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Marian AJ, Asatryan B, Wehrens XHT. Genetic basis and molecular biology of cardiac arrhythmias in cardiomyopathies. Cardiovasc Res 2021; 116:1600-1619. [PMID: 32348453 DOI: 10.1093/cvr/cvaa116] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 03/09/2020] [Accepted: 04/21/2020] [Indexed: 12/19/2022] Open
Abstract
Cardiac arrhythmias are common, often the first, and sometimes the life-threatening manifestations of hereditary cardiomyopathies. Pathogenic variants in several genes known to cause hereditary cardiac arrhythmias have also been identified in the sporadic cases and small families with cardiomyopathies. These findings suggest a shared genetic aetiology of a subset of hereditary cardiomyopathies and cardiac arrhythmias. The concept of a shared genetic aetiology is in accord with the complex and exquisite interplays that exist between the ion currents and cardiac mechanical function. However, neither the causal role of cardiac arrhythmias genes in cardiomyopathies is well established nor the causal role of cardiomyopathy genes in arrhythmias. On the contrary, secondary changes in ion currents, such as post-translational modifications, are common and contributors to the pathogenesis of arrhythmias in cardiomyopathies through altering biophysical and functional properties of the ion channels. Moreover, structural changes, such as cardiac hypertrophy, dilatation, and fibrosis provide a pro-arrhythmic substrate in hereditary cardiomyopathies. Genetic basis and molecular biology of cardiac arrhythmias in hereditary cardiomyopathies are discussed.
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Affiliation(s)
- Ali J Marian
- Department of Medicine, Center for Cardiovascular Genetics, Institute of Molecular Medicine, University of Texas Health Sciences Center at Houston, 6770 Bertner Street, Suite C900A, Houston, TX 77030, USA
| | - Babken Asatryan
- Department of Cardiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Xander H T Wehrens
- Department of Biophysics and Molecular Physiology, Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX 77030, USA
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2
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Stress-driven cardiac calcium mishandling via a kinase-to-kinase crosstalk. Pflugers Arch 2021; 473:363-375. [PMID: 33590296 PMCID: PMC7940337 DOI: 10.1007/s00424-021-02533-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 01/19/2021] [Accepted: 02/02/2021] [Indexed: 01/25/2023]
Abstract
Calcium homeostasis in the cardiomyocyte is critical to the regulation of normal cardiac function. Abnormal calcium dynamics such as altered uptake by the sarcoplasmic reticulum (SR) Ca2+-ATPase and increased diastolic SR calcium leak are involved in the development of maladaptive cardiac remodeling under pathological conditions. Ca2+/calmodulin-dependent protein kinase II-δ (CaMKIIδ) is a well-recognized key molecule in calcium dysregulation in cardiomyocytes. Elevated cellular stress is known as a common feature during pathological remodeling, and c-jun N-terminal kinase (JNK) is an important stress kinase that is activated in response to intrinsic and extrinsic stress stimuli. Our lab recently identified specific actions of JNK isoform 2 (JNK2) in CaMKIIδ expression, activation, and CaMKIIδ-dependent SR Ca2+ mishandling in the stressed heart. This review focuses on the current understanding of cardiac SR calcium handling under physiological and pathological conditions as well as the newly identified contribution of the stress kinase JNK2 in CaMKIIδ-dependent SR Ca2+ abnormal mishandling. The new findings identifying dual roles of JNK2 in CaMKIIδ expression and activation are also discussed in this review.
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3
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Li S, Li P, Liu W, Shang J, Qiu S, Li X, Liu W, Shi H, Zhou M, Liu H. Danhong Injection Alleviates Cardiac Fibrosis via Preventing the Hypermethylation of Rasal1 and Rassf1 in TAC Mice. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:3158108. [PMID: 33456666 PMCID: PMC7787771 DOI: 10.1155/2020/3158108] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 12/02/2020] [Accepted: 12/06/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND/AIM Danhong injection (DHI) is a Chinese patent drug used for relieving cardiovascular diseases. Recent studies have suggested that DNA methylation plays a pivotal role in the maintenance of cardiac fibrosis (CF) in cardiovascular diseases. This study was aimed at identifying the effect and the underlying mechanism of DHI on CF, especially the DNA methylation. METHODS A CF murine model was established by thoracic aortic constriction (TAC). A 28-day daily treatment with or without DHI via intraperitoneal injection was carried out immediately following TAC surgery. The changes in cardiac function, pathology, and fibrosis following TAC were measured by echocardiography and immunostaining. We used methyl-seq analysis to assess the DNA methylation changes in whole genes and identified the methylation changes of two Ras signaling-related genes in TAC mice, including Ras protein activator like-1 (Rasal1) and Ras-association domain family 1 (Rassf1). Next, the methylation status and expression levels of Rasal1 and Rassf1 genes were consolidated by bisulfite sequencing, quantitative reverse transcription polymerase chain reaction (RT-qPCR), and Western blotting, respectively. To determine the underlying molecular mechanism, the expressions of DNA methyltransferases (DNMTs), Tet methylcytosine dioxygenase 3 (TET3), fibrosis-related genes, and the activity of Ras/ERK were measured by RT-qPCR and Western blotting. RESULTS DHI treatment alleviated CF and significantly improved cardiac function on day 28 of TAC. The methyl-seq analysis identified 42,606 differential methylated sites (DMSs), including 19,618 hypermethylated DMSs and 22,988 hypomethylated DMSs between TAC and sham-operated mice. The enrichment analysis of these DMSs suggested that the methylated regulation of Ras signal transduction and focal adhesion-related genes would be involved in the TAC-induced CF development. The results of bisulfite sequencing revealed that the TAC-induced methylation affected the CpG site in both of Rasal1 and Rassf1 genes, and DHI treatment remarkably downregulated the promoter methylation of Rasal1 and Rassf1 in CF hearts. Furthermore, DHI treatment upregulated the expressions of Rasal1 and Rassf1, inhibited the hyperactivity of Ras/ERK, and decreased the expressions of fibrosis-related genes. Notably, we found that DHI treatment markedly downregulated the expression of DNMT3B in CF hearts, while it did not affect the expressions of DNMT1, DNMT3A, and TET3. CONCLUSION Aberrant DNA methylation of Rasal1 and Rassf1 genes was involved in the CF development. DHI treatment alleviated CF, prevented the hypermethylation of Rasal1 and Rassf1, and downregulated DNMT3B expression in CF hearts.
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Affiliation(s)
- Sinai Li
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing 100010, China
- Beijing Institute of Traditional Chinese Medicine, Beijing 100010, China
| | - Ping Li
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing 100010, China
- Beijing Institute of Traditional Chinese Medicine, Beijing 100010, China
| | - Weihong Liu
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing 100010, China
- Beijing Institute of Traditional Chinese Medicine, Beijing 100010, China
| | - Juju Shang
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing 100010, China
| | - Shenglei Qiu
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing 100010, China
| | - Xiang Li
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing 100010, China
| | - Wei Liu
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing 100010, China
| | - Haoyue Shi
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing 100010, China
| | - Mingxue Zhou
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing 100010, China
- Beijing Institute of Traditional Chinese Medicine, Beijing 100010, China
| | - Hongxu Liu
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing 100010, China
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4
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CaMKII Activity in the Inflammatory Response of Cardiac Diseases. Int J Mol Sci 2019; 20:ijms20184374. [PMID: 31489895 PMCID: PMC6770001 DOI: 10.3390/ijms20184374] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/02/2019] [Accepted: 09/03/2019] [Indexed: 12/20/2022] Open
Abstract
Inflammation is a physiological process by which the body responds to external insults and stress conditions, and it is characterized by the production of pro-inflammatory mediators such as cytokines. The acute inflammatory response is solved by removing the threat. Conversely, a chronic inflammatory state is established due to a prolonged inflammatory response and may lead to tissue damage. Based on the evidence of a reciprocal regulation between inflammation process and calcium unbalance, here we described the involvement of a calcium sensor in cardiac diseases with inflammatory drift. Indeed, the Ca2+/calmodulin-dependent protein kinase II (CaMKII) is activated in several diseases with an inflammatory component, such as myocardial infarction, ischemia/reperfusion injury, pressure overload/hypertrophy, and arrhythmic syndromes, in which it actively regulates pro-inflammatory signaling, among which includes nuclear factor kappa-B (NF-κB), thus contributing to pathological cardiac remodeling. Thus, CaMKII may represent a key target to modulate the severity of the inflammatory-driven degeneration.
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He Q, Cheng J, Wang Y. Chronic CaMKII inhibition reverses cardiac function and cardiac reserve in HF mice. Life Sci 2019; 219:122-128. [PMID: 30639281 DOI: 10.1016/j.lfs.2019.01.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 01/08/2019] [Accepted: 01/09/2019] [Indexed: 12/17/2022]
Abstract
AIMS The present study was to explore the impact of KN93 - a specific inhibitor of CaMKII - on cardiac function and cardiac reserve in HF mice. MAIN METHODS We have generated pressure-overload HF mice using modified transverse aortic constriction (TAC) method. For acute inhibition (AI) experiment, HF mice were randomly divided into HF group, HF + KN93 AI group and HF + KN92 AI group, using sham mice as control. Mice in HF + KN93 AI group and HF + KN92 AI group were injected with CaMKII inhibitor KN93 or its inactive analogue KN92 on post-TAC day 15, while mice in HF group and Sham group were treated with saline. For chronic inhibition (CI) experiment, mice were injected daily with KN93, KN92 or saline for one week. At baseline and after isoproterenol (Iso) injection, in vivo cardiac function was assessed by echocardiography and left ventricular pressure-volume catheter. KEY FINDINGS Acute inhibition of CaMKII leads to decreased -dP/dtmin, increased EF, FS, longitudinal strain, longitudinal strain rate, ESPVR, dP/dtmax-EDV, PRSW, Tau and EDPVR, and unaltered reactivity to Iso in HF mice. Chronic inhibition results in increased EF, FS, longitudinal strain, longitudinal strain rate, ESPVR, dP/dtmax-EDV and PRSW, without alteration in -dP/dtmin, Tau and EDPVR. In addition, chronic inhibition reverses the effect of Iso on HF mice. SIGNIFICANCE Although acute CaMKII inhibition can repair systolic function in HF mice, it also exacerbates the diastolic function, whereas chronic inhibition improves both systolic function and cardiac reserve to β-adrenergic stimulation without impairing diastolic function.
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Affiliation(s)
- Qianwen He
- Department of Anesthesiology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Jun Cheng
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China
| | - Yanggan Wang
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan 430071, China.
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Zhang D, Tu H, Wadman MC, Li YL. Substrates and potential therapeutics of ventricular arrhythmias in heart failure. Eur J Pharmacol 2018; 833:349-356. [PMID: 29940156 DOI: 10.1016/j.ejphar.2018.06.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 04/30/2018] [Accepted: 06/19/2018] [Indexed: 12/30/2022]
Abstract
Heart failure (HF) is a clinical syndrome characterized by ventricular contractile dysfunction. About 50% of death in patients with HF are due to fetal ventricular arrhythmias including ventricular tachycardia and ventricular fibrillation. Understanding ventricular arrhythmic substrates and discovering effective antiarrhythmic interventions are extremely important for improving the prognosis of patients with HF and reducing its mortality. In this review, we discussed ventricular arrhythmic substrates and current clinical therapeutics for ventricular arrhythmias in HF. Base on the fact that classic antiarrhythmic drugs have the limited efficacy, side effects, and proarrhythmic potentials, we also updated some therapeutic strategies for the development of potential new antiarrhythmic interventions for patients with HF.
