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Salyer LG, Salhi HE, Brundage EA, Shettigar V, Sturgill SL, Zanella H, Templeton B, Abay E, Emmer KM, Lowe J, Rafael-Fortney JA, Parinandi N, Foster DB, McKinsey TA, Woulfe KC, Ziolo MT, Biesiadecki BJ. Troponin I Tyrosine Phosphorylation Beneficially Accelerates Diastolic Function. Circ Res 2024; 134:33-45. [PMID: 38095088 PMCID: PMC10872382 DOI: 10.1161/circresaha.123.323132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 11/28/2023] [Indexed: 01/06/2024]
Abstract
BACKGROUND A healthy heart is able to modify its function and increase relaxation through post-translational modifications of myofilament proteins. While there are known examples of serine/threonine kinases directly phosphorylating myofilament proteins to modify heart function, the roles of tyrosine (Y) phosphorylation to directly modify heart function have not been demonstrated. The myofilament protein TnI (troponin I) is the inhibitory subunit of the troponin complex and is a key regulator of cardiac contraction and relaxation. We previously demonstrated that TnI-Y26 phosphorylation decreases calcium-sensitive force development and accelerates calcium dissociation, suggesting a novel role for tyrosine kinase-mediated TnI-Y26 phosphorylation to regulate cardiac relaxation. Therefore, we hypothesize that increasing TnI-Y26 phosphorylation will increase cardiac relaxation in vivo and be beneficial during pathological diastolic dysfunction. METHODS The signaling pathway involved in TnI-Y26 phosphorylation was predicted in silico and validated by tyrosine kinase activation and inhibition in primary adult murine cardiomyocytes. To investigate how TnI-Y26 phosphorylation affects cardiac muscle, structure, and function in vivo, we developed a novel TnI-Y26 phosphorylation-mimetic mouse that was subjected to echocardiography, pressure-volume loop hemodynamics, and myofibril mechanical studies. TnI-Y26 phosphorylation-mimetic mice were further subjected to the nephrectomy/DOCA (deoxycorticosterone acetate) model of diastolic dysfunction to investigate the effects of increased TnI-Y26 phosphorylation in disease. RESULTS Src tyrosine kinase is sufficient to phosphorylate TnI-Y26 in cardiomyocytes. TnI-Y26 phosphorylation accelerates in vivo relaxation without detrimental structural or systolic impairment. In a mouse model of diastolic dysfunction, TnI-Y26 phosphorylation is beneficial and protects against the development of disease. CONCLUSIONS We have demonstrated that tyrosine kinase phosphorylation of TnI is a novel mechanism to directly and beneficially accelerate myocardial relaxation in vivo.
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Affiliation(s)
- Lorien G Salyer
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute (L.G.S., H.E.S., E.A.B., V.S., S.L.S., H.Z., B.T., E.A., J.L., J.A.R.-F., M.T.Z., B.J.B.), Ohio State University, Columbus
| | - Hussam E Salhi
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute (L.G.S., H.E.S., E.A.B., V.S., S.L.S., H.Z., B.T., E.A., J.L., J.A.R.-F., M.T.Z., B.J.B.), Ohio State University, Columbus
| | - Elizabeth A Brundage
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute (L.G.S., H.E.S., E.A.B., V.S., S.L.S., H.Z., B.T., E.A., J.L., J.A.R.-F., M.T.Z., B.J.B.), Ohio State University, Columbus
| | - Vikram Shettigar
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute (L.G.S., H.E.S., E.A.B., V.S., S.L.S., H.Z., B.T., E.A., J.L., J.A.R.-F., M.T.Z., B.J.B.), Ohio State University, Columbus
| | - Sarah L Sturgill
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute (L.G.S., H.E.S., E.A.B., V.S., S.L.S., H.Z., B.T., E.A., J.L., J.A.R.-F., M.T.Z., B.J.B.), Ohio State University, Columbus
| | - Helena Zanella
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute (L.G.S., H.E.S., E.A.B., V.S., S.L.S., H.Z., B.T., E.A., J.L., J.A.R.-F., M.T.Z., B.J.B.), Ohio State University, Columbus
| | - Benjamin Templeton
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute (L.G.S., H.E.S., E.A.B., V.S., S.L.S., H.Z., B.T., E.A., J.L., J.A.R.-F., M.T.Z., B.J.B.), Ohio State University, Columbus
| | - Eaman Abay
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute (L.G.S., H.E.S., E.A.B., V.S., S.L.S., H.Z., B.T., E.A., J.L., J.A.R.-F., M.T.Z., B.J.B.), Ohio State University, Columbus
| | - Kathryn M Emmer
- University Laboratory Animal Resources (K.M.E.), Ohio State University, Columbus
| | - Jeovanna Lowe
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute (L.G.S., H.E.S., E.A.B., V.S., S.L.S., H.Z., B.T., E.A., J.L., J.A.R.-F., M.T.Z., B.J.B.), Ohio State University, Columbus
| | - Jill A Rafael-Fortney
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute (L.G.S., H.E.S., E.A.B., V.S., S.L.S., H.Z., B.T., E.A., J.L., J.A.R.-F., M.T.Z., B.J.B.), Ohio State University, Columbus
| | - Narasimham Parinandi
- Division of Pulmonary, Critical Care and Sleep Medicine (N.P.), Ohio State University, Columbus
| | - D Brian Foster
- Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD (D.B.F.)
