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Shi W, Han Y, Guo C, Zhao X, Liu S, Su W, Wang Y, Zha S, Chai X, Liu G. Ocean acidification hampers sperm-egg collisions, gamete fusion, and generation of Ca 2+ oscillations of a broadcast spawning bivalve, Tegillarca granosa. MARINE ENVIRONMENTAL RESEARCH 2017; 130:106-112. [PMID: 28750793 DOI: 10.1016/j.marenvres.2017.07.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 07/15/2017] [Accepted: 07/18/2017] [Indexed: 06/07/2023]
Abstract
Although the effect of ocean acidification on fertilization success of marine organisms is increasingly well documented, the underlying mechanisms are not completely understood. The fertilization success of broadcast spawning invertebrates depends on successful sperm-egg collisions, gamete fusion, and standard generation of Ca2+ oscillations. Therefore, the realistic effects of future ocean pCO2 levels on these specific aspects of fertilization of Tegillarca granosa were investigated in the present study through sperm velocity trials, fertilization kinetics model analysis, and intracellular Ca2+ assays, respectively. Results obtained indicated that ocean acidification significantly reduced the fertilization success of T. granosa, which could be accountable by (i) decreased sperm velocity hence reducing the probability for sperm-egg collisions; (ii) lowered probability of gamete fusion for each gamete collision event; and (iii) disrupted intracellular Ca2+ oscillations.
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Affiliation(s)
- Wei Shi
- College of Animal Sciences, Zhejiang University, Hangzhou, PR China
| | - Yu Han
- College of Animal Sciences, Zhejiang University, Hangzhou, PR China
| | - Cheng Guo
- College of Animal Sciences, Zhejiang University, Hangzhou, PR China
| | - Xinguo Zhao
- College of Animal Sciences, Zhejiang University, Hangzhou, PR China
| | - Saixi Liu
- College of Animal Sciences, Zhejiang University, Hangzhou, PR China
| | - Wenhao Su
- College of Animal Sciences, Zhejiang University, Hangzhou, PR China
| | - Yichen Wang
- College of Animal Sciences, Zhejiang University, Hangzhou, PR China
| | - Shanjie Zha
- College of Animal Sciences, Zhejiang University, Hangzhou, PR China
| | - Xueliang Chai
- Zhejiang Mariculture Research Institute, Wenzhou, PR China
| | - Guangxu Liu
- College of Animal Sciences, Zhejiang University, Hangzhou, PR China.
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Ma Q, Ye L, Liu H, Shi Y, Zhou N. An overview of Ca 2+ mobilization assays in GPCR drug discovery. Expert Opin Drug Discov 2017; 12:511-523. [PMID: 28277837 DOI: 10.1080/17460441.2017.1303473] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
INTRODUCTION Calcium ions (Ca2+) serve as a second messenger or universal signal transducer implicated in the regulation of a wide range of physiological processes. A change in the concentration of intracellular Ca2+ is an important step in intracellular signal transduction. G protein-coupled receptors (GPCRs), the largest and most versatile group of cell surface receptors, transduce extracellular signals into intracellular responses via their coupling to heterotrimeric G proteins. Since Ca2+ plays a crucial role in GPCR-induced signaling, measurement of intracellular Ca2+ has attracted more and more attention in GPCR-targeted drug discovery. Areas covered: This review focuses on the most popular functional assays measuring GPCRs-induced intracellular Ca2+ signaling. These include photoprotein-based, synthetic fluorescent indicator-based and genetically encoded calcium indicator (GECI)-based Ca2+ mobilization assays. A brief discussion of the design strategy of fluorescent probes in GPCR studies is also presented. Expert opinion: GPCR-mediated intracellular signaling is multidimensional. There is an urgent need for the development of multiple-readout screening assays capable of simultaneous detection of biased signaling and screening of both agonists and antagonists in the same assay. It is also necessary to develop GECIs offering low cost and consistent assays suitable for investigating GPCR activation in vivo.
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Affiliation(s)
- Qiang Ma
- a College of Life Sciences, Zijingang Campus , Zhejiang University, Institute of Biochemistry and Molecular Biology , Hangzhou , Zhejiang , China
| | - Lingyan Ye
- a College of Life Sciences, Zijingang Campus , Zhejiang University, Institute of Biochemistry and Molecular Biology , Hangzhou , Zhejiang , China
| | - Hongxia Liu
- b Department of Internal Medicine , Edong Healthcare Group , Huangshi , Hubei , China
| | - Ying Shi
- a College of Life Sciences, Zijingang Campus , Zhejiang University, Institute of Biochemistry and Molecular Biology , Hangzhou , Zhejiang , China
| | - Naiming Zhou
- a College of Life Sciences, Zijingang Campus , Zhejiang University, Institute of Biochemistry and Molecular Biology , Hangzhou , Zhejiang , China
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Calcium signaling in human pluripotent stem cells. Cell Calcium 2016; 59:117-23. [PMID: 26922096 DOI: 10.1016/j.ceca.2016.01.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 01/14/2016] [Accepted: 01/19/2016] [Indexed: 01/24/2023]
Abstract
Human pluripotent stem cells provide new tools for developmental and pharmacological studies as well as for regenerative medicine applications. Calcium homeostasis and ligand-dependent calcium signaling are key components of major cellular responses, including cell proliferation, differentiation or apoptosis. Interestingly, these phenomena have not been characterized in detail as yet in pluripotent human cell sates. Here we review the methods applicable for studying both short- and long-term calcium responses, focusing on the expression of fluorescent calcium indicator proteins and imaging methods as applied in pluripotent human stem cells. We discuss the potential regulatory pathways involving calcium responses in hPS cells and compare these to the implicated pathways in mouse PS cells. A recent development in the stem cell field is the recognition of so called "naïve" states, resembling the earliest potential forms of stem cells during development, as well as the "fuzzy" stem cells, which may be alternative forms of pluripotent cell types, therefore we also discuss the potential role of calcium homeostasis in these PS cell types.
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Chen F, Zhu L, Cai L, Zhang J, Zeng X, Li J, Su Y, Hu Q. A stromal interaction molecule 1 variant up-regulates matrix metalloproteinase-2 expression by strengthening nucleoplasmic Ca2+ signaling. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:617-29. [PMID: 26775216 DOI: 10.1016/j.bbamcr.2016.01.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 01/02/2016] [Accepted: 01/11/2016] [Indexed: 10/22/2022]
Abstract
Very recent studies hold promise to reveal the role of stromal interaction molecule 1 (STIM1) in non-store-operated Ca2+ entry. Here we showed that in contrast to cytoplasmic membrane redistribution as previously noted, human umbilical vein endothelial STIM1 with a T-to-C nucleotide transition resulting in an amino acid substitution of leucine by proline in the signal peptide sequence translocated to perinuclear membrane upon intracellular Ca2+ depletion, amplified nucleoplasmic Ca2+ signaling through ryanodine receptor-dependent pathway, and enhanced the subsequent cAMP responsive element binding protein activity, matrix metalloproteinase-2 (MMP-2) gene expression, and endothelial tube forming. The abundance of mutated STIM1 and the MMP-2 expression were higher in native human umbilical vein endothelial cells of patients with gestational hypertension than controls and were significantly correlated with blood pressure. These findings broaden our understanding about structure-function bias of STIM1 and offer unique insights into its application in nucleoplasmic Ca2+, MMP-2 expression, endothelial dysfunction, and pathophysiological mechanism(s) of gestational hypertension.
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Affiliation(s)
- Fengrong Chen
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong Science and Technology University (HUST), Wuhan 430030, People's Republic of China; Key Laboratory of Pulmonary Diseases of Ministry of Health of China, Tongji Medical College, Huazhong Science and Technology University (HUST), Wuhan 430030, People's Republic of China
| | - Liping Zhu
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong Science and Technology University (HUST), Wuhan 430030, People's Republic of China; Key Laboratory of Pulmonary Diseases of Ministry of Health of China, Tongji Medical College, Huazhong Science and Technology University (HUST), Wuhan 430030, People's Republic of China
| | - Lei Cai
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong Science and Technology University (HUST), Wuhan 430030, People's Republic of China; Key Laboratory of Pulmonary Diseases of Ministry of Health of China, Tongji Medical College, Huazhong Science and Technology University (HUST), Wuhan 430030, People's Republic of China
| | - Jiwei Zhang
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong Science and Technology University (HUST), Wuhan 430030, People's Republic of China; Key Laboratory of Pulmonary Diseases of Ministry of Health of China, Tongji Medical College, Huazhong Science and Technology University (HUST), Wuhan 430030, People's Republic of China
| | - Xianqin Zeng
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong Science and Technology University (HUST), Wuhan 430030, People's Republic of China; Key Laboratory of Pulmonary Diseases of Ministry of Health of China, Tongji Medical College, Huazhong Science and Technology University (HUST), Wuhan 430030, People's Republic of China
| | - Jiansha Li
- Key Laboratory of Pulmonary Diseases of Ministry of Health of China, Tongji Medical College, Huazhong Science and Technology University (HUST), Wuhan 430030, People's Republic of China; Department of Pathology, Tongji Hospital, Tongji Medical College, Huazhong Science and Technology University (HUST), Wuhan 430030, People's Republic of China
| | - Yuan Su
- Key Laboratory of Pulmonary Diseases of Ministry of Health of China, Tongji Medical College, Huazhong Science and Technology University (HUST), Wuhan 430030, People's Republic of China; Department of Respiratory Medicine, Union Hospital, Tongji Medical College, Huazhong Science and Technology University (HUST), Wuhan 430030, People's Republic of China
| | - Qinghua Hu
- Department of Pathophysiology, School of Basic Medicine, Tongji Medical College, Huazhong Science and Technology University (HUST), Wuhan 430030, People's Republic of China; Key Laboratory of Pulmonary Diseases of Ministry of Health of China, Tongji Medical College, Huazhong Science and Technology University (HUST), Wuhan 430030, People's Republic of China; Key Laboratory of Molecular Biophysics of the Ministry of Education, Huazhong Science and Technology University (HUST), Wuhan 430030, People's Republic of China.
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5
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Zhao S, Liu ZX, Bao ZJ, Wu Y, Wang K, Yu GM, Wang CM, Zeng SM. Age-associated potency decline in bovine oocytes is delayed by blocking extracellular Ca(2+) influx. Theriogenology 2015; 83:1493-501. [PMID: 25784452 DOI: 10.1016/j.theriogenology.2015.01.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 01/09/2015] [Accepted: 01/17/2015] [Indexed: 10/24/2022]
Abstract
Oocyte aging due to delayed fertilization is associated with declining quality and developmental potential. Intracellular calcium (Ca(2+)) concentration ([Ca(2+)]i) regulates oocyte growth, maturation, and fertilization and has also been implicated in aging. Using bovine oocytes, we tested the hypothesis that oocyte aging could be delayed by reducing [Ca(2+)]ivia blocking the influx of extracellular Ca(2+) or chelating ooplasmic free Ca(2+). After IVM, cumulus-oocyte complexes or denuded oocytes were cultured in medium supplemented with 1-octanol, phorbol 12-myristate 13-acetate, or 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis-acetoxymethyl ester (BAPTA-AM) to manipulate [Ca(2+)]i. Addition of 1-mM 1-octanol increased blastocyst development rates in the cumulus-oocyte complexes aged for 6 hours by IVF and for 6, 12, and 24 hours by parthenoactivation, and this effect was independent of the presence of cumulus cells. The intracellular levels of ATP, Glutathione, and Glutathione disulfide were not affected by 1-octanol, but [Ca(2+)]i was significantly decreased. When oocytes were cultured in Ca(2+)-free medium for 12 hours, the blastocyst development rate was greater and the beneficial effects of 1-octanol on oocyte aging were abolished. However, when the medium was supplemented with phorbol 12-myristate 13-acetate, [Ca(2+)]i increased and the blastocyst development rate decreased. Moreover, BAPTA-AM reduced [Ca(2+)]i and increased blastocyst development rates after IVF or parthenoactivation. We conclude that the age-associated developmental potency decline was delayed by blocking the influx of extracellular Ca(2+) or reducing ooplasmic free Ca(2+). 1-Octanol, BAPTA-AM, or Ca(2+)-free medium could be used to lengthen the fertilization windows of aged bovine oocytes.
