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Westenbrink BD, Edwards AG, McCulloch AD, Brown JH. The promise of CaMKII inhibition for heart disease: preventing heart failure and arrhythmias. Expert Opin Ther Targets 2013; 17:889-903. [PMID: 23789646 DOI: 10.1517/14728222.2013.809064] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
INTRODUCTION Calcium-calmodulin-dependent protein kinase II (CaMKII) has emerged as a central mediator of cardiac stress responses which may serve several critical roles in the regulation of cardiac rhythm, cardiac contractility and growth. Sustained and excessive activation of CaMKII during cardiac disease has, however, been linked to arrhythmias, and maladaptive cardiac remodeling, eventually leading to heart failure (HF) and sudden cardiac death. AREAS COVERED In the current review, the authors describe the unique structural and biochemical properties of CaMKII and focus on its physiological effects in cardiomyocytes. Furthermore, they provide evidence for a role of CaMKII in cardiac pathologies, including arrhythmogenesis, myocardial ischemia and HF development. The authors conclude by discussing the potential for CaMKII as a target for inhibition in heart disease. EXPERT OPINION CaMKII provides a promising nodal point for intervention that may allow simultaneous prevention of HF progression and development of arrhythmias. For future studies and drug development there is a strong rationale for the development of more specific CaMKII inhibitors. In addition, an improved understanding of the differential roles of CaMKII subtypes is required.
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Affiliation(s)
- B Daan Westenbrink
- University of California, Department of Pharmacology, San Diego, La Jolla, CA, USA
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302
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Johnsen AB, Høydal M, Røsbjørgen R, Stølen T, Wisløff U. Aerobic interval training partly reverse contractile dysfunction and impaired Ca2+ handling in atrial myocytes from rats with post infarction heart failure. PLoS One 2013; 8:e66288. [PMID: 23799089 PMCID: PMC3682943 DOI: 10.1371/journal.pone.0066288] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 05/05/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND There is limited knowledge about atrial myocyte Ca(2+) handling in the failing hearts. The aim of this study was to examine atrial myocyte contractile function and Ca(2+) handling in rats with post-infarction heart failure (HF) and to examine whether aerobic interval training could reverse a potential dysfunction. METHODS AND RESULTS Post-infarction HF was induced in Sprague Dawley rats by ligation of the left descending coronary artery. Atrial myocyte shortening was depressed (p<0.01) and time to relaxation was prolonged (p<0.01) in sedentary HF-rats compared to healthy controls. This was associated with decreased Ca(2+) amplitude, decreased SR Ca(2+) content, and slower Ca(2+) transient decay. Atrial myocytes from HF-rats had reduced sarcoplasmic reticulum Ca(2+) ATPase activity, increased Na(+)/Ca(2+)-exchanger activity and increased diastolic Ca(2+) leak through ryanodine receptors. High intensity aerobic interval training in HF-rats restored atrial myocyte contractile function and reversed changes in atrial Ca(2+) handling in HF. CONCLUSION Post infarction HF in rats causes profound impairment in atrial myocyte contractile function and Ca(2+) handling. The observed dysfunction in atrial myocytes was partly reversed after aerobic interval training.
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Affiliation(s)
- Anne Berit Johnsen
- K.G. Jebsen Center of Exercise in Medicine, Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Morten Høydal
- K.G. Jebsen Center of Exercise in Medicine, Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Ragnhild Røsbjørgen
- K.G. Jebsen Center of Exercise in Medicine, Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Tomas Stølen
- K.G. Jebsen Center of Exercise in Medicine, Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Ulrik Wisløff
- K.G. Jebsen Center of Exercise in Medicine, Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway
- * E-mail:
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303
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The effects of neuregulin on cardiac Myosin light chain kinase gene-ablated hearts. PLoS One 2013; 8:e66720. [PMID: 23776695 PMCID: PMC3679076 DOI: 10.1371/journal.pone.0066720] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 05/09/2013] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Activation of ErbB2/4 receptor tyrosine kinases in cardiomyocytes by neuregulin treatment is associated with improvement in cardiac function, supporting its use in human patients with heart failure despite the lack of a specific mechanism. Neuregulin infusion in rodents increases cardiac myosin light chain kinase (cMLCK) expression and cardiac myosin regulatory light chain (RLC) phosphorylation which may improve actin-myosin interactions for contraction. We generated a cMLCK knockout mouse to test the hypothesis that cMLCK is necessary for neuregulin-induced improvement in cardiac function by increasing RLC phosphorylation. PRINCIPAL FINDINGS The cMLCK knockout mice have attenuated RLC phosphorylation and decreased cardiac performance measured as fractional shortening. Neuregulin infusion for seven days in wildtype mice increased cardiac cMLCK protein expression and RLC phosphorylation while increasing Akt phosphorylation and decreasing phospholamban phosphorylation. There was no change in fractional shortening. In contrast, neuregulin infusion in cMLCK knockout animals increased cardiac performance in the absence of cMLCK without increasing RLC phosphorylation. In addition, CaMKII signaling appeared to be enhanced in neuregulin-treated knockout mice. CONCLUSIONS Thus, Neuregulin may improve cardiac performance in the failing heart without increasing cMLCK and RLC phosphorylation by activating other signaling pathways.
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304
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Yamaguchi N, Chakraborty A, Huang TQ, Xu L, Gomez AC, Pasek DA, Meissner G. Cardiac hypertrophy associated with impaired regulation of cardiac ryanodine receptor by calmodulin and S100A1. Am J Physiol Heart Circ Physiol 2013; 305:H86-94. [PMID: 23666671 DOI: 10.1152/ajpheart.00144.2013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The cardiac ryanodine receptor (RyR2) is inhibited by calmodulin (CaM) and S100A1. Simultaneous substitution of three amino acid residues (W3587A, L3591D, F3603A; RyR2ADA) in the CaM binding domain of RyR2 results in loss of CaM inhibition at submicromolar (diastolic) and micromolar (systolic) Ca²⁺, cardiac hypertrophy, and heart failure in Ryr2ADA/ADA mice. To address whether cardiac hypertrophy results from the elimination of CaM and S100A1 inhibition at diastolic or systolic Ca²⁺, a mutant mouse was generated with a single RyR2 amino acid substitution (L3591D; RyR2D). Here we report that in single-channel measurements RyR2-L3591D isolated from Ryr2D/D hearts lost CaM inhibition at diastolic Ca²⁺ only, whereas S100A1 regulation was eliminated at both diastolic and systolic Ca²⁺. In contrast to the ~2-wk life span of Ryr2ADA/ADA mice, Ryr2D/D mice lived longer than 1 yr. Six-month-old Ryr2D/D mice showed a 9% increase in heart weight-to-body weight ratio, modest changes in cardiac morphology, and a twofold increase in atrial natriuretic peptide mRNA levels compared with wild type. After 4-wk pressure overload with transverse aortic constriction, heart weight-to-body weight ratio and atrial natriuretic peptide mRNA levels increased and echocardiography showed changes in heart morphology of Ryr2D/D mice compared with sham-operated mice. Collectively, the findings indicate that the single RyR2-L3591D mutation, which distinguishes the effects of diastolic and systolic Ca²⁺, alters heart size and cardiac function to a lesser extent in Ryr2D/D mice than the triple mutation in Ryr2ADA/ADA mice. They further suggest that CaM inhibition of RyR2 at systolic Ca²⁺ is important for maintaining normal cardiac function.
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Affiliation(s)
- Naohiro Yamaguchi
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA
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305
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Lu CC, Xu YQ, Wu JC, Hang PZ, Wang Y, Wang C, Wu JW, Qi JC, Zhang Y, Du ZM. Vitexin protects against cardiac hypertrophy via inhibiting calcineurin and CaMKII signaling pathways. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2013; 386:747-55. [DOI: 10.1007/s00210-013-0873-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 04/08/2013] [Indexed: 11/28/2022]
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306
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Yaniv Y, Spurgeon HA, Ziman BD, Lyashkov AE, Lakatta EG. Mechanisms that match ATP supply to demand in cardiac pacemaker cells during high ATP demand. Am J Physiol Heart Circ Physiol 2013; 304:H1428-38. [PMID: 23604710 DOI: 10.1152/ajpheart.00969.2012] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The spontaneous action potential (AP) firing rate of sinoatrial node cells (SANCs) involves high-throughput signaling via Ca(2+)-calmodulin activated adenylyl cyclases (AC), cAMP-mediated protein kinase A (PKA), and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII)-dependent phosphorylation of SR Ca(2+) cycling and surface membrane ion channel proteins. When the throughput of this signaling increases, e.g., in response to β-adrenergic receptor activation, the resultant increase in spontaneous AP firing rate increases the demand for ATP. We hypothesized that an increase of ATP production to match the increased ATP demand is achieved via a direct effect of increased mitochondrial Ca(2+) (Ca(2+)m) and an indirect effect via enhanced Ca(2+)-cAMP/PKA-CaMKII signaling to mitochondria. To increase ATP demand, single isolated rabbit SANCs were superfused by physiological saline at 35 ± 0.5°C with isoproterenol, or by phosphodiesterase or protein phosphatase inhibition. We measured cytosolic and mitochondrial Ca(2+) and flavoprotein fluorescence in single SANC, and we measured cAMP, ATP, and O₂ consumption in SANC suspensions. Although the increase in spontaneous AP firing rate was accompanied by an increase in O₂ consumption, the ATP level and flavoprotein fluorescence remained constant, indicating that ATP production had increased. Both Ca(2+)m and cAMP increased concurrently with the increase in AP firing rate. When Ca(2+)m was reduced by Ru360, the increase in spontaneous AP firing rate in response to isoproterenol was reduced by 25%. Thus, both an increase in Ca(2+)m and an increase in Ca(2+) activated cAMP-PKA-CaMKII signaling regulate the increase in ATP supply to meet ATP demand above the basal level.
