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Hurley ME, Shah SS, Sheard TMD, Kirton HM, Steele DS, Gamper N, Jayasinghe I. Super-Resolution Analysis of the Origins of the Elementary Events of ER Calcium Release in Dorsal Root Ganglion Neurons. Cells 2023; 13:38. [PMID: 38201242 PMCID: PMC10778190 DOI: 10.3390/cells13010038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 12/18/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024] Open
Abstract
Coordinated events of calcium (Ca2+) released from the endoplasmic reticulum (ER) are key second messengers in excitable cells. In pain-sensing dorsal root ganglion (DRG) neurons, these events can be observed as Ca2+ sparks, produced by a combination of ryanodine receptors (RyR) and inositol 1,4,5-triphosphate receptors (IP3R1). These microscopic signals offer the neuronal cells with a possible means of modulating the subplasmalemmal Ca2+ handling, initiating vesicular exocytosis. With super-resolution dSTORM and expansion microscopies, we visualised the nanoscale distributions of both RyR and IP3R1 that featured loosely organised clusters in the subplasmalemmal regions of cultured rat DRG somata. We adapted a novel correlative microscopy protocol to examine the nanoscale patterns of RyR and IP3R1 in the locality of each Ca2+ spark. We found that most subplasmalemmal sparks correlated with relatively small groups of RyR whilst larger sparks were often associated with larger groups of IP3R1. These data also showed spontaneous Ca2+ sparks in <30% of the subplasmalemmal cell area but consisted of both these channel species at a 3.8-5 times higher density than in nonactive regions of the cell. Taken together, these observations reveal distinct patterns and length scales of RyR and IP3R1 co-clustering at contact sites between the ER and the surface plasmalemma that encode the positions and the quantity of Ca2+ released at each Ca2+ spark.
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Affiliation(s)
- Miriam E. Hurley
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Shihab S. Shah
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Thomas M. D. Sheard
- School of Biosciences, Faculty of Science, The University of Sheffield, Sheffield S10 2TN, UK
| | - Hannah M. Kirton
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Derek S. Steele
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Nikita Gamper
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Izzy Jayasinghe
- School of Biosciences, Faculty of Science, The University of Sheffield, Sheffield S10 2TN, UK
- EMBL Australia Node in Single Molecule Science, School of Biomedical Science, University of New South Wales, Kensington, Sydney 2052, Australia
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2
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Raudszus R, Paulig A, Urban N, Deckers A, Gräßle S, Vanderheiden S, Jung N, Bräse S, Schaefer M, Hill K. Pharmacological inhibition of TRPV2 attenuates phagocytosis and lipopolysaccharide-induced migration of primary macrophages. Br J Pharmacol 2023; 180:2736-2749. [PMID: 37254803 DOI: 10.1111/bph.16154] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 02/03/2023] [Accepted: 05/15/2023] [Indexed: 06/01/2023] Open
Abstract
BACKGROUND AND PURPOSE In macrophages, transient receptor potential vanilloid 2 (TRPV2) channel contributes to various cellular processes such as cytokine production, differentiation, phagocytosis and migration. Due to a lack of selective pharmacological tools, its function in immunological processes is not well understood and the identification of novel and selective TRPV2 modulators is highly desirable. EXPERIMENTAL APPROACH Novel and selective TRPV2 modulators were identified by screening a compound library using Ca2+ influx assays with human embryonic kidney 293 (HEK293) cells heterologously expressing rat TRPV2. Hits were further characterized and validated with Ca2+ influx and electrophysiological assays. Phagocytosis and migration of macrophages were analysed and the contribution of TRPV2 to the generation of Ca2+ microdomains was studied by total internal reflection fluorescence microscopy (TIRFM). KEY RESULTS The compound IV2-1, a dithiolane derivative (1,3-dithiolan-2-ylidene)-4-methyl-5-phenylpentan-2-one), is a potent inhibitor of heterologously expressed TRPV2 channels (IC50 = 6.3 ± 0.7 μM) but does not modify TRPV1, TRPV3 or TRPV4 channels. IV2-1 also inhibits TRPV2-mediated Ca2+ influx in macrophages. IV2-1 inhibits macrophage phagocytosis along with valdecoxib and after siRNA-mediated knockdown. Moreover, TRPV2 inhibition inhibits lipopolysaccharide-induced migration of macrophages whereas TRPV2 activation promotes migration. After activation, TRPV2 shapes Ca2+ microdomains predominantly at the margin of macrophages, which are important cellular regions to promote phagocytosis and migration. CONCLUSIONS AND IMPLICATIONS IV2-1 is a novel TRPV2-selective blocker and underline the role of TRPV2 in macrophage-mediated phagocytosis and migration. Furthermore, we provide evidence that TRPV2 activation generates Ca2+ microdomains, which may be involved in phagocytosis and migration of macrophages.
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Affiliation(s)
- Rick Raudszus
- Rudolf-Boehm-Institute of Pharmacology and Toxicology, Leipzig University, Leipzig, Germany
| | - Andrea Paulig
- Rudolf-Boehm-Institute of Pharmacology and Toxicology, Leipzig University, Leipzig, Germany
| | - Nicole Urban
- Rudolf-Boehm-Institute of Pharmacology and Toxicology, Leipzig University, Leipzig, Germany
| | - Anke Deckers
- Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Simone Gräßle
- Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Sylvia Vanderheiden
- Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Nicole Jung
- Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Stefan Bräse
- Institute of Biological and Chemical Systems, Karlsruhe Institute of Technology, Karlsruhe, Germany
- Institute of Organic Chemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Michael Schaefer
- Rudolf-Boehm-Institute of Pharmacology and Toxicology, Leipzig University, Leipzig, Germany
| | - Kerstin Hill
- Rudolf-Boehm-Institute of Pharmacology and Toxicology, Leipzig University, Leipzig, Germany
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3
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Hurley ME, White E, Sheard TMD, Steele D, Jayasinghe I. Correlative super-resolution analysis of cardiac calcium sparks and their molecular origins in health and disease. Open Biol 2023; 13:230045. [PMID: 37220792 PMCID: PMC10205181 DOI: 10.1098/rsob.230045] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Accepted: 04/28/2023] [Indexed: 05/25/2023] Open
Abstract
Rapid release of calcium from internal stores via ryanodine receptors (RyRs) is one of the fastest types of cytoplasmic second messenger signalling in excitable cells. In the heart, rapid summation of the elementary events of calcium release, 'calcium sparks', determine the contraction of the myocardium. We adapted a correlative super-resolution microscopy protocol to correlate sub-plasmalemmal spontaneous calcium sparks in rat right ventricular myocytes with the local nanoscale RyR2 positions. This revealed a steep relationship between the integral of a calcium spark and the sum of the local RyR2s. Segmentation of recurring spark sites showed evidence of repeated and triggered saltatory activation of multiple local RyR2 clusters. In myocytes taken from failing right ventricles, RyR2 clusters themselves showed a dissipated morphology and fragmented (smaller) clusters. They also featured greater heterogeneity in both the spark properties and the relationship between the integral of the calcium spark and the local ensemble of RyR2s. While fragmented (smaller) RyR2 clusters were rarely observed directly underlying the larger sparks or the recurring spark sites, local interrogation of the channel-to-channel distances confirmed a clear link between the positions of each calcium spark and the tight, non-random clustering of the local RyR2 in both healthy and failing ventricles.
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Affiliation(s)
- Miriam E. Hurley
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Ed White
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Thomas M. D. Sheard
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
- School of Biosciences, Faculty of Science, The University of Sheffield, Sheffield S10 2TN, UK
| | - Derek Steele
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Izzy Jayasinghe
- School of Biosciences, Faculty of Science, The University of Sheffield, Sheffield S10 2TN, UK
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4
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Knighten JM, Aziz T, Pleshinger DJ, Annamdevula N, Rich TC, Taylor MS, Andrews JF, Macarilla CT, Francis CM. Algorithm for biological second messenger analysis with dynamic regions of interest. PLoS One 2023; 18:e0284394. [PMID: 37167308 PMCID: PMC10174521 DOI: 10.1371/journal.pone.0284394] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 03/29/2023] [Indexed: 05/13/2023] Open
Abstract
Physiological function is regulated through cellular communication that is facilitated by multiple signaling molecules such as second messengers. Analysis of signal dynamics obtained from cell and tissue imaging is difficult because of intricate spatially and temporally distinct signals. Signal analysis tools based on static region of interest analysis may under- or overestimate signals in relation to region of interest size and location. Therefore, we developed an algorithm for biological signal detection and analysis based on dynamic regions of interest, where time-dependent polygonal regions of interest are automatically assigned to the changing perimeter of detected and segmented signals. This approach allows signal profiles to be rigorously and precisely tracked over time, eliminating the signal distortion observed with static methods. Integration of our approach with state-of-the-art image processing and particle tracking pipelines enabled the isolation of dynamic cellular signaling events and characterization of biological signaling patterns with distinct combinations of parameters including amplitude, duration, and spatial spread. Our algorithm was validated using synthetically generated datasets and compared with other available methods. Application of the algorithm to volumetric time-lapse hyperspectral images of cyclic adenosine monophosphate measurements in rat microvascular endothelial cells revealed distinct signal heterogeneity with respect to cell depth, confirming the utility of our approach for analysis of 5-dimensional data. In human tibial arteries, our approach allowed the identification of distinct calcium signal patterns associated with atherosclerosis. Our algorithm for automated detection and analysis of second messenger signals enables the decoding of signaling patterns in diverse tissues and identification of pathologic cellular responses.
