51
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Behringer EJ. Calcium and electrical signaling in arterial endothelial tubes: New insights into cellular physiology and cardiovascular function. Microcirculation 2018; 24. [PMID: 27801542 DOI: 10.1111/micc.12328] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 10/25/2016] [Indexed: 12/23/2022]
Abstract
The integral role of the endothelium during the coordination of blood flow throughout vascular resistance networks has been recognized for several decades now. Early examination of the distinct anatomy and physiology of the endothelium as a signaling conduit along the vascular wall has prompted development and application of an intact endothelial "tube" study model isolated from rodent skeletal muscle resistance arteries. Vasodilatory signals such as increased endothelial cell (EC) Ca2+ ([Ca2+ ]i ) and hyperpolarization take place in single ECs while shared between electrically coupled ECs through gap junctions up to distances of millimeters (≥2 mm). The small- and intermediate-conductance Ca2+ activated K+ (SKCa /IKCa or KCa 2.3/KCa 3.1) channels function at the interface of Ca2+ signaling and hyperpolarization; a bidirectional relationship whereby increases in [Ca2+ ]i activate SKCa /IKCa channels to produce hyperpolarization and vice versa. Further, the spatial domain of hyperpolarization among electrically coupled ECs can be finely tuned via incremental modulation of SKCa /IKCa channels to balance the strength of local and conducted electrical signals underlying vasomotor activity. Multifunctional properties of the voltage-insensitive SKCa /IKCa channels of resistance artery endothelium may be employed for therapy during the aging process and development of vascular disease.
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Affiliation(s)
- Erik J Behringer
- Department of Basic Sciences, Loma Linda University, Loma Linda, CA, USA
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52
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Servin-Vences MR, Richardson J, Lewin GR, Poole K. Mechanoelectrical transduction in chondrocytes. Clin Exp Pharmacol Physiol 2018; 45:481-488. [PMID: 29359488 DOI: 10.1111/1440-1681.12917] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Revised: 12/20/2017] [Accepted: 01/09/2018] [Indexed: 11/29/2022]
Abstract
Cartilage tissue lines the joints of mammals, helping to lubricate joint movement and distribute mechanical loads. This tissue is comprised of isolated cells known as chondrocytes which are embedded in an extracellular matrix. Chondrocytes produce and maintain the cartilage by sensing and responding to changing mechanical loads. Mechanosensitive ion channels have been implicated in chondrocyte mechanotransduction and recent studies have shown that both PIEZO1 and TRPV4 can be activated by mechanical stimuli in these cells. The 2 channels mediate separate but overlapping mechanoelectrical transduction pathways, PIEZO1 in response to stretch and substrate deflections and TRPV4 in response to substrate deflections alone. These distinct pathways of mechanoelectrical transduction suggest a mechanism by which chondrocytes can distinguish between different stimuli that arise in their complex mechanical environment.
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Affiliation(s)
| | - Jessica Richardson
- School of Medical Sciences, EMBL Australia node for Single Molecule Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Gary R Lewin
- Max Delbruck Center for Molecular Medicine, Department Neuroscience, Berlin-Buch, Germany
| | - Kate Poole
- School of Medical Sciences, EMBL Australia node for Single Molecule Sciences, University of New South Wales, Sydney, NSW, Australia
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53
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Phuong TTT, Redmon SN, Yarishkin O, Winter JM, Li DY, Križaj D. Calcium influx through TRPV4 channels modulates the adherens contacts between retinal microvascular endothelial cells. J Physiol 2017; 595:6869-6885. [PMID: 28949006 DOI: 10.1113/jp275052] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 09/18/2017] [Indexed: 12/17/2022] Open
Abstract
