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Paulus WJ, van Ballegoij JJM. Treatment of heart failure with normal ejection fraction: an inconvenient truth! J Am Coll Cardiol 2010; 55:526-37. [PMID: 20152557 DOI: 10.1016/j.jacc.2009.06.067] [Citation(s) in RCA: 178] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 06/12/2009] [Accepted: 06/15/2009] [Indexed: 11/30/2022]
Abstract
Despite use of similar drugs, outcomes of recent heart failure (HF) trials were frequently neutral in heart failure with normal left ventricular ejection fraction (HFNEF) and positive in heart failure with reduced left ventricular ejection fraction (HFREF). The neutral outcomes of HFNEF trials were often attributed to deficient HFNEF patient recruitment with inclusion of many HFREF or noncardiac patients. Patient recruitment criteria of 21 HFNEF trials were therefore reviewed in reference to diagnostic guidelines for HFNEF. In the 4 published sets of guidelines, a definite diagnosis of HFNEF required the simultaneous and obligatory presence of signs and/or symptoms of HF and evidence of normal systolic left ventricular (LV) function and of diastolic LV dysfunction. In 3 of 4 sets of guidelines, normal systolic LV function comprised both a left ventricular ejection fraction (LVEF) >50% and an absence of LV dilation. Among the 21 HFNEF trials, LVEF cutoff values ranged from 35% to 50%, with only 8 trials adhering to an LVEF >50%. Furthermore, only 1 trial specified a normal LV end-diastolic dimension as an enrollment criterion and only 7 trials required evidence of diastolic LV dysfunction. Nonadherence to diagnostic guidelines induced excessive enrollment into HFNEF trials of HF patients with eccentric LV remodeling and ischemic heart disease compared with HF patients with concentric LV remodeling and arterial hypertension. Nonadherence to guidelines also led to underpowered HFNEF trials with a low incidence of outcome events such as death or HF hospitalizations. Future HFNEF trials should therefore adhere to diagnostic guidelines for HFNEF.
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Affiliation(s)
- Walter J Paulus
- Institute for Cardiovascular Research Vrije Universiteit, VU University Medical Center Amsterdam, Amsterdam, the Netherlands.
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253
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Chaturvedi RR, Herron T, Simmons R, Shore D, Kumar P, Sethia B, Chua F, Vassiliadis E, Kentish JC. Passive Stiffness of Myocardium From Congenital Heart Disease and Implications for Diastole. Circulation 2010; 121:979-88. [DOI: 10.1161/circulationaha.109.850677] [Citation(s) in RCA: 118] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Rajiv R. Chaturvedi
- From the King’s College London British Heart Foundation Centre (R.R.C., T.H., R.S., E.V., J.C.K.); Royal Brompton Hospital (R.R.C., D.S., P.K., B.S.); and Centre for Respiratory Research, University College (F.C.), London, UK. Dr Chaturvedi is currently at the Division of Cardiology, Hospital for Sick Children, Toronto, Canada. Dr Herron is currently at the Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor. Dr Kumar is currently at the Cardiac Centre, Morriston
| | - Todd Herron
- From the King’s College London British Heart Foundation Centre (R.R.C., T.H., R.S., E.V., J.C.K.); Royal Brompton Hospital (R.R.C., D.S., P.K., B.S.); and Centre for Respiratory Research, University College (F.C.), London, UK. Dr Chaturvedi is currently at the Division of Cardiology, Hospital for Sick Children, Toronto, Canada. Dr Herron is currently at the Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor. Dr Kumar is currently at the Cardiac Centre, Morriston
| | - Robert Simmons
- From the King’s College London British Heart Foundation Centre (R.R.C., T.H., R.S., E.V., J.C.K.); Royal Brompton Hospital (R.R.C., D.S., P.K., B.S.); and Centre for Respiratory Research, University College (F.C.), London, UK. Dr Chaturvedi is currently at the Division of Cardiology, Hospital for Sick Children, Toronto, Canada. Dr Herron is currently at the Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor. Dr Kumar is currently at the Cardiac Centre, Morriston
| | - Darryl Shore
