1
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Beverley KM, Levitan I. Cholesterol regulation of mechanosensitive ion channels. Front Cell Dev Biol 2024; 12:1352259. [PMID: 38333595 PMCID: PMC10850386 DOI: 10.3389/fcell.2024.1352259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 01/17/2024] [Indexed: 02/10/2024] Open
Abstract
The purpose of this review is to evaluate the role of cholesterol in regulating mechanosensitive ion channels. Ion channels discussed in this review are sensitive to two types of mechanical signals, fluid shear stress and/or membrane stretch. Cholesterol regulates the channels primarily in two ways: 1) indirectly through localizing the channels into cholesterol-rich membrane domains where they interact with accessory proteins and/or 2) direct binding of cholesterol to the channel at specified putative binding sites. Cholesterol may also regulate channel function via changes of the biophysical properties of the membrane bilayer. Changes in cholesterol affect both mechanosensitivity and basal channel function. We focus on four mechanosensitive ion channels in this review Piezo, Kir2, TRPV4, and VRAC channels. Piezo channels were shown to be regulated by auxiliary proteins that enhance channel function in high cholesterol domains. The direct binding mechanism was shown in Kir2.1 and TRPV4 where cholesterol inhibits channel function. Finally, cholesterol regulation of VRAC was attributed to changes in the physical properties of lipid bilayer. Additional studies should be performed to determine the physiological implications of these sterol effects in complex cellular environments.
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Affiliation(s)
- Katie M. Beverley
- Division of Pulmonary, Critical Care, Sleep, and Allergy, Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Irena Levitan
- Division of Pulmonary, Critical Care, Sleep, and Allergy, Department of Medicine, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
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2
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Gou Z, Zhang H, Misbah C. Heterogeneous ATP patterns in microvascular networks. J R Soc Interface 2023; 20:20230186. [PMID: 37464803 PMCID: PMC10354495 DOI: 10.1098/rsif.2023.0186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 06/21/2023] [Indexed: 07/20/2023] Open
Abstract
ATP is not only an energy carrier but also serves as an important signalling molecule in many physiological processes. Abnormal ATP level in blood vessel is known to be related to several pathologies, such as inflammation, hypoxia and atherosclerosis. Using advanced numerical methods, we analysed ATP released by red blood cells (RBCs) and its degradation by endothelial cells (ECs) in a cat mesentery-inspired vascular network, accounting for RBC mutual interaction and interactions with vascular walls. Our analysis revealed a heterogeneous ATP distribution in the network, with higher concentrations in the cell-free layer, concentration peaks around bifurcations and heterogeneity among vessels of the same level. These patterns arise from the spatio-temporal organization of RBCs induced by the network geometry. It is further shown that an alteration of hematocrit and flow strength significantly affects ATP level as well as heterogeneity in the network. These findings constitute a first building block to elucidate the intricate nature of ATP patterns in vascular networks and the far reaching consequences for other biochemical signalling, such as calcium, by ECs.
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Affiliation(s)
- Zhe Gou
- CNRS, LIPhy, Université Grenoble Alpes, 38000 Grenoble, France
| | - Hengdi Zhang
- CNRS, LIPhy, Université Grenoble Alpes, 38000 Grenoble, France
- Shenzhen Sibionics Co. Ltd, Shenzhen, People’s Republic of China
| | - Chaouqi Misbah
- CNRS, LIPhy, Université Grenoble Alpes, 38000 Grenoble, France
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3
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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: 45] [Impact Index Per Article: 45.0] [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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4
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Ebihara L, Acharya P, Tong JJ. Mechanical Stress Modulates Calcium-Activated-Chloride Currents in Differentiating Lens Cells. Front Physiol 2022; 13:814651. [PMID: 35173630 PMCID: PMC8842795 DOI: 10.3389/fphys.2022.814651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 01/06/2022] [Indexed: 11/13/2022] Open
Abstract
During accommodation, the lens changes focus by altering its shape following contraction and relaxation of the ciliary muscle. At the cellular level, these changes in shape may be accompanied by fluid flow in and out of individual lens cells. We tested the hypothesis that some of this flow might be directly modulated by pressure-activated channels. In particular, we used the whole cell patch clamp technique to test whether calcium-activated-chloride channels (CaCCs) expressed in differentiating lens cells are activated by mechanical stimulation. Our results show that mechanical stress, produced by focally perfusing the lens cell at a constant rate, caused a significant increase in a chloride current that could be fully reversed by stopping perfusion. The time course of activation and recovery from activation of the flow-induced current occurred rapidly over a time frame similar to that of accommodation. The flow-induced current could be inhibited by the TMEM16A specific CaCC blocker, Ani9, suggesting that the affected current was predominantly due to TMEM16A chloride channels. The mechanism of action of mechanical stress did not appear to involve calcium influx through other mechanosensitive ion channels since removal of calcium from the bath solution failed to block the flow-induced chloride current. In conclusion, our results suggest that CaCCs in the lens can be rapidly and reversibly modulated by mechanical stress, consistent with their participation in regulation of volume in this organ.
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Affiliation(s)
- Lisa Ebihara
- Center of Proteomics and Molecular Therapeutics, Rosalind Franklin University of Medicine and Science, North Chicago, IL, United States
- Discipline of Physiology and Biophysics, Rosalind Franklin University of Medicine and Science, North Chicago, IL, United States
- *Correspondence: Lisa Ebihara,
| | - Pooja Acharya
- Center of Proteomics and Molecular Therapeutics, Rosalind Franklin University of Medicine and Science, North Chicago, IL, United States
| | - Jun-Jie Tong
- Center of Proteomics and Molecular Therapeutics, Rosalind Franklin University of Medicine and Science, North Chicago, IL, United States
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5
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Yoon J, Shin M, Kim D, Lim J, Kim HW, Kang T, Choi JW. Bionanohybrid composed of metalloprotein/DNA/MoS 2/peptides to control the intracellular redox states of living cells and its applicability as a cell-based biomemory device. Biosens Bioelectron 2022; 196:113725. [PMID: 34678652 DOI: 10.1016/j.bios.2021.113725] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 10/17/2021] [Indexed: 12/13/2022]
Abstract
The development of cell-based bioelectronic devices largely depends on the direct control of intracellular redox states. However, most related studies have focused on the accurate measurement of electrical signals from living cells, whereas direct intracellular state control remains largely unexplored. Here, we developed a biocompatible transmembranal bionanohybrid structure composed of a recombinant metalloprotein, DNA, molybdenum disulfide nanoparticles (MoS2), and peptides to control intracellular redox states, which can be used as a cell-based biomemory device. Using the capacitance of MoS2 located inside the cell, the bionanohybrid controled the intracellular redox states of living cells by recording and extracting intracellular charges, which inturn was achieved by activating (writing) and deactivating (erasing) the cells. As a proof of concept, cell-based biomemory functions including writing, reading, and erasing were successfully demonstrated and confirmed via electrochemical methods and patch-clamp analyses, resulting in the development of the first in vitro cell-based biomemory device. This newly developed bionanohybrid provides a novel approach to control cellular redox states for cell-based bioelectronic applications, and can be applicable in a wide range of biological fields including bioelectronic medicine and intracellular redox status regulation.
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Affiliation(s)
- Jinho Yoon
- Department of Chemical & Biomolecular Engineering, Sogang University, 35 Baekbeom-Ro, Mapo-Gu, Seoul 04107, Republic of Korea
| | - Minkyu Shin
- Department of Chemical & Biomolecular Engineering, Sogang University, 35 Baekbeom-Ro, Mapo-Gu, Seoul 04107, Republic of Korea
| | - Dongyeon Kim
- Department of Chemical & Biomolecular Engineering, Sogang University, 35 Baekbeom-Ro, Mapo-Gu, Seoul 04107, Republic of Korea
| | - Joungpyo Lim
- Department of Chemical & Biomolecular Engineering, Sogang University, 35 Baekbeom-Ro, Mapo-Gu, Seoul 04107, Republic of Korea
| | - Hyun-Woong Kim
- Department of Chemical & Biomolecular Engineering, Sogang University, 35 Baekbeom-Ro, Mapo-Gu, Seoul 04107, Republic of Korea
| | - Taewook Kang
- Department of Chemical & Biomolecular Engineering, Sogang University, 35 Baekbeom-Ro, Mapo-Gu, Seoul 04107, Republic of Korea
| | - Jeong-Woo Choi
- Department of Chemical & Biomolecular Engineering, Sogang University, 35 Baekbeom-Ro, Mapo-Gu, Seoul 04107, Republic of Korea.
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6
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Fancher IS. Cardiovascular mechanosensitive ion channels-Translating physical forces into physiological responses. CURRENT TOPICS IN MEMBRANES 2021; 87:47-95. [PMID: 34696889 DOI: 10.1016/bs.ctm.2021.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cells and tissues are constantly exposed to mechanical stress. In order to respond to alterations in mechanical stimuli, specific cellular machinery must be in place to rapidly convert physical force into chemical signaling to achieve the desired physiological responses. Mechanosensitive ion channels respond to such physical stimuli in the order of microseconds and are therefore essential components to mechanotransduction. Our understanding of how these ion channels contribute to cellular and physiological responses to mechanical force has vastly expanded in the last few decades due to engineering ingenuities accompanying patch clamp electrophysiology, as well as sophisticated molecular and genetic approaches. Such investigations have unveiled major implications for mechanosensitive ion channels in cardiovascular health and disease. Therefore, in this chapter I focus on our present understanding of how biophysical activation of various mechanosensitive ion channels promotes distinct cell signaling events with tissue-specific physiological responses in the cardiovascular system. Specifically, I discuss the roles of mechanosensitive ion channels in mediating (i) endothelial and smooth muscle cell control of vascular tone, (ii) mechano-electric feedback and cell signaling pathways in cardiomyocytes and cardiac fibroblasts, and (iii) the baroreflex.