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Affiliation(s)
- Jennifer M Knighten
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, Mobile, Alabama, United States of America
| | - Takreem Aziz
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, Mobile, Alabama, United States of America
| | - Donald J Pleshinger
- Department of Pharmacology, University of South Alabama College of Medicine, Mobile, Alabama, United States of America
| | - Naga Annamdevula
- Department of Pharmacology, University of South Alabama College of Medicine, Mobile, Alabama, United States of America
| | - Thomas C Rich
- Department of Pharmacology, University of South Alabama College of Medicine, Mobile, Alabama, United States of America
- Center for Lung Biology, University of South Alabama College of Medicine, Mobile, Alabama, United States of America
| | - Mark S Taylor
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, Mobile, Alabama, United States of America
| | - Joel F Andrews
- Bioimaging Core Facility, University of South Alabama College of Medicine, Mobile, Alabama, United States of America
| | - Christian T Macarilla
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, Mobile, Alabama, United States of America
| | - C Michael Francis
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, Mobile, Alabama, United States of America
- Center for Lung Biology, University of South Alabama College of Medicine, Mobile, Alabama, United States of America
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5
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McCarthy A, Avegnon KLM, Holubeck PA, Brown D, Karan A, Sharma NS, John JV, Weihs S, Ley J, Xie J. Electrostatic flocking of salt-treated microfibers and nanofiber yarns for regenerative engineering. Mater Today Bio 2021; 12:100166. [PMID: 34901819 PMCID: PMC8640530 DOI: 10.1016/j.mtbio.2021.100166] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 11/11/2021] [Accepted: 11/23/2021] [Indexed: 11/25/2022] Open
Abstract
Electrostatic flocking is a textile technology that employs a Coulombic driving force to launch short fibers from a charging source towards an adhesive-covered substrate, resulting in a dense array of aligned fibers perpendicular to the substrate. However, electrostatic flocking of insulative polymeric fibers remains a challenge due to their insufficient charge accumulation. We report a facile method to flock electrostatically insulative poly(ε-caprolactone) (PCL) microfibers (MFs) and electrospun PCL nanofiber yarns (NFYs) by incorporating NaCl during pre-flock processing. Both MF and NFY were evaluated for flock functionality, mechanical properties, and biological responses. To demonstrate this platform's diverse applications, standalone flocked NFY and MF scaffolds were synthesized and evaluated as scaffold for cell growth. Employing the same methodology, scaffolds made from poly(glycolide-co-l-lactide) (PGLA) (90:10) MFs were evaluated for their wound healing capacity in a diabetic mouse model. Further, a flock-reinforced polydimethylsiloxane (PDMS) disc was fabricated to create an anisotropic artificial vertebral disc (AVD) replacement potentially used as a treatment for lumbar degenerative disc disease. Overall, a salt-based flocking method is described with MFs and NFYs, with wound healing and AVD repair applications presented. NaCl coatings enable sufficient charge accumulation on electrically insulative polymer fibers during electrostatic flocking. Flocked nanofiber yarns allow further functionalization of flocked scaffolds. Flocked fiber scaffolds sustain cell proliferation. Flocked PGLA (90:10) fiber scaffolds promote modest fiber-density dependent wound healing and angiogenesis. Flock fibers-reinforced elastomeric artificial vertebral discs are mechanically robust.
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Affiliation(s)
- Alec McCarthy
- Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 668198, USA
| | - Kossi Loic M Avegnon
- Department of Mechanical and Materials Engineering, College of Engineering, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
| | - Phil A Holubeck
- Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 668198, USA
| | - Demi Brown
- Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 668198, USA
| | - Anik Karan
- Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 668198, USA
| | - Navatha Shree Sharma
- Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 668198, USA
| | - Johnson V John
- Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 668198, USA
| | - Shelbie Weihs
- Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 668198, USA
| | - Jazmin Ley
- Department of Mechanical and Materials Engineering, College of Engineering, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
| | - Jingwei Xie
- Department of Surgery-Transplant and Mary & Dick Holland Regenerative Medicine Program, College of Medicine, University of Nebraska Medical Center, Omaha, NE, 668198, USA.,Department of Mechanical and Materials Engineering, College of Engineering, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
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6
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Yang S, Li R, Chen J, Li Z, Huang Z, Xie W. Calcium Spark Detection and Event-Based Classification of Single Cardiomyocyte Using Deep Learning. Front Physiol 2021; 12:770051. [PMID: 34819876 PMCID: PMC8607692 DOI: 10.3389/fphys.2021.770051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 10/15/2021] [Indexed: 11/13/2022] Open
Abstract
Ca2+ sparks are the elementary Ca2+ release events in cardiomyocytes, altered properties of which lead to impaired Ca2+ handling and finally contribute to cardiac pathology under various diseases. Despite increasing use of machine-learning algorithms in deciphering the content of biological and medical data, Ca2+ spark images and data are yet to be deeply learnt and analyzed. In the present study, we developed a deep residual convolutional neural network method to detect Ca2+ sparks. Compared to traditional detection methods with arbitrarily defined thresholds to distinguish signals from noises, our new method detected more Ca2+ sparks with lower amplitudes but similar spatiotemporal distributions, thereby indicating that our new algorithm detected many very weak events that are usually omitted when using traditional detection methods. Furthermore, we proposed an event-based logistic regression and binary classification model to classify single cardiomyocytes using Ca2+ spark characteristics, which to date have generally been used only for simple statistical analyses and comparison between normal and diseased groups. Using this new detection algorithm and classification model, we succeeded in distinguishing wild type (WT) vs RyR2-R2474S± cardiomyocytes with 100% accuracy, and vehicle vs isoprenaline-insulted WT cardiomyocytes with 95.6% accuracy. The model can be extended to judge whether a small number of cardiomyocytes (and so the whole heart) are under a specific cardiac disease. Thus, this study provides a novel and powerful approach for the research and application of calcium signaling in cardiac diseases.
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Affiliation(s)
- Shengqi Yang
- Beijing Engineering Research Center for IoT Software and Systems, Beijing University of Technology, Beijing, China
| | - Ran Li
- Beijing Engineering Research Center for IoT Software and Systems, Beijing University of Technology, Beijing, China
| | - Jiliang Chen
- Beijing Engineering Research Center for IoT Software and Systems, Beijing University of Technology, Beijing, China
| | - Zhen Li
- Beijing Engineering Research Center for IoT Software and Systems, Beijing University of Technology, Beijing, China
| | - Zhangqin Huang
- Beijing Engineering Research Center for IoT Software and Systems, Beijing University of Technology, Beijing, China
| | - Wenjun Xie
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, Institute of Health and Rehabilitation Science, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China
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7
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Hurley ME, Sheard TMD, Norman R, Kirton HM, Shah SS, Pervolaraki E, Yang Z, Gamper N, White E, Steele D, Jayasinghe I. A correlative super-resolution protocol to visualise structural underpinnings of fast second-messenger signalling in primary cell types. Methods 2021; 193:27-37. [PMID: 33059034 DOI: 10.1016/j.ymeth.2020.10.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 09/28/2020] [Accepted: 10/07/2020] [Indexed: 10/24/2022] Open
Abstract
Nanometre-scale cellular information obtained through super-resolution microscopies are often unaccompanied by functional information, particularly transient and diffusible signals through which life is orchestrated in the nano-micrometre spatial scale. We describe a correlative imaging protocol which allows the ubiquitous intracellular second messenger, calcium (Ca2+), to be directly visualised against nanoscale patterns of the ryanodine receptor (RyR) Ca2+ channels which give rise to these Ca2+ signals in wildtype primary cells. This was achieved by combining total internal reflection fluorescence (TIRF) imaging of the elementary Ca2+ signals, with the subsequent DNA-PAINT imaging of the RyRs. We report a straightforward image analysis protocol of feature extraction and image alignment between correlative datasets and demonstrate how such data can be used to visually identify the ensembles of Ca2+ channels that are locally activated during the genesis of cytoplasmic Ca2+ signals.
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Affiliation(s)
- Miriam E Hurley
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, LS2 9JT, UK
| | - Thomas M D Sheard
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, LS2 9JT, UK
| | - Ruth Norman
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, LS2 9JT, UK
| | - Hannah M Kirton
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, LS2 9JT, UK
| | - Shihab S Shah
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, LS2 9JT, UK
| | - Eleftheria Pervolaraki
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, LS2 9JT, UK
| | - Zhaokang Yang
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, LS2 9JT, UK
| | - Nikita Gamper
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, LS2 9JT, UK
| | - Ed White
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, LS2 9JT, UK
| | - Derek Steele
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, LS2 9JT, UK
| | - Izzy Jayasinghe
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, LS2 9JT, UK; Department of Molecular Biology and Biotechnology, Faculty of Science, The University of Sheffield, S10 2TN, UK.
