Normal cardiac contraction in mice lacking the proline-alanine rich region and C1 domain of cardiac myosin binding protein C

Sabine J. van Dijk, Christian C. Witt, Samantha P. Harris

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Cardiac myosin binding protein C (cMyBP-C) is an essential regulator of cross bridge cycling. Through mechanisms that are incompletely understood the N-terminal domains (NTDs) of cMyBP-C can activate contraction even in the absence of calcium and can also inhibit cross bridge kinetics in the presence of calcium. In vitro studies indicated that the proline-alanine rich (p/a) region and C1 domain are involved in these processes, although effects were greater using human proteins compared to murine proteins (Shaffer et al. J Biomed Biotechnol 2010, 2010: 789798). We hypothesized that the p/a and C1 region are critical for the timing of contraction. In this study we tested this hypothesis using a mouse model lacking the p/a and C1 region (p/a-C1-/- mice) to investigate the in vivo relevance of these regions on cardiac performance.Surprisingly, hearts of adult p/a-C1-/- mice functioned normally both on a cellular and whole organ level. Force measurements in permeabilized cardiomyocytes from adult p/a-C1-/- mice and wild type (Wt) littermate controls demonstrated similar rates of force redevelopment both at submaximal and maximal activation. Maximal and passive force and calcium sensitivity of force were comparable between groups as well. Echocardiograms showed normal isovolumetric contraction times, fractional shortening and ejection fraction, indicating proper systolic function in p/a-C1-/- mouse hearts. p/a-C1-/- mice showed a slight but significant reduction in isovolumetric relaxation time compared to Wt littermates, yet this difference disappeared in older mice (7-8months of age). Moreover, stroke volume was preserved in p/a-C1-/- mice, corroborating sufficient time for normal filling of the heart. Overall, the hearts of p/a-C1-/- mice showed no signs of dysfunction even after chronic stress with an adrenergic agonist.Together, these results indicate that the p/a region and the C1 domain of cMyBP-C are not critical for normal cardiac contraction in mice and that these domains have little if any impact on cross bridge kinetics in mice. These results thus contrast with in vitro studies utilizing proteins encoding the human p/a region and C1 domain. More detailed insight in how individual domains of cMyBP-C function and interact, across species and over the wide spectrum of conditions in which the heart has to function, will be essential to a better understanding of how cMyBP-C tunes cardiac contraction.

Original languageEnglish (US)
Pages (from-to)124-132
Number of pages9
JournalJournal of Molecular and Cellular Cardiology
Volume88
DOIs
StatePublished - Nov 1 2015
Externally publishedYes

Fingerprint

Cardiac Myosins
Proline
Alanine
Calcium
myosin-binding protein C
Adrenergic Agonists
Proteins
Cardiac Myocytes
Stroke Volume

Keywords

  • Cardiac contraction
  • Echocardiogram
  • Mice
  • Myosin binding protein C
  • Sarcomere

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine

Cite this

Normal cardiac contraction in mice lacking the proline-alanine rich region and C1 domain of cardiac myosin binding protein C. / van Dijk, Sabine J.; Witt, Christian C.; Harris, Samantha P.

In: Journal of Molecular and Cellular Cardiology, Vol. 88, 01.11.2015, p. 124-132.

Research output: Contribution to journalArticle

@article{5ada1cff1fc14c3daca793d42b86e6b4,
title = "Normal cardiac contraction in mice lacking the proline-alanine rich region and C1 domain of cardiac myosin binding protein C",
abstract = "Cardiac myosin binding protein C (cMyBP-C) is an essential regulator of cross bridge cycling. Through mechanisms that are incompletely understood the N-terminal domains (NTDs) of cMyBP-C can activate contraction even in the absence of calcium and can also inhibit cross bridge kinetics in the presence of calcium. In vitro studies indicated that the proline-alanine rich (p/a) region and C1 domain are involved in these processes, although effects were greater using human proteins compared to murine proteins (Shaffer et al. J Biomed Biotechnol 2010, 2010: 789798). We hypothesized that the p/a and C1 region are critical for the timing of contraction. In this study we tested this hypothesis using a mouse model lacking the p/a and C1 region (p/a-C1-/- mice) to investigate the in vivo relevance of these regions on cardiac performance.Surprisingly, hearts of adult p/a-C1-/- mice functioned normally both on a cellular and whole organ level. Force measurements in permeabilized cardiomyocytes from adult p/a-C1-/- mice and wild type (Wt) littermate controls demonstrated similar rates of force redevelopment both at submaximal and maximal activation. Maximal and passive force and calcium sensitivity of force were comparable between groups as well. Echocardiograms showed normal isovolumetric contraction times, fractional shortening and ejection fraction, indicating proper systolic function in p/a-C1-/- mouse hearts. p/a-C1-/- mice showed a slight but significant reduction in isovolumetric relaxation time compared to Wt littermates, yet this difference disappeared in older mice (7-8months of age). Moreover, stroke volume was preserved in p/a-C1-/- mice, corroborating sufficient time for normal filling of the heart. Overall, the hearts of p/a-C1-/- mice showed no signs of dysfunction even after chronic stress with an adrenergic agonist.Together, these results indicate that the p/a region and the C1 domain of cMyBP-C are not critical for normal cardiac contraction in mice and that these domains have little if any impact on cross bridge kinetics in mice. These results thus contrast with in vitro studies utilizing proteins encoding the human p/a region and C1 domain. More detailed insight in how individual domains of cMyBP-C function and interact, across species and over the wide spectrum of conditions in which the heart has to function, will be essential to a better understanding of how cMyBP-C tunes cardiac contraction.",
keywords = "Cardiac contraction, Echocardiogram, Mice, Myosin binding protein C, Sarcomere",
author = "{van Dijk}, {Sabine J.} and Witt, {Christian C.} and Harris, {Samantha P.}",
year = "2015",
month = "11",
day = "1",
doi = "10.1016/j.yjmcc.2015.09.006",
language = "English (US)",
volume = "88",
pages = "124--132",
journal = "Journal of Molecular and Cellular Cardiology",
issn = "0022-2828",
publisher = "Academic Press Inc.",

}

TY - JOUR

T1 - Normal cardiac contraction in mice lacking the proline-alanine rich region and C1 domain of cardiac myosin binding protein C

AU - van Dijk, Sabine J.