| | - Timothy A McKinsey
- Department of Medicine, Division of Cardiology (T.A.M., K.C.W.), University of Colorado Anschutz Medical Campus, Aurora
- Consortium for Fibrosis Research and Translation (T.A.M.), University of Colorado Anschutz Medical Campus, Aurora
| | - Kathleen C Woulfe
- Department of Medicine, Division of Cardiology (T.A.M., K.C.W.), University of Colorado Anschutz Medical Campus, Aurora
| | - Mark T Ziolo
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute (L.G.S., H.E.S., E.A.B., V.S., S.L.S., H.Z., B.T., E.A., J.L., J.A.R.-F., M.T.Z., B.J.B.), Ohio State University, Columbus
| | - Brandon J Biesiadecki
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute (L.G.S., H.E.S., E.A.B., V.S., S.L.S., H.Z., B.T., E.A., J.L., J.A.R.-F., M.T.Z., B.J.B.), Ohio State University, Columbus
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Salhi HE, Shettigar V, Salyer L, Sturgill S, Brundage EA, Robinett J, Xu Z, Abay E, Lowe J, Janssen PML, Rafael-Fortney JA, Weisleder N, Ziolo MT, Biesiadecki BJ. The lack of Troponin I Ser-23/24 phosphorylation is detrimental to in vivo cardiac function and exacerbates cardiac disease. J Mol Cell Cardiol 2023; 176:84-96. [PMID: 36724829 PMCID: PMC10074981 DOI: 10.1016/j.yjmcc.2023.01.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 01/11/2023] [Accepted: 01/24/2023] [Indexed: 01/30/2023]
Abstract
Troponin I (TnI) is a key regulator of cardiac contraction and relaxation with TnI Ser-23/24 phosphorylation serving as a myofilament mechanism to modulate cardiac function. Basal cardiac TnI Ser-23/24 phosphorylation is high such that both increased and decreased TnI phosphorylation may modulate cardiac function. While the effects of increasing TnI Ser-23/24 phosphorylation on heart function are well established, the effects of decreasing TnI Ser-23/24 phosphorylation are not clear. To understand the in vivo role of decreased TnI Ser-23/24 phosphorylation, mice expressing TnI with Ser-23/24 mutated to alanine (TnI S23/24A) that lack the ability to be phosphorylated at these residues were subjected to echocardiography and pressure-volume hemodynamic measurements in the absence or presence of physiological (pacing increasing heart rate or adrenergic stimulation) or pathological (transverse aortic constriction (TAC)) stress. In the absence of pathological stress, the lack of TnI Ser-23/24 phosphorylation impaired systolic and diastolic function. TnI S23/24A mice also had an impaired systolic and diastolic response upon stimulation increased heart rate and an impaired adrenergic response upon dobutamine infusion. Following pathological cardiac stress induced by TAC, TnI S23/24A mice had a greater increase in ventricular mass, worse diastolic function, and impaired systolic and diastolic function upon increasing heart rate. These findings demonstrate that mice lacking the ability to phosphorylate TnI at Ser-23/24 have impaired in vivo systolic and diastolic cardiac function, a blunted cardiac reserve and a worse response to pathological stress supporting decreased TnI Ser23/24 phosphorylation is a modulator of these processes in vivo.
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Affiliation(s)
- Hussam E Salhi
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Vikram Shettigar
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Lorien Salyer
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Sarah Sturgill
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Elizabeth A Brundage
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Joel Robinett
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Zhaobin Xu
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Eaman Abay
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Jeovanna Lowe
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Paul M L Janssen
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Jill A Rafael-Fortney
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Noah Weisleder
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Mark T Ziolo
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America
| | - Brandon J Biesiadecki
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States of America.
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3
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Sturgill SL, Salyer LG, Shettigar V, Brundage EA, Biesiadecki BJ, Ziolo MT. Troponin I phosphorylation is essential for cardiac reserve. J Gen Physiol 2022. [PMID: 34767005 DOI: 10.1085/2021ecc31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
With an increase in the body's metabolic demand (e.g., exercise), the heart must increase its pumping performance. To achieve this increased performance, the heart relies on its cardiac reserve, which is the ability to increase its systolic and diastolic function. The mechanism responsible for cardiac reserve is poorly understood. The myofilaments are essential for contraction/relaxation, with troponin I (the inhibitory subunit of troponin, TnI) being a key regulatory protein. Studies have shown that TnI serine 23/24 (S23/S24) phosphorylation is a key mechanism for accelerating relaxation by decreasing Ca2+ sensitivity. However, the role of TnI in cardiac reserve is unknown. For this study, we characterized the systolic and diastolic reserve in TnI S23/S24 phosphorylation-null transgenic mice (S23/S24 mutated to alanine [AA] mice). Even with increased Ca2+ sensitivity, the AA mice exhibited normal function at resting heart rate with no difference in cardiac structure compared with wild type. To examine the role TnI S23/S24 phosphorylation in systolic and diastolic reserve, we assessed hemodynamics via left ventricular catheterization on the Bowditch effect (i.e., an increase in contractile function with increasing heart rate) by increasing heart rate (from 240 to 420 beats per minute) and sympathetic stimulation (dobutamine). Our data exhibited a clear loss of diastolic and systolic reserve in the AA mice with increasing heart rate and dobutamine. Since we observed a clear inability to increase systolic and diastolic function in AA mice, we performed speckle tracking echocardiography to quantitatively characterize function at resting heart rate. We observed that AA mice demonstrated normal systolic function (radial strain rate) and impaired directional diastolic function (reverse radial strain rate) at resting heart rate. We conclude that TnI S23/S24 phosphorylation is essential for cardiac reserve by enhancing systolic and diastolic function. A blunted cardiac reserve leads to heart disease making TnI S23/S24 phosphorylation a potential therapeutic strategy.
