1
|
Zhang DM, Lin YF. Functional modulation of sarcolemmal K ATP channels by atrial natriuretic peptide-elicited intracellular signaling in adult rabbit ventricular cardiomyocytes. Am J Physiol Cell Physiol 2020; 319:C194-C207. [PMID: 32432931 DOI: 10.1152/ajpcell.00409.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
ATP-sensitive potassium (KATP) channels couple cell metabolic status to membrane excitability and are crucial for stress adaptation and cytoprotection in the heart. Atrial natriuretic peptide (ANP), a cardiac peptide important for cardiovascular homeostasis, also exhibits cytoprotective features including protection against myocardial ischemia-reperfusion injuries. However, how ANP modulates cardiac KATP channels is largely unknown. In the present study we sought to address this issue by investigating the role of ANP signaling in functional modulation of sarcolemmal KATP (sarcKATP) channels in ventricular myocytes freshly isolated from adult rabbit hearts. Single-channel recordings were performed in combination with pharmacological approaches in the cell-attached patch configuration. Bath application of ANP markedly potentiated sarcKATP channel activities induced by metabolic inhibition with sodium azide, whereas the KATP-stimulating effect of ANP was abrogated by selective inhibition of the natriuretic peptide receptor type A (NPR-A), cGMP-dependent protein kinase (PKG), reactive oxygen species (ROS), extracellular signal-regulated protein kinase (ERK)1/2, Ca2+/calmodulin-dependent protein kinase II (CaMKII), or the ryanodine receptor (RyR). Blockade of RyRs also nullified hydrogen peroxide (H2O2)-induced stimulation of sarcKATP channels in intact cells. Furthermore, single-channel kinetic analyses revealed that ANP enhanced the function of ventricular sarcKATP channels through destabilizing the long closures and facilitating the opening transitions, without affecting the single-channel conductance. In conclusion, here we report that ANP positively modulates the activity of ventricular sarcKATP channels via an intracellular signaling mechanism consisting of NPR-A, PKG, ROS, ERK1/2, CaMKII, and RyR2. This novel mechanism may regulate cardiac excitability and contribute to cytoprotection, in part, by opening myocardial KATP channels.
Collapse
Affiliation(s)
- Dai-Min Zhang
- Department of Physiology and Membrane Biology, University of California, Davis, California
| | - Yu-Fung Lin
- Department of Physiology and Membrane Biology, University of California, Davis, California.,Department of Anesthesiology and Pain Medicine, University of California, Davis, California
| |
Collapse
|
2
|
Liu Z, Zhou Z, Wang L, Dong W, Qiu L, Song L. The cholinergic immune regulation mediated by a novel muscarinic acetylcholine receptor through TNF pathway in oyster Crassostrea gigas. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2016; 65:139-148. [PMID: 27394930 DOI: 10.1016/j.dci.2016.07.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 07/03/2016] [Accepted: 07/04/2016] [Indexed: 06/06/2023]
Abstract
Muscarinic receptors, which selectively take muscarine as their ligand, are critical for the immunological and physiological processes in animals. In the present study, the open region frame (ORF) of a homologue of muscarinic acetylcholine (ACh) receptor (mAChR) was amplified from oyster Crassostrea gigas (named as CgmAChR-1), whose full length was 1983 bp and the protein it encoded contained 660 amino acids with a seven transmembrane region. Phylogeny analysis suggested that CgmAChR-1 shared homology with M5 muscarinic receptor found in invertebrates including Habropoda laboriosa, Acromyrmex echinatior and Echinococcus granulosus. After cell transfection of CgmAChR-1 into HEK293T cells and ACh incubation, the level of intracellular Ca(2+) and cAMP increased significantly (p < 0.05). Such trend could be reverted with the addition of M3 and M5 muscarinic receptor antagonists DAMP and DAR. The CgmAChR-1 transcripts were ubiquitously detectable in seven different tissues with the maximal expression level in adductor muscle. When the oysters received LPS stimulation, CgmAChR-1 mRNA expression in haemocyte was increased to the highest level (6.05-fold, p < 0.05) at 24 h, while blocking CgmAChR-1 using receptor antagonists before LPS stimulation promoted the expression of oyster TNF, resulting in the increase of haemocyte apoptosis index. These results suggested that CgmAChR-1 was the key molecule in cholinergic neuroendocrine-immune system contributing to the regulation of TNF expression and apoptosis process.