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Affiliation(s)
- Dongze Zhang
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Huiyin Tu
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Michael C Wadman
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Yu-Long Li
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA.
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7
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Xie A, Song Z, Liu H, Zhou A, Shi G, Wang Q, Gu L, Liu M, Xie LH, Qu Z, Dudley SC. Mitochondrial Ca 2+ Influx Contributes to Arrhythmic Risk in Nonischemic Cardiomyopathy. J Am Heart Assoc 2018; 7:e007805. [PMID: 29627768 PMCID: PMC6015427 DOI: 10.1161/jaha.117.007805] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Accepted: 03/07/2018] [Indexed: 12/12/2022]
Abstract
BACKGROUND Heart failure (HF) is associated with increased arrhythmia risk and triggered activity. Abnormal Ca2+ handling is thought to underlie triggered activity, and mitochondria participate in Ca2+ homeostasis. METHODS AND RESULTS A model of nonischemic HF was induced in C57BL/6 mice by hypertension. Computer simulations were performed using a mouse ventricular myocyte model of HF. Isoproterenol-induced premature ventricular contractions and ventricular fibrillation were more prevalent in nonischemic HF mice than sham controls. Isolated myopathic myocytes showed decreased cytoplasmic Ca2+ transients, increased mitochondrial Ca2+ transients, and increased action potential duration at 90% repolarization. The alteration of action potential duration at 90% repolarization was consistent with in vivo corrected QT prolongation and could be explained by augmented L-type Ca2+ currents, increased Na+-Ca2+ exchange currents, and decreased total K+ currents. Of myopathic ventricular myocytes, 66% showed early afterdepolarizations (EADs) compared with 17% of sham myocytes (P<0.05). Intracellular application of 1 μmol/L Ru360, a mitochondrial Ca2+ uniporter-specific antagonist, could reduce mitochondrial Ca2+ transients, decrease action potential duration at 90% repolarization, and ameliorate EADs. Furthermore, genetic knockdown of mitochondrial Ca2+ uniporters inhibited mitochondrial Ca2+ uptake, reduced Na+-Ca2+ exchange currents, decreased action potential duration at 90% repolarization, suppressed EADs, and reduced ventricular fibrillation in nonischemic HF mice. Computer simulations showed that EADs promoted by HF remodeling could be abolished by blocking either the mitochondrial Ca2+ uniporter or the L-type Ca2+ current, consistent with the experimental observations. CONCLUSIONS Mitochondrial Ca2+ handling plays an important role in EADs seen with nonischemic cardiomyopathy and may represent a therapeutic target to reduce arrhythmic risk in this condition.
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Affiliation(s)
- An Xie
- Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, MN
| | - Zhen Song
- Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, CA
| | - Hong Liu
- Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, MN
| | - Anyu Zhou
- Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, MN
| | - Guangbin Shi
- Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, MN
| | - Qiongying Wang
- Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, MN
| | - Lianzhi Gu
- Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, MN
| | - Man Liu
- Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, MN
| | - Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, New Jersey Medical School Rutgers, The State University of New Jersey, Newark, NJ
| | - Zhilin Qu
- Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, CA
| | - Samuel C Dudley
- Department of Medicine, Lillehei Heart Institute, University of Minnesota, Minneapolis, MN
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Abstract
The transmural heterogeneity of the contractility in ventricular muscle has not been well-studied. Here, we investigated the calcium transient and sarcomere contraction/relaxation in the endocardial (Endo) and epicardial (Epi) myocytes. Endo and Epi myocytes were isolated from C57/BL6 mice by Langendorff perfusion. Ca2+ transient and sarcomere contraction/relaxation were recorded simultaneously at different stimulation frequencies using a dual excitation fluorescence photomultiplier system. We found that the Endo myocytes have higher baseline diastolic calcium, significantly larger calcium transient and stronger sarcomere shortening than Epi myocytes. However, both the rising and decline phases for calcium transient and sarcomere shortening were slower in Endo than in Epi myocytes. When simulation frequency was increased from 1 to 3 Hz, a greater percent increase in the diastole calcium level, Ca2+ transient and sarcomere shortening amplitude has been observed in the Endo myocytes. Accordingly, the frequency-dependent acceleration in the decay rate of calcium transient and sarcomere relaxation was more profound in the Endo than in Epi myocytes. Western blot analysis showed that CaMKII activity was significantly higher in Epi than in Endo myocardium before stimulation. However, this transmural heterogeneity was reversed by rapid pacing. CaMKII inhibition by KN93 diminished the frequency-dependent alterations of Ca2+ transient and sarcomere contraction. Our results suggest that the contractility of ventricular myocytes is heterogeneous. The Endo-myocardium is the major force generating layer in the heart, both at slow and fast heart rate, and the transmural heterogeneity of CaMKII activation plays an important role in the frequency-dependent alterations.
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Affiliation(s)
- Wen Pan
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Ziqi Yang
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Jun Cheng
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Cheng Qian
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Yanggan Wang
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan, China.,Medical Research Institute of Wuhan University, Wuhan University, Wuhan, China
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Cheng J, Cao J, Jiang X, Xu L, Wang Y. Kv4.3 expression reverses I Ca remodeling in ventricular myocytes of heart failure. Oncotarget 2017; 8:104037-104045. [PMID: 29262619 PMCID: PMC5732785 DOI: 10.18632/oncotarget.21956] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 09/25/2017] [Indexed: 11/25/2022] Open
Abstract
Background Ca2+/calmodulin-dependent protein kinase II (CaMKII)-dependent L-type calcium channel (LTCC) current (ICa) remodeling is an important contributor to the disruption of calcium homeostasis in heart failure (HF). We have reported that Kv4.3 proteins play an important role in delicate regulation of the membrane-associated CaMKII activity in ventricular myocytes. Here, we investigated the effect of in vivo Kv4.3 expression on ICa in HF left ventricular (LV) myocytes. Results Kv4.3 expression reduced overall CaMKII autophosphorylation with much greater reduction in the membrane compartmentalized CaMKII activity. ICa density in subepicardial (SEP) and subendocardial (SEN) myocytes was proportionately reduced, without changing the transmural gradient. While the time course of ICa decay was hastened, the voltage-dependence of ICa activation and inactivation, however, remained unchanged. ICa recovery from inactivation was significantly accelerated. In line with the partial inhibition of CaMKII, the frequency-dependent Ca2+-induced ICa facilitation was recovered in the HF myocytes transfected with Kv4.3. Materials and Methods Pressure-overload HF was induced by thoracic aortic banding. Kv4.3 expression was achieved by Ad-Kv4.3 injection in the LV myocardium. ICa was recorded in dissociated SEP and SEN myocytes using whole-cell patch clamp method. Conclusions Kv4.3 expression in HF ventricle can effectively reverse ICa remodeling via inhibition of the membrane-associated CaMKII, pointing to Kv4.3 restoration as a potential therapeutic approach for the disordered calcium regulation in HF.
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Affiliation(s)
- Jun Cheng
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan 430071, China
| | - Jianlei Cao
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan 430071, China
| | - Xingchen Jiang
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan 430071, China
| | - Lin Xu
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan University, Wuhan 430060, China
| | - Yanggan Wang
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan University, Wuhan 430071, China.,Medical Research Institute of Wuhan University, Wuhan University, Wuhan 430071, China
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Li S, Nong Y, Gao Q, Liu J, Li Y, Cui X, Wan J, Lu J, Sun M, Wu Q, Shi X, Cui H, Liu W, Zhou M, Li L, Lin Q. Astragalus Granule Prevents Ca 2+ Current Remodeling in Heart Failure by the Downregulation of CaMKII. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE : ECAM 2017; 2017:7517358. [PMID: 28855948 PMCID: PMC5569633 DOI: 10.1155/2017/7517358] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 07/06/2017] [Indexed: 12/20/2022]
Abstract
BACKGROUND Astragalus was broadly used for treating heart failure (HF) and arrhythmias in East Asia for thousands of years. Astragalus granule (AG), extracted from Astragalus, shows beneficial effect on the treatment of HF in clinical research. We hypothesized that administration of AG prevents the remodeling of L-type Ca2+ current (ICa-L) in HF mice by the downregulation of Ca2+/calmodulin-dependent protein kinase II (CaMKII). METHODS HF mice were induced by thoracic aortic constriction (TAC). After 4 weeks of AG treatment, cardiac function and QT interval were evaluated. Single cardiac ventricular myocyte was then isolated and whole-cell patch clamp was used to record action potential (AP) and ICa-L. The expressions of L-type calcium channel alpha 1C subunit (Cav1.2), CaMKII, and phosphorylated protein kinase A (p-PKA) were examined by western blot. RESULTS The failing heart manifested distinct electrical remodeling including prolonged repolarization time and altered ICa-L kinetics. AG treatment attenuated this electrical remodeling, supported by AG-related shortened repolarization time, decreased peak ICa-L, accelerated ICa-L inactivation, and positive frequency-dependent ICa-L facilitation. In addition, AG treatment suppressed the overexpression of CaMKII, but not p-PKA, in the failing heart. CONCLUSION AG treatment protected the failing heart against electrical remodeling and ICa-L remodeling by downregulating CaMKII.
