1
|
Mendez J, Toker A. Minimizing Shear Stress in Cell Signaling Studies. Curr Protoc 2024; 4:e1019. [PMID: 38506433 DOI: 10.1002/cpz1.1019] [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] [Indexed: 03/21/2024]
Abstract
Cellular signal transduction comprises a complex series of biochemical reactions by which extracellular signals such as growth factors, hormones, cytokines, and neurotransmitters are translated into specific intracellular responses. Signal transduction is mediated by protein kinase phosphorylation cascades that culminate in the regulation of numerous cellular responses, including division, differentiation, migration, and survival. Importantly, signal relay pathways are dysregulated in human diseases, making the study of signal transduction important for both uncovering basic biology and understanding pathophysiology. Established laboratory cell culture models are useful for studying signal transduction mechanisms, but differences in sample handling procedures can introduce unwanted variability in experimental outcomes and conclusions. One such potential source of experimental variability is the introduction of fluid shear stress upon handling of tissue culture cells. Fluid shear stress triggers a wide range of cellular responses in adherent cell culture, including stimulating the production of cyclic AMP, potentiating the activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), and ultimately inducing changes in the gene expression of growth and remodeling factors. Further, mechanical stress on cells is physiologically relevant to the development of many pathologies. Here, we describe a detailed protocol for cell lysis and protein extraction that minimizes shear stress induced by classical cell harvest protocols. We also highlight the impact of fluid shear stress by using immunoblotting to assess ERK pathway activation as a readout for this protocol. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Gentle cell lysis and protein extraction Basic Protocol 2: Immunoblotting for cell signaling readouts by SDS-PAGE.
Collapse
Affiliation(s)
- Josefina Mendez
- Department of Pathology and Cancer Center, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Alex Toker
- Department of Pathology and Cancer Center, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| |
Collapse
|
2
|
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.
Collapse
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.
| |
Collapse
|
3
|
Zhang X, Huk DJ, Wang Q, Lincoln J, Zhao Y. A microfluidic shear device that accommodates parallel high and low stress zones within the same culturing chamber. BIOMICROFLUIDICS 2014; 8:054106. [PMID: 25332743 PMCID: PMC4189595 DOI: 10.1063/1.4894783] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 08/26/2014] [Indexed: 05/02/2023]
Abstract
Fluid shear stress (FSS) plays a critical role in regulating endothelium function and maintaining vascular homeostasis. Current microfluidic devices for studying FSS effects on cells either separate high shear stress zone and low shear stress zone into different culturing chambers, or arranging the zones serially along the flow direction, which complicates subsequent data interpretation. In this paper, we report a diamond shaped microfluidic shear device where the high shear stress zone and the low shear stress zone are arranged in parallel within one culturing chamber. Since the zones with different shear stress magnitudes are aligned normal to the flow direction, the cells in one stress group are not substantially affected by the flow-induced cytokine/chemokine releases by cells in the other group. Cell loading experiments using human umbilical vein endothelial cells show that the device is able to reveal stress magnitude-dependent and loading duration-dependent cell responses. The co-existence of shear stress zones with varied magnitudes within the same culturing chamber not only ensures that all the cells are subject to the identical culturing conditions, but also allows the resemblance of the differential shear stress pattern in natural arterial conditions. The device is expected to provide a new solution for studying the effects of heterogeneous hemodynamic patterns in the onset and progression of various vascular diseases.
Collapse
Affiliation(s)
- X Zhang
- Laboratory for Biomedical Microsystems, Department of Biomedical Engineering, The Ohio State University , Columbus, Ohio 43210, USA
| | - D J Huk
- The Heart Center and Nationwide Children's Hospital Research Institute , Columbus, Ohio 43205, USA
| | - Q Wang
- Laboratory for Biomedical Microsystems, Department of Biomedical Engineering, The Ohio State University , Columbus, Ohio 43210, USA
| | | | - Y Zhao
- Laboratory for Biomedical Microsystems, Department of Biomedical Engineering, The Ohio State University , Columbus, Ohio 43210, USA
| |
Collapse
|
4
|
Tarbell JM, Shi ZD, Dunn J, Jo H. Fluid Mechanics, Arterial Disease, and Gene Expression. ANNUAL REVIEW OF FLUID MECHANICS 2014; 46:591-614. [PMID: 25360054 PMCID: PMC4211638 DOI: 10.1146/annurev-fluid-010313-141309] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
This review places modern research developments in vascular mechanobiology in the context of hemodynamic phenomena in the cardiovascular system and the discrete localization of vascular disease. The modern origins of this field are traced, beginning in the 1960s when associations between flow characteristics, particularly blood flow-induced wall shear stress, and the localization of atherosclerotic plaques were uncovered, and continuing to fluid shear stress effects on the vascular lining endothelial) cells (ECs), including their effects on EC morphology, biochemical production, and gene expression. The earliest single-gene studies and genome-wide analyses are considered. The final section moves from the ECs lining the vessel wall to the smooth muscle cells and fibroblasts within the wall that are fluid me chanically activated by interstitial flow that imposes shear stresses on their surfaces comparable with those of flowing blood on EC surfaces. Interstitial flow stimulates biochemical production and gene expression, much like blood flow on ECs.
Collapse
Affiliation(s)
- John M Tarbell
- Department of Biomedical Engineering, The City College of New York, New York, NY 10031
| | - Zhong-Dong Shi
- Developmental Biology Program, Sloan-Kettering Institute, New York, NY 10065
| | - Jessilyn Dunn
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30322
| | - Hanjoong Jo
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30322
| |
Collapse
|
5
|
Qiu J, Zheng Y, Hu J, Liao D, Gregersen H, Deng X, Fan Y, Wang G. Biomechanical regulation of vascular smooth muscle cell functions: from in vitro to in vivo understanding. J R Soc Interface 2013; 11:20130852. [PMID: 24152813 DOI: 10.1098/rsif.2013.0852] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Vascular smooth muscle cells (VSMCs) have critical functions in vascular diseases. Haemodynamic factors are important regulators of VSMC functions in vascular pathophysiology. VSMCs are physiologically active in the three-dimensional matrix and interact with the shear stress sensor of endothelial cells (ECs). The purpose of this review is to illustrate how haemodynamic factors regulate VSMC functions under two-dimensional conditions in vitro or three-dimensional co-culture conditions in vivo. Recent advances show that high shear stress induces VSMC apoptosis through endothelial-released nitric oxide and low shear stress upregulates VSMC proliferation and migration through platelet-derived growth factor released by ECs. This differential regulation emphasizes the need to construct more actual environments for future research on vascular diseases (such as atherosclerosis and hypertension) and cardiovascular tissue engineering.
Collapse
Affiliation(s)
- Juhui Qiu
- Key Laboratory of Biorheological Science and Technology (Chongqing University), Ministry of Education, Chongqing Engineering Laboratory in Vascular Implants, College of Bioengineering, Chongqing University, , Chongqing 400044, People's Republic of China
| | | | | | | | | | | | | | | |
Collapse
|
6
|
Liu B, Zhang JN, Pu PY. Expressions of PDGF-B and collagen type III in the remodeling of experimental saccular aneurysm in rats. Neurol Res 2013; 30:632-8. [DOI: 10.1179/174313208x291595] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
|
7
|
Gazit AZ, Canter CE. Impact of pulmonary vascular resistances in heart transplantation for congenital heart disease. Curr Cardiol Rev 2013; 7:59-66. [PMID: 22548028 PMCID: PMC3197090 DOI: 10.2174/157340311797484213] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Revised: 05/23/2011] [Accepted: 06/27/2011] [Indexed: 02/02/2023] Open
Abstract
Congenital heart disease is one of the major diagnoses in pediatric heart transplantation recipients of all age groups. Assessment of pulmonary vascular resistance in these patients prior to transplantation is crucial to determine their candidacy, however, it is frequently inaccurate because of their abnormal anatomy and physiology. This problem places them at significant risk for pulmonary hypertension and right ventricular failure post transplantation. The pathophysiology of pulmonary vascular disease in children with congenital heart disease depends on their pulmonary blood flow patterns, systemic ventricle function, as well as semilunar valves and atrioventricular valves structure and function. In our review we analyze the pathophysiology of pulmonary vascular disease in children with congenital heart disease and end-stage heart failure, and outline the state of the art pre-transplantation medical and surgical management to achieve reverse remodeling of the pulmonary vasculature by using pulmonary vasodilators and mechanical circulatory support.
