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Bondarenko AI. Endothelial atypical cannabinoid receptor: do we have enough evidence? Br J Pharmacol 2014; 171:5573-88. [PMID: 25073723 PMCID: PMC4290703 DOI: 10.1111/bph.12866] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Revised: 07/14/2014] [Accepted: 07/24/2014] [Indexed: 12/16/2022] Open
Abstract
Cannabinoids and their synthetic analogues affect a broad range of physiological functions, including cardiovascular variables. Although direct evidence is still missing, the relaxation of a vast range of vascular beds induced by cannabinoids is believed to involve a still unidentified non-CB1 , non-CB2 Gi/o protein-coupled receptor located on endothelial cells, the so called endothelial cannabinoid receptor (eCB receptor). Evidence for the presence of an eCB receptor comes mainly from vascular relaxation studies, which commonly employ pertussis toxin as an indicator for GPCR-mediated signalling. In addition, a pharmacological approach is widely used to attribute the relaxation to eCB receptors. Recent findings have indicated a number of GPCR-independent targets for both agonists and antagonists of the presumed eCB receptor, warranting further investigations and cautious interpretation of the vascular relaxation studies. This review will provide a brief historical overview on the proposed novel eCB receptor, drawing attention to the discrepancies between the studies on the pharmacological profile of the eCB receptor and highlighting the Gi/o protein-independent actions of the eCB receptor inhibitors widely used as selective compounds. As the eCB receptor represents an attractive pharmacological target for a number of cardiovascular abnormalities, defining its molecular identity and the extent of its regulation of vascular function will have important implications for drug discovery. This review highlights the need to re-evaluate this subject in a thoughtful and rigorous fashion. More studies are needed to differentiate Gi/o protein-dependent endothelial cannabinoid signalling from that involving the classical CB1 and CB2 receptors as well as its relevance for pathophysiological conditions.
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Affiliation(s)
- Alexander I Bondarenko
- Circulatory Physiology Department, O.O.Bogomoletz Institute of PhysiologyKiev, Ukraine
- Institute of Molecular Biology and Biochemistry, Medical University of GrazGraz, Austria
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2
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Vaessen SFC, Bruysters MWP, Vandebriel RJ, Verkoeijen S, Bos R, Krul CAM, Akkermans AM. Toward a mechanism-based in vitro safety test for pertussis toxin. Hum Vaccin Immunother 2014; 10:1391-5. [PMID: 24553455 DOI: 10.4161/hv.28001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Pertussis vaccines are routinely administered to infants to protect them from whooping cough. Still, an adequate safety test for pertussis toxin (PT), one of the main antigens in these vaccines, is not available. The histamine sensitization test is currently the only assay accepted by regulatory authorities to test for the absence of active PT in vaccines. This is however, a lethal animal test with poor reproducibility. In addition, it is not clear whether the assumed underlying mechanism, i.e., ADP-ribosylation of G proteins, is the only effect that should be considered in safety evaluation of PT. The in vitro safety test for PT that we developed is based on the clinical effects of PT in humans. For this, human cell lines were chosen based on the cell types involved in the clinical effects of PT. These cell lines were exposed to PT and analyzed by microarray. In this review, we discuss the clinical effects of PT and the mechanisms that underlie them. The approach taken may provide as an example for other situations in which an in vitro assay based on clinical effects in humans is required.
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Affiliation(s)
- Stefan F C Vaessen
- Research Centre Technology & Innovation; Innovative testing in Life sciences and Chemistry; University of Applied Sciences; Utrecht, the Netherlands
| | - Martijn W P Bruysters
- Center for Health Protection; National Institute for Public Health and the Environment; Bilthoven, the Netherlands
| | - Rob J Vandebriel
- Center for Health Protection; National Institute for Public Health and the Environment; Bilthoven, the Netherlands
| | - Saertje Verkoeijen
- Research Centre Technology & Innovation; Innovative testing in Life sciences and Chemistry; University of Applied Sciences; Utrecht, the Netherlands
| | - Rogier Bos
- Central Committee on Research Involving Human Subjects; Den Haag, the Netherlands
| | - Cyrille A M Krul
- Research Centre Technology & Innovation; Innovative testing in Life sciences and Chemistry; University of Applied Sciences; Utrecht, the Netherlands
| | - Arnoud M Akkermans
- Center for Health Protection; National Institute for Public Health and the Environment; Bilthoven, the Netherlands
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3
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Alfaro J, Grau M, Serrano M, Checa AI, Criado LM, Moreno E, Paz-Artal E, Mellado M, Serrano A. Blockade of endothelial G(i) protein enhances early engraftment in intraportal cell transplant to mouse liver. Cell Transplant 2013; 21:1383-96. [PMID: 22525519 DOI: 10.3727/096368912x640501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The limited availability of liver donors and recent progress in cell therapy technologies has centered interest on cell transplantation as a therapeutic alternative to orthotopic liver transplant for restoring liver function. Following transplant by intraportal perfusion, the main obstacle to cell integration in the parenchyma is the endothelial barrier. Transplanted cells form emboli in the portal branches, inducing ischemia and reperfusion injury, which cause disruption of endothelial impermeability and activate the immune system. Approximately 95% of transplanted cells fail to implant and die within hours by anoikis or are destroyed by the host immune system. Intravascular perfusion of Bordetella pertussis toxin (PTx) blocks endothelial G(i) proteins and acts as a reversible inducer of actin cytoskeleton reorganization, leading to interruption of cell confluence in vitro and increased vascular permeability in vivo. PTx treatment of the murine portal vascular tree 2 h before intraportal perfusion of embryonic stem cells facilitated rapid cell engraftment. By 2 h postperfusion, the number of implanted cells in treated mice was more than fivefold greater than in untreated controls, a difference that was maintained to at least 30 days posttransplant. We conclude that prior to cell transplant, PTx blockade of the G(i) protein pathway in liver endothelium promotes rapid, efficient cell implantation in liver parenchyma, and blocks chemokine receptor signaling, an essential step in early activation of the immune system.