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Affiliation(s)
- Sinai Li
- Dongfang Hospital, Beijing University of Chinese Medicine, Beijing 100078, China
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing Institute of Traditional Chinese Medicine, Beijing 100010, China
| | - Yibing Nong
- Dongfang Hospital, Beijing University of Chinese Medicine, Beijing 100078, China
- Department of Medicine, Institute of Molecular Cardiology, University of Louisville, Louisville, KY 40292, USA
| | - Qun Gao
- Dongfang Hospital, Beijing University of Chinese Medicine, Beijing 100078, China
| | - Jing Liu
- Dongfang Hospital, Beijing University of Chinese Medicine, Beijing 100078, China
| | - Yan Li
- Dongfang Hospital, Beijing University of Chinese Medicine, Beijing 100078, China
| | - Xiaoyun Cui
- Dongfang Hospital, Beijing University of Chinese Medicine, Beijing 100078, China
| | - Jie Wan
- Dongfang Hospital, Beijing University of Chinese Medicine, Beijing 100078, China
| | - Jinjin Lu
- Dongfang Hospital, Beijing University of Chinese Medicine, Beijing 100078, China
| | - Mingjie Sun
- Experimental Research Center, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Qian Wu
- Experimental Research Center, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Xiaolu Shi
- Experimental Research Center, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Haifeng Cui
- Experimental Research Center, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Weihong Liu
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing Institute of Traditional Chinese Medicine, Beijing 100010, China
| | - Mingxue Zhou
- Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, Beijing Institute of Traditional Chinese Medicine, Beijing 100010, China
| | - Lina Li
- College of Basic Medicine, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Qian Lin
- Dongfang Hospital, Beijing University of Chinese Medicine, Beijing 100078, China
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11
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Nassal DM, Wan X, Liu H, Maleski D, Ramirez-Navarro A, Moravec CS, Ficker E, Laurita KR, Deschênes I. KChIP2 is a core transcriptional regulator of cardiac excitability. eLife 2017; 6. [PMID: 28263709 PMCID: PMC5338919 DOI: 10.7554/elife.17304] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 02/19/2017] [Indexed: 11/18/2022] Open
Abstract
Arrhythmogenesis from aberrant electrical remodeling is a primary cause of death among patients with heart disease. Amongst a multitude of remodeling events, reduced expression of the ion channel subunit KChIP2 is consistently observed in numerous cardiac pathologies. However, it remains unknown if KChIP2 loss is merely a symptom or involved in disease development. Using rat and human derived cardiomyocytes, we identify a previously unobserved transcriptional capacity for cardiac KChIP2 critical in maintaining electrical stability. Through interaction with genetic elements, KChIP2 transcriptionally repressed the miRNAs miR-34b and miR-34c, which subsequently targeted key depolarizing (INa) and repolarizing (Ito) currents altered in cardiac disease. Genetically maintaining KChIP2 expression or inhibiting miR-34 under pathologic conditions restored channel function and moreover, prevented the incidence of reentrant arrhythmias. This identifies the KChIP2/miR-34 axis as a central regulator in developing electrical dysfunction and reveals miR-34 as a therapeutic target for treating arrhythmogenesis in heart disease. DOI:http://dx.doi.org/10.7554/eLife.17304.001 The heart pumps blood throughout the body to provide oxygen and nourishment. To do so, proteins in the heart create electrical signals that tell the heart muscles to contract in a coordinated manner. Heart disease can cause cells to lose control of the production or activity of these proteins, creating disorganized electrical signals called arrhythmias that interfere with the heart’s ability to pump. Sometimes these arrhythmias lead to sudden death. Researchers do not know exactly what triggers these changes in the heart’s normal electrical rhythms. This has made it difficult to develop strategies to prevent these disruptions or to fix them when they occur. By studying rat and human heart cells, Nassal et al. now show that a protein called KChIP2 stops working properly during heart disease. Most importantly, because of the decreased level of KChIP2 in heart disease, KChIP2 loses the ability to restrict the production of two microRNA molecules – a role that KChIP2 was not previously known to perform. This loss of activity sets off a cascade of signals that worsens the balance of electrical activity in the heart cells, creating arrhythmias. Treatments that restored proper levels of the fully working KChIP2 protein to the heart cells or that blocked the signals set off by a lack of KChIP2 returned the electrical activity of the cells back to normal. This also stopped the development of arrhythmias. Further studies are now needed to investigate whether these treatments have the same effects in living mammals. If effective, this could ultimately lead to new treatments for heart diseases and arrhythmias. DOI:http://dx.doi.org/10.7554/eLife.17304.002
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Affiliation(s)
- Drew M Nassal
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, United States.,Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, United States
| | - Xiaoping Wan
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, United States
| | - Haiyan Liu
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, United States
| | - Danielle Maleski
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, United States
| | - Angelina Ramirez-Navarro
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, United States
| | - Christine S Moravec
- Department of Molecular Cardiology, Cleveland Clinic, Cleveland, United States
| | - Eckhard Ficker
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, United States
| | - Kenneth R Laurita
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, United States
| | - Isabelle Deschênes
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, United States.,Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, United States
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McKinnon D, Rosati B. Transmural gradients in ion channel and auxiliary subunit expression. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 122:165-186. [PMID: 27702655 DOI: 10.1016/j.pbiomolbio.2016.09.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/30/2016] [Indexed: 12/11/2022]
Abstract
Evolution has acted to shape the action potential in different regions of the heart in order to produce a maximally stable and efficient pump. This has been achieved by creating regional differences in ion channel expression levels within the heart as well as differences between equivalent cardiac tissues in different species. These region- and species-dependent differences in channel expression are established by regulatory evolution, evolution of the regulatory mechanisms that control channel expression levels. Ion channel auxiliary subunits are obvious targets for regulatory evolution, in order to change channel expression levels and/or modify channel function. This review focuses on the transmural gradients of ion channel expression in the heart and the role that regulation of auxiliary subunit expression plays in generating and shaping these gradients.
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Affiliation(s)
- David McKinnon
- Department of Veterans Affairs Medical Center, Northport, NY, USA; Institute of Molecular Cardiology, Stony Brook University, Stony Brook, NY, USA; Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Barbara Rosati
- Department of Veterans Affairs Medical Center, Northport, NY, USA; Institute of Molecular Cardiology, Stony Brook University, Stony Brook, NY, USA; Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, 11794, USA.
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13
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Chen M, Xin J, Liu B, Luo L, Li J, Yin W, Li M. Mitogen-Activated Protein Kinase and Intracellular Polyamine Signaling Is Involved in TRPV1 Activation-Induced Cardiac Hypertrophy. J Am Heart Assoc 2016; 5:JAHA.116.003718. [PMID: 27473037 PMCID: PMC5015292 DOI: 10.1161/jaha.116.003718] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND The transient receptor potential vanilloid type 1 (TRPV1) is expressed in the cardiovascular system, and increased TRPV1 expression has been associated with cardiac hypertrophy. Nevertheless, the role of TRPV1 in the pathogenesis of cardiac hypertrophy and the underlying molecular mechanisms remain unclear. METHODS AND RESULTS In cultured cardiomyocytes, activation of TRPV1 increased cell size and elevated expression of atrial natriuretic peptide mRNA and intracellular calcium level, which was reversed by TRPV1 antagonist capsazepine. Increased expression of phosphorylated calmodulin-dependent protein kinase IIδ and mitogen-activated protein kinases were found in TRPV1 agonist capsaicin-treated cardiomyocytes. Selective inhibitor of calmodulin-dependent protein kinase IIδ decreased phosphorylation of extracellular signal-regulated kinases and p38. Capsaicin induced an increase in expression of ornithine decarboxylase protein, which is the key enzyme in polyamine biosynthesis in cardiomyocytes. Nevertheless, there was no obvious change of ornithine decarboxylase expression in TRPV1 knockdown cells after capsaicin treatment, and specific inhibitors of calmodulin-dependent protein kinase IIδ or p38 downregulated the capsaicin-induced expression of ornithine decarboxylase. Capsazepine alleviated the increase in cross-sectional area of cardiomyocytes and the ratio of heart weight to body weight and improved cardiac function, including left ventricular internal end-diastolic and -systolic dimensions and ejection fraction and fractional shortening percentages, in mice treated with transverse aorta constriction. Capsazepine also reduced expression of ornithine decarboxylase and cardiac polyamine levels. Transverse aorta constriction induced increases in phosphorylated calmodulin-dependent protein kinase IIδ and extracellular signal-regulated kinases, and p38 and Serca2a were attenuated by capsazepine treatment. CONCLUSIONS This study revealed that the mitogen-activated protein kinase signaling pathway and intracellular polyamines are essential for TRPV1 activation-induced cardiac hypertrophy.
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Affiliation(s)
- Mai Chen
- Department of Cardiology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Jiajia Xin
- Department of Blood Transfusion, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Baohui Liu
- Department of Cardiac Surgery, Binzhou Medical University Hospital, Binzhou, China
| | - Liyang Luo
- Department of Pharmacology, School of Pharmacy, The Fourth Military Medical University, Xi'an, China
| | - Jiayi Li
- Department of Cardiology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Wen Yin
- Department of Blood Transfusion, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Mingkai Li
- Department of Pharmacology, School of Pharmacy, The Fourth Military Medical University, Xi'an, China
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14
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Guilbert A, Lim HJ, Cheng J, Wang Y. CaMKII-dependent myofilament Ca2+ desensitization contributes to the frequency-dependent acceleration of relaxation. Cell Calcium 2015; 58:489-99. [PMID: 26297240 DOI: 10.1016/j.ceca.2015.08.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 07/06/2015] [Accepted: 08/04/2015] [Indexed: 11/15/2022]
Abstract
BACKGROUND Previous studies suggest that CaMKII activity is required for frequency-dependent acceleration of relaxation (FDAR) in ventricular myocytes. We propose that the underlying mechanism involves CaMKII-dependent regulation of myofilament Ca(2+) sensitivity. METHODS AND RESULTS Cardiac function was measured in mice using murine echo machine. [Ca(2+)]i and sarcomere length were measured by IonOptix Ca(2+) image system. Increasing pacing rate from 0.5 to 4 Hz in left ventricular myocytes induced frequency-dependent myofilament Ca(2+) desensitization (FDMCD) and FDAR. Acute inhibition of PKA or PKC had no effect, whereas CaMKII inhibition abolished both FDMCD and FDAR. Co-immunoprecipitation of CaMKII and troponin I (TnI) has been detected and CaMKII inhibition significantly reduced serine residue phosphorylation of TnI. Finally, chronic inhibition of CaMKII in vivo reduced TnI phosphorylation and abolished both FDAR and FDMCD, leading to impaired diastolic function. CONCLUSIONS Our results suggest that CaMKII-dependent TnI phosphorylation is involved in FDMCD and the consequent FDAR and that CaMKII inhibition removes this mechanism and thus induces diastolic dysfunction.
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Affiliation(s)
| | - Hyun Joung Lim
- Department of Pediatrics, Emory University, Atlanta, USA
| | - Jun Cheng
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan University, China; Department of Pediatrics, Emory University, Atlanta, USA
| | - Yanggan Wang
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan University, China; Department of Pediatrics, Emory University, Atlanta, USA.
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15
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Markandeya YS, Phelan LJ, Woon MT, Keefe AM, Reynolds CR, August BK, Hacker TA, Roth DM, Patel HH, Balijepalli RC. Caveolin-3 Overexpression Attenuates Cardiac Hypertrophy via Inhibition of T-type Ca2+ Current Modulated by Protein Kinase Cα in Cardiomyocytes. J Biol Chem 2015; 290:22085-100. [PMID: 26170457 DOI: 10.1074/jbc.m115.674945] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Indexed: 12/24/2022] Open
Abstract
Pathological cardiac hypertrophy is characterized by subcellular remodeling of the ventricular myocyte with a reduction in the scaffolding protein caveolin-3 (Cav-3), altered Ca(2+) cycling, increased protein kinase C expression, and hyperactivation of calcineurin/nuclear factor of activated T cell (NFAT) signaling. However, the precise role of Cav-3 in the regulation of local Ca(2+) signaling in pathological cardiac hypertrophy is unclear. We used cardiac-specific Cav-3-overexpressing mice and in vivo and in vitro cardiac hypertrophy models to determine the essential requirement for Cav-3 expression in protection against pharmacologically and pressure overload-induced cardiac hypertrophy. Transverse aortic constriction and angiotensin-II (Ang-II) infusion in wild type (WT) mice resulted in cardiac hypertrophy characterized by significant reduction in fractional shortening, ejection fraction, and a reduced expression of Cav-3. In addition, association of PKCα and angiotensin-II receptor, type 1, with Cav-3 was disrupted in the hypertrophic ventricular myocytes. Whole cell patch clamp analysis demonstrated increased expression of T-type Ca(2+) current (ICa, T) in hypertrophic ventricular myocytes. In contrast, the Cav-3-overexpressing mice demonstrated protection from transverse aortic constriction or Ang-II-induced pathological hypertrophy with inhibition of ICa, T and intact Cav-3-associated macromolecular signaling complexes. siRNA-mediated knockdown of Cav-3 in the neonatal cardiomyocytes resulted in enhanced Ang-II stimulation of ICa, T mediated by PKCα, which caused nuclear translocation of NFAT. Overexpression of Cav-3 in neonatal myocytes prevented a PKCα-mediated increase in ICa, T and nuclear translocation of NFAT. In conclusion, we show that stable Cav-3 expression is essential for protecting the signaling mechanisms in pharmacologically and pressure overload-induced cardiac hypertrophy.