AU - Witt, Christian C.

AU - Harris, Samantha P.

PY - 2015/11/1

Y1 - 2015/11/1

N2 - Cardiac myosin binding protein C (cMyBP-C) is an essential regulator of cross bridge cycling. Through mechanisms that are incompletely understood the N-terminal domains (NTDs) of cMyBP-C can activate contraction even in the absence of calcium and can also inhibit cross bridge kinetics in the presence of calcium. In vitro studies indicated that the proline-alanine rich (p/a) region and C1 domain are involved in these processes, although effects were greater using human proteins compared to murine proteins (Shaffer et al. J Biomed Biotechnol 2010, 2010: 789798). We hypothesized that the p/a and C1 region are critical for the timing of contraction. In this study we tested this hypothesis using a mouse model lacking the p/a and C1 region (p/a-C1-/- mice) to investigate the in vivo relevance of these regions on cardiac performance.Surprisingly, hearts of adult p/a-C1-/- mice functioned normally both on a cellular and whole organ level. Force measurements in permeabilized cardiomyocytes from adult p/a-C1-/- mice and wild type (Wt) littermate controls demonstrated similar rates of force redevelopment both at submaximal and maximal activation. Maximal and passive force and calcium sensitivity of force were comparable between groups as well. Echocardiograms showed normal isovolumetric contraction times, fractional shortening and ejection fraction, indicating proper systolic function in p/a-C1-/- mouse hearts. p/a-C1-/- mice showed a slight but significant reduction in isovolumetric relaxation time compared to Wt littermates, yet this difference disappeared in older mice (7-8months of age). Moreover, stroke volume was preserved in p/a-C1-/- mice, corroborating sufficient time for normal filling of the heart. Overall, the hearts of p/a-C1-/- mice showed no signs of dysfunction even after chronic stress with an adrenergic agonist.Together, these results indicate that the p/a region and the C1 domain of cMyBP-C are not critical for normal cardiac contraction in mice and that these domains have little if any impact on cross bridge kinetics in mice. These results thus contrast with in vitro studies utilizing proteins encoding the human p/a region and C1 domain. More detailed insight in how individual domains of cMyBP-C function and interact, across species and over the wide spectrum of conditions in which the heart has to function, will be essential to a better understanding of how cMyBP-C tunes cardiac contraction.

AB - Cardiac myosin binding protein C (cMyBP-C) is an essential regulator of cross bridge cycling. Through mechanisms that are incompletely understood the N-terminal domains (NTDs) of cMyBP-C can activate contraction even in the absence of calcium and can also inhibit cross bridge kinetics in the presence of calcium. In vitro studies indicated that the proline-alanine rich (p/a) region and C1 domain are involved in these processes, although effects were greater using human proteins compared to murine proteins (Shaffer et al. J Biomed Biotechnol 2010, 2010: 789798). We hypothesized that the p/a and C1 region are critical for the timing of contraction. In this study we tested this hypothesis using a mouse model lacking the p/a and C1 region (p/a-C1-/- mice) to investigate the in vivo relevance of these regions on cardiac performance.Surprisingly, hearts of adult p/a-C1-/- mice functioned normally both on a cellular and whole organ level. Force measurements in permeabilized cardiomyocytes from adult p/a-C1-/- mice and wild type (Wt) littermate controls demonstrated similar rates of force redevelopment both at submaximal and maximal activation. Maximal and passive force and calcium sensitivity of force were comparable between groups as well. Echocardiograms showed normal isovolumetric contraction times, fractional shortening and ejection fraction, indicating proper systolic function in p/a-C1-/- mouse hearts. p/a-C1-/- mice showed a slight but significant reduction in isovolumetric relaxation time compared to Wt littermates, yet this difference disappeared in older mice (7-8months of age). Moreover, stroke volume was preserved in p/a-C1-/- mice, corroborating sufficient time for normal filling of the heart. Overall, the hearts of p/a-C1-/- mice showed no signs of dysfunction even after chronic stress with an adrenergic agonist.Together, these results indicate that the p/a region and the C1 domain of cMyBP-C are not critical for normal cardiac contraction in mice and that these domains have little if any impact on cross bridge kinetics in mice. These results thus contrast with in vitro studies utilizing proteins encoding the human p/a region and C1 domain. More detailed insight in how individual domains of cMyBP-C function and interact, across species and over the wide spectrum of conditions in which the heart has to function, will be essential to a better understanding of how cMyBP-C tunes cardiac contraction.

KW - Cardiac contraction

KW - Echocardiogram

KW - Mice

KW - Myosin binding protein C

KW - Sarcomere

UR - http://www.scopus.com/inward/record.url?scp=84944219771&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84944219771&partnerID=8YFLogxK

U2 - 10.1016/j.yjmcc.2015.09.006

DO - 10.1016/j.yjmcc.2015.09.006

M3 - Article

C2 - 26455481

AN - SCOPUS:84944219771

VL - 88

SP - 124

EP - 132

JO - Journal of Molecular and Cellular Cardiology

JF - Journal of Molecular and Cellular Cardiology

SN - 0022-2828

ER -