Pub Date : 2002-05-17DOI: 10.1161/01.RES.0000017629.70769.CC
E. Suzuki, H. Nishimatsu, H. Satonaka, K. Walsh, A. Goto, M. Omata, T. Fujita, R. Nagai, Y. Hirata
It is well known that angiotensin II (Ang II) is implicated in the phenotypic modulation and hypertrophy of vascular smooth muscle cells (VSMCs). To study the mechanisms by which Ang II contributes to the pathological changes of VSMCs, we examined whether Ang II stimulated myocyte enhancer factor 2 (MEF2)- and calcineurin/nuclear factor of activated T cell (NFAT)-dependent transcriptional activation of genes in VSMCs. Ang II increased the DNA binding activity of MEF2A and its expression at the protein level. Ang II induced c-jun promoter activity, and this increase was inhibited by dominant-negative mutants of MEF2A and mitogen-activated protein kinase kinase 6 but not by calcineurin inhibitors. Ang II stimulated NFAT DNA binding activity and NFAT-dependent gene transcription, and these effects of Ang II were inhibited by calcineurin inhibitors. Furthermore, Ang II induced the promoter activity of the nonmuscle-type myosin heavy chain B gene, which we used as a marker of the dedifferentiated state of VSMCs, and this increase was inhibited by calcineurin inhibitors but not by the dominant-negative mutants of MEF2A or mitogen-activated protein kinase kinase 6. Finally, Ang II increased protein synthesis, and this increase was inhibited by infection with an adenovirus construct that expresses the dominant-negative mutant of MEF2A but not by calcineurin inhibitors. These results suggest that Ang II stimulates the MEF2- and calcineurin/NFAT-dependent pathways and that these pathways have distinct roles in VSMCs.
{"title":"Angiotensin II Induces Myocyte Enhancer Factor 2- and Calcineurin/Nuclear Factor of Activated T Cell-Dependent Transcriptional Activation in Vascular Myocytes","authors":"E. Suzuki, H. Nishimatsu, H. Satonaka, K. Walsh, A. Goto, M. Omata, T. Fujita, R. Nagai, Y. Hirata","doi":"10.1161/01.RES.0000017629.70769.CC","DOIUrl":"https://doi.org/10.1161/01.RES.0000017629.70769.CC","url":null,"abstract":"It is well known that angiotensin II (Ang II) is implicated in the phenotypic modulation and hypertrophy of vascular smooth muscle cells (VSMCs). To study the mechanisms by which Ang II contributes to the pathological changes of VSMCs, we examined whether Ang II stimulated myocyte enhancer factor 2 (MEF2)- and calcineurin/nuclear factor of activated T cell (NFAT)-dependent transcriptional activation of genes in VSMCs. Ang II increased the DNA binding activity of MEF2A and its expression at the protein level. Ang II induced c-jun promoter activity, and this increase was inhibited by dominant-negative mutants of MEF2A and mitogen-activated protein kinase kinase 6 but not by calcineurin inhibitors. Ang II stimulated NFAT DNA binding activity and NFAT-dependent gene transcription, and these effects of Ang II were inhibited by calcineurin inhibitors. Furthermore, Ang II induced the promoter activity of the nonmuscle-type myosin heavy chain B gene, which we used as a marker of the dedifferentiated state of VSMCs, and this increase was inhibited by calcineurin inhibitors but not by the dominant-negative mutants of MEF2A or mitogen-activated protein kinase kinase 6. Finally, Ang II increased protein synthesis, and this increase was inhibited by infection with an adenovirus construct that expresses the dominant-negative mutant of MEF2A but not by calcineurin inhibitors. These results suggest that Ang II stimulates the MEF2- and calcineurin/NFAT-dependent pathways and that these pathways have distinct roles in VSMCs.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"25 1","pages":"1004-1011"},"PeriodicalIF":0.0,"publicationDate":"2002-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90779203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-17DOI: 10.1161/01.RES.0000018422.31717.EE
G. Chiesa, E. Monteggia, M. Marchesi, P. Lorenzon, M. Laucello, V. Lorusso, C. Di Mario, E. Karvouni, R. Newton, C. Bisgaier, G. Franceschini, C. Sirtori
Apolipoprotein A-IMilano (AIM), a natural variant of human apolipoprotein A-I, confers to carriers a significant protection against vascular disease. In previous studies, administration of recombinant AIM-phospholipid (AIM-PL) complexes to hypercholesterolemic rabbits markedly inhibited neointimal formation after arterial injury; moreover, repeated injections of AIM-PL in apoE-deficient mice significantly reduced atherosclerosis progression. The objective of the present study was to determine if a single localized infusion of AIM-PL complexes administered directly to atheromatous lesions could promote plaque regression. Lipid-rich, atheromatous plaques were generated at both common carotid arteries of 25 rabbits by applying a perivascular electric injury, followed by 1.5% cholesterol diet for 90 days. Rabbits were infused with either saline, phospholipid vesicles, or 3 different AIM-PL doses (250, 500, or 1000 mg of protein) delivered through an intravascular ultrasound (IVUS) catheter positioned at the origin of the right carotid. The lesions at the left carotid artery were therefore exposed to the agents systemically. Infusion of AIM-PL at the 2 highest doses caused reduction of right carotid artery plaque area by the end a 90-minute infusion as assessed by IVUS analysis. Plaque area regression was confirmed by histology in carotid arteries receiving direct (500 and 1000 mg doses) and systemic (500 mg dose) delivery, 72 hours after the start of the treatment. Plaque lipid content was associated with significant and similar decreases in Oil Red O staining in both arteries. These results suggest AIM-PL complexes enhanced lipid removal from arteries is the mechanism responsible for the observed plaque changes.
