1
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Codon Usage Bias and Cluster Analysis of the MMP-2 and MMP-9 Genes in Seven Mammals. Genet Res (Camb) 2022; 2022:2823356. [PMID: 36118275 PMCID: PMC9467794 DOI: 10.1155/2022/2823356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 08/04/2022] [Indexed: 11/17/2022] Open
Abstract
Matrix metalloproteinase (MMP)-2 and MMP-9 are a family of Zn2+ and Ca2+-dependent gelatinase MMPs that regulate muscle development and disease treatment, and they are highly conservative during biological evolution. Despite increasing knowledge of MMP genes, their evolutionary mechanism for functional adaption remains unclear. Moreover, analysis of codon usage bias (CUB) is reliable to understand evolutionary associations. However, the distribution of CUB of MMP-2 and MMP-9 genes in mammals has not been revealed clearly. Multiple analytical software was used to study the genetic evolution, phylogeny, and codon usage pattern of these two genes in seven species of mammals. Results showed that the MMP-2 and MMP-9 genes have CUB. By comparing the content of synonymous codon bases amongst seven mammals, we found that MMP-2 and MMP-9 were low-expression genes in mammals with high codon conservation, and their third codon preferred the G/C base. RSCU analysis revealed that these two genes preferred codons encoding delicious amino acids. Analysing what factors influence CUB showed that the third base distributors of these two genes were C/A and C/T, and GC3S had a wide distribution range on the ENC plot reference curve under no selection or mutational pressure. Thus, mutational pressure is an important factor in CUB. This study revealed the usage characteristics of the MMP-2 and MMP-9 gene codons in different mammals and provided basic data for further study towards enhancing meat flavour, treating muscle disease, and optimizing codons.
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2
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The Oxidative Balance Orchestrates the Main Keystones of the Functional Activity of Cardiomyocytes. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2022; 2022:7714542. [PMID: 35047109 PMCID: PMC8763515 DOI: 10.1155/2022/7714542] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 11/03/2021] [Accepted: 12/15/2021] [Indexed: 12/11/2022]
Abstract
This review is aimed at providing an overview of the key hallmarks of cardiomyocytes in physiological and pathological conditions. The main feature of cardiac tissue is the force generation through contraction. This process requires a conspicuous energy demand and therefore an active metabolism. The cardiac tissue is rich of mitochondria, the powerhouses in cells. These organelles, producing ATP, are also the main sources of ROS whose altered handling can cause their accumulation and therefore triggers detrimental effects on mitochondria themselves and other cell components thus leading to apoptosis and cardiac diseases. This review highlights the metabolic aspects of cardiomyocytes and wanders through the main systems of these cells: (a) the unique structural organization (such as different protein complexes represented by contractile, regulatory, and structural proteins); (b) the homeostasis of intracellular Ca2+ that represents a crucial ion for cardiac functions and E-C coupling; and (c) the balance of Zn2+, an ion with a crucial impact on the cardiovascular system. Although each system seems to be independent and finely controlled, the contractile proteins, intracellular Ca2+ homeostasis, and intracellular Zn2+ signals are strongly linked to each other by the intracellular ROS management in a fascinating way to form a "functional tetrad" which ensures the proper functioning of the myocardium. Nevertheless, if ROS balance is not properly handled, one or more of these components could be altered resulting in deleterious effects leading to an unbalance of this "tetrad" and promoting cardiovascular diseases. In conclusion, this "functional tetrad" is proposed as a complex network that communicates continuously in the cardiomyocytes and can drive the switch from physiological to pathological conditions in the heart.
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3
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Chaulin AM. Some Common Causes of False Positive Increases in Serum Levels of Cardiac Troponins. Curr Cardiol Rev 2022; 18:e130422203527. [PMID: 35422225 PMCID: PMC9893154 DOI: 10.2174/1573403x18666220413124038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 02/21/2022] [Accepted: 02/26/2022] [Indexed: 11/22/2022] Open
Abstract
Cardiac troponin molecules (cTnI and cTnT) are the most valuable and in-demand biomarkers for detecting various types of myocardial damage (reversible and irreversible, ischemic, inflammatory, toxic, etc.) in current clinical practice. These biomarkers are widely used for early diagnosis of acute myocardial infarction (AMI) and risk stratification of patients suffering from a number of cardiac (such as myocarditis, heart failure, cardiomyopathy, etc.) and extra-cardiac diseases (such as sepsis, renal failure, pulmonary embolism, neurological pathologies, etc.) that negatively affect the cells of cardiac muscle tissue. However, in daily routine clinical activities, internists and cardiologists often encounter cases of false increases in the concentrations of cardiospecific troponins. A false increase in the concentration of troponins contributes to an incorrect diagnosis and incorrect therapy, which can harm the patient. A false increase in the concentration of troponins contributes to an incorrect diagnosis and incorrect therapy, which can harm the patient, therefore, internists and cardiologists should be well aware of the main reasons and mechanisms for false-positive results cTnI and cTnT. This review article mainly focuses on the causes of falsepositive increases in serum levels of cTnI and cTnT, which provide helpful clues for the accurate diagnosis of AMI and evidence for the differential diagnosis.
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Affiliation(s)
- Aleksey Michailovich Chaulin
- Department of Cardiology and Cardiovascular Surgery, Medical Faculty, Samara State Medical University, Samara, Russia
- Department of Clinical Chemistry, Samara Regional Clinical Cardiological Dispensary, Samara, Russia
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4
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Powers JD, Malingen SA, Regnier M, Daniel TL. The Sliding Filament Theory Since Andrew Huxley: Multiscale and Multidisciplinary Muscle Research. Annu Rev Biophys 2021; 50:373-400. [PMID: 33637009 DOI: 10.1146/annurev-biophys-110320-062613] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Two groundbreaking papers published in 1954 laid out the theory of the mechanism of muscle contraction based on force-generating interactions between myofilaments in the sarcomere that cause filaments to slide past one another during muscle contraction. The succeeding decades of research in muscle physiology have revealed a unifying interest: to understand the multiscale processes-from atom to organ-that govern muscle function. Such an understanding would have profound consequences for a vast array of applications, from developing new biomimetic technologies to treating heart disease. However, connecting structural and functional properties that are relevant at one spatiotemporal scale to those that are relevant at other scales remains a great challenge. Through a lens of multiscale dynamics, we review in this article current and historical research in muscle physiology sparked by the sliding filament theory.
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Affiliation(s)
- Joseph D Powers
- Department of Bioengineering, University of California San Diego, La Jolla, California 92093, USA
| | - Sage A Malingen
- Department of Biology, University of Washington, Seattle, Washington 98195, USA;
| | - Michael Regnier
- Department of Bioengineering, University of Washington, Seattle, Washington 98185, USA
- Center for Translational Muscle Research, University of Washington, Seattle, Washington 98185, USA
| | - Thomas L Daniel
- Department of Biology, University of Washington, Seattle, Washington 98195, USA;
- Department of Bioengineering, University of Washington, Seattle, Washington 98185, USA
- Center for Translational Muscle Research, University of Washington, Seattle, Washington 98185, USA
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5
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Arata T. Myosin and Other Energy-Transducing ATPases: Structural Dynamics Studied by Electron Paramagnetic Resonance. Int J Mol Sci 2020; 21:E672. [PMID: 31968570 PMCID: PMC7014194 DOI: 10.3390/ijms21020672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/05/2020] [Accepted: 01/06/2020] [Indexed: 02/07/2023] Open
Abstract
The objective of this article was to document the energy-transducing and regulatory interactions in supramolecular complexes such as motor, pump, and clock ATPases. The dynamics and structural features were characterized by motion and distance measurements using spin-labeling electron paramagnetic resonance (EPR) spectroscopy. In particular, we focused on myosin ATPase with actin-troponin-tropomyosin, neural kinesin ATPase with microtubule, P-type ion-motive ATPase, and cyanobacterial clock ATPase. Finally, we have described the relationships or common principles among the molecular mechanisms of various energy-transducing systems and how the large-scale thermal structural transition of flexible elements from one state to the other precedes the subsequent irreversible chemical reactions.
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Affiliation(s)
- Toshiaki Arata
- Department of Biology, Graduate School of Science, Osaka City University, Osaka 558-8585, Japan
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6
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Zhao C, Somiya T, Takai S, Ueki S, Arata T. Structural Dynamics of the N-Extension of Cardiac Troponin I Complexed with Troponin C by Site-Directed Spin Labeling Electron Paramagnetic Resonance. Sci Rep 2019; 9:15259. [PMID: 31649274 PMCID: PMC6813352 DOI: 10.1038/s41598-019-51740-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 10/07/2019] [Indexed: 11/29/2022] Open
Abstract
The secondary structure of the N-extension of cardiac troponin I (cTnI) was determined by measuring the distance distribution between spin labels attached to the i and i + 4 residues: 15/19, 23/27, 27/31, 35/39, and 43/47. All of the EPR spectra of these regions in the monomeric state were broadened and had a amplitude that was reduced by two-thirds of that of the single spin-labeled spectra and was fit by two residual distance distributions, with a major distribution one spreading over the range from 1 to 2.5 nm and the other minor peak at 0.9 nm. Only slight or no obvious changes were observed when the extension was bound to cTnC in the cTnI-cTnC complex at 0.2 M KCl. However, at 0.1 M KCl, residues 43/47, located at the PKC phosphorylation sites Ser42/44 on the boundary of the extension, exclusively exhibited a 0.9 nm peak, as expected from α-helix in the crystal structure, in the complex. Furthermore, 23/27, which is located on the PKA phosphorylation sites Ser23/24, showed that the major distribution was markedly narrowed, centered at 1.4 nm and 0.5 nm wide, accompanying the spin label immobilization of residue 27. Residues 35 and 69 at site 1 and 2 of cTnC exhibited partial immobilization of the attached spin labels upon complex formation. The results show that the extension exhibited a primarily partially folded or unfolded structure equilibrated with a transiently formed α-helix-like short structure over the length. We hypothesize that the structure binds at least near sites 1 and 2 of cTnC and that the specific secondary structure of the extension on cTnC becomes uncovered when decreasing the ionic strength demonstrating that only the phosphorylation regions of cTnI interact stereospecifically with cTnC.
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Affiliation(s)
- Chenchao Zhao
- Department of Biological Sciences, Graduate School of Science, Osaka University, Machikaneyama-cho 1-1, Toyonaka, Osaka, 560-0043, Japan
| | - Takayasu Somiya
- Department of Biological Sciences, Graduate School of Science, Osaka University, Machikaneyama-cho 1-1, Toyonaka, Osaka, 560-0043, Japan
| | - Shinji Takai
- Department of Biological Sciences, Graduate School of Science, Osaka University, Machikaneyama-cho 1-1, Toyonaka, Osaka, 560-0043, Japan
| | - Shoji Ueki
- Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Shido 1314-1, Samuki, Kagawa, 769-2193, Japan
| | - Toshiaki Arata
- Department of Biological Sciences, Graduate School of Science, Osaka University, Machikaneyama-cho 1-1, Toyonaka, Osaka, 560-0043, Japan. .,Center for Advanced High Magnetic Field Science, Graduate School of Science, Osaka University, Machikaneyama-cho 1-1, Toyonaka, Osaka, 560-0043, Japan. .,Department of Biology, Graduate School of Science, Osaka City University, Sugimoto 3-3-138, Osaka, Osaka, 558-8585, Japan.
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7
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Tveita T, Arteaga GM, Han YS, Sieck GC. Cardiac troponin-I phosphorylation underlies myocardial contractile dysfunction induced by hypothermia rewarming. Am J Physiol Heart Circ Physiol 2019; 317:H726-H731. [PMID: 31373512 DOI: 10.1152/ajpheart.00101.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Rewarming the intact heart after a period of hypothermia is associated with reduced myocardial contractility, decreased Ca2+ sensitivity, and increased cardiac troponin-I (cTnI) phosphorylation. We hypothesized that hypothermia/rewarming (H/R) induces left ventricular (LV) contractile dysfunction due to phosphorylation of cTnI at Ser23/24. To test this hypothesis, the response of wild-type mice (n = 7) to H/R was compared with transgenic (TG) mice expressing slow skeletal TnI (TG-ssTnI; n = 7) that lacks the Ser23/24 phosphorylation sites. Hypothermia was induced by surface cooling and maintained at 23-25°C for 3 h. Subsequently, the animals were rewarmed to 37°C. LV systolic and diastolic function was assessed using a 1.4 F pressure-volume Millar catheter introduced via the right carotid artery. At baseline conditions, there were no significant differences in LV systolic function between wild-type and TG-ssTnI mice, whereas measurements of diastolic function [isovolumic relaxation constant (τ) and end-diastolic pressure-volume relationship (EDPVR)] were significantly (P < 0.05) reduced in TG-ssTnI animals. Immediately after rewarming, significant differences between groups were found in cardiac output (CO; wild-type 6.6 ± 0.7 vs. TG-ssTnI 8.8 ± 0.7 mL/min), stroke work (SW; wild-type 796 ± 112 vs. TG-ssTnI 1208 ± 67 mmHg/μL), and the preload recruited stroke work (PRSW; wild-type 38.3 ± 4.9 vs. TG-ssTnI 68.8 ± 8.2 mmHg). However, EDPVR and τ returned to control levels within 1 h in both groups. We conclude that H/R-induced LV systolic dysfunction results from phosphorylation of cTnI at Ser23/24.NEW & NOTEWORTHY Rewarming following a period of accidental hypothermia leads to a form of acute cardiac failure (rewarming shock), which is in part due to reduced sensitivity to Ca2+ activation of myocardial contraction. The results of the present study support the hypothesis that rewarming shock is due to phosphorylation of cardiac troponin I.
