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Cai Y, Ying F, Liu H, Ge L, Song E, Wang L, Zhang D, Hoi Ching Tang E, Xia Z, Irwin MG. Deletion of Rap1 protects against myocardial ischemia/reperfusion injury through suppressing cell apoptosis via activation of STAT3 signaling. FASEB J 2020; 34:4482-4496. [PMID: 32020680 DOI: 10.1096/fj.201901592rr] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 12/28/2019] [Accepted: 01/14/2020] [Indexed: 12/21/2022]
Abstract
Ischemic heart disease is a leading cause of morbidity and mortality. Repressor activator protein 1 (Rap1), an established telomere-associated protein, is a novel modulator of hypoxia-induced apoptosis. This study aimed to explore the potential direct role of Rap1 in myocardial ischemia/reperfusion injury (I/RI) and to determine the underlying molecular mechanism. In a mouse model of myocardial I/RI (30-min of left descending coronary artery ligation followed by 2-h reperfusion), Rap1 deficiency significantly reduced myocardial infarct size (IS) and improved cardiac systolic/diastolic function. This was associated with a reduction in apoptosis in the post-ischemic myocardium. In H9C2 and primary cardiomyocytes, Rap1 knockdown or knockout significantly suppressed hypoxia/reoxygenation (H/R)-induced cell injury and apoptosis through increasing the phosphorylation/activation of STAT3 at site Ser727 and translocation of STAT3 to the nucleus. We surmise this since Stattic (selective STAT3 inhibitor) pretreatment canceled the abovementioned protective effect. Furthermore, co-immunoprecipitation assay revealed a direct interaction between Rap1 and STAT3, but not JAK2, suggesting that the association of Rap1 with STAT3 may contribute to the reduced activity of STAT3 (Ser727 ) upon H/R stimulation. In conclusion, Rap1 deficiency protects the heart from ischemic damage through STAT3-dependent reduction of cardiomyocyte apoptosis, which may yield viable target for pharmacological intervention in ischemic heart disease.
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Affiliation(s)
- Yin Cai
- Department of Anaesthesiology, The University of Hong Kong, Hong Kong SAR, China
| | - Fan Ying
- Department of Anaesthesiology, The University of Hong Kong, Hong Kong SAR, China
| | - Hao Liu
- Department of Anaesthesiology, The University of Hong Kong, Hong Kong SAR, China.,Department of Cardiology, Guangzhou Institute of Cardiovascular Disease, The Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Liang Ge
- Department of Anesthesiology, The First Hospital, Jilin University, Changchun, China
| | - Erfei Song
- The First Affiliated Hospital, Jinan University, Guangzhou, China
| | - Lin Wang
- Department of Anaesthesiology, The University of Hong Kong, Hong Kong SAR, China
| | - Dengwen Zhang
- Department of Anesthesiology, Guangdong Cardiovascular Institute, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong, China
| | - Eva Hoi Ching Tang
- Department of Pharmacology and Pharmacy and School of Biomedical Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Zhengyuan Xia
- Department of Anaesthesiology, The University of Hong Kong, Hong Kong SAR, China
| | - Michael G Irwin
- Department of Anaesthesiology, The University of Hong Kong, Hong Kong SAR, China
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Reperfusion Therapy with Rapamycin Attenuates Myocardial Infarction through Activation of AKT and ERK. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:4619720. [PMID: 28373901 PMCID: PMC5360974 DOI: 10.1155/2017/4619720] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 01/26/2017] [Accepted: 02/14/2017] [Indexed: 01/04/2023]
Abstract
Prompt coronary reperfusion is the gold standard for minimizing injury following acute myocardial infarction. Rapamycin, mammalian target of Rapamycin (mTOR) inhibitor, exerts preconditioning-like cardioprotective effects against ischemia/reperfusion (I/R) injury. We hypothesized that Rapamycin, given at the onset of reperfusion, reduces myocardial infarct size through modulation of mTOR complexes. Adult C57 male mice were subjected to 30 min of myocardial ischemia followed by reperfusion for 1 hour/24 hours. Rapamycin (0.25 mg/kg) or DMSO (7.5%) was injected intracardially at the onset of reperfusion. Post-I/R survival (87%) and cardiac function (fractional shortening, FS: 28.63 ± 3.01%) were improved in Rapamycin-treated