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Abstract
Major advances have been made over the last decade towards the elucidation of the molecular mechanisms involved in the endothelium-dependent regulation of vascular tone and blood flow. While the primary endothelium-derived vasodilator autacoid is nitric oxide, it is clear that epoxyeicosatrienoic acids and other endothelium-derived hyperpolarising factors, as well as endothelin-1 and reactive oxygen species, play a significant role in the regulation of vascular tone and gene expression. This review is intended as an overview of the signalling mechanisms that link haemodynamic stimuli (such as shear stress and cyclic stretch) and endothelial cell perturbation to the activation of enzymes generating vasoactive autacoids.
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Affiliation(s)
- R Busse
- Vascular Signalling Group, Institut für Kardiovaskuläre Physiologie, Klinikum der J.W. Goethe-Universität, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany
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52
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The Endothelium. Vasc Med 2006. [DOI: 10.1016/b978-0-7216-0284-4.50007-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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53
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Dixit M, Loot AE, Mohamed A, Fisslthaler B, Boulanger CM, Ceacareanu B, Hassid A, Busse R, Fleming I. Gab1, SHP2, and Protein Kinase A Are Crucial for the Activation of the Endothelial NO Synthase by Fluid Shear Stress. Circ Res 2005; 97:1236-44. [PMID: 16284184 DOI: 10.1161/01.res.0000195611.59811.ab] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Fluid shear stress enhances NO production in endothelial cells by a mechanism involving the activation of the phosphatidylinositol 3-kinase and the phosphorylation of the endothelial NO synthase (eNOS). We investigated the role of the scaffolding protein Gab1 and the tyrosine phosphatase SHP2 in this signal transduction cascade in cultured and native endothelial cells. Fluid shear stress elicited the phosphorylation and activation of Akt and eNOS as well as the tyrosine phosphorylation of Gab1 and its association with the p85 subunit of phosphatidylinositol 3-kinase and SHP2. Overexpression of a Gab1 mutant lacking the pleckstrin homology domain abrogated the shear stress–induced phosphorylation of Akt but failed to affect the phosphorylation or activity of eNOS. The latter response, however, was sensitive to a protein kinase A (PKA) inhibitor. Mutation of Gab1 Tyr627 to phenylalanine (YF-Gab1) to prevent the binding of SHP2 completely prevented the shear stress–induced phosphorylation of eNOS, leaving the Akt response intact. A dominant-negative SHP2 mutant prevented the activation of PKA and phosphorylation of eNOS without affecting that of Akt. Moreover, shear stress elicited the formation of a signalosome complex including eNOS, Gab1, SHP2 and the catalytic subunit of PKA. In isolated murine carotid arteries, flow-induced vasodilatation was prevented by a PKA inhibitor as well as by overexpression of either the YF-Gab1 or the dominant-negative SHP2 mutant. Thus, the shear stress–induced activation of eNOS depends on Gab1 and SHP2, which, in turn, regulate the phosphorylation and activity of eNOS by a PKA-dependent but Akt-independent mechanism.
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Affiliation(s)
- Madhulika Dixit
- Vascular Signalling Group, Institut für Kardiovaskuläre Physiologie, Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany
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54
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Li YSJ, Haga JH, Chien S. Molecular basis of the effects of shear stress on vascular endothelial cells. J Biomech 2005; 38:1949-71. [PMID: 16084198 DOI: 10.1016/j.jbiomech.2004.09.030] [Citation(s) in RCA: 593] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2004] [Accepted: 09/20/2004] [Indexed: 12/15/2022]
Abstract
Blood vessels are constantly exposed to hemodynamic forces in the form of cyclic stretch and shear stress due to the pulsatile nature of blood pressure and flow. Endothelial cells (ECs) are subjected to the shear stress resulting from blood flow and are able to convert mechanical stimuli into intracellular signals that affect cellular functions, e.g., proliferation, apoptosis, migration, permeability, and remodeling, as well as gene expression. The ECs use multiple sensing mechanisms to detect changes in mechanical forces, leading to the activation of signaling networks. The cytoskeleton provides a structural framework for the EC to transmit mechanical forces between its luminal, abluminal and junctional surfaces and its interior, including the cytoplasm, the nucleus, and focal adhesion sites. Endothelial cells also respond differently to different modes of shear forces, e.g., laminar, disturbed, or oscillatory flows. In vitro studies on cultured ECs in flow channels have been conducted to investigate the molecular mechanisms by which cells convert the mechanical input into biochemical events, which eventually lead to functional responses. The knowledge gained on mechano-transduction, with verifications under in vivo conditions, will advance our understanding of the physiological and pathological processes in vascular remodeling and adaptation in health and disease.
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Affiliation(s)
- Yi-Shuan J Li
- Department of Bioengineering, University of California, San Diego, La Jolla, 92093-0412, USA
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55
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Wunder C, Brock RW, Frantz S, Göttsch W, Morawietz H, Roewer N, Eichelbrönner O. Carbon monoxide, but not endothelin-1, plays a major role for the hepatic microcirculation in a murine model of early systemic inflammation. Crit Care Med 2005; 33:2323-31. [PMID: 16215388 DOI: 10.1097/01.ccm.0000182794.42733.71] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
OBJECTIVE Endothelin-1 and carbon monoxide play a major role in the regulation of liver microcirculation in numerous disease states. During sepsis and endotoxemia, elevated formation of endothelin-1 results in reduced sinusoidal blood flow. However, the role of carbon monoxide and endothelin-1 and its receptors endothelin receptor A and endothelin receptor B in the deranged liver microcirculation during early systemic inflammation remains unclear. DESIGN Prospective, randomized, controlled experiment. SETTING University animal laboratory. SUBJECTS Male C57/BL6 mice, weighing 23-27 g. INTERVENTIONS To induce a systemic inflammation, mice were treated with 1 hr of bilateral hind limb ischemia followed by 3 hrs or 6 hrs of reperfusion. Animals were randomly exposed to the nonselective endothelin receptor antagonist Ro-61-6612 (Tezosentan) and/or a continuous endothelin-1 infusion. Different animals were randomized to methylene chloride gavage or carbon monoxide inhalation during the reperfusion period. MEASUREMENTS AND MAIN RESULTS After ischemia/reperfusion, endothelin-1 plasma concentrations, endothelin-1 messenger RNA expression, and endothelin receptor A and B messenger RNA expression revealed no significant changes when compared with sham animals. After 6 hrs of ischemia/reperfusion, hepatic microcirculatory variables (sinusoidal density, sinusoidal diameter, and red blood cell velocity) deteriorated. Tezosentan after 6 hrs of ischemia/reperfusion did not improve the liver microcirculation, whereas the continuous infusion of endothelin-1 after 6 hrs of ischemia/reperfusion further impaired sinusoidal blood flow. Tezosentan treatment did not produce any alterations in hepatocellular injury or hepatic redox status when compared with the untreated animals receiving 6 hrs of ischemia/reperfusion. Animals receiving 6 hrs of ischemia/reperfusion and exposed to methylene chloride gavage or inhaled carbon monoxide during limb reperfusion showed significantly improved microcirculatory variables, hepatic redox status, and attenuated hepatocellular injury. CONCLUSIONS These data suggest that endothelin-1 and the endothelin receptors A and B are not responsible for the observed hepatic microcirculatory and cellular dysfunction during early systemic inflammation, but exposure to exogenous carbon monoxide protected the hepatic microcirculation and improved the impaired hepatic cellular integrity and the hepatocellular redox status.
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Affiliation(s)
- Christian Wunder
- Klinik und Poliklinik für Anästhesiologie, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
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56
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Elkouri S, Demers P, Sirois MG, Couturier A, Cartier R. Effect of chronic exercise and Angiotensin-converting enzyme inhibition on rodent thoracic aorta. J Cardiovasc Pharmacol 2005; 44:582-90. [PMID: 15505496 DOI: 10.1097/00005344-200411000-00011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Vascular reactivity can be modulated by local physical factors as well as pharmacologic manipulations. The aim of this study was to evaluate the effects of chronic exercise (EX) with or without the ACEI captopril (CAP) on vascular reactivity. Sixty-four Sprague-Dawley male rats were randomized into 4 groups (n = 16): group 1, control; group 2, captopril; group 3, exercise; and group 4, exercise and captopril. After 10 weeks of treatment, rats were killed, and their thoracic aortas harvested. Vascular reactivity was studied in an organ chamber (n = 12). Aortic endothelium constitutive nitric oxyde synthase (NOS3) expression was determined by Western blot analysis (n = 4). Endothelial-dependent relaxation was increased in both CAP and EX rats relative to the control group. Maximal aortic relaxations were enhanced in the CAP group, and potencies of these mediators were enhanced in the EX group (P < 0.05 versus control). Combined treatment did not result in a synergistic effect. NOS3 relative expressions were: group 1, 100%; group 2, 241%; group 3, 64%; and group 4, 108%. Exercise enhanced both potencies and efficacies of the mediators studied, whereas CAP increased mainly their efficacies. NOS3 protein expression was up-regulated in CAP-treated rats but not in exercised rats. These findings suggest different mechanisms for the observed increased vascular reactivity.