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Affiliation(s)
- Torkjel Tveita
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota.,Anesthesia and Critical Care Research Group, Institute of Clinical Medicine, The Arctic University of Norway, Tromsø, Norway
| | - Grace M Arteaga
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Young-Soo Han
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Gary C Sieck
- Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, Minnesota
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8
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Schmidt W, Cammarato A. The actin 'A-triad's' role in contractile regulation in health and disease. J Physiol 2019; 598:2897-2908. [PMID: 30770548 DOI: 10.1113/jp276741] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 01/30/2019] [Indexed: 12/15/2022] Open
Abstract
Striated muscle contraction is regulated by Ca2+ -dependent modulation of myosin cross-bridge binding to F-actin by the thin filament troponin (Tn)-tropomyosin (Tm) complex. In the absence of Ca2+ , Tn binds to actin and constrains Tm to an azimuthal location where it sterically occludes myosin binding sites along the thin filament surface. This limits force production and promotes muscle relaxation. In addition to Tn-actin interactions, inhibitory Tm positioning requires associations between other thin filament constituents. For example, the actin 'A-triad', composed of residues K326, K328 and R147, forms numerous, highly favourable electrostatic contacts with Tm that are critical for establishing its inhibitory azimuthal binding position. Here, we review recent findings, including the identification and interrogation of modifications within and proximal to the A-triad that are associated with disease and/or altered muscle behaviour, which highlight the surface feature's role in F-actin-Tm interactions and contractile regulation.
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Affiliation(s)
- William Schmidt
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, 733 N Broadway, 21205, Baltimore, MD, USA
| | - Anthony Cammarato
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, 733 N Broadway, 21205, Baltimore, MD, USA.,Department of Physiology, Johns Hopkins University School of Medicine, 733 N Broadway, 21205, Baltimore, MD, USA
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9
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Marques MA, Parvatiyar MS, Yang W, de Oliveira GAP, Pinto JR. The missing links within troponin. Arch Biochem Biophys 2018; 663:95-100. [PMID: 30584890 DOI: 10.1016/j.abb.2018.12.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 10/18/2018] [Accepted: 12/21/2018] [Indexed: 01/02/2023]
Abstract
The cardiac contraction-relaxation cycle is controlled by a sophisticated set of machinery. Of particular interest, is the revelation that allosteric networks transmit effects of binding at one site to influence troponin complex dynamics and structural-mediated signaling in often distal, functional sites in the myofilament. Our recent observations provide compelling evidence that allostery can explain the function of large-scale macromolecular events. Here we elaborate on our recent findings of interdomain communication within troponin C, using cutting-edge structural biology approaches, and highlight the importance of unveiling the unknown, distant communication networks within this system to obtain more comprehensive knowledge of how allostery impacts cardiac physiology and disease.
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Affiliation(s)
- Mayra A Marques
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Michelle S Parvatiyar
- Department of Nutrition, Food and Exercise Sciences, Florida State University, 107 Chieftan Way, Tallahassee, FL, 32306-1493, USA
| | - Wei Yang
- Department of Chemistry and Biochemistry and Institute of Molecular Biophysics, Florida State University, Kasha Laboratory Building, 91 Chieftan Way, Tallahassee, FL, 32306-4380, USA
| | - Guilherme A P de Oliveira
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, 22908-0733, USA.
| | - Jose R Pinto
- Department of Biomedical Sciences, Florida State University College of Medicine, 1115 West Call Street, Tallahassee, FL, 32306-4300, USA.
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10
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Wang Q, Zhu C, Sun M, Maimaiti R, Ford SP, Nathanielsz PW, Ren J, Guo W. Maternal obesity impairs fetal cardiomyocyte contractile function in sheep. FASEB J 2018; 33:2587-2598. [PMID: 30289749 DOI: 10.1096/fj.201800988r] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Obesity is a major public health problem worldwide. In the United States, one-third of women of reproductive age are obese. Human studies show that maternal obesity (MO) predisposes offspring to cardiovascular disease. However, the underlying mechanisms remain unclear. Given the similarities between pregnancy in sheep and humans, we studied sheep to examine the impact of MO on fetal cardiomyocyte contractility at term. We observed that MO impaired cardiomyocyte contractility by reducing peak shortening and shortening/relengthening velocity, prolonging time to relengthening. MO disrupted Ca2+ homeostasis in fetal cardiomyocytes, increasing intracellular Ca2+ and inducing cellular Ca2+ insensitivity. The Ca2+-release channel was impaired, but Ca2+ uptake was unaffected by MO. The upstream kinases that phosphorylate the Ca2+-release channel-ryanodine receptor-2, PKA, and calmodulin-dependent protein kinase II-were activated in MO fetuses. Contractile dysfunction was associated with an increased ratio of myosin heavy chain (MHC)-β to MHC-α and upregulated cardiac troponin (cTn)-T and tropomyosin, as well as cTn-I phosphorylation. In summary, this is the first characterization of the effects of MO on fetal cardiomyocyte contractility. Our findings indicate that MO impairs fetal cardiomyocyte contractility through altered intracellular Ca2+ handling, overloading fetal cardiomyocyte intracellular Ca2+ and aberrant myofilament protein composition. These mechanisms may contribute to developmental programming by MO of offspring cardiac function and predisposition to later life cardiovascular disease in the offspring.-Wang, Q., Zhu, C., Sun, M., Maimaiti, R., Ford, S. P., Nathanielsz, P. W., Ren, J., Guo, W. Maternal obesity impairs fetal cardiomyocyte contractile function in sheep.
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Affiliation(s)
- Qiurong Wang
- Center for the Study of Fetal Programming, University of Wyoming, Laramie, Wyoming, USA.,Animal Science Department, University of Wyoming, Laramie, Wyoming, USA; and
| | - Chaoqun Zhu
- Animal Science Department, University of Wyoming, Laramie, Wyoming, USA; and
| | - Mingming Sun
- Animal Science Department, University of Wyoming, Laramie, Wyoming, USA; and
| | - Rexiati Maimaiti
- Animal Science Department, University of Wyoming, Laramie, Wyoming, USA; and
| | - Stephen P Ford
- Center for the Study of Fetal Programming, University of Wyoming, Laramie, Wyoming, USA.,Animal Science Department, University of Wyoming, Laramie, Wyoming, USA; and
| | - Peter W Nathanielsz
- Center for the Study of Fetal Programming, University of Wyoming, Laramie, Wyoming, USA.,Animal Science Department, University of Wyoming, Laramie, Wyoming, USA; and
| | - Jun Ren
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, Wyoming, USA
| | - Wei Guo
- Center for the Study of Fetal Programming, University of Wyoming, Laramie, Wyoming, USA.,Animal Science Department, University of Wyoming, Laramie, Wyoming, USA; and.,Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, Laramie, Wyoming, USA
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11
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Shah S, Akhtar MS, Hassan M, Akhtar M, Paudel YN, Najmi AK. EGFR tyrosine kinase inhibition decreases cardiac remodeling and SERCA2a/NCX1 depletion in streptozotocin induced cardiomyopathy in C57/BL6 mice. Life Sci 2018; 210:29-39. [DOI: 10.1016/j.lfs.2018.08.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 07/28/2018] [Accepted: 08/07/2018] [Indexed: 12/22/2022]
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12
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Unravelling the effects of mechanical physiological conditioning on cardiac adipose tissue-derived progenitor cells in vitro and in silico. Sci Rep 2018; 8:499. [PMID: 29323152 PMCID: PMC5764962 DOI: 10.1038/s41598-017-18799-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 12/14/2017] [Indexed: 01/08/2023] Open
Abstract
Mechanical conditioning is incompletely characterized for stimulating therapeutic cells within the physiological range. We sought to unravel the mechanism of action underlying mechanical conditioning of adipose tissue-derived progenitor cells (ATDPCs), both in vitro and in silico. Cardiac ATDPCs, grown on 3 different patterned surfaces, were mechanically stretched for 7 days at 1 Hz. A custom-designed, magnet-based, mechanical stimulator device was developed to apply ~10% mechanical stretching to monolayer cell cultures. Gene and protein analyses were performed for each cell type and condition. Cell supernatants were also collected to analyze secreted proteins and construct an artificial neural network. Gene and protein modulations were different for each surface pattern. After mechanostimulation, cardiac ATDPCs increased the expression of structural genes and there was a rising trend on cardiac transcription factors. Finally, secretome analyses revealed upregulation of proteins associated with both myocardial infarction and cardiac regeneration, such as regulators of the immune response, angiogenesis or cell adhesion. To conclude, mechanical conditioning of cardiac ATDPCs enhanced the expression of early and late cardiac genes in vitro. Additionally, in silico analyses of secreted proteins showed that mechanical stimulation of cardiac ATDPCs was highly associated with myocardial infarction and repair.
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13
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Abstract
Cardiac and skeletal striated muscles are intricately designed machines responsible for muscle contraction. Coordination of the basic contractile unit, the sarcomere, and the complex cytoskeletal networks are critical for contractile activity. The sarcomere is comprised of precisely organized individual filament systems that include thin (actin), thick (myosin), titin, and nebulin. Connecting the sarcomere to other organelles (e.g., mitochondria and nucleus) and serving as the scaffold to maintain cellular integrity are the intermediate filaments. The costamere, on the other hand, tethers the sarcomere to the cell membrane. Unique structures like the intercalated disc in cardiac muscle and the myotendinous junction in skeletal muscle help synchronize and transmit force. Intense investigation has been done on many of the proteins that make up these cytoskeletal assemblies. Yet the details of their function and how they interconnect have just started to be elucidated. A vast number of human myopathies are contributed to mutations in muscle proteins; thus understanding their basic function provides a mechanistic understanding of muscle disorders. In this review, we highlight the components of striated muscle with respect to their interactions, signaling pathways, functions, and connections to disease. © 2017 American Physiological Society. Compr Physiol 7:891-944, 2017.
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Affiliation(s)
- Christine A Henderson
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Christopher G Gomez
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Stefanie M Novak
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Lei Mi-Mi
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Carol C Gregorio
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
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14
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Liu X, Zhang L, Pacciulli D, Zhao J, Nan C, Shen W, Quan J, Tian J, Huang X. Restrictive Cardiomyopathy Caused by Troponin Mutations: Application of Disease Animal Models in Translational Studies. Front Physiol 2016; 7:629. [PMID: 28066262 PMCID: PMC5165243 DOI: 10.3389/fphys.2016.00629] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Accepted: 12/02/2016] [Indexed: 12/14/2022] Open
Abstract
Cardiac troponin I (cTnI) plays a critical role in regulation of cardiac function. Studies have shown that the deficiency of cTnI or mutations in cTnI (particularly in the C-terminus of cTnI) results in diastolic dysfunction (impaired relaxation) due to an increased myofibril sensitivity to calcium. The first clinical study revealing the association between restrictive cardiomyopathy (RCM) with cardiac troponin mutations was reported in 2003. In order to illustrate the mechanisms underlying the cTnI mutation caused cardiomyopathy, we have generated a cTnI gene knockout mouse model and transgenic mouse lines with the reported point mutations in cTnI C-terminus. In this paper, we summarize our studies using these animal models from our laboratory and the other in vitro studies using reconstituted filament and cultured cells. The potential mechanisms underlying diastolic dysfunction and heart failure caused by these cTnI C-terminal mutations are discussed as well. Furthermore, calcium desensitizing in correction of impaired relaxation in myocardial cells due to cTnI mutations is discussed. Finally, we describe a model of translational study, i.e., from bedside to bench and from bench to bedside. These studies may enrich our understanding of the mechanism underlying inherited cardiomyopathies and provide the clues to search for target-oriented medication aiming at the treatment of diastolic dysfunction and heart failure.
