Ankyrin-G mediates targeting of both Na + and K ATP channels to the rat cardiac intercalated disc

• Published in: eLife 2020-01, Vol.9
• Main Authors: Yang, Hua-Qian, Pérez-Hernández, Marta, Sanchez-Alonso, Jose, Shevchuk, Andriy, Gorelik, Julia, Rothenberg, Eli, Delmar, Mario, Coetzee, William A
• Format: Article
• Language: English
• Subjects: Animals; Ankyrins - chemistry; Binding Sites; Biotinylation; Gene Expression Regulation; HEK293 Cells; Humans; Mutagenesis; Myocardium - metabolism; Myocytes, Cardiac - metabolism; NAV1.5 Voltage-Gated Sodium Channel - metabolism; Patch-Clamp Techniques; Potassium Channels, Inwardly Rectifying - metabolism; Rats
• ISSN: 2050-084X
• DOI: 10.7554/eLife.52373

We investigated targeting mechanisms of Na and K channels to the intercalated disk (ICD) of cardiomyocytes. Patch clamp and surface biotinylation data show reciprocal downregulation of each other's surface density. Mutagenesis of the Kir6.2 ankyrin binding site disrupts this functional coupling. Duplex patch clamping and Angle SICM recordings show that I and I functionally co-localize at the rat ICD, but not at the lateral membrane. Quantitative STORM imaging show that Na and K channels are localized close to each other and to AnkG, but not to AnkB, at the ICD. Peptides corresponding to Nav1.5 and Kir6.2 ankyrin binding sites dysregulate targeting of both Na and K channels to the ICD, but not to lateral membranes. Finally, a clinically relevant gene variant that disrupts K channel trafficking also regulates Na channel surface expression. The functional coupling between these two channels need to be considered when assessing clinical variants and therapeutics.