{"title":"Recombinant Apolipoprotein A-IMilano Infusion Into Rabbit Carotid Artery Rapidly Removes Lipid From Fatty Streaks","authors":"G. Chiesa, E. Monteggia, M. Marchesi, P. Lorenzon, M. Laucello, V. Lorusso, C. Di Mario, E. Karvouni, R. Newton, C. Bisgaier, G. Franceschini, C. Sirtori","doi":"10.1161/01.RES.0000018422.31717.EE","DOIUrl":"https://doi.org/10.1161/01.RES.0000018422.31717.EE","url":null,"abstract":"Apolipoprotein A-IMilano (AIM), a natural variant of human apolipoprotein A-I, confers to carriers a significant protection against vascular disease. In previous studies, administration of recombinant AIM-phospholipid (AIM-PL) complexes to hypercholesterolemic rabbits markedly inhibited neointimal formation after arterial injury; moreover, repeated injections of AIM-PL in apoE-deficient mice significantly reduced atherosclerosis progression. The objective of the present study was to determine if a single localized infusion of AIM-PL complexes administered directly to atheromatous lesions could promote plaque regression. Lipid-rich, atheromatous plaques were generated at both common carotid arteries of 25 rabbits by applying a perivascular electric injury, followed by 1.5% cholesterol diet for 90 days. Rabbits were infused with either saline, phospholipid vesicles, or 3 different AIM-PL doses (250, 500, or 1000 mg of protein) delivered through an intravascular ultrasound (IVUS) catheter positioned at the origin of the right carotid. The lesions at the left carotid artery were therefore exposed to the agents systemically. Infusion of AIM-PL at the 2 highest doses caused reduction of right carotid artery plaque area by the end a 90-minute infusion as assessed by IVUS analysis. Plaque area regression was confirmed by histology in carotid arteries receiving direct (500 and 1000 mg doses) and systemic (500 mg dose) delivery, 72 hours after the start of the treatment. Plaque lipid content was associated with significant and similar decreases in Oil Red O staining in both arteries. These results suggest AIM-PL complexes enhanced lipid removal from arteries is the mechanism responsible for the observed plaque changes.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"38 1","pages":"974-980"},"PeriodicalIF":0.0,"publicationDate":"2002-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78422391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-17DOI: 10.1161/01.RES.0000017632.83720.68
H. Funakoshi, T. Kubota, Natsumi Kawamura, Yoji Machida, A. Feldman, H. Tsutsui, H. Shimokawa, A. Takeshita
Abstract— Transgenic (TG) mice with cardiac-specific overexpression of tumor necrosis factor-&agr; develop congestive heart failure. We have previously reported that short-term inhibition of inducible nitric oxide synthase (iNOS) ameliorates &bgr;-adrenergic hyporesponsiveness in TG mice. To examine whether long-term inhibition of iNOS may rescue TG mice from developing congestive heart failure, we disrupted iNOS gene by crossing TG mice with iNOS knockout mice. Myocardial levels of iNOS protein were significantly increased in TG mice compared with age- and sex-matched wild-type (WT) mice. No iNOS protein was detected in TG mice with the disruption of iNOS. Myocardial levels of endothelial NOS were not different among these mice. To examine the effects of iNOS disruption on myocardial contractility, left ventricular pressure was measured. In TG mice, +dP/dtmax was significantly suppressed, and its &bgr;-adrenergic responsiveness was blunted. As in the case with short-term inhibition of iNOS, the disruption of iNOS gene improved &bgr;-adrenergic inotropic responsiveness in TG mice but not in WT mice. However, the iNOS disruption did not alter myocardial inflammation, ventricular hypertrophy, or the survival of these mice. These results indicate that although myocardial expression of iNOS plays a key role in the attenuation of &bgr;-adrenergic inotropic responsiveness, NO-independent mechanisms might be more important in the development of congestive heart failure.