Collapse
Affiliation(s)
- Avihu Z Gazit
- Divisions of Critical Care and Cardiology, Department of Pediatrics, Saint Louis Children's Hospital, Washington University in Saint Louis, Missouri, USA.
| | | |
Collapse
|
8
|
High wall shear stress and spatial gradients in vascular pathology: a review. Ann Biomed Eng 2012; 41:1411-27. [PMID: 23229281 DOI: 10.1007/s10439-012-0695-0] [Citation(s) in RCA: 232] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Accepted: 11/06/2012] [Indexed: 12/18/2022]
Abstract
Cardiovascular pathologies such as intracranial aneurysms (IAs) and atherosclerosis preferentially localize to bifurcations and curvatures where hemodynamics are complex. While extensive knowledge about low wall shear stress (WSS) has been generated in the past, due to its strong relevance to atherogenesis, high WSS (typically >3 Pa) has emerged as a key regulator of vascular biology and pathology as well, receiving renewed interests. As reviewed here, chronic high WSS not only stimulates adaptive outward remodeling, but also contributes to saccular IA formation (at bifurcation apices or outer curves) and atherosclerotic plaque destabilization (in stenosed vessels). Recent advances in understanding IA pathogenesis have shed new light on the role of high WSS in pathological vascular remodeling. In complex geometries, high WSS can couple with significant spatial WSS gradient (WSSG). A combination of high WSS and positive WSSG has been shown to trigger aneurysm initiation. Since endothelial cells (ECs) are sensors of WSS, we have begun to elucidate EC responses to high WSS alone and in combination with WSSG. Understanding such responses will provide insight into not only aneurysm formation, but also plaque destabilization and other vascular pathologies and potentially lead to improved strategies for disease management and novel targets for pharmacological intervention.
Collapse
|
9
|
Patrick CW, McIntire LV. Fluid Shear Stress Effects on Endothelial Cell Cytosolic pH. ACTA ACUST UNITED AC 2011; 1:53-70. [PMID: 19877915 DOI: 10.1089/ten.1995.1.53] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Fluid flow can modulate endothelial cell intracellular pH (pH(i)). Venous and arterial shear stresses of 1.4 and 14 dyn/cm2, respectively, induced intracellular acidification. The kinetics of the process and magnitude of acidification were dependent on the level of shear stress. Endothelial cells exposed to a venous shear stress were able to recover from the acidification, whereas cells exposed to an arterial shear stress remained acidic. Addition of SITS (1 mM), a HCO(3) (-)/CI(-) exchange inhibitor, greatly reduced the shear stress induced acidification, suggesting that the HCO(3) (-)/C1(-) exchanger is activated by shear stress. Shear stress may activate the exchanger by lowering the [HCO(3) (-)] at the cell surface via convective mass transfer. Altering the HCO(3) (-) gradient across the cell membrane activates the exchanger and, as a consequence, results in intracellular acidification. Perfusion with media containing ATP (10 microM) altered the kinetics of flow-induced acidification observed at both shear stress levels. ATP modulation of pH(i) may be coupled to the rise in [Ca(2+)](j) known to occur with ATP stimulation. To summarize, media perfusion induces intracellular acidification in endothelial cells, and there is evidence to suggest that pH(i) may serve as a second messenger to modulate flow associated changes in endothelial cell metabolism.
Collapse
Affiliation(s)
- C W Patrick
- Cox Laboratory for Biomedical Engineering, Institute of Biosciences and Bioengineering, Rice University, Houston, Texas 77005-1892
| | | |
Collapse
|
10
|
Van Ijzendoorn SC, Heemskerk JW, Reutelingsperger CP. Interactions between Endothelial Cells and Blood Platelets. ACTA ACUST UNITED AC 2009. [DOI: 10.3109/10623329509053385] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
|
11
|
Goettsch W, Augustin HG, Morawietz H. Down-Regulation of Endothelial EphrinB2 Expression by Laminar Shear Stress. ACTA ACUST UNITED AC 2009; 11:259-65. [PMID: 15763946 DOI: 10.1080/10623320490904151] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The EphB receptors and their ephrinB ligands are involved in vascular assembly and differentiation. In this study, the authors analyzed the regulation of ephrinB2 and EphB4 in response to laminar shear stress in human endothelial cells. In order to simulate different flow conditions in vitro, human endothelial cells were exposed to laminar shear stress (1 to 50 dyn/cm2 for up to 24 h) in a cone-and-plate viscometer. EphrinB2 mRNA expression is down-regulated by arterial, but not by venous, laminar shear stress in a dose-dependent manner in primary cultures of human umbilical vein endothelial cells (HUVECs) (maximum at 30 dyn/cm2, 24 h: 46% +/- 4%of internal control without shear stress, n = 16, p < .05). The down-regulation of ephrinB2 by arterial shear stress is blocked by the protein kinase C inhibitor RO-31-8220. A similar shear stress-dependent down-regulation of ephrin-B2 can be found in human coronary artery endothelial cells (HCAECs). Chronic application of laminar shear stress does not affect EphB4 expression in venous and arterial endothelial cells. The down-regulation of ephrinB2 in response to laminar shear stress may contribute to the differentiation of endothelial cells into a nonactivated phenotype.
Collapse
Affiliation(s)
- Winfried Goettsch
- Department of Vascular Endothelium and Microcirculation, Medical Faculty Carl Gustav Carus, University of Technology Dresden, Dresden, Germany
| | | | | |
Collapse
|
12
|
White CR, Frangos JA. The shear stress of it all: the cell membrane and mechanochemical transduction. Philos Trans R Soc Lond B Biol Sci 2007; 362:1459-67. [PMID: 17569643 PMCID: PMC2440408 DOI: 10.1098/rstb.2007.2128] [Citation(s) in RCA: 185] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
As the inner lining of the vessel wall, vascular endothelial cells are poised to act as a signal transduction interface between haemodynamic forces and the underlying vascular smooth-muscle cells. Detailed analyses of fluid mechanics in atherosclerosis-susceptible regions of the vasculature reveal a strong correlation between endothelial cell dysfunction and areas of low mean shear stress and oscillatory flow with flow recirculation. Conversely, steady shear stress stimulates cellular responses that are essential for endothelial cell function and are atheroprotective. The molecular basis of shear-induced mechanochemical signal transduction and the endothelium's ability to discriminate between flow profiles remains largely unclear. Given that fluid shear stress does not involve a traditional receptor/ligand interaction, identification of the molecule(s) responsible for sensing fluid flow and mechanical force discrimination has been difficult. This review will provide an overview of the haemodynamic forces experienced by the vascular endothelium and its role in localizing atherosclerotic lesions within specific regions of the vasculature. Also reviewed are several recent lines of evidence suggesting that both changes in membrane microviscosity linked to heterotrimeric G proteins, and the transmission of tension across the cell membrane to the cell-cell junction where known shear-sensitive proteins are localized, may serve as the primary force-sensing elements of the cell.
Collapse
|
13
|
Abstract
Atherosclerotic lesions form preferentially at distinct sites in the arterial tree, especially at or near branch points, bifurcations, and curvatures where there is disturbed or oscillatory blood flow. In contrast, straight regions of the vasculature exhibit uniform laminar shear stress, which is atheroprotective. The ability of laminar flow to exert an anti-inflammatory effect on the endothelial cell lining of the blood vessel is revealed by preventing monocyte adhesion, proliferation, and apoptosis. Changes in endothelial cell gene expression in response to laminar shear stress reflect these changes in cell physiology with the demonstration that physiologic flow inhibits the expression of inflammatory genes. Thus, shear stress is critically important in regulating vascular physiology and pathobiology of the vessel wall via the modulation of endothelial cell gene expression.
Collapse
Affiliation(s)
- Cameron J World
- Cardiovascular Research Institute, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | | | | |
Collapse
|
14
|
Pannier B, Guérin AP, Marchais SJ, Métivier F, London GM. Arterial structure and function in end-stage renal disease. Artery Res 2007. [DOI: 10.1016/j.artres.2007.06.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
|
15
|
Jo H, Song H, Mowbray A. Role of NADPH oxidases in disturbed flow- and BMP4- induced inflammation and atherosclerosis. Antioxid Redox Signal 2006; 8:1609-19. [PMID: 16987015 DOI: 10.1089/ars.2006.8.1609] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Atherosclerosis is an inflammatory disease, occurring preferentially in branched or curved arterial regions exposed to disturbed flow conditions including oscillatory shear stress (OS). In contrast, straight portions exposed to undisturbed laminar shear stress (LS) are relatively lesion free. The opposite effects of atheroprotective LS and proatherogenic OS are likely to be determined by differential expression of genes and proteins, including redox regulating factors. OS induces inflammation via mechanisms involving increased reactive oxygen species (ROS) production from the NADPH oxidases. Through a transcript profiling study and subsequent verification and functional studies, the authors discovered that OS induces inflammation by producing bone morphogenic protein 4 (BMP4) in endothelial cells. BMP4 stimulates expression and activity of NADPH oxidase requiring p47phox and Nox-1 in an autocrine-like manner. The NADPH oxidase activation by BMP4 then leads to ROS production, NF-kappaB activation, intercellular adhesion molecule 1 (ICAM-1) expression, and subsequent increased monocyte adhesivity of endothelial cells. It is proposed that endothelial NADPH oxidases play a critical role in disturbed flow- and BMP4-dependent inflammation, which is the critical early atherogenic response occurring in atheroprone areas. This emerging field of shear stress, BMP4, NADPH oxidases, inflammation, and atherosclerosis is reviewed.