- From the King’s College London British Heart Foundation Centre (R.R.C., T.H., R.S., E.V., J.C.K.); Royal Brompton Hospital (R.R.C., D.S., P.K., B.S.); and Centre for Respiratory Research, University College (F.C.), London, UK. Dr Chaturvedi is currently at the Division of Cardiology, Hospital for Sick Children, Toronto, Canada. Dr Herron is currently at the Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor. Dr Kumar is currently at the Cardiac Centre, Morriston
| | - Pankaj Kumar
- From the King’s College London British Heart Foundation Centre (R.R.C., T.H., R.S., E.V., J.C.K.); Royal Brompton Hospital (R.R.C., D.S., P.K., B.S.); and Centre for Respiratory Research, University College (F.C.), London, UK. Dr Chaturvedi is currently at the Division of Cardiology, Hospital for Sick Children, Toronto, Canada. Dr Herron is currently at the Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor. Dr Kumar is currently at the Cardiac Centre, Morriston
| | - Babulal Sethia
- From the King’s College London British Heart Foundation Centre (R.R.C., T.H., R.S., E.V., J.C.K.); Royal Brompton Hospital (R.R.C., D.S., P.K., B.S.); and Centre for Respiratory Research, University College (F.C.), London, UK. Dr Chaturvedi is currently at the Division of Cardiology, Hospital for Sick Children, Toronto, Canada. Dr Herron is currently at the Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor. Dr Kumar is currently at the Cardiac Centre, Morriston
| | - Felix Chua
- From the King’s College London British Heart Foundation Centre (R.R.C., T.H., R.S., E.V., J.C.K.); Royal Brompton Hospital (R.R.C., D.S., P.K., B.S.); and Centre for Respiratory Research, University College (F.C.), London, UK. Dr Chaturvedi is currently at the Division of Cardiology, Hospital for Sick Children, Toronto, Canada. Dr Herron is currently at the Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor. Dr Kumar is currently at the Cardiac Centre, Morriston
| | - Efstathios Vassiliadis
- From the King’s College London British Heart Foundation Centre (R.R.C., T.H., R.S., E.V., J.C.K.); Royal Brompton Hospital (R.R.C., D.S., P.K., B.S.); and Centre for Respiratory Research, University College (F.C.), London, UK. Dr Chaturvedi is currently at the Division of Cardiology, Hospital for Sick Children, Toronto, Canada. Dr Herron is currently at the Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor. Dr Kumar is currently at the Cardiac Centre, Morriston
| | - Jonathan C. Kentish
- From the King’s College London British Heart Foundation Centre (R.R.C., T.H., R.S., E.V., J.C.K.); Royal Brompton Hospital (R.R.C., D.S., P.K., B.S.); and Centre for Respiratory Research, University College (F.C.), London, UK. Dr Chaturvedi is currently at the Division of Cardiology, Hospital for Sick Children, Toronto, Canada. Dr Herron is currently at the Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor. Dr Kumar is currently at the Cardiac Centre, Morriston
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257
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Anderson BR, Bogomolovas J, Labeit S, Granzier H. The effects of PKCalpha phosphorylation on the extensibility of titin's PEVK element. J Struct Biol 2010; 170:270-7. [PMID: 20149875 DOI: 10.1016/j.jsb.2010.02.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 02/01/2010] [Accepted: 02/03/2010] [Indexed: 11/29/2022]
Abstract
Post-translational modifications, along with isoform splicing, of titin determine the passive tension development of stretched sarcomeres. It was recently shown that PKCalpha phosphorylates two highly-conserved residues (S26 and S170) of the PEVK region in cardiac titin, resulting in passive tension increase. To determine how each phosphorylated residue affects myocardial stiffness, we generated three recombinant mutant PEVK fragments (S26A, S170A and S170A/S26A), each flanked by Ig domains. Single-molecule force spectroscopy shows that PKCalpha decreases the PEVK persistence length (from 0.99 to 0.68 nm); the majority of this decrease is attributable to phosphorylation of S26. Before PKCalpha, all three mutant PEVK fragments showed at least 40% decrease in persistence length compared to wildtype. Furthermore, Ig domain unfolding force measurements indicate that PEVK's flanking Ig domains are relatively unstable compared to other titin Ig domains. We conclude that phosphorylation of S26 is the primary mechanism through which PKCalpha modulates cardiac stiffness.