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Affiliation(s)
- Yael Yaniv
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
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307
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Verdejo HE, del Campo A, Troncoso R, Gutierrez T, Toro B, Quiroga C, Pedrozo Z, Munoz JP, Garcia L, Castro PF, Lavandero S. Mitochondria, myocardial remodeling, and cardiovascular disease. Curr Hypertens Rep 2013; 14:532-9. [PMID: 22972531 DOI: 10.1007/s11906-012-0305-4] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The process of muscle remodeling lies at the core of most cardiovascular diseases. Cardiac adaptation to pressure or volume overload is associated with a complex molecular change in cardiomyocytes which leads to anatomic remodeling of the heart muscle. Although adaptive at its beginnings, the sustained cardiac hypertrophic remodeling almost unavoidably ends in progressive muscle dysfunction, heart failure and ultimately death. One of the features of cardiac remodeling is a progressive impairment in mitochondrial function. The heart has the highest oxygen uptake in the human body and accordingly it has a large number of mitochondria, which form a complex network under constant remodeling in order to sustain the high metabolic rate of cardiac cells and serve as Ca(2+) buffers acting together with the endoplasmic reticulum (ER). However, this high dependence on mitochondrial metabolism has its costs: when oxygen supply is threatened, high leak of electrons from the electron transport chain leads to oxidative stress and mitochondrial failure. These three aspects of mitochondrial function (Reactive oxygen species signaling, Ca(2+) handling and mitochondrial dynamics) are critical for normal muscle homeostasis. In this article, we will review the latest evidence linking mitochondrial morphology and function with the process of myocardial remodeling and cardiovascular disease.
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Affiliation(s)
- Hugo E Verdejo
- Centro Estudios Moleculares de la Célula, Facultad Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
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308
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Lairez O, Cognet T, Schaak S, Calise D, Guilbeau-Frugier C, Parini A, Mialet-Perez J. Role of serotonin 5-HT2A receptors in the development of cardiac hypertrophy in response to aortic constriction in mice. J Neural Transm (Vienna) 2013; 120:927-35. [PMID: 23543114 DOI: 10.1007/s00702-013-1011-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Accepted: 03/08/2013] [Indexed: 11/26/2022]
Abstract
Serotonin, in addition to its fundamental role as a neurotransmitter, plays a critical role in the cardiovascular system, where it is thought to be involved in the development of cardiac hypertrophy and failure. Indeed, we recently found that mice with deletion of monoamine oxidase A had enhanced levels of blood and cardiac 5-HT, which contributed to exacerbation of hypertrophy in a model of experimental pressure overload. 5-HT2A receptors are expressed in the heart and mediate a hypertrophic response to 5-HT in cardiac cells. However, their role in cardiac remodeling in vivo and the signaling pathways associated are not well understood. In the present study, we evaluated the effect of a selective 5-HT2A receptor antagonist, M100907, on the development of cardiac hypertrophy induced by transverse aortic constriction (TAC). Cardiac 5-HT2A receptor expression was transiently increased after TAC, and was recapitulated in cardiomyocytes, as observed with 5-HT2A in situ labeling by immunohistochemistry. Selective blockade of 5-HT2A receptors prevented the development of cardiac hypertrophy, as measured by echocardiography, cardiomyocyte area and heart weight-to-body weight ratio. Interestingly, activation of calmodulin kinase (CamKII), which is a core mechanism in cardiac hypertrophy, was reduced in cardiac samples from M100907-treated TAC mice compared to vehicle-treated mice. In addition, phosphorylation of histone deacetylase 4 (HDAC4), a downstream partner of CamKII was significantly diminished in M100907-treated TAC mice. Thus, our results show that selective blockade of 5-HT2A receptors has beneficial effect in the development of cardiac hypertrophy through inhibition of the CamKII/HDAC4 pathway.
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Affiliation(s)
- O Lairez
- INSERM UMR 1048, Institut des Maladies Métaboliques et Cardiovasculaires, BP 84225, 31432, Toulouse Cedex 4, France
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309
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Fu Q, Chen X, Xiang YK. Compartmentalization of β-adrenergic signals in cardiomyocytes. Trends Cardiovasc Med 2013; 23:250-6. [PMID: 23528751 DOI: 10.1016/j.tcm.2013.02.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 01/03/2013] [Accepted: 01/04/2013] [Indexed: 11/19/2022]
Abstract
Under β-adrenergic stimulation, the distribution of cAMP is highly restricted at distinct intracellular domains for compartmentalized activation of protein kinase A, which promotes selective phosphorylation of proteins for contractile responses in cardiomyocytes. This is primarily due to a concerted effort between restrictions of cAMP distribution by a family of phosphodiesterases and locally anchored protein kinase A by a family of scaffold A kinase-anchoring proteins. Moreover, these regulatory mechanisms underlie the cross talk between β-adrenergic signals and other receptor-stimulated signaling cascades, which alters the compartmentalized β-adrenergic signals for proper contractility in myocardium. Maintaining integrity of compartmentalized β-adrenergic signals is critical for physiological cardiac function and for preventing development of cardiac diseases.
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Affiliation(s)
- Qin Fu
- Department of Pharmacology, University of California at Davis, Davis, CA 95616; Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
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310
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Roe ND, Ren J. Oxidative activation of Ca(2+)/calmodulin-activated kinase II mediates ER stress-induced cardiac dysfunction and apoptosis. Am J Physiol Heart Circ Physiol 2013; 304:H828-39. [PMID: 23316062 PMCID: PMC3602775 DOI: 10.1152/ajpheart.00752.2012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 12/20/2012] [Indexed: 12/23/2022]
Abstract
Endoplasmic reticulum (ER) stress elicits oxidative stress and intracellular Ca(2+) derangement via activation of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII). This study was designed to examine the role of CaMKII in ER stress-induced cardiac dysfunction and apoptosis as well as the effect of antioxidant catalase. Wild-type FVB and transgenic mice with cardiac-specific overexpression of catalase were challenged with the ER stress inducer tunicamycin (3 mg/kg ip for 48 h). Presence of ER stress was verified using the ER stress protein markers immunoglobulin binding protein (BiP) and C/EBP homologous protein (CHOP), the effect of which was unaffected by catalase overexpression. Echocardiographic assessment revealed that tunicamycin elicited cardiac remodeling (enlarged end-systolic diameter without affecting diastolic and ventricular wall thickness), depressed fractional shortening, ejection fraction, and cardiomyocyte contractile capacity, intracellular Ca(2+) mishandling, accumulation of reactive oxygen species (superoxide production and NADPH oxidase p47phox level), CaMKII oxidation, and apoptosis (evidenced by Bax, Bcl-2/Bax ratio, and TUNEL staining), the effects of which were obliterated by catalase. Interestingly, tunicamycin-induced cardiomyocyte mechanical anomalies and cell death were ablated by the CaMKII inhibitor KN93, in a manner reminiscent of catalase. These data favored a permissive role of oxidative stress and CaMKII activation in ER stress-induced cardiac dysfunction and cell death. Our data further revealed the therapeutic potential of antioxidant or CaMKII inhibition in cardiac pathological conditions associated with ER stress. This research shows for the first time that contractile dysfunction caused by ER stress is a result of the oxidative activation of the CaMKII pathway.
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Affiliation(s)
- Nathan D Roe
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming College of Health Sciences, School of Pharmacy, Laramie, WY 82071, USA
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311
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Yaniv Y, Spurgeon HA, Ziman BD, Lakatta EG. Ca²+/calmodulin-dependent protein kinase II (CaMKII) activity and sinoatrial nodal pacemaker cell energetics. PLoS One 2013; 8:e57079. [PMID: 23459256 PMCID: PMC3581576 DOI: 10.1371/journal.pone.0057079] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 01/18/2013] [Indexed: 11/18/2022] Open
Abstract
UNLABELLED : Ca(2+)-activated basal adenylate cyclase (AC) in rabbit sinoatrial node cells (SANC) guarantees, via basal cAMP/PKA-calmodulin/CaMKII-dependent protein phosphorylation, the occurrence of rhythmic, sarcoplasmic-reticulum generated, sub-membrane Ca(2+) releases that prompt rhythmic, spontaneous action potentials (APs). This high-throughput signaling consumes ATP. AIMS We have previously demonstrated that basal AC-cAMP/PKA signaling directly, and Ca(2+) indirectly, regulate mitochondrial ATP production. While, clearly, Ca(2+)-calmodulin-CaMKII activity regulates ATP consumption, whether it has a role in the control of ATP production is unknown. METHODS AND RESULTS We superfused single, isolated rabbit SANC at 37°C with physiological saline containing CaMKII inhibitors, (KN-93 or autocamtide-2 Related Inhibitory Peptide (AIP)), or a calmodulin inhibitor (W-7) and measured cytosolic Ca(2+), flavoprotein fluorescence and spontaneous AP firing rate. We measured cAMP, ATP and O2 consumption in cell suspensions. Graded reductions in basal CaMKII activity by KN-93 (0.5-3 µmol/L) or AIP (2-10 µmol/L) markedly slow the kinetics of intracellular Ca(2+) cycling, decrease the spontaneous AP firing rate, decrease cAMP, and reduce O2 consumption and flavoprotein fluorescence. In this context of graded reductions in ATP demand, however, ATP also becomes depleted, indicating reduced ATP production. CONCLUSIONS CaMKII signaling, a crucial element of normal automaticity in rabbit SANC, is also involved in SANC bioenergetics.
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Affiliation(s)
- Yael Yaniv
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Harold A. Spurgeon
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Bruce D. Ziman
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Edward G. Lakatta
- Laboratory of Cardiovascular Science, Gerontology Research Center, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, Maryland, United States of America
- * E-mail:
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312
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Belevych AE, Radwański PB, Carnes CA, Györke S. 'Ryanopathy': causes and manifestations of RyR2 dysfunction in heart failure. Cardiovasc Res 2013; 98:240-7. [PMID: 23408344 DOI: 10.1093/cvr/cvt024] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The cardiac ryanodine receptor (RyR2), a Ca(2+) release channel on the membrane of the sarcoplasmic reticulum (SR), plays a key role in determining the strength of the heartbeat by supplying Ca(2+) required for contractile activation. Abnormal RyR2 function is recognized as an important part of the pathophysiology of heart failure (HF). While in the normal heart, the balance between the cytosolic and intra-SR Ca(2+) regulation of RyR2 function maintains the contraction-relaxation cycle, in HF, this behaviour is compromised by excessive post-translational modifications of the RyR2. Such modification of the Ca(2+) release channel impairs the ability of the RyR2 to properly deactivate leading to a spectrum of Ca(2+)-dependent pathologies that include cardiac systolic and diastolic dysfunction, arrhythmias, and structural remodelling. In this article, we present an overview of recent advances in our understanding of the underlying causes and pathological consequences of abnormal RyR2 function in the failing heart. We also discuss the implications of these findings for HF therapy.