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MESH Headings
- Acetylcholine/pharmacology
- Adenosine Diphosphate/pharmacology
- Administration, Oral
- Angiotensin-Converting Enzyme Inhibitors/administration & dosage
- Angiotensin-Converting Enzyme Inhibitors/pharmacokinetics
- Animals
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/metabolism
- Aorta, Thoracic/ultrastructure
- Blood Pressure/physiology
- Blotting, Western/methods
- Body Weight/physiology
- Calcium/metabolism
- Captopril/administration & dosage
- Captopril/pharmacokinetics
- Down-Regulation/physiology
- Drug Administration Schedule
- Drug Evaluation, Preclinical/methods
- Endothelium, Vascular/chemistry
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/ultrastructure
- Heart
- Histamine/pharmacology
- Immunochemistry/methods
- Ionophores/pharmacology
- Male
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Nitric Oxide Synthase
- Nitric Oxide Synthase Type III
- Organ Size/physiology
- Phenylephrine/pharmacology
- Physical Conditioning, Animal/methods
- Physical Conditioning, Animal/physiology
- Rats
- Rats, Sprague-Dawley
- Time Factors
- Up-Regulation
- Vasodilation/drug effects
- Vasodilation/physiology
- von Willebrand Factor/chemistry
- von Willebrand Factor/immunology
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Affiliation(s)
- Stéphane Elkouri
- Department of Surgery, Montreal Heart Institute, Montreal, Quebec, Canada
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57
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Benigni A, Remuzzi G. The renoprotective potential of endothelin receptor antagonists. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.7.2.139] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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58
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Yang LL, Arab S, Liu P, Stewart DJ, Husain M. The role of endothelin-1 in myocarditis and inflammatory cardiomyopathy: old lessons and new insights. Can J Physiol Pharmacol 2005; 83:47-62. [PMID: 15759050 DOI: 10.1139/y05-002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Endothelin-1 has emerged as an important participant in the pathophysiology of a variety of cardiovascular diseases, where it may act on endocrine, paracrine and autocrine bases. Here we review its regulated biosynthesis, receptor-mediated signaling, and functional consequences in the heart, with particular emphasis on cardiac development and disease. Exploring published data employing molecular genetic mouse models of endothelin dysregulation, we highlight its heretofore underappreciated role as a pro-inflammatory cytokine. We also present novel micro-array data from one such mouse model, which implicate the specific downstream pathways that may mediate endothelin-1's effects.Key words: endothelin-1, cardiac development, inflammation, transgenic mice, gene expression profiling.
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Affiliation(s)
- Li L Yang
- Heart and Stroke Richard Lewar Centre of Excellence, University of Toronto, Toronto, ON, Canada
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59
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Lungu AO, Jin ZG, Yamawaki H, Tanimoto T, Wong C, Berk BC. Cyclosporin A inhibits flow-mediated activation of endothelial nitric-oxide synthase by altering cholesterol content in caveolae. J Biol Chem 2004; 279:48794-800. [PMID: 15383526 DOI: 10.1074/jbc.m313897200] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fluid shear stress generated by blood flowing over the endothelium is a major determinant of arterial tone, vascular remodeling, and atherogenesis. Nitric oxide (NO) produced by endothelial NO synthase (eNOS) plays an essential role in regulation of vascular function and structure by blood flow. Although cyclosporin A (CsA), an inhibitory ligand of cyclophilin A, is a widely used immunosuppressive drug, it causes arterial hypertension in part by impairing eNOS-dependent vasodilation. Here we show that CsA inhibits fluid shear stress-mediated eNOS activation in endothelial cells via decreasing cholesterol content in caveolae. Exposure of cultured bovine aortic endothelial cells to 1 mum CsA for 1 h significantly inhibited NO production and eNOS phosphorylation at Ser-1179 induced by flow (shear stress=dynes/cm2). The effect of CsA was not related to inhibition of two known eNOS kinases, protein kinase B (Akt) and protein kinase A, because CsA did not affect Akt or protein kinase A activation. In rabbit aorta perfused ex vivo, CsA also significantly inhibited flow-induced eNOS phosphorylation at Ser-1179 but had no effect on Akt measured by phosphorylation at Ser-473. However, CsA treatment decreased cholesterol content in caveolae and displaced eNOS from caveolae, which may be caused by CsA disrupting the association of caveolin-1 and cyclophilin A. The magnitude of the cholesterol depleting effect was similar to that of beta-cyclodextrin, a cholesterol-binding molecule, and beta-cyclodextrin had a similar inhibitory effect on flow-mediated eNOS activation. Treating bovine aortic endothelial cells for 24 h with 30 mug/ml cholesterol blocked the CsA effect and restored eNOS phosphorylation in response to flow. These data suggest that decreasing cholesterol content in caveolae by CsA is a potentially important pathogenic mechanism for CsA-induced endothelial dysfunction and hypertension.
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Affiliation(s)
- Andreea O Lungu
- Department of Medicine and Center for Cardiovascular Research, University of Rochester School of Medicine and Dentistry, Aab Institute of Biomedical Sciences, Rochester, New York 14642, USA
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60
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Boo YC, Jo H. Flow-dependent regulation of endothelial nitric oxide synthase: role of protein kinases. Am J Physiol Cell Physiol 2003; 285:C499-508. [PMID: 12900384 DOI: 10.1152/ajpcell.00122.2003] [Citation(s) in RCA: 286] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Vascular endothelial cells are directly and continuously exposed to fluid shear stress generated by blood flow. Shear stress regulates endothelial structure and function by controlling expression of mechanosensitive genes and production of vasoactive factors such as nitric oxide (NO). Though it is well known that shear stress stimulates NO production from endothelial nitric oxide synthase (eNOS), the underlying molecular mechanisms remain unclear and controversial. Shear-induced production of NO involves Ca2+/calmodulin-independent mechanisms, including phosphorylation of eNOS at several sites and its interaction with other proteins, including caveolin and heat shock protein-90. There have been conflicting results as to which protein kinases-protein kinase A, protein kinase B (Akt), other Ser/Thr protein kinases, or tyrosine kinases-are responsible for shear-dependent eNOS regulation. The functional significance of each phosphorylation site is still unclear. We have attempted to summarize the current status of understanding in shear-dependent eNOS regulation.
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Affiliation(s)
- Yong Chool Boo
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Tech and Emory University, Atlanta, GA 30322, USA.
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61
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Douthwaite JA, Lees DM, Corder R. A role for increased mRNA stability in the induction of endothelin-1 synthesis by lipopolysaccharide. Biochem Pharmacol 2003; 66:589-94. [PMID: 12906923 DOI: 10.1016/s0006-2952(03)00336-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
An association exists between infection and cardiovascular diseases, including atherosclerosis, stroke and myocardial infarction. This may involve endothelin-1 (ET-1) which has been implicated in these and other vascular pathologies. ET-1 synthesis is controlled primarily by the level of its mRNA and numerous stimuli, including infection, lead to elevated ET-1 levels. Here, we have investigated the regulation of ET-1 release and preproET-1 (ppET-1) mRNA in bovine aortic endothelial cells by lipopolysaccharide (LPS). ET-1 release from bovine aortic endothelial cells was stimulated by LPS and reporter gene assays implicated LPS-induced ppET-1 transcription. However, changes in transcription were modest compared to increases in ET-1 synthesis. Therefore, ppET-1 mRNA levels were measured by real-time reverse transcription-polymerase chain reaction. The effect of LPS on ppET-1 mRNA levels was more marked than on transcription (1.2-fold increase in transcription vs. 5.5-fold increase in ppET-1 mRNA). Analysis of ppET-1 mRNA stability by real-time reverse transcription-polymerase chain reaction showed that LPS increased its half-life by approximately 2-fold. Thus, upregulated ppET-1 mRNA and hence increased ET-1 synthesis may be due to both increased transcription and reduced mRNA degradation. These effects of LPS on mRNA stability may be a key mechanism in vascular pathologies through which many proteins are induced in response to infection.
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Affiliation(s)
- Julie A Douthwaite
- Department of Experimental Therapeutics, William Harvey Research Institute, St Bartholomew's and the Royal London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, EC1M 6BQ, London, UK.
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62
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Li X, Benjamin IS, Alexander B. The role of nitric oxide in systemic and hepatic haemodynamics in the rat in vivo. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2003; 368:142-9. [PMID: 12898126 DOI: 10.1007/s00210-003-0774-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2002] [Accepted: 05/26/2003] [Indexed: 02/07/2023]
Abstract
The physiological role of nitric oxide (NO) in portal venous and hepatic arterial haemodynamics in the rat in vivo during healthy and diseased conditions remains unclear. The present study determined the physiological role of nitric oxide in hepatic haemodynamics in the rat in vivo during healthy conditions as a basis for future pharmacological work. Male Wistar rats (300-350 g) were anaesthetised with fentany/fluanisone (0.3 mg/kg s.c.) and midazolam (0.3 mg/kg s.c.) and heparinised (30 U/100 g i.v.) via a cannulated left carotid artery for measurement of heart rate, mean arterial pressure, and the difference between systolic and diastolic blood pressures (P(S-D)). Following laparotomy, two distal ileocolic veins were cannulated, one catheter introduced to a distance of 1 cm and used for intraportal drug injections and the other to the main trunk of the portal vein for continuous measurement of portal venous pressure. The portal venous trunk and hepatic artery were carefully isolated and electromagnetic probes placed around each of them for measurement of portal venous flow and hepatic arterial flow. Augmentation of NO production was achieved by intraportal injection of 0.2, 0.4, 0.6 and 0.8 g/kg L-arginine and the NO donor, 3-morpholinosydnonimine (SIN-1), was injected intraportally at 0.2, 0.4, 0.6 and 0.8 mg/kg. L-NAME, the non-selective NOS inhibitor, was injected intraportally in increasing doses of 5, 10, 15 and 20 mg/kg in the absence or presence of L-arginine in doses of 0.2 and 0.5 g/kg. L-arginine increased portal blood flow by 25% without significant changes in systemic haemodynamics. SIN-1 decreased mean arterial pressure by 33% with no effect on portal blood flow. Both L-arginine and SIN-1 reduced portal venous pressure by 25% in a dose-dependent manner. L-NAME had no effect on portal haemodynamics despite a significant increase in systemic arterial pressure of 60% that was reduced dose-dependently by L-arginine. Hepatic arterial flow increased by 88% and 49% at the second and third doses of L-arginine and by 68% and 27% at the first two doses of L-NAME. No significant changes in hepatic arterial flow were found when L-NAME and L-arginine were given together. It is concluded that augmented endogenous NO production increased portal flow. Inhibition of endogenous NO had no effect on portal haemodynamics. Endogenous NO may not play a major role in regulation of portal haemodynamics in the rat in vivo.
