101
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Richards M, Lomas O, Jalink K, Ford KL, Vaughan-Jones RD, Lefkimmiatis K, Swietach P. Intracellular tortuosity underlies slow cAMP diffusion in adult ventricular myocytes. Cardiovasc Res 2016; 110:395-407. [PMID: 27089919 PMCID: PMC4872880 DOI: 10.1093/cvr/cvw080] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 04/11/2016] [Indexed: 12/20/2022] Open
Abstract
Aims 3′,5′-Cyclic adenosine monophosphate (cAMP) signals in the heart are often confined to concentration microdomains shaped by cAMP diffusion and enzymatic degradation. While the importance of phosphodiesterases (degradative enzymes) in sculpting cAMP microdomains is well established in cardiomyocytes, less is known about cAMP diffusivity (DcAMP) and factors affecting it. Many earlier studies have reported fast diffusivity, which argues against sharply defined microdomains. Methods and results [cAMP] dynamics in the cytoplasm of adult rat ventricular myocytes were imaged using a fourth generation genetically encoded FRET-based sensor. The [cAMP]-response to the addition and removal of isoproterenol (β-adrenoceptor agonist) quantified the rates of cAMP synthesis and degradation. To obtain a read out of DcAMP, a stable [cAMP] gradient was generated using a microfluidic device which delivered agonist to one half of the myocyte only. After accounting for phosphodiesterase activity, DcAMP was calculated to be 32 µm2/s; an order of magnitude lower than in water. Diffusivity was independent of the amount of cAMP produced. Saturating cAMP-binding sites with the analogue 6-Bnz-cAMP did not accelerate DcAMP, arguing against a role of buffering in restricting cAMP mobility. cAMP diffused at a comparable rate to chemically unrelated but similar sized molecules, arguing for a common physical cause of restricted diffusivity. Lower mitochondrial density and order in neonatal cardiac myocytes allowed for faster diffusion, demonstrating the importance of mitochondria as physical barriers to cAMP mobility. Conclusion In adult cardiac myocytes, tortuosity due to physical barriers, notably mitochondria, restricts cAMP diffusion to levels that are more compatible with microdomain signalling.
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Affiliation(s)
- Mark Richards
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Parks Road, Oxford OX1 3PT, UK
| | - Oliver Lomas
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Parks Road, Oxford OX1 3PT, UK
| | - Kees Jalink
- Division of Cell Biology, Netherlands Cancer Institute, 1066 CX Amsterdam, Netherlands
| | - Kerrie L Ford
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Parks Road, Oxford OX1 3PT, UK
| | - Richard D Vaughan-Jones
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Parks Road, Oxford OX1 3PT, UK
| | - Konstantinos Lefkimmiatis
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Parks Road, Oxford OX1 3PT, UK BHF Centre of Research Excellence, Oxford
| | - Pawel Swietach
- Burdon Sanderson Cardiac Science Centre, Department of Physiology, Anatomy and Genetics, Parks Road, Oxford OX1 3PT, UK
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102
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Abstract
Ca(2+)entry into the cell via store-operated Ca(2+)release-activated Ca(2+)(CRAC) channels triggers diverse signaling cascades that affect cellular processes like cell growth, gene regulation, secretion, and cell death. These store-operated Ca(2+)channels open after depletion of intracellular Ca(2+)stores, and their main features are fully reconstituted by the two molecular key players: the stromal interaction molecule (STIM) and Orai. STIM represents an endoplasmic reticulum-located Ca(2+)sensor, while Orai forms a highly Ca(2+)-selective ion channel in the plasma membrane. Functional as well as mutagenesis studies together with structural insights about STIM and Orai proteins provide a molecular picture of the interplay of these two key players in the CRAC signaling cascade. This review focuses on the main experimental advances in the understanding of the STIM1-Orai choreography, thereby establishing a portrait of key mechanistic steps in the CRAC channel signaling cascade. The focus is on the activation of the STIM proteins, the subsequent coupling of STIM1 to Orai1, and the consequent structural rearrangements that gate the Orai channels into the open state to allow Ca(2+)permeation into the cell.