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Affiliation(s)
- Xiaoyan Liu
- Cardiovascular Research Laboratory, Division of Cardiology, Chongqing Medical University Children's Hospital Chongqing, China
| | - Lei Zhang
- Cardiovascular Research Laboratory, Division of Cardiology, Chongqing Medical University Children's Hospital Chongqing, China
| | - Daniel Pacciulli
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University Boca Raton, FL, USA
| | - Jianquan Zhao
- Department of Cardiology, Bayannaoer City Hospital Bayannaoer, China
| | - Changlong Nan
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University Boca Raton, FL, USA
| | - Wen Shen
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University Boca Raton, FL, USA
| | - Junjun Quan
- Cardiovascular Research Laboratory, Division of Cardiology, Chongqing Medical University Children's Hospital Chongqing, China
| | - Jie Tian
- Cardiovascular Research Laboratory, Division of Cardiology, Chongqing Medical University Children's Hospital Chongqing, China
| | - Xupei Huang
- Department of Biomedical Science, Charles E. Schmidt College of Medicine, Florida Atlantic University Boca Raton, FL, USA
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15
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Barnes DE, Hwang H, Ono K, Lu H, Ono S. Molecular evolution of troponin I and a role of its N-terminal extension in nematode locomotion. Cytoskeleton (Hoboken) 2016; 73:117-30. [PMID: 26849746 DOI: 10.1002/cm.21281] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 01/22/2016] [Accepted: 01/27/2016] [Indexed: 01/29/2023]
Abstract
The troponin complex, composed of troponin T (TnT), troponin I (TnI), and troponin C (TnC), is the major calcium-dependent regulator of muscle contraction, which is present widely in both vertebrates and invertebrates. Little is known about evolutionary aspects of troponin in the animal kingdom. Using a combination of data mining and functional analysis of TnI, we report evidence that an N-terminal extension of TnI is present in most of bilaterian animals as a functionally important domain. Troponin components have been reported in species in most of representative bilaterian phyla. Comparison of TnI sequences shows that the core domains are conserved in all examined TnIs, and that N- and C-terminal extensions are variable among isoforms and species. In particular, N-terminal extensions are present in all protostome TnIs and chordate cardiac TnIs but lost in a subset of chordate TnIs including vertebrate skeletal-muscle isoforms. Transgenic rescue experiments in Caenorhabditis elegans striated muscle show that the N-terminal extension of TnI (UNC-27) is required for coordinated worm locomotion but not in sarcomere assembly and single muscle-contractility kinetics. These results suggest that N-terminal extensions of TnIs are retained from a TnI ancestor as a functional domain.
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Affiliation(s)
- Dawn E Barnes
- Department of Pathology and Department of Cell Biology, Emory University, Atlanta, Georgia
| | - Hyundoo Hwang
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia.,School of Engineering and Sciences, Technológico de Monterrey, Monterrey, Nuevo León, Mexico
| | - Kanako Ono
- Department of Pathology and Department of Cell Biology, Emory University, Atlanta, Georgia
| | - Hang Lu
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia.,Interdisciplinary Program of Bioengineering, Georgia Institute of Technology, Atlanta, Georgia.,The Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Shoichiro Ono
- Department of Pathology and Department of Cell Biology, Emory University, Atlanta, Georgia
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16
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Bedada FB, Martindale JJ, Arden E, Metzger JM. Molecular inotropy mediated by cardiac miR-based PDE4D/PRKAR1α/phosphoprotein signaling. Sci Rep 2016; 6:36803. [PMID: 27833092 PMCID: PMC5105063 DOI: 10.1038/srep36803] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 10/21/2016] [Indexed: 01/05/2023] Open
Abstract
Molecular inotropy refers to cardiac contractility that can be modified to affect overall heart pump performance. Here we show evidence of a new molecular pathway for positive inotropy by a cardiac-restricted microRNA (miR). We report enhanced cardiac myocyte performance by acute titration of cardiac myosin-embedded miR-208a. The observed positive effect was independent of host gene myosin effects with evidence of negative regulation of cAMP-specific 3',5'-cyclic phosphodiesterase 4D (PDE4D) and the regulatory subunit of PKA (PRKAR1α) content culminating in PKA-site dependent phosphorylation of cardiac troponin I (cTnI) and phospholamban (PLN). Further, acute inhibition of miR-208a in adult myocytes in vitro increased PDE4D expression causing reduced isoproterenol-mediated phosphorylation of cTnI and PLN. Next, rAAV-mediated miR-208a gene delivery enhanced heart contractility and relaxation parameters in vivo. Finally, acute inducible increases in cardiac miR-208a in vivo reduced PDE4D and PRKAR1α, with evidence of increased content of several complementary miRs harboring the PDE4D recognition sequence. Physiologically, this resulted in significant cardiac cTnI and PLN phosphorylation and improved heart performance in vivo. As phosphorylation of cTnI and PLN is critical to myocyte function, titration of miR-208a represents a potential new mechanism to enhance myocardial performance via the PDE4D/PRKAR1α/PKA phosphoprotein signaling pathway.
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Affiliation(s)
- Fikru B. Bedada
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, 6-125 Jackson Hall, 321 Church Street SE, Minneapolis, MN 55455 USA
| | - Joshua J. Martindale
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, 6-125 Jackson Hall, 321 Church Street SE, Minneapolis, MN 55455 USA
| | - Erik Arden
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, 6-125 Jackson Hall, 321 Church Street SE, Minneapolis, MN 55455 USA
| | - Joseph M. Metzger
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, 6-125 Jackson Hall, 321 Church Street SE, Minneapolis, MN 55455 USA
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17
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Papadaki M, Marston SB. The Importance of Intrinsically Disordered Segments of Cardiac Troponin in Modulating Function by Phosphorylation and Disease-Causing Mutations. Front Physiol 2016; 7:508. [PMID: 27853436 PMCID: PMC5089987 DOI: 10.3389/fphys.2016.00508] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 10/17/2016] [Indexed: 11/18/2022] Open
Abstract
Troponin plays a central role in regulation of muscle contraction. It is the Ca2+ switch of striated muscles including the heart and in the cardiac muscle it is physiologically modulated by PKA-dependent phosphorylation at Ser22 and 23. Many cardiomyopathy-related mutations affect Ca2+ regulation and/or disrupt the relationship between Ca2+ binding and phosphorylation. Unlike the mechanism of heart activation, the modulation of Ca2+-sensitivity by phosphorylation of the cardiac specific N-terminal segment of TnI (1–30) is structurally subtle and has proven hard to investigate. The crystal structure of cardiac troponin describes only the relatively stable core of the molecule and the crucial mobile parts of the molecule are missing including TnI C-terminal region, TnI (1–30), TnI (134–149) (“inhibitory” peptide) and the C-terminal 28 amino acids of TnT that are intrinsically disordered. Recent studies have been performed to answer this matter by building structural models of cardiac troponin in phosphorylated and dephosphorylated states based on peptide NMR studies. Now these have been updated by more recent concepts derived from molecular dynamic simulations treating troponin as a dynamic structure. The emerging model confirms the stable core structure of troponin and the mobile structure of the intrinsically disordered segments. We will discuss how we can describe these segments in terms of dynamic transitions between a small number of states, with the probability distributions being altered by phosphorylation and by HCM or DCM-related mutations that can explain how Ca2+-sensitivity is modulated by phosphorylation and the effects of mutations.
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Affiliation(s)
- Maria Papadaki
- Department of Cell and Molecular Physiology, Loyola University of Chicago Maywood, IL, USA
| | - Steven B Marston
- Myocardial Function, National Heart and Lung Institute, Imperial College London London, UK
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18
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Marston SB. Why Is there a Limit to the Changes in Myofilament Ca 2+-Sensitivity Associated with Myopathy Causing Mutations? Front Physiol 2016; 7:415. [PMID: 27725803 PMCID: PMC5035734 DOI: 10.3389/fphys.2016.00415] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 09/05/2016] [Indexed: 12/15/2022] Open
Abstract
Mutations in striated muscle contractile proteins have been found to be the cause of a number of inherited muscle diseases; in most cases the mechanism proposed for causing the disease is derangement of the thin filament-based Ca2+-regulatory system of the muscle. When considering the results of experiments reported over the last 15 years, one feature has been frequently noted, but rarely discussed: the magnitude of changes in myofilament Ca2+-sensitivity due to myopathy-causing mutations in skeletal or heart muscle seems to be always in the range 1.5-3x EC50. Such consistency suggests it may be related to a fundamental property of muscle regulation; in this article we will investigate whether this observation is true and consider why this should be so. A literature search found 71 independent measurements of HCM mutation-induced change of EC50 ranging from 1.15 to 3.8-fold with a mean of 1.87 ± 0.07 (sem). We also found 11 independent measurements of increased Ca2+-sensitivity due to mutations in skeletal muscle proteins ranging from 1.19 to 2.7-fold with a mean of 2.00 ± 0.16. Investigation of dilated cardiomyopathy-related mutations found 42 independent determinations with a range of EC50 wt/mutant from 0.3 to 2.3. In addition we found 14 measurements of Ca2+-sensitivity changes due skeletal muscle myopathy mutations ranging from 0.39 to 0.63. Thus, our extensive literature search, although not necessarily complete, found that, indeed, the changes in myofilament Ca2+-sensitivity due to disease-causing mutations have a bimodal distribution and that the overall changes in Ca2+-sensitivity are quite small and do not extend beyond a three-fold increase or decrease in Ca2+-sensitivity. We discuss two mechanism that are not necessarily mutually exclusive. Firstly, it could be that the limit is set by the capabilities of the excitation-contraction machinery that supplies activating Ca2+ and that striated muscle cannot work in a way compatible with life outside these limits; or it may be due to a fundamental property of the troponin system and the permitted conformational transitions compatible with efficient regulation.
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Affiliation(s)
- Steven B Marston
- National Heart & Lung Institute, Imperial College London London, UK
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19
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Cheng Y, Lindert S, Oxenford L, Tu AY, McCulloch AD, Regnier M. Effects of Cardiac Troponin I Mutation P83S on Contractile Properties and the Modulation by PKA-Mediated Phosphorylation. J Phys Chem B 2016; 120:8238-53. [PMID: 27150586 PMCID: PMC5001945 DOI: 10.1021/acs.jpcb.6b01859] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
cTnI(P82S) (cTnI(P83S) in rodents) resides at the I-T arm of cardiac troponin I (cTnI) and was initially identified as a disease-causing mutation of hypertrophic cardiomyopathy (HCM). However, later studies suggested this may not be true. We recently reported that introduction of an HCM-associated mutation in either inhibitory-peptide (cTnI(R146G)) or cardiac-specific N-terminus (cTnI(R21C)) of cTnI blunts the PKA-mediated modulation on myofibril activation/relaxation kinetics by prohibiting formation of intrasubunit contacts between these regions. Here, we tested whether this also occurs for cTnI(P83S). cTnI(P83S) increased both Ca(2+) binding affinity to cTn (KCa) and affinity of cTnC for cTnI (KC-I), and eliminated the reduction of KCa and KC-I observed for phosphorylated-cTnI(WT). In isolated myofibrils, cTnI(P83S) maintained maximal tension (TMAX) and Ca(2+) sensitivity of tension (pCa50). For cTnI(WT) myofibrils, PKA-mediated phosphorylation decreased pCa50 and sped up the slow-phase relaxation (especially for those Ca(2+) conditions that heart performs in vivo). Those effects were blunted for cTnI(P83S) myofibrils. Molecular-dynamics simulations suggested cTnI(P83S) moderately inhibited an intrasubunit interaction formation between inhibitory-peptide and N-terminus, but this "blunting" effect was weaker than that with cTnI(R146G) or cTnI(R21C). In summary, cTnI(P83S) has similar effects as other HCM-associated cTnI mutations on troponin and myofibril function even though it is in the I-T arm of cTnI.
