Extended Data Fig. 4: The effect of dextromethorphan on potassium channels in human cardiomyocytes derived from isogenic control iPSCs.
From: Sigma non-opioid receptor 1 is a potential therapeutic target for long QT syndrome
(a) Representative traces of IKr current (E-4031-sensitive) in isogenic control (Ctrl) cardiomyocytes treated with Dxm (5 μM, 2 hr) or without treatment. (b-c) IKr current amplitude (b) and tail IKr current (c) were not significantly changed by Dxm in the isogenic Ctrl cardiomyocytes (n = 10/group). (d) Schematic representation of confocal imaging for proximity ligation assay (PLA, SIGMAR1-hERG, red) in human iPSC-derived cardiomyocytes. (e) Representative confocal fluorescent images of TS cardiomyocytes used for PLA (SIGMAR1-hERG, red) and DAPI (blue) staining. Dxm treatment (+Dxm, 5 μM, 2 hr) was conducted to examine the effect of Dxm on PLA signals in TS cardiomyocytes. #3 images are used in Fig. 2j. Scale bar, 10μm. (f) Representative epi-fluorescent and phase-contrast images of isogenic Ctrl cardiomyocytes used for PLA (red, SIGMAR1-hERG) and DAPI (blue) staining. Dxm treatment (+Dxm, 5 μM, 2 hr) was conducted to examine the effect of Dxm on PLA signals in the cardiomyocytes. Scale bar, 10μm. (g) Quantification of PLA signal number of SIGMAR1-hERG in Dxm-treated (n = 21) and non-treated (n = 21) isogenic Ctrl cardiomyocytes. (h) Representative traces of IKs current (Chromanol 293B-sensitive) in isogenic control (Ctrl) cardiomyocytes treated with Dxm or without treatment. (i) IKs current amplitude analysis in the isogenic Ctrl cardiomyocytes with Dxm (5 μM, 2 hr, n = 9) or without treatment (n = 10). (j) Representative epi-fluorescent and phase-contrast images of isogenic Ctrl cardiomyocytes used for PLA (red, SIGMAR1-KV7.1) and DAPI (blue) staining. Dxm treatment (+Dxm, 5 μM, 2 hr) was conducted to examine the effect of Dxm on PLA signals in the cardiomyocytes. Scale bar, 10μm. (k) Quantification of PLA signal number of SIGMAR1-KV7.1 in Dxm-treated (n = 40) and non-treated (n = 44) isogenic Ctrl cardiomyocytes. All data are mean ± s.d. Unpaired two-tailed Student t-test was used for g,k between the groups, and for b,c,i at each voltage step. * P < 0.05. n.s., not significant. The cell samples were from at least two independent differentiations.