Collapse
Affiliation(s)
- Zhaoqun Liu
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhi Zhou
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Lingling Wang
- Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian, 116023, China.
| | - Wenjing Dong
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Limei Qiu
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
| | - Linsheng Song
- Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian, 116023, China.
| |
Collapse
|
3
|
The simple neuroendocrine-immune regulatory network in oyster Crassostrea gigas mediates complex functions. Sci Rep 2016; 6:26396. [PMID: 27193598 PMCID: PMC4872224 DOI: 10.1038/srep26396] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 04/29/2016] [Indexed: 01/01/2023] Open
Abstract
The neuroendocrine-immune (NEI) regulatory network is a complex system, which plays an indispensable role in the immunity of the host. In the present study, the bioinformatical analysis of the transcriptomic data from oyster Crassostrea gigas and further biological validation revealed that oyster TNF (CgTNF-1 CGI_10018786) could activate the transcription factors NF-κB and HSF (heat shock transcription factor) through MAPK signaling pathway, and then regulate apoptosis, redox reaction, neuro-regulation and protein folding in oyster haemocytes. The activated immune cells then released neurotransmitters including acetylcholine, norepinephrine and [Met(5)]-enkephalin to regulate the immune response by arising the expression of three TNF (CGI_10005109, CGI_10005110 and CGI_10006440) and translocating two NF-κB (Cgp65, CGI_10018142 and CgRel, CGI_10021567) between the cytoplasm and nuclei of haemocytes. Neurotransmitters exhibited the immunomodulation effects by influencing apoptosis and phagocytosis of oyster haemocytes. Acetylcholine and norepinephrine could down-regulate the immune response, while [Met(5)]-enkephalin up-regulate the immune response. These results suggested that the simple neuroendocrine-immune regulatory network in oyster might be activated by oyster TNF and then regulate the immune response by virtue of neurotransmitters, cytokines and transcription factors.
Collapse
|
4
|
Zholobenko A, Modriansky M. Silymarin and its constituents in cardiac preconditioning. Fitoterapia 2014; 97:122-32. [DOI: 10.1016/j.fitote.2014.05.016] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 05/21/2014] [Accepted: 05/22/2014] [Indexed: 01/28/2023]
|
5
|
Shi X, Wang L, Zhou Z, Liu R, Li Y, Song L. Acetylcholine modulates the immune response in Zhikong scallop Chlamys farreri. FISH & SHELLFISH IMMUNOLOGY 2014; 38:204-210. [PMID: 24680755 DOI: 10.1016/j.fsi.2014.03.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2013] [Revised: 02/19/2014] [Accepted: 03/07/2014] [Indexed: 06/03/2023]
Abstract
Acetylcholine (ACh) is an indispensable neurotransmitter and neuromodulator in the cholinergic nervous system and it is implicated in the dynamic modulation of immune response in vertebrates. Although ACh has also been identified in most invertebrates, the knowledge about its immunomodulation is still limited. In the present study, the immunoreactivities of ACh and acetylcholinesterase (AChE) were observed in all the tested tissues of scallop Chlamys farreri, including adductor muscle, mantle, gill, hepatopancreas, kidney and gonad. The ACh concentration in the supernate of scallop hemolymph increased from 11.59 ± 0.27 to 14.36 ± 0.17 μM L(-1) at 6 h after LPS (0.5 mg ml(-1)) stimulation, and increased to 15.51 ± 1.20 μM L(-1) at 3 h after the stimulation of tumor necrosis factor alpha (TNF-α) (50 ng ml(-1)). After LPS stimulation, the mRNA expression levels of superoxide dismutase (CfSOD), catalase (CfCAT) and lysozyme (CfLYZ) in hemocytes increased significantly at 3 h (P < 0.05), 6 h (P < 0.05) and 12 h (P < 0.05), respectively. Compared with the LPS treatment, the induction of CfSOD, CfCAT and CfLYZ expression in hemocytes was repressed effectively (P < 0.05) by the co-stimulation of LPS and ACh (5 × 10(-7) M) at 3 h (P < 0.05), 6 h (P < 0.05) and 12 h (P < 0.05), respectively. Furthermore, the expression level of CfCAT in hemocytes increased significantly after 12 h by the co-stimulation with LPS and ACh (P < 0.05). These results indicated collectively that the scallop cholinergic nervous system could be activated by immune stimulations, and it might play an essential role in immunomodulation of scallops.