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8
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Jiang F, Yin K, Wu K, Zhang M, Wang S, Cheng H, Zhou Z, Xiao B. The mechanosensitive Piezo1 channel mediates heart mechano-chemo transduction. Nat Commun 2021; 12:869. [PMID: 33558521 PMCID: PMC7870949 DOI: 10.1038/s41467-021-21178-4] [Citation(s) in RCA: 97] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 01/19/2021] [Indexed: 01/20/2023] Open
Abstract
The beating heart possesses the intrinsic ability to adapt cardiac output to changes in mechanical load. The century-old Frank-Starling law and Anrep effect have documented that stretching the heart during diastolic filling increases its contractile force. However, the molecular mechanotransduction mechanism and its impact on cardiac health and disease remain elusive. Here we show that the mechanically activated Piezo1 channel converts mechanical stretch of cardiomyocytes into Ca2+ and reactive oxygen species (ROS) signaling, which critically determines the mechanical activity of the heart. Either cardiac-specific knockout or overexpression of Piezo1 in mice results in defective Ca2+ and ROS signaling and the development of cardiomyopathy, demonstrating a homeostatic role of Piezo1. Piezo1 is pathologically upregulated in both mouse and human diseased hearts via an autonomic response of cardiomyocytes. Thus, Piezo1 serves as a key cardiac mechanotransducer for initiating mechano-chemo transduction and consequently maintaining normal heart function, and might represent a novel therapeutic target for treating human heart diseases.
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Affiliation(s)
- Fan Jiang
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, IDG/McGovern Institute for Brain Research, School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100084, China
| | - Kunlun Yin
- State Key Laboratory of Cardiovascular Disease, Beijing Key Laboratory for Molecular Diagnostics of Cardiovascular Diseases, Center of Laboratory Medicine, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China
| | - Kun Wu
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, IDG/McGovern Institute for Brain Research, School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100084, China
- Medical Research Center, Beijing Key Laboratory of Cardiopulmonary Cerebral Resuscitation, Department of Emergency, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Mingmin Zhang
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, IDG/McGovern Institute for Brain Research, School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100084, China
| | - Shiqiang Wang
- State Key Laboratory of Membrane Biology, College of Life Sciences and Institute of Molecular Medicine, Peking University, Beijing, China
| | - Heping Cheng
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Zhou Zhou
- State Key Laboratory of Cardiovascular Disease, Beijing Key Laboratory for Molecular Diagnostics of Cardiovascular Diseases, Center of Laboratory Medicine, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China
| | - Bailong Xiao
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, IDG/McGovern Institute for Brain Research, School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100084, China.
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9
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Leigh WA, Del Valle G, Kamran SA, Drumm BT, Tavakkoli A, Sanders KM, Baker SA. A high throughput machine-learning driven analysis of Ca 2+ spatio-temporal maps. Cell Calcium 2020; 91:102260. [PMID: 32795721 PMCID: PMC7530121 DOI: 10.1016/j.ceca.2020.102260] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 07/24/2020] [Accepted: 07/24/2020] [Indexed: 12/31/2022]
Abstract
High-resolution Ca2+ imaging to study cellular Ca2+ behaviors has led to the creation of large datasets with a profound need for standardized and accurate analysis. To analyze these datasets, spatio-temporal maps (STMaps) that allow for 2D visualization of Ca2+ signals as a function of time and space are often used. Methods of STMap analysis rely on a highly arduous process of user defined segmentation and event-based data retrieval. These methods are often time consuming, lack accuracy, and are extremely variable between users. We designed a novel automated machine-learning based plugin for the analysis of Ca2+ STMaps (STMapAuto). The plugin includes optimized tools for Ca2+ signal preprocessing, automated segmentation, and automated extraction of key Ca2+ event information such as duration, spatial spread, frequency, propagation angle, and intensity in a variety of cell types including the Interstitial cells of Cajal (ICC). The plugin is fully implemented in Fiji and able to accurately detect and expeditiously quantify Ca2+ transient parameters from ICC. The plugin's speed of analysis of large-datasets was 197-fold faster than the commonly used single pixel-line method of analysis. The automated machine-learning based plugin described dramatically reduces opportunities for user error and provides a consistent method to allow high-throughput analysis of STMap datasets.
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Affiliation(s)
- Wesley A Leigh
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Guillermo Del Valle
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Sharif Amit Kamran
- Department of Computer Science and Engineering, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Bernard T Drumm
- Department of Life & Health Science, Dundalk Institute of Technology, Co. Louth, Ireland
| | - Alireza Tavakkoli
- Department of Computer Science and Engineering, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Kenton M Sanders
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Salah A Baker
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV 89557, USA.
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10
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Tian Q, Lipp P. Apparent calcium spark properties and fast-scanning 2D confocal imaging modalities. Cell Calcium 2020; 93:102303. [PMID: 33316584 DOI: 10.1016/j.ceca.2020.102303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 09/11/2020] [Accepted: 09/25/2020] [Indexed: 10/23/2022]
Abstract
Ca2+ sparks are instrumental to understand physiological and pathological Ca2+ signaling in the heart. High-speed two spatially dimensional (2D) confocal imaging (>120 Hz) enables acquisition of sparks with high-content information, however, owing to a wide variety of different acquisition modalities the question arises: how much they reflect the "true" Ca2+ spark properties. To address this issue, we compared a fast point and a 2D-array scanner equipped with a range of different detectors. As a quasi-standard biological sample, we employed Ca2+ sparks in permeabilized and intact mouse ventricular myocytes and utilized an unbiased, automatic Ca2+ spark analysis tool, iSpark. Data from the point scanner suffered from low pixel photon fluxes (PPF) concomitant with high Poissonian noise. Images from the 2D-array scanner displayed substantially increased PPF, lower Poissonian noise and almost 3-fold increased sign-to-noise ratios. Noteworthy, data from the 2D scanner suffered from considerable inter-pinhole crosstalk evident for the permeabilized cells. Spark properties, such as frequency, amplitude, decay time and spatial spread were distinctly different for any scanner/detector combination. Our study reveals that the apparent Ca2+ spark properties differ dependent on the particular recording modality and set-up employed, quantitatively.
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Affiliation(s)
- Qinghai Tian
- Center for Molecular Signaling (PZMS), Institute for Molecular Cell Biology, Research Center for Molecular Imaging and Screening, Medical Faculty, Saarland University, Kirrberger Str. 100, Homburg, Saar, 66421, Germany
| | - Peter Lipp
- Center for Molecular Signaling (PZMS), Institute for Molecular Cell Biology, Research Center for Molecular Imaging and Screening, Medical Faculty, Saarland University, Kirrberger Str. 100, Homburg, Saar, 66421, Germany.
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11
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Shah SI, Ong HL, Demuro A, Ullah G. PunctaSpecks: A tool for automated detection, tracking, and analysis of multiple types of fluorescently labeled biomolecules. Cell Calcium 2020; 89:102224. [PMID: 32502904 PMCID: PMC7343294 DOI: 10.1016/j.ceca.2020.102224] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 05/12/2020] [Accepted: 05/21/2020] [Indexed: 01/21/2023]
Abstract
Recent advances in imaging technology and fluorescent probes have made it possible to gain information about the dynamics of subcellular processes at unprecedented spatiotemporal scales. Unfortunately, a lack of automated tools to efficiently process the resulting imaging data encoding fine details of the biological processes remains a major bottleneck in utilizing the full potential of these powerful experimental techniques. Here we present a computational tool, called PunctaSpecks, that can characterize fluorescence signals arising from a wide range of biological molecules under normal and pathological conditions. Among other things, the program can calculate the number, areas, life-times, and amplitudes of fluorescence signals arising from multiple sources, track diffusing fluorescence sources like moving mitochondria, and determine the overlap probability of two processes or organelles imaged using indicator dyes of different colors. We have tested PunctaSpecks on synthetic time-lapse movies containing mobile fluorescence objects of various sizes, mimicking the activity of biomolecules. The robustness of the software is tested by varying the level of noise along with random but known pattern of appearing, disappearing, and movement of these objects. Next, we use PunctaSpecks to characterize protein-protein interaction involved in store-operated Ca2+ entry through the formation and activation of plasma membrane-bound ORAI1 channel and endoplasmic reticulum membrane-bound stromal interaction molecule (STIM), the evolution of inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ signals from sub-micrometer size local events into global waves in human cortical neurons, and the activity of Alzheimer's disease-associated β amyloid pores in the plasma membrane. The tool can also be used to study other dynamical processes imaged through fluorescence molecules. The open source algorithm allows for extending the program to analyze more than two types of biomolecules visualized using markers of different colors.
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Affiliation(s)
| | - Hwei Ling Ong
- Secretory Physiology Section, NIDCR, NIH, Bethesda, MD, 20892,USA
| | - Angelo Demuro
- Department of Neurobiology and Behavior, University of California, Irvine, CA 92697, USA
| | - Ghanim Ullah
- Department of Physics, University of South Florida, Tampa, FL 33647, USA.
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12
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Liu T, Xiong F, Qi XY, Xiao J, Villeneuve L, Abu-Taha I, Dobrev D, Huang C, Nattel S. Altered calcium handling produces reentry-promoting action potential alternans in atrial fibrillation-remodeled hearts. JCI Insight 2020; 5:133754. [PMID: 32255765 DOI: 10.1172/jci.insight.133754] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 03/25/2020] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) alters atrial cardiomyocyte (ACM) Ca2+ handling, promoting ectopic beat formation. We examined the effects of AF-associated remodeling on Ca2+-related action potential dynamics and consequences for AF susceptibility. AF was maintained electrically in dogs by right atrial (RA) tachypacing. ACMs isolated from AF dogs showed increased Ca2+ release refractoriness, spontaneous Ca2+ spark frequency, and cycle length (CL) threshold for Ca2+ and action potential duration (APD) alternans versus controls. AF increased the in situ CL threshold for Ca2+/APD alternans and spatial dispersion in Ca2+ release recovery kinetics, leading to spatially discordant alternans associated with reentrant rotor formation and susceptibility to AF induction/maintenance. The clinically available agent dantrolene reduced Ca2+ leak and CL threshold for Ca2+/APD alternans in ACMs and AF dog right atrium, while suppressing AF susceptibility; caffeine increased Ca2+ leak and CL threshold for Ca2+/APD alternans in control dog ACMs and RA tissues. In vivo, the atrial repolarization alternans CL threshold was increased in AF versus control, as was AF vulnerability. Intravenous dantrolene restored repolarization alternans threshold and reduced AF vulnerability. Immunoblots showed reduced expression of total and phosphorylated ryanodine receptors and calsequestrin in AF and unchanged phospholamban/SERCA expression. Thus, along with promoting spontaneous ectopy, AF-induced Ca2+ handling abnormalities favor AF by enhancing vulnerability to repolarization alternans, promoting initiation and maintenance of reentrant activity; dantrolene provides a lead molecule to target this mechanism.