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Affiliation(s)
- Shuan Zhao
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China; Laboratory of Animal Embryonic Biotechnology, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Zhen-Xing Liu
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China; Laboratory of Animal Embryonic Biotechnology, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Zhong-Jian Bao
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China; Laboratory of Animal Embryonic Biotechnology, College of Animal Science and Technology, China Agricultural University, Beijing, China; Laboratory of genitourinary, Assisted Reproductive Technology Center, Shenzhen Zhongshan Urology Hospital, Shenzhen, China
| | - Yi Wu
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China; Laboratory of Animal Embryonic Biotechnology, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Kun Wang
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China; Laboratory of Animal Embryonic Biotechnology, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Guang-Min Yu
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China; Laboratory of Animal Embryonic Biotechnology, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Cui-Mei Wang
- Yantai Research Institute, China Agricultural University, Yantai, Shandong, China
| | - Shen-Ming Zeng
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, National Engineering laboratory for Animal Breeding, College of Animal Science and Technology, China Agricultural University, Beijing, China; Laboratory of Animal Embryonic Biotechnology, College of Animal Science and Technology, China Agricultural University, Beijing, China.
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6
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Meng G, Pan L, Li C, Hu F, Shi X, Lee I, Drevenšek-Olenik I, Zhang X, Xu J. Temperature-induced labelling of Fluo-3 AM selectively yields brighter nucleus in adherent cells. Biochem Biophys Res Commun 2013; 443:888-93. [PMID: 24380862 DOI: 10.1016/j.bbrc.2013.12.105] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 12/11/2013] [Indexed: 10/25/2022]
Abstract
Fluo-3 is widely used to study cell calcium. Two traditional approaches: (1) direct injection and (2) Fluo-3 acetoxymethyl ester (AM) loading, often bring conflicting results in cytoplasmic calcium ([Ca(2+)]c) and nuclear calcium ([Ca(2+)]n) imaging. AM loading usually yields a darker nucleus than in cytoplasm, while direct injection always induces a brighter nucleus which is more responsive to [Ca(2+)]n detection. In this work, we detailedly investigated the effects of loading and de-esterification temperatures on the fluorescence intensity of Fluo-3 in response to [Ca(2+)]n and [Ca(2+)]c in adherent cells, including osteoblast, HeLa and BV2 cells. Interestingly, it showed that fluorescence intensity of nucleus in osteoblast cells was about two times larger than that of cytoplasm when cells were loaded with Fluo-3 AM at 4 °C and allowed a subsequent step for de-esterification at 20 °C. Brighter nuclei were also acquired in HeLa and BV2 cells using the same experimental condition. Furthermore, loading time and adhesion quality of cells had effect on fluorescence intensity. Taken together, cold loading and room temperature de-esterification treatment of Fluo-3 AM selectively yielded brighter nucleus in adherent cells.
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Affiliation(s)
- Guixian Meng
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin, China
| | - Leiting Pan
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin, China.
| | - Cunbo Li
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin, China
| | - Fen Hu
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin, China
| | - Xuechen Shi
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin, China
| | - Imshik Lee
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin, China
| | - Irena Drevenšek-Olenik
- Faculty of Mathematics and Physics, University of Ljubljana, and J. Stefan Institute, Ljubljana, Slovenia
| | - Xinzheng Zhang
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin, China
| | - Jingjun Xu
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin, China
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Zheng J, Chen Z, Yin W, Miao L, Zhou Z, Ji G. Ryanodine receptors are involved in nuclear calcium oscillation in primary pancreatic β-cells. Biochem Biophys Res Commun 2012; 423:207-11. [PMID: 22564739 DOI: 10.1016/j.bbrc.2012.04.114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 04/21/2012] [Indexed: 12/31/2022]
Abstract
Ryanodine receptors (RyRs) are mainly located on the endoplasmic reticulum (ER) and play an important role in regulating glucose-induced cytosolic Ca(2+) oscillation in pancreatic β-cells. However, subcellular locations and functions of RyRs on other cell organelles such as nuclear envelope are not well understood. In order to investigate the role of RyRs in nuclear Ca(2+) oscillation we designed and conducted experiments in intact primary pancreatic β-cells. Immunocytochemistry was used to examine the expression of RYRs on the nuclear envelope. Confocal microscopy was used to evaluate the function of RYRs on the nuclear envelope. We found that RyRs are expressed on the nuclear envelope in single primary pancreatic β-cells and isolated nuclei. Laser scanning confocal microscopy studies indicated that application of glucose to the cells co-incubated with Ca(2+) indicator Fluo-4 AM and cell-permeable nuclear indicator Hoechst 33342 resulted in nuclear Ca(2+) oscillation. The pattern of glucose-induced Ca(2+) oscillation in the nucleus and cytosol was similar. The reduction of Ca(2+) oscillation amplitude by ryanodine was much greater in the nucleus though both the cytosol and the nucleus Ca(2+) amplitude decreased by ryanodine. Our results suggest that functional ryanodine receptors not only exist in endoplasmic reticulum but are also expressed in nuclear envelope of pancreatic β-cells.
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Affiliation(s)
- Ji Zheng
- Urological Surgery Research Institute, Southwest Hospital, Third Military Medical University, Chongqing, China
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9
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Apáti Á, Pászty K, Erdei Z, Szebényi K, Homolya L, Sarkadi B. Calcium signaling in pluripotent stem cells. Mol Cell Endocrinol 2012; 353:57-67. [PMID: 21945604 DOI: 10.1016/j.mce.2011.08.038] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Revised: 08/30/2011] [Accepted: 08/30/2011] [Indexed: 10/17/2022]
Abstract
Pluripotent stem cells represent a new source of biological material allowing the exploration of signaling phenomena during normal cell development and differentiation. Still, the calcium signaling pathways and intracellular calcium responses to various ligands or stress conditions have not been sufficiently explored as yet in embryonic or induced pluripotent stem cells and in their differentiated offspring. This is partly due to the special culturing conditions of these cell types, the rapid morphological and functional changes in heterogeneous cell populations during early differentiation, and methodological problems in cellular calcium measurements. In this paper, we review the currently available data in the literature on calcium signaling in pluripotent stem cells and discuss the potential shortcomings of these studies. Various assay methods are surveyed for obtaining reliable data both in undifferentiated embryonic stem cells and in specific, stem cell-derived human tissues. In this paper, we present the modulation of calcium signaling in human embryonic stem cells (hESC) and in their derivates; mesenchymal stem cell like (MSCl) cells and cardiac tissues using the fluorescent calcium indicator Fluo-4 and confocal microscopy. LPA, trypsin and angiotensin II were effective in inducing calcium signals both in HUES9 and MSCl cells. Histamine and thrombin induced calcium signal exclusively in the MSCl cells, while ATP was effective only in HUES9 cells. There was no calcium signal evoked by GABA, even at relatively high concentrations. In stem cell-derived cardiomyocytes a rapid increase in the beating rate and an increase of the calcium signal peaks could be observed after the addition of adrenaline, while verapamil led to a strong decrease in cellular calcium and stopped spontaneous contractions in a relaxed state.
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Affiliation(s)
- Ágota Apáti
- Membrane Research Group of the Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary
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Dupriez VJ, Maes K, Le Poul E, Burgeon E, Detheux M. Aequorin-Based Functional Assays for G-Protein-Coupled Receptors, Ion Channels, and Tyrosine Kinase Receptors. ACTA ACUST UNITED AC 2011. [DOI: 10.3109/10606820214646] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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11
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Ljubojević S, Walther S, Asgarzoei M, Sedej S, Pieske B, Kockskämper J. In situ calibration of nucleoplasmic versus cytoplasmic Ca²+ concentration in adult cardiomyocytes. Biophys J 2011; 100:2356-66. [PMID: 21575569 DOI: 10.1016/j.bpj.2011.03.060] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 03/14/2011] [Accepted: 03/31/2011] [Indexed: 12/31/2022] Open
Abstract
Quantification of subcellularly resolved Ca²⁺ signals in cardiomyocytes is essential for understanding Ca²⁺ fluxes in excitation-contraction and excitation-transcription coupling. The properties of fluorescent indicators in intracellular compartments may differ, thus affecting the translation of Ca²⁺-dependent fluorescence changes into [Ca²⁺] changes. Therefore, we determined the in situ characteristics of a frequently used Ca²⁺ indicator, Fluo-4, and a ratiometric Ca²⁺ indicator, Asante Calcium Red, and evaluated their use for reporting and quantifying cytoplasmic and nucleoplasmic Ca²⁺ signals in isolated cardiomyocytes. Ca²⁺ calibration curves revealed significant differences in the apparent Ca²⁺ dissociation constants of Fluo-4 and Asante Calcium Red between cytoplasm and nucleoplasm. These parameters were used for transformation of fluorescence into nucleoplasmic and cytoplasmic [Ca²⁺]. Resting and diastolic [Ca²⁺] were always higher in the nucleoplasm. Systolic [Ca²⁺] was usually higher in the cytoplasm, but some cells (15%) exhibited higher systolic [Ca²⁺] in the nucleoplasm. Ca²⁺ store depletion or blockade of Ca²⁺ leak pathways eliminated the resting [Ca²⁺] gradient between nucleoplasm and cytoplasm, whereas inhibition of inositol 1,4,5-trisphosphate receptors by 2-APB reversed it. The results suggest the presence of significant nucleoplasmic-to-cytoplasmic [Ca²⁺] gradients in resting myocytes and during the cardiac cycle. Nucleoplasmic [Ca²⁺] in cardiomyocytes may be regulated via two mechanisms: diffusion from the cytoplasm and active Ca²⁺ release via inositol 1,4,5-trisphosphate receptors from perinuclear Ca²⁺ stores.
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Affiliation(s)
- Senka Ljubojević
- Division of Cardiology, Medical University of Graz, Graz, Austria
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12
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Gruol DL, Netzeband JG, Nelson TE. Somatic Ca2+ signaling in cerebellar Purkinje neurons. J Neurosci Res 2010; 88:275-89. [PMID: 19681168 DOI: 10.1002/jnr.22204] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Activity-driven Ca(2+) signaling plays an important role in a number of neuronal functions, including neuronal growth, differentiation, and plasticity. Both cytosolic and nuclear Ca(2+) has been implicated in these functions. In the current study, we investigated membrane-to-nucleus Ca(2+) signaling in cerebellar Purkinje neurons in culture to gain insight into the pathways and mechanisms that can initiate nuclear Ca(2+) signaling in this neuronal type. Purkinje neurons are known to express an abundance of Ca(2+) signaling molecules such as voltage-gated Ca(2+) channels, ryanodine receptors, and IP3 receptors. Results show that membrane depolarization evoked by brief stimulation with K(+) saline elicits a prominent Ca(2+) signal in the cytosol and nucleus of the Purkinje neurons. Ca(2+) influx through P/Q- and L-type voltage-gated Ca(2+) channels and Ca(2+)-induced Ca(2+) release (CICR) from intracellular stores contributed to the Ca(2+) signal, which spread from the plasma membrane to the nucleus. At strong K(+) stimulations, the amplitude of the nuclear Ca(2+) signal exceeded that of the cytosolic Ca(2+) signal, suggesting the involvement of a nuclear amplification mechanism and/or differences in Ca(2+) buffering in these two cellular compartments. An enhanced nuclear Ca(2+) signal was more prominent for Ca(2+) signals elicited by membrane depolarization than for Ca(2+) signals elicited by activation of the metabotropic glutamate receptor pathway (mGluR1), which is linked to Ca(2+) release from intracellular stores controlled by the IP3 receptor.
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Affiliation(s)
- D L Gruol
- Molecular and Integrative Neurosciences Department, The Scripps Research Institute, La Jolla, California 92037, USA.
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Bootman MD, Fearnley C, Smyrnias I, MacDonald F, Roderick HL. An update on nuclear calcium signalling. J Cell Sci 2009; 122:2337-50. [PMID: 19571113 DOI: 10.1242/jcs.028100] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Over the past 15 years or so, numerous studies have sought to characterise how nuclear calcium (Ca2+) signals are generated and reversed, and to understand how events that occur in the nucleoplasm influence cellular Ca2+ activity, and vice versa. In this Commentary, we describe mechanisms of nuclear Ca2+ signalling and discuss what is known about the origin and physiological significance of nuclear Ca2+ transients. In particular, we focus on the idea that the nucleus has an autonomous Ca2+ signalling system that can generate its own Ca2+ transients that modulate processes such as gene transcription. We also discuss the role of nuclear pores and the nuclear envelope in controlling ion flux into the nucleoplasm.