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Affiliation(s)
- Ibra S Fancher
- Department of Kinesiology and Applied Physiology, College of Health Sciences, University of Delaware, Newark, DE, United States.
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7
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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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8
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Ando J, Yamamoto K. Hemodynamic Forces, Endothelial Mechanotransduction, and Vascular Diseases. Magn Reson Med Sci 2021; 21:258-266. [PMID: 34024868 DOI: 10.2463/mrms.rev.2021-0018] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Cells in the tissues and organs of a living body are subjected to mechanical forces, such as pressure, friction, and tension from their surrounding environment. Cells are equipped with a mechanotransduction mechanism by which they perceive mechanical forces and transmit information into the cell interior, thereby causing physiological or pathogenetic mechano-responses. Endothelial cells (ECs) lining the inner surface of blood vessels are constantly exposed to shear stress caused by blood flow and a cyclic strain caused by intravascular pressure. A number of studies have shown that ECs are sensitive to changes in these hemodynamic forces and alter their morphology and function, sometimes by modifying gene expression. The mechanism of endothelial mechanotransduction has been elucidated, and the plasma membrane has recently been shown to act as a mechanosensor. The lipid order and cholesterol content of plasma membranes change immediately upon the exposure of ECs to hemodynamic forces, resulting in a change in membrane fluidity. These changes in a plasma membrane's physical properties affect the conformation and function of various ion channels, receptors, and microdomains (such as caveolae and primary cilia), thereby activating a wide variety of downstream signaling pathways. Such endothelial mechanotransduction works to maintain circulatory homeostasis; however, errors in endothelial mechanotransduction can cause abnormalities in vascular physiological function, leading to the initiation and progression of various vascular diseases, such as hypertension, thrombosis, aneurysms, and atherosclerosis. Recent advances in detailed imaging technology and computational fluid dynamics analysis have enabled us to evaluate the hemodynamic forces acting on vascular tissue accurately, contributing greatly to our understanding of vascular mechanotransduction and the pathogenesis of vascular diseases, as well as the development of new therapies for vascular diseases.
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Affiliation(s)
- Joji Ando
- Laboratory of Biomedical Engineering, School of Medicine, Dokkyo Medical University, Mibu
| | - Kimiko Yamamoto
- Laboratory of System Physiology, Department of Biomedical Engineering, Graduate School of Medicine, The University of Tokyo
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9
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Alghanem AF, Abello J, Maurer JM, Kumar A, Ta CM, Gunasekar SK, Fatima U, Kang C, Xie L, Adeola O, Riker M, Elliot-Hudson M, Minerath RA, Grueter CE, Mullins RF, Stratman AN, Sah R. The SWELL1-LRRC8 complex regulates endothelial AKT-eNOS signaling and vascular function. eLife 2021; 10:61313. [PMID: 33629656 PMCID: PMC7997661 DOI: 10.7554/elife.61313] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 02/22/2021] [Indexed: 12/15/2022] Open
Abstract
The endothelium responds to numerous chemical and mechanical factors in regulating vascular tone, blood pressure, and blood flow. The endothelial volume-regulated anion channel (VRAC) has been proposed to be mechanosensitive and thereby sense fluid flow and hydrostatic pressure to regulate vascular function. Here, we show that the leucine-rich repeat-containing protein 8a, LRRC8A (SWELL1), is required for VRAC in human umbilical vein endothelial cells (HUVECs). Endothelial LRRC8A regulates AKT-endothelial nitric oxide synthase (eNOS) signaling under basal, stretch, and shear-flow stimulation, forms a GRB2-Cav1-eNOS signaling complex, and is required for endothelial cell alignment to laminar shear flow. Endothelium-restricted Lrrc8a KO mice develop hypertension in response to chronic angiotensin-II infusion and exhibit impaired retinal blood flow with both diffuse and focal blood vessel narrowing in the setting of type 2 diabetes (T2D). These data demonstrate that LRRC8A regulates AKT-eNOS in endothelium and is required for maintaining vascular function, particularly in the setting of T2D.
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Affiliation(s)
- Ahmad F Alghanem
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States.,Eastern Region, King Abdullah International Medical Research Center, King Saud bin Abdulaziz University for Health Sciences, Al Hasa, Saudi Arabia
| | - Javier Abello
- Department of Cell Biology and Physiology, Washington University in St. Louis, School of Medicine, St. Louis, United States
| | - Joshua M Maurer
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
| | - Ashutosh Kumar
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
| | - Chau My Ta
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
| | - Susheel K Gunasekar
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
| | - Urooj Fatima
- Department of Internal Medicine, Cardiovascular Division, University of Iowa, Iowa City, United States
| | - Chen Kang
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
| | - Litao Xie
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
| | - Oluwaseun Adeola
- Department of Internal Medicine, Cardiovascular Division, University of Iowa, Iowa City, United States
| | - Megan Riker
- Department of Ophthalmology, University of Iowa, Carver College of Medicine, Iowa City, United States
| | - Macaulay Elliot-Hudson
- Department of Internal Medicine, Cardiovascular Division, University of Iowa, Iowa City, United States
| | - Rachel A Minerath
- Department of Internal Medicine, Cardiovascular Division, University of Iowa, Iowa City, United States
| | - Chad E Grueter
- Department of Internal Medicine, Cardiovascular Division, University of Iowa, Iowa City, United States
| | - Robert F Mullins
- Department of Ophthalmology, University of Iowa, Carver College of Medicine, Iowa City, United States
| | - Amber N Stratman
- Department of Cell Biology and Physiology, Washington University in St. Louis, School of Medicine, St. Louis, United States
| | - Rajan Sah
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States.,Center for Cardiovascular Research, Washington University, St Louis, United States
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10
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Kumar A, Xie L, Ta CM, Hinton AO, Gunasekar SK, Minerath RA, Shen K, Maurer JM, Grueter CE, Abel ED, Meyer G, Sah R. SWELL1 regulates skeletal muscle cell size, intracellular signaling, adiposity and glucose metabolism. eLife 2020; 9:58941. [PMID: 32930093 PMCID: PMC7541086 DOI: 10.7554/elife.58941] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 09/07/2020] [Indexed: 12/26/2022] Open
Abstract
Maintenance of skeletal muscle is beneficial in obesity and Type 2 diabetes. Mechanical stimulation can regulate skeletal muscle differentiation, growth and metabolism; however, the molecular mechanosensor remains unknown. Here, we show that SWELL1 (Lrrc8a) functionally encodes a swell-activated anion channel that regulates PI3K-AKT, ERK1/2, mTOR signaling, muscle differentiation, myoblast fusion, cellular oxygen consumption, and glycolysis in skeletal muscle cells. LRRC8A over-expression in Lrrc8a KO myotubes boosts PI3K-AKT-mTOR signaling to supra-normal levels and fully rescues myotube formation. Skeletal muscle-targeted Lrrc8a KO mice have smaller myofibers, generate less force ex vivo, and exhibit reduced exercise endurance, associated with increased adiposity under basal conditions, and glucose intolerance and insulin resistance when raised on a high-fat diet, compared to wild-type (WT) mice. These results reveal that the LRRC8 complex regulates insulin-PI3K-AKT-mTOR signaling in skeletal muscle to influence skeletal muscle differentiation in vitro and skeletal myofiber size, muscle function, adiposity and systemic metabolism in vivo.
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Affiliation(s)
- Ashutosh Kumar
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
| | - Litao Xie
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
| | - Chau My Ta
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
| | - Antentor O Hinton
- Fraternal Order of Eagles Diabetes Research Center, Iowa City, United States.,Division of Endocrinology and Metabolism, Iowa City, United States
| | - Susheel K Gunasekar
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
| | - Rachel A Minerath
- Fraternal Order of Eagles Diabetes Research Center, Iowa City, United States.,Division of Cardiology, University of Iowa, Iowa City, United States
| | - Karen Shen
- Program in Physical Therapy and Departments of Neurology, Biomedical Engineering and Orthopedic Surgery, Washington University in St. Louis, St. Louis, United States
| | - Joshua M Maurer
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
| | - Chad E Grueter
- Fraternal Order of Eagles Diabetes Research Center, Iowa City, United States.,Division of Cardiology, University of Iowa, Iowa City, United States
| | - E Dale Abel
- Fraternal Order of Eagles Diabetes Research Center, Iowa City, United States.,Division of Endocrinology and Metabolism, Iowa City, United States
| | - Gretchen Meyer
- Program in Physical Therapy and Departments of Neurology, Biomedical Engineering and Orthopedic Surgery, Washington University in St. Louis, St. Louis, United States
| | - Rajan Sah
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, United States
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11
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Ma T, Bai YP. The hydromechanics in arteriogenesis. Aging Med (Milton) 2020; 3:169-177. [PMID: 33103037 PMCID: PMC7574636 DOI: 10.1002/agm2.12101] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 02/23/2020] [Accepted: 02/23/2020] [Indexed: 12/15/2022] Open
Abstract
Coronary heart diseases are tightly associated with aging. Although current revascularization therapies, such as percutaneous coronary interventions (PCI) and coronary artery bypass graft (CABG), improve the clinical outcomes of patients with coronary diseases, their application and therapeutic effects are limited in elderly patients. Thus, developing novel therapeutic strategies, like prompting collateral development or the process of arteriogenesis, is necessary for the treatment of the elderly with coronary diseases. Arteriogenesis (ie, the vascular remodeling from pre‐existent arterioles to collateral conductance networks) functions as an essential compensation for tissue hypoperfusion caused by artery occlusion or stenosis, and its mechanisms remain to be elucidated. In this review, we will summarize the roles of the major hydromechanical components in laminar conditions in arteriogenesis, and discuss the potential effects of disturbed flow components in non‐laminar conditions.