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Affiliation(s)
- Andriy E Belevych
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University, Columbus, OH 43210, USA
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313
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Abnormalities of calcium handling proteins in skeletal muscle mirror those of the heart in humans with heart failure: a shared mechanism? J Card Fail 2013; 18:724-33. [PMID: 22939042 DOI: 10.1016/j.cardfail.2012.07.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 07/16/2012] [Accepted: 07/17/2012] [Indexed: 11/21/2022]
Abstract
BACKGROUND In the failing human heart, abnormalities of Ca(2+) cycling have been described, but there is scant knowledge about Ca(2+) handling in the skeletal muscle of humans with heart failure (HF). We tested the hypothesis that in humans with HF, Ca(2+) cycling proteins in skeletal muscle are abnormal. METHODS AND RESULTS Ten advanced HF patients (50.4 ± 3.7 years), and 9 age-matched controls underwent vastus lateralis biopsy. Western blot analysis showed that sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA)2a, which is responsible for Ca(2+) sequestration into the sarcoplasmic reticulum(SR), was lower in HF versus controls (4.8 ± 0.5 vs 7.5 ± 0.8 AU, P = .01). Although phospholamban (PLN), which inhibits SERCA2a, was not different in HF versus controls, phosphorylation (SER16 site) of PLN, which relieves this inhibition, was reduced (0.8 ± 0.1 vs 3.9 ± 0.9 AU, P = .004). Dihydropyridine receptors were reduced in HF, (2.1 ± 0.4 vs 3.6 ± 0.5 AU, P = .04). We tested the hypothesis that these abnormalities of Ca(2+) handling protein content and regulation were due to increased oxidative stress, but oxygen radical scavenger proteins were not elevated in the skeletal muscle of HF patients. CONCLUSION In chronic HF, marked abnormalities of Ca(2+) handling proteins are present in skeletal muscle, which mirror those in failing heart tissue. This suggests a common mechanism, such as chronic augmentation of sympathetic activity and autophosphorylation of Ca(2+)-calmodulin-dependent-protein kinase II.
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314
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DeGrande ST, Little SC, Nixon DJ, Wright P, Snyder J, Dun W, Murphy N, Kilic A, Higgins R, Binkley PF, Boyden PA, Carnes CA, Anderson ME, Hund TJ, Mohler PJ. Molecular mechanisms underlying cardiac protein phosphatase 2A regulation in heart. J Biol Chem 2013; 288:1032-46. [PMID: 23204520 PMCID: PMC3542989 DOI: 10.1074/jbc.m112.426957] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Revised: 11/21/2012] [Indexed: 11/06/2022] Open
Abstract
Kinase/phosphatase balance governs cardiac excitability in health and disease. Although detailed mechanisms for cardiac kinase regulation are established, far less is known regarding cardiac protein phosphatase 2A (PP2A) regulation. This is largely due to the complexity of the PP2A holoenzyme structure (combinatorial assembly of three subunit enzyme from >17 subunit genes) and the inability to segregate "global" PP2A function from the activities of multiple "local" holoenzyme populations. Here we report that PP2A catalytic, regulatory, and scaffolding subunits are tightly regulated at transcriptional, translational, and post-translational levels to tune myocyte function at base line and in disease. We show that past global read-outs of cellular PP2A activity more appropriately represent the collective activity of numerous individual PP2A holoenzymes, each displaying a specific subcellular localization (dictated by select PP2A regulatory subunits) as well as local specific post-translational catalytic subunit methylation and phosphorylation events that regulate local and rapid holoenzyme assembly/disassembly (via leucine carboxymethyltransferase 1/phosphatase methylesterase 1 (LCMT-1/PME-1). We report that PP2A subunits are selectively regulated between human and animal models, across cardiac chambers, and even within specific cardiac cell types. Moreover, this regulation can be rapidly tuned in response to cellular activation. Finally, we report that global PP2A is altered in human and experimental models of heart disease, yet each pathology displays its own distinct molecular signature though specific PP2A subunit modulatory events. These new data provide an initial view into the signaling pathways that govern PP2A function in heart but also establish the first step in defining specific PP2A regulatory targets in health and disease.
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Affiliation(s)
- Sean T. DeGrande
- From The Dorothy M. Davis Heart and Lung Research Institute
- Department of Internal Medicine, Division of Cardiovascular Medicine
- the Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, and
| | - Sean C. Little
- From The Dorothy M. Davis Heart and Lung Research Institute
| | - Derek J. Nixon
- From The Dorothy M. Davis Heart and Lung Research Institute
| | - Patrick Wright
- From The Dorothy M. Davis Heart and Lung Research Institute
| | - Jedidiah Snyder
- From The Dorothy M. Davis Heart and Lung Research Institute
- Department of Internal Medicine, Division of Cardiovascular Medicine
- College of Engineering, Department of Biomedical Engineering, and
| | - Wen Dun
- the Department of Pharmacology, Columbia University, New York, New York 10032
| | | | - Ahmet Kilic
- From The Dorothy M. Davis Heart and Lung Research Institute
- Division of Cardiac Surgery, The Ohio State University Wexner Medical Center
| | - Robert Higgins
- From The Dorothy M. Davis Heart and Lung Research Institute
- Division of Cardiac Surgery, The Ohio State University Wexner Medical Center
| | - Philip F. Binkley
- From The Dorothy M. Davis Heart and Lung Research Institute
- Department of Internal Medicine, Division of Cardiovascular Medicine
| | - Penelope A. Boyden
- the Department of Pharmacology, Columbia University, New York, New York 10032
| | - Cynthia A. Carnes
- From The Dorothy M. Davis Heart and Lung Research Institute
- The College of Pharmacy, The Ohio State University, Columbus, Ohio 43210
| | - Mark E. Anderson
- the Department of Internal Medicine, Division of Cardiovascular Medicine and
- the Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, and
| | - Thomas J. Hund
- From The Dorothy M. Davis Heart and Lung Research Institute
- Department of Internal Medicine, Division of Cardiovascular Medicine
- College of Engineering, Department of Biomedical Engineering, and
| | - Peter J. Mohler
- From The Dorothy M. Davis Heart and Lung Research Institute
- Department of Internal Medicine, Division of Cardiovascular Medicine
- Department of Physiology and Cell Biology
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315
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Li RC, Tao J, Guo YB, Wu HD, Liu RF, Bai Y, Lv ZZ, Luo GZ, Li LL, Wang M, Yang HQ, Gao W, Han QD, Zhang YY, Wang XJ, Xu M, Wang SQ. In vivo suppression of microRNA-24 prevents the transition toward decompensated hypertrophy in aortic-constricted mice. Circ Res 2013; 112:601-5. [PMID: 23307820 DOI: 10.1161/circresaha.112.300806] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
RATIONALE During the transition from compensated hypertrophy to heart failure, the signaling between L-type Ca(2+) channels in the cell membrane/T-tubules and ryanodine receptors in the sarcoplasmic reticulum becomes defective, partially because of the decreased expression of a T-tubule-sarcoplasmic reticulum anchoring protein, junctophilin-2. MicroRNA (miR)-24, a junctophilin-2 suppressing miR, is upregulated in hypertrophied and failing cardiomyocytes. OBJECTIVE To test whether miR-24 suppression can protect the structural and functional integrity of L-type Ca(2+) channel-ryanodine receptor signaling in hypertrophied cardiomyocytes. METHODS AND RESULTS In vivo silencing of miR-24 by a specific antagomir in an aorta-constricted mouse model effectively prevented the degradation of heart contraction, but not ventricular hypertrophy. Electrophysiology and confocal imaging studies showed that antagomir treatment prevented the decreases in L-type Ca(2+) channel-ryanodine receptor signaling fidelity/efficiency and whole-cell Ca(2+) transients. Further studies showed that antagomir treatment stabilized junctophilin-2 expression and protected the ultrastructure of T-tubule-sarcoplasmic reticulum junctions from disruption. CONCLUSIONS MiR-24 suppression prevented the transition from compensated hypertrophy to decompensated hypertrophy, providing a potential strategy for early treatment against heart failure.
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Affiliation(s)
- Rong-Chang Li
- College of Life Sciences, Peking University, Beijing 100871, China
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316
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Hamdani N, Krysiak J, Kreusser MM, Neef S, Dos Remedios CG, Maier LS, Krüger M, Backs J, Linke WA. Crucial role for Ca2(+)/calmodulin-dependent protein kinase-II in regulating diastolic stress of normal and failing hearts via titin phosphorylation. Circ Res 2013; 112:664-74. [PMID: 23283722 DOI: 10.1161/circresaha.111.300105] [Citation(s) in RCA: 140] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
RATIONALE Myocardial diastolic stiffness and cardiomyocyte passive force (F(passive)) depend in part on titin isoform composition and phosphorylation. Ca(2+)/calmodulin-dependent protein kinase-II (CaMKII) phosphorylates ion channels, Ca(2+)-handling proteins, and chromatin-modifying enzymes in the heart, but has not been known to target titin. OBJECTIVE To elucidate whether CaMKII phosphorylates titin and modulates F(passive) in normal and failing myocardium. METHODS AND RESULTS Titin phosphorylation was assessed in CaMKIIδ/γ double-knockout (DKO) mouse, transgenic CaMKIIδC-overexpressing mouse, and human hearts, by Pro-Q-Diamond/Sypro-Ruby staining, autoradiography, and immunoblotting using phosphoserine-specific titin-antibodies. CaMKII-dependent site-specific titin phosphorylation was quantified in vivo by mass spectrometry using stable isotope labeling by amino acids in cell culture mouse heart mixed with wild-type (WT) or DKO heart. F(passive) of single permeabilized cardiomyocytes was recorded before and after CaMKII-administration. All-titin phosphorylation was reduced by >50% in DKO but increased by up to ≈100% in transgenic versus WT hearts. Conserved CaMKII-dependent phosphosites were identified within the PEVK-domain of titin by quantitative mass spectrometry and confirmed in recombinant human PEVK-fragments. CaMKII also phosphorylated the cardiac titin N2B-unique sequence. Phosphorylation at specific PEVK/titin N2B-unique sequence sites was decreased in DKO and amplified in transgenic versus WT hearts. F(passive) was elevated in DKO and reduced in transgenic compared with WT cardiomyocytes. CaMKII-administration lowered F(passive) of WT and DKO cardiomyocytes, an effect blunted by titin antibody pretreatment. Human end-stage failing hearts revealed higher CaMKII expression/activity and phosphorylation at PEVK/titin N2B-unique sequence sites than nonfailing donor hearts. CONCLUSIONS CaMKII phosphorylates the titin springs at conserved serines/threonines, thereby lowering F(passive). Deranged CaMKII-dependent titin phosphorylation occurs in heart failure and contributes to altered diastolic stress.