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Affiliation(s)
- Javier Alfaro
- Cell Transplantation Unit, Department of Immunology Hospital Universitario 12 de Octubre, 28041 Madrid, Spain
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Murugesan N, Paul D, Lemire Y, Shrestha B, Ge S, Pachter JS. Active induction of experimental autoimmune encephalomyelitis by MOG35-55 peptide immunization is associated with differential responses in separate compartments of the choroid plexus. Fluids Barriers CNS 2012; 9:15. [PMID: 22870943 PMCID: PMC3493354 DOI: 10.1186/2045-8118-9-15] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Accepted: 07/30/2012] [Indexed: 01/06/2023] Open
Abstract
UNLABELLED BACKGROUND There is increasing awareness that, aside from producing cerebrospinal fluid, the choroid plexus (CP) might be a key regulator of immune activity in the central nervous system (CNS) during neuroinflammation. Specifically, the CP has recently been posited to control entry of sentinel T cells into the uninflamed CNS during the early stages of neuroinflammatory diseases, like multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). As the CP is compartmentalized into a stromal core containing fenestrated capillaries devoid of typical blood-brain barrier properties, surrounded by a tight junction-expressing choroidal epithelium, each of these compartments might mount unique responses that instigate the neuroinflammatory process. METHODS To discern responses of the respective CP stromal capillary and choroidal epithelial tissues during evolving neuroinflammation, we investigated morphology and in situ expression of 93 immune-related genes during early stages of EAE induced by immunization with myelin oligodendrocyte glycoprotein peptide (MOG35-55). Specifically, 3-D immunofluorescent imaging was employed to gauge morphological changes, and laser capture microdissection was coupled to an Immune Panel TaqMan Low Density Array to detail alterations in gene expression patterns at these separate CP sites on days 9 and 15 post-immunization (p.i.). To resolve CP effects due to autoimmunity against MOG peptide, from those due to complete Freund's adjuvant (CFA) and pertussis toxin (PTX) included in the immunization, analysis was performed on MOG-CFA/PTX-treated, CFA/PTX-treated, and naïve cohorts. RESULTS The CP became swollen and displayed significant molecular changes in response to MOG-CFA/PTX immunization. Both stromal capillary and choroidal epithelial tissues mounted vigorous, yet different, changes in expression of numerous genes over the time course analyzed - including those encoding adhesion molecules, cytokines, chemokines, statins, interleukins, T cell activation markers, costimulatory molecules, cyclooxygenase, pro-inflammatory transcription factors and pro-apoptotic markers. Moreover, CFA/PTX-treatment, alone, resulted in extensive, though less robust, alterations in both CP compartments. CONCLUSIONS MOG-CFA/PTX immunization significantly affects CP morphology and stimulates distinct expression patterns of immune-related genes in CP stromal capillary and epithelial tissues during evolving EAE. CFA/PTX treatment, alone, causes widespread gene alterations that could prime the CP to unlock the CNS to T cell infiltration during neuroinflammatory disease.
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Affiliation(s)
- Nivetha Murugesan
- Blood-brain Barrier Laboratory, Department of Cell Biology, University of Connecticut Health Center, 263 Farmington Ave, Farmington, CT, 06030, USA.
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5
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Schneider OD, Millen SH, Weiss AA, Miller WE. Mechanistic insight into pertussis toxin and lectin signaling using T cells engineered to express a CD8α/CD3ζ chimeric receptor. Biochemistry 2012; 51:4126-37. [PMID: 22551306 DOI: 10.1021/bi3002693] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Mammalian cell-surface receptors typically display N- or O-linked glycans added post-translationally. Plant lectins such as phytohemagluttinin (PHA) can activate the T cell receptor (TCR) and other cell-surface receptors by binding to glycans and initiating receptor cross-linking. Pathogenic microorganisms such as Bordetella pertussis also express proteins with lectin-like activities. Similar to plant lectins, pertussis toxin (PTx) can activate the TCR and bind to a variety of glycans. However, whether the lectin-like activity of PTx is responsible for its ability to activate TCR signaling has not been formally proven. Here we examined the ability of PTx and a panel of lectins to activate the TCR or a CD8α/CD3ζ chimeric receptor (termed CD8ζ). We demonstrate that CD8ζ rescues PTx-induced signaling events lacking in TCR null cells. This result indicates that CD8ζ can substitute for TCR and supports the hypothesis that PTxB (functioning as a lectin) stimulates signaling via receptor cross-linking rather than by binding to a specific epitope on the TCR. Moreover, PTx is able to activate signaling by binding either N-linked or O-linked glycan-modified receptors as the TCR displays N-linked glycans while CD8ζ displays O-linked glycans. Finally, studies with a diverse panel of lectins indicate that the signaling activity of the lectins does not always correlate with the biochemical reports of ligand preferences. Comparison of lectin signaling through TCR or CD8ζ allows us to better define the structural and functional properties of lectin-glycan interactions using a biologically based signaling readout.
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Affiliation(s)
- Olivia D Schneider
- Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
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Barrows ND, Nelson OL, Robbins CT, Rourke BC. Increased cardiac alpha-myosin heavy chain in left atria and decreased myocardial insulin-like growth factor (Igf-I) expression accompany low heart rate in hibernating grizzly bears. Physiol Biochem Zool 2011; 84:1-17. [PMID: 21117961 DOI: 10.1086/657589] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Grizzly bears (Ursus arctos horribilis) tolerate extended periods of extremely low heart rate during hibernation without developing congestive heart failure or cardiac chamber dilation. Left ventricular atrophy and decreased left ventricular compliance have been reported in this species during hibernation. We evaluated the myocardial response to significantly reduced heart rate during hibernation by measuring relative myosin heavy-chain (MyHC) isoform expression and expression of a set of genes important to muscle plasticity and mass regulation in the left atria and left ventricles of active and hibernating bears. We supplemented these data with measurements of systolic and diastolic function via echocardiography in unanesthetized grizzly bears. Atrial strain imaging revealed decreased atrial contractility, decreased expansion/reservoir function (increased atrial stiffness), and decreased passive-filling function (increased ventricular stiffness) in hibernating bears. Relative MyHC-α protein expression increased significantly in the atrium during hibernation. The left ventricle expressed 100% MyHC-β protein in both groups. Insulin-like growth factor (IGF-I) mRNA expression was reduced by ∼50% in both chambers during hibernation, consistent with the ventricular atrophy observed in these bears. Interestingly, mRNA expression of the atrophy-related ubiquitin ligases Muscle Atrophy F-box (MAFBx) and Muscle Ring Finger 1 did not increase, nor did expression of myostatin or hypoxia-inducible factor 1α (HIF-1α). We report atrium-specific decreases of 40% and 50%, respectively, in MAFBx and creatine kinase mRNA expression during hibernation. Decreased creatine kinase expression is consistent with lowered energy requirements and could relate to reduced atrial emptying function during hibernation. Taken together with our hemodynamic assessment, these data suggest a potential downregulation of atrial chamber function during hibernation to prevent fatigue and dilation due to excessive work against an optimally filled ventricle, a response unpredicted by the Frank-Starling mechanism.
