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Davis MJ, Earley S, Li YS, Chien S. Vascular mechanotransduction. Physiol Rev 2023; 103:1247-1421. [PMID: 36603156 PMCID: PMC9942936 DOI: 10.1152/physrev.00053.2021] [Citation(s) in RCA: 43] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 09/26/2022] [Accepted: 10/04/2022] [Indexed: 01/07/2023] Open
Abstract
This review aims to survey the current state of mechanotransduction in vascular smooth muscle cells (VSMCs) and endothelial cells (ECs), including their sensing of mechanical stimuli and transduction of mechanical signals that result in the acute functional modulation and longer-term transcriptomic and epigenetic regulation of blood vessels. The mechanosensors discussed include ion channels, plasma membrane-associated structures and receptors, and junction proteins. The mechanosignaling pathways presented include the cytoskeleton, integrins, extracellular matrix, and intracellular signaling molecules. These are followed by discussions on mechanical regulation of transcriptome and epigenetics, relevance of mechanotransduction to health and disease, and interactions between VSMCs and ECs. Throughout this review, we offer suggestions for specific topics that require further understanding. In the closing section on conclusions and perspectives, we summarize what is known and point out the need to treat the vasculature as a system, including not only VSMCs and ECs but also the extracellular matrix and other types of cells such as resident macrophages and pericytes, so that we can fully understand the physiology and pathophysiology of the blood vessel as a whole, thus enhancing the comprehension, diagnosis, treatment, and prevention of vascular diseases.
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Affiliation(s)
- Michael J Davis
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Scott Earley
- Department of Pharmacology, University of Nevada, Reno, Nevada
| | - Yi-Shuan Li
- Department of Bioengineering, University of California, San Diego, California
- Institute of Engineering in Medicine, University of California, San Diego, California
| | - Shu Chien
- Department of Bioengineering, University of California, San Diego, California
- Institute of Engineering in Medicine, University of California, San Diego, California
- Department of Medicine, University of California, San Diego, California
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2
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Kutikhin AG, Shishkova DK, Velikanova EA, Sinitsky MY, Sinitskaya AV, Markova VE. Endothelial Dysfunction in the Context of Blood–Brain Barrier Modeling. J EVOL BIOCHEM PHYS+ 2022; 58:781-806. [PMID: 35789679 PMCID: PMC9243926 DOI: 10.1134/s0022093022030139] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 04/04/2022] [Accepted: 04/05/2022] [Indexed: 01/04/2023]
Abstract
Here, we discuss pathophysiological approaches to the defining
of endothelial dysfunction criteria (i.e., endothelial activation,
impaired endothelial mechanotransduction, endothelial-to-mesenchymal
transition, reduced nitric oxide release, compromised endothelial
integrity, and loss of anti-thrombogenic properties) in different
in vitro and in vivo models. The canonical definition of endothelial
dysfunction includes insufficient production of vasodilators, pro-thrombotic
and pro-inflammatory activation of endothelial cells, and pathologically
increased endothelial permeability. Among the clinical consequences
of endothelial dysfunction are arterial hypertension, macro- and
microangiopathy, and microalbuminuria. We propose to extend the definition
of endothelial dysfunction by adding altered endothelial mechanotransduction
and endothelial-to-mesenchymal transition to its criteria. Albeit
interleukin-6, interleukin-8, and MCP-1/CCL2 dictate the pathogenic
paracrine effects of dysfunctional endothelial cells and are therefore
reliable endothelial dysfunction biomarkers in vitro, they are non-specific
for endothelial cells and cannot be used for the diagnostics of
endothelial dysfunction in vivo. Conceptual improvements in the
existing methods to model endothelial dysfunction, specifically,
in relation to the blood–brain barrier, include endothelial cell
culturing under pulsatile flow, collagen IV coating of flow chambers,
and endothelial lysate collection from the blood vessels of laboratory
animals in situ for the subsequent gene and protein expression profiling.
Combined with the simulation of paracrine effects by using conditioned
medium from dysfunctional endothelial cells, these flow-sensitive
models have a high physiological relevance, bringing the experimental
conditions to the physiological scenario.
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Affiliation(s)
- A. G. Kutikhin
- Research Institute for Complex Issues of Cardiovascular Diseases, Kemerovo, Russia
| | - D. K. Shishkova
- Research Institute for Complex Issues of Cardiovascular Diseases, Kemerovo, Russia
| | - E. A. Velikanova
- Research Institute for Complex Issues of Cardiovascular Diseases, Kemerovo, Russia
| | - M. Yu. Sinitsky
- Research Institute for Complex Issues of Cardiovascular Diseases, Kemerovo, Russia
| | - A. V. Sinitskaya
- Research Institute for Complex Issues of Cardiovascular Diseases, Kemerovo, Russia
| | - V. E. Markova
- Research Institute for Complex Issues of Cardiovascular Diseases, Kemerovo, Russia
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3
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Brandt MM, Cheng C, Merkus D, Duncker DJ, Sorop O. Mechanobiology of Microvascular Function and Structure in Health and Disease: Focus on the Coronary Circulation. Front Physiol 2022; 12:771960. [PMID: 35002759 PMCID: PMC8733629 DOI: 10.3389/fphys.2021.771960] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 11/11/2021] [Indexed: 12/19/2022] Open
Abstract
The coronary microvasculature plays a key role in regulating the tight coupling between myocardial perfusion and myocardial oxygen demand across a wide range of cardiac activity. Short-term regulation of coronary blood flow in response to metabolic stimuli is achieved via adjustment of vascular diameter in different segments of the microvasculature in conjunction with mechanical forces eliciting myogenic and flow-mediated vasodilation. In contrast, chronic adjustments in flow regulation also involve microvascular structural modifications, termed remodeling. Vascular remodeling encompasses changes in microvascular diameter and/or density being largely modulated by mechanical forces acting on the endothelium and vascular smooth muscle cells. Whereas in recent years, substantial knowledge has been gathered regarding the molecular mechanisms controlling microvascular tone and how these are altered in various diseases, the structural adaptations in response to pathologic situations are less well understood. In this article, we review the factors involved in coronary microvascular functional and structural alterations in obstructive and non-obstructive coronary artery disease and the molecular mechanisms involved therein with a focus on mechanobiology. Cardiovascular risk factors including metabolic dysregulation, hypercholesterolemia, hypertension and aging have been shown to induce microvascular (endothelial) dysfunction and vascular remodeling. Additionally, alterations in biomechanical forces produced by a coronary artery stenosis are associated with microvascular functional and structural alterations. Future studies should be directed at further unraveling the mechanisms underlying the coronary microvascular functional and structural alterations in disease; a deeper understanding of these mechanisms is critical for the identification of potential new targets for the treatment of ischemic heart disease.
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Affiliation(s)
- Maarten M Brandt
- Division of Experimental Cardiology, Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Caroline Cheng
- Division of Experimental Cardiology, Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands.,Division of Internal Medicine and Dermatology, Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, Netherlands
| | - Daphne Merkus
- Division of Experimental Cardiology, Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands.,Walter Brendel Center of Experimental Medicine (WBex), LMU Munich, Munich, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Munich, Munich Heart Alliance (MHA), Munich, Germany
| | - Dirk J Duncker
- Division of Experimental Cardiology, Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Oana Sorop
- Division of Experimental Cardiology, Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
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4
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Mishchenko EL, Mishchenko AM, Ivanisenko VA. Mechanosensitive molecular interactions in atherogenic regions of the arteries: development of atherosclerosis. Vavilovskii Zhurnal Genet Selektsii 2021; 25:552-561. [PMID: 34595377 PMCID: PMC8453358 DOI: 10.18699/vj21.062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 03/26/2021] [Accepted: 04/08/2021] [Indexed: 11/30/2022] Open
Abstract
A terrible disease of the cardiovascular system, atherosclerosis, develops in the areas of bends and
branches of arteries, where the direction and modulus of the blood flow velocity vector change, and consequently
so does the mechanical effect on endothelial cells in contact with the blood flow. The review focuses on topical
research studies on the development of atherosclerosis – mechanobiochemical events that transform the proatherogenic
mechanical stimulus of blood flow – low and low/oscillatory arterial wall shear stress in the chains of biochemical
reactions in endothelial cells, leading to the expression of specific proteins that cause the progression
of the pathological process. The stages of atherogenesis, systemic risk factors for atherogenesis and its important
hemodynamic factor, low and low/oscillatory wall shear stress exerted by blood flow on the endothelial cells lining
the arterial walls, have been described. The interactions of cell adhesion molecules responsible for the development
of atherosclerosis under low and low/oscillating shear stress conditions have been demonstrated. The activation
of the regulator of the expression of cell adhesion molecules, the transcription factor NF-κB, and the factors
regulating its activation under these conditions have been described. Mechanosensitive signaling pathways leading
to the expression of NF-κB in endothelial cells have been described. Studies of the mechanobiochemical signaling
pathways and interactions involved in the progression of atherosclerosis provide valuable information for the
development of approaches that delay or block the development of this disease.
Key words: atherogenesis; shear stress; transcription factor NF-κB; RelA expression; mechanosensitive receptors;
cell adhesion molecules; signaling pathways; mechanotransduction.