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Affiliation(s)
- Nazha Hamdani
- Department of Cardiovascular Physiology, Ruhr University Bochum, Bochum, Germany
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317
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318
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van Berlo JH, Maillet M, Molkentin JD. Signaling effectors underlying pathologic growth and remodeling of the heart. J Clin Invest 2013; 123:37-45. [PMID: 23281408 DOI: 10.1172/jci62839] [Citation(s) in RCA: 334] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Cardiovascular disease is the number one cause of mortality in the Western world. The heart responds to many cardiopathological conditions with hypertrophic growth by enlarging individual myocytes to augment cardiac pump function and decrease ventricular wall tension. Initially, such cardiac hypertrophic growth is often compensatory, but as time progresses these changes become maladaptive. Cardiac hypertrophy is the strongest predictor for the development of heart failure, arrhythmia, and sudden death. Here we discuss therapeutic avenues emerging from molecular and genetic studies of cardiovascular disease in animal models. The majority of these are based on intracellular signaling pathways considered central to pathologic cardiac remodeling and hypertrophy, which then leads to heart failure. We focus our discussion on selected therapeutic targets that have more recently emerged and have a tangible translational potential given the available pharmacologic agents that could be readily evaluated in human clinical trials.
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Affiliation(s)
- Jop H van Berlo
- Department of Pediatrics, University of Cincinnati, Cincinnati Children’s Hospital Medical Center, Howard Hughes Medical Institute, Cincinnati, Ohio 45229-3039, USA
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319
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Sun B, Huo R, Sheng Y, Li Y, Xie X, Chen C, Liu HB, Li N, Li CB, Guo WT, Zhu JX, Yang BF, Dong DL. Bone morphogenetic protein-4 mediates cardiac hypertrophy, apoptosis, and fibrosis in experimentally pathological cardiac hypertrophy. Hypertension 2012; 61:352-60. [PMID: 23248151 DOI: 10.1161/hypertensionaha.111.00562] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Identifying the key factor mediating pathological cardiac hypertrophy is critically important for developing the strategy to protect against heart failure. Bone morphogenetic protein-4 (BMP4) is a mechanosensitive and proinflammatory gene. In this study, we investigated the role of BMP4 in cardiac hypertrophy, apoptosis, and fibrosis in experimentally pathological cardiac hypertrophy. The in vivo pathological cardiac hypertrophy models were induced by pressure-overload and angiotensin (Ang) II constant infusion in mice, and the in vitro model was induced by Ang II exposure to cultured cardiomyocytes. The expression of BMP4 increased in pressure overload, Ang II constant infusion-induced pathological cardiac hypertrophy, but not in swimming exercise-induced physiological cardiac hypertrophy in mice. BMP4 expression also increased in Ang II-induced cardiomyocyte hypertrophy in vitro. In turn, BMP4 induced cardiomyocyte hypertrophy, apoptosis, and cardiac fibrosis, and these pathological consequences were inhibited by the treatment with BMP4 inhibitors noggin and DMH1. Moreover, Ang II-induced cardiomyocyte hypertrophy was inhibited by BMP4 inhibitors. The underlying mechanism that BMP4-induced cardiomyocyte hypertrophy and apoptosis was through increasing NADPH oxidase 4 expression and reactive oxygen species-dependent pathways. Lentivirus-mediated overexpression of BMP4 recapitulated hypertrophy and apoptosis in cultured cardiomyocytes. BMP4 inhibitor DMH1 inhibited pressure overload-induced cardiac hypertrophy in mice in vivo. The plasma BMP4 level of heart failure patients was increased compared with that of subjects without heart failure. In summary, we conclude that BMP4 is a mediator and novel therapeutic target for pathological cardiac hypertrophy.
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Affiliation(s)
- Bo Sun
- Department of Pharmacology, Harbin Medical University, Baojian Rd 157, Harbin 150086, Heilongjiang Province, P.R. China
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320
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Sierra A, Zhu Z, Sapay N, Sharotri V, Kline CF, Luczak ED, Subbotina E, Sivaprasadarao A, Snyder PM, Mohler PJ, Anderson ME, Vivaudou M, Zingman LV, Hodgson-Zingman DM. Regulation of cardiac ATP-sensitive potassium channel surface expression by calcium/calmodulin-dependent protein kinase II. J Biol Chem 2012; 288:1568-81. [PMID: 23223335 DOI: 10.1074/jbc.m112.429548] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Cardiac ATP-sensitive potassium (K(ATP)) channels are key sensors and effectors of the metabolic status of cardiomyocytes. Alteration in their expression impacts their effectiveness in maintaining cellular energy homeostasis and resistance to injury. We sought to determine how activation of calcium/calmodulin-dependent protein kinase II (CaMKII), a central regulator of calcium signaling, translates into reduced membrane expression and current capacity of cardiac K(ATP) channels. We used real-time monitoring of K(ATP) channel current density, immunohistochemistry, and biotinylation studies in isolated hearts and cardiomyocytes from wild-type and transgenic mice as well as HEK cells expressing wild-type and mutant K(ATP) channel subunits to track the dynamics of K(ATP) channel surface expression. Results showed that activation of CaMKII triggered dynamin-dependent internalization of K(ATP) channels. This process required phosphorylation of threonine at 180 and 224 and an intact (330)YSKF(333) endocytosis motif of the K(ATP) channel Kir6.2 pore-forming subunit. A molecular model of the μ2 subunit of the endocytosis adaptor protein, AP2, complexed with Kir6.2 predicted that μ2 docks by interaction with (330)YSKF(333) and Thr-180 on one and Thr-224 on the adjacent Kir6.2 subunit. Phosphorylation of Thr-180 and Thr-224 would favor interactions with the corresponding arginine- and lysine-rich loops on μ2. We concluded that calcium-dependent activation of CaMKII results in phosphorylation of Kir6.2, which promotes endocytosis of cardiac K(ATP) channel subunits. This mechanism couples the surface expression of cardiac K(ATP) channels with calcium signaling and reveals new targets to improve cardiac energy efficiency and stress resistance.
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Affiliation(s)
- Ana Sierra
- Department of Internal Medicine, University of Iowa, Carver College of Medicine, Iowa City, Iowa 52242, USA
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321
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Hidalgo CG, Chung CS, Saripalli C, Methawasin M, Hutchinson KR, Tsaprailis G, Labeit S, Mattiazzi A, Granzier HL. The multifunctional Ca(2+)/calmodulin-dependent protein kinase II delta (CaMKIIδ) phosphorylates cardiac titin's spring elements. J Mol Cell Cardiol 2012; 54:90-7. [PMID: 23220127 DOI: 10.1016/j.yjmcc.2012.11.012] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Accepted: 11/22/2012] [Indexed: 10/27/2022]
Abstract
Titin-based passive stiffness is post-translationally regulated by several kinases that phosphorylate specific spring elements located within titin's elastic I-band region. Whether titin is phosphorylated by calcium/calmodulin dependent protein kinase II (CaMKII), an important regulator of cardiac function and disease, has not been addressed. The aim of this work was to determine whether CaMKIIδ, the predominant CaMKII isoform in the heart, phosphorylates titin, and to use phosphorylation assays and mass spectrometry to study which of titin's spring elements might be targeted by CaMKIIδ. It was found that CaMKIIδ phosphorylates titin in mouse LV skinned fibers, that the CaMKIIδ sites can be dephosphorylated by protein phosphatase 1 (PP1), and that under baseline conditions, in both intact isolated hearts and skinned myocardium, about half of the CaMKIIδ sites are phosphorylated. Mass spectrometry revealed that both the N2B and PEVK segments are targeted by CaMKIIδ at several conserved serine residues. Whether phosphorylation of titin by CaMKIIδ occurs in vivo, was tested in several conditions using back phosphorylation assays and phospho-specific antibodies to CaMKIIδ sites. Reperfusion following global ischemia increased the phosphorylation level of CaMKIIδ sites on titin and this effect was abolished by the CaMKII inhibitor KN-93. No changes in the phosphorylation level of the PEVK element were found suggesting that the increased phosphorylation level of titin in IR (ischemia reperfusion) might be due to phosphorylation of the N2B element. The findings of these studies show for the first time that titin can be phosphoryalated by CaMKIIδ, both in vitro and in vivo, and that titin's molecular spring region that determines diastolic stiffness is a target of CaMKIIδ.