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Affiliation(s)
- Yogananda S Markandeya
- From the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin 53706
| | - Laura J Phelan
- From the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin 53706
| | - Marites T Woon
- From the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin 53706
| | - Alexis M Keefe
- From the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin 53706
| | - Courtney R Reynolds
- From the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin 53706
| | - Benjamin K August
- From the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin 53706
| | - Timothy A Hacker
- From the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin 53706
| | - David M Roth
- the Veterans Affairs San Diego Healthcare Systems, San Diego, California 92161, and the Department of Anesthesiology, University of California at San Diego, La Jolla, California 92161
| | - Hemal H Patel
- the Veterans Affairs San Diego Healthcare Systems, San Diego, California 92161, and the Department of Anesthesiology, University of California at San Diego, La Jolla, California 92161
| | - Ravi C Balijepalli
- From the Cellular and Molecular Arrhythmia Research Program, Department of Medicine, University of Wisconsin, Madison, Wisconsin 53706,
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Huo R, Sheng Y, Guo WT, Dong DL. The potential role of Kv4.3 K+ channel in heart hypertrophy. Channels (Austin) 2015; 8:203-9. [PMID: 24762397 DOI: 10.4161/chan.28972] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Transient outward K+ current (I(to)) plays a crucial role in the early phase of cardiac action potential repolarization. Kv4.3 K(+) channel is an important component of I(to). The function and expression of Kv4.3 K(+) channel decrease in variety of heart diseases, especially in heart hypertrophy/heart failure. Int his review, we summarized the changes of cardiac Kv4.3 K(+) channel in heart diseases and discussed the potential role of Kv4.3 K(+) channel in heart hypertrophy/heart failure. In heart hypertrophy/heart failure of mice and rats, down regulation of Kv4.3 K(+) channel leads to prolongation of action potential duration (APD), which is associated with increased [Ca(2+)](I), activation of calcineurin and heart hypertrophy/heart failure.However, in canine and human, Kv4.3 K(+) channel does not play a major role in setting cardiac APD. So, in addition to Kv4.3 K(+) channel/APD/[Ca(2+)](I) pathway, there exits another mechanism of Kv4.3 K(+) channel in heart hypertrophy and heart failure: downregulation of Kv4.3 K(+) channels leads to CaMKII dissociation from Kv4.3–CaMKII complex and subsequent activation of the dissociated CaMKII , which induces heart hypertrophy/heart failure. Upregulation of Kv4.3K(+) channel inhibits CaMKII activation and its related harmful consequences. We put forward a new point-of-view that Kv4.3 K(+) channel is involved in heart hypertrophy/heart failure independently of its electric function, and drugs inhibiting or upregulating Kv4.3 K(+) channel might be potentially harmful or beneficial to hearts through CaMKII.
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17
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Qu F, Zhao Z, Yuan B, Qi W, Li C, Shen X, Liu C, Li H, Zhao G, Wang J, Guo Q, Liu Y. CaMKII plays a part in the chondrogenesis of bone marrow-derived mesenchymal stem cells. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2015; 8:5981-5987. [PMID: 26191331 PMCID: PMC4503202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 03/16/2015] [Indexed: 06/04/2023]
Abstract
AIMS The purpose of the study is to observe the functions of calcium/calmodulin dependent protein kinase II (CaMKII) in the induced chondrogenic differentiation of bone marrow derived mesenchymal stem cells (BMSCs). METHODS BMSCs was in vitro isolated and cultured for induced chondrogenesis. Western blot was used to ascertain the expression of CaMKII and phosphorylated CaMKII (PCaMKII, activatory CaMKII) in chondrogenic induced BMSCs. MTT method was utilized to observe the impact of CaMKII on the proliferation of BMSCs. The generation of cartilage matrix in BMSCs cells was detected by toluidine blue staining. The levels of cartilage marker genes COL2A1, Aggrecan and SOX9 in BMSCs were gained by real-time fluorescence quantitative polymerase chain reaction (RT-QPCR). Finally, BMSCs proliferation, cartilage matrix generation and the changes of COL2A1, Aggrecan and SOX9 were surveyed after CaMKII being blocked by CaMKII inhibitor KN93. RESULTS Expression of CaMKII and PCaMKII could be found in chondrogenic induced BMSCs. CaMKII had no significant influence on BMSCs proliferation, but the toluidine blue staining was obviously lighter, indicating a significant decline in the expression of COL2A1, Aggrecan and SOX9. CONCLUSION As one of the factors influencing the chondrogenic capacity of BMSCs, CaMKII does not impact on BMSCs proliferation, but it can inhibit the chondrogenic ability of BMSCs by influencing its differentiation.
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Affiliation(s)
- Feng Qu
- Department of Orthopedics, Chinese PLA General Hospital28 Fuxing Road, Haidian District, Beijing 100853, China
| | - Zhikun Zhao
- Department of Orthopedics, The First Affiliated Hospital of Chinese PLA General Hospital51 Fucheng Road, Haidian District, Beijing 100048, China
| | - Bangtuo Yuan
- Department of Orthopedics, Chinese PLA General Hospital28 Fuxing Road, Haidian District, Beijing 100853, China
| | - Wei Qi
- Department of Orthopedics, Chinese PLA General Hospital28 Fuxing Road, Haidian District, Beijing 100853, China
| | - Chunbao Li
- Department of Orthopedics, Chinese PLA General Hospital28 Fuxing Road, Haidian District, Beijing 100853, China
| | - Xuezhen Shen
- Department of Orthopedics, Chinese PLA General Hospital28 Fuxing Road, Haidian District, Beijing 100853, China
| | - Chang Liu
- Department of Orthopedics, Chinese PLA General Hospital28 Fuxing Road, Haidian District, Beijing 100853, China
| | - Hongliang Li
- Department of Orthopedics, Chinese PLA General Hospital28 Fuxing Road, Haidian District, Beijing 100853, China
| | - Gang Zhao
- Department of Orthopedics, Chinese PLA General Hospital28 Fuxing Road, Haidian District, Beijing 100853, China
| | - Jiangtao Wang
- Department of Orthopedics, Chinese PLA General Hospital28 Fuxing Road, Haidian District, Beijing 100853, China
| | - Qi Guo
- Department of Orthopedics, Chinese PLA General Hospital28 Fuxing Road, Haidian District, Beijing 100853, China
| | - Yujie Liu
- Department of Orthopedics, Chinese PLA General Hospital28 Fuxing Road, Haidian District, Beijing 100853, China
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18
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Ablorh NAD, Dong X, James ZM, Xiong Q, Zhang J, Thomas DD, Karim CB. Synthetic phosphopeptides enable quantitation of the content and function of the four phosphorylation states of phospholamban in cardiac muscle. J Biol Chem 2014; 289:29397-405. [PMID: 25190804 DOI: 10.1074/jbc.m114.556621] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have studied the differential effects of phospholamban (PLB) phosphorylation states on the activity of the sarcoplasmic reticulum Ca-ATPase (SERCA). It has been shown that unphosphorylated PLB (U-PLB) inhibits SERCA and that phosphorylation of PLB at Ser-16 or Thr-17 relieves this inhibition in cardiac sarcoplasmic reticulum. However, the levels of the four phosphorylation states of PLB (U-PLB, P16-PLB, P17-PLB, and doubly phosphorylated 2P-PLB) have not been measured quantitatively in cardiac tissue, and their functional effects on SERCA have not been determined directly. We have solved both problems through the chemical synthesis of all four PLB species. We first used the synthetic PLB as standards for a quantitative immunoblot assay, to determine the concentrations of all four PLB phosphorylation states in pig cardiac tissue, with and without left ventricular hypertrophy (LVH) induced by aortic banding. In both LVH and sham hearts, all phosphorylation states were significantly populated, but LVH hearts showed a significant decrease in U-PLB, with a corresponding increase in the ratio of total phosphorylated PLB to U-PLB. To determine directly the functional effects of each PLB species, we co-reconstituted each of the synthetic peptides in phospholipid membranes with SERCA and measured calcium-dependent ATPase activity. SERCA inhibition was maximally relieved by P16-PLB (the most highly populated PLB state in cardiac tissue homogenates), followed by 2P-PLB, then P17-PLB. These results show that each PLB phosphorylation state uniquely alters Ca(2+) homeostasis, with important implications for cardiac health, disease, and therapy.
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Affiliation(s)
| | - Xiaoqiong Dong
- From the Departments of Biochemistry, Molecular Biology and Biophysics and
| | - Zachary M James
- From the Departments of Biochemistry, Molecular Biology and Biophysics and
| | - Qiang Xiong
- Medicine, University of Minnesota, Minneapolis, Minnesota 55455
| | - Jianyi Zhang
- Medicine, University of Minnesota, Minneapolis, Minnesota 55455
| | - David D Thomas
- From the Departments of Biochemistry, Molecular Biology and Biophysics and
| | - Christine B Karim
- From the Departments of Biochemistry, Molecular Biology and Biophysics and
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19
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Bers DM, Morotti S. Ca(2+) current facilitation is CaMKII-dependent and has arrhythmogenic consequences. Front Pharmacol 2014; 5:144. [PMID: 24987371 PMCID: PMC4060732 DOI: 10.3389/fphar.2014.00144] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 06/02/2014] [Indexed: 11/13/2022] Open
Abstract
The cardiac voltage gated Ca2+ current (ICa) is critical to the electrophysiological properties, excitation-contraction coupling, mitochondrial energetics, and transcriptional regulation in heart. Thus, it is not surprising that cardiac ICa is regulated by numerous pathways. This review will focus on changes in ICa that occur during the cardiac action potential (AP), with particular attention to Ca2+-dependent inactivation (CDI), Ca2+-dependent facilitation (CDF) and how calmodulin (CaM) and Ca2+-CaM dependent protein kinase (CaMKII) participate in the regulation of Ca2+ current during the cardiac AP. CDI depends on CaM pre-bound to the C-terminal of the L-type Ca2+ channel, such that Ca2+ influx and Ca2+ released from the sarcoplasmic reticulum bind to that CaM and cause CDI. In cardiac myocytes CDI normally pre-dominates over voltage-dependent inactivation. The decrease in ICa via CDI provides direct negative feedback on the overall Ca2+ influx during a single beat, when myocyte Ca2+ loading is high. CDF builds up over several beats, depends on CaMKII-dependent Ca2+ channel phosphorylation, and results in a staircase of increasing ICa peak, with progressively slower inactivation. CDF and CDI co-exist and in combination may fine-tune the ICa waveform during the cardiac AP. CDF may partially compensate for the tendency for Ca2+ channel availability to decrease at higher heart rates because of accumulating inactivation. CDF may also allow some reactivation of ICa during long duration cardiac APs, and contribute to early afterdepolarizations, a form of triggered arrhythmias.
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Affiliation(s)
- Donald M Bers
- Department of Pharmacology, University of California Davis Davis, CA, USA
| | - Stefano Morotti
- Department of Pharmacology, University of California Davis Davis, CA, USA
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20
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Abstract
Despite declines in heart failure morbidity and mortality with current therapies, rehospitalization rates remain distressingly high, substantially affecting individuals, society, and the economy. As a result, the need for new therapeutic advances and novel medical devices is urgent. Disease-related left ventricular remodeling is a complex process involving cardiac myocyte growth and death, vascular rarefaction, fibrosis, inflammation, and electrophysiological remodeling. Because these events are highly interrelated, targeting a single molecule or process may not be sufficient. Here, we review molecular and cellular mechanisms governing pathological ventricular remodeling.