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Affiliation(s)
- Sarah L Sturgill
- Dorothy M. Davis Heart and Lung Research Institute, Physiology and Cell Biology Department, Wexner Medical Center, The Ohio State University, Columbus, OH
| | - Lorien G Salyer
- Dorothy M. Davis Heart and Lung Research Institute, Physiology and Cell Biology Department, Wexner Medical Center, The Ohio State University, Columbus, OH
| | - Vikram Shettigar
- Dorothy M. Davis Heart and Lung Research Institute, Physiology and Cell Biology Department, Wexner Medical Center, The Ohio State University, Columbus, OH
| | - Elizabeth A Brundage
- Dorothy M. Davis Heart and Lung Research Institute, Physiology and Cell Biology Department, Wexner Medical Center, The Ohio State University, Columbus, OH
| | - Brandon J Biesiadecki
- Dorothy M. Davis Heart and Lung Research Institute, Physiology and Cell Biology Department, Wexner Medical Center, The Ohio State University, Columbus, OH
| | - Mark T Ziolo
- Dorothy M. Davis Heart and Lung Research Institute, Physiology and Cell Biology Department, Wexner Medical Center, The Ohio State University, Columbus, OH
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Landim-Vieira M, Childers MC, Wacker AL, Garcia MR, He H, Singh R, Brundage EA, Johnston JR, Whitson BA, Chase PB, Janssen PML, Regnier M, Biesiadecki BJ, Pinto JR, Parvatiyar MS. Post-translational modification patterns on β-myosin heavy chain are altered in ischemic and nonischemic human hearts. eLife 2022; 11:74919. [PMID: 35502901 PMCID: PMC9122498 DOI: 10.7554/elife.74919] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Accepted: 05/01/2022] [Indexed: 11/13/2022] Open
Abstract
Phosphorylation and acetylation of sarcomeric proteins are important for fine-tuning myocardial contractility. Here, we used bottom-up proteomics and label-free quantification to identify novel post-translational modifications (PTMs) on β-myosin heavy chain (β-MHC) in normal and failing human heart tissues. We report six acetylated lysines and two phosphorylated residues: K34-Ac, K58-Ac, S210-P, K213-Ac, T215-P, K429-Ac, K951-Ac, and K1195-Ac. K951-Ac was significantly reduced in both ischemic and nonischemic failing hearts compared to nondiseased hearts. Molecular dynamics (MD) simulations show that K951-Ac may impact stability of thick filament tail interactions and ultimately myosin head positioning. K58-Ac altered the solvent-exposed SH3 domain surface - known for protein-protein interactions - but did not appreciably change motor domain conformation or dynamics under conditions studied. Together, K213-Ac/T215-P altered loop 1's structure and dynamics - known to regulate ADP-release, ATPase activity, and sliding velocity. Our study suggests that β-MHC acetylation levels may be influenced more by the PTM location than the type of heart disease since less protected acetylation sites are reduced in both heart failure groups. Additionally, these PTMs have potential to modulate interactions between β-MHC and other regulatory sarcomeric proteins, ADP-release rate of myosin, flexibility of the S2 region, and cardiac myofilament contractility in normal and failing hearts.
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Affiliation(s)
- Maicon Landim-Vieira
- Department of Biomedical Sciences, College of Medicine, The Florida State UniversityTallahasseeUnited States
| | - Matthew C Childers
- Department of Bioengineering, College of Medicine, University of WashingtonSeattleUnited States
| | - Amanda L Wacker
- Department of Nutrition and Integrative Physiology, The Florida State UniversityTallahasseeUnited States
| | - Michelle Rodriquez Garcia
- Department of Biomedical Sciences, College of Medicine, The Florida State UniversityTallahasseeUnited States
| | - Huan He
- Department of Biomedical Sciences, College of Medicine, The Florida State UniversityTallahasseeUnited States,Translational Science Laboratory, College of Medicine, The Florida State UniversityTallahasseeUnited States
| | - Rakesh Singh
- Department of Biomedical Sciences, College of Medicine, The Florida State UniversityTallahasseeUnited States,Translational Science Laboratory, College of Medicine, The Florida State UniversityTallahasseeUnited States
| | - Elizabeth A Brundage
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State UniversityColumbusUnited States
| | - Jamie R Johnston
- Department of Biomedical Sciences, College of Medicine, The Florida State UniversityTallahasseeUnited States
| | - Bryan A Whitson
- Department of Surgery, College of Medicine, The Ohio State UniversityColumbusUnited States
| | - P Bryant Chase
- Department of Biological Science, The Florida State UniversityTallahasseeUnited States
| | - Paul ML Janssen
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State UniversityColumbusUnited States
| | - Michael Regnier
- Department of Bioengineering, College of Medicine, University of WashingtonSeattleUnited States
| | - Brandon J Biesiadecki
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State UniversityColumbusUnited States
| | - J Renato Pinto
- Department of Biomedical Sciences, College of Medicine, The Florida State UniversityTallahasseeUnited States
| | - Michelle S Parvatiyar
- Department of Nutrition and Integrative Physiology, The Florida State UniversityTallahasseeUnited States
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Landim-Vieira M, Childers MC, Wacker AL, Rodriguez Garcia M, Singh RK, Brundage EA, Whitson BA, Janssen PM, Chase PB, Biesiadecki BJ, Regnier M, Pinto JR, Parvatiyar MS. Post-Translational Modifications in Human Beta Myosin Heavy Chain. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.2089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Blair CA, Brundage EA, Thompson KL, Stromberg A, Guglin M, Biesiadecki BJ, Campbell KS. Heart Failure in Humans Reduces Contractile Force in Myocardium From Both Ventricles. JACC Basic Transl Sci 2020; 5:786-798. [PMID: 32875169 PMCID: PMC7452203 DOI: 10.1016/j.jacbts.2020.05.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 05/18/2020] [Accepted: 05/18/2020] [Indexed: 01/01/2023]
Abstract
Contractile assays were performed using multicellular preparations isolated from the left and right ventricles of organ donors and patients with heart failure. Heart failure reduced maximum force and power by approximately 30% in the myocardium from both ventricles. Heart failure increased the Ca2+ sensitivity of contraction, but the effect was bigger in right ventricular tissue than in left ventricular samples. The changes in Ca2+ sensitivity may reflect ventricle-specific post-translational modifications to sarcomeric proteins.
