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Molecular context of Schistosoma mansoni transmission in the molluscan environments: A mini-review. Acta Trop 2017; 176:98-104. [PMID: 28754250 DOI: 10.1016/j.actatropica.2017.07.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 07/18/2017] [Accepted: 07/19/2017] [Indexed: 12/22/2022]
Abstract
Schistosoma mansoni, being transmitted by some freshwater Biomphalaria snails, is a major causative agent of human schistosomiasis. In the absence of effective vaccine and alternative drug designs to fight against the disease, and with the limitations of molluscicide application, developing more efficient strategies to interrupt the snail-mediated parasite transmission is being emphasized as potentially instrumental in the efforts toward schistosomiasis elimination, hence, necessitating thorough and comprehensive understanding of the fundamental mechanisms involved in the transmission process. Based on the current advances, this paper presents a concise exposition of the cellular, biochemical, genetic and immunological dynamics of the complex and statge-by-stage interactions between the parasite and its vector in their aquatic environment. It also highlights the possible crosstalk between the parasite's intracellular cyclic adenosine monophosphate (cAMP) and p38 mitogen-activated protein kinase (p38 MAPK) during the intramolluscan stage. Undoubtedly, decades of intensive investigation have untangled many S. mansoni-B. glabrata complexities, yet many aspects of the parasite-vector cycle which can help define potential control clues await further elucidation.
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2
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Crajoinas RO, Polidoro JZ, Carneiro de Morais CPA, Castelo-Branco RC, Girardi ACC. Angiotensin II counteracts the effects of cAMP/PKA on NHE3 activity and phosphorylation in proximal tubule cells. Am J Physiol Cell Physiol 2016; 311:C768-C776. [PMID: 27510906 DOI: 10.1152/ajpcell.00191.2016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 07/29/2016] [Indexed: 12/16/2022]
Abstract
Binding of angiotensin II (ANG II) to the AT1 receptor (AT1R) in the proximal tubule stimulates Na+/H+ exchanger isoform 3 (NHE3) activity through multiple signaling pathways. However, the effects of ANG II/AT1R-induced inihibitory G protein (Gi) activation and subsequent decrease in cAMP accumulation on NHE3 regulation are not well established. We therefore tested the hypothesis that ANG II reduces cAMP/PKA-mediated phosphorylation of NHE3 on serine 552 and, in doing so, stimulates NHE3 activity. Under basal conditions, ANG II stimulated NHE3 activity but did not affect PKA-mediated NHE3 phosphorylation at serine 552 in opossum kidney (OKP) cells. However, in the presence of the cAMP-elevating agent forskolin (FSK), ANG II blocked FSK-induced NHE3 inhibition, reduced intracellular cAMP concentrations, lowered PKA activity, and prevented the FSK-mediated increase in NHE3 serine 552 phosphorylation. All effects of ANG II were blocked by pretreating OKP cells with the AT1R antagonist losartan, highlighting the contribution of the AT1R/Gi pathway in ANG II-mediated NHE3 upregulation under cAMP-elevating conditions. Accordingly, Gi inhibition by pertussis toxin treatment decreased NHE3 activity both in vitro and in vivo and, more importantly, prevented the stimulatory effect of ANG II on NHE3 activity in rat proximal tubules. Collectively, our results suggest that ANG II counteracts the effects of cAMP/PKA on NHE3 phosphorylation and inhibition by activating the AT1R/Gi pathway. Moreover, these findings support the notion that NHE3 dephosphorylation at serine 552 may represent a key event in the regulation of renal proximal tubule sodium handling by ANG II in the presence of natriuretic hormones that promote cAMP accumulation and transporter phosphorylation.
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Affiliation(s)
- Renato O Crajoinas
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, São Paulo, Brazil; and
| | - Juliano Z Polidoro
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, São Paulo, Brazil; and
| | - Carla P A Carneiro de Morais
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, São Paulo, Brazil; and
| | - Regiane C Castelo-Branco
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, São Paulo, São Paulo, Brazil
| | - Adriana C C Girardi
- Laboratory of Genetics and Molecular Cardiology, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, São Paulo, Brazil; and
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Gusan S, Anand-Srivastava MB. cAMP attenuates the enhanced expression of Gi proteins and hyperproliferation of vascular smooth muscle cells from SHR: role of ROS and ROS-mediated signaling. Am J Physiol Cell Physiol 2013; 304:C1198-209. [PMID: 23576581 DOI: 10.1152/ajpcell.00269.2012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We previously showed that angiotensin II (ANG II)-induced overexpression of inhibitory G proteins (Gi) was attenuated by dibutyryl-cAMP (db-cAMP) in A10 vascular smooth muscle cells (VSMC). Since enhanced levels of endogenous ANG II contributed to the overexpression of Gi protein and hyperproliferation of VSMC from spontaneously hypertensive rats (SHR), the present study was therefore undertaken to examine if cAMP could also attenuate the overexpression of Gi proteins and hyperproliferation of VSMC from SHR and to explore the underlying molecular mechanisms responsible for this response. The enhanced expression of Giα proteins in VSMC from SHR and Nω-nitro-L-arginine methyl ester hypertensive rats was decreased by db-cAMP. In addition, enhanced inhibition of adenylyl cyclase by inhibitory hormones and forskolin-stimulated adenylyl cyclase activity by low concentration of GTPγS in VSMC from SHR was also restored to Wistar-Kyoto (WKY) levels by db-cAMP. Furthermore, db-cAMP also attenuated the hyperproliferation and the increased production of superoxide anion, NAD(P)H oxidase activity, overexpression of Nox1/Nox2/Nox4 and p47phox proteins, increased phosphorylation of PDGF-receptor (R), EGF-R, c-Src, and ERK1/2 to control levels. In addition, the protein kinase A (PKA) inhibitor reversed the effects of db-cAMP on the expression of Nox4 and Giα proteins and hyperproliferation of VSMC from SHR to WKY levels, while stimulation of the exchange protein directly activated by cAMP did not have any effect on these parameters. These results suggest that cAMP via PKA pathway attenuates the overexpression of Gi proteins and hyperproliferation of VSMC from SHR through the inhibition of ROS and ROS-mediated transactivation of EGF-R/PDGF-R and MAPK signaling pathways.
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Affiliation(s)
- Svetlana Gusan
- Department of Physiology, Université de Montréal, Montreal, Quebec, Canada
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Goncharova EA, Khavin IS, Goncharov DA, Krymskaya VP. Differential effects of formoterol on thrombin- and PDGF-induced proliferation of human pulmonary arterial vascular smooth muscle cells. Respir Res 2012. [PMID: 23186269 PMCID: PMC3545871 DOI: 10.1186/1465-9921-13-109] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Background Increased pulmonary arterial vascular smooth muscle (PAVSM) cell proliferation is a key pathophysiological component of pulmonary vascular remodeling in pulmonary arterial hypertension (PH). The long-acting β2-adrenergic receptor (β2AR) agonist formoterol, a racemate comprised of (R,R)- and (S,S)-enantiomers, is commonly used as a vasodilator in chronic obstructive pulmonary disease (COPD). PH, a common complication of COPD, increases patients’ morbidity and reduces survival. Recent studies demonstrate that formoterol has anti-proliferative effects on airway smooth muscle cells and bronchial fibroblasts. The effects of formoterol and its enantiomers on PAVSM cell proliferation are not determined. The goals of this study were to examine effects of racemic formoterol and its enantiomers on PAVSM cell proliferation as it relates to COPD-associated PH. Methods Basal, thrombin-, PDGF- and chronic hypoxia-induced proliferation of primary human PAVSM cells was examined by DNA synthesis analysis using BrdU incorporation assay. ERK1/2, mTORC1 and mTORC2 activation were determined by phosphorylation levels of ERK1/2, ribosomal protein S6 and S473-Akt using immunoblot analysis. Results We found that (R,R) and racemic formoterol inhibited basal, thrombin- and chronic hypoxia-induced proliferation of human PAVSM cells while (S,S) formoterol had lesser inhibitory effect. The β2AR blocker propranolol abrogated the growth inhibitory effect of formoterol. (R,R), but not (S,S) formoterol attenuated basal, thrombin- and chronic hypoxia-induced ERK1/2 phosphorylation, but had little effect on Akt and S6 phosphorylation levels. Formoterol and its enantiomers did not significantly affect PDGF-induced DNA synthesis and PDGF-dependent ERK1/2, S473-Akt and S6 phosphorylation in human PAVSM cells. Conclusions Formoterol inhibits basal, thrombin-, and chronic hypoxia-, but not PDGF-induced human PAVSM cell proliferation and ERK1/2, but has little effect on mTORC1 and mTORC2 signaling. Anti-proliferative effects of formoterol depend predominantly on its (R,R) enantiomer and require the binding with β2AR. These data suggest that (R,R) formoterol may be considered as potential adjuvant therapy to inhibit PAVSM cell proliferation in COPD-associated PH.