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Affiliation(s)
- N D Barrows
- Department of Biological Sciences, California State University, Long Beach, California 90840, USA
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7
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Mangmool S, Kurose H. G(i/o) protein-dependent and -independent actions of Pertussis Toxin (PTX). Toxins (Basel) 2011; 3:884-99. [PMID: 22069745 PMCID: PMC3202852 DOI: 10.3390/toxins3070884] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 06/14/2011] [Accepted: 06/16/2011] [Indexed: 12/22/2022] Open
Abstract
Pertussis toxin (PTX) is a typical A-B toxin. The A-protomer (S1 subunit) exhibits ADP-ribosyltransferase activity. The B-oligomer consists of four subunits (S2 to S5) and binds extracellular molecules that allow the toxin to enter the cells. The A-protomer ADP-ribosylates the α subunits of heterotrimeric Gi/o proteins, resulting in the receptors being uncoupled from the Gi/o proteins. The B-oligomer binds proteins expressed on the cell surface, such as Toll-like receptor 4, and activates an intracellular signal transduction cascade. Thus, PTX modifies cellular responses by at least two different signaling pathways; ADP-ribosylation of the Gαi/o proteins by the A-protomer (Gi/o protein-dependent action) and the interaction of the B-oligomer with cell surface proteins (Gi/o protein-independent action).
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Affiliation(s)
- Supachoke Mangmool
- Department of Pharmacology, Faculty of Pharmacy, Mahidol University, 447 Sri-Ayudhaya, Rajathevi, Bangkok 10400, Thailand;
| | - Hitoshi Kurose
- Department of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
- Author to whom correspondence should be addressed; ; Tel.: +81-92-642-6884; Fax: +81-92-642-6884
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8
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Yang YY, Lin HC, Huang YT, Lee TY, Hou MC, Wang YW, Lee FY, Lee SD. Role of Ca2+-dependent potassium channels in in vitro anandamide-mediated mesenteric vasorelaxation in rats with biliary cirrhosis. Liver Int 2007; 27:1045-55. [PMID: 17845532 DOI: 10.1111/j.1478-3231.2007.01551.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND/AIM Anandamide can activate potassium (K(+)) channels to induce an endothelium-dependent vasorelaxation in normal rat mesenteric arteries. Cannabinoids contribute partly to the splanchnic vasodilation in cirrhosis. This study investigated the roles of vascular K(+) channels in anandamide-induced mesenteric vasorelaxation in isolated rat cirrhotic vessels. METHODS The effects of the pretreatment of AM251, a specific CB(1) receptor antagonist, were assessed on the vascular reactivity to phenylephrine (PE), potassium chloride (KCl), acetylcholine (ACh) and sodium nitroprusside (SNP). Additionally, cannabinoid (CB(1) and CB(2)) receptors' protein expression and the effects of different K(+) channel blockers on vascular reactivity to anandamide were also studied. RESULTS Cirrhotic mesenteric arteries showed an overexpression of CB(1) receptor associated with hyporeactivity to PE and KCl, and hyper-response to ACh, SNP and anandamide. Pretreatment with AM251 significantly improved the hyporeactivity to KCl and ameliorated the hyper-response to ACh in cirrhotic vessels. Increased relaxation response to anandamide was suppressed by combinations of vascular Ca(2+)-dependent K(+) channel blockers (including apamin+charybdotoxin+iberiotoxin or apamin+TRAM-34+iberiotoxin) (TRAM-34, 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole). CONCLUSIONS In cirrhotic mesenteric arteries, vascular CB(1) receptor and anandamide contribute to the in vitro hyporeactivity to KCl. In addition, hyper-response to ACh may probably act through the modulation of vascular Ca(2+)-dependent K(+) channels.