{"title":"Disruption of Inducible Nitric Oxide Synthase Improves &bgr;-Adrenergic Inotropic Responsiveness but Not the Survival of Mice With Cytokine-Induced Cardiomyopathy","authors":"H. Funakoshi, T. Kubota, Natsumi Kawamura, Yoji Machida, A. Feldman, H. Tsutsui, H. Shimokawa, A. Takeshita","doi":"10.1161/01.RES.0000017632.83720.68","DOIUrl":"https://doi.org/10.1161/01.RES.0000017632.83720.68","url":null,"abstract":"Abstract— Transgenic (TG) mice with cardiac-specific overexpression of tumor necrosis factor-&agr; develop congestive heart failure. We have previously reported that short-term inhibition of inducible nitric oxide synthase (iNOS) ameliorates &bgr;-adrenergic hyporesponsiveness in TG mice. To examine whether long-term inhibition of iNOS may rescue TG mice from developing congestive heart failure, we disrupted iNOS gene by crossing TG mice with iNOS knockout mice. Myocardial levels of iNOS protein were significantly increased in TG mice compared with age- and sex-matched wild-type (WT) mice. No iNOS protein was detected in TG mice with the disruption of iNOS. Myocardial levels of endothelial NOS were not different among these mice. To examine the effects of iNOS disruption on myocardial contractility, left ventricular pressure was measured. In TG mice, +dP/dtmax was significantly suppressed, and its &bgr;-adrenergic responsiveness was blunted. As in the case with short-term inhibition of iNOS, the disruption of iNOS gene improved &bgr;-adrenergic inotropic responsiveness in TG mice but not in WT mice. However, the iNOS disruption did not alter myocardial inflammation, ventricular hypertrophy, or the survival of these mice. These results indicate that although myocardial expression of iNOS plays a key role in the attenuation of &bgr;-adrenergic inotropic responsiveness, NO-independent mechanisms might be more important in the development of congestive heart failure.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"23 1","pages":"959-965"},"PeriodicalIF":0.0,"publicationDate":"2002-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76296034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-17DOI: 10.1161/01.RES.0000018162.87285.F8
K. Gauthier, Christina Deeter, U. Murali Krishna, Y. Krishna Reddy, M. Bondlela, J. Falck, William B. Campbell
Endothelium-dependent hyperpolarization and relaxation of vascular smooth muscle are mediated by endothelium-derived hyperpolarizing factors (EDHFs). EDHF candidates include cytochrome P-450 metabolites of arachidonic acid, K+, hydrogen peroxide, or electrical coupling through gap junctions. In bovine coronary arteries, epoxyeicosatrienoic acids (EETs) appear to function as EDHFs. A 14,15-EET analogue, 14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EEZE) was synthesized and identified as an EET-specific antagonist. In bovine coronary arterial rings preconstricted with U46619, 14,15-EET, 11,12-EET, 8,9-EET, and 5,6-EET induced concentration-related relaxations. Preincubation of the arterial rings with 14,15-EEZE (10 &mgr;mol/L) inhibited the relaxations to 14,15-EET, 11,12-EET, 8,9-EET, and 5,6-EET but was most effective in inhibiting 14,15-EET–induced relaxations. 14,15-EEZE also inhibited indomethacin-resistant relaxations to methacholine and arachidonic acid and indomethacin-resistant and l-nitroarginine-resistant relaxations to bradykinin. It did not alter relaxation responses to sodium nitroprusside, iloprost, or the K+ channel activators (NS1619 and bimakalim). Additionally, in small bovine coronary arteries pretreated with indomethacin and l-nitroarginine and preconstricted with U46619, 14,15-EEZE (3 &mgr;mol/L) inhibited bradykinin (10 nmol/L)–induced smooth muscle hyperpolarizations and relaxations. In rat renal microsomes, 14,15-EEZE (10 &mgr;mol/L) did not decrease EET synthesis and did not alter 20-hydroxyeicosatetraenoic acid synthesis. This analogue acts as an EET antagonist by inhibiting the following: (1) EET-induced relaxations, (2) the EDHF component of methacholine-induced, bradykinin-induced, and arachidonic acid–induced relaxations, and (3) the smooth muscle hyperpolarization response to bradykinin. Thus, a distinct molecular structure is required for EET activity, and alteration of this structure modifies agonist and antagonist activity. These findings support a role of EETs as EDHFs.