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Affiliation(s)
- Yuanhua Cheng
- Department of Bioengineering, University of Washington, Seattle, Washington 98105, United States
- National Biomedical Computation Resource, University of California San Diego, La Jolla, California 92093, United States
| | - Steffen Lindert
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Lucas Oxenford
- Department of Bioengineering, University of Washington, Seattle, Washington 98105, United States
| | - An-yue Tu
- Department of Bioengineering, University of Washington, Seattle, Washington 98105, United States
| | - Andrew D. McCulloch
- National Biomedical Computation Resource, University of California San Diego, La Jolla, California 92093, United States
- Department of Bioengineering, University of California San Diego, La Jolla, California 92093, United States
| | - Michael Regnier
- Department of Bioengineering, University of Washington, Seattle, Washington 98105, United States
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington 98195, United States
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20
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Cheng Y, Regnier M. Cardiac troponin structure-function and the influence of hypertrophic cardiomyopathy associated mutations on modulation of contractility. Arch Biochem Biophys 2016; 601:11-21. [PMID: 26851561 PMCID: PMC4899195 DOI: 10.1016/j.abb.2016.02.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 01/30/2016] [Accepted: 02/02/2016] [Indexed: 11/29/2022]
Abstract
Cardiac troponin (cTn) acts as a pivotal regulator of muscle contraction and relaxation and is composed of three distinct subunits (cTnC: a highly conserved Ca(2+) binding subunit, cTnI: an actomyosin ATPase inhibitory subunit, and cTnT: a tropomyosin binding subunit). In this mini-review, we briefly summarize the structure-function relationship of cTn and its subunits, its modulation by PKA-mediated phosphorylation of cTnI, and what is known about how these properties are altered by hypertrophic cardiomyopathy (HCM) associated mutations of cTnI. This includes recent work using computational modeling approaches to understand the atomic-based structural level basis of disease-associated mutations. We propose a viewpoint that it is alteration of cTnC-cTnI interaction (rather than the Ca(2+) binding properties of cTn) per se that disrupt the ability of PKA-mediated phosphorylation at cTnI Ser-23/24 to alter contraction and relaxation in at least some HCM-associated mutations. The combination of state of the art biophysical approaches can provide new insight on the structure-function mechanisms of contractile dysfunction resulting cTnI mutations and exciting new avenues for the diagnosis, prevention, and even treatment of heart diseases.
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Affiliation(s)
- Yuanhua Cheng
- University of Washington, Department of Bioengineering, Seattle, WA, USA
| | - Michael Regnier
- University of Washington, Department of Bioengineering, Seattle, WA, USA.
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21
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Marston S, Messer A, Papadaki M. '(De-)sensitization' vs. 'Uncoupling': what drives cardiomyopathies in the thin filament? Reply. Cardiovasc Res 2016; 109:187-8. [PMID: 26464332 DOI: 10.1093/cvr/cvv233] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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22
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Zamora JE, Papadaki M, Messer AE, Marston SB, Gould IR. Troponin structure: its modulation by Ca2+and phosphorylation studied by molecular dynamics simulations. Phys Chem Chem Phys 2016; 18:20691-707. [DOI: 10.1039/c6cp02610a] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The only available crystal structure of the human cardiac troponin molecule (cTn) in the Ca2+activated state does not include crucial segments, including the N-terminus of the cTn inhibitory subunit (cTnI).
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Affiliation(s)
- Juan Eiros Zamora
- Department of Chemistry
- Institute of Chemical Biology
- Imperial College London
- UK
| | - Maria Papadaki
- National Heart & Lung Institute
- Myocardial Function Section
- Imperial College London
- UK
| | - Andrew E. Messer
- National Heart & Lung Institute
- Myocardial Function Section
- Imperial College London
- UK
| | - Steven B. Marston
- National Heart & Lung Institute
- Myocardial Function Section
- Imperial College London
- UK
| | - Ian R. Gould
- Department of Chemistry
- Institute of Chemical Biology
- Imperial College London
- UK
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23
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Sheng JJ, Jin JP. TNNI1, TNNI2 and TNNI3: Evolution, regulation, and protein structure-function relationships. Gene 2015; 576:385-94. [PMID: 26526134 DOI: 10.1016/j.gene.2015.10.052] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 09/21/2015] [Accepted: 10/20/2015] [Indexed: 12/11/2022]
Abstract
Troponin I (TnI) is the inhibitory subunit of the troponin complex in the sarcomeric thin filament of striated muscle and plays a central role in the calcium regulation of contraction and relaxation. Vertebrate TnI has evolved into three isoforms encoded by three homologous genes: TNNI1 for slow skeletal muscle TnI, TNNI2 for fast skeletal muscle TnI and TNNI3 for cardiac TnI, which are expressed under muscle type-specific and developmental regulations. To summarize the current knowledge on the TnI isoform genes and products, this review focuses on the evolution, gene regulation, posttranslational modifications, and structure-function relationship of TnI isoform proteins. Their physiological and medical significances are also discussed.
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Affiliation(s)
- Juan-Juan Sheng
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Jian-Ping Jin
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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24
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Lindert S, Cheng Y, Kekenes-Huskey P, Regnier M, McCammon JA. Effects of HCM cTnI mutation R145G on troponin structure and modulation by PKA phosphorylation elucidated by molecular dynamics simulations. Biophys J 2015; 108:395-407. [PMID: 25606687 DOI: 10.1016/j.bpj.2014.11.3461] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 11/21/2014] [Accepted: 11/21/2014] [Indexed: 10/24/2022] Open
Abstract
Cardiac troponin (cTn) is a key molecule in the regulation of human cardiac muscle contraction. The N-terminal cardiac-specific peptide of the inhibitory subunit of troponin, cTnI (cTnI(1-39)), is a target for phosphorylation by protein kinase A (PKA) during β-adrenergic stimulation. We recently presented evidence indicating that this peptide interacts with the inhibitory peptide (cTnl(137-147)) when S23 and S24 are phosphorylated. The inhibitory peptide is also the target of the point mutation cTnI-R145G, which is associated with hypertrophic cardiomyopathy (HCM), a disease associated with sudden death in apparently healthy young adults. It has been shown that both phosphorylation and this mutation alter the cTnC-cTnI (C-I) interaction, which plays a crucial role in modulating contractile activation. However, little is known about the molecular-level events underlying this modulation. Here, we computationally investigated the effects of the cTnI-R145G mutation on the dynamics of cTn, cTnC Ca(2+) handling, and the C-I interaction. Comparisons were made with the cTnI-R145G/S23D/S24D phosphomimic mutation, which has been used both experimentally and computationally to study the cTnI N-terminal specific effects of PKA phosphorylation. Additional comparisons between the phosphomimic mutations and the real phosphorylations were made. For this purpose, we ran triplicate 150 ns molecular dynamics simulations of cTnI-R145G Ca(2+)-bound cTnC(1-161)-cTnI(1-172)-cTnT(236-285), cTnI-R145G/S23D/S24D Ca(2+)-bound cTnC(1-161)-cTnI(1-172)-cTnT(236-285), and cTnI-R145G/PS23/PS24 Ca(2+)-bound cTnC(1-161)-cTnI(1-172)-cTnT(236-285), respectively. We found that the cTnI-R145G mutation did not impact the overall dynamics of cTn, but stabilized crucial Ca(2+)-coordinating interactions. However, the phosphomimic mutations increased overall cTn fluctuations and destabilized Ca(2+) coordination. Interestingly, cTnI-R145G blunted the intrasubunit interactions between the cTnI N-terminal extension and the cTnI inhibitory peptide, which have been suggested to play a crucial role in modulating troponin function during β-adrenergic stimulation. These findings offer a molecular-level explanation for how the HCM mutation cTnI-R145G reduces the modulation of cTn by phosphorylation of S23/S24 during β-adrenergic stimulation.
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Affiliation(s)
- Steffen Lindert
- Department of Pharmacology, University of California San Diego, La Jolla, California; NSF Center for Theoretical Biological Physics, La Jolla, California.
| | - Yuanhua Cheng
- Department of Bioengineering, University of Washington, Seattle, Washington
| | - Peter Kekenes-Huskey
- Department of Pharmacology, University of California San Diego, La Jolla, California; Department of Chemistry, University of Kentucky, Lexington, Kentucky
| | - Michael Regnier
- Department of Bioengineering, University of Washington, Seattle, Washington
| | - J Andrew McCammon
- Department of Pharmacology, University of California San Diego, La Jolla, California; Howard Hughes Medical Institute, University of California San Diego, La Jolla, California; Department of Chemistry and Biochemistry, National Biomedical Computation Resource, University of California San Diego, La Jolla, California; NSF Center for Theoretical Biological Physics, La Jolla, California
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25
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Harvey TJ, Murphy RM, Morrison JL, Posterino GS. Maternal Nutrient Restriction Alters Ca2+ Handling Properties and Contractile Function of Isolated Left Ventricle Bundles in Male But Not Female Juvenile Rats. PLoS One 2015; 10:e0138388. [PMID: 26406887 PMCID: PMC4583465 DOI: 10.1371/journal.pone.0138388] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 08/28/2015] [Indexed: 01/09/2023] Open
Abstract
Intrauterine growth restriction (IUGR), defined as a birth weight below the 10th centile, may be caused by maternal undernutrition, with evidence that IUGR offspring have an increased risk of cardiovascular disease (CVD) in adulthood. Calcium ions (Ca2+) are an integral messenger for several steps associated with excitation-contraction coupling (ECC); the cascade of events from the initiation of an action potential at the surface membrane, to contraction of the cardiomyocyte. Any changes in Ca2+ storage and release from the sarcoplasmic reticulum (SR), or sensitivity of the contractile apparatus to Ca2+ may underlie the mechanism linking IUGR to an increased risk of CVD. This study aimed to explore the effects of maternal nutrient restriction on cardiac function, including Ca2+ handling by the SR and force development by the contractile apparatus. Juvenile Long Evans hooded rats born to Control (C) and nutrient restricted (NR) dams were anaesthetized for collection of the heart at 10–12 weeks of age. Left ventricular bundles from male NR offspring displayed increased maximum Ca2+-activated force, and decreased protein content of troponin I (cTnI) compared to C males. Furthermore, male NR offspring showed a reduction in rate of rise of the caffeine-induced Ca2+ force response and a decrease in the protein content of ryanodine receptor (RYR2). These physiological and biochemical findings observed in males were not evident in female offspring. These findings illustrate a sex-specific effect of maternal NR on cardiac development, and also highlight a possible mechanism for the development of hypertension and hypertrophy in male NR offspring.
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Affiliation(s)
- Thomas J. Harvey
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, Vic, Australia
- * E-mail:
| | - Robyn M. Murphy
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Vic, Australia
| | - Janna L. Morrison
- School of Pharmacy and Medical Science, Sansom Institute for Health Research, University of South Australia, Adelaide, Australia
| | - Giuseppe S. Posterino
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Melbourne, Vic, Australia
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26
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Cheng Y, Rao V, Tu AY, Lindert S, Wang D, Oxenford L, McCulloch AD, McCammon JA, Regnier M. Troponin I Mutations R146G and R21C Alter Cardiac Troponin Function, Contractile Properties, and Modulation by Protein Kinase A (PKA)-mediated Phosphorylation. J Biol Chem 2015; 290:27749-66. [PMID: 26391394 DOI: 10.1074/jbc.m115.683045] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Indexed: 11/06/2022] Open
Abstract
Two hypertrophic cardiomyopathy-associated cardiac troponin I (cTnI) mutations, R146G and R21C, are located in different regions of cTnI, the inhibitory peptide and the cardiac-specific N terminus. We recently reported that these regions may interact when Ser-23/Ser-24 are phosphorylated, weakening the interaction of cTnI with cardiac TnC. Little is known about how these mutations influence the affinity of cardiac TnC for cTnI (KC-I) or contractile kinetics during β-adrenergic stimulation. Here, we tested how cTnI(R146G) or cTnI(R21C) influences contractile activation and relaxation and their response to protein kinase A (PKA). Both mutations significantly increased Ca(2+) binding affinity to cTn (KCa) and KC-I. PKA phosphorylation resulted in a similar reduction of KCa for all complexes, but KC-I was reduced only with cTnI(WT). cTnI(WT), cTnI(R146G), and cTnI(R21C) were complexed into cardiac troponin and exchanged into rat ventricular myofibrils, and contraction/relaxation kinetics were measured ± PKA phosphorylation. Maximal tension (Tmax) was maintained for cTnI(R146G)- and cTnI(R21C)-exchanged myofibrils, and Ca(2+) sensitivity of tension (pCa50) was increased. PKA phosphorylation decreased pCa50 for cTnI(WT)-exchanged myofibrils but not for either mutation. PKA phosphorylation accelerated the early slow phase relaxation for cTnI(WT) myofibrils, especially at Ca(2+) levels that the heart operates in vivo. Importantly, this effect was blunted for cTnI(R146G)- and cTnI(R21C)-exchanged myofibrils. Molecular dynamics simulations suggest both mutations inhibit formation of intra-subunit contacts between the N terminus and the inhibitory peptide of cTnI that is normally seen with WT-cTn upon PKA phosphorylation. Together, our results suggest that cTnI(R146G) and cTnI(R21C) blunt PKA modulation of activation and relaxation kinetics by prohibiting cardiac-specific N-terminal interaction with the cTnI inhibitory peptide.