Collapse
Affiliation(s)
- Hanjoong Jo
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, 30322, USA.
| | | | | |
Collapse
|
16
|
Subramanya S, Mensa-Wilmot K. Regulated cleavage of intracellular glycosylphosphatidylinositol in a trypanosome. Peroxisome-to-endoplasmic reticulum translocation of a phospholipase C. FEBS J 2006; 273:2110-26. [PMID: 16649989 DOI: 10.1111/j.1742-4658.2006.05225.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cell exposure to hypo-osmolarity and alkalinity triggers a spectrum of responses including activation of phospholipases. Glycosylphosphatidylinositol-specific phospholipase C (GPI-PLC) is expressed in Trypanosoma brucei, a protozoan parasite that causes human African trypanosomiasis. We examined possible contributions of GPI-PLC to the response of T. brucei to hypo-osmotic or mildly alkaline conditions. GPIs were detected at the endoplasmic reticulum (ER). They were cleaved after exposure of T. brucei to hypo-osmolarity or mild alkalinity, which also, strikingly, caused translocation of GPI-PLC from glycosomes (peroxisomes) to the ER. A catalytically inactive Gln81Leu mutant of GPI-PLC failed to cleave GPIs despite being transported from glycosomes to the ER after hypo-osmotic or mild alkaline treatment of the parasites. In contrast, a Cys347Ser mutant of the enzyme could not exit glycosomes after treatment of cells expressing the protein with mild base or hypo-osmotic buffer. We conclude that: (a) GPI-PLC contributes to loss of GPIs in T. brucei treated with hypo-osmotic or mildly alkaline buffer; (b) access of GPI-PLC to its substrate in vivo can be regulated post-translationally; (c) translocation of GPI-PLC from glycosomes to the ER is important for in vivo cleavage of GPIs; (d) Cys347 is part of a peptide motif required for post-translational targeting of GPI-PLC to the ER. Glycosome-to-ER movement of GPI-PLC reveals a novel pathway for intracellular protein traffic. The physiological significance of GPI digestion in cells exposed to mildly alkalinity or hypo-osmolarity is discussed.
Collapse
Affiliation(s)
- Sandesh Subramanya
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, USA
| | | |
Collapse
|
17
|
Li YSJ, Haga JH, Chien S. Molecular basis of the effects of shear stress on vascular endothelial cells. J Biomech 2005; 38:1949-71. [PMID: 16084198 DOI: 10.1016/j.jbiomech.2004.09.030] [Citation(s) in RCA: 593] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2004] [Accepted: 09/20/2004] [Indexed: 12/15/2022]
Abstract
Blood vessels are constantly exposed to hemodynamic forces in the form of cyclic stretch and shear stress due to the pulsatile nature of blood pressure and flow. Endothelial cells (ECs) are subjected to the shear stress resulting from blood flow and are able to convert mechanical stimuli into intracellular signals that affect cellular functions, e.g., proliferation, apoptosis, migration, permeability, and remodeling, as well as gene expression. The ECs use multiple sensing mechanisms to detect changes in mechanical forces, leading to the activation of signaling networks. The cytoskeleton provides a structural framework for the EC to transmit mechanical forces between its luminal, abluminal and junctional surfaces and its interior, including the cytoplasm, the nucleus, and focal adhesion sites. Endothelial cells also respond differently to different modes of shear forces, e.g., laminar, disturbed, or oscillatory flows. In vitro studies on cultured ECs in flow channels have been conducted to investigate the molecular mechanisms by which cells convert the mechanical input into biochemical events, which eventually lead to functional responses. The knowledge gained on mechano-transduction, with verifications under in vivo conditions, will advance our understanding of the physiological and pathological processes in vascular remodeling and adaptation in health and disease.
Collapse
Affiliation(s)
- Yi-Shuan J Li
- Department of Bioengineering, University of California, San Diego, La Jolla, 92093-0412, USA
| | | | | |
Collapse
|
18
|
Bilodeau K, Couet F, Boccafoschi F, Mantovani D. Design of a Perfusion Bioreactor Specific to the Regeneration of Vascular Tissues Under Mechanical Stresses. Artif Organs 2005; 29:906-12. [PMID: 16266305 DOI: 10.1111/j.1525-1594.2005.00154.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The objective of this work was to design a bioreactor to stimulate the three-dimensional regeneration of arterial tissue on a cylindrical scaffold with a methodological approach. Once seeded, the scaffold is perfused internally and the externally with culture medium with two independent perfusion systems at different flow rates. The horizontal position and the rotation of the construct ensure the uniformity of the arterial growth and of the endothelial cell spreading. During cell culture, the parameters, such as internal flow and stretching of the vessel, can evolve gradually from the fetal stage to the adult stage. The bioreactor will also be useful for investigating the influence of mechanical stresses and strains on the properties of mature arteries (rigidity, burst strength, adhesion of endothelial cells, etc.).
Collapse
Affiliation(s)
- Katia Bilodeau
- Laboratory for Biomaterials and Bioengineering, Department of Materials Engineering, Laval University, Quebec City, Canada
| | | | | | | |
Collapse
|
19
|
Liu Y, Zhu Y, Rannou F, Lee TS, Formentin K, Zeng L, Yuan X, Wang N, Chien S, Forman BM, Shyy JYJ. Laminar flow activates peroxisome proliferator-activated receptor-gamma in vascular endothelial cells. Circulation 2004; 110:1128-33. [PMID: 15313948 DOI: 10.1161/01.cir.0000139850.08365.ec] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Steady laminar flow is atheroprotective, in part because of its antiinflammatory effects on vascular endothelial cells (ECs). We studied the activation of peroxisome proliferator-activated receptor-gamma (PPARgamma) in ECs in response to laminar flow and the associated antiinflammatory effect. METHODS AND RESULTS Using flow channel with cultured ECs, we found that laminar flow activated the PPARgamma-mediated PPAR-responsive element (PPRE) activity and increased the mRNA encoding CD36, a PPARgamma-targeted gene. Analysis of the CD36 promoter revealed that PPRE was required for flow activation. Laminar flow induced the GAL-PPARgamma-LBD fusion protein, which suggests that flow activation of PPARgamma was ligand dependent. The pharmaceutical inhibitors of phospholipase A2 (PLA2) and cytochrome P450 epoxygenases (CYP450s) were able to block the laminar flow-activated PPARgamma. We also showed that lipid extracts from flow media contained ligands for the activation of PPARgamma in other cell types. This paracrine activation exerted antiinflammatory effects in ECs and THP-1 cells, including the suppression of cytokine-induced nuclear factor-kappaB activation and expression of intercellular adhesion molecule-1. CONCLUSIONS Laminar flow activates endogenous PPARgamma in ECs, which is ligand dependent. The flow production of PPARgamma ligands is through the PLA2-CYP450 pathway, and the induced PPARgamma ligands exert antiinflammatory effects in several types of cells.
Collapse
Affiliation(s)
- Yi Liu
- Division of Biomedical Sciences, University of California at Riverside, Riverside, CA 92521-0121, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Miyakawa AA, de Lourdes Junqueira M, Krieger JE. Identification of two novel shear stress responsive elements in rat angiotensin I converting enzyme promoter. Physiol Genomics 2004; 17:107-13. [PMID: 14872008 DOI: 10.1152/physiolgenomics.00169.2003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mechanical forces contribute to maintenance of cardiovascular homeostasis via the control of release and production of vasoactive substances. We demonstrated previously that shear stress decreases rat ACE activity and expression. Using a reporter gene approach and mutagenesis, we show now that the classic shear stress responsive element or SSRE (GAGACC) contained within 1,274 bp of this promoter is not functional in response to shear stress (15 dyn/cm2, 18 h) [for the wild-type ACE promoter (WLuc), static control (C) = 107 ± 6.5%, shear stress (SS) = 65.9 ± 9.4%, n = 8; for the promoter with the classic SSRE mutated (WSS-mut), C = 100 ± 8.2%, SS = 60.2 ± 5.2%, n = 10, respectively]. Analysis of progressive deletion mutants unraveled a 57-bp fragment, position −251 to −195, from the transcription start site, containing functional SSRE (for WLuc, C = 107 ± 6.5%, SS = 65.9 ± 9.4%, n = 8; for 378, C = 100 ± 6.4%, SS = 60.4 ± 4.3%, n = 11; for 251, C = 99.7 ± 2.6%, SS = 63.2 ± 5.5%, n = 7; for 194, C = 104.6 ± 8.1%, SS = 92.4 ± 6.9%, n = 9). This fragment responded to shear stress even in the context of a heterologous promoter. Finally, functional analysis of mutated candidate regulatory elements identified by gel shift, DNase I footprint, and conservation of aligned sequences revealed that only the double mutant (Barbie/GAGA-mut) but not isolated disruption of the Barbie (WBarbie-mut) or the GAGA (WGAGA-mut) prevented the shear-stress-induced response (for Barbie/GAGA-mut, C = 97.9 ± 5%, SS = 99.4 ± 7.2%, n = 6; for WBarbie-mut, C = 106.1 ± 8.6%, SS = 65.9 ± 9.4%, n = 6; for WGAGA-mut, C = 100.1 ± 2.9%, SS = 66.7 ± 1.6, n = 6;). Taken together, these data provide direct evidence for the new role of Barbie and GAGA boxes in mediating the shear-stress-induced downregulation of rat ACE expression and demonstrate that the classic SSRE (GAGACC) is not functional under the experimental conditions tested.
