1
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Hantz ER, Tikunova SB, Belevych N, Davis JP, Reiser PJ, Lindert S. Targeting Troponin C with Small Molecules Containing Diphenyl Moieties: Calcium Sensitivity Effects on Striated Muscles and Structure-Activity Relationship. J Chem Inf Model 2023; 63:3462-3473. [PMID: 37204863 PMCID: PMC10496875 DOI: 10.1021/acs.jcim.3c00196] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Despite large investments from academia and industry, heart failure, which results from a disruption of the contractile apparatus, remains a leading cause of death. Cardiac muscle contraction is a calcium-dependent mechanism, which is regulated by the troponin protein complex (cTn) and specifically by the N-terminal domain of its calcium-binding subunit (cNTnC). There is an increasing need for the development of small molecules that increase calcium sensitivity without altering the systolic calcium concentration, thereby strengthening the cardiac function. Here, we examined the effect of our previously identified calcium-sensitizing small molecule, ChemBridge compound 7930079, in the context of several homologous muscle systems. The effect of this molecule on force generation in isolated cardiac trabeculae and slow skeletal muscle fibers was measured. Furthermore, we explored the use of Gaussian accelerated molecular dynamics in sampling highly predictive receptor conformations based on NMR-derived starting structures. Additionally, we took a rational computational approach for lead optimization based on lipophilic diphenyl moieties. This integrated structural-biochemical-physiological approach led to the identification of three novel low-affinity binders, which had similar binding affinities to the known positive inotrope trifluoperazine. The most potent identified calcium sensitizer was compound 16 with an apparent affinity of 117 ± 17 μM.
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Affiliation(s)
- Eric R. Hantz
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210
| | - Svetlana B. Tikunova
- Davis Heart and Lung Research Institute and Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, 43210
| | - Natalya Belevych
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH 43210
| | - Jonathan P. Davis
- Davis Heart and Lung Research Institute and Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, 43210
| | - Peter J. Reiser
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH 43210
| | - Steffen Lindert
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210
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2
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Cool AM, Lindert S. Umbrella Sampling Simulations of Cardiac Thin Filament Reveal Thermodynamic Consequences of Troponin I Inhibitory Peptide Mutations. J Chem Inf Model 2023; 63:3534-3543. [PMID: 37261389 PMCID: PMC10506665 DOI: 10.1021/acs.jcim.3c00388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The cardiac thin filament comprises F-actin, tropomyosin, and troponin (cTn). cTn is composed of three subunits: troponin C (cTnC), troponin I (cTnI), and troponin T (cTnT). To computationally study the effect of the thin filament on cTn activation events, we employed targeted molecular dynamics followed by umbrella sampling using a model of the thin filament to measure the thermodynamics of cTn transition events. Our simulations revealed that the thin filament causes an increase in the free energy required to open the cTnC hydrophobic patch and causes a more favorable interaction between this region and the cTnI switch peptide. Mutations to the cTn complex can lead to cardiomyopathy, a collection of diseases that present clinically with symptoms of hypertrophy or dilation of the cardiac muscle, leading to impairment of the heart's ability to function normally and ultimately myocardial infarction or heart failure. Upon introduction of cardiomyopathic mutations to R145 of cTnI, we observed a general decrease in the free energy of opening the cTnC hydrophobic patch, which is on par with previous experimental results. These mutations also exhibited a decrease in electrostatic interactions between cTnI-R145 and actin-E334. After introduction of a small molecule to the wild-type cTnI-actin interface to intentionally disrupt intersubunit contacts, we successfully observed similar thermodynamic consequences and disruptions to the same protein-protein contacts as observed with the cardiomyopathic mutations. Computational studies utilizing the cTn complex in isolation would have been unable to observe these effects, highlighting the importance of using a more physiologically relevant thin-filament model to investigate the global consequences of cardiomyopathic mutations to the cTn complex.
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Affiliation(s)
- Austin M. Cool
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210
| | - Steffen Lindert
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210
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3
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Cai F, Kampourakis T, Parijat P, Cockburn KT, Sykes BD. Conversion of a Cardiac Muscle Modulator from an Inhibitor to an Activator. ACS Med Chem Lett 2023; 14:530-533. [PMID: 37077384 PMCID: PMC10108394 DOI: 10.1021/acsmedchemlett.3c00033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 03/01/2023] [Indexed: 03/06/2023] Open
Abstract
The binding of calcium to cardiac troponin C (cTnC) enhances the binding of troponin I (cTnI) switch region to the regulatory domain of cTnC (cNTnC) and triggers muscle contraction. Several molecules alter the response of the sarcomere by targeting this interface; virtually all have an aromatic core that binds to the hydrophobic pocket of cNTnC and an aliphatic tail that interacts with the switch region of cTnI. W7 has been extensively studied, and the positively charged tail has been shown to be important for its inhibitory action. Herein we investigate the importance of the aromatic core of W7 by synthesizing compounds that have the core region of calcium activator dfbp-o with various lengths of the same tail (D-series). These compounds all bind more tightly to cNTnC-cTnI chimera (cChimera) than the analogous W-series compounds and show increased calcium sensitivity of force generation and ATPase activity, demonstrating that the cardiovascular system is tightly balanced.
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Affiliation(s)
- Fangze Cai
- Department
of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Thomas Kampourakis
- Randall
Centre for Cell and Molecular Biophysics, King’s College London, London SE1 1UL, United Kingdom
| | - Priyanka Parijat
- Randall
Centre for Cell and Molecular Biophysics, King’s College London, London SE1 1UL, United Kingdom
| | - Kieran T. Cockburn
- Department
of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Brian D. Sykes
- Department
of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
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4
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Parijat P, Ponnam S, Attili S, Campbell KS, El-Mezgueldi M, Pfuhl M, Kampourakis T. Discovery of novel cardiac troponin activators using fluorescence polarization-based high throughput screening assays. Sci Rep 2023; 13:5216. [PMID: 36997544 PMCID: PMC10063609 DOI: 10.1038/s41598-023-32476-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 03/28/2023] [Indexed: 04/03/2023] Open
Abstract
The large unmet demand for new heart failure therapeutics is widely acknowledged. Over the last decades the contractile myofilaments themselves have emerged as an attractive target for the development of new therapeutics for both systolic and diastolic heart failure. However, the clinical use of myofilament-directed drugs has been limited, and further progress has been hampered by incomplete understanding of myofilament function on the molecular level and screening technologies for small molecules that accurately reproduce this function in vitro. In this study we have designed, validated and characterized new high throughput screening platforms for small molecule effectors targeting the interactions between the troponin C and troponin I subunits of the cardiac troponin complex. Fluorescence polarization-based assays were used to screen commercially available compound libraries, and hits were validated using secondary screens and orthogonal assays. Hit compound-troponin interactions were characterized using isothermal titration calorimetry and NMR spectroscopy. We identified NS5806 as novel calcium sensitizer that stabilizes active troponin. In good agreement, NS5806 greatly increased the calcium sensitivity and maximal isometric force of demembranated human donor myocardium. Our results suggest that sarcomeric protein-directed screening platforms are suitable for the development of compounds that modulate cardiac myofilament function.
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Affiliation(s)
- Priyanka Parijat
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, SE1 1UL, UK
- British Heart Foundation Centre of Research Excellence, King's College London, London, SE1 1UL, UK
| | - Saraswathi Ponnam
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, SE1 1UL, UK
- British Heart Foundation Centre of Research Excellence, King's College London, London, SE1 1UL, UK
| | - Seetharamaiah Attili
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, SE1 1UL, UK
- British Heart Foundation Centre of Research Excellence, King's College London, London, SE1 1UL, UK
| | - Kenneth S Campbell
- Division of Cardiovascular Medicine and Department of Physiology, University of Kentucky, Lexington, KY, USA
| | - Mohammed El-Mezgueldi
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, SE1 1UL, UK
- British Heart Foundation Centre of Research Excellence, King's College London, London, SE1 1UL, UK
| | - Mark Pfuhl
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, SE1 1UL, UK
- British Heart Foundation Centre of Research Excellence, King's College London, London, SE1 1UL, UK
| | - Thomas Kampourakis
- Randall Centre for Cell and Molecular Biophysics, King's College London, London, SE1 1UL, UK.
- British Heart Foundation Centre of Research Excellence, King's College London, London, SE1 1UL, UK.
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5
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Hantz ER, Tikunova SB, Belevych N, Davis JP, Reiser PJ, Lindert S. Targeting Troponin C with Small Molecules Containing Diphenyl Moieties: Calcium Sensitivity Effects on Striated Muscle and Structure Activity Relationship. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.06.527323. [PMID: 36798160 PMCID: PMC9934531 DOI: 10.1101/2023.02.06.527323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Despite large investments from academia and industry, heart failure, which results from a disruption of the contractile apparatus, remains a leading cause of death. Cardiac muscle contraction is a calcium-dependent mechanism, which is regulated by the troponin protein complex (cTn) and specifically by the N-terminal domain of its calcium binding subunit (cNTnC). There is an increasing need for the development of small molecules that increase calcium sensitivity without altering systolic calcium concentration, thereby strengthening cardiac function. Here, we examined the effect of our previously identified calcium sensitizing small molecule, ChemBridge compound 7930079, in the context of several homologous muscle systems. The effect of this molecule on force generation in isolated cardiac trabeculae and slow skeletal muscle fibers was measured. Furthermore, we explored the use of Gaussian accelerated molecular dynamics in sampling highly predictive receptor conformations based on NMR derived starting structures. Additionally, we took a rational computational approach for lead optimization based on lipophilic diphenyl moieties. This led to the identification of three novel low affinity binders, which had similar binding affinities to known positive inotrope trifluoperazine. The most potent identified calcium sensitizer was compound 16 with an apparent affinity of 117 ± 17 μM .
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Affiliation(s)
- Eric R. Hantz
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210
| | - Svetlana B. Tikunova
- Davis Heart and Lung Research Institute and Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, 43210
| | - Natalya Belevych
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH 43210
| | - Jonathan P. Davis
- Davis Heart and Lung Research Institute and Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, 43210
| | - Peter J. Reiser
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH 43210
| | - Steffen Lindert
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, 43210,Correspondence to: Department of Chemistry and Biochemistry, Ohio State University, 2114 Newman & Wolfrom Laboratory, 100 W. 18th Avenue, Columbus, OH 43210, 614-292-8284 (office), 614-292-1685 (fax),
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6
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Dong Q, Ou W, Wang M, Jiang T, Weng Y, Zhou X, Tang X. Study on influencing factors of anthracycline-induced subclinical cardiotoxicity in DLBCL patients administered (R)-CHOP. BMC Cancer 2022; 22:988. [PMID: 36115970 PMCID: PMC9482309 DOI: 10.1186/s12885-022-10085-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 09/12/2022] [Indexed: 07/10/2024] Open
Abstract
Background Anthracycline-induced cardiotoxicity is an irreversible cardiac cell injury. Therefore, it’s very important to identify influencing factors of anthracycline-induced subclinical cardiotoxicity (AISC). This study was designed to analyze the influencing factors of AISC in patients with diffuse large B-cell lymphoma (DLBCL) treated with the (R)-CHOP chemotherapy regimen. Methods This is an ongoing observational prospective clinical trial. All patients underwent conventional echocardiography and speckle tracking echocardiography at the time of enrollment and during treatment. Changes of global longitudinal peak systolic strain were assessed after 3 cycles of (R)-CHOP chemotherapy, and patients were divided into the AISC and No-AISC groups. Demographic data, clinical variables, and biochemical variables were measured. Regression models, receiver operating characteristic curve analysis, and difference values were used to explore the relationships between variables and AISC. Results Among 70 patients who completed 3 cycles of (R)-CHOP chemotherapy, 26 developed AISC. In multiple logistic regression, HDL-C (P = 0.047), ApoA1 (P = 0.022), TG (P = 0.029) and e’ (P = 0.008) were associated with AISC. The combination of HDL-C and NT-proBNP had the highest area under curves (AUC) for the diagnosis of AISC than HDL-C and NT-proBNP alone (AUC = 0.752, 95%CI: 0.63–0.87, P = 0.001). Between the No-AISC and AISC groups, there was no significant difference in HDL-C, ApoA1, and e’ at baseline and after 3 cycles of chemotherapy, respectively. The dynamic changes of HDL-C, ApoA1, and e’ from baseline to the end of the 3rd cycle of chemotherapy showed statistically significant differences. Conclusions HDL-C, ApoA1, TG, and e’ are independent predictive factors in DLBCL cases treated with the (R)-CHOP chemotherapy regimen. The combination of HDL-C and NT-proBNP may improve the predictive ability for AISC in patients with DLBCL administered 3 cycles of (R)-CHOP chemotherapy. Dynamic changes of HDL-C, ApoA1, and e’ may be meaningful for predicting AISC. Trial registration Our study was registered in the Chinese Clinical Trial Registry (Approval ID. ChiCTR2100054721 http://www.chictr.org.cn/showproj.aspx?proj=145082).
