The sarcomere is the molecular motor of the heart. Contraction of the heart is finely tuned by regulatory proteins and in particular troponin I on the thin filament of the sarcomere. Cardiac troponin I function is modified by multiple post-translational modifications, including novel modifications we recently discovered. Modifications of troponin I are altered in heart failure and hypertrophic cardiomyopathy, a genetic disease of sarcomeric proteins. The investigator's laboratory has a long-term interest in post-translational changes in the myofilament proteins which contribute to systolic and diastolic dysfunction. The laboratory continues to focus on understanding the precise quantification of site specific post-translational modifications and the functional significance of specific modifications of troponin I This proposal will test hypotheses that post- translational modifications and disease allele specific protein expression in hypertrophic cardiomyopathy underlie some of the pathophysiologic manifestations of disease, and that novel phosphorylation sites on troponin I contribute to contractile pathophysiology in heart failure and hypertrophy.
The aims i nclude translational proteomics experiments to quantify mutant allele expression and hypertrophic cardiomyopathy associated phosphorylation alterations and linking these directly to function in human cardiomyocytes. Two novel TnI phosphorylations, discovered in the prior cycle, which are relevant to the heart failure phenotype, will also be functionally evaluated. These studies wil produce new therapeutic strategies which may target and compensate for these functional changes in hypertrophic as well as dilated cardiomyopathy and heart failure.

Public Health Relevance

These studies are relevant to important clinical problems including heart failure and hypertrophic cardiomyopathy. Heart failure is a common disorder that affects an estimated 6 million people in the United States. Heart failure has estimated survival of only 50% within 5 years after diagnosis. Hypertrophic cardiomyopathy is a common genetic disease affecting 1/500 people and is the most common cause of sudden cardiac death in young athletes.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL063038-17
Application #
9458236
Study Section
Myocardial Ischemia and Metabolism Study Section (MIM)
Program Officer
Adhikari, Bishow B
Project Start
1999-09-13
Project End
2019-03-31
Budget Start
2018-04-01
Budget End
2019-03-31
Support Year
17
Fiscal Year
2018
Total Cost
Indirect Cost
Name
Johns Hopkins University
Department
Pediatrics
Type
Schools of Medicine
DUNS #
001910777
City
Baltimore
State
MD
Country
United States
Zip Code
21205
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Li, Yuejin; Zhu, Guangshuo; Paolocci, Nazareno et al. (2017) Heart Failure-Related Hyperphosphorylation in the Cardiac Troponin I C Terminus Has Divergent Effects on Cardiac Function In Vivo. Circ Heart Fail 10:
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Wijnker, Paul J M; Li, Yuejin; Zhang, Pingbo et al. (2015) A novel phosphorylation site, Serine 199, in the C-terminus of cardiac troponin I regulates calcium sensitivity and susceptibility to calpain-induced proteolysis. J Mol Cell Cardiol 82:93-103
Wijnker, Paul J M; Sequeira, Vasco; Foster, D Brian et al. (2014) Length-dependent activation is modulated by cardiac troponin I bisphosphorylation at Ser23 and Ser24 but not by Thr143 phosphorylation. Am J Physiol Heart Circ Physiol 306:H1171-81
Wijnker, Paul J M; Sequeira, Vasco; Witjas-Paalberends, E Rosalie et al. (2014) Phosphorylation of protein kinase C sites Ser42/44 decreases Ca(2+)-sensitivity and blunts enhanced length-dependent activation in response to protein kinase A in human cardiomyocytes. Arch Biochem Biophys 554:11-21

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