Heart failure can be a result of impaired cardiac contraction or relaxation or both, which are regulated by Ca2+induced thin filament activation and deactivation. Therefore, understanding the mechanism of thin filament regulation is of great importance in prevention and treatment of heart failure. The molecular basis of the thin filament regulation involves Ca2+induced alterations in the structure and structural kinetics and dynamics associated with the protein-protein interactions at the interface between troponin and actin. The objective of this proposal is to define the detailed kinetic mechanism that underlies Ca2+induced thin filament activation/deactivation and how it is affected by troponin phosphorylation and cardiomyopathy mutations found in cTnI. To achieve the goal, this proposal will address the following questions: 1) What is the kinetic role of different functional regions of cTnI in regulating crossbridge kinetics? 2) How do the structural dynamics of the cTnI C-domain play roles in thin filament regulation? and 3) How are the structural changes and structural kinetics of the thin filament modified in the skinned muscle fibers and myofibrils? The underlying hypothesis of this proposal is that the Ca2+induced structural transitions involving the different regions of troponin I at the interface between troponin and actin play different roles in regulating kinetics of the interaction between actin and mysoin, and the structural transitions can be affected by strong crossbridges, cardiomyopathy mutations, and phosphorylation of troponin proteins, as well as cellular lattice environment found in intact muscle cells. This project capitalizes on our FRET and fluorescence anisotropy expertise in determining protein structural kinetics and dynamics to exploit a new approach by implementing FRET methodologies into muscle fibers and myofibril measurements. This will enable us to acquire the urgently needed kinetic and dynamic information associated with the Ca2+induced thin filament regulation on muscle function. The results from this study will have a positive impact by advancing our understanding of the regulatory role of cardiac thin filament in cardiac muscle contraction and relaxation in health and disease.
The objective of this proposal is to define the detailed kinetic mechanism that underlies Ca2+induced thin filament activation/deactivation and how it is affected by troponin phosphorylation and cardiomyopathy mutations found in cTnI. This application is related to research to improve depressed cardiac contractility under pathological conditions.
|Bohlooli Ghashghaee, Nazanin; Li, King-Lun; Solaro, R John et al. (2018) Role of the C-terminus mobile domain of cardiac troponin I in the regulation of thin filament activation in skinned papillary muscle strips. Arch Biochem Biophys 648:27-35|
|Schlecht, William; Dong, Wen-Ji (2017) Dynamic Equilibrium of Cardiac Troponin C's Hydrophobic Cleft and Its Modulation by Ca2+ Sensitizers and a Ca2+ Sensitivity Blunting Phosphomimic, cTnT(T204E). Bioconjug Chem 28:2581-2590|
|Bohlooli Ghashghaee, Nazanin; Tanner, Bertrand C W; Dong, Wen-Ji (2017) Functional significance of C-terminal mobile domain of cardiac troponin I. Arch Biochem Biophys 634:38-46|
|Li, King-Lun; Ghashghaee, Nazanin Bohlooli; Solaro, R John et al. (2016) Sarcomere length dependent effects on the interaction between cTnC and cTnI in skinned papillary muscle strips. Arch Biochem Biophys 601:69-79|
|Pulcastro, Hannah C; Awinda, Peter O; Methawasin, Mei et al. (2016) Increased Titin Compliance Reduced Length-Dependent Contraction and Slowed Cross-Bridge Kinetics in Skinned Myocardial Strips from Rbm (20?RRM) Mice. Front Physiol 7:322|
|Schlecht, William; Li, King-Lun; Hu, Dehong et al. (2016) Fluorescence Based Characterization of Calcium Sensitizer Action on the Troponin Complex. Chem Biol Drug Des 87:171-81|
|Schlecht, William; Zhou, Zhiqun; Li, King-Lun et al. (2014) FRET study of the structural and kinetic effects of PKC phosphomimetic cardiac troponin T mutants on thin filament regulation. Arch Biochem Biophys 550-551:1-11|
|Jayasundar, Jayant James; Xing, Jun; Robinson, John M et al. (2014) Molecular dynamics simulations of the cardiac troponin complex performed with FRET distances as restraints. PLoS One 9:e87135|
|Li, King-Lun; Rieck, Daniel; Solaro, R John et al. (2014) In situ time-resolved FRET reveals effects of sarcomere length on cardiac thin-filament activation. Biophys J 107:682-693|
|Jacroux, Thomas; Bottenus, Danny; Rieck, Bennett et al. (2014) Cationic isotachophoresis separation of the biomarker cardiac troponin I from a high-abundance contaminant, serum albumin. Electrophoresis 35:2029-38|
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