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Affiliation(s)
- Xiangnong Li
- St Thomas's Hospital, Guy's, King's and St Thomas' School of Medicine, Lambeth Palace Road, SE1 7EH, London, UK
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63
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Popowski K, Sperker B, Kroemer HK, John U, Laule M, Stangl K, Cascorbi I. Functional significance of a hereditary adenine insertion variant in the 5'-UTR of the endothelin-1 gene. PHARMACOGENETICS 2003; 13:445-51. [PMID: 12893982 DOI: 10.1097/00008571-200308000-00002] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Endothelin-1 (ET-1) is known as a potent vasoconstrictor peptide and stimulator of cell proliferation. The human preproendothelin-1 mRNA contains a frequent adenine insertion polymorphism (allele frequency = 0.28) within the 5'-untranslated region (5'-UTR), 138 bp downstream of the transcription start site, which was assumed to be related to hypertension. This 5'-UTR variant could putatively influence the mRNA secondary structure and stability, efficacy of translation initiation, or binding of sequence-specific mRNA-binding proteins. By cloning the entire ET-1 gene 5'-UTR in a pGL3 vector and transfection of two cell lines, we studied the effects on luciferase expression in vitro. Luciferase activity was significantly increased in the insertion variant (I) compared to the wild-type (D) variant for both COS1 (2.97 +/- 0.12 versus 2.17 +/- 0.10; P = 0.002) and HepG2 cells (5.42 +/- 0.90 versus 3.68 +/- 0.37; P = 0.002). Investigations performed ex vivo using human umbilical vein endothelial cells were performed to examine the influence of genotypes on the formation of mRNA and protein. Preproendothelin-1-mRNA was quantified in relation to GAPDH by a realtime polymerase chain reaction. Homozygous I-carriers showed significant elevated mRNA levels compared to I/D and I/I-carriers (I/I 9.03 +/- 1.86, I/D 2.07 +/- 1.15, D/D 2.33 +/- 0.99; P = 0.001). ET-1 protein expression, determined by enzyme-linked immunosorbent assay, was increased among I-carriers (I/I 814 +/- 144, I/D 528 +/- 103, D/D 556 +/- 75 pg/ml; P = 0.001). The observed effects may be due to an enhanced mRNA stability because the half-life of mRNA consisting of the I-variant was prolonged (35.4 +/- 7.9 versus 19.9 +/- 4.5 min). We were able to show that the +138 I/D polymorphism is of functional importance for ET-1 expression, and this may have consequences for vessel tonus regulation.
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Affiliation(s)
- Katrin Popowski
- Peter Holtz Research Center of Pharmacology and Experimental Therapeutics, Department of Pharmacology, Ernst Moritz Arndt University-Greifswald, Friedrich-Loeffler-Strasse 20/21, D-17487 Greifswald, Germany
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64
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Tschumperlin DJ, Shively JD, Kikuchi T, Drazen JM. Mechanical stress triggers selective release of fibrotic mediators from bronchial epithelium. Am J Respir Cell Mol Biol 2003; 28:142-9. [PMID: 12540481 DOI: 10.1165/rcmb.2002-0121oc] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Transforming growth factor-beta (TGF-beta) and endothelin (ET) are found in elevated amounts in the airways of individuals with asthma. The cellular source of these peptides and their role in mediating the airway fibrosis of chronic asthma are unknown. In response to mechanical stresses similar to those occurring in vivo during airway constriction, bronchial epithelial cells increase the steady-state level of mRNA for both ET-1 and ET-2, followed by increased release of ET protein. Mechanical stress also enhances release of TGF-beta2 from a preformed cell-associated pool. TGF-beta2 and ET act individually and, more importantly, synergistically to promote fibrotic protein synthesis in reporter fibroblasts. To confirm the role of these intermediates in stress-induced fibrosis, conditioned medium from mechanically stressed bronchial epithelial cells was shown to elicit fibrotic protein synthesis in reporter fibroblasts; this effect was significantly inhibited by combined treatment with ET receptor antagonists and a neutralizing antibody to TGF-beta2. These data are consistent with a primary pathogenic role for mechanical stress-induced release of both TGF-beta2 and ET in the subepithelial fibrosis that characterizes chronic asthma.
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Affiliation(s)
- Daniel J Tschumperlin
- Pulmonary and Critical Care Division, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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65
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Affiliation(s)
- Don C Rockey
- Department of Medicine and The Liver Center, Duke University Medical Center, Durham, NC 27710, USA.
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66
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Boo YC, Hwang J, Sykes M, Michell BJ, Kemp BE, Lum H, Jo H. Shear stress stimulates phosphorylation of eNOS at Ser(635) by a protein kinase A-dependent mechanism. Am J Physiol Heart Circ Physiol 2002; 283:H1819-28. [PMID: 12384459 DOI: 10.1152/ajpheart.00214.2002] [Citation(s) in RCA: 178] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Shear stress stimulates nitric oxide (NO) production by phosphorylating endothelial NO synthase (eNOS) at Ser(1179) in a phosphoinositide-3-kinase (PI3K)- and protein kinase A (PKA)-dependent manner. The eNOS has additional potential phosphorylation sites, including Ser(116), Thr(497), and Ser(635). Here, we studied these potential phosphorylation sites in response to shear, vascular endothelial growth factor (VEGF), and 8-bromocAMP (8-BRcAMP) in bovine aortic endothelial cells (BAEC). All three stimuli induced phosphorylation of eNOS at Ser(635), which was consistently slower than that at Ser(1179). Thr(497) was rapidly dephosphorylated by 8-BRcAMP but not by shear and VEGF. None of the stimuli phosphorylated Ser(116). Whereas shear-stimulated Ser(635) phosphorylation was not affected by phosphoinositide-3-kinase inhibitors wortmannin and LY-294002, it was blocked by either treating the cells with a PKA inhibitor H89 or infecting them with a recombinant adenovirus-expressing PKA inhibitor. These results suggest that shear stress stimulates eNOS by two different mechanisms: 1) PKA- and PI3K-dependent and 2) PKA-dependent but PI3K-independent pathways. Phosphorylation of Ser(635) may play an important role in chronic regulation of eNOS in response to mechanical and humoral stimuli.
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Affiliation(s)
- Yong Chool Boo
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, Atlanta, GA 30322, USA
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67
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Hopkins N, McLoughlin P. The structural basis of pulmonary hypertension in chronic lung disease: remodelling, rarefaction or angiogenesis? J Anat 2002; 201:335-48. [PMID: 12430958 PMCID: PMC1570922 DOI: 10.1046/j.1469-7580.2002.00096.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chronic lung disease in humans is frequently complicated by the development of secondary pulmonary hypertension, which is associated with increased morbidity and mortality. Hypoxia, inflammation and increased shear stress are the primary stimuli although the exact pathways through which these initiating events lead to pulmonary hypertension remain to be completely elucidated. The increase in pulmonary vascular resistance is attributed, in part, to remodelling of the walls of resistance vessels. This consists of intimal, medial and adventitial hypertrophy, which can lead to encroachment into and reduction of the vascular lumen. In addition, it has been reported that there is a reduction in the number of blood vessels in the hypertensive lung, which could also contribute to increased vascular resistance. The pulmonary endothelium plays a key role in mediating and modulating these changes. These structural alterations in the pulmonary vasculature contrast sharply with the responses of the systemic vasculature to the same stimuli. In systemic organs, both hypoxia and inflammation cause angiogenesis. Furthermore, remodelling of the walls of resistance vessels is not observed in these conditions. Thus it has been generally stated that, in the adult pulmonary circulation, angiogenesis does not occur. Prompted by previous observations that chronic airway inflammation can lead to pulmonary vascular remodelling without hypertension, we have recently shown, using quantitative stereological techniques, that angiogenesis can occur in the adult pulmonary circulation. Pulmonary angiogenesis has also been reported in some other conditions including post-pneumonectomy lung growth, metastatic disease of the lung and in biliary cirrhosis. Such angiogenesis may serve to prevent or attenuate increased vascular resistance in lung disease. In view of these more recent data, the role of structural alterations in the pulmonary vasculature in the development of pulmonary hypertension should be carefully reconsidered.
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Affiliation(s)
- Natalie Hopkins
- Department of Human Anatomy and Physiology, Conway Institute of Biomolecular and Biomedical Research, Dublin, Ireland
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68
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Hillsley MV, Tarbell JM. Oscillatory shear alters endothelial hydraulic conductivity and nitric oxide levels. Biochem Biophys Res Commun 2002; 293:1466-71. [PMID: 12054680 DOI: 10.1016/s0006-291x(02)00410-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This study addresses the role of nitric oxide (NO) and downstream signaling pathways in mediating the influences of oscillatory shear stress on the hydraulic conductivity (L(p)) of bovine aortic endothelial cell (BAEC) monolayers. Exposure of BAEC monolayers to 20 dyne/cm2 steady shear stress for 3 h induced a 3.3-fold increase in L(p). When an oscillatory shear amplitude of 10 dyne/cm2 was superimposed on a steady shear of 10 dyne/cm2 to produce a non-reversing oscillatory shear pattern (10+/-10 dyne/cm2), L(p) increased by 3.0-fold within 90 min. When the amplitude was increased to 15 dyne/cm2, resulting in a reversing oscillatory shear pattern (10+/-15 dyne/cm2), the increase in L(p) over 3 h was completely suppressed. Twenty and 10+/-10 dyne/cm2 induced 2.9- and 2.6-fold increases in NO production above non-sheared controls, respectively, whereas 10+/-15 dyne/cm2 stimulated a 14-fold increase in NO production. The inhibition of L(p) with reversing oscillatory shear may be associated with alterations in cyclic guanosine monophosphate (cGMP) production downstream of NO which is up-regulated by reversing oscillatory shear, but is unaffected by steady shear.