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MESH Headings
- Acetylcholine/pharmacology
- Animals
- Apamin/pharmacology
- Arachidonic Acids/metabolism
- Cannabinoid Receptor Modulators/metabolism
- Charybdotoxin/pharmacology
- Common Bile Duct/surgery
- Dose-Response Relationship, Drug
- Endocannabinoids
- Glyburide/pharmacology
- Ligation
- Liver Cirrhosis, Biliary/metabolism
- Liver Cirrhosis, Biliary/physiopathology
- Liver Cirrhosis, Experimental/metabolism
- Liver Cirrhosis, Experimental/physiopathology
- Male
- Mesenteric Artery, Superior/drug effects
- Mesenteric Artery, Superior/metabolism
- Mesenteric Artery, Superior/physiopathology
- Nitroprusside/pharmacology
- Peptides/pharmacology
- Phenylephrine/pharmacology
- Piperidines/pharmacology
- Polyunsaturated Alkamides/metabolism
- Potassium/metabolism
- Potassium Channel Blockers/pharmacology
- Potassium Channels, Calcium-Activated/antagonists & inhibitors
- Potassium Channels, Calcium-Activated/metabolism
- Potassium Chloride/pharmacology
- Pyrazoles/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/metabolism
- Receptor, Cannabinoid, CB2/metabolism
- Vasoconstrictor Agents/pharmacology
- Vasodilation/drug effects
- Vasodilator Agents/pharmacology
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Affiliation(s)
- Ying-Ying Yang
- Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan
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Radke MH, Peng J, Wu Y, McNabb M, Nelson OL, Granzier H, Gotthardt M. Targeted deletion of titin N2B region leads to diastolic dysfunction and cardiac atrophy. Proc Natl Acad Sci U S A 2007; 104:3444-9. [PMID: 17360664 PMCID: PMC1805563 DOI: 10.1073/pnas.0608543104] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Titin is a giant protein that is in charge of the assembly and passive mechanical properties of the sarcomere. Cardiac titin contains a unique N2B region, which has been proposed to modulate elasticity of the titin filament and to be important for hypertrophy signaling and the ischemic stress response through its binding proteins FHL2 and alphaB-crystallin, respectively. To study the role of the titin N2B region in systole and diastole of the heart, we generated a knockout (KO) mouse deleting only the N2B exon 49 and leaving the remainder of the titin gene intact. The resulting mice survived to adulthood and were fertile. Although KO hearts were small, they produced normal ejection volumes because of an increased ejection fraction. FHL2 protein levels were significantly reduced in the KO mice, a finding consistent with the reduced size of KO hearts. Ultrastructural analysis revealed an increased extension of the remaining spring elements of titin (tandem Ig segments and the PEVK region), which, together with the reduced sarcomere length and increased passive tension derived from skinned cardiomyocyte experiments, translates to diastolic dysfunction as documented by echocardiography. We conclude from our work that the titin N2B region is dispensable for cardiac development and systolic properties but is important to integrate trophic and elastic functions of the heart. The N2B-KO mouse is the first titin-based model of diastolic dysfunction and, considering the high prevalence of diastolic heart failure, it could provide future mechanistic insights into the disease process.
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Affiliation(s)
- Michael H. Radke
- *Department of Neuromuscular and Cardiovascular Cell Biology, Max-Delbrück-Center for Molecular Medicine, D-13122 Berlin-Buch, Germany; and
| | - Jun Peng
- Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, and
| | - Yiming Wu
- Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, and
| | - Mark McNabb
- Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, and
| | - O. Lynne Nelson
- Department of Veterinary Clinical Sciences, Washington State University, Pullman, WA 99164
| | - Henk Granzier
- Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, and
| | - Michael Gotthardt
- *Department of Neuromuscular and Cardiovascular Cell Biology, Max-Delbrück-Center for Molecular Medicine, D-13122 Berlin-Buch, Germany; and
- Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, and
- To whom correspondence should be addressed at:
Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, Washington State University, Wegner Hall, Room 205, Pullman, WA 99164-6520 or Max-Delbrück-Center for Molecular Medicine Berlin-Buch, Robert Rössle Strasse 10, 13122 Berlin, Germany. E-mail: or
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10
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Lenard NR, Prpic V, Adamson AW, Rogers RC, Gettys TW. Differential coupling of beta3A- and beta3B-adrenergic receptors to endogenous and chimeric Galphas and Galphai. Am J Physiol Endocrinol Metab 2006; 291:E704-15. [PMID: 16705062 DOI: 10.1152/ajpendo.00048.2006] [Citation(s) in RCA: 3] [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: 11/22/2022]
Abstract
Chimeric G proteins made by replacing the COOH-terminal heptapeptide of G(alpha)q with the COOH-terminal heptapeptide of G(alpha)s or G(alpha)i were used to assess the relative coupling of beta(3)-adrenergic receptor (beta(3)-AR) splice variants (beta(3A) and beta(3B)) to G(alpha)s and G(alpha)i. The G(alpha)q/s and G(alpha)q/i chimeras transformed the response to receptor activation from regulation of adenylyl cyclase to mobilization of intracellular calcium (Ca(2+)(i)). Complementary high-throughput and single-cell approaches were used to evaluate agonist-induced coupling of the receptor to the G protein chimeras. In cells stably transformed with rat beta(3)-AR, transfected with the G protein chimeras, and evaluated using a scanning fluorometer, beta(3)-AR-induced coupling to G(alpha)q/s produced a rapid eightfold increase in Ca(2+)(i) followed by a slow decay to levels 25% above baseline. G(alpha)q/i also linked rat beta(3)-AR to mobilization of Ca(2+)(i) in a similar time- and agonist-dependent manner, but the net 2.5-fold increase in Ca(2+)(i) was only 30% of the response obtained with G(alpha)q/s. Activation of the rat beta(3)-AR also increased GTP binding to endogenous G(alpha)i threefold in membranes from CHO cells stably transformed with the receptor. A complementary single-cell imaging approach was used to assess the relative coupling of mouse beta(3A)- and beta(3B)-AR to G(alpha)i under conditions established to produce equivalent agonist-dependent coupling of the receptor splice variants to G(alpha)q/s and to increases in intracellular cAMP through endogenous G(alpha)s. The beta(3A)- and beta(3B)-AR coupled equivalently to G(alpha)q/i, but the temporal patterns of Ca(2+)(i) mobilization indicated that coupling was significantly less efficient than coupling to G(alpha)q/s. Collectively, these findings indicate less efficient but equivalent coupling of beta(3A)- and beta(3B)-AR to G(alpha)i vs. G(alpha)s and suggest that differential expression of the splice variants would not produce local differences in signaling networks linked to beta(3)-AR activation.