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Affiliation(s)
- Martin D Bootman
- Laboratory of Molecular Signalling, The Babraham Institute, Babraham, Cambridge CB22 3AT, UK.
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Chen Z, Li Z, Peng G, Chen X, Yin W, Kotlikoff MI, Yuan ZQ, Ji G. Extracellular ATP-induced nuclear Ca2+ transient is mediated by inositol 1,4,5-trisphosphate receptors in mouse pancreatic beta-cells. Biochem Biophys Res Commun 2009; 382:381-4. [PMID: 19285037 DOI: 10.1016/j.bbrc.2009.03.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Accepted: 03/06/2009] [Indexed: 10/21/2022]
Abstract
Extracellular ATP (eATP) induces an intracellular Ca(2+) transient by activating phospholipase C (PLC)-associated P2X4 purinergic receptors, leading to production of inositol 1,4,5-trisphosphate (IP3) and subsequent Ca(2+) release from intracellular stores in mouse pancreatic beta-cells. Using laser scanning confocal microscopy, Ca(2+) indicator fluo-4 AM, and the cell permeable nuclear indicator Hoechst 33342, we examined the properties of eATP-induced Ca(2+) release in pancreatic beta-cell nuclei. eATP induced a higher nuclear Ca(2+) transient in pancreatic beta-cell nuclei than in the cytosol. After pretreatment with thapsigargin (TG), an inhibitor of sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA) pumps, the amplitude of eATP-induced Ca(2+) transients in the nucleus was still much higher than those in the cytosol. This effect of eATP was not altered by inhibition of either the plasma membrane Ca(2+)-ATPase (PMCA) or the plasma membrane Na(+)/Ca(2+) exchanger (NCX) by LaCl(3) or by replacement of Na(+) with N-Methyl-Glucosamine. eATP-induced nuclear Ca(2+) transients were abolished by a cell-permeable IP3R inhibitor, 2-aminoethoxydiphenyl borate (2-APB), but were not blocked by the ryanodine receptor (RyR) antagonist ryanodine. Immunofluorescence studies showed that IP3Rs are expressed on the nuclear envelope of pancreatic beta-cells. These results indicate that eATP triggers nuclear Ca(2+) transients by mobilizing a nuclear Ca(2+) store via nuclear IP3Rs.
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Affiliation(s)
- Zheng Chen
- National Laboratory of Biomacromolecules, Institute of Biophysics of Chinese Academy of Sciences, Beijing, China
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15
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Díaz-Muñoz M, de la Rosa Santander P, Juárez-Espinosa AB, Arellano RO, Morales-Tlalpan V. Granulosa cells express three inositol 1,4,5-trisphosphate receptor isoforms: cytoplasmic and nuclear Ca2+ mobilization. Reprod Biol Endocrinol 2008; 6:60. [PMID: 19068129 PMCID: PMC2631483 DOI: 10.1186/1477-7827-6-60] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Accepted: 12/09/2008] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Granulosa cells play an important endocrine role in folliculogenesis. They mobilize Ca2+ from intracellular stores by a coordinated action between 1,4,5 inositol trisphosphate and ryanodine receptors (IP3R and RyR). The aim of this study was to explore the isoforms of IP3Rs expressed in mouse C57BL/6 NHsd granulosa cells, characterizing their intranuclear localization and the relation with other Ca2+-handling proteins. METHODS Ovarian tissue and granulosa cells were analyzed by multiphotonic and confocal microscopy to determine the intracellular presence of IP3R types 1, 2 and 3, RyR, thapsigargin-sensitive Ca2+-ATPase, and endomembranes. Cellular fractionation and Western blot assays were also used to further confirm the nuclear occurrence of the three IP3R isoforms. Free nuclear and cytosolic Ca2+ concentrations were measured using Fluo-4 AM by confocal microscopy. RESULTS By using antibodies and specific fluorophores, was shown that granulosa cells endomembranes contain three isoforms of IP3R, the RyR, and the thapsigargin-sensitive Ca2+-ATPase (SERCA). Interestingly, all these proteins were also detected in the nuclear envelope and in well-defined intranuclear structures. Microsomal membranes depicted characteristic bands of the 3 types of IP3R, but also variants of lower molecular weight. Analysis of nuclear membranes and nucleoplasmic fraction confirmed the nuclear localization of the IP3R types 1, 2 and 3. We demonstrated ATP-induced Ca2+ transients in the nuclear and cytoplasmic compartments. Remarkably, the inhibitory effect on ATP-induced Ca2+ mobilization of brefeldin A was more accentuated in the cytoplasm than in the nucleus. CONCLUSION These findings provide evidence that granulosa cells, including nuclei, express the Ca2+-handling proteins that allow Ca2+ mobilization. All three IP3R were also detected in ovarian slices, including the nuclei of granulosa cells, suggesting that these cells use the three IP3R in situ to achieve their physiological responses.
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Affiliation(s)
- Mauricio Díaz-Muñoz
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus UNAM-Juriquilla, Querétaro 76230, QRO., México
| | - Patricia de la Rosa Santander
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus UNAM-Juriquilla, Querétaro 76230, QRO., México
| | - Anna Berenice Juárez-Espinosa
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus UNAM-Juriquilla, Querétaro 76230, QRO., México
| | - Rogelio O Arellano
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus UNAM-Juriquilla, Querétaro 76230, QRO., México
| | - Verónica Morales-Tlalpan
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Campus UNAM-Juriquilla, Querétaro 76230, QRO., México
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Sappington RM, Calkins DJ. Contribution of TRPV1 to microglia-derived IL-6 and NFkappaB translocation with elevated hydrostatic pressure. Invest Ophthalmol Vis Sci 2008; 49:3004-17. [PMID: 18362111 DOI: 10.1167/iovs.07-1355] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
PURPOSE The authors investigated the contributions of the transient receptor potential vanilloid-1 receptor (TRPV1) and Ca(2+) to microglial IL-6 and nuclear factor kappa B (NFkappaB) translocation with elevated hydrostatic pressure. METHODS The authors first examined IL-6 colocalization with the microglia marker Iba-1 in the DBA/2 mouse model of glaucoma to establish relevance. They isolated microglia from rat retina and maintained them at ambient or elevated (+70 mm Hg) hydrostatic pressure in vitro and used ELISA and immunocytochemistry to measure changes in the IL-6 concentration and NFkappaB translocation induced by the Ca(2+) chelator EGTA, the broad-spectrum Ca(2+) channel inhibitor ruthenium red, and the TRPV1 antagonist iodo-resiniferatoxin (I-RTX). They applied the Ca(2+) dye Fluo-4 AM to measure changes in intracellular Ca(2+) at elevated pressure induced by I-RTX and confirmed TRPV1 expression in microglia using PCR and immunocytochemistry. RESULTS In DBA/2 retina, elevated intraocular pressure increased microglial IL-6 in the ganglion cell layer. Elevated hydrostatic pressure (24 hours) increased microglial IL-6 release, cytosolic NFkappaB, and NFkappaB translocation in vitro. These effects were reduced substantially by EGTA and ruthenium red. Antagonism of TRPV1 in microglia partially inhibited pressure-induced increases in IL-6 release and NFkappaB translocation. Brief elevated pressure (1 hour) induced a significant increase in microglial intracellular Ca(2+) that was partially attenuated by TRPV1 antagonism. CONCLUSIONS Elevated pressure induces an influx of extracellular Ca(2+) in retinal microglia that precedes the activation of NFkappaB and the subsequent production and release of IL-6 and is at least partially dependent on the activation of TRPV1 and other ruthenium red-sensitive channels.
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Affiliation(s)
- Rebecca M Sappington
- Department of Ophthalmology and Visual Sciences, Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee 37232-0654, USA
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17
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Luo D, Yang D, Lan X, Li K, Li X, Chen J, Zhang Y, Xiao RP, Han Q, Cheng H. Nuclear Ca2+ sparks and waves mediated by inositol 1,4,5-trisphosphate receptors in neonatal rat cardiomyocytes. Cell Calcium 2008; 43:165-74. [PMID: 17583790 PMCID: PMC2266086 DOI: 10.1016/j.ceca.2007.04.017] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Revised: 04/16/2007] [Accepted: 04/29/2007] [Indexed: 11/21/2022]
Abstract
Dynamic nuclear Ca(2+) signals play pivotal roles in diverse cellular functions including gene transcription, cell growth, differentiation, and apoptosis. Here we report a novel nuclear Ca(2+) regulatory mechanism mediated by inositol 1,4,5-trisphosphate receptors (IP(3)Rs) around the nucleus in developing cardiac myocytes. Activation of IP(3)Rs by alpha(1)-adrenergic receptor (alpha(1)AR) stimulation or by IP(3) application (in saponin-permeabilized cells) increases Ca(2+) spark frequency preferentially in the region around the nucleus in neonatal rat ventricular myocytes. A nuclear enrichment of IP(3)R distribution supports the higher responsiveness of Ca(2+) release in this particular region. Strikingly, we observed "nuclear Ca(2+)waves" that engulf the entire nucleus without spreading into the bulk cytosol. alpha(1)AR stimulation enhances the occurrence of nuclear Ca(2+) waves and confers them the ability to trigger cytosolic Ca(2+) waves via IP(3)R-dependent pathways. This finding accounts, at least partly, for a profound frequency-dependent modulation of global Ca(2+) oscillations during alpha(1)AR stimulation. Thus, IP(3)R-mediated Ca(2+) waves traveling in the nuclear region provide active, autonomous regulation of nuclear Ca(2+) signaling, which provides for not only the local signal transduction, but also a pacemaker to drive global Ca(2+) transient in the context of alpha(1)AR stimulation in developing cardiac myocytes.
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MESH Headings
- Adrenergic alpha-Agonists/pharmacology
- Animals
- Animals, Newborn
- Calcium Signaling/physiology
- Cell Membrane Permeability
- Inositol 1,4,5-Trisphosphate Receptors/drug effects
- Inositol 1,4,5-Trisphosphate Receptors/physiology
- Microscopy, Confocal
- Myocytes, Cardiac/physiology
- Nuclear Envelope/physiology
- Phenylephrine/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, Adrenergic, alpha-1/drug effects
- Receptors, Adrenergic, alpha-1/physiology
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Affiliation(s)
- Dali Luo
- Department of Pharmacology, School of Chemical Biology & Pharmaceutical Sciences, Capital Medical University, Beijing 100069, China.
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18
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Costa RR, Varanda WA. Intracellular calcium changes in mice Leydig cells are dependent on calcium entry through T-type calcium channels. J Physiol 2007; 585:339-49. [PMID: 17932157 DOI: 10.1113/jphysiol.2007.137950] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Luteinizing hormone (LH) regulates testosterone synthesis in Leydig cells by inducing an intracellular increase in cAMP concentration. LH also increases the intracellular calcium concentration ([Ca2+]i), dependent on the presence of Ca2+ in the extracellular medium ([Ca2+]e) for its effect. Despite these evidences, the identity of a pathway for calcium entry has remained elusive and the relationship between cAMP and [Ca2+]i has been questioned. Here we show that mice Leydig cells do have an inward Ca2+ current carried by T-type Ca2+ channels. In 10 mm [Ca2+]e, the currents start to be activated at -60 mV, reaching maximal amplitude of 1.8 +/- 0.3 pA pF(-1) at -20 mV. Currents were not modified by Ba2+ or Sr2+, were suppressed in Ca2+-free external solution, and were blocked by 100 microm nickel or 100 microm cadmium. The Ki for Ni2+ is 2.6 microm and concentrations of Cd2+ smaller than 50 microm have a very small effect on the currents. The calcium currents displayed a window centred at -40 mV. The half-voltage (V0.5) of activation is -30.3 mV, whereas the half-voltage steady-state inactivation is -51.1 mV. The deactivation time constant (taudeactivation) is around 3 ms at -35 mV. Confocal microscopy experiments with Fluo-3 loaded cells reveal that both LH and dibutyryl-cAMP (db-cAMP) increase [Ca2+]i. The db-cAMP induced calcium increase was dependent on Ca2+ influx since it was abolished by removal of extracellular Ca2+ and by 400 microm Ni2+. [Ca2+]i increases in regions close to the plasma membrane and in the cell nucleus. Similar effects are seen when Leydig cells are depolarized by withdrawing K+ from the extracellular solution. Altogether, our studies show that Ca2+ influx through T-type Ca2+ channels in the plasma membrane of Leydig cells plays a crucial role in the intracellular calcium concentration changes that follow binding of LH to its receptor.