This study measured how heart failure affects the contractile properties of the human myocardium from the left and right ventricles. The data showed that maximum force and maximum power were reduced by approximately 30% in multicellular preparations from both ventricles, possibly because of ventricular remodeling (e.g., cellular disarray and/or excess fibrosis). Heart failure increased the calcium (Ca2+) sensitivity of contraction in both ventricles, but the effect was bigger in right ventricular samples. The changes in Ca2+ sensitivity were associated with ventricle-specific changes in the phosphorylation of troponin I, which indicated that adrenergic stimulation might induce different effects in the left and right ventricles.
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Key Words
- Ca2+ sensitivity
- Ca2+, calcium
- Fact, maximum Ca2+-activated force
- Fpas, passive force
- LV, left ventricle
- MyBP-C, myosin binding protein-C
- PKA, protein kinase A
- Pmax, maximum power output
- RLC, regulatory light chain
- RV, right ventricle
- TnI, troponin I
- Vmax, maximum shortening velocity
- heart failure
- human myocardium
- ktr, rate of force recovery
- myofilament proteins
- nH, Hill coefficient
- ventricular function
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Affiliation(s)
- Cheavar A Blair
- Department of Physiology, University of Kentucky, Lexington, Kentucky
| | - Elizabeth A Brundage
- Department of Physiology and Cell Biology and The Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | | | - Arnold Stromberg
- Department of Statistics, University of Kentucky, Lexington, Kentucky
| | - Maya Guglin
- Division of Cardiovascular Medicine, University of Kentucky, Lexington, Kentucky
| | - Brandon J Biesiadecki
- Department of Physiology and Cell Biology and The Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Kenneth S Campbell
- Department of Physiology, University of Kentucky, Lexington, Kentucky.,Division of Cardiovascular Medicine, University of Kentucky, Lexington, Kentucky
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Wacker A, Rodriguez Garcia MC, Landim Vieira M, Singh RK, Brundage EA, Whitson BA, Janssen PM, Chase PB, Biesiadecki BJ, Parvatiyar MS, Pinto JRD. Reduced Beta Myosin Heavy Chain K213 Acetylation and T215 Phosphorylation in Human Heart Failure. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Brundage EA, Shettigar V, Lin YH, Agatisa-Boyle B, Jeong MY, Ziolo MT, Biesiadecki BJ. Abstract 900: Troponin I Tyrosine 26 Phosphorylation Accelerates i
n vivo
Myocardial Relaxation. Circ Res 2019. [DOI: 10.1161/res.125.suppl_1.900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Heart failure results in depressed cardiac systolic contraction and diastolic relaxation, both of which limit the heart’s ability to pump blood. Currently there is no therapy to accelerate the detrimental slowed relaxation in heart failure. A fundamental mechanism of the heart to modulate cardiac relaxation is through serine/threonine kinase-mediated phosphorylation of the contractile regulatory protein troponin I (TnI). Non-receptor tyrosine-specific kinases are expressed in the heart and their activity is altered in disease; yet, the role of tyrosine kinase-mediated phosphorylation to directly modulate cardiac relaxation has not been described. TnI is phosphorylated at tyrosine 26 (Tyr26) in the heart and we previously demonstrated TnI Tyr26 phosphorylation accelerates myofilament deactivation. TnI Tyr26 phosphorylation is therefore the first tyrosine phosphorylation identified to directly modulate cardiac myofilament function, however the effects of tyrosine phosphorylation on in vivo function of the heart are unknown. To determine the effect of tyrosine phosphorylation on heart function, we generated a TnI Tyr26 phosphorylation (Tg Y26E) mouse. At the muscle level, myofibrils from Tg Y26E mice exhibit accelerated myofibril relaxation. Echocardiography and pressure-volume hemodynamic measurements demonstrate Tg Y26E mice have enhanced diastolic function evident in accelerated myocardial relaxation, without depressed systolic function or altered morphology. As a whole these data support the phosphorylation of TnI at Tyr26 as a novel tyrosine signaling mechanism to accelerate in vivo diastolic function without depressing systolic contraction.
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Brundage EA, Shettigar V, Lin YH, Agatisa-Boyle B, Jeong M, Ziolo MT, Biesiadecki BJ. Troponin I Tyrosine Phosphorylation: Novel Regulator of Cardiac Function. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.646] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Brundage EA, Agatisa-Boyle B, Shettigar V, Jeong MY, Salhi HE, Chung JH, Qian Z, Janssen PM, Pei D, Davis JP, Ziolo MT, Biesiadecki BJ. Abstract 437: Tyrosine Phosphorylation: Regulator of Cardiac Contraction. Circ Res 2018. [DOI: 10.1161/res.123.suppl_1.437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Myocardial contractile function is depressed in heart failure. Contractile function of the normal and failing heart is in part determined by kinase mediated serine/threonine phosphorylation. While non-receptor tyrosine specific kinases are expressed in the heart and their activity is increased in disease, the role of tyrosine kinase signaling to modulate cardiac contraction is unknown. Previous work demonstrated the cardiac contractile regulatory protein troponin I (TnI) is phosphorylated at tyrosine 26 (Tyr26). Subsequently, we demonstrated TnI Tyr26 phosphorylation alters myofilament function thereby identifying the first tyrosine phosphorylation to directly modulate cardiac contraction. The role of TnI Tyr26 phosphorylation in the normal or diseased heart and the signaling pathways responsible for its phosphorylation are unknown. To identify the kinase responsible for TnI Tyr26 phosphorylation and its effect on in vivo heart function, we generated a novel tyrosine kinase activator and a TnI Tyr26 phosphorylation (Tg Y26E) mouse. Biochemical kinase assays and kinase activation in ventricular myocytes identify Src family kinases as sufficient to induce TnI Tyr26 phosphorylation. Tg Y26E mice exhibit decreased myofilament calcium sensitivity and accelerated relaxation. Finally, we demonstrate TnI Tyr26 phosphorylation is increased during in vivo myocardial ischemia when Src family tyrosine kinases are also activated. Together these data support targeting Src family tyrosine kinase and TnI Tyr26 phosphorylation to improve heart function in myocardial ischemia and the failing heart.