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Affiliation(s)
- Tianqi Ma
- Department of Geriatric Medicine Xiangya Hospital Central South University Changsha China
| | - Yong-Ping Bai
- Department of Geriatric Medicine Xiangya Hospital Central South University Changsha China
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12
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Molladavoodi S, McMorran J, Gregory D. Mechanobiology of annulus fibrosus and nucleus pulposus cells in intervertebral discs. Cell Tissue Res 2019; 379:429-444. [PMID: 31844969 DOI: 10.1007/s00441-019-03136-1] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 11/03/2019] [Indexed: 02/07/2023]
Abstract
Low back pain (LBP) is a chronic condition that can affect up to 80% of the global population. It is the number one cause of disability worldwide and has enormous socioeconomic consequences. One of the main causes of this condition is intervertebral disc (IVD) degeneration. IVD degenerative processes and inflammation associated with it has been the subject of many studies in both tissue and cell level. It is believed that the phenotype of the resident cells within the IVD directly affects homeostasis of the tissue. At the same time, IVDs located between vertebral bodies of spine are under various mechanical loading conditions in vivo. Therefore, investigating how mechanical loading can affect the behaviour of IVD cells has been a subject of many research articles. In this review paper, following a brief explanation of the anatomy of the IVD and its resident cells, we compiled mechanobiological studies of IVD cells (specifically, annulus fibrosus and nucleus pulposus cells) and synthesized and discussed the key findings of the field.
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Affiliation(s)
- Sara Molladavoodi
- Department of Kinesiology and Physical Education, Wilfrid Laurier University, Waterloo, ON, Canada.,Department of Health Sciences, Wilfrid Laurier University, Waterloo, ON, Canada
| | - John McMorran
- Department of Kinesiology and Physical Education, Wilfrid Laurier University, Waterloo, ON, Canada
| | - Diane Gregory
- Department of Kinesiology and Physical Education, Wilfrid Laurier University, Waterloo, ON, Canada. .,Department of Health Sciences, Wilfrid Laurier University, Waterloo, ON, Canada.
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13
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Gunasekar SK, Xie L, Sah R. SWELL signalling in adipocytes: can fat 'feel' fat? Adipocyte 2019; 8:223-228. [PMID: 31112068 PMCID: PMC6768237 DOI: 10.1080/21623945.2019.1612223] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 04/18/2019] [Accepted: 04/19/2019] [Indexed: 01/04/2023] Open
Abstract
Obesity is becoming a global epidemic, predisposing to Type 2 diabetes, cardiovascular disease, fatty liver disease, pulmonary disease, osteoarthritis and cancer. Therefore, understanding the biology of adipocyte expansion in response to overnutrition is critical to devising strategies to treat obesity, and the associated burden of morbidity and mortality. Through exploratory patch-clamp experiments in freshly isolated primary murine and human adipocytes, we recently determined that SWELL1/LRRC8a, a leucine-rich repeat containing transmembrane protein, functionally encoded an ion channel signalling complex (the volume-regulated anion channel, or VRAC) on the adipocyte plasma membrane. The SWELL1-/LRRC8 channel complex activates in response to increases in adipocyte volume and in the context of obesity. SWELL1 is also required for insulin-PI3K-AKT2 signalling to regulate adipocyte growth and systemic glycaemia. This commentary delves further into our working models for the molecular mechanisms of adipocyte SWELL1-mediated VRAC activation, proposed signal transduction mechanisms, and putative impact on adipocyte hypertrophy during caloric excess.
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Affiliation(s)
- Susheel K. Gunasekar
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA
| | - Litao Xie
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA
| | - Rajan Sah
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, USA
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14
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Chatterjee S. Endothelial Mechanotransduction, Redox Signaling and the Regulation of Vascular Inflammatory Pathways. Front Physiol 2018; 9:524. [PMID: 29930512 PMCID: PMC5999754 DOI: 10.3389/fphys.2018.00524] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 04/24/2018] [Indexed: 12/13/2022] Open
Abstract
The endothelium that lines the interior of blood vessels is directly exposed to blood flow. The shear stress arising from blood flow is “sensed” by the endothelium and is “transduced” into biochemical signals that eventually control vascular tone and homeostasis. Sensing and transduction of physical forces occur via signaling processes whereby the forces associated with blood flow are “sensed” by a mechanotransduction machinery comprising of several endothelial cell elements. Endothelial “sensing” involves converting the physical cues into cellular signaling events such as altered membrane potential and activation of kinases, which are “transmission” signals that cause oxidant production. Oxidants produced are the “transducers” of the mechanical signals? What is the function of these oxidants/redox signals? Extensive data from various studies indicate that redox signals initiate inflammation signaling pathways which in turn can compromise vascular health. Thus, inflammation, a major response to infection or endotoxins, can also be initiated by the endothelium in response to various flow patterns ranging from aberrant flow to alteration of flow such as cessation or sudden increase in blood flow. Indeed, our work has shown that endothelial mechanotransduction signaling pathways participate in generation of redox signals that affect the oxidant and inflammation status of cells. Our goal in this review article is to summarize the endothelial mechanotransduction pathways that are activated with stop of blood flow and with aberrant flow patterns; in doing so we focus on the complex link between mechanical forces and inflammation on the endothelium. Since this “inflammation susceptible” phenotype is emerging as a trigger for pathologies ranging from atherosclerosis to rejection post-organ transplant, an understanding of the endothelial machinery that triggers these processes is very crucial and timely.
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Affiliation(s)
- Shampa Chatterjee
- Department of Physiology, Perelman School of Medicine, Institute for Environmental Medicine, University of Pennsylvania, Philadelphia, PA, United States
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15
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Roy S, Mathew MK. Fluid flow modulates electrical activity in cardiac hERG potassium channels. J Biol Chem 2018; 293:4289-4303. [PMID: 29305421 DOI: 10.1074/jbc.ra117.000432] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 12/28/2017] [Indexed: 01/01/2023] Open
Abstract
Fluid movement within the heart generates substantial shear forces, but the effect of this mechanical stress on the electrical activity of the human heart has not been examined. The fast component of the delayed rectifier potassium currents responsible for repolarization of the cardiac action potential, Ikr, is encoded by the human ether-a-go-go related gene (hERG) channel. Here, we exposed hERG1a channel-expressing HEK293T cells to laminar shear stress (LSS) and observed that this mechanical stress increased the whole-cell current by 30-40%. LSS shifted the voltage dependence of steady-state activation of the hERG channel to the hyperpolarizing direction, accelerated the time course of activation and recovery from inactivation, slowed down deactivation, and shifted the steady-state inactivation to the positive direction, all of which favored the hERG open state. In contrast, the time course of inactivation was faster, favoring the closed state. Using specific inhibitors of focal adhesion kinase, a regulator of mechano-transduction via the integrin pathway, we also found that the LSS-induced modulation of the whole-cell current depended on the integrin pathway. The hERG1b channel variant, which lacks the Per-Arnt-Sim (PAS) domain, and long QT syndrome-associated variants having point mutations in the PAS domain were unaffected by LSS, suggesting that the PAS domain in hERG1a channel may be involved in sensing mechanical shear stress. We conclude that a mechano-electric feedback pathway modulates hERG channel activity through the integrin pathway, indicating that mechanical forces in the heart influence its electrical activity.
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Affiliation(s)
- Samrat Roy
- From the National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065.,the Biocon Bristol Myers Squibb Research Center, Bengaluru 560099, and.,the School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT) University, Bhubaneswar 751024, India
| | - M K Mathew
- From the National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065,
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16
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García-Cardeña G, Slegtenhorst BR. Hemodynamic Control of Endothelial Cell Fates in Development. Annu Rev Cell Dev Biol 2017; 32:633-648. [PMID: 27712101 DOI: 10.1146/annurev-cellbio-100814-125610] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Biomechanical forces are emerging as critical regulators of embryogenesis, particularly in the developing cardiovascular system. From the onset of blood flow, the embryonic vasculature is continuously exposed to a variety of hemodynamic forces. These biomechanical stimuli are key determinants of vascular cell specification and remodeling and the establishment of vascular homeostasis. In recent years, major advances have been made in our understanding of mechano-activated signaling networks that control both spatiotemporal and structural aspects of vascular development. It has become apparent that a major site for mechanotransduction is situated at the interface of blood and the vessel wall and that this process is controlled by the vascular endothelium. In this review, we discuss the hemodynamic control of endothelial cell fates, focusing on arterial-venous specification, lymphatic development, and the endothelial-to-hematopoietic transition, and present some recent insights into the mechano-activated pathways driving these cell fate decisions in the developing embryo.
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Affiliation(s)
- Guillermo García-Cardeña
- Program in Developmental and Regenerative Biology, Harvard Medical School, Boston, Massachusetts 02115; .,Center for Excellence in Vascular Biology, Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts 02115
| | - Bendix R Slegtenhorst
- Program in Developmental and Regenerative Biology, Harvard Medical School, Boston, Massachusetts 02115; .,Center for Excellence in Vascular Biology, Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts 02115.,Department of Surgery, Erasmus MC-University Medical Center, 3015 CE, Rotterdam, The Netherlands
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17
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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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18
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Chistiakov DA, Orekhov AN, Bobryshev YV. Effects of shear stress on endothelial cells: go with the flow. Acta Physiol (Oxf) 2017; 219:382-408. [PMID: 27246807 DOI: 10.1111/apha.12725] [Citation(s) in RCA: 261] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 02/17/2016] [Accepted: 05/30/2016] [Indexed: 12/11/2022]
Abstract
Haemodynamic forces influence the functional properties of vascular endothelium. Endothelial cells (ECs) have a variety of receptors, which sense flow and transmit mechanical signals through mechanosensitive signalling pathways to recipient molecules that lead to phenotypic and functional changes. Arterial architecture varies greatly exhibiting bifurcations, branch points and curved regions, which are exposed to various flow patterns. Clinical studies showed that atherosclerotic plaques develop preferentially at arterial branches and curvatures, that is in the regions exposed to disturbed flow and shear stress. In the atheroprone regions, the endothelium has a proinflammatory phenotype associated with low nitric oxide production, reduced barrier function and increased proadhesive, procoagulant and proproliferative properties. Atheroresistant regions are exposed to laminar flow and high shear stress that induce prosurvival antioxidant signals and maintain the quiescent phenotype in ECs. Indeed, various flow patterns contribute to phenotypic and functional heterogeneity of arterial endothelium whose response to proatherogenic stimuli is differentiated. This may explain the preferential development of endothelial dysfunction in arterial sites with disturbed flow.