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7
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The importance of pharmacokinetics, pharmacodynamic and repetitive use of levosimendan. Biomed Pharmacother 2022; 153:113391. [DOI: 10.1016/j.biopha.2022.113391] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Revised: 07/06/2022] [Accepted: 07/07/2022] [Indexed: 12/15/2022] Open
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8
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Mahmud Z, Tikunova S, Belevych N, Wagg CS, Zhabyeyev P, Liu PB, Rasicci DV, Yengo CM, Oudit GY, Lopaschuk GD, Reiser PJ, Davis JP, Hwang PM. Small Molecule RPI-194 Stabilizes Activated Troponin to Increase the Calcium Sensitivity of Striated Muscle Contraction. Front Physiol 2022; 13:892979. [PMID: 35755445 PMCID: PMC9213791 DOI: 10.3389/fphys.2022.892979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 05/10/2022] [Indexed: 11/13/2022] Open
Abstract
Small molecule cardiac troponin activators could potentially enhance cardiac muscle contraction in the treatment of systolic heart failure. We designed a small molecule, RPI-194, to bind cardiac/slow skeletal muscle troponin (Cardiac muscle and slow skeletal muscle share a common isoform of the troponin C subunit.) Using solution NMR and stopped flow fluorescence spectroscopy, we determined that RPI-194 binds to cardiac troponin with a dissociation constant KD of 6-24 μM, stabilizing the activated complex between troponin C and the switch region of troponin I. The interaction between RPI-194 and troponin C is weak (KD 311 μM) in the absence of the switch region. RPI-194 acts as a calcium sensitizer, shifting the pCa50 of isometric contraction from 6.28 to 6.99 in mouse slow skeletal muscle fibers and from 5.68 to 5.96 in skinned cardiac trabeculae at 100 μM concentration. There is also some cross-reactivity with fast skeletal muscle fibers (pCa50 increases from 6.27 to 6.52). In the slack test performed on the same skinned skeletal muscle fibers, RPI-194 slowed the velocity of unloaded shortening at saturating calcium concentrations, suggesting that it slows the rate of actin-myosin cross-bridge cycling under these conditions. However, RPI-194 had no effect on the ATPase activity of purified actin-myosin. In isolated unloaded mouse cardiomyocytes, RPI-194 markedly decreased the velocity and amplitude of contractions. In contrast, cardiac function was preserved in mouse isolated perfused working hearts. In summary, the novel troponin activator RPI-194 acts as a calcium sensitizer in all striated muscle types. Surprisingly, it also slows the velocity of unloaded contraction, but the cause and significance of this is uncertain at this time. RPI-194 represents a new class of non-specific troponin activator that could potentially be used either to enhance cardiac muscle contractility in the setting of systolic heart failure or to enhance skeletal muscle contraction in neuromuscular disorders.
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Affiliation(s)
- Zabed Mahmud
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - Svetlana Tikunova
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, United States
| | - Natalya Belevych
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, United States
| | - Cory S Wagg
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
| | - Pavel Zhabyeyev
- Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Philip B Liu
- Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - David V Rasicci
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, University Park, PA, United States
| | - Christopher M Yengo
- Department of Cellular and Molecular Physiology, College of Medicine, Pennsylvania State University, University Park, PA, United States
| | - Gavin Y Oudit
- Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Gary D Lopaschuk
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada
| | - Peter J Reiser
- Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, United States
| | - Jonathan P Davis
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, United States
| | - Peter M Hwang
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada.,Department of Medicine, University of Alberta, Edmonton, AB, Canada
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9
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Cai F, Kampourakis T, Cockburn KT, Sykes BD. Drugging the Sarcomere, a Delicate Balance: Position of N-Terminal Charge of the Inhibitor W7. ACS Chem Biol 2022; 17:1495-1504. [PMID: 35649123 DOI: 10.1021/acschembio.2c00126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
W7 is a sarcomere inhibitor that decreases the calcium sensitivity of force development in cardiac muscle. W7 binds to the interface of the regulatory domain of cardiac troponin C (cNTnC) and the switch region of troponin I (cTnI), decreasing the binding of cTnI to cNTnC, presumably by electrostatic repulsion between the -NH3+ group of W7 and basic amino acids in cTnI. W7 analogs with a -CO2- tail are inactive. To evaluate the importance of the location of the charged -NH3+, we used a series of compounds W4, W6, W8, and W9, which have three less, one less, one more, and two more methylene groups in the tail region than W7. W6, W8, and W9 all bind tighter to cNTnC-cTnI chimera (cChimera) than W7, while W4 binds weaker. W4 and, strikingly, W6 have no effect on calcium sensitivity of force generation, while W8 and W9 decrease calcium sensitivity, but less than W7. The structures of the cChimera-W6 and cChimera-W8 complexes reveal that W6 and W8 bind to the same hydrophobic cleft as W7, with the aliphatic tail taking a similar route to the surface. NMR relaxation data show that internal flexibility in the tail of W7 is very limited. Alignment of the cChimera-W7 structure with the recent cryoEM structures of the cardiac sarcomere in the diastolic and systolic states reveals the critical location of the amino group. Small molecule induced structural changes can therefore affect the tightly balanced equilibrium between tethered components required for rapid contraction.
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Affiliation(s)
- Fangze Cai
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - Thomas Kampourakis
- Randall Centre for Cell and Molecular Biophysics, King's College London, London SE1 1UL, United Kingdom
| | - Kieran T Cockburn
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
| | - Brian D Sykes
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
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10
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Cai F, Kampourakis T, Klein BA, Sykes BD. A Potent Fluorescent Reversible-Covalent Inhibitor of Cardiac Muscle Contraction. ACS Med Chem Lett 2021; 12:1503-1507. [PMID: 34531960 DOI: 10.1021/acsmedchemlett.1c00366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 08/19/2021] [Indexed: 11/28/2022] Open
Abstract
Compounds that directly modulate the response of the cardiac sarcomere have potential in the treatment of cardiac disease. While a number of sarcomere activators have been discovered and extensively studied, very few inhibitors have been identified. We report a potent cardiac sarcomere inhibitor, DN-F01, targeting the cardiac muscle thin filament protein troponin complex. Functional studies show that DN-F01 has a strong inhibitory calcium-dependent effect on cardiac myofibrillar ATPase activity with an IC50 value of 11 ± 4 nmol/L. DN-F01 is shown to bind to a cardiac troponin C-troponin I chimera (cChimera) with a K D of ∼50 nM using fluorescence spectroscopy, indicating that troponin is the likely target for DN-F01. NMR titrations of DN-F01 to C35S and A-Cys cChimera show covalent and noncovalent binding of DN-F01 bound to the calcium-saturated cChimera.
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Affiliation(s)
- Fangze Cai
- Department of Biochemistry, University of Alberta, Edmonton AB T6G 2R3, Canada
| | - Thomas Kampourakis
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London SE1 1UL, United Kingdom
| | - Brittney A. Klein
- Department of Biochemistry, University of Alberta, Edmonton AB T6G 2R3, Canada
| | - Brian D. Sykes
- Department of Biochemistry, University of Alberta, Edmonton AB T6G 2R3, Canada
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11
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Genchev GZ, Kobayashi M, Kobayashi T, Lu H. Molecular dynamics provides new insights into the mechanism of calcium signal transduction and interdomain interactions in cardiac troponin. FEBS Open Bio 2021; 11:1841-1853. [PMID: 33085832 PMCID: PMC8255835 DOI: 10.1002/2211-5463.13009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 10/05/2020] [Accepted: 10/17/2020] [Indexed: 12/16/2022] Open
Abstract
Understanding the regulation of cardiac muscle contraction at a molecular level is crucial for the development of therapeutics for heart conditions. Despite the availability of atomic structures of the protein components of cardiac muscle thin filaments, detailed insights into their dynamics and response to calcium are yet to be fully depicted. In this study, we used molecular dynamics simulations of the core domains of the cardiac muscle protein troponin to characterize the equilibrium dynamics of its calcium-bound and calcium-free forms, with a focus on elements of cardiac muscle contraction activation and deactivation, that is, calcium binding to the cardiac troponin Ca2+ -binding subunit (TnC) and the release of the switch region of the troponin inhibitory subunit (TnI) from TnC. The process of calcium binding to the TnC binding site is described as a three-step process commencing with calcium capture by the binding site residues, followed by cooperative residue interplay bringing the calcium ion to the binding site, and finally, calcium-water exchange. Furthermore, we uncovered a set of TnC-TnI interdomain interactions that are critical for TnC N-lobe hydrophobic pocket dynamics. Absence of these interactions allows the closure of the TnC N-lobe hydrophobic pocket while the TnI switch region remains expelled, whereas if the interactions are maintained, the hydrophobic pocket remains open. Modification of these interactions may fine-tune the ability of the TnC N-lobe hydrophobic pocket to close or remain open, modulate cardiac contractility and present potential therapy-relevant targets.
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Affiliation(s)
- Georgi Z Genchev
- Center for Biomedical Informatics, Shanghai Children's Hospital, Shanghai, China.,SJTU-Yale Joint Center for Biostatistics, Shanghai Jiao Tong University, Shanghai, China.,Bulgarian Institute for Genomics and Precision Medicine, Sofia, Bulgaria.,Bioinformatics Program, Department of Bioengineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Minae Kobayashi
- Department of Physiology and Biophysics and Center for Cardiovascular Research, University of Illinois at Chicago College of Medicine, Chicago, IL, USA
| | - Tomoyoshi Kobayashi
- Department of Physiology and Biophysics and Center for Cardiovascular Research, University of Illinois at Chicago College of Medicine, Chicago, IL, USA
| | - Hui Lu
- Center for Biomedical Informatics, Shanghai Children's Hospital, Shanghai, China.,SJTU-Yale Joint Center for Biostatistics, Shanghai Jiao Tong University, Shanghai, China.,Department of Bioinformatics and Biostatistics, Shanghai Jiao Tong University, Shanghai, China
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12
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Li MX, Mercier P, Hartman JJ, Sykes BD. Structural Basis of Tirasemtiv Activation of Fast Skeletal Muscle. J Med Chem 2021; 64:3026-3034. [PMID: 33703886 DOI: 10.1021/acs.jmedchem.0c01412] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Troponin regulates the calcium-mediated activation of skeletal muscle. Muscle weakness in diseases such as amyotrophic lateral sclerosis and spinal muscular atrophy occurs from diminished neuromuscular output. The first direct fast skeletal troponin activator, tirasemtiv, amplifies the response of muscle to neuromuscular input. Tirasemtiv binds selectively and strongly to fast skeletal troponin, slowing the rate of calcium release and sensitizing muscle to calcium. We report the solution NMR structure of tirasemtiv bound to a fast skeletal troponin C-troponin I chimera. The structure reveals that tirasemtiv binds in a hydrophobic pocket between the regulatory domain of troponin C and the switch region of troponin I, which overlaps with that of Anapoe in the X-ray structure of skeletal troponin. Multiple interactions stabilize the troponin C-troponin I interface, increase the affinity of troponin C for the switch region of fast skeletal troponin I, and drive the equilibrium toward the active state.
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Affiliation(s)
- Monica X Li
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Pascal Mercier
- National High Field NMR Centre, University of Alberta, Edmonton, AB T6G 2E1, Canada
| | - James J Hartman
- Cytokinetics, Inc., South San Francisco, California 94080, United States
| | - Brian D Sykes
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
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13
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Cai F, Robertson IM, Kampourakis T, Klein BA, Sykes BD. The Role of Electrostatics in the Mechanism of Cardiac Thin Filament Based Sensitizers. ACS Chem Biol 2020; 15:2289-2298. [PMID: 32633482 DOI: 10.1021/acschembio.0c00519] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Heart muscle contraction is regulated by calcium binding to cardiac troponin C. This induces troponin I (cTnI) switch region binding to the regulatory domain of troponin C (cNTnC), pulling the cTnI inhibitory region off actin and triggering muscle contraction. Small molecules targeting this cNTnC-cTnI interface have potential in the treatment of heart disease. Most of these have an aromatic core which binds to the hydrophobic core of cNTnC, and a polar and often charged 'tail'. The calmodulin antagonist W7 is unique in that it acts as calcium desensitizer. W7 binds to the interface of cNTnC and cTnI switch region and weakens cTnI binding, possibly by electrostatic repulsion between the positively charged terminal amino group of W7 and the positively charged RRVR144-147 region of cTnI. To evaluate the role of electrostatics, we synthesized A7, where the amino group of W7 was replaced with a carboxyl group. We determined the high-resolution solution NMR structure of A7 bound to a cNTnC-cTnI chimera. The structure shows that A7 does not change the overall conformation of the cNTnC-cTnI interface, and the naphthalene ring of A7 sits in the same hydrophobic pocket as that of W7, but the charged tail takes a different route to the surface of the complex, especially with respect to the position of the switch region of cTnI. We measured the affinities of A7 for cNTnC and the cNTnC-cTnI complex and that of the cTnI switch peptide for the cNTnC-A7 complex. We also compared the binding of W7 and A7 for two cNTnC-cTnI chimeras, differing in the presence or absence of the RRVR region of cTnI. A7 decreased the binding affinity of cTnI to cNTnC substantially less than W7 and bound more tightly to the more positively charged chimera. We tested the effects of W7 and A7 on the force-calcium relation of demembranated rat right ventricular trabeculae and demonstrated that A7 has a much weaker desensitization effect than W7. We also synthesized A6, which has one less methylene group on the hydrocarbon chain than A7. A6 did not affect binding of cTnI switch peptide nor change the calcium sensitivity of ventricular trabeculae. These results suggest that the negative inotropic effect of W7 may result from a combination of electrostatic repulsion and steric hindrance with cTnI.