Collapse
Affiliation(s)
- Xiaowei Shi
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; College of Physical Education, Linyi University, Linyi 276000, China
| | - Lingling Wang
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Zhi Zhou
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Rui Liu
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Yunchen Li
- College of Physical Education, Linyi University, Linyi 276000, China
| | - Linsheng Song
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
| |
Collapse
|
6
|
Chen XM, Wang NN, Zhang TY, Wang F, Wu CF, Yang JY. Neuroprotection by sildenafil: neuronal networks potentiation in acute experimental stroke. CNS Neurosci Ther 2013; 20:40-9. [PMID: 24034153 DOI: 10.1111/cns.12162] [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] [Received: 03/04/2013] [Revised: 07/02/2013] [Accepted: 07/13/2013] [Indexed: 12/24/2022] Open
Abstract
AIMS Sildenafil, a phosphodiesterase type 5 inhibitor, has been found to produce functional recovery in ischemic rats by increasing the cGMP level and triggering neurogenesis. The aim of this study was to investigate further sildenafil mechanisms. METHODS Male Sprague-Dawley rats underwent middle cerebral artery occlusion and reperfusion, followed by intraperitoneal or intravenous treatment of sildenafil starting 2 h later. Behavioral tests were performed on day 1 or day 7 after reperfusion, while cerebral infarction, edema, Nissl staining, Fluoro-Jade B staining, and electron microscopy studies were carried out 24 h poststroke. The cGMP-dependent Nogo-66 receptor (Nogo-R) pathway, synaptophysin, PSD-95/neuronal nitric oxide synthases (nNOS), brain-derived neurotrophic factor (BDNF)/tropomyosin-related kinase B (TrkB), and nerve growth factor (NGF)/tropomyosin-related kinase A (TrkA) were measured. RESULTS Sildenafil enhanced neurological recovery and inhibited infarction, even following delayed administration 4 h after stroke onset. Furthermore, sildenafil reduced the loss of neurons and modulated the expressions of the cGMP-dependent Nogo-R pathway. Moreover, sildenafil protected the structure of synapses and mediated the expressions of synaptophysin, PSD-95/nNOS, BDNF/TrkB, and NGF/TrkA. CONCLUSIONS Sildenafil produces significant neuroprotective effects on injured neurons in acute stroke, and these are mediated by the cGMP-dependent Nogo-R pathway, NGF/TrkA, and BDNF/TrkB.
Collapse
Affiliation(s)
- Xue-Mei Chen
- Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang, China
| | | | | | | | | | | |
Collapse
|
7
|
Gambaryan S, Butt E, Kobsar A, Geiger J, Rukoyatkina N, Parnova R, Nikolaev VO, Walter U. The oligopeptide DT-2 is a specific PKG I inhibitor only in vitro, not in living cells. Br J Pharmacol 2013; 167:826-38. [PMID: 22612416 DOI: 10.1111/j.1476-5381.2012.02044.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND AND PURPOSE cGMP is involved in the regulation of many cellular processes including cardiac and smooth muscle contractility, aldosterone synthesis and inhibition of platelet activation. Intracellular effects cGMP are mediated by cGMP-dependent PKs, cGMP-regulated PDEs and cGMP-gated ion channels. PKG inhibitors are widely used to discriminate PKG-specific effects. They can be divided into cyclic nucleotide-binding site inhibitors such as Rp-phosphorothioate analogues (Rp-cGMPS), ATP-binding site inhibitors such as KT5823, and substrate binding site inhibitors represented by the recently described DT-oligopeptides. As it has been shown that Rp-cGMPS and KT5823 have numerous non-specific effects, we analysed the pharmacological properties of the oligopeptide (D)-DT-2 described as a highly specific, membrane-permeable, PKG inhibitor. EXPERIMENTAL APPROACH Specificity and potency of (D)-DT-2 to inhibit PKG activity was evaluated using biochemical assays in vitro and by substrate phosphorylation analysis in various cell types including human platelets, rat mesangial cells and rat neonatal cardiomyocytes. KEY RESULTS Despite potent inhibition of PKGI in vitro, (D)-DT-2 lost specificity for PKG in cell homogenates and particularly in living cells, as demonstrated by phosphorylation of different substrates. Instead, (D)-DT-2 modulated activity of other kinases including ERK, p38, PKB and PKC, thereby inducing unpredicted and often opposing functional effects. CONCLUSIONS AND IMPLICATIONS We conclude that DT-oligopeptides, as other inhibitors, cannot be used to specifically inhibit PKG in intact cells. Therefore, no specific pharmacological PKG inhibitors are available, and reliable studies of PKG signalling can only be made by using RNA knockdown or genetic deletion methods.