mice compared to DMSO (survival: 63%, FS: 17.4 ± 2.6%). Rapamycin caused significant reduction in myocardial infarct size (IS: 26.2 ± 2.2%) and apoptosis (2.87 ± 0.64%) as compared to DMSO-treated mice (IS: 47.0 ± 2.3%; apoptosis: 7.39 ± 0.81%). Rapamycin induced phosphorylation of AKT S473 (target of mTORC2) but abolished ribosomal protein S6 phosphorylation (target of mTORC1) after I/R. Rapamycin induced phosphorylation of ERK1/2 but inhibited p38 phosphorylation. Infarct-limiting effect of Rapamycin was abolished with ERK inhibitor, PD98059. Rapamycin also attenuated Bax and increased Bcl-2/Bax ratio. These results suggest that reperfusion therapy with Rapamycin protects the heart against I/R injury by selective activation of mTORC2 and ERK with concurrent inhibition of mTORC1 and p38.
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Relevance of mouse models of cardiac fibrosis and hypertrophy in cardiac research. Mol Cell Biochem 2016; 424:123-145. [PMID: 27766529 DOI: 10.1007/s11010-016-2849-0] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 10/14/2016] [Indexed: 01/15/2023]
Abstract
Heart disease causing cardiac cell death due to ischemia-reperfusion injury is a major cause of morbidity and mortality in the United States. Coronary heart disease and cardiomyopathies are the major cause for congestive heart failure, and thrombosis of the coronary arteries is the most common cause of myocardial infarction. Cardiac injury is followed by post-injury cardiac remodeling or fibrosis. Cardiac fibrosis is characterized by net accumulation of extracellular matrix proteins in the cardiac interstitium and results in both systolic and diastolic dysfunctions. It has been suggested by both experimental and clinical evidence that fibrotic changes in the heart are reversible. Hence, it is vital to understand the mechanism involved in the initiation, progression, and resolution of cardiac fibrosis to design anti-fibrotic treatment modalities. Animal models are of great importance for cardiovascular research studies. With the developing research field, the choice of selecting an animal model for the proposed research study is crucial for its outcome and translational purpose. Compared to large animal models for cardiac research, the mouse model is preferred by many investigators because of genetic manipulations and easier handling. This critical review is focused to provide insight to young researchers about the various mouse models, advantages and disadvantages, and their use in research pertaining to cardiac fibrosis and hypertrophy.
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Martin ED, Bassi R, Marber MS. p38 MAPK in cardioprotection - are we there yet? Br J Pharmacol 2015; 172:2101-13. [PMID: 25204838 PMCID: PMC4386984 DOI: 10.1111/bph.12901] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 08/22/2014] [Accepted: 08/28/2014] [Indexed: 12/14/2022] Open
Abstract
PKs transfer a phosphate from ATP to the side-chain hydroxyl group of a serine, threonine or tyrosine residue of a substrate protein. This in turn can alter that protein's function; modulating fundamental cellular processes including, metabolism, transcription, growth, division, differentiation, motility and survival. PKs are subdivided into families based on homology. One such group are the stress-activated kinases, which as the name suggests, are activated in response to cellular stresses such as toxins, cytokines, mechanical deformation and osmotic stress. Members include the p38 MAPK family, which is composed of α, β, γ and δ, isoforms which are encoded by separate genes. These kinases transduce extracellular signals and coordinate the cellular responses needed for adaptation and survival. However, in cardiovascular and other disease states, these same systems can trigger maladaptive responses that aggravate, rather than alleviate, the disease. This situation is analogous to adrenergic, angiotensin and aldosterone signalling in heart failure, where inhibition is beneficial despite the importance of these hormones to homeostasis. The question is whether similar benefits could accrue from p38 inhibition? In this review, we will discuss the structure and function of p38, the history of p38 inhibitors and their use in preclinical studies. Finally, we will summarize the results of recent cardiovascular clinical trials with p38 inhibitors.