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Affiliation(s)
- Carlos G Hidalgo
- Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ 85724, USA
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322
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Kalyanasundaram A, Lacombe VA, Belevych AE, Brunello L, Carnes CA, Janssen PML, Knollmann BC, Periasamy M, Gyørke S. Up-regulation of sarcoplasmic reticulum Ca(2+) uptake leads to cardiac hypertrophy, contractile dysfunction and early mortality in mice deficient in CASQ2. Cardiovasc Res 2012; 98:297-306. [PMID: 23135969 DOI: 10.1093/cvr/cvs334] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Although aberrant Ca(2+) release (i.e. Ca(2+) 'leak') from the sarcoplasmic reticulum (SR) through cardiac ryanodine receptors (RyR2) is linked to heart failure (HF), it remains unknown whether and under what conditions SR-derived Ca(2+) can actually cause HF. We tested the hypothesis that combining dysregulated RyR2 function with facilitated Ca(2+) uptake into SR will exacerbate abnormal SR Ca(2+) release and induce HF. We also examined the mechanisms for these alterations. METHODS AND RESULTS We crossbred mice deficient in expression of cardiac calsequestrin (CASQ2) with mice overexpressing the skeletal muscle isoform of SR Ca(2+)ATPase (SERCA1a). The new double-mutant strains displayed early mortality, congestive HF with left ventricular dilated hypertrophy, and decreased ejection fraction. Intact right ventricular muscle preparations from double-mutant mice preserved normal systolic contractile force but were susceptible to spontaneous contractions. Double-mutant cardiomyocytes while preserving normal amplitude of systolic Ca(2+) transients displayed marked disturbances in diastolic Ca(2+) handling in the form of multiple, periodic Ca(2+) waves and wavelets. Dysregulated myocyte Ca(2+) handling and structural and functional cardiac pathology in double-mutant mice were associated with increased rate of apoptotic cell death. Qualitatively similar results were obtained in a hybrid strain created by crossing CASQ2 knockout mice with mice deficient in phospholamban. CONCLUSION We demonstrate that enhanced SR Ca(2+) uptake combined with dysregulated RyR2s results in sustained diastolic Ca(2+) release causing apoptosis, dilated cardiomyopathy, and early mortality. Our data also suggest that up-regulation of SERCA activity must be advocated with caution as a therapy for HF in the context of abnormal RyR2 function.
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Affiliation(s)
- Anuradha Kalyanasundaram
- Department of Physiology and Cell Biology, College of Medicine, 505 Davis Heart and Lung Research Institute, The Ohio State University, 473 W 12th Ave, Columbus, OH 43210, USA
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Abstract
The field of heart transplantation has seen significant progress in the past 40 years. However, the breakthroughs in long-term outcome have seen stagnation in the past decade. Through advances in genomics and transcriptomics, there is hope that an era of personalized transplant therapy lies in the future. To see where heart transplantation truly fits into the long term, searching for and understanding the alternative approaches for heart failure therapy is both important and inevitable. The application of mechanical circulatory support has contributed to the largest advancement in treatment of end stage heart failure. It has already been approved for destination therapy of heart failure, and greater portability and ease of use of the device will be the future trend. Although it is still not prime time for stem cell therapy, clinical experiences have already suggested its potential therapeutic effects. And finally, whole organ engineering is on the horizon as new techniques have opened the way for this to proceed. In the end, progress on alternative therapies largely depends on our deeper understanding of the mechanisms of heart failure and how to prevent it.
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324
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Zhang X, Szeto C, Gao E, Tang M, Jin J, Fu Q, Makarewich C, Ai X, Li Y, Tang A, Wang J, Gao H, Wang F, Ge XJ, Kunapuli SP, Zhou L, Zeng C, Xiang KY, Chen X. Cardiotoxic and cardioprotective features of chronic β-adrenergic signaling. Circ Res 2012; 112:498-509. [PMID: 23104882 DOI: 10.1161/circresaha.112.273896] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE In the failing heart, persistent β-adrenergic receptor activation is thought to induce myocyte death by protein kinase A (PKA)-dependent and PKA-independent activation of calcium/calmodulin-dependent kinase II. β-adrenergic signaling pathways also are capable of activating cardioprotective mechanisms. OBJECTIVE This study used a novel PKA inhibitor peptide to inhibit PKA activity to test the hypothesis that β-adrenergic receptor signaling causes cell death through PKA-dependent pathways and cardioprotection through PKA-independent pathways. METHODS AND RESULTS In PKA inhibitor peptide transgenic mice, chronic isoproterenol failed to induce cardiac hypertrophy, fibrosis, and myocyte apoptosis, and decreased cardiac function. In cultured adult feline ventricular myocytes, PKA inhibition protected myocytes from death induced by β1-adrenergic receptor agonists by preventing cytosolic and sarcoplasmic reticulum Ca(2+) overload and calcium/calmodulin-dependent kinase II activation. PKA inhibition revealed a cardioprotective role of β-adrenergic signaling via cAMP/exchange protein directly activated by cAMP/Rap1/Rac/extracellular signal-regulated kinase pathway. Selective PKA inhibition causes protection in the heart after myocardial infarction that was superior to β-blocker therapy. CONCLUSIONS These results suggest that selective block of PKA could be a novel heart failure therapy.
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Affiliation(s)
- Xiaoying Zhang
- Cardiovascular Research Center, Department of Physiology, Temple University School of Medicine, Philadelphia, PA 19140, USA
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325
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Abstract
Cardiac myocyte function is dependent on the synchronized movements of Ca(2+) into and out of the cell, as well as between the cytosol and sarcoplasmic reticulum. These movements determine cardiac rhythm and regulate excitation-contraction coupling. Ca(2+) cycling is mediated by a number of critical Ca(2+)-handling proteins and transporters, such as L-type Ca(2+) channels (LTCCs) and sodium/calcium exchangers in the sarcolemma, and sarcoplasmic/endoplasmic reticulum calcium ATPase 2a (SERCA2a), ryanodine receptors, and cardiac phospholamban in the sarcoplasmic reticulum. The entry of Ca(2+) into the cytosol through LTCCs activates the release of Ca(2+) from the sarcoplasmic reticulum through ryanodine receptor channels and initiates myocyte contraction, whereas SERCA2a and cardiac phospholamban have a key role in sarcoplasmic reticulum Ca(2+) sequesteration and myocyte relaxation. Excitation-contraction coupling is regulated by phosphorylation of Ca(2+)-handling proteins. Abnormalities in sarcoplasmic reticulum Ca(2+) cycling are hallmarks of heart failure and contribute to the pathophysiology and progression of this disease. Correcting impaired intracellular Ca(2+) cycling is a promising new approach for the treatment of heart failure. Novel therapeutic strategies that enhance myocyte Ca(2+) homeostasis could prevent and reverse adverse cardiac remodeling and improve clinical outcomes in patients with heart failure.
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326
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Yang T, Colecraft HM. Regulation of voltage-dependent calcium channels by RGK proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:1644-54. [PMID: 23063948 DOI: 10.1016/j.bbamem.2012.10.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 10/04/2012] [Accepted: 10/05/2012] [Indexed: 12/28/2022]
Abstract
RGK proteins belong to the Ras superfamily of monomeric G-proteins, and currently include four members - Rad, Rem, Rem2, and Gem/Kir. RGK proteins are broadly expressed, and are the most potent known intracellular inhibitors of high-voltage-activated Ca²⁺ (Ca(V)1 and Ca(V)2) channels. Here, we review and discuss the evidence in the literature regarding the functional mechanisms, structural determinants, physiological role, and potential practical applications of RGK-mediated inhibition of Ca(V)1/Ca(V)2 channels. This article is part of a Special Issue entitled: Calcium channels.
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Affiliation(s)
- Tingting Yang
- Department of Physiology and Cellular Biophysics, Columbia University, College of Physicians and Surgeons, 1150 St. Nicholas Avenue, New York, NY 10032, USA
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327
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CaMKII determines mitochondrial stress responses in heart. Nature 2012; 491:269-73. [PMID: 23051746 PMCID: PMC3471377 DOI: 10.1038/nature11444] [Citation(s) in RCA: 322] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Accepted: 07/26/2012] [Indexed: 12/17/2022]
Abstract
Myocardial cell death is initiated by excessive mitochondrial Ca2+ entry, causing Ca2+ overload, mitochondrial permeability transition pore (mPTP) opening and dissipation of the mitochondrial inner membrane potential (ΔΨm)1,2. However, the signaling pathways that control mitochondrial Ca2+ entry through the inner membrane mitochondrial Ca2+ uniporter (MCU)3–5 are not known. The multifunctional Ca2+ and calmodulin-dependent protein kinase II (CaMKII) is activated in ischemia reperfusion (I/R), myocardial infarction (MI) and neurohumoral injury, common causes of myocardial death and heart failure, suggesting CaMKII could couple disease stress to mitochondrial injury. Here we show that CaMKII promotes mPTP opening and myocardial death by increasing MCU current (IMCU). Mitochondrial-targeted CaMKII inhibitory protein or cyclosporin A (CsA), an mPTP antagonist with clinical efficacy in I/R injury6, equivalently prevent mPTP opening, ΔΨm deterioration and diminish mitochondrial disruption and programmed cell death in response to I/R injury. Mice with myocardial and mitochondrial-targeted CaMKII inhibition are resistant to I/R injury, MI and neurohumoral injury, suggesting pathological actions of CaMKII are substantially mediated by increasing IMCU. Our findings identify CaMKII activity as a central mechanism for mitochondrial Ca2+ entry and suggest mitochondrial-targeted CaMKII inhibition could prevent or reduce myocardial death and heart failure dysfunction in response to common experimental forms of pathophysiological stress.
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328
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Ruiz-Hurtado G, Gómez-Hurtado N, Fernández-Velasco M, Calderón E, Smani T, Ordoñez A, Cachofeiro V, Boscá L, Díez J, Gómez AM, Delgado C. Cardiotrophin-1 induces sarcoplasmic reticulum Ca(2+) leak and arrhythmogenesis in adult rat ventricular myocytes. Cardiovasc Res 2012; 96:81-9. [PMID: 22787135 DOI: 10.1093/cvr/cvs234] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
AIMS Plasma levels of cardiotrophin-1 (CT-1) are elevated in several cardiovascular diseases and are correlated with the severity of the pathology. However, the mechanisms by which this inflammatory cytokine participates in the pathology of the heart are not completely understood. It is well established that alterations in intracellular calcium ([Ca(2+)](i)) handling are involved in cardiac dysfunction during heart failure, but it is unknown whether CT-1 modulates [Ca(2+)](i) handling in adult cardiomyocytes. Here we have analyzed for the first time the effects of CT-1 on [Ca(2+)](i) homeostasis in adult rat cardiomyocytes. METHODS AND RESULTS L-type calcium current (I(CaL)) was recorded using patch-clamp techniques, and [Ca(2+)](i) transients and Ca(2+) sparks were viewed by confocal microscopy. Treatment of cardiomyocytes with 1 nM CT-1 for 20-60 min induced a significant increase in I(CaL) density, [Ca(2+)](i) transients, and cell shortening compared with control cells. Our study reveals that CT-1 increases I(CaL) by a protein kinase A-dependent mechanism, and Ca(2+) sparks by a Ca(2+)/calmodulin kinase II-dependent and protein kinase A-independent mechanism. Cardiomyocytes treated with CT-1 exhibited a higher occurrence of arrhythmogenic behaviour, manifested as spontaneous Ca(2+) waves and aftercontractions. CONCLUSION Our findings provide evidence that cardiomyocytes treated with CT-1 present high spontaneous Ca(2+) release during diastole, a mechanism linked to arrhythmogenicity in the pathologic heart.