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Brundage EA, Agatisa-Boyle B, Shettigar V, Chung JH, Qian Z, Salhi HE, Janssen PM, Pei D, Davis JP, Ziolo MT, Biesiadecki BJ. Abstract 223: Troponin I Tyrosine Phosphorylation Modulation of Cardiac Function. Circ Res 2017. [DOI: 10.1161/res.121.suppl_1.223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Heart failure results in depressed contraction and slowed relaxation, both of which limit heart function and contribute to the progression of heart disease. Currently there is no chronic therapy to accelerate relaxation and reverse the diastolic dysfunction present in heart failure. Myocardial relaxation is regulated by serine/threonine phosphorylation of key regulatory proteins. Tyrosine (Tyr) specific kinases are expressed in the heart but the Tyr phosphorylation of regulatory proteins to modulate heart function has not been demonstrated. To investigate the effects of Tyr kinase phosphorylation on cardiac contraction we employed a novel cell penetrating peptide to deliver a direct Tyr kinase activator into isolated adult myocytes. Results demonstrate Tyr kinases activation increases Tyr phosphorylation of the regulatory protein troponin I (TnI) at Tyr26. We have demonstrated that TnI Tyr26 phosphorylation is beneficial to cardiac health by decreasing calcium sensitivity and accelerating myofilament deactivation (key determinants in accelerating myocardial relaxation) and that TnI Tyr26 phosphorylation undergoes functional integration with TnI Ser23/24 resulting in further accelerated calcium dissociation (accelerated relaxation) without further decreased calcium sensitivity (no further depression of contraction). We now demonstrate TnI Tyr26 also undergoes novel signaling integration with TnI Ser23/24 phosphorylation increasing the rate of Tyr kinase mediated Tyr26 phosphorylation. For the first time we demonstrate tyrosine kinase phosphorylation of TnI at Tyr26 modulates cardiac function resulting in accelerated relaxation. Increasing TnI Tyr26 phosphorylation may therefore serve as a novel targeted mechanism for future therapeutic development to accelerate depressed myocardial relaxation and improve diastolic dysfunction in heart failure.
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Brundage EA, Shettigar V, Salhi HE, Davis JP, Ziolo MT, Biesiadecki B. Troponin I Tyrosine Phosphorylation Modulates Cardiac Contraction. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.2611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Salhi HE, Hassel NC, Siddiqui JK, Brundage EA, Ziolo MT, Janssen PML, Davis JP, Biesiadecki BJ. Myofilament Calcium Sensitivity: Mechanistic Insight into TnI Ser-23/24 and Ser-150 Phosphorylation Integration. Front Physiol 2016; 7:567. [PMID: 28018230 PMCID: PMC5156683 DOI: 10.3389/fphys.2016.00567] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 11/08/2016] [Indexed: 11/14/2022] Open
Abstract
Troponin I (TnI) is a major regulator of cardiac muscle contraction and relaxation. During physiological and pathological stress, TnI is differentially phosphorylated at multiple residues through different signaling pathways to match cardiac function to demand. The combination of these TnI phosphorylations can exhibit an expected or unexpected functional integration, whereby the function of two phosphorylations are different than that predicted from the combined function of each individual phosphorylation alone. We have shown that TnI Ser-23/24 and Ser-150 phosphorylation exhibit functional integration and are simultaneously increased in response to cardiac stress. In the current study, we investigated the functional integration of TnI Ser-23/24 and Ser-150 to alter cardiac contraction. We hypothesized that Ser-23/24 and Ser-150 phosphorylation each utilize distinct molecular mechanisms to alter the TnI binding affinity within the thin filament. Mathematical modeling predicts that Ser-23/24 and Ser-150 phosphorylation affect different TnI affinities within the thin filament to distinctly alter the Ca2+-binding properties of troponin. Protein binding experiments validate this assertion by demonstrating pseudo-phosphorylated Ser-150 decreases the affinity of isolated TnI for actin, whereas Ser-23/24 pseudo-phosphorylation is not different from unphosphorylated. Thus, our data supports that TnI Ser-23/24 affects TnI-TnC binding, while Ser-150 phosphorylation alters TnI-actin binding. By measuring force development in troponin-exchanged skinned myocytes, we demonstrate that the Ca2+ sensitivity of force is directly related to the amount of phosphate present on TnI. Furthermore, we demonstrate that Ser-150 pseudo-phosphorylation blunts Ser-23/24-mediated decreased Ca2+-sensitive force development whether on the same or different TnI molecule. Therefore, TnI phosphorylations can integrate across troponins along the myofilament. These data demonstrate that TnI Ser-23/24 and Ser-150 phosphorylation regulates muscle contraction in part by modulating different TnI interactions in the thin filament and it is the combination of these differential mechanisms that provides understanding of their functional integration.