KEY POINTS Endothelial cells employ transient receptor potential isoform 4 (TRPV4) channels to sense ambient mechanical and chemical stimuli. In retinal microvascular endothelial cells, TRPV4 channels regulate calcium homeostasis, cytoskeletal signalling and the organization of adherens junctional contacts. Intracellular calcium increases induced by TRPV4 agonists include a significant contribution from calcium release from internal stores. Activation of TRPV4 channels regulates retinal endothelial barriers in vitro and in vivo. TRPV4 sensing may provide a feedback mechanism between sensing shear flow and eicosanoid modulators, vascular permeability and contractility at the inner retinal endothelial barrier. ABSTRACT The identity of microvascular endothelial (MVE) mechanosensors that sense blood flow in response to mechanical and chemical stimuli and regulate vascular permeability in the retina is unknown. Using immunohistochemistry, calcium imaging, electrophysiology, impedance measurements and vascular permeability assays, we show that the transient receptor potential isoform 4 (TRPV4) plays a major role in Ca2+ /cation signalling, cytoskeletal remodelling and barrier function in retinal microvasculature in vitro and in vivo. Human retinal MVE cells (HrMVECs) predominantly expressed Trpv1 and Trpv4 transcripts, and TRPV4 was broadly localized to the plasma membrane of cultured cells and intact blood vessels in the inner retina. Treatment with the selective TRPV4 agonist GSK1016790A (GSK101) activated a nonselective cation current, robustly elevated [Ca2+ ]i and reversibly increased the permeability of MVEC monolayers. This was associated with disrupted organization of endothelial F-actin, downregulated expression of occludin and remodelling of adherens contacts consisting of vascular endothelial cadherin (VE-cadherin) and β-catenin. In vivo, GSK101 increased the permeability of retinal blood vessels in wild type but not in TRPV4 knockout mice. Agonist-evoked effects on barrier permeability and cytoskeletal reorganization were antagonized by the selective TRPV4 blocker HC 067047. Human choroidal endothelial cells expressed lower TRPV4 mRNA/protein levels and showed less pronounced agonist-evoked calcium signals compared to MVECs. These findings indicate a major role for TRPV4 in Ca2+ homeostasis and barrier function in human retinal capillaries and suggest that TRPV4 may differentially contribute to the inner vs. outer blood-retinal barrier function.
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Affiliation(s)
- Tam T T Phuong
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Sarah N Redmon
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Oleg Yarishkin
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Jacob M Winter
- Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Dean Y Li
- Department of Medicine, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - David Križaj
- Department of Ophthalmology & Visual Sciences, University of Utah School of Medicine, Salt Lake City, UT, USA.,Department of Neurobiology & Anatomy, University of Utah School of Medicine, Salt Lake City, UT, USA.,Department of Bioengineering, University of Utah School of Medicine, Salt Lake City, UT, USA
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54
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Baratchi S, Khoshmanesh K, Woodman OL, Potocnik S, Peter K, McIntyre P. Molecular Sensors of Blood Flow in Endothelial Cells. Trends Mol Med 2017; 23:850-868. [PMID: 28811171 DOI: 10.1016/j.molmed.2017.07.007] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/16/2017] [Accepted: 07/19/2017] [Indexed: 01/08/2023]
Abstract
Mechanical stress from blood flow has a significant effect on endothelial physiology, with a key role in initiating vasoregulatory signals. Disturbances in blood flow, such as in regions of disease-associated stenosis, arterial branch points, and sharp turns, can induce proatherogenic phenotypes in endothelial cells. The disruption of vascular homeostasis as a result of endothelial dysfunction may contribute to early and late stages of atherosclerosis, the underlying cause of coronary artery disease. In-depth knowledge of the mechanobiology of endothelial cells is essential to identifying mechanosensory complexes involved in the pathogenesis of atherosclerosis. In this review, we describe different blood flow patterns and summarize current knowledge on mechanosensory molecules regulating endothelial vasoregulatory functions, with clinical implications. Such information may help in the search for novel therapeutic approaches.
