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Protein kinase C α and ε phosphorylation of troponin and myosin binding protein C reduce Ca(2+) sensitivity in human myocardium
Previous studies indicated that the increase in protein kinase C (PKC)-mediated myofilament protein phosphorylation observed in failing myocardium might be detrimental for contractile function. This study was designed to reveal and compare the effects of PKCα- and PKCε-mediated phosphorylation on my...
Autores principales: | , , , , , , |
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Formato: | Texto |
Lenguaje: | English |
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D. Steinkopff-Verlag
2009
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2807945/ https://www.ncbi.nlm.nih.gov/pubmed/19655190 http://dx.doi.org/10.1007/s00395-009-0053-z |
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author | Kooij, Viola Boontje, Nicky Zaremba, Ruud Jaquet, Kornelia dos Remedios, Cris Stienen, Ger J. M. van der Velden, Jolanda |
author_facet | Kooij, Viola Boontje, Nicky Zaremba, Ruud Jaquet, Kornelia dos Remedios, Cris Stienen, Ger J. M. van der Velden, Jolanda |
author_sort | Kooij, Viola |
collection | PubMed |
description | Previous studies indicated that the increase in protein kinase C (PKC)-mediated myofilament protein phosphorylation observed in failing myocardium might be detrimental for contractile function. This study was designed to reveal and compare the effects of PKCα- and PKCε-mediated phosphorylation on myofilament function in human myocardium. Isometric force was measured at different [Ca(2+)] in single permeabilized cardiomyocytes from failing human left ventricular tissue. Activated PKCα and PKCε equally reduced Ca(2+) sensitivity in failing cardiomyocytes (ΔpCa(50) = 0.08 ± 0.01). Both PKC isoforms increased phosphorylation of troponin I- (cTnI) and myosin binding protein C (cMyBP-C) in failing cardiomyocytes. Subsequent incubation of failing cardiomyocytes with the catalytic subunit of protein kinase A (PKA) resulted in a further reduction in Ca(2+) sensitivity, indicating that the effects of both PKC isoforms were not caused by cross-phosphorylation of PKA sites. Both isozymes showed no effects on maximal force and only PKCα resulted in a modest significant reduction in passive force. Effects of PKCα were only minor in donor cardiomyocytes, presumably because of already saturated cTnI and cMyBP-C phosphorylation levels. Donor tissue could therefore be used as a tool to reveal the functional effects of troponin T (cTnT) phosphorylation by PKCα. Massive dephosphorylation of cTnT with alkaline phosphatase increased Ca(2+) sensitivity. Subsequently, PKCα treatment of donor cardiomyocytes reduced Ca(2+) sensitivity (ΔpCa(50) = 0.08 ± 0.02) and solely increased phosphorylation of cTnT, but did not affect maximal and passive force. PKCα- and PKCε-mediated phosphorylation of cMyBP-C and cTnI as well as cTnT decrease myofilament Ca(2+) sensitivity and may thereby reduce contractility and enhance relaxation of human myocardium. |
format | Text |
id | pubmed-2807945 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2009 |
publisher | D. Steinkopff-Verlag |
record_format | MEDLINE/PubMed |
spelling | pubmed-28079452010-01-22 Protein kinase C α and ε phosphorylation of troponin and myosin binding protein C reduce Ca(2+) sensitivity in human myocardium Kooij, Viola Boontje, Nicky Zaremba, Ruud Jaquet, Kornelia dos Remedios, Cris Stienen, Ger J. M. van der Velden, Jolanda Basic Res Cardiol Original Contribution Previous studies indicated that the increase in protein kinase C (PKC)-mediated myofilament protein phosphorylation observed in failing myocardium might be detrimental for contractile function. This study was designed to reveal and compare the effects of PKCα- and PKCε-mediated phosphorylation on myofilament function in human myocardium. Isometric force was measured at different [Ca(2+)] in single permeabilized cardiomyocytes from failing human left ventricular tissue. Activated PKCα and PKCε equally reduced Ca(2+) sensitivity in failing cardiomyocytes (ΔpCa(50) = 0.08 ± 0.01). Both PKC isoforms increased phosphorylation of troponin I- (cTnI) and myosin binding protein C (cMyBP-C) in failing cardiomyocytes. Subsequent incubation of failing cardiomyocytes with the catalytic subunit of protein kinase A (PKA) resulted in a further reduction in Ca(2+) sensitivity, indicating that the effects of both PKC isoforms were not caused by cross-phosphorylation of PKA sites. Both isozymes showed no effects on maximal force and only PKCα resulted in a modest significant reduction in passive force. Effects of PKCα were only minor in donor cardiomyocytes, presumably because of already saturated cTnI and cMyBP-C phosphorylation levels. Donor tissue could therefore be used as a tool to reveal the functional effects of troponin T (cTnT) phosphorylation by PKCα. Massive dephosphorylation of cTnT with alkaline phosphatase increased Ca(2+) sensitivity. Subsequently, PKCα treatment of donor cardiomyocytes reduced Ca(2+) sensitivity (ΔpCa(50) = 0.08 ± 0.02) and solely increased phosphorylation of cTnT, but did not affect maximal and passive force. PKCα- and PKCε-mediated phosphorylation of cMyBP-C and cTnI as well as cTnT decrease myofilament Ca(2+) sensitivity and may thereby reduce contractility and enhance relaxation of human myocardium. D. Steinkopff-Verlag 2009-08-05 2010 /pmc/articles/PMC2807945/ /pubmed/19655190 http://dx.doi.org/10.1007/s00395-009-0053-z Text en © The Author(s) 2009 https://creativecommons.org/licenses/by-nc/4.0/ This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. |
spellingShingle | Original Contribution Kooij, Viola Boontje, Nicky Zaremba, Ruud Jaquet, Kornelia dos Remedios, Cris Stienen, Ger J. M. van der Velden, Jolanda Protein kinase C α and ε phosphorylation of troponin and myosin binding protein C reduce Ca(2+) sensitivity in human myocardium |
title | Protein kinase C α and ε phosphorylation of troponin and myosin binding protein C reduce Ca(2+) sensitivity in human myocardium |
title_full | Protein kinase C α and ε phosphorylation of troponin and myosin binding protein C reduce Ca(2+) sensitivity in human myocardium |
title_fullStr | Protein kinase C α and ε phosphorylation of troponin and myosin binding protein C reduce Ca(2+) sensitivity in human myocardium |
title_full_unstemmed | Protein kinase C α and ε phosphorylation of troponin and myosin binding protein C reduce Ca(2+) sensitivity in human myocardium |
title_short | Protein kinase C α and ε phosphorylation of troponin and myosin binding protein C reduce Ca(2+) sensitivity in human myocardium |
title_sort | protein kinase c α and ε phosphorylation of troponin and myosin binding protein c reduce ca(2+) sensitivity in human myocardium |
topic | Original Contribution |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2807945/ https://www.ncbi.nlm.nih.gov/pubmed/19655190 http://dx.doi.org/10.1007/s00395-009-0053-z |
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