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Affiliation(s)
- Mechteld V Hillsley
- Biomolecular Transport Dynamics Laboratory, Department of Chemical Engineering, The Pennsylvania State University, University Park, PA 16802-4400, USA
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69
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Abstract
OBJECTIVE The endothelium is normally subjected to mechanical deformation resulting from shear stress and from strain associated with stretch of the vessel wall. These stimuli are detected by a mechanosensor that initiates a variety of signaling systems responsible for triggering the functional responses. The identity of the mechanosensor has not been established. This article discusses the different mechanisms of mechanosensing that have been proposed and reviews the literature with respect to signaling systems that are activated in response to stress and strain in endothelium. DATA SOURCES Published literature related to mechanotransduction, signal transduction pathways initiated by strain in endothelium, and pathophysiologic effects of abnormal shear forces in diseases. DATA EXTRACTION AND SYNTHESIS Proposed mechanisms of mechanosensing include stretch-sensitive ion channels, protein kinases associated with the cytoskeleton, integrin-cytoskeletal interactions, cytoskeletal-nuclear interactions, and oxidase systems capable of generating reactive oxygen species. However, the molecular identity of the mechanosensor is not known, nor is it clear whether multiple sensing mechanisms exist. CONCLUSIONS Many responses are initiated in cells subjected to mechanical deformation, including alterations in ion channel conductance, activation of signal transduction pathways, and altered expression of specific genes. Future progress in this field will require a critical distinction between cell systems that become activated during mechanical strain and the identity of the cellular mechanosensor that triggers subsequent responses.
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Affiliation(s)
- Mir H Ali
- University of Chicago, Pulmonary and Critical Care Medicine, 5841 South Maryland Avenue, Chicago, IL, USA
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70
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Buus CL, Pourageaud F, Fazzi GE, Janssen G, Mulvany MJ, De Mey JG. Smooth muscle cell changes during flow-related remodeling of rat mesenteric resistance arteries. Circ Res 2001; 89:180-6. [PMID: 11463726 DOI: 10.1161/hh1401.093575] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To obtain information on the molecular and cellular mechanisms of flow-induced arterial remodeling, we analyzed the morphology and smooth muscle cell (SMC) characteristics in rat mesenteric resistance arteries after interventions that decreased and increased flow. Juvenile male Wistar Kyoto rats were subjected to surgery that, compared with control arteries, provided arteries with chronic low flow and chronic high flow. Low flow resulted in a decreased passive lumen diameter, hypotrophy of the artery wall, and both loss and decreased size of SMCs. Time course studies, with intervention length ranging from 2 to 32 days of altered blood flow, showed that the narrowing of the lumen diameter in low-flow arteries appeared within 2 days and that an early dedifferentiation of SMC phenotype was indicated by markedly reduced levels of desmin mRNA. High flow resulted in an increased passive lumen diameter and in hypertrophy of the artery wall. The hypertrophy resulted from SMC proliferation because SMC number, measured by the 3D-dissector technique, was increased and immunohistochemical assessment of proliferating cell nuclear antigen also showed an increase. The widening of high-flow arteries required 16 days to become established, at which time desmin mRNA was reduced. This time was also required to establish changed wall mass in both low-flow and high-flow arteries. Apoptotic cells detected by TdT-mediated dUTP-biotin nick end labeling staining were mainly located in the medial layer, and evaluation of DNA fragmentation indicated that increased apoptosis occurred in both low flow and high flow. This study shows for the first time direct evidence that reduced and elevated blood flow in resistance arteries produce, respectively, decrease and increase in SMC number, with dedifferentiation of the SMCs in both cases.
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Affiliation(s)
- C L Buus
- Department of Pharmacology, Cardiovascular Research Institute Maastricht, Universiteit Maastricht, The Netherlands
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71
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Chen J, Fabry B, Schiffrin EL, Wang N. Twisting integrin receptors increases endothelin-1 gene expression in endothelial cells. Am J Physiol Cell Physiol 2001; 280:C1475-84. [PMID: 11350743 DOI: 10.1152/ajpcell.2001.280.6.c1475] [Citation(s) in RCA: 160] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A magnetic twisting stimulator was developed based on the previously published technique of magnetic twisting cytometry. Using ligand-coated ferromagnetic microbeads, this device can apply mechanical stresses with varying amplitudes, duration, frequencies, and waveforms to specific cell surface receptors. Biochemical and biological responses of the cells to the mechanical stimulation can be assayed. Twisting integrin receptors with RGD (Arg-Gly-Asp)-containing peptide-coated beads increased endothelin-1 (ET-1) gene expression by >100%. In contrast, twisting scavenger receptors with acetylated low-density lipoprotein-coated beads or twisting HLA antigen with anti-HLA antibody-coated beads did not lead to alterations in ET-1 gene expression. In situ hybridization showed that the increase in ET-1 mRNA was localized in the cells that were stressed with the RGD-coated beads. Blocking stretch-activated ion channels with gadolinium, chelating Ca2+ with EGTA, or inhibiting tyrosine phosphorylation with genistein abolished twist-induced ET-1 mRNA elevation. Abolishing cytoskeletal tension with an inhibitor of the myosin ATPase, with an inhibitor of myosin light chain kinase, or with an actin microfilament disrupter blocked twisted-induced increases in ET-1 expression. Our results are consistent with the hypothesis that the molecular structural linkage of integrin-cytoskeleton is an important pathway for stress-induced ET-1 gene expression.
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MESH Headings
- Actins/analysis
- Cells, Cultured
- Cytological Techniques
- Cytoskeleton/physiology
- Endothelin-1/genetics
- Endothelium, Vascular/chemistry
- Endothelium, Vascular/physiology
- Endothelium, Vascular/ultrastructure
- Gene Expression/physiology
- Humans
- In Situ Hybridization
- Integrins/chemistry
- Integrins/physiology
- Magnetics
- Microscopy, Electron, Scanning
- Microspheres
- Protein Structure, Tertiary
- RNA, Messenger/analysis
- Receptors, Immunologic/chemistry
- Receptors, Immunologic/physiology
- Receptors, Peptide/chemistry
- Receptors, Peptide/physiology
- Stress, Mechanical
- Umbilical Veins/cytology
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Affiliation(s)
- J Chen
- Physiology Program, Department of Environmental Health, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115, USA
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72
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Xiong Y, Tanaka H, Richardson JA, Williams SC, Slaughter CA, Nakamura M, Chen JL, Yanagisawa M. Endothelin-1 stimulates leptin production in adipocytes. J Biol Chem 2001; 276:28471-7. [PMID: 11359784 DOI: 10.1074/jbc.m103478200] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Leptin is an adipocyte-derived hormone that regulates body fat stores and feeding behavior. In an effort to identify endogenous diffusible modulators of leptin production, we found that endothelin-1 (ET-1) up-regulates leptin expression in adipocytes. ET-1 is as potent and efficacious as insulin in stimulating leptin production in two different adipocyte cell lines. Endothelins stimulate leptin production via the endothelin-A receptor (ET(A)), as judged by a potency rank order of ET-1 ET-3. We detected expression of ET(A) but not ET(B) in both cell lines by Northern blot analysis. In addition, the ET(A)-selective antagonist FR139317 inhibited ET-1-induced leptin expression more potently than did the ET(B)-selective antagonist BQ788. ET-1 and insulin positively interact with each other in increasing leptin production in adipocytes. In primary mouse white fat cells, we detected expression of both ET(A) and ET(B) by Northern blot and in situ hybridization analyses. We conclude that ET-1 stimulates leptin production via the ET(A) receptor in cultured adipocytes.
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Affiliation(s)
- Y Xiong
- Howard Hughes Medical Institute and Department of Molecular Genetics, The University of Texas Southwestern Medical Center, Dallas, Texas 75390-9050, USA
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73
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Petkova SB, Huang H, Factor SM, Pestell RG, Bouzahzah B, Jelicks LA, Weiss LM, Douglas SA, Wittner M, Tanowitz HB. The role of endothelin in the pathogenesis of Chagas' disease. Int J Parasitol 2001; 31:499-511. [PMID: 11334935 DOI: 10.1016/s0020-7519(01)00168-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Infection with Trypanosoma cruzi causes a generalised vasculitis of several vascular beds. This vasculopathy is manifested by vasospasm, reduced blood flow, focal ischaemia, platelet thrombi, increased platelet aggregation and elevated plasma levels of thromboxane A(2) and endothelin-1. In the myocardium of infected mice, myonecrosis and a vasculitis of the aorta, coronary artery, smaller myocardial vessels and the endocardial endothelium are observed. Immunohistochemistry studies employing anti-endothelin-1 antibody revealed increased expression of endothelin-1, most intense in the endocardial and vascular endothelium. Elevated levels of mRNA for prepro endothelin-1, endothelin converting enzyme and endothelin-1 were observed in the infected myocardium. When T. cruzi-infected mice were treated with phosphoramidon, an inhibitor of endothelin converting enzyme, there was a decrease in heart size and severity of pathology. Mitogen-activated protein kinases and the transcription factor activator-protein-1 regulate the expression of endothelin-1. Therefore, we examined the activation of mitogen-activated protein kinases in the myocardium by T. cruzi. Western blot demonstrated an extracellular signal regulated kinase. In addition, the activator-protein-1 DNA binding activity, as determined by electrophoretic mobility shift assay, was increased. Increased expression of cyclins A and cyclin D1 was observed in the myocardium, and immunohistochemistry studies revealed that interstitial cells and vascular and endocardial endothelial cells stained intensely with antibodies to these cyclins. These data demonstrate that T. cruzi infection of the myocardium activates extracellular signal regulated kinase, activator-protein-1, endothelin-1, and cyclins. The activation of these pathways is likely to contribute to the pathogenesis of chagasic heart disease. These experimental observations suggest that the vasculature plays a role in the pathogenesis of chagasic cardiomyopathy. Additionally, the identification of these pathways provides possible targets for therapeutic interventions to ameliorate or prevent the development of cardiomyopathy during T. cruzi infection.
