Dilated cardiomyopathy (DCM) is often associated with sarcomere protein mutations that confer reduced myofilament tension-generating capacity. We demonstrate that cardiac twitch tension-time integrals can be targeted and tuned to prevent DCM remodeling in hearts with contractile dysfunction. We employ a transgenic murine model of DCM caused by the D230N tropomyosin (Tm) mutation and design a sarcomere-based intervention specifically targeting the twitch tension-time integral of D230N-Tm hearts using multiscale computational models of intra- and inter-molecular interactions in the thin filament and cell-level contractile simulations. Our models predict that increasing the calcium-sensitivity of thin filament activation using the cardiac troponin C (cTnC) variant L48Q can sufficiently augment twitch tension-time integrals of D230N-Tm hearts. Indeed, cardiac muscle isolated from double-transgenic (DTG) hearts expressing D230N Tm and L48Q cTnC have increased calcium-sensitivity of tension development and increased twitch tension-time integrals compared to preparations from hearts with D230N Tm alone. Longitudinal echocardiographic measurements revealed that DTG hearts retain normal cardiac morphology and function, while D230N-Tm hearts develop progressive DCM. We present a computational and experimental framework for targeting molecular mechanisms governing the twitch tension of cardiomyopathic hearts to counteract putative mechanical drivers of adverse remodeling, and open new possibilities for tension-based treatments of genetic cardiomyopathies.
Joseph D. Powers, Kristina B. Kooiker, Allison B. Mason, Abigail E. Teitgen, Galina V. Flint, Jil C. Tardiff, Steven D. Schwartz, Andrew D. McCulloch, Michael Regnier, Jennifer Davis, Farid Moussavi-Harami
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