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Affiliation(s)
- Elena A Goncharova
- Pulmonary, Allergy & Critical Care Division, Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
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Uemura Y, Shibata R, Ohashi K, Enomoto T, Kambara T, Yamamoto T, Ogura Y, Yuasa D, Joki Y, Matsuo K, Miyabe M, Kataoka Y, Murohara T, Ouchi N. Adipose-derived factor CTRP9 attenuates vascular smooth muscle cell proliferation and neointimal formation. FASEB J 2012; 27:25-33. [PMID: 22972916 DOI: 10.1096/fj.12-213744] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Obesity is closely associated with the progression of vascular disorders, including atherosclerosis and postangioplasty restenosis. C1q/TNF-related protein (CTRP) 9 is an adipocytokine that is down-regulated in obese mice. Here we investigated whether CTRP9 modulates neointimal hyperplasia and vascular smooth muscle cell (VSMC) proliferation in vivo and in vitro. Left femoral arteries of wild-type (WT) mice were injured by a steel wire. An adenoviral vector expressing CTRP9 (Ad-CTRP9) or β-galactosidase as a control was intravenously injected into WT mice 3 d before vascular injury. Delivery of Ad-CTRP9 significantly attenuated the neointimal thickening and the number of bromodeoxyuridine-positive proliferating cells in the injured arteries compared with that of control. Treatment of VSMCs with CTRP9 protein attenuated the proliferative and chemotactic activities induced by growth factors including platelet-derived growth factor (PDGF)-BB, and suppressed PDGF-BB-stimulated phosphorylation of ERK. CTRP9 treatment dose-dependently increased cAMP levels in VSMCs. Blockade of cAMP-PKA pathway reversed the inhibitory effect of CTRP9 on DNA synthesis and ERK phosphorylation in response to PDGF-BB. The present data indicate that CTRP9 functions to attenuate neointimal formation following vascular injury through its ability to inhibit VSMC growth via cAMP-dependent mechanism, suggesting that the therapeutic approaches to enhance CTRP9 production could be valuable for prevention of vascular restenosis after angioplasty.
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Affiliation(s)
- Yusuke Uemura
- Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
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Miller CL, Cai Y, Oikawa M, Thomas T, Dostmann WR, Zaccolo M, Fujiwara K, Yan C. Cyclic nucleotide phosphodiesterase 1A: a key regulator of cardiac fibroblast activation and extracellular matrix remodeling in the heart. Basic Res Cardiol 2011; 106:1023-39. [PMID: 22012077 DOI: 10.1007/s00395-011-0228-2] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 10/07/2011] [Accepted: 10/10/2011] [Indexed: 11/26/2022]
Abstract
Cardiac fibroblasts become activated and differentiate to smooth muscle-like myofibroblasts in response to hypertension and myocardial infarction (MI), resulting in extracellular matrix (ECM) remodeling, scar formation and impaired cardiac function. cAMP and cGMP-dependent signaling have been implicated in cardiac fibroblast activation and ECM synthesis. Dysregulation of cyclic nucleotide phosphodiesterase (PDE) activity/expression is also associated with various diseases and several PDE inhibitors are currently available or in development for treating these pathological conditions. The objective of this study is to define and characterize the specific PDE isoform that is altered during cardiac fibroblast activation and functionally important for regulating myofibroblast activation and ECM synthesis. We have found that Ca(2+)/calmodulin-stimulated PDE1A isoform is specifically induced in activated cardiac myofibroblasts stimulated by Ang II and TGF-β in vitro as well as in vivo within fibrotic regions of mouse, rat, and human diseased hearts. Inhibition of PDE1A function via PDE1-selective inhibitor or PDE1A shRNA significantly reduced Ang II or TGF-β-induced myofibroblast activation, ECM synthesis, and pro-fibrotic gene expression in rat cardiac fibroblasts. Moreover, the PDE1 inhibitor attenuated isoproterenol-induced interstitial fibrosis in mice. Mechanistic studies revealed that PDE1A modulates unique pools of cAMP and cGMP, predominantly in perinuclear and nuclear regions of cardiac fibroblasts. Further, both cAMP-Epac-Rap1 and cGMP-PKG signaling was involved in PDE1A-mediated regulation of collagen synthesis. These results suggest that induction of PDE1A plays a critical role in cardiac fibroblast activation and cardiac fibrosis, and targeting PDE1A may lead to regression of the adverse cardiac remodeling associated with various cardiac diseases.
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Affiliation(s)
- Clint L Miller
- Department of Pharmacology and Physiology, Aab Cardiovascular Research Institute, University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave, Box CVRI, Rochester, NY 14642, USA
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Hewer RC, Sala-Newby GB, Wu YJ, Newby AC, Bond M. PKA and Epac synergistically inhibit smooth muscle cell proliferation. J Mol Cell Cardiol 2010; 50:87-98. [PMID: 20971121 PMCID: PMC3093616 DOI: 10.1016/j.yjmcc.2010.10.010] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 10/08/2010] [Accepted: 10/11/2010] [Indexed: 12/14/2022]
Abstract
Cyclic AMP signalling promotes VSMC quiescence in healthy vessels and during vascular healing following injury. Cyclic AMP inhibits VSMC proliferation via mechanisms that are not fully understood. We investigated the role of PKA and Epac signalling on cAMP-induced inhibition of VSMC proliferation. cAMP-mediated growth arrest was PKA-dependent. However, selective PKA activation with 6-Benzoyl-cAMP did not inhibit VSMC proliferation, indicating a requirement for additional pathways. Epac activation using the selective cAMP analogue 8-CPT-2′-O-Me-cAMP, did not affect levels of hyperphosphorylated Retinoblastoma (Rb) protein, a marker of G1-S phase transition, or BrdU incorporation, despite activation of the Epac-effector Rap1. However, 6-Benzoyl-cAMP and 8-CPT-2′-O-Me-cAMP acted synergistically to inhibit Rb-hyperphosphorylation and BrdU incorporation, indicating that both pathways are required for growth inhibition. Consistent with this, constitutively active Epac increased Rap1 activity and synergised with 6-Benzoyl-cAMP to inhibit VSMC proliferation. PKA and Epac synergised to inhibit phosphorylation of ERK and JNK. Induction of stellate morphology, previously associated with cAMP-mediated growth arrest, was also dependent on activation of both PKA and Epac. Rap1 inhibition with Rap1GAP or siRNA silencing did not negate forskolin-induced inhibition of Rb-hyperphosphorylation, BrdU incorporation or stellate morphology. This data demonstrates for the first time that Epac synergises with PKA via a Rap1-independent mechanism to mediate cAMP-induced growth arrest in VSMC. This work highlights the role of Epac as a major player in cAMP-dependent growth arrest in VSMC.