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Affiliation(s)
- Tao Liu
- Montreal Heart Institute, Department of Medicine, Université de Montréal, Montréal, Québec, Canada.,Department of Cardiology, Renmin Hospital of Wuhan University, China.,Cardiovascular Research Institute, Wuhan University, China.,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Feng Xiong
- Montreal Heart Institute, Department of Medicine, Université de Montréal, Montréal, Québec, Canada.,Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada
| | - Xiao-Yan Qi
- Montreal Heart Institute, Department of Medicine, Université de Montréal, Montréal, Québec, Canada
| | - Jiening Xiao
- Montreal Heart Institute, Department of Medicine, Université de Montréal, Montréal, Québec, Canada
| | - Louis Villeneuve
- Montreal Heart Institute, Department of Medicine, Université de Montréal, Montréal, Québec, Canada
| | - Issam Abu-Taha
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Germany
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Germany
| | - Congxin Huang
- Department of Cardiology, Renmin Hospital of Wuhan University, China.,Cardiovascular Research Institute, Wuhan University, China.,Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Stanley Nattel
- Montreal Heart Institute, Department of Medicine, Université de Montréal, Montréal, Québec, Canada.,Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada.,Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Germany.,IHU LIRYC Institute, Fondation Bordeaux Université, Bordeaux, France
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13
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Vierra NC, Kirmiz M, van der List D, Santana LF, Trimmer JS. Kv2.1 mediates spatial and functional coupling of L-type calcium channels and ryanodine receptors in mammalian neurons. eLife 2019; 8:49953. [PMID: 31663850 PMCID: PMC6839919 DOI: 10.7554/elife.49953] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 10/29/2019] [Indexed: 12/16/2022] Open
Abstract
The voltage-gated K+ channel Kv2.1 serves a major structural role in the soma and proximal dendrites of mammalian brain neurons, tethering the plasma membrane (PM) to endoplasmic reticulum (ER). Although Kv2.1 clustering at neuronal ER-PM junctions (EPJs) is tightly regulated and highly conserved, its function remains unclear. By identifying and evaluating proteins in close spatial proximity to Kv2.1-containing EPJs, we discovered that a significant role of Kv2.1 at EPJs is to promote the clustering and functional coupling of PM L-type Ca2+ channels (LTCCs) to ryanodine receptor (RyR) ER Ca2+ release channels. Kv2.1 clustering also unexpectedly enhanced LTCC opening at polarized membrane potentials. This enabled Kv2.1-LTCC-RyR triads to generate localized Ca2+ release events (i.e., Ca2+ sparks) independently of action potentials. Together, these findings uncover a novel mode of LTCC regulation and establish a unique mechanism whereby Kv2.1-associated EPJs provide a molecular platform for localized somatodendritic Ca2+ signals in mammalian brain neurons.
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Affiliation(s)
- Nicholas C Vierra
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, United States.,Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, United States
| | - Michael Kirmiz
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, United States
| | - Deborah van der List
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, United States.,Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, United States
| | - L Fernando Santana
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, United States
| | - James S Trimmer
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, United States.,Department of Neurobiology, Physiology, and Behavior, University of California, Davis, Davis, United States
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14
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Tian Q, Schröder L, Schwarz Y, Flockerzi A, Kaestner L, Zeug A, Bruns D, Lipp P. Large scale, unbiased analysis of elementary calcium signaling events in cardiac myocytes. J Mol Cell Cardiol 2019; 135:79-89. [DOI: 10.1016/j.yjmcc.2019.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 07/26/2019] [Accepted: 08/12/2019] [Indexed: 12/12/2022]
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15
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Laasmaa M, Karro N, Birkedal R, Vendelin M. IOCBIO Sparks detection and analysis software. PeerJ 2019; 7:e6652. [PMID: 30956900 PMCID: PMC6442673 DOI: 10.7717/peerj.6652] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 02/19/2019] [Indexed: 12/01/2022] Open
Abstract
Analysis of calcium sparks in cardiomyocytes can provide valuable information about functional changes of calcium handling in health and disease. As a part of the calcium sparks analysis, sparks detection and characterization is necessary. Here, we describe a new open-source platform for automatic calcium sparks detection from line scan confocal images. The developed software is tailored for detecting only calcium sparks, allowing us to design a graphical user interface specifically for this task. The software enables detecting sparks automatically as well as adding, removing, or adjusting regions of interest marking each spark. The results of the analysis are stored in an SQL database, allowing simple integration with statistical tools. We have analyzed the performance of the algorithm using a large set of synthetic images with varying spark sizes and noise levels and also compared the analysis results with results obtained by software established in the field. The use of our software is illustrated by an analysis of the effect of isoprenaline (ISO) on spark frequency, amplitude, and spatial and temporal characteristics. For that, cardiomyocytes from C57BL/6 mice were used. We demonstrated an increase in spark frequency, tendency of having larger spark amplitudes, sparks with a longer duration, and occurrence of multiple sparks from the same site in the presence of ISO. We also show that the duration and the width of sparks with the same amplitude were similar in the absence and presence of ISO. The software was released as an open source repository and is available for free use and collaborative development.
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Affiliation(s)
- Martin Laasmaa
- Laboratory of Systems Biology, Department of Cybernetics, School of Science, Tallinn University of Technology, Tallinn, Estonia
| | - Niina Karro
- Laboratory of Systems Biology, Department of Cybernetics, School of Science, Tallinn University of Technology, Tallinn, Estonia
| | - Rikke Birkedal
- Laboratory of Systems Biology, Department of Cybernetics, School of Science, Tallinn University of Technology, Tallinn, Estonia
| | - Marko Vendelin
- Laboratory of Systems Biology, Department of Cybernetics, School of Science, Tallinn University of Technology, Tallinn, Estonia
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16
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Illaste A, Wullschleger M, Fernandez-Tenorio M, Niggli E, Egger M. Automatic Detection and Classification of Ca 2+ Release Events in Line- and Frame-Scan Images. Biophys J 2018; 116:383-394. [PMID: 30638961 DOI: 10.1016/j.bpj.2018.12.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 11/27/2018] [Accepted: 12/12/2018] [Indexed: 10/27/2022] Open
Abstract
Analysis of Ca2+ signals obtained in various cell types (i.e., cardiomyocytes) is always a tradeoff between acquisition speed and signal/noise ratio of the fluorescence signal. This becomes especially apparent during fast two- or three-dimensional confocal imaging when local intracellular fluorescence signals originating from Ca2+ release from intracellular Ca2+ stores (e.g., sarcoplasmic reticulum) need to be examined. Mathematical methods have been developed to remedy a high noise level by fitting each pixel with a transient function to "denoise" the image. So far, current available analytical approaches have been impaired by a number of constraints (e.g., inability to fit local, concurrent, and consecutive events) and the limited ability to customize implementation. Here, we suggest a, to our knowledge, novel approach for detailed analysis of subcellular micro-Ca2+ events based on pixel-by-pixel denoising of confocal frame- and line-scan images. The algorithm enables spatiotemporally overlapping events (e.g., a Ca2+ spark occurring during the decaying phase of a Ca2+ wave) to be extracted so that various types of Ca2+ events can be detected at a pixel time level of precision. The method allows a nonconstant baseline to be estimated for each pixel, foregoing the need to subtract fluorescence background or apply self-ratio methods before image analysis. Furthermore, by using a clustering algorithm, identified single-pixel events are grouped into "physiologically relevant" Ca2+ signaling events spanning multiple pixels (sparks, waves, puffs, transients, etc.), from which spatiotemporal event parameters (e.g., full duration at half maximal amplitude, full width at half maximal amplitude, amplitude, wave speed, rise, and decay times) can be easily extracted. The method was implemented with cross-platform open source software, providing a comprehensive and easy-to-use graphical user interface enabling rapid line-scan images and rapid frame-scan image sequences (up to 150 frames/s) to be analyzed and repetitive Ca2+ events (Ca2+ sparks and Ca2+ puffs) originating from clusters of Ca2+ release channels located in the sarcoplasmic reticulum membrane (ryanodine receptors and inositol 1,4,5-trisphosphate receptors) of isolated cardiomyocytes to be examined with a high level of precision.
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Affiliation(s)
- Ardo Illaste
- Department of Physiology, University of Bern, Bern, Switzerland
| | | | | | - Ernst Niggli
- Department of Physiology, University of Bern, Bern, Switzerland.
| | - Marcel Egger
- Department of Physiology, University of Bern, Bern, Switzerland.