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Affiliation(s)
- D. A. Chistiakov
- Department of Medical Nanobiotechnology; Pirogov Russian State Medical University; Moscow Russia
| | - A. N. Orekhov
- Institute of General Pathology and Pathophysiology; Russian Academy of Medical Sciences; Moscow Russia
- Institute for Atherosclerosis Research; Skolkovo Innovative Center; Moscow Russia
- Department of Biophysics; Biological Faculty; Moscow State University; Moscow Russia
| | - Y. V. Bobryshev
- Institute of General Pathology and Pathophysiology; Russian Academy of Medical Sciences; Moscow Russia
- Faculty of Medicine and St Vincent's Centre for Applied Medical Research; University of New South Wales; Sydney NSW Australia
- School of Medicine; University of Western Sydney; Campbelltown NSW Australia
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19
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Hyman AJ, Tumova S, Beech DJ. Piezo1 Channels in Vascular Development and the Sensing of Shear Stress. CURRENT TOPICS IN MEMBRANES 2017; 79:37-57. [PMID: 28728823 DOI: 10.1016/bs.ctm.2016.11.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A critical point in mammalian development occurs before mid-embryogenesis when the heart starts to beat, pushing blood into the nascent endothelial lattice. This pushing force is a signal, detected by endothelial cells as a frictional force (shear stress) to trigger cellular changes that underlie the essential processes of vascular remodeling and expansion required for embryonic growth. The processes are complex and multifactorial and Piezo1 became a recognized player only 2years ago, 4years after Piezo1's initial discovery as a functional membrane protein. Piezo1 is now known to be critical in murine embryonic development just at the time when the pushing force is first detected by endothelial cells. Murine Piezo1 gene disruption in endothelial cells is embryonic lethal and mutations in human PIEZO1 associate with severe disease phenotype due to abnormal lymphatic vascular development. Piezo1 proteins coassemble to form calcium-permeable nonselective cationic channels, most likely as trimers. They are large proteins with little if any resemblance to other proteins or ion channel subunits. The channels appear to sense mechanical force directly, including the force imposed on endothelial cells by physiological shear stress. Here, we review current knowledge of Piezo1 in the vascular setting and discuss hypotheses about how it might serve its vascular functions and integrate with other mechanisms. Piezo1 is a new important player for investigators in this field and promises much as a basis for better understanding of vascular physiology and pathophysiology and perhaps also discovery of new therapies.
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Affiliation(s)
- A J Hyman
- University of Leeds, Leeds, United Kingdom
| | - S Tumova
- University of Leeds, Leeds, United Kingdom
| | - D J Beech
- University of Leeds, Leeds, United Kingdom
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20
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Wilson C, Lee MD, McCarron JG. Acetylcholine released by endothelial cells facilitates flow-mediated dilatation. J Physiol 2016; 594:7267-7307. [PMID: 27730645 PMCID: PMC5157078 DOI: 10.1113/jp272927] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 10/03/2016] [Indexed: 01/24/2023] Open
Abstract
KEY POINTS The endothelium plays a pivotal role in the vascular response to chemical and mechanical stimuli. The endothelium is exquisitely sensitive to ACh, although the physiological significance of ACh-induced activation of the endothelium is unknown. In the present study, we investigated the mechanisms of flow-mediated endothelial calcium signalling. Our data establish that flow-mediated endothelial calcium responses arise from the autocrine action of non-neuronal ACh released by the endothelium. ABSTRACT Circulating blood generates frictional forces (shear stress) on the walls of blood vessels. These frictional forces critically regulate vascular function. The endothelium senses these frictional forces and, in response, releases various vasodilators that relax smooth muscle cells in a process termed flow-mediated dilatation. Although some elements of the signalling mechanisms have been identified, precisely how flow is sensed and transduced to cause the release of relaxing factors is poorly understood. By imaging signalling in large areas of the endothelium of intact arteries, we show that the endothelium responds to flow by releasing ACh. Once liberated, ACh acts to trigger calcium release from the internal store in endothelial cells, nitric oxide production and artery relaxation. Flow-activated release of ACh from the endothelium is non-vesicular and occurs via organic cation transporters. ACh is generated following mitochondrial production of acetylCoA. Thus, we show ACh is an autocrine signalling molecule released from endothelial cells, and identify a new role for the classical neurotransmitter in endothelial mechanotransduction.
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Affiliation(s)
- Calum Wilson
- Strathclyde Institute of Pharmacy and Biomedical SciencesUniversity of StrathclydeSIPBS BuildingGlasgowUK
| | - Matthew D. Lee
- Strathclyde Institute of Pharmacy and Biomedical SciencesUniversity of StrathclydeSIPBS BuildingGlasgowUK
| | - John G. McCarron
- Strathclyde Institute of Pharmacy and Biomedical SciencesUniversity of StrathclydeSIPBS BuildingGlasgowUK
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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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22
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Abstract
Fluid shear stress is an important environmental cue that governs vascular physiology and pathology, but the molecular mechanisms that mediate endothelial responses to flow are only partially understood. Gating of ion channels by flow is one mechanism that may underlie many of the known responses. Here, we review the literature on endothelial ion channels whose activity is modulated by flow with an eye toward identifying important questions for future research.
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Affiliation(s)
- Kristin A Gerhold
- Department of Internal Medicine (Cardiology), Yale Cardiovascular Research Center, Yale University, New Haven, Connecticut; and
| | - Martin A Schwartz
- Department of Internal Medicine (Cardiology), Yale Cardiovascular Research Center, Yale University, New Haven, Connecticut; and Departments of Cell Biology and Biomedical Engineering, Yale University, New Haven, Connecticut
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23
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Schwingshackl A. The role of stretch-activated ion channels in acute respiratory distress syndrome: finally a new target? Am J Physiol Lung Cell Mol Physiol 2016; 311:L639-52. [PMID: 27521425 DOI: 10.1152/ajplung.00458.2015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 08/05/2016] [Indexed: 02/06/2023] Open
Abstract
Mechanical ventilation (MV) and oxygen therapy (hyperoxia; HO) comprise the cornerstones of life-saving interventions for patients with acute respiratory distress syndrome (ARDS). Unfortunately, the side effects of MV and HO include exacerbation of lung injury by barotrauma, volutrauma, and propagation of lung inflammation. Despite significant improvements in ventilator technologies and a heightened awareness of oxygen toxicity, besides low tidal volume ventilation few if any medical interventions have improved ARDS outcomes over the past two decades. We are lacking a comprehensive understanding of mechanotransduction processes in the healthy lung and know little about the interactions between simultaneously activated stretch-, HO-, and cytokine-induced signaling cascades in ARDS. Nevertheless, as we are unraveling these mechanisms we are gathering increasing evidence for the importance of stretch-activated ion channels (SACs) in the activation of lung-resident and inflammatory cells. In addition to the discovery of new SAC families in the lung, e.g., two-pore domain potassium channels, we are increasingly assigning mechanosensing properties to already known Na(+), Ca(2+), K(+), and Cl(-) channels. Better insights into the mechanotransduction mechanisms of SACs will improve our understanding of the pathways leading to ventilator-induced lung injury and lead to much needed novel therapeutic approaches against ARDS by specifically targeting SACs. This review 1) summarizes the reasons why the time has come to seriously consider SACs as new therapeutic targets against ARDS, 2) critically analyzes the physiological and experimental factors that currently limit our knowledge about SACs, and 3) outlines the most important questions future research studies need to address.
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24
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Natarajan M, Aravindan N, Sprague EA, Mohan S. Hemodynamic Flow-Induced Mechanotransduction Signaling Influences the Radiation Response of the Vascular Endothelium. Radiat Res 2016; 186:175-88. [PMID: 27387860 DOI: 10.1667/rr14410.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Hemodynamic shear stress is defined as the physical force exerted by the continuous flow of blood in the vascular system. Endothelial cells, which line the inner layer of blood vessels, sense this physiological force through mechanotransduction signaling and adapt to maintain structural and functional homeostasis. Hemodynamic flow, shear stress and mechanotransduction signaling are, therefore, an integral part of endothelial pathophysiology. Although this is a well-established concept in the cardiovascular field, it is largely dismissed in studies aimed at understanding radiation injury to the endothelium and subsequent cardiovascular complications. We and others have reported on the differential response of the endothelium when the cells are under hemodynamic flow shear compared with static culture. Further, we have demonstrated significant differences in the gene expression of static versus shear-stressed irradiated cells in four key pathways, reinforcing the importance of shear stress in understanding radiation injury of the endothelium. This article further emphasizes the influence of hemodynamic shear stress and the associated mechanotransduction signaling on physiological functioning of the vascular endothelium and underscores its significance in understanding radiation injury to the vasculature and associated cardiac complications. Studies of radiation effect on endothelial biology and its implication on cardiotoxicity and vascular complications thus far have failed to highlight the significance of these factors. Factoring in these integral parts of the endothelium will enhance our understanding of the contribution of the endothelium to radiation biology. Without such information, the current approaches to studying radiation-induced injury to the endothelium and its consequences in health and disease are limited.