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Sevoflurane Protects Ventricular Myocytes against Oxidative Stress-induced Cellular Ca2+ Overload and Hypercontracture. Anesthesiology 2013; 119:606-20. [DOI: 10.1097/aln.0b013e318292ee52] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Abstract
Background:
Oxidative stress is implicated in pathogenesis of cardiac reperfusion injury, characterized by cellular Ca2+ overload and hypercontracture. Volatile anesthetics protect the heart against reperfusion injury primarily by attenuating Ca2+ overload. This study investigated electrophysiological mechanisms underlying cardioprotective effects of sevoflurane against oxidative stress-induced cellular injury.
Methods:
The cytosolic Ca2+ levels and cell morphology were assessed in mouse ventricular myocytes, using confocal fluo-3 fluorescence imaging, whereas membrane potentials and L-type Ca2+ current (ICa,L) were recorded using whole-cell patch-clamp techniques. Phosphorylation of Ca2+/calmodulin-dependent protein kinase II was examined by Western blotting.
Results:
Exposure to H2O2 (100 μm) for 15 min evoked cytosolic Ca2+ elevation and hypercontracture in 56.8% of ventricular myocytes in 11 experiments, which was partly but significantly reduced by nifedipine, tetracaine, or SEA0400. Sevoflurane prevented H2O2-induced cellular Ca2+ overload in a concentration-dependent way (IC50 = 1.35%). Isoflurane (2%) and desflurane (10%) also protected ventricular myocytes by a degree similar to sevoflurane (3%). Sevoflurane suppressed H2O2-induced electrophysiological disturbances, including early afterdepolarizations, voltage fluctuations in resting potential, and abnormal automaticities. H2O2 significantly enhanced ICa,L by activating Ca2+/calmodulin-dependent protein kinase II, and subsequent addition of sevoflurane, isoflurane, or desflurane similarly reduced ICa,L to below baseline levels. Phosphorylated Ca2+/calmodulin-dependent protein kinase II increased after 10-min incubation with H2O2, which was significantly prevented by concomitant administration of sevoflurane.
Conclusions:
Sevoflurane protected ventricular myocytes against H2O2-induced Ca2+ overload and hypercontracture, presumably by affecting multiple Ca2+ transport pathways, including ICa,L, Na+/Ca2+ exchanger and ryanodine receptor. These actions appear to mediate cardioprotection against reperfusion injury associated with oxidative stress.
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Wang Y, Tandan S, Hill JA. Calcineurin-dependent ion channel regulation in heart. Trends Cardiovasc Med 2013; 24:14-22. [PMID: 23809405 DOI: 10.1016/j.tcm.2013.05.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Revised: 05/20/2013] [Accepted: 05/21/2013] [Indexed: 02/05/2023]
Abstract
Calcineurin, a serine-threonine-specific, Ca(2+)-calmodulin-activated protein phosphatase, conserved from yeast to humans, plays a key role in regulating cardiac development, hypertrophy, and pathological remodeling. Recent studies demonstrate that calcineurin regulates cardiomyocyte ion channels and receptors in a manner which often entails direct interaction with these target proteins. Here, we review the current state of knowledge of calcineurin-mediated regulation of ion channels in the myocardium with emphasis on the transient outward potassium current (Ito) and L-type calcium current (ICa,L). We go on to discuss unanswered questions that surround these observations and provide perspective on future directions in this exciting field.
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Affiliation(s)
- Yanggan Wang
- Department of Cardiology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, China; Department of Pediatrics, Emory University, Atlanta, GA, USA.
| | - Samvit Tandan
- Department of Internal Medicine (Cardiology), University of Texas, Southwestern Medical Center, Dallas, TX, USA
| | - Joseph A Hill
- Department of Internal Medicine (Cardiology), University of Texas, Southwestern Medical Center, Dallas, TX, USA; Department of Molecular Biology, University of Texas, Southwestern Medical Center, Dallas, TX, USA.
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23
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Yu L, Li M, She T, Shi C, Meng W, Wang B, Cheng M. Endothelin-1 stimulates the expression of L-type Ca2+ channels in neonatal rat cardiomyocytes via the extracellular signal-regulated kinase 1/2 pathway. J Membr Biol 2013; 246:343-53. [PMID: 23546014 DOI: 10.1007/s00232-013-9538-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Accepted: 03/16/2013] [Indexed: 01/07/2023]
Abstract
The cardiac L-type Ca(2+) channel current (I(Ca,L)) plays an important role in controlling both cardiac excitability and excitation-contraction coupling and is involved in the electrical remodeling during postnatal heart development and cardiac hypertrophy. However, the possible role of endothelin-1 (ET-1) in the electrical remodeling of postnatal and diseased hearts remains unclear. Therefore, the present study was designed to investigate the transcriptional regulation of I(Ca,L) mediated by ET-1 in neonatal rat ventricular myocytes using the whole-cell patch-clamp technique, quantitative RT-PCR and Western blotting. Furthermore, we determined whether the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway is involved. ET-1 increased I(Ca,L) density without altering its voltage dependence of activation and inactivation. In line with the absence of functional changes, ET-1 increased L-type Ca(2+) channel pore-forming α1C-subunit mRNA and protein levels without affecting the mRNA expression of auxiliary β- and α2/δ-subunits. Furthermore, an actinomycin D chase experiment revealed that ET-1 did not alter α1C-subunit mRNA stability. These effects of ET-1 were inhibited by the ETA receptor antagonist BQ-123 but not the ETB receptor antagonist BQ-788. Moreover, the effects of ET-1 on I(Ca,L) and α1C-subunit expression were abolished by the ERK1/2 inhibitor (PD98059) but not by the p38 MAPK inhibitor (SB203580) or the c-Jun N-terminal kinase inhibitor (SP600125). These findings indicate that ET-1 increased the transcription of L-type Ca(2+) channel in cardiomyocytes via activation of ERK1/2 through the ETA receptor, which may contribute to the electrical remodeling of heart during postnatal development and cardiac hypertrophy.
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Affiliation(s)
- Liangzhu Yu
- Hubei Province Key Laboratory on Cardiovascular, Cerebrovascular, and Metabolic Disorders, Hubei University of Science and Technology, Xianning, Peoples Republic of China.
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Lai D, Xu L, Cheng J, Guilbert AB, Lim HJ, Fu G, Wang Y. Stretch current-induced abnormal impulses in CaMKIIδ knockout mouse ventricular myocytes. J Cardiovasc Electrophysiol 2012; 24:457-63. [PMID: 23279377 DOI: 10.1111/jce.12060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND CaMKII activation is proarrhythmic in heart failure where myocardium is stretched. However, the arrhythmogenic role of CaMKII in stretched ventricle has not been well understood. OBJECTIVE We tested abnormal impulse inducibility by stretch current in myocytes isolated from CaMKIIδ knockout (KO) mouse left ventricle (LV) where CaMKII activity is reduced by ≈ 62%. METHODS AND RESULTS Action potentials were recorded by whole-cell patch clamp, and abnormal impulses were induced in LV myocytes by a simulation of stretch-activated channel (SAC) current. SAC activation failed to induce abnormal impulses in wild type (WT) myocytes but steadily produced early after-depolarizations and automaticity in KO myocytes in which an increase in L-type calcium channel (LTCC) current (I(Ca)) and a reduction of sarcoplasmic reticulum Ca(2+) leak and action potential duration (APD) were observed. The abnormal impulses were not suppressed by CaMKII inhibitor AIP whereas a low concentration of nifedipine eliminated abnormal impulses without shortening APD, implicating I(Ca) in promoting stretch-induced abnormal impulses. In addition, APD prolongation by LTCC opener S(-)Bay K 8644 or isoproterenol facilitated abnormal impulse induction in WT ventricular myocytes even in the presence of CaMKII inhibitor AIP, whereas APD prolongation by K(+) channel blocker 4-aminopyridine promoted abnormal impulses in KO myocytes but not in WT myocytes. CONCLUSION I(Ca) activation plays a central role in stretch-induced abnormal impulses and APD prolongation is arrhythmogenic only when I(Ca) is highly activated. At increased I(Ca) activation, CaMKII inhibition cannot suppress abnormal impulse induction.
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Affiliation(s)
- Dongwu Lai
- Department of Pediatrics, Emory University, Atlanta, Georgia, USA
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Hill JA. Hypertrophic reprogramming of the left ventricle: translation to the ECG. J Electrocardiol 2012; 45:624-9. [PMID: 22999493 DOI: 10.1016/j.jelectrocard.2012.08.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Indexed: 01/16/2023]
Abstract
Hypertrophic growth of the heart occurs in many clinical scenarios, and it confers substantially increased risk of untoward sequelae. Among them, transition to ventricular dilation, wall thinning, contractile dysfunction, and a clinical syndrome of heart failure are paramount. Left ventricular hypertrophy (LVH) is typically diagnosed by either electrocardiography or echocardiography. However, these two means of assessing hypertrophic transformation of the left ventricle can sometimes disagree. At one level, this may not be surprising as the two methodologies are based on entirely divergent signals: electrical potential between two places on the surface of the skin and ultrasound energy reflected from the ventricle itself. Echocardiography is an effective means of assessing ventricular mass, which is a cardinal feature of LVH. Importantly, however, LVH is characterized by a wide range of remodeling events beyond simple increases in muscle mass. Electrocardiographic changes in LVH are reflective of the electrophysiological aspects of hypertrophic transformation. Here, I present an overview of the complex biology of left ventricular hypertrophy with an eye toward enhancing our understanding of its ECG manifestations.
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Affiliation(s)
- Joseph A Hill
- Department of Internal Medicine, Cardiology, University of Texas Southwestern Medical Center, Dallas, TX 75390-8573, USA.
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N-acetylcysteine prevents electrical remodeling and attenuates cellular hypertrophy in epicardial myocytes of rats with ascending aortic stenosis. Basic Res Cardiol 2012; 107:290. [PMID: 22855324 DOI: 10.1007/s00395-012-0290-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 05/22/2012] [Accepted: 07/18/2012] [Indexed: 02/07/2023]
Abstract
Pressure overload is associated with cardiac hypertrophy and electrical remodeling. Here, we investigate the effects of the antioxidant N-acetylcysteine (NAC) on the cellular cardiac electrophysiology of female Sprague-Dawley rats with ascending aortic stenosis (AS). Rats were treated with NAC (1 g/kg body weight) or control solution 1 week before the intervention and in the week following AS or sham operation. Seven days after the operation, blood pressure and left ventricular pressure were measured before the heart was excised. Single cells were isolated from epicardial and endocardial layers of the left ventricular free wall and investigated using the whole-cell patch-clamp technique. Systolic blood pressure and left ventricular peak pressure were not significantly altered in the NAC group. NAC reduced the increase (p < 0.001) in the relative left ventricular weight (p < 0.05) as well as the increase (p < 0.001) in cell capacitance in epicardial (p < 0.05), but not in endocardial myocytes of AS animals. The L-type Ca(2+) current (I (CaL)) was significantly increased by AS in epicardial (+19 % at 0 mV, p < 0.01) but not in endocardial myocytes. NAC completely prevented this increase in I (CaL) (p < 0.01). The current density of the transient outward K(+) current (I (to)) was not affected by AS or NAC. Action potential duration to 90 % repolarization was significantly prolonged in epicardial (p < 0.01) as well as in endocardial (p < 0.001) cells of AS animals. NAC prevented the AP prolongation in epicardial myocytes only (p < 0.05). We conclude that reducing oxidative stress in pressure overload can prevent electrical remodeling and ameliorate hypertrophy in epicardial but not in endocardial myocytes.