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Affiliation(s)
- S B Petkova
- Department of Pathology, Albert Einstein College of Medicine, Jacobi Medical Center, 1300 Morris Park Avenue, 10461, Bronx, NY, USA
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74
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Yamashita K, Discher DJ, Hu J, Bishopric NH, Webster KA. Molecular regulation of the endothelin-1 gene by hypoxia. Contributions of hypoxia-inducible factor-1, activator protein-1, GATA-2, AND p300/CBP. J Biol Chem 2001; 276:12645-53. [PMID: 11278891 DOI: 10.1074/jbc.m011344200] [Citation(s) in RCA: 263] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Endothelin-1 (ET-1) is a peptide hormone with potent vasoconstrictor properties which is synthesized and secreted predominantly by vascular endothelial cells. Its production is regulated by numerous stimuli including ischemia and hypoxia, and the enhanced levels that occur during myocardial ischemia may contribute to the progression of heart failure. We reported previously a preliminary characterization of a hypoxia-inducible factor-1 (HIF-1) binding site in the human ET-1 promoter which contributed to the activation of ET-1 expression in endothelial cells. We report here that the HIF-1 binding site alone is not sufficient for the response to hypoxia but requires an additional 50 base pairs of flanking sequence that includes binding sites for the factors activator protein-1 (AP-1), GATA-2, and CAAT-binding factor (NF-1). Mutation of any one of these sites or the HIF-1 site eliminated induction by hypoxia. Mutations of the AP-1 and GATA-2 sites, but not the HIF-1 site, were complemented by overexpressing AP-1, GATA-2, HIF-1alpha, or the activator protein p300/CBP, restoring the response to hypoxia. Binding studies in vitro confirmed physical associations among GATA-2, AP-1, and HIF-1 factors. Overexpression or depletion of p300/CBP modulated the level of ET-1 promoter expression as well as the endogenous ET-1 transcript but did not change the fold induction by hypoxia in either case. Regulation of the ET-1 promoter by hypoxia in non-endothelial cells required overexpression of GATA-2 and HIF-1alpha. The results support essential roles for AP-1, GATA-2, and NF-1 in stabilizing the binding of HIF-1 and promoting recruitment of p300/CBP to the ET-1 hypoxia response complex.
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Affiliation(s)
- K Yamashita
- Department of Molecular and Cellular Pharmacology, University of Miami Medical Center, Miami, Florida 33149, USA
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75
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Abstract
Vasoactive autocoids with directly opposing actions on the renal vasculature, glomerular function, and in salt and water homeostasis have been demonstrated in the kidney. In the renal cortex, endothelin (ET)-1 and angiotensin-II cause vasoconstriction, decreasing renal blood flow, and glomerular filtration rate, whereas bradykinin and atrial natriuretic peptide cause vasodilation and increase glomerular capillary permeability. ET-1 causes vasoconstriction of the afferent and efferent arteries and outer medullary descending vasa recta, thereby decreasing vasa recta and papillary blood flow, while bradykinin has the opposite effect. ET-1 stimulates cell proliferation, increasing the expression of several genes, including collagenase, prostaglandin endoperoxidase synthase, and platelet-derived growth factor. ET-1 promotes natriuresis via the ET-B receptor, causing down-regulation of the epithelial Na(+) channel in the renal tubule. Thus, ETs affect three major aspects of renal physiology: vascular and mesangial tone, Na(+) and water excretion, and cell proliferation and matrix formation.
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Affiliation(s)
- S Naicker
- Department of Medicine, Nelson R. Mandela School of Medicine, University of Natal, Durban, South Africa
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76
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Petkova SB, Tanowitz HB, Magazine HI, Factor SM, Chan J, Pestell RG, Bouzahzah B, Douglas SA, Shtutin V, Morris SA, Tsang E, Weiss LM, Christ GJ, Wittner M, Huang H. Myocardial expression of endothelin-1 in murine Trypanosoma cruzi infection. Cardiovasc Pathol 2000; 9:257-65. [PMID: 11064272 DOI: 10.1016/s1054-8807(00)00045-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Chagas' disease, caused by Trypanosoma cruzi, is an important cause of myocarditis and chronic cardiomyopathy and is accompanied by microvascular spasm and myocardial ischemia. We reported previously that infection of cultured endothelial cells with T. cruzi increased the synthesis of biologically active endothlein-1 (ET-1). In the present study, we examined the role of ET-1 in the cardiovascular system of CD1 mice infected with the Brazil strain of T. cruzi and C57BL/6 mice infected with the Tulahuen strain during acute infection. In the myocardium of infected mice myonecrosis and multiple pseudocysts were observed. There was also an intense vasculitis of the aorta, coronary artery, smaller myocardial vessels and the endocardial endothelium. Immunohistochemistry studies employing anti-ET-1 antibody revealed increased expression of ET-1 that was most intense in the endocardial and vascular endothelium. Elevated levels of mRNA for preproET-1, endothelin converting enzyme and ET-1 were observed in the same myocardial samples. Plasma ET-1 levels were significantly elevated in infected CD1 mice 10-15 days post infection. These observations suggest that increased levels of ET-1 are a consequence of the initial invasion of the cardiovascular system and provide a mechanism for infection-associated myocardial dysfunction.
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Affiliation(s)
- S B Petkova
- Departments of Pathology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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77
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Valen G, Paulsson G, Bennet AM, Hansson GK, Vaage J. Gene expression of inflammatory mediators in different chambers of the human heart. Ann Thorac Surg 2000; 70:562-7. [PMID: 10969681 DOI: 10.1016/s0003-4975(00)01507-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Inflammatory genes may be unevenly expressed in different heart chambers. METHODS Biopsies were taken simultaneously from the right atrium (RA), left atrium (LA), and left ventricle (LV) of 19 patients before cardioplegic arrest during open heart surgery. The mRNA expression of tumor necrosis factor alpha (TNFalpha), interleukin 1beta (IL-1beta), inducible and endothelial nitric oxide synthase (iNOS and eNOS), endothelin-1 (ET-1), E-selectin (CD62E), intercellular adhesion molecule-1 (ICAM-1) and its ligand CD18, and CD25 was evaluated with semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). RESULTS Expression of TNFalpha mRNA was higher in RA than LA and LV (p<0.05), whereas IL-1beta was more expressed in LA than RA (p<0.05), which was higher than LV (p<0.0001). There were no significant regional differences in the expression of ICAM-1, CD62E, CD25, iNOS, and eNOS. CD18 was higher in RA than LA (p<0.05); ET-1 was more expressed in RA than LV (p<0.04). Patients with stable angina had no expression of eNOS. CONCLUSIONS Gene expression of inflammatory mediators was detected in the hearts of patients with different cardiovascular disorders, and was unevenly distributed in different heart chambers. Cardiac biopsies should be taken from the same site.
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Affiliation(s)
- G Valen
- Department of Thoracic Surgery, Center for Molecular Medicine, Karolinska Hospital, Stockholm, Sweden.
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78
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Takeshita S, Inoue N, Ueyama T, Kawashima S, Yokoyama M. Shear stress enhances glutathione peroxidase expression in endothelial cells. Biochem Biophys Res Commun 2000; 273:66-71. [PMID: 10873565 DOI: 10.1006/bbrc.2000.2898] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hemodynamic forces have profound effects on vasculature. Laminar shear stress upregulates superoxide dismutase (SOD) expression in endothelial cells. SOD converts superoxide anion to H(2)O(2), which, however, promotes atherosclerosis. Therefore, defense against H(2)O(2) may be crucial in reducing oxidative stress. Since glutathione peroxidase (GPx-1) reduces H(2)O(2) to H(2)O, the regulation of GPx-1 expression by mechanical stress was examined. Cultured bovine aortic endothelial cells (BAECs) were subjected to laminar shear stress and stretch force. Shear stress upregulated GPx-1 mRNA expression in a time- and force-dependent manner in BAECs, whereas stretch force was without effect. Furthermore, shear stress increased GPx activity. L-NAME, an inhibitor of nitric oxide synthase, did not affect shear stress-induced GPx-1 mRNA expression. The ability of laminar shear stress to induce GPx-1 expression in endothelial cells may be an important mechanism whereby shear stress protects vascular cells against oxidative stress.
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Affiliation(s)
- S Takeshita
- First Department of Internal Medicine, Kobe University School of Medicine, Kobe, 650-0017, Japan
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79
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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.