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Affiliation(s)
- Roberta Ribeiro Costa
- Department of Physiology, School of Medicine of Ribeirão Preto/University of São Paulo, Av. Bandeirantes, 3900, 14049-900 Ribeirão Preto/São Paulo Brazil
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19
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Zima AV, Bare DJ, Mignery GA, Blatter LA. IP3-dependent nuclear Ca2+ signalling in the mammalian heart. J Physiol 2007; 584:601-11. [PMID: 17761776 PMCID: PMC2277156 DOI: 10.1113/jphysiol.2007.140731] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In cardiac myocytes the type-2 inositol 1,4,5-trisphosphate receptor (IP(3)R2) is the predominant isoform expressed. The IP(3)R2 channel is localized to the SR and to the nuclear envelope. We studied IP(3)-dependent nuclear Ca(2+) signals ([Ca(2+)](Nuc)) in permeabilized atrial myocytes and in isolated cardiac nuclei. In permeabilized myocytes IP(3) (20 microm) and the more potent IP(3)R agonist adenophostin (5 microm) caused an elevation of [Ca(2+)](Nuc). An IP(3)-dependent increase of [Ca(2+)](Nuc) was still observed after pretreatment with tetracaine to block Ca(2+) release from ryanodine receptors (RyRs), and the effect of IP(3) was partially reversed or prevented by the IP(3)R blockers heparin and 2-APB. Isolated nuclei were superfused with an internal solution containing the Ca(2+) indicator fluo-4 dextran. Exposure to IP(3) (10 microm) and adenophostin (0.5 microm) increased [Ca(2+)](Nuc) by 25 and 27%, respectively. [Ca(2+)](Nuc) increased to higher levels than [Ca(2+)](Cyt) immediately adjacent to the outer membrane of the nuclear envelope, suggesting that a significant portion of nuclear IP(3) receptors are facing the nucleoplasm. When nuclei were pretreated with heparin or 2-APB, IP(3) failed to increase [Ca(2+)](Nuc). Isolated nuclei were also loaded with the membrane-permeant low-affinity Ca(2+) probe fluo-5N AM which compartmentalized into the nuclear envelope. Exposure to IP(3) and adenophostin resulted in a decrease of the fluo-5N signal that could be prevented by heparin. Stimulation of IP(3)R caused depletion of the nuclear Ca(2+) stores by approximately 60% relative to the maximum depletion produced by the ionophores ionomycin and A23187. The fluo-5N fluorescence decrease was particularly pronounced in the nuclear periphery, suggesting that the nuclear envelope may represent the predominant nuclear Ca(2+) store. The data indicate that IP(3) can elicit Ca(2+) release from cardiac nuclei resulting in localized nuclear Ca(2+) signals.
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Affiliation(s)
- Aleksey V Zima
- Department of Physiology, Loyola University Chicago, Maywood, IL 60153, USA
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20
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Eder A, Bading H. Calcium signals can freely cross the nuclear envelope in hippocampal neurons: somatic calcium increases generate nuclear calcium transients. BMC Neurosci 2007; 8:57. [PMID: 17663775 PMCID: PMC1950097 DOI: 10.1186/1471-2202-8-57] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2007] [Accepted: 07/30/2007] [Indexed: 12/02/2022] Open
Abstract
Background In hippocampal neurons, nuclear calcium signaling is important for learning- and neuronal survival-associated gene expression. However, it is unknown whether calcium signals generated by neuronal activity at the cell membrane and propagated to the soma can unrestrictedly cross the nuclear envelope to invade the nucleus. The nuclear envelope, which allows ion transit via the nuclear pore complex, may represent a barrier for calcium and has been suggested to insulate the nucleus from activity-induced cytoplasmic calcium transients in some cell types. Results Using laser-assisted uncaging of caged calcium compounds in defined sub-cellular domains, we show here that the nuclear compartment border does not represent a barrier for calcium signals in hippocampal neurons. Although passive diffusion of molecules between the cytosol and the nucleoplasm may be modulated through changes in conformational state of the nuclear pore complex, we found no evidence for a gating mechanism for calcium movement across the nuclear border. Conclusion Thus, the nuclear envelope does not spatially restrict calcium transients to the somatic cytosol but allows calcium signals to freely enter the cell nucleus to trigger genomic events.
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Affiliation(s)
- Anja Eder
- Department of Neurobiology, Interdisciplinary Centre for Neurosciences, Im Neuenheimer Feld 364, 69120 Heidelberg, Germany
| | - Hilmar Bading
- Department of Neurobiology, Interdisciplinary Centre for Neurosciences, Im Neuenheimer Feld 364, 69120 Heidelberg, Germany
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21
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Chamero P, Manjarres IM, García-Verdugo JM, Villalobos C, Alonso MT, García-Sancho J. Nuclear calcium signaling by inositol trisphosphate in GH3 pituitary cells. Cell Calcium 2007; 43:205-14. [PMID: 17583789 DOI: 10.1016/j.ceca.2007.05.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2007] [Revised: 05/01/2007] [Accepted: 05/08/2007] [Indexed: 11/28/2022]
Abstract
It has been proposed that nuclear and cytosolic Ca(2+) ([Ca(2+)](N) and [Ca(2+)](C)) may be regulated independently. We address here the issue of whether inositol trisphosphate (IP(3)) can, bypassing changes of [Ca(2+)](C), produce direct release of Ca(2+) into the nucleoplasm. We have used targeted aequorins to selectively measure and compare the changes in [Ca(2+)](C) and [Ca(2+)](N) induced by IP(3) in GH(3) pituitary cells. Heparin, an IP(3) inhibitor that does not permeate the nuclear pores, abolished the [Ca(2+)](C) peaks but inhibited only partly the [Ca(2+)](N) peaks. The permeant inhibitor 2-aminoethoxy-diphenyl-borate (2-APB) blocked both responses. Removal of ATP also inhibited more strongly the [Ca(2+)](C) than [Ca(2+)](N) peak. The [Ca(2+)](N) and [Ca(2+)](C) responses differed also in their sensitivity to IP(3), the nuclear response showing higher affinity. Among IP(3) receptors, type 2 (IP(3)R2) has a higher affinity for IP(3) and is not inactivated by ATP removal. We find that IP(3)R2 immunoreactivity is present inside the nucleus whereas the other IP(3)R subtypes are detected only in the cytoplasm. The nuclear envelope (NE) of GH(3) cells showed deep invaginations into the nucleoplasm, with cytosol and cytoplasmic organella inside. These results indicate that GH(3) pituitary cells possess mechanisms able to produce selective increases of [Ca(2+)](N).
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Affiliation(s)
- Pablo Chamero
- Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid and Consejo Superior de Investigaciones Científicas (CSIC), Departamento de Fisiología y Bioquímica, Facultad de Medicina, E-47005 Valladolid, Spain
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22
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Rück A, Heckelsmiller K, Kaufmann R, Grossman N, Haseroth E, Akgün N. Light-induced Apoptosis Involves a Defined Sequence of Cytoplasmic and Nuclear Calcium Release in AlPcS4-photosensitized Rat Bladder RR 1022 Epithelial Cells¶. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2000)0720210liaiad2.0.co2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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23
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Alonso MT, Villalobos C, Chamero P, Alvarez J, García-Sancho J. Calcium microdomains in mitochondria and nucleus. Cell Calcium 2006; 40:513-25. [PMID: 17067669 DOI: 10.1016/j.ceca.2006.08.013] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Accepted: 08/23/2006] [Indexed: 10/24/2022]
Abstract
Endomembranes modify the progression of the cytosolic Ca(2+) wave and contribute to generate Ca(2+) microdomains, both in the cytosol and inside the own organella. The concentration of Ca(2+) in the cytosol ([Ca(2+)](C)), the mitochondria ([Ca(2+)](M)) and the nucleus ([Ca(2+)](N)) are similar at rest, but may become very different during cell activation. Mitochondria avidly take up Ca(2+) from the high [Ca(2+)](C) microdomains generated during cell activation near Ca(2+) channels of the plasma membrane and/or the endomembranes and prevent propagation of the high Ca(2+) signal to the bulk cytosol. This shaping of [Ca(2+)](C) signaling is essential for independent regulation of compartmentalized cell functions. On the other hand, a high [Ca(2+)](M) signal is generated selectively in the mitochondria close to the active areas, which tunes up respiration to the increased local needs. The progression of the [Ca(2+)](C) signal to the nucleus may be dampened by mitochondria, the nuclear envelope or higher buffering power inside the nucleoplasm. On the other hand, selective [Ca(2+)](N) signals could be generated by direct release of stored Ca(2+) into the nucleoplasm. Ca(2+) release could even be restricted to subnuclear domains. Putative Ca(2+) stores include the nuclear envelope, their invaginations inside the nucleoplasm (nucleoplasmic reticulum) and nuclear microvesicles. Inositol trisphosphate, cyclic ADP-ribose and nicotinic acid adenine dinucleotide phosphate have all been reported to produce release of Ca(2+) into the nucleoplasm, but contribution of these mechanisms under physiological conditions is still uncertain.
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Affiliation(s)
- María Teresa Alonso
- Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid and Consejo Superior de Investigaciones Científicas (CSIC), c/Sanz y Forés s/n, Valladolid, Spain
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24
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Rojas JD, Sennoune SR, Maiti D, Bakunts K, Reuveni M, Sanka SC, Martinez GM, Seftor EA, Meininger CJ, Wu G, Wesson DE, Hendrix MJC, Martínez-Zaguilán R. Vacuolar-type H+-ATPases at the plasma membrane regulate pH and cell migration in microvascular endothelial cells. Am J Physiol Heart Circ Physiol 2006; 291:H1147-57. [PMID: 16679513 DOI: 10.1152/ajpheart.00166.2006] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Microvascular endothelial cells involved in angiogenesis are exposed to an acidic environment that is not conducive for growth and survival. These cells must exhibit a dynamic intracellular (cytosolic) pH (pHcyt) regulatory mechanism to cope with acidosis, in addition to the ubiquitous Na+/H+exchanger and HCO3−-based H+-transporting systems. We hypothesize that the presence of plasmalemmal vacuolar-type proton ATPases (pmV-ATPases) allows microvascular endothelial cells to better cope with this acidic environment and that pmV-ATPases are required for cell migration. This study indicates that microvascular endothelial cells, which are more migratory than macrovascular endothelial cells, express pmV-ATPases. Spectral imaging microscopy indicates a more alkaline pHcytat the leading than at the lagging edge of microvascular endothelial cells. Treatment of microvascular endothelial cells with V-ATPase inhibitors decreases the proton fluxes via pmV-ATPases and cell migration. These data suggest that pmV-ATPases are essential for pHcytregulation and cell migration in microvascular endothelial cells.
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Affiliation(s)
- J D Rojas
- Department of Physiology, Texas Tech University Health Sciences Center, 3601 4th St., Lubbock, TX 79430-6551, USA
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25
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Lax A, Soler F, Fernández-Belda F. Cytoplasmic Ca2+ signals and cellular death by apoptosis in myocardiac H9c2 cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2006; 1763:937-47. [PMID: 16887208 DOI: 10.1016/j.bbamcr.2006.05.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2006] [Revised: 05/04/2006] [Accepted: 05/12/2006] [Indexed: 11/29/2022]
Abstract
The incubation of H9c2 cells with 10 microM thapsigargin (TG) was associated with the appearance of a two-component cytoplasmic Ca2+ peak. Experiments performed in a Ca2+-free medium indicated that both components came from intracellular sources. The first component of the signal corresponded to the discharge of the sarco-endoplasmic reticulum (SER) Ca2+ store. The appearance of the second component was prevented by cell preincubation with cyclosporin A (CsA) and gave rise to a clear and permanent depolarization of the mitochondrial inner membrane. These features were indication of a mitochondrial origin. The observed release of mitochondrial Ca2+ was related with opening of the permeability transition pore (PTP). The two-component cytoplasmic Ca2+ peak, i.e., treatment with 10 microM TG, as compared with the first component alone, i.e., treatment with 3 microM TG, was associated with a faster process of cellular death. In both cases, chromatin fragmentation and condensation at the nuclear periphery were observed. Other prominent apoptotic events such as loss of DNA content and cleavage of poly(ADP-ribose) polymerase (PARP) were also dependent on TG concentration and occurred in different time windows. PTP opening induced by 10 microM TG was responsible for the faster apoptotic death.
