Structural and functional impact of troponin C-mediated Ca2+ sensitization on myofilament lattice spacing and cross-bridge mechanics in mouse cardiac muscle
Journal Article
·
· Journal of Molecular and Cellular Cardiology
- Florida State Univ., Tallahassee, FL (United States). Dept. of Biomedical Sciences
- Illinois Inst. of Technology, Chicago, IL (United States). Dept. of Biological Sciences
- Illinois Inst. of Technology, Chicago, IL (United States). Dept. of Biological Sciences; Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS), X-Ray Science Division
- Florida State Univ., Tallahassee, FL (United States). Dept. of Biological Science
Acto-myosin cross-bridge kinetics are important for beat-to-beat regulation of cardiac contractility; however, physiological and pathophysiological mechanisms for regulation of contractile kinetics are incompletely understood. Here we explored whether thin filament-mediated Ca2+ sensitization influences cross-bridge kinetics in permeabilized, osmotically compressed cardiac muscle preparations. We used a murine model of hypertrophic cardiomyopathy (HCM) harboring a cardiac troponin C (cTnC) Ca2+-sensitizing mutation, Ala8Val in the regulatory N-domain. We also treated wild-type murine muscle with bepridil, a cTnC-targeting Ca2+ sensitizer. Our findings suggest that both methods of increasing myofilament Ca2+ sensitivity increase cross-bridge cycling rate measured by the rate of tension redevelopment (kTR); force per cross-bridge was also enhanced as measured by sinusoidal stiffness and I1,1-1/I1,0 ratio from X-ray diffraction. Computational modeling suggests that Ca2+ sensitization through this cTnC mutation or bepridil accelerates kTR primarily by promoting faster cross-bridge detachment. To elucidate if myofilament structural rearrangements are associated with changes in k(TR), we used small angle X-ray diffraction to simultaneously measure myofilament lattice spacing and isometric force during steady-state Ca2+ activations. Within in vivo lattice dimensions, lattice spacing and steady-state isometric force increased significantly at submaximal activation. We conclude that the cTnC N-domain controls force by modulating both the number and rate of cycling cross-bridges, and that the both methods of Ca2+ sensitization may act through stabilization of cTnC's D-helix. Furthermore, we propose that the transient expansion of the myofilament lattice during Ca2+ activation may be an additional factor that could increase the rate of cross-bridge cycling in cardiac muscle. These findings may have implications for the pathophysiology of HCM.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- National Institutes of Health (NIH); USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- Grant/Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1505173
- Alternate ID(s):
- OSTI ID: 1691653
OSTI ID: 1478093
- Journal Information:
- Journal of Molecular and Cellular Cardiology, Journal Name: Journal of Molecular and Cellular Cardiology Journal Issue: C Vol. 123; ISSN 0022-2828
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Sexual dimorphism in cardiac transcriptome associated with a troponin C murine model of hypertrophic cardiomyopathy
|
journal | March 2020 |
Cardiomyocyte nuclearity and ploidy: when is double trouble?
|
journal | July 2019 |
Basic residues within the cardiac troponin T C terminus are required for full inhibition of muscle contraction and limit activation by calcium
|
journal | November 2019 |
The intrinsically disordered C terminus of troponin T binds to troponin C to modulate myocardial force generation
|
journal | November 2019 |
Similar Records
Disruption of Z-Disc Function Promotes Mechanical Dysfunction in Human Myocardium: Evidence for a Dual Myofilament Modulatory Role by Alpha-Actinin 2
Thick-to-Thin Filament Surface Distance Modulates Cross-Bridge Kinetics in Drosophila Flight Muscle
Myofilament length dependent activation
Journal Article
·
Mon Sep 25 20:00:00 EDT 2023
· International Journal of Molecular Sciences (Online)
·
OSTI ID:2470122
Thick-to-Thin Filament Surface Distance Modulates Cross-Bridge Kinetics in Drosophila Flight Muscle
Journal Article
·
Wed Sep 19 00:00:00 EDT 2012
· Biophysical Journal
·
OSTI ID:1051124
Myofilament length dependent activation
Journal Article
·
Tue May 25 00:00:00 EDT 2010
· J. Mol. Cell. Cardiol.
·
OSTI ID:1002388