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Kumar D, Luan L, Pathak S, Salhan D, Magoon S, Singhal PC. Ang II enhances tubular cell Ets-1 expression and associated down stream signaling is mediated through AT1 receptors. Ren Fail 2010; 32:986-91. [DOI: 10.3109/0886022x.2010.501936] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
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White M, Ross H, Levesque S, Whittom L, Pelletier GB, Racine N, Meloche S, Voisin L. Effects of angiotensin-converting enzyme inhibitor versus valsartan on cellular signaling events in heart transplant. Ann Pharmacother 2009; 43:831-9. [PMID: 19417110 DOI: 10.1345/aph.1l602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) provide similar biologic effects in model systems and similar clinical impacts in humans. The changes in the cardiac angiotensin system signaling pathways in the human heart in response to ACE inhibitors versus ARBs have been incompletely studied. OBJECTIVE To investigate the effects of ACE inhibitors versus valsartan on the angiotensin II signal transduction pathways in the transplanted human heart. METHODS Twenty-seven stable cardiac transplant recipients were randomized to remain on ACE inhibitor therapy (n = 8) or to receive valsartan (n = 19). Two additional endomyocardial biopsy samples were obtained at baseline and after 9 months of therapy. The expression of cardiac angiotensin type I and II receptors and atrial natriuretic factor (ANF) was measured by quantitative polymerase chain reaction. The expression and phosphorylation levels of selected signal transduction pathways were analyzed by immunoblotting. RESULTS The mean dose of valsartan was 114 +/- 41 mg/day. The use of valsartan resulted in a similar impact on blood pressure and biochemistry profile. There were no significant changes in the expression of angiotensin type I and II receptors and ANF with valsartan. Similarly, no significant changes in the expression and phosphorylation of Jun N-terminal kinase, extracellular signal-regulated kinase 1 and 2, and p38 mitogen-activated protein kinases or AKT, and mammalian target of rapamycin was observed in the valsartan-treated group. CONCLUSIONS Valsartan use is associated with similar clinical and molecular cardiac effects as ACE inhibitor therapy in stable long-term cardiac transplant recipients.
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Affiliation(s)
- Michel White
- Department of Medicine, Montreal Heart Institute and University of Montreal, Montreal, Quebec, Canada.
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Hirata K, Kume S, Araki SI, Sakaguchi M, Chin-Kanasaki M, Isshiki K, Sugimoto T, Nishiyama A, Koya D, Haneda M, Kashiwagi A, Uzu T. Exendin-4 has an anti-hypertensive effect in salt-sensitive mice model. Biochem Biophys Res Commun 2009; 380:44-9. [PMID: 19150338 DOI: 10.1016/j.bbrc.2009.01.003] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Accepted: 01/05/2009] [Indexed: 12/20/2022]
Abstract
The improvement of salt-sensitive hypertension is a therapeutic target for various vascular diseases. Glucagon-like peptide 1 (GLP-1), an incretin peptide, has been reported to have natriuretic effect as well as blood glucose lowering effect, although its exact mechanism and clinical usefulness remain unclear. Here, we examined anti-hypertensive effect of exendin-4, a GLP-1 analog, in salt-sensitive obese db/db mice and angiotensin II (angII)-infused C57BLK6/J mice. The treatment of exendin-4 for 12 weeks inhibited the development of hypertension in db/db mice. In db/db mice, the urinary sodium excretion was delayed and blood pressure was elevated in response to a high-salt load, whereas these were attenuated by exendin-4. In db/db mice, intra-renal angII concentration was increased. Furthermore, exendin-4 prevented angII-induced hypertension in non-diabetic mice and inhibited angII-induced phosphorylation of ERK1/2 in cultured renal cells. Considered together, our results indicate that exendin-4 has anti-hypertensive effects through the attenuation of angII-induced high-salt sensitivity.
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Affiliation(s)
- Kunio Hirata
- Department of Medicine, Shiga University of Medical Science, Tsukinowa-cho, Seta, Otsu, Shiga 520-2192, Japan
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Carey RM. Pathophysiology of Primary Hypertension. Microcirculation 2008. [DOI: 10.1016/b978-0-12-374530-9.00020-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Gong KZ, Zhang H, Du JH, Zhang YY. Crosstalk between signaling pathways of adrenoreceptors and signal transducers and activators of transcription 3 (STAT3) in heart. Acta Pharmacol Sin 2007; 28:153-65. [PMID: 17241516 DOI: 10.1111/j.1745-7254.2007.00525.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Recently, there have been important advancements in our understanding of the signaling mechanisms of adrenoreceptors (AR) and signal transducers and activators of transcription 3 (STAT3). While their crucial roles in the pathological processes of the heart are well established, accumulating evidence suggests there is a complex pattern of crosstalk between these 2 signaling pathways. Moreover, the potential for crosstalk occurs at multiple levels in each signaling cascade and involves receptor transactivation, G proteins, small GTPases, cyclic adenosine 3',5'-monophosphate/protein kinase A, protein kinase C, scaffold/adaptor proteins, protein tyrosine kinases, and mitogen-activated protein kinases. In addition, post-translational modification (eg acetylation) of STAT3 may provide a link between STAT3 and AR signaling. In particular, crosstalk between these 2 systems in the heart would appear to be dependent upon the species/tissue studied, developmental stage, and eliciting stimulus. This at least partly accounts for the epigenetic effects on biological function that is mediated by the 2 signaling pathways. Elucidation of these mechanisms will provide new targets in the development of novel clinical strategies for heart disorders.
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Affiliation(s)
- Kai-zheng Gong
- Institute of Vascular Medicine, Peking University Third Hospital, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing 100083, China
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Pelletier S, Julien C, Popoff MR, Lamarche-Vane N, Meloche S. Cyclic AMP induces morphological changes of vascular smooth muscle cells by inhibiting a Rac-dependent signaling pathway. J Cell Physiol 2005; 204:412-22. [PMID: 15706595 DOI: 10.1002/jcp.20308] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Cyclic AMP (cAMP) is a pleiotropic second messenger that regulates numerous cellular processes. In vascular smooth muscle cells (VSMCs), these include cell proliferation, migration, and contractility. Here we show that cAMP-elevating agents induce dramatic morphological changes in VSMCs, characterized by cell rounding and formation of long branching processes. The stellate morphology is associated with disassembly of actin stress fibers and lamellipodia, loss of focal adhesions, and the formation of small F-actin rings. Because of the importance of Rho family GTPases in regulating actin dynamics, we analyzed their individual roles in the cAMP phenotype. We found that pharmacological or genetic inhibition of Rac mimics cAMP effect in inducing a stellate morphology of VSMCs. Expression of activated Rac1 prevents forskolin-induced cAMP stellation, suggesting that cAMP affects cell morphology by inhibiting Rac function. Consistent with this, treatment with forskolin inhibits agonist-stimulated Rac activation in VSMCs. We further show that activated Rac1 containing the F37A effector loop substitution fails to rescue the cAMP phenotype. Our results suggest that cAMP modulates the morphology of VSMCs by inhibiting a Rac-dependent signaling pathway.