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Affiliation(s)
- Antonio Lax
- Departamento de Bioquímica y Biología Molecular A, Edificio de Veterinaria, Universidad de Murcia, Campus de Espinardo, 30071 Murcia, Spain
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26
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Isokawa M, Alger BE. Ryanodine Receptor Regulates Endogenous Cannabinoid Mobilization in the Hippocampus. J Neurophysiol 2006; 95:3001-11. [PMID: 16467427 DOI: 10.1152/jn.00975.2005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Endogenous cannabinoids (eCBs) are produced and mobilized in a cytosolic calcium ([Ca2+]i)–dependent manner, and they regulate excitatory and inhibitory neurotransmitter release by acting as retrograde messengers. An indirect but real-time bioassay for this process on GABAergic transmission is DSI (depolarization-induced suppression of inhibition). The magnitude of DSI correlates linearly with depolarization-induced increase of [Ca2+]ithat is thought to be initiated by Ca2+influx through voltage-gated Ca2+channels. However, the identity of Ca2+sources involved in eCB mobilization in DSI remains undetermined. Here we show that, in CA1 pyramidal cells, DSI-inducing depolarizing voltage steps caused Ca2+-induced Ca2+release (CICR) by activating the ryanodine receptor (RyR) Ca2+-release channel. CICR was reduced, and the remaining increase in [Ca2+]iwas less effective in generating DSI, when the RyR antagonists, ryanodine or ruthenium red, were applied intracellularly, or the Ca2+stores were depleted by the Ca2+-ATPase inhibitors, cyclopiazonic acid or thapsigargin. The CICR-dependent effects were most prominent in cultured or immature acute slices, but were also detectable in slices from adult tissue. Thus we suggest that voltage-gated Ca2+entry raises local [Ca2+]isufficiently to activate nearby RyRs and that the resulting CICR plays a critical role in initiating eCB mobilization. RyR may be a key molecule for the depolarization-induced production of eCBs that inhibit GABA release in the hippocampus.
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Affiliation(s)
- Masako Isokawa
- Department of Physiology, University of Maryland, Baltimore, Maryland, USA.
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Lax A, Soler F, Fernández-Belda F. Intracellular ca(2+) pools and fluxes in cardiac muscle-derived h9c2 cells. J Bioenerg Biomembr 2005; 37:249-59. [PMID: 16167180 DOI: 10.1007/s10863-005-6635-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Accepted: 05/09/2005] [Indexed: 01/27/2023]
Abstract
Relevant Ca(2+) pools and fluxes in H9c2 cells have been studied using fluorescent indicators and Ca(2+)-mobilizing agents. Vasopressin produced a cytoplasmic Ca(2+) peak with half-maximal effective concentration of 6 nM, whereas thapsigargin-induced Ca(2+) increase showed half-maximal effect at 3 nM. Depolarization of the mitochondrial inner membrane by protonophore was also associated with an increase in cytoplasmic Ca(2+). Ionomycin induced a small and sustained depolarization, while thapsigargin had a small but transient effect. The thapsigargin-sensitive Ca(2+) pool was also sensitive to ionomycin, whereas the protonophore-sensitive Ca(2+) pool was not. The vasopressin-induced cytoplasmic Ca(2+) signal, which caused a reversible discharge of the sarco-endoplasmic reticulum Ca(2+) pool, was sensed as a mitochondrial Ca(2+) peak but was unaffected by the permeability transition pore inhibitor cyclosporin A. The mitochondrial Ca(2+) peak was affected by cyclosporin A when the Ca(2+) signal was induced by irreversible discharge of the intracellular Ca(2+) pool, i.e., adding thapsigargin. These observations indicate that the mitochondria interpret the cytoplasmic Ca(2+) signals generated in the reticular store.
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Affiliation(s)
- Antonio Lax
- Departamento de Bioquímica y Biología Molecular A, Facultad de Veterinaria, Universidad de Murcia, Murcia, Spain
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28
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Sánchez-Armáss S, Sennoune SR, Maiti D, Ortega F, Martínez-Zaguilán R. Spectral imaging microscopy demonstrates cytoplasmic pH oscillations in glial cells. Am J Physiol Cell Physiol 2005; 290:C524-38. [PMID: 16135543 DOI: 10.1152/ajpcell.00290.2005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glial cells exhibit distinct cellular domains, somata, and filopodia. Thus the cytoplasmic pH (pH(cyt)) and/or the behavior of the fluorescent ion indicator might be different in these cellular domains because of distinct microenvironments. To address these issues, we loaded C6 glial cells with carboxyseminaphthorhodafluor (SNARF)-1 and evaluated pH(cyt) using spectral imaging microscopy. This approach allowed us to study pH(cyt) in discrete cellular domains with high temporal, spatial, and spectral resolution. Because there are differences in the cell microenvironment that may affect the behavior of SNARF-1, we performed in situ titrations in discrete cellular regions of single cells encompassing the somata and filopodia. The in situ titration parameters apparent acid-base dissociation constant (pK'(a)), maximum ratio (R(max)), and minimum ratio (R(min)) had a mean coefficient of variation approximately six times greater than those measured in vitro. Therefore, the individual in situ titration parameters obtained from specific cellular domains were used to estimate the pH(cyt) of each region. These studies indicated that glial cells exhibit pH(cyt) heterogeneities and pH(cyt) oscillations in both the absence and presence of physiological HCO(3)(-). The amplitude and frequency of the pH(cyt) oscillations were affected by alkalosis, by acidosis, and by inhibitors of the ubiquitous Na(+)/H(+) exchanger- and HCO(3)(-)-based H(+)-transporting mechanisms. Optical imaging approaches used in conjunction with BCECF as a pH probe corroborated the existence of pH(cyt) oscillations in glial cells.
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Affiliation(s)
- Sergio Sánchez-Armáss
- Departamento de Fisiología y Farmacología, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
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29
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Koopman WJH, Willems PHGM, Oosterhof A, van Kuppevelt TH, Gielen SCAM. Amplitude modulation of nuclear Ca2+ signals in human skeletal myotubes: A possible role for nuclear Ca2+ buffering. Cell Calcium 2005; 38:141-52. [PMID: 16054687 DOI: 10.1016/j.ceca.2005.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2004] [Revised: 05/17/2005] [Accepted: 06/02/2005] [Indexed: 11/20/2022]
Abstract
Video-rate confocal microscopy of Indo-1-loaded human skeletal myotubes was used to assess the relationship between the changes in sarcoplasmic ([Ca(2+)](S)) and nuclear ([Ca(2+)](N)) Ca(2+) concentration during low- and high-frequency electrostimulation. A single stimulus of 10 ms duration transiently increased [Ca(2+)] in both compartments with the same time of onset. Rate and amplitude of the [Ca(2+)] rise were significantly lower in the nucleus (4.0- and 2.5-fold, respectively). Similarly, [Ca(2+)](N) decayed more slowly than [Ca(2+)](S) (mono-exponential time constants of 6.1 and 2.5 s, respectively). After return of [Ca(2+)] to the prestimulatory level, a train of 10 stimuli was applied at a frequency of 1 Hz. The amplitude of the first [Ca(2+)](S) transient was 25% lower than that of the preceding single transient. Thereafter, [Ca(2+)](S) increased stepwise to a maximum that equalled that of the single transient. Similarly, the amplitude of the first [Ca(2+)](N) transient was 20% lower than that of the preceding single transient. In contrast to [Ca(2+)](S), [Ca(2+)](N) then increased to a maximum that was 2.3-fold higher than that of the single transient and equalled that of [Ca(2+)](S). In the nucleus, and to a lesser extent in the sarcoplasm, [Ca(2+)] decreased faster at the end of the stimulus train than after the preceding single stimulus (time constants of 3.3 and 2.1 s, respectively). To gain insight into the molecular principles underlying the shaping of the nuclear Ca(2+) signal, a 3-D mathematical model was constructed. Intriguingly, quantitative modelling required the inclusion of a satiable nuclear Ca(2+) buffer. Alterations in the concentration of this putative buffer had dramatic effects on the kinetics of the nuclear Ca(2+) signal. This finding unveils a possible mechanism by which the skeletal muscle can adapt to changes in physiological demand.
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Affiliation(s)
- Werner J H Koopman
- Department of 160 Biochemistry NCMLS, Radboud University Nijmegen Medical Center, The Netherlands
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30
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Quesada I, Martin F, Roche E, Soria B. Nutrients induce different Ca(2+) signals in cytosol and nucleus in pancreatic beta-cells. Diabetes 2004; 53 Suppl 1:S92-5. [PMID: 14749272 DOI: 10.2337/diabetes.53.2007.s92] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Specific activation of Ca(2+)-dependent functions is achieved by the particular dynamics and local restriction of Ca(2+) signals. It has been shown that changes in amplitude, duration, or frequency of Ca(2+) signals modulate gene transcription. Thus, Ca(2+) variations should be finely controlled within the nucleus. Although a variety of mechanisms in the nuclear membrane have been demonstrated to regulate nuclear Ca(2+), the existence of an autonomous Ca(2+) homeostasis within the nucleus is still questioned. In the pancreatic beta-cell, besides their effect on insulin secretion, Ca(2+) messages generated by nutrients also exert their action on gene expression. However, the dynamics of these Ca(2+) signals in relation to nuclear function have been explored little in islet cells. In the current study, Ca(2+) changes both in the nucleoplasm and in the cytosol of INS-1 and pancreatic beta-cells were monitored using spot confocal microscopy. We show that nutrients trigger Ca(2+) signals of higher amplitude in the nucleus than in the cytosol. These amplitude-modulated Ca(2+) signals transmitted to the nucleus might play an important role in the control of gene expression in the pancreatic beta-cell.
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Affiliation(s)
- Ivan Quesada
- Department of Bioengineering, University of Washington, Seattle, Washington, USA
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31
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Bkaily G, Choufani S, Sader S, Jacques D, d'Orléans-Juste P, Nader M, Kurban G, Kamal M. Activation of sarcolemma and nuclear membranes ET-1 receptors regulates transcellular calcium levels in heart and vascular smooth muscle cells. Can J Physiol Pharmacol 2003; 81:654-62. [PMID: 12839276 DOI: 10.1139/y03-020] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The use of an ET-1 fluorescent probe in human heart and vascular smooth muscle cells showed that ET-1 receptors are present at both the sarcolemma and nuclear envelope membranes. The use of immunofluorescence studies showed that the ETA receptor was mainly present at the sarcolemma and cytosolic levels. However, the ETB receptor was present at the sarcolemma and the cytosol, as well as the nuclear envelope membranes and the nucleoplasm. In addition, ET-1 immunoreactivity was seen in the cytosol and the nucleus. Using Ca2+ fluorescent probes such as Fluo-3, Indo 1, and yellow cameleon, as well as confocal microscopy three-dimensional image measurement technique, stimulation of ET-1 receptors at the sarcolemma membranes induced an increase of cytosolic and nuclear free Ca2+ levels. This effect of extracellular ET-1 was blocked by removal of extracellular calcium. Direct stimulation of ET-1 receptors at the nuclear envelope membranes also induced an increase of intranuclear free Ca2+ level. Our results suggest that the stimulation of sarcolemmal Ca2+ influx by ET-1 seems to be due to the activation of ETA and ETB receptors. However, the increase of nucleoplasmic Ca2+ levels by cytosolic ET-1 seems to be mediated via the activation of ETB receptors. Activation of nuclear membranes ETB receptors seems to prevent nuclear Ca2+ overload and may protect the cell from apoptosis.
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MESH Headings
- Calcium/metabolism
- Cells, Cultured
- Dose-Response Relationship, Drug
- Endothelin-1/metabolism
- Endothelin-1/pharmacology
- Humans
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Nuclear Envelope/drug effects
- Nuclear Envelope/metabolism
- Receptors, Endothelin/agonists
- Receptors, Endothelin/metabolism
- Sarcolemma/drug effects
- Sarcolemma/metabolism
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Affiliation(s)
- Ghassan Bkaily
- Department of Anatomy and Cell Biology, Faculty of Medicine, University of Sherbrooke, Sherbrooke, QC J1H 5N4, Canada.