Collapse
Affiliation(s)
- Ayumi Aurea Miyakawa
- Laboratory of Genetic and Molecular Cardiology, Heart Institute (InCor) and Internal Medicine Department/LIM13, University of São Paulo Medical School, 05403-901 São Paulo SP, Brazil
| | | | | |
Collapse
|
21
|
Florian JA, Kosky JR, Ainslie K, Pang Z, Dull RO, Tarbell JM. Heparan Sulfate Proteoglycan Is a Mechanosensor on Endothelial Cells. Circ Res 2003; 93:e136-42. [PMID: 14563712 DOI: 10.1161/01.res.0000101744.47866.d5] [Citation(s) in RCA: 422] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The objective of this study was to test whether a glycosaminoglycan component of the surface glycocalyx layer is a fluid shear stress sensor on endothelial cells (ECs). Because enhanced nitric oxide (NO) production in response to fluid shear stress is a characteristic and physiologically important response of ECs, we evaluated NO
x
(NO
2
−
and NO
3
−
) production in response to fluid shear stress after enzymatic removal of heparan sulfate, the dominant glycosaminoglycan of the EC glycocalyx, from cultured ECs. The significant NO
x
production induced by steady shear stress (20 dyne/cm
2
) was inhibited completely by pretreatment with 15 mU/mL heparinase III (E.C.4.2.2.8) for 2 hours. Oscillatory shear stress (10±15 dyne/cm
2
) induced an even greater NO
x
production than steady shear stress that was completely inhibited by pretreatment with heparinase III. Addition of bradykinin (BK) induced significant NO
x
production that was not inhibited by heparinase pretreatment, demonstrating that the cells were still able to produce abundant NO after heparinase treatment. Fluorescent imaging with a heparan sulfate antibody revealed that heparinase III treatments removed a substantial fraction of the heparan sulfate bound to the surfaces of ECs. In summary, these experiments demonstrate that a heparan sulfate component of the EC glycocalyx participates in mechanosensing that mediates NO production in response to shear stress. The full text of this article is available online at http://www.circresaha.org.
Collapse
Affiliation(s)
- Jeffry A Florian
- Biomolecular Transport Dynamics Laboratory, Department of Chemical Engineering, The Pennsylvania State University, University Park, Pa, USA
| | | | | | | | | | | |
Collapse
|
22
|
Pertrini CM, Miyakawa AA, Laurindo FRM, Krieger JE. Nitric oxide regulates angiotensin-I converting enzyme under static conditions but not under shear stress. Braz J Med Biol Res 2003; 36:1175-8. [PMID: 12937782 DOI: 10.1590/s0100-879x2003000900005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mechanical forces including pressure and shear stress play an important role in vascular homeostasis via the control of the production and release of a variety of vasoactive factors. An increase in vascular shear stress is accompanied by nitric oxide (NO) release and NO synthase activation. Previously, we have demonstrated that shear stress induces angiotensin-I converting enzyme (ACE) down-regulation in vivo and in vitro. In the present study, we determined whether NO participates in the shear stress-induced ACE suppression response. Rabbit aortic endothelial cells were evaluated using the NO synthase inhibitor L-NAME, and two NO donors, diethylamine NONOate (DEA/NO) and sodium nitroprusside (SNP). Under static conditions, incubation of endothelial cells with 1 mM L-NAME for 18 h increased ACE activity by 27% (from 1.000 +/- 0.090 to 1.272 +/- 0.182) while DEA/NO and SNP (0.1, 0.5 and 1 mM) caused no change in ACE activity. Interestingly, ACE activity was down-regulated similarly in the presence or absence of L-NAME (delta(0 mM) = 0.26 0.055, delta(0.1 mM) = 0.21 +/- 0.22, delta(1 mM) = 0.36 +/- 0.13) upon 18 h shear stress activation (from static to 15 dyn/cm2 ). Taken together, these results indicate that NO can participate in the maintenance of basal ACE levels in the static condition but NO is not associated with the shear stress-induced inactivation of ACE.
Collapse
Affiliation(s)
- C M Pertrini
- Laboratório de Genética e Cardiologia Molecular, Instituto do Coração (InCor), Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil
| | | | | | | |
Collapse
|
23
|
Abstract
Blood vessels are permanently subjected to mechanical forces in the form of stretch, encompassing cyclic mechanical strain due to the pulsatile nature of blood flow, and shear stress. Alterations in stretch or shear stress invariably produce transformations in the vessel wall that will aim to accommodate the new conditions and to ultimately restore basal levels of tensile stress and shear stress. Vascular cells are equipped with numerous receptors that allow them to detect and respond to the mechanical forces generated by pressure and shear stress. The cytoskeleton and other structural components have an established role in mechanotransduction, being able to transmit and modulate tension within the cell via focal adhesion sites, integrins, cellular junctions and the extracellular matrix. Beyond the structural modifications incurred, mechanical forces can also initiate complex signal transduction cascades leading to functional changes within the cell. Many intracellular pathways, including the MAP kinase cascade, are activated by flow or stretch and initiate, via sequential phosphorylations, the activation of transcription factors and subsequent gene expression.
Collapse
|
24
|
Resnick N, Yahav H, Shay-Salit A, Shushy M, Schubert S, Zilberman LCM, Wofovitz E. Fluid shear stress and the vascular endothelium: for better and for worse. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2003; 81:177-99. [PMID: 12732261 DOI: 10.1016/s0079-6107(02)00052-4] [Citation(s) in RCA: 370] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
As blood flows, the vascular wall is constantly subjected to physical forces, which regulate important physiological blood vessel responses, as well as being implicated in the development of arterial wall pathologies. Changes in blood flow, thus generating altered hemodynamic forces are responsible for acute vessel tone regulation, the development of blood vessel structure during embryogenesis and early growth, as well as chronic remodeling and generation of adult blood vessels. The complex interaction of biomechanical forces, and more specifically shear stress, derived by the flow of blood and the vascular endothelium raise many yet to be answered questions:How are mechanical forces transduced by endothelial cells into a biological response, and is there a "shear stress receptor"?Are "mechanical receptors" and the final signaling pathways they evoke similar to other stimulus-response transduction systems?How do vascular endothelial cells differ in their response to physiological or pathological shear stresses?Can shear stress receptors or shear stress responsive genes serve as novel targets for the design of diagnostic and therapeutic modalities for cardiovascular pathologies?The current review attempts to bring together recent findings on the in vivo and in vitro responses of the vascular endothelium to shear stress and to address some of the questions raised above.
Collapse
Affiliation(s)
- Nitzan Resnick
- Department of Anatomy and Cell Biology, Bruce Rappaport Research Institute, Bruce Rappaport Faculty of Medicine, P.O. Box. 9697 Technion Bat-Galim, Haifa, 31096 Israel.
| | | | | | | | | | | | | |
Collapse
|
25
|
Zhao Y, Chen BPC, Miao H, Yuan S, Li YS, Hu Y, Rocke DM, Chien S. Improved significance test for DNA microarray data: temporal effects of shear stress on endothelial genes. Physiol Genomics 2002; 12:1-11. [PMID: 12399447 DOI: 10.1152/physiolgenomics.00024.2002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Statistical methods for identifying differentially expressed genes from microarray data are evolving. We developed a test for the statistical significance of differential expression as a function of time. When applied to microarray data obtained from endothelial cells exposed to shearing for different durations, the new multi-group test (G-test) identified three times as many genes as the one-way ANOVA at the same significance level. Using simulated data, we showed that this increase in sensitivity was achieved without sacrificing specificity. Several genes known to respond to shear stress by Northern blotting were identified by the G-test at P < or = 0.01 (but not by ANOVA), with similar temporal patterns. The validity and utility of the G-test were further supported by the examination of a few more example genes in relation to the present knowledge of their regulatory mechanisms. This new significance test may have broad application for the analysis of gene-expression studies and, in fact, to other biological studies in general.
Collapse
Affiliation(s)
- Yihua Zhao
- Department of Bioengineering and the Whitaker Institute of Biomedical Engineering, University of California, San Diego, La Jolla 92093-0427, USA
| | | | | | | | | | | | | | | |
Collapse
|
26
|
Clark CB, McKnight NL, Frangos JA. Strain and strain rate activation of G proteins in human endothelial cells. Biochem Biophys Res Commun 2002; 299:258-62. [PMID: 12437979 DOI: 10.1016/s0006-291x(02)02628-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The endothelium is known to sense and respond to its physical environment, but the underlying mechanisms and early events of endothelial cell mechanotransduction are not well understood. The present study measured G protein activation by mechanical strain in human umbilical vein endothelial cells (HUVEC) directly by photoincorporation of a hydrolysis resistant, radiolabeled GTP analog. Ten percent uniaxial strain at a strain rate of 20% s(-1) over 1min activated a 38kDa Galpha subunit 167+/-17% relative to controls, while 2% cyclic strain failed to significantly activate the protein (117+/-19%). A single cycle of 10% strain at 20% s(-1) strain rate activated the Galpha subunit 152+/-25%, while activation at the same strain but lower strain rate (0.3% s(-1)) was not significantly different from controls (116+/-12%). Western blot analysis identified the 38kDa protein as Galpha(q/11). These results demonstrate the rapid activation of G proteins in HUVEC by cyclic uniaxial strain in a strain- and strain rate-dependent manner.
