scholarly journals Force Generation via β-Cardiac Myosin, Titin, and α-Actinin Drives Cardiac Sarcomere Assembly from Cell-Matrix Adhesions

2018 ◽  
Vol 44 (1) ◽  
pp. 87-96.e5 ◽  
Author(s):  
Anant Chopra ◽  
Matthew L. Kutys ◽  
Kehan Zhang ◽  
William J. Polacheck ◽  
Calvin C. Sheng ◽  
...  
Keyword(s):  
Force Generation ◽  
Cardiac Myosin ◽  
Cardiac Sarcomere ◽  
Cell Matrix ◽  
Sarcomere Assembly

scholarly journals Altered C10 domain in cardiac myosin binding protein-C results in hypertrophic cardiomyopathy

2019 ◽  
Vol 115 (14) ◽  
pp. 1986-1997 ◽  
Author(s):  
Diederik W D Kuster ◽  
Thomas L Lynch ◽  
David Y Barefield ◽  
Mayandi Sivaguru ◽  
Gina Kuffel ◽  
...  
Keyword(s):  
Hypertrophic Cardiomyopathy ◽  
Protein C ◽  
Binding Protein ◽  
Force Generation ◽  
Contractile Dysfunction ◽  
Cardiac Myosin ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Myosin Binding

Abstract Aims A 25-base pair deletion in the cardiac myosin binding protein-C (cMyBP-C) gene (MYBPC3), proposed to skip exon 33, modifies the C10 domain (cMyBP-CΔC10mut) and is associated with hypertrophic cardiomyopathy (HCM) and heart failure, affecting approximately 100 million South Asians. However, the molecular mechanisms underlying the pathogenicity of cMyBP-CΔC10mutin vivo are unknown. We hypothesized that expression of cMyBP-CΔC10mut exerts a poison polypeptide effect leading to improper assembly of cardiac sarcomeres and the development of HCM. Methods and results To determine whether expression of cMyBP-CΔC10mut is sufficient to cause HCM and contractile dysfunction in vivo, we generated transgenic (TG) mice having cardiac-specific protein expression of cMyBP-CΔC10mut at approximately half the level of endogenous cMyBP-C. At 12 weeks of age, significant hypertrophy was observed in TG mice expressing cMyBP-CΔC10mut (heart weight/body weight ratio: 4.43 ± 0.11 mg/g non-transgenic (NTG) vs. 5.34 ± 0.25 mg/g cMyBP-CΔC10mut, P < 0.05). Furthermore, haematoxylin and eosin, Masson’s trichrome staining, as well as second-harmonic generation imaging revealed the presence of significant fibrosis and a greater relative nuclear area in cMyBP-CΔC10mut hearts compared with NTG controls. M-mode echocardiography analysis revealed hypercontractile hearts (EF: 53.4%±2.9% NTG vs. 66.4% ± 4.7% cMyBP-CΔC10mut; P < 0.05) and early diastolic dysfunction (E/E′: 28.7 ± 3.7 NTG vs. 46.3 ± 8.4 cMyBP-CΔC10mut; P < 0.05), indicating the presence of an HCM phenotype. To assess whether these changes manifested at the myofilament level, contractile function of single skinned cardiomyocytes was measured. Preserved maximum force generation and increased Ca2+-sensitivity of force generation were observed in cardiomyocytes from cMyBP-CΔC10mut mice compared with NTG controls (EC50: 3.6 ± 0.02 µM NTG vs. 2.90 ± 0.01 µM cMyBP-CΔC10mut; P < 0.0001). Conclusion Expression of cMyBP-C protein with a modified C10 domain is sufficient to cause contractile dysfunction and HCM in vivo.

scholarly journals Vinculin-dependent actin bundling regulates cell migration and traction forces

2015 ◽  
Vol 465 (3) ◽  
pp. 383-393 ◽  
Author(s):  
Karry M. Jannie ◽  
Shawn M. Ellerbroek ◽  
Dennis W. Zhou ◽  
Sophia Chen ◽  
David J. Crompton ◽  
...  
Keyword(s):  
Cell Migration ◽  
Traction Force ◽  
Force Generation ◽  
Actin Binding ◽  
Traction Forces ◽  
Cell Matrix ◽  
Cell Cell

Vinculin transduces force and orchestrates mechanical signalling at cell–cell and cell–matrix adhesions. Cells expressing a mutant vinculin deficient in actin binding and bundling display migration and traction force defects. Vinculin binding to actin is critical for cell migration and force generation.

scholarly journals Author response: Single molecule mechanics resolves the earliest events in force generation by cardiac myosin

2019 ◽  
Author(s):  
Michael S Woody ◽  
Donald A Winkelmann ◽  
Marco Capitanio ◽  
E Michael Ostap ◽  
Yale E Goldman
Keyword(s):  
Single Molecule ◽  
Force Generation ◽  
Author Response ◽  
Cardiac Myosin

scholarly journals Electrostatic Interactions Within Loop 1 and the Force Generation Region of Human Cardiac Myosin Affect the Rate of Actomyosin Dissociation and ADP Release

2019 ◽  
Vol 116 (3) ◽  
pp. 259a-260a
Author(s):  
Akhil Gargey ◽  
Jinghua Ge ◽  
Alex Grdzelishvili ◽  
Yaroslav Tkachev ◽  
Yuri E. Nesmelov
Keyword(s):  
Electrostatic Interactions ◽  
Force Generation ◽  
Cardiac Myosin ◽  
Adp Release ◽  
Generation Region

scholarly journals Single molecule mechanics resolves the earliest events in force generation by cardiac myosin

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Michael S Woody ◽  
Donald A Winkelmann ◽  
Marco Capitanio ◽  
E Michael Ostap ◽  
Yale E Goldman
Keyword(s):  
Single Molecule ◽  
High Speed ◽  
Atp Hydrolysis ◽  
Optical Trap ◽  
Force Generation ◽  
Actin Binding ◽  
Cardiac Myosin ◽  
Phosphate Release ◽  
Hydrolysis Products ◽  
Key Steps

Key steps of cardiac mechanochemistry, including the force-generating working stroke and the release of phosphate (Pi), occur rapidly after myosin-actin attachment. An ultra-high-speed optical trap enabled direct observation of the timing and amplitude of the working stroke, which can occur within <200 μs of actin binding by β-cardiac myosin. The initial actomyosin state can sustain loads of at least 4.5 pN and proceeds directly to the stroke or detaches before releasing ATP hydrolysis products. The rates of these processes depend on the force. The time between binding and stroke is unaffected by 10 mM Pi which, along with other findings, indicates the stroke precedes phosphate release. After Pi release, Pi can rebind enabling reversal of the working stroke. Detecting these rapid events under physiological loads provides definitive indication of the dynamics by which actomyosin converts biochemical energy into mechanical work.

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