Collapse
Affiliation(s)
- Stepan Gambaryan
- Institute of Clinical Biochemistry and Pathobiochemistry, University of Wuerzburg, Wuerzburg, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
8
|
Madhani M, Hall AR, Cuello F, Charles RL, Burgoyne JR, Fuller W, Hobbs AJ, Shattock MJ, Eaton P. Phospholemman Ser69 phosphorylation contributes to sildenafil-induced cardioprotection against reperfusion injury. Am J Physiol Heart Circ Physiol 2010; 299:H827-36. [PMID: 20543084 PMCID: PMC2944484 DOI: 10.1152/ajpheart.00129.2010] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The phosphodiesterase type-5 inhibitor sildenafil has powerful cardioprotective effects against ischemia-reperfusion injury. PKG-mediated signaling has been implicated in this protection, although the mechanism and the downstream targets of this kinase remain to be fully elucidated. In this study we assessed the role of phospholemman (PLM) phosphorylation, which activates the Na+/K+-ATPase, in cardioprotection afforded by sildenafil administered during reperfusion. Isolated perfused mouse hearts were optimally protected against infarction (indexed by tetrazolium staining) by 0.1 μM sildenafil treatment during the first 10 min of reperfusion. Extended sildenafil treatment (30, 60, or 120 min at reperfusion) did not alter the degree of protection provided. This protection was PKG dependent, since it was blocked by KT-5823. Western blot analysis using phosphospecific antibodies to PLM showed that sildenafil at reperfusion did not modulate PLM Ser63 or Ser68 phosphorylation but significantly increased Ser69 phosphorylation. The treatment of isolated rat ventricular myocytes with sildenafil or 8-bromo-cGMP (PKG agonist) enhanced PLM Ser69 phosphorylation, which was bisindolylmaleimide (PKC inhibitor) sensitive. Patch-clamp studies showed that sildenafil treatment also activated the Na+/K+-ATPase, which is anticipated in light of PLM Ser69 phosphorylation. Na+/K+-ATPase activation during reperfusion would attenuate Na+ overload at this time, providing a molecular explanation of how sildenafil guards against injury at this time. Indeed, using flame photometry and rubidium uptake into isolated mouse hearts, we found that sildenafil enhanced Na+/K+-ATPase activity during reperfusion. In this study we provide a molecular explanation of how sildenafil guards against myocardial injury during postischemic reperfusion.
Collapse
Affiliation(s)
- Melanie Madhani
- Cardiovascular Division, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, United Kingdom
| | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Botha P, MacGowan GA, Dark JH. Sildenafil Citrate Augments Myocardial Protection in Heart Transplantation. Transplantation 2010; 89:169-77. [DOI: 10.1097/tp.0b013e3181c42b22] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
10
|
Sadat U. Signaling pathways of cardioprotective ischemic preconditioning. Int J Surg 2009; 7:490-8. [PMID: 19540944 DOI: 10.1016/j.ijsu.2009.06.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2009] [Revised: 06/10/2009] [Accepted: 06/11/2009] [Indexed: 12/26/2022]
Abstract
BACKGROUND Ischemia/reperfusion (I/R) injury is a major contributory factor to cardiac dysfunction and infarct size that determines patient prognosis after acute myocardial infarction. During the last 20 years, since the appearance of the first publication on ischemic preconditioning (IP), our knowledge of this phenomenon has increased exponentially. RESULTS AND CONCLUSION Basic scientific experiments and preliminary clinical trials in humans suggest that IP confers resistance to subsequent sustained ischemic insults not only in the regional tissue but also in distant organs (remote ischemic preconditioning), which may provide a simple, cost-effective means of reducing the risk of perioperative myocardial ischemia. The mechanism may be humoral, neural, or a combination of both, and involves adenosine, bradykinin, protein kinases and K(ATP) channels, although the precise end-effector remains unclear. This review describes different signaling pathways involved in acute ischemic preconditioning in detail.
Collapse
Affiliation(s)
- Umar Sadat
- Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
| |
Collapse
|
11
|
Pinkse MWH, Rijkers DTS, Dostmann WR, Heck AJR. Mode of action of cGMP-dependent protein kinase-specific inhibitors probed by photoaffinity cross-linking mass spectrometry. J Biol Chem 2009; 284:16354-16368. [PMID: 19369251 DOI: 10.1074/jbc.m808521200] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The inhibitor peptide DT-2 (YGRKKRRQRRRPPLRKKKKKH) is the most potent and selective inhibitor of the cGMP-dependent protein kinase (PKG) known today. DT-2 is a construct of a PKG tight binding sequence (W45, LRKKKKKH, KI=0.8 microM) and a membrane translocating sequence (DT-6, YGRKKRRQRRRPP, KI=1.1 microM), that combined strongly inhibits PKG catalyzed phosphorylation (KI=12.5 nM) with approximately 1000-fold selectivity toward PKG over protein kinase A, the closest relative of PKG. However, the molecular mechanism behind this inhibition is not entirely understood. Using a combination of photoaffinity labeling, stable isotope labeling, and mass spectrometry, we have located the binding sites of PKG-specific substrate and inhibitor peptides. Covalent linkage of a PKG-specific substrate analogue was localized in the catalytic core on residues 356-372, also known as the glycine-rich loop, essential for ATP binding. By analogy, the individual inhibitor peptides W45 and DT-6 were also found to cross-link near the glycine-rich loop, suggesting these are both substrate competitive inhibitors. A bifunctional photoreactive analogue of DT-2 was found to generate dimers of PKG. This cross-linking induced covalent PKG dimerization was not observed for an N-terminal deletion mutant of PKG, which lacks the dimerization domain. In addition, non-covalent mass spectrometry was used to determine binding stoichiometry and binding order of the inhibitor peptides. Dimeric PKG binds two W45 and DT-6 peptides, whereas only one DT-2 molecule was observed to bind to the dimeric PKG. Taken together, these findings imply that (i) the two individual components making up DT-2 are both targeted against the substrate-binding site and (ii) binding of a single DT-2 molecule inactivates both PKG monomers simultaneously, which is an indication that (iii) in cGMP-activated PKG the catalytic centers of both subunits may be in each other's proximity.