Collapse
Affiliation(s)
- Craig B Clark
- Department of Bioengineering, University of California San Diego, 92093-0142, La Jolla, CA, USA
| | | | | |
Collapse
|
27
|
Tai LK, Okuda M, Abe JI, Yan C, Berk BC. Fluid shear stress activates proline-rich tyrosine kinase via reactive oxygen species-dependent pathway. Arterioscler Thromb Vasc Biol 2002; 22:1790-6. [PMID: 12426206 DOI: 10.1161/01.atv.0000034475.40227.40] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Fluid shear stress (flow) modulates endothelial cell (EC) function via specific signal transduction events. Previously, we showed that flow-mediated tyrosine phosphorylation of p130 Crk-associated substrate (Cas) required calcium-dependent c-Src activation. Because flow increases reactive oxygen species (ROS) production in ECs and because H(2)O(2) increases tyrosine phosphorylation of proline-rich tyrosine kinase (PYK2), we hypothesized that flow may activate PYK2 via ROS. METHODS AND RESULTS Exposure of bovine aortic ECs to flow stimulated PYK2 phosphorylation rapidly, with a peak at 2 minutes. The activation of PYK2 and phosphorylation of Cas induced by flow were inhibited by pretreatment with the antioxidant N-acetylcysteine. Flow-induced PYK2 phosphorylation was inhibited by BAPTA-AM, an intracellular calcium chelator. Bovine aortic ECs transfected with kinase-inactive PYK2 showed attenuated flow-stimulated Cas tyrosine phosphorylation. Although flow-induced Cas phosphorylation was inhibited by kinase-inactive Src, PYK2 activation induced by flow was not inhibited by overexpression of kinase-inactive Src. CONCLUSIONS These results show a redox-sensitive pathway for flow-mediated activation of nonreceptor tyrosine kinase activity that requires ROS and intracellular calcium, but not Src kinase.
Collapse
Affiliation(s)
- Lung-Kuo Tai
- Center for Cardiovascular Research, University of Rochester, Rochester, NY 14642, USA
| | | | | | | | | |
Collapse
|
28
|
Palestini P, Calvi C, Conforti E, Botto L, Fenoglio C, Miserocchi G. Composition, biophysical properties, and morphometry of plasma membranes in pulmonary interstitial edema. Am J Physiol Lung Cell Mol Physiol 2002; 282:L1382-90. [PMID: 12003796 DOI: 10.1152/ajplung.00447.2001] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We evaluated the changes in plasma membrane composition, biophysical properties, and morphology of pulmonary endothelial cells in anesthetized rabbits receiving 0.5 ml. kg(-1). min(-1) saline infusion for 180 min, causing mild interstitial edema. Plasma membrane fractions were obtained from lung homogenates with gradient centrifugation, allowing a sixfold enrichment in caveolin-1. In edematous lungs, cholesterol content and phospholipidic phosphorus increased by 15 and 40%, respectively. These data correlated with morphometric analysis of lungs fixed in situ by vascular perfusion with 2.5% glutaraldehyde, suggesting a relative increase in surface of luminal to interstitial front of the capillary endothelial cells, due to a convoluted luminal profile. In edematous lungs, the fraction of double-bound fatty acids increased in membrane lipids; moreover, the phosphatidylcholine/phosphatidylethanolamine and the cholesterol/phospholipid ratios decreased. These changes were consistent with the increase in fluorescence anisotropy of plasma membrane, indicating an increase in its fluidity. Data suggest that mechanical stimuli elicited by a modest (approximately 4%) increase in extravascular water cause marked changes in plasma membranes that may be of relevance in signal transduction and endothelial cell activation.
Collapse
Affiliation(s)
- Paola Palestini
- Department of Experimental, Environmental Medicine and Biotechnology, University of Milano-Bicocca, Monza 20052, Italy
| | | | | | | | | | | |
Collapse
|
29
|
Nichols TC, Fischer TH, Deliargyris EN, Baldwin AS. Role of nuclear factor-kappa B (NF-kappa B) in inflammation, periodontitis, and atherogenesis. ANNALS OF PERIODONTOLOGY 2001; 6:20-9. [PMID: 11887466 DOI: 10.1902/annals.2001.6.1.20] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Atherosclerosis, the major cause of death and disability in the United States, is a chronic disease with inflammatory components. The first objective of this review is to explain how activation of NF-kappa B contributes to atherosclerosis. The second objective is to describe a potential link between inflammation, activation of NF-kappa B, and periodontitis. The nuclear transcription factor NF-kappa B controls the expression of many genes linked to atherogenesis including those involved with inflammation. We hypothesize that one unifying mechanism in this complex disease is the activation of NF-kappa B. The mechanism(s) that activates NF-kappa B in atherogenesis is unknown and the effect of inhibiting NF-kappa B activation on atherogenesis is untested. Periodontal disease has now been established as a risk factor for atherosclerosis and its thrombotic complications. It is unknown if periodontal disease contributes to the initiation or progression of atherosclerosis. We hypothesize that the chronic and intense inflammatory response accompanying periodontal disease produces an excess burden of circulating mediators of inflammation that initiate or exacerbate the inflammatory components of atherogenesis. Further understanding of the mechanisms involved in the activation of NF-kappa B in atherosclerosis could lead to important therapeutic applications especially as it relates to the impact of periodontitis.
Collapse
Affiliation(s)
- T C Nichols
- Department of Pathology and Laboratory Medicine, Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA.
| | | | | | | |
Collapse
|
30
|
Edwards YS. Stretch stimulation: its effects on alveolar type II cell function in the lung. Comp Biochem Physiol A Mol Integr Physiol 2001; 129:245-60. [PMID: 11369549 DOI: 10.1016/s1095-6433(01)00321-x] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mechanical stimuli regulate cell function in much the same way as chemical signals do. This has been studied in various cell types, particularly those with defined mechanical roles. The alveolar type II cell (ATII) cell, which is part of the alveolar epithelium of the lung, is responsible for the synthesis and secretion of pulmonary surfactant. It is now widely believed that stretch of ATII cells, which occurs during breathing, is the predominant physiological trigger for surfactant release. To study this, investigators have used an increasingly sophisticated array of in vitro and in vivo models. Using various stretch devices and models of lung ventilation and expansion, it has been shown that stretch regulates multiple activities in ATII cells. In addition to surfactant secretion, stretch triggers the differentiation of ATII to alveolar type I cells, as well as ATII cell apoptosis. In doing so, stretch modulates the proportion of these cells in the lung epithelium during both development and maturation of the lung and following lung injury. From such studies, it appears that mechanical distortion plays an integral part in maintaining the overall structure and function of the lung.
Collapse
Affiliation(s)
- Y S Edwards
- Department of Environmental Biology, University of Adelaide, South Australia, 5005, Adelaide, Australia.
| |
Collapse
|
31
|
Abstract
Endothelial injury, obliterative microvascular lesions, and increased vascular wall thickness are present in all involved organs in scleroderma. The vascular pathology is associated with altered vascular function with increased vasospasm, reduced vasodilatory capacity and increased adhesiveness of the blood vessels to platelets and lymphocytes. The extent of injury and dysfunction is reflected by changes in the circulating levels of vascular markers. The initial triggers for the vascular pathology are not known. Possible viral triggers are visited here, including cytomegalovirus in view of increased levels of anti-CMV antibodies in scleroderma, and the remarkable similarities between CMV vasculopathies and scleroderma vascular disease. Endothelial apoptosis in scleroderma may be related to viral infection, immune reactions to viral or environmental factors, reperfusion injury or to anti-endothelial antibodies. The impact of the vascular pathology on the evolution of tissue fibrosis is not known; still, cytokines (TGFbeta, IL4), vascular factors (endothelin), and growth factors (PDGF) are possibly crucial signals that link the vascular disease to tissue fibrosis. Knowledge of the regulation of these and other factors will provide the opportunity to develop more rational therapeutic approaches to the disease.