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Affiliation(s)
- Natalie R Lenard
- Laboratories of Adipocyte Signaling, Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
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11
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Wang ZY, Yang D, Chen Q, Leifer CA, Segal DM, Su SB, Caspi RR, Howard ZOM, Oppenheim JJ. Induction of dendritic cell maturation by pertussis toxin and its B subunit differentially initiate Toll-like receptor 4–dependent signal transduction pathways. Exp Hematol 2006; 34:1115-24. [PMID: 16863919 DOI: 10.1016/j.exphem.2006.04.025] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2006] [Indexed: 11/20/2022]
Abstract
OBJECTIVE Pertussis toxin (PT) has the capacity to activate dendritic cells (DCs) for the augmentation of cell-mediated immune responses. To investigate the mechanism(s) by which PT activates DCs, we investigated the effects of PT and its B-oligomer (PTB) on the maturation of human and mouse DCs and determined whether PT could act as a pathogen-associated molecular pattern to activate one of the Toll-like receptors (TLRs). METHODS The effects of PT and PTB on the maturation of human and mouse DCs were analyzed in terms of surface marker expression, cytokine production, antigen-presenting capacity, and intracellular signaling. The participation of TLR4 in PT-induced signaling was determined by comparing the effect of PT on DCs derived from TLR4-deficient and wild-type mice, as well as by measuring PT-induced NF-kappaB activation in HEK293 cells transiently transfected to express various TLRs. RESULTS Although both promoted phenotypic and functional maturation DCs, however, unlike PT that induced DC production of interleukin (IL)-6, tumor necrosis factor-alpha, IL-12, and interferon-inducible protein, PTB was capable of stimulating the production of interferon-inducible protein. Bone marrow-derived DCs from C3H/HeJ mice with defective TLR-4 alleles were unresponsive to PT and PTB, whereas DCs from C3H/HeN mice responded. In addition, PT induced NF-kappaB activation and IL-8 production in HEK293 cells transfected with a combination of TLR4 and MD2 but not in nontransfected or TLR2-transfected HEK293 cells. Comparison of the patterns of cytokine induction and intracellular signaling events in DCs treated by PT and PTB revealed that although PT, like lipopolysaccharide, triggered both MyD88-dependent and -independent pathways, PTB preferentially triggered MyD88-independent pathways. Interestingly, mouse splenocyte proliferation in response to PT and PTB was only partially dependent on TLR4. CONCLUSION The data identify PT as another pathogen-associated molecular pattern that induces DC maturation in a TLR4-dependent manner. Unlike PT, which triggers both MyD88-dependent and -independent pathways, PTB only triggers the MyD88-independent pathway in DCs.
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Affiliation(s)
- Zhao Yuan Wang
- Intramural Basic Research Program, SAIC-Frederick, Inc, USA
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12
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Rizzi C, Crippa MP, Jeeninga RE, Berkhout B, Blasi F, Poli G, Alfano M. Pertussis toxin B-oligomer suppresses IL-6 induced HIV-1 and chemokine expression in chronically infected U1 cells via inhibition of activator protein 1. THE JOURNAL OF IMMUNOLOGY 2006; 176:999-1006. [PMID: 16393986 DOI: 10.4049/jimmunol.176.2.999] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pertussis toxin B-oligomer (PTX-B) inhibits HIV replication in T lymphocytes and monocyte-derived macrophages by interfering with multiple steps of the HIV life cycle. PTX-B prevents CCR5-dependent (R5) virus entry in a noncompetitive manner, and it also exerts suppressive effects on both R5- and CXCR4-dependent HIV expression at a less-characterized postentry level. We demonstrate in this study that PTX-B profoundly inhibits HIV expression in chronically infected promonocytic U1 cells stimulated with several cytokines and, particularly, the IL-6-mediated effect, a cytokine that triggers viral production in these cells independently of NF-kappaB activation. From U1 cells we have subcloned a cell line, named U1-CR1, with increased responsiveness to IL-6. In these cells, PTX-B neither down-regulated the IL-6R nor prevented IL-6 induced signaling in terms of STAT3 phosphorylation and DNA binding. In contrast, PTX-B inhibited AP-1 binding to target DNA and modified its composition with a proportional increases in FosB, Fra2, and ATF2. PTX-B inhibited IL-6-induced HIV-1 long-terminal repeat-driven transcription from A, C, E, and F viral subtypes, which contain functional AP-1 binding sites, but failed to inhibit transcription from subtypes B and D LTR devoid of these sites. In addition, PTX-B inhibited the secretion of IL-6-induced, AP-1-dependent genes, including urokinase-type plasminogen activator, CXCL8/IL-8, and CCL2/monocyte chemotactic protein-1. Thus, PTX-B suppression of IL-6 induced expression of HIV and cellular genes in chronically infected promonocytic cells is strongly correlated to inhibition of AP-1.
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Affiliation(s)
- Chiara Rizzi
- AIDS Immunopathogenesis Unit, San Raffaele Scientific Institute, Milan, Italy
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Kolosova IA, Mirzapoiazova T, Adyshev D, Usatyuk P, Romer LH, Jacobson JR, Natarajan V, Pearse DB, Garcia JGN, Verin AD. Signaling pathways involved in adenosine triphosphate-induced endothelial cell barrier enhancement. Circ Res 2005; 97:115-24. [PMID: 15994434 DOI: 10.1161/01.res.0000175561.55761.69] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Endothelial barrier dysfunction caused by inflammatory agonists is a frequent underlying cause of vascular leak and edema. Novel strategies to preserve barrier integrity could have profound clinical impact. Adenosine triphosphate (ATP) released from endothelial cells by shear stress and injury has been shown to protect the endothelial barrier in some settings. We have demonstrated that ATP and its nonhydrolyzed analogues enhanced barrier properties of cultured endothelial cell monolayers and caused remodeling of cell-cell junctions. Increases in cytosolic Ca2+ and Erk activation caused by ATP were irrelevant to barrier enhancement. Experiments using biochemical inhibitors or siRNA indicated that G proteins (specifically Galphaq and Galphai2), protein kinase A (PKA), and the PKA substrate vasodilator-stimulated phosphoprotein were involved in ATP-induced barrier enhancement. ATP treatment decreased phosphorylation of myosin light chain and specifically activated myosin-associated phosphatase. Depletion of Galphaq with siRNA prevented ATP-induced activation of myosin phosphatase. We conclude that the mechanisms of ATP-induced barrier enhancement are independent of intracellular Ca2+, but involve activation of myosin phosphatase via a novel G-protein-coupled mechanism and PKA.