{"title":"14,15-Epoxyeicosa-5(Z)-enoic Acid: A Selective Epoxyeicosatrienoic Acid Antagonist That Inhibits Endothelium-Dependent Hyperpolarization and Relaxation in Coronary Arteries","authors":"K. Gauthier, Christina Deeter, U. Murali Krishna, Y. Krishna Reddy, M. Bondlela, J. Falck, William B. Campbell","doi":"10.1161/01.RES.0000018162.87285.F8","DOIUrl":"https://doi.org/10.1161/01.RES.0000018162.87285.F8","url":null,"abstract":"Endothelium-dependent hyperpolarization and relaxation of vascular smooth muscle are mediated by endothelium-derived hyperpolarizing factors (EDHFs). EDHF candidates include cytochrome P-450 metabolites of arachidonic acid, K+, hydrogen peroxide, or electrical coupling through gap junctions. In bovine coronary arteries, epoxyeicosatrienoic acids (EETs) appear to function as EDHFs. A 14,15-EET analogue, 14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EEZE) was synthesized and identified as an EET-specific antagonist. In bovine coronary arterial rings preconstricted with U46619, 14,15-EET, 11,12-EET, 8,9-EET, and 5,6-EET induced concentration-related relaxations. Preincubation of the arterial rings with 14,15-EEZE (10 &mgr;mol/L) inhibited the relaxations to 14,15-EET, 11,12-EET, 8,9-EET, and 5,6-EET but was most effective in inhibiting 14,15-EET–induced relaxations. 14,15-EEZE also inhibited indomethacin-resistant relaxations to methacholine and arachidonic acid and indomethacin-resistant and l-nitroarginine-resistant relaxations to bradykinin. It did not alter relaxation responses to sodium nitroprusside, iloprost, or the K+ channel activators (NS1619 and bimakalim). Additionally, in small bovine coronary arteries pretreated with indomethacin and l-nitroarginine and preconstricted with U46619, 14,15-EEZE (3 &mgr;mol/L) inhibited bradykinin (10 nmol/L)–induced smooth muscle hyperpolarizations and relaxations. In rat renal microsomes, 14,15-EEZE (10 &mgr;mol/L) did not decrease EET synthesis and did not alter 20-hydroxyeicosatetraenoic acid synthesis. This analogue acts as an EET antagonist by inhibiting the following: (1) EET-induced relaxations, (2) the EDHF component of methacholine-induced, bradykinin-induced, and arachidonic acid–induced relaxations, and (3) the smooth muscle hyperpolarization response to bradykinin. Thus, a distinct molecular structure is required for EET activity, and alteration of this structure modifies agonist and antagonist activity. These findings support a role of EETs as EDHFs.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"33 1","pages":"1028-1036"},"PeriodicalIF":0.0,"publicationDate":"2002-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81023622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-03DOI: 10.1161/01.RES.0000016960.61087.86
K. Gima, Y. Rudy
Body surface electrocardiograms and electrograms recorded from the surfaces of the heart are the basis for diagnosis and treatment of cardiac electrophysiological disorders and arrhythmias. Given recent advances in understanding the molecular mechanisms of arrhythmia, it is important to relate these electrocardiographic waveforms to cellular electrophysiological processes. This modeling study establishes the following principles: (1) voltage gradients created by heterogeneities of the slow-delayed rectifier (IKs) and transient outward (Ito) potassium current inscribe the T wave and J wave, respectively; T-wave polarity and width are strongly influenced by the degree of intercellular coupling through gap-junctions. (2) Changes in [K+]o modulate the T wave through their effect on the rapid-delayed rectifier, IKr. (3) Alterations of IKs, IKr, and INa (fast sodium current) in long-QT syndrome (LQT1, LQT2, and LQT3, respectively) are reflected in characteristic QT-interval and T-wave changes; LQT1 prolongs QT without widening the T wave. (4) Accelerated inactivation of INa on the background of large epicardial Ito results in ST elevation (Brugada phenotype) that reflects the degree of severity. (5) Activation of the ATP-sensitive potassium current, IK(ATP), is sufficient to cause ST elevation during acute ischemia. These principles provide a mechanistic cellular basis for interpretation of electrocardiographic waveforms.
{"title":"Ionic Current Basis of Electrocardiographic Waveforms: A Model Study","authors":"K. Gima, Y. Rudy","doi":"10.1161/01.RES.0000016960.61087.86","DOIUrl":"https://doi.org/10.1161/01.RES.0000016960.61087.86","url":null,"abstract":"Body surface electrocardiograms and electrograms recorded from the surfaces of the heart are the basis for diagnosis and treatment of cardiac electrophysiological disorders and arrhythmias. Given recent advances in understanding the molecular mechanisms of arrhythmia, it is important to relate these electrocardiographic waveforms to cellular electrophysiological processes. This modeling study establishes the following principles: (1) voltage gradients created by heterogeneities of the slow-delayed rectifier (IKs) and transient outward (Ito) potassium current inscribe the T wave and J wave, respectively; T-wave polarity and width are strongly influenced by the degree of intercellular coupling through gap-junctions. (2) Changes in [K+]o modulate the T wave through their effect on the rapid-delayed rectifier, IKr. (3) Alterations of IKs, IKr, and INa (fast sodium current) in long-QT syndrome (LQT1, LQT2, and LQT3, respectively) are reflected in characteristic QT-interval and T-wave changes; LQT1 prolongs QT without widening the T wave. (4) Accelerated inactivation of INa on the background of large epicardial Ito results in ST elevation (Brugada phenotype) that reflects the degree of severity. (5) Activation of the ATP-sensitive potassium current, IK(ATP), is sufficient to cause ST elevation during acute ischemia. These principles provide a mechanistic cellular basis for interpretation of electrocardiographic waveforms.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"81 1","pages":"889-896"},"PeriodicalIF":0.0,"publicationDate":"2002-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81725413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-03DOI: 10.1161/01.RES.0000016165.23795.1F