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Affiliation(s)
- Fangze Cai
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Ian M. Robertson
- Ministry of Health, Government of Alberta, Edmonton, AB T5J 1S6, Canada
| | - Thomas Kampourakis
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London SE1 1UL, United Kingdom
| | - Brittney A. Klein
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
| | - Brian D. Sykes
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2R3, Canada
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14
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Potential of the Cardiovascular Drug Levosimendan in the Management of Amyotrophic Lateral Sclerosis: An Overview of a Working Hypothesis. J Cardiovasc Pharmacol 2020; 74:389-399. [PMID: 31730560 DOI: 10.1097/fjc.0000000000000728] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Levosimendan is a calcium sensitizer that promotes myocyte contractility through its calcium-dependent interaction with cardiac troponin C. Administered intravenously, it has been used for nearly 2 decades to treat acute and advanced heart failure and to support the heart function in various therapy settings characterized by low cardiac output. Effects of levosimendan on noncardiac muscle suggest a possible new application in the treatment of people with amyotrophic lateral sclerosis (ALS), a neuromuscular disorder characterized by progressive weakness, and eventual paralysis. Previous attempts to improve the muscle response in ALS patients and thereby maintain respiratory function and delay progression of disability have produced some mixed results. Continuing this line of investigation, levosimendan has been shown to enhance in vitro the contractility of the diaphragm muscle fibers of non-ALS patients and to improve in vivo diaphragm neuromuscular efficiency in healthy subjects. Possible positive effects on respiratory function in people with ALS were seen in an exploratory phase 2 study, and a phase 3 clinical trial is now underway to evaluate the potential benefit of an oral form of levosimendan on both respiratory and overall functions in patients with ALS. Here, we will review the various known pharmacologic effects of levosimendan, considering their relevance to people living with ALS.
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15
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Papp Z, Agostoni P, Alvarez J, Bettex D, Bouchez S, Brito D, Černý V, Comin-Colet J, Crespo-Leiro MG, Delgado JF, Édes I, Eremenko AA, Farmakis D, Fedele F, Fonseca C, Fruhwald S, Girardis M, Guarracino F, Harjola VP, Heringlake M, Herpain A, Heunks LM, Husebye T, Ivancan V, Karason K, Kaul S, Kivikko M, Kubica J, Masip J, Matskeplishvili S, Mebazaa A, Nieminen MS, Oliva F, Papp JG, Parissis J, Parkhomenko A, Põder P, Pölzl G, Reinecke A, Ricksten SE, Riha H, Rudiger A, Sarapohja T, Schwinger RH, Toller W, Tritapepe L, Tschöpe C, Wikström G, von Lewinski D, Vrtovec B, Pollesello P. Levosimendan Efficacy and Safety: 20 years of SIMDAX in Clinical Use. Card Fail Rev 2020; 6:e19. [PMID: 32714567 PMCID: PMC7374352 DOI: 10.15420/cfr.2020.03] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 03/16/2020] [Indexed: 12/12/2022] Open
Abstract
Levosimendan was first approved for clinic use in 2000, when authorisation was granted by Swedish regulatory authorities for the haemodynamic stabilisation of patients with acutely decompensated chronic heart failure. In the ensuing 20 years, this distinctive inodilator, which enhances cardiac contractility through calcium sensitisation and promotes vasodilatation through the opening of adenosine triphosphate-dependent potassium channels on vascular smooth muscle cells, has been approved in more than 60 jurisdictions, including most of the countries of the European Union and Latin America. Areas of clinical application have expanded considerably and now include cardiogenic shock, takotsubo cardiomyopathy, advanced heart failure, right ventricular failure and pulmonary hypertension, cardiac surgery, critical care and emergency medicine. Levosimendan is currently in active clinical evaluation in the US. Levosimendan in IV formulation is being used as a research tool in the exploration of a wide range of cardiac and non-cardiac disease states. A levosimendan oral form is at present under evaluation in the management of amyotrophic lateral sclerosis. To mark the 20 years since the advent of levosimendan in clinical use, 51 experts from 23 European countries (Austria, Belgium, Croatia, Cyprus, Czech Republic, Estonia, Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Norway, Poland, Portugal, Russia, Slovenia, Spain, Sweden, Switzerland, UK and Ukraine) contributed to this essay, which evaluates one of the relatively few drugs to have been successfully introduced into the acute heart failure arena in recent times and charts a possible development trajectory for the next 20 years.
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Affiliation(s)
- Zoltán Papp
- Department of Cardiology, Faculty of Medicine, University of Debrecen Debrecen, Hungary
| | - Piergiuseppe Agostoni
- Department of Clinical Sciences and Community Health, Centro Cardiologico Monzino, IRCCS Milan, Italy
| | - Julian Alvarez
- Department of Surgery, School of Medicine, University of Santiago de Compostela Santiago de Compostela, Spain
| | - Dominique Bettex
- Institute of Anaesthesiology, University Hospital of Zurich Zurich, Switzerland
| | - Stefan Bouchez
- Department of Anaesthesiology, University Hospital Ghent, Belgium
| | - Dulce Brito
- Cardiology Department, Centro Hospitalar Universitario Lisboa Norte, CCUI, Faculdade de Medicina, Universidade de Lisboa Lisbon, Portugal
| | - Vladimir Černý
- Department of Anaesthesiology, Perioperative Medicine and Intensive Care, Masaryk Hospital, J.E. Purkinje University Usti nad Labem, Czech Republic
| | - Josep Comin-Colet
- Heart Diseases Institute, Hospital Universitari de Bellvitge Barcelona, Spain
| | - Marisa G Crespo-Leiro
- Complexo Hospitalario Universitario A Coruña (CHUAC), CIBERCV, Instituto de Investigacion Biomedica A Coruña (INIBIC), Universidad de a Coruña (UDC) La Coruña, Spain
| | - Juan F Delgado
- Heart Failure and Transplant Program, Cardiology Department, University Hospital 12 Octubre Madrid, Spain
| | - Istvan Édes
- Department of Cardiology, Faculty of Medicine, University of Debrecen Debrecen, Hungary
| | - Alexander A Eremenko
- Department of Cardiac Intensive Care, Petrovskii National Research Centre of Surgery, Sechenov University Moscow, Russia
| | - Dimitrios Farmakis
- Department of Cardiology, Medical School, University of Cyprus Nicosia, Cyprus
| | - Francesco Fedele
- Department of Cardiovascular, Respiratory, Nephrology, Anaesthesiology and Geriatric Sciences, La Sapienza University of Rome Rome, Italy
| | - Cândida Fonseca
- Heart Failure Clinic, São Francisco Xavier Hospital, CHLO Lisbon, Portugal
| | - Sonja Fruhwald
- Department of Anaesthesiology and Intensive Care Medicine, Division of Anaesthesiology for Cardiovascular Surgery and Intensive Care Medicine, Medical University of Graz Graz, Austria
| | - Massimo Girardis
- Struttura Complessa di Anestesia 1, Policlinico di Modena Modena, Italy
| | - Fabio Guarracino
- Dipartimento di Anestesia e Terapie Intensive, Azienda Ospedaliero-Universitaria Pisana Pisa, Italy
| | - Veli-Pekka Harjola
- Emergency Medicine, Meilahti Central University Hospital, University of Helsinki Helsinki, Finland
| | - Matthias Heringlake
- Department of Anaesthesiology and Intensive Care Medicine, University of Lübeck Lübeck, Germany
| | - Antoine Herpain
- Department of Intensive Care, Hôpital Erasme Brussels, Belgium
| | - Leo Ma Heunks
- Department of Intensive Care Medicine, Amsterdam UMC Amsterdam, the Netherlands
| | - Tryggve Husebye
- Department of Cardiology, Oslo University Hospital Ullevaal Oslo, Norway
| | - Višnja Ivancan
- Department of Anaesthesiology, Reanimatology and Intensive Care, University Hospital Centre Zagreb, Croatia
| | - Kristjan Karason
- Departments of Cardiology and Transplantation, Sahlgrenska University Hospital Gothenburg, Sweden
| | - Sundeep Kaul
- Intensive Care Unit, National Health Service Leeds, UK
| | - Matti Kivikko
- Global Medical Affairs, R&D, Orion Pharma Espoo, Finland
| | - Janek Kubica
- Department of Cardiology and Internal Medicine, Nicolaus Copernicus University Torun, Poland
| | - Josep Masip
- Intensive Care Department, Consorci Sanitari Integral, University of Barcelona Barcelona, Spain
| | | | - Alexandre Mebazaa
- Department of Anaesthesiology and Critical Care Medicine, AP-HP, Saint Louis and Lariboisière University Hospitals Paris, France
| | | | - Fabrizio Oliva
- Department of Cardiology, Niguarda Ca'Granda Hospital Milan, Italy
| | - Julius-Gyula Papp
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, University of Szeged Szeged, Hungary
| | - John Parissis
- Second Department of Cardiology, Attikon University Hospital, National and Kapodistrian University of Athens Athens, Greece
| | - Alexander Parkhomenko
- Emergency Cardiology Department, National Scientific Centre MD Strazhesko Institute of Cardiology Kiev, Ukraine
| | - Pentti Põder
- Department of Cardiology, North Estonia Medical Centre Tallinn, Estonia
| | - Gerhard Pölzl
- Department of Internal Medicine III, Cardiology and Angiology, Medical University of Innsbruck Innsbruck, Austria
| | - Alexander Reinecke
- Klinik für Innere Medizin III, Kardiologie, Universitätsklinikum Schleswig-Holstein Kiel, Germany
| | - Sven-Erik Ricksten
- Department of Anaesthesiology and Intensive Care, Sahlgrenska University Hospital Gothenburg, Sweden
| | - Hynek Riha
- Cardiothoracic Anaesthesiology and Intensive Care, Department of Anaesthesiology and Intensive Care Medicine, Institute for Clinical and Experimental Medicine Prague, Czech Republic
| | - Alain Rudiger
- Department of Medicine, Spittal Limmattal Schlieren, Switzerland
| | | | - Robert Hg Schwinger
- Medizinische Klinik II, Klinikum Weiden, Teaching Hospital of University of Regensburg Weiden, Germany
| | - Wolfgang Toller
- Department of Anaesthesiology and Intensive Care Medicine, Medical University of Graz Graz, Austria
| | - Luigi Tritapepe
- Anaesthesia and Intensive Care Division, San Camillo-Forlanini Hospital Rome, Italy
| | - Carsten Tschöpe
- Department of Cardiology, Campus Virchow Klinikum, Charité - University Medicine Berlin Berlin, Germany
| | - Gerhard Wikström
- Institute of Medical Sciences, Uppsala University Uppsala, Sweden
| | - Dirk von Lewinski
- Department of Cardiology, Myokardiale Energetik und Metabolismus Research Unit, Medical University of Graz Graz, Austria
| | - Bojan Vrtovec
- Advanced Heart Failure and Transplantation Centre, Department of Cardiology, University Clinical Centre Ljubljana, Slovenia
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16
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Papp Z, Agostoni P, Alvarez J, Bettex D, Bouchez S, Brito D, Černý V, Comin-Colet J, Crespo-Leiro MG, Delgado JF, Édes I, Eremenko AA, Farmakis D, Fedele F, Fonseca C, Fruhwald S, Girardis M, Guarracino F, Harjola VP, Heringlake M, Herpain A, Heunks LMA, Husebye T, Ivancan V, Karason K, Kaul S, Kivikko M, Kubica J, Masip J, Matskeplishvili S, Mebazaa A, Nieminen MS, Oliva F, Papp JG, Parissis J, Parkhomenko A, Põder P, Pölzl G, Reinecke A, Ricksten SE, Riha H, Rudiger A, Sarapohja T, Schwinger RHG, Toller W, Tritapepe L, Tschöpe C, Wikström G, von Lewinski D, Vrtovec B, Pollesello P. Levosimendan Efficacy and Safety: 20 Years of SIMDAX in Clinical Use. J Cardiovasc Pharmacol 2020; 76:4-22. [PMID: 32639325 PMCID: PMC7340234 DOI: 10.1097/fjc.0000000000000859] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 05/28/2020] [Indexed: 12/12/2022]
Abstract
Levosimendan was first approved for clinical use in 2000, when authorization was granted by Swedish regulatory authorities for the hemodynamic stabilization of patients with acutely decompensated chronic heart failure (HF). In the ensuing 20 years, this distinctive inodilator, which enhances cardiac contractility through calcium sensitization and promotes vasodilatation through the opening of adenosine triphosphate-dependent potassium channels on vascular smooth muscle cells, has been approved in more than 60 jurisdictions, including most of the countries of the European Union and Latin America. Areas of clinical application have expanded considerably and now include cardiogenic shock, takotsubo cardiomyopathy, advanced HF, right ventricular failure, pulmonary hypertension, cardiac surgery, critical care, and emergency medicine. Levosimendan is currently in active clinical evaluation in the United States. Levosimendan in IV formulation is being used as a research tool in the exploration of a wide range of cardiac and noncardiac disease states. A levosimendan oral form is at present under evaluation in the management of amyotrophic lateral sclerosis. To mark the 20 years since the advent of levosimendan in clinical use, 51 experts from 23 European countries (Austria, Belgium, Croatia, Cyprus, Czech Republic, Estonia, Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Norway, Poland, Portugal, Russia, Slovenia, Spain, Sweden, Switzerland, the United Kingdom, and Ukraine) contributed to this essay, which evaluates one of the relatively few drugs to have been successfully introduced into the acute HF arena in recent times and charts a possible development trajectory for the next 20 years.