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Affiliation(s)
- Stéphane Pelletier
- Institut de Recherche en Immunovirologie et Cancérologie, Université de Montréal, Montreal, Quebec, Canada
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15
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Siragy HM, Carey RM. The Angiotensin Receptors: AT1 and AT2. Hypertension 2005. [DOI: 10.1016/b978-0-7216-0258-5.50101-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Gravel SP, Servant MJ. Roles of an IkappaB kinase-related pathway in human cytomegalovirus-infected vascular smooth muscle cells: a molecular link in pathogen-induced proatherosclerotic conditions. J Biol Chem 2004; 280:7477-86. [PMID: 15619605 DOI: 10.1074/jbc.m410392200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Viral and bacterial pathogens have long been suspected to affect atherogenesis directly. However, mechanisms linking innate immunity to chronic inflammatory diseases such as atherosclerosis are still poorly defined. Here we show that infection of primary human aortic smooth muscle cells (HAOSMC) with human cytomegalovirus (HCMV) leads to activation of the novel IkappaB kinase (IKK)-related kinase, Tank-binding kinase-1 (TBK1), a major effector of the cellular innate immune response. We demonstrate that part of the HCMV inflammatory response is most likely mediated via this novel kinase because the canonical IKK complex was only poorly activated upon infection of HAOSMC. An increase in TBK1 phosphotransferase activity led to a strong activation of the interferon regulatory factor (IRF)-3 transcription factor as measured by its C-terminal phosphorylation, dimerization, and DNA binding activity. In addition to TBK1, HAOSMC also express another IKK-related kinase isoform, IKKepsilon, albeit at a lower level. Nevertheless, both isoforms were required for full activation of IRF-3 by HCMV. The transcripts of proatherosclerotic genes Ccl5 (encoding for the chemokine RANTES (regulated upon activation, normal T cell expressed and secreted)) and Cxcl10 (encoding for the chemokine IP-10 (interferon-gamma-inducible protein 10)) were induced in an IRF-3-dependent manner after HCMV infection of smooth muscle cells. In addition, cytokine arrays analysis showed that RANTES and IP-10 were the predominant chemokines present in the supernatant of HCMV-infected HAOSMC. Activation of the TBK1/IRF-3 pathway was independent of epidermal growth factor receptor and pertussis toxin-sensitive G protein-coupled receptor activation. Our results thus add additional molecular clues to a possible role of HCMV as a modulator of atherogenesis through the induction of a proinflammatory response that is, in part, dependent of an IKK-related kinase pathway.
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MESH Headings
- Adaptor Proteins, Signal Transducing/metabolism
- Amino Acid Sequence
- Animals
- Arteriosclerosis/pathology
- Arteriosclerosis/virology
- Cells, Cultured
- Chemokine CCL5/metabolism
- Chemokine CXCL10
- Chemokines, CC/metabolism
- Chemokines, CXC/metabolism
- Cycloheximide/pharmacology
- Cytomegalovirus/genetics
- DNA/metabolism
- DNA-Binding Proteins/metabolism
- Dimerization
- Electrophoresis, Polyacrylamide Gel
- Endothelium, Vascular/pathology
- Enzyme Activation
- GTP-Binding Proteins/metabolism
- Humans
- I-kappa B Kinase
- Inflammation
- Interferon Regulatory Factor-3
- Molecular Sequence Data
- Muscle, Smooth, Vascular/virology
- Myocytes, Smooth Muscle/virology
- Pertussis Toxin/pharmacology
- Phosphorylation
- Plasmids/metabolism
- Protein Isoforms
- Protein Serine-Threonine Kinases/metabolism
- Protein Structure, Tertiary
- RNA, Small Interfering/metabolism
- Rats
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Homology, Amino Acid
- Signal Transduction
- Time Factors
- Transcription Factors/metabolism
- U937 Cells
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Affiliation(s)
- Simon-Pierre Gravel
- Faculty of Pharmacy, University of Montreal, Montreal, Quebec H3C 3J7, Canada
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Olschewski H, Rose F, Schermuly R, Ghofrani HA, Enke B, Olschewski A, Seeger W. Prostacyclin and its analogues in the treatment of pulmonary hypertension. Pharmacol Ther 2004; 102:139-53. [PMID: 15163595 DOI: 10.1016/j.pharmthera.2004.01.003] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Prostacyclin and its analogues (prostanoids) are potent vasodilators and possess antithrombotic and antiproliferative properties. All of these properties help to antagonize the pathological changes that take place in the small pulmonary arteries of patients with pulmonary hypertension. Indeed, several prostanoids have been shown to be efficacious to treat pulmonary hypertension, while the main mechanism underlying the beneficial effects remains unknown. There are indications of beneficial combination effects of prostaglandins and phosphodiesterase inhibitors and endothelin receptor antagonists. This speaks in favor of combination therapies for pulmonary hypertension in the future. The mode of application of prostanoids used in randomized controlled studies has been quite variable: continuous i.v. infusion of prostacyclin, continuous s.c. infusion of treprostinil, p.o. application of beraprost, and inhaled application of iloprost. In addition, the applied doses were quite different, ranging from 0.25 ng/kg/min for inhaled iloprost to 30-50 ng/kg/min for i.v. prostacyclin. While the principal pharmacological properties of all prostanoids are very similar due to a main action on IP receptors, there are considerable differences in pharmacokinetics and metabolism, with half-lives of 2 min for prostacyclin and about 34 min for treprostinil for i.v. infused drugs and half-lives of about 85 min for s.c. infused treprostinil. In addition, the adverse effects largely depend on the doses used and the mode of application, although there is great variability between subjects. It remains to be determined which patients will profit most from which substance (or combination) and mode of application.
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Abstract
Prostaglandins released by injured vascular tissue can modulate smooth muscle cell (SMC) proliferation. The mechanism of action of PGE(2) was investigated with porcine coronary artery SMCs obtained by explant culture. DNA and RNA syntheses exhibited a concentration-dependent increase following treatment of quiescent SMCs with PGE(2), while PGI(2) had no effect. PGE(2) also elevated PCNA expression, bromodeoxyuridine incorporation, and cell number, indicative of a hyperplastic growth response. Furthermore, induction of c-fos expression required activation of both phosphatidylinositol 3-kinase and mitogen-activated protein kinase. Contrary to these data, treatment of proliferating cells with PGE(2) caused a reduction in DNA synthesis. A role for PKA in either growth stimulation or inhibition was excluded. Interestingly, only quiescent SMCs expressed EP2 receptors, and the selective EP2 receptor agonist butaprost confirmed that this receptor was essential for growth stimulation and possibly inhibition. These data suggest that the growth state-dependent actions of PGE(2) on SMC proliferation may be mediated via the EP2 receptor.
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Affiliation(s)
- Lorraine Yau
- Department of Physiology, University of Manitoba, Manitoba, Canada
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19
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Pelletier S, Duhamel F, Coulombe P, Popoff MR, Meloche S. Rho family GTPases are required for activation of Jak/STAT signaling by G protein-coupled receptors. Mol Cell Biol 2003; 23:1316-33. [PMID: 12556491 PMCID: PMC141129 DOI: 10.1128/mcb.23.4.1316-1333.2003] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
As do cytokine receptors and receptor tyrosine kinases, G protein-coupled receptors (GPCRs) signal to Janus kinases (Jaks) and signal transducers and activators of transcription (STATs). However, the early biochemical events linking GPCRs to this signaling pathway have been unclear. Here we show that GPCR-stimulated Rac activity and the subsequent generation of reactive oxygen species are necessary for activating tyrosine phosphorylation of Jaks and STAT-dependent transcription. The requirement for Rac activity can be overcome by addition of hydrogen peroxide. Expression of activated mutants of Rac1 is sufficient to activate Jak2 and STAT-dependent transcription, and the activation of Jak2 correlates with the ability of Rac1 to bind to NADPH oxidase subunit p67(phox). We further show that GPCR agonists stimulate tyrosine phosphorylation of STAT1 and STAT3 proteins in a Rac-dependent manner. The tyrosine phosphorylation of STAT3 is biphasic; the first peak of phosphorylation is weak and correlates with rapid activation of Jaks by GPCRs, whereas the second peak is stronger and requires the synthesis of an autocrine factor. Rho also plays an essential role in the induction of STAT transcriptional activity. Our results highlight a novel role for Rho GTPases in mediating the regulatory effects of GPCRs on STAT-dependent gene expression.