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Affiliation(s)
- M B Kahaleh
- Department of Medicine, Richard Ruppert Health Center, Medical College of Ohio, Toledo 43614-5809, USA
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80
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Morawietz H, Talanow R, Szibor M, Rueckschloss U, Schubert A, Bartling B, Darmer D, Holtz J. Regulation of the endothelin system by shear stress in human endothelial cells. J Physiol 2000; 525 Pt 3:761-70. [PMID: 10856127 PMCID: PMC2269966 DOI: 10.1111/j.1469-7793.2000.00761.x] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
In this study, the effect of shear stress on the expression of genes of the human endothelin-1 system was examined. Primary cultures of human umbilical vein endothelial cells (HUVEC) were exposed to laminar shear stress of 1, 15 or 30 dyn cm-2 (i.e. 0.1, 1.5 or 3 N m-2) (venous and two different arterial levels of shear stress) in a cone-and-plate viscometer. Laminar shear stress transiently upregulates preproendothelin-1 (ppET-1) mRNA, reaching its maximum after 30 min (approx 1.7-fold increase). In contrast, long-term application of shear stress (24 h) causes downregulation of ppET-1 mRNA in a dose-dependent manner. Arterial levels of shear stress result in downregulation of endothelin-converting enzyme-1 isoform ECE-1a (predominating in HUVEC) to 36.2 +/- 8.5 %, and isoform ECE-1b mRNA to 72.3 +/- 1.9 % of static control level. The endothelin-1 (ET-1) release is downregulated by laminar shear stress in a dose-dependent manner. This downregulation of ppET-1 mRNA and ET-1 release is not affected by inhibition of protein kinase C (PKC), or tyrosine kinase. Inhibition of endothelial NO synthase (L-NAME, 500 microm) prevents downregulation of ppET-1 mRNA by shear stress. In contrast, increasing degrees of long-term shear stress upregulate endothelin receptor type B (ETB) mRNA by a NO- and PKC-, but not tyrosine kinase-dependent mechanism. In conclusion, our data suggest the downregulation of human endothelin synthesis, and an upregulation of the ETB receptor by long-term arterial laminar shear stress. These effects might contribute to the vasoprotective and anti-arteriosclerotic potential of arterial laminar shear stress.
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Affiliation(s)
- H Morawietz
- Institute of Pathophysiology, Faculty of Medicine, Martin Luther University Halle-Wittenberg, D-06097 Halle, Germany.
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81
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Matrougui K, Lévy BI, Henrion D. Tissue angiotensin II and endothelin-1 modulate differently the response to flow in mesenteric resistance arteries of normotensive and spontaneously hypertensive rats. Br J Pharmacol 2000; 130:521-6. [PMID: 10821779 PMCID: PMC1572118 DOI: 10.1038/sj.bjp.0703371] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In resistance arteries pressure-induced (myogenic) tone (MT) and flow (shear stress)-induced dilation (FD) are potent determinant of vascular resistance. We investigated the role of angiotensin II and endothelin-1 in FD and MT in resistance arteries and their potential change in hypertension. Flow - diameter - pressure relationship was established in situ, under anaesthesia, in two daughter branches of a mesenteric resistance artery (180 microM, n=7 per group) from spontaneously hypertensive (SHR) or normotensive (WKY) rats. One artery was ligated distally, so that it was submitted to pressure only, while the other was submitted to pressure and flow. Drugs were added to the preparation and external diameter, pressure and flow measured continuously. External diameter (with flow) ranged from 150+/-3 to 191+/-7 microM in WKY (n=28) rats and from 168+/-6 to 186+/-6 microM in SHR (n=28). Flow induced a dilation of the non-ligated arteries which was lower in SHR (13+/-5 - 31+/-4 microM vs WKY: 5+/-5 - 44+/-4 microM). In the ligated artery, the diameter did not significantly change, due to MT. In the vessels submitted to flow angiotensin converting enzyme inhibition (perindopril, 10 micromol L(-1)) increased the diameter in SHR (+11+/-2 microM) significantly more than in WKY (+2+/-1 microM). Angiotensin type 1 receptor (AT(1)R) blockade (losartan, 10 micromol L(-1)) increased the diameter in the vessels with flow in SHR only (+6+/-1 microM). Angiotensin type 2 receptor (AT(2)R) blockade (PD 123319, 1 micromol L(-1)) decreased arterial diameter in WKY only (9+/-2). Endothelin-1 type A receptor (ET(A)R) blockade (LU135252, 0.1 micromol L(-1)) increased the diameter only in SHR in the artery submitted to flow (by 6+/-1 microM). Thus FD was counteracted by a flow-dependent AT(1) and ET(A) receptors-activation in SHR whereas in WKY FD AT(2)-dependent dilation is involved.
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Affiliation(s)
- K Matrougui
- Institut National de la Santé et de la Recherche Médicale (INSERM) U 541, IFR 6, Université Paris VII, 41 Bd de la Chapelle, 75475 Paris, cedex 10, France
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82
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Lepailleur-Enouf D, Valdenaire O, Philippe M, Jandrot-Perrus M, Michel JB. Thrombin induces endothelin expression in arterial smooth muscle cells. Am J Physiol Heart Circ Physiol 2000; 278:H1606-12. [PMID: 10775140 DOI: 10.1152/ajpheart.2000.278.5.h1606] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Thrombin has been shown to stimulate endothelin release by endothelial cells, but the ability of thrombin to induce endothelin in nonendothelial cells is less well-known. Incubation of rat aortic smooth muscle cells with thrombin resulted in a stimulation of preproendothelin-1 (preproET-1) mRNA expression. This induction of preproET-1 mRNA expression by thrombin was accompanied by the release of immunoreactive peptide ET-1 into the extracellular medium. The synthetic thrombin receptor activator peptide (TRAP) confirmed ligand-specific receptor action to induce preproET-1 mRNA. Nuclear run-on analysis revealed that the transcriptional rate of preproET-1 mRNA increases twofold after 1 h of incubation with thrombin. In cells treated with thrombin, the half-life of preproET-1 mRNA was identical to that in untreated control cells. These results demonstrated that thrombin regulates endothelin synthesis at a transcriptional level but does not influence mRNA stability. Inhibition of protein kinase C (PKC) with selective inhibitors (chelerythrine and bisindolylmaleimide I) before thrombin stimulation failed to significantly inhibit preproET-1 gene expression. Inhibition of mitogen-activated protein (MAP) kinase kinase and protein tyrosine kinase decreased preproET-1 mRNA expression in thrombin-stimulated smooth muscle cells. Furthermore, addition of an activator of peroxisome proliferator-activated receptors-alpha (PPARalpha), fenofibrate, prevented the preproET-1 gene induction in response to thrombin. These results demonstrated that thrombin-induced endothelin gene transcription involved MAP kinase kinase rather than the PKC cascade in smooth muscle cells, which was repressed by PPARalpha stimulation.
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MESH Headings
- Animals
- Aorta
- Arteries/drug effects
- Arteries/metabolism
- Cells, Cultured
- Dose-Response Relationship, Drug
- Endothelin-1/genetics
- Endothelin-1/metabolism
- Endothelins/biosynthesis
- Endothelins/genetics
- Endothelins/metabolism
- Enzyme Inhibitors/pharmacology
- Gene Expression/drug effects
- Linear Models
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Peptide Fragments/pharmacology
- Protein Kinase C/drug effects
- Protein Kinase C/metabolism
- Protein Precursors/biosynthesis
- Protein Precursors/genetics
- Proteins/pharmacology
- RNA Polymerase II/antagonists & inhibitors
- RNA Stability/drug effects
- RNA, Messenger/biosynthesis
- Rats
- Receptor, PAR-1
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, Thrombin/metabolism
- Tetradecanoylphorbol Acetate/pharmacology
- Thrombin/metabolism
- Thrombin/pharmacology
- Transcription Factors/metabolism
- Transcription, Genetic/drug effects
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Affiliation(s)
- D Lepailleur-Enouf
- Institut National de la Santé et de la Recherche Médicale U460, UFR X. Bichat, 75018 Paris, France
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83
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Resnick N, Yahav H, Schubert S, Wolfovitz E, Shay A. Signalling pathways in vascular endothelium activated by shear stress: relevance to atherosclerosis. Curr Opin Lipidol 2000; 11:167-77. [PMID: 10787179 DOI: 10.1097/00041433-200004000-00010] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Major advances in our understanding of how endothelial cells sense and respond to haemodynamic forces and, more specifically, to fluid shear stress have been achieved during the past 3 years. These include definition of potential shear stress receptors and multiple signalling pathways that mediate shear stress regulation of gene expression. A few studies have also pointed to the unique effects of complex shear stress on endothelial activation, thus leading to better understanding of the mechanisms that lead to the development of atherosclerosis.
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Affiliation(s)
- N Resnick
- The Department of Anatomy and Cell Biology, Bruce Rappaport Research Institute, Bruce Rappaport Faculty of Medicine, Technion, Haifa, Israel.
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84
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Nakahashi T, Fujimura H, Altar CA, Li J, Kambayashi J, Tandon NN, Sun B. Vascular endothelial cells synthesize and secrete brain-derived neurotrophic factor. FEBS Lett 2000; 470:113-7. [PMID: 10734218 DOI: 10.1016/s0014-5793(00)01302-8] [Citation(s) in RCA: 330] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Brain-derived neurotrophic factor (BDNF) is an abundant neurotrophin in brain and peripheral nerves, where it affects neural development, survival and repair after injury. BDNF has been detected in rat and human blood, but the source of circulating BDNF is not established. BDNF messenger and peptide were detected in cultured cells and in the culture medium of human umbilical vein endothelial cells. The expression of BDNF was up-regulated by elevation of intracellular cAMP and down-regulated by Ca(2+) ionophore, bovine brain extract and laminar fluid shear stress. These results suggest that vascular endothelial cells may contribute to circulating BDNF.