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Affiliation(s)
- E D Martin
- King's College London BHF Centre of Research Excellence, Cardiovascular Division, The Rayne Institute, St Thomas' HospitalLondon, UK
| | - R Bassi
- King's College London BHF Centre of Research Excellence, Cardiovascular Division, The Rayne Institute, St Thomas' HospitalLondon, UK
| | - M S Marber
- King's College London BHF Centre of Research Excellence, Cardiovascular Division, The Rayne Institute, St Thomas' HospitalLondon, UK
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Mitra A, Ray A, Datta R, Sengupta S, Sarkar S. Cardioprotective Role of P38 MAPK During Myocardial Infarction Via Parallel Activation of α-Crystallin B and Nrf2. J Cell Physiol 2014; 229:1272-82. [DOI: 10.1002/jcp.24565] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 01/22/2014] [Indexed: 01/25/2023]
Affiliation(s)
- Arkadeep Mitra
- Genetics and Molecular Cardiology Laboratory; Department of Zoology; University of Calcutta; Kolkata India
| | - Aramita Ray
- Genetics and Molecular Cardiology Laboratory; Department of Zoology; University of Calcutta; Kolkata India
| | - Ritwik Datta
- Genetics and Molecular Cardiology Laboratory; Department of Zoology; University of Calcutta; Kolkata India
| | - Shantanu Sengupta
- Genomics and Molecular Medicine Unit; CSIR-Institute of Genomics and Integrative Biology; New Delhi India
| | - Sagartirtha Sarkar
- Genetics and Molecular Cardiology Laboratory; Department of Zoology; University of Calcutta; Kolkata India
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Inhibition of p38 MAPK During Ischemia, But Not Reperfusion, Effectively Attenuates Fatal Arrhythmia in Ischemia/Reperfusion Heart. J Cardiovasc Pharmacol 2013; 61:133-41. [DOI: 10.1097/fjc.0b013e318279b7b1] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Kumphune S, Chattipakorn S, Chattipakorn N. Role of p38 inhibition in cardiac ischemia/reperfusion injury. Eur J Clin Pharmacol 2011; 68:513-24. [PMID: 22205273 DOI: 10.1007/s00228-011-1193-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Accepted: 11/29/2011] [Indexed: 10/14/2022]
Abstract
The p38 mitogen-activated protein kinases (p38s) are Ser/Thr kinases that are activated as a result of cellular stresses and various pathological conditions, including myocardial ischemia/reperfusion. p38 activation has been shown to accentuate myocardial injury and impair cardiac function. Inhibition of p38 activation and its activity has been proposed to be cardioprotective by slowing the rate of myocardial damage and improving cardiac function. The growing body of evidence on the use of p38 inhibitors as therapeutic means for responding to heart problems is controversial, since both beneficial as well as a lack of protective effects on the heart have been reported. In this review, the outcomes from studies investigating the effect of p38 inhibitors on the heart in a wide range of study models, including in vitro, ex vivo, and in vivo models, are discussed. The correlations of experimental models with practical clinical usefulness, as well as the need for future studies regarding the use of p38 inhibitors, are also addressed.