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258
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Kooij V, Saes M, Jaquet K, Zaremba R, Foster DB, Murphy AM, Dos Remedios C, van der Velden J, Stienen GJM. Effect of troponin I Ser23/24 phosphorylation on Ca2+-sensitivity in human myocardium depends on the phosphorylation background. J Mol Cell Cardiol 2010; 48:954-63. [PMID: 20079747 DOI: 10.1016/j.yjmcc.2010.01.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Revised: 01/05/2010] [Accepted: 01/05/2010] [Indexed: 11/29/2022]
Abstract
Protein kinase A (PKA)-mediated phosphorylation of Ser23/24 of cardiac troponin I (cTnI) causes a reduction in Ca(2+)-sensitivity of force development. This study aimed to determine whether the PKA-induced modulation of the Ca(2+)-sensitivity is solely due to cTnI phosphorylation or depends on the phosphorylation status of other sarcomeric proteins. Endogenous troponin (cTn) complex in donor cardiomyocytes was partially exchanged (up to 66+/-1%) with recombinant unphosphorylated human cTn and in failing cells similar exchange was achieved using PKA-(bis)phosphorylated cTn complex. Cardiomyocytes immersed in exchange solution without complex added served as controls. Partial exchange of unphosphorylated cTn complex in donor tissue significantly increased Ca(2+)-sensitivity (pCa(50)) to 5.50+/-0.02 relative to the donor control value (pCa(50)=5.43+/-0.04). Exchange in failing tissue with PKA-phosphorylated cTn complex did not change Ca(2+)-sensitivity relative to the failing control (pCa(50)=5.60+/-0.02). Subsequent treatment of the cardiomyocytes with the catalytic subunit of PKA significantly decreased Ca(2+)-sensitivity in donor and failing tissue. Analysis of phosphorylated cTnI species revealed the same distribution of un-, mono- and bis-phosphorylated cTnI in donor control and in failing tissue exchanged with PKA-phosphorylated cTn complex. Phosphorylation of myosin-binding protein-C in failing tissue was significantly lower compared to donor tissue. These differences in Ca(2+)-sensitivity in donor and failing cells, despite similar distribution of cTnI species, could be abolished by subsequent PKA-treatment and indicate that other targets of PKA are involved the reduction of Ca(2+)-sensitivity. Our findings suggest that the sarcomeric phosphorylation background, which is altered in cardiac disease, influences the impact of cTnI Ser23/24 phosphorylation by PKA on Ca(2+)-sensitivity.
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Affiliation(s)
- Viola Kooij
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands.
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259
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Hudson BD, Hidalgo CG, Gotthardt M, Granzier HL. Excision of titin's cardiac PEVK spring element abolishes PKCalpha-induced increases in myocardial stiffness. J Mol Cell Cardiol 2009; 48:972-8. [PMID: 20026128 DOI: 10.1016/j.yjmcc.2009.12.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 12/03/2009] [Accepted: 12/08/2009] [Indexed: 11/26/2022]
Abstract
Protein kinase C-alpha (PKCalpha) was recently reported to increase myocardial stiffness, an effect that was proposed to be due to phosphorylation of two highly conserved sites (S11878 and S12022) within the proline-glutamic acid-valine-lysine (PEVK) rich spring element of titin. To test this proposal we investigated the effect of PKCalpha on phosphorylation and passive stiffness in a mouse model lacking the titin exons that contain these two phosphorylation sites, the PEVK knockout (KO). We used skinned, gelsolin-extracted, left ventricular myocardium from wildtype and PEVK KO mice. Consistent with previous work we found that PKCalpha increased passive stiffness in the WT myocardium by 27+/-6%. Importantly, this effect was completely abolished in KO myocardium. In addition, increases in the elastic and viscous moduli at a wide range of frequencies (properties important in diastolic filling) following PKCalpha incubation (27+/-3% and 20+/-4%, respectively) were also ablated in the KO. Back phosphorylation assays showed that titin phosphorylation following incubation with PKCalpha was significantly reduced by 36+/-12% in skinned PEVK KO myocardial tissues. The remaining phosphorylation in the KO suggests that PKCalpha sites exist in the titin molecule outside the PEVK region; these sites are not involved in increasing passive stiffness. Our results firmly support that the PEVK region of cardiac titin is phosphorylated by PKCalpha and that this increases passive tension. Thus, the PEVK spring element is the critical site of PKCalpha's involvement in passive myocardial stiffness.