A. Sabri, B. Wilson, S. Steinberg
Previous attempts to delineate the consequences of G&agr; q activation in cardiomyocytes relied largely on molecular strategies in cultures or transgenic mice. Modest levels of wild-type G&agr;q overexpression induce stable cardiac hypertrophy, whereas intense G&agr;q stimulation induces cardiomyocyte apoptosis. The precise mechanism(s) whereby traditional targets of G&agr; q subunits that induce hypertrophy also trigger cardiomyocyte apoptosis is not obvious and is explored with recombinant Pasteurella multocida toxin (rPMT, a G&agr;q agonist). Cells cultured with rPMT display cardiomyocyte enlargement, sarcomeric organization, and increased atrial natriuretic factor expression in association with activation of phospholipase C, novel protein kinase C (PKC) isoforms, extracellular signal-regulated protein kinase (ERK), and (to a lesser extent) JNK/p38-MAPK. rPMT stimulates the ERK cascade via epidermal growth factor (EGF) receptor transactivation in cardiac fibroblasts, but EGF receptor transactivation plays no role in ERK activation in cardiomyocytes. Surprisingly, rPMT (or novel PKC isoform activation by PMA) decreases basal Akt phosphorylation; rPMT prevents Akt phosphorylation by EGF or IGF-1 and functionally augments cardiomyocyte apoptosis in response to H2O2. These results identify a G&agr;q-PKC pathway that represses basal Akt phosphorylation and impairs Akt stimulation by survival factors. Because inhibition of Akt enhances cardiomyocyte susceptibility to apoptosis, this pathway is predicted to contribute to the transition from hypertrophy to cardiac decompensation and could be targeted for therapy in heart failure.
{"title":"Dual Actions of the G&agr;q Agonist Pasteurella multocida Toxin to Promote Cardiomyocyte Hypertrophy and Enhance Apoptosis Susceptibility","authors":"A. Sabri, B. Wilson, S. Steinberg","doi":"10.1161/01.RES.0000016165.23795.1F","DOIUrl":"https://doi.org/10.1161/01.RES.0000016165.23795.1F","url":null,"abstract":"Previous attempts to delineate the consequences of G&agr; q activation in cardiomyocytes relied largely on molecular strategies in cultures or transgenic mice. Modest levels of wild-type G&agr;q overexpression induce stable cardiac hypertrophy, whereas intense G&agr;q stimulation induces cardiomyocyte apoptosis. The precise mechanism(s) whereby traditional targets of G&agr; q subunits that induce hypertrophy also trigger cardiomyocyte apoptosis is not obvious and is explored with recombinant Pasteurella multocida toxin (rPMT, a G&agr;q agonist). Cells cultured with rPMT display cardiomyocyte enlargement, sarcomeric organization, and increased atrial natriuretic factor expression in association with activation of phospholipase C, novel protein kinase C (PKC) isoforms, extracellular signal-regulated protein kinase (ERK), and (to a lesser extent) JNK/p38-MAPK. rPMT stimulates the ERK cascade via epidermal growth factor (EGF) receptor transactivation in cardiac fibroblasts, but EGF receptor transactivation plays no role in ERK activation in cardiomyocytes. Surprisingly, rPMT (or novel PKC isoform activation by PMA) decreases basal Akt phosphorylation; rPMT prevents Akt phosphorylation by EGF or IGF-1 and functionally augments cardiomyocyte apoptosis in response to H2O2. These results identify a G&agr;q-PKC pathway that represses basal Akt phosphorylation and impairs Akt stimulation by survival factors. Because inhibition of Akt enhances cardiomyocyte susceptibility to apoptosis, this pathway is predicted to contribute to the transition from hypertrophy to cardiac decompensation and could be targeted for therapy in heart failure.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"78 4 1","pages":"850-857"},"PeriodicalIF":0.0,"publicationDate":"2002-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88083318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-03DOI: 10.1161/01.RES.0000016164.02525.B4
V. Bodart, M. Febbraio, Annie Demers, N. Mcnicoll, P. Pohanková, A. Perreault, T. Sejlitz, E. Escher, R. Silverstein, D. Lamontagne, H. Ong
Growth hormone-releasing peptides (GHRPs) are known as potent growth hormone secretagogues whose actions are mediated by the ghrelin receptor, a G protein-coupled receptor cloned from pituitary libraries. Hexarelin, a hexapeptide of the GHRP family, has reported cardiovascular activity. To identify the molecular target mediating this activity, rat cardiac membranes were labeled with a radioactive photoactivatable derivative of hexarelin and purified using lectin affinity chromatography and preparative gel electrophoresis. A binding protein of Mr 84 000 was identified. The N-terminal sequence determination of the deglycosylated protein was identical to rat CD36, a multifunctional glycoprotein, which was expressed in cardiomyocytes and microvascular endothelial cells. Activation of CD36 in perfused hearts by hexarelin was shown to elicit an increase in coronary perfusion pressure in a dose-dependent manner. This effect was lacking in hearts from CD36-null mice and hearts from spontaneous hypertensive rats genetically deficient in CD36. The coronary vasoconstrictive response correlated with expression of CD36 as assessed by immunoblotting and covalent binding with hexarelin. These data suggest that CD36 may mediate the coronary vasospasm seen in hypercholesterolemia and atherosclerosis.