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Affiliation(s)
| | - Natarajan Aravindan
- c Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104
| | - Eugene A Sprague
- b Medicine University of Texas Health Science Center, San Antonio, Texas 78229; and
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25
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Gross CM, Aggarwal S, Kumar S, Tian J, Kasa A, Bogatcheva N, Datar SA, Verin AD, Fineman JR, Black SM. Sox18 preserves the pulmonary endothelial barrier under conditions of increased shear stress. J Cell Physiol 2014; 229:1802-16. [PMID: 24677020 DOI: 10.1002/jcp.24633] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 03/26/2014] [Indexed: 01/13/2023]
Abstract
Shear stress secondary to increased pulmonary blood flow (PBF) is elevated in some children born with congenital cardiac abnormalities. However, the majority of these patients do not develop pulmonary edema, despite high levels of permeability inducing factors. Previous studies have suggested that laminar fluid shear stress can enhance pulmonary vascular barrier integrity. However, little is known about the mechanisms by which this occurs. Using microarray analysis, we have previously shown that Sox18, a transcription factor involved in blood vessel development and endothelial barrier integrity, is up-regulated in an ovine model of congenital heart disease with increased PBF (shunt). By subjecting ovine pulmonary arterial endothelial cells (PAEC) to laminar flow (20 dyn/cm(2) ), we identified an increase in trans-endothelial resistance (TER) across the PAEC monolayer that correlated with an increase in Sox18 expression. Further, the TER was also enhanced when Sox18 was over-expressed and attenuated when Sox18 expression was reduced, suggesting that Sox18 maintains the endothelial barrier integrity in response to shear stress. Further, we found that shear stress up-regulates the cellular tight junction protein, Claudin-5, in a Sox18 dependent manner, and Claudin-5 depletion abolished the Sox18 mediated increase in TER in response to shear stress. Finally, utilizing peripheral lung tissue of 4 week old shunt lambs with increased PBF, we found that both Sox18 and Claudin-5 mRNA and protein levels were elevated. In conclusion, these novel findings suggest that increased laminar flow protects endothelial barrier function via Sox18 dependent up-regulation of Claudin-5 expression.
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Affiliation(s)
- Christine M Gross
- Pulmonary Disease Program Vascular Biology Center, Georgia Regents University, Augusta, Georgia
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26
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Chatterjee S, Nieman GF, Christie JD, Fisher AB. Shear stress-related mechanosignaling with lung ischemia: lessons from basic research can inform lung transplantation. Am J Physiol Lung Cell Mol Physiol 2014; 307:L668-80. [PMID: 25239915 DOI: 10.1152/ajplung.00198.2014] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Cessation of blood flow represents a physical event that is sensed by the pulmonary endothelium leading to a signaling cascade that has been termed "mechanotransduction." This paradigm has clinical relevance for conditions such as pulmonary embolism, lung bypass surgery, and organ procurement and storage during lung transplantation. On the basis of our findings with stop of flow, we postulate that normal blood flow is "sensed" by the endothelium by virtue of its location at the interface of the blood and vessel wall and that this signal is necessary to maintain the endothelial cell membrane potential. Stop of flow is sensed by a "mechanosome" consisting of PECAM-VEGF receptor-VE cadherin that is located in the endothelial cell caveolae. Activation of the mechanosome results in endothelial cell membrane depolarization that in turn leads to activation of NADPH oxidase (NOX2) to generate reactive oxygen species (ROS). Endothelial depolarization additionally results in opening of T-type voltage-gated Ca(2+) channels, increased intracellular Ca(2+), and activation of nitric oxide (NO) synthase with resultant generation of NO. Increased NO causes vasodilatation whereas ROS provide a signal for neovascularization; however, with lung transplantation overproduction of ROS and NO can cause oxidative injury and/or activation of proteins that drive inflammation and cell death. Understanding the key events in the mechanosignaling cascade has important lessons for the design of strategies or interventions that may reduce injury during storage of donor lungs with the goal to increase the availability of lungs suitable for donation and thus improving access to lung transplantation.
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Affiliation(s)
- Shampa Chatterjee
- Institute for Environmental Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennyslvania;
| | - Gary F Nieman
- Department of Surgery, SUNY Upstate Medical University, Syracuse, New York; and
| | - Jason D Christie
- Pulmonary Allergy and Critical Care Division, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
| | - Aron B Fisher
- Institute for Environmental Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennyslvania
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27
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Du J, Ma X, Shen B, Huang Y, Birnbaumer L, Yao X. TRPV4, TRPC1, and TRPP2 assemble to form a flow-sensitive heteromeric channel. FASEB J 2014; 28:4677-85. [PMID: 25114176 DOI: 10.1096/fj.14-251652] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Transient receptor potential (TRP) channels, a superfamily of ion channels, can be divided into 7 subfamilies, including TRPV, TRPC, TRPP, and 4 others. Functional TRP channels are tetrameric complexes consisting of 4 pore-forming subunits. The purpose of this study was to explore the heteromerization of TRP subunits crossing different TRP subfamilies. Two-step coimmunoprecipitation (co-IP) and fluorescence resonance energy transfer (FRET) were used to determine the interaction of the different TRP subunits. Patch-clamp and cytosolic Ca(2+) measurements were used to determine the functional role of the ion channels in flow conditions. The analysis demonstrated the formation of a heteromeric TRPV4-C1-P2 complex in primary cultured rat mesenteric artery endothelial cells (MAECs) and HEK293 cells that were cotransfected with TRPV4, TRPC1, and TRPP2. In functional experiments, pore-dead mutants for each of these 3 TRP isoforms nearly abolished the flow-induced cation currents and Ca(2+) increase, suggesting that all 3 TRPs contribute to the ion permeation pore of the channels. We identified the first heteromeric TRP channels composed of subunits from 3 different TRP subfamilies. Functionally, this heteromeric TRPV4-C1-P2 channel mediates the flow-induced Ca(2+) increase in native vascular endothelial cells.
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Affiliation(s)
- Juan Du
- School of Biomedical Sciences and Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong, China; Department of Physiology, Anhui Medical University, He Fei, China; and
| | - Xin Ma
- School of Biomedical Sciences and Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong, China
| | - Bing Shen
- School of Biomedical Sciences and Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong, China; Department of Physiology, Anhui Medical University, He Fei, China; and
| | - Yu Huang
- School of Biomedical Sciences and Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong, China
| | - Lutz Birnbaumer
- National Institute of Environmental Health Sciences, U.S. National Institutes of Health, Research Triangle Park, North Carolina, USA
| | - Xiaoqiang Yao
- School of Biomedical Sciences and Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong, Hong Kong, China;
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28
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ZHOU TIAN, ZHENG YIMING, QIU JUHUI, HU JIANJUN, SUN DAMING, TANG CHAOJUN, WANG GUIXUE. ENDOTHELIAL MECHANOTRANSDUCTION MECHANISMS FOR VASCULAR PHYSIOLOGY AND ATHEROSCLEROSIS. J MECH MED BIOL 2014. [DOI: 10.1142/s0219519414300063] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Vascular physiology and disease progression, such as atherosclerosis, are mediated by hemodynamic force generated from blood flow. The hemodynamic force exerts on vascular endothelial cells (ECs), which could perceive the mechanical signals and transmit them into cell interior by multiple potential shear sensors, collectively known as mechanotransduction. However, we do not understand completely how these shear-sensitive components orchestrate physiological and atherosclerotic responses to shear stress. In this review, we provide an overview of biomechanical mechanisms underlying vascular physiology and atherosclerotic progression. Additionally, we summarize current evidences to illustrate that atherosclerotic lesions preferentially develop in arterial regions experiencing disturbance in blood flow, during which endothelial dysfunction is the initial event of atherosclerosis, inflammation plays dominant roles in atherosclerotic progression, and angiogenesis emerges as compensatory explanation for atherosclerotic plaque rupture. Especially in the presence of systemic risk factors (e.g., hyperlipidaemia, hypertension and hyperglycemia), the synergy between these systemic risk factors with hemodynamic factors aggravates atherosclerosis by co-stimulating some of these biomechanical events. Given the hemodynamic environment of vasculature, understanding how the rapid shear-mediated signaling, particularly in combination with systemic risk factors, contribute to atherosclerotic progression through endothelial dysfunction, inflammation and angiogenesis helps to elucidate the role for atherogenic shear stress in specifically localizing atherosclerotic lesions in arterial regions with disturbed flow.
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Affiliation(s)
- TIAN ZHOU
- Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Chongqing Engineering Laboratory in Vascular Implants, Bioengineering College of Chongqing University, Chongqing 400044, P. R. China
| | - YIMING ZHENG
- Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Chongqing Engineering Laboratory in Vascular Implants, Bioengineering College of Chongqing University, Chongqing 400044, P. R. China
| | - JUHUI QIU
- Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Chongqing Engineering Laboratory in Vascular Implants, Bioengineering College of Chongqing University, Chongqing 400044, P. R. China
| | - JIANJUN HU
- Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Chongqing Engineering Laboratory in Vascular Implants, Bioengineering College of Chongqing University, Chongqing 400044, P. R. China
| | - DAMING SUN
- Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Chongqing Engineering Laboratory in Vascular Implants, Bioengineering College of Chongqing University, Chongqing 400044, P. R. China
| | - CHAOJUN TANG
- Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Chongqing Engineering Laboratory in Vascular Implants, Bioengineering College of Chongqing University, Chongqing 400044, P. R. China
| | - GUIXUE WANG
- Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Chongqing Engineering Laboratory in Vascular Implants, Bioengineering College of Chongqing University, Chongqing 400044, P. R. China
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Zhang W, Wei P, Chen Y, Yang L, Jiang C, Jiang P, Chen D. Down-regulated expression of vimentin induced by mechanical stress in fibroblasts derived from patients with ossification of the posterior longitudinal ligament. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2014; 23:2410-5. [PMID: 24908253 DOI: 10.1007/s00586-014-3394-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 05/23/2014] [Accepted: 05/24/2014] [Indexed: 11/24/2022]
Abstract
PURPOSE The aim of this study was to investigate the potential role of vimentin in the signal transduction pathways initiated by mechanical stimulation that contribute to ossification of the posterior longitudinal ligament of the spine (OPLL). METHODS We investigated the effects of in vitro cyclic stretch on cultured spinal ligament cells derived from OPLL (OPLL cells) and non-OPLL (non-OPLL cells) patients. The expression levels of the osteoblast-specific genes encoding osteocalcin (OCN), alkaline phosphatase (ALP), and type I collagen (COL I) were assessed by semi-quantitative reverse transcription-polymerase chain reaction. Vimentin protein expression in OPLL cells was detected by Western blotting. Small interfering RNA (siRNA) interference targeting vimentin was performed in OPLL cells induced by mechanical stress, and the expression levels of OCN, ALP and COL I were assessed. RESULTS In response to mechanical stretch, the expression levels of OCN, ALP, and COL I were increased in OPLL cells, whereas no change was observed in non-OPLL cells. Furthermore, knockdown of vimentin protein expression by siRNA resulted in an increase in the mRNA expression levels of OCN, ALP, and COL I. CONCLUSION The down-regulation of vimentin induced by mechanical stress plays an important role in the progression of OPLL through the induction of osteogenic differentiation in OPLL cells.