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Affiliation(s)
- Zoltán Papp
- Department of Cardiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Piergiuseppe Agostoni
- Department of Clinical Sciences and Community Health, Centro Cardiologico Monzino, IRCCS, Milan, Italy
| | - Julian Alvarez
- Department of Surgery, School of Medicine, University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Dominique Bettex
- Institute of Anaesthesiology, University Hospital of Zurich, Zurich, Switzerland
| | - Stefan Bouchez
- Department of Anaesthesiology, University Hospital, Ghent, Belgium
| | - Dulce Brito
- Cardiology Department, Centro Hospitalar Universitario Lisboa Norte, CCUI, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Vladimir Černý
- Department of Anaesthesiology, Perioperative Medicine and Intensive Care, Masaryk Hospital, J.E. Purkinje University, Usti nad Labem, Czech Republic
| | - Josep Comin-Colet
- Heart Diseases Institute, Hospital Universitari de Bellvitge, Barcelona, Spain
| | - Marisa G. Crespo-Leiro
- Complexo Hospitalario Universitario A Coruña (CHUAC), CIBERCV, Instituto de Investigacion Biomedica A Coruña (INIBIC), Universidad de a Coruña (UDC), La Coruña, Spain
| | - Juan F. Delgado
- Heart Failure and Transplant Program, Cardiology Department, University Hospital 12 Octubre, Madrid, Spain
| | - István Édes
- Department of Cardiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Alexander A. Eremenko
- Department of Cardiac Intensive Care, Petrovskii National Research Centre of Surgery, Sechenov University, Moscow, Russia
| | - Dimitrios Farmakis
- Department of Cardiology, Medical School, University of Cyprus, Nicosia, Cyprus
| | - Francesco Fedele
- Department of Cardiovascular, Respiratory, Nephrology, Anaesthesiology and Geriatric Sciences, La Sapienza University of Rome, Rome, Italy
| | - Cândida Fonseca
- Heart Failure Clinic, São Francisco Xavier Hospital, CHLO, Lisbon, Portugal
| | - Sonja Fruhwald
- Department of Anaesthesiology and Intensive Care Medicine, Division of Anaesthesiology for Cardiovascular Surgery and Intensive Care Medicine, Medical University of Graz, Graz, Austria
| | - Massimo Girardis
- Struttura Complessa di Anestesia 1, Policlinico di Modena, Modena, Italy
| | - Fabio Guarracino
- Dipartimento di Anestesia e Terapie Intensive, Azienda Ospedaliero-Universitaria Pisana, Pisa, Italy
| | - Veli-Pekka Harjola
- Emergency Medicine, Meilahti Central University Hospital, University of Helsinki, Helsinki, Finland
| | - Matthias Heringlake
- Department of Anaesthesiology and Intensive Care Medicine, University of Lübeck, Lübeck, Germany
| | - Antoine Herpain
- Department of Intensive Care, Hôpital Erasme, Brussels, Belgium
| | - Leo M. A. Heunks
- Department of Intensive Care Medicine, Amsterdam UMC, Amsterdam, the Netherlands
| | - Tryggve Husebye
- Department of Cardiology, Oslo University Hospital Ullevaal, Oslo, Norway
| | - Višnja Ivancan
- Department of Anaesthesiology, Reanimatology and Intensive Care, University Hospital Centre, Zagreb, Croatia
| | - Kristjan Karason
- Departments of Cardiology and Transplantation, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Sundeep Kaul
- Intensive Care Unit, National Health Service, Leeds, United Kingdom
| | - Matti Kivikko
- Global Medical Affairs, R&D, Orion Pharma, Espoo, Finland
| | - Janek Kubica
- Department of Cardiology and Internal Medicine, Nicolaus Copernicus University, Torun, Poland
| | - Josep Masip
- Intensive Care Department, Consorci Sanitari Integral, University of Barcelona, Barcelona, Spain
| | | | - Alexandre Mebazaa
- Department of Anaesthesiology and Critical Care Medicine, AP-HP, Saint Louis and Lariboisière University Hospitals, Paris, France
| | | | - Fabrizio Oliva
- Department of Cardiology, Niguarda Ca'Granda Hospital, Milan, Italy
| | - Julius G. Papp
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, University of Szeged, Szeged, Hungary
| | - John Parissis
- Second Department of Cardiology, Attikon University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Alexander Parkhomenko
- Emergency Cardiology Department, National Scientific Centre MD Strazhesko Institute of Cardiology, Kiev, Ukraine
| | - Pentti Põder
- Department of Cardiology, North Estonia Medical Centre, Tallinn, Estonia
| | - Gerhard Pölzl
- Department of Internal Medicine III, Cardiology and Angiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Alexander Reinecke
- Klinik für Innere Medizin III, Kardiologie, Universitätsklinikum Schleswig-Holstein, Kiel, Germany
| | - Sven-Erik Ricksten
- Department of Anaesthesiology and Intensive Care, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Hynek Riha
- Department of Anaesthesiology and Intensive Care Medicine, Cardiothoracic Anaesthesiology and Intensive Care, Institute for Clinical and Experimental Medicine, Prague, Czech Republic
| | - Alain Rudiger
- Department of Medicine, Spittal Limmattal, Schlieren, Switzerland
| | | | - Robert H. G. Schwinger
- Medizinische Klinik II, Klinikum Weiden, Teaching Hospital of University of Regensburg, Weiden, Germany
| | - Wolfgang Toller
- Department of Anaesthesiology and Intensive Care Medicine, Medical University of Graz, Graz, Austria
| | - Luigi Tritapepe
- Anaesthesia and Intensive Care Division, San Camillo-Forlanini Hospital, Rome, Italy
| | - Carsten Tschöpe
- Department of Cardiology, Campus Virchow Klinikum, Charité—University Medicine Berlin, Berlin, Germany
| | - Gerhard Wikström
- Institute of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Dirk von Lewinski
- Department of Cardiology, Myokardiale Energetik und Metabolismus Research Unit, Medical University of Graz, Graz, Austria
| | - Bojan Vrtovec
- Department of Cardiology, Advanced Heart Failure and Transplantation Centre, University Clinical Centre, Ljubljana, Slovenia
| | - Piero Pollesello
- Critical Care Proprietary Products, Orion Pharma, Espoo, Finland.
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17
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Robertson IM, Klein BA, Sykes BD. Optimizing fluorine labelling for 19F solid-state NMR in oriented biological systems. JOURNAL OF BIOMOLECULAR NMR 2020; 74:1-7. [PMID: 31912345 DOI: 10.1007/s10858-019-00296-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 12/31/2019] [Indexed: 06/10/2023]
Abstract
When planning a fluorine labeling strategy for 19F solid state NMR (ssNMR) studies of the structure and/or mobility of fluorine labeled compounds in situ in an oriented biological system, it is important to characterize the NMR properties of the label. This manuscript focuses on the characterization of a selection of aromatic fluorine compounds in dimyristoylphosphatidylcholine bilayers using 19F ssNMR from the standpoint of determining the optimum arrangement of fluorine nuclei on a pendant aromatic ring before incorporation into more complex biological systems.
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Affiliation(s)
- Ian M Robertson
- Ministry of Health, Government of Alberta, Edmonton, AB, T5J 1S6, Canada
| | - Brittney A Klein
- Department of Biochemistry, University of Alberta, Edmonton, AB, T6G2H7, Canada
| | - Brian D Sykes
- Department of Biochemistry, University of Alberta, Edmonton, AB, T6G2H7, Canada.
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18
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Kumar S. Troponin and its applications in forensic science. JOURNAL OF FORENSIC SCIENCE AND MEDICINE 2020. [DOI: 10.4103/jfsm.jfsm_3_20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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19
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Klein BA, Robertson IM, Reiz B, Kampourakis T, Li L, Sykes BD. Thioimidate Bond Formation between Cardiac Troponin C and Nitrile-containing Compounds. ACS Med Chem Lett 2019; 10:1007-1012. [PMID: 32426091 PMCID: PMC7227049 DOI: 10.1021/acsmedchemlett.9b00168] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 05/15/2019] [Indexed: 12/16/2022] Open
Abstract
We have investigated the mechanism and reactivity of covalent bond formation between cysteine-84 of the regulatory domain of cardiac troponin C and compounds containing a nitrile moiety similar to the calcium sensitizer levosimendan. The results of modifications to the levosimendan framework ranged from a large increase in covalent bond formation to complete inactivity. We present the biological activity of one of the most potent compounds. Limitations, including compound solubility and degradation at acidic pH, have prevented thorough investigation of the potential of these compounds. Our studies reveal the efficacious nature of the malononitrile moiety in targeting cNTnC and its potential in future cardiotonic drug design.
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Affiliation(s)
- Brittney A. Klein
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Ian M. Robertson
- Ministry of Health, Government of Alberta, Edmonton, Alberta T5J 1S6, Canada
| | - Béla Reiz
- Department of Chemistry, Faculty of Science, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Thomas Kampourakis
- Randall Division of Cell and Molecular Biophysics, King’s College London, New Hunt’s House, London, SE1 1UL, U.K
| | - Liang Li
- Department of Chemistry, Faculty of Science, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Brian D. Sykes
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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20
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Marston S. Small molecule studies: the fourth wave of muscle research. J Muscle Res Cell Motil 2019; 40:69-76. [PMID: 31228047 PMCID: PMC6726831 DOI: 10.1007/s10974-019-09526-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 06/13/2019] [Indexed: 12/28/2022]
Abstract
The study of muscle and contractility is an unusual scientific endeavour since it has from the start been focussed on one problem-What makes muscle work?-and yet has needed a vast range of different approaches and techniques to study it. Its uniqueness lies in the fundamental fascination of a large scale molecular machine that converts chemical energy into mechanical energy at ambient temperature and with high efficiency that is also controlled by an exquisitely intricate yet utterly reliable regulatory system and is an essential component of animal life. The investigation of muscle is as innovative as any other field of research. As soon as one approach appears to be played out another comes along. It is instructive to consider this as a series of waves of novel and heightened activity starting in the 1950s. The thesis of this article is that we are approaching the fourth wave with the recent rise of interest in small molecules as research tools and possible therapies for muscle diseases.
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Affiliation(s)
- Steven Marston
- Cardiovascular Division, National Heart and Lung Institute, Imperial Centre for Translational and Experimental Medicine, Imperial College London, Hammersmith Campus, Du Cane Road, London, W12 0NN, UK.
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21
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Bowman JD, Coldren WH, Lindert S. Mechanism of Cardiac Troponin C Calcium Sensitivity Modulation by Small Molecules Illuminated by Umbrella Sampling Simulations. J Chem Inf Model 2019; 59:2964-2972. [PMID: 31141358 DOI: 10.1021/acs.jcim.9b00256] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cardiac troponin C (cTnC) binds intracellular calcium and subsequently cardiac troponin I (cTnI), initiating cardiac muscle contraction. Due to its role in contraction, cTnC has been a therapeutic target in the search for small molecules to treat conditions that interfere with normal muscle contraction like the heritable cardiomyopathies. Structural studies have shown the binding location of small molecules such as bepridil, dfbp-o, 3-methyldiphenylamine (DPA), and W7 to be a hydrophobic pocket in the regulatory domain of cTnC (cNTnC) but have not shown the influence of these small molecules on the energetics of opening this domain. Here we describe an application of an umbrella sampling method used to elucidate the impact these calcium sensitivity modulators have on the free energy of cNTnC hydrophobic patch opening. We found that all these molecules lowered the free energy of opening in the absence of the cTnI, with bepridil facilitating the least endergonic transformation. In the presence of cTnI, however, we saw a stabilization of the open configuration due to DPA and dfbp-o binding, and a destabilization of the open configuration imparted by bepridil and W7. Predicted poor binding molecule NSC34337 left the hydrophobic patch in under 3 ns in conventional MD simulations suggesting that only hydrophobic patch binders stabilized the open conformation. In conclusion, this study presents a novel approach to study the impact of small molecules on hydrophobic patch opening through umbrella sampling, and it proposes mechanisms for calcium sensitivity modulation.