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Affiliation(s)
- Isabella Derler
- Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria; and
| | - Isaac Jardin
- Department of Physiology, University of Extremadura, Cáceres, Spain
| | - Christoph Romanin
- Institute of Biophysics, Johannes Kepler University of Linz, Linz, Austria; and
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103
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Stanisz H, Vultur A, Herlyn M, Roesch A, Bogeski I. The role of Orai-STIM calcium channels in melanocytes and melanoma. J Physiol 2016; 594:2825-35. [PMID: 26864956 DOI: 10.1113/jp271141] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 02/04/2016] [Indexed: 12/12/2022] Open
Abstract
Calcium signalling within normal and cancer cells regulates many important cellular functions such as migration, proliferation, differentiation and cytokine secretion. Store operated Ca(2+) entry (SOCE) via the Ca(2+) release activated Ca(2+) (CRAC) channels, which are composed of the plasma membrane based Orai channels and the endoplasmic reticulum stromal interaction molecules (STIMs), is a major Ca(2+) entry route in many cell types. Orai and STIM have been implicated in the growth and metastasis of multiple cancers; however, while their involvement in cancer is presently indisputable, how Orai-STIM-controlled Ca(2+) signals affect malignant transformation, tumour growth and invasion is not fully understood. Here, we review recent studies linking Orai-STIM Ca(2+) channels with cancer, with a particular focus on melanoma. We highlight and examine key molecular players and the signalling pathways regulated by Orai and STIM in normal and malignant cells, we expose discrepancies, and we reflect on the potential of Orai-STIMs as anticancer drug targets. Finally, we discuss the functional implications of future discoveries in the field of Ca(2+) signalling.
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Affiliation(s)
- Hedwig Stanisz
- Department of Dermatology, Venerology and Allergology, University Hospital of the Saarland, Homburg, Germany
| | - Adina Vultur
- Program of Cellular and Molecular Oncogenesis, Melanoma Research Center, The Wistar Institute, Philadelphia, PA, USA
| | - Meenhard Herlyn
- Program of Cellular and Molecular Oncogenesis, Melanoma Research Center, The Wistar Institute, Philadelphia, PA, USA
| | - Alexander Roesch
- Department of Dermatology, University Hospital Essen, Hufelandstraße 55, D-45122, Essen, Germany
| | - Ivan Bogeski
- Department of Biophysics, CIPMM, School of Medicine, Saarland University, 66421, Homburg, Germany
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104
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Calcium signalling in pancreatic stellate cells: Mechanisms and potential roles. Cell Calcium 2016; 59:140-4. [DOI: 10.1016/j.ceca.2016.02.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 02/05/2016] [Indexed: 11/22/2022]
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105
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Jang SI, Ong HL, Liu X, Alevizos I, Ambudkar IS. Up-regulation of Store-operated Ca2+ Entry and Nuclear Factor of Activated T Cells Promote the Acinar Phenotype of the Primary Human Salivary Gland Cells. J Biol Chem 2016; 291:8709-20. [PMID: 26903518 DOI: 10.1074/jbc.m115.701607] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Indexed: 01/12/2023] Open
Abstract
The signaling pathways involved in the generation and maintenance of exocrine gland acinar cells have not yet been established. Primary human salivary gland epithelial cells, derived from salivary gland biopsies, acquired an acinar-like phenotype when the [Ca(2+)] in the serum-free medium (keratinocyte growth medium, KGM) was increased from 0.05 mm (KGM-L) to 1.2 mm (KGM-H). Here we examined the mechanism underlying this Ca(2+)-dependent generation of the acinar cell phenotype. Compared with cells in KGM-L, those in KGM-H display enhancement of Orai1, STIM1, STIM2, and nuclear factor of activated T cells 1 (NFAT1) expression together with an increase in store-operated Ca(2+) entry (SOCE), SOCE-dependent nuclear translocation of pGFP-NFAT1, and NFAT-dependent but not NFκB-dependent gene expression. Importantly, AQP5, an acinar-specific protein critical for function, is up-regulated in KGM-H via SOCE/NFAT-dependent gene expression. We identified critical NFAT binding motifs in the AQP5 promoter that are involved in Ca(2+)-dependent up-regulation of AQP5. These important findings reveal that the Ca(2+)-induced switch of salivary epithelial cells to an acinar-like phenotype involves remodeling of SOCE and NFAT signaling, which together control the expression of proteins critically relevant for acinar cell function. Our data provide a novel strategy for generating and maintaining acinar cells in culture.