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Affiliation(s)
- Wei Zhang
- Department of Orthopedics, Affiliated Hospital of North Sichuan Medical College, North Sichuan Medical College, Nanchong, 637007, China
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Chatterjee S, Fisher AB. Mechanotransduction in the endothelium: role of membrane proteins and reactive oxygen species in sensing, transduction, and transmission of the signal with altered blood flow. Antioxid Redox Signal 2014; 20:899-913. [PMID: 24328670 PMCID: PMC3924805 DOI: 10.1089/ars.2013.5624] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
SIGNIFICANCE Changes in shear stress associated with alterations in blood flow initiate a signaling cascade that modulates the vascular phenotype. Shear stress is "sensed" by the endothelium via a mechanosensitive complex on the endothelial cell (EC) membrane that has been characterized as a "mechanosome" consisting of caveolae, platelet endothelial cell adhesion molecule (PECAM), vascular endothelial growth factor receptor 2 (VEGFR2), vascular endothelial (VE)-cadherin, and possibly other elements. This shear signal is transduced by cell membrane ion channels and various kinases and results in the activation of NADPH oxidase (type 2) with the production of reactive oxygen species (ROS). RECENT ADVANCES The signaling cascade associated with stop of shear, as would occur in vivo with various obstructive pathologies, leads to cell proliferation and eventual revascularization. CRITICAL ISSUES AND FUTURE DIRECTIONS Although several elements of mechanosensing such as the sensing event, the transduction, transmission, and reception of the mechanosignal are now reasonably well understood, the links among these discrete steps in the pathway are not clear. Thus, identifying the mechanisms for the interaction of the K(ATP) channel, the kinases, and ROS to drive long-term adaptive responses in ECs is necessary. A critical re-examination of the signaling events associated with complex flow patterns (turbulent, oscillatory) under physiological conditions is also essential for the progress in the field. Since these complex shear patterns may be associated with an atherosclerosis susceptible phenotype, a specific challenge will be the pharmacological modulation of the responses to altered signaling events that occur at specific sites of disturbed or obstructed flow.
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Affiliation(s)
- Shampa Chatterjee
- Institute for Environmental Medicine, Perelman School of Medicine, University of Pennsylvania , Philadelphia, Pennsylvania
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31
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Khanna A, Kahle KT, Walcott BP, Gerzanich V, Simard JM. Disruption of ion homeostasis in the neurogliovascular unit underlies the pathogenesis of ischemic cerebral edema. Transl Stroke Res 2013; 5:3-16. [PMID: 24323726 DOI: 10.1007/s12975-013-0307-9] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 10/22/2013] [Accepted: 11/06/2013] [Indexed: 02/06/2023]
Abstract
Cerebral edema is a major cause of morbidity and mortality following ischemic stroke, but its underlying molecular pathophysiology is incompletely understood. Recent data have revealed the importance of ion flux via channels and transporters expressed in the neurogliovascular unit in the development of ischemia-triggered cytotoxic edema, vasogenic edema, and hemorrhagic conversion. Disruption of homeostatic mechanisms governing cell volume regulation and epithelial/endothelial ion transport due to ischemia-associated energy failure results in the thermodynamically driven re-equilibration of solutes and water across the CSF-blood and blood-brain barriers that ultimately increases the brain's extravascular volume. Additionally, hypoxia, inflammation, and other stress-triggered increases in the functional expression of ion channels and transporters normally expressed at low levels in the neurogliovascular unit cause disruptions in ion homeostasis that contribute to ischemic cerebral edema. Here, we review the pathophysiological significance of several molecular mediators of ion transport expressed in the neurogliovascular unit, including targets of existing FDA-approved drugs, which might be potential nodes for therapeutic intervention.
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dela Paz NG, Melchior B, Frangos JA. Early VEGFR2 activation in response to flow is VEGF-dependent and mediated by MMP activity. Biochem Biophys Res Commun 2013; 434:641-6. [PMID: 23583373 DOI: 10.1016/j.bbrc.2013.03.134] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 03/27/2013] [Indexed: 11/20/2022]
Abstract
Although several potential mechanosensors/mechanotransducers have been proposed, the precise mechanisms by which ECs sense and respond to mechanical forces and translate them into biochemical signals remains unclear. Here, we report that two major ligand-dependent tyrosine autophosphorylation sites of VEGFR2, Y1175 and Y1214, are rapidly activated by shear stress in human coronary artery endothelial cells (HCAECs). Neutralizing antibody against VEGFR2 not only abrogates flow-induced phosphorylation of these tyrosine residues, but also has a marked inhibitory effect on downstream eNOS activation. In situ proximity ligation assay revealed that VEGF and VEGFR2 are closely associated in HCAECs, and more importantly, this association is increased with flow. Finally, we show that flow-induced VEGFR2 activation is attenuated in the presence of the broad spectrum matrix metalloproteinase (MMP) inhibitor, GM6001. Taken together, our results suggest that a ligand-dependent mechanism involving the activity of MMPs plays a key role in the early, shear stress-induced activation of VEGFR2.
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Affiliation(s)
- Nathaniel G dela Paz
- La Jolla Bioengineering Institute, 3535 General Atomics Court, Suite 210, San Diego, CA 92121, USA.
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Abstract
Blood vessels alter their morphology and function in response to changes in blood flow, and their responses are based on blood flow detection by the vascular endothelium. Endothelial cells (ECs) covering the inner surface of blood vessels sense shear stress generated by flowing blood and transmit the signal into the interior of the cell, which evokes a cellular response. The EC response to shear stress is closely linked to the regulation of vascular tone, blood coagulation and fibrinolysis, angiogenesis, and vascular remodelling, and it plays an important role in maintaining the homoeostasis of the circulatory system. Impairment of the EC response to shear stress leads to the development of vascular diseases such as hypertension, thrombosis, aneurysms, and atherosclerosis. Rapid progress has been made in elucidating shear stress mechanotransduction by using in vitro methods that apply controlled levels of shear stress to cultured ECs in fluid-dynamically designed flow-loading devices. The results have revealed that shear stress is converted into intracellular biochemical signals that are mediated by a variety of membrane molecules and microdomains, including ion channels, receptors, G-proteins, adhesion molecules, the cytoskeleton, caveolae, the glycocalyx, and primary cilia, and that multiple downstream signalling pathways become activated almost simultaneously. Nevertheless, neither the shear-stress-sensing mechanisms nor the sensor molecules that initially sense shear stress are yet known. Their identification would contribute to a better understanding of the pathophysiology of the vascular diseases that occur in a blood flow-dependent manner and to the development of new treatments for them.
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Affiliation(s)
- Joji Ando
- Laboratory of Biomedical Engineering, School of Medicine, Dokkyo Medical University, 880 Kita-kobayashi, Mibu, Tochigi 321-0293, Japan.
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Hwang Y, Gouget CLM, Barakat AI. Mechanisms of cytoskeleton-mediated mechanical signal transmission in cells. Commun Integr Biol 2013; 5:538-42. [PMID: 23336020 PMCID: PMC3541317 DOI: 10.4161/cib.21633] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Recent experiments have demonstrated very rapid long-distance transmission of mechanical forces within cells. Because the speed of this transmission greatly exceeds that of reaction-diffusion signaling, it has been conjectured that it occurs via the propagation of elastic waves through the actin stress fiber network. To explore the plausibility of this conjecture, we recently developed a model of small amplitude stress fiber deformations in prestressed viscoelastic stress fibers subjected to external forces. The model results demonstrated that rapid mechanical signal transmission is only possible when the external force is applied orthogonal to the stress fiber axis and that the dynamics of this transmission are governed by a balance between the prestress in the stress fiber and the stress fiber's material viscosity. The present study, which is a follow-up on our previous model, uses dimensional analysis to: (1) further evaluate the plausibility of the elastic wave conjecture and (2) obtain insight into mechanical signal transmission dynamics in simple stress fiber networks. We show that the elastic wave scenario is likely not the mechanism of rapid mechanical signal transmission in actin stress fibers due to the highly viscoelastic character of these fibers. Our analysis also demonstrates that the time constant characterizing mechanical stimulus transmission is strongly dependent on the topology of the stress fiber network, implying that network organization plays an important role in determining the dynamics of cellular responsiveness to mechanical stimulation.