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Affiliation(s)
- Yuanhua Cheng
- From the Department of Bioengineering, University of Washington, Seattle, Washington 98105, the National Biomedical Computational Resource and
| | - Vijay Rao
- From the Department of Bioengineering, University of Washington, Seattle, Washington 98105
| | - An-Yue Tu
- From the Department of Bioengineering, University of Washington, Seattle, Washington 98105
| | - Steffen Lindert
- Pharmacology, University of California at San Diego, La Jolla, California 92093, and
| | - Dan Wang
- From the Department of Bioengineering, University of Washington, Seattle, Washington 98105
| | - Lucas Oxenford
- From the Department of Bioengineering, University of Washington, Seattle, Washington 98105
| | - Andrew D McCulloch
- the National Biomedical Computational Resource and Departments of Bioengineering and
| | - J Andrew McCammon
- the National Biomedical Computational Resource and Pharmacology, University of California at San Diego, La Jolla, California 92093, and
| | - Michael Regnier
- From the Department of Bioengineering, University of Washington, Seattle, Washington 98105, the Center for Cardiovascular Biology, University of Washington, Seattle, Washington 98105
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Solaro RJ. A sarcomeric protein tongue-twister: post-translation, citrullination/deimination and elimination of arginine residues. Cardiovasc Res 2015; 108:212-4. [PMID: 26392345 DOI: 10.1093/cvr/cvv220] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- R John Solaro
- Department of Physiology and Biophysics and Center for Cardiovascular Research, University of Illinois at Chicago, College of Medicine, 835 S. Wolcott Avenue, Chicago, IL 60612, USA
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The Mechanism Research of Qishen Yiqi Formula by Module-Network Analysis. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2015; 2015:497314. [PMID: 26379745 PMCID: PMC4561322 DOI: 10.1155/2015/497314] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 08/04/2015] [Indexed: 01/18/2023]
Abstract
Qishen Yiqi formula (QSYQ) has the effect of tonifying Qi and promoting blood circulation, which is widely used to treat the cardiovascular diseases with Qi deficiency and blood stasis syndrome. However, the mechanism of QSYQ to tonify Qi and promote blood circulation is rarely reported at molecular or systems level. This study aimed to elucidate the mechanism of QSYQ based on the protein interaction network (PIN) analysis. The targets' information of the active components was obtained from ChEMBL and STITCH databases and was further used to search against protein-protein interactions by String database. Next, the PINs of QSYQ were constructed by Cytoscape and were analyzed by gene ontology enrichment analysis based on Markov Cluster algorithm. Finally, based on the topological parameters, the properties of scale-free, small world, and modularity of the QSYQ's PINs were analyzed. And based on function modules, the mechanism of QSYQ was elucidated. The results indicated that Qi-tonifying efficacy of QSYQ may be partly attributed to the regulation of amino acid metabolism, carbohydrate metabolism, lipid metabolism, and cAMP metabolism, while QSYQ improves the blood stasis through the regulation of blood coagulation and cardiac muscle contraction. Meanwhile, the “synergy” of formula compatibility was also illuminated.
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Rao V, Cheng Y, Lindert S, Wang D, Oxenford L, McCulloch AD, McCammon JA, Regnier M. PKA phosphorylation of cardiac troponin I modulates activation and relaxation kinetics of ventricular myofibrils. Biophys J 2015; 107:1196-1204. [PMID: 25185555 DOI: 10.1016/j.bpj.2014.07.027] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 07/10/2014] [Accepted: 07/15/2014] [Indexed: 10/24/2022] Open
Abstract
Protein kinase A (PKA) phosphorylation of myofibril proteins constitutes an important pathway for β-adrenergic modulation of cardiac contractility and relaxation. PKA targets the N-terminus (Ser-23/24) of cardiac troponin I (cTnI), cardiac myosin-binding protein C (cMyBP-C) and titin. The effect of PKA-mediated phosphorylation on the magnitude of contraction has been studied in some detail, but little is known about how it modulates the kinetics of thin filament activation and myofibril relaxation as Ca(2+) levels vary. Troponin C (cTnC) interaction with cTnI (C-I interaction) is a critical step in contractile activation that can be modulated by cTnI phosphorylation. We tested the hypothesis that altering C-I interactions by PKA, or by cTnI phosphomimetic mutations (S23D/S24D-cTnI), directly affects thin filament activation and myofilament relaxation kinetics. Rat ventricular myofibrils were isolated and endogenous cTn was exchanged with either wild-type cTnI, or S23D/S24D-cTnI recombinant cTn. Contractile mechanics were monitored at maximum and submaximal Ca(2+) concentrations. PKA treatment of wild-type cTn or exchange of cTn containing S23D/S24D-cTnI resulted in an increase in the rate of early, slow phase of relaxation (kREL,slow) and a decrease in its duration (tREL,slow). These effects were greater for submaximal Ca(2+) activated contractions. PKA treatment also reduced the rate of contractile activation (kACT) at maximal, but not submaximal Ca(2+), and reduced the Ca(2+) sensitivity of contraction. Using a fluorescent probe coupled to cTnC (C35S-IANBD), the Ca(2+)-cTn binding affinity and C-I interaction were monitored. Ca(2+) binding to cTn (pCa50) was significantly decreased when cTnI was phosphorylated by PKA (ΔpCa50 = 0.31). PKA phosphorylation of cTnI also weakened C-I interaction in the presence of Ca(2+). These data suggest that weakened C-I interaction, via PKA phosphorylation of cTnI, may slow thin filament activation and result in increased myofilament relaxation kinetics, the latter of which could enhance early phase diastolic relaxation during β-adrenergic stimulation.
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Affiliation(s)
- Vijay Rao
- University of Washington, Department of Bioengineering, Seattle, Washington
| | - Yuanhua Cheng
- University of Washington, Department of Bioengineering, Seattle, Washington; National Biomedical Computational Resource, La Jolla, California
| | - Steffen Lindert
- University of California San Diego, Department of Pharmacology, La Jolla, California
| | - Dan Wang
- University of Washington, Department of Bioengineering, Seattle, Washington
| | - Lucas Oxenford
- University of Washington, Department of Bioengineering, Seattle, Washington
| | - Andrew D McCulloch
- University of California San Diego, Department of Bioengineering, La Jolla, California; National Biomedical Computational Resource, La Jolla, California
| | - J Andrew McCammon
- University of California San Diego, Department of Pharmacology, La Jolla, California; National Biomedical Computational Resource, La Jolla, California
| | - Michael Regnier
- University of Washington, Department of Bioengineering, Seattle, Washington.
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McConnell BK, Singh S, Fan Q, Hernandez A, Portillo JP, Reiser PJ, Tikunova SB. Knock-in mice harboring a Ca(2+) desensitizing mutation in cardiac troponin C develop early onset dilated cardiomyopathy. Front Physiol 2015; 6:242. [PMID: 26379556 PMCID: PMC4550777 DOI: 10.3389/fphys.2015.00242] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 08/11/2015] [Indexed: 12/05/2022] Open
Abstract
The physiological consequences of aberrant Ca(2+) binding and exchange with cardiac myofilaments are not clearly understood. In order to examine the effect of decreasing Ca(2+) sensitivity of cTnC on cardiac function, we generated knock-in mice carrying a D73N mutation (not known to be associated with heart disease in human patients) in cTnC. The D73N mutation was engineered into the regulatory N-domain of cTnC in order to reduce Ca(2+) sensitivity of reconstituted thin filaments by increasing the rate of Ca(2+) dissociation. In addition, the D73N mutation drastically blunted the extent of Ca(2+) desensitization of reconstituted thin filaments induced by cTnI pseudo-phosphorylation. Compared to wild-type mice, heterozygous knock-in mice carrying the D73N mutation exhibited a substantially decreased Ca(2+) sensitivity of force development in skinned ventricular trabeculae. Kaplan-Meier survival analysis revealed that median survival time for knock-in mice was 12 weeks. Echocardiographic analysis revealed that knock-in mice exhibited increased left ventricular dimensions with thinner walls. Echocardiographic analysis also revealed that measures of systolic function, such as ejection fraction (EF) and fractional shortening (FS), were dramatically reduced in knock-in mice. In addition, knock-in mice displayed electrophysiological abnormalities, namely prolonged QRS and QT intervals. Furthermore, ventricular myocytes isolated from knock-in mice did not respond to β-adrenergic stimulation. Thus, knock-in mice developed pathological features similar to those observed in human patients with dilated cardiomyopathy (DCM). In conclusion, our results suggest that decreasing Ca(2+) sensitivity of the regulatory N-domain of cTnC is sufficient to trigger the development of DCM.
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Affiliation(s)
- Bradley K. McConnell
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
| | - Sonal Singh
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
| | - Qiying Fan
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
| | - Adriana Hernandez
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
| | - Jesus P. Portillo
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
| | - Peter J. Reiser
- Division of Biosciences, College of Dentistry, The Ohio State UniversityColumbus, OH, USA
| | - Svetlana B. Tikunova
- Department of Pharmacological and Pharmaceutical Sciences, University of HoustonHouston, TX, USA
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Land S, Niederer SA. A Spatially Detailed Model of Isometric Contraction Based on Competitive Binding of Troponin I Explains Cooperative Interactions between Tropomyosin and Crossbridges. PLoS Comput Biol 2015; 11:e1004376. [PMID: 26262582 PMCID: PMC4532474 DOI: 10.1371/journal.pcbi.1004376] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 06/03/2015] [Indexed: 01/20/2023] Open
Abstract
Biophysical models of cardiac tension development provide a succinct representation of our understanding of force generation in the heart. The link between protein kinetics and interactions that gives rise to high cooperativity is not yet fully explained from experiments or previous biophysical models. We propose a biophysical ODE-based representation of cross-bridge (XB), tropomyosin and troponin within a contractile regulatory unit (RU) to investigate the mechanisms behind cooperative activation, as well as the role of cooperativity in dynamic tension generation across different species. The model includes cooperative interactions between regulatory units (RU-RU), between crossbridges (XB-XB), as well more complex interactions between crossbridges and regulatory units (XB-RU interactions). For the steady-state force-calcium relationship, our framework predicts that: (1) XB-RU effects are key in shifting the half-activation value of the force-calcium relationship towards lower [Ca2+], but have only small effects on cooperativity. (2) XB-XB effects approximately double the duty ratio of myosin, but do not significantly affect cooperativity. (3) RU-RU effects derived from the long-range action of tropomyosin are a major factor in cooperative activation, with each additional unblocked RU increasing the rate of additional RU’s unblocking. (4) Myosin affinity for short (1–4 RU) unblocked stretches of actin of is very low, and the resulting suppression of force at low [Ca2+] is a major contributor in the biphasic force-calcium relationship. We also reproduce isometric tension development across mouse, rat and human at physiological temperature and pacing rate, and conclude that species differences require only changes in myosin affinity and troponin I/troponin C affinity. Furthermore, we show that the calcium dependence of the rate of tension redevelopment ktr is explained by transient blocking of RU’s by a temporary decrease in XB-RU effects. Force generation in cardiac muscle cells is driven by changes in calcium concentration. Relatively small changes in the calcium concentration over the course of a heart beat lead to the large changes in force required to fully contract and relax the heart. This is known as ‘cooperative activation’, and involves a complex interaction of several proteins involved in contraction. Current computer models which reproduce force generation often do not represent these processes explicitly, and stochastic approaches that do tend to require large amounts of computational power to solve, which limit the range of investigations in which they can be used. We have created an new computational model that captures the underlying physiological processes in more detail, and is more efficient than stochastic approaches, while still being able to run a large range of simulations. The model is able to explain the biological processes leading to the cooperative activation of muscle. In addition, the model reproduces how this cooperative activation translates to normal muscle function to generate force from changes in calcium across three different species.