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17
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Shah SI, Smith M, Swaminathan D, Parker I, Ullah G, Demuro A. CellSpecks: A Software for Automated Detection and Analysis of Calcium Channels in Live Cells. Biophys J 2018; 115:2141-2151. [PMID: 30447989 DOI: 10.1016/j.bpj.2018.10.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 09/27/2018] [Accepted: 10/22/2018] [Indexed: 02/01/2023] Open
Abstract
To couple the fidelity of patch-clamp recording with a more high-throughput screening capability, we pioneered a, to our knowledge, novel approach to single-channel recording that we named "optical patch clamp." By using highly sensitive fluorescent Ca2+ indicator dyes in conjunction with total internal fluorescence microscopy techniques, we monitor Ca2+ flux through individual Ca2+-permeable channels. This approach provides information about channel gating analogous to patch-clamp recording at a time resolution of ∼2 ms with the additional advantage of being massively parallel, providing simultaneous and independent recording from thousands of channels in the native environment. However, manual analysis of the data generated by this technique presents severe challenges because a video recording can include many thousands of frames. To overcome this bottleneck, we developed an image processing and analysis framework called CellSpecks capable of detecting and fully analyzing the kinetics of ion channels within a video sequence. By using randomly generated synthetic data, we tested the ability of CellSpecks to rapidly and efficiently detect and analyze the activity of thousands of ion channels, including openings for a few milliseconds. Here, we report the use of CellSpecks for the analysis of experimental data acquired by imaging muscle nicotinic acetylcholine receptors and the Alzheimer's disease-associated amyloid β pores with multiconductance levels in the plasma membrane of Xenopus laevis oocytes. We show that CellSpecks can accurately and efficiently generate location maps and create raw and processed fluorescence time traces; histograms of mean open times, mean close times, open probabilities, durations, and maximal amplitudes; and a "channel chip" showing the activity of all channels as a function of time. Although we specifically illustrate the application of CellSpecks for analyzing data from Ca2+ channels, it can be easily customized to analyze other spatially and temporally localized signals.
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Affiliation(s)
| | | | - Divya Swaminathan
- Department of Neurobiology and Behavior,University of California Irvine, Irvine, California
| | - Ian Parker
- Department of Neurobiology and Behavior,University of California Irvine, Irvine, California; Department of Physiology and Biophysics, University of California Irvine, Irvine, California
| | - Ghanim Ullah
- Department of Physics, University of South Florida, Tampa, Florida.
| | - Angelo Demuro
- Department of Neurobiology and Behavior,University of California Irvine, Irvine, California.
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18
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SICT: automated detection and supervised inspection of fast Ca 2+ transients. Sci Rep 2018; 8:15523. [PMID: 30341397 PMCID: PMC6195629 DOI: 10.1038/s41598-018-33847-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 10/05/2018] [Indexed: 02/06/2023] Open
Abstract
Recent advances in live Ca2+ imaging with increasing spatial and temporal resolution offer unprecedented opportunities, but also generate an unmet need for data processing. Here we developed SICT, a MATLAB program that automatically identifies rapid Ca2+ rises in time-lapse movies with low signal-to-noise ratios, using fluorescent indicators. A graphical user interface allows visual inspection of automatically detected events, reducing manual labour to less than 10% while maintaining quality control. The detection performance was tested using synthetic data with various signal-to-noise ratios. The event inspection phase was evaluated by four human observers. Reliability of the method was demonstrated in a direct comparison between manual and SICT-aided analysis. As a test case in cultured neurons, SICT detected an increase in frequency and duration of spontaneous Ca2+ transients in the presence of caffeine. This new method speeds up the analysis of elementary Ca2+ transients.
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19
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Ednie AR, Deng W, Yip KP, Bennett ES. Reduced myocyte complex N-glycosylation causes dilated cardiomyopathy. FASEB J 2018; 33:1248-1261. [PMID: 30138037 DOI: 10.1096/fj.201801057r] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Protein glycosylation is an essential posttranslational modification that affects a myriad of physiologic processes. Humans with genetic defects in glycosylation, which result in truncated glycans, often present with significant cardiac deficits. Acquired heart diseases and their associated risk factors were also linked to aberrant glycosylation, highlighting its importance in human cardiac disease. In both cases, the link between causation and corollary remains enigmatic. The glycosyltransferase gene, mannosyl (α-1,3-)-glycoprotein β-1,2- N-acetylglucosaminyltransferase (Mgat1), whose product, N-acetylglucosaminyltransferase 1 (GlcNAcT1) is necessary for the formation of hybrid and complex N-glycan structures in the medial Golgi, was shown to be at reduced levels in human end-stage cardiomyopathy, thus making Mgat1 an attractive target for investigating the role of hybrid/complex N-glycosylation in cardiac pathogenesis. Here, we created a cardiomyocyte-specific Mgat1 knockout (KO) mouse to establish a model useful in exploring the relationship between hybrid/complex N-glycosylation and cardiac function and disease. Biochemical and glycomic analyses showed that Mgat1KO cardiomyocytes produce predominately truncated N-glycan structures. All Mgat1KO mice died significantly younger than control mice and demonstrated chamber dilation and systolic dysfunction resembling human dilated cardiomyopathy (DCM). Data also indicate that a cardiomyocyte L-type voltage-gated Ca2+ channel (Cav) subunit (α2δ1) is a GlcNAcT1 target, and Mgat1KO Cav activity is shifted to more-depolarized membrane potentials. Consistently, Mgat1KO cardiomyocyte Ca2+ handling is altered and contraction is dyssynchronous compared with controls. The data demonstrate that reduced hybrid/complex N-glycosylation contributes to aberrant cardiac function at whole-heart and myocyte levels drawing a direct link between altered glycosylation and heart disease. Thus, the Mgat1KO provides a model for investigating the relationship between systemic reductions in glycosylation and cardiac disease, showing that clinically relevant changes in cardiomyocyte hybrid/complex N-glycosylation are sufficient to cause DCM and early death.-Ednie, A. R., Deng, W., Yip, K.-P., Bennett, E. S. Reduced myocyte complex N-glycosylation causes dilated cardiomyopathy.
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Affiliation(s)
- Andrew R Ednie
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio, USA.,College of Science and Mathematics, Wright State University, Dayton, Ohio, USA; and
| | - Wei Deng
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Kay-Pong Yip
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Eric S Bennett
- Department of Neuroscience, Cell Biology, and Physiology, Boonshoft School of Medicine, Wright State University, Dayton, Ohio, USA.,College of Science and Mathematics, Wright State University, Dayton, Ohio, USA; and
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20
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Galice S, Xie Y, Yang Y, Sato D, Bers DM. Size Matters: Ryanodine Receptor Cluster Size Affects Arrhythmogenic Sarcoplasmic Reticulum Calcium Release. J Am Heart Assoc 2018; 7:e008724. [PMID: 29929992 PMCID: PMC6064922 DOI: 10.1161/jaha.118.008724] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 05/16/2018] [Indexed: 11/19/2022]
Abstract
BACKGROUND Ryanodine receptors (RyR) mediate sarcoplasmic reticulum calcium (Ca2+) release and influence myocyte Ca2+ homeostasis and arrhythmias. In cardiac myocytes, RyRs are found in clusters of various sizes and shapes, and RyR cluster size may critically influence normal and arrhythmogenic Ca2+ spark and wave formation. However, the actual RyR cluster sizes at specific Ca2+ spark sites have never been measured in the physiological setting. METHODS AND RESULTS Here we measured RyR cluster size and Ca2+ sparks simultaneously to assess how RyR cluster size influences Ca2+ sparks and sarcoplasmic reticulum Ca2+ leak. For small RyR cluster sizes (<50), Ca2+ spark frequency is very low but then increases dramatically at larger cluster sizes. In contrast, Ca2+ spark amplitude is nearly maximal even at relatively small RyR cluster size (≈10) and changes little at larger cluster size. These properties agreed with computational simulations of RyR gating within clusters. CONCLUSIONS Our study explains how this combination of properties may limit arrhythmogenic Ca2+ sparks and wave propagation (at many junctions) while preserving the efficacy and spatial synchronization of Ca2+-induced Ca2+-release during normal excitation-contraction coupling. However, variations in RyR cluster size among individual junctions and RyR sensitivity could exacerbate heterogeneity of local sarcoplasmic reticulum Ca2+ release and arrhythmogenesis under pathological conditions.
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Affiliation(s)
- Samuel Galice
- Department of Pharmacology, University of California Davis, Davis, CA
| | - Yuanfang Xie
- Department of Pharmacology, University of California Davis, Davis, CA
| | - Yi Yang
- Department of Pharmacology, University of California Davis, Davis, CA
| | - Daisuke Sato
- Department of Pharmacology, University of California Davis, Davis, CA
| | - Donald M Bers
- Department of Pharmacology, University of California Davis, Davis, CA
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21
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Ca 2+ signals initiate at immobile IP 3 receptors adjacent to ER-plasma membrane junctions. Nat Commun 2017; 8:1505. [PMID: 29138405 PMCID: PMC5686115 DOI: 10.1038/s41467-017-01644-8] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 10/06/2017] [Indexed: 11/08/2022] Open
Abstract
IP3 receptors (IP3Rs) release Ca2+ from the ER when they bind IP3 and Ca2+. The spatial organization of IP3Rs determines both the propagation of Ca2+ signals between IP3Rs and the selective regulation of cellular responses. Here we use gene editing to fluorescently tag endogenous IP3Rs, and super-resolution microscopy to determine the geography of IP3Rs and Ca2+ signals within living cells. We show that native IP3Rs cluster within ER membranes. Most IP3R clusters are mobile, moved by diffusion and microtubule motors. Ca2+ signals are generated by a small population of immobile IP3Rs. These IP3Rs are licensed to respond, but they do not readily mix with mobile IP3Rs. The licensed IP3Rs reside alongside ER-plasma membrane junctions where STIM1, which regulates store-operated Ca2+ entry, accumulates after depletion of Ca2+ stores. IP3Rs tethered close to ER-plasma membrane junctions are licensed to respond and optimally placed to be activated by endogenous IP3 and to regulate Ca2+ entry. IP3 receptors mediate Ca2+ release from the endoplasmic reticulum. Here the authors show that only a small fraction of IP3 receptors initiate Ca2+ signals; these immobile IP3 receptors adjacent to the plasma membrane are optimally placed to control STIM1-dependent Ca2+ entry.