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Affiliation(s)
- Yongyun Hwang
- Hydrodynamics Laboratory (LadHyX); Ecole Polytechnique; CNRS UMR7646; Palaiseau, France
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Dutta AK, Woo K, Khimji AK, Kresge C, Feranchak AP. Mechanosensitive Cl- secretion in biliary epithelium mediated through TMEM16A. Am J Physiol Gastrointest Liver Physiol 2013; 304:G87-98. [PMID: 23104560 PMCID: PMC3543635 DOI: 10.1152/ajpgi.00154.2012] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Bile formation by the liver is initiated by canalicular transport at the hepatocyte membrane, leading to an increase in ductular bile flow. Thus, bile duct epithelial cells (cholangiocytes), which contribute to the volume and dilution of bile through regulated Cl(-) transport, are exposed to changes in flow and shear force at the apical membrane. The aim of the present study was to determine if fluid flow, or shear stress, is a signal regulating cholangiocyte transport. The results demonstrate that, in human and mouse biliary cells, fluid flow, or shear, increases Cl(-) currents and identify TMEM16A, a Ca(2+)-activated Cl(-) channel, as the operative channel. Furthermore, activation of TMEM16A by flow is dependent on PKCα through a process involving extracellular ATP, binding purinergic P2 receptors, and increases in intracellular Ca(2+) concentration. These studies represent the initial characterization of mechanosensitive Cl(-) currents mediated by TMEM16A. Identification of this novel mechanosensitive secretory pathway provides new insight into bile formation and suggests new therapeutic targets to enhance bile formation in the treatment of cholestatic liver disorders.
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Affiliation(s)
- Amal K. Dutta
- 1Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Kangmee Woo
- 1Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Al-karim Khimji
- 2Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Charles Kresge
- 1Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Andrew P. Feranchak
- 1Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas; and
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Vascular Endothelium. TISSUE FUNCTIONING AND REMODELING IN THE CIRCULATORY AND VENTILATORY SYSTEMS 2013. [DOI: 10.1007/978-1-4614-5966-8_9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Hwang Y, Barakat AI. Dynamics of mechanical signal transmission through prestressed stress fibers. PLoS One 2012; 7:e35343. [PMID: 22514731 PMCID: PMC3325979 DOI: 10.1371/journal.pone.0035343] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 03/15/2012] [Indexed: 01/14/2023] Open
Abstract
Transmission of mechanical stimuli through the actin cytoskeleton has been proposed as a mechanism for rapid long-distance mechanotransduction in cells; however, a quantitative understanding of the dynamics of this transmission and the physical factors governing it remains lacking. Two key features of the actin cytoskeleton are its viscoelastic nature and the presence of prestress due to actomyosin motor activity. We develop a model of mechanical signal transmission through prestressed viscoelastic actin stress fibers that directly connect the cell surface to the nucleus. The analysis considers both temporally stationary and oscillatory mechanical signals and accounts for cytosolic drag on the stress fibers. To elucidate the physical parameters that govern mechanical signal transmission, we initially focus on the highly simplified case of a single stress fiber. The results demonstrate that the dynamics of mechanical signal transmission depend on whether the applied force leads to transverse or axial motion of the stress fiber. For transverse motion, mechanical signal transmission is dominated by prestress while fiber elasticity has a negligible effect. Conversely, signal transmission for axial motion is mediated uniquely by elasticity due to the absence of a prestress restoring force. Mechanical signal transmission is significantly delayed by stress fiber material viscosity, while cytosolic damping becomes important only for longer stress fibers. Only transverse motion yields the rapid and long-distance mechanical signal transmission dynamics observed experimentally. For simple networks of stress fibers, mechanical signals are transmitted rapidly to the nucleus when the fibers are oriented largely orthogonal to the applied force, whereas the presence of fibers parallel to the applied force slows down mechanical signal transmission significantly. The present results suggest that cytoskeletal prestress mediates rapid mechanical signal transmission and allows temporally oscillatory signals in the physiological frequency range to travel a long distance without significant decay due to material viscosity and/or cytosolic drag.
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Affiliation(s)
- Yongyun Hwang
- Hydrodynamics Laboratory (LadHyX), Department of Mechanics, École Polytechnique, CNRS UMR7646, Palaiseau, France
| | - Abdul I. Barakat
- Hydrodynamics Laboratory (LadHyX), Department of Mechanics, École Polytechnique, CNRS UMR7646, Palaiseau, France
- Mechanical & Aerospace Engineering, University of California Davis, Davis, California, United States of America
- * E-mail:
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Morgan JT, Wood JA, Shah NM, Hughbanks ML, Russell P, Barakat AI, Murphy CJ. Integration of basal topographic cues and apical shear stress in vascular endothelial cells. Biomaterials 2012; 33:4126-35. [PMID: 22417618 DOI: 10.1016/j.biomaterials.2012.02.047] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Accepted: 02/26/2012] [Indexed: 11/19/2022]
Abstract
In vivo, vascular endothelial cells (VECs) are anchored to the underlying stroma through a specialization of the extracellular matrix, the basement membrane (BM) which provides a variety of substratum associated biophysical cues that have been shown to regulate fundamental VEC behaviors. VEC function and homeostasis are also influenced by hemodynamic cues applied to their apical surface. How the combination of these biophysical cues impacts fundamental VEC behavior remains poorly studied. In the present study, we investigated the impact of providing biophysical cues simultaneously to the basal and apical surfaces of human aortic endothelial cells (HAECs). Anisotropically ordered patterned surfaces of alternating ridges and grooves and isotropic holed surfaces of varying pitch (pitch = ridge or hole width + intervening groove or planar regions) were fabricated and seeded with HAECs. The cells were then subjected to a steady shear stress of 20 dyne/cm(2) applied either parallel or perpendicular to the direction of the ridge/groove topography. HAECs subjected to flow parallel to the ridge/groove topography exhibited protagonistic effects of the two stimuli on cellular orientation and elongation. In contrast, flow perpendicular to the substrate topography resulted in largely antagonistic effects. Interestingly, the behavior depended on the shape and size of the topographic features. HAECs exhibited a response that was less influenced by the substratum and primarily driven by flow on isotropically ordered holed surfaces of identical pitch to the anistropically ordered surfaces of alternating ridges and grooves. Simultaneous presentation of biophysical cues to the basal and apical aspects of cells also influenced nuclear orientation and elongation; however, the extent of nuclear realignment was more modest in comparison to cellular realignment regardless of the surface order of topographic features. Flow-induced HAEC migration was also influenced by the ridge/groove surface topographic features with significantly altered migration direction and increased migration tortuosity when flow was oriented perpendicular to the topography; this effect was also pitch-dependent. The present findings provide valuable insight into the interaction of biologically relevant apical and basal biophysical cues in regulating cellular behavior and promise to inform improved prosthetic design.
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Affiliation(s)
- Joshua T Morgan
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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40
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Stoner L, Sabatier MJ. Use of ultrasound for non-invasive assessment of flow-mediated dilation. J Atheroscler Thromb 2012; 19:407-21. [PMID: 22659525 DOI: 10.5551/jat.11395] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The pathological complications of atherosclerosis, namely heart attacks and strokes, remain the leading cause of mortality in the Western world. Preceding atherosclerosis is endothelial dysfunction. There is therefore interest in the application of non-invasive clinical tools to assess endothelial function. The flow-mediated dilation (FMD) test is the standard tool used to assess endothelial function. Reduced FMD is an early marker of atherosclerosis and has been noted for its capacity to predict future cardiovascular disease events. This review discusses the measurement of endothelial function using ultrasound, with a focus on the FMD technique.
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Affiliation(s)
- Lee Stoner
- School of Sport and Exercise, Massey University, Wellington, New Zealand.
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The importance of velocity acceleration to flow-mediated dilation. Int J Vasc Med 2012; 2012:589213. [PMID: 22315688 PMCID: PMC3270398 DOI: 10.1155/2012/589213] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Accepted: 10/12/2011] [Indexed: 01/22/2023] Open
Abstract
The validity of the flow-mediated dilation test has been questioned due to the lack of normalization to the primary stimulus, shear stress. Shear stress can be calculated using Poiseuille's law. However, little attention has been given to the most appropriate blood velocity parameter(s) for calculating shear stress. The pulsatile nature of blood flow exposes the endothelial cells to two distinct shear stimuli during the cardiac cycle: a large rate of change in shear at the onset of flow (velocity acceleration), followed by a steady component. The parameter typically entered into the Poiseuille's law equation to determine shear stress is time-averaged blood velocity, with no regard for flow pulsatility. This paper will discuss (1) the limitations of using Posieuille's law to estimate shear stress and (2) the importance of the velocity profile-with emphasis on velocity acceleration-to endothelial function and vascular tone.
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Browning EA, Chatterjee S, Fisher AB. Stop the flow: a paradigm for cell signaling mediated by reactive oxygen species in the pulmonary endothelium. Annu Rev Physiol 2011; 74:403-24. [PMID: 22077215 DOI: 10.1146/annurev-physiol-020911-153324] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The lung endothelium is exposed to mechanical stimuli through shear stress arising from blood flow and responds to altered shear by activation of NADPH (NOX2) to generate reactive oxygen species (ROS). This review describes the pathway for NOX2 activation and the downstream ROS-mediated signaling events on the basis of studies of isolated lungs and flow-adapted endothelial cells in vitro that are subjected to acute flow cessation (ischemia). Altered mechanical stress is detected by a cell-associated complex involving caveolae and other membrane proteins that results in endothelial cell membrane depolarization and then the activation of specific kinases that lead to the assembly of NOX2 components. ROS generated by this enzyme amplify the mechanosignal within the endothelial cell to regulate activation and/or synthesis of proteins that participate in cell growth, proliferation, differentiation, apoptosis, and vascular remodeling. These responses indicate an important role for NOX2-derived ROS associated with mechanotransduction in promoting vascular homeostasis.
