RT Journal Article
SR Electronic
T1 Hypertrophic cardiomyopathy ß-cardiac myosin mutation (P710R) leads to hypercontractility by disrupting super-relaxed state: multiscale measurements and computational modeling
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.11.10.375493
DO 10.1101/2020.11.10.375493
A1 Alison Schroer Vander Roest
A1 Chao Liu
A1 Makenna M Morck
A1 Kristina Bezold Kooiker
A1 Gwanghyun Jung
A1 Dan Song
A1 Aminah Dawood
A1 Arnav Jhingran
A1 Gaspard Pardon
A1 Sara Ranjbarvaziri
A1 Giovanni Fajardo
A1 Mingming Zhao
A1 Kenneth S Campbell
A1 Beth L Pruitt
A1 James Spudich
A1 Kathleen M Ruppel
A1 Daniel Bernstein
YR 2020
UL http://biorxiv.org/content/early/2020/11/10/2020.11.10.375493.abstract
AB Hypertrophic cardiomyopathy (HCM) is the most common inherited form of heart disease, associated with over 1000 mutations, many in β-cardiac myosin (MYH7). Molecular studies of myosin with different HCM mutations have revealed a diversity of effects on ATPase and load-sensitive rate of detachment from actin. It has been difficult to predict how such diverse molecular effects combine to influence forces at the cellular level and further influence cellular phenotypes. This study focused on the P710R mutation that dramatically decreases in vitro motility and actin-activated ATPase, in contrast to other MYH7 mutations. Optical trap measurements of single myosin molecules revealed that this mutation reduced the step size of the myosin motor and the load-sensitivity of the actin detachment rate. Conversely, this mutation destabilized the super-relaxed state in larger, two-headed myosin constructs, freeing more heads to generate force. Micropatterned hiPSC-cardiomyocytes CRISPR-edited with the P710R mutation produced significantly increased force (measured by traction force microscopy) compared with isogenic control cells. The P710R mutation also caused cardiomyocyte hypertrophy and cytoskeletal remodeling, as measured by immunostaining and electron microscopy. Cellular hypertrophy was prevented in the P710R cells by inhibition of ERK or Akt. Finally, we used a computational model that integrates measured molecular changes to demonstrate that closely predict the measured traction forces. These results confirm a key role for regulation of the super-relaxed state in driving hypercontractility in HCM and demonstrate the value of a multiscale approach in revealing key mechanisms of disease.Significance Statement Heart disease is the leading cause of death world wide, and hypertrophic cardiomyopathy (HCM) is the most common inherited form of heart disease, affecting over 1 in 200 people. Mutations in myosin, the motor protein responsible for contraction of the heart, are a common cause of HCM but have diverse effects on the biomechanics of the myosin protein that can make it difficult to predict the combined effects of each mutation. We demonstrate that complex biomechanical effects of mutations associated with heart disease can be effectively studied and understood using a multi-scale experimental and computational modeling approach. This work can be extended to aid in the development of new targeted therapies for patients with different mutations.Competing Interest StatementThe authors have declared no competing interest.