Contractile responses to endothelin-1 are regulated by PKC phosphorylation of cardiac myosin binding protein-C in rat ventricular myocytes

Ioannis Smyrnias, Normann Goodwin, Dagmar Wachten, Jonas Skogestad, Jan Magnus Aronsen, Emma L Robinson, Kateryna Demydenko, Anne Segonds-Pichon, David Oxley, Sakthivel Sadayappan, Karin Sipido, Martin D Bootman, H Llewelyn Roderick*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

The shortening of sarcomeres that co-ordinates the pump function of the heart is stimulated by electrically-mediated increases in [Ca2+]. This process of excitation-contraction coupling (ECC) is subject to modulation by neurohormonal mediators that tune the output of the heart to meet the needs of the organism. Endothelin-1 (ET-1) is a potent modulator of cardiac function with effects on contraction amplitude, chronotropy and automaticity. The actions of ET-1 are evident during normal adaptive physiological responses and increased under pathophysiological conditions, such as following myocardial infarction and during heart failure, where ET-1 levels are elevated. In myocytes, ET-1 acts through ETA- or ETB-G protein-coupled receptors (GPCRs). Although well studied in atrial myocytes, the influence and mechanisms of action of ET-1 upon ECC in ventricular myocytes are not fully resolved. We show in rat ventricular myocytes that ET-1 elicits a biphasic effect on fractional shortening (initial transient negative and sustained positive inotropy) and increases the peak amplitude of systolic Ca2+ transients in adult rat ventricular myocytes. The negative inotropic phase was ETB receptor-dependent, whereas the positive inotropic response and increase in peak amplitude of systolic Ca2+ transients required ETA receptor engagement. Both effects of ET-1 required phospholipase C (PLC)-activity, although distinct signalling pathways downstream of PLC elicited the effects of each ET receptor. The negative inotropic response involved inositol 1,4,5-trisphosphate (InsP3) signalling and protein kinase C epsilon (PKCε). The positive inotropic action and the enhancement in Ca2+ transient amplitude induced by ET-1 were independent of InsP3 signalling, but suppressed by PKCε. Serine 302 in cardiac myosin binding protein-C was identified as a PKCε substrate that when phosphorylated contributed to the suppression of contraction and Ca2+ transients by PKCε following ET-1 stimulation. Thus, our data provide a new role and mechanism of action for InsP3 and PKCε in mediating the negative inotropic response and in restraining the positive inotropy and enhancement in Ca2+ transients following ET-1 stimulation.

Original languageEnglish
Pages (from-to)1-18
Number of pages18
JournalJournal of Molecular and Cellular Cardiology
Volume117
DOIs
Publication statusPublished - Apr 2018
Externally publishedYes

Keywords

  • Animals
  • Calcium/metabolism
  • Calcium Signaling/drug effects
  • Cardiotonic Agents/pharmacology
  • Carrier Proteins/metabolism
  • Cytosol/metabolism
  • Endothelin-1/pharmacology
  • Excitation Contraction Coupling/drug effects
  • Heart Ventricles/cytology
  • Inositol 1,4,5-Trisphosphate Receptors/metabolism
  • Male
  • Myocardial Contraction/drug effects
  • Myocytes, Cardiac/drug effects
  • Phosphorylation/drug effects
  • Protein Kinase C-epsilon/antagonists & inhibitors
  • Rats, Wistar
  • Receptors, Endothelin/metabolism
  • Sarcoplasmic Reticulum/drug effects
  • Type C Phospholipases/metabolism

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