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Affiliation(s)
- Jacob D Bowman
- Department of Chemistry and Biochemistry , Ohio State University , 2114 Newman & Wolfrom Laboratory, 100 West 18th Avenue , Columbus , Ohio 43210 , United States
| | - William H Coldren
- Department of Chemistry and Biochemistry , Ohio State University , 2114 Newman & Wolfrom Laboratory, 100 West 18th Avenue , Columbus , Ohio 43210 , United States
| | - Steffen Lindert
- Department of Chemistry and Biochemistry , Ohio State University , 2114 Newman & Wolfrom Laboratory, 100 West 18th Avenue , Columbus , Ohio 43210 , United States
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22
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Szatkowski L, Lynn ML, Holeman T, Williams MR, Baldo AP, Tardiff JC, Schwartz SD. Proof of Principle that Molecular Modeling Followed by a Biophysical Experiment Can Develop Small Molecules that Restore Function to the Cardiac Thin Filament in the Presence of Cardiomyopathic Mutations. ACS OMEGA 2019; 4:6492-6501. [PMID: 31342001 PMCID: PMC6649307 DOI: 10.1021/acsomega.8b03340] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 03/28/2019] [Indexed: 06/10/2023]
Abstract
This article reports a coupled computational experimental approach to design small molecules aimed at targeting genetic cardiomyopathies. We begin with a fully atomistic model of the cardiac thin filament. To this we dock molecules using accepted computational drug binding methodologies. The candidates are screened for their ability to repair alterations in biophysical properties caused by mutation. Hypertrophic and dilated cardiomyopathies caused by mutation are initially biophysical in nature, and the approach we take is to correct the biophysical insult prior to irreversible cardiac damage. Candidate molecules are then tested experimentally for both binding and biophysical properties. This is a proof of concept study-eventually candidate molecules will be tested in transgenic animal models of genetic (sarcomeric) cardiomyopathies.
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Affiliation(s)
- Lukasz Szatkowski
- Department
of Chemistry and Biochemistry, University
of Arizona, Tucson, Arizona 85721, United States
| | - Melissa L. Lynn
- Department of Physiological
Sciences and Department of Medicine, University of Arizona, Tucson, Arizona 85724, United States
| | - Teryn Holeman
- Department of Physiological
Sciences and Department of Medicine, University of Arizona, Tucson, Arizona 85724, United States
| | - Michael R. Williams
- Department
of Chemistry and Biochemistry, University
of Arizona, Tucson, Arizona 85721, United States
| | - Anthony P. Baldo
- Department
of Chemistry and Biochemistry, University
of Arizona, Tucson, Arizona 85721, United States
| | - Jil C. Tardiff
- Department of Physiological
Sciences and Department of Medicine, University of Arizona, Tucson, Arizona 85724, United States
| | - Steven D. Schwartz
- Department
of Chemistry and Biochemistry, University
of Arizona, Tucson, Arizona 85721, United States
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23
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Cai F, Hwang PM, Sykes BD. Structural Changes Induced by the Binding of the Calcium Desensitizer W7 to Cardiac Troponin. Biochemistry 2018; 57:6461-6469. [DOI: 10.1021/acs.biochem.8b00882] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Fangze Cai
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | - Peter M. Hwang
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
| | - Brian D. Sykes
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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24
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Sheehan A, Messer AE, Papadaki M, Choudhry A, Kren V, Biedermann D, Blagg B, Khandelwal A, Marston SB. Molecular Defects in Cardiac Myofilament Ca 2+-Regulation Due to Cardiomyopathy-Linked Mutations Can Be Reversed by Small Molecules Binding to Troponin. Front Physiol 2018; 9:243. [PMID: 29636697 PMCID: PMC5881522 DOI: 10.3389/fphys.2018.00243] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 03/06/2018] [Indexed: 12/28/2022] Open
Abstract
The inherited cardiomyopathies, hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are relatively common, potentially life-threatening and currently untreatable. Mutations are often in the contractile proteins of cardiac muscle and cause abnormal Ca2+ regulation via troponin. HCM is usually linked to higher myofilament Ca2+-sensitivity whilst in both HCM and DCM mutant tissue there is often an uncoupling of the relationship between troponin I (TnI) phosphorylation by PKA and modulation of myofilament Ca2+-sensitivity, essential for normal responses to adrenaline. The adrenergic response is blunted, and this may predispose the heart to failure under stress. At present there are no compounds or interventions that can prevent or treat sarcomere cardiomyopathies. There is a need for novel therapies that act at a more fundamental level to affect the disease process. We demonstrated that epigallocatechin-3 gallate (EGCG) was found to be capable of restoring the coupled relationship between Ca2+-sensitivity and TnI phosphorylation in mutant thin filaments to normal in vitro, independent of the mutation (15 mutations tested). We have labeled this property "re-coupling." The action of EGCG in vitro to reverse the abnormality caused by myopathic mutations would appear to be an ideal pharmaceutical profile for treatment of inherited HCM and DCM but EGCG is known to be promiscuous in vivo and is thus unsuitable as a therapeutic drug. We therefore investigated whether other structurally related compounds can re-couple myofilaments without these off-target effects. We used the quantitative in vitro motility assay to screen 40 compounds, related to C-terminal Hsp90 inhibitors, and found 23 that can re-couple mutant myofilaments. There is no correlation between re-couplers and Hsp90 inhibitors. The Ca2+-sensitivity shift due to TnI phosphorylation was restored to 2.2 ± 0.01-fold (n = 19) compared to 2.0 ± 0.24-fold (n = 7) in wild-type thin filaments. Many of these compounds were either pure re-couplers or pure desensitizers, indicating these properties are independent; moreover, re-coupling ability could be lost with small changes of compound structure, indicating the possibility of specificity. Small molecules that can re-couple may have therapeutic potential. HIGHLIGHTS - Inherited cardiomyopathies are common diseases that are currently untreatable at a fundamental level and therefore finding a small molecule treatment is highly desirable.- We have identified a molecular level dysfunction common to nearly all mutations: uncoupling of the relationship between troponin I phosphorylation and modulation of myofilament Ca2+-sensitivity, essential for normal responses to adrenaline.- We have identified a new class of drugs that are capable of both reducing Ca2+-sensitivity and/or recouping the relationship between troponin I phosphorylation and Ca2+-sensitivity.- The re-coupling phenomenon can be explained on the basis of a single mechanism that is testable.- Measurements with a wide range of small molecules of varying structures can indicate the critical molecular features required for recoupling and allows the prediction of other potential re-couplers.
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Affiliation(s)
- Alice Sheehan
- NHLI, Imperial College London, London, United Kingdom
| | | | | | | | - Vladimír Kren
- Laboratory of Biotransformation, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
| | - David Biedermann
- Laboratory of Biotransformation, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czechia
| | - Brian Blagg
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS, United States
| | - Anuj Khandelwal
- Department of Medicinal Chemistry, The University of Kansas, Lawrence, KS, United States
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25
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Klein BA, Reiz B, Robertson IM, Irving M, Li L, Sun YB, Sykes BD. Reversible Covalent Reaction of Levosimendan with Cardiac Troponin C in Vitro and in Situ. Biochemistry 2018; 57:2256-2265. [DOI: 10.1021/acs.biochem.8b00109] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Brittney A. Klein
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Béla Reiz
- Department of Chemistry, Faculty of Science, University of Alberta, Edmonton, Alberta T6H 2H7, Canada
| | - Ian M. Robertson
- Pharmaceutical and Health Benefits Branch, Ministry of Health, Government of Alberta, Edmonton, Alberta T5J 3Z5, Canada
| | - Malcolm Irving
- Randall Centre for Cell and Molecular Biophysics and British Heart Foundation Centre of Research Excellence, King’s College London, London SE1 1UL, U.K
| | - Liang Li
- Department of Chemistry, Faculty of Science, University of Alberta, Edmonton, Alberta T6H 2H7, Canada
| | - Yin-Biao Sun
- Randall Centre for Cell and Molecular Biophysics and British Heart Foundation Centre of Research Excellence, King’s College London, London SE1 1UL, U.K
| | - Brian D. Sykes
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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26
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Xue K, Gu JJ, Zhang Q, Liu X, Wang J, Li XQ, Luo J, Hernandez-Ilizaliturri FJ, Fernandez SF, Czuczman MS, Cao J, Hong X, Guo Y. Cardiotoxicity as indicated by LVEF and troponin T sensitivity following two anthracycline-based regimens in lymphoma: Results from a randomized prospective clinical trial. Oncotarget 2018; 7:32519-31. [PMID: 27081036 PMCID: PMC5078030 DOI: 10.18632/oncotarget.8685] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 03/28/2016] [Indexed: 12/02/2022] Open
Abstract
Anthracycline-induced cardiotoxicity influences treatment selection and may negatively affect clinical outcomes in lymphoma patients. While epirubicin induced cardiotoxicity less often than the same dose of doxorubicin in breast cancer, higher doses of epirubicin are required in lymphoma regimens for equivalent efficacy. Whether a higher dosage of epirubicin also induces cardiotoxicity less often than doxorubicin in lymphoma remains unknown. We therefore administered 6-8 cycles of cyclophosphamide, vincristine and prednisone (CEpOP) +/− rituximab (R) with either epirubicin (CEpOP) or doxorubicin (CHOP) to patients (N=398) with untreated diffuse large B-cell lymphoma (DLBCL) or follicular lymphoma grade 3 (FLG3). Left ventricular ejection fraction (LVEF) and high-sensitivity serum cardiac troponin T (HsTnT) were assessed at baseline and after 4 cycles of treatment. Epirubicin (70 mg/m2/dose) was equivalent to doxorubicin (50 mg/m2/dose) in terms of 3-year progression-free survival. The risk of decreased LVEF was similar between the two regimens. CEpOP+/−R induced HsTnT elevation less often than CHOP+/−R. We conclude that CEpOP+/−R is a more acceptable regimen with short-term efficacy similar to CHOP+/−R in lymphoma patients. Longer follow-up is needed to monitor the risk of cardiac dysfunction and determine whether differences in the induction of elevated HsTnT between epirubicin and doxorubicin justify changes in clinical practice.
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Affiliation(s)
- Kai Xue
- Department of Medical Oncology, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Juan J Gu
- Department of Medicine & Immunology, Roswell Park Cancer Institute, Buffalo, NY, USA
| | - Qunling Zhang
- Department of Medical Oncology, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Xiaojian Liu
- Department of Medical Oncology, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Jiachen Wang
- Department of Medical Oncology, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Xiao-Qiu Li
- Department of Pathology, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Jianfeng Luo
- Department of Biostatistics, School of Public Health, Fudan University, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | | | - Stanley F Fernandez
- Department of Medicine, University at Buffalo, The State University of New York, Buffalo, NY, USA
| | - Myron S Czuczman
- Department of Medicine & Immunology, Roswell Park Cancer Institute, Buffalo, NY, USA
| | - Junning Cao
- Department of Medical Oncology, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Xiaonan Hong
- Department of Medical Oncology, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Ye Guo
- Department of Medical Oncology, Fudan University Shanghai Cancer Center, Shanghai, China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
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27
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Xu D, Gao Y, Guo L, Lin C, Sun Y. Effect of dys-1 mutation on gene expression profile in space-flown Caenorhabditis elegans. Muscle Nerve 2018; 58:114-122. [PMID: 29346705 DOI: 10.1002/mus.26076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/16/2018] [Indexed: 11/09/2022]
Abstract
INTRODUCTION Dystrophin-like dys-1 gene expression increases in the body wall muscles of Caenorhabditis elegans after spaceflight (SF). Here we used a dys-1(cx18) mutant to analyze the molecular adaptive responses of C. elegans to SF. METHODS DNA microarrays were performed to identify differentially expressed genes between wild-type (WT) and dys-1 mutant worms after SF. We performed Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses, predicted human diseases, and screened out key genes for human muscle diseases with NextBio. RESULTS Gene expression was less affected by SF in the dys-1 mutant than in the WT worms. The dys-1 mutation influenced neuromuscular gene expression (neuropeptide genes, muscle-related genes, and dystrophin-related genes) under SF conditions, among which 15 genes were specifically regulated by dys-1. NextBio analysis predicted that cdka-1, lev-11, unc-27, and unc-94 genes might play critical roles in muscle atrophy. DISCUSSION dys-1 Potentially regulates the neuromuscular system in space. Muscle Nerve, 2018.