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Affiliation(s)
- Gema Ruiz-Hurtado
- Inserm, U769, IFR141, Labex Lermit, Université Paris 11, Chatenay-Malabry, France
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329
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Dallas ML, Yang Z, Boyle JP, Boycott HE, Scragg JL, Milligan CJ, Elies J, Duke A, Thireau J, Reboul C, Richard S, Bernus O, Steele DS, Peers C. Carbon monoxide induces cardiac arrhythmia via induction of the late Na+ current. Am J Respir Crit Care Med 2012; 186:648-56. [PMID: 22822026 PMCID: PMC3622900 DOI: 10.1164/rccm.201204-0688oc] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 07/10/2012] [Indexed: 11/16/2022] Open
Abstract
RATIONALE Clinical reports describe life-threatening cardiac arrhythmias after environmental exposure to carbon monoxide (CO) or accidental CO poisoning. Numerous case studies describe disruption of repolarization and prolongation of the QT interval, yet the mechanisms underlying CO-induced arrhythmias are unknown. OBJECTIVES To understand the cellular basis of CO-induced arrhythmias and to identify an effective therapeutic approach. METHODS Patch-clamp electrophysiology and confocal Ca(2+) and nitric oxide (NO) imaging in isolated ventricular myocytes was performed together with protein S-nitrosylation to investigate the effects of CO at the cellular and molecular levels, whereas telemetry was used to investigate effects of CO on electrocardiogram recordings in vivo. MEASUREMENTS AND MAIN RESULTS CO increased the sustained (late) component of the inward Na(+) current, resulting in prolongation of the action potential and the associated intracellular Ca(2+) transient. In more than 50% of myocytes these changes progressed to early after-depolarization-like arrhythmias. CO elevated NO levels in myocytes and caused S-nitrosylation of the Na(+) channel, Na(v)1.5. All proarrhythmic effects of CO were abolished by the NO synthase inhibitor l-NAME, and reversed by ranolazine, an inhibitor of the late Na(+) current. Ranolazine also corrected QT variability and arrhythmias induced by CO in vivo, as monitored by telemetry. CONCLUSIONS Our data indicate that the proarrhythmic effects of CO arise from activation of NO synthase, leading to NO-mediated nitrosylation of Na(V)1.5 and to induction of the late Na(+) current. We also show that the antianginal drug ranolazine can abolish CO-induced early after-depolarizations, highlighting a novel approach to the treatment of CO-induced arrhythmias.
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Affiliation(s)
- Mark L. Dallas
- Division of Cardiovascular Medicine, Faculty of Medicine and Health, and
| | - Zhaokang Yang
- Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - John P. Boyle
- Division of Cardiovascular Medicine, Faculty of Medicine and Health, and
| | - Hannah E. Boycott
- Division of Cardiovascular Medicine, Faculty of Medicine and Health, and
| | - Jason L. Scragg
- Division of Cardiovascular Medicine, Faculty of Medicine and Health, and
| | - Carol J. Milligan
- Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Jacobo Elies
- Division of Cardiovascular Medicine, Faculty of Medicine and Health, and
| | - Adrian Duke
- Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Jérôme Thireau
- Inserm U1046, Physiologie et Médecine Expérimentale du Coeur et des Muscles, CHU Arnaud de Villeneuve, Montpellier, France; and
| | - Cyril Reboul
- Laboratoire de Pharm-écologie Cardiovasculaire, Faculté des Sciences, Avignon, France
| | - Sylvain Richard
- Inserm U1046, Physiologie et Médecine Expérimentale du Coeur et des Muscles, CHU Arnaud de Villeneuve, Montpellier, France; and
| | - Olivier Bernus
- Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Derek S. Steele
- Institute of Membrane and Systems Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Chris Peers
- Division of Cardiovascular Medicine, Faculty of Medicine and Health, and
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Ryanodine receptor phosphorylation, calcium/calmodulin-dependent protein kinase II, and life-threatening ventricular arrhythmias. Trends Cardiovasc Med 2012; 21:48-51. [PMID: 22578240 DOI: 10.1016/j.tcm.2012.02.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ryanodine receptor (RyR2) dysfunction, which may result from a variety of mechanisms, has been implicated in the pathogenesis of cardiac arrhythmias and heart failure. In this review, we discuss the important role of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) in the regulation of RyR2-mediated Ca(2+) release. In particular, we examine how pathological activation of CaMKII can lead to an increased risk of sudden arrhythmic death. Finally, we discuss how reduction of CaMKII-mediated RyR2 hyperactivity might reduce the risk of arrhythmias and may serve as a rationale for future pharmacotherapeutic approaches.
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331
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Wen H, Gwathmey JK, Xie LH. Oxidative stress-mediated effects of angiotensin II in the cardiovascular system. World J Hypertens 2012; 2:34-44. [PMID: 24587981 PMCID: PMC3936474 DOI: 10.5494/wjh.v2.i4.34] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Angiotensin II (Ang II), an endogenous peptide hormone, plays critical roles in the pathophysiological modulation of cardiovascular functions. Ang II is the principle effector of the renin-angiotensin system for maintaining homeostasis in the cardiovascular system, as well as a potent stimulator of NAD(P)H oxidase, which is the major source and primary trigger for reactive oxygen species (ROS) generation in various tissues. Recent accumulating evidence has demonstrated the importance of oxidative stress in Ang II-induced heart diseases. Here, we review the recent progress in the study on oxidative stress-mediated effects of Ang II in the cardiovascular system. In particular, the involvement of Ang II-induced ROS generation in arrhythmias, cell death/heart failure, ischemia/reperfusion injury, cardiac hypertrophy and hypertension are discussed. Ca2+/calmodulin-dependent protein kinase II is an important molecule linking Ang II, ROS and cardiovascular pathological conditions.
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332
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Xu M, Wu HD, Li RC, Zhang HB, Wang M, Tao J, Feng XH, Guo YB, Li SF, Lai ST, Zhou P, Li LL, Yang HQ, Luo GZ, Bai Y, Xi JJ, Gao W, Han QD, Zhang YY, Wang XJ, Meng X, Wang SQ. Mir-24 regulates junctophilin-2 expression in cardiomyocytes. Circ Res 2012; 111:837-41. [PMID: 22891046 DOI: 10.1161/circresaha.112.277418] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
RATIONALE Failing cardiomyocytes exhibit decreased efficiency of excitation-contraction (E-C) coupling. The downregulation of junctophilin-2 (JP2), a protein anchoring the sarcoplasmic reticulum to T-tubules, has been identified as a major mechanism underlying the defective E-C coupling. However, the regulatory mechanism of JP2 remains unknown. OBJECTIVE To determine whether microRNAs regulate JP2 expression. METHODS AND RESULTS Bioinformatic analysis predicted 2 potential binding sites of miR-24 in the 3'-untranslated regions of JP2 mRNA. Luciferase assays confirmed that miR-24 suppressed JP2 expression by binding to either of these sites. In the aortic stenosis model, miR-24 was upregulated in failing cardiomyocytes. Adenovirus-directed overexpression of miR-24 in cardiomyocytes decreased JP2 expression and reduced Ca(2+) transient amplitude and E-C coupling gain. CONCLUSIONS MiR-24-mediated suppression of JP2 expression provides a novel molecular mechanism for E-C coupling regulation in heart cells and suggests a new target against heart failure.
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Affiliation(s)
- Ming Xu
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Third Hospital, College of Engineering and College of Life Sciences, Peking University, China
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Miyamoto SD, Stauffer BL, Nakano S, Sobus R, Nunley K, Nelson P, Sucharov CC. Beta-adrenergic adaptation in paediatric idiopathic dilated cardiomyopathy. Eur Heart J 2012; 35:33-41. [PMID: 22843448 DOI: 10.1093/eurheartj/ehs229] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Although the pathophysiology and treatment of adult heart failure (HF) are well studied, HF in children remains poorly understood. In adults, adrenergic receptor (AR)-mediated adaptation plays a central role in cardiac abnormalities in HF, and these patients respond well to β-blocker (BB) therapy. However, in children with HF, there is a growing body of literature suggesting a lack of efficacy of adult HF therapies. Due to these unanticipated differences in response to therapy and the paucity of data regarding the molecular adaptation of the paediatric heart, we investigated the molecular characteristics of HF in children. METHODS AND RESULTS Explanted hearts from adults and children with idiopathic dilated cardiomyopathy and non-failing controls were used in the study. Our results show that the molecular characteristics of paediatric HF are strikingly different from their adult counterparts. These differences include: (i) down-regulation of β1- and β2-AR in children, whereas β2-AR expression is maintained in adults; (ii) up-regulation of connexin43 in children, whereas down-regulation is observed in adults; (iii) no differences in phosphatase expression, whereas up-regulation is observed in adults; (iv) no decrease in the phosphorylation of phospholamban at the Ser16 or Thr17 sites in children, which are known characteristics of adult HF. CONCLUSION There is a different adaptation of β-AR and adrenergic signalling pathways in children with HF compared with adults. Our results begin to address the disparities in cardiovascular research specific to children and suggest that age-related differences in adaptation could influence the response to therapy. These findings could lead to a paradigm shift in the contemporary management of children with HF.