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Affiliation(s)
- Bryan D Hudson
- Department of Physiology, Sarver Molecular Cardiovascular Research Program, University of Arizona, PO Box 245217 Tucson, AZ 85724, USA
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261
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Effects of diabetes mellitus, pressure-overload and their association on myocardial structure and function. Am J Hypertens 2009; 22:1190-8. [PMID: 19745820 DOI: 10.1038/ajh.2009.159] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND Structural and functional changes involved in cardiac injury induced by diabetes mellitus, pressure-overload, or both conditions were evaluated. METHODS Pressure-overload was established by suprarenal aortic banding in rats. Six weeks later, diabetes was induced by streptozotocin (STZ, 65 mg/kg, intraperitoneally), resulting in four groups: SHAM, banded (BA), diabetic (DM), and diabetic-banded (DM-BA). On the 12th week, left ventricular (LV) structure and function were evaluated. LV function was assessed in vivo with pressure-volume catheters and in vitro by papillary muscles' performance at baseline and in response to isoprenaline (ISO, 10(-8) to 10(-5) M). RESULTS Compared to SHAM, we observed a significant increase of type-B natriuretic peptide (BA = 370 +/- 110%; DM-BA = 580 +/- 210%), LV mass (BA = 36.8 +/- 3.6%; DM-BA = 32.1 +/- 3.1%), cardiomyocyte diameter (BA = 19.5 +/- 2.3%; DM = 14.3 +/- 1.9%; DM-BA = 11.4 +/- 2.0%), fibrosis (BA = 85 +/- 14%; DM = 145 +/- 28%; DM-BA = 155 +/- 14%), advanced glycation end-product (AGE) deposition (DM = 141 +/- 29%; DM-BA = 166 +/- 46%), contraction (tAT: DM = 13.7 +/- 2.4%; DM-BA = 26.3 +/- 7.1%); a delayed relaxation (tHR: DM = 13.8 +/- 2.6%; DM-BA = 25.5 +/- 9.2%) and a decrease of collagen type-I/type-III ratio (DM = -66.1 +/- 4.6%; DM-BA = -51.9 +/- 5.5). In SHAM animals, ISO (10(-5) M) increased 86.5 +/- 26.2% active tension, 105.3 +/- 20.2% dT/dt(max), and 166.8 +/- 29.9% dT/dt(min). Similar effects were observed in BA and DM animals, whereas in DM-BA these inotropic and lusitropic responses were blunted. Moreover, at a similar resting muscle length, ISO decreased passive tension by 12 +/- 3% in SHAM and 11 +/- 3% in BA, indicating an increase in myocardial distensibility, an effect that was absent in both diabetic groups. CONCLUSION Long-standing pressure-overload increased LV mass, while diabetes promoted AGE and collagen deposition, which might explain the abolition of ISO-induced increased myocardial distensibility. Association of pressure-overload and diabetes completely blunted the inotropic and lusitropic responses to ISO, with no additional structural damages than in pressure-overload or diabetes alone.