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Affiliation(s)
- Irina A Kolosova
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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14
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Zharikov SI, Krotova KY, Belayev L, Block ER. Pertussis toxin activates L-arginine uptake in pulmonary endothelial cells through downregulation of PKC-alpha activity. Am J Physiol Lung Cell Mol Physiol 2003; 286:L974-83. [PMID: 14695118 DOI: 10.1152/ajplung.00236.2003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pertussis toxin (PTX) induces activation of l-arginine transport in pulmonary artery endothelial cells (PAEC). The effects of PTX on l-arginine transport appeared after 6 h of treatment and reached maximal values after treatment for 12 h. PTX-induced changes in l-arginine transport were not accompanied by changes in expression of cationic amino acid transporter (CAT)-1 protein, the main l-arginine transporter in PAEC. Unlike holotoxin, the beta-oligomer-binding subunit of PTX did not affect l-arginine transport in PAEC, suggesting that Galpha(i) ribosylation is an important step in the activation of l-arginine transport by PTX. An activator of adenylate cyclase, forskolin, and an activator of protein kinase A (PKA), Sp-cAMPS, did not affect l-arginine transport in PAEC. In addition, inhibitors of PKA or adenylate cyclase did not change the activating effect of PTX on l-arginine uptake. Long-term treatment with PTX (18 h) induced a 40% decrease in protein kinase C (PKC)-alpha but did not affect the activities of PKC-epsilon and PKC-zeta in PAEC. An activator of PKC-alpha, phorbol 12-myristate 13-acetate, abrogated the activation of l-arginine transport in PAEC treated with PTX. Incubation of PTX-treated PAEC with phorbol 12-myristate 13-acetate in combination with an inhibitor of PKC-alpha (Go 6976) restored the activating effects of PTX on l-arginine uptake, suggesting PTX-induced activation of l-arginine transport is mediated through downregulation of PKC-alpha. Measurements of nitric oxide (NO) production by PAEC revealed that long-term treatment with PTX induced twofold increases in the amount of NO in PAEC. PTX also increased l-[(3)H]citrulline production from extracellular l-[(3)H]arginine without affecting endothelial NO synthase activity. These results demonstrate that PTX increased NO production through activation of l-arginine transport in PAEC.
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Affiliation(s)
- Sergey I Zharikov
- Div. of Pulmonary Medicine, UF College of Medicine, P. O. Box 100225, Gainesville, FL 32610-0225, USA.
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15
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Bogatcheva NV, Dudek SM, Garcia JGN, Verin AD. Mitogen-Activated Protein Kinases in Endothelial Pathophysiology. J Investig Med 2003. [DOI: 10.1177/108155890305100630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Endothelial cells continuously respond to extracellular stimuli such as chemical signals produced by circulating blood elements or mechanical forces such as shear stress. Proinflammatory cytokines, mitogens, reactive oxygen species, and shear stress trigger signal molecules to initiate multiple intracellular pathways, which often converge at mitogen-activated protein (MAP) kinase activation. The MAP kinase superfamily represents a burgeoning area of clinical investigation for treatment of various inflammatory and oncologic diseases and plays an essential role in mediating response to infection, ischemia/reperfusion injury, and vessel healing and remodeling through regulation of such diverse phenomena as endothelial cell proliferation, migration, apoptosis, and endothelial barrier function. The downstream effects of MAP kinase activation include modulation of gene expression via up-regulation of various transcription factors. In addition to these sustained effects, MAP kinases coordinate more immediate responses that affect dynamic cytoskeletal rearrangements necessary for cell migration and regulation of barrier function. This review discusses the important regulatory roles of MAP kinases in the vital physiologic functions of endothelium, focusing mainly on the role of MAP kinases in the maintenance of endothelial barrier.
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Affiliation(s)
| | - Steven M. Dudek
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Joe G. N. Garcia
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Alexander D. Verin
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
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16
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The A1166C polymorphism of the AT1 receptor gene is associated with collagen type I synthesis and myocardial stiffness in hypertensives. J Hypertens 2003. [DOI: 10.1097/00004872-200311000-00018] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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17
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Carlin SM, Roth M, Black JL. Urokinase potentiates PDGF-induced chemotaxis of human airway smooth muscle cells. Am J Physiol Lung Cell Mol Physiol 2003; 284:L1020-6. [PMID: 12576295 DOI: 10.1152/ajplung.00092.2002] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated the chemotactic action of PDGF and urokinase on human airway smooth muscle (HASM) cells in culture. Cells were put in collagen-coated transwells with 8-micro m perforations, incubated for 4 h with test compounds, then fixed, stained, and counted as migrated nuclei by microscopy. Cells from all culture conditions showed some basal migration (migration in the absence of stimuli during the assay), but cells preincubated for 24 h in 10% FBS or 20 ng/ml PDGF showed higher basal migration than cells quiesced in 1% FBS. PDGF(BB), PDGF(AA), and PDGF(AB) were all chemotactic when added during the assay. PDGF chemotaxis was blocked by the phosphatidyl 3'-kinase inhibitor LY-294002, the MEK inhibitor U-0126, PGE(2), formoterol, pertussis toxin, and the Rho kinase inhibitor Y-27632. Urokinase alone had no stimulatory effect on migration of quiescent cells but caused a dose-dependent potentiation of chemotaxis toward PDGF. Urokinase also potentiated the elevated basal migration of cells pretreated in 10% FBS or PDGF. This potentiating effect of urokinase appears to be novel. We conclude that PDGF and similar cytokines may be important factors in airway remodeling by redistribution of smooth muscle cells during inflammation and that urokinase may be important in potentiating the response.
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Affiliation(s)
- Stephen M Carlin
- Department of Pharmacology, University of Sydney, New South Wales 2006, Australia.
