Published online before print February 28, 2002, doi: 10.1161/01.RES.0000014080.82861.5F
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Submitted on August 3, 2001
Revised on February 15, 2002
Accepted on February 15, 2002
Phosphorylation of Troponin I Controls Cardiac Twitch Dynamics. Evidence From Phosphorylation Site Mutants Expressed on a Troponin I--Null Background in Mice
YeQing Pi ;
From the Department of Physiology (Y.P., K.R.K., D.Z., J.W.W.), University of Wisconsin, Madison, Wis; and the Department of Pharmacology and Cell Biophysics (E.G.K.), University of Cincinnati, Cincinnati, Ohio.
* To whom correspondence should be addressed. E-mail: jwalker{at}physiology.wisc.edu.
The cardiac myofilament protein troponin I (cTnI) is phosphorylated by protein kinase C (PKC), a family of serine/threonine kinases activated within heart muscle by a variety of agonists. cTnI is also a substrate for cAMP-dependent protein kinase (PKA) activated during ß-adrenergic signaling. To investigate the role of cTnI phosphorylation in contractile regulation by these pathways, we generated transgenic mice harboring a mutated cTnI protein lacking phosphorylation sites for PKC (serine43/45 and threonine144 mutated to alanine) and for PKA (serine23/24 mutated to alanine). Transgenic mice were interbred with cTnI-knockout mice to ensure the absence of endogenous phosphorylatable cTnI. Here, we report that regulation of myocyte twitch kinetics by ß-stimulation and by endothelin-1 was altered in myocytes containing mutant cTnI. In wild-type myocytes, the ß-agonist isoproterenol decreased twitch duration and relaxation time constant (
) by 37% to 44%. These lusitropic effects of isoproterenol were reduced by about half in nonphosphorylatable cTnI mutant myocytes and were absent in cTnI mutants also lacking phospholamban (generated by crossing cTnI mutants with phospholamban-knockout mice). These observations are consistent with important roles for both cTnI and phospholamban phosphorylation in accelerating relaxation after ß-adrenergic stimulation. In contrast, endothelin-1 increased twitch duration by 32% and increased by 58%. These endothelin-1 effects were substantially blunted in nonphosphorylatable cTnI myocytes, indicating that PKC phosphorylation of cTnI slows cardiac relaxation and increases twitch duration. We propose that ß-agonists and endothelin-1 regulate cardiac twitch dynamics in opposite directions in part through phosphorylation of the myofilament protein cTnI on distinct sites.
Key words: transgenic mice • protein kinase C • protein kinase A • phospholamban
This article has been cited by other articles:
 |
|
 |
|
  K. A. Sheehan, Y. Ke, B. M. Wolska, and R. J. Solaro Expression of active p21-activated kinase-1 induces Ca2+ flux modification with altered regulatory protein phosphorylation in cardiac myocytes Am J Physiol Cell Physiol, January 1, 2009; 296(1): C47 - C58. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Davis, M. V. Westfall, D. Townsend, M. Blankinship, T. J. Herron, G. Guerrero-Serna, W. Wang, E. Devaney, and J. M. Metzger Designing Heart Performance by Gene Transfer Physiol Rev, October 1, 2008; 88(4): 1567 - 1651. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. Zabrouskov, Y. Ge, J. Schwartz, and J. W. Walker Unraveling Molecular Complexity of Phosphorylated Human Cardiac Troponin I by Top Down Electron Capture Dissociation/Electron Transfer Dissociation Mass Spectrometry Mol. Cell. Proteomics, October 1, 2008; 7(10): 1838 - 1849. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. E. Stelzer, J. R. Patel, J. W. Walker, and R. L. Moss Differential Roles of Cardiac Myosin-Binding Protein C and Cardiac Troponin I in the Myofibrillar Force Responses to Protein Kinase A Phosphorylation Circ. Res., August 31, 2007; 101(5): 503 - 511. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Kang, K. Y. Chung, and J. W. Walker G-Protein Coupled Receptor Signaling in Myocardium: Not for the Faint of Heart Physiology, June 1, 2007; 22(3): 174 - 184. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. C. Bilchick, J. G. Duncan, R. Ravi, E. Takimoto, H. C. Champion, W. D. Gao, L. B. Stull, D. A. Kass, and A. M. Murphy Heart failure-associated alterations in troponin I phosphorylation impair ventricular relaxation-afterload and force-frequency responses and systolic function Am J Physiol Heart Circ Physiol, January 1, 2007; 292(1): H318 - H325. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. J. Belin, M. P. Sumandea, T. Kobayashi, L. A. Walker, V. L. Rundell, D. Urboniene, M. Yuzhakova, S. H. Ruch, D. L. Geenen, R. J. Solaro, et al. Left ventricular myofilament dysfunction in rat experimental hypertrophy and congestive heart failure Am J Physiol Heart Circ Physiol, November 1, 2006; 291(5): H2344 - H2353. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Kang and J. W. Walker Endothelin-1 and PKC Induce Positive Inotropy Without Affecting pHi in Ventricular Myocytes. Experimental Biology and Medicine, June 1, 2006; 231(6): 865 - 870. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. V. Westfall, A. M. Lee, and D. A. Robinson Differential Contribution of Troponin I Phosphorylation Sites to the Endothelin-modulated Contractile Response J. Biol. Chem., December 16, 2005; 280(50): 41324 - 41331. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. L. Robia, M. Kang, and J. W. Walker Novel determinant of PKC-{epsilon} anchoring at cardiac Z-lines Am J Physiol Heart Circ Physiol, November 1, 2005; 289(5): H1941 - H1950. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Layland, R. J. Solaro, and A. M. Shah Regulation of cardiac contractile function by troponin I phosphorylation Cardiovasc Res, April 1, 2005; 66(1): 12 - 21. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Sakthivel, N. L. Finley, P. R. Rosevear, J. N. Lorenz, J. Gulick, S. Kim, P. VanBuren, L. A. Martin, and J. Robbins In Vivo and in Vitro Analysis of Cardiac Troponin I Phosphorylation J. Biol. Chem., January 7, 2005; 280(1): 703 - 714. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Layland, D. J. Grieve, A. C. Cave, E. Sparks, R J. Solaro, and A. M. Shah Essential role of troponin I in the positive inotropic response to isoprenaline in mouse hearts contracting auxotonically J. Physiol., May 1, 2004; 556(3): 835 - 847. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. R Pena and B. M Wolska Troponin I phosphorylation plays an important role in the relaxant effect of {beta}-adrenergic stimulation in mouse hearts Cardiovasc Res, March 1, 2004; 61(4): 756 - 763. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. M. Metzger and M. V. Westfall Covalent and Noncovalent Modification of Thin Filament Action: The Essential Role of Troponin in Cardiac Muscle Regulation Circ. Res., February 6, 2004; 94(2): 146 - 158. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Ke, L. Wang, W. G. Pyle, P. P. de Tombe, and R. J. Solaro Intracellular Localization and Functional Effects of P21-Activated Kinase-1 (Pak1) in Cardiac Myocytes Circ. Res., February 6, 2004; 94(2): 194 - 200. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. B. Marston and C. S. Redwood Modulation of Thin Filament Activation by Breakdown or Isoform Switching of Thin Filament Proteins: Physiological and Pathological Implications Circ. Res., December 12, 2003; 93(12): 1170 - 1178. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Pi, D. Zhang, K. R Kemnitz, H. Wang, and J. W Walker Protein kinase C and A sites on troponin I regulate myofilament Ca2+ sensitivity and ATPase activity in the mouse myocardium J. Physiol., November 1, 2003; 552(3): 845 - 857. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. V. Westfall and A. R. Borton Role of Troponin I Phosphorylation in Protein Kinase C-mediated Enhanced Contractile Performance of Rat Myocytes J. Biol. Chem., September 5, 2003; 278(36): 33694 - 33700. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Chu, R. Takahashi, I. Norota, T. Miyamoto, Y. Takeishi, K. Ishii, I. Kubota, and M. Endoh Signal Transduction and Ca2+ Signaling in Contractile Regulation Induced by Crosstalk Between Endothelin-1 and Norepinephrine in Dog Ventricular Myocardium Circ. Res., May 16, 2003; 92(9): 1024 - 1032. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. G. Brittsan, K. S. Ginsburg, G. Chu, A. Yatani, B. M. Wolska, A. G. Schmidt, M. Asahi, D. H. MacLennan, D. M. Bers, and E. G. Kranias Chronic SR Ca2+-ATPase Inhibition Causes Adaptive Changes in Cellular Ca2+ Transport Circ. Res., April 18, 2003; 92(7): 769 - 776. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. M. Burkart, M. P. Sumandea, T. Kobayashi, M. Nili, A. F. Martin, E. Homsher, and R. J. Solaro Phosphorylation or Glutamic Acid Substitution at Protein Kinase C Sites on Cardiac Troponin I Differentially Depress Myofilament Tension and Shortening Velocity J. Biol. Chem., March 21, 2003; 278(13): 11265 - 11272. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Chaudhri, F. del Monte, R. J. Hajjar, and S. E. Harding Interaction between increased SERCA2a activity and beta -adrenoceptor stimulation in adult rabbit myocytes Am J Physiol Heart Circ Physiol, December 1, 2002; 283(6): H2450 - H2457. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Melendez, S. Welch, E. Schaefer, C. S. Moravec, S. Avraham, H. Avraham, and M. A. Sussman Activation of pyk2/Related Focal Adhesion Tyrosine Kinase and Focal Adhesion Kinase in Cardiac Remodeling J. Biol. Chem., November 15, 2002; 277(47): 45203 - 45210. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. S. McDonald and T. J. Herron It Takes "Heart" to Win: What Makes the Heart Powerful? Physiology, October 1, 2002; 17(5): 185 - 190. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Layland and J. C Kentish Myofilament-based relaxant effect of isoprenaline revealed during work-loop contractions in rat cardiac trabeculae J. Physiol., October 1, 2002; 544(1): 171 - 182. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. M. Murphy Troponin I: In Sickness and In Health--and Normal Development Circ. Res., September 20, 2002; 91(6): 449 - 450. [Full Text] [PDF]
|
|
|
|
|
|
M. V. Westfall, A. R. Borton, F. P. Albayya, and J. M. Metzger Myofilament Calcium Sensitivity and Cardiac Disease: Insights From Troponin I Isoforms and Mutants Circ. Res., September 20, 2002; 91(6): 525 - 531. [Abstract] [Full Text] [PDF]
|
|