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MESH Headings
- Angiotensin II/pharmacology
- Animals
- Antioxidants/pharmacology
- Bacterial Toxins/pharmacology
- Cells, Cultured
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/metabolism
- GTP-Binding Proteins/metabolism
- Humans
- Janus Kinase 2
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Mutation
- Oxidants/pharmacology
- Phosphorylation
- Protein-Tyrosine Kinases/genetics
- Protein-Tyrosine Kinases/metabolism
- Proto-Oncogene Proteins
- Rats
- Reactive Oxygen Species/metabolism
- Receptors, Cytoplasmic and Nuclear/drug effects
- Receptors, Cytoplasmic and Nuclear/metabolism
- STAT1 Transcription Factor
- STAT2 Transcription Factor
- STAT3 Transcription Factor
- Signal Transduction
- Thrombin/pharmacology
- Trans-Activators/genetics
- Trans-Activators/metabolism
- Transcription, Genetic
- Tyrosine/metabolism
- rac1 GTP-Binding Protein/drug effects
- rac1 GTP-Binding Protein/genetics
- rac1 GTP-Binding Protein/metabolism
- rho GTP-Binding Proteins/drug effects
- rho GTP-Binding Proteins/metabolism
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Affiliation(s)
- Stéphane Pelletier
- Institut de recherches cliniques de Montréal and Department of Pharmacology, Université de Montréal, Montréal, Québec, Canada
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20
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Konger RL, Scott GA, Landt Y, Ladenson JH, Pentland AP. Loss of the EP2 prostaglandin E2 receptor in immortalized human keratinocytes results in increased invasiveness and decreased paxillin expression. THE AMERICAN JOURNAL OF PATHOLOGY 2002; 161:2065-78. [PMID: 12466123 PMCID: PMC1850902 DOI: 10.1016/s0002-9440(10)64485-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Prostaglandin E(2) (PGE(2)) receptor subtype EP(2), which is coupled to cAMP metabolism, is known to mediate proliferation of primary human keratinocytes in vitro. The effect of gain or loss of EP(2) receptors in immortalized human keratinocytes (HaCat cells) was examined. HaCat keratinocytes were transfected with sense or anti-sense constructs of the EP(2) receptor. Loss or gain of EP(2) expression was documented by immunoblot and associated changes in agonist-stimulated cAMP production. Loss or gain of EP(2) receptor expression correlated with alterations in plating efficiencies but with modest affects on growth. When cell lines were studied in an organ culture model, anti-sense clones were highly invasive compared with vector controls and sense transfectants. A marked increase in prostaglandin production is commonly seen in malignant lesions. Because prostaglandin receptors are known to undergo ligand-induced receptor down-regulation, we sought to determine whether EP(2) receptor down-regulation results in increased invasiveness. In vector controls, invasiveness was reproduced by ligand-dependent EP(2) receptor down-regulation as assessed by immunohistochemistry. In addition, loss of EP(2) receptor expression was associated with decreased paxillin expression, a critical component of focal adhesion assembly. Thus, down-regulation of EP(2) receptors represents a potential mechanism for neoplastic progression to an invasive phenotype.
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Affiliation(s)
- Raymond L Konger
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, 406 Fesler Hall, 1120 South Drive, Indianapolis, IN 46202, USA.
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21
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Voisin L, Foisy S, Giasson E, Lambert C, Moreau P, Meloche S. EGF receptor transactivation is obligatory for protein synthesis stimulation by G protein-coupled receptors. Am J Physiol Cell Physiol 2002; 283:C446-55. [PMID: 12107054 DOI: 10.1152/ajpcell.00261.2001] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The epidermal growth factor receptor (EGFR) was recently identified as a signal transducer of G protein-coupled receptors (GPCRs). In this study, we have examined the contribution of EGFR transactivation to the growth-promoting effect of GPCRs on vascular smooth muscle cells. Activation of the G(q)-coupled ANG II receptor or G(i)-coupled lysophosphatidic acid receptor resulted in increased tyrosine phosphorylation and activation of EGFR. Specific inhibition of EGFR kinase activity by tyrphostin AG-1478 or expression of a dominant-negative EGFR mutant abolished this response. Importantly, inhibition of EGFR function strongly attenuated the global stimulation of protein synthesis by GPCR agonists in vitro in cultured aortic smooth muscle cells and in vivo in the rat aorta and in small resistance arteries. The growth inhibition was associated with a marked reduction of extracellular signal-regulated kinase and phosphoinositide 3-kinase pathway activity and the resulting suppression of eukaryotic translation initiation factor 4E and 4E binding protein 1 phosphorylation. Our results demonstrate that EGFR transactivation is a physiologically relevant action of GPCRs linked to translational control and protein synthesis.
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MESH Headings
- Animals
- Cell Division/physiology
- Cells, Cultured
- ErbB Receptors/genetics
- Eukaryotic Initiation Factor-4E
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Protein alpha Subunits, Gq-G11
- GTP-Binding Proteins/metabolism
- Heterotrimeric GTP-Binding Proteins/metabolism
- Muscle Proteins/biosynthesis
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/metabolism
- Peptide Initiation Factors/metabolism
- Rats
- Receptors, Angiotensin/metabolism
- Receptors, Cell Surface/metabolism
- Receptors, G-Protein-Coupled
- Receptors, Lysophosphatidic Acid
- Signal Transduction/physiology
- Transcriptional Activation/physiology
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Affiliation(s)
- Laure Voisin
- Institut de recherches cliniques de Montréal, Montreal H2W 1R7, Canada
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22
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Olschewski H, Olschewski A, Rose F, Schermuly R, Schütte H, Weissmann N, Seeger W, Grimminger F. Physiologic basis for the treatment of pulmonary hypertension. THE JOURNAL OF LABORATORY AND CLINICAL MEDICINE 2001; 138:287-97. [PMID: 11709653 DOI: 10.1067/mlc.2001.119329] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- H Olschewski
- Medical Clinic II, Justus-Liebig-University, Giessen, Germany
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23
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Orlov SN, Taurin S, Tremblay J, Hamet P. Inhibition of Na+,K+ pump affects nucleic acid synthesis and smooth muscle cell proliferation via elevation of the [Na+]i/[K+]i ratio: possible implication in vascular remodelling. J Hypertens 2001; 19:1559-65. [PMID: 11564975 DOI: 10.1097/00004872-200109000-00007] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Na+,K+ pump inhibition is known to delay the development of apoptosis in vascular smooth muscle cells (VSMC). This study examines Na+,K+ pump involvement in the regulation of VSMC macromolecular synthesis and proliferation. METHODS DNA, RNA and protein synthesis in VSMC from the rat aorta was studied by the incorporation of [3H]-labelled thymidine, uridine and leucine. Cell cycle progression was estimated by flow cytometry. Intracellular Na+ and K+ content and Na+,K+ pump activity were quantified as the steady-state distribution of 22Na and 86Rb and the rate of ouabain-sensitive 86Rb uptake in Na+-loaded cells, respectively. RESULTS Ouabain inhibited the Na+,K+ pump with a Ki of 0.1 mmol/l. At concentrations less than 0.1 mmol/l, neither [Na+]i nor [K+]i was affected by ouabain; elevation of ouabain concentration sharply increased the [Na+]i/[K+]i ratio with a K0.5 of approximately 0.3 mmol/l. At concentrations higher than 0.1 mmol/l, ouabain time- and dose-dependently activated RNA and DNA syntheses in serum-deprived VSMC and inhibited cell cycle progression triggered by serum. In quiescent VSMC, ouabain did not affect protein synthesis, total cell number, but slightly increased the percentage of cells in the S-phase (4.25 versus 1.46%) and attenuated cell death assessed by staining with trypan blue and lactate dehydrogenase release. CONCLUSIONS Elevation of the [Na+]i/[K+]i ratio caused by Na+,K+ pump inhibition markedly enhances nucleic acid synthesis in quiescent VSMC and blocks cell cycle progression in serum-supplied VSMC. The relative contribution of this phenomenon as well as the anti-apoptotic action of increased [Na+]i/[K+]i ratio to vascular remodelling under augmented content of endogenous Na+,K+ pump inhibitors, seen in volume-expanded hypertension, should be investigated by in-vivo studies.