{"title":"CD36 Mediates the Cardiovascular Action of Growth Hormone-Releasing Peptides in the Heart","authors":"V. Bodart, M. Febbraio, Annie Demers, N. Mcnicoll, P. Pohanková, A. Perreault, T. Sejlitz, E. Escher, R. Silverstein, D. Lamontagne, H. Ong","doi":"10.1161/01.RES.0000016164.02525.B4","DOIUrl":"https://doi.org/10.1161/01.RES.0000016164.02525.B4","url":null,"abstract":"Growth hormone-releasing peptides (GHRPs) are known as potent growth hormone secretagogues whose actions are mediated by the ghrelin receptor, a G protein-coupled receptor cloned from pituitary libraries. Hexarelin, a hexapeptide of the GHRP family, has reported cardiovascular activity. To identify the molecular target mediating this activity, rat cardiac membranes were labeled with a radioactive photoactivatable derivative of hexarelin and purified using lectin affinity chromatography and preparative gel electrophoresis. A binding protein of Mr 84 000 was identified. The N-terminal sequence determination of the deglycosylated protein was identical to rat CD36, a multifunctional glycoprotein, which was expressed in cardiomyocytes and microvascular endothelial cells. Activation of CD36 in perfused hearts by hexarelin was shown to elicit an increase in coronary perfusion pressure in a dose-dependent manner. This effect was lacking in hearts from CD36-null mice and hearts from spontaneous hypertensive rats genetically deficient in CD36. The coronary vasoconstrictive response correlated with expression of CD36 as assessed by immunoblotting and covalent binding with hexarelin. These data suggest that CD36 may mediate the coronary vasospasm seen in hypercholesterolemia and atherosclerosis.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"68 1","pages":"844-849"},"PeriodicalIF":0.0,"publicationDate":"2002-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74130392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-03DOI: 10.1161/01.RES.0000017068.58856.F3
A. Kiemer, N. Weber, R. Fürst, Nicole Bildner, Stefanie Kulhanek-Heinze, A. Vollmar
The atrial natriuretic peptide (ANP) is a cardiovascular hormone possessing antiinflammatory potential due to its inhibitory action on the production of inflammatory mediators, such as tumor necrosis factor-&agr; (TNF-&agr;). The aim of this study was to determine whether ANP is able to attenuate inflammatory effects of TNF-&agr; on target cells. Human umbilical vein endothelial cells (HUVECs) were treated with TNF-&agr; in the presence or absence of ANP. Changes in permeability, cytoskeletal alterations, phosphorylation of p38 MAPK and HSP27, and expression of MKP-1 were determined by macromolecule permeability assay, fluorescence labeling, RT-PCR, and immunoblotting. Antisense studies were done by transfecting cells with MKP-1 antisense oligonucleotides. Activation of HUVECs with TNF-&agr; lead to a significant increase of macromolecule permeability and formation of stress fibers. Treatment of cells with ANP (10−8 to 10−6 mol/L) significantly reduced the formation of stress fibers and elevated permeability. Both TNF-&agr;–induced effects were shown to be mediated via the activation of p38 using SB203580, a specific inhibitor of p38. ANP significantly reduced the TNF-&agr;–induced activation of p38 and attenuated the phosphorylation of HSP27, a central target downstream of p38. ANP showed no effect on p38 upstream kinases MKK3/6. However, a significant induction of the MAPK phosphatase MKP-1 mRNA and protein could be observed in ANP-treated cells. Antisense experiments proved a causal role for MKP-1 induction in the ANP-mediated inhibition of p38. These data show the inhibitory action of ANP on TNF-&agr;–induced changes in endothelial cytoskeleton and macromolecule permeability involving an MKP-1–induced inactivation of p38 MAPK. These effects point to an antiinflammatory and antiatherogenic potential of this cardiovascular hormone.