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Affiliation(s)
- Sander Land
- Department of Biomedical Engineering, King’s College London, United Kingdom
- * E-mail:
| | - Steven A. Niederer
- Department of Biomedical Engineering, King’s College London, United Kingdom
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Vikhorev PG, Song W, Wilkinson R, Copeland O, Messer AE, Ferenczi MA, Marston SB. The dilated cardiomyopathy-causing mutation ACTC E361G in cardiac muscle myofibrils specifically abolishes modulation of Ca(2+) regulation by phosphorylation of troponin I. Biophys J 2015; 107:2369-80. [PMID: 25418306 PMCID: PMC4241448 DOI: 10.1016/j.bpj.2014.10.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 09/25/2014] [Accepted: 10/16/2014] [Indexed: 01/30/2023] Open
Abstract
Phosphorylation of troponin I by protein kinase A (PKA) reduces Ca2+ sensitivity and increases the rate of Ca2+ release from troponin C and the rate of relaxation in cardiac muscle. In vitro experiments indicate that mutations that cause dilated cardiomyopathy (DCM) uncouple this modulation, but this has not been demonstrated in an intact contractile system. Using a Ca2+-jump protocol, we measured the effect of the DCM-causing mutation ACTC E361G on the equilibrium and kinetic parameters of Ca2+ regulation of contractility in single transgenic mouse heart myofibrils. We used propranolol treatment of mice to reduce the level of troponin I and myosin binding protein C (MyBP-C) phosphorylation in their hearts before isolating the myofibrils. In nontransgenic mouse myofibrils, the Ca2+ sensitivity of force was increased, the fast relaxation phase rate constant, kREL, was reduced, and the length of the slow linear phase, tLIN, was increased when the troponin I phosphorylation level was reduced from 1.02 to 0.3 molPi/TnI (EC50 P/unP = 1.8 ± 0.2, p < 0.001). Native myofibrils from ACTC E361G transgenic mice had a 2.4-fold higher Ca2+ sensitivity than nontransgenic mouse myofibrils. Strikingly, the Ca2+ sensitivity and relaxation parameters of ACTC E361G myofibrils did not depend on the troponin I phosphorylation level (EC50 P/unP = 0.88 ± 0.17, p = 0.39). Nevertheless, modulation of the Ca2+ sensitivity of ACTC E361G myofibrils by sarcomere length or EMD57033 was indistinguishable from that of nontransgenic myofibrils. Overall, EC50 measured in different conditions varied over a 7-fold range. The time course of relaxation, as defined by tLIN and kREL, was correlated with EC50 but varied by just 2.7- and 3.3-fold, respectively. Our results confirm that troponin I phosphorylation specifically alters the Ca2+ sensitivity of isometric tension and the time course of relaxation in cardiac muscle myofibrils. Moreover, the DCM-causing mutation ACTC E361G blunts this phosphorylation-dependent response without affecting other parameters of contraction, including length-dependent activation and the response to EMD57033.
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Affiliation(s)
- Petr G Vikhorev
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Weihua Song
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Ross Wilkinson
- National Heart and Lung Institute, Imperial College London, London, UK
| | - O'Neal Copeland
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Andrew E Messer
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Michael A Ferenczi
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Steven B Marston
- National Heart and Lung Institute, Imperial College London, London, UK.
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Waddingham MT, Edgley AJ, Tsuchimochi H, Kelly DJ, Shirai M, Pearson JT. Contractile apparatus dysfunction early in the pathophysiology of diabetic cardiomyopathy. World J Diabetes 2015; 6:943-960. [PMID: 26185602 PMCID: PMC4499528 DOI: 10.4239/wjd.v6.i7.943] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 12/30/2014] [Accepted: 03/09/2015] [Indexed: 02/05/2023] Open
Abstract
Diabetes mellitus significantly increases the risk of cardiovascular disease and heart failure in patients. Independent of hypertension and coronary artery disease, diabetes is associated with a specific cardiomyopathy, known as diabetic cardiomyopathy (DCM). Four decades of research in experimental animal models and advances in clinical imaging techniques suggest that DCM is a progressive disease, beginning early after the onset of type 1 and type 2 diabetes, ahead of left ventricular remodeling and overt diastolic dysfunction. Although the molecular pathogenesis of early DCM still remains largely unclear, activation of protein kinase C appears to be central in driving the oxidative stress dependent and independent pathways in the development of contractile dysfunction. Multiple subcellular alterations to the cardiomyocyte are now being highlighted as critical events in the early changes to the rate of force development, relaxation and stability under pathophysiological stresses. These changes include perturbed calcium handling, suppressed activity of aerobic energy producing enzymes, altered transcriptional and posttranslational modification of membrane and sarcomeric cytoskeletal proteins, reduced actin-myosin cross-bridge cycling and dynamics, and changed myofilament calcium sensitivity. In this review, we will present and discuss novel aspects of the molecular pathogenesis of early DCM, with a special focus on the sarcomeric contractile apparatus.
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Papadaki M, Vikhorev PG, Marston SB, Messer AE. Uncoupling of myofilament Ca2+ sensitivity from troponin I phosphorylation by mutations can be reversed by epigallocatechin-3-gallate. Cardiovasc Res 2015; 108:99-110. [PMID: 26109583 DOI: 10.1093/cvr/cvv181] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 06/11/2015] [Indexed: 02/02/2023] Open
Abstract
AIMS Heart muscle contraction is regulated via the β-adrenergic response that leads to phosphorylation of Troponin I (TnI) at Ser22/23, which changes the Ca(2+) sensitivity of the cardiac myofilament. Mutations in thin filament proteins that cause dilated cardiomyopathy (DCM) and some mutations that cause hypertrophic cardiomyopathy (HCM) abolish the relationship between TnI phosphorylation and Ca(2+) sensitivity (uncoupling). Small molecule Ca(2+) sensitizers and Ca(2+) desensitizers that act upon troponin alter the Ca(2+) sensitivity of the thin filament, but their relationship with TnI phosphorylation has never been studied before. METHODS AND RESULTS Quantitative in vitro motility assay showed that 30 µM EMD57033 and 100 µM Bepridil increase Ca(2+) sensitivity of phosphorylated cardiac thin filaments by 3.1- and 2.8-fold, respectively. Additionally they uncoupled Ca(2+) sensitivity from TnI phosphorylation, mimicking the effect of HCM mutations. Epigallocatechin-3-gallate (EGCG) decreased Ca(2+) sensitivity of phosphorylated and unphosphorylated wild-type thin filaments equally (by 2.15 ± 0.45- and 2.80 ± 0.48-fold, respectively), retaining the coupling. Moreover, EGCG also reduced Ca(2+) sensitivity of phosphorylated but not unphosphorylated thin filaments containing DCM and HCM-causing mutations; thus, the dependence of Ca(2+) sensitivity upon TnI phosphorylation of uncoupled mutant thin filaments was restored in every case. In single mouse heart myofibrils, EGCG reduced Ca(2+) sensitivity of force and kACT and also preserved coupling. Myofibrils from the ACTC E361G (DCM) mouse were uncoupled; EGCG reduced Ca(2+) sensitivity more for phosphorylated than for unphosphorylated myofibrils, thus restoring coupling. CONCLUSION We conclude that it is possible to both mimic and reverse the pathological defects in troponin caused by cardiomyopathy mutations pharmacologically. Re-coupling by EGCG may be of potential therapeutic significance for treating cardiomyopathies.
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Affiliation(s)
- Maria Papadaki
- National Heart and Lung Institute, Imperial College London, London W12 0NN, UK
| | - Petr G Vikhorev
- National Heart and Lung Institute, Imperial College London, London W12 0NN, UK
| | - Steven B Marston
- National Heart and Lung Institute, Imperial College London, London W12 0NN, UK
| | - Andrew E Messer
- National Heart and Lung Institute, Imperial College London, London W12 0NN, UK
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Schwan J, Campbell SG. Prospects for In Vitro Myofilament Maturation in Stem Cell-Derived Cardiac Myocytes. Biomark Insights 2015; 10:91-103. [PMID: 26085788 PMCID: PMC4463797 DOI: 10.4137/bmi.s23912] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 03/09/2015] [Accepted: 03/11/2015] [Indexed: 12/20/2022] Open
Abstract
Cardiomyocytes derived from human stem cells are quickly becoming mainstays of cardiac regenerative medicine, in vitro disease modeling, and drug screening. Their suitability for such roles may seem obvious, but assessments of their contractile behavior suggest that they have not achieved a completely mature cardiac muscle phenotype. This could be explained in part by an incomplete transition from fetal to adult myofilament protein isoform expression. In this commentary, we review evidence that supports this hypothesis and discuss prospects for ultimately generating engineered heart tissue specimens that behave similarly to adult human myocardium. We suggest approaches to better characterize myofilament maturation level in these in vitro systems, and illustrate how new computational models could be used to better understand complex relationships between muscle contraction, myofilament protein isoform expression, and maturation.
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Affiliation(s)
- Jonas Schwan
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
| | - Stuart G Campbell
- Department of Biomedical Engineering, Yale University, New Haven, CT, USA
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Pineda-Sanabria SE, Robertson IM, Sykes BD. Structure and Dynamics of the Acidosis-Resistant A162H Mutant of the Switch Region of Troponin I Bound to the Regulatory Domain of Troponin C. Biochemistry 2015; 54:3583-93. [DOI: 10.1021/acs.biochem.5b00178] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Sandra E. Pineda-Sanabria
- Department of Biochemistry, ‡Department of Pediatrics, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Ian M. Robertson
- Department of Biochemistry, ‡Department of Pediatrics, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
| | - Brian D. Sykes
- Department of Biochemistry, ‡Department of Pediatrics, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB T6G 2H7, Canada
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Dissecting human skeletal muscle troponin proteoforms by top-down mass spectrometry. J Muscle Res Cell Motil 2015; 36:169-81. [PMID: 25613324 DOI: 10.1007/s10974-015-9404-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 01/07/2015] [Indexed: 01/26/2023]
Abstract
Skeletal muscles are the most abundant tissues in the human body. They are composed of a heterogeneous collection of muscle fibers that perform various functions. Skeletal muscle troponin (sTn) regulates skeletal muscle contraction and relaxation. sTn consists of 3 subunits, troponin I (TnI), troponin T (TnT), and troponin C (TnC). TnI inhibits the actomyosin Mg(2+)-ATPase, TnC binds Ca(2+), and TnT is the tropomyosin (Tm)-binding subunit. The cardiac and skeletal isoforms of Tn share many similarities but the roles of modifications of Tn in the two muscles may differ. The modifications of cardiac Tn are known to alter muscle contractility and have been well-characterized. However, the modification status of sTn remains unclear. Here, we have employed top-down mass spectrometry (MS) to decipher the modifications of human sTnT and sTnI. We have extensively characterized sTnT and sTnI proteoforms, including alternatively spliced isoforms and post-translationally modified forms, found in human skeletal muscle with high mass accuracy and comprehensive sequence coverage. Moreover, we have localized the phosphorylation site of slow sTnT isoform III to Ser1 by tandem MS with electron capture dissociation. This is the first study to comprehensively characterize human sTn and also the first to identify the basal phosphorylation site for human sTnT by top-down MS.
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Akhter S, Jin JP. Distinct conformational and functional effects of two adjacent pathogenic mutations in cardiac troponin I at the interface with troponin T. FEBS Open Bio 2015; 5:64-75. [PMID: 25685665 PMCID: PMC4325132 DOI: 10.1016/j.fob.2015.01.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 12/31/2014] [Accepted: 01/02/2015] [Indexed: 11/29/2022] Open
Abstract
Mutations in the TnT-interface of cardiac TnI cause cardiomyopathies. Mutations A117G and K118C resulted in distinct changes in protein conformation. K118C, but not A117G, decreased the binding affinity for TnT. K118C decreased binding affinity for TnC in a Ca2+-dependent manner – A117G had a similar but less profound effect. PKA treatment or N-terminal truncation produces similar changes in cardiac TnI.
The α-helix in troponin I (TnI) at the interface with troponin T (TnT) is a highly conserved structure. A point mutation in this region, A116G, was found in human cardiac TnI in a case of cardiomyopathy. An adjacent dominantly negative mutation found in turkey cardiac TnI (R111C, equivalent to K117C in human and K118C in mouse) decreased diastolic function and blunted beta-adrenergic response in transgenic mice. To investigate the functional importance of the TnI–TnT interface and pathological impact of the cardiac TnI mutations, we engineered K118C and A117G mutations in mouse cardiac TnI for functional studies. Despite their adjacent locations, A117G substitution results in faster mobility of cardiac TnI in SDS–PAGE whereas K118C decreases gel mobility, indicating significant and distinct changes in overall protein conformation. Consistently, monoclonal antibody epitope analysis demonstrated distinct local and remote conformational alterations in the two mutant proteins. Protein binding assays showed that K118C, but not A117G, decreased the relative binding affinity of cardiac TnI for TnT. K118C mutation decreased binding affinity for troponin C in a Ca2+-dependent manner, whereas A117G had a similar but less profound effect. Protein kinase A phosphorylation or truncation to remove the cardiac specific N-terminal extension of cardiac TnI resulted in similar conformational changes in the region interfacing with TnT and minimized the functional impacts of the mutations. The data demonstrate potent conformational and functional impacts of the TnT-interfacing helix in TnI and suggest a role of the N-terminal extension of cardiac TnI in modulating TnI–TnT interface functions.