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Affiliation(s)
- Dan Xu
- Institute of Environmental Systems Biology, Dalian Maritime University, Linghai Road 1 Dalian, 116026, People's Republic of China
| | - Ying Gao
- Institute of Environmental Systems Biology, Dalian Maritime University, Linghai Road 1 Dalian, 116026, People's Republic of China
- Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, People's Republic of China
| | - Lin Guo
- Institute of Environmental Systems Biology, Dalian Maritime University, Linghai Road 1 Dalian, 116026, People's Republic of China
| | - Chenggang Lin
- Institute of Environmental Systems Biology, Dalian Maritime University, Linghai Road 1 Dalian, 116026, People's Republic of China
| | - Yeqing Sun
- Institute of Environmental Systems Biology, Dalian Maritime University, Linghai Road 1 Dalian, 116026, People's Republic of China
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28
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The Evaluation of the Ameliorative Effect of Montelukast Against Arsenic Trioxide-Induced Cardiotoxicity in Rats. Jundishapur J Nat Pharm Prod 2017. [DOI: 10.5812/jjnpp.65046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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29
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Aprahamian ML, Tikunova SB, Price MV, Cuesta AF, Davis JP, Lindert S. Successful Identification of Cardiac Troponin Calcium Sensitizers Using a Combination of Virtual Screening and ROC Analysis of Known Troponin C Binders. J Chem Inf Model 2017; 57:3056-3069. [PMID: 29144742 DOI: 10.1021/acs.jcim.7b00536] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Calcium-dependent cardiac muscle contraction is regulated by the protein complex troponin. Calcium binds to the N-terminal domain of troponin C (cNTnC) which initiates the process of contraction. Heart failure is a consequence of a disruption of this process. With the prevalence of this condition, a strong need exists to find novel compounds to increase the calcium sensitivity of cNTnC. Desirable are small chemical molecules that bind to the interface between cTnC and the cTnI switch peptide and exhibit calcium sensitizing properties by possibly stabilizing cTnC in an open conformation. To identify novel drug candidates, we employed a structure-based drug discovery protocol that incorporated the use of a relaxed complex scheme (RCS). In preparation for the virtual screening, cNTnC conformations were identified based on their ability to correctly predict known cNTnC binders using a receiver operating characteristics analysis. Following a virtual screen of the National Cancer Institute's Developmental Therapeutic Program database, a small number of molecules were experimentally tested using stopped-flow kinetics and steady-state fluorescence titrations. We identified two novel compounds, 3-(4-methoxyphenyl)-6,7-chromanediol (NSC600285) and 3-(4-methylphenyl)-7,8-chromanediol (NSC611817), that show increased calcium sensitivity of cTnC in the presence of the regulatory domain of cTnI. The effects of NSC600285 and NSC611817 on the calcium dissociation rate was stronger than that of the known calcium sensitizer bepridil. Thus, we identified a 3-phenylchromane group as a possible key pharmacophore in the sensitization of cardiac muscle contraction. Building on this finding is of interest to researchers working on development of drugs for calcium sensitization.
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Affiliation(s)
- Melanie L Aprahamian
- Department of Chemistry and Biochemistry, Ohio State University , Columbus, Ohio 43210, United States
| | - Svetlana B Tikunova
- Davis Heart and Lung Research Institute and Department of Physiology and Cell Biology, Ohio State University , Columbus, Ohio 43210, United States
| | - Morgan V Price
- Davis Heart and Lung Research Institute and Department of Physiology and Cell Biology, Ohio State University , Columbus, Ohio 43210, United States
| | - Andres F Cuesta
- Davis Heart and Lung Research Institute and Department of Physiology and Cell Biology, Ohio State University , Columbus, Ohio 43210, United States
| | - Jonathan P Davis
- Davis Heart and Lung Research Institute and Department of Physiology and Cell Biology, Ohio State University , Columbus, Ohio 43210, United States
| | - Steffen Lindert
- Department of Chemistry and Biochemistry, Ohio State University , Columbus, Ohio 43210, United States
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30
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García-Canales A, Peña-Juárez RA, Sandoval-Franco LDM. [Vasopressors and inotropes: use in paediatrics]. ARCHIVOS DE CARDIOLOGIA DE MEXICO 2017; 88:39-50. [PMID: 28336302 DOI: 10.1016/j.acmx.2017.02.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 02/14/2017] [Accepted: 02/15/2017] [Indexed: 11/16/2022] Open
Abstract
The cardiovascular system is a dynamic system, which is required to ensure adequate delivery of oxygen, nutrients, and hormones to the tissues that are necessary for cell metabolism. It also synthesises and modifies the vasoactive components that regulate vascular tone and myocardial function. These vasoactive components have demonstrated their beneficial effects in the management of paediatric patients in a critical condition with heart failure and shock. However, their use and abuse brings harmful effects, increases mortality, and is associated with arrhythmias. An increase in myocardial oxygen consumption favours the presence of ischaemia, therefore it is necessary to know the mechanism of action and indications of these drugs to minimise their harmful effects. The purpose of this review is to describe the pharmacology and clinical applications of inotropic and vasopressor agents in the paediatric patient in acritical condition.
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Affiliation(s)
- Adrián García-Canales
- Departamento de Terapia Intensiva Pediátrica, Hospital Regional Valentín Gómez Farías, ISSSTE, Zapopan, Jalisco, México.
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31
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Robertson IM, Pineda-Sanabria SE, Yan Z, Kampourakis T, Sun YB, Sykes BD, Irving M. Reversible Covalent Binding to Cardiac Troponin C by the Ca2+-Sensitizer Levosimendan. Biochemistry 2016; 55:6032-6045. [DOI: 10.1021/acs.biochem.6b00758] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ian M. Robertson
- Randall
Division of Cell and Molecular Biophysics and British Heart Foundation
Centre of Research Excellence, King’s College London, New Hunt’s
House, Guy’s Campus, London, SE1 1UL, U.K
- Department
of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Sandra E. Pineda-Sanabria
- Department
of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Ziqian Yan
- Randall
Division of Cell and Molecular Biophysics and British Heart Foundation
Centre of Research Excellence, King’s College London, New Hunt’s
House, Guy’s Campus, London, SE1 1UL, U.K
| | - Thomas Kampourakis
- Randall
Division of Cell and Molecular Biophysics and British Heart Foundation
Centre of Research Excellence, King’s College London, New Hunt’s
House, Guy’s Campus, London, SE1 1UL, U.K
| | - Yin-Biao Sun
- Randall
Division of Cell and Molecular Biophysics and British Heart Foundation
Centre of Research Excellence, King’s College London, New Hunt’s
House, Guy’s Campus, London, SE1 1UL, U.K
| | - Brian D. Sykes
- Department
of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Malcolm Irving
- Randall
Division of Cell and Molecular Biophysics and British Heart Foundation
Centre of Research Excellence, King’s College London, New Hunt’s
House, Guy’s Campus, London, SE1 1UL, U.K
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32
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Dewan S, McCabe KJ, Regnier M, McCulloch AD, Lindert S. Molecular Effects of cTnC DCM Mutations on Calcium Sensitivity and Myofilament Activation-An Integrated Multiscale Modeling Study. J Phys Chem B 2016; 120:8264-75. [PMID: 27133568 PMCID: PMC5001916 DOI: 10.1021/acs.jpcb.6b01950] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mutations in cardiac troponin C (D75Y, E59D, and G159D), a key regulatory protein of myofilament contraction, have been associated with dilated cardiomyopathy (DCM). Despite reports of altered myofilament function in these mutants, the underlying molecular alterations caused by these mutations remain elusive. Here we investigate in silico the intramolecular mechanisms by which these mutations affect myofilament contraction. On the basis of the location of cardiac troponin C (cTnC) mutations, we tested the hypothesis that intramolecular effects can explain the altered myofilament calcium sensitivity of force development for D75Y and E59D cTnC, whereas altered cardiac troponin C-troponin I (cTnC-cTnI) interaction contributes to the reported contractile effects of the G159D mutation. We employed a multiscale approach combining molecular dynamics (MD) and Brownian dynamics (BD) simulations to estimate cTnC calcium association and hydrophobic patch opening. We then integrated these parameters into a Markov model of myofilament activation to compute the steady-state force-pCa relationship. The analysis showed that myofilament calcium sensitivity with D75Y and E59D can be explained by changes in calcium binding affinity of cTnC and the rate of hydrophobic patch opening, if a partial cTnC interhelical opening angle (110°) is sufficient for cTnI switch peptide association to cTnC. In contrast, interactions between cTnC and cTnI within the cardiac troponin complex must also be accounted for to explain contractile alterations due to G159D. In conclusion, this is the first multiscale in silico study to elucidate how direct molecular effects of genetic mutations in cTnC translate to altered myofilament contractile function.
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Affiliation(s)
- Sukriti Dewan
- Department of Bioengineering, University of California at San Diego, La Jolla, CA, 92093
| | - Kimberly J. McCabe
- Department of Bioengineering, University of California at San Diego, La Jolla, CA, 92093
| | - Michael Regnier
- Dept. of Bioengineering, University of Washington, Seattle, WA 98195
- Center for Cardiovascular Biology, University of Washington, Seattle, WA 98109
| | - Andrew D. McCulloch
- Department of Bioengineering, University of California at San Diego, La Jolla, CA, 92093
| | - Steffen Lindert
- Department of Chemistry & Biochemistry, Ohio State University, Columbus, OH, 43210
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33
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Thompson BR, Martindale J, Metzger JM. Sarcomere neutralization in inherited cardiomyopathy: small-molecule proof-of-concept to correct hyper-Ca2+-sensitive myofilaments. Am J Physiol Heart Circ Physiol 2016; 311:H36-43. [PMID: 27199134 DOI: 10.1152/ajpheart.00981.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 05/05/2016] [Indexed: 11/22/2022]
Abstract
The sarcomere is the functional unit of the heart. Alterations in sarcomere activation lead to disease states such as hypertrophic and restrictive cardiomyopathy (HCM/RCM). Mutations in many of the sarcomeric genes are causal for HCM/RCM. In most cases, these mutations result in increased Ca(2+) sensitivity of the sarcomere, giving rise to altered systolic and diastolic function. There is emerging evidence that small-molecule sarcomere neutralization is a potential therapeutic strategy for HCM/RCM. To pursue proof-of-concept, W7 was used here because of its well-known Ca(2+) desensitizer biochemical effects at the level of cardiac troponin C. Acute treatment of adult cardiac myocytes with W7 caused a dose-dependent (1-10 μM) decrease in contractility in a Ca(2+)-independent manner. Alkalosis was used as an in vitro experimental model of acquired heightened Ca(2+) sensitivity, resulting in increased live cell contractility and decreased baseline sarcomere length, which were rapidly corrected with W7. As an inherited cardiomyopathy model, R193H cardiac troponin I (cTnI) transgenic myocytes showed significant decreased baseline sarcomere length and slowed relaxation that were rapidly and dose-dependently corrected by W7. Langendorff whole heart pacing stress showed that R193H cTnI transgenic hearts had elevated end-diastolic pressures at all pacing frequencies compared with hearts from nontransgenic mice. Acute treatment with W7 rapidly restored end-diastolic pressures to normal values in R193H cTnI hearts, supporting a sarcomere intrinsic mechanism of dysfunction. The known off-target effects of W7 notwithstanding, these results provide further proof-of-concept that small-molecule-based sarcomere neutralization is a potential approach to remediate hyper-Ca(2+)-sensitive sarcomere function.
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Affiliation(s)
- Brian R Thompson
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Joshua Martindale
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Joseph M Metzger
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, Minnesota
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Nagy L, Pollesello P, Haikala H, Végh Á, Sorsa T, Levijoki J, Szilágyi S, Édes I, Tóth A, Papp Z, Papp JG. ORM-3819 promotes cardiac contractility through Ca(2+) sensitization in combination with selective PDE III inhibition, a novel approach to inotropy. Eur J Pharmacol 2016; 775:120-9. [PMID: 26872993 DOI: 10.1016/j.ejphar.2016.02.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 02/05/2016] [Accepted: 02/08/2016] [Indexed: 11/29/2022]
Abstract
This study is the first pharmacological characterization of the novel chemical entity, ORM-3819 (L-6-{4-[N'-(4-Hydroxi-3-methoxy-2-nitro-benzylidene)-hydrazino]-phenyl}-5-methyl-4,5-dihydro-2H-pyridazin-3-one), focusing primarily on its cardiotonic effects. ORM-3819 binding to cardiac troponin C (cTnC) was confirmed by nuclear magnetic resonance spectroscopy, and a selective inhibition of the phosphodiesterase III (PDE III) isozyme (IC50=3.88±0.3 nM) was revealed during in vitro enzyme assays. The Ca(2+)-sensitizing effect of ORM-3819 was demonstrated in vitro in permeabilized myocyte-sized preparations from left ventricles (LV) of guinea pig hearts (ΔpCa50=0.12±0.01; EC50=2.88±0.14 µM). ORM-3819 increased the maximal rate of LV pressure development (+dP/dtmax) (EC50=8.9±1.7 nM) and LV systolic pressure (EC50=7.63±1.74 nM) in Langendorff-perfused guinea pig hearts. Intravenous administration of ORM-3819 increased LV+dP/dtmax (EC50=0.13±0.05 µM/kg) and improved the rate of LV pressure decrease (-dP/dtmax); (EC50=0.03±0.02 µM/kg) in healthy guinea pigs. In an in vivo dog model of myocardial stunning, ORM-3819 restored the depressed LV+dP/dtmax and improved % segmental shortening (%SS) in the ischemic area (to 18.8±3), which was reduced after the ischaemia-reperfusion insult (from 24.1±2.1 to 11.0±2.4). Our data demonstrate ORM-3819 as a potent positive inotropic agent exerting its cardiotonic effect by a cTnC-dependent Ca(2+)-sensitizing mechanism in combination with the selective inhibition of the PDE III isozyme. This dual mechanism of action results in the concentration-dependent augmentation of the contractile performance under control conditions and in the postischemic failing myocardium.