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Affiliation(s)
- E L Mishchenko
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | | | - V A Ivanisenko
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
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5
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Dessalles CA, Leclech C, Castagnino A, Barakat AI. Integration of substrate- and flow-derived stresses in endothelial cell mechanobiology. Commun Biol 2021; 4:764. [PMID: 34155305 PMCID: PMC8217569 DOI: 10.1038/s42003-021-02285-w] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Accepted: 06/02/2021] [Indexed: 02/05/2023] Open
Abstract
Endothelial cells (ECs) lining all blood vessels are subjected to large mechanical stresses that regulate their structure and function in health and disease. Here, we review EC responses to substrate-derived biophysical cues, namely topography, curvature, and stiffness, as well as to flow-derived stresses, notably shear stress, pressure, and tensile stresses. Because these mechanical cues in vivo are coupled and are exerted simultaneously on ECs, we also review the effects of multiple cues and describe burgeoning in vitro approaches for elucidating how ECs integrate and interpret various mechanical stimuli. We conclude by highlighting key open questions and upcoming challenges in the field of EC mechanobiology.
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Affiliation(s)
- Claire A Dessalles
- LadHyX, CNRS, Ecole polytechnique, Institut polytechnique de Paris, Palaiseau, France
| | - Claire Leclech
- LadHyX, CNRS, Ecole polytechnique, Institut polytechnique de Paris, Palaiseau, France
| | - Alessia Castagnino
- LadHyX, CNRS, Ecole polytechnique, Institut polytechnique de Paris, Palaiseau, France
| | - Abdul I Barakat
- LadHyX, CNRS, Ecole polytechnique, Institut polytechnique de Paris, Palaiseau, France.
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Zhang Q, Cao Y, Liu Y, Huang W, Ren J, Wang P, Song C, Fan K, Ba L, Wang L, Sun H. Shear stress inhibits cardiac microvascular endothelial cells apoptosis to protect against myocardial ischemia reperfusion injury via YAP/miR-206/PDCD4 signaling pathway. Biochem Pharmacol 2021; 186:114466. [PMID: 33610591 DOI: 10.1016/j.bcp.2021.114466] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 02/03/2021] [Accepted: 02/04/2021] [Indexed: 01/09/2023]
Abstract
Cardiac microvascular endothelial cells (CMECs), derived from coronary circulation microvessel, are the main barrier for the exchange of energy and nutrients between myocardium and blood. However, microvascular I/R injury is a severely neglected topic, and few strategies can reverse this pathology. In this study, we investigated the mechanism of shear stress in microvascular I/R injury, and try to elucidate the downstream signaling pathways that inhibit CMECs apoptosis to reduce I/R injury. Our results demonstrated that shear stress inhibited the apoptosis protein, increased PECAM-1 expression and eNOS phosphorylation in hypoxia reoxygenated (H/R) CMECs. The mechanism of shear stress was related to up-regulated expression of YAP, the increased number of YAP entering the nucleus by dephosphorylation, the reduced number of TUNEL positive cells, increased miR-206 and inhibited protein level of PDCD4 in CMECs. However, siRNA-mediated knockdown of YAP abolished the protective effects of shear stress on CMECs apoptosis, similar results obtained from administration with AMO-miR-206, and also prevented PDCD4 (target gene of miR-206) increasing when treatment with both AMO-miR-206 and mimics-miR-206. In vivo, restoring the blood fluid with nitroglycerin (NTG) to mimic in vitro shear stress levels, which subsequently improved cardiac function, reduced infarcted area, lowered microvascular perfusion defects. Functional investigations clearly illustrated that increased the protein expression of PECAM-1 and eNOS phosphorylation, activated YAP, strengthened miR-206 expression, and suppressed PDCD4 expression. In summary, this study confirmed that shear stress reversed CMECs apoptosis, relieved microvascular I/R injury, the mechanism of which involving through YAP/miR-206/PDCD4 signaling pathway to finally suppress myocardial I/R injury.
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Affiliation(s)
- Qianlong Zhang
- Department of Physiology, Harbin Medical University-Daqing, Daqing 163319, China
| | - Yonggang Cao
- Department of Pharmacology, Harbin Medical University-Daqing, Daqing 163319, China
| | - Yongsheng Liu
- Department of Pharmacology, Harbin Medical University-Daqing, Daqing 163319, China
| | - Wei Huang
- Department of Pharmacology, Harbin Medical University-Daqing, Daqing 163319, China
| | - Jing Ren
- Department of Pharmacology, Harbin Medical University-Daqing, Daqing 163319, China
| | - Peng Wang
- Department of Physiology, Harbin Medical University-Daqing, Daqing 163319, China
| | - Chao Song
- Department of Pharmacology, Harbin Medical University-Daqing, Daqing 163319, China
| | - Kai Fan
- Department of Pathology and Pathophysiology, Harbin Medical University-Daqing, Daqing 163319, China
| | - Lina Ba
- Department of Pharmacology, Harbin Medical University-Daqing, Daqing 163319, China
| | - Lixin Wang
- Department of Pharmacology, Harbin Medical University-Daqing, Daqing 163319, China
| | - Hongli Sun
- Department of Pharmacology, Harbin Medical University-Daqing, Daqing 163319, China.
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7
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Krüger-Genge A, Blocki A, Franke RP, Jung F. Vascular Endothelial Cell Biology: An Update. Int J Mol Sci 2019; 20:ijms20184411. [PMID: 31500313 PMCID: PMC6769656 DOI: 10.3390/ijms20184411] [Citation(s) in RCA: 533] [Impact Index Per Article: 106.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 06/28/2019] [Accepted: 07/01/2019] [Indexed: 12/20/2022] Open
Abstract
The vascular endothelium, a monolayer of endothelial cells (EC), constitutes the inner cellular lining of arteries, veins and capillaries and therefore is in direct contact with the components and cells of blood. The endothelium is not only a mere barrier between blood and tissues but also an endocrine organ. It actively controls the degree of vascular relaxation and constriction, and the extravasation of solutes, fluid, macromolecules and hormones, as well as that of platelets and blood cells. Through control of vascular tone, EC regulate the regional blood flow. They also direct inflammatory cells to foreign materials, areas in need of repair or defense against infections. In addition, EC are important in controlling blood fluidity, platelet adhesion and aggregation, leukocyte activation, adhesion, and transmigration. They also tightly keep the balance between coagulation and fibrinolysis and play a major role in the regulation of immune responses, inflammation and angiogenesis. To fulfill these different tasks, EC are heterogeneous and perform distinctly in the various organs and along the vascular tree. Important morphological, physiological and phenotypic differences between EC in the different parts of the arterial tree as well as between arteries and veins optimally support their specified functions in these vascular areas. This review updates the current knowledge about the morphology and function of endothelial cells, particularly their differences in different localizations around the body paying attention specifically to their different responses to physical, biochemical and environmental stimuli considering the different origins of the EC.
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Affiliation(s)
- Anne Krüger-Genge
- Department of Biomaterials and Healthcare, Division of Life Science and Bioprocesses, Fraunhofer Institute for Applied Polymer Research (IAP), Potsdam-Golm 14476, Germany.
- Department of Anesthesia, Pain Management and Perioperative Medicine, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 2Y9, Canada.
| | - Anna Blocki
- Institute for Tissue Engineering and Regenerative Medicine (ITERM), School of Biomedical Sciences (SBS), Chinese University of Hong Kong (CUHK), New Territories, Hong Kong, China
| | - Ralf-Peter Franke
- Central Institute for Biomedical Technology, Dep. Biomaterials, University of Ulm, Albert-Einstein-Allee 47, 89081 Ulm, Germany
| | - Friedrich Jung
- Institute of Biotechnology, Molecular Cell Biology, Brandenburg University of Technology, 01968 Senftenberg, Germany
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8
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Shear stress: An essential driver of endothelial progenitor cells. J Mol Cell Cardiol 2018; 118:46-69. [PMID: 29549046 DOI: 10.1016/j.yjmcc.2018.03.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 03/08/2018] [Accepted: 03/09/2018] [Indexed: 02/06/2023]
Abstract
The blood flow through vessels produces a tangential, or shear, stress sensed by their innermost layer (i.e., endothelium) and representing a major hemodynamic force. In humans, endothelial repair and blood vessel formation are mainly performed by circulating endothelial progenitor cells (EPCs) characterized by a considerable expression of vascular endothelial growth factor receptor 2 (VEGFR2), CD34, and CD133, pronounced tube formation activity in vitro, and strong reendothelialization or neovascularization capacity in vivo. EPCs have been proposed as a promising agent to induce reendothelialization of injured arteries, neovascularization of ischemic tissues, and endothelialization or vascularization of bioartificial constructs. A number of preconditioning approaches have been suggested to improve the regenerative potential of EPCs, including the use of biophysical stimuli such as shear stress. However, in spite of well-defined influence of shear stress on mature endothelial cells (ECs), articles summarizing how it affects EPCs are lacking. Here we discuss the impact of shear stress on homing, paracrine effects, and differentiation of EPCs. Unidirectional laminar shear stress significantly promotes homing of circulating EPCs to endothelial injury sites, induces anti-thrombotic and anti-atherosclerotic phenotype of EPCs, increases their capability to form capillary-like tubes in vitro, and enhances differentiation of EPCs into mature ECs in a dose-dependent manner. These effects are mediated by VEGFR2, Tie2, Notch, and β1/3 integrin signaling and can be abrogated by means of complementary siRNA/shRNA or selective pharmacological inhibitors of the respective proteins. Although the testing of sheared EPCs for vascular tissue engineering or regenerative medicine applications is still an unaccomplished task, favorable effects of unidirectional laminar shear stress on EPCs suggest its usefulness for their preconditioning.