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Affiliation(s)
- Sarawut Kumphune
- Department of Medical Technology, Faculty of Allied Health Sciences, Naresuan University, Phitsanulok 65000, Thailand
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Marber MS, Rose B, Wang Y. The p38 mitogen-activated protein kinase pathway--a potential target for intervention in infarction, hypertrophy, and heart failure. J Mol Cell Cardiol 2010; 51:485-90. [PMID: 21062627 DOI: 10.1016/j.yjmcc.2010.10.021] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2010] [Revised: 10/19/2010] [Accepted: 10/19/2010] [Indexed: 12/20/2022]
Abstract
The p38 mitogen-activated protein kinases (p38s) are stress-activated Ser/Thr kinases. Their activation has been associated with various pathological stressors in the heart. Activated p38 is implicated in a wide spectrum of cardiac pathologies, including hypertrophy, myocardial infarction, as well as systolic and diastolic heart failure. In this review, the specific contribution of different isoforms of p38 kinases to cardiac diseases as well as TAB-1-mediated non-canonical activation pathway are discussed as a rationale for inhibiting p38 activity to treat cardiac hypertrophy, ischemic injury, and heart failure. Finally, a summary of current clinical trials targeting p38 kinases in cardiovascular diseases is provided to highlight the potential promise as well as existing challenges of this therapeutic approach. This article is part of a special issue entitled "Key Signaling Molecules in Hypertrophy and Heart Failure."
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Affiliation(s)
- Michael S Marber
- King's College London BHF Centre, Cardiovascular Division, The Rayne Institute, St. Thomas' Hospital, London SE1 7EH, United Kingdom.
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Zhao P, Wang J, He L, Ma H, Zhang X, Zhu X, Dolence EK, Ren J, Li J. Deficiency in TLR4 signal transduction ameliorates cardiac injury and cardiomyocyte contractile dysfunction during ischemia. J Cell Mol Med 2009; 13:1513-25. [PMID: 19508385 PMCID: PMC3828863 DOI: 10.1111/j.1582-4934.2009.00798.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Toll-like receptor 4 (TLR4), a proximal signalling receptor in innate immune responses to lipopolysaccharide of gram-negative pathogens, is expressed in the heart. Accumulating evidence have consolidated the notion that TLR4 plays an essential role in the pathogenesis of cardiac dysfunction. However, the molecular mechanisms of TLR4 responsible for ischemia-induced cardiac dysfunction remain unclear. To address the signalling mechanisms of TLR4-deficiency cardioprotection against ischemic injury, in vivo regional ischemia was induced by occlusion of the left anterior descending coronary artery in wild-type (WT) C3H/HeN and TLR4-mutated C3H/HeJ mice. The results demonstrated that blunted ischemic activation of p38 mitogen-activated protein kinase and JNK signalling occurred in C3H/HeJ hearts versus C3H/HeN hearts, while ERK and AMP-activated protein kinase (AMPK) signalling pathways were augmented during ischemia in C3H/HeJ hearts versus C3H/HeN hearts. Intriguingly, ischemia-stimulated endoplasmic reticulum stress was higher in C3H/HeN hearts than that in C3H/HeJ as demonstrated by up-regulation of Grp78/BiP, Gadd153/CHOP and IRE-1α. Myocardial infarct, caspase-3 activity and terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) staining demonstrated that C3H/HeN hearts suffered more damage than those of C3H/HeJ hearts during ischemia. Moreover, isolated cardiomyocytes from C3H/HeJ hearts showed resistance to hypoxia-induced contractile dysfunction compared to those from C3H/HeN hearts, which are associated with greater hypoxic activation of AMPK and ERK signalling, better intracellular Ca2+ handling in C3H/HeJ versus C3H/HeN cardiomyocytes. These findings suggest that the cardioprotective effects against ischemic injury of hearts with deficiency in TLR4 signalling may be mediated through modulating AMPK and ERK signalling pathway during ischemia.