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32
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Bkaily G, Sleiman S, Stephan J, Asselin C, Choufani S, Kamal M, Jacques D, Gobeil F, D'Orléans-Juste P. Angiotensin II AT1 receptor internalization, translocation and de novo synthesis modulate cytosolic and nuclear calcium in human vascular smooth muscle cells. Can J Physiol Pharmacol 2003; 81:274-87. [PMID: 12733826 DOI: 10.1139/y03-007] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study was designed to verify if human (h) Angiotensin II (Ang II) type-1 receptor (hAT1R) undergoes internalization, nuclear translocation, and de novo synthesis in primary culture of human aortic vascular smooth muscle cells (hVSMCs) and if overexpression of this receptor modulates sustained free cytosolic ([Ca]c) and nuclear ([Ca]n) calcium. 3-dimensional (3-D) confocal microscopy was used to monitor free intracellular Ca2+ and hAT1R-green fluorescence protein (GFP) fusion protein in cultured hVSMCs. Immunofluorescence studies showed the presence of hAT1R and the absence of hAT2R in normal hVSMCs. Using 3-D imaging technique, hAT1 receptors were localized at the sarcolemma and in the cytosolic and nuclear compartments. In native as well as in normal hAT1R or hAT1R-GFP overexpressing hVSMCs, Ang II (10(-9) and 10(-4) M) induced internalization and nuclear translocation of this type of receptor. The internalization of hAT1Rs is mediated via clathrin-coated pits and vesicles pathway. This phenomenon of trancellular trafficking of receptors was associated with an increase of hAT1R. The Ang II induced increase of hAT1R density was prevented by the protein synthesis inhibitor cycloheximide. Overexpression of hAT1R and hAT1R-GFP decreased both basal cytosolic and nuclear Ca2+. In normal hVSMCs and low hAT1R-GFP overexpressing hVSMCs, Ang II (10(-15) to 10(-4) M) induced a dose-dependent sustained increase of [Ca]c and [Ca]n with an EC50 near 5 x 10(-11) and 5 x 10(-9) M, respectively. Our results suggest that hAT1Rs are the predominant type of Ang II receptors in aortic hVSMCs and are present in the sarcolemma, the cytosolic and the nuclear compartments. Ang II rapidly induces hAT1R internalization, nuclear translocation, as well as nuclear de novo synthesis of this receptor. The hAT1R overexpression in hVSMCs modulates sustained [Ca]c and [Ca]n.
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MESH Headings
- Aniline Compounds
- Aorta/cytology
- Aorta/metabolism
- Blotting, Western
- Calcium/metabolism
- Cell Nucleus/metabolism
- Cells, Cultured
- Fluorescent Antibody Technique
- Fluorescent Dyes
- Green Fluorescent Proteins
- Humans
- Luminescent Proteins/genetics
- Microscopy, Confocal
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/metabolism
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
- Recombinant Fusion Proteins/metabolism
- Sarcolemma/physiology
- Transfection
- Translocation, Genetic
- Xanthenes
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Affiliation(s)
- G Bkaily
- Department of Anatomy & Cell Biology, and CIHR Group in Immunocardiovascular Interaction, Faculty of Medicine, University of Sherbrooke, Sherbrooke, QC J1H 5N4, Canada.
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33
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Abrenica B, Pierce GN, Gilchrist JSC. Nucleoplasmic calcium regulation in rabbit aortic vascular smooth muscle cells. Can J Physiol Pharmacol 2003; 81:301-10. [PMID: 12733828 DOI: 10.1139/y03-005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study, we investigated whether nucleoplasmic free Ca2+ in aortic vascular smooth muscle cells (VSMCs) might be independently regulated from cytosolic free Ca2+. Understanding mechanisms and pathways responsible for this regulation is especially relevant given the role of a numerous intranuclear Ca2+-sensitive proteins in transcriptional regulation, apoptosis and cell division. The question of an independent regulatory mechanism remains largely unsettled because the previous use of intensitometric fluorophores (e.g., Fluo-3) has been criticized on technical grounds. To circumvent the potential problem of fluorescence artifact, we utilized confocal laser scanning microscopy to image intracellular Ca2+ movements with the ratiometric fluorophore Indo-1. In cultured rabbit VSMCs, we found sarcoplasmic reticulum (SR) Ca2+ ATPase (SERCA) pumps and ryanodine receptor (RyR) Ca2+ channel proteins to be discretely arranged within a perinuclear locus, as determined by fluorescent staining patterns of BODIPY FL thapsigargin and BODIPY FL-X Ry. When intracellular Ca2+ stores were mobilized by addition of thapsigargin (5 microM) and activatory concentrations of ryanodine (1 microM), Indo-1 ratiometric signals were largely restricted to the nucleoplasm. Cytosolic signals, by comparison, were relatively small and even then its spatial distribution was largely perinuclear rather homogeneous. These observations indicate perinuclear RyR and SERCA proteins are intimately involved in regulating VSMC nucleoplasmic Ca2+ concentrations. We also observed a similar pattern of largely nucleoplasmic Ca2+ mobilization upon exposure of cells to the immunosuppressant drug FK506 (tacrolimus), which binds to the RyR-associated immunophillin-binding proteins FKBP12 and FKBP12.6. However, initial FK506-induced nucleoplasmic Ca2+ mobilization was followed by marked reduction of Indo-1 signal intensity close to pretreatment levels. This suggested FK506 exerts both activatory and inhibitory effects upon RyR channels. The latter was reinforced by observed effects of FK506 to only reduce nucleoplasmic Indo-1 signal intensity when added following pretreatment with both activatory and inhibitory concentrations of ryanodine. These latter observations raise the possibility that VSMC nuclei represent an important sink of intracellular Ca2+ and may help explain vasodilatory actions of FK506 observed by others.
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Affiliation(s)
- Bernard Abrenica
- Department of Oral Biology, Division of Stroke and Vascular Disease, University of Manitoba, Winnipeg, MB R2H 2A6, Canada
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34
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Payet MD, Bilodeau L, Breault L, Fournier A, Yon L, Vaudry H, Gallo-Payet N. PAC1 receptor activation by PACAP-38 mediates Ca2+ release from a cAMP-dependent pool in human fetal adrenal gland chromaffin cells. J Biol Chem 2003; 278:1663-70. [PMID: 12429744 DOI: 10.1074/jbc.m206470200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previous studies have shown that human fetal adrenal gland from 17- to 20-week-old fetuses expressed pituitary adenylate cyclase-activating polypeptide (PACAP) receptors, which were localized on chromaffin cells. The aim of the present study was to identify PACAP receptor isoforms and to determine whether PACAP can affect intracellular calcium concentration ([Ca(2+)](i)) and catecholamine secretion. Using primary cultures and specific stimulation of chromaffin cells, we demonstrate that PACAP-38 induced an increase in [Ca(2+)](i) that was blocked by PACAP (6-38), was independent of external Ca(2+), and originated from thapsigargin-insensitive internal stores. The PACAP-triggered Ca(2+) increase was not affected by inhibition of PLC beta (preincubation with U-73122) or by pretreatment of cells with Xestospongin C, indicating that the inositol 1,4,5-triphosphate-sensitive stores were not mobilized. However, forskolin (FSK), which raises cytosolic cAMP, induced an increase in Ca(2+) similar to that recorded with PACAP-38. Blockage of PKA by H-89 or (R(p))-cAMPS suppressed both PACAP-38 and FSK calcium responses. The effect of PACAP-38 was also abolished by emptying the caffeine/ryanodine-sensitive Ca(2+) stores. Furthermore, treatment of cells with orthovanadate (100 microm) impaired Ca(2+) reloading of PACAP-sensitive stores indicating that PACAP-38 can mobilize Ca(2+) from secretory vesicles. Moreover, PACAP induced catecholamine secretion by chromaffin cells. It is concluded that PACAP-38, through the PAC(1) receptor, acts as a neurotransmitter in human fetal chromaffin cells inducing catecholamine secretion, through nonclassical, recently described, ryanodine/caffeine-sensitive pools, involving a cAMP- and PKA-dependent phosphorylation mechanism.
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Affiliation(s)
- Marcel D Payet
- Department of Physiology and Biophysics, Faculty of Medicine, University of Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada.
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35
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Wamhoff BR, Bowles DK, Dietz NJ, Hu Q, Sturek M. Exercise training attenuates coronary smooth muscle phenotypic modulation and nuclear Ca2+ signaling. Am J Physiol Heart Circ Physiol 2002; 283:H2397-410. [PMID: 12388302 DOI: 10.1152/ajpheart.00371.2001] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Physical inactivity is an independent risk factor for coronary heart disease, yet the mechanism(s) of exercise-related cardioprotection remains unknown. We tested the hypothesis that coronary smooth muscle after exercise training would have decreased mitogen-induced phenotypic modulation and enhanced regulation of nuclear Ca(2+). Yucatan swine were endurance exercise trained (EX) on a treadmill for 16-20 wk. EX reduced endothelin-1-induced DNA content by 40% compared with sedentary (SED) swine (P < 0.01). EX decreased single cell peak endothelin-1-induced cytosolic Ca(2+) responses compared with SED by 16% and peak nuclear Ca(2+) responses by 33% (P < 0.05), as determined by confocal microscopy. On the basis of these results, we hypothesized that sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) and intracellular Ca(2+) stores in native smooth muscle are spatially localized to dissociate cytosolic Ca(2+) and nuclear Ca(2+). Subcellular localization of SERCA in living and fixed cells revealed a distribution of SERCA near the sarcolemma and on the nuclear envelope. These results show that EX enhances nuclear Ca(2+) regulation, possibly via SERCA, which may be one mechanism by which coronary smooth muscle cells from EX are less responsive to mitogen-induced phenotypic modulation.
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Affiliation(s)
- B R Wamhoff
- Department of Physiology, School of Medicine, University of Missouri, Columbia 65212, USA
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36
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Colombaioni L, Colombini L, Garcia-Gil M. Role of mitochondria in serum withdrawal-induced apoptosis of immortalized neuronal precursors. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2002; 134:93-102. [PMID: 11947940 DOI: 10.1016/s0165-3806(01)00326-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The intracellular mechanisms controlling apoptosis in immature neurons are still largely unknown. Taking immortalized hippocampal neuronal precursors (mouse cell line HN9.10e) as a model, we have analyzed the cellular events associated to apoptosis induced by serum deprivation. We observed translocation of Bax from cytosol to mitochondria after 1 h of serum withdrawal followed, 2 h later, by cytochrome c release from mitochondria. These events occurred without mitochondrial membrane potential loss nor mitochondrial calcium raise. As calcium is implicated in several cell death pathways, we analyzed intracellular calcium levels after longer periods of serum deprivation. After 6 h, an increase of cytosolic Ca2+ was detected in HN9.10e cells loaded with the Ca2+ indicator Fluo3-AM. This increase of calcium preceded morphological signs of apoptosis such as cell shrinkage and nuclear fragmentation, and was followed by a more pronounced raise that persisted until the terminal phases of the apoptotic process. Cells serum-deprived for 4 h and then grown in complete medium for 20 h fully recovered viability. Summarizing, in HN9.10e cells, calcium deregulation occurs in the late phases of apoptosis; earlier events involve translocation of Bax, release of cytochrome c, and maintenance of mitochondrial functionality. This allows an enlargement of the temporal window in which commitment to death is reversible.
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Affiliation(s)
- Laura Colombaioni
- Institute of Neurophysiology of CNR, Italian National Research Council, Area della Ricerca CNR, Via G. Moruzzi, 1, Pisa, Italy.