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MESH Headings
- Animals
- Blood Platelets/cytology
- Blood Platelets/metabolism
- Brain/cytology
- Brain-Derived Neurotrophic Factor/biosynthesis
- Brain-Derived Neurotrophic Factor/genetics
- Brain-Derived Neurotrophic Factor/metabolism
- Calcimycin/pharmacology
- Calcium/metabolism
- Cattle
- Cell Extracts/pharmacology
- Cells, Cultured
- Colforsin/pharmacology
- Culture Media, Conditioned/chemistry
- Cyclic AMP/analogs & derivatives
- Cyclic AMP/metabolism
- Cyclic AMP/pharmacology
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Humans
- Interleukin-1/pharmacology
- Megakaryocytes/cytology
- Megakaryocytes/metabolism
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/metabolism
- RNA, Messenger/analysis
- RNA, Messenger/genetics
- Stress, Mechanical
- Time Factors
- Transforming Growth Factor beta/pharmacology
- Umbilical Veins/cytology
- Up-Regulation/drug effects
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Affiliation(s)
- T Nakahashi
- Maryland Research Laboratories, Otsuka America Pharmaceutical, Inc., 9900 Medical Center Drive, Rockville, MD 20850, USA
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85
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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.
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Affiliation(s)
- M Papadaki
- Department of Chemical Engineering and Harvard-MIT Health Science and Technology, Massachusetts Institute of Technology, Cambridge 02139, USA
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86
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Affiliation(s)
- D T Price
- Department of Medicine, Boston University School of Medicine, Massachusetts 02118, USA
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87
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88
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Abstract
Cardiac myocytes and vascular endothelial cells produce endothelin-1, which increases the contractility of cardiac muscles and of vascular smooth muscles. Endothelin-1 also exerts long-term effects, such as myocardial hypertrophy, and causes cellular injury in cardiac myocytes. In heart failure, the production of endothelin-1 is markedly increased in the failing heart. Here, evidence that an endothelin receptor antagonist is a useful new drug for the treatment of heart failure is discussed. Long-term treatment with an endothelin receptor antagonist greatly improves the survival rate of animals (rat, hamster, etc.) with chronic heart failure. This beneficial effect is accompanied by amelioration of left ventricular dysfunction. The myocardial endothelin system appears to be a novel and important target for therapeutic intervention in heart failure.
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Affiliation(s)
- T Miyauchi
- Department of Internal Medicine, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
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89
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Wung BS, Cheng JJ, Chao YJ, Hsieh HJ, Wang DL. Modulation of Ras/Raf/extracellular signal-regulated kinase pathway by reactive oxygen species is involved in cyclic strain-induced early growth response-1 gene expression in endothelial cells. Circ Res 1999; 84:804-12. [PMID: 10205148 DOI: 10.1161/01.res.84.7.804] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Endothelial cells (ECs) exposed to cyclic strain induce gene expression. To elucidate the signaling mechanisms involved, we studied the effects of cyclic strain on ECs by using early growth response-1 (Egr-1) as a target gene. Cyclic strain induced a transient increase of Egr-1 mRNA levels that resulted in an increase of binding of nuclear proteins to the Egr-1 binding sequences in the platelet-derived growth factor-A promoter region. ECs subjected to strain enhanced Egr-1 transcription as revealed by promoter activities. Catalase pretreatment inhibited this induction. ECs, transfected with a dominant positive mutant of Ras (RasL61), increased Egr-1 promoter activities. In contrast, transfection with a dominant negative mutant of Ras (RasN17) attenuated this strain inducibility. ECs transfected with a dominant negative mutant of Raf-1 (Raf301) or the catalytically inactive mutant of extracellular signal-regulated kinase (ERK)-2 (mERK2) diminished strain-induced promoter activities. However, little effect on strain inducibility was observed in ECs transfected with a dominant negative mutant of Rac (RacN17) or a catalytically inactive mutant of JNK (JNK[K-R]). Consistently, strain-induced Egr-1 expression was inhibited after ECs were treated with a specific inhibitor (PD98059) to mitogen-activated protein kinase kinase. Moreover, strain to ECs induced mitogen-activated protein kinase/ERK activity. The activation of the ERK pathway was further substantiated by an increase of strain-induced transcriptional activity of Elk1, an ERK substrate. This strain-induced ERK activity was attenuated after ECs were treated with N-acetylcysteine or catalase. Consequently, this Egr-1 gene induction was abolished after ECs were treated with N-acetylcysteine or catalase. Deletion analyses of the promoter region (-698 bp) indicated that cyclic strain and H2O2 shared a common serum response element. Our data clearly indicate that cyclic strain-induced Egr-1 expression is mediated mainly via the Ras/Raf-1/ERK pathway and that strain-induced reactive oxygen species can modulate Egr-1 expression at least partially via this signaling pathway.
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Affiliation(s)
- B S Wung
- Cardiovascular Division, Institute of Biomedical Sciences, Academia Sinica, and Department of Chemical Engineering, National Taiwan University, Taipei, Taiwan, ROC
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90
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Abstract
In this article, we review the basic pharmacological and biochemical features of endothelin and the pathophysiological roles of endothelin in cardiovascular diseases. Development of receptor antagonists has accelerated the pace of investigations into the pathophysiological roles of endogenous endothelin-1 in various diseases, e.g. chronic heart failure, renal diseases, hypertension, cerebral vasospasm, and pulmonary hypertension. In chronic heart failure, the expression of endothelin-1 and its receptors in cardiomyocytes is increased, and treatment with an endothelin receptor antagonist improves survival and cardiac function. Endothelin receptor antagonists also improve other cardiovascular diseases. These results suggest that the interference with endothelin pathway either by receptor blockade or by inhibition of endothelin converting enzyme may provide novel therapeutic drugs strategies for multiple disease states.
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Affiliation(s)
- T Miyauchi
- Department of Internal Medicine, University of Tsukuba, Ibaraki, Japan.
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91
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Calvo WJ, Hajduczok G, Russell JA, Diamond SL. Inhibition of nitric oxide but not prostacyclin prevents poststenotic dilatation in rabbit femoral artery. Circulation 1999; 99:1069-76. [PMID: 10051302 DOI: 10.1161/01.cir.99.8.1069] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Poststenotic dilatation (PSD) occurs in a low-pressure region where recirculation eddies oscillate in size during the cardiac cycle. NO may be an important mediator of PSD. METHODS AND RESULTS Femoral arteries of 7 adult male New Zealand White rabbits were stenosed bilaterally to achieve a diameter reduction of 70. 9+/-6.7% (n=14). At the time of stenosis, the adventitia of one of the arteries was coated with 1 mmol/L of NG-nitro-L-arginine methyl ester (L-NAME) in 22% (wt/vol) Pluronic gel, while the contralateral vessel was coated with gel without L-NAME. In stenosed femoral arteries that were treated with gel without L-NAME, a maximum PSD of 30.99+/-7.92% (n=7) was observed in polymer casts at 3 days relative to the mean proximal diameter of 1.57+/-0.25 mm at a position 12 mm upstream of each stenosis. In contrast, the vessels treated with L-NAME exhibited a maximum PSD of only 7.16+/-8.81% (n=7) relative to the mean proximal diameter of 1.55+/-0.16 mm. L-NAME caused a 76. 9% reduction (P<0.001, n=7) of PSD. Similarly, NG-monomethyl-L-arginine 1 mmol/L and NG-nitro-L-arginine 10 micromol/L attenuated PSD by 57.5% (P<0.001, n=6) and 63.9% (P<0.05, n=6), respectively. Indomethacin 10 micromol/L caused no reduction in PSD. Arterial rings obtained from the poststenotic region were more sensitive and responsive to acetylcholine than those obtained proximal to the stenosis. CONCLUSIONS NO, but not prostacyclin, is a major mediator of PSD.
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Affiliation(s)
- W J Calvo
- Bioengineering Laboratory, Department of Chemical Engineering, School of Medicine, State University of New York at Buffalo, New York, USA
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92
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Topper JN, Gimbrone MA. Blood flow and vascular gene expression: fluid shear stress as a modulator of endothelial phenotype. MOLECULAR MEDICINE TODAY 1999; 5:40-6. [PMID: 10088131 DOI: 10.1016/s1357-4310(98)01372-0] [Citation(s) in RCA: 240] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Vascular endothelium, the cellular monolayer lining the entire cardiovascular system, is exposed to a variety of biochemical and biomechanical stimuli. Fluid shear stresses generated by blood flow in the vasculature can profoundly influence the phenotype of the endothelium by regulating the activity of certain flow-sensitive proteins (for example, enzymes), as well as by modulating gene expression. The finding that specific fluid mechanical forces can alter endothelial structure and function has provided a framework for a mechanistic understanding of flow-dependent processes, ranging from vascular remodeling in response to hemodynamic changes, to the initiation and localization of chronic vascular diseases such as atherosclerosis.
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Affiliation(s)
- J N Topper
- Dept of Medicine, Stanford University School of Medicine, Falk Cardiovascular Research Center, CA 94305-5406, USA.
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93
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Park H, Go YM, St John PL, Maland MC, Lisanti MP, Abrahamson DR, Jo H. Plasma membrane cholesterol is a key molecule in shear stress-dependent activation of extracellular signal-regulated kinase. J Biol Chem 1998; 273:32304-11. [PMID: 9822710 DOI: 10.1074/jbc.273.48.32304] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Shear stress, the dragging force generated by fluid flow, differentially activates extracellular signal-regulated kinase (ERK) and c-Jun NH2-terminal kinase (JNK) in bovine aortic endothelial cells (BAEC) (Jo, H., Sipos, K., Go, Y. M., Law, R., Rong, J., and McDonald, J. M. (1997) J. Biol. Chem. 272, 1395-1401). Here, we examine whether cholesterol-enriched compartments in the plasma membrane are responsible for such differential regulation. Pretreatment of BAEC with a cholesterol-binding antibiotic, filipin, did not inhibit shear-dependent activation of JNK. In contrast, filipin and other membrane-permeable cholesterol-binding agents (digitonin and nystatin), but not the lipid-binding agent xylazine, inhibited shear-dependent activation of ERK. The effect of cholesterol-binding drugs did not appear to be due to membrane permeabilization, since treatment of BAEC with a detergent, Triton X-100 which also permeabilizes membranes, did not inhibit shear-dependent activation of ERK. Furthermore, shear-dependent activation of ERK, but not JNK, was inhibited by cyclodextrin, a membrane-impermeable cholesterol-binding agent, which removes cell-surface cholesterol. Moreover, the effects of cyclodextrin were prevented by adding cholesterol during the incubation. These results indicate that cholesterol or cholesterol-sensitive compartments in the plasma membrane play a selective and essential role in activation of ERK, but not JNK, by shear stress. Although exposure to shear stress (1 h) increased the number of caveolae by 3-fold, treatment with filipin had no effect in either control or shear-exposed cells suggesting that caveolae density per se is not a crucial determinant in shear-dependent ERK activation. In summary, the current study suggests that cholesterol-sensitive microdomains in the plasma membrane, such as caveolae-like domains, play a critical role in differential activation of ERK and JNK by shear stress.
