Cloning and characterization of zebrafish K 2P 13.1 (THIK-1) two-pore-domain K + channels

• Published in: Journal of molecular and cellular cardiology 2019-01, Vol.126, p.96
• Main Authors: Staudacher, Ingo, Seehausen, Sebastian, Gierten, Jakob, Illg, Claudius, Schweizer, Patrick A, Katus, Hugo A, Thomas, Dierk
• Format: Article
• Language: English
• Subjects: Animals; Cloning, Molecular; Humans; Hydrogen-Ion Concentration; Peptides - metabolism; Potassium Channels, Tandem Pore Domain - genetics; Potassium Channels, Tandem Pore Domain - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; Zebrafish - genetics; Zebrafish Proteins - chemistry; Zebrafish Proteins - genetics; Zebrafish Proteins - metabolism
• ISSN: 1095-8584

Two-pore-domain potassium (K ) channels conduct background potassium currents in the heart and other tissues. K currents are involved in the repolarization of action potentials and stabilize the resting membrane potential. Human K 13.1 (THIK-1) channels are expressed in the heart and have recently been implicated in atrial fibrillation. The in vivo significance of K 13.1 currents in cardiac electrophysiology is not known. We hypothesized that Danio rerio (zebrafish) may serve as model to elucidate the functional role of cardiac K 13.1 channels. This work was designed to characterize zebrafish orthologs of K 13.1. Two zkcnk13 coding sequences were identified by DNA database searches and amplified from zebrafish cDNA. Human and zebrafish K 13.1 proteins exhibit 70% (K 13.1a) and 66% (K 13.1b) identity. Kcnk13 expression in zebrafish was studied using polymerase chain reaction. Zebrafish kcnk13a and zkcnk13b mRNAs were detected in brain and heart. Human and zebrafish K 13.1 currents were analyzed in the Xenopus oocyte expression system by voltage clamp electrophysiology. Zebrafish K 13.1a polypeptides were non-functional, while zK 13.1b channels exhibited K selective, outwardly rectifying currents. Zebrafish and human K 13.1 currents were similarly activated by arachidonic acid and reduced by barium, mexiletine, lidocaine, and inhibition of phospholipase C. In conclusion, zebrafish K 13.1b channels and their human orthologs exhibit structural and regulatory similarities. Zebrafish may be used as in vivo model for the assessment of physiology and therapeutic significance of K 13.1.