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22
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Keebler MV, Taylor CW. Endogenous signalling pathways and caged IP 3 evoke Ca 2+ puffs at the same abundant immobile intracellular sites. J Cell Sci 2017; 130:3728-3739. [PMID: 28893841 PMCID: PMC5702060 DOI: 10.1242/jcs.208520] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 09/04/2017] [Indexed: 12/18/2022] Open
Abstract
The building blocks of intracellular Ca2+ signals evoked by inositol 1,4,5-trisphosphate receptors (IP3Rs) are Ca2+ puffs, transient focal increases in Ca2+ concentration that reflect the opening of small clusters of IP3Rs. We use total internal reflection fluorescence microscopy and automated analyses to detect Ca2+ puffs evoked by photolysis of caged IP3 or activation of endogenous muscarinic receptors with carbachol in human embryonic kidney 293 cells. Ca2+ puffs evoked by carbachol initiated at an estimated 65±7 sites/cell, and the sites remained immobile for many minutes. Photolysis of caged IP3 evoked Ca2+ puffs at a similar number of sites (100±35). Increasing the carbachol concentration increased the frequency of Ca2+ puffs without unmasking additional Ca2+ release sites. By measuring responses to sequential stimulation with carbachol or photolysed caged IP3, we established that the two stimuli evoked Ca2+ puffs at the same sites. We conclude that IP3-evoked Ca2+ puffs initiate at numerous immobile sites and the sites become more likely to fire as the IP3 concentration increases; there is no evidence that endogenous signalling pathways selectively deliver IP3 to specific sites. Summary: Ca2+ puffs are the building blocks for IP3-evoked Ca2+ signals. Ca2+ puffs evoked by caged IP3 or via endogenous signalling pathways initiate at the same fixed intracellular sites.
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Affiliation(s)
- Michael V Keebler
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Colin W Taylor
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
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23
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Maltsev AV, Maltsev VA, Stern MD. Stabilization of diastolic calcium signal via calcium pump regulation of complex local calcium releases and transient decay in a computational model of cardiac pacemaker cell with individual release channels. PLoS Comput Biol 2017; 13:e1005675. [PMID: 28792496 PMCID: PMC5562330 DOI: 10.1371/journal.pcbi.1005675] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 08/18/2017] [Accepted: 07/06/2017] [Indexed: 11/18/2022] Open
Abstract
Intracellular Local Ca releases (LCRs) from sarcoplasmic reticulum (SR) regulate cardiac pacemaker cell function by activation of electrogenic Na/Ca exchanger (NCX) during diastole. Prior studies demonstrated the existence of powerful compensatory mechanisms of LCR regulation via a complex local cross-talk of Ca pump, release and NCX. One major obstacle to study these mechanisms is that LCR exhibit complex Ca release propagation patterns (including merges and separations) that have not been characterized. Here we developed new terminology, classification, and computer algorithms for automatic detection of numerically simulated LCRs and examined LCR regulation by SR Ca pumping rate (Pup) that provides a major contribution to fight-or-flight response. In our simulations the faster SR Ca pumping accelerates action potential-induced Ca transient decay and quickly clears Ca under the cell membrane in diastole, preventing premature releases. Then the SR generates an earlier, more synchronized, and stronger diastolic LCR signal activating an earlier and larger inward NCX current. LCRs at higher Pup exhibit larger amplitudes and faster propagation with more collisions to each other. The LCRs overlap with Ca transient decay, causing an elevation of the average diastolic [Ca] nadir to ~200 nM (at Pup = 24 mM/s). Background Ca (in locations lacking LCRs) quickly decays to resting Ca levels (<100 nM) at high Pup, but remained elevated during slower decay at low Pup. Release propagation is facilitated at higher Pup by a larger LCR amplitude, whereas at low Pup by higher background Ca. While at low Pup LCRs show smaller amplitudes, their larger durations and sizes combined with longer transient decay stabilize integrals of diastolic Ca and NCX current signals. Thus, the local interplay of SR Ca pump and release channels regulates LCRs and Ca transient decay to insure fail-safe pacemaker cell operation within a wide range of rates.
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Affiliation(s)
- Alexander V. Maltsev
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, 251 Bayview Blvd., Baltimore, MD, United States of America
| | - Victor A. Maltsev
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, 251 Bayview Blvd., Baltimore, MD, United States of America
| | - Michael D. Stern
- Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, NIH, 251 Bayview Blvd., Baltimore, MD, United States of America
- * E-mail:
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24
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Lee AM, Colin-York H, Fritzsche M. CalQuo 2 : Automated Fourier-space, population-level quantification of global intracellular calcium responses. Sci Rep 2017; 7:5416. [PMID: 28710416 PMCID: PMC5511169 DOI: 10.1038/s41598-017-05322-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 06/09/2017] [Indexed: 02/06/2023] Open
Abstract
Intracellular calcium acts as a secondary messenger in a wide variety of crucial biological signaling processes. Advances in fluorescence microscopy and calcium sensitive dyes has led to the routine quantification of calcium responses in non-excitable cells. However, the automatization of global intracellular calcium analysis at the single-cell level within a large population simultaneously remains challenging. One software, CalQuo (Calcium Quantification), offers some automatic features in calcium analysis. Here, we present an advanced version of the software package: CalQuo 2 . CalQuo 2 analyzes the calcium response in the Fourier-domain, allowing the number of user-defined filtering parameters to be reduced to one and a greater diversity of calcium responses to be recognized, compared to CalQuo that directly interprets the calcium intensity signal. CalQuo 2 differentiates cells that release a single calcium response and those that release oscillatory calcium fluxes. We have demonstrated the use of CalQuo 2 by measuring the calcium response in genetically modified Jurkat T-cells under varying ligand conditions, in which we show that peptide:MHCs and anti-CD3 antibodies trigger a fraction of T cells to release oscillatory calcium fluxes that increase with increasing koff rates. These results show that CalQuo 2 is a robust and user-friendly tool for characterizing global, single cell calcium responses.
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Affiliation(s)
- Angela M Lee
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford, OX3 9DS, United Kingdom
| | - Huw Colin-York
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford, OX3 9DS, United Kingdom
| | - Marco Fritzsche
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford, OX3 9DS, United Kingdom.
- Kennedy Institute for Rheumatology, Roosevelt Drive, University of Oxford, Oxford, OX3 7FY, United Kingdom.
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25
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Computer algorithms for automated detection and analysis of local Ca2+ releases in spontaneously beating cardiac pacemaker cells. PLoS One 2017; 12:e0179419. [PMID: 28683095 PMCID: PMC5500000 DOI: 10.1371/journal.pone.0179419] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Accepted: 05/29/2017] [Indexed: 11/25/2022] Open
Abstract
Local Ca2+ Releases (LCRs) are crucial events involved in cardiac pacemaker cell function. However, specific algorithms for automatic LCR detection and analysis have not been developed in live, spontaneously beating pacemaker cells. In the present study we measured LCRs using a high-speed 2D-camera in spontaneously contracting sinoatrial (SA) node cells isolated from rabbit and guinea pig and developed a new algorithm capable of detecting and analyzing the LCRs spatially in two-dimensions, and in time. Our algorithm tracks points along the midline of the contracting cell. It uses these points as a coordinate system for affine transform, producing a transformed image series where the cell does not contract. Action potential-induced Ca2+ transients and LCRs were thereafter isolated from recording noise by applying a series of spatial filters. The LCR birth and death events were detected by a differential (frame-to-frame) sensitivity algorithm applied to each pixel (cell location). An LCR was detected when its signal changes sufficiently quickly within a sufficiently large area. The LCR is considered to have died when its amplitude decays substantially, or when it merges into the rising whole cell Ca2+ transient. Ultimately, our algorithm provides major LCR parameters such as period, signal mass, duration, and propagation path area. As the LCRs propagate within live cells, the algorithm identifies splitting and merging behaviors, indicating the importance of locally propagating Ca2+-induced-Ca2+-release for the fate of LCRs and for generating a powerful ensemble Ca2+ signal. Thus, our new computer algorithms eliminate motion artifacts and detect 2D local spatiotemporal events from recording noise and global signals. While the algorithms were developed to detect LCRs in sinoatrial nodal cells, they have the potential to be used in other applications in biophysics and cell physiology, for example, to detect Ca2+ wavelets (abortive waves), sparks and embers in muscle cells and Ca2+ puffs and syntillas in neurons.