Collapse
Affiliation(s)
- Martijn W H Pinkse
- From the Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Sorbonnnelaan 16, Utrecht 3584 CA, The Netherlands; Department of Biotechnology, Delft, University of Technology, Delft 2628 BC, The Netherlands
| | - Dirk T S Rijkers
- Medicinal Chemistry and Chemical Biology, Utrecht Institute for Pharmaceutical Sciences, Department of Pharmaceutical Sciences, Faculty of Science, Utrecht University, Utrecht 3584 CA, The Netherlands
| | - Wolfgang R Dostmann
- Department of Pharmacology, College of Medicine, University of Vermont, Burlington, Vermont 05405
| | - Albert J R Heck
- From the Biomolecular Mass Spectrometry and Proteomics Group, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Sorbonnnelaan 16, Utrecht 3584 CA, The Netherlands.
| |
Collapse
|
12
|
Abstract
The first cGMP-dependent protein kinase (PKG) modulators were described nearly 30 years ago and since then more than 200 compounds have been synthesized and tested, but only a small subset of these compounds has found widespread application. The aim of this review is to suggest a framework for evaluating and using PKG activators and inhibitors and to explore and interpret PKG signal transduction in cell culture-based model systems. Therefore, cross-reactivity of cGMP-analogs with other classes of cyclic nucleotide binding proteins, as well as the advantages and problems of newly designed PKG inhibitors, are discussed. Additional information and a search option are available at www.cyclic-nucleotides.org
Collapse
|
13
|
Garlid KD, Costa ADT, Quinlan CL, Pierre SV, Dos Santos P. Cardioprotective signaling to mitochondria. J Mol Cell Cardiol 2008; 46:858-66. [PMID: 19118560 DOI: 10.1016/j.yjmcc.2008.11.019] [Citation(s) in RCA: 156] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Revised: 11/07/2008] [Accepted: 11/26/2008] [Indexed: 01/05/2023]
Abstract
Mitochondria are central players in the pathophysiology of ischemia-reperfusion. Activation of plasma membrane G-coupled receptors or the Na,K-ATPase triggers cytosolic signaling pathways that result in cardioprotection. Our working hypothesis is that the occupied receptors migrate to caveolae, where signaling enzymes are scaffolded into signalosomes that bud off the plasma membrane and migrate to mitochondria. The signalosome-mitochondria interaction then initiates intramitochondrial signaling by opening the mitochondrial ATP-sensitive K(+) channel (mitoK(ATP)). MitoK(ATP) opening causes an increase in ROS production, which activates mitochondrial protein kinase C epsilon (PKCvarepsilon), which inhibits the mitochondrial permeability transition (MPT), thus decreasing cell death. We review the experimental findings that bear on these hypotheses and other modes of protection involving mitochondria.
Collapse
Affiliation(s)
- Keith D Garlid
- Department of Biology, Portland State University, Portland, OR 97201-0751, USA.
| | | | | | | | | |
Collapse
|
14
|
Das A, Xi L, Kukreja RC. Protein kinase G-dependent cardioprotective mechanism of phosphodiesterase-5 inhibition involves phosphorylation of ERK and GSK3beta. J Biol Chem 2008; 283:29572-85. [PMID: 18723505 DOI: 10.1074/jbc.m801547200] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sildenafil, a potent inhibitor of phosphodiesterase-5 (PDE-5) induces powerful protection against myocardial ischemia-reperfusion injury. PDE-5 inhibition increases cGMP levels that activate cGMP-dependent protein kinase (PKG). However, the cause and effect relationship of PKG in sildenafil-induced cardioprotection and the downstream targets of PKG remain unclear. Adult ventricular myocytes were treated with sildenafil and subjected to simulated ischemia and reoxygenation. Sildenafil treatment significantly decreased cardiomyocyte necrosis and apoptosis. The PKG inhibitors, KT5823, guanosine 3',5'-cyclic monophosphorothioate, 8-(4-chloro-phenylthio) (R(p)-8-pCPT-cGMPs), or DT-2 blocked the anti-necrotic and anti-apoptotic effect of sildenafil. Selective knockdown of PKG in cardiomyocytes with adenoviral vector containing short hairpin RNA of PKG also abolished sildenafil-induced protection. Furthermore, intra-coronary infusion of sildenafil in Langendorff-isolated mouse hearts prior to ischemia-reperfusion significantly reduced myocardial infarct size after 20 min ischemia and 30 min reperfusion, which was abrogated by KT5823. Sildenafil significantly increased PKG activity in intact hearts and cardiomyocytes. Sildenafil also enhanced the Bcl-2/Bax ratio, phosphorylation of Akt, ERK1/2, and glycogen synthase kinase 3beta. All these changes (except Akt phosphorylation) were significantly blocked by KT5823 and short hairpin RNA of PKG. These studies provide the first evidence for an essential role of PKG in sildenafil-induced cardioprotection. Moreover, our results demonstrate that sildenafil activates a PKG-dependent novel signaling cascade that involves activation of ERK and inhibition of glycogen synthase kinase 3beta leading to cytoprotection.