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18
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Hou W, Wu Y, Sun S, Shi M, Sun Y, Yang C, Pei G, Gu Y, Zhong C, Sun B. Pertussis toxin enhances Th1 responses by stimulation of dendritic cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:1728-36. [PMID: 12574336 DOI: 10.4049/jimmunol.170.4.1728] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Pertussis toxin (PTX) has been widely used as an adjuvant to induce Th1-mediated organ-specific autoimmune diseases in animal models. However, the cellular and molecular mechanisms remain to be defined. In this study, we showed that dendritic cells (DC) stimulated with PTX (PTX-DC) were able to substitute for PTX to promote experimental autoimmune uveitis (EAU). EAU induced by PTX-DC revealed a typical Th1 response, characterized by high uveitogenic retinal Ag interphotoreceptor retinoid-binding protein (IRBP)-specific IFN-gamma and IL-12 production in the draining lymph nodes, as well as increased levels of anti-IRBP IgG2a and decreased levels of anti-IRBP IgG1 in the serum of IRBP-immunized mice. Furthermore, PTX-DC preferentially induced T cells to produce the Th1 cytokine, IFN-gamma. After being stimulated with PTX, DC exhibited up-regulation of MHC class II, CD80, CD86, CD40, and DEC205. PTX-DC had also increased allostimulatory capacity and IL-12 and TNF-alpha production. Serum IL-12 was increased in naive mice that received PTX-DC i.p. In addition, PTX activated extracellular signal-regulated kinase in DC. Following the inhibition of extracellular signal-regulated kinase signaling, the maturation of PTX-DC was reduced. Subsequently, the ability of PTX-DC to promote IFN-gamma production by T cells in vitro and to induce EAU in vivo was blocked. The results suggest that PTX might exert an adjuvant effect on DC to promote their maturation and the production of proinflammatory cytokines, thereby eliciting a Th1 response.
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MESH Headings
- Adjuvants, Immunologic/administration & dosage
- Adjuvants, Immunologic/pharmacology
- Adjuvants, Immunologic/physiology
- Animals
- Cell Differentiation/immunology
- Cell Movement/immunology
- Cells, Cultured
- Coculture Techniques
- Dendritic Cells/cytology
- Dendritic Cells/enzymology
- Dendritic Cells/immunology
- Dendritic Cells/transplantation
- Eye Proteins/administration & dosage
- Eye Proteins/immunology
- Female
- Injections, Intraperitoneal
- Injections, Subcutaneous
- Interferon-gamma/biosynthesis
- Interleukin-12/blood
- Interleukin-12/metabolism
- Lymph Nodes/immunology
- Lymph Nodes/pathology
- Lymphocyte Culture Test, Mixed
- MAP Kinase Signaling System/immunology
- Mice
- Mice, Inbred A
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Pertussis Toxin/administration & dosage
- Pertussis Toxin/pharmacology
- Pertussis Toxin/physiology
- Retinol-Binding Proteins/administration & dosage
- Retinol-Binding Proteins/immunology
- Th1 Cells/enzymology
- Th1 Cells/immunology
- Th1 Cells/metabolism
- Uveitis/enzymology
- Uveitis/etiology
- Uveitis/immunology
- Uveitis/pathology
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Affiliation(s)
- Wanqiu Hou
- Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
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19
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Bird IM, Zhang L, Magness RR. Possible mechanisms underlying pregnancy-induced changes in uterine artery endothelial function. Am J Physiol Regul Integr Comp Physiol 2003; 284:R245-58. [PMID: 12529278 DOI: 10.1152/ajpregu.00108.2002] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The last 10 years has seen a dramatic increase in our understanding of the mechanisms underlying the pregnancy-specific adaptation in cardiovascular function in general and the dramatic changes that occur in uterine artery endothelium in particular to support the growing fetus. The importance of these changes is clear from a number of studies linking restriction of uterine blood flow (UBF) and/or endothelial dysfunction and clinical conditions such as intrauterine growth retardation (IUGR) and/or preeclampsia in both humans and animal models; these topics are covered only briefly here. The recent developments that prompts this review are twofold. The first is advances in an understanding of the cell signaling processes that regulate endothelial nitric oxide synthase (eNOS) in particular (Govers R and Rabelink TJ. Am J Physiol Renal Physiol 280: F193-F206, 2001). The second is the emerging picture that uterine artery (UA) endothelial cell production of nitric oxide (NO) as well as prostacyclin (PGI2) may be as much a consequence of cellular reprogramming at the level of cell signaling as due to tonic stimuli inducing changes in the level of expression of eNOS or the enzymes of the PGI2 biosynthetic pathway (cPLA2, COX-1, PGIS). In reviewing just how we came to this conclusion and outlining the implications of such a finding, we draw mostly on data from ovine or human studies, with reference to other species only where directly relevant.
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Affiliation(s)
- Ian M Bird
- University of Wisconsin-Madison, Department of Obstetrics and Gynecology, Perinatal Research Laboratories, Madison, Wisconsin 53715, USA.
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20
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Wolburg H, Lippoldt A. Tight junctions of the blood-brain barrier: development, composition and regulation. Vascul Pharmacol 2002; 38:323-37. [PMID: 12529927 DOI: 10.1016/s1537-1891(02)00200-8] [Citation(s) in RCA: 780] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
1. The blood-brain barrier is essential for the maintenance and regulation of the neural microenvironment. The main characteristic features of blood-brain barrier endothelial cells are an extremely low rate of transcytotic vesicles and a restrictive paracellular diffusion barrier. 2. Endothelial blood-brain barrier tight junctions differ from epithelial tight junctions, not only by distinct morphological and molecular properties, but also by the fact that endothelial tight junctions are more sensitive to microenvironmental than epithelial factors. 3. Many ubiquitous molecular tight junction components have been identified and characterized including claudins, occludin, ZO-1, ZO-2, ZO-3, cingulin and 7H6. Signaling pathways involved in tight junction regulation include G-proteins, serine-, threonine- and tyrosine-kinases, extra and intracellular calcium levels, cAMP levels, proteases and cytokines. Common to most of these pathways is the modulation of cytoskeletal elements and the connection of tight junction transmembrane molecules to the cytoskeleton. Additionally, crosstalk between components of the tight junction- and the cadherin-catenin system of the adherens junction suggests a close functional interdependence of the two cell-cell contact systems. 4. Important new molecular aspects of tight junction regulation were recently elucidated. This review provides an integration of these new results.
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Affiliation(s)
- Hartwig Wolburg
- Institute of Pathology, University of Tübingen, Liebermeisterstr. 8, D-72076 Tübingen, Germany.