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Key Words
- BSA, bovine serum albumin
- Cardiac muscle
- ELISA, enzyme linked immunosorbent assay
- McTnI, wild type mouse cardiac TnI
- McTnI-ND, N-terminal truncated mouse cardiac TnI
- McTnI-NDA117G, N-terminal truncated McTnIA117G
- McTnI-NDK118C, N-terminal truncated McTnIK118C
- McTnIA117G, mouse cardiac TnI A117G mutation
- McTnIK118C, mouse cardiac TnI K118C mutation
- PKA, protein kinase A
- Protein conformation
- TnC, troponin C
- TnI, troponin I
- TnT, troponin T
- Troponin
- Troponin I mutation
- Troponin I–Troponin T interface
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Affiliation(s)
- Shirin Akhter
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States
| | - J-P Jin
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States
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Gregorich ZR, Ge Y. Top-down proteomics in health and disease: challenges and opportunities. Proteomics 2014; 14:1195-210. [PMID: 24723472 DOI: 10.1002/pmic.201300432] [Citation(s) in RCA: 147] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 03/10/2014] [Accepted: 03/24/2014] [Indexed: 01/06/2023]
Abstract
Proteomics is essential for deciphering how molecules interact as a system and for understanding the functions of cellular systems in human disease; however, the unique characteristics of the human proteome, which include a high dynamic range of protein expression and extreme complexity due to a plethora of PTMs and sequence variations, make such analyses challenging. An emerging "top-down" MS-based proteomics approach, which provides a "bird's eye" view of all proteoforms, has unique advantages for the assessment of PTMs and sequence variations. Recently, a number of studies have showcased the potential of top-down proteomics for the unraveling of disease mechanisms and discovery of new biomarkers. Nevertheless, the top-down approach still faces significant challenges in terms of protein solubility, separation, and the detection of large intact proteins, as well as underdeveloped data analysis tools. Consequently, new technological developments are urgently needed to advance the field of top-down proteomics. Herein, we intend to provide an overview of the recent applications of top-down proteomics in biomedical research. Moreover, we will outline the challenges and opportunities facing top-down proteomics strategies aimed at understanding and diagnosing human diseases.
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Affiliation(s)
- Zachery R Gregorich
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI, USA; Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
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Yang S, Barbu-Tudoran L, Orzechowski M, Craig R, Trinick J, White H, Lehman W. Three-dimensional organization of troponin on cardiac muscle thin filaments in the relaxed state. Biophys J 2014; 106:855-64. [PMID: 24559988 DOI: 10.1016/j.bpj.2014.01.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 12/02/2013] [Accepted: 01/07/2014] [Indexed: 01/03/2023] Open
Abstract
Muscle contraction is regulated by troponin-tropomyosin, which blocks and unblocks myosin binding sites on actin. To elucidate this regulatory mechanism, the three-dimensional organization of troponin and tropomyosin on the thin filament must be determined. Although tropomyosin is well defined in electron microscopy helical reconstructions of thin filaments, troponin density is mostly lost. Here, we determined troponin organization on native relaxed cardiac muscle thin filaments by applying single particle reconstruction procedures to negatively stained specimens. Multiple reference models led to the same final structure, indicating absence of model bias in the procedure. The new reconstructions clearly showed F-actin, tropomyosin, and troponin densities. At the 25 Å resolution achieved, troponin was considerably better defined than in previous reconstructions. The troponin density closely resembled the shape of troponin crystallographic structures, facilitating detailed interpretation of the electron microscopy density map. The orientation of troponin-T and the troponin core domain established troponin polarity. Density attributable to the troponin-I mobile regulatory domain was positioned where it could hold tropomyosin in its blocking position on actin, thus suggesting the underlying structural basis of thin filament regulation. Our previous understanding of thin filament regulation had been limited to known movements of tropomyosin that sterically block and unblock myosin binding sites on actin. We now show how troponin, the Ca(2+) sensor, may control these movements, ultimately determining whether muscle contracts or relaxes.
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Affiliation(s)
- Shixin Yang
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | | | - Marek Orzechowski
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts
| | - Roger Craig
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - John Trinick
- School of Molecular and Cellular Biology, University of Leeds, Leeds, United Kingdom
| | - Howard White
- Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, Virginia
| | - William Lehman
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts.
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Lymperopoulos A, Garcia D, Walklett K. Pharmacogenetics of cardiac inotropy. Pharmacogenomics 2014; 15:1807-1821. [PMID: 25493572 DOI: 10.2217/pgs.14.120] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The ability to stimulate cardiac contractility is known as positive inotropy. Endogenous hormones, such as adrenaline and several natural or synthetic compounds possess this biological property, which is invaluable in the modern cardiovascular therapy setting, especially in acute heart failure or in cardiogenic shock. A number of proteins inside the cardiac myocyte participate in the molecular pathways that translate the initial stimulus, that is, the hormone or drug, into the effect of increased contractility (positive inotropy). Genetic variations (polymorphisms) in several genes encoding these proteins have been identified and characterized in humans with potentially significant consequences on cardiac inotropic function. The present review discusses these polymorphisms and their effects on cardiac inotropy, along with the individual pharmacogenomics of the most important positive inotropic agents in clinical use today. Important areas for future investigations in the field are also highlighted.
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Affiliation(s)
- Anastasios Lymperopoulos
- From the Laboratory for the Study of Neurohormonal Control of the Circulation, Department of Pharmaceutical Sciences, Nova Southeastern University College of Pharmacy, 3200 S. University Drive, HPD (Terry) Bldg/Room 1338, Ft. Lauderdale, FL 33328-2018, USA
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42
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Cheng Y, Lindert S, Kekenes-Huskey P, Rao VS, Solaro RJ, Rosevear PR, Amaro R, McCulloch AD, McCammon JA, Regnier M. Computational studies of the effect of the S23D/S24D troponin I mutation on cardiac troponin structural dynamics. Biophys J 2014; 107:1675-85. [PMID: 25296321 PMCID: PMC4190606 DOI: 10.1016/j.bpj.2014.08.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 07/25/2014] [Accepted: 08/11/2014] [Indexed: 11/27/2022] Open
Abstract
During β-adrenergic stimulation, cardiac troponin I (cTnI) is phosphorylated by protein kinase A (PKA) at sites S23/S24, located at the N-terminus of cTnI. This phosphorylation has been shown to decrease KCa and pCa50, and weaken the cTnC-cTnI (C-I) interaction. We recently reported that phosphorylation results in an increase in the rate of early, slow phase of relaxation (kREL,slow) and a decrease in its duration (tREL,slow), which speeds up the overall relaxation. However, as the N-terminus of cTnI (residues 1-40) has not been resolved in the whole cardiac troponin (cTn) structure, little is known about the molecular-level behavior within the whole cTn complex upon phosphorylation of the S23/S24 residues of cTnI that results in these changes in function. In this study, we built up the cTn complex structure (including residues cTnC 1-161, cTnI 1-172, and cTnT 236-285) with the N-terminus of cTnI. We performed molecular-dynamics (MD) simulations to elucidate the structural basis of PKA phosphorylation-induced changes in cTn structure and Ca(2+) binding. We found that introducing two phosphomimic mutations into sites S23/S24 had no significant effect on the coordinating residues of Ca(2+) binding site II. However, the overall fluctuation of cTn was increased and the C-I interaction was altered relative to the wild-type model. The most significant changes involved interactions with the N-terminus of cTnI. Interestingly, the phosphomimic mutations led to the formation of intrasubunit interactions between the N-terminus and the inhibitory peptide of cTnI. This may result in altered interactions with cTnC and could explain the increased rate and decreased duration of slow-phase relaxation seen in myofibrils.
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Affiliation(s)
- Yuanhua Cheng
- Department of Bioengineering, University of Washington, Seattle, Washington; National Biomedical Computational Resource, University of California, San Diego, La Jolla, California
| | - Steffen Lindert
- National Biomedical Computational Resource, University of California, San Diego, La Jolla, California; Department of Pharmacology, University of California, San Diego, La Jolla, California
| | - Peter Kekenes-Huskey
- National Biomedical Computational Resource, University of California, San Diego, La Jolla, California; Department of Pharmacology, University of California, San Diego, La Jolla, California
| | - Vijay S Rao
- Department of Bioengineering, University of Washington, Seattle, Washington
| | - R John Solaro
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, Illinois
| | - Paul R Rosevear
- Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati, Cincinnati, Ohio
| | - Rommie Amaro
- National Biomedical Computational Resource, University of California, San Diego, La Jolla, California
| | - Andrew D McCulloch
- National Biomedical Computational Resource, University of California, San Diego, La Jolla, California; Department of Bioengineering, University of California, San Diego, La Jolla, California
| | - J Andrew McCammon
- National Biomedical Computational Resource, University of California, San Diego, La Jolla, California; Department of Pharmacology, University of California, San Diego, La Jolla, California
| | - Michael Regnier
- Department of Bioengineering, University of Washington, Seattle, Washington.
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43
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Messer AE, Marston SB. Investigating the role of uncoupling of troponin I phosphorylation from changes in myofibrillar Ca(2+)-sensitivity in the pathogenesis of cardiomyopathy. Front Physiol 2014; 5:315. [PMID: 25202278 PMCID: PMC4142463 DOI: 10.3389/fphys.2014.00315] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 08/02/2014] [Indexed: 12/12/2022] Open
Abstract
Contraction in the mammalian heart is controlled by the intracellular Ca(2+) concentration as it is in all striated muscle, but the heart has an additional signaling system that comes into play to increase heart rate and cardiac output during exercise or stress. β-adrenergic stimulation of heart muscle cells leads to release of cyclic-AMP and the activation of protein kinase A which phosphorylates key proteins in the sarcolemma, sarcoplasmic reticulum and contractile apparatus. Troponin I (TnI) and Myosin Binding Protein C (MyBP-C) are the prime targets in the myofilaments. TnI phosphorylation lowers myofibrillar Ca(2+)-sensitivity and increases the speed of Ca(2+)-dissociation and relaxation (lusitropic effect). Recent studies have shown that this relationship between Ca(2+)-sensitivity and TnI phosphorylation may be unstable. In familial cardiomyopathies, both dilated and hypertrophic (DCM and HCM), a mutation in one of the proteins of the thin filament often results in the loss of the relationship (uncoupling) and blunting of the lusitropic response. For familial dilated cardiomyopathy in thin filament proteins it has been proposed that this uncoupling is causative of the phenotype. Uncoupling has also been found in human heart tissue from patients with hypertrophic obstructive cardiomyopathy as a secondary effect. Recently, it has been found that Ca(2+)-sensitizing drugs can promote uncoupling, whilst one Ca(2+)-desensitizing drug Epigallocatechin 3-Gallate (EGCG) can reverse uncoupling. We will discuss recent findings about the role of uncoupling in the development of cardiomyopathies and the molecular mechanism of the process.
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Affiliation(s)
- Andrew E. Messer
- National Heart & Lung Institute, Imperial College LondonLondon, UK
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44
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Iribe G, Kaneko T, Yamaguchi Y, Naruse K. Load dependency in force–length relations in isolated single cardiomyocytes. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:103-14. [DOI: 10.1016/j.pbiomolbio.2014.06.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 06/17/2014] [Indexed: 10/25/2022]
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45
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Ying P, Serife AG, Deyang Y, Ying G. Top-down mass spectrometry of cardiac myofilament proteins in health and disease. Proteomics Clin Appl 2014; 8:554-68. [PMID: 24945106 PMCID: PMC4231170 DOI: 10.1002/prca.201400043] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 05/21/2014] [Accepted: 06/12/2014] [Indexed: 12/29/2022]
Abstract
Myofilaments are composed of thin and thick filaments that coordinate with each other to regulate muscle contraction and relaxation. PTMs together with genetic variations and alternative splicing of the myofilament proteins play essential roles in regulating cardiac contractility in health and disease. Therefore, a comprehensive characterization of the myofilament proteins in physiological and pathological conditions is essential for better understanding the molecular basis of cardiac function and dysfunction. Due to the vast complexity and dynamic nature of proteins, it is challenging to obtain a holistic view of myofilament protein modifications. In recent years, top-down MS has emerged as a powerful approach to study isoform composition and PTMs of proteins owing to its advantage of complete sequence coverage and its ability to identify PTMs and sequence variants without a priori knowledge. In this review, we will discuss the application of top-down MS to the study of cardiac myofilaments and highlight the insights it provides into the understanding of molecular mechanisms in contractile dysfunction of heart failure. Particularly, recent results of cardiac troponin and tropomyosin modifications will be elaborated. The limitations and perspectives on the use of top-down MS for myofilament protein characterization will also be briefly discussed.