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Affiliation(s)
- Hussam E Salhi
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, Ohio State University Columbus, OH, USA
| | - Nathan C Hassel
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, Ohio State University Columbus, OH, USA
| | - Jalal K Siddiqui
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, Ohio State University Columbus, OH, USA
| | - Elizabeth A Brundage
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, Ohio State University Columbus, OH, USA
| | - Mark T Ziolo
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, Ohio State University Columbus, OH, USA
| | - Paul M L Janssen
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, Ohio State University Columbus, OH, USA
| | - Jonathan P Davis
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, Ohio State University Columbus, OH, USA
| | - Brandon J Biesiadecki
- Department of Physiology and Cell Biology and Davis Heart and Lung Research Institute, Ohio State University Columbus, OH, USA
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Salhi HE, Gualtieri NP, Walton SD, Brundage EA, Davis JP, Biesiadecki BJ. Integration of Cardiac Troponin I Phosphorylations to Modulate Function. Biophys J 2016. [DOI: 10.1016/j.bpj.2015.11.2809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Brundage EA, Biesiadecki BJ, Reiser PJ. Nucleotide and protein sequences for dog masticatory tropomyosin identify a novel Tpm4 gene product. J Muscle Res Cell Motil 2015; 36:339-347. [PMID: 26400443 DOI: 10.1007/s10974-015-9425-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 09/14/2015] [Indexed: 12/18/2022]
Abstract
Jaw-closing muscles of several vertebrate species, including members of Carnivora, express a unique, "masticatory", isoform of myosin heavy chain, along with isoforms of other myofibrillar proteins that are not expressed in most other muscles. It is generally believed that the complement of myofibrillar isoforms in these muscles serves high force generation for capturing live prey, breaking down tough plant material and defensive biting. A unique isoform of tropomyosin (Tpm) was reported to be expressed in cat jaw-closing muscle, based upon two-dimensional gel mobility, peptide mapping, and immunohistochemistry. The objective of this study was to obtain protein and gene sequence information for this unique Tpm isoform. Samples of masseter (a jaw-closing muscle), tibialis (predominantly fast-twitch fibers), and the deep lateral gastrocnemius (predominantly slow-twitch fibers) were obtained from adult dogs. Expressed Tpm isoforms were cloned and sequencing yielded cDNAs that were identical to genomic predicted striated muscle Tpm1.1St(a,b,b,a) (historically referred to as αTpm), Tpm2.2St(a,b,b,a) (βTpm) and Tpm3.12St(a,b,b,a) (γTpm) isoforms (nomenclature reflects predominant tissue expression ("St"-striated muscle) and exon splicing pattern), as well as a novel 284 amino acid isoform observed in jaw-closing muscle that is identical to a genomic predicted product of the Tpm4 gene (δTpm) family. The novel isoform is designated as Tpm4.3St(a,b,b,a). The myofibrillar Tpm isoform expressed in dog masseter exhibits a unique electrophoretic mobility on gels containing 6 M urea, compared to other skeletal Tpm isoforms. To validate that the cloned Tpm4.3 isoform is the Tpm expressed in dog masseter, E. coli-expressed Tpm4.3 was electrophoresed in the presence of urea. Results demonstrate that Tpm4.3 has identical electrophoretic mobility to the unique dog masseter Tpm isoform and is of different mobility from that of muscle Tpm1.1, Tpm2.2 and Tpm3.12 isoforms. We conclude that the unique Tpm isoform in dog masseter is a product of the Tpm4 gene and that the 284 amino acid protein product of this gene represents a novel myofibrillar Tpm isoform never before observed to be expressed in striated muscle.
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Affiliation(s)
- Elizabeth A Brundage
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Brandon J Biesiadecki
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Peter J Reiser
- Division of Biosciences, College of Dentistry, The Ohio State University, 305 West 12th Avenue, Columbus, OH 43210, USA
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Roof SR, Ho HT, Little SC, Ostler JE, Brundage EA, Periasamy M, Villamena FA, Györke S, Biesiadecki BJ, Heymes C, Houser SR, Davis JP, Ziolo MT. Obligatory role of neuronal nitric oxide synthase in the heart's antioxidant adaptation with exercise. J Mol Cell Cardiol 2015; 81:54-61. [PMID: 25595735 DOI: 10.1016/j.yjmcc.2015.01.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 12/18/2014] [Accepted: 01/06/2015] [Indexed: 02/07/2023]
Abstract
Excessive oxidative stress in the heart results in contractile dysfunction. While antioxidant therapies have been a disappointment clinically, exercise has shown beneficial results, in part by reducing oxidative stress. We have previously shown that neuronal nitric oxide synthase (nNOS) is essential for cardioprotective adaptations caused by exercise. We hypothesize that part of the cardioprotective role of nNOS is via the augmentation of the antioxidant defense with exercise by positively shifting the nitroso-redox balance. Our results show that nNOS is indispensable for the augmented anti-oxidant defense with exercise. Furthermore, exercise training of nNOS knockout mice resulted in a negative shift in the nitroso-redox balance resulting in contractile dysfunction. Remarkably, overexpressing nNOS (conditional cardiac-specific nNOS overexpression) was able to mimic exercise by increasing VO2max. This study demonstrates that exercise results in a positive shift in the nitroso-redox balance that is nNOS-dependent. Thus, targeting nNOS signaling may mimic the beneficial effects of exercise by combating oxidative stress and may be a viable treatment strategy for heart disease.
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Affiliation(s)
- Steve R Roof
- Department of Physiology & Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Hsiang-Ting Ho
- Department of Physiology & Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Sean C Little
- Department of Physiology & Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Joseph E Ostler
- Department of Physiology & Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Elizabeth A Brundage
- Department of Physiology & Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Muthu Periasamy
- Department of Physiology & Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Frederick A Villamena
- Department of Physiology & Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Sandor Györke
- Department of Physiology & Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Brandon J Biesiadecki
- Department of Physiology & Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Christophe Heymes
- Institut des Maladies Métaboliques et Cardiovasculaires, Institut National de la Santé et de la Recherche Médicale, Toulouse, France
| | - Steven R Houser
- Department of Physiology, Cardiovascular Research Center, Temple University, Philadelphia, PA, USA
| | - Jonathan P Davis
- Department of Physiology & Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Mark T Ziolo
- Department of Physiology & Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA.