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Affiliation(s)
- Peng Zhao
- Department of Cardiology, Shandong Provincial Hospital, Shandong University, Jinan, China
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Jacquet S, Nishino Y, Kumphune S, Sicard P, Clark JE, Kobayashi KS, Flavell RA, Eickhoff J, Cotten M, Marber MS. The role of RIP2 in p38 MAPK activation in the stressed heart. J Biol Chem 2008; 283:11964-71. [PMID: 18310079 DOI: 10.1074/jbc.m707750200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The activation of p38 MAPK by dual phosphorylation aggravates myocardial ischemic injury and depresses cardiac contractile function. SB203580, an ATP-competitive inhibitor of p38 MAPK and other kinases, prevents this dual phosphorylation during ischemia. Studies in non-cardiac tissue have shown receptor-interacting protein 2 (RIP2) lies upstream of p38 MAPK, is SB203580-sensitive and ischemia-responsive, and aggravates ischemic injury. We therefore examined the RIP2-p38 MAPK signaling axis in the heart. Adenovirus-driven expression of wild-type RIP2 in adult rat ventricular myocytes caused robust, SB203580-sensitive dual phosphorylation of p38 MAPK associated with activation of p38 MAPK kinases MKK3, MKK4, and MKK6. The effect of SB203580 was recapitulated by unrelated inhibitors of RIP2 or the downstream MAPK kinase kinase, TAK1. However, overexpression of wild-type, kinase-dead, caspase recruitment domain-deleted, or kinase-dead and caspase recruitment domain-deleted forms of RIP2 had no effect on the activating dual phosphorylation of p38 MAPK during simulated ischemia. Similarly, p38 MAPK activation and myocardial infarction size in response to true ischemia did not differ between hearts from wild-type and RIP2 null mice. However, both p38 MAPK activation and the contractile depression caused by the endotoxin component muramyl dipeptide were attenuated by SB203580 and in RIP2 null hearts. Although RIP2 can cause myocardial p38 MAPK dual phosphorylation in the heart under some circumstances, it is not responsible for the SB203580-sensitive pattern of activation during ischemia.
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Affiliation(s)
- Sebastien Jacquet
- Cardiovascular Division, King's College London, The Rayne Institute, St. Thomas' Hospital, London SE1 7EH, United Kingdom
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Clark JE, Sarafraz N, Marber MS. Potential of p38-MAPK inhibitors in the treatment of ischaemic heart disease. Pharmacol Ther 2007; 116:192-206. [PMID: 17765316 DOI: 10.1016/j.pharmthera.2007.06.013] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Accepted: 06/14/2007] [Indexed: 11/25/2022]
Abstract
Chronic heart failure is debilitating, often fatal, expensive to treat and common. In most patients it is a late consequence of myocardial infarction (MI). The intracellular signals following infarction that lead to diminished contractility, apoptosis, fibrosis and ultimately heart failure are not fully understood but probably involve p38-mitogen activated protein kinases (p38), a family of serine/threonine kinases which, when activated, cause cardiomyocyte contractile dysfunction and death. Pharmacological inhibitors of p38 suppress inflammation and are undergoing clinical trials in rheumatoid arthritis, Chrohn's disease, psoriasis and surgery-induced tissue injury. In this review, we discuss the mechanisms, circumstances and consequences of p38 activation in the heart. The purpose is to evaluate p38 inhibition as a potential therapy for ischaemic heart disease.