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Affiliation(s)
- S N Orlov
- Centre de recherche, Centre hospitalier de l'Université de Montréal, Hôtel-Dieu, Montréal, Québec, Canada
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24
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Thorin-Trescases N, Orlov SN, Taurin S, Dulin NO, Allen BG, deBlois D, Tremblay J, Pshezhetsky AV, Hamet P. Antiproliferative effect of brief exposure to cholera toxin in vascular smooth muscle cells: role of cAMP and protein kinase A. Can J Physiol Pharmacol 2001. [DOI: 10.1139/y01-017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The effect of cholera toxin (CTX), an activator of the adenylate cyclase-coupled G protein αS subunit, was studied on cultured vascular smooth muscle cell (VSMC) proliferation. Continuous exposure (48 h) to CTX as well as 2-min pretreatment of VSMC with CTX led to the same level of cAMP production, inhibition of DNA synthesis, and arrest in the G1 phase without induction of necrosis or apoptosis in VSMC. Protein kinase A (PKA) activity in CTX-pretreated cells was transiently elevated by 3-fold after 3 h of incubation, whereas after 48 h it was reduced by 2-fold compared with baseline values without modulation of the expression of its catalytic α subunit. The PKA inhibitors H89 and KT 5720 did not protect VSMC from the antiproliferative effect of CTX. Two-dimensional electrophoresis was used to analyze the influence of CTX on protein phosphorylation. After 3 h of incubation of CTX-pretreated cells, we observed both newly-phosphorylated and dephosphorylated proteins (77 and 50 protein species, respectively). After 24 h of incubation, the number of phosphorylated proteins in CTX-treated cells was decreased to 39, whereas the number of dephosphorylated proteins was increased to 106. In conclusion, brief exposure to CTX leads to full-scale activation of cAMP signaling and evokes VSMC arrest in the G1 phase.Key words: vascular smooth muscle, proliferation, cholera toxin, cAMP, protein kinase A.
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25
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Sachinidis A, Seul C, Gouni-Berthold I, Seewald S, Ko Y, Vetter H, Fingerle J, Hoppe J. Cholera toxin treatment of vascular smooth muscle cells decreases smooth muscle alpha-actin content and abolishes the platelet-derived growth factor-BB-stimulated DNA synthesis. Br J Pharmacol 2000; 130:1561-70. [PMID: 10928958 PMCID: PMC1572234 DOI: 10.1038/sj.bjp.0703480] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2000] [Revised: 04/11/2000] [Accepted: 05/12/2000] [Indexed: 11/08/2022] Open
Abstract
The second messenger cyclic AMP regulates diverse biological processes such as cell morphology and cell growth. We examined the role of the second messenger cyclic AMP on rat aortic vascular smooth muscle cell (VSMC) morphology and the intracellular transduction pathway mediated by platelet-derived growth factor beta-receptor (PDGF-Rbeta). The effect of PDGF-BB on VSMCs growth was assessed by [(3)H]-thymidine incorporation. Tyrosine phosphorylation of PDGF-Rbeta, PLC-gamma1, ERK1 and ERK2, p125(FAK) and paxillin as well as Sm alpha-actin was examined by the chemiluminescence Western blotting method. Actin mRNA level was quantitated by Northern blotting. Visualization of Sm alpha-actin filaments, paxillin and PDGF-Rbeta was performed by immunfluorescence microscopy. Cholera toxin (CTX; 10 nM) treatment lead to a large and sustained increase in the cyclic AMP concentration after 2 h which correlated with change of VSMC morphology including complete disruption of the Sm alpha-actin filament array and loss of focal adhesions. Treatment of VSMCs with CTX did not influence tyrosine phosphorylation of p125(FAK) and paxillin but decreased the content of a Sm alpha-actin protein. Maximal decrease of 70% was observed after 24 h of treatment. CTX also caused a 90% decrease of the actin mRNA level. CTX treatment completely abolished PDGF-BB stimulated DNA-synthesis although PDGF-Rbeta level and subcellular distribution and translocation was not altered. Furthermore CTX attenuated the PDGF-BB-induced tyrosine phosphorylation of the PDGF-Rbeta, PI 3'-K, PLC-gamma1 and ERK1/2 indicating an action of cyclic AMP on PDGF-beta receptor. We conclude that although cyclic AMP attenuates the PDGF-Rbeta mediated intracellular transduction pathway, an intact actin filament may be required for the PDGF-BB-induced DNA synthesis in VSMCs.
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Affiliation(s)
- A Sachinidis
- Medizinische Universitäts-Poliklinik, Weilhelmstr. 35-37, D-53111 Bonn, Germany.
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26
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Werstiuk ES, Lee RMKW. Vascular β-adrenoceptor function in hypertension and in ageing. Can J Physiol Pharmacol 2000. [DOI: 10.1139/y00-015] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Functional β-adrenoceptors (β-AR) have been identified and characterized in blood vessels under in vivo conditions as well as in vascular smooth muscle cells (SMC) grown in culture. Agonist occupancy of β-AR activates adenylyl cyclase (AC) via the stimulatory guanine nucleotide-binding protein (Gs) and leads to elevations in intracellular adenosine 3',5'-cyclic monophosphate levels (cAMP). Increased cAMP activates the cAMP-dependent protein kinase (PKA), with subsequent phosphorylation of various target proteins. This β-AR pathway interacts with several other intracellular signalling pathways via cross-talk, so that activation by β-AR agonists may also modulate other second messengers and protein kinases. SMC β-AR play an important role in SMC function. In intact blood vessels they mediate SMC relaxation by various intracellular mechanisms, ultimately causing a decrease in intracellular Ca2+ levels. In cultured SMC, activation of the β-AR pathway results in inhibition of cellular proliferation, the development of SMC polyploidy, and SMC apoptosis. Blood vessels from hypertensive animals are characterized by an increase in SMC cell mass, a greater incidence of SMC polyploidy in the aorta, and an impairment in the β-agonist-mediated SMC relaxation. Some of these changes may result from an attenuation of β-AR function due to agonist-induced receptor desensitization caused by the uncoupling of receptors from the Gs-AC system. The phosphorylated β-AR may in turn trigger new signals and activate different intracellular pathways. However, the details of these mechanisms are still unresolved. Since functional β-AR play such a prominent and multi-faceted role in SMC function, it is important to understand how these diverse physiological effects are mediated by this receptor system, and how they contribute to the development of hypertension. With ageing, a decrease in β-AR-Gs-AC coupling is observed, and this is implicated in the reduced responsiveness of SMC. The similarities in SMC β-AR functional changes in hypertension and in ageing suggest that the underlying mechanisms are also analogous.Key words: smooth muscle, β-adrenoceptors, cyclic AMP, protein kinase A, cell proliferation, polyploidy, relaxation, apoptosis, hypertension, ageing.