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Affiliation(s)
- Shyh-Ing Jang
- Sjögren's Syndrome and Salivary Gland Dysfunction Unit, Molecular Physiology and Therapeutics Branch, NIDCR/National Institutes of Health, Bethesda, Maryland 20892
| | | | - Xibao Liu
- From the Secretory and Physiology Section and
| | - Ilias Alevizos
- Sjögren's Syndrome and Salivary Gland Dysfunction Unit, Molecular Physiology and Therapeutics Branch, NIDCR/National Institutes of Health, Bethesda, Maryland 20892
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106
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Frischauf I, Zayats V, Deix M, Hochreiter A, Jardin I, Muik M, Lackner B, Svobodová B, Pammer T, Litviňuková M, Sridhar AA, Derler I, Bogeski I, Romanin C, Ettrich RH, Schindl R. A calcium-accumulating region, CAR, in the channel Orai1 enhances Ca(2+) permeation and SOCE-induced gene transcription. Sci Signal 2015; 8:ra131. [PMID: 26696631 DOI: 10.1126/scisignal.aab1901] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The Ca(2+) release-activated Ca(2+) channel mediates Ca(2+) influx in a plethora of cell types, thereby controlling diverse cellular functions. The channel complex is composed of stromal interaction molecule 1 (STIM1), an endoplasmic reticulum Ca(2+)-sensing protein, and Orai1, a plasma membrane Ca(2+) channel. Channels composed of STIM1 and Orai1 mediate Ca(2+) influx even at low extracellular Ca(2+) concentrations. We investigated whether the activity of Orai1 adapted to different environmental Ca(2+) concentrations. We used homology modeling and molecular dynamics simulations to predict the presence of an extracellular Ca(2+)-accumulating region (CAR) at the pore entrance of Orai1. Furthermore, simulations of Orai1 proteins with mutations in CAR, along with live-cell experiments, or simulations and electrophysiological recordings of the channel with transient, electrostatic loop3 interacting with loop1 (the site of CAR) determined that CAR enhanced Ca(2+) permeation most efficiently at low external Ca(2+) concentrations. Consistent with these results, cells expressing Orai1 CAR mutants exhibited impaired gene expression stimulated by the Ca(2+)-activated transcription factor nuclear factor of activated T cells (NFAT). We propose that the Orai1 channel architecture with a close proximity of CAR to the selectivity filter, which enables Ca(2+)-selective ion permeation, enhances the local extracellular Ca(2+) concentration to maintain Ca(2+)-dependent gene regulation even in environments with relatively low Ca(2+)concentrations.