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Affiliation(s)
- László Nagy
- Division of Clinical Physiology, Institute of Cardiology, Research Centre for Molecular Medicine, Faculty of Medicine, University of Debrecen, Hungary Móricz Zs. krt. 22 Hungary, 4032 Debrecen, Hungary
| | | | - Heimo Haikala
- Orion Pharma, Drug Discovery and Pharmacology, Espoo, Finland
| | - Ágnes Végh
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Tia Sorsa
- Orion Pharma, Drug Discovery and Pharmacology, Espoo, Finland
| | - Jouko Levijoki
- Orion Pharma, Drug Discovery and Pharmacology, Espoo, Finland
| | - Szabolcs Szilágyi
- Division of Clinical Physiology, Institute of Cardiology, Research Centre for Molecular Medicine, Faculty of Medicine, University of Debrecen, Hungary Móricz Zs. krt. 22 Hungary, 4032 Debrecen, Hungary
| | - István Édes
- Division of Clinical Physiology, Institute of Cardiology, Research Centre for Molecular Medicine, Faculty of Medicine, University of Debrecen, Hungary Móricz Zs. krt. 22 Hungary, 4032 Debrecen, Hungary
| | - Attila Tóth
- Division of Clinical Physiology, Institute of Cardiology, Research Centre for Molecular Medicine, Faculty of Medicine, University of Debrecen, Hungary Móricz Zs. krt. 22 Hungary, 4032 Debrecen, Hungary
| | - Zoltán Papp
- Division of Clinical Physiology, Institute of Cardiology, Research Centre for Molecular Medicine, Faculty of Medicine, University of Debrecen, Hungary Móricz Zs. krt. 22 Hungary, 4032 Debrecen, Hungary.
| | - Julius Gy Papp
- MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
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Pineda-Sanabria SE, Robertson IM, Sun YB, Irving M, Sykes BD. Probing the mechanism of cardiovascular drugs using a covalent levosimendan analog. J Mol Cell Cardiol 2016; 92:174-84. [PMID: 26853943 PMCID: PMC4831045 DOI: 10.1016/j.yjmcc.2016.02.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 01/24/2016] [Accepted: 02/02/2016] [Indexed: 01/16/2023]
Abstract
One approach to improve contraction in the failing heart is the administration of calcium (Ca2 +) sensitizers. Although it is known that levosimendan and other sensitizers bind to troponin C (cTnC), their in vivo mechanism is not fully understood. Based on levosimendan, we designed a covalent Ca2 + sensitizer (i9) that targets C84 of cTnC and exchanged this complex into cardiac muscle. The NMR structure of the covalent complex showed that i9 binds deep in the hydrophobic pocket of cTnC. Despite slightly reducing troponin I affinity, i9 enhanced the Ca2 + sensitivity of cardiac muscle. We conclude that i9 enhances Ca2 + sensitivity by stabilizing the open conformation of cTnC. These findings provide new insights into the in vivo mechanism of Ca2 + sensitization and demonstrate that directly targeting cTnC has significant potential in cardiovascular therapy. A Ca2 + sensitizer, i9 was designed that forms a covalent bond with C84 of cTnC. i9 stabilized the open state of the N-domain of cTnC. The structure of the covalent cTnC-cTnI-i9 complex was solved by NMR. The structure showed that i9 binds deep in the hydrophobic pocket of cTnC. Despite slightly reducing cTnI affinity, i9 enhanced the Ca2 + sensitivity of cardiac muscle.
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Affiliation(s)
- Sandra E Pineda-Sanabria
- Department of Biochemistry, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Ian M Robertson
- Randall Division of Cell and Molecular Biophysics and British Heart Foundation Centre of Research Excellence, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Yin-Biao Sun
- Randall Division of Cell and Molecular Biophysics and British Heart Foundation Centre of Research Excellence, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Malcolm Irving
- Randall Division of Cell and Molecular Biophysics and British Heart Foundation Centre of Research Excellence, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Brian D Sykes
- Department of Biochemistry, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
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Schlecht W, Li KL, Hu D, Dong W. Fluorescence Based Characterization of Calcium Sensitizer Action on the Troponin Complex. Chem Biol Drug Des 2015; 87:171-81. [PMID: 26375298 DOI: 10.1111/cbdd.12651] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 07/15/2015] [Accepted: 08/05/2015] [Indexed: 11/29/2022]
Abstract
Calcium sensitizers enhance the transduction of the Ca(2+) signal into force within the heart and have found use in treating heart failure. However the mechanisms of action for most Ca(2+) sensitizers remain unclear. To address this issue an efficient fluorescence based approach to Ca(2+) sensitizer screening was developed which monitors cardiac troponin C's (cTnC's) hydrophobic cleft. This approach was tested on four common Ca(2+) -sensitizers, EMD 57033, levosimendan, bepridil and pimobendan with the aim of elucidating the mechanisms of action for each as well as proving the efficacy of the new screening method. Ca(2+) -titration experiments were employed to determine the effect on Ca(2+) sensitivity and cooperativity of cTnC opening, while stopped flow experiments were used to investigate the impact on cTnC relaxation kinetics. Bepridil was shown to increase the sensitivity of cTnC for Ca(2+) under all reconstitution conditions, sensitization by the other drugs was context dependent. Levosimendan and pimobendan reduced the rate of cTnC closing consistent with a stabilization of cTnC's open conformation while bepridil increased the rate of relaxation. Experiments were also run on samples containing cTnT(T204E), a known Ca(2+) -desensitizing phosphorylation mimic. Levosimendan, bepridil, and pimobendan were found to elevate the Ca(2+) -sensitivity of cTnT(T204E) containing samples in this context.
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Affiliation(s)
- William Schlecht
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, PO Box 646515, Washington State University, Pullman, WA 99164-6515, USA
| | - King-Lun Li
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, PO Box 646515, Washington State University, Pullman, WA 99164-6515, USA
| | - Dehong Hu
- The Environmental and Molecular Science Laboratory, Pacific Northwest National Laboratory, 3335 Innovation Boulevard Richland, WA 99354, USA
| | - Wenji Dong
- The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, PO Box 646515, Washington State University, Pullman, WA 99164-6515, USA
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In situ time-resolved FRET reveals effects of sarcomere length on cardiac thin-filament activation. Biophys J 2015; 107:682-693. [PMID: 25099807 DOI: 10.1016/j.bpj.2014.05.044] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 05/10/2014] [Accepted: 05/13/2014] [Indexed: 02/07/2023] Open
Abstract
During cardiac thin-filament activation, the N-domain of cardiac troponin C (N-cTnC) binds to Ca(2+) and interacts with the actomyosin inhibitory troponin I (cTnI). The interaction between N-cTnC and cTnI stabilizes the Ca(2+)-induced opening of N-cTnC and is presumed to also destabilize cTnI-actin interactions that work together with steric effects of tropomyosin to inhibit force generation. Recently, our in situ steady-state FRET measurements based on N-cTnC opening suggested that at long sarcomere length, strongly bound cross-bridges indirectly stabilize this Ca(2+)-sensitizing N-cTnC-cTnI interaction through structural effects on tropomyosin and cTnI. However, the method previously used was unable to determine whether N-cTnC opening depends on sarcomere length. In this study, we used time-resolved FRET to monitor the effects of cross-bridge state and sarcomere length on the Ca(2+)-dependent conformational behavior of N-cTnC in skinned cardiac muscle fibers. FRET donor (AEDANS) and acceptor (DDPM)-labeled double-cysteine mutant cTnC(T13C/N51C)AEDANS-DDPM was incorporated into skinned muscle fibers to monitor N-cTnC opening. To study the structural effects of sarcomere length on N-cTnC, we monitored N-cTnC opening at relaxing and saturating levels of Ca(2+) and 1.80 and 2.2-μm sarcomere length. Mg(2+)-ADP and orthovanadate were used to examine the structural effects of noncycling strong-binding and weak-binding cross-bridges, respectively. We found that the stabilizing effect of strongly bound cross-bridges on N-cTnC opening (which we interpret as transmitted through related changes in cTnI and tropomyosin) become diminished by decreases in sarcomere length. Additionally, orthovanadate blunted the effect of sarcomere length on N-cTnC conformational behavior such that weak-binding cross-bridges had no effect on N-cTnC opening at any tested [Ca(2+)] or sarcomere length. Based on our findings, we conclude that the observed sarcomere length-dependent positive feedback regulation is a key determinant in the length-dependent Ca(2+) sensitivity of myofilament activation and consequently the mechanism underlying the Frank-Starling law of the heart.
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Li MX, Hwang PM. Structure and function of cardiac troponin C (TNNC1): Implications for heart failure, cardiomyopathies, and troponin modulating drugs. Gene 2015; 571:153-66. [PMID: 26232335 DOI: 10.1016/j.gene.2015.07.074] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 06/24/2015] [Accepted: 07/21/2015] [Indexed: 10/23/2022]
Abstract
In striated muscle, the protein troponin complex turns contraction on and off in a calcium-dependent manner. The calcium-sensing component of the complex is troponin C, which is expressed from the TNNC1 gene in both cardiac muscle and slow-twitch skeletal muscle (identical transcript in both tissues) and the TNNC2 gene in fast-twitch skeletal muscle. Cardiac troponin C (cTnC) is made up of two globular EF-hand domains connected by a flexible linker. The structural C-domain (cCTnC) contains two high affinity calcium-binding sites that are always occupied by Ca(2+) or Mg(2+) under physiologic conditions, stabilizing an open conformation that remains anchored to the rest of the troponin complex. In contrast, the regulatory N-domain (cNTnC) contains a single low affinity site that is largely unoccupied at resting calcium concentrations. During muscle activation, calcium binding to cNTnC favors an open conformation that binds to the switch region of troponin I, removing adjacent inhibitory regions of troponin I from actin and allowing muscle contraction to proceed. Regulation of the calcium binding affinity of cNTnC is physiologically important, because it directly impacts the calcium sensitivity of muscle contraction. Calcium sensitivity can be modified by drugs that stabilize the open form of cNTnC, post-translational modifications like phosphorylation of troponin I, or downstream thin filament protein interactions that impact the availability of the troponin I switch region. Recently, mutations in cTnC have been associated with hypertrophic or dilated cardiomyopathy. A detailed understanding of how calcium sensitivity is regulated through the troponin complex is necessary for explaining how mutations perturb its function to promote cardiomyopathy and how post-translational modifications in the thin filament affect heart function and heart failure. Troponin modulating drugs are being developed for the treatment of cardiomyopathies and heart failure.
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Affiliation(s)
- Monica X Li
- Department of Medicine, University of Alberta, Edmonton, AB T6G 2G3, Canada; Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Peter M Hwang
- Department of Medicine, University of Alberta, Edmonton, AB T6G 2G3, Canada; Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
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Abstract
Acute heart failure (AHF) emerges as a major and growing epidemiological concern with high morbidity and mortality rates. Current therapies in patients with acute heart failure rely on different strategies. Patients with hypotension, hypoperfusion, or shock require inotropic support, whereas diuretics and vasodilators are recommended in patients with systemic or pulmonary congestion. Traditionally inotropic agents, referred to as Ca2+ mobilizers load the cardiomyocyte with Ca2+ and thereby increase oxygen consumption and risk for arrhythmias. These limitations of traditional inotropes may be avoided by sarcomere targeted agents. Direct activation of the cardiac sarcomere may be achieved by either sensitizing the cardiac myofilaments to Ca2+ or activating directly the cardiac myosin. In this review, we focus on sarcomere targeted inotropic agents, emphasizing their mechanisms of action and overview the most relevant clinical considerations.
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Abstract
Various human diseases can disrupt the balance between muscle contraction and relaxation. Sarcomeric modulators can be used to readjust this balance either indirectly by intervening in signalling pathways or directly through interaction with the muscle proteins that control contraction. Such agents represent a novel approach to treating any condition in which striated muscle function is compromised, including heart failure, cardiomyopathies, skeletal myopathies and a wide range of neuromuscular conditions. Here, we review agents that modulate the mechanical function of the sarcomere, focusing on emerging compounds that target myosin or the troponin complex.