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21
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Affiliation(s)
- I Cook
- Department of Physiology, University of Sydney, NSW 2006, Australia.
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Bátkai S, Járai Z, Wagner JA, Goparaju SK, Varga K, Liu J, Wang L, Mirshahi F, Khanolkar AD, Makriyannis A, Urbaschek R, Garcia N, Sanyal AJ, Kunos G. Endocannabinoids acting at vascular CB1 receptors mediate the vasodilated state in advanced liver cirrhosis. Nat Med 2001; 7:827-32. [PMID: 11433348 DOI: 10.1038/89953] [Citation(s) in RCA: 252] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Advanced cirrhosis is associated with generalized vasodilation of unknown origin, which contributes to mortality. Cirrhotic patients are endotoxemic, and activation of vascular cannabinoid CB1 receptors has been implicated in endotoxin-induced hypotension. Here we show that rats with biliary cirrhosis have low blood pressure, which is elevated by the CB1 receptor antagonist SR141716A. The low blood pressure of rats with CCl4-induced cirrhosis was similarly reversed by SR141716A, which also reduced the elevated mesenteric blood flow and portal pressure. Monocytes from cirrhotic but not control patients or rats elicited SR141716A-sensitive hypotension in normal recipient rats and showed significantly elevated levels of anandamide. Compared with non-cirrhotic controls, in cirrhotic human livers there was a three-fold increase in CB1 receptors on isolated vascular endothelial cells. These results implicate anandamide and vascular CB1 receptors in the vasodilated state in advanced cirrhosis and indicate a novel approach for its management.
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Affiliation(s)
- S Bátkai
- National Institute on Alcohol Abuse & Alcoholism, National Institutes of Health, Bethesda, Maryland, USA
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23
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Liu F, Verin AD, Borbiev T, Garcia JG. Role of cAMP-dependent protein kinase A activity in endothelial cell cytoskeleton rearrangement. Am J Physiol Lung Cell Mol Physiol 2001; 280:L1309-17. [PMID: 11350812 DOI: 10.1152/ajplung.2001.280.6.l1309] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To examine signaling mechanisms relevant to cAMP/protein kinase A (PKA)-dependent endothelial cell barrier regulation, we investigated the impact of the cAMP/PKA inhibitors Rp diastereomer of adenosine 3',5'-cyclic monophosphorothioate (Rp-cAMPS) and PKA inhibitor (PKI) on bovine pulmonary artery and bovine lung microvascular endothelial cell cytoskeleton reorganization. Rp-cAMPS as well as PKI significantly increased the formation of actin stress fibers and intercellular gaps but did not alter myosin light chain (MLC) phosphorylation, suggesting that the Rp-cAMPS-induced contractile phenotype evolves in an MLC-independent fashion. We next examined the role of extracellular signal-regulated kinases (ERKs) in Rp-cAMPS- and PKI-induced actin rearrangement. The activities of both ERK1/2 and its upstream activator Raf-1 were transiently enhanced by Rp-cAMPS and linked to the phosphorylation of the well-known ERK cytoskeletal target caldesmon. Inhibition of the Raf-1 target ERK kinase (MEK) either attenuated or abolished Rp-cAMPS- and PKI-induced ERK activation, caldesmon phosphorylation, and stress fiber formation. In summary, our data elucidate the involvement of the p42/44 ERK pathway in cytoskeletal rearrangement evoked by reductions in PKA activity and suggest the involvement of significant cross talk between cAMP- and ERK-dependent signaling pathways in endothelial cell cytoskeletal organization and barrier regulation.
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Affiliation(s)
- F Liu
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224-6801, USA
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Liu F, Verin AD, Wang P, Day R, Wersto RP, Chrest FJ, English DK, Garcia JG. Differential regulation of sphingosine-1-phosphate- and VEGF-induced endothelial cell chemotaxis. Involvement of G(ialpha2)-linked Rho kinase activity. Am J Respir Cell Mol Biol 2001; 24:711-9. [PMID: 11415936 DOI: 10.1165/ajrcmb.24.6.4323] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
We compared stimulus-coupling pathways involved in bovine pulmonary artery (PA) and lung microvascular endothelial cell migration evoked by sphingosine-1-phosphate (S1P), a potent bioactive lipid released from activated platelets, and by vascular endothelial growth factor (VEGF), a well-recognized angiogenic factor. S1P-induced endothelial cell migration was maximum at 1 microM (approximately 8-fold increase with PA endothelium) and surpassed the maximal response evoked by either VEGF (10 ng/ml) (approximately 2.5-fold increase) or hepatocyte growth factor (HGF) (approximately 2.5-fold increase). Migration induced by S1P, but not by VEGF, was significantly inhibited by treatment with antisense oligonucleotides directed to Edg-1 and Edg-3 (endothelial differentiation gene) S1P receptors and by G protein modification. These strategies included pretreatment with pertussis toxin, or transfection with mini-genes encoding a betagamma subunit inhibitory peptide of the beta-adrenergic receptor kinase, or an 11-amino-acid peptide that inhibits G(1alpha2) signaling. Various strategies to interrupt Rho family signaling, including C(3) exotoxin, dominant/negative Rho, or the addition of Y27632, a cell-permeable Rho kinase inhibitor, significantly attenuated S1P- but not VEGF-induced migration. Conversely, pharmacologic inhibition of either myosin light chain kinase, src family tyrosine kinases, or phosphatidylinositol-3' kinase reduced basal endothelial cell migration and abolished VEGF-induced endothelial cell migration but did not inhibit the increase in S1P-induced migration. Whereas VEGF and S1P increased both p42/p44 extracellular regulated kinase and p38 mitogen-activated protein (MAP) kinase activities, only p38 MAP kinase inhibition significantly reduced VEGF- and S1P-stimulated migration. These data confirm S1P as a potent endothelial cell chemoattractant through G(1alpha2)-coupled Edg receptors linked to Rho-associated kinase and p38 MAP kinase activation. The divergence in signaling pathways evoked by S1P and VEGF suggests complex and agonist-specific regulation of endothelial cell angiogenic responses.
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Affiliation(s)
- F Liu
- Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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