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264
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Hidalgo C, Hudson B, Bogomolovas J, Zhu Y, Anderson B, Greaser M, Labeit S, Granzier H. PKC phosphorylation of titin's PEVK element: a novel and conserved pathway for modulating myocardial stiffness. Circ Res 2009; 105:631-8, 17 p following 638. [PMID: 19679839 DOI: 10.1161/circresaha.109.198465] [Citation(s) in RCA: 202] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Protein kinase C (PKC) regulates contractility of cardiac muscle cells by phosphorylating thin- and thick- filament-based proteins. Myocardial sarcomeres also contain a third myofilament, titin, and it is unknown whether titin can be phosphorylated by PKC and whether it affects passive tension. OBJECTIVE The purpose of this study was to examine the effect of PKC on titin phosphorylation and titin-based passive tension. METHODS AND RESULTS Phosphorylation assays with PKCalpha revealed that titin is phosphorylated in skinned myocardial tissues; this effect is exacerbated by pretreating with protein phosphatase 1. In vitro phosphorylation of recombinant protein representing titin's spring elements showed that PKCalpha targets the proline - glutamate - valine - lysine (PEVK) spring element. Furthermore, mass spectrometry in combination with site-directed mutagenesis identified 2 highly conserved sites in the PEVK region that are phosphorylated by PKCalpha (S11878 and S12022); when these 2 sites are mutated to alanine, phosphorylation is effectively abolished. Mechanical experiments with skinned left ventricular myocardium revealed that PKCalpha significantly increases titin-based passive tension, an effect that is reversed by protein phosphatase 1. Single molecule force-extension curves show that PKCalpha decreases the PEVK persistence length (from 1.20 nm to 0.55 nm), without altering the contour length, and using a serially-linked wormlike chain model we show that this increases titin-based passive force with a sarcomere length dependence that is similar to that measured in skinned myocardium after PKCalpha phosphorylation. CONCLUSIONS PKC phosphorylation of titin is a novel and conserved pathway that links myocardial signaling and myocardial stiffness.
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Affiliation(s)
- Carlos Hidalgo
- Sarver Molecular Cardiovascular Research Program, University of Arizona, Tucson, AZ 85724, USA
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265
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Kooij V, Boontje N, Zaremba R, Jaquet K, dos Remedios C, Stienen GJM, van der Velden J. Protein kinase C alpha and epsilon phosphorylation of troponin and myosin binding protein C reduce Ca2+ sensitivity in human myocardium. Basic Res Cardiol 2009; 105:289-300. [PMID: 19655190 PMCID: PMC2807945 DOI: 10.1007/s00395-009-0053-z] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Revised: 07/20/2009] [Accepted: 07/22/2009] [Indexed: 12/01/2022]
Abstract
Previous studies indicated that the increase in protein kinase C (PKC)-mediated myofilament protein phosphorylation observed in failing myocardium might be detrimental for contractile function. This study was designed to reveal and compare the effects of PKCα- and PKCε-mediated phosphorylation on myofilament function in human myocardium. Isometric force was measured at different [Ca2+] in single permeabilized cardiomyocytes from failing human left ventricular tissue. Activated PKCα and PKCε equally reduced Ca2+ sensitivity in failing cardiomyocytes (ΔpCa50 = 0.08 ± 0.01). Both PKC isoforms increased phosphorylation of troponin I- (cTnI) and myosin binding protein C (cMyBP-C) in failing cardiomyocytes. Subsequent incubation of failing cardiomyocytes with the catalytic subunit of protein kinase A (PKA) resulted in a further reduction in Ca2+ sensitivity, indicating that the effects of both PKC isoforms were not caused by cross-phosphorylation of PKA sites. Both isozymes showed no effects on maximal force and only PKCα resulted in a modest significant reduction in passive force. Effects of PKCα were only minor in donor cardiomyocytes, presumably because of already saturated cTnI and cMyBP-C phosphorylation levels. Donor tissue could therefore be used as a tool to reveal the functional effects of troponin T (cTnT) phosphorylation by PKCα. Massive dephosphorylation of cTnT with alkaline phosphatase increased Ca2+ sensitivity. Subsequently, PKCα treatment of donor cardiomyocytes reduced Ca2+ sensitivity (ΔpCa50 = 0.08 ± 0.02) and solely increased phosphorylation of cTnT, but did not affect maximal and passive force. PKCα- and PKCε-mediated phosphorylation of cMyBP-C and cTnI as well as cTnT decrease myofilament Ca2+ sensitivity and may thereby reduce contractility and enhance relaxation of human myocardium.
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Affiliation(s)
- Viola Kooij
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands.
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