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Affiliation(s)
- Shelley D Miyamoto
- Department of Pediatrics, University of Colorado School of Medicine, Children's Hospital Colorado, Aurora, CO, USA
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335
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Nuclear inositol 1,4,5-trisphosphate is a necessary and conserved signal for the induction of both pathological and physiological cardiomyocyte hypertrophy. J Mol Cell Cardiol 2012; 53:475-86. [PMID: 22766271 DOI: 10.1016/j.yjmcc.2012.06.017] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 06/20/2012] [Accepted: 06/21/2012] [Indexed: 01/08/2023]
Abstract
It is well established that inositol 1,4,5-trisphosphate (IP3) dependent Ca(2+) signaling plays a crucial role in cardiomyocyte hypertrophy. However, it is not yet known whether nuclear IP3 represents a Ca(2+) mobilizing pathway involved in this process. The goal of the current work was to investigate the specific role of nuclear IP3 in cardiomyocyte hypertrophic response. In this work, we used an adenovirus construct that selectively buffers IP3 in the nuclear region of neonatal cardiomyocytes. We showed for the first time that nuclear IP3 mediates endothelin-1 (ET-1) induced hypertrophy. We also found that both calcineurin (Cn)/nuclear factor of activated T Cells (NFAT) and histone deacetylase-5 (HDAC5) pathways require nuclear IP3 to mediate pathological cardiomyocyte growth. Additionally, we found that nuclear IP3 buffering inhibited insulin-like growth factor-1 (IGF-1) induced hypertrophy and prevented reexpression of fetal gene program. Together, these results demonstrated that nuclear IP3 is an essential and a conserved signal for both pathological and physiological forms of cardiomyocyte hypertrophy.
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336
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Haworth RS, Stathopoulou K, Candasamy AJ, Avkiran M. Neurohormonal regulation of cardiac histone deacetylase 5 nuclear localization by phosphorylation-dependent and phosphorylation-independent mechanisms. Circ Res 2012; 110:1585-95. [PMID: 22581927 DOI: 10.1161/circresaha.111.263665] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Myocyte enhancer factor 2 (MEF2) transcription factors drive the genetic reprogramming that precipitates pathological cardiac hypertrophy and remodeling. Class II histone deacetylase (HDAC) isoforms, such as HDAC5, act as signal-responsive repressors of MEF2 activity in cardiac myocytes and their nuclear export provides a key mechanism for the neurohormonal induction of such activity. OBJECTIVE To delineate the mechanism(s) through which 2 clinically relevant neurohormonal stimuli, endothelin-1 (ET1) and the β-adrenergic receptor (β-AR) agonist isoproterenol (ISO), may regulate HDAC5 nuclear localization in adult cardiac myocytes. METHODS AND RESULTS ET1 induced HDAC5 phosphorylation and nuclear export in ventricular myocytes from the adult rat heart. Use of a novel, highly selective protein kinase D (PKD) inhibitor and a nonphosphorylatable HDAC5 mutant revealed that PKD-mediated phosphorylation was necessary for ET1-induced HDAC5 nuclear export. In contrast, ISO reduced HDAC5 phosphorylation in the presence or absence of ET1 but still induced HDAC5 nuclear export. ISO-induced HDAC5 nuclear export occurred through a β(1)-AR-mediated oxidative process that was independent of PKD, protein kinase A, and Ca(2+)/calmodulin-dependent kinase II activities. Although ET1 and ISO shared a similar ability to induce HDAC5 nuclear export, albeit through distinct phosphorylation-dependent versus phosphorylation-independent mechanisms, ISO induced a significantly greater increase in MEF2 activity. CONCLUSIONS PKD-mediated HDAC5 phosphorylation and nuclear export are unlikely to be of major importance in regulating MEF2-driven cardiac remodeling in the presence of sympathetic activity with intact β(1)-AR signaling, which would not only counteract HDAC5 phosphorylation but also induce HDAC5 nuclear export through a novel phosphorylation-independent, oxidation-mediated mechanism. Inhibition of this mechanism may contribute to the therapeutic efficacy of β(1)-AR antagonists in heart failure.
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Affiliation(s)
- Robert S Haworth
- Cardiovascular Division, King's College London, The Rayne Institute, St Thomas' Hospital, London SE1 7EH, UK
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337
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Ashpole NM, Herren AW, Ginsburg KS, Brogan JD, Johnson DE, Cummins TR, Bers DM, Hudmon A. Ca2+/calmodulin-dependent protein kinase II (CaMKII) regulates cardiac sodium channel NaV1.5 gating by multiple phosphorylation sites. J Biol Chem 2012; 287:19856-69. [PMID: 22514276 DOI: 10.1074/jbc.m111.322537] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The cardiac Na(+) channel Na(V)1.5 current (I(Na)) is critical to cardiac excitability, and altered I(Na) gating has been implicated in genetic and acquired arrhythmias. Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) is up-regulated in heart failure and has been shown to cause I(Na) gating changes that mimic those induced by a point mutation in humans that is associated with combined long QT and Brugada syndromes. We sought to identify the site(s) on Na(V)1.5 that mediate(s) the CaMKII-induced alterations in I(Na) gating. We analyzed both CaMKII binding and CaMKII-dependent phosphorylation of the intracellularly accessible regions of Na(V)1.5 using a series of GST fusion constructs, immobilized peptide arrays, and soluble peptides. A stable interaction between δ(C)-CaMKII and the intracellular loop between domains 1 and 2 of Na(V)1.5 was observed. This region was also phosphorylated by δ(C)-CaMKII, specifically at the Ser-516 and Thr-594 sites. Wild-type (WT) and phosphomutant hNa(V)1.5 were co-expressed with GFP-δ(C)-CaMKII in HEK293 cells, and I(Na) was recorded. As observed in myocytes, CaMKII shifted WT I(Na) availability to a more negative membrane potential and enhanced accumulation of I(Na) into an intermediate inactivated state, but these effects were abolished by mutating either of these sites to non-phosphorylatable Ala residues. Mutation of these sites to phosphomimetic Glu residues negatively shifted I(Na) availability without the need for CaMKII. CaMKII-dependent phosphorylation of Na(V)1.5 at multiple sites (including Thr-594 and Ser-516) appears to be required to evoke loss-of-function changes in gating that could contribute to acquired Brugada syndrome-like effects in heart failure.
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Affiliation(s)
- Nicole M Ashpole
- Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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338
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Maier LS. Ca2+/Calmodulin-Dependent Protein Kinase II (CaMKII) in the Heart. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:685-702. [DOI: 10.1007/978-94-007-2888-2_30] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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339
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Vagnozzi RJ, Hoffman NE, Elrod JW, Madesh M, Force T. Protein Kinase Signaling at the Crossroads of Myocyte Life and Death in Ischemic Heart Disease. ACTA ACUST UNITED AC 2012; 9:e173-e182. [PMID: 24839450 DOI: 10.1016/j.ddstr.2013.12.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Myocardial ischemia results in death of cardiac myocytes via tightly-regulated and interconnected signaling pathways. Protein kinases play crucial roles in this regulation and are highly amenable to therapeutic intervention, making targeted inhibition an attractive strategy for ischemic heart disease. Recent studies have uncovered numerous kinases that participate in the cardiomyocyte response to ischemic injury, thus potentiating the development of new therapeutics. Moreover, many kinase signaling pathways converge at the mitochondria, a key participant in both cardiomyocyte physiology and the pathogenesis of ischemic heart disease. Herein we highlight kinase pathways regulating three major drivers of cell death: mitochondrial permeability transition pore opening (mPTP), programmed necrosis and Ca2+ overload-induced mitochondrial dysfunction. Inhibition of each of these kinase pathways has been proposed as a means to limit cardiomyocyte death from ischemia/reperfusion (I/R) injury.
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Affiliation(s)
- Ronald J Vagnozzi
- Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3026, USA
| | - Nicholas E Hoffman
- Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3026, USA
| | - John W Elrod
- Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3026, USA
| | - Muniswamy Madesh
- Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3026, USA
| | - Thomas Force
- Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3026, USA
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340
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Christel C, Lee A. Ca2+-dependent modulation of voltage-gated Ca2+ channels. Biochim Biophys Acta Gen Subj 2011; 1820:1243-52. [PMID: 22223119 DOI: 10.1016/j.bbagen.2011.12.012] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2011] [Revised: 12/15/2011] [Accepted: 12/16/2011] [Indexed: 01/06/2023]
Abstract
BACKGROUND Voltage-gated (Cav) Ca2+ channels are multi-subunit complexes that play diverse roles in a wide variety of tissues. A fundamental mechanism controlling Cav channel function involves the Ca2+ ions that permeate the channel pore. Ca2+ influx through Cav channels mediates feedback regulation to the channel that is both negative (Ca2+-dependent inactivation, CDI) and positive (Ca2+-dependent facilitation, CDF). SCOPE OF REVIEW This review highlights general mechanisms of CDI and CDF with an emphasis on how these processes have been studied electrophysiologically in native and heterologous expression systems. MAJOR CONCLUSIONS Electrophysiological analyses have led to detailed insights into the mechanisms and prevalence of CDI and CDF as Cav channel regulatory mechanisms. All Cav channel family members undergo some form of Ca2+-dependent feedback that relies on CaM or a related Ca2+ binding protein. Tremendous progress has been made in characterizing the role of CaM in CDI and CDF. Yet, what contributes to the heterogeneity of CDI/CDF in various cell-types and how Ca2+-dependent regulation of Cav channels controls Ca2+ signaling remain largely unexplored. GENERAL SIGNIFICANCE Ca2+ influx through Cav channels regulates diverse physiological events including excitation-contraction coupling in muscle, neurotransmitter and hormone release, and Ca2+-dependent gene transcription. Therefore, the mechanisms that regulate channels, such as CDI and CDF, can have a large impact on the signaling potential of excitable cells in various physiological contexts. This article is part of a Special Issue entitled Biochemical, biophysical and genetic approaches to intracellular calcium signaling.
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Affiliation(s)
- Carl Christel
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA
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341
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Alternative strategies in arrhythmia therapy: evaluation of Na/Ca exchange as an anti-arrhythmic target. Pharmacol Ther 2011; 134:26-42. [PMID: 22197992 DOI: 10.1016/j.pharmthera.2011.12.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 11/22/2011] [Accepted: 11/22/2011] [Indexed: 01/08/2023]
Abstract
The search for alternative anti-arrhythmic strategies is fueled by an unmet medical need as well as by the opportunities arising from identification of novel targets and novel drugs. Na/Ca exchange is a potential target involved in several types of arrhythmias, such as those related to ischemia-reperfusion, heart failure and also some forms of genetic arrhythmias. Inhibition of Na/Ca exchange is theoretically not only anti-arrhythmic but also increases cellular Ca(2+) content. This could be an advantage in conditions of low inotropy, such as in heart failure, but may also worsen conditions such as the recovery from ischemia or relaxation abnormalities. With the available drugs such as KB-R7943 and SEA-0400 these theories have now been tested in a number of cellular and in vivo models. Experience is overall rather positive and seems less hampered by the potential drawbacks than expected. This may be because the currently available drugs are not highly selective, with additional benefit derived from concurrent effects. While this precludes a definite answer regarding the benefit of a pure NCX inhibitor, they indicate that Na/Ca exchange inhibition as part of a multi-target strategy is an avenue to be considered. Such studies will need further 'bench' work and testing in relevant preclinical models, including chronic disease.
