| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
© 2000 American Heart Association, Inc.
Cellular Biology |
Investigation of a Truncated Cardiac Troponin T That Causes Familial Hypertrophic Cardiomyopathy
Ca2+ Regulatory Properties of Reconstituted Thin Filaments Depend on the Ratio of Mutant to Wild-Type Protein
From the Department of Cardiovascular Medicine (C.R., G.E., K.E., H.W.), University of Oxford, John Radcliffe Hospital, Oxford, and Department of Cardiac Medicine (K.L., W.B., H.A., A.K., I.P., S.M.), Imperial College School of Medicine, National Heart and Lung Institute, London, United Kingdom.
Correspondence to Dr Charles Redwood, Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK. E-mail credwood{at}molbiol.ox.ac.uk
Abstract—Familial hypertrophic cardiomyopathy (HCM) is caused by mutations in at least 8 contractile protein genes, most commonly ß myosin heavy chain, myosin binding protein C, and cardiac troponin T. Affected individuals are heterozygous for a particular mutation, and most evidence suggests that the mutant protein acts in a dominant-negative fashion. To investigate the functional properties of a truncated troponin T shown to cause HCM, both wild-type and mutant human cardiac troponin T were overexpressed in Escherichia coli, purified, and combined with human cardiac troponins I and C to reconstitute human cardiac troponin. Significant differences were found between the regulatory properties of wild-type and mutant troponin in vitro, as follows. (1) In actin-tropomyosin–activated myosin ATPase assays at pCa 9, wild-type troponin caused 80% inhibition of ATPase, whereas the mutant complex gave negligible inhibition. (2) Similarly, in the in vitro motility assay, mutant troponin failed to decrease both the proportion of actin-tropomyosin filaments motile and the velocity of motile filaments at pCa 9. (3) At pCa 5, the addition of mutant complex caused a greater increase (21.7%) in velocity of actin-tropomyosin filaments than wild-type troponin (12.3%). These data suggest that the truncated troponin T prevents switching off of the thin filament at low Ca2+. However, the study of thin filaments containing varying ratios of wild-type and mutant troponin T at low Ca2+ indicated an opposite effect of mutant troponin, causing enhancement of the inhibitory effect of wild-type complex, when it is present in a low ratio (10% to 50%). These multiple effects need to be taken into account to explain the physiological consequences of this mutation in HCM. Further, these findings underscore the importance of studying mixed mutant:wild-type preparations to faithfully model this autosomal-dominant disease.
Key Words: familial hypertrophic cardiomyopathy • troponin T • cardiac muscle • in vitro motility
This article has been cited by other articles:
 |
|
 |
|
  E. C. Dyer, A. M. Jacques, A. C. Hoskins, D. G. Ward, C. E. Gallon, A. E. Messer, J. P. Kaski, M. Burch, J. C. Kentish, and S. B. Marston Functional Analysis of a Unique Troponin C Mutation, GLY159ASP, that Causes Familial Dilated Cardiomyopathy, Studied in Explanted Heart Muscle Circ Heart Fail, September 1, 2009; 2(5): 456 - 464. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. Jagatheesan, S. Rajan, E. M. Schulz, R. P. H. Ahmed, N. Petrashevskaya, A. Schwartz, G. P. Boivin, G. M. Arteaga, T. Wang, Y.-G. Wang, et al. An internal domain of {beta}-tropomyosin increases myofilament Ca2+ sensitivity Am J Physiol Heart Circ Physiol, July 1, 2009; 297(1): H181 - H190. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. M. Jacques, N. Briceno, A. E. Messer, C. E. Gallon, S. Jalilzadeh, E. Garcia, G. Kikonda-Kanda, J. Goddard, S. E. Harding, H. Watkins, et al. The molecular phenotype of human cardiac myosin associated with hypertrophic obstructive cardiomyopathy Cardiovasc Res, August 1, 2008; 79(3): 481 - 491. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Robinson, P. J. Griffiths, H. Watkins, and C. S. Redwood Dilated and Hypertrophic Cardiomyopathy Mutations in Troponin and {alpha}-Tropomyosin Have Opposing Effects on the Calcium Affinity of Cardiac Thin Filaments Circ. Res., December 7, 2007; 101(12): 1266 - 1273. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Ashrafian and H. Watkins Reviews of Translational Medicine and Genomics in Cardiovascular Disease: New Disease Taxonomy and Therapeutic Implications: Cardiomyopathies: Therapeutics Based on Molecular Phenotype J. Am. Coll. Cardiol., March 27, 2007; 49(12): 1251 - 1264. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Robinson, S. Lipscomb, L. C. Preston, E. Altin, H. Watkins, C. C. Ashley, and C. S. Redwood Mutations in fast skeletal troponin I, troponin T, and {beta}-tropomyosin that cause distal arthrogryposis all increase contractile function FASEB J, March 1, 2007; 21(3): 896 - 905. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Adamcova, M. Sterba, T. Simunek, A. Potacova, O. Popelova, and V. Gersl Myocardial regulatory proteins and heart failure Eur J Heart Fail, June 1, 2006; 8(4): 333 - 342. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. R. Ertz-Berger, H. He, C. Dowell, S. M. Factor, T. E. Haim, S. Nunez, S. D. Schwartz, J. S. Ingwall, and J. C. Tardiff Changes in the chemical and dynamic properties of cardiac troponin T cause discrete cardiomyopathies in transgenic mice PNAS, December 13, 2005; 102(50): 18219 - 18224. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Mirza, S. Marston, R. Willott, C. Ashley, J. Mogensen, W. McKenna, P. Robinson, C. Redwood, and H. Watkins Dilated Cardiomyopathy Mutations in Three Thin Filament Regulatory Proteins Result in a Common Functional Phenotype J. Biol. Chem., August 5, 2005; 280(31): 28498 - 28506. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Sanbe, J. James, V. Tuzcu, S. Nas, L. Martin, J. Gulick, H. Osinska, S. Sakthivel, R. Klevitsky, K. S. Ginsburg, et al. Transgenic Rabbit Model for Human Troponin I-Based Hypertrophic Cardiomyopathy Circulation, May 10, 2005; 111(18): 2330 - 2338. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. E. Stelzer, J. R. Patel, M. C. Olsson, D. P. Fitzsimons, L. A. Leinwand, and R. L. Moss Expression of cardiac troponin T with COOH-terminal truncation accelerates cross-bridge interaction kinetics in mouse myocardium Am J Physiol Heart Circ Physiol, October 1, 2004; 287(4): H1756 - H1761. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. B. Foster, T. Noguchi, P. VanBuren, A. M. Murphy, and J. E. Van Eyk C-Terminal Truncation of Cardiac Troponin I Causes Divergent Effects on ATPase and Force: Implications for the Pathophysiology of Myocardial Stunning Circ. Res., November 14, 2003; 93(10): 917 - 924. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Venkatraman, K. Harada, A. V. Gomes, W. G. L. Kerrick, and J. D. Potter Different Functional Properties of Troponin T Mutants That Cause Dilated Cardiomyopathy J. Biol. Chem., October 24, 2003; 278(43): 41670 - 41676. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Siedner, M. Kruger, M. Schroeter, D. Metzler, W. Roell, B. K Fleischmann, J. Hescheler, G. Pfitzer, and R. Stehle Developmental changes in contractility and sarcomeric proteins from the early embryonic to the adult stage in the mouse heart J. Physiol., April 15, 2003; 548(2): 493 - 505. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. G. Dos Remedios, D. Chhabra, M. Kekic, I. V. Dedova, M. Tsubakihara, D. A. Berry, and N. J. Nosworthy Actin Binding Proteins: Regulation of Cytoskeletal Microfilaments Physiol Rev, April 1, 2003; 83(2): 433 - 473. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Miller, J. Maycock, E. White, M. Peckham, and S. Calaghan Heterologous expression of wild-type and mutant {beta}-cardiac myosin changes the contractile kinetics of cultured mouse myotubes J. Physiol., April 1, 2003; 548(1): 167 - 174. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Robinson, M. Mirza, A. Knott, H. Abdulrazzak, R. Willott, S. Marston, H. Watkins, and C. Redwood Alterations in Thin Filament Regulation Induced by a Human Cardiac Troponin T Mutant That Causes Dilated Cardiomyopathy Are Distinct from Those Induced by Troponin T Mutants That Cause Hypertrophic Cardiomyopathy J. Biol. Chem., October 18, 2002; 277(43): 40710 - 40716. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Fatkin and R. M. Graham Molecular Mechanisms of Inherited Cardiomyopathies Physiol Rev, October 1, 2002; 82(4): 945 - 980. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. D. Barrans, P. D. Allen, D. Stamatiou, V. J. Dzau, and C.-C. Liew Global Gene Expression Profiling of End-Stage Dilated Cardiomyopathy Using a Human Cardiovascular-Based cDNA Microarray Am. J. Pathol., June 1, 2002; 160(6): 2035 - 2043. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. H. Marden, G. H. Fitzhugh, M. Girgenrath, M. R. Wolf, and S. Girgenrath Alternative splicing, muscle contraction and intraspecific variation: associations between troponin T transcripts, Ca2+ sensitivity and the force and power output of dragonfly flight muscles during oscillatory contraction J. Exp. Biol., March 12, 2002; 204(20): 3457 - 3470. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Morimoto, Q.-W. Lu, K. Harada, F. Takahashi-Yanaga, R. Minakami, M. Ohta, T. Sasaguri, and I. Ohtsuki Ca2+-desensitizing effect of a deletion mutation Delta K210 in cardiac troponin T that causes familial dilated cardiomyopathy PNAS, January 1, 2002; (2002) 22628899. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. E Montgomery, J. C Tardiff, and M. Chandra Cardiac troponin T mutations: correlation between the type of mutation and the nature of myofilament dysfunction in transgenic mice J. Physiol., October 15, 2001; 536(2): 583 - 592. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. B. Harrap and S. Petrou Utility of genetic approaches to common cardiovascular diseases Am J Physiol Heart Circ Physiol, July 1, 2001; 281(1): H1 - H6. [Full Text] [PDF]
|
|
|
|
 |
|
 O. M. Hernandez, P. R. Housmans, and J. D. Potter Plasticity in Skeletal, Cardiac, and Smooth Muscle: Invited Review: Pathophysiology of cardiac muscle contraction and relaxation as a result of alterations in thin filament regulation J Appl Physiol, March 1, 2001; 90(3): 1125 - 1136. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Elliott, H. Watkins, and C. S. Redwood Altered Regulatory Properties of Human Cardiac Troponin I Mutants That Cause Hypertrophic Cardiomyopathy J. Biol. Chem., July 14, 2000; 275(29): 22069 - 22074. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Burhop, M. Rosol, R. Craig, L. S. Tobacman, and W. Lehman Effects of a Cardiomyopathy-causing Troponin T Mutation on Thin Filament Function and Structure J. Biol. Chem., June 1, 2001; 276(23): 20788 - 20794. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Morimoto, Q.-W. Lu, K. Harada, F. Takahashi-Yanaga, R. Minakami, M. Ohta, T. Sasaguri, and I. Ohtsuki Ca2+-desensitizing effect of a deletion mutation Delta K210 in cardiac troponin T that causes familial dilated cardiomyopathy PNAS, January 22, 2002; 99(2): 913 - 918. [Abstract] [Full Text] [PDF]
|
|