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Affiliation(s)
- Irene Frischauf
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Vasilina Zayats
- Center for Nanobiology and Structural Biology, Institute of Microbiology, Academy of Sciences of the Czech Republic, Zamek 136, CZ-373 33, Nove Hrady, Czech Republic.,Faculty of Sciences, University of South Bohemia, Zamek 136, CZ-373 33, Nove Hrady, Czech Republic
| | - Michael Deix
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Anna Hochreiter
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria.,Institute for Experimental and Clinical Cell Therapy, Paracelsus Medical University, A-5020 Salzburg, Austria
| | - Isaac Jardin
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Martin Muik
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Barbara Lackner
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Barbora Svobodová
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria.,Institute for Biophysics of Medical University Graz, A-8010, Graz, Austria
| | - Teresa Pammer
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Monika Litviňuková
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Amrutha Arumbakam Sridhar
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Isabella Derler
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Ivan Bogeski
- Department of Biophysics, School of Medicine, University of Saarland, D-66421 Homburg, Germany
| | - Christoph Romanin
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Rüdiger H Ettrich
- Center for Nanobiology and Structural Biology, Institute of Microbiology, Academy of Sciences of the Czech Republic, Zamek 136, CZ-373 33, Nove Hrady, Czech Republic.,Faculty of Sciences, University of South Bohemia, Zamek 136, CZ-373 33, Nove Hrady, Czech Republic
| | - Rainer Schindl
- Institute of Biophysics, JKU Life Science Center, Johannes Kepler University Linz, Gruberstrasse 40, 4020 Linz, Austria
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107
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Wang K, Zhang DL, Long B, An T, Zhang J, Zhou LY, Liu CY, Li PF. NFAT4-dependent miR-324-5p regulates mitochondrial morphology and cardiomyocyte cell death by targeting Mtfr1. Cell Death Dis 2015; 6:e2007. [PMID: 26633713 PMCID: PMC4720883 DOI: 10.1038/cddis.2015.348] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 10/10/2015] [Accepted: 11/02/2015] [Indexed: 12/19/2022]
Abstract
Emerging evidence suggest that the abnormal mitochondrial fission participates in pathogenesis of cardiac diseases, including myocardial infarction and heart failure. However, the molecular components regulating mitochondrial network in heart remain largely unidentified. Here we report that NFAT4, miR-324-5p and mitochondrial fission regulator 1 (Mtfr1) function in one signaling axis that regulates mitochondrial morphology and cardiomyocyte cell death. Knocking down Mtfr1 suppresses mitochondrial fission, apoptosis and myocardial infarction. Mtfr1 is a direct target of miR-324-5p, and miR-324-5p attenuates mitochondrial fission, cardiomyocyte apoptosis and myocardial infarction by suppressing Mtfr1 translation. Finally, we show that transcription factor NFAT4 inhibits miR-324-5p expression. Knockdown of NFAT4 suppresses mitochondrial fission and protects cardiomyocyte from apoptosis and myocardial infarction. Our study defines the NFAT4/ miR-324-5p/Mtfr1 axis, which participates in the regulation of mitochondrial fission and cardiomyocyte apoptosis, and suggests potential new treatment avenues for cardiac diseases.
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Affiliation(s)
- K Wang
- Center for Developmental Cardiology, Institute for Translational Medicine, College of Medicine, Qingdao University, Qingdao, China
| | - D-L Zhang
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiaotong University, Shanghai, China
| | - B Long
- Laboratory of Molecular Medicine, Central Research Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - T An
- State Key Laboratory of Cardiovascular Disease, Heart Failure Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
| | - J Zhang
- State Key Laboratory of Cardiovascular Disease, Heart Failure Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China
| | - L-Y Zhou
- Center for Developmental Cardiology, Institute for Translational Medicine, College of Medicine, Qingdao University, Qingdao, China
| | - C-Y Liu
- Center for Developmental Cardiology, Institute for Translational Medicine, College of Medicine, Qingdao University, Qingdao, China
| | - P-F Li
- Center for Developmental Cardiology, Institute for Translational Medicine, College of Medicine, Qingdao University, Qingdao, China
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108
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STIM1 dimers undergo unimolecular coupling to activate Orai1 channels. Nat Commun 2015; 6:8395. [PMID: 26399906 PMCID: PMC4598629 DOI: 10.1038/ncomms9395] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 08/18/2015] [Indexed: 11/08/2022] Open
Abstract
The endoplasmic reticulum (ER) Ca(2+) sensor, STIM1, becomes activated when ER-stored Ca(2+) is depleted and translocates into ER-plasma membrane junctions where it tethers and activates Orai1 Ca(2+) entry channels. The dimeric STIM1 protein contains a small STIM-Orai-activating region (SOAR)--the minimal sequence sufficient to activate Orai1 channels. Since SOAR itself is a dimer, we constructed SOAR concatemer-dimers and introduced mutations at F394, which is critical for Orai1 coupling and activation. The F394H mutation in both SOAR monomers completely blocks dimer function, but F394H introduced in only one of the dimeric SOAR monomers has no effect on Orai1 binding or activation. This reveals an unexpected unimolecular coupling between STIM1 and Orai1 and argues against recent evidence suggesting dimeric interaction between STIM1 and two adjacent Orai1 channel subunits. The model predicts that STIM1 dimers may be involved in crosslinking between Orai1 channels with implications for the kinetics and localization of Orai1 channel opening.