{"title":"Inhibition of p38 MAPK Activation via Induction of MKP-1: Atrial Natriuretic Peptide Reduces TNF-&agr;–Induced Actin Polymerization and Endothelial Permeability","authors":"A. Kiemer, N. Weber, R. Fürst, Nicole Bildner, Stefanie Kulhanek-Heinze, A. Vollmar","doi":"10.1161/01.RES.0000017068.58856.F3","DOIUrl":"https://doi.org/10.1161/01.RES.0000017068.58856.F3","url":null,"abstract":"The atrial natriuretic peptide (ANP) is a cardiovascular hormone possessing antiinflammatory potential due to its inhibitory action on the production of inflammatory mediators, such as tumor necrosis factor-&agr; (TNF-&agr;). The aim of this study was to determine whether ANP is able to attenuate inflammatory effects of TNF-&agr; on target cells. Human umbilical vein endothelial cells (HUVECs) were treated with TNF-&agr; in the presence or absence of ANP. Changes in permeability, cytoskeletal alterations, phosphorylation of p38 MAPK and HSP27, and expression of MKP-1 were determined by macromolecule permeability assay, fluorescence labeling, RT-PCR, and immunoblotting. Antisense studies were done by transfecting cells with MKP-1 antisense oligonucleotides. Activation of HUVECs with TNF-&agr; lead to a significant increase of macromolecule permeability and formation of stress fibers. Treatment of cells with ANP (10−8 to 10−6 mol/L) significantly reduced the formation of stress fibers and elevated permeability. Both TNF-&agr;–induced effects were shown to be mediated via the activation of p38 using SB203580, a specific inhibitor of p38. ANP significantly reduced the TNF-&agr;–induced activation of p38 and attenuated the phosphorylation of HSP27, a central target downstream of p38. ANP showed no effect on p38 upstream kinases MKK3/6. However, a significant induction of the MAPK phosphatase MKP-1 mRNA and protein could be observed in ANP-treated cells. Antisense experiments proved a causal role for MKP-1 induction in the ANP-mediated inhibition of p38. These data show the inhibitory action of ANP on TNF-&agr;–induced changes in endothelial cytoskeleton and macromolecule permeability involving an MKP-1–induced inactivation of p38 MAPK. These effects point to an antiinflammatory and antiatherogenic potential of this cardiovascular hormone.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"59 1","pages":"874-881"},"PeriodicalIF":0.0,"publicationDate":"2002-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82783863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-03DOI: 10.1161/01.RES.0000016481.87703.CC
Zane S. Jackson, A. Gotlieb, B. Langille
Changes in blood pressure or flow induce arterial remodeling that normalizes mechanical loads that are imposed on arterial tissue. Arteries are also under substantial longitudinal stretch (axial strain) that may be altered by growth or atrophy of tissues to which they are attached. We therefore tested whether axial strain is also regulated in a negative feedback manner through arterial remodeling. Axial strain in rabbit carotid arteries was increased from 62±2% to 97±2% without altering other mechanical loads on wall tissues. Strain was reduced within 3 days and completely normalized by 7 days. Remodeling involved tissue elaboration, endothelial cell replication rates were increased by >50-fold and smooth muscle cell replication rates were increased by >15-fold, and substantially elevated DNA, elastin, and collagen contents were recorded. Also, increased rates of apoptosis were indicated by degradation of DNA into oligonucleosomes, and matrix remodeling was reflected in enlarged fenestrae in the internal elastic lamina and increased expression and activation of gelatinases, especially matrix metalloproteinase-2. Intriguingly, reduced axial strain was not normalized, presumably because remodeling processes, apart from cell contraction, are ineffective in decreasing strain, and arterial smooth muscle orientation precludes large effects of contraction on axial strain.
{"title":"Wall Tissue Remodeling Regulates Longitudinal Tension in Arteries","authors":"Zane S. Jackson, A. Gotlieb, B. Langille","doi":"10.1161/01.RES.0000016481.87703.CC","DOIUrl":"https://doi.org/10.1161/01.RES.0000016481.87703.CC","url":null,"abstract":"Changes in blood pressure or flow induce arterial remodeling that normalizes mechanical loads that are imposed on arterial tissue. Arteries are also under substantial longitudinal stretch (axial strain) that may be altered by growth or atrophy of tissues to which they are attached. We therefore tested whether axial strain is also regulated in a negative feedback manner through arterial remodeling. Axial strain in rabbit carotid arteries was increased from 62±2% to 97±2% without altering other mechanical loads on wall tissues. Strain was reduced within 3 days and completely normalized by 7 days. Remodeling involved tissue elaboration, endothelial cell replication rates were increased by >50-fold and smooth muscle cell replication rates were increased by >15-fold, and substantially elevated DNA, elastin, and collagen contents were recorded. Also, increased rates of apoptosis were indicated by degradation of DNA into oligonucleosomes, and matrix remodeling was reflected in enlarged fenestrae in the internal elastic lamina and increased expression and activation of gelatinases, especially matrix metalloproteinase-2. Intriguingly, reduced axial strain was not normalized, presumably because remodeling processes, apart from cell contraction, are ineffective in decreasing strain, and arterial smooth muscle orientation precludes large effects of contraction on axial strain.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"4 1","pages":"918-925"},"PeriodicalIF":0.0,"publicationDate":"2002-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89977402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-05-03DOI: 10.1161/01.RES.0000016501.56641.83
J. Silence, D. Collen, H. Lijnen
Development and progression of atherosclerotic lesions and aneurysm formation were investigated in mice with single or combined deficiency of apolipoprotein E (ApoE) and tissue inhibitor of metalloproteinase-1 (TIMP-1) kept on a cholesterol-rich diet for 30 weeks. Atherosclerotic lesions throughout the thoracic aorta were significantly (P <0.001) larger in mice wild-type for TIMP-1 (ApoE−/−:TIMP-1+/+) than in mice deficient in TIMP-1 (ApoE−/−:TIMP-1−/−). Aneurysms in the thoracic and abdominal aortas were less frequent in ApoE−/−:TIMP-1+/+ mice than in ApoE−/−:TIMP-1−/− mice (11±3.0 versus 23±5.1 aneurysms per 100 sections analyzed, mean±SD, P <0.001). Immunocytochemistry revealed enhanced accumulation of Oil red O–stained lipids, colocalizing with macrophages in atherosclerotic lesions of ApoE−/−:TIMP-1−/− mice (P <0.05). In situ zymography using a casein substrate showed enhanced lysis in plaques of ApoE−/−:TIMP-1−/− mice as compared with ApoE−/−:TIMP-1+/+ mice (P <0.01). MMP activity was most pronounced at sites where degradation of the elastic lamina occurred. These data suggest that enhanced MMP activity, as a result of TIMP-1 deficiency, contributes to a reduction of atherosclerotic plaque size but promotes aneurysm formation.