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Thompson BR, Houang EM, Sham YY, Metzger JM. Molecular determinants of cardiac myocyte performance as conferred by isoform-specific TnI residues. Biophys J 2014; 106:2105-14. [PMID: 24853739 DOI: 10.1016/j.bpj.2014.04.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 03/14/2014] [Accepted: 04/04/2014] [Indexed: 11/27/2022] Open
Abstract
Troponin I (TnI) is the molecular switch of the sarcomere. Cardiac myocytes express two isoforms of TnI during development. The fetal heart expresses the slow skeletal TnI (ssTnI) isoform and shortly after birth ssTnI is completely and irreversibly replaced by the adult cardiac TnI (cTnI) isoform. These two isoforms have important functional differences; broadly, ssTnI is a positive inotrope, especially under acidic/hypoxic conditions, whereas cTnI facilitates faster relaxation performance. Evolutionary directed changes in cTnI sequence suggest cTnI evolved to favor relaxation performance in the mammalian heart. To investigate the mechanism, we focused on several notable TnI isoform and trans-species-specific residues located in TnI's helix 4 using structure/function and molecular dynamics analyses. Gene transduction of adult cardiac myocytes by cTnIs with specific helix 4 ssTnI substitutions, Q157R/A164H/E166V/H173N (QAEH), and A164H/H173N (AH), were investigated. cTnI QAEH is similar in these four residues to ssTnI and nonmammalian chordate cTnIs, whereas cTnI AH is similar to fish cTnI in these four residues. In comparison to mammalian cTnI, cTnI QAEH and cTnI AH showed increased contractility and slowed relaxation, which functionally mimicked ssTnI expressing myocytes. cTnI QAEH molecular dynamics simulations demonstrated altered intermolecular interactions between TnI helix 4 and cTnC helix A, specifically revealing a new, to our knowledge, electrostatic interaction between R171of cTnI and E15 of cTnC, which structurally phenocopied the ssTnI conformation. Free energy perturbation calculation of cTnC Ca(2+) binding for these conformations showed relative increased calcium binding for cTnI QAEH compared to cTnI. Taken together, to our knowledge, these new findings provide evidence that the evolutionary-directed coordinated acquisition of residues Q157, A164, E166, H173 facilitate enhanced relaxation performance in mammalian adult cardiac myocytes.
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Affiliation(s)
- Brian R Thompson
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Evelyne M Houang
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, Minnesota; Center for Drug Design, University of Minnesota Academic Health Center, Minneapolis, Minnesota
| | - Yuk Y Sham
- Center for Drug Design, University of Minnesota Academic Health Center, Minneapolis, Minnesota
| | - Joseph M Metzger
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, Minnesota.
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Pineda-Sanabria SE, Julien O, Sykes BD. Versatile cardiac troponin chimera for muscle protein structural biology and drug discovery. ACS Chem Biol 2014; 9:2121-30. [PMID: 25010113 DOI: 10.1021/cb500249j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Investigation of the molecular interactions within and between subunits of the heterotrimeric troponin complex, and with other proteins in the sarcomere, has revealed salient structural elements involved in regulation of muscle contraction. The discovery of new cardiotonic drugs and structural studies utilizing intact troponin, or regulatory complexes formed between the key regions identified in troponin C and troponin I, face intrinsic and technical difficulties associated with weak protein-protein interactions and with solubility, aggregation, stability of the overall architecture, isotope labeling, and size, respectively. We have designed and characterized a chimeric troponin C-troponin I hybrid protein with a cleavable linker that is useful for producing isotopically labeled troponin peptides, stabilizes their interaction, and has proven to be a faithful representation of the original complex in the systolic state, but lacking its disadvantages, making it particularly suitable for drug screening and structural studies.
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Affiliation(s)
- Sandra E. Pineda-Sanabria
- Department of Biochemistry, University of Alberta, 4-19 Medical
Sciences Building, Edmonton, Alberta Canada, T6G 2H7
| | - Olivier Julien
- Department of Biochemistry, University of Alberta, 4-19 Medical
Sciences Building, Edmonton, Alberta Canada, T6G 2H7
| | - Brian D. Sykes
- Department of Biochemistry, University of Alberta, 4-19 Medical
Sciences Building, Edmonton, Alberta Canada, T6G 2H7
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Lindert S, Li MX, Sykes BD, McCammon JA. Computer-aided drug discovery approach finds calcium sensitizer of cardiac troponin. Chem Biol Drug Des 2014; 85:99-106. [PMID: 24954187 DOI: 10.1111/cbdd.12381] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 05/27/2014] [Accepted: 06/04/2014] [Indexed: 11/28/2022]
Abstract
In the fight against heart failure, therapeutics that have the ability to increase the contractile power of the heart are urgently needed. One possible route of action to improve heart contractile power is increasing the calcium sensitivity of the thin filament. From a pharmaceutical standpoint, calcium sensitizers have the distinct advantage of not altering cardiomyocyte calcium levels and thus have lower potential for side-effects. Small chemical molecules have been shown to bind to the interface between cTnC and the cTnI switch peptide and exhibit calcium-sensitizing properties, possibly by stabilizing cTnC in an open conformation. Building on existing structural data of a known calcium sensitizer bound to cardiac troponin, we combined computational structure-based virtual screening drug discovery methods and solution NMR titration assays to identify a novel calcium sensitizer 4-(4-(2,5-dimethylphenyl)-1-piperazinyl)-3-pyridinamine (NSC147866) which binds to cTnC and the cTnC-cTnI147-163 complex. Its presence increases the affinity of switch peptide to cTnC by approximately a factor of two. This action is comparable to that of known levosimendan analogues.
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Affiliation(s)
- Steffen Lindert
- Department of Pharmacology, University of California San Diego, La Jolla, CA, 92093, USA; NSF Center for Theoretical Biological Physics, La Jolla, CA, 92093, USA
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Robertson IM, Pineda-Sanabria SE, Holmes PC, Sykes BD. Conformation of the critical pH sensitive region of troponin depends upon a single residue in troponin I. Arch Biochem Biophys 2014; 552-553:40-9. [DOI: 10.1016/j.abb.2013.12.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2013] [Revised: 11/18/2013] [Accepted: 12/05/2013] [Indexed: 12/20/2022]
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Pathak A, Lebrin M, Vaccaro A, Senard JM, Despas F. Pharmacology of levosimendan: inotropic, vasodilatory and cardioprotective effects. J Clin Pharm Ther 2013; 38:341-9. [PMID: 23594161 DOI: 10.1111/jcpt.12067] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 03/20/2013] [Indexed: 01/15/2023]
Abstract
WHAT IS KNOWN AND OBJECTIVE Positive inotropic agents are frequently used in acute decompensated heart failure (ADHF) due to left ventricular systolic dysfunction. These agents are known to improve cardiac performance and peripheral perfusion in the short-term treatment. However, several preclinical and clinical studies emphasized detrimental effects of these drugs on myocardial oxygen demand and on sympathetic tone entailing arrhythmogenesis. Levosimendan is an inotropic agent with an original mechanism of action. This review focuses on major data available for levosimendan. METHODS A literature search was conducted in the PubMed database by including studies published in English using combinations of the following key words, levosimendan, inotropic drugs and acute heart failure. Furthermore, bibliographies of selected references were also evaluated for relevant articles. The collection for this review was limited to the most recently available human and animal data. RESULTS AND DISCUSSION Levosimendan's vasodilatory and cardioprotective effects are mediated by calcium sensitization of contractile proteins and opening of adenosine triphosphate (ATP)-dependent K+ channels in vascular smooth muscle cells and on mitochondrial ATP-sensitive potassium [mito.K(ATP)] channels. This inotropic agent has mild PDE inhibitory action. Unlike other inotropic agents, levosimendan improves cardiac performance without activating the sympathetic nervous system. Moreover, there are evidences that levosimendan has additional anti-inflammatory and anti-apoptotic properties that prevent cardiac toxicity and contributes to positive hemodynamic response of the drug. Four randomized trials evaluated the effects of levosimendan on mortality in patients with acute decompensated chronic heart failure; nevertheless, a clear benefit has not been demonstrated so far. Although levosimendan is indicated for the treatment of ADHF (class of recommendation IIa, level of evidence B), it is has not been approved in all countries. WHAT IS NEW AND CONCLUSION This review summarizes the characteristics and the current knowledge of the literature on levosimendan and its active metabolite OR-1896.
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Affiliation(s)
- A Pathak
- Institut National de Sante et de Recherche Médicale (INSERM), UMR-1048, Institut des maladies métaboliques et cardiovasculaires I2MC, Toulouse, France
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Zhang XL, Tibbits GF, Paetzel M. The structure of cardiac troponin C regulatory domain with bound Cd2+ reveals a closed conformation and unique ion coordination. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2013; 69:722-34. [PMID: 23633581 DOI: 10.1107/s0907444913001182] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 01/11/2013] [Indexed: 12/22/2022]
Abstract
The amino-terminal domain of cardiac troponin C (cNTnC) is an essential Ca(2+) sensor found in cardiomyocytes. It undergoes a conformational change upon Ca(2+) binding and transduces the signal to the rest of the troponin complex to initiate cardiac muscle contraction. Two classical EF-hand motifs (EF1 and EF2) are present in cNTnC. Under physiological conditions, only EF2 binds Ca(2+); EF1 is a vestigial site that has lost its function in binding Ca(2+) owing to amino-acid sequence changes during evolution. Proteins with EF-hand motifs are capable of binding divalent cations other than calcium. Here, the crystal structure of wild-type (WT) human cNTnC in complex with Cd(2+) is presented. The structure of Cd(2+)-bound cNTnC with the disease-related mutation L29Q, as well as a structure with the residue differences D2N, V28I, L29Q and G30D (NIQD), which have been shown to have functional importance in Ca(2+) sensing at lower temperatures in ectothermic species, have also been determined. The structures resemble the overall conformation of NMR structures of Ca(2+)-bound cNTnC, but differ significantly from a previous crystal structure of Cd(2+)-bound cNTnC in complex with deoxycholic acid. The subtle structural changes observed in the region near the mutations may play a role in the increased Ca(2+) affinity. The 1.4 Å resolution WT cNTnC structure, which is the highest resolution structure yet obtained for cardiac troponin C, reveals a Cd(2+) ion coordinated in the canonical pentagonal bipyramidal geometry in EF2 despite three residues in the loop being disordered. A Cd(2+) ion found in the vestigial ion-binding site of EF1 is coordinated in a noncanonical `distorted' octahedral geometry. A comparison of the ion coordination observed within EF-hand-containing proteins for which structures have been solved in the presence of Cd(2+) is presented. A refolded WT cNTnC structure is also presented.
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Affiliation(s)
- Xiaolu Linda Zhang
- Department of Molecular Biology and Biochemistry, Simon Fraser University, South Science Building, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
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Abstract
Heart failure (HF) is a vicious circle in which an original insult leading to mechanical cardiac dysfunction initiates multiple morphological, biochemical and molecular pathological alterations referred to as cardiac remodelling. Remodelling leads to further deterioration of cardiac function and functional reserve. Interrupting or reversing cardiac remodelling is a major therapeutic goal of HF therapies. The role of molecules and molecular pathways in cardiac remodelling and HF has been extensively studied. Multiple approaches are now used or investigated in HF therapy, including pharmacological therapy, device therapy, gene therapy, cell therapy and biological therapy targeting cytokines and growth factors. This review explores the molecular targets and molecular bases of current and prospective therapies in HF.
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Affiliation(s)
- Elie R Chemaly
- Cardiovascular Research Center, Mount Sinai School of Medicine, New York, NY 10029, USA
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48
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Pineda-Sanabria SE, Robertson IM, Li MX, Sykes BD. Interaction between the regulatory domain of cardiac troponin C and the acidosis-resistant cardiac troponin I A162H. Cardiovasc Res 2012. [DOI: 10.1093/cvr/cvs348] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Lindert S, Kekenes-Huskey PM, McCammon JA. Long-timescale molecular dynamics simulations elucidate the dynamics and kinetics of exposure of the hydrophobic patch in troponin C. Biophys J 2012; 103:1784-9. [PMID: 23083722 DOI: 10.1016/j.bpj.2012.08.058] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 08/16/2012] [Accepted: 08/20/2012] [Indexed: 01/06/2023] Open
Abstract
Troponin (Tn) is an important regulatory protein in the thin-filament complex of cardiomyocytes. Calcium binding to the troponin C (TnC) subunit causes a change in its dynamics that leads to the transient opening of a hydrophobic patch on TnC's surface, to which a helix of another subunit, troponin I (TnI), binds. This process initiates contraction, making it an important target for studies investigating the detailed molecular processes that underlie contraction. Here we use microsecond-timescale Anton molecular dynamics simulations to investigate the dynamics and kinetics of the opening transition of the TnC hydrophobic patch. Free-energy differences for opening are calculated for wild-type Ca(2+)-bound TnC (∼8 kcal/mol), V44Q Ca(2+)-bound TnC (3.2 kcal/mol), E40A Ca(2+)-bound TnC (∼12 kcal/mol), and wild-type apo TnC (∼20 kcal/mol). These results suggest that the mutations have a profound impact on the frequency with which the hydrophobic patch presents to TnI. In addition, these simulations corroborate that cardiac wild-type TnC does not open on timescales relevant to contraction without calcium being bound.
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Affiliation(s)
- Steffen Lindert
- Department of Pharmacology, University of California San Diego, La Jolla, California, USA.
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Papp Z, Édes I, Fruhwald S, De Hert SG, Salmenperä M, Leppikangas H, Mebazaa A, Landoni G, Grossini E, Caimmi P, Morelli A, Guarracino F, Schwinger RH, Meyer S, Algotsson L, Wikström BG, Jörgensen K, Filippatos G, Parissis JT, González MJG, Parkhomenko A, Yilmaz MB, Kivikko M, Pollesello P, Follath F. Levosimendan: Molecular mechanisms and clinical implications. Int J Cardiol 2012; 159:82-7. [DOI: 10.1016/j.ijcard.2011.07.022] [Citation(s) in RCA: 213] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 07/01/2011] [Accepted: 07/03/2011] [Indexed: 11/28/2022]
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