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Salhi HE, Walton SD, Hassel NC, Brundage EA, de Tombe PP, Janssen PML, Davis JP, Biesiadecki BJ. Cardiac troponin I tyrosine 26 phosphorylation decreases myofilament Ca2+ sensitivity and accelerates deactivation. J Mol Cell Cardiol 2014; 76:257-64. [PMID: 25252176 DOI: 10.1016/j.yjmcc.2014.09.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 09/09/2014] [Accepted: 09/12/2014] [Indexed: 10/24/2022]
Abstract
Troponin I (TnI), the inhibitory subunit of the troponin complex, can be phosphorylated as a key regulatory mechanism to alter the calcium regulation of contraction. Recent work has identified phosphorylation of TnI Tyr-26 in the human heart with unknown functional effects. We hypothesized that TnI Tyr-26N-terminal phosphorylation decreases calcium sensitivity of the thin filament, similar to the desensitizing effects of TnI Ser-23/24 phosphorylation. Our results demonstrate that Tyr-26 phosphorylation and pseudo-phosphorylation decrease calcium binding to troponin C (TnC) on the thin filament and calcium sensitivity of force development to a similar magnitude as TnI Ser-23/24 pseudo-phosphorylation. To investigate the effects of TnI Tyr-26 phosphorylation on myofilament deactivation, we measured the rate of calcium dissociation from TnC. Results demonstrate that filaments containing Tyr-26 pseudo-phosphorylated TnI accelerate the rate of calcium dissociation from TnC similar to that of TnI Ser-23/24. Finally, to assess functional integration of TnI Tyr-26 with Ser-23/24 phosphorylation, we generated recombinant TnI phospho-mimetic substitutions at all three residues. Our biochemical analyses demonstrated no additive effect on calcium sensitivity or calcium-sensitive force development imposed by Tyr-26 and Ser-23/24 phosphorylation integration. However, integration of Tyr-26 phosphorylation with pseudo-phosphorylated Ser-23/24 further accelerated thin filament deactivation. Our findings suggest that TnI Tyr-26 phosphorylation functions similarly to Ser-23/24N-terminal phosphorylation to decrease myofilament calcium sensitivity and accelerate myofilament relaxation. Furthermore, Tyr-26 phosphorylation can buffer the desensitization of Ser-23/24 phosphorylation while further accelerating thin filament deactivation. Therefore, the functional integration of TnI phosphorylation may be a common mechanism to modulate Ser-23/24 phosphorylation function.
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Affiliation(s)
- Hussam E Salhi
- The Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, USA; The Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Shane D Walton
- The Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, USA; The Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Nathan C Hassel
- The Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, USA; The Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Elizabeth A Brundage
- The Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, USA; The Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Pieter P de Tombe
- The Department of Cell and Molecular Physiology, Health Sciences Division, Loyola University Chicago, Maywood, IL 60153, USA
| | - Paul M L Janssen
- The Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, USA; The Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Jonathan P Davis
- The Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, USA; The Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Brandon J Biesiadecki
- The Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH 43210, USA; The Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA.
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Nixon BR, Walton SD, Zhang B, Brundage EA, Little SC, Ziolo MT, Davis JP, Biesiadecki BJ. Combined troponin I Ser-150 and Ser-23/24 phosphorylation sustains thin filament Ca(2+) sensitivity and accelerates deactivation in an acidic environment. J Mol Cell Cardiol 2014; 72:177-85. [PMID: 24657721 DOI: 10.1016/j.yjmcc.2014.03.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 03/10/2014] [Accepted: 03/13/2014] [Indexed: 01/09/2023]
Abstract
The binding of Ca(2+) to troponin C (TnC) in the troponin complex is a critical step regulating the thin filament, the actin-myosin interaction and cardiac contraction. Phosphorylation of the troponin complex is a key regulatory mechanism to match cardiac contraction to demand. Here we demonstrate that phosphorylation of the troponin I (TnI) subunit is simultaneously increased at Ser-150 and Ser-23/24 during in vivo myocardial ischemia. Myocardial ischemia decreases intracellular pH resulting in depressed binding of Ca(2+) to TnC and impaired contraction. To determine the pathological relevance of these simultaneous TnI phosphorylations we measured individual TnI Ser-150 (S150D), Ser-23/24 (S23/24D) and combined (S23/24/150D) pseudo-phosphorylation effects on thin filament regulation at acidic pH similar to that in myocardial ischemia. Results demonstrate that while acidic pH decreased thin filament Ca(2+) binding to TnC regardless of TnI composition, TnI S150D attenuated this decrease rendering it similar to non-phosphorylated TnI at normal pH. The dissociation of Ca(2+) from TnC was unaltered by pH such that TnI S150D remained slow, S23/24D remained accelerated and the combined S23/24/150D remained accelerated. This effect of the combined TnI Ser-150 and Ser-23/24 pseudo-phosphorylations to maintain Ca(2+) binding while accelerating Ca(2+) dissociation represents the first post-translational modification of troponin by phosphorylation to both accelerate thin filament deactivation and maintain Ca(2+) sensitive activation. These data suggest that TnI Ser-150 phosphorylation induced attenuation of the pH-dependent decrease in Ca(2+) sensitivity and its combination with Ser-23/24 phosphorylation to maintain accelerated thin filament deactivation may impart an adaptive role to preserve contraction during acidic ischemia pH without slowing relaxation.
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Affiliation(s)
- Benjamin R Nixon
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Shane D Walton
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Bo Zhang
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Elizabeth A Brundage
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Sean C Little
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Mark T Ziolo
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Jonathan P Davis
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Brandon J Biesiadecki
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA.