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Abstract
Electrical storm (ES), characterized by recurrent ventricular tachycardia/fibrillation, is a serious condition, adversely affecting prognosis in patients with implantable cardioverter/defibrillators. Electrical storm patients often die of progressive heart failure, but the underlying molecular basis is poorly understood. We have recently created an animal model of ES that features repetitive implantable cardioverter/defibrillator firing for recurrent ventricular fibrillation and found that ES events cause striking activation of Ca(2+)/calmodulin-dependent protein kinase II and prominent alteration of Ca(2+)-handling protein phosphorylation, possibly explaining mechanical dysfunction and arrhythmia promotion that characterize ES. Here, the pathophysiology and potential therapeutic strategies for ES, based on experimental and clinical studies by us and others, are described.
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Liu W, Chen J, Xu T, Tian W, Li Y, Zhang Z, Li W. Qiliqiangxin improves cardiac function in spontaneously hypertensive rats through the inhibition of cardiac chymase. Am J Hypertens 2012; 25:250-60. [PMID: 22089109 DOI: 10.1038/ajh.2011.219] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND This study was designed to investigate the effects and mechanism of action of the traditional Chinese drug formula, qiliqiangxin (QLQX), on cardiac function in spontaneously hypertensive rats (SHRs). METHODS We evaluated the effects of oral high-dose (4 g/kg/day, n = 7) and low-dose (1 g/kg/day, n = 7) QLQX on cardiac function in SHRs aged between 8 compared to control, the 8-week-old Wistar-Kyoto (WKY) rats. Echocardiography was performed to evaluate cardiac function and hemodynamic parameters. Hematoxylin and eosin (HE) and Masson's trichrome staining were performed, and the expression of myocardial angiotensin (Ang)-converting enzyme, chymase, transforming growth factor (TGF)-β, and collagen-type I and III were evaluated with real-time reverse transcription-PCR. Myocardial chymase, Ang-converting enzyme (ACE), and Ang II activities were measured with radioimmunoassay (RIA) techniques. Cardiac mast cells were detected with toluidine blue staining. RESULTS In SHRs, the number of chymase enzyme-positive mast cells increased in the left ventricle (LV) compared with WKY rats. QLQX significantly decreased mast cell density and cardiac chymase levels, and it improved ejection fraction values and cardiac systolic function compared with vehicle. Moreover, QLQX decreased left atrial diameters and improved the E/A ratio. QLQX suppressed collagen-type I and III and TGF-β mRNA levels, and Ang II activity, in a dose-dependent manner. Whereas no difference in ACE activity was found between SHRs, chymase expression and activity were significantly decreased with QLQX. CONCLUSIONS These data suggest that QLQX improves both systolic and diastolic cardiac function in SHRs through downregulating the cardiac chymase signaling pathway and chymase-mediated Ang II production.
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Cheng J, Xu L, Lai D, Guilbert A, Lim HJ, Keskanokwong T, Wang Y. CaMKII inhibition in heart failure, beneficial, harmful, or both. Am J Physiol Heart Circ Physiol 2012; 302:H1454-65. [PMID: 22287581 DOI: 10.1152/ajpheart.00812.2011] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Calmodulin-dependent protein kinase II (CaMKII) has been proposed to be a therapeutic target for heart failure (HF). However, the cardiac effect of chronic CaMKII inhibition in HF has not been well understood. We have tested alterations of Ca(2+) handling, excitation-contraction coupling, and in vivo β-adrenergic regulation in pressure-overload HF mice with CaMKIIδ knockout (KO). HF was produced in wild-type (WT) and KO mice 1 wk after severe thoracic aortic banding (sTAB) with a continuous left ventricle (LV) dilation and reduction of ejection fraction for up to 3 wk postbanding. Cardiac hypertrophy was similar between WT HF and KO HF mice. However, KO HF mice manifested exacerbation of diastolic function and reduction in cardiac reserve to β-adrenergic stimulation. Compared with WT HF, L-type calcium channel current (I(Ca)) density in KO HF LV was decreased without changes in I(Ca) activation and inactivation kinetics, whereas I(Ca) recovery from inactivation was accelerated and Ca(2+)-dependent I(Ca) facilitation, a positive staircase blunted in WT HF, was recovered. However, I(Ca) response to isoproterenol was reduced. KO HF myocytes manifested dramatic decrease in sarcoplasmic reticulum (SR) Ca(2+) leak and slowed cytostolic Ca(2+) concentration decline. Sarcomere shortening was increased, but relaxation was slowed. In addition, an increase in myofilament sensitivity to Ca(2+) and the slow skeletal muscle troponin I-to-cardiac troponin I ratio and interstitial fibrosis and a decrease in Na/Ca exchange function and myocyte apoptosis were observed in KO HF LV. CaMKIIδ KO cannot suppress severe pressure-overload-induced HF. Although cellular contractility is improved, it reduces in vivo cardiac reserve to β-adrenergic regulation and deteriorates diastolic function. Our findings challenge the strategy of CaMKII inhibition in HF.
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Affiliation(s)
- Jun Cheng
- Department of Pediatrics, Emory University, Atlanta, Georgia 30322, USA
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Cutler MJ, Jeyaraj D, Rosenbaum DS. Cardiac electrical remodeling in health and disease. Trends Pharmacol Sci 2011; 32:174-80. [PMID: 21316769 DOI: 10.1016/j.tips.2010.12.001] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 11/25/2010] [Accepted: 12/01/2010] [Indexed: 01/12/2023]
Abstract
Electrical remodeling of the heart takes place in response to both functional (altered electrical activation) and structural (including heart failure and myocardial infarction) stressors. These electrophysiological changes produce a substrate that is prone to malignant ventricular arrhythmias. Understanding the cellular and molecular mechanisms of electrical remodeling is important in elucidating potential therapeutic targets designed to alter maladaptive electrical remodeling. For example, altered patterns of electrical activation lead primarily to electrical remodeling, without significant structural remodeling. By contrast, secondary remodeling arises in response to a structural insult. In this article we review cardiac electrical remodeling (predominantly in the ventricle) with an emphasis on the mechanisms causing these adaptations. These mechanisms suggest novel therapeutic targets for the management or prevention of the most devastating manifestation of heart disease, sudden cardiac death (SCD).
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Affiliation(s)
- Michael J Cutler
- The Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio, USA
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Ca2+ disorder caused by rapid electrical field stimulation can be modulated by CaMKIIδ expression in primary rat atrial myocytes. Biochem Biophys Res Commun 2011; 409:287-92. [DOI: 10.1016/j.bbrc.2011.05.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Accepted: 05/02/2011] [Indexed: 11/19/2022]
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Fan X, Ma J, Wan W, Zhang P, Wang C, Wu L. Increased intracellular calcium concentration causes electrical turbulence in guinea pig ventricular myocytes. SCIENCE CHINA-LIFE SCIENCES 2011; 54:240-7. [PMID: 21416323 DOI: 10.1007/s11427-011-4146-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Accepted: 12/21/2010] [Indexed: 01/25/2023]
Abstract
Dysregulation of intracellular Ca(2+) homeostasis is associated with various pathological conditions and arrhythmogenesis of the heart. The objective of this study was to investigate the effects of an acute increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) on the electrophysiology of ventricular myocytes by mimicking intracellular Ca(2+) overload. The [Ca(2+)](i) was clamped to either a controlled (65-100 nmol L(-1)) or increased (1 μmol L(-1)) level. The transmembrane action potentials and ionic currents were recorded using whole-cell patch clamp techniques. We found that the acute increase in [Ca(2+)](i) shortened the action potential duration, reduced the action potential amplitude, maximum depolarization velocity and resting membrane potential, caused delayed after-depolarizations (DADs), and triggered activity-compared with these parameters in the control. The increased [Ca(2+)](i) augmented late I (Na) in a time-dependent manner, reduced I (CaL) and I (K1), and increased I (Kr) but not I (Ks). The results of this study can be used to explain calcium overload-induced ventricular arrhythmias.
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Affiliation(s)
- Xinrong Fan
- Cardio-Electrophysiological Research Laboratory, Medical College of Wuhan University of Science and Technology, Wuhan 430081, China
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The mechanisms underlying ICa heterogeneity across murine left ventricle. Mol Cell Biochem 2011; 352:239-46. [PMID: 21373807 DOI: 10.1007/s11010-011-0759-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2010] [Accepted: 02/17/2011] [Indexed: 10/18/2022]
Abstract
L-type calcium current (I(Ca)) plays a critical role in excitation-contraction coupling (ECC). Unlike transient outward K(+) current (I(to)), it is controversial whether I(Ca) transmural gradient exists in left ventricle. Although previous studies have shown some evidences for I(Ca) heterogeneity, the mechanism is still unknown. In this study, the authors recorded I(Ca) from epicardial (EPI) and endocardial (ENDO) myocytes isolated from murine left ventricle using patch-clamp technique. It was found that I(Ca) density was obviously larger in EPI than in ENDO (7.3 ± 0.3 pA/pF vs. 6.2 ± 0.2 pA/pF, at test potential of +10 mV, P < 0.05). The characteristics of I(Ca) showed no difference between these two regions except for the fast inactivation time constants (9.9 ± 0.9 ms in EPI vs. 13.5 ± 0.9 ms in ENDO, at test potential of +10 mV, P < 0.05). In addition, it was explored the molecular mechanism underlying I(Ca) transmural gradient by Western blot. The authors demonstrated that a higher activity of CaMKII in ENDO cells induced more nuclear translocation of p65, a component of nuclear factor-kappa B (NF-kB). Consequently, p65 in ENDO inhibited more transcription of Cav1.2, the main encoding gene for L-type calcium channels (LTCCs). These results reveal a difference in CaMKII/p65 signal pathway between EPI and ENDO that underlies this mechanism of I(Ca) heterogeneity in murine left ventricle.
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Massare J, Berry JM, Luo X, Rob F, Johnstone JL, Shelton JM, Bassel-Duby R, Hill JA, Naseem RH. Diminished cardiac fibrosis in heart failure is associated with altered ventricular arrhythmia phenotype. J Cardiovasc Electrophysiol 2011; 21:1031-7. [PMID: 20233273 DOI: 10.1111/j.1540-8167.2010.01736.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVES We sought to define the role of interstitial fibrosis in the proarrhythmic phenotype of failing ventricular myocardium. BACKGROUND Multiple cellular events that occur during pathological remodeling of the failing ventricle are implicated in the genesis of ventricular tachycardia (VT), including interstitial fibrosis. Recent studies suggest that ventricular fibrosis is reversible, and current anti-remodeling therapies attenuate ventricular fibrosis. However, the role of interstitial fibrosis in the proarrhythmic phenotype of failing ventricular myocardium is currently not well defined. METHODS Class II histone deacetylases (HDACs) have been implicated in promoting collagen biosynthesis. As these enzymes are inhibited by protein kinase D1 (PKD1), we studied mice with cardiomyocyte-specific transgenic over-expression of a constitutively active mutant of PKD1 (caPKD). caPKD mice were compared with animals in which cardiomyopathy was induced by severe thoracic aortic banding (sTAB). Hearts were analyzed by echocardiographic and electrocardiographic means. Interstitial fibrosis was assessed by histology and quantified biochemically. Ventricular arrhythmias were induced by closed-chest, intracardiac pacing. RESULTS Similar degrees of hypertrophic growth, systolic dysfunction and mortality were observed in the two models. In sTAB mice, robust ventricular fibrosis was readily detected, but myocardial collagen content was significantly reduced in caPKD mice. As expected, VT was readily inducible by programmed stimulation in sTAB mice and VT was less inducible in caPKD mice. Surprisingly, episodes of VT manifested longer cycle lengths and longer duration in caPKD mice. CONCLUSION Attenuated ventricular fibrosis is associated with reduced VT inducibility, increased VT duration, and significantly longer arrhythmia cycle length.