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Affiliation(s)
- Peng Ying
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Ayaz-Guner Serife
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
| | - Yu Deyang
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
- Molecular and Environmental Toxicology Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Ge Ying
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
- Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, USA
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46
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Wijnker PJM, Sequeira V, Witjas-Paalberends ER, Foster DB, dos Remedios CG, Murphy AM, Stienen GJM, van der Velden J. Phosphorylation of protein kinase C sites Ser42/44 decreases Ca(2+)-sensitivity and blunts enhanced length-dependent activation in response to protein kinase A in human cardiomyocytes. Arch Biochem Biophys 2014; 554:11-21. [PMID: 24814372 PMCID: PMC4121669 DOI: 10.1016/j.abb.2014.04.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 04/29/2014] [Accepted: 04/29/2014] [Indexed: 10/25/2022]
Abstract
Protein kinase C (PKC)-mediated phosphorylation of troponin I (cTnI) at Ser42/44 is increased in heart failure. While studies in rodents demonstrated that PKC-mediated Ser42/44 phosphorylation decreases maximal force and ATPase activity, PKC incubation of human cardiomyocytes did not affect maximal force. We investigated whether Ser42/44 pseudo-phosphorylation affects force development and ATPase activity using troponin exchange in human myocardium. Additionally, we studied if pseudo-phosphorylated Ser42/44 modulates length-dependent activation of force, which is regulated by protein kinase A (PKA)-mediated cTnI-Ser23/24 phosphorylation. Isometric force was measured in membrane-permeabilized cardiomyocytes exchanged with human recombinant wild-type troponin or troponin mutated at Ser42/44 or Ser23/24 into aspartic acid (D) or alanine (A) to mimic phosphorylation and dephosphorylation, respectively. In troponin-exchanged donor cardiomyocytes experiments were repeated after PKA incubation. ATPase activity was measured in troponin-exchanged cardiac muscle strips. Compared to wild-type, 42D/44D decreased Ca(2+)-sensitivity without affecting maximal force in failing and donor cardiomyocytes. In donor myocardium, 42D/44D did not affect maximal ATPase activity or tension cost. Interestingly, 42D/44D blunted the length-dependent increase in Ca(2+)-sensitivity induced upon PKA-mediated phosphorylation. Since the drop in Ca(2+)-sensitivity at physiological Ca(2+)-concentrations is relatively large phosphorylation of Ser42/44 may result in a decrease of force and associated ATP utilization in the human heart.
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Affiliation(s)
- Paul J M Wijnker
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands; Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | - Vasco Sequeira
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands.
| | - E Rosalie Witjas-Paalberends
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands.
| | - D Brian Foster
- Department of Pediatrics/Division of Cardiology, Johns Hopkins University School of Medicine, Ross Bldg 1144/720 Rutland Avenue, Baltimore, MD 21205, USA.
| | | | - Anne M Murphy
- Department of Pediatrics/Division of Cardiology, Johns Hopkins University School of Medicine, Ross Bldg 1144/720 Rutland Avenue, Baltimore, MD 21205, USA.
| | - Ger J M Stienen
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands; Department of Physics and Astronomy, VU University, Amsterdam, The Netherlands.
| | - Jolanda van der Velden
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands; ICIN-Netherlands Heart Institute, Utrecht, The Netherlands.
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47
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Rain S, Bos DDSG, Handoko ML, Westerhof N, Stienen G, Ottenheijm C, Goebel M, Dorfmüller P, Guignabert C, Humbert M, Bogaard HJ, Remedios CD, Saripalli C, Hidalgo CG, Granzier HL, Vonk-Noordegraaf A, van der Velden J, de Man FS. Protein changes contributing to right ventricular cardiomyocyte diastolic dysfunction in pulmonary arterial hypertension. J Am Heart Assoc 2014; 3:e000716. [PMID: 24895160 PMCID: PMC4309054 DOI: 10.1161/jaha.113.000716] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Background Right ventricular (RV) diastolic function is impaired in patients with pulmonary arterial hypertension (PAH). Our previous study showed that elevated cardiomyocyte stiffness and myofilament Ca2+ sensitivity underlie diastolic dysfunction in PAH. This study investigates protein modifications contributing to cellular diastolic dysfunction in PAH. Methods and Results RV samples from PAH patients undergoing heart‐lung transplantation were compared to non‐failing donors (Don). Titin stiffness contribution to RV diastolic dysfunction was determined by Western‐blot analyses using antibodies to protein‐kinase‐A (PKA), Cα (PKCα) and Ca2+/calmoduling‐dependent‐kinase (CamKIIδ) titin and phospholamban (PLN) phosphorylation sites: N2B (Ser469), PEVK (Ser170 and Ser26), and PLN (Thr17), respectively. PKA and PKCα sites were significantly less phosphorylated in PAH compared with donors (P<0.0001). To test the functional relevance of PKA‐, PKCα‐, and CamKIIδ‐mediated titin phosphorylation, we measured the stiffness of single RV cardiomyocytes before and after kinase incubation. PKA significantly decreased PAH RV cardiomyocyte diastolic stiffness, PKCα further increased stiffness while CamKIIδ had no major effect. CamKIIδ activation was determined indirectly by measuring PLN Thr17phosphorylation level. No significant changes were found between the groups. Myofilament Ca2+ sensitivity is mediated by sarcomeric troponin I (cTnI) phosphorylation. We observed increased unphosphorylated cTnI in PAH compared with donors (P<0.05) and reduced PKA‐mediated cTnI phosphorylation (Ser22/23) (P<0.001). Finally, alterations in Ca2+‐handling proteins contribute to RV diastolic dysfunction due to insufficient diastolic Ca2+ clearance. PAH SERCA2a levels and PLN phosphorylation were significantly reduced compared with donors (P<0.05). Conclusions Increased titin stiffness, reduced cTnI phosphorylation, and altered levels of phosphorylation of Ca2+ handling proteins contribute to RV diastolic dysfunction in PAH.
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Affiliation(s)
- Silvia Rain
- Department of Pulmonology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., D.S.G.B., N.W., H.J.B., A.V.N., F.S.M.) Department of Physiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., L.H., N.W., G.S., C.O., M.G., J.V., F.S.M.)
| | - Denielli da Silva Goncalves Bos
- Department of Pulmonology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., D.S.G.B., N.W., H.J.B., A.V.N., F.S.M.)
| | - M Louis Handoko
- Department of Physiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., L.H., N.W., G.S., C.O., M.G., J.V., F.S.M.) Department of Cardiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (L.H.)
| | - Nico Westerhof
- Department of Pulmonology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., D.S.G.B., N.W., H.J.B., A.V.N., F.S.M.) Department of Physiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., L.H., N.W., G.S., C.O., M.G., J.V., F.S.M.)
| | - Ger Stienen
- Department of Physiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., L.H., N.W., G.S., C.O., M.G., J.V., F.S.M.) Department of Physics and Astronomy, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (G.S.)
| | - Coen Ottenheijm
- Department of Physiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., L.H., N.W., G.S., C.O., M.G., J.V., F.S.M.)
| | - Max Goebel
- Department of Physiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., L.H., N.W., G.S., C.O., M.G., J.V., F.S.M.)
| | - Peter Dorfmüller
- Faculté de Médecine, Université Paris-Sud, Le Kremlin-Bicêtre, France (P.D., C.G., M.H.) Inserm U999, LabEx LERMIT, Centre Chirurgical Marie Lannelongue, Le Plessis Robinson, France (P.D., C.G., M.H.)
| | - Christophe Guignabert
- Faculté de Médecine, Université Paris-Sud, Le Kremlin-Bicêtre, France (P.D., C.G., M.H.) Inserm U999, LabEx LERMIT, Centre Chirurgical Marie Lannelongue, Le Plessis Robinson, France (P.D., C.G., M.H.)
| | - Marc Humbert
- Faculté de Médecine, Université Paris-Sud, Le Kremlin-Bicêtre, France (P.D., C.G., M.H.) Inserm U999, LabEx LERMIT, Centre Chirurgical Marie Lannelongue, Le Plessis Robinson, France (P.D., C.G., M.H.) Service d'Anatomie Pathologique, Centre Chirurgical Marie Lannelongue, Le Plessis Robinson, France (M.H.) Assistance Publique-Hôspitaux de Paris, Service de Pneumologie, Département Hôspital Universitaire, Thorax innovation, (DHU-TORINO), Hôpital Bicêtre, France (M.H.)
| | - Harm-Jan Bogaard
- Department of Pulmonology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., D.S.G.B., N.W., H.J.B., A.V.N., F.S.M.)
| | - Cris Dos Remedios
- Muscle Research Unit, Discipline of Anatomy & Histology, Bosch Institute, The University of Sydney, Sydney, Australia (C.R.)
| | - Chandra Saripalli
- Sarver Molecular Cardiovascular Research Program, Department of Physiology, University of Arizona, Tucson, AZ, The Netherlands (C.S., C.G.H., H.L.G.)
| | - Carlos G Hidalgo
- Sarver Molecular Cardiovascular Research Program, Department of Physiology, University of Arizona, Tucson, AZ, The Netherlands (C.S., C.G.H., H.L.G.)
| | - Henk L Granzier
- Sarver Molecular Cardiovascular Research Program, Department of Physiology, University of Arizona, Tucson, AZ, The Netherlands (C.S., C.G.H., H.L.G.)
| | - Anton Vonk-Noordegraaf
- Department of Pulmonology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., D.S.G.B., N.W., H.J.B., A.V.N., F.S.M.)
| | - Jolanda van der Velden
- Department of Physiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., L.H., N.W., G.S., C.O., M.G., J.V., F.S.M.) ICIN - The Netherlands Heart Institute, Amsterdam, The Netherlands (J.V.)
| | - Frances S de Man
- Department of Pulmonology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., D.S.G.B., N.W., H.J.B., A.V.N., F.S.M.) Department of Physiology, VU University Medical Center/Institute for Cardiovascular Research, Amsterdam, The Netherlands (S.R., L.H., N.W., G.S., C.O., M.G., J.V., F.S.M.)
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48
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Restrictive cardiomyopathy mutations demonstrate functions of the C-terminal end-segment of troponin I. Arch Biochem Biophys 2014; 552-553:3-10. [DOI: 10.1016/j.abb.2013.12.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 11/11/2013] [Accepted: 12/03/2013] [Indexed: 11/22/2022]
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49
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Sheng JJ, Jin JP. Gene regulation, alternative splicing, and posttranslational modification of troponin subunits in cardiac development and adaptation: a focused review. Front Physiol 2014; 5:165. [PMID: 24817852 PMCID: PMC4012202 DOI: 10.3389/fphys.2014.00165] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 04/10/2014] [Indexed: 12/19/2022] Open
Abstract
Troponin plays a central role in regulating the contraction and relaxation of vertebrate striated muscles. This review focuses on the isoform gene regulation, alternative RNA splicing, and posttranslational modifications of troponin subunits in cardiac development and adaptation. Transcriptional and posttranscriptional regulations such as phosphorylation and proteolysis modifications, and structure-function relationships of troponin subunit proteins are summarized. The physiological and pathophysiological significances are discussed for impacts on cardiac muscle contractility, heart function, and adaptations in health and diseases.
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Affiliation(s)
- Juan-Juan Sheng
- Department of Physiology, Wayne State University School of Medicine Detroit, MI, USA
| | - Jian-Ping Jin
- Department of Physiology, Wayne State University School of Medicine Detroit, MI, USA
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50
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Kalyva A, Parthenakis FI, Marketou ME, Kontaraki JE, Vardas PE. Biochemical characterisation of Troponin C mutations causing hypertrophic and dilated cardiomyopathies. J Muscle Res Cell Motil 2014; 35:161-78. [PMID: 24744096 DOI: 10.1007/s10974-014-9382-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 04/02/2014] [Indexed: 01/27/2023]
Abstract
Cardiac muscle contraction occurs through an interaction of the myosin head with the actin filaments, a process which is regulated by the troponin complex together with tropomyosin and is Ca(2+) dependent. Mutations in genes encoding sarcomeric proteins are a common cause of familial hypertrophic and dilated cardiomyopathies. The scope of this review is to gather information from studies regarding the in vitro characterisation of six HCM and six DCM mutations on the cardiac TnC gene and to suggest, if possible, how they may lead to dysfunction. Since TnC is the subunit responsible for Ca(2+) binding, mutations in the TnC could possibly have a strong impact on Ca(2+) binding affinities. Furthermore, the interactions of mutant TnCs with their binding partners could be altered. From the characterisation studies available to date, we can conclude that the HCM mutations on TnC increase significantly the Ca(2+) sensitivity of force development or of ATPase activity, producing large pCa shifts in comparison to WT TnC. In contrast, the DCM mutations on TnC have a tendency to decrease the Ca(2+) sensitivity of force development or of ATPase activity in comparison to WT TnC. Furthermore, the DCM mutants of TnC are not responsive to the TnI phosphorylation signal resulting in filaments that preserve their Ca(2+) sensitivity in contrast to WT filaments that experience a decrease in Ca(2+) sensitivity upon TnI phosphorylation.
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Affiliation(s)
- Athanasia Kalyva
- Molecular Cardiology Laboratory, Department of Cardiology, School of Medicine, University of Crete, Crete, Greece,
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