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Affiliation(s)
- H Park
- Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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94
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Go YM, Park H, Maland MC, Darley-Usmar VM, Stoyanov B, Wetzker R, Jo H. Phosphatidylinositol 3-kinase gamma mediates shear stress-dependent activation of JNK in endothelial cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:H1898-904. [PMID: 9815099 DOI: 10.1152/ajpheart.1998.275.5.h1898] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Shear stress differentially activates extracellular signal-regulated kinase (ERK) and c-Jun NH2-terminal kinase (JNK) by mechanisms involving Galphai2 and Gbeta/gamma proteins, respectively, in bovine aortic endothelial cells (BAEC). The early events in this signaling mechanism by which G proteins regulate ERK and JNK in response to shear stress have not been defined. Here we show that BAEC endogenously express a G protein-dependent form of phosphatidylinositol 3-kinase, PI3Kgamma, and its activity is stimulated by shear stress. PI3Kgamma activity was measured in vitro using BAEC that were transiently transfected with an epitope-tagged PI3Kgamma (vsv-PI3Kgamma). Exposure of BAEC to shear stress rapidly and transiently stimulated the activity of vsv-PI3Kgamma (maximum by 15 s, with a return to basal after 1-min exposure to 5 dyn/cm2 shear stress). Activity of vsv-PI3Kgamma was stimulated by shear stress intensities as low as 0.5 dyn/cm2. Treatment of BAEC with an inhibitor of PI3K, wortmannin, inhibited shear-dependent activation of JNK but had no effect on that of ERK. Furthermore, expression of a kinase-inactive mutant (PI3KgammaK799R) in BAEC inhibited the shear-dependent activation of JNK but not ERK. Taken together, these results suggest that PI3Kgamma selectively regulates the shear-sensitive JNK pathway. This differential and novel signaling pathway may be responsible for coordinating various mechanosensitive events in endothelial cells.
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Affiliation(s)
- Y M Go
- Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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95
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McDowell CL, Papoutsakis ET. Increased agitation intensity increases CD13 receptor surface content and mRNA levels, and alters the metabolism of HL60 cells cultured in stirred tank bioreactors. Biotechnol Bioeng 1998. [DOI: 10.1002/(sici)1097-0290(19981020)60:2<239::aid-bit11>3.0.co;2-h] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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96
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Abstract
Shear stress and the endothelium. Vascular endothelial cells (ECs) in vivo are influenced by two distinct hemodynamic forces: cyclical strain due to vessel wall distention by transmural pressure, and shear stress, the frictional force generated by blood flow. Shear stress acts at the apical cell surface to deform cells in the direction of blood flow; wall distention tends to deform cells in all directions. The shear stress response differs, at least partly, from the cyclical strain response, suggesting that cytoskeletal strain alone cannot explain it. Acute shear stress in vitro elicits rapid cytoskeletal remodeling and activates signaling cascades in ECs, with the consequent acute release of nitric oxide and prostacyclin; activation of transcription factors nuclear factor (NF)kappaB, c-fos, c-jun and SP-1; and transcriptional activation of genes, including ICAM-1, MCP-1, tissue factor, platelet-derived growth factor-B (PDGF-B), transforming growth factor (TGF)-beta1, cyclooxygenase-II, and endothelial nitric oxide synthase (eNOS). This response thus shares similarities with EC responses to inflammatory cytokines. In contrast, ECs adapt to chronic shear stress by structural remodeling and flattening to minimize shear stress. Such cells become very adherent to their substratum and show evidence of differentiation. Increased adhesion following chronic shear stress has been exploited to generate vascular grafts with confluent EC monolayers, retained after implantation in vivo, thus overcoming a major obstacle to endothelialization of vascular prostheses.
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Affiliation(s)
- B J Ballermann
- Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
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97
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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.
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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
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Affiliation(s)
- T Murase
- Department of Geriatric Medicine, Graduate School of Medicine, Kyoto University, Japan
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98
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Hu J, Discher DJ, Bishopric NH, Webster KA. Hypoxia regulates expression of the endothelin-1 gene through a proximal hypoxia-inducible factor-1 binding site on the antisense strand. Biochem Biophys Res Commun 1998; 245:894-9. [PMID: 9588211 DOI: 10.1006/bbrc.1998.8543] [Citation(s) in RCA: 213] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Endothelin-1 (ET-1) is a peptide hormone with potent vasoconstrictor properties that is synthesized and secreted predominantly by vascular endothelial cells. Its production is regulated by numerous stimuli including ischemia and hypoxia, and the enhanced levels that occur during myocardial ischemia may contribute to the progression of heart failure. We previously reported that ET-1 expression was induced by both hypoxia and transition metals in endothelial cells (ECs). Here we define an element in the proximal promoter of the ET-1 gene that is responsible for this induction. By using deletions and site directed mutagenesis of the human ET-1 promoter, in combination with electrophoretic gel mobility shifts and transient expression assays in human ECs, we identified an active hypoxia-inducible factor 1 (HIF-1) binding site starting at position -118 upstream of the transcription start site on the non-coding DNA strand. Mutation of this site eliminated induction by hypoxia without affecting basal (aerobic) expression, and the mutated sequence did not display hypoxia-specific binding of HIF-1.
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Affiliation(s)
- J Hu
- Department of Molecular and Cellular Pharmacology, University of Miami Medical Center, Florida 33136, USA
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99
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Kosaki K, Ando J, Korenaga R, Kurokawa T, Kamiya A. Fluid shear stress increases the production of granulocyte-macrophage colony-stimulating factor by endothelial cells via mRNA stabilization. Circ Res 1998; 82:794-802. [PMID: 9562439 DOI: 10.1161/01.res.82.7.794] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
To investigate whether the production of colony-stimulating factors (CSFs) by vascular endothelial cells is regulated by hemodynamic force, we exposed cultured human umbilical vein endothelial cells (HUVECs) to controlled levels of shear stress in a flow-loading apparatus and examined changes in the production of CSFs at both the protein and mRNA level. Exposure of HUVECs to a shear stress of 15 and 25 dyne/cm2 markedly increased the release of granulocyte-macrophage CSF (GM-CSF) detected by ELISA to 5.0 and 9.5 times, respectively, the amount released by the static controls at 24 hours, but it had no significant influence on the release of granulocyte CSF or macrophage CSF. The results of reverse transcriptase-polymerase chain reaction demonstrated that GM-CSF mRNA began to increase as early as 2 hours after initiation of 15 dyne/cm2 shear stress and continued to increase with time, reaching a peak of about four times the control levels at 24 hours. This increase in GM-CSF mRNA levels in response to shear stress depended on protein synthesis, because it was blocked by cycloheximide. Neither nuclear run-on assay or luciferase assay using a reporter gene containing GM-CSF gene promoter showed any significant change in transcription of the GM-CSF gene even after 24-hour exposure to a shear stress of 15 dyne/cm2. Actinomycin D chase experiments using a competitive polymerase chain reaction showed that shear stress extended the half-life of GM-CSF mRNA from approximately 23 to 42 minutes in HUVECs. These findings suggest that fluid shear stress increases the production of GM-CSF in HUVECs via mRNA stabilization.
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Affiliation(s)
- K Kosaki
- Department of Orthopedic Surgery, Graduate School of Medicine, University of Tokyo, Japan
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100
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Jones GT, van Rij AM, Packer SG, Walker RJ, Stehbens WE. Venous endothelial changes in therapeutic arteriovenous fistulae. Atherosclerosis 1998; 137:149-56. [PMID: 9568747 DOI: 10.1016/s0021-9150(97)00271-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Specimens of veins of therapeutic arteriovenous fistulae from five patients were examined by an en face immunohistochemical technique to investigate endothelial morphology and the presence of the vasoactive peptide endothelin-1 (ET-1). These were compared with control segments of long saphenous veins from six patients. Venous endothelium from the arteriovenous shunts was mostly intact even overlying phlebosclerotic plaques. Occasional small areas of denudation, with associated platelets, were present in the depressions of 'jet' lesion however. The endothelial cells were generally elongated and interspersed with foci of polyhedral cells. The control saphenous veins contained elongated endothelial cells without detectable denudation. Image analysis of histological sections of veins from the shunts indicated significantly less intact elastic tissue than control veins but greater mononucleated endothelial cell density in en face preparations. ET-1 staining was considerably stronger in endothelium from the fistulae than in the control saphenous veins and was most intense over the raised crescentic ridges of jet lesions, stenoses and phlebosclerotic plaques. Endothelial mitoses and cells with hyperchromatic nuclei stained more strongly for ET-1 than surrounding cells. These results indicate that the endothelial cells lining veins associated with arteriovenous fistulae are dynamically altered by the increased haemodynamic stresses associated with these shunts. Furthermore ET-1 may act as a localising factor associated with intimal thickening at sites of 'jet' lesions, stenosis and phlebosclerosis.
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Affiliation(s)
- G T Jones
- Department of Surgery, Otago Medical School, Dunedin, New Zealand.
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