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Affiliation(s)
- Sara Baratchi
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC 3083, Australia; Baker Heart and Diabetes Institute, Melbourne, VIC 3004, Australia.
| | | | - Owen L Woodman
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC 3083, Australia
| | - Simon Potocnik
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC 3083, Australia
| | - Karlheinz Peter
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC 3083, Australia; Baker Heart and Diabetes Institute, Melbourne, VIC 3004, Australia
| | - Peter McIntyre
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC 3083, Australia
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55
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Modulation of TRP Channel Activity by Hydroxylation and Its Therapeutic Potential. Pharmaceuticals (Basel) 2017; 10:ph10020035. [PMID: 28346371 PMCID: PMC5490392 DOI: 10.3390/ph10020035] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 03/15/2017] [Accepted: 03/24/2017] [Indexed: 12/15/2022] Open
Abstract
Two transient receptor potential (TRP) channels—TRPA1 and TRPV3—are post-translationally hydroxylated, resulting in oxygen-dependent regulation of channel activity. The enzymes responsible are the HIF prolyl hydroxylases (PHDs) and the asparaginyl hydroxylase factor inhibiting HIF (FIH). The PHDs and FIH are well characterized for their hydroxylation of the hypoxic inducible transcription factors (HIFs), mediating their hypoxic regulation. Consequently, these hydroxylases are currently being targeted therapeutically to modulate HIF activity in anemia, inflammation, and ischemic disease. Modulating the HIFs by targeting these hydroxylases may result in both desirable and undesirable effects on TRP channel activity, depending on the physiological context. For the best outcomes, these hydroxylases could be therapeutically targeted in pathologies where activation of both the HIFs and the relevant TRP channels are predicted to independently achieve positive outcomes, such as wound healing and obesity.
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56
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Billert M, Skrzypski M, Sassek M, Szczepankiewicz D, Wojciechowicz T, Mergler S, Strowski MZ, Nowak KW. TRPV4 regulates insulin mRNA expression and INS-1E cell death via ERK1/2 and NO-dependent mechanisms. Cell Signal 2017; 35:242-249. [PMID: 28359774 DOI: 10.1016/j.cellsig.2017.03.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2016] [Revised: 03/21/2017] [Accepted: 03/24/2017] [Indexed: 12/19/2022]
Abstract
TRPV4 is a Ca2+-permeable, nonselective cation channel. Recently, TRPV4 was implicated in controlling peripheral insulin sensitivity, insulin secretion and apoptosis of pancreatic beta cells. Here, we characterize the role and potential mechanisms of TRPV4 in regulating insulin mRNA expression and cell death in insulin producing INS-1E cells and rat pancreatic islets. TRPV4 protein production was downregulated by siRNA. Intracellular calcium level was measured using Fluo-3 AM. Gene expression was studied by real-time PCR. Phosphorylation of extracellular signal-regulated kinase (ERK1 and ERK2) was detected by Western blot. Nitric oxide (NO) production was assessed by chemiluminescent reaction. Reactive oxygen species (ROS) level was analysed using a fluorogenic dye (DCFDA). Cell death was evaluated by determination of cytoplasmic histone-associated DNA fragments. Downregulation of TRPV4 neither affected insulin mRNA expression nor INS-1E cell growth. By contrast, pharmacological TRPV4 activation by 100nmol/l GSK1016790A increased Ca2+ levels in INS-1E cells and enhanced insulin mRNA expression after 1 and 3h, whereas a suppression of insulin mRNA expression was detected after 24h incubation. GSK1016790A increased ERK1/2 phosphorylation and NO production but not ROS production. Pharmacological blockade of ERK1/2 attenuated GSK1016790A-induced insulin mRNA expression. Inhibition of NO synthesis by l-NAME failed to affect insulin mRNA expression in GSK1016790A treated INS-1E cells. Furthermore, inhibition of NO production attenuated GSK1016790A-induced INS-1E cell death. In pancreatic islets, 100nmol/l GSK1016790A increased insulin mRNA levels after 3h without inducing cytotoxicity after 24h. In conclusion, TRPV4 differently regulates insulin mRNA expression in INS-1E cells via ERK1/2 and NO-dependent mechanisms.