研究了载脂蛋白E (ApoE)和金属蛋白酶组织抑制剂-1 (TIMP-1)单一或联合缺乏的小鼠在高胆固醇饮食30周后动脉粥样硬化病变和动脉瘤形成的发展和进展。TIMP-1野生型小鼠(ApoE−/−:TIMP-1+/+)的胸主动脉动脉粥样硬化病变明显(P <0.001)大于TIMP-1缺失小鼠(ApoE−/−:TIMP-1−/−)。ApoE−/−:TIMP-1+/+小鼠的胸腹主动脉动脉瘤发生率低于ApoE−/−:TIMP-1+/+小鼠(每100个切片11±3.0个动脉瘤vs 23±5.1个动脉瘤，平均值±SD, P <0.001)。免疫细胞化学显示，在ApoE−/−:TIMP-1−/−小鼠的动脉粥样硬化病变中，油红o染色的脂质积累增强，与巨噬细胞共定位(P <0.05)。酪蛋白底物原位酶谱分析显示，与ApoE−/−:TIMP-1+/+小鼠相比，ApoE−/−:TIMP-1−/ -小鼠斑块的酶解增强(P <0.01)。MMP活性在弹性层发生退化的部位最为明显。这些数据表明，由于TIMP-1缺乏，MMP活性增强有助于减少动脉粥样硬化斑块大小，但促进动脉瘤形成。
{"title":"Reduced Atherosclerotic Plaque but Enhanced Aneurysm Formation in Mice With Inactivation of the Tissue Inhibitor of Metalloproteinase-1 (TIMP-1) Gene","authors":"J. Silence, D. Collen, H. Lijnen","doi":"10.1161/01.RES.0000016501.56641.83","DOIUrl":"https://doi.org/10.1161/01.RES.0000016501.56641.83","url":null,"abstract":"Development and progression of atherosclerotic lesions and aneurysm formation were investigated in mice with single or combined deficiency of apolipoprotein E (ApoE) and tissue inhibitor of metalloproteinase-1 (TIMP-1) kept on a cholesterol-rich diet for 30 weeks. Atherosclerotic lesions throughout the thoracic aorta were significantly (P <0.001) larger in mice wild-type for TIMP-1 (ApoE−/−:TIMP-1+/+) than in mice deficient in TIMP-1 (ApoE−/−:TIMP-1−/−). Aneurysms in the thoracic and abdominal aortas were less frequent in ApoE−/−:TIMP-1+/+ mice than in ApoE−/−:TIMP-1−/− mice (11±3.0 versus 23±5.1 aneurysms per 100 sections analyzed, mean±SD, P <0.001). Immunocytochemistry revealed enhanced accumulation of Oil red O–stained lipids, colocalizing with macrophages in atherosclerotic lesions of ApoE−/−:TIMP-1−/− mice (P <0.05). In situ zymography using a casein substrate showed enhanced lysis in plaques of ApoE−/−:TIMP-1−/− mice as compared with ApoE−/−:TIMP-1+/+ mice (P <0.01). MMP activity was most pronounced at sites where degradation of the elastic lamina occurred. These data suggest that enhanced MMP activity, as a result of TIMP-1 deficiency, contributes to a reduction of atherosclerotic plaque size but promotes aneurysm formation.","PeriodicalId":10314,"journal":{"name":"Circulation Research: Journal of the American Heart Association","volume":"7 1","pages":"897-903"},"PeriodicalIF":0.0,"publicationDate":"2002-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86543504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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