muscle contraction and thus are a critical factor in airway hyper-responsiveness. Using a mathematical model, closely tied to experimental work, we show that the oscillations in membrane potential accompanying the calcium oscillations have no significant effect on the properties of the calcium oscillations. In addition, the model shows that calcium entry through store-operated calcium channels is critical for calcium oscillations, but calcium entry through voltage-gated channels has much less effect. The model predicts that voltage-gated channels are less important than store-operated channels in the control of airway smooth muscle tone. ABSTRACT Airway smooth muscle contraction is typically the key mechanism underlying airway hyper-responsiveness, and the strength of muscle contraction is determined by the frequency of oscillations of intracellular calcium (Ca2+ ) concentration. In airway smooth muscle cells, these Ca2+ oscillations are caused by cyclic Ca2+ release from the sarcoplasmic reticulum, although Ca2+ influx via plasma membrane channels is also necessary to sustain the oscillations over longer times. To assess the relative contributions of store-operated and voltage-gated Ca2+ channels to this Ca2+ influx, we generated a comprehensive mathematical model, based on experimental Ca2+ measurements in mouse precision-cut lung slices, to simulate Ca2+ oscillations and changes in membrane potential. Agonist-induced Ca2+ oscillations are accompanied by oscillations in membrane potential, although the membrane potential oscillations are too small to generate large Ca2+ currents through voltage-gated Ca2+ channels, and thus have little effect on the Ca2+ oscillations. Ca2+ entry through voltage-gated channels only becomes important when the cell is depolarized (e.g. by a high external K+ concentration). As a result, agonist-induced Ca2+ oscillations are critically dependent on Ca2+ entry through store-operated channels but do not depend strongly on Ca2+ entry though voltage-gated channels.
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Affiliation(s)
- Sebastian Boie
- Department of Mathematics, The University of Auckland, Auckland, New Zealand
| | - Jun Chen
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, USA
| | - Michael J Sanderson
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, USA
| | - James Sneyd
- Department of Mathematics, The University of Auckland, Auckland, New Zealand
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