TY - JOUR
T1 - Dynamics of PKA phosphorylation and gain of function in cardiac pacemaker cells: a computational model analysis
T2 - A computational model analysis
AU - Behar, Joachim
AU - Yaniv, Yael
N1 - Publisher Copyright:
© 2016 the American Physiological Society.
PY - 2016/5/1
Y1 - 2016/5/1
N2 - Cardiac pacemaker cell function is regulated by a coupled-clock system that integrates molecular cues on the cell-membrane surface (i.e., membrane clock) and on the sarcoplasmic reticulum (SR) (i.e., Ca2+ clock). A recent study has shown that cotransfection of spontaneous beating cells (HEK293 cells and neonatal rat myocytes) with R524Q-mutant human hyperpolarization-activated cyclic nucleotide-gated molecules (the dominant component of funny channels) increases the funny channel's sensitivity to cAMP and leads to a decrease in spontaneous action potential (AP) cycle length (i.e., tachycardia). We hypothesize that in rabbit pacemaker cells, the same behavior is expected, and because of the coupled-clock system, the resultant steady-state decrease in AP cycle length will embody contributions from both clocks: the initial decrease in the spontaneous AP beating interval, arising from increased sensitivity of the f-channel to cAMP, will be accompanied by an increase in the adenylyl cyclase (AC)-cAMP-PKA-dependent phosphorylation activity, which will further decrease this interval. To test our hypothesis, we used the recently developed Yaniv-Lakatta pacemaker cell numerical model. This model predicts the cAMP signaling dynamics, as well as the kinetics and magnitude of protein phosphorylation in both normal and mutant pacemaker cells. We found that R524Q-mutant pacemaker cells have a shorter AP firing rate than that of wild-type cells and that gain in pacemaker function is the net effect of the R514Q mutation on the functioning of the coupled-clock system. Specifically, our results directly support the hypothesis that changes in Ca2+-activated AC-cAMP-PKA signaling are involved in the development of tachycardia in R524Q-mutant pacemaker cells.
AB - Cardiac pacemaker cell function is regulated by a coupled-clock system that integrates molecular cues on the cell-membrane surface (i.e., membrane clock) and on the sarcoplasmic reticulum (SR) (i.e., Ca2+ clock). A recent study has shown that cotransfection of spontaneous beating cells (HEK293 cells and neonatal rat myocytes) with R524Q-mutant human hyperpolarization-activated cyclic nucleotide-gated molecules (the dominant component of funny channels) increases the funny channel's sensitivity to cAMP and leads to a decrease in spontaneous action potential (AP) cycle length (i.e., tachycardia). We hypothesize that in rabbit pacemaker cells, the same behavior is expected, and because of the coupled-clock system, the resultant steady-state decrease in AP cycle length will embody contributions from both clocks: the initial decrease in the spontaneous AP beating interval, arising from increased sensitivity of the f-channel to cAMP, will be accompanied by an increase in the adenylyl cyclase (AC)-cAMP-PKA-dependent phosphorylation activity, which will further decrease this interval. To test our hypothesis, we used the recently developed Yaniv-Lakatta pacemaker cell numerical model. This model predicts the cAMP signaling dynamics, as well as the kinetics and magnitude of protein phosphorylation in both normal and mutant pacemaker cells. We found that R524Q-mutant pacemaker cells have a shorter AP firing rate than that of wild-type cells and that gain in pacemaker function is the net effect of the R514Q mutation on the functioning of the coupled-clock system. Specifically, our results directly support the hypothesis that changes in Ca2+-activated AC-cAMP-PKA signaling are involved in the development of tachycardia in R524Q-mutant pacemaker cells.
KW - arrhythmia
KW - Ca2+ cycling
KW - Ca2+-excitation contraction coupling
KW - pacemaker cell automaticity
UR - http://www.scopus.com/inward/record.url?scp=84983746021&partnerID=8YFLogxK
U2 - 10.1152/ajpheart.00076.2016
DO - 10.1152/ajpheart.00076.2016
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SN - 0363-6135
VL - 310
SP - H1259-H1266
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 9
ER -