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109
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Lohse MJ, Hofmann KP. Spatial and Temporal Aspects of Signaling by G-Protein-Coupled Receptors. Mol Pharmacol 2015; 88:572-8. [PMID: 26184590 DOI: 10.1124/mol.115.100248] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 07/10/2015] [Indexed: 01/07/2023] Open
Abstract
Signaling by G-protein-coupled receptors is often considered a uniform process, whereby a homogeneously activated proportion of randomly distributed receptors are activated under equilibrium conditions and produce homogeneous, steady-state intracellular signals. While this may be the case in some biologic systems, the example of rhodopsin with its strictly local single-quantum mode of function shows that homogeneity in space and time cannot be a general property of G-protein-coupled systems. Recent work has now revealed many other systems where such simplicity does not prevail. Instead, a plethora of mechanisms allows much more complex patterns of receptor activation and signaling: different mechanisms of protein-protein interaction; temporal changes under nonequilibrium conditions; localized receptor activation; and localized second messenger generation and degradation-all of which shape receptor-generated signals and permit the creation of multiple signal types. Here, we review the evidence for such pleiotropic receptor signaling in space and time.
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Affiliation(s)
- Martin J Lohse
- Institute of Pharmacology and Toxicology, Rudolf Virchow Center, and Comprehensive Heart Failure Center, University of Würzburg, Würzburg, Germany (M.J.L.); Institut für Medizinische Physik und Biophysik (CC2), Charité-Universitätsmedizin Berlin, Berlin, Germany (K.P.H.); and Zentrum für Biophysik und Bioinformatik, Humboldt-Universität zu Berlin, Berlin, Germany (K.P.H.)
| | - Klaus Peter Hofmann
- Institute of Pharmacology and Toxicology, Rudolf Virchow Center, and Comprehensive Heart Failure Center, University of Würzburg, Würzburg, Germany (M.J.L.); Institut für Medizinische Physik und Biophysik (CC2), Charité-Universitätsmedizin Berlin, Berlin, Germany (K.P.H.); and Zentrum für Biophysik und Bioinformatik, Humboldt-Universität zu Berlin, Berlin, Germany (K.P.H.)
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110
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Abstract
Adrenergic signaling, in particular signaling in the sympathetic nervous system, is a prime example of the control of an essential physiological system. It has served as a model system both for the control of mediator release and for receptor signaling and regulation. This review covers the historical development of the field and then addresses issues that represent key fields of ongoing research: the mechanisms and kinetics of receptor activation, temporal patterns of downstream signaling and signal bias, receptor mobility and aggregation, and signal compartmentation and specificity. The available evidence suggests that adrenergic signaling may involve complex spatiotemporal patterns, which give texture to the signaling process and may contain additional biological information.
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Affiliation(s)
- Martin J Lohse
- Institute of Pharmacology and Toxicology, University of Würzburg, Versbacher Str. 9, 97078, Würzburg, Germany.
- Rudolf Virchow Center, University of Würzburg, Versbacher Str. 9, 97078, Würzburg, Germany.
- Comprehensive Heart Failure Center, University of Würzburg, Versbacher Str. 9, 97078, Würzburg, Germany.
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111
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Abstract
In this issue of Molecular Cell, Kar and Parekh (2015) reveal the remarkable intricacy and accuracy of Ca(2+) signals in differentially controlling the function of closely related transcription factors.
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Affiliation(s)
- Yandong Zhou
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, PA 17033, USA
| | - Mohamed Trebak
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, PA 17033, USA
| | - Donald L Gill
- Department of Cellular and Molecular Physiology, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, PA 17033, USA.
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