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9
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Urner S, Kelly-Goss M, Peirce SM, Lammert E. Mechanotransduction in Blood and Lymphatic Vascular Development and Disease. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2017; 81:155-208. [PMID: 29310798 DOI: 10.1016/bs.apha.2017.08.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The blood and lymphatic vasculatures are hierarchical networks of vessels, which constantly transport fluids and, therefore, are exposed to a variety of mechanical forces. Considering the role of mechanotransduction is key for fully understanding how these vascular systems develop, function, and how vascular pathologies evolve. During embryonic development, for example, initiation of blood flow is essential for early vascular remodeling, and increased interstitial fluid pressure as well as initiation of lymph flow is needed for proper development and maturation of the lymphatic vasculature. In this review, we introduce specific mechanical forces that affect both the blood and lymphatic vasculatures, including longitudinal and circumferential stretch, as well as shear stress. In addition, we provide an overview of the role of mechanotransduction during atherosclerosis and secondary lymphedema, which both trigger tissue fibrosis.
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Affiliation(s)
- Sofia Urner
- Institute of Metabolic Physiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Molly Kelly-Goss
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, United States
| | - Shayn M Peirce
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, United States
| | - Eckhard Lammert
- Institute of Metabolic Physiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany; Institute for Beta Cell Biology, German Diabetes Center, Leibniz Center for Diabetes Research at Heinrich Heine University, Düsseldorf, Germany.
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10
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Sulistyowati E, Permatasari N, Aris Widodo M. Combined effects of shear stress and glucose on the morphology, actin filaments, and VE-cadherin of endothelial cells in vitro. IJC HEART & VASCULATURE 2017; 15:31-35. [PMID: 28785603 PMCID: PMC5522977 DOI: 10.1016/j.ijcha.2017.03.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 03/31/2017] [Indexed: 11/28/2022]
Abstract
Objective The purpose of the present study was to analyze the effects of glucose and shear stress on the morphology and density of endothelial cells, actin filamen, and the expression of VE-cadherin. Methods After confluency of endothelial cells (3–4 days), 22 mM of d-glucose was administered for 7 days. Endothelial cells were exposed to shear stress of 10 dyne/cm2 for varied durations of 5, 8, 12, and 15 min. Morphology of ECs was observed using an inverted microscope before and after shear stress exposure. VE-cadherin and actin filament were analyzed immunohistochemically. Results Exposure to high glucose induces more shrinkage and the cell density decreased at 15 min. High glucose reduced actin filaments and the more globular ones, especially around the nuclei. There was a decline in VE-cadherin scores with significant differences between treatments with 5 mM and 22 mM of glucose. Conclusion Combination exposure of shear stress and high glucose changes morphology, reduces actin filament and VE-cadherin, of endothelial cells.
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Affiliation(s)
- Erna Sulistyowati
- Department of Pathology, Faculty of Medicine, Malang Islamic University, Malang, East Java, Indonesia
| | - Nur Permatasari
- Department of Pharmacology, Faculty of Medicine, Brawijaya University, Malang, East Java, Indonesia
| | - M Aris Widodo
- Department of Pharmacology, Faculty of Medicine, Brawijaya University, Malang, East Java, Indonesia
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11
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Dela Paz NG, Melchior B, Frangos JA. Shear stress induces Gα q/11 activation independently of G protein-coupled receptor activation in endothelial cells. Am J Physiol Cell Physiol 2017; 312:C428-C437. [PMID: 28148497 DOI: 10.1152/ajpcell.00148.2016] [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] [Received: 05/20/2016] [Revised: 01/25/2017] [Accepted: 01/25/2017] [Indexed: 12/17/2022]
Abstract
Mechanochemical signal transduction occurs when mechanical forces, such as fluid shear stress, are converted into biochemical responses within the cell. The molecular mechanisms by which endothelial cells (ECs) sense/transduce shear stress into biological signals, including the nature of the mechanosensor, are still unclear. G proteins and G protein-coupled receptors (GPCRs) have been postulated independently to mediate mechanotransduction. In this study, we used in situ proximity ligation assay (PLA) to investigate the role of a specific GPCR/Gαq/11 pair in EC shear stress-induced mechanotransduction. We demonstrated that sphingosine 1-phosphate (S1P) stimulation causes a rapid dissociation at 0.5 min of Gαq/11 from its receptor S1P3, followed by an increased association within 2 min of GPCR kinase-2 (GRK2) and β-arrestin-1/2 with S1P3 in human coronary artery ECs, which are consistent with GPCR/Gαq/11 activation and receptor desensitization/internalization. The G protein activator AlF4 resulted in increased dissociation of Gαq/11 from S1P3, but no increase in association between S1P3 and either GRK2 or β-arrestin-1/2. The G protein inhibitor guanosine 5'-(β-thio) diphosphate (GDP-β-S) and the S1P3 antagonist VPC23019 both prevented S1P-induced activation. Shear stress also caused the rapid activation within 7 s of S1P3/Gαq/11 There were no increased associations between S1P3 and GRK2 or S1P3 and β-arrestin-1/2 until 5 min. GDP-β-S, but not VPC23019, prevented dissociation of Gαq/11 from S1P3 in response to shear stress. Shear stress did not induce rapid dephosphorylation of β-arrestin-1 or rapid internalization of S1P3, indicating no GPCR activation. These findings suggest that Gαq/11 participates in the sensing/transducing of shear stress independently of GPCR activation in ECs.
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Abstract
SIGNIFICANCE Forces are important in the cardiovascular system, acting as regulators of vascular physiology and pathology. Residing at the blood vessel interface, cells (endothelial cell, EC) are constantly exposed to vascular forces, including shear stress. Shear stress is the frictional force exerted by blood flow, and its patterns differ based on vessel geometry and type. These patterns range from uniform laminar flow to nonuniform disturbed flow. Although ECs sense and differentially respond to flow patterns unique to their microenvironment, the mechanisms underlying endothelial mechanosensing remain incompletely understood. RECENT ADVANCES A large body of work suggests that ECs possess many mechanosensors that decorate their apical, junctional, and basal surfaces. These potential mechanosensors sense blood flow, translating physical force into biochemical signaling events. CRITICAL ISSUES Understanding the mechanisms by which proposed mechanosensors sense and respond to shear stress requires an integrative approach. It is also critical to understand the role of these mechanosensors not only during embryonic development but also in the different vascular beds in the adult. Possible cross talk and integration of mechanosensing via the various mechanosensors remain a challenge. FUTURE DIRECTIONS Determination of the hierarchy of endothelial mechanosensors is critical for future work, as is determination of the extent to which mechanosensors work together to achieve force-dependent signaling. The role and primary sensors of shear stress during development also remain an open question. Finally, integrative approaches must be used to determine absolute mechanosensory function of potential mechanosensors. Antioxid. Redox Signal. 25, 373-388.
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Affiliation(s)
- Chris Givens
- 1 Department of Cell Biology and Physiology, University of North Carolina-Chapel Hill , Chapel Hill, North Carolina
| | - Ellie Tzima
- 1 Department of Cell Biology and Physiology, University of North Carolina-Chapel Hill , Chapel Hill, North Carolina.,2 Cardiovascular Medicine, Wellcome Trust Centre for Human Genetics , Oxford, United Kingdom
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13
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Abstract
PURPOSE OF REVIEW Blood flow is intimately linked with cardiovascular development, repair and dysfunction. The current review will build on the fluid mechanical principle underlying haemodynamic shear forces, mechanotransduction and metabolic effects. RECENT FINDINGS Pulsatile flow produces both time (∂τ/∂t) and spatial-varying shear stress (∂τ/∂x) to modulate vascular oxidative stress and inflammatory response with pathophysiological significance to atherosclerosis. The characteristics of haemodynamic shear forces, namely, steady laminar (∂τ/∂t = 0), pulsatile shear stress (PSS: unidirectional forward flow) and oscillatory shear stress (bidirectional with a near net 0 forward flow), modulate mechano-signal transduction to influence metabolic effects on vascular endothelial function. Atheroprotective PSS promotes antioxidant, anti-inflammatory and antithrombotic responses, whereas atherogenic oscillatory shear stress induces nicotinamide adenine dinucleotide phosphate oxidase-JNK signalling to increase mitochondrial superoxide production, protein degradation of manganese superoxide dismutase and post-translational protein modifications of LDL particles in the disturbed flow-exposed regions of vasculature. In the era of tissue regeneration, shear stress has been implicated in reactivation of developmental genes, namely, Wnt and Notch signalling, for vascular development and repair. SUMMARY Blood flow imparts a dynamic continuum from vascular development to repair. Augmentation of PSS confers atheroprotection and reactivation of developmental signalling pathways for regeneration.
