scholarly journals Engineering Synthetic DNA Nanotube Thick Filaments to Dissect Beta-Cardiac Myosin and Cardiac Myosin-Binding Protein C Interactions

2020 ◽  
Vol 118 (3) ◽  
pp. 426a
Author(s):  
Anja M. Touma ◽  
Ashim Rai ◽  
Christopher M. Yengo ◽  
Samantha B. Previs ◽  
David M. Warshaw ◽  
...  
Keyword(s):  
Protein C ◽  
Binding Protein ◽  
Cardiac Myosin ◽  
Synthetic Dna ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Thick Filaments ◽  
Myosin Binding ◽  
Dna Nanotube

scholarly journals Phosphorylation of cardiac myosin binding protein C releases myosin heads from the surface of cardiac thick filaments

2017 ◽  
Vol 114 (8) ◽  
pp. E1355-E1364 ◽  
Author(s):  
Robert W. Kensler ◽  
Roger Craig ◽  
Richard L. Moss
Keyword(s):  
Protein C ◽  
Structural Changes ◽  
Binding Protein ◽  
Cardiac Contraction ◽  
Cardiac Myosin ◽  
Cross Bridge ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Thick Filaments ◽  
Myosin Binding

Cardiac myosin binding protein C (cMyBP-C) has a key regulatory role in cardiac contraction, but the mechanism by which changes in phosphorylation of cMyBP-C accelerate cross-bridge kinetics remains unknown. In this study, we isolated thick filaments from the hearts of mice in which the three serine residues (Ser273, Ser282, and Ser302) that are phosphorylated by protein kinase A in the m-domain of cMyBP-C were replaced by either alanine or aspartic acid, mimicking the fully nonphosphorylated and the fully phosphorylated state of cMyBP-C, respectively. We found that thick filaments from the cMyBP-C phospho-deficient hearts had highly ordered cross-bridge arrays, whereas the filaments from the cMyBP-C phospho-mimetic hearts showed a strong tendency toward disorder. Our results support the hypothesis that dephosphorylation of cMyBP-C promotes or stabilizes the relaxed/superrelaxed quasi-helical ordering of the myosin heads on the filament surface, whereas phosphorylation weakens this stabilization and binding of the heads to the backbone. Such structural changes would modulate the probability of myosin binding to actin and could help explain the acceleration of cross-bridge interactions with actin when cMyBP-C is phosphorylated because of, for example, activation of β1-adrenergic receptors in myocardium.

Abstract 376: Amino Terminal C0-C1f Region of Cardiac Myosin Binding Protein-C is Essential for Normal Cardiac Function

2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Thomas L Lynch ◽  
Diederik W Kuster ◽  
David Barefield ◽  
Mayandi Sivaguru ◽  
Michael J Previs ◽  
...  
Keyword(s):  
Cardiac Function ◽  
Protein C ◽  
Binding Protein ◽  
Cardiac Myosin ◽  
Amino Terminal ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Thick Filaments ◽  
Myosin Binding

Rationale: Cardiac myosin binding protein-C (cMyBP-C) is a trans-filament protein that has been shown to regulate cardiac function via its amino terminal (N’) regions. However, it is unknown whether the first 271 residues (C0-C1f region) are necessary to regulate contractile function in vivo. Hypothesis: The N’-region of cMyBP-C is critical for proper cardiac function in vivo. Methods and Results: Transgenic mice with approximately 80% expression of mutant truncated cMyBP-C missing C0-C1f (cMyBP-C 110kDa ), compared to endogenous cMyBP-C, were generated and characterized at 3-months of age. cMyBP-C 110kDa hearts had significantly elevated heart weight/body weight ratio, fibrosis, nuclear area and collagen content compared to hearts from non-transgenic (NTG) littermates. Electron microscopic analysis revealed normal sarcomere structure in cMyBP-C 110kDa hearts but with apparently weaker cMyBP-C stripes. Furthermore, the ability of cMyBP-C to slow actin-filament sliding within the C-zone of native thick filaments isolated from NTG hearts was lost on thick filaments from cMyBP-C 110kDa hearts. Short axis M-mode echocardiography revealed a significant increase in left ventricular (LV) internal diameter during diastole in cMyBP-C 110kDa hearts. Importantly, cMyBP-C 110kDa hearts displayed a significant reduction in fractional shortening compared to hearts from NTG littermates. We further observed a decrease in the thickness of the LV interventricular septum and free wall during systole in cMyBP-C 110kDa hearts. Strain analysis using images acquired from ECG-Gated Kilohertz Visualization identified a significant deficit in global longitudinal strain in cMyBP-C 110kDa hearts compared to NTG hearts. Conclusion: The N’-region of cMyBP-C is indispensable for maintaining normal cardiac morphology and function and loss of this region promotes contractile dysfunction both at the molecular and tissue levels.

