The SLC4A3-N353K knock-in zebrafish model exhibited shortened action potential durations and increased cardiac pauses (23.08% vs 4.65% in WT), which were reversed by 1μM quinidine.
Does quinidine prolong action potential duration in a zebrafish model of SLC4A3-N353K short QT syndrome?
The SLC4A3-N353K variant causes short QT syndrome phenotypes in a zebrafish model, which can be partially reversed by quinidine treatment.
Absolute Event Rate: 23.08% vs 4.65%
Abstract Background Short QT syndrome (SQTS) is an inherited cardiac channelopathy characterized by an abnormally short QT interval, which can lead to ventricular fibrillation (VF) and cardiac death. Recently, SLC4A3, a gene that encodes the membrane-localized anion exchanger 3 (AE3) responsible for regulating intracellular pH (pHi), has been reported as a causative gene for SQTS. We have identified a novel SLC4A3 variant (c.1059 CA, p.N353K) in a family with SQTS. However, the exact pathogenic mechanism of SLC4A3 variants whichcause SQTS remains unclear. Purpose We aimed to elucidate the pathogenesis of a novel SLC4A3 variant identified in a SQTS family using the knock-in zebrafish model. Methods To clarify the pathogenesis of the SLC4A3 variant in vivo, we injected CRISPR-Cas9 along with a repair template into one-cell stage zebrafish embryos, establishing a SLC4A3 knock-in (KI) zebrafish model (hereafter referred to as slc4a3 zebrafish). The KI offspring were used for analysis. Action potential durations (APD) were recorded in zebrafish at 3 days post-fertilization (dpf) both before and after pharmacological treatment by patch-clamp system. Bazett’s formula was used to correct APD for varying beating frequencies (cAPD). High-speed immunofluorescence imaging and immunostaining were conducted in this study. Results The slc4a3 KI zebrafish, which harbors the paralogous mutation of SLC4A3-N353K, showed normal cardiac development by immunostaining at 3 dpf. However, at the meanwhile, the APD50, and 70 were significantly shortened in the slc4a3 zebrafish (HOMO)compared to the control (WT), even after correction with heart beats providing evidence for the shortened QT interval with the SLC4A3 variant in vivo (Figure A). Additionally, there was an increased proportion of cardiac pauses in the slc4a3 zebrafish (HET 15.79% and HOMO 23.08%) compared to WT (4.65%) during the recording, which suggested slc4a3 zebrafish increased the potential for the rhythm disturbance. Moreover, slc4a3 zebrafish highly developed severe pericardiac edema (WT 9%, HET 35%, HOMO 46%) at 5 dpf. The systolic function in both fractional shortening and ejection fraction in zebrafish with edema significantly decreased, which indicates the existence of heart failure (Figure B). To investigate potential pharmacological effects for SLC4A3-N353K inducing SQTS, we applied with 1μM of quinidine. cAPD50, and 70 were significantly increased in slc4a3 zebrafish (HET and HOMO) compared to the baseline (Figure C and D) which suggested quinidine could be a candidate treatment for SQTS patients caused by SLC4A3-N353K. Conclusion SLC4A3-N353K is considered as a pathogenic variant causing SQTS. Quinidine treatment may be beneficial for SQTS patients who carry pathogenic SLC4A3 variants.
Zhu et al. (Sat,) conducted a other in Short QT syndrome (SQTS). SLC4A3-N353K knock-in and quinidine vs. Wild-type (WT) zebrafish was evaluated on Action potential durations (APD) and cardiac pauses. The SLC4A3-N353K knock-in zebrafish model exhibited shortened action potential durations and increased cardiac pauses (23.08% vs 4.65% in WT), which were reversed by 1μM quinidine.