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27
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Orlov SN, Taurin S, Thorin-Trescases N, Dulin NO, Tremblay J, Hamet P. Inversion of the intracellular Na(+)/K(+) ratio blocks apoptosis in vascular smooth muscle cells by induction of RNA synthesis. Hypertension 2000; 35:1062-8. [PMID: 10818065 DOI: 10.1161/01.hyp.35.5.1062] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This study examines the involvement of RNA and protein synthesis in the modulation of apoptosis in vascular smooth muscle cells (VSMC) by intracellular monovalent cations. In VSMC transfected with E1A adenovirus (VSMC-E1A), inversion of the [Na(+)](i)/[K(+)](i) ratio by an inhibitor of the Na(+),K(+) pump, ouabain, prevented the development of apoptosis triggered by serum withdrawal. Inhibition of apoptosis by ouabain was abolished by inhibitors of RNA and protein synthesis, actinomycin D, and cycloheximide, respectively. In VSMC-E1A, incubation with ouabain for 4 and 24 hours augmented RNA synthesis by 20% to 50% and 3-fold to 4-fold, respectively. In quiescent VSMC, the effect of ouabain and serum on RNA synthesis was additive. Ouabain did not affect the level of phosphorylation of ERK, JNK, and p38 MAP kinases and blocked apoptosis independent of the presence of the MAPK kinase inhibitors PD98059 and SB 202190. Equimolar substitution of NaCl with KCl in the incubation medium abolished the effect of ouabain on intracellular Na(+) and K(+) concentration, apoptosis, and RNA synthesis. Thus, our results demonstrate that the antiapoptotic effect of the inverted [Na(+)](i)/[K(+)](i) ratio is mediated by MAPK-independent induction of de novo synthesis of RNA species encoding inhibitor(s) of programmed cell death.
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Affiliation(s)
- S N Orlov
- Centre de Recherché du CHUM, Campus Hotel-Dieu, University of Montreal, Montreal, PQ, Canada.
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28
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Servant MJ, Coulombe P, Turgeon B, Meloche S. Differential regulation of p27(Kip1) expression by mitogenic and hypertrophic factors: Involvement of transcriptional and posttranscriptional mechanisms. J Cell Biol 2000; 148:543-56. [PMID: 10662779 PMCID: PMC2174813 DOI: 10.1083/jcb.148.3.543] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/1999] [Accepted: 12/29/1999] [Indexed: 12/19/2022] Open
Abstract
Platelet-derived growth factor-BB (PDGF-BB) acts as a full mitogen for cultured aortic smooth muscle cells (SMC), promoting DNA synthesis and cell proliferation. In contrast, angiotensin II (Ang II) induces cellular hypertrophy as a result of increased protein synthesis, but is unable to drive cells into S phase. In an effort to understand the molecular basis for this differential growth response, we have examined the downstream effects of PDGF-BB and Ang II on regulators of the cell cycle machinery in rat aortic SMC. Both PDGF-BB and Ang II were found to stimulate the accumulation of G(1) cyclins with similar kinetics. In addition, little difference was observed in the expression level of their catalytic partners, Cdk4 and Cdk2. However, while both factors increased the enzymatic activity of Cdk4, only PDGF-BB stimulated Cdk2 activity in late G(1) phase. The lack of activation of Cdk2 in Ang II-treated cells was causally related to the failure of Ang II to stimulate phosphorylation of the enzyme on threonine and to downregulate p27(Kip1) expression. By contrast, exposure to PDGF-BB resulted in a progressive and dramatic reduction in the level of p27(Kip1) protein. The time course of p27(Kip1) decline was correlated with a reduced rate of synthesis and an increased rate of degradation of the protein. Importantly, the repression of p27(Kip1) synthesis by PDGF-BB was associated with a marked attenuation of Kip1 gene transcription and a corresponding decrease in Kip1 mRNA accumulation. We also show that the failure of Ang II to promote S phase entry is not related to the autocrine production of transforming growth factor-beta1 by aortic SMC. These results identify p27(Kip1) as an important regulator of the phenotypic response of vascular SMC to mitogenic and hypertrophic stimuli.
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Affiliation(s)
- Marc J. Servant
- Research Centre, Centre hospitalier de l'Université de Montréal and Department of Pharmacology, University of Montreal, Montreal, Quebec, H2W 1T8 Canada
| | - Philippe Coulombe
- Research Centre, Centre hospitalier de l'Université de Montréal and Department of Pharmacology, University of Montreal, Montreal, Quebec, H2W 1T8 Canada
| | - Benjamin Turgeon
- Research Centre, Centre hospitalier de l'Université de Montréal and Department of Pharmacology, University of Montreal, Montreal, Quebec, H2W 1T8 Canada
| | - Sylvain Meloche
- Research Centre, Centre hospitalier de l'Université de Montréal and Department of Pharmacology, University of Montreal, Montreal, Quebec, H2W 1T8 Canada
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29
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Hou M, Pantev E, Möller S, Erlinge D, Edvinsson L. Angiotensin II type 1 receptors stimulate protein synthesis in human cardiac fibroblasts via a Ca2+-sensitive PKC-dependent tyrosine kinase pathway. ACTA PHYSIOLOGICA SCANDINAVICA 2000; 168:301-9. [PMID: 10712568 DOI: 10.1046/j.1365-201x.2000.00684.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The aim of the present study was to investigate the proliferative effects of Ang II in human cardiac fibroblasts. The effects of Ang II in human cardiac fibroblasts on the 3H-thymidine incorporation, the cell number, the 3H-leucine incorporation and the total protein content were measured. The expression of receptor mRNA was performed by reverse transcription-polymerase chain reaction (RT-PCR). Ang II increased 3H-leucine incorporation in a concentration-dependent manner but not 3H-thymidine incorporation in primary cultures of human cardiac fibroblasts. The maximum effect (24 +/- 3% over control) was obtained at a concentration of 10 nM. There were no significant alterations of cell number or total protein content, suggesting that Ang II stimulated protein synthesis but did not induce hypertrophy. The accumulation of 3H-leucine was blocked by the AT1 receptor antagonist candesartan but not by the AT2 receptor antagonist PD123319. By using RT-PCR, both AT1 and AT2 receptors mRNA were found to be expressed in human cardiac fibroblasts. The selective MAPKK inhibitor PD098059, the protein kinase C inhibitor K252a or the phospholipase C inhibitor U73122 did not significantly inhibit Ang II augmented 3H-leucine incorporation. However, this was significantly blocked by the Ca2+-dependent protein kinase C inhibitor GO6976, the non-selective protein kinase inhibitor staurosporine and the tyrosine kinase inhibitor tyrphostin 25. The effects of Ang II were unaffected by the Gi-protein blocker pertussis toxin, indicating a Gi-protein-independent pathway. Ang II was synergistic with insulin but showed no significant increase on 3H-leucine incorporation when combined with PDGF or EGF. In summary, Ang II stimulates protein synthesis through AT1 receptors in human cardiac fibroblasts, but has no hypertrophic or hyperplastic effect. The response is mediated by a MAPKK-independent and Ca2+-sensitive PKC-dependent pathway.