scholarly journals Molecular Mechanics of Cardiac Myosin-Binding Protein C in Native Thick Filaments

Science ◽  
2012 ◽  
Vol 337 (6099) ◽  
pp. 1215-1218 ◽  
Author(s):  
M. J. Previs ◽  
S. B. Previs ◽  
J. Gulick ◽  
J. Robbins ◽  
D. M. Warshaw
Keyword(s):  
Molecular Mechanics ◽  
Protein C ◽  
Binding Protein ◽  
Cardiac Myosin ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Thick Filaments ◽  
Myosin Binding

scholarly journals The Structural and Biomechanical Properties of Insect Thick Filaments Expressing Flightin and Cardiac Myosin Binding Protein-C

2013 ◽  
Vol 19 (S2) ◽  
pp. 80-81
Author(s):  
L. Menard ◽  
L. Nyland ◽  
J. Vigoreaux
Keyword(s):  
Protein C ◽  
Binding Protein ◽  
Biomechanical Properties ◽  
Cardiac Myosin ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Thick Filaments ◽  
Myosin Binding

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

scholarly journals Site-specific phosphorylation of myosin binding protein-C coordinates thin and thick filament activation in cardiac muscle

2019 ◽  
Vol 116 (31) ◽  
pp. 15485-15494 ◽  
Author(s):  
Saraswathi Ponnam ◽  
Ivanka Sevrieva ◽  
Yin-Biao Sun ◽  
Malcolm Irving ◽  
Thomas Kampourakis
Keyword(s):  
Signaling Pathways ◽  
Protein C ◽  
Binding Protein ◽  
Cardiac Myosin ◽  
Thin Filaments ◽  
Site Specific ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Thick Filaments ◽  
Myosin Binding

The heart’s response to varying demands of the body is regulated by signaling pathways that activate protein kinases which phosphorylate sarcomeric proteins. Although phosphorylation of cardiac myosin binding protein-C (cMyBP-C) has been recognized as a key regulator of myocardial contractility, little is known about its mechanism of action. Here, we used protein kinase A (PKA) and Cε (PKCε), as well as ribosomal S6 kinase II (RSK2), which have different specificities for cMyBP-C’s multiple phosphorylation sites, to show that individual sites are not independent, and that phosphorylation of cMyBP-C is controlled by positive and negative regulatory coupling between those sites. PKA phosphorylation of cMyBP-C’s N terminus on 3 conserved serine residues is hierarchical and antagonizes phosphorylation by PKCε, and vice versa. In contrast, RSK2 phosphorylation of cMyBP-C accelerates PKA phosphorylation. We used cMyBP-C’s regulatory N-terminal domains in defined phosphorylation states for protein–protein interaction studies with isolated cardiac native thin filaments and the S2 domain of cardiac myosin to show that site-specific phosphorylation of this region of cMyBP-C controls its interaction with both the actin-containing thin and myosin-containing thick filaments. We also used fluorescence probes on the myosin-associated regulatory light chain in the thick filaments and on troponin C in the thin filaments to monitor structural changes in the myofilaments of intact heart muscle cells associated with activation of myocardial contraction by the N-terminal region of cMyBP-C in its different phosphorylation states. Our results suggest that cMyBP-C acts as a sarcomeric integrator of multiple signaling pathways that determines downstream physiological function.

scholarly journals Multiple Forms of Cardiac Myosin-binding Protein C Exist and Can Regulate Thick Filament Stability

2007 ◽  
Vol 129 (5) ◽  
pp. 419-428 ◽  
Author(s):  
Irina Kulikovskaya ◽  
George B. McClellan ◽  
Rhea Levine ◽  
Saul Winegrad
Keyword(s):  
Protein C ◽  
Heart Function ◽  
Binding Protein ◽  
Thick Filament ◽  
Stable Form ◽  
Cardiac Myosin ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Thick Filaments ◽  
Myosin Binding

