TY - JOUR
T1 - Loss of Camp-Dependent Protein Kinase A (PKA)-Mediated Na Channel Phosphorylation and Brugada Syndrome
AU - Aiba, Takeshi
AU - Farinelli, Federica
AU - Hesketh, Geoffrey
AU - Shimizu, Wataru
AU - Tomaselli, Gordon
PY - 2011
Y1 - 2011
N2 - PKA phosphorylation is important for Nav1.5 expression and function, however little is known about the relationship between Brugada syndrome (BrS) phenotype and PKA. We characterized the biophysical properties of a novel BrS-associated SCN5A mutation, R526H, identified in a proband that was resuscitated from sudden cardiac death. Methods: Whole-cell currents through wild-type (WT) Nav1.5 and mutant (R526H) channels expressed in HEK293-cell were recorded using patch clamp. Results: No difference was found in the peak current, steady-state activation, inactivation and recovery from inactivation in WT and mutant channels at baseline. PKA-stimulation (forskolin+cAMP) 1.7-fold increased the peak Na current (p>0.01), hyperpolarized the activation curve (+13mV; p>0.01) and hastened recovery from inactivation of WT. In contrast, no difference was found in the peak Na current, activation and recovery from inactivation after PKA-stimulation in R526H or in the mutation of the PKA-phosphorylation site, S528A. Voltage-dependent availability was not altered by PKA in WT, R526H and S528A. Thus, PKA-stimulation 4-fold increased Na window current in WT but not the mutant channels. In-vitro PKA phosphorylation was detected in the I-II linker of WT but not R526H and S528A mutants of Nav1.5. Conclusion: R526H mutant eliminated phosphorylation of Nav1.5 and abolished the PKA-induced increase in current amplitude. The loss of PKA stimulation may result in the Brugada phenotype.
AB - PKA phosphorylation is important for Nav1.5 expression and function, however little is known about the relationship between Brugada syndrome (BrS) phenotype and PKA. We characterized the biophysical properties of a novel BrS-associated SCN5A mutation, R526H, identified in a proband that was resuscitated from sudden cardiac death. Methods: Whole-cell currents through wild-type (WT) Nav1.5 and mutant (R526H) channels expressed in HEK293-cell were recorded using patch clamp. Results: No difference was found in the peak current, steady-state activation, inactivation and recovery from inactivation in WT and mutant channels at baseline. PKA-stimulation (forskolin+cAMP) 1.7-fold increased the peak Na current (p>0.01), hyperpolarized the activation curve (+13mV; p>0.01) and hastened recovery from inactivation of WT. In contrast, no difference was found in the peak Na current, activation and recovery from inactivation after PKA-stimulation in R526H or in the mutation of the PKA-phosphorylation site, S528A. Voltage-dependent availability was not altered by PKA in WT, R526H and S528A. Thus, PKA-stimulation 4-fold increased Na window current in WT but not the mutant channels. In-vitro PKA phosphorylation was detected in the I-II linker of WT but not R526H and S528A mutants of Nav1.5. Conclusion: R526H mutant eliminated phosphorylation of Nav1.5 and abolished the PKA-induced increase in current amplitude. The loss of PKA stimulation may result in the Brugada phenotype.
KW - Na channel
KW - phosphorylation
KW - sudden death
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U2 - 10.4020/jhrs.27.PE4_060
DO - 10.4020/jhrs.27.PE4_060
M3 - Article
AN - SCOPUS:85009580787
SN - 1880-4276
VL - 27
JO - Journal of Arrhythmia
JF - Journal of Arrhythmia
ER -