TY - JOUR
T1 - ZFHX3 knockdown increases arrhythmogenesis and dysregulates calcium homeostasis in HL-1 atrial myocytes
AU - Kao, Yu Hsun
AU - Hsu, Jung Chieh
AU - Chen, Yao Chang
AU - Lin, Yung Kuo
AU - Lkhagva, Baigalmaa
AU - Chen, Shih Ann
AU - Chen, Yi Jen
N1 - Funding Information:
The present work was supported by grants from Taipei Medical University ( TMU101-AE1-B54 ), Wan Fang Hospital ( 103swf-10 , 103-wf-eva-02 and 105-wf-eva-08 ), and the Ministry of Science and Technology, Taiwan ( NSC100-2628-B-038-001-MY4 and 102-2628-B-038-002-MY3 ).
Publisher Copyright:
© 2016 Elsevier Ireland Ltd. All rights reserved.
PY - 2016/5/1
Y1 - 2016/5/1
N2 - Background ZFHX3 plays an important role in the genesis of atrial fibrillation. However, the atrial electrophysiological effects of ZFHX3 are not clear. This study sought to investigate roles of ZFHX3 in atrial electrophysiology and calcium homeostasis by using HL-1 atrial myocytes knocked-down with ZFHX3. Methods Patch clamp, confocal fluorescence microscopy and Western blot were used to study electrical activity, ionic currents, calcium homeostasis and protein expressions in stable ZFHX3 shRNA cells. Results As compared to control, ZFHX3 shRNA cells with 28% decline of ZFHX3 protein had a larger sarcoplasmic reticulum Ca2+ content by 62%, Ca2+ transient by 20%, and calcium leak by 75%. ZFHX3 shRNA cells (n = 35) had shorter action potential duration (APD) at 50% (14.7 ± 0.9 versus 20.3 ± 1.4 ms, P <0.005), and 20% (6.1 ± 0.3 versus 8.3 ± 0.8 ms, P <0.005) repolarization than control cells (n = 30). ZFHX3 shRNA cells (n = 10) had larger amplitudes of isoproterenol (1 μM)-induced delayed afterdepolarization (14.1 ± 0.9 versus 7.2 ± 0.2 mV, P <0.05) than control cells (n = 10). Besides, acetylcholine (3 μM) shortened APD at 90% repolarization to a greater extent (19 ± 4% versus 7 ± 2%, P <0.01) in ZFHX3 shRNA cells (n = 11) than in control cells (n = 12). In addition, ZFHX3 shRNA cells had increased expressions of SERCA2a, ryanodine receptor, Kv1.4, Kv1.5 and Kir3.4. Moreover, ZFHX3 shRNA cells had a larger SERCA2a activity, ultra-rapid delayed rectifier potassium currents, transient outward currents and acetylcholine-sensitive potassium currents. Conclusions ZFHX3 knock-down in atrial myocytes dysregulated calcium homeostasis and increased atrial arrhythmogenesis, which may contribute to the occurrence of AF.
AB - Background ZFHX3 plays an important role in the genesis of atrial fibrillation. However, the atrial electrophysiological effects of ZFHX3 are not clear. This study sought to investigate roles of ZFHX3 in atrial electrophysiology and calcium homeostasis by using HL-1 atrial myocytes knocked-down with ZFHX3. Methods Patch clamp, confocal fluorescence microscopy and Western blot were used to study electrical activity, ionic currents, calcium homeostasis and protein expressions in stable ZFHX3 shRNA cells. Results As compared to control, ZFHX3 shRNA cells with 28% decline of ZFHX3 protein had a larger sarcoplasmic reticulum Ca2+ content by 62%, Ca2+ transient by 20%, and calcium leak by 75%. ZFHX3 shRNA cells (n = 35) had shorter action potential duration (APD) at 50% (14.7 ± 0.9 versus 20.3 ± 1.4 ms, P <0.005), and 20% (6.1 ± 0.3 versus 8.3 ± 0.8 ms, P <0.005) repolarization than control cells (n = 30). ZFHX3 shRNA cells (n = 10) had larger amplitudes of isoproterenol (1 μM)-induced delayed afterdepolarization (14.1 ± 0.9 versus 7.2 ± 0.2 mV, P <0.05) than control cells (n = 10). Besides, acetylcholine (3 μM) shortened APD at 90% repolarization to a greater extent (19 ± 4% versus 7 ± 2%, P <0.01) in ZFHX3 shRNA cells (n = 11) than in control cells (n = 12). In addition, ZFHX3 shRNA cells had increased expressions of SERCA2a, ryanodine receptor, Kv1.4, Kv1.5 and Kir3.4. Moreover, ZFHX3 shRNA cells had a larger SERCA2a activity, ultra-rapid delayed rectifier potassium currents, transient outward currents and acetylcholine-sensitive potassium currents. Conclusions ZFHX3 knock-down in atrial myocytes dysregulated calcium homeostasis and increased atrial arrhythmogenesis, which may contribute to the occurrence of AF.
KW - Atrial arrhythmogenesis
KW - Calcium homeostasis
KW - ZFHX3
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U2 - 10.1016/j.ijcard.2016.02.091
DO - 10.1016/j.ijcard.2016.02.091
M3 - Article
C2 - 26930642
AN - SCOPUS:84964664255
SN - 0167-5273
VL - 210
SP - 85
EP - 92
JO - International Journal of Cardiology
JF - International Journal of Cardiology
ER -