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Affiliation(s)
- Jorge Massare
- Department of Internal Medicine (Cardiology), University of Texas Southwestern Medical Center, Dallas, Texas 75390-8573, USA
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Keskanokwong T, Lim HJ, Zhang P, Cheng J, Xu L, Lai D, Wang Y. Dynamic Kv4.3-CaMKII unit in heart: an intrinsic negative regulator for CaMKII activation. Eur Heart J 2010; 32:305-15. [PMID: 21148163 DOI: 10.1093/eurheartj/ehq469] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Reduction of transient outward current (I(to)) and excessive activation of Ca(2+)/Calmodulin-dependent kinase II (CaMKII) are general features of ventricular myocytes in heart failure. We hypothesize that alterations of I(to) directly regulate CaMKII activation in cardiomyocytes. METHODS AND RESULTS A dynamic coupling of I(to) channel subunit Kv4.3 and inactive CaMKII was discovered in cardiomyocytes with the membrane predominant distribution by co-immunoprecipitation and fluorescence resonance energy transfer techniques. CaMKII dissociation from Kv4.3-CaMKII units caused a significant increase in CaMKII autophosphorylation and L-type calcium current (I(Ca)) facilitation. I(Ca) facilitation was blunted by the compartmental Ca²(+) chelator BAPTA but unaffected by bulk Ca²(+) chelator EGTA, implicating membrane-localized CaMKII. Kv4.3 overexpression reduced basal CaMKII autophosphorylation in myocytes and eliminated Ca²(+)-induced CaMKII activation. Kv4.3 blocks CaMKII activation by binding to the calmodulin binding sites, whereas Kv4.3 uncoupling releases these sites and leads to a substantial CaMKII activation. CONCLUSION Our results uncovered an important mechanism that regulates CaMKII activation in the heart and implicate I(to) channel alteration in pathological CaMKII activation.
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Affiliation(s)
- Thitima Keskanokwong
- Department of Pediatrics and Children's Healthcare of Atlanta, Emory University, Atlanta, GA 30322, USA
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Krishna A, Sun L, Valderrábano M, Palade PT, Clark JW. Modeling CICR in rat ventricular myocytes: voltage clamp studies. Theor Biol Med Model 2010; 7:43. [PMID: 21062495 PMCID: PMC3245510 DOI: 10.1186/1742-4682-7-43] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Accepted: 11/10/2010] [Indexed: 01/08/2023] Open
Abstract
Background The past thirty-five years have seen an intense search for the molecular mechanisms underlying calcium-induced calcium-release (CICR) in cardiac myocytes, with voltage clamp (VC) studies being the leading tool employed. Several VC protocols including lowering of extracellular calcium to affect Ca2+ loading of the sarcoplasmic reticulum (SR), and administration of blockers caffeine and thapsigargin have been utilized to probe the phenomena surrounding SR Ca2+ release. Here, we develop a deterministic mathematical model of a rat ventricular myocyte under VC conditions, to better understand mechanisms underlying the response of an isolated cell to calcium perturbation. Motivation for the study was to pinpoint key control variables influencing CICR and examine the role of CICR in the context of a physiological control system regulating cytosolic Ca2+ concentration ([Ca2+]myo). Methods The cell model consists of an electrical-equivalent model for the cell membrane and a fluid-compartment model describing the flux of ionic species between the extracellular and several intracellular compartments (cell cytosol, SR and the dyadic coupling unit (DCU), in which resides the mechanistic basis of CICR). The DCU is described as a controller-actuator mechanism, internally stabilized by negative feedback control of the unit's two diametrically-opposed Ca2+ channels (trigger-channel and release-channel). It releases Ca2+ flux into the cyto-plasm and is in turn enclosed within a negative feedback loop involving the SERCA pump, regulating[Ca2+]myo. Results Our model reproduces measured VC data published by several laboratories, and generates graded Ca2+ release at high Ca2+ gain in a homeostatically-controlled environment where [Ca2+]myo is precisely regulated. We elucidate the importance of the DCU elements in this process, particularly the role of the ryanodine receptor in controlling SR Ca2+ release, its activation by trigger Ca2+, and its refractory characteristics mediated by the luminal SR Ca2+ sensor. Proper functioning of the DCU, sodium-calcium exchangers and SERCA pump are important in achieving negative feedback control and hence Ca2+ homeostasis. Conclusions We examine the role of the above Ca2+ regulating mechanisms in handling various types of induced disturbances in Ca2+ levels by quantifying cellular Ca2+ balance. Our model provides biophysically-based explanations of phenomena associated with CICR generating useful and testable hypotheses.
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Affiliation(s)
- Abhilash Krishna
- Department of Electrical and Computer Engineering, Rice University, Houston, TX 77005, USA.
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Toischer K, Rokita AG, Unsöld B, Zhu W, Kararigas G, Sossalla S, Reuter SP, Becker A, Teucher N, Seidler T, Grebe C, Preuss L, Gupta SN, Schmidt K, Lehnart SE, Krüger M, Linke WA, Backs J, Regitz-Zagrosek V, Schäfer K, Field LJ, Maier LS, Hasenfuss G. Differential cardiac remodeling in preload versus afterload. Circulation 2010; 122:993-1003. [PMID: 20733099 DOI: 10.1161/circulationaha.110.943431] [Citation(s) in RCA: 239] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND Hemodynamic load regulates myocardial function and gene expression. We tested the hypothesis that afterload and preload, despite similar average load, result in different phenotypes. METHODS AND RESULTS Afterload and preload were compared in mice with transverse aortic constriction (TAC) and aortocaval shunt (shunt). Compared with sham mice, 6 hours after surgery, systolic wall stress (afterload) was increased in TAC mice (+40%; P<0.05), diastolic wall stress (preload) was increased in shunt (+277%; P<0.05) and TAC mice (+74%; P<0.05), and mean total wall stress was similarly increased in TAC (69%) and shunt mice (67%) (P=NS, TAC versus shunt; each P<0.05 versus sham). At 1 week, left ventricular weight/tibia length was significantly increased by 22% in TAC and 29% in shunt mice (P=NS, TAC versus shunt). After 24 hours and 1 week, calcium/calmodulin-dependent protein kinase II signaling was increased in TAC. This resulted in altered calcium cycling, including increased L-type calcium current, calcium transients, fractional sarcoplasmic reticulum calcium release, and calcium spark frequency. In shunt mice, Akt phosphorylation was increased. TAC was associated with inflammation, fibrosis, and cardiomyocyte apoptosis. The latter was significantly reduced in calcium/calmodulin-dependent protein kinase IIdelta-knockout TAC mice. A total of 157 mRNAs and 13 microRNAs were differentially regulated in TAC versus shunt mice. After 8 weeks, fractional shortening was lower and mortality was higher in TAC versus shunt mice. CONCLUSIONS Afterload results in maladaptive fibrotic hypertrophy with calcium/calmodulin-dependent protein kinase II-dependent altered calcium cycling and apoptosis. Preload is associated with Akt activation without fibrosis, little apoptosis, better function, and lower mortality. This indicates that different loads result in distinct phenotype differences that may require specific pharmacological interventions.
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Affiliation(s)
- Karl Toischer
- Department of Cardiology and Pneumology, Georg-August-University Goettingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany
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Abstract
Calcium/calmodulin-dependent kinase II (CaMKII) is a multifunctional serine/threonine kinase expressed abundantly in the heart. CaMKII targets numerous proteins involved in excitation-contraction coupling and excitability, and its activation may simultaneously contribute to heart failure and cardiac arrhythmias. In this review, we summarize the modulatory effects of CaMKII on cardiac ion channel function and expression and illustrate potential implications in the onset of arrhythmias via a computer model.
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Rellos P, Pike ACW, Niesen FH, Salah E, Lee WH, von Delft F, Knapp S. Structure of the CaMKIIdelta/calmodulin complex reveals the molecular mechanism of CaMKII kinase activation. PLoS Biol 2010; 8:e1000426. [PMID: 20668654 PMCID: PMC2910593 DOI: 10.1371/journal.pbio.1000426] [Citation(s) in RCA: 192] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Accepted: 06/08/2010] [Indexed: 11/25/2022] Open
Abstract
Structural and biophysical studies reveal how CaMKII kinases, which are important for cellular learning and memory, are switched on by binding of Ca2+/calmodulin. Long-term potentiation (LTP), a long-lasting enhancement in communication between neurons, is considered to be the major cellular mechanism underlying learning and memory. LTP triggers high-frequency calcium pulses that result in the activation of Calcium/Calmodulin (CaM)-dependent kinase II (CaMKII). CaMKII acts as a molecular switch because it remains active for a long time after the return to basal calcium levels, which is a unique property required for CaMKII function. Here we describe the crystal structure of the human CaMKIIδ/Ca2+/CaM complex, structures of all four human CaMKII catalytic domains in their autoinhibited states, as well as structures of human CaMKII oligomerization domains in their tetradecameric and physiological dodecameric states. All four autoinhibited human CaMKIIs were monomeric in the determined crystal structures but associated weakly in solution. In the CaMKIIδ/Ca2+/CaM complex, the inhibitory region adopted an extended conformation and interacted with an adjacent catalytic domain positioning T287 into the active site of the interacting protomer. Comparisons with autoinhibited CaMKII structures showed that binding of calmodulin leads to the rearrangement of residues in the active site to a conformation suitable for ATP binding and to the closure of the binding groove for the autoinhibitory helix by helix αD. The structural data, together with biophysical interaction studies, reveals the mechanism of CaMKII activation by calmodulin and explains many of the unique regulatory properties of these two essential signaling molecules. Enhanced version This article can also be viewed as an enhanced version in which the text of the article is integrated with interactive 3-D representations and animated transitions. Please note that a web plugin is required to access this enhanced functionality. Instructions for the installation and use of the Web plugin are available in Text S1. CaMKII enzymes transmit calcium ion (Ca2+) signals released inside the cell by regulating signal transduction pathways through phosphorylation: Ca2+ first binds to the small regulatory protein CaM; this Ca2+/CaM complex then binds to and activates the kinase, which phosphorylates other proteins in the cell. Since CaMKs remain active long after rapid Ca2+ pulses have dropped they function as molecular switches that turn on or off crucial cell functions in response to Ca2+ levels. The multifunctional CaMKII forms of this enzyme – of which there are four in human – are important in many processes including signaling in neurons and controlling of the heart rate. They are particularly abundant in the brain where they probably play a role in memory. CaMKII forms an exceptionally large, dodecameric complex. Here, we describe the crystal structure of this complex for each of the four human CaMKII catalytic domains in their autoinhibited states, a complex of CaMKII with Ca2+/CaM, as well as the structure of the oligomerization domain (the part of the protein that mediates complex formation) in its physiological dodecameric state and in a tetradecameric state. Detailed comparison of this large body of structural data together with biophysical studies has allowed us to better understand the structural mechanisms of CaMKII activation by CaM and to explain many of the complex regulatory features of these essential enzymes.