Collapse
Affiliation(s)
- M B Kahaleh
- Department of Medicine, Richard Ruppert Health Center, Medical College of Ohio, Toledo 43614-5809, USA
| | | |
Collapse
|
32
|
Haidekker MA, L'Heureux N, Frangos JA. Fluid shear stress increases membrane fluidity in endothelial cells: a study with DCVJ fluorescence. Am J Physiol Heart Circ Physiol 2000; 278:H1401-6. [PMID: 10749738 DOI: 10.1152/ajpheart.2000.278.4.h1401] [Citation(s) in RCA: 134] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Fluid shear stress (FSS) has been shown to be an ubiquitous stimulator of mammalian cell metabolism. Although many of the intracellular signal transduction pathways have been characterized, the primary mechanoreceptor for FSS remains unknown. One hypothesis is that the cytoplasmic membrane acts as the receptor for FSS, leading to increased membrane fluidity, which in turn leads to the activation of heterotrimetric G proteins (13). 9-(Dicyanovinyl)-julolidine (DCVJ) is a fluorescent probe that integrates into the cell membrane and changes its quantum yield with the viscosity of the environment. In a parallel-plate flow chamber, confluent layers of DCVJ-labeled human endothelial cells were exposed to different levels of FSS. With increased FSS, a reduced fluorescence intensity was observed, indicating an increase of membrane fluidity. Step changes of FSS caused an approximately linear drop of fluorescence within 5 s, showing fast and almost full recovery after shear cessation. A linear dose-response relationship between shear stress and membrane fluidity changes was observed. The average fluidity increase over the entire cell monolayer was 22% at 26 dyn/cm(2). This study provides evidence for a link between FSS and membrane fluidity, and suggests that the membrane is an important flow mechanosensor of the cell.
Collapse
Affiliation(s)
- M A Haidekker
- Department of Bioengineering, University of California, San Diego, La Jolla, California 92093-0412, USA
| | | | | |
Collapse
|
33
|
Jiang MJ, Yu YJ, Chen YL, Lee YM, Hung LS. Cyclic strain stimulates monocyte chemotactic protein-1 mRNA expression in smooth muscle cells. J Cell Biochem 2000. [DOI: 10.1002/(sici)1097-4644(20000201)76:2<303::aid-jcb13>3.0.co;2-e] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
|
34
|
Abstract
The lung is a dynamic organ that is subjected to mechanical forces throughout development and adult life. This review article addresses the types of mechanical forces in the lung and their effects on development and normal lung functions. The effects of mechanical forces on the various different cell types of the lung are discussed, as are the mechanisms underlying mechanotransduction.
Collapse
Affiliation(s)
- H R Wirtz
- Department of Medicine (I), University of Leipzig, Germany
| | | |
Collapse
|
35
|
McCarty MF. Endothelial membrane potential regulates production of both nitric oxide and superoxide--a fundamental determinant of vascular health. Med Hypotheses 1999; 53:277-89. [PMID: 10608262 DOI: 10.1054/mehy.1998.0758] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
There is recent evidence that the membrane potential of vascular endothelium regulates not only nitric oxide (NO) synthesis, but also superoxide generation, such that hyperpolarization stimulates NO production while suppressing that of superoxide. Given that NO works in a variety of ways to inhibit atherothrombotic disease and hypertension, whereas superoxide not only vetoes the benefits of NO but also disrupts endothelial metabolism and promotes LDL oxidation through its oxidant activity, it is thus evident that endothelium membrane potential is a crucial determinant of cardiovascular risk. Membrane polarization can be enhanced by measures which increase the synthesis or availability of the Na+-K+-ATPase, moderately enhance serum K+ and increase the conductance of membrane K+ channels. Such measures may include high-K+/low-Na+ natural diets, insulin sensitizing modalities, 'euthyroid replacement therapy' and ACE inhibitors. Epidemiological correlations of insulin resistance with hypertension and cardiovascular risk may reflect the low membrane potential of insulin-resistant vascular endothelium. Adjunctive measures for suppressing the generation or half-life of endothelial superoxide are suggested.
Collapse
|
36
|
Liu M, Tanswell AK, Post M. Mechanical force-induced signal transduction in lung cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:L667-83. [PMID: 10516207 DOI: 10.1152/ajplung.1999.277.4.l667] [Citation(s) in RCA: 147] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The lung is a unique organ in that it is exposed to physical forces derived from breathing, blood flow, and surface tension throughout life. Over the past decade, significant progress has been made at the cellular and molecular levels regarding the mechanisms by which physical forces affect lung morphogenesis, function, and metabolism. With the use of newly developed devices, mechanical forces have been applied to a variety of lung cells including fetal lung cells, adult alveolar epithelial cells, fibroblasts, airway epithelial and smooth muscle cells, pulmonary endothelial and smooth muscle cells, and mesothelial cells. These studies have led to new insights into how cells sense mechanical stimulation, transmit signals intra- and intercellularly, and regulate gene expression at the transcriptional and posttranscriptional levels. These advances have significantly increased our understanding of the process of mechanotransduction in lung cells. Further investigation in this exciting research field will facilitate our understanding of pulmonary physiology and pathophysiology at the cellular and molecular levels.
Collapse
Affiliation(s)
- M Liu
- Thoracic Surgery Research Laboratory, Toronto General Hospital, University Health Network, Toronto M5G 2C4, Ontario, Canada M5G 1X8.
| | | | | |
Collapse
|
37
|
Okuda M, Takahashi M, Suero J, Murry CE, Traub O, Kawakatsu H, Berk BC. Shear stress stimulation of p130(cas) tyrosine phosphorylation requires calcium-dependent c-Src activation. J Biol Chem 1999; 274:26803-9. [PMID: 10480886 DOI: 10.1074/jbc.274.38.26803] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Fluid shear stress (flow) modulates endothelial cell function via specific intracellular signaling events. Previously we showed that flow activated ERK1/2 in an integrin-dependent manner (Takahashi, M., and Berk, B. C. (1996) J. Clin. Invest. 98, 2623-2631). p130 Crk-associated substrate (Cas), a putative c-Src substrate, was originally identified as a highly phosphorylated protein that is localized to focal adhesions and acts as an adapter protein. Recent reports have shown that Cas is important in cardiovascular development and actin filament assembly. Flow (shear stress = 12 dynes/cm(2)) stimulated Cas tyrosine phosphorylation within 1 min in human umbilical vein endothelial cells. Phosphorylation peaked at 5 min (3.5 +/- 0.7-fold) and was sustained to 20 min. Tyrosine phosphorylation of Cas was functionally important because flow stimulated association of Cas with Crk in a time- and force-dependent manner. Flow-mediated activation of c-Src, phosphorylation of Cas, and association of Cas with Crk were all inhibited by calcium chelation and pretreatment with the Src family-specific tyrosine kinase inhibitor PP1. To determine the role of c-Src in flow-stimulated phosphorylation of Cas, we transduced cells with adenovirus encoding kinase-inactive Src. Expression of kinase-inactive Src prevented flow-induced Cas tyrosine phosphorylation but not ERK1/2 activation. Calcium-dependent activation of c-Src and tyrosine phosphorylation of Cas defines a new flow-stimulated signal pathway, different from ERK1/2 activation. This pathway may be involved in focal adhesion remodeling and actin filament assembly.
Collapse
Affiliation(s)
- M Okuda
- Department of Medicine, Cardiology Division, University of Washington, Seattle, Washington 98195, USA
| | | | | | | | | | | | | |
Collapse
|
38
|
Nakazawa T, Yasuhara H, Shigematsu K, Shigematsu H. Platelet-induced migration of smooth muscle cells under shear stress. Microvasc Res 1999; 58:177-82. [PMID: 10458933 DOI: 10.1006/mvre.1999.2172] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- T Nakazawa
- Department of Surgery, The University of Tokyo, Tokyo, Japan
| | | | | | | |
Collapse
|
39
|
Papadaki M, Eskin SG, Ruef J, Runge MS, McIntire LV. Fluid shear stress as a regulator of gene expression in vascular cells: possible correlations with diabetic abnormalities. Diabetes Res Clin Pract 1999; 45:89-99. [PMID: 10588360 DOI: 10.1016/s0168-8227(99)00036-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Diabetes mellitus is associated with increased frequency, severity and more rapid progression of cardiovascular diseases. Metabolic perturbations from hyperglycemia result in disturbed endothelium-dependent relaxation, activation of coagulation pathways, depressed fibrinolysis, and other abnormalities in vascular homeostasis. Atherosclerosis is localized mainly at areas of geometric irregularity at which blood vessels branch, curve and change diameter, and where blood is subjected to sudden changes in velocity and/or direction of flow. Shear stress resulting from blood flow is a well known modulator of vascular cell function. This paper presents what is currently known regarding the molecular mechanisms responsible for signal transduction and gene regulation in vascular cells exposed to shear stress. Considering the importance of the hemodynamic environment of vascular cells might be vital to increasing our understanding of diabetes.