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Affiliation(s)
- Juhyun Lee
- Department of Bioengineering, Department of Medicine, all at the University of California, Los Angeles, Los Angeles, California
| | - René R. Sevag Packard
- Department of Molecular, Cellular and Integrative Physiology, Department of Medicine, all at the University of California, Los Angeles, Los Angeles, California
- Division of Cardiology, Department of Medicine, all at the University of California, Los Angeles, Los Angeles, California
| | - Tzung K. Hsiai
- Department of Bioengineering, Department of Medicine, all at the University of California, Los Angeles, Los Angeles, California
- Department of Molecular, Cellular and Integrative Physiology, Department of Medicine, all at the University of California, Los Angeles, Los Angeles, California
- Division of Cardiology, Department of Medicine, all at the University of California, Los Angeles, Los Angeles, California
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14
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Digital microfluidic immunocytochemistry in single cells. Nat Commun 2015; 6:7513. [PMID: 26104298 PMCID: PMC4491823 DOI: 10.1038/ncomms8513] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 05/14/2015] [Indexed: 01/06/2023] Open
Abstract
We report a new technique called Digital microfluidic Immunocytochemistry in Single Cells (DISC). DISC automates protocols for cell culture, stimulation and immunocytochemistry, enabling the interrogation of protein phosphorylation on pulsing with stimulus for as little as 3 s. DISC was used to probe the phosphorylation states of platelet-derived growth factor receptor (PDGFR) and the downstream signalling protein, Akt, to evaluate concentration- and time-dependent effects of stimulation. The high time resolution of the technique allowed for surprising new observations-for example, a 10 s pulse stimulus of a low concentration of PDGF is sufficient to cause >30% of adherent fibroblasts to commit to Akt activation. With the ability to quantitatively probe signalling events with high time resolution at the single-cell level, we propose that DISC may be an important new technique for a wide range of applications, especially for screening signalling responses of a heterogeneous cell population.
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15
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Li X, Yang Q, Wang Z, Wei D. Shear Stress in Atherosclerotic Plaque Determination. DNA Cell Biol 2014; 33:830-8. [DOI: 10.1089/dna.2014.2480] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Xiaohong Li
- Institute of Cardiovascular Disease, Key Laboratory for Atherosclerology of Hunan Province, University of South China, Hengyang, China
| | - Qin Yang
- Institute of Cardiovascular Disease, Key Laboratory for Atherosclerology of Hunan Province, University of South China, Hengyang, China
| | - Zuo Wang
- Institute of Cardiovascular Disease, Key Laboratory for Atherosclerology of Hunan Province, University of South China, Hengyang, China
| | - Dangheng Wei
- Institute of Cardiovascular Disease, Key Laboratory for Atherosclerology of Hunan Province, University of South China, Hengyang, China
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16
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Abstract
Hemodynamic shear stress, the frictional force acting on vascular endothelial cells, is crucial for endothelial homeostasis under normal physiological conditions. When discussing blood flow effects on various forms of endothelial (dys)function, one considers two flow patterns: steady laminar flow and disturbed flow because endothelial cells respond differently to these flow types both in vivo and in vitro. Laminar flow which exerts steady laminar shear stress is atheroprotective while disturbed flow creates an atheroprone environment. Emerging evidence has provided new insights into the cellular mechanisms of flow-dependent regulation of vascular function that leads to cardiovascular events such as atherosclerosis, atherothrombosis, and myocardial infarction. In order to study effects of shear stress and different types of flow, various models have been used. In this review, we will summarize our current views on how disturbed flow-mediated signaling pathways are involved in the development of atherosclerosis.
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Affiliation(s)
- Kyung-Sun Heo
- Aab Cardiovascular Research Institute, University of Rochester, Rochester, NY 14642,
USA
| | - Keigi Fujiwara
- Aab Cardiovascular Research Institute, University of Rochester, Rochester, NY 14642,
USA
| | - Jun-ichi Abe
- Aab Cardiovascular Research Institute, University of Rochester, Rochester, NY 14642,
USA
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17
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Devika NT, Jaffar Ali BM. Analysing calcium dependent and independent regulation of eNOS in endothelium triggered by extracellular signalling events. MOLECULAR BIOSYSTEMS 2014; 9:2653-64. [PMID: 23954998 DOI: 10.1039/c3mb70258h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The vascular endothelium, the intima of blood vessels, coordinately interacts with several biochemical factors expressing endothelial nitric oxide synthase (eNOS) to produce nitric oxide (NO), a potent endogenous vasodilator. The present study investigated the regulation of eNOS by multiple molecular signal transduction pathways, namely vascular endothelial growth factor (VEGF-A) and shear stress which are implicated in the process of angiogenesis and vascular remodelling respectively. In response to signal transduction upstream by VEGF-A and shear stress, different signalling pathways mediated by kinases and intracellular calcium potentiates eNOS activation leading to nitric oxide release. Our study revealed a distinct pattern of eNOS activation driven by VEGF-A and shear stress, maintaining the signalling specificity of the respective pathways. A transient response to eNOS activation was observed under VEGF-A and shear stress stimulus when mediated by calcium dependent cascades, whereas a sustained response was produced by calcium independent vascular signalling kinases. Furthermore, we found that the basal arterial shear stress enhanced eNOS activity when stimulated synergistically even at low VEGF-A levels which might be utilized to facilitate specific endothelial cell functions. Moreover, our study revealed that the presence of PI3K imparted transient behaviour to PLCγ1 supporting the hypothesis that regression and formation of tube structures are mediated by PLCγ1 and PI3K respectively in endothelial cells. This fact is corroborated by the absence of transient behaviour when PI3K is inhibited. We therefore obtained subtle insights into the control mechanism governing the role of specific signalling proteins which are obligate for the regulation of endothelial cell function and the consequent modulation of the nitric oxide release pattern.
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Affiliation(s)
- N T Devika
- AU-KBC Research Centre, Madras Institute of Technology, Anna University, Chrompet, Chennai - 600 044, Tamil Nadu, India.
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18
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Conway DE, Schwartz MA. Flow-dependent cellular mechanotransduction in atherosclerosis. J Cell Sci 2013; 126:5101-9. [PMID: 24190880 DOI: 10.1242/jcs.138313] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Atherosclerosis depends on risk factors such as hyperlipidemia, smoking, hypertension and diabetes. Although these risk factors are relatively constant throughout the arterial circulation, atherosclerotic plaques occur at specific sites where flow patterns are disturbed, with lower overall magnitude and complex changes in speed and direction. Research over the past few decades has provided new insights into the cellular mechanisms of force transduction and how mechanical effects act in concert with conventional risk factors to mediate plaque formation and progression. This Commentary summarizes our current understanding of how mechanotransduction pathways synergize with conventional risk factors in atherosclerosis. We attempt to integrate cellular studies with animal and clinical data, and highlight major questions that need to be answered to develop more effective therapies.
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Affiliation(s)
- Daniel E Conway
- Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908, USA
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19
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Abstract
At least 468 individual genes have been manipulated by molecular methods to study their effects on the initiation, promotion, and progression of atherosclerosis. Most clinicians and many investigators, even in related disciplines, find many of these genes and the related pathways entirely foreign. Medical schools generally do not attempt to incorporate the relevant molecular biology into their curriculum. A number of key signaling pathways are highly relevant to atherogenesis and are presented to provide a context for the gene manipulations summarized herein. The pathways include the following: the insulin receptor (and other receptor tyrosine kinases); Ras and MAPK activation; TNF-α and related family members leading to activation of NF-κB; effects of reactive oxygen species (ROS) on signaling; endothelial adaptations to flow including G protein-coupled receptor (GPCR) and integrin-related signaling; activation of endothelial and other cells by modified lipoproteins; purinergic signaling; control of leukocyte adhesion to endothelium, migration, and further activation; foam cell formation; and macrophage and vascular smooth muscle cell signaling related to proliferation, efferocytosis, and apoptosis. This review is intended primarily as an introduction to these key signaling pathways. They have become the focus of modern atherosclerosis research and will undoubtedly provide a rich resource for future innovation toward intervention and prevention of the number one cause of death in the modern world.
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Affiliation(s)
- Paul N Hopkins
- Cardiovascular Genetics, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, USA.
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20
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Wakayama N, Katow T, Katow H. Characterization and Endocytic Internalization of Epith-2 Cell Surface Glycoprotein during the Epithelial-to-Mesenchymal Transition in Sea Urchin Embryos. Front Endocrinol (Lausanne) 2013; 4:112. [PMID: 24009602 PMCID: PMC3757445 DOI: 10.3389/fendo.2013.00112] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 08/14/2013] [Indexed: 01/25/2023] Open
Abstract
The epithelial cells of the sea urchin Hemicentrotus pulcherrimus embryo express an Epith-2, uncharacterized glycoprotein, on the lateral surface. Here, we describe internalization of Epith-2 during mesenchyme formation through the epithelial-to-mesenchymal transition (EMT). Epith-2 was first expressed on the entire egg surface soon after fertilization and on the blastomeres until the 4-cell stage, but was localized to the lateral surface of epithelial cells at and after the 16-cell stage throughout the later developmental period. However, primary mesenchyme cells (PMC) and secondary mesenchyme cells (SMC) that ingress by EMT lost Epith-2 from their cell surface by endocytosis during dissociation from the epithelium, which was associated with the appearance of cytoplasmic Epith-2 dots. The cytoplasmic Epith-2 retained a similar relative molecular mass to that of the cell surface immediately after ingression through the early period of the spreading to single cells. Then, Epith-2 was completely lost from the cytoplasm. Tyrosine residues of Epith-2 were phosphorylated. The endocytic retraction of Epith-2 was inhibited by herbimycin A (HA), a protein tyrosine kinase (PTK) inhibitor, and suramin, a growth factor receptor (GFR) inhibitor, suggesting the involvement of the GFR/PTK (GP) signaling pathway. These two GP inhibitors also inhibited PMC and SMC spreading to individual cells after ingression, but the dissociation of PMC and SMC from the epithelium was not inhibited. In suramin-treated embryos, dissociated mesenchyme cells migrated partially by retaining their epithelial morphology. In HA-treated embryos, no mesenchyme cells migrated. Thus, the EMT occurs in relation to internalization of Epith-2 from presumptive PMC and SMC.