Collapse
Affiliation(s)
- Anindita Das
- Division of Cardiology, Department of Internal Medicine, Virginia Commonwealth University, Richmond, Virginia 23298, USA
| | | | | |
Collapse
|
15
|
Maas O, Donat U, Frenzel M, Rütz T, Kroemer HK, Felix SB, Krieg T. Vardenafil protects isolated rat hearts at reperfusion dependent on GC and PKG. Br J Pharmacol 2008; 154:25-31. [PMID: 18332860 DOI: 10.1038/bjp.2008.71] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE The type-5 PDE inhibitor vardenafil reduces myocardial infarct size in situ, following ischemia/reperfusion, when applied at reperfusion in animal models. Little is known about the underlying protective signaling. Here, we test whether vardenafil is protective in rat isolated hearts and in a cell model of calcium stress. EXPERIMENTAL APPROACH Infarct size in rat isolated hearts was measured after a 30 min regional ischemia and 120 min reperfusion. Vardenafil (1 nM-1 microM) was infused during reperfusion. HL-1 cardiomyocytes were loaded with tetramethylrhodamine ethyl ester (TMRE), a fluorescent marker of mitochondrial membrane potential (psi m). KEY RESULTS Vardenafil at reperfusion reduced infarct size as percentage of the ischemic zone from 45.8+/-2.0% in control hearts to 26.2+/-2.7% (P<0.001) only at 10 nM, whereas higher or lower dosages failed to protect. This protective effect was blocked by co-administration of either the GC inhibitor, 1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one (ODQ), or the PKG inhibitor, KT-5823. HL-1 cardiomyocytes, loaded with TMRE, were treated for 80 min with the calcium ionophore, calcimycin, to induce calcium stress. This reduced the mean cell fluorescence to 63.3 +/- 3.8% of baseline values and vardenafil protected against this fall (78.6 +/- 3.6%, P<0.01). The vardenafil-induced protection of HL-1 cells was blocked by ODQ, KT-5823 or the PKG-inhibiting peptides DT-2 and DT-3, confirming a role for GC and PKG. CONCLUSIONS AND IMPLICATIONS These results further support the hypothesis that PDE-5 inhibitors are protective in ischemic hearts, in addition to their known clinical effects in the treatment of erectile dysfunction in men.
Collapse
Affiliation(s)
- O Maas
- Department of Cardiology, Ernst-Moritz-Arndt University, Greifswald, Germany
| | | | | | | | | | | | | |
Collapse
|
16
|
Helmig S, Schuckenböhmer P, Heger J, Euler G, Piper HM, Schlüter KD. Direct effects of the angiotensin-converting enzyme inhibitor ramiprilat on adult rat ventricular cardiomyocytes. Acta Physiol (Oxf) 2007; 191:267-74. [PMID: 17825088 DOI: 10.1111/j.1748-1716.2007.01738.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
AIM Angiotensin-converting enzyme (ACE) inhibitors like ramiprilat bind to ACE expressed on the cell surface of endothelial cells and induce cell-specific signalling including the activation of activator protein (AP)-1. The present study addressed the question whether ramiprilat exerts a similar effect on adult ventricular cardiomyocytes, i.e. activates the AP-1 or modifies contractile performance. It was further aimed to decide whether such effects depend on bradykinin receptors or whether they are directly mediated via ACE. METHODS Adult rat ventricular cardiomyocytes were isolated and cultured. mRNA expression of ACE was investigated by RT-PCR, AP-1 activation by gel mobility shift assays, and cardiac contractile performance by electrical pacing of isolated cells and analysis of cell shortening via a line-camera. RESULTS Cardiomyocytes stably express ACE. Ramiprilat increased maximal contraction velocity and shortened the time-to-peak of contraction. In contrast to effects evoked by bradykinin, such effects caused by ramiprilat were not attenuated by HOE 140, a bradykinin-receptor antagonist. These effects were also not attenuated in the presence of l-nitro-arginine, used to mimic bradykinin-dependent signalling. In cardiomyocytes, bradykinin but not ramiprilat activated AP-1. Ramiprilat activates AP-1 in endothelial cells that are known to respond to ramiprilat in this way. CONCLUSION Ramiprilat exerts direct, bradykinin-receptor independent effects on cardiomyocytes that improve cellular function without a corresponding effect on AP-1 activation or induction of AP-1 dependent effects. This newly described effect of ramiprilat may contribute to the protective effects seen by application of ACE inhibitors.