Although absence or abnormality of cardiac myosin binding protein C (cMyBP-C) produces serious structural and functional abnormalities of the heart, function of the protein itself is not clearly understood, and the cause of the abnormalities, unidentified. Here we report that a major function of cMyBP-C may be regulating the stability of the myosin-containing contractile filaments through phosphorylation of cMyBP-C. Antibodies were raised against three different regions of cMyBP-C to detect changes in structure within the molecule, and loss of myosin heavy chain was used to monitor degradation of the thick filament. Results from Western blotting and polyacrylamide gel electrophoresis indicate that cMyBP-C can exist in two different forms that produce, respectively, stable and unstable thick filaments. The stable form has well-ordered myosin heads and requires phosphorylation of the cMyBP-C. The unstable form has disordered myosin heads. In tissue with intact cardiac cells, the unstable unphosphorylated cMyBP-C is more easily proteolyzed, causing thick filaments first to release cMyBP-C and/or its proteolytic peptides and then myosin. Filaments deficient in cMyBP-C are fragmented by shear force well tolerated by the stable form. We hypothesize that modulation of filament stability can be coupled at the molecular level with the strength of contraction by the sensitivity of each to the concentration of calcium ions.

ID: 136: N-TERMINAL REGION OF CARDIAC MYOSIN BINDING PROTEIN-C IS NECESSARY FOR CARDIAC FUNCTION

2016 ◽  
Vol 64 (4) ◽  
pp. 911.2-912
Author(s):  
M Sivaguru ◽  
TL Lynch ◽  
DW Kuster ◽  
S Govindan ◽  
S Sadayappan ◽  
...  
Keyword(s):  
Cardiac Function ◽  
Actin Filament ◽  
Protein C ◽  
Binding Protein ◽  
Cardiac Myosin ◽  
Myosin Binding Protein ◽  
Myosin Binding Protein C ◽  
Thick Filaments ◽  
Myosin Binding

RationaleCardiac myosin binding protein-C (cMyBP-C) is a trans-filament protein that has been shown to regulate cardiac function via its amino terminal (N′) region. In vitro studies have suggested the importance of the first 271 N′-residues of cMyBP-C (C0-C1f region) in slowing actin filament sliding over myosin to regulate cross-bridge cycling kinetics within the cardiac sarcomere. However, the role and necessity of the C0-C1f region of cMyBP-C in regulating contractile and cardiac function in vivo have not been elucidated.HypothesisThe N′-C0-C1f region of cMyBP-C is critical for proper cardiac function in vivo.Methods and ResultsTransgenic mice with approximately 95% expression of a mutant truncated cMyBP-C missing the N′-C0-C1f region (cMyBP-C110 kDa), compared to endogenous cMyBP-C, were generated and characterized at 3-months of age. cMyBP-C110 kDa hearts had significantly elevated heart weight/body weight ratio, fibrosis, nuclear area and collagen content compared to hearts from non-transgenic (NTG) littermates. Electron microscopic analysis revealed normal sarcomere structure in cMyBP-C110 kDa hearts but with apparently weaker cMyBP-C stripes. Furthermore, the ability of cMyBP-C to slow actin-filament sliding within the C-zone of native thick filaments isolated from NTG hearts was lost on thick filaments from cMyBP-C110 kDa hearts. Short axis M-mode echocardiography revealed a significant increase in left ventricular (LV) internal diameter during diastole in cMyBP-C110 kDa hearts. Importantly, cMyBP-C110 kDa hearts displayed a significant reduction in fractional shortening compared to hearts from NTG mice. We further observed a decrease in the thickness of the LV interventricular septum and free wall during systole in cMyBP-C110 kDa hearts. Strain analysis using images acquired from ECG-Gated Kilohertz Visualization identified a significant deficit in global longitudinal strain in cMyBP-C110 kDa hearts compared to NTG hearts. Consistent with cardiac hypertrophy, we observed a significant increase in the expression of the hypertrophic genes MYH7 and NPPA by real-time PCR analysis. As expected, the expression levels of the MYBPC3 gene were significantly elevated in cMyBP-C110 kDa hearts compared to NTG hearts. Surprisingly, our Western blot analyses revealed no significant difference in total cMyBP-C levels between NTG and cMyBP-C110 kDa heart homogenates. However, intriguingly, we observed a significant elevation in cMyBP-C phosphorylation at Ser-273, Ser-282, and Ser-302, sites important for cMyBP-C's regulation of actomyosin interaction, in cMyBP-C110 kDa heart homogenates compared to those from NTG mice.ConclusionThe N′-C0-C1f region of cMyBP-C is essential for maintaining normal cardiac morphology and function in vivo and loss of this region promotes contractile dysfunction both at the molecular and tissue level.

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