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Affiliation(s)
- Norio Wakayama
- Research Center for Marine Biology, Tohoku University, Aomori, Aomori, Japan
| | - Tomoko Katow
- Research Center for Marine Biology, Tohoku University, Aomori, Aomori, Japan
| | - Hideki Katow
- Research Center for Marine Biology, Tohoku University, Aomori, Aomori, Japan
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21
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Abstract
The ability to respond and adapt to changes in the physical environment is a universal and essential cellular property. Here we demonstrated that cells respond to mechanical compressive stress by rapidly inducing autophagosome formation. We measured this response in both Dictyostelium and mammalian cells, indicating that this is an evolutionarily conserved, general response to mechanical stress. In Dictyostelium, the number of autophagosomes increased 20-fold within 10 min of 1 kPa pressure being applied and a similar response was seen in mammalian cells after 30 min. We showed in both cell types that autophagy is highly sensitive to changes in mechanical pressure and the response is graduated, with half-maximal responses at ~0.2 kPa, similar to other mechano-sensitive responses. We further showed that the mechanical induction of autophagy is TOR-independent and transient, lasting until the cells adapt to their new environment and recover their shape. The autophagic response is therefore part of an integrated response to mechanical challenge, allowing cells to cope with a continuously changing physical environment.
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Affiliation(s)
- Jason S King
- Beatson Institute for Cancer Research, Glasgow, Scotland, UK.
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22
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Melchior B, Frangos JA. Gαq/11-mediated intracellular calcium responses to retrograde flow in endothelial cells. Am J Physiol Cell Physiol 2012; 303:C467-73. [PMID: 22700794 DOI: 10.1152/ajpcell.00117.2012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Disturbed flow patterns, including reversal in flow direction, are key factors in the development of dysfunctional endothelial cells (ECs) and atherosclerotic lesions. An almost immediate response of ECs to fluid shear stress is the increase in cytosolic calcium concentration ([Ca(2+)](i)). Whether the source of [Ca(2+)](i) is extracellular, released from Ca(2+) intracellular stores, or both is still undefined, though it is likely dependent on the nature of forces involved. We have previously shown that a change in flow direction (retrograde flow) on a flow-adapted endothelial monolayer induces the remodeling of the cell-cell junction along with a dramatic [Ca(2+)](i) burst compared with cells exposed to unidirectional or orthograde flow. The heterotrimeric G protein-α q and 11 subunit (Gα(q/11)) is a likely candidate in effecting shear-induced increases in [Ca(2+)](i) since its expression is enriched at the junction and has been previously shown to be activated within seconds after onset of flow. In flow-adapted human ECs, we have investigated to what extent the Gα(q/11) pathway mediates calcium dynamics after reversal in flow direction. We observed that the elapsed time to peak [Ca(2+)](i) response to a 10 dyn/cm(2) retrograde shear stress was increased by 11 s in cells silenced with small interfering RNA directed against Gα(q/11). A similar lag in [Ca(2+)](i) transient was observed after cells were treated with the phospholipase C (PLC)-βγ inhibitor, U-73122, or the phosphatidylinositol-specific PLC inhibitor, edelfosine, compared with controls. Lower levels of inositol 1,4,5-trisphosphate accumulation seconds after the onset of flow correlated with the increased lag in [Ca(2+)](i) responses observed with the different treatments. In addition, inhibition of the inositol 1,4,5-trisphosphate receptor entirely abrogated flow-induced [Ca(2+)](i). Taken together, our results identify the Gα(q/11)-PLC pathway as the initial trigger for retrograde flow-induced endoplasmic reticulum calcium store release, thereby offering a novel approach to regulating EC dysfunctions in regions subjected to the reversal of blood flow.
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Affiliation(s)
- Benoît Melchior
- La Jolla Bioengineering Institute, San Diego, California, USA
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23
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Conway D, Schwartz MA. Lessons from the endothelial junctional mechanosensory complex. F1000 BIOLOGY REPORTS 2012; 4:1. [PMID: 22238515 PMCID: PMC3251317 DOI: 10.3410/b4-1] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Mechanotransduction plays a key role in both normal physiology and in diseases such as cancer, atherosclerosis and hypertension. Nowhere is this more evident than in the vascular system, where fluid shear stress from blood flow plays a critical role in shaping the blood vessels and in determining their function and dysfunction. Responses to flow are mediated in part by a complex of proteins comprised of PECAM-1, VE-cadherin and VEGFR2 at endothelial cell-cell junctions; all proteins that clearly have other, non-mechanical functions. We review recent progress toward understanding the functions and mechanisms of mechanotransduction by this complex and suggest some principles that may apply more broadly.
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Affiliation(s)
- Daniel Conway
- Department of Microbiology and Cardiovascular Research Center, University of VirginiaCharlottesville VA 22908USA
| | - Martin A. Schwartz
- Department of Microbiology and Cardiovascular Research Center, University of VirginiaCharlottesville VA 22908USA
- Departments of Cell Biology and Biomedical Engineering, University of VirginiaCharlottesville VA 22908USA
- Departments of Medicine and Cell Biology, Yale UniversityNew Haven CT 06511USA
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24
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Curry FE, Adamson RH. Endothelial glycocalyx: permeability barrier and mechanosensor. Ann Biomed Eng 2011; 40:828-39. [PMID: 22009311 DOI: 10.1007/s10439-011-0429-8] [Citation(s) in RCA: 194] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 10/03/2011] [Indexed: 12/16/2022]
Abstract
Endothelial cells are covered with a polysaccharide rich layer more than 400 nm thick, mechanical properties of which limit access of circulating plasma components to endothelial cell membranes. The barrier properties of this endothelial surface layer are deduced from the rate of tracer penetration into the layer and the mechanics of red and white cell movement through capillary microvessels. This review compares the mechanosensor and permeability properties of an inner layer (100-150 nm, close to the endothelial membrane) characterized as a quasi-periodic structure which accounts for key aspects of transvascular exchange and vascular permeability with those of the whole endothelial surface layers. We conclude that many of the barrier properties of the whole surface layer are not representative of the primary fiber matrix forming the molecular filter determining transvascular exchange. The differences between the properties of the whole layer and the inner glycocalyx structures likely reflect dynamic aspects of the endothelial surface layer including tracer binding to specific components, synthesis and degradation of key components, activation of signaling pathways in the endothelial cells when components of the surface layer are lost or degraded, and the spatial distribution of adhesion proteins in microdomains of the endothelial cell membrane.
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Affiliation(s)
- F E Curry
- Department of Physiology and Membrane Biology, School of Medicine, University of California at Davis, 1 Shields Avenue, Davis, CA 95616, USA.
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25
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Low-intensity pulsed ultrasound modulates shear stress induced PGHS-2 expression and PGE2 synthesis in MLO-Y4 osteocyte-like cells. Ann Biomed Eng 2010; 39:378-93. [PMID: 20820919 DOI: 10.1007/s10439-010-0156-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2010] [Accepted: 08/25/2010] [Indexed: 02/01/2023]
Abstract
Fluid shear stress (SS) has been shown to be a prevailing physiological stimulus in the regulation of bone cell metabolism and so are the exogenous biomechanical forces, like ultrasound (US) and vibration. The purpose of this study is to elaborate the interplay of laminar fluid SS with low-intensity pulsed US in the regulation of prostaglandin H synthase 2 (PGHS-2) and prostaglandin E2 (PGE2). Murine long bone osteocyte-like (MLO-Y4) cells were exposed to various regimes of US (1.5 Hz, 30 mW/cm2) and SS (19 dyn/cm2) alone and sequentially. Changes in PGHS-2 gene expression levels were quantified at 3 and 24 h using real-time RT-PCR. PGE2 levels in the culture media were measured using enzyme immunoassay at 3 and 24 h. PGE2 levels significantly increased after exposure to SS for 3 and 24 h by 2.17±0.02 and 5.47±0.42-fold, respectively, compared to control cells. A 20 min US treatment prior to SS significantly increased SS PGE2 levels 2.95±0.18 and 2.90±0.50-fold at 3 and 24 h, respectively. US also significantly increased PGHS-2 mRNA levels in cells exposed to SS. SS caused a 2.74 ± 0.49-fold increase in PGHS-2 mRNA levels at 3 h and a significant 3.70±0.25-fold increase at 24 h relative to control. A 20 min US treatment caused 1.35±0.49 and 2.44±0.82-fold increase in PGHS-2 mRNA levels in cells exposed to SS at 3 and 24 h, respectively. These results indicate that combining US with SS may have a more anabolic benefit for bone tissue than either stimulus alone.
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26
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Gordeladze JO, Djouad F, Brondello JM, Noël D, Duroux-Richard I, Apparailly F, Jorgensen C. Concerted stimuli regulating osteo-chondral differentiation from stem cells: phenotype acquisition regulated by microRNAs. Acta Pharmacol Sin 2009; 30:1369-84. [PMID: 19801995 DOI: 10.1038/aps.2009.143] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Bone and cartilage are being generated de novo through concerted actions of a plethora of signals. These act on stem cells (SCs) recruited for lineage-specific differentiation, with cellular phenotypes representing various functions throughout their life span. The signals are rendered by hormones and growth factors (GFs) and mechanical forces ensuring proper modelling and remodelling of bone and cartilage, due to indigenous and programmed metabolism in SCs, osteoblasts, chondrocytes, as well as osteoclasts and other cell types (eg T helper cells).This review focuses on the concerted action of such signals, as well as the regulatory and/or stabilizing control circuits rendered by a class of small RNAs, designated microRNAs. The impact on cell functions evoked by transcription factors (TFs) via various signalling molecules, also encompassing mechanical stimulation, will be discussed featuring microRNAs as important members of an integrative system. The present approach to cell differentiation in vitro may vastly influence cell engineering for in vivo tissue repair.