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Affiliation(s)
- Peter Rellos
- University of Oxford, Nuffield Department of Clinical Medicine, Structural Genomics Consortium, Oxford, United Kingdom
| | - Ashley C. W. Pike
- University of Oxford, Nuffield Department of Clinical Medicine, Structural Genomics Consortium, Oxford, United Kingdom
| | - Frank H. Niesen
- University of Oxford, Nuffield Department of Clinical Medicine, Structural Genomics Consortium, Oxford, United Kingdom
| | - Eidarus Salah
- University of Oxford, Nuffield Department of Clinical Medicine, Structural Genomics Consortium, Oxford, United Kingdom
| | - Wen Hwa Lee
- University of Oxford, Nuffield Department of Clinical Medicine, Structural Genomics Consortium, Oxford, United Kingdom
| | - Frank von Delft
- University of Oxford, Nuffield Department of Clinical Medicine, Structural Genomics Consortium, Oxford, United Kingdom
| | - Stefan Knapp
- University of Oxford, Nuffield Department of Clinical Medicine, Structural Genomics Consortium, Oxford, United Kingdom
- * E-mail:
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Xu L, Lai D, Cheng J, Lim HJ, Keskanokwong T, Backs J, Olson EN, Wang Y. Alterations of L-type calcium current and cardiac function in CaMKII{delta} knockout mice. Circ Res 2010; 107:398-407. [PMID: 20538682 DOI: 10.1161/circresaha.110.222562] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Recent studies have highlighted important roles of CaMKII in regulating Ca(2+) handling and excitation-contraction coupling. However, the cardiac effect of chronic CaMKII inhibition has not been well understood. OBJECTIVE We have tested the alterations of L-type calcium current (I(Ca)) and cardiac function in CaMKIIdelta knockout (KO) mouse left ventricle (LV). METHODS AND RESULTS We used the patch-clamp method to record I(Ca) in ventricular myocytes and found that in KO LV, basal I(Ca) was significantly increased without changing the transmural gradient of I(Ca) distribution. Substitution of Ba(2+) for Ca(2+) showed similar increase in I(Ba). There was no change in the voltage dependence of I(Ca) activation and inactivation. I(Ca) recovery from inactivation, however, was significantly slowed. In KO LV, the Ca(2+)-dependent I(Ca) facilitation (CDF) and I(Ca) response to isoproterenol (ISO) were significantly reduced. However, ISO response was reversed by beta2-adrenergic receptor (AR) inhibition. Western blots showed a decrease in beta1-AR and an increase in Ca(v)1.2, beta2-AR, and Galphai3 protein levels. Ca(2+) transient and sarcomere shortening in KO myocytes were unchanged at 1-Hz but reduced at 3-Hz stimulation. Echocardiography in conscious mice revealed an increased basal contractility in KO mice. However, cardiac reserve to work load and beta-adrenergic stimulation was reduced. Surprisingly, KO mice showed a reduced heart rate in response to work load or beta-adrenergic stimulation. CONCLUSIONS Our results implicate physiological CaMKII activity in maintaining normal I(Ca), Ca(2+) handling, excitation-contraction coupling, and the in vivo heart function in response to cardiac stress.
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Affiliation(s)
- Lin Xu
- Department of Pediatrics and Children's Healthcare of Atlanta, Emory University, GA, USA
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41
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Wang Y, Hill JA. Electrophysiological remodeling in heart failure. J Mol Cell Cardiol 2010; 48:619-32. [PMID: 20096285 DOI: 10.1016/j.yjmcc.2010.01.009] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Revised: 01/11/2010] [Accepted: 01/12/2010] [Indexed: 11/25/2022]
Abstract
Heart failure affects nearly 6 million Americans, with a half-million new cases emerging each year. Whereas up to 50% of heart failure patients die of arrhythmia, the diverse mechanisms underlying heart failure-associated arrhythmia are poorly understood. As a consequence, effectiveness of antiarrhythmic pharmacotherapy remains elusive. Here, we review recent advances in our understanding of heart failure-associated molecular events impacting the electrical function of the myocardium. We approach this from an anatomical standpoint, summarizing recent insights gleaned from pre-clinical models and discussing their relevance to human heart failure.
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Affiliation(s)
- Yanggan Wang
- Department of Pediatrics, Emory University, Atlanta, GA, USA.
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42
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Louch WE, Hougen K, Mørk HK, Swift F, Aronsen JM, Sjaastad I, Reims HM, Roald B, Andersson KB, Christensen G, Sejersted OM. Sodium accumulation promotes diastolic dysfunction in end-stage heart failure following Serca2 knockout. J Physiol 2009; 588:465-78. [PMID: 20008467 DOI: 10.1113/jphysiol.2009.183517] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Alterations in trans-sarcolemmal and sarcoplasmic reticulum (SR) Ca(2+) fluxes may contribute to impaired cardiomyocyte contraction and relaxation in heart failure. We investigated the mechanisms underlying heart failure progression in mice with conditional, cardiomyocyte-specific excision of the SR Ca(2+)-ATPase (SERCA) gene. At 4 weeks following gene deletion (4-week KO) cardiac function remained near normal values. However, end-stage heart failure developed by 7 weeks (7-week KO) as systolic and diastolic performance declined. Contractions in isolated myocytes were reduced between 4- and 7-week KO, and relaxation was slowed. Ca(2+) transients were similarly altered. Reduction in Ca(2+) transient magnitude resulted from complete loss of SR Ca(2+) release between 4- and 7-week KO, due to loss of a small remaining pool of SERCA2. Declining SR Ca(2+) release was partly offset by increased L-type Ca(2+) current, which was facilitated by AP prolongation in 7-week KO. Ca(2+) entry via reverse-mode Na(+)-Ca(2+) exchange (NCX) was also enhanced. Up-regulation of NCX and plasma membrane Ca(2+)-ATPase increased Ca(2+) extrusion rates in 4-week KO. Diastolic dysfunction in 7-week KO resulted from further SERCA2 loss, but also impaired NCX-mediated Ca(2+) extrusion following Na(+) accumulation. Reduced Na(+)-K(+)-ATPase activity contributed to the Na(+) gain. Normalizing [Na(+)] by dialysis increased the Ca(2+) decline rate in 7-week KO beyond 4-week values. Thus, while SERCA2 loss promotes both systolic and diastolic dysfunction, Na(+) accumulation additionally impairs relaxation in this model. Our observations indicate that if cytosolic Na(+) gain is prevented, up-regulated Ca(2+) extrusion mechanisms can maintain near-normal diastolic function in the absence of SERCA2.
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Affiliation(s)
- William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital Ullevaal, 0407 Oslo, Norway.
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43
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Benitah JP, Alvarez JL, Gómez AM. L-type Ca(2+) current in ventricular cardiomyocytes. J Mol Cell Cardiol 2009; 48:26-36. [PMID: 19660468 DOI: 10.1016/j.yjmcc.2009.07.026] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 07/09/2009] [Accepted: 07/27/2009] [Indexed: 12/24/2022]
Abstract
L-type Ca(2+) channels are mediators of Ca(2+) influx and the regulatory events accompanying it and are pivotal in the function and dysfunction of ventricular cardiac myocytes. L-type Ca(2+) channels are located in sarcolemma, including the T-tubules facing the sarcoplasmic reticulum junction, and are activated by membrane depolarization, but intracellular Ca(2+)-dependent inactivation limits Ca(2+) influx during action potential. I(CaL) is important in heart function because it triggers excitation-contraction coupling, modulates action potential shape and is involved in cardiac arrhythmia. L-type Ca(2+) channels are multi-subunit complexes that interact with several molecules involved in their regulations, notably by beta-adrenergic signaling. The present review highlights some of the recent findings on L-type Ca(2+) channel function, regulation, and alteration in acquired pathologies such as cardiac hypertrophy, heart failure and diabetic cardiomyopathy, as well as in inherited arrhythmic cardiac diseases such as Timothy and Brugada syndromes.
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Hardwick JC, Baran CN, Southerland EM, Ardell JL. Remodeling of the guinea pig intrinsic cardiac plexus with chronic pressure overload. Am J Physiol Regul Integr Comp Physiol 2009; 297:R859-66. [PMID: 19605763 DOI: 10.1152/ajpregu.00245.2009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chronic pressure overload (PO) is associated with cardiac hypertrophy and altered autonomic control of cardiac function, in which the latter may involve adaptations in central and/or peripheral cardiac neural control mechanisms. To evaluate the specific remodeling of the intrinsic cardiac nervous system following pressure overload, the descending thoracic aorta artery of the guinea pig was constricted approximately 20%, and the animals recovered for 9 wk. Thereafter, atrial neurons of the intrinsic cardiac plexus were isolated for electrophysiological and immunohistochemical analyses. Intracellular voltage recordings from intrinsic cardiac neurons demonstrated no significant changes in passive membrane properties or action potential depolarization compared with age-matched controls and sham-operated animals, but afterhyperpolarization duration was increased in PO animals. Neuronal excitability, as determined by the number of action potentials produced with depolarizing stimuli, was differentially increased in phasic neurons derived from PO animals in response to exogenously applied histamine compared with sham and age-matched controls. Conversely, pituitary adenylate cyclase-activating polypeptide-induced increases in intrinsic cardiac neuron evoked AP frequency were similar between control and PO animals. Immunohistochemical analysis demonstrated a twofold increase in the percentage of neurons immunoreactive for neuronal nitric oxide synthase in PO animals compared with control. The density of mast cells within the intrinsic cardiac plexus from PO animals was also increased twofold compared with preparations from control animals. These results indicate that congestive heart failure associated with chronic pressure overload induces a differential remodeling of intrinsic cardiac neurons and upregulation of neuronal responsiveness to specific neuromodulators.
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Affiliation(s)
- Jean C Hardwick
- Biology Dept., Ithaca College, 953 Danby Road, Ithaca, NY 14850, USA.
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Wang Y, Joyner RW, Wagner MB, Cheng J, Lai D, Crawford BH. Stretch-activated channel activation promotes early afterdepolarizations in rat ventricular myocytes under oxidative stress. Am J Physiol Heart Circ Physiol 2009; 296:H1227-35. [PMID: 19286952 DOI: 10.1152/ajpheart.00808.2008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Mechanical stretch and oxidative stress have been shown to prolong action potential duration (APD) and produce early afterdepolarizations (EADs). Here, we developed a simulation model to study the role of stretch-activated channel (SAC) currents in triggering EADs in ventricular myocytes under oxidative stress. We adapted our coupling clamp circuit so that a model ionic current representing the actual SAC current was injected into ventricular myocytes and added as a real-time current. This current was calculated as I(SAC) = G(SAC) * (V(m) - E(SAC)), where G(SAC) is the stretch-activated conductance, V(m) is the membrane potential, and E(SAC) is the reversal potential. In rat ventricular myocytes, application of G(SAC) did not produce sustained automaticity or EADs, although turn-on of G(SAC) did produce some transient automaticity at high levels of G(SAC). Exposure of myocytes to 100 microM H(2)O(2) induced significant APD prolongation and increase in intracellular Ca(2+) load and transient, but no EAD or sustained automaticity was generated in the absence of G(SAC). However, the combination of G(SAC) and H(2)O(2) consistently produced EADs at lower levels of G(SAC) (2.6 +/- 0.4 nS, n = 14, P < 0.05). Pacing myocytes at a faster rate further prolonged APD and promoted the development of EADs. SAC activation plays an important role in facilitating the development of EADs in ventricular myocytes under acute oxidative stress. This mechanism may contribute to the increased propensity to lethal ventricular arrhythmias seen in cardiomyopathies, where the myocardium stretch and oxidative stress generally coexist.
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Affiliation(s)
- Yanggan Wang
- Dept. of Pediatrics, Emory Univ., 2015 Uppergate Dr., Rm. 364, Atlanta, GA 30322, USA.
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