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37
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Takahashi S, Hitomi J, Satoh YI, Takahashi T, Asakura H, Ushiki T. Fine structure of the mouse portal vein in relation to its peristaltic movement. ARCHIVES OF HISTOLOGY AND CYTOLOGY 2002; 65:71-82. [PMID: 12002612 DOI: 10.1679/aohc.65.71] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The hepatic portal vein has been known to make a spontaneous peristaltic movement in some mammals, including the mouse and rat. To investigate the fine structure of the portal vein in relation to its physiological characteristics, we observed the mouse portal vein by using various histological techniques including conventional light microscopy, videomicroscopy, transmission and scanning electron microscopy, and real-time confocal laser scanning microscopy. The mouse hepatic portal vein was provided with a spiral fold which was produced by the inner layer, i.e. the endothelium and smooth muscles of the wall protruding into the lumen. Longitudinal smooth muscle cells spanned the interval of the fold, like a spirally arranged palisade around the vessel wall. The longitudinal muscle fibers ended at the spiral fold, being partly connected with a network of irregularly shaped smooth muscle cells. This network, hitherto unknown, was recognized to be restricted to the fold in distribution and characterized by numerous gap junctions connecting the muscle cells. Real-time confocal laser scanning microscopy using a Ca2+ sensitive fluorescent dye revealed that a transient and periodic increase in Ca2+ concentration occurred in the longitudinal smooth muscle cells and was transmitted spirally from the intestinal to the hepatic side. These findings indicate that, during the peristaltic movement, the contraction of smooth muscle cells is transmitted along the longitudinal smooth muscles of the portal vein wall toward the liver, presumably controlled by the network of the irregularly-shaped smooth muscle cells in the fold of the portal vein. Light microscopic observation in some specimens indicated an occurrence of cardiac muscle cells outside the smooth muscle layer. Restricted to the site of the porta hepatis in distribution, their involvement in the peristaltic contraction of the portal vein seemed unlikely.
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Affiliation(s)
- Sumio Takahashi
- Department of Cellular Function, Graduate School of Medical and Dental Sciences, Niigata University, Japan
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38
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Le Poul E, Hisada S, Mizuguchi Y, Dupriez VJ, Burgeon E, Detheux M. Adaptation of aequorin functional assay to high throughput screening. JOURNAL OF BIOMOLECULAR SCREENING 2002; 7:57-65. [PMID: 11897056 DOI: 10.1177/108705710200700108] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
AequoScreen, a cellular aequorin-based functional assay, has been optimized for luminescent high-throughput screening (HTS) of G protein-coupled receptor (GPCRs). AequoScreen is a homogeneous assay in which the cells are loaded with the apoaequorin cofactor coelenterazine, diluted in assay buffer, and injected into plates containing the samples to be tested. A flash of light is emitted following the calcium increase resulting from the activation of the GPCR by the sample. Here we have validated a new plate reader, the Hamamatsu Photonics FDSS6000, for HTS in 96- and 384-well plates with CHO-K1 cells stably coexpressing mitochondrial apoaequorin and different GPCRs (AequoScreen cell lines). The acquisition time, plate type, and cell number per well have been optimized to obtain concentration-response curves with 4000 cells/well in 384-well plates and a high signal:background ratio. The FDSS6000 and AequoScreen cell lines allow reading of twenty 96- or 384-well plates in 1 h with Z' values of 0.71 and 0.78, respectively. These results bring new insights to functional assays, and therefore reinforce the interest in aequorin-based assays in a HTS environment.
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39
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Thomas D, Mason MJ, Mahaut-Smith MP. Depolarisation-evoked Ca2+ waves in the non-excitable rat megakaryocyte. J Physiol 2001; 537:371-8. [PMID: 11731571 PMCID: PMC2278975 DOI: 10.1111/j.1469-7793.2001.00371.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
1. A combination of patch clamp, confocal microscopy and immunohistochemistry was used to examine the spatial properties of Ca2+ signalling in the rat megakaryocyte, a non-excitable cell type in which membrane potential can markedly modulate agonist-evoked Ca2+ release. 2. Intracellular calcium ion concentration ([Ca2+]i) increases, stimulated by both ADP and depolarisation, frequently originated from a peripheral locus and spread as a wave throughout the cell. Spatially restricted [Ca2+]i increases, consistent with elementary Ca2+ release events, were occasionally observed prior to ADP-evoked waves. 3. ADP- and depolarisation-evoked Ca2+ waves travelled approximately twice as fast around the periphery of the cell compared to across its radius, leading to a curvilinear wavefront. There was no significant difference between wave velocities generated by the two stimuli. 4. Immunohistochemical staining of type III IP3 receptors, the endoplasmic reticulum-specific protein GRP78/BiP and calreticulin indicated a major peripheral location of the cellular Ca2+ stores which probably accounts for the accelerated wave velocity at the cell periphery. 5. These data demonstrate that [Ca2+]i increases, stimulated by depolarisation or the agonist ADP, have indistinguishable spatial properties, providing evidence that similar underlying mechanisms are responsible for their generation.
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Affiliation(s)
- D Thomas
- Department of Physiology, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK
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40
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Chawla S, Bading H. CREB/CBP and SRE-interacting transcriptional regulators are fast on-off switches: duration of calcium transients specifies the magnitude of transcriptional responses. J Neurochem 2001; 79:849-58. [PMID: 11723177 DOI: 10.1046/j.1471-4159.2001.00645.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Transient increases in the intracellular calcium concentration, which are associated with electrical activation of neurones, control synapse-to-nucleus communication. Calcium signals differ in time and space but it is unclear exactly how this translates into stimulus-specific gene expression. Analysis of transcription induced by calcium transients with defined durations revealed that the evoked genomic responses, unlike those following neurotrophin exposure, are not all-or-none but graded events. The CRE-binding protein CREB, its coactivator CREB-binding protein (CBP), and SRE-interacting transcriptional regulators are fast on-off switches: their activities are induced by short-lasting calcium signals, remain active for the duration of the signal and are rapidly shut-off after calcium concentrations have returned to basal levels. CREB is switched on by a fast, nuclear calmodulin (CaM) kinase-dependent mechanism that mediates CREB phosphorylation on serine 133 within 30 s of calcium entry. The second calcium-activated route to CREB involves the MAP kinase/extracellular signal-regulated kinase (ERK1/2) cascade. This pathway can be triggered by brief, 30-60 s calcium transients. ERK1/2 activity peaks several minutes after calcium entry and can outlast the calcium transient. The shut-off of CREB and ERK1/2 involves rapid dephosphorylation of their activator sites. These properties of transcription factors and their regulating kinases and phosphatases provide a mechanism through which the duration of calcium signals specifies the magnitude of the transcriptional response. The decoding of temporal features of calcium transients is likely to contribute to impulse-specific gene expression.
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Affiliation(s)
- S Chawla
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge, UK
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41
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Lee CH, Poburko D, Sahota P, Sandhu J, Ruehlmann DO, van Breemen C. The mechanism of phenylephrine-mediated [Ca(2+)](i) oscillations underlying tonic contraction in the rabbit inferior vena cava. J Physiol 2001; 534:641-50. [PMID: 11483697 PMCID: PMC2278727 DOI: 10.1111/j.1469-7793.2001.t01-1-00641.x] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
1. We characterized the mechanisms in vascular smooth muscle cells (VSMCs) that produce asynchronous, wave-like Ca(2+) oscillations in response to phenylephrine (PE). Confocal imaging was used to observe [Ca(2+)](i) in individual VSMCs of intact inferior vena cava (IVC) from rabbits. 2. It was found that the Ca(2+) waves were initiated by Ca(2+) release from the sarcoplasmic reticulum (SR) via inositol 1,4,5-trisphosphate-sensitive SR Ca(2+) release channels (IP(3)R channels) and that refilling of the SR Ca(2+) store through the sarcoplasmic-endoplasmic reticulum Ca(2+)-ATPase (SERCA) was required for maintained generation of the repetitive Ca(2+) waves. 3. Blockade of L-type voltage-gated Ca(2+) channels (L-type VGCCs) with nifedipine reduced the frequency of PE-stimulated [Ca(2+)](i) oscillations, while additional blockade of receptor-operated channels/store-operated channels (ROCs/SOCs) with SKF96365 abolished the remaining oscillations. Parallel force measurements showed that nifedipine inhibited PE-induced tonic contraction by 27 % while SKF96365 abolished it. This indicates that stimulated Ca(2+) entry refills the SR to support the recurrent waves of SR Ca(2+) release and that both L-type VGCCs and ROCs/SOCs contribute to this process. 4. Application of the Na(+)-Ca(2+) exchanger (NCX) inhibitors 2',4'-dichlorobenzamil (forward- and reverse-mode inhibitor) and KB-R7943 (reverse-mode inhibitor) completely abolished the nifedipine-resistant component of [Ca(2+)](i) oscillations and markedly reduced PE-induced tone. 5. Thus, we conclude that each Ca(2+) wave depends on initial SR Ca(2+) release via IP(3)R channels followed by SR Ca(2+) refilling through SERCA. Na(+) entry through ROCs/SOCs facilitates Ca(2+) entry through the NCX operating in the reverse mode, which refills the SR and maintains PE-induced [Ca(2+)](i) oscillations. In addition some Ca(2+) entry through L-type VGCCs and ROCs/SOCs serves to modulate the frequency of the oscillations and the magnitude of force development.
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Affiliation(s)
- C H Lee
- Vancouver Vascular Biology Research Center, University of British Columbia, St Paul's Hospital, Room 292, 1081 Burrard Street, Vancouver, BC, Canada V6Z 1Y6
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Abstract
In many neurons, Ca(2+) signaling depends on efflux of Ca(2+) from intracellular stores into the cytoplasm via caffeine-sensitive ryanodine receptors (RyRs) of the endoplasmic reticulum. We have used high-speed confocal microscopy to image depolarization- and caffeine-evoked increases in cytoplasmic Ca(2+) levels in individual cultured frog sympathetic neurons. Although caffeine-evoked Ca(2+) wave fronts propagated throughout the cell, in most cells the initial Ca(2+) release was from one or more discrete sites that were several micrometers wide and located at the cell edge, even in Ca(2+)-free external solution. During cell-wide cytoplasmic [Ca(2+)] oscillations triggered by continual caffeine application, the initial Ca(2+) release that began each Ca(2+) peak was from the same subcellular site or sites. The Ca(2+) wave fronts propagated with constant amplitude; the spread was mostly via calcium-induced calcium release. Propagation was faster around the cell periphery than radially inward. Local Ca(2+) levels within the cell body could increase or decrease independently of neighboring regions, suggesting independent action of spatially separate Ca(2+) stores. Confocal imaging of fluorescent analogs of ryanodine and thapsigargin, and of MitoTracker, showed potential structural correlates to the patterns of Ca(2+) release and propagation. High densities of RyRs were found in a ring around the cell periphery, mitochondria in a broader ring just inside the RyRs, and sarco-endoplasmic reticulum Ca(2+) ATPase pumps in hot spots at the cell edge. Discrete sites at the cell edge primed to release Ca(2+) from intracellular stores might preferentially convert Ca(2+) influx through a local area of plasma membrane into a cell-wide Ca(2+) increase.
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43
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Massaeli H, Hurtado C, Austria JA, Pierce GN. Increase in nuclear calcium in smooth muscle cells exposed to oxidized low density lipoprotein. Free Radic Res 2001; 34:9-16. [PMID: 11234999 DOI: 10.1080/10715760100300021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Vascular smooth muscle cells respond with an increase in intracellular Ca2+ within seconds after exposure to oxidized low density lipoprotein (oxLDL). This has been suggested to represent a signaling response that may have implications for gene expression. If so, oxLDL may induce increases in nuclear Ca2+ in smooth muscle cells in response to oxLDL. Aortic smooth muscle cells were exposed to 100 microg/ml oxLDL. Large, rapid increases in [Ca2+]i were observed using fluo-3 as an indicator dye to detect intracellular Ca2+ on the stage of a confocal microscope. This was also confirmed using ratiometric imaging of indo signals. These elevations appeared to be localized to the nuclear region of the cell. DNA staining of the cells confirmed its localization to the nuclear/perinuclear region of the cell. Our data demonstrate that oxLDL induces a nuclear localized elevation in Ca2+i that may have important implications for nuclear function.