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27
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Abstract
The focal development of atherosclerosis in the vascular tree may be explained in part by the local nature of blood flow. Bifurcations and branching points, prone to early atherogenesis, experience disturbed and oscillatory flow, whereas straight vascular regions, resistant to atherosclerosis, are exposed to steady laminar flow. A large number of studies suggest that the antiatherosclerotic effects of laminar flow are in part due to the ability of flow to modulate endothelial cell phenotype. Under steady laminar flow, endothelial cells generate molecules that promote a vasoactive, anticoagulant, anti-inflammatory, and growth-inhibitory surface. In contrast, disturbed flow induces a proliferative, prothrombotic, and adhesive phenotype. Endothelial cells are able to sense the variations of flow via mechanosensitive cell surface proteins and to transduce these signals via intracellular pathways to transcription factors in the nucleus leading to phenotypic changes. This review summarizes the "outside-in" signaling events initiated by flow that modulate endothelial cell phenotype.
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Affiliation(s)
- Gwenaele Garin
- Department of Medicine, Cardiovascular Research Institute and University of Rochester, Rochester, New York 14642, USA
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28
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Otte LA, Bell KS, Loufrani L, Yeh JC, Melchior B, Dao DN, Stevens HY, White CR, Frangos JA. Rapid changes in shear stress induce dissociation of a G alpha(q/11)-platelet endothelial cell adhesion molecule-1 complex. J Physiol 2009; 587:2365-73. [PMID: 19332487 DOI: 10.1113/jphysiol.2009.172643] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
It has been recently shown that endothelial platelet endothelial cell adhesion molecule-1 (PECAM-1) expression is pro-atherogenic. PECAM-1 is involved in sensing rapid changes in fluid shear stress but the mechanisms for activating signalling complexes at the endothelial cell junction have yet to be elucidated. Additional studies suggest the activation of membrane-bound G proteins G alpha(q/11) also mediate flow-induced responses. Here, we investigated whether PECAM-1 and G alpha(q/11) could act in unison to rapidly respond to fluid shear stress. With immunohistochemistry, we observed a co-localization of G alpha(q/11) and PECAM-1 at the cell-cell junction in the atheroprotected section of mouse aortae. In contrast, G alpha(q/11) was absent from junctions in atheroprone areas as well as in all arterial sections of PECAM-1 knockout mice. In primary human endothelial cells, temporal gradients in shear stress led to a rapid dissociation of the G alpha(q/11)-PECAM-1 complex within 30 s and a partial relocalization of the G alpha(q/11) staining to perinuclear areas within 150 min, whereas transitioning fluid flow devoid of temporal gradients did not disrupt the complex. Inhibition of G protein activation eliminated temporal gradient flow-induced G alpha(q/11)-PECAM-1 dissociation. These results allow us to conclude that G alpha(q/11)-PECAM-1 forms a mechanosensitive complex and its localization suggests the G alpha(q/11)-PECAM-1 complex is a critical mediator of vascular diseases.
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Affiliation(s)
- Laura A Otte
- La Jolla Bioengineering Institute, 505 Coast Blvd South, La Jolla, CA 92037, USA
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29
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Lowering caveolin-1 expression in human vascular endothelial cells inhibits signal transduction in response to shear stress. Int J Cell Biol 2008; 2009:532432. [PMID: 20111626 PMCID: PMC2809413 DOI: 10.1155/2009/532432] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Accepted: 10/19/2008] [Indexed: 11/17/2022] Open
Abstract
Vascular endothelial cells have an extensive response to physiological levels of shear stress. There is evidence that the protein caveolin-1 is involved in the early phase of this response. In this study, caveolin-1 was downregulated in human endothelial cells by RNAi. When these cells were subjected to a shear stress of 15 dyn/cm(2) for 10 minutes, activation of Akt and ERK1/2 was significantly lower than in control cells. Moreover, activation of Akt and ERK1/2 in response to vascular endothelial growth factor was significantly lower in cells with low levels of caveolin-1. However, activation of integrin-mediated signaling during cell adhesion onto fibronectin was not hampered by lowered caveolin-1 levels. In conclusion, caveolin-1 is an essential component in the response of endothelial cells to shear stress. Furthermore, the results suggest that the role of caveolin-1 in this process lies in facilitating efficient VEGFR2-mediated signaling.
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30
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Yeh JC, Otte LA, Frangos JA. Regulation of G protein-coupled receptor activities by the platelet-endothelial cell adhesion molecule, PECAM-1. Biochemistry 2008; 47:9029-39. [PMID: 18672896 DOI: 10.1021/bi8003846] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
It is becoming increasingly evident that the cell-cell junction is a major signaling center. Here we show that the Galphaq/11 subunit of heterotrimeric G proteins forms a complex with platelet-endothelial cell adhesion molecule 1 (PECAM-1), a junctional protein that has been shown to be involved in mechanosignaling in endothelial cells. To understand the role of PECAM-1 in this complex, we determined the critical regions of PECAM-1 involved in this interaction. By expressing truncated forms of PECAM-1 in human embryonic kidney (HEK293) cells, we found that the cytoplasmic domain of PECAM-1 is not required for its association with Galphaq/11. Domain swapping of PECAM-1 with intracellular cell adhesion molecule 1 (ICAM-1), a protein that does not form a complex with Galphaq/11, provides evidence that the extracellular domain of PECAM-1 is critical for this interaction. This result also suggests that PECAM-1 does not directly interact with Galphaq/11. Coexpression of bradykinin receptor B2 (BKRB2), a Galphaq/11-coupled receptor, with PECAM-1 enhances formation of the PECAM-1-Galphaq/11 complex, suggesting an interaction between PECAM-1 and BKRB2. Co-immunoprecipitation experiments indicate that these two molecules indeed form a complex when expressed in HEK293 cells. Activation of ERK1/2 by bradykinin in HUVEC is enhanced when PECAM-1 expression is inhibited by transfection of small interference RNA against PECAM-1. Taken together, our results provide evidence of interaction of PECAM-1 with BKRB2 and of its possible role in regulating G protein-coupled receptor (GPCR) and G protein functions.
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Affiliation(s)
- Jiunn-chern Yeh
- La Jolla Bioengineering Institute, 505 Coast Boulevard South, Suite 406, La Jolla, California 92037, USA
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31
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Rapid signal transduction in living cells is a unique feature of mechanotransduction. Proc Natl Acad Sci U S A 2008; 105:6626-31. [PMID: 18456839 DOI: 10.1073/pnas.0711704105] [Citation(s) in RCA: 318] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
It is widely postulated that mechanotransduction is initiated at the local force-membrane interface by inducing local conformational changes of proteins, similar to soluble ligand-induced signal transduction. However, all published reports are limited in time scale to address this fundamental issue. Using a FRET-based cytosolic Src reporter in a living cell, we quantified changes of Src activities as a local stress via activated integrins was applied. The stress induced rapid (<0.3 s) activation of Src at remote cytoplasmic sites, which depends on the cytoskeletal prestress. In contrast, there was no Src activation within 12 s of soluble epidermal growth factor (EGF) stimulation. A 1.8-Pa stress over a focal adhesion activated Src to the same extent as 0.4 ng/ml EGF at long times (minutes), and the energy levels for mechanical stimulation and chemical stimulation were comparable. The effect of both stress and EGF was less than additive. Nanometer-scale cytoskeletal deformation analyses revealed that the strong activation sites of Src by stress colocalized with large deformation sites of microtubules, suggesting that microtubules are essential structures for transmitting stresses to activate cytoplasmic proteins. These results demonstrate that rapid signal transduction via the prestressed cytoskeleton is a unique feature of mechanotransduction.
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32
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Fernandes J, Lorenzo IM, Andrade YN, Garcia-Elias A, Serra SA, Fernández-Fernández JM, Valverde MA. IP3 sensitizes TRPV4 channel to the mechano- and osmotransducing messenger 5'-6'-epoxyeicosatrienoic acid. ACTA ACUST UNITED AC 2008; 181:143-55. [PMID: 18378772 PMCID: PMC2287294 DOI: 10.1083/jcb.200712058] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mechanical and osmotic sensitivity of the transient receptor potential vanilloid 4 (TRPV4) channel depends on phospholipase A2 (PLA2) activation and the subsequent production of the arachidonic acid metabolites, epoxyeicosatrienoic acid (EET). We show that both high viscous loading and hypotonicity stimuli in native ciliated epithelial cells use PLA2–EET as the primary pathway to activate TRPV4. Under conditions of low PLA2 activation, both also use extracellular ATP-mediated activation of phospholipase C (PLC)–inositol trisphosphate (IP3) signaling to support TRPV4 gating. IP3, without being an agonist itself, sensitizes TRPV4 to EET in epithelial ciliated cells and cells heterologously expressing TRPV4, an effect inhibited by the IP3 receptor antagonist xestospongin C. Coimmunoprecipitation assays indicated a physical interaction between TRPV4 and IP3 receptor 3. Collectively, our study suggests a functional coupling between plasma membrane TRPV4 channels and intracellular store Ca2+ channels required to initiate and maintain the oscillatory Ca2+ signal triggered by high viscosity and hypotonic stimuli that do not reach a threshold level of PLA2 activation.
