Fig. 4: Increased late INa and decreased IKs contribute to action potential prolongation in NAA10-mutant iPSC-CMs.
From: Dysregulation of N-terminal acetylation causes cardiac arrhythmia and cardiomyopathy
a Sodium current (INa) traces from iPSC-CMs. b Increased peak INa in NAA10-mutant iPSC-CMs (upper). Voltage-dependent activation and inactivation curves (lower). (n = 14, 8, and 10; independent differentiation experiments, n = 4, 3, 6 in WT-, pNAA10R4S/Y-, and eNAA10R4S/Y-iPSC-CMs; p = 0.0265; two-way repeated-measures ANOVA). c Late INa (INaL) traces elicited by tetrodotoxin (TTX) blockade (gray). d INaL normalized to peak INa: WT = 0.03 ± 0.005 %, vs pNAA10R4S/Y = 0.06 ± 0.01 % (p = 0.0268), and eNAA10R4S/Y = 0.07 ± 0.02 % (p = 0.0105); n = 13, 8, and 6; n = 7, 5, 3, independent differentiation experiments; one-way ANOVA. e Slow delayed rectifier potassium current (IKs) traces. f IKs current-voltage relationship (n = 5, 8, and 10; n = 5, 7, and 4, independent differentiation experiments in WT-, pNAA10R4S/Y-, and eNAA10R4S/Y-iPSC-CMs; p = 0.0009; two-way repeated-measures ANOVA). g Rapid delayed rectifier potassium current (IKr) traces. h IKr-tail current demonstrated no differences (n = 6, 7, and 7; n = 3, 3, and 3, independent differentiation experiments in WT-, pNAA10R4S/Y-, and eNAA10R4S/Y-iPSC-CMs; p = 0.4440; two-way repeated-measures ANOVA). Membrane capacitance: WT = 49.8 ± 6.8 pF, pNAA10R4S/Y = 46.8 ± 12.7 pF, eNAA10R4S/Y = 43.7 ± 6.6 pF. i. Immunoblot for membrane NaV1.5, confirming separation with Transferrin receptor (TFRC)-positive and β-actin-negative blot. j Membrane NaV1.5 normalized to TFRC: WT = 1.0 ± 0.0, pNAA10R4S/Y = 3.2 ± 1.1 (p = 0.0414), eNAA10R4S/Y = 2.3 ± 0.3 (p = 0.0164); n = 6; Kruskal-Wallis test. k Schematic of KCNQ1 with cMyc epitope (extracellular) and EGFP (C-terminus). Created in BioRender. Yoshinaga, D. (2025) https://BioRender.com/b59q327. l Flow cytometry analysis of EGFP and cMyc-Alexa 647 intensity in KCNQ1-transfected cells. m cMyc intensity normalized to EGFP: siNC = 1.0 ± 0.04 vs siNAA10 = 0.6 ± 0.01; biological replicates, n = 3; p = 0.0075; two-tailed unpaired t-test. Data are presented as mean ± SEM. ns = p > 0.1, *p < 0.05, **p < 0.01, ***p < 0.005, ****p < 0.0001. Source data are provided as a Source Data file.
