Cardiac Myosin Binding Protein-C (cMyBP-C) is critical to normal cardiac performance as evidenced by genetic mutations in cMyBP-C being one of the leading causes of familial hypertrophic cardiomyopathy. Despite its functional importance, the molecular mechanism by which cMyBP-C exerts its effect on the myosin molecular motor as it interacts with actin to generate force and motion remains largely undefined. A yet unanswered question is with its low ratio relative to myosin and it being located in distinct regions of the thick filament, we will determine how cMyBP-C's modulates actomyosin's power generation by interacting with only a limited population of crossbridges within the thick filament. To address this in Aim #1, we will use state-of- the-art single molecule biophysical techniques (e.g. laser trap assay) to probe the effect that cMyBP-C exerts on actomyosin function along the length a single native thick filament.
In Aim #2, we will use expressed N-terminal fragments of cMyBP-C to probe the binding affinity of these fragments for actin, the regulated thin filament, and/or myosin. In combination with motility and laser trap assays, we will determine if the N- terminus of CMyBP-C limits myosin's attachment rate to the thin filament or if it directly affects myosin's inherent molecular mechanics and kinetics. Finally, in Aim #3 we will characterize how phosphorylation regulates cMyBP-C action. Using existing transgenic mouse models expressing cMyBP C mutants having alanine or aspartic acid substitutions for all three phosphorylatable serines, we will determine the functional importance of phosphorylation using native thick filaments containing mutant cMyBP-C as well as N-terminal fragments having the same mutations. Once the molecular mechanism of cMyBP-C is defined, the potential for novel therapeutics or clinical intervention may be possible in cases of heart failure associated with genetic mutations in cMyBP-C.

Public Health Relevance

Cardiac Myosin Binding Protein-C (cMyBP-C) is critical to normal cardiac performance as evidenced by genetic mutations in cMyBP-C being one of the leading causes of familial hypertrophic cardiomyopathy. Despite its functional importance, the molecular mechanism by which cMyBP-C exerts its effect on the myosin molecular motor as it interacts with actin to generate force and motion remains largely undefined.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL086728-02
Application #
7665569
Study Section
Cardiac Contractility, Hypertrophy, and Failure Study Section (CCHF)
Program Officer
Przywara, Dennis
Project Start
2008-08-01
Project End
2010-02-01
Budget Start
2009-05-31
Budget End
2010-02-01
Support Year
2
Fiscal Year
2009
Total Cost
$253,250
Indirect Cost
Name
University of Vermont & St Agric College
Department
Physiology
Type
Schools of Medicine
DUNS #
066811191
City
Burlington
State
VT
Country
United States
Zip Code
05405
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Saber, Walid; Begin, Kelly J; Warshaw, David M et al. (2008) Cardiac myosin binding protein-C modulates actomyosin binding and kinetics in the in vitro motility assay. J Mol Cell Cardiol 44:1053-61