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26
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Mackay L, Mikolajewicz N, Komarova SV, Khadra A. Systematic Characterization of Dynamic Parameters of Intracellular Calcium Signals. Front Physiol 2016; 7:525. [PMID: 27891096 PMCID: PMC5102910 DOI: 10.3389/fphys.2016.00525] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 10/24/2016] [Indexed: 12/14/2022] Open
Abstract
Dynamic processes, such as intracellular calcium signaling, are hallmark of cellular biology. As real-time imaging modalities become widespread, a need for analytical tools to reliably characterize time-series data without prior knowledge of the nature of the recordings becomes more pressing. The goal of this study is to develop a signal-processing algorithm for MATLAB that autonomously computes the parameters characterizing prominent single transient responses (TR) and/or multi-peaks responses (MPR). The algorithm corrects for signal contamination and decomposes experimental recordings into contributions from drift, TRs, and MPRs. It subsequently provides numerical estimates for the following parameters: time of onset after stimulus application, activation time (time for signal to increase from 10 to 90% of peak), and amplitude of response. It also provides characterization of the (i) TRs by quantifying their area under the curve (AUC), response duration (time between 1/2 amplitude on ascent and descent of the transient), and decay constant of the exponential decay region of the deactivation phase of the response, and (ii) MPRs by quantifying the number of peaks, mean peak magnitude, mean periodicity, standard deviation of periodicity, oscillatory persistence (time between first and last discernable peak), and duty cycle (fraction of period during which system is active) for all the peaks in the signal, as well as coherent oscillations (i.e., deterministic spikes). We demonstrate that the signal detection performance of this algorithm is in agreement with user-mediated detection and that parameter estimates obtained manually and algorithmically are correlated. We then apply this algorithm to study how metabolic acidosis affects purinergic (P2) receptor-mediated calcium signaling in osteoclast precursor cells. Our results reveal that acidosis significantly attenuates the amplitude and AUC calcium responses at high ATP concentrations. Collectively, our data validated this algorithm as a general framework for comprehensively analyzing dynamic time-series.
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Affiliation(s)
- Laurent Mackay
- Department of Physiology, McGill University Montreal, QC, Canada
| | - Nicholas Mikolajewicz
- Faculty of Dentistry, McGill UniversityMontreal, QC, Canada; Shriners Hospital for Children-CanadaMontreal, QC, Canada
| | - Svetlana V Komarova
- Faculty of Dentistry, McGill UniversityMontreal, QC, Canada; Shriners Hospital for Children-CanadaMontreal, QC, Canada
| | - Anmar Khadra
- Department of Physiology, McGill University Montreal, QC, Canada
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27
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Szymanska AF, Heylman C, Datta R, Gratton E, Nenadic Z. Automated detection and analysis of depolarization events in human cardiomyocytes using MaDEC. Comput Biol Med 2016; 75:109-17. [PMID: 27281718 DOI: 10.1016/j.compbiomed.2016.05.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 05/17/2016] [Accepted: 05/20/2016] [Indexed: 11/16/2022]
Abstract
Optical imaging-based methods for assessing the membrane electrophysiology of in vitro human cardiac cells allow for non-invasive temporal assessment of the effect of drugs and other stimuli. Automated methods for detecting and analyzing the depolarization events (DEs) in image-based data allow quantitative assessment of these different treatments. In this study, we use 2-photon microscopy of fluorescent voltage-sensitive dyes (VSDs) to capture the membrane voltage of actively beating human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs). We built a custom and freely available Matlab software, called MaDEC, to detect, quantify, and compare DEs of hiPS-CMs treated with the β-adrenergic drugs, propranolol and isoproterenol. The efficacy of our software is quantified by comparing detection results against manual DE detection by expert analysts, and comparing DE analysis results to known drug-induced electrophysiological effects. The software accurately detected DEs with true positive rates of 98-100% and false positive rates of 1-2%, at signal-to-noise ratios (SNRs) of 5 and above. The MaDEC software was also able to distinguish control DEs from drug-treated DEs both immediately as well as 10min after drug administration.
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Affiliation(s)
- Agnieszka F Szymanska
- Department of Biomedical Engineering, University of California Irvine, Irvine, CA 92697, USA.
| | - Christopher Heylman
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California Irvine, Irvine, CA 92697, USA
| | - Rupsa Datta
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California Irvine, Irvine, CA 92697, USA
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, Department of Biomedical Engineering, University of California Irvine, Irvine, CA 92697, USA
| | - Zoran Nenadic
- Department of Biomedical Engineering, University of California Irvine, Irvine, CA 92697, USA
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28
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Cully TR, Launikonis BS. Leaky ryanodine receptors delay the activation of store overload-induced Ca2+ release, a mechanism underlying malignant hyperthermia-like events in dystrophic muscle. Am J Physiol Cell Physiol 2016; 310:C673-80. [PMID: 26825125 DOI: 10.1152/ajpcell.00366.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 01/19/2016] [Indexed: 02/04/2023]
Abstract
The mouse model of Duchenne muscular dystrophy, the mdx mouse, displays changes in Ca(2+)homeostasis that may lead to the pathology of the muscle. Here we examine the activation of store overload-induced Ca(2+)release (SOICR) in mdx muscle. The activation of SOICR is associated with the depolymerization of the sarcoplasmic reticulum (SR) Ca(2+)buffer calsequestrin and the reduction of SR Ca(2+)buffering power (BSR). The role of SOICR in healthy and dystrophic muscle is unclear. Using skinned fibers we show that lowering the Mg(2+)concentration can activate discrete Ca(2+)release events that did not necessarily lead to activation of SOICR. However, SOICR waves could propagate into these fiber segments. The average delay to activation of SOICR in mdx fibers was longer than in wild-type (WT) fibers. In the lowered Ca(2+)-buffered environment following large SOICR events, brief waves in mdx fibers displayed a low amplitude and propagation rate, in contrast to WT fibers that showed a range of amplitudes correlated with wave propagation rate. The distinct properties of SOICR in mdx fibers were consistent with a ryanodine receptor (RyR) that was leakier to Ca(2+)than in WT. The consequence of delayed SOICR and leaky RyRs is prolonged high BSRand a reduction in free Ca(2+)concentration inside the SR as total SR calcium drops. We present a hypothesis that SOICR activation is required in healthy muscle and that this mechanism works suboptimally in mdx fibers to fail to limit the activation of store-operated Ca(2+)entry.
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Affiliation(s)
- Tanya R Cully
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Bradley S Launikonis
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
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29
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Fritzsche M, Fernandes RA, Colin-York H, Santos AM, Lee SF, Lagerholm BC, Davis SJ, Eggeling C. CalQuo: automated, simultaneous single-cell and population-level quantification of global intracellular Ca2+ responses. Sci Rep 2015; 5:16487. [PMID: 26563585 PMCID: PMC4643230 DOI: 10.1038/srep16487] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 10/14/2015] [Indexed: 11/08/2022] Open
Abstract
Detecting intracellular calcium signaling with fluorescent calcium indicator dyes is often coupled with microscopy techniques to follow the activation state of non-excitable cells, including lymphocytes. However, the analysis of global intracellular calcium responses both at the single-cell level and in large ensembles simultaneously has yet to be automated. Here, we present a new software package, CalQuo (Calcium Quantification), which allows the automated analysis and simultaneous monitoring of global fluorescent calcium reporter-based signaling responses in up to 1000 single cells per experiment, at temporal resolutions of sub-seconds to seconds. CalQuo quantifies the number and fraction of responding cells, the temporal dependence of calcium signaling and provides global and individual calcium-reporter fluorescence intensity profiles. We demonstrate the utility of the new method by comparing the calcium-based signaling responses of genetically manipulated human lymphocytic cell lines.
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Affiliation(s)
- Marco Fritzsche
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS Oxford, United Kingdom
| | - Ricardo A. Fernandes
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS Oxford, United Kingdom
| | - Huw Colin-York
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS Oxford, United Kingdom
| | - Ana M. Santos
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS Oxford, United Kingdom
| | - Steven F. Lee
- Department of Chemistry, University of Cambridge, CB2 1EW Cambridge, United Kingdom
| | - B. Christoffer Lagerholm
- Wolfson Imaging Centre Oxford, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS Oxford, United Kingdom
| | - Simon J. Davis
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS Oxford, United Kingdom
| | - Christian Eggeling
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS Oxford, United Kingdom
- Wolfson Imaging Centre Oxford, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS Oxford, United Kingdom
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30
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Georgiev T, Zapiec B, Förderer M, Fink RHA, Vogel M. Colocalization properties of elementary Ca(2+) release signals with structures specific to the contractile filaments and the tubular system of intact mouse skeletal muscle fibers. J Struct Biol 2015; 192:366-375. [PMID: 26431893 DOI: 10.1016/j.jsb.2015.09.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 09/26/2015] [Accepted: 09/29/2015] [Indexed: 11/19/2022]
Abstract
Ca(2+) regulates several important intracellular processes. We combined second harmonic generation (SHG) and two photon excited fluorescence microscopy (2PFM) to simultaneously record the SHG signal of the myosin filaments and localized elementary Ca(2+) release signals (LCSs). We found LCSs associated with Y-shaped structures of the myosin filament pattern (YMs), so called verniers, in intact mouse skeletal muscle fibers under hypertonic treatment. Ion channels crucial for the Ca(2+) regulation are located in the tubular system, a system that is important for Ca(2+) regulation and excitation-contraction coupling. We investigated the tubular system of intact, living mouse skeletal muscle fibers using 2PFM and the fluorescent Ca(2+) indicator Fluo-4 dissolved in the external solution or the membrane dye di-8-ANEPPS. We simultaneously measured the SHG signal from the myosin filaments of the skeletal muscle fibers. We found that at least a subset of the YMs observed in SHG images are closely juxtaposed with Y-shaped structures of the transverse tubules (YTs). The distances of corresponding YMs and YTs yield values between 1.3 μm and 4.1 μm including pixel uncertainty with a mean distance of 2.52±0.10 μm (S.E.M., n=41). Additionally, we observed that some of the linear-shaped areas in the tubular system are colocalized with linear-shaped areas in the SHG images.