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Affiliation(s)
- M Billert
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60-637 Poznań, Poland
| | - M Skrzypski
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60-637 Poznań, Poland.
| | - M Sassek
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60-637 Poznań, Poland
| | - D Szczepankiewicz
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60-637 Poznań, Poland
| | - T Wojciechowicz
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60-637 Poznań, Poland
| | - S Mergler
- Department of Ophthalmology, Charité University Medicine Berlin, Germany
| | - M Z Strowski
- Department of Hepatology and Gastroenterology, Interdisciplinary Centre of Metabolism, Endocrinology, Diabetes and Metabolism, Charité-University Medicine Berlin, 13353 Berlin, Germany; Department of Internal Medicine-Gastroenterology, Park-Klinik Weissensee, 13086 Berlin, Germany
| | - K W Nowak
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60-637 Poznań, Poland
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57
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Grace MS, Bonvini SJ, Belvisi MG, McIntyre P. Modulation of the TRPV4 ion channel as a therapeutic target for disease. Pharmacol Ther 2017; 177:9-22. [PMID: 28202366 DOI: 10.1016/j.pharmthera.2017.02.019] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Transient Receptor Potential Vanilloid 4 (TRPV4) is a broadly expressed, polymodally gated ion channel that plays an important role in many physiological and pathophysiological processes. TRPV4 knockout mice and several synthetic pharmacological compounds that selectively target TRPV4 are now available, which has allowed detailed investigation in to the therapeutic potential of this ion channel. Results from animal studies suggest that TRPV4 antagonism has therapeutic potential in oedema, pain, gastrointestinal disorders, and lung diseases such as cough, bronchoconstriction, pulmonary hypertension, and acute lung injury. A lack of observed side-effects in vivo has prompted a first-in-human trial for a TRPV4 antagonist in healthy participants and stable heart failure patients. If successful, this would open up an exciting new area of research for a multitude of TRPV4-related pathologies. This review will discuss the known roles of TRPV4 in disease, and highlight the possible implications of targeting this important cation channel for therapy.
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Affiliation(s)
- Megan S Grace
- Baker Heart and Diabetes Institute, Melbourne, Australia; School of Health and Biomedical Sciences, RMIT University, Bundoora, Melbourne, Australia; Department of Physiology, School of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Australia.
| | - Sara J Bonvini
- Respiratory Pharmacology, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK
| | - Maria G Belvisi
- Respiratory Pharmacology, National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, UK
| | - Peter McIntyre
- School of Health and Biomedical Sciences, RMIT University, Bundoora, Melbourne, Australia
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58
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Servin-Vences MR, Moroni M, Lewin GR, Poole K. Direct measurement of TRPV4 and PIEZO1 activity reveals multiple mechanotransduction pathways in chondrocytes. eLife 2017; 6. [PMID: 28135189 PMCID: PMC5279942 DOI: 10.7554/elife.21074] [Citation(s) in RCA: 151] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 01/03/2017] [Indexed: 12/24/2022] Open
Abstract
The joints of mammals are lined with cartilage, comprised of individual chondrocytes embedded in a specialized extracellular matrix. Chondrocytes experience a complex mechanical environment and respond to changing mechanical loads in order to maintain cartilage homeostasis. It has been proposed that mechanically gated ion channels are of functional importance in chondrocyte mechanotransduction; however, direct evidence of mechanical current activation in these cells has been lacking. We have used high-speed pressure clamp and elastomeric pillar arrays to apply distinct mechanical stimuli to primary murine chondrocytes, stretch of the membrane and deflection of cell-substrate contacts points, respectively. Both TRPV4 and PIEZO1 channels contribute to currents activated by stimuli applied at cell-substrate contacts but only PIEZO1 mediates stretch-activated currents. These data demonstrate that there are separate, but overlapping, mechanoelectrical transduction pathways in chondrocytes.
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Affiliation(s)
| | - Mirko Moroni
- Department of Neuroscience, Max Delbruck Center for Molecular Medicine, Berlin, Germany
| | - Gary R Lewin
- Department of Neuroscience, Max Delbruck Center for Molecular Medicine, Berlin, Germany
| | - Kate Poole
- Department of Neuroscience, Max Delbruck Center for Molecular Medicine, Berlin, Germany.,Department of Physiology, School of Medical Sciences, University of New South Wales, Sydney, Australia.,EMBL Australia node for Single Molecule Sciences, School of Medical Sciences, University of New South Wales, Sydney, Australia
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