Collapse
Affiliation(s)
- M Papadaki
- Department of Chemical Engineering and Harvard-MIT Health Science and Technology, Massachusetts Institute of Technology, Cambridge 02139, USA
| | | | | | | | | |
Collapse
|
40
|
Kato H, Osajima A, Uezono Y, Okazaki M, Tsuda Y, Tanaka H, Oishi Y, Izumi F, Nakashima Y. Involvement of PDGF in pressure-induced mesangial cell proliferation through PKC and tyrosine kinase pathways. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:F105-12. [PMID: 10409303 DOI: 10.1152/ajprenal.1999.277.1.f105] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In glomerular hypertension, mesangial cells (MC) are subjected to at least two physical forces: mechanical stretch and high transmural pressure. Increased transmural pressure, as well as mechanical stretch, promotes MC proliferation, which may enhance glomerulosclerosis. The exact mechanism of this effect is not fully understood. We examined the effects of transmural pressure alone on cell proliferation and DNA synthesis and investigated the role of platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF), candidates for mediation of glomerular diseases, in the pressure-induced events. Pressure was applied to cultured MC placed in a sealed chamber using compressed helium gas. Application of pressure resulted in a time-dependent ( approximately 2 h) and pressure level-dependent (approximately 80 mmHg) increase in cell number (1.4-fold) and [(3)H]thymidine incorporation (2.7-fold). Pressure-induced DNA synthesis was significantly suppressed by inhibitors of phospholipase C (2-nitro-4-carboxyphenyl-N, N-diphenylcarbamate), protein kinase C [1-(5-isoquinolinylsulfonyl)-2-methylpiperazine and chelerythrine], or tyrosine kinases (genistein). Pressure caused a rapid but transient formation of inositol 1,4,5-trisphosphate, which was blocked by the phospholipase C inhibitor. Pressure also promoted a rapid increase in tyrosine kinase activity. Pressure increased mRNA levels of PDGF-B, with a peak at 6 h, but not those of PDGF-A or bFGF. Pressure-induced DNA synthesis was partially inhibited by a neutralizing anti-PDGF antibody but not by an antibody against bFGF or nonimmune IgG. Our results indicated that pressure by itself increases DNA synthesis and proliferation of cultured rat MC possibly through activation of protein kinase C and tyrosine kinases, and PDGF-B could be partially involved in these pathways.
Collapse
Affiliation(s)
- H Kato
- Second Department of Internal Medicine, University of Occupational and Environmental Health, School of Medicine, Kitakyushu 807-8555, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Stamatas GN, McIntire LV. Novel optical methodologies in studying mechanical signal transduction in mammalian cells. Ind Eng Chem Res 1999; 38:601-9. [PMID: 11757568 DOI: 10.1021/ie980426a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
For the last 3 decades evidence has been accumulating that some types of mammalian cells respond to their mechanically active environment by altering their morphology, growth rate, and metabolism. The study of such responses is very important in understanding, physiological and pathological conditions ranging from bone formation to atherosclerosis. Obtaining this knowledge has been the goal for an active research area in bioengineering termed cell mechanotransduction. The advancement of optical methodologies used in cell biology research has given the tools to elucidate cellular mechanisms that would otherwise be impossible to visualize. Combined with molecular biology techniques, they give engineers invaluable tools in understanding the chemical pathways involved in mechanotransduction. Herein we briefly review the current knowledge on mechanical signal transduction in mammalian cells, focusing on the application of novel optical techniques in the ongoing research.
Collapse
MESH Headings
- Animals
- Cell Physiological Phenomena
- Endothelium, Vascular/cytology
- Endothelium, Vascular/physiology
- Fluorescent Antibody Technique
- Hemorheology
- Microscopy, Atomic Force
- Microscopy, Confocal
- Microscopy, Fluorescence
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/physiology
- Signal Transduction/physiology
- Stress, Mechanical
Collapse
Affiliation(s)
- G N Stamatas
- Cox Laboratory for Biomedical Engineering, Institute of Biosciences and Bioengineering, Rice University, Houston, Texas 77251-1892, USA
| | | |
Collapse
|
42
|
Bryant SR, Bjercke RJ, Erichsen DA, Rege A, Lindner V. Vascular remodeling in response to altered blood flow is mediated by fibroblast growth factor-2. Circ Res 1999; 84:323-8. [PMID: 10024306 DOI: 10.1161/01.res.84.3.323] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Vascular structures adapt to changes in blood flow by adjusting their diameter accordingly. The factors mediating this process are only beginning to be identified. We have recently established a mouse model of arterial remodeling in which flow in the common carotid artery is interrupted by ligation of the vessel near the carotid bifurcation, resulting in a dramatic reduction in vessel diameter as a consequence of inward remodeling and intimal lesion formation. In the present study, we used this model to determine the role of fibroblast growth factor-2 (FGF-2) in the remodeling response by maintaining neutralizing serum levels of a mouse monoclonal antibody against FGF-2 for 4 weeks. Morphometric analysis revealed that intimal lesion formation was not affected by the antibody. However, lumen narrowing was significantly inhibited, resulting in a greater than 3-fold increase in lumen area in anti-FGF-2-treated animals compared with controls. Treatment with anti-FGF-2 antibody significantly inhibited the reduction in vessel diameter (inward remodeling) and shortening of the internal elastic lamina in the ligated vessel. In addition, anti-FGF-2 treatment also caused outward remodeling of the contralateral carotid artery. These findings identify FGF-2 as an important factor in vascular remodeling, and its effects are likely to be mediated by increasing vascular tone. The results are consistent with the recent observation of reduced vascular tone in the FGF-2-deficient mouse.
Collapse
Affiliation(s)
- S R Bryant
- Center for Molecular Medicine, Maine Medical Center Research Institute, South Portland, Maine, USA
| | | | | | | | | |
Collapse
|
43
|
London GM, Guerin AP, Pannier B, Marchais SJ, Safar ME. Large artery structure and function in hypertension and end-stage renal disease. J Hypertens 1998; 16:1931-8. [PMID: 9886879 DOI: 10.1097/00004872-199816121-00012] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The cardiovascular complications in hypertension are ascribed to two different but associated alterations, namely atherosclerosis and arteriosclerosis. Whereas the former disturbs principally the conduit function and the delivery of an adequate blood flow to peripheral organs and tissues, the latter disturbs the cushioning function of large arteries, inducing an inadequate increase in systolic and pulse pressure. Arteriosclerosis represents a clinical form of accelerated ageing process and is characterized by a diffuse dilation and hypertrophy of large conduit arteries and stiffening of arterial walls. Independently from the ageing, structural changes are associated with several haemodynamic alterations such as increased in blood flow and flow velocity, and increased parietal stress due to increased arterial diameters and/or intraarterial pressure. The principal consequences of arterial stiffening are: (1) an increased left ventricular afterload with development of left ventricular hypertrophy and increased myocardial oxygen demand; (2) altered coronary perfusion and blood flow distribution; and (3) decreased perfusion reserve during haemodynamic stress. In the absence of controlled studies, it is difficult to propose therapeutic interventions aimed to prevent or treat arterial abnormalities in hypertensive patients. It has been shown that long-term administration of either calcium channel blockers and angiotensin converting enzyme inhibitors led to an improvement of vessel wall elasticity. Nevertheless, these studies did not conclude whether the improvement of elastic properties were due only to decrease in blood pressure or to alterations in intrinsic properties of arterial walls. More investigations should be necessary to investigate this important problem.
Collapse
|
44
|
Murase T, Kume N, Korenaga R, Ando J, Sawamura T, Masaki T, Kita T. Fluid shear stress transcriptionally induces lectin-like oxidized LDL receptor-1 in vascular endothelial cells. Circ Res 1998; 83:328-33. [PMID: 9710126 DOI: 10.1161/01.res.83.3.328] [Citation(s) in RCA: 154] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Fluid shear stress has been shown to modulate various endothelial functions, including gene expression. In this study, we examined the effect of fluid shear stress on the expression of lectin-like oxidized LDL receptor-1 (LOX-1), a novel receptor for atherogenic oxidized LDL in cultured bovine aortic endothelial cells (BAECs). Exposure of BAECs to the physiological range of shear stress (1 to 15 dyne/cm2) upregulated LOX-1 protein and mRNA in a time-dependent fashion. LOX-1 mRNA levels peaked at 4 hours, and LOX-1 protein levels peaked at 8 hours. Inhibition of de novo RNA synthesis by actinomycin D totally abolished shear stress-induced LOX-1 mRNA expression. Furthermore, nuclear runoff assay showed that shear stress directly stimulates transcription of the LOX-1 gene. Chelation of intracellular Ca2+ with quin 2-AM completely reduced shear stress-induced LOX-1 mRNA expression; furthermore, the treatment of BAECs with ionomycin upregulated LOX-1 mRNA levels in a dose-dependent manner. Taken together, physiological levels of fluid shear stress can regulate LOX-1 expression by a mechanism dependent on intracellular Ca2+ mobilization. Inducible expression of LOX-1 by fluid mechanics may play a role in localized expression of LOX-1 and atherosclerotic lesion formation in vivo.