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Affiliation(s)
- Elizabeth A Browning
- Institute for Environmental Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
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Yamamoto K, Ando J. New molecular mechanisms for cardiovascular disease:blood flow sensing mechanism in vascular endothelial cells. J Pharmacol Sci 2011; 116:323-31. [PMID: 21757846 DOI: 10.1254/jphs.10r29fm] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Endothelial cells (ECs) lining blood vessels have a variety of functions and play a critical role in the homeostasis of the circulatory system. It has become clear that biomechanical forces generated by blood flow regulate EC functions. ECs are in direct contact with blood flow and exposed to shear stress, a frictional force generated by flowing blood. A number of recent studies have revealed that ECs recognize changes in shear stress and transmit signals to the interior of the cell, which leads to cell responses that involve changes in cell morphology, cell function, and gene expression. These EC responses to shear stress are thought to play important roles in blood flow-dependent phenomena such as vascular tone control, angiogenesis, vascular remodeling, and atherogenesis. Much research has been done on shear stress sensing and signal transduction, and their molecular mechanisms are gradually becoming understood. However, much remains uncertain, and many candidates have been proposed for shear stress sensors. More extensive studies of vascular mechanobiology should increase our understanding of the molecular basis of the blood flow-mediated control of vascular functions.
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Affiliation(s)
- Kimiko Yamamoto
- Laboratory of System Physiology, Department of Biomedical Engineering, Graduate School of Medicine, University of Tokyo, Japan.
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Callies C, Fels J, Liashkovich I, Kliche K, Jeggle P, Kusche-Vihrog K, Oberleithner H. Membrane potential depolarization decreases the stiffness of vascular endothelial cells. J Cell Sci 2011; 124:1936-42. [PMID: 21558418 DOI: 10.1242/jcs.084657] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The stiffness of vascular endothelial cells is crucial to mechanically withstand blood flow and, at the same time, to control deformation-dependent nitric oxide release. However, the regulation of mechanical stiffness is not yet understood. There is evidence that a possible regulator is the electrical plasma membrane potential difference. Using a novel technique that combines fluorescence-based membrane potential recordings with atomic force microscopy (AFM)-based stiffness measurements, the present study shows that membrane depolarization is associated with a decrease in the stiffness of endothelial cells. Three different depolarization protocols were applied, all of which led to a similar and significant decrease in cell stiffness, independently of changes in cell volume. Moreover, experiments using the actin-destabilizing agent cytochalasin D indicated that depolarization acts by affecting the cortical actin cytoskeleton. A model is proposed whereby a change of the electrical field across the plasma membrane is directly sensed by the submembranous actin network, regulating the actin polymerization:depolymerization ratio and thus cell stiffness. This depolarization-induced decrease in the stiffness of endothelial cells could play a role in flow-mediated nitric-oxide-dependent vasodilation.
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Affiliation(s)
- Chiara Callies
- Institute of Physiology II, University of Münster, Robert-Koch-Str. 27b, 48149 Münster, Germany.
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Kefaloyianni E, Coetzee WA. Transcriptional remodeling of ion channel subunits by flow adaptation in human coronary artery endothelial cells. J Vasc Res 2011; 48:357-67. [PMID: 21389733 DOI: 10.1159/000323475] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Accepted: 11/23/2010] [Indexed: 12/20/2022] Open
Abstract
Endothelial cells (ECs) are constantly exposed to blood flow-induced shear forces in the vessels and this is a major determinant of endothelial function. Ion channels have a major role in endothelial function and in the control of vascular tone. We hypothesized that shear force is a general regulator of ion channel expression, which will have profound effects on endothelial function. We examined this hypothesis using large-scale quantitative real-time RT-PCR. Human coronary artery ECs were exposed to two levels of flow-induced shear stress for 24 h, while control cells were grown under static conditions. The expression of ion channel subunits was compared between control and flow-adapted cells. We used primers against 55 ion channel and exchanger subunits and were able to detect 54 subunits. Five dyn/cm(2) of shear induced downregulation of 1 (NCX1) and upregulation of 18 subunits, including K(Ca)2.2, K(Ca)2.3, CX37, K(v)1.5 and HCN2. Fifteen dyn/cm(2) of shear stress induced the expression of 30 ion channel subunits, including K(Ca)2.3, K(Ca)2.2, CX37, K(ir)2.3 and K(Ca)3.1. Our data demonstrate that substantial remodeling of endothelial ion channel subunit expression occurs with flow adaptation and suggest that altered ion channel expression may significantly contribute to vascular pathology associated with flow-induced alterations.
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Affiliation(s)
- Eirini Kefaloyianni
- Department of Pediatrics, New York University School of Medicine, New York, NY 10016, USA
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46
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Dynamic modeling for flow-activated chloride-selective membrane current in vascular endothelial cells. Biomech Model Mechanobiol 2010; 10:743-54. [DOI: 10.1007/s10237-010-0270-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2010] [Accepted: 10/25/2010] [Indexed: 10/18/2022]
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47
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Hemodynamic forces in endothelial dysfunction and vascular aging. Exp Gerontol 2010; 46:185-8. [PMID: 20888896 DOI: 10.1016/j.exger.2010.09.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Revised: 09/20/2010] [Accepted: 09/21/2010] [Indexed: 01/28/2023]
Abstract
Aging is a key risk factor associated with the onset of cardiovascular disease. Notably, vascular aging and cardiovascular disease are both associated with endothelial dysfunction, or a marked decrease in production and bioavailability the vasodilator of nitric oxide (NO). As a result of decreased nitric oxide availability, aging vessels often exhibit endothelial cell senescence and increased oxidative stress. One of the most potent activators of NO production is fluid shear stress produced by blood flow. Interestingly, age-related decrease in NO production partially results from endothelial insensitivity to shear stress. While the endothelial cell response to fluid shear stress has been well characterized in recent years, the exact mechanisms of how the mechanical force of fluid shear stress is converted into intracellular biochemical signals are relatively unknown. Therefore, gaining a better knowledge of mechanosignaling events in endothelial cells may prove to be beneficial for developing potential therapies for cardiovascular diseases.
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48
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Dahl KN, Kalinowski A, Pekkan K. Mechanobiology and the microcirculation: cellular, nuclear and fluid mechanics. Microcirculation 2010; 17:179-91. [PMID: 20374482 DOI: 10.1111/j.1549-8719.2009.00016.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Endothelial cells are stimulated by shear stress throughout the vasculature and respond with changes in gene expression and by morphological reorganization. Mechanical sensors of the cell are varied and include cell surface sensors that activate intracellular chemical signaling pathways. Here, possible mechanical sensors of the cell including reorganization of the cytoskeleton and the nucleus are discussed in relation to shear flow. A mutation in the nuclear structural protein lamin A, related to Hutchinson-Gilford progeria syndrome, is reviewed specifically as the mutation results in altered nuclear structure and stiffer nuclei; animal models also suggest significantly altered vascular structure. Nuclear and cellular deformation of endothelial cells in response to shear stress provides partial understanding of possible mechanical regulation in the microcirculation. Increasing sophistication of fluid flow simulations inside the vessel is also an emerging area relevant to the microcirculation as visualization in situ is difficult. This integrated approach to study--including medicine, molecular and cell biology, biophysics and engineering--provides a unique understanding of multi-scale interactions in the microcirculation.
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Affiliation(s)
- Kris Noel Dahl
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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Abstract
Endothelial cells (ECs) lining blood vessel walls respond to shear stress, a fluid mechanical force generated by flowing blood, and the EC responses play an important role in the homeostasis of the circulatory system. Abnormal EC responses to shear stress impair various vascular functions and lead to vascular diseases, including hypertension, thrombosis, and atherosclerosis. Bioengineering approaches in which cultured ECs are subjected to shear stress in fluid-dynamically designed flow-loading devices have been widely used to analyze EC responses at the cellular and molecular levels. Remarkable progress has been made, and the results have shown that ECs alter their morphology, function, and gene expression in response to shear stress. Shear stress affects immature cells, as well as mature ECs, and promotes differentiation of bone-marrow-derived endothelial progenitor cells and embryonic stem cells into ECs. Much research has been done on shear stress sensing and signal transduction, and their molecular mechanisms are gradually coming to be understood. However, much remains uncertain, and many candidates have been proposed for shear stress sensors. More extensive studies of vascular mechanobiology should increase our understanding of the molecular basis of the blood-flow-mediated control of vascular functions.
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Affiliation(s)
- Joji Ando
- Laboratory of Biomedical Engineering, School of Medicine, Dokkyo Medical University, Tochigi, Japan.
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Pan S. Molecular mechanisms responsible for the atheroprotective effects of laminar shear stress. Antioxid Redox Signal 2009; 11:1669-82. [PMID: 19309258 PMCID: PMC2842586 DOI: 10.1089/ars.2009.2487] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The endothelium lining the inner surface of blood vessels of the cardiovascular system is constantly exposed to hemodynamic shear stress. The interaction between endothelial cells and hemodynamic shear stress has critical implications for atherosclerosis. Regions of arterial narrowing, curvatures, and bifurcations are especially susceptible to atherosclerotic lesion formation. In such areas, endothelial cells experience low, or oscillatory, shear stress. Corresponding changes in endothelial cell structure and function make them susceptible to the initiation and development of atherosclerosis. In contrast, blood flow with high laminar shear stress activates signal transductions as well as gene and protein expressions that play important roles in vascular homeostasis. In response to laminar shear stress, the release of vasoactive substances such as nitric oxide and prostacyclin decreases permeability to plasma lipoproteins as well as the adhesion of leukocytes, and inhibits smooth muscle cell proliferation and migration. In summary, different flow patterns directly determine endothelial cell morphology, metabolism, and inflammatory phenotype through signal transduction and gene and protein expression. Thus, high laminar shear stress plays a key role in the prevention of atherosclerosis through its regulation of vascular tone and long-term maintenance of the integrity and function of endothelial cells.
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Affiliation(s)
- Shi Pan
- Aab Cardiovascular Research Institute, University of Rochester, School of Medicine and Dentistry, Rochester, New York 14642, USA.
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