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Affiliation(s)
- Jacqueline Fernandes
- Laboratory of Molecular Physiology and Channelopathies, Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona 08003, Spain
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33
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Abstract
The Ras superfamily consists of over 50 low-molecular-weight proteins that cycle between an inactive guanosine diphosphate-bound state and an active guanosine triphosphate (GTP)-bound state. They are involved in a variety of signal transduction pathways that regulate cell growth, intracellular trafficking, cell migration, and apoptosis. Several methods have been devised to measure the activation state of Ras proteins, defined as the percent of Ras molecules in the active GTP-bound state. We have previously developed a quantitative biochemical method that can be applied to animal and human tissues and have used it to measure the activation state of Ras, Rap1, Rheb, and Rho proteins in cultured cells and in animal and human tumors. Ras, Rac, and Rho all play roles in regulating the functions of T and B lymphocytes and dendritic cells, and these proteins are clearly important in maintaining normal immune system function.
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Affiliation(s)
- Juergen S Scheele
- Co-ordinating Center for Clinical Trials, Martin Luther University, Halle, Germany
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Lawler K, Foran E, O'Sullivan G, Long A, Kenny D. Mobility and invasiveness of metastatic esophageal cancer are potentiated by shear stress in a ROCK- and Ras-dependent manner. Am J Physiol Cell Physiol 2006; 291:C668-77. [PMID: 16641163 DOI: 10.1152/ajpcell.00626.2005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
To metastasize, tumor cells must adopt different morphological responses to resist shear forces encountered in circulating blood and invade through basement membranes. The Rho and Ras GTPases play a critical role in regulating this dynamic behavior. Recently, we demonstrated shear-induced activation of adherent esophageal metastatic cells, characterized by formation of dynamic membrane blebs. Although membrane blebbing has only recently been characterized as a rounded mode of cellular invasion promoted through Rho kinase (ROCK), the role of shear forces in modulating membrane blebbing activity is unknown. To further characterize membrane blebbing in esophageal metastatic cells (OC-1 cell line), we investigated the role of shear in cytoskeletal remodeling and signaling through ROCK and Ras. Our results show that actin and tubulin colocalize to the cortical ring of the OC-1 cell under static conditions. However, under shear, actin acquires a punctuate distribution and tubulin localizes to the leading edge of the OC-1 cell. We show for the first time that dynamic bleb formation is induced by shear alone independent of integrin-mediated adhesion ( P < 0.001, compared with OC-1 cells). Y-27632, a specific inhibitor of ROCK, causes a significant reduction in shear-induced bleb formation and inhibits integrin αvβ3-Ras colocalization at the leading edge of the cell. Direct measurement of Ras activation shows that the level of GTP-bound Ras is elevated in sheared OC-1 cells and that the shear-induced increase in Ras activity is inhibited by Y-27632. Finally, we show that shear stress significantly increases OC-1 cell invasion ( P < 0.007), an effect negated by the presence of Y-27632. Together our findings suggest a novel physiological role for ROCK and Ras in metastatic cell behavior.
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Affiliation(s)
- Karen Lawler
- Department of Clinical Pharmacology, Royal College of Surgeons, Dublin, Ireland
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35
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Abstract
Fluid shear stress caused by blood flow is a major determinant of vascular remodeling and arterial tone and can lead to development of atherosclerosis. The endothelial monolayer in vivo acts as a signal transduction interface for hemodynamic forces; these forces determine the shape, cytoskeletal organization, and function of endothelial cells, allowing the vessels to cope with physiological or pathological conditions. The Ras superfamily of GTPases have been revealed to be master regulators of many cellular activities. In particular, the GTPases RhoA, Rac1, and Cdc42 are known to regulate cell shape changes through effects on the cytoskeleton, but their ability to influence polarity, microtubule dynamics, and transcription factor activity is just as significant. Shear stress modulates the activity of small GTPases, which are critical for both cytoskeletal reorganization and changes in gene expression in response to shear stress. The goal of this article is to review what is known about Ras and more so about Rho GTPases in mechanotransduction and the responses of cells to fluid flow. Several distinct signaling pathways can be coordinately activated by flow, and small GTPases are strongly implicated in some of them; thus possible connections will be explored and a unifying hypothesis offered.
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Affiliation(s)
- Eleni Tzima
- Department of Cell and Molecular Physiology, Carolina Cardiovascular Biology Center, University of North Carolina, Chapel Hill, NC 27599, USA.
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36
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Rubin J, Rubin C, Jacobs CR. Molecular pathways mediating mechanical signaling in bone. Gene 2006; 367:1-16. [PMID: 16361069 PMCID: PMC3687520 DOI: 10.1016/j.gene.2005.10.028] [Citation(s) in RCA: 297] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2005] [Accepted: 10/03/2005] [Indexed: 12/26/2022]
Abstract
Bone tissue has the capacity to adapt to its functional environment such that its morphology is "optimized" for the mechanical demand. The adaptive nature of the skeleton poses an interesting set of biological questions (e.g., how does bone sense mechanical signals, what cells are the sensing system, what are the mechanical signals that drive the system, what receptors are responsible for transducing the mechanical signal, what are the molecular responses to the mechanical stimuli). Studies of the characteristics of the mechanical environment at the cellular level, the forces that bone cells recognize, and the integrated cellular responses are providing new information at an accelerating speed. This review first considers the mechanical factors that are generated by loading in the skeleton, including strain, stress and pressure. Mechanosensitive cells placed to recognize these forces in the skeleton, osteoblasts, osteoclasts, osteocytes and cells of the vasculature are reviewed. The identity of the mechanoreceptor(s) is approached, with consideration of ion channels, integrins, connexins, the lipid membrane including caveolar and non-caveolar lipid rafts and the possibility that altering cell shape at the membrane or cytoskeleton alters integral signaling protein associations. The distal intracellular signaling systems on-line after the mechanoreceptor is activated are reviewed, including those emanating from G-proteins (e.g., intracellular calcium shifts), MAPKs, and nitric oxide. The ability to harness mechanical signals to improve bone health through devices and exercise is broached. Increased appreciation of the importance of the mechanical environment in regulating and determining the structural efficacy of the skeleton makes this an exciting time for further exploration of this area.
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Affiliation(s)
- Janet Rubin
- Department of Medicine, VAMC and Emory University School of Medicine, Atlanta GA, VAMC-151, 1670 Clairmont Rd, Decatur, GA 30033, USA.
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37
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Abstract
Major advances have been made over the last decade towards the elucidation of the molecular mechanisms involved in the endothelium-dependent regulation of vascular tone and blood flow. While the primary endothelium-derived vasodilator autacoid is nitric oxide, it is clear that epoxyeicosatrienoic acids and other endothelium-derived hyperpolarising factors, as well as endothelin-1 and reactive oxygen species, play a significant role in the regulation of vascular tone and gene expression. This review is intended as an overview of the signalling mechanisms that link haemodynamic stimuli (such as shear stress and cyclic stretch) and endothelial cell perturbation to the activation of enzymes generating vasoactive autacoids.
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Affiliation(s)
- R Busse
- Vascular Signalling Group, Institut für Kardiovaskuläre Physiologie, Klinikum der J.W. Goethe-Universität, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany
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Li YSJ, Haga JH, Chien S. Molecular basis of the effects of shear stress on vascular endothelial cells. J Biomech 2005; 38:1949-71. [PMID: 16084198 DOI: 10.1016/j.jbiomech.2004.09.030] [Citation(s) in RCA: 593] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2004] [Accepted: 09/20/2004] [Indexed: 12/15/2022]
Abstract
Blood vessels are constantly exposed to hemodynamic forces in the form of cyclic stretch and shear stress due to the pulsatile nature of blood pressure and flow. Endothelial cells (ECs) are subjected to the shear stress resulting from blood flow and are able to convert mechanical stimuli into intracellular signals that affect cellular functions, e.g., proliferation, apoptosis, migration, permeability, and remodeling, as well as gene expression. The ECs use multiple sensing mechanisms to detect changes in mechanical forces, leading to the activation of signaling networks. The cytoskeleton provides a structural framework for the EC to transmit mechanical forces between its luminal, abluminal and junctional surfaces and its interior, including the cytoplasm, the nucleus, and focal adhesion sites. Endothelial cells also respond differently to different modes of shear forces, e.g., laminar, disturbed, or oscillatory flows. In vitro studies on cultured ECs in flow channels have been conducted to investigate the molecular mechanisms by which cells convert the mechanical input into biochemical events, which eventually lead to functional responses. The knowledge gained on mechano-transduction, with verifications under in vivo conditions, will advance our understanding of the physiological and pathological processes in vascular remodeling and adaptation in health and disease.
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Affiliation(s)
- Yi-Shuan J Li
- Department of Bioengineering, University of California, San Diego, La Jolla, 92093-0412, USA
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39
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Calvert RJ, Kammouni W, Kikawa KD. Optimization of a nonradioactive method for consistent and sensitive determination of activated K-ras protein. Anal Biochem 2005; 343:283-92. [PMID: 16018961 DOI: 10.1016/j.ab.2005.06.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2005] [Revised: 05/25/2005] [Accepted: 06/03/2005] [Indexed: 11/17/2022]
Abstract
Accurate measurement of activity of wild-type K-ras protein is important due to its tumor suppressor action in tissues such as lung. A published method by Taylor and co-workers uses plasmid-containing Escherichia coli cells to produce a glutathione-S-transferase/raf-1 ras binding domain (GST-RBD) fusion protein attached to glutathione beads to isolate activated ras protein. We systematically optimized the method before use on lung tissues. Changing the GST-RBD protein induction temperature from the original 37 to 30 degrees C produced a consistently greater yield of fusion protein. To improve stability of the GST-RBD beads so as to perform large-scale experiments, 0.1% NaN(3) was added. NaN(3)-treated beads retained full affinity for at least 24 days. Sensitivity was improved by using a polyvinylidene difluoride membrane rather than nitrocellulose for immunoblotting. We also compared our GST-RBD beads with two commercial assay kits and found that our beads had both superior sensitivity and reduced variability. In summary, our modification of the GST-RBD affinity method to recover activated K-ras greatly increased the yield of fusion protein, prolonged the useful life of GST-RBD beads to at least 24 days, and enhanced detection sensitivity.