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MESH Headings
- Adenosine Diphosphate/metabolism
- Adenosine Diphosphate/pharmacology
- Adenosine Triphosphate/metabolism
- Adenosine Triphosphate/pharmacology
- Aniline Compounds/chemistry
- Aniline Compounds/metabolism
- Animals
- Aorta/cytology
- Calcium/metabolism
- Cell Nucleus/metabolism
- Cells, Cultured
- Dose-Response Relationship, Drug
- Fluorescent Dyes/chemistry
- Fluorescent Dyes/metabolism
- Indoles/chemistry
- Indoles/metabolism
- Iron/metabolism
- Iron/pharmacology
- Lipoproteins, LDL/metabolism
- Lipoproteins, LDL/pharmacology
- Microscopy, Confocal
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Rabbits
- Xanthenes/chemistry
- Xanthenes/metabolism
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Affiliation(s)
- H Massaeli
- Division of Stroke & Vascular Disease, St. Boniface General Hospital Research Centre, and University of Manitoba, Winnipeg, Canada
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Rück A, Heckelsmiller K, Kaufmann R, Grossman N, Haseroth E, Akgün N. Light-induced apoptosis involves a defined sequence of cytoplasmic and nuclear calcium release in AlPcS4-photosensitized rat bladder RR 1022 epithelial cells. Photochem Photobiol 2000; 72:210-6. [PMID: 10946575 DOI: 10.1562/0031-8655(2000)072<0210:liaiad>2.0.co;2] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Oxidative stress induced by light activation of photosensitizers is regarded to have a role in triggering cell death pathways during photodynamic therapy (PDT). Reactive oxygen species have been proposed to act as signal transduction molecules activating downstream reactions that lead to apoptosis. Mainly debated is the cooperating role of other signaling systems like calcium or pH. The present work contributes to this discussion by studying PDT effects in cell cultures of rat bladder epithelial cells for the hydrophilic tetrasulfonated aluminum phthalocyanine (AlPcS4). Cells were coincubated with the photosensitizer and the calcium-sensitive probe Fluo-3. The light-induced reactions were analyzed with a confocal laser scanning microscope. The dynamics of the process during light activation was observed with subcellular resolution. A transient calcium elevation during the irradiation process was detected, especially in the cell's nuclei, followed by a more sustained increase. The evaluation of the energy-dose-dependent phototoxicity after an incubation time with the photosensitizer of 1 and 24 h, showed enhanced phototoxicity when the drug was present for 24 h. Surprisingly, stimulation of cell proliferation was observed at very low light doses (at 0.2 J/cm2) when the drug was incubated for 24 h (cell viability 160%). Induction of apoptosis could be observed after irradiation with fluences between 1 and 3 J/cm2. Apoptotic cells were identified with fluorescein isothiocyanate-labeled Annexin V, which binds to phosphatidylserine after its translocation to the outer plasma membrane. In the presence of the antioxidant pyrrolidinedithiocarbamate the transient calcium elevation was totally inhibited, as was the subsequent translocation of PS. In contrast, N-acetyl-L-cysteine did not suppress the transient calcium increase. Our data might be consistent with calcium regulated processes during AlPcS4-PDT and the involvement of oxygen radicals.
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Affiliation(s)
- A Rück
- Institute for Laser Technologies in Medicine and Metrology, Ulm, Germany.
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46
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Abrenica B, Gilchrist JS. Nucleoplasmic Ca(2+)loading is regulated by mobilization of perinuclear Ca(2+). Cell Calcium 2000; 28:127-36. [PMID: 10970769 DOI: 10.1054/ceca.2000.0137] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Regulation of nucleoplasmic calcium (Ca(2+)) concentration may occur by the mobilization of perinuclear luminal Ca(2+)pools involving specific Ca(2+)pumps and channels of both inner and outer perinuclear membranes. To determine the role of perinuclear luminal Ca(2+), we examined freshly cultured 10 day-old embryonic chick ventricular cardiomyocytes. We obtained evidence suggesting the existence of the molecular machinery required for the bi-directional Ca(2+)fluxes using confocal imaging techniques. Embryonic cardiomyocytes were probed with antibodies specific for ryanodine-sensitive Ca(2+)channels (RyR2), sarco/endoplasmic reticulum Ca(2+)ATPase (SERCA2)-pumps, and fluorescent BODIPY derivatives of ryanodine and thapsigargin. Using immunocytochemistry techniques, confocal imaging showed the presence of RyR2 Ca(2+)channels and SERCA2-pumps highly localized to regions surrounding the nucleus, referable to the nuclear envelope. Results obtained from Fluo-3, AM loaded ionomycin-perforated embryonic cardiomyocytes demonstrated that gradual increases of extranuclear Ca(2+)from 100 to 1600 nM Ca(2+)was localized to the nucleus. SERCA2-pump inhibitors thapsigargin and cyclopiazonic acid showed a concentration-dependent inhibition of nuclear Ca(2+)loading. Furthermore, ryanodine demonstrated a biphasic concentration-dependence upon active nuclear Ca(2+)loading. The concomitant addition of thapsigargin or cyclopiazonic acid with ryanodine at inhibitory concentrations caused an significant increase in nuclear Ca(2+)loading at low concentrations of extranuclear added Ca(2+). Our results show that the perinuclear lumen in embryonic chick ventricular cardiomyocytes is capable of autonomously regulating nucleoplasmic Ca(2+)fluxes.
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Affiliation(s)
- B Abrenica
- Department of Oral Biology and Physiology, Division of Stroke and Vascular Disease, University of Manitoba, Winnipeg, Manitoba, Canada
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Monteith GR. Seeing is believing: recent trends in the measurement of Ca2+ in subcellular domains and intracellular organelles. Immunol Cell Biol 2000; 78:403-7. [PMID: 10947865 DOI: 10.1046/j.1440-1711.2000.00920.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The role of Ca2+ in the regulation of the cell cycle has been investigated mostly in studies assessing global cytosolic free Ca2+. Recent studies, however, have used unique techniques to assess Ca2+ in subcellular organelles, such as mitochondria, and in discrete regions of the cytoplasm. These studies have used advanced fluorescence digital imaging techniques and Ca2+-sensitive fluorescence probes, and/or targeting of Ca2+-sensitive proteins to intracellular organelles. The present review describes the results of some of these studies and the techniques used. The novel techniques used to measure Ca2+ in microdomains and intracellular organelles are likely to be of great use in future investigations assessing Ca2+ homeostasis during the cell cycle.
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Affiliation(s)
- G R Monteith
- School of Pharmacy, The University of Queensland, St Lucia, Australia.
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Mori S, Saino T, Satoh Y. Effect of low temperatures on compound 48/80-induced intracellular Ca2+ changes and exocytosis of rat peritoneal mast cells. ARCHIVES OF HISTOLOGY AND CYTOLOGY 2000; 63:261-70. [PMID: 10989938 DOI: 10.1679/aohc.63.261] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
It has been well documented that compound 48/80-induced exocytosis of mast cells is accompanied by changes in intracellular Ca2+ concentration ([Ca2+]i) showing a biphasic pattern: an initial phase which constitutes an abrupt increase, followed by a plateau phase. The former is caused by Ca2+ release from intracellular Ca2+ stores, and the latter is the result of secondary Ca2+ influx. Low temperatures lead to the inhibition of exocytosis, but the precise mechanism remains unclear. The present study aims to reveal whether [Ca2+]i changes are affected by the environmental temperature. To this end, we developed a novel imaging method to record [Ca2+]i changes and exocytotic processes simultaneously. Rat peritoneal mast cells were loaded by Indo-1/AM or Fluo-3/AM for measuring [Ca2+]i, and the exocytosed granule matrices were stained by sulforhodamine-B. Cells were stimulated by compound 48/80, and [Ca2+]i changes and exocytosis were recorded by means of a real-time confocal microscope. At 37 degrees C, [Ca2+]i changes in stimulated mast cells showed a sustained plateau phase. Granule discharge was observed at the cell surface, and, in addition, most of the intracellular granule matrices were involved in compound exocytosis. The granule discharge and compound exocytosis proceeded over a period of a few minutes. At 4 degrees C, the plateau phase of [Ca2+]i changes declined rapidly, although the initial phase was not suppressed. Granule discharge occurred at the cell surface, but compound exocytosis ceased within a few minutes. These findings indicate that a low temperature inhibits compound exocytosis which can be caused by Ca2+ influx. The present imaging method represents a powerful tool for investigating the stimulus-secretion coupling of mast cells.
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Affiliation(s)
- S Mori
- Department of Cell Biology and Neuroanatomy, Iwate Medical University, Morioka, Japan
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Ward CW, Schneider MF, Castillo D, Protasi F, Wang Y, Chen SR, Allen PD. Expression of ryanodine receptor RyR3 produces Ca2+ sparks in dyspedic myotubes. J Physiol 2000; 525 Pt 1:91-103. [PMID: 10811728 PMCID: PMC2269930 DOI: 10.1111/j.1469-7793.2000.t01-2-00091.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Discrete, localized elevations of myoplasmic [Ca2+], Ca2+ 'sparks', were readily detected using the fluorescent Ca2+ indicator fluo-3 and laser scanning confocal microscopy in 'dyspedic' 1B5 myotubes, i.e. myotubes which do not express ryanodine receptors (RyRs), transduced with virions containing cDNA for RyR type 3 that were saponin permeabilized to allow dye entry. Ca2+ sparks were never observed in non-transduced RyR null myotubes. The spatial locations of sparks observed in permeabilized myotubes roughly corresponded to regions of RyR protein expression in the same myotube as detected after subsequent fixation and antibody staining. Permeabilized RyR3-transduced myotubes exhibited similar punctate peripheral RyR3 protein immunohistochemical patterns as myotubes fixed before permeabilization indicating that permeabilization did not affect the structural organization of the triad. Ca2+ sparks, recorded in line scan mode, in permeabilized myotubes expressing RyR3 exhibited mean amplitudes (change in fluorescence/mean fluorescence, DeltaF/F: 1.20 +/- 0.04) and temporal rise times (10-90%; 6.31 +/- 0.12 ms) similar to those of sparks recorded in permeabilized frog skeletal muscle fibres (0.98 +/- 0.01; 6.11 +/- 0.07, respectively) using the same confocal system. Spatial extent and temporal duration of the Ca2+ sparks were approximately 40% larger in the RyR3-expressing myotube cultures than in frog fibres. Ca2+ sparks recorded in line scan mode often occurred repetitively at the same spatial location in RyR3-expressing myotubes. Such repetitive events were highly reproducible in amplitude and spatio-temporal properties, as previously observed for repetitive mode sparks in frog skeletal muscle. Ca2+ sparks recorded in xy mode were frequently compressed in the y (slower scan) direction compared to the x direction. This asymmetry was reproduced assuming spatially symmetric events having the time course of Ca2+ sparks recorded in line scan (xt) mode. These expression studies demonstrate that the presence of RyR3 is sufficient for the production of Ca2+ sparks in a skeletal muscle system lacking the expression of any other RyR isoform.
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Affiliation(s)
- C W Ward
- Department of Biochemistry and Molecular Biology, University of Calgary, Alberta, Canada
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50
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Fast VG, Ideker RE. Simultaneous optical mapping of transmembrane potential and intracellular calcium in myocyte cultures. J Cardiovasc Electrophysiol 2000; 11:547-56. [PMID: 10826934 DOI: 10.1111/j.1540-8167.2000.tb00008.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Fast spatially resolved measurements of transmembrane potential (Vm) and intracellular calcium (Ca(i)2+) are important for studying mechanisms of arrhythmias and defibrillation. The goals of this work were (1) to develop an optical technique for simultaneous multisite optical recordings of Vm and Ca(i)2+, and (2) to determine the relationship between Vm and Ca(i)2+ during normal impulse propagation in myocyte cultures. METHODS AND RESULTS Monolayers of neonatal rat myocytes were stained with fluorescent dye RH-237 (Vm) and Fluo-3AM (Ca(i)2+). Both dyes were excited at the same wavelength range. The emitted fluorescence was optically separated into components corresponding to changes in Vm and Ca(i)2+ and measured using two 16 x 16 photodiode arrays at a spatial resolution of up to 27.5 microm per diode and sampling rate of 2.5 kHz. The optical setup was adjusted so that there was no optical cross-talk between the two types of measurements, which was validated in experiments involving staining with either RH-237 or Fluo-3. The amplitude of Fluo-3 signals rapidly decreased during experiments due to dye leakage. Dye leakage was substantially reduced by application of 1 mM probenecid, a blocker of organic anion transport, which had no effect on action potential duration and only minor effect on conduction velocity. In double-stained preparations, during regular pacing Ca(i)2+ transients had a rise time of 14.2 +/- 2 msec, and they followed Vm upstrokes with a delay of 5.3 +/- 1 msec (n = 9). Durations of Vm and Ca(i)2+ transients determined at 50% level of signal recovery were 54.6 +/- 10 msec and 136 +/- 8 msec, respectively. Application of 2 microM nifedipine reduced the amplitude and duration of Ca(i)2+ transients without significantly affecting conduction velocity. CONCLUSION The results demonstrate feasibility of simultaneous optical recordings of Vm and Ca(i)2+ transients with high spatial and temporal resolution.
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Affiliation(s)
- V G Fast
- Department of Biomedical Engineering, University of Alabama at Birmingham, 35294, USA.
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