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Affiliation(s)
- Tihomir Georgiev
- Medical Biophysics, Institute of Physiology and Pathophysiology, Ruprecht Karls Universität, Im Neuenheimer Feld 326, 69120 Heidelberg, Germany.
| | - Bolek Zapiec
- Medical Biophysics, Institute of Physiology and Pathophysiology, Ruprecht Karls Universität, Im Neuenheimer Feld 326, 69120 Heidelberg, Germany; Max Planck Research Unit for Neurogenetics, 60438 Frankfurt am Main, Germany
| | - Moritz Förderer
- Medical Biophysics, Institute of Physiology and Pathophysiology, Ruprecht Karls Universität, Im Neuenheimer Feld 326, 69120 Heidelberg, Germany
| | - Rainer H A Fink
- Medical Biophysics, Institute of Physiology and Pathophysiology, Ruprecht Karls Universität, Im Neuenheimer Feld 326, 69120 Heidelberg, Germany
| | - Martin Vogel
- Medical Biophysics, Institute of Physiology and Pathophysiology, Ruprecht Karls Universität, Im Neuenheimer Feld 326, 69120 Heidelberg, Germany; Max Planck Research Unit for Neurogenetics, 60438 Frankfurt am Main, Germany.
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31
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Yang Z, Kirton HM, MacDougall DA, Boyle JP, Deuchars J, Frater B, Ponnambalam S, Hardy ME, White E, Calaghan SC, Peers C, Steele DS. The Golgi apparatus is a functionally distinct Ca2+ store regulated by the PKA and Epac branches of the β1-adrenergic signaling pathway. Sci Signal 2015; 8:ra101. [PMID: 26462734 PMCID: PMC4869832 DOI: 10.1126/scisignal.aaa7677] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Ca(2+) release from the Golgi apparatus regulates key functions of the organelle, including vesicle trafficking. We found that the Golgi apparatus was the source of prolonged Ca(2+) release events that originated near the nuclei of primary cardiomyocytes. Golgi Ca(2+) release was unaffected by depletion of sarcoplasmic reticulum Ca(2+), and disruption of the Golgi apparatus abolished Golgi Ca(2+) release without affecting sarcoplasmic reticulum function, suggesting functional and spatial independence of Golgi and sarcoplasmic reticulum Ca(2+) stores. β1-Adrenoceptor stimulation triggers the production of the second messenger cAMP, which activates the Epac family of Rap guanine nucleotide exchange factors and the kinase PKA (protein kinase A). Phosphodiesterases (PDEs), including those in the PDE3 and PDE4 families, degrade cAMP. Activation of β1-adrenoceptors stimulated Golgi Ca(2+) release, an effect that required activation of Epac, PKA, and the kinase CaMKII. Inhibition of PDE3s or PDE4s potentiated β1-adrenergic-induced Golgi Ca(2+) release, which is consistent with compartmentalization of cAMP signaling near the Golgi apparatus. Interventions that stimulated Golgi Ca(2+) release appeared to increase the trafficking of vascular endothelial growth factor receptor-1 (VEGFR-1) from the Golgi apparatus to the surface membrane of cardiomyocytes. In cardiomyocytes from rats with heart failure, decreases in the abundance of PDE3s and PDE4s were associated with increased Golgi Ca(2+) release events. These data suggest that the Golgi apparatus is a focal point for β1-adrenergic-stimulated Ca(2+) signaling and that the Golgi Ca(2+) store functions independently from the sarcoplasmic reticulum and the global Ca(2+) transients that trigger contraction in cardiomyocytes.
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Affiliation(s)
- Zhaokang Yang
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK.
| | - Hannah M Kirton
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | | | - John P Boyle
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK
| | - James Deuchars
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Brenda Frater
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | | | - Matthew E Hardy
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Edward White
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Sarah C Calaghan
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Chris Peers
- Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK
| | - Derek S Steele
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK.
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32
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Georgiev T, Svirin M, Jaimovich E, Fink RHA. Localized nuclear and perinuclear Ca(2+) signals in intact mouse skeletal muscle fibers. Front Physiol 2015; 6:263. [PMID: 26483696 PMCID: PMC4586431 DOI: 10.3389/fphys.2015.00263] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 09/07/2015] [Indexed: 11/13/2022] Open
Abstract
Nuclear Ca2+ is important for the regulation of several nuclear processes such as gene expression. Localized Ca2+ signals (LCSs) in skeletal muscle fibers of mice have been mainly studied as Ca2+ release events from the sarcoplasmic reticulum. Their location with regard to cell nuclei has not been investigated. Our study is based on the hypothesis that LCSs associated with nuclei are present in skeletal muscle fibers of adult mice. Therefore, we carried out experiments addressing this question and we found novel Ca2+ signals associated with nuclei of skeletal muscle fibers (with possibly attached satellite cells). We measured localized nuclear and perinuclear Ca2+ signals (NLCSs and PLCSs) alongside cytosolic localized Ca2+ signals (CLCSs) during a hypertonic treatment. We also observed NLCSs under isotonic conditions. The NLCSs and PLCSs are Ca2+ signals in the range of micrometer [FWHM (full width at half maximum): 2.75 ± 0.27 μm (NLCSs) and 2.55 ± 0.17 μm (PLCSs), S.E.M.]. Additionally, global nuclear Ca2+ signals (NGCSs) were observed. To investigate which type of Ca2+ channels contribute to the Ca2+ signals associated with nuclei in skeletal muscle fibers, we performed measurements with the RyR blocker dantrolene, the DHPR blocker nifedipine or the IP3R blocker Xestospongin C. We observed Ca2+ signals associated with nuclei in the presence of each blocker. Nifedipine and dantrolene had an inhibitory effect on the fraction of fibers with PLCSs. The situation for the fraction of fibers with NLCSs is more complex indicating that RyR is less important for the generation of NLCSs compared to the generation of PLCSs. The fraction of fibers with NLCSs and PLCSs is not reduced in the presence of Xestospongin C. The localized perinuclear and intranuclear Ca2+ signals may be a powerful tool for the cell to regulate adaptive processes as gene expression. The intranuclear Ca2+ signals may be particularly interesting in this respect.
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Affiliation(s)
- Tihomir Georgiev
- Medical Biophysics Unit, Institut für Physiologie und Pathophysiologie, Ruprecht Karls Universität Heidelberg, Germany ; Facultad de Medicina, Center for Molecular Studies of the Cell, Universidad de Chile Santiago de Chile, Chile
| | - Mikhail Svirin
- Medical Biophysics Unit, Institut für Physiologie und Pathophysiologie, Ruprecht Karls Universität Heidelberg, Germany
| | - Enrique Jaimovich
- Facultad de Medicina, Center for Molecular Studies of the Cell, Universidad de Chile Santiago de Chile, Chile
| | - Rainer H A Fink
- Medical Biophysics Unit, Institut für Physiologie und Pathophysiologie, Ruprecht Karls Universität Heidelberg, Germany
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33
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Ellefsen KL, Settle B, Parker I, Smith IF. An algorithm for automated detection, localization and measurement of local calcium signals from camera-based imaging. Cell Calcium 2014; 56:147-56. [PMID: 25047761 DOI: 10.1016/j.ceca.2014.06.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2014] [Revised: 06/10/2014] [Accepted: 06/15/2014] [Indexed: 10/25/2022]
Abstract
Local Ca(2+) transients such as puffs and sparks form the building blocks of cellular Ca(2+) signaling in numerous cell types. They have traditionally been studied by linescan confocal microscopy, but advances in TIRF microscopy together with improved electron-multiplied CCD (EMCCD) cameras now enable rapid (>500 frames s(-1)) imaging of subcellular Ca(2+) signals with high spatial resolution in two dimensions. This approach yields vastly more information (ca. 1 Gb min(-1)) than linescan imaging, rendering visual identification and analysis of local events imaged both laborious and subject to user bias. Here we describe a routine to rapidly automate identification and analysis of local Ca(2+) events. This features an intuitive graphical user-interfaces and runs under Matlab and the open-source Python software. The underlying algorithm features spatial and temporal noise filtering to reliably detect even small events in the presence of noisy and fluctuating baselines; localizes sites of Ca(2+) release with sub-pixel resolution; facilitates user review and editing of data; and outputs time-sequences of fluorescence ratio signals for identified event sites along with Excel-compatible tables listing amplitudes and kinetics of events.
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Affiliation(s)
- Kyle L Ellefsen
- Department of Neurobiology & Behavior, University of California, Irvine, CA 92697, USA
| | - Brett Settle
- Department of Neurobiology & Behavior, University of California, Irvine, CA 92697, USA
| | - Ian Parker
- Department of Neurobiology & Behavior, University of California, Irvine, CA 92697, USA; Department of Physiology & Biophysics, University of California, Irvine, CA 92697, USA
| | - Ian F Smith
- Department of Neurobiology & Behavior, University of California, Irvine, CA 92697, USA.
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