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Affiliation(s)
- Richard J Calvert
- U.S. Food and Drug Administration, Office of Nutritional Products, Labeling, and Dietary Supplements, Division of Research and Applied Technology, College Park, MD 20740, USA.
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40
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Fleming I, Fisslthaler B, Dixit M, Busse R. Role of PECAM-1 in the shear-stress-induced activation of Akt and the endothelial nitric oxide synthase (eNOS) in endothelial cells. J Cell Sci 2005; 118:4103-11. [PMID: 16118242 DOI: 10.1242/jcs.02541] [Citation(s) in RCA: 227] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The application of fluid shear stress to endothelial cells elicits the formation of nitric oxide (NO) and phosphorylation of the endothelial NO synthase (eNOS). Shear stress also elicits the enhanced tyrosine phosphorylation of endothelial proteins, especially of those situated in the vicinity of cell-cell contacts. Since a major constituent of these endothelial cell-cell contacts is the platelet endothelial cell adhesion molecule-1 (PECAM-1) we assessed the role of PECAM-1 in the activation of eNOS.In human endothelial cells, shear stress induced the tyrosine phosphorylation of PECAM-1 and enhanced the association of PECAM-1 with eNOS. Endothelial cell stimulation with shear stress elicited the phosphorylation of Akt and eNOS as well as of the AMP-activated protein kinase (AMPK). While the shear-stress-induced tyrosine phosphorylation of PECAM-1 as well as the serine phosphorylation of Akt and eNOS were abolished by the pre-treatment of cells with the tyrosine kinase inhibitor PP1 the phosphorylation of AMPK was unaffected. Down-regulation of PECAM-1 using a siRNA approach attenuated the shear-stress-induced phosphorylation of Akt and eNOS, as well as the shear-stress-induced accumulation of cyclic GMP levels while the shear-stress-induced phosphorylation of AMPK remained intact. A comparable attenuation of Akt and eNOS (but not AMPK) phosphorylation and NO production was also observed in endothelial cells generated from PECAM-1-deficient mice.These data indicate that the shear-stress-induced activation of Akt and eNOS in endothelial cells is modulated by the tyrosine phosphorylation of PECAM-1 whereas the shear-stress-induced phosphorylation of AMPK is controlled by an alternative signaling pathway.
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Affiliation(s)
- Ingrid Fleming
- Institut für Kardiovaskuläre Physiologie, Johann Wolfgang Goethe-Universität, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany.
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Ganguli A, Persson L, Palmer IR, Evans I, Yang L, Smallwood R, Black R, Qwarnstrom EE. Distinct NF-κB Regulation by Shear Stress Through Ras-Dependent IκBα Oscillations. Circ Res 2005; 96:626-34. [PMID: 15731464 DOI: 10.1161/01.res.0000160435.83210.95] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
NF-kappaB, a transcription factor central to inflammatory regulation during development of atherosclerosis, is activated by soluble mediators and through biomechanical inputs such as flow-mediated shear- stress. To investigate the molecular mechanisms underlying shear stress mediated signal transduction in vascular cells we have developed a system that applies flow-mediated shear stress in a controlled manner, while inserted in a confocal microscope. In combination with GFP-based methods, this allows continuous monitoring of flow induced signal transduction in live cells and in real time. Flow-mediated shear stress, induced using the system, caused a successive increase in NF-kappaB-regulated gene activation. Experiments assessing the mechanisms underlying the NF-kappaB induced activity showed time and flow rate dependent effects on the inhibitor, IkappaBalpha, involving nuclear translocation characterized by a biphasic or cyclic pattern. The effect was observed in both endothelial- and smooth muscle cells, demonstrated to impact noncomplexed IkappaBalpha, and to involve mechanisms distinct from those mediating cytokine signals. In contrast, effects on the NF-kappaB subunit relA were similar to those observed during cytokine stimulation. Further experiments showed the flow induced inter-compartmental transport of IkappaBalpha to be regulated through the Ras GTP-ase, demonstrating a pronounced reduction in the effects following blocking of Ras activity. These studies show that flow-mediated shear stress, regulated by the Ras GTP-ase, uses distinct mechanisms of NF-kappaB control at the molecular level. The oscillatory pattern, reflecting inter-compartmental translocation of IkappaBetaalpha, is likely to have fundamental impact on pathway regulation and on development of shear stress-induced distinct vascular cell phenotypes.
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Affiliation(s)
- Arunima Ganguli
- Academic Unit of Cell Biology, School of Medicine and Biomedical Sciences, University of Sheffield, UK
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42
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Abstract
Although the pathobiology of atherosclerosis is a complex multifactorial process, blood flow-induced shear stress has emerged as an essential feature of atherogenesis. This fluid drag force acting on the vessel wall is mechanotransduced into a biochemical signal that results in changes in vascular behavior. Maintenance of a physiologic, laminar shear stress is known to be crucial for normal vascular functioning, which includes the regulation of vascular caliber as well as inhibition of proliferation, thrombosis and inflammation of the vessel wall. Thus, shear stress is atheroprotective. It is also recognized that disturbed or oscillatory flows near arterial bifurcations, branch ostia and curvatures are associated with atheroma formation. Additionally, vascular endothelium has been shown to have different behavioral responses to altered flow patterns both at the molecular and cellular levels and these reactions are proposed to promote atherosclerosis in synergy with other well-defined systemic risk factors. Nonlaminar flow promotes changes to endothelial gene expression, cytoskeletal arrangement, wound repair, leukocyte adhesion as well as to the vasoreactive, oxidative and inflammatory states of the artery wall. Disturbed shear stress also influences the site selectivity of atherosclerotic plaque formation as well as its associated vessel wall remodeling, which can affect plaque vulnerability, stent restenosis and smooth muscle cell intimal hyperplasia in venous bypass grafts. Thus, shear stress is critically important in regulating the atheroprotective, normal physiology as well as the pathobiology and dysfunction of the vessel wall through complex molecular mechanisms that promote atherogenesis.
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Affiliation(s)
- Kristopher S Cunningham
- Department of Pathology, Toronto General Research Institute, University Health Network, Canada
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43
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Cotter EJ, von Offenberg Sweeney N, Coen PM, Birney YA, Glucksman MJ, Cahill PA, Cummins PM. Regulation of Endopeptidases EC3.4.24.15 and EC3.4.24.16 in Vascular Endothelial Cells by Cyclic Strain: Role of Gi Protein Signaling. Arterioscler Thromb Vasc Biol 2004; 24:457-63. [PMID: 14726412 DOI: 10.1161/01.atv.0000117176.71143.a1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Endopeptidase EC3.4.24.15 (EP24.15)- and EC3.4.24.16 (EP24.16)-specific peptide hydrolysis plays an important role in endothelium-mediated vasoregulation. Given the significant influence of hemodynamic forces on vascular homeostasis and pathology, we postulated that these related peptidases may be mechanosensitive. The objective of this study, therefore, was to investigate the putative role of cyclic strain in regulating the expression and enzymatic activity of EP24.15 and EP24.16 in bovine aortic endothelial cells (BAECs). METHODS AND RESULTS BAECs were cultured under conditions of defined cyclic strain (0% to 10% stretch, 60 cycles/min, 0 to 24 hours). Strain significantly increased EP24.15 and EP24.16 soluble activity in a force- and time-dependent manner, with elevations of 2.3+/-0.4- and 1.9+/-0.3-fold for EP24.15 and EP24.16, respectively, after 24 hours at 10% strain. Pharmacological agents and dominant-negative G protein mutants used to selectively disrupt Gi(alpha)- and Gbetagamma-mediated signaling pathways attenuated strain-dependent (24 hours, 5%) increases for both enzymes. Differences in the inhibitory profile for both enzymes were also noted, with EP24.15 displaying greater sensitivity to Gi(alpha2/3) inhibition and EP24.16 exhibiting greater sensitivity to Gi(alpha1/2) and Gbetagamma inhibition. Cyclic strain also increased levels of secreted EP24.15 and EP24.16 activity by 2.6+/-0.02- and 3.6+/-0.2-fold, respectively, in addition to mRNA levels for both enzymes (EP24.15 +42%, EP24.16 +56%). CONCLUSIONS Our findings suggest that cyclic strain putatively regulates both the mRNA expression and enzymatic function of EP24.15 and EP24.16 in BAECs via alternate Gi protein signaling pathways.
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Affiliation(s)
- Eoin J Cotter
- Vascular Health Research Centre, Faculty of Science and Health, Dublin City University, Glasnevin, Dublin, Ireland
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44
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Eskin SG, Horbett TA, McIntire LV, Mitchell RN, Ratner BD, Schoen FJ, Yee A. Some Background Concepts. Biomater Sci 1996. [DOI: 10.1016/b978-012582460-6/50006-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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