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342
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Abstract
Heart failure (HF) involves changes in cardiac structure, myocardial composition, myocyte deformation, and multiple biochemical and molecular alterations that impact heart function and reserve capacity. Collectively, these changes have been referred to as 'cardiac remodeling'. Understanding the components of this process with the goal of stopping or reversing its progression has become a major objective. This concept is often termed 'reverse remodeling', and is successfully achieved by inhibitors of the renin-angiotensin-aldosterone system, β-blockers, and device therapies such as cardiac resynchronization or ventricular assist devices. Not every method of reverse remodeling has long-lasting clinical efficacy. However, thus far, every successful clinical treatment with long-term benefits on the morbidity and mortality of patients with HF reverses remodeling. Reverse remodeling is defined by lower chamber volumes (particularly end-systolic volume) and is often accompanied by improved β-adrenergic and heart-rate responsiveness. At the cellular level, reverse remodeling impacts on myocyte size, function, excitation-contraction coupling, bioenergetics, and a host of molecular pathways that regulate contraction, cell survival, mitochondrial function, oxidative stress, and other features. Here, we review the current evidence for reverse remodeling by existing therapies, and discuss novel approaches that are rapidly moving from preclinical to clinical trials.
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343
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Hong TT, Smyth JW, Chu KY, Vogan JM, Fong TS, Jensen BC, Fang K, Halushka MK, Russell SD, Colecraft H, Hoopes CW, Ocorr K, Chi NC, Shaw RM. BIN1 is reduced and Cav1.2 trafficking is impaired in human failing cardiomyocytes. Heart Rhythm 2011; 9:812-20. [PMID: 22138472 DOI: 10.1016/j.hrthm.2011.11.055] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2011] [Indexed: 10/14/2022]
Abstract
BACKGROUND Heart failure is a growing epidemic, and a typical aspect of heart failure pathophysiology is altered calcium transients. Normal cardiac calcium transients are initiated by Cav1.2 channels at cardiac T tubules. Bridging integrator 1 (BIN1) is a membrane scaffolding protein that causes Cav1.2 to traffic to T tubules in healthy hearts. The mechanisms of Cav1.2 trafficking in heart failure are not known. OBJECTIVE To study BIN1 expression and its effect on Cav1.2 trafficking in failing hearts. METHODS Intact myocardium and freshly isolated cardiomyocytes from nonfailing and end-stage failing human hearts were used to study BIN1 expression and Cav1.2 localization. To confirm Cav1.2 surface expression dependence on BIN1, patch-clamp recordings were performed of Cav1.2 current in cell lines with and without trafficking-competent BIN1. Also, in adult mouse cardiomyocytes, surface Cav1.2 and calcium transients were studied after small hairpin RNA-mediated knockdown of BIN1. For a functional readout in intact heart, calcium transients and cardiac contractility were analyzed in a zebrafish model with morpholino-mediated knockdown of BIN1. RESULTS BIN1 expression is significantly decreased in failing cardiomyocytes at both mRNA (30% down) and protein (36% down) levels. Peripheral Cav1.2 is reduced to 42% by imaging, and a biochemical T-tubule fraction of Cav1.2 is reduced to 68%. The total calcium current is reduced to 41% in a cell line expressing a nontrafficking BIN1 mutant. In mouse cardiomyocytes, BIN1 knockdown decreases surface Cav1.2 and impairs calcium transients. In zebrafish hearts, BIN1 knockdown causes a 75% reduction in calcium transients and severe ventricular contractile dysfunction. CONCLUSIONS The data indicate that BIN1 is significantly reduced in human heart failure, and this reduction impairs Cav1.2 trafficking, calcium transients, and contractility.
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Affiliation(s)
- Ting-Ting Hong
- Cardiovascular Research Institute, University of California, San Francisco, CA, USA
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344
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Song YH, Choi E, Park SH, Lee SH, Cho H, Ho WK, Ryu SY. Sustained CaMKII activity mediates transient oxidative stress-induced long-term facilitation of L-type Ca(2+) current in cardiomyocytes. Free Radic Biol Med 2011; 51:1708-16. [PMID: 21854842 DOI: 10.1016/j.freeradbiomed.2011.07.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2011] [Revised: 07/27/2011] [Accepted: 07/28/2011] [Indexed: 11/17/2022]
Abstract
Oxidative stress remodels Ca(2+) signaling in cardiomyocytes, which promotes altered heart function in various heart diseases. Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) was shown to be activated by oxidation, but whether and how CaMKII links oxidative stress to pathophysiological long-term changes in Ca(2+) signaling remain unknown. Here, we present evidence demonstrating the role of CaMKII in transient oxidative stress-induced long-term facilitation (LTF) of L-type Ca(2+) current (I(Ca,L)) in rat cardiomyocytes. A 5-min exposure of 1mM H(2)O(2) induced an increase in I(Ca,L), and this increase was sustained for ~1h. The CaMKII inhibitor KN-93 fully reversed H(2)O(2)-induced LTF of I(Ca,L), indicating that sustained CaMKII activity underlies this oxidative stress-induced memory. Simultaneous inhibition of oxidation and autophosphorylation of CaMKII prevented the maintenance of LTF, suggesting that both mechanisms contribute to sustained CaMKII activity. We further found that sarcoplasmic reticulum Ca(2+) release and mitochondrial ROS generation have critical roles in sustaining CaMKII activity via autophosphorylation- and oxidation-dependent mechanisms. Finally, we show that long-term remodeling of the cardiac action potential is induced by H(2)O(2) via CaMKII. In conclusion, CaMKII and mitochondria confer oxidative stress-induced pathological cellular memory that leads to cardiac arrhythmia.
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Affiliation(s)
- Young-Hwan Song
- Department of Pediatrics, Sanggye Paik Hospital, Inje University College of Medicine, Seoul 139-707, Republic of Korea
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345
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Simpson PC. Where are the new drugs to treat heart failure? Introduction to the special issue on "key signaling molecules in hypertrophy and heart failure". J Mol Cell Cardiol 2011; 51:435-7. [PMID: 21851824 DOI: 10.1016/j.yjmcc.2011.08.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Accepted: 08/10/2011] [Indexed: 12/30/2022]
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346
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Erickson JR, Patel R, Ferguson A, Bossuyt J, Bers DM. Fluorescence resonance energy transfer-based sensor Camui provides new insight into mechanisms of calcium/calmodulin-dependent protein kinase II activation in intact cardiomyocytes. Circ Res 2011; 109:729-38. [PMID: 21835909 DOI: 10.1161/circresaha.111.247148] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Calcium/calmodulin-dependent protein kinase II (CaMKII) is a key mediator of intracellular signaling in the heart. However, the tools currently available for assessing dynamic changes in CaMKII localization and activation in living myocytes are limited. OBJECTIVE We use Camui, a novel FRET-based biosensor in which full-length CaMKII is flanked by CFP and YFP, to measure CaMKII activation state in living rabbit myocytes. METHODS AND RESULTS We show that Camui and mutant variants that lack the sites of CaMKII autophosphorylation (T286A) and oxidative regulation (CM280/1VV) serve as useful biosensors for CaMKIIδ activation state. Camui (wild-type or mutant) was expressed in isolated adult cardiac myocytes, and localization and CaMKII activation state were determined using confocal microscopy. Camui, like CaMKIIδ, is concentrated at the z-lines, with low baseline activation state. Camui activation increased directly with pacing frequency, but the maximal effect was blunted with the T286A, consistent with frequency-dependent phosphorylation of CaMKII at T286 mainly at high-frequency and high-amplitude Ca transients. Camui was also activated by 4 neurohormonal agonists. Angiotensin II and endothelin-1 activated Camui, largely through an oxidation-dependent mechanism, whereas isoproterenol- and phenylephrine-mediated mechanisms had a significant autophosphorylation-dependent component. CONCLUSIONS Camui is a novel, nondestructive tool that allows spatiotemporally resolved measurement of CaMKII activation state in physiologically functioning myocytes. This represents a first step in using Camui to elucidate key mechanistic details of CaMKII signaling in live hearts and myocytes.
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Affiliation(s)
- Jeffrey R Erickson
- Department of Pharmacology, University of California, Davis, CA 95616-8636, USA
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347
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Abstract
Ischemic insults on neurons trigger excessive, pathological glutamate release that causes Ca²⁺ overload resulting in neuronal cell death (excitotoxicity). The Ca²⁺/calmodulin (CaM)-dependent protein kinase II (CaMKII) is a major mediator of physiological excitatory glutamate signals underlying neuronal plasticity and learning. Glutamate stimuli trigger autophosphorylation of CaMKII at T286, a process that makes the kinase "autonomous" (partially active independent from Ca²⁺ stimulation) and that is required for forms of synaptic plasticity. Recent studies suggested autonomous CaMKII activity also as potential drug target for post-insult neuroprotection, both after glutamate insults in neuronal cultures and after focal cerebral ischemia in vivo. However, CaMKII and other members of the CaM kinase family have been implicated in regulation of both neuronal death and survival. Here, we discuss past findings and possible mechanisms of CaM kinase functions in excitotoxicity and cerebral ischemia, with a focus on CaMKII and its regulation.
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348
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Grimm M, Ling H, Brown JH. Crossing signals: relationships between β-adrenergic stimulation and CaMKII activation. Heart Rhythm 2011; 8:1296-8. [PMID: 21354330 DOI: 10.1016/j.hrthm.2011.02.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Accepted: 02/18/2011] [Indexed: 11/28/2022]
Affiliation(s)
- Michael Grimm
- Department of Pharmacology, University of California San Diego, La Jolla California, USA
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