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Affiliation(s)
- M Hou
- Division of Experimental Vascular Research, Department of Internal Medicine, Lund University Hospital, Lund, Sweden
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30
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Wang XQ, Lindberg FP, Frazier WA. Integrin-associated protein stimulates alpha2beta1-dependent chemotaxis via Gi-mediated inhibition of adenylate cyclase and extracellular-regulated kinases. J Cell Biol 1999; 147:389-400. [PMID: 10525543 PMCID: PMC2174227 DOI: 10.1083/jcb.147.2.389] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Integrin-associated protein (IAP/CD47) augments the function of alpha2beta1 integrin in smooth muscle cells (SMC), resulting in enhanced chemotaxis toward soluble collagen (Wang, X-Q., and W.A. Frazier. 1998. Mol. Biol. Cell. 9:865). IAP-deficient SMC derived from IAP(-/-) animals did not migrate in response to 4N1K (KRFYVVMWKK), a peptide agonist of IAP derived from the COOH-terminal domain of thrombospondin-1 (TSP1). When normal SMC were preincubated with 4N1K or an anti-alpha2beta1 function-stimulating antibody, cell migration to soluble collagen was significantly enhanced. 4N1K-induced chemotaxis was blocked by treatment of SMC with pertussis toxin indicating that IAP acts through Gi. In agreement with this, 4N1K evoked a rapid decrease in cAMP levels which was intensified in the presence of collagen, and forskolin and 8-Br-cAMP both inhibited SMC migration stimulated via IAP. 4N1K strongly inhibited extracellular regulated kinase (ERK) activation in SMC attaching to collagen and reduced basal ERK activity in suspended SMC. Pertussis toxin treatment of SMC significantly activated ERK, suggesting that an inhibitory input was alleviated. Inhibition of ERK activity by (a) the MAP kinase kinase (MEK) inhibitor, PD98059, (b) antisense oligonucleotide depletion of ERK, and (c) expression of mitogen-activated protein (MAP) kinase phosphatase-1 in SMC all led to increased migration to collagen, 4N1K, or 4N1K plus collagen. Thus, IAP stimulates alpha2beta1 integrin-mediated SMC migration via Gi-mediated inhibition of ERK activity and suppression of cyclic AMP levels. Both of these signaling pathways could directly modulate the state of the integrin as well as impact downstream components of the cell motility apparatus.
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Affiliation(s)
- Xue-Qing Wang
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Frederik P. Lindberg
- Department of Infectious Diseases, Washington University School of Medicine, St. Louis, Missouri 63110
| | - William A. Frazier
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110
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31
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Bornfeldt KE, Krebs EG. Crosstalk between protein kinase A and growth factor receptor signaling pathways in arterial smooth muscle. Cell Signal 1999; 11:465-77. [PMID: 10405757 DOI: 10.1016/s0898-6568(99)00020-0] [Citation(s) in RCA: 92] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Crosstalk between the cyclic AMP-dependent protein kinase (PKA) and growth factor receptor signaling is one of many emerging concepts of crosstalk in signal transduction. Understanding of PKA crosstalk may have important implications for studies of crosstalk between other, less well known, signaling pathways. This review focuses on PKA crosstalk in arterial smooth muscle. Proliferation and migration of arterial smooth muscle cells (SMCs) contribute to the thickening of the blood vessel wall that occurs in many types of cardiovascular disease. PKA potently inhibits SMC proliferation by antagonizing the major mitogenic signaling pathways induced by growth factors in SMCs. PKA also inhibits growth factor-induced SMC migration. An intricate crosstalk between PKA and the mitogen-activated protein kinase (MAPK/ERK) pathway, the p70 S6 kinase pathway and cyclin-dependent kinases has been described. Further, PKA regulates expression of growth regulatory molecules. The result of PKA activation in SMCs is the potent inhibition of cell cycle traverse and SMC migration. In this review, we discuss recent advances in our understanding of the crosstalk between PKA and signaling pathways induced by growth factor receptors in SMCs, and where relevant, in other cell types in which interesting examples of PKA crosstalk have been described.
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Affiliation(s)
- K E Bornfeldt
- Department of Pathology, University of Washington, Seattle 98195-7470, USA.
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Sabri A, Govindarajan G, Griffin TM, Byron KL, Samarel AM, Lucchesi PA. Calcium- and protein kinase C-dependent activation of the tyrosine kinase PYK2 by angiotensin II in vascular smooth muscle. Circ Res 1998; 83:841-51. [PMID: 9776731 DOI: 10.1161/01.res.83.8.841] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Angiotensin II (Ang II) induces vascular smooth muscle cell (VSMC) growth by activating Gq-protein-coupled AT1 receptors, which leads to elevation of cytosolic Ca2+ ([Ca2+]i) and activation of protein kinase C (PKC) and mitogen-activated protein kinases. To assess the link between these Ang II-induced signaling events, we examined the effect of Ang II on the proline-rich tyrosine kinase (PYK2), previously found to be activated by a variety of stimuli that increase [Ca2+]i or activate PKC. PYK2 distribution was demonstrated in rat aortic tissue and in cultured VSMC by immunohistochemistry, revealing a cytosolic distribution distinct from smooth muscle alpha-actin, focal adhesion kinase, or paxillin. The involvement of PYK2 in Ang II signaling was measured by immunoprecipitation and immune complex kinase assays. Treatment of quiescent VSMC with Ang II resulted in a concentration- and time-dependent increase in PYK2 tyrosine phosphorylation and kinase activity in PYK2 immunoprecipitates. PYK2 phosphorylation was inhibited by AT1 receptor blockade and was attenuated by downregulation of PKC or the chelation of [Ca2+]i. Treatment with either phorbol ester or Ca2+ ionophore also increased PYK2 phosphorylation, suggesting that PKC activation and/or increased [Ca2+]i are both necessary and sufficient to activate PYK2. Activation of PYK2 by Ang II was also associated with increased PYK2-src complex formation, suggesting that PYK2 activation represents a potential link between Ang II-stimulated [Ca2+]i and PKC activation with downstream signaling events such as mitogen-activated protein kinase activation involved in the regulation of VSMC growth.
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MESH Headings
- Actins/analysis
- Angiotensin II/pharmacology
- Animals
- Anti-Arrhythmia Agents/pharmacology
- Aorta/cytology
- Calcium/pharmacology
- Cell Adhesion Molecules/analysis
- Cells, Cultured
- Enzyme Activation/drug effects
- Focal Adhesion Kinase 1
- Focal Adhesion Kinase 2
- Focal Adhesion Protein-Tyrosine Kinases
- Imidazoles/pharmacology
- Losartan/pharmacology
- Male
- Muscle, Smooth, Vascular/chemistry
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/enzymology
- Phosphorylation
- Protein Kinase C/metabolism
- Protein-Tyrosine Kinases/analysis
- Protein-Tyrosine Kinases/metabolism
- Pyridines/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Receptor, Insulin/analysis
- Receptors, Angiotensin/metabolism
- Tyrosine/metabolism
- src-Family Kinases/metabolism
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Affiliation(s)
- A Sabri
- Department of Physiology and the Cardiovascular Institute, Department of Medicine, Loyola University Chicago, Maywood IL, USA. Maywood, Ill
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de Gasparo M, Levens N. Does blockade of angiotensin II receptors offer clinical benefits over inhibition of angiotensin-converting enzyme? PHARMACOLOGY & TOXICOLOGY 1998; 82:257-71. [PMID: 9677617 DOI: 10.1111/j.1600-0773.1998.tb01572.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Angiotensin AT1 receptor antagonists represent a new class of drugs for the treatment of hypertension. They are specific for the renin-angiotensin system, selective for the angiotensin AT1 receptor, and act independently of the angiotensin II synthetic pathway. Blockade of the renin-angiotensin system at the receptor level should therefore be more complete. The high circulating levels of angiotensin II following angiotensin AT1 receptor blockade could be beneficial in stimulating other unblocked angiotensin receptors, especially the AT2 receptor. It has been proposed that the angiotensin AT2 receptor, which is re-expressed or up-regulated during pathological circumstances, counterbalances the effect of the stimulation of the angiotensin AT1 receptor. Through this mechanism, angiotensin AT1 antagonists may be superior to ACE inhibitors in cardiac and vascular remodelling as well as in kidney insufficiency. Long-term trials are required to demonstrate the possible clinical superiority of this new class of antihypertensive agents.
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