Please use this identifier to cite or link to this item:http://hdl.handle.net/20.500.12105/11056
The p.P888L SAP97 polymorphism increases the transient outward current (Ito,f) and abbreviates the action potential duration and the QT interval.
Tinaquero, David | Crespo-García, Teresa | Utrilla, Raquel G | Nieto-Marín, Paloma | González-Guerra, Andrés | Rubio-Alarcón, Marcos | Cámara-Checa, Anabel | Dago, María | Matamoros, Marcos | Pérez-Hernández, Marta | Tamargo, María | Cebrián, Jorge | Jalife, Jose CNIC | Tamargo, Juan | Bernal, Juan Antonio CNIC | Caballero, Ricardo | Delpón, Eva
Sci Rep. 2020; 10(1):10707
Synapse-Associated Protein 97 (SAP97) is an anchoring protein that in cardiomyocytes targets to the membrane and regulates Na+ and K+ channels. Here we compared the electrophysiological effects of native (WT) and p.P888L SAP97, a common polymorphism. Currents were recorded in cardiomyocytes from mice trans-expressing human WT or p.P888L SAP97 and in Chinese hamster ovary (CHO)-transfected cells. The duration of the action potentials and the QT interval were significantly shorter in p.P888L-SAP97 than in WT-SAP97 mice. Compared to WT, p.P888L SAP97 significantly increased the charge of the Ca-independent transient outward (Ito,f) current in cardiomyocytes and the charge crossing Kv4.3 channels in CHO cells by slowing Kv4.3 inactivation kinetics. Silencing or inhibiting Ca/calmodulin kinase II (CaMKII) abolished the p.P888L-induced Kv4.3 charge increase, which was also precluded in channels (p.S550A Kv4.3) in which the CaMKII-phosphorylation is prevented. Computational protein-protein docking predicted that p.P888L SAP97 is more likely to form a complex with CaMKII than WT. The Na+ current and the current generated by Kv1.5 channels increased similarly in WT-SAP97 and p.P888L-SAP97 cardiomyocytes, while the inward rectifier current increased in WT-SAP97 but not in p.P888L-SAP97 cardiomyocytes. The p.P888L SAP97 polymorphism increases the Ito,f, a CaMKII-dependent effect that may increase the risk of arrhythmias.