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Affiliation(s)
- James E Clark
- The Cardiovascular Division, King's College London, The Rayne Institute, St Thomas' Hospital, London, SE1 7EH, United Kingdom
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Jaswal JS, Gandhi M, Finegan BA, Dyck JRB, Clanachan AS. Inhibition of p38 MAPK and AMPK restores adenosine-induced cardioprotection in hearts stressed by antecedent ischemia by altering glucose utilization. Am J Physiol Heart Circ Physiol 2007; 293:H1107-14. [PMID: 17496214 DOI: 10.1152/ajpheart.00455.2007] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
p38 mitogen-activated protein kinase (MAPK) and 5′-AMP-activated protein kinase (AMPK) are activated by metabolic stresses and are implicated in the regulation of glucose utilization and ischemia-reperfusion (IR) injury. This study tested the hypothesis that inhibition of p38 MAPK restores the cardioprotective effects of adenosine in stressed hearts by preventing activation of AMPK and the uncoupling of glycolysis from glucose oxidation. Working rat hearts were perfused with Krebs solution (1.2 mM palmitate, 11 mM [3H/14C]glucose, and 100 mU/l insulin). Hearts were stressed by transient antecedent IR (2 × 10 min I/5 min R) before severe IR (30 min I/30 min R). Hearts were treated with vehicle, p38 MAPK inhibitor (SB-202190, 10 μM), adenosine (500 μM), or their combination before severe IR. After severe IR, the phosphorylation (arbitrary density units) of p38 MAPK and AMPK, rates of glucose metabolism (μmol·g dry wt−1·min−1), and recovery of left ventricular (LV) work (Joules) were similar in vehicle-, SB-202190- and adenosine-treated hearts. Treatment with SB-202190 + adenosine versus adenosine alone decreased p38 MAPK (0.03 ± 0.01, n = 3 vs. 0.48 ± 0.10, n = 3, P < 0.05) and AMPK (0.00 ± 0.00, n = 3 vs. 0.26 ± 0.08, n = 3 P < 0.05) phosphorylation. This was accompanied by attenuated rates of glycolysis (1.51 ± 0.40, n = 7 vs. 3.95 ± 0.65, n = 7, P < 0.05) and H+ production (2.12 ± 0.76, n = 7 vs. 6.96 ± 1.48, n = 7, P < 0.05), and increased glycogen synthesis (1.91 ± 0.25, n = 6 vs. 0.27 ± 0.28, n = 6, P < 0.05) and improved recovery of LV work (0.81 ± 0.08, n = 7 vs. 0.30 ± 0.15, n = 8, P < 0.05). These data indicate that inhibition of p38 MAPK abolishes subsequent phosphorylation of AMPK and improves the coupling of glucose metabolism, thereby restoring adenosine-induced cardioprotection.
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Affiliation(s)
- Jagdip S Jaswal
- Department of Pharmacology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton Alberta T6G 2H7, Canada
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Ruusalepp A, Czibik G, Flatebø T, Vaage J, Valen G. Myocardial protection evoked by hyperoxic exposure involves signaling through nitric oxide and mitogen activated protein kinases. Basic Res Cardiol 2007; 102:318-26. [PMID: 17268885 DOI: 10.1007/s00395-007-0644-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2006] [Revised: 12/27/2006] [Accepted: 01/03/2007] [Indexed: 11/24/2022]
Abstract
BACKGROUND Hyperoxic exposure in vivo (> 95% oxygen) attenuates ischemia-reperfusion injury, but the signaling mechanisms of this cardioprotection are not fully determined. We studied a possible role of nitric oxide (NO) and mitogen activated protein kinases (MAPK) in hyperoxic protection. METHODS Mice (n = 7-9 in each group) were kept in normoxic or hyperoxic environments for 15 min prior to harvesting the heart and Langendorff perfusion with global ischemia (45 min) and reperfusion (60 min). Endpoints were cardiac function and infarct size. Additional hearts were collected to evaluate MAPK phosphorylation (immunoblot). The nitric oxide synthase inhibitor L-NAME, the ERK1/2 inhibitor PD98059 and the p38 MAPK inhibitor FR167653 were injected intraperitoneally before hyperoxia or normoxia. RESULTS Hyperoxia improved postischemic functional recovery and reduced infarct size (p < 0.05). Hyperoxic exposure caused cardiac phosphorylation of the MAPK family members p38 and ERK1/2, but not JNK. L-NAME, PD98059 and FR167653 all reduced the protection afforded by hyperoxic exposure, but did not influence performance or infarction in hearts of normoxic mice. The hyperoxia-induced phosphorylation of ERK1/2 and p38 was reduced by L-NAME and both MAPK inhibitors. CONCLUSION Nitric oxide triggers hyperoxic protection, and ERK1/2 and p38 MAPK are involved in signaling of protection against ischemia-reperfusion injury.
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Affiliation(s)
- Arno Ruusalepp
- Institute of Basic Medical Science, Dept. of Physiology University of Oslo, Oslo, Norway.
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