Collapse
MESH Headings
- Animals
- Calcium/metabolism
- Cattle
- Cells, Cultured
- Cycloheximide/pharmacology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Hemorheology
- Ionomycin/pharmacology
- Ionophores/pharmacology
- Protein Synthesis Inhibitors/pharmacology
- RNA, Messenger/metabolism
- Receptors, LDL/biosynthesis
- Receptors, LDL/genetics
- Receptors, Oxidized LDL
- Stress, Mechanical
- Transcription, Genetic/drug effects
- Transcription, Genetic/physiology
Collapse
Affiliation(s)
- T Murase
- Department of Geriatric Medicine, Graduate School of Medicine, Kyoto University, Japan
| | | | | | | | | | | | | |
Collapse
|
45
|
Motomura N, Lou H, Orskov H, Ramwell PW, Foegh ML. Exposure of vascular allografts to insulin-like growth factor-I (IGF-I) increases vascular expression of IGF-I ligand and receptor protein and accelerates arteriosclerosis in rats. Transplantation 1998; 65:1024-30. [PMID: 9583860 DOI: 10.1097/00007890-199804270-00003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Accelerated arteriosclerosis limits the survival of transplanted hearts. We hypothesized that insulin-like growth factor-I (IGF-I) is crucial in accelerating transplant arteriosclerosis. Recently, we reported that exposure to IGF-I prior to transplantation accelerates transplant arteriosclerosis in the rat aorta allograft model. Here, we studied the mechanism whereby IGF-I exposure accelerates transplant arteriosclerosis. METHODS The abdominal aorta was harvested from male Brown Norway rats and exposed to 0, 200, or 500 ng/ml of IGF-I at 37 degrees C for 30 min prior to transplantation to the abdominal position of male Lewis rats. The allografts were harvested 14 days later and processed for immunohistochemical staining for alpha-actin, growth factors (IGF-I, IGF-I receptor, platelet-derived growth factor-BB, and basic fibroblast growth factor), and immunological markers (major histocompatibility complex class II antigen, macrophage, and CD4- and CD8-positive T cells). RESULTS By 14 days, the ex vivo IGF-I donor aorta treatment with IGF-I increased in a concentration-dependent manner the expression of IGF-I and IGF-I receptor in both the intima and the adventitia. In contrast, the expression of platelet-derived growth factor-BB was decreased in a concentration-dependent manner in the intima while basic fibroblast growth factor remained unchanged. The cell-mediated immune response was not affected by IGF-I at 14 days after transplantation, which suggests that the immune events associated with acceleration of transplant arteriosclerosis may occur at an earlier time. CONCLUSION Acceleration of transplant arteriosclerosis by exposure to IGF-I is associated with increased IGF-I ligand and receptor expression in the allograft vascular wall. These data further suggest that IGF-I may be a major factor in mediating graft arteriosclerosis.
Collapse
Affiliation(s)
- N Motomura
- Department of Surgery, Georgetown University Medical Center, Washington, DC 20007, USA
| | | | | | | | | |
Collapse
|
46
|
Price RJ, Skalak TC. Prazosin administration enhances proliferation of arteriolar adventitial fibroblasts. Microvasc Res 1998; 55:138-45. [PMID: 9521888 DOI: 10.1006/mvre.1997.2062] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chronic vasodilation stimulates the formation of new arterioles in skeletal muscle, a process that requires the differentiation of mesenchymally derived precursor cells on the abluminal surface of capillaries. Fibroblast proliferation and migration to the arterializing capillary likely precede this differentiation process. In the current study, we investigated the effects of chronic vasodilation with the alpha1 adrenergic blocker prazosin, a treatment that produces enhanced terminal arteriolar development, on the proliferation of fibroblasts present in the adventitia of transverse arterioles. Dual-immunofluorescence labeling for the smooth muscle contractile protein SM-myosin heavy chain (MHC) and for bromodeoxyuridine (BRDU) uptake revealed that prazosin treatment for 4 days stimulated a threefold increase in the density of proliferating fibroblasts surrounding transverse arteriolar trees. This increase was primarily due to an eightfold increase in the density of S-phase fibroblasts surrounding <8 micron m diameter terminal arterioles and a 280% increase in the density of S-phase fibroblasts surrounding 8- to 12-micron m terminal arterioles. Alcian blue counterstaining indicated that no proliferating cells were mast cells. An in vitro study demonstrated that prazosin, at concentrations of 0.5 and 0.05 mg/liter, has no direct effect on fibroblast proliferation. It is concluded that chronic vasodilation with prazosin, a treatment that elicits elevated levels of hemodynamic stress, stimulates the proliferation of adventitial fibroblasts, particularly at the terminal endings of transverse arteriolar trees.
Collapse
Affiliation(s)
- R J Price
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia
| | | |
Collapse
|
47
|
Jalali S, Li YS, Sotoudeh M, Yuan S, Li S, Chien S, Shyy JY. Shear stress activates p60src-Ras-MAPK signaling pathways in vascular endothelial cells. Arterioscler Thromb Vasc Biol 1998; 18:227-34. [PMID: 9484987 DOI: 10.1161/01.atv.18.2.227] [Citation(s) in RCA: 167] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The aim of this study was to elucidate the upstream signaling mechanism that mediates the fluid shear stress activation of mitogen-activated protein kinases (MAPKs), including c-Jun NH2-terminal kinase (JNK) and extracellular signal-regulated kinases (ERKs), in vascular endothelial cells (ECs). Our results indicate that p60src is rapidly activated by fluid shear stress in bovine aortic endothelial cells (BAECs). Shear stress induction of the hemagglutinin (HA) epitope-tagged HA-JNK1 and the Myc epitope-tagged Myc-ERK2 was significantly attenuated by v-src(K295R) and c-src(K295R), the kinase-defective mutants ofv-src and c-src, respectively. HA-JNK1 and Myc-ERK2 were activated by c-src(F527), a constitutively activated form of p60src, and the activation was abolished by RasN17, a dominant-negative mutant of p2lras. In contrast, although HA-JNK1 and Myc-ERK2 were also activated by RasL61, an activated form of p21ras, the activation was not affected by v-src(K295R). These results indicate that p60src is upstream to the Ras-JNK and Ras-ERK pathways in response to shear stress. The shear stress inductions of the promoters of monocyte chemotactic protein-1 (MCP-1) and c-fos, driven by TPA-responsive element (TRE) and serum-responsive element (SRE), respectively, were attenuated by v-src(K295R). This attenuation is associated with decreased transcriptional activities of c-Jun and Elk-1, the transcription factors targeting TRE and SRE, respectively. Thus, p60src plays a critical role in the shear stress activation of MAPK pathways and induction of Activating Protein-1 (AP- 1)/TRE and Elk-1/SRE-mediated transcription in ECs.
Collapse
Affiliation(s)
- S Jalali
- Department of Bioengineering and Institute for Biomedical Engineering, University of California, San Diego, La Jolla 92093-0412, USA
| | | | | | | | | | | | | |
Collapse
|
48
|
Motobu M, Wang PC, Matsumura M. Effect of shear stress on recombinant Chinese hamster ovary cells. ACTA ACUST UNITED AC 1998. [DOI: 10.1016/s0922-338x(97)86766-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
49
|
Chien S, Li S, Shyy YJ. Effects of mechanical forces on signal transduction and gene expression in endothelial cells. Hypertension 1998; 31:162-9. [PMID: 9453297 DOI: 10.1161/01.hyp.31.1.162] [Citation(s) in RCA: 373] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Fluid shear stress and circumferential stretch play important roles in maintaining the homeostasis of the blood vessel, and they can also be pathophysiological factors in cardiovascular diseases such as atherosclerosis and hypertension. The uses of flow channels and stretch devices as in vitro models have helped to elucidate the mechanisms of signal transduction and gene expression in cultured endothelial cells in response to shear stress, which is a function of blood flow and vascular geometry, or mechanical strain, which is a function of transmural pressure and the mechanical properties and geometry of the vessel. Shear stress has been found to increase the activities of a number of kinases to modulate the phosphorylation of many signaling proteins in endothelial cells, eg, the proteins in focal adhesion sites and the proteins in the mitogen-activated protein kinase pathways. Downstream to such signaling cascades, multiple transcription factors such as AP-1, NF-kappaB, Sp-1, and Egr-1 are activated. The actions of these transcription factors on the corresponding cis-elements result in the induction of genes encoding for vasoactivators, adhesion molecules, monocyte chemoattractants, and growth factors in endothelial cells, thus modulating vascular structure and function. Some of the effects of mechanical strain on endothelial cells are similar to those by shear stress, eg, the signaling pathways and the genes activated, but there are differences, eg, the time course of the responses. Studies on the effects of mechanical forces on signal transduction and gene expression provide insights into the molecular mechanisms by which hemodynamic factors regulate vascular physiology, and pathophysiology.
Collapse
Affiliation(s)
- S Chien
- Department of Bioengineering and Institute for Biomedical Engineering, University of California, San Diego, La Jolla 92093-0412, USA.
| | | | | |
Collapse
|
50
|
Abstract
Improved outcome after coronary bypass surgery over the last decade has been attributed largely to the increasing use of arterial conduits and their superior patency rates over that of saphenous vein grafts. In spite of this trend, autologous saphenous vein has remained an important and convenient conduit for a variety of operative scenarios, and is still used for more than 70% of grafts. As a result, vein graft failure continues to represent a significant clinical and economic burden upon the health care service. Between 15 to 30% of saphenous vein grafts occlude within the first year of surgery, increasing to over 50% after 10 years. By this time, more than 10% of patients will require further intervention to alleviate symptoms arising from occluded grafts and progression of native disease. Graft occlusion arises either from early thrombosis or the later onset of 'vein graft disease' and subsequent atherosclerotic changes.
Collapse
Affiliation(s)
- D Mehta
- Bristol Heart Institute, University of Bristol, UK
| | | | | | | |
Collapse
|