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Ho HT, Liu B, Snyder JS, Lou Q, Brundage EA, Velez-Cortes F, Wang H, Ziolo MT, Anderson ME, Sen CK, Wehrens XHT, Fedorov VV, Biesiadecki BJ, Hund TJ, Györke S. Ryanodine receptor phosphorylation by oxidized CaMKII contributes to the cardiotoxic effects of cardiac glycosides. Cardiovasc Res 2013; 101:165-74. [PMID: 24104877 DOI: 10.1093/cvr/cvt233] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
AIMS Recent studies suggest that proarrhythmic effects of cardiac glycosides (CGs) on cardiomyocyte Ca(2+) handling involve generation of reactive oxygen species (ROS). However, the specific pathway(s) of ROS production and the subsequent downstream molecular events that mediate CG-dependent arrhythmogenesis remain to be defined. METHODS AND RESULTS We examined the effects of digitoxin (DGT) on Ca(2+) handling and ROS production in cardiomyocytes using a combination of pharmacological approaches and genetic mouse models. Myocytes isolated from mice deficient in NADPH oxidase type 2 (NOX2KO) and mice transgenically overexpressing mitochondrial superoxide dismutase displayed markedly increased tolerance to the proarrhythmic action of DGT as manifested by the inhibition of DGT-dependent ROS and spontaneous Ca(2+) waves (SCW). Additionally, DGT-induced mitochondrial membrane potential depolarization was abolished in NOX2KO cells. DGT-dependent ROS was suppressed by the inhibition of PI3K, PKC, and the mitochondrial KATP channel, suggesting roles for these proteins, respectively, in activation of NOX2 and in mitochondrial ROS generation. Western blot analysis revealed increased levels of oxidized CaMKII in WT but not in NOX2KO hearts treated with DGT. The DGT-induced increase in SCW frequency was abolished in myocytes isolated from mice in which the Ser 2814 CaMKII phosphorylation site on RyR2 is constitutively inactivated. CONCLUSION These results suggest that the arrhythmogenic adverse effects of CGs on Ca(2+) handling involve PI3K- and PKC-mediated stimulation of NOX2 and subsequent NOX2-dependent ROS release from the mitochondria; mitochondria-derived ROS then activate CaMKII with consequent phosphorylation of RyR2 at Ser 2814.
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Affiliation(s)
- Hsiang-Ting Ho
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
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Biesiadecki BJ, Nixon BR, Little SC, Brundage EA, Davis JP. Abstract 312: Troponin I Phosphorylation Crosstalk. Circ Res 2012. [DOI: 10.1161/res.111.suppl_1.a312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The troponin (Tn) complex is a critical regulatory and integrative hub for myofilament post-translational modifications that regulate cardiac contraction. Beta-adrenergic-induced protein kinase A (PKA) phosphorylation of cardiac troponin I (cTnI) at Ser-23/24 is a major myofilament cardiac contractile modulator. In addition to this PKA-induced phosphorylation, cTnI can be simultaneously phosphorylated at a number of other residues. To fully understand the molecular mechanisms that underlie cardiac muscle regulation at the myofilament level, cTnI phosphorylations must be studied as integrated events. As an initial step towards understanding the integration of these events, we employed a phosphomimetic approach to investigate the effect of cTnI Ser-150 pseudo-phosphorylation (TnI-S150D) on cTnI PKA pseudo-phosphorylation (TnI-S23/24D) function within the thin filament. The combinatorial effect of these phosphorylation events were determined by measuring the binding of calcium to troponin C in thin filaments reconstituted with human Tn. The steady-state calcium sensitivity of TnC was increased ∼2.3 fold in thin filaments reconstituted with TnI-S150D containing Tn, while TnI-S23/24D containing filaments exhibited an ∼3.9 fold decrease of calcium sensitivity. Importantly, in the presence of both cTnI pseudo-phosphorylations (TnI-S23/24/150D) calcium binding was not different from that of wild-type. Likewise, calcium dissociation from thin filaments reconstituted with TnI-S23/24D was increased by ∼3.5 fold, while TnI-S150D containing filaments demonstrated a decrease in calcium dissociation of ∼2.3 fold compared to wild-type filaments. Interestingly the combined pseudo-phosphorylations of TnI-S23/24/150D only blunted TnI-23/24D calcium dissociation kinetics to ∼1.2 fold of the TnI-S23/24D filaments alone. These findings demonstrate the integrated effects of cTnI site-specific phosphorylation crosstalk to affect the function of cTnI PKA-induced phosphorylation. These data further highlight the importance of understanding the integrated role of Tn phosphorylation crosstalk on cardiac contractile regulation.
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Nixon BR, Thawornkaiwong A, Jin J, Brundage EA, Little SC, Davis JP, Solaro RJ, Biesiadecki BJ. AMP-activated protein kinase phosphorylates cardiac troponin I at Ser-150 to increase myofilament calcium sensitivity and blunt PKA-dependent function. J Biol Chem 2012; 287:19136-47. [PMID: 22493448 DOI: 10.1074/jbc.m111.323048] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
AMP-activated protein kinase (AMPK) is an energy-sensing enzyme central to the regulation of metabolic homeostasis. In the heart AMPK is activated during cardiac stress-induced ATP depletion and functions to stimulate metabolic pathways that restore the AMP/ATP balance. Recently it was demonstrated that AMPK phosphorylates cardiac troponin I (cTnI) at Ser-150 in vitro. We sought to determine if the metabolic regulatory kinase AMPK phosphorylates cTnI at Ser-150 in vivo to alter cardiac contractile function directly at the level of the myofilament. Rabbit cardiac myofibrils separated by two-dimensional isoelectric focusing subjected to a Western blot with a cTnI phosphorylation-specific antibody demonstrates that cTnI is endogenously phosphorylated at Ser-150 in the heart. Treatment of myofibrils with the AMPK holoenzyme increased cTnI Ser-150 phosphorylation within the constraints of the muscle lattice. Compared with controls, cardiac fiber bundles exchanged with troponin containing cTnI pseudo-phosphorylated at Ser-150 demonstrate increased sensitivity of calcium-dependent force development, blunting of both PKA-dependent calcium desensitization, and PKA-dependent increases in length dependent activation. Thus, in addition to the defined role of AMPK as a cardiac metabolic energy gauge, these data demonstrate AMPK Ser-150 phosphorylation of cTnI directly links the regulation of cardiac metabolic demand to myofilament contractile energetics. Furthermore, the blunting effect of cTnI Ser-150 phosphorylation cross-talk can uncouple the effects of myofilament PKA-dependent phosphorylation from β-adrenergic signaling as a novel thin filament contractile regulatory signaling mechanism.
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Affiliation(s)
- Benjamin R Nixon
- Department of Physiology and Cell Biology and The Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio 43210, USA
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