Collapse
Affiliation(s)
- S Helmig
- Justus-Liebig-Universität GieSSen, Physiologisches Institut, GieSSen, Germany
| | | | | | | | | | | |
Collapse
|
17
|
p38-MAPK is involved in restoration of the lost protection of preconditioning by nicorandil in vivo. Eur J Pharmacol 2007; 579:289-97. [PMID: 18031732 DOI: 10.1016/j.ejphar.2007.10.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2007] [Revised: 10/12/2007] [Accepted: 10/18/2007] [Indexed: 11/20/2022]
Abstract
Nicorandil, a selective mitochondrial K(ATP) channel opener, reinstates the waned protection after multiple cycles of preconditioning. In this study, we determined the signal transduction activated in heart after 3 or 8 cycles of preconditioning and prolonged ischemia in rabbits treated with placebo or nicorandil. In a first series (eight groups) we evaluated the (%) infarct to risk ratio after 30 min ischemia/3 h reperfusion and in a second series (six groups), we assessed the intracellular levels of cyclic GMP (c-GMP), protein kinase C (PKC) activity and p38-mitogen activated protein kinase (p38-MAPK) phosphorylation from heart samples taken during the long ischemia. Cardioprotection by 3 cycles of preconditioning (11.7+/-3.8% vs 45.9+/-5.2% in the control, P<0.001) was lost after 8 cycles (43.9+/-5.1%, P=NS vs control). Nicorandil restored it to the levels of classic preconditioning (13.7+/-2.4% vs 40.8+/-3.5% in respective controls, P<0.001). This was reversed by the p38-MAPK inhibitor SB203580 (48.8+/-5.1%) which had no protective effect in the control group (44.6+/-5.8%). In the placebo-treated rabbits, intracellular c-GMP and PKC were increased only in the group subjected to 3 cycles of preconditioning. Despite that nicorandil equalizes the intracellular levels of c-GMP, PKC and activated p38-MAPK at the long ischemia, specific alterations of p38-MAPK phosphorylation differentiate the protected groups. Our data delineate the signal transduction mechanism mediating the beneficial effect of nicorandil and imply that the recapture of the lost protection is due to a dynamic process of the intracellular mediators accompanied by an increase in p38-MAPK phosphorylation and not to an instantaneous event.
Collapse
|
18
|
Goswami SK, Maulik N, Das DK. Ischemia-reperfusion and cardioprotection: a delicate balance between reactive oxygen species generation and redox homeostasis. Ann Med 2007; 39:275-89. [PMID: 17558599 DOI: 10.1080/07853890701374677] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Ischemia-reperfusion injury of the myocardium has long been a subject of intense research. Cardiac preconditioning, an associated phenomenon, has also been critically investigated over the past two decades. Although the biochemistry of ischemia-reperfusion and its association with oxidative metabolism has long been established, recent studies have further revealed a more intricate role of a number of reactive oxygen-nitrogen species in those processes. Emerging evidence suggests that an elaborate network of enzymes (and other biomolecules) dedicated to the generation, utilization, and diminution of reactive oxygen-nitrogen species maintains the redox homeostasis in the myocardium, and any perturbation of its status has distinctive effects. It thus appears that while excessive generation of reactive species leads to cellular injury, their regulated generation may cause transient and reversible modifications of cellular proteins leading the transmission of intracellular signals with specific effects. Taken together, generation of reactive oxygen-nitrogen species in the myocardium plays a nodal role in mediating both ischemic injury and cardioprotection.
