%0 Journal Article
%A Ponce-Balbuena, Daniela et.al
%A Jalife, Jalife
%A Caballero Collado, Ricardo
%A Delpón Mosquera, María Eva
%T Cardiac Kir2.1 and NaV1.5 Channels Traffic Together to the Sarcolemma to Control Excitability.
%D 2018
%U https://hdl.handle.net/20.500.14352/92143
%X Rationale: In cardiomyocytes, NaV1.5 and Kir2.1 channels interact dynamically as part of membrane boundmacromolecular complexes.Objective: The objective of this study was to test whether NaV1.5 and Kir2.1 preassemble during early forwardtrafficking and travel together to common membrane microdomains.Methods and Results: In patch-clamp experiments, coexpression of trafficking-deficient mutants Kir2.1Δ314-315 orKir2.1R44A/R46A with wild-type (WT) NaV1.5WT in heterologous cells reduced inward sodium current compared withNaV1.5WT alone or coexpressed with Kir2.1WT. In cell surface biotinylation experiments, expression of Kir2.1Δ314-315reduced NaV1.5 channel surface expression. Glycosylation analysis suggested that NaV1.5WT and Kir2.1WT channelsassociate early in their biosynthetic pathway, and fluorescence recovery after photobleaching experimentsdemonstrated that coexpression with Kir2.1 increased cytoplasmic mobility of NaV1.5WT, and vice versa, whereascoexpression with Kir2.1Δ314-315 reduced mobility of both channels. Viral gene transfer of Kir2.1Δ314-315 in adult ratventricular myocytes and human induced pluripotent stem cell–derived cardiomyocytes reduced inward rectifierpotassium current and inward sodium current, maximum diastolic potential and action potential depolarizationrate, and increased action potential duration. On immunostaining, the AP1 (adaptor protein complex 1) colocalizedwith NaV1.5WT and Kir2.1WT within areas corresponding to t-tubules and intercalated discs. Like Kir2.1WT, NaV1.5WTcoimmunoprecipitated with AP1. Site-directed mutagenesis revealed that NaV1.5WT channels interact with AP1through the NaV1.5Y1810 residue, suggesting that, like for Kir2.1WT, AP1 can mark NaV1.5 channels for incorporationinto clathrin-coated vesicles at the trans-Golgi. Silencing the AP1 ϒ-adaptin subunit in human induced pluripotentstem cell–derived cardiomyocytes reduced inward rectifier potassium current, inward sodium current, andmaximum diastolic potential and impaired rate-dependent action potential duration adaptation.Conclusions: The NaV1.5-Kir2.1 macromolecular complex pre-assembles early in the forward trafficking pathway.Therefore, disruption of Kir2.1 trafficking in cardiomyocytes affects trafficking of NaV1.5, which may haveimportant implications in the mechanisms of arrhythmias in inheritable cardiac diseases. (Circ Res. 2018;122:1501-1516. DOI: 10.1161/CIRCRESAHA.117.311872.)
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