The molecular mechanism by which cMyBP-C exerts its effect on actomyosin force power generating system remains largely undefined. With its low ratio relative to myosin and it being located in distinct regions of the thick filament, we will determine in this Project how cMyBP-C's modulates actomyosin's power generation by either interacting with a limited population of crossbridges or whether it cooperatively affects all crossbridges within the thick filament. This project serves as a physiological bridge between the animal (Project #3, Robbins), whole heart (Core B, Kass) and fiber (Core B, Palmer, Maughan) studies.
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 isolated from transgenic mice designed in Project #3 (Robbins) and produced in Core C (Robbins).
In Aim #2, we will use expressed N-terminal fragments of cMyBP-C produced in Core C (Robbins) to probe the binding affinity of these fragments for actin and/or myosin. Thus, these data and that obtained in Project #1 (Craig), Project #3 (Robbins) and Core B (Palmer) will help define cMyBP-C's specific binding partners (i.e. myosin and/or actin) and thus its physiological site of action. In combination with motility and laser trap assays, we will determine if the N-terminus of CMyBP-C limits myosin's attachment rate to actin 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 transgenic mouse models (Core C, Robbins) expressing cMyBP C mutants having alanine or aspartic acid substitutions for one or more of the three phosphorylatable serines, we will determine the functional importance of phosphorylation and the hierarchical importance of each site 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

cMyBP-C is critical to normal cardiac performance. Using single molecule biophysical techniques to characterize the molecular mechanism of cMyBP-C function, the results may provide the potential for novel therapies in cases of heart failure associated with genetic mutations in cMyBP-C.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Program Projects (P01)
Project #
5P01HL059408-15
Application #
8611947
Study Section
Heart, Lung, and Blood Initial Review Group (HLBP)
Project Start
Project End
Budget Start
2014-02-01
Budget End
2015-01-31
Support Year
15
Fiscal Year
2014
Total Cost
$728,269
Indirect Cost
$245,185
Name
University of Vermont & St Agric College
Department
Type
DUNS #
066811191
City
Burlington
State
VT
Country
United States
Zip Code
05405
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Tanner, Bertrand C W; Wang, Yuan; Robbins, Jeffrey et al. (2014) Kinetics of cardiac myosin isoforms in mouse myocardium are affected differently by presence of myosin binding protein-C. J Muscle Res Cell Motil 35:267-78
Wang, Xuejun; Robbins, Jeffrey (2014) Proteasomal and lysosomal protein degradation and heart disease. J Mol Cell Cardiol 71:16-24

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