Collapse
Affiliation(s)
- Shyamal K Goswami
- Cardiovascular Research Center, University of Connecticut School of Medicine, Farmington, CT 06030-1110, USA
| | | | | |
Collapse
|
19
|
Pasdois P, Quinlan CL, Rissa A, Tariosse L, Vinassa B, Costa ADT, Pierre SV, Dos Santos P, Garlid KD. Ouabain protects rat hearts against ischemia-reperfusion injury via pathway involving src kinase, mitoKATP, and ROS. Am J Physiol Heart Circ Physiol 2006; 292:H1470-8. [PMID: 17098831 DOI: 10.1152/ajpheart.00877.2006] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We showed recently that mitochondrial ATP-dependent K(+) channel (mitoK(ATP)) opening is required for the inotropic response to ouabain. Because mitoK(ATP) opening is also required for most forms of cardioprotection, we investigated whether exposure to ouabain was cardioprotective. We also began to map the signaling pathways linking ouabain binding to Na(+)-K(+)-ATPase with the opening of mitoK(ATP). In Langendorff-perfused rat hearts, 10-80 microM ouabain given before the onset of ischemia resulted in cardioprotection against ischemia-reperfusion injury, as documented by an improved recovery of contractile function and a reduction of infarct size. In skinned cardiac fibers, a ouabain-induced protection of mitochondrial outer membrane integrity, adenine nucleotide compartmentation, and energy transfer efficiency was evidenced by a decreased release of cytochrome c and preserved half-saturation constant of respiration for ADP and adenine nucleotide translocase-mitochondrial creatine kinase coupling, respectively. Ouabain-induced positive inotropy was dose dependent over the range studied, whereas ouabain-induced cardioprotection was maximal at the lowest dose tested. Compared with bradykinin (BK)-induced preconditioning, ouabain was equally efficient. However, the two ligands clearly diverge in the intracellular steps leading to mitoK(ATP) opening from their respective receptors. Thus BK-induced cardioprotection was blocked by inhibitors of cGMP-dependent protein kinase (PKG) or guanylyl cyclase (GC), whereas ouabain-induced protection was not blocked by either agent. Interestingly, however, ouabain-induced inotropy appears to require PKG and GC. Thus 5-hydroxydecanoate (a selective mitoK(ATP) inhibitor), N-(2-mercaptopropionyl)glycine (MPG; a reactive oxygen species scavenger), ODQ (a GC inhibitor), PP2 (a src kinase inhibitor), and KT-5823 (a PKG inhibitor) abolished preconditioning by BK and blocked the inotropic response to ouabain. However, only PP2, 5-HD, and MPG blocked ouabain-induced cardioprotection.
Collapse
Affiliation(s)
- Philippe Pasdois
- Institut National de la Santé et de la Recherche, Médicale U441, University Victor Segalen-Bordeaux 2, University Hospital of Bordeaux, Bordeaux, France
| | | | | | | | | | | | | | | | | |
Collapse
|
20
|
Rhoden CR, Wellenius GA, Ghelfi E, Lawrence J, González-Flecha B. PM-induced cardiac oxidative stress and dysfunction are mediated by autonomic stimulation. Biochim Biophys Acta Gen Subj 2005; 1725:305-13. [PMID: 16005153 DOI: 10.1016/j.bbagen.2005.05.025] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2005] [Revised: 05/19/2005] [Accepted: 05/24/2005] [Indexed: 11/22/2022]
Abstract
Epidemiological studies show that increases in particulate air pollution (PM) are associated with increases in cardiopulmonary morbidity and mortality. However, the mechanism(s) underlying the cardiac effects of PM remain unknown. We used pharmacological strategies to determine whether oxidants are implicated in PM-dependent cardiac dysfunction and whether PM-induced increase in autonomic stimulation on the heart mediates cardiac oxidative stress and toxicity. Adult Sprague-Dawley rats were exposed to either intratracheal instillation of urban air particles (UAP 750 microg) or to inhalation of concentrated ambient particles (CAPs mass concentration 700+/-180 microg/m3) for 5 h. Oxidative stress and cardiac function were evaluated 30 min after UAP instillation or immediately after exposure to CAPs. Instillation of UAP led to significant increases in heart oxidants measured as organ chemiluminescence (UAP: 38+/-5 cps/cm2, sham: 10+/-1 cps/cm2) or thiobarbituric acid reactive substances (TBARS, UAP: 76+/-10, Sham 30+/-6 pmol/mg protein). Heart rate increased immediately after exposure (UAP: 390+/-20 bpm, sham: 350+/-10 bpm) and returned to basal levels over the next 30 min. Heart rate variability (SDNN) was unchanged immediately after exposure, but significantly increased during the recovery phase (UAP: 3.4+/-0.2, Sham: 2.4+/-0.3). To determine the role of ROS in the development of cardiac malfunction, rats were treated with 50 mg/kg N-acetylcysteine (NAC) 1 h prior to UAP instillation or CAPs inhalation. NAC prevented changes in heart rate and SDNN in UAP-exposed rats (340+/-8 and 2.9+/-0.3, respectively). To investigate the role of the autonomic nervous system in PM-induced oxidative stress, rats were given 5 mg/kg atenolol (beta-1 receptor antagonist), 0.30 mg/kg glycopyrrolate (muscarinic receptor antagonist) or saline immediately before exposure to CAPs aerosols. Both atenolol and glycopyrrolate effectively prevented CAPs-induced cardiac oxidative stress (CL(ATEN): 11+/-1 cps/cm2, CL(GLYCO): 10+/-1 cps/cm2, TBARS(ATEN): 40+/-6 pmol/mg protein, TBARS(GLYCO): 38+/-6 pmol/mg protein). These data indicate that PM exposure increases cardiac oxidants via autonomic signals and the resulting oxidative stress is associated with significant functional alterations in the heart.
Collapse
Affiliation(s)
- Claudia R Rhoden
- Department of Environmental Health, Physiology Program, Harvard School of Public Health, Boston, MA 02115, USA
| | | | | | | | | |
Collapse
|