title: Angiotensin II upregulates Kv1.5 expression through ROS-dependent transforming growth factor-beta1 and extracellular signal-regulated kinase 1/2 signalings in neonatal rat atrial myocytes.
abstract: Kv1.5 potassium channel represents a promising target for atrial fibrillation (AF) therapy. During AF, the renin-angiotensin system is markedly activated. Recent evidence indicates that angiotensin II (Ang II) can upregulate Kv1.5 channel, but the mechanism remains unknown. In this study, we report that Ang II-mediated transforming growth factor-beta1 (TGF-β1)/Smad2/3 and extracellular signal-regulated kinase (ERK) 1/2 signalings are involved in atrial Kv1.5 expression. In neonatal rat atrial myocytes, quantitative PCR and Western blotting revealed that Ang II upregulated TGF-β1, synapse-associated protein 97 (SAP97) and Kv1.5 expression in a time- and concentration-dependent manner. The Ang II-induced upregulation of Kv1.5, SAP97 and phosphorylated Smad2/3 (P-Smad2/3) were reversed by the Ang II type 1 (AT1) receptor antagonist losartan, an anti-TGF-β1 antibody and the ERK 1/2 inhibitor PD98059 but not by the AT2 receptor antagonist PD123319. mRNA knockdown of either Smad2 or Smad3 blocked Ang II-induced expression of Kv1.5 and SAP97. These data suggest that AT1 receptor/TGF-β1/P-Smad2/3 and ERK 1/2 signalings are involved in Ang II-induced Kv1.5 and SAP97 expression. Flow cytometry and Western blotting revealed that losartan and the anti-TGF-β1 antibody diminished Ang II-induced reactive oxygen species (ROS) generation and that the antioxidants diphenyleneiodonium and N-acetyl cysteine inhibited Ang II-induced expression of P-Smad2/3, phosphorylated ERK (P-ERK) 1/2, Kv1.5, SAP97, suggesting that ROS participate in Kv1.5 and SAP97 regulation by modulating Ang II-induced P-Smad2/3 and P-ERK 1/2 expression. In conclusion, we demonstrate that ROS-dependent Ang II/AT1 receptor/TGF-β1/P-Smad2/3 and Ang II/ERK 1/2 signalings are involved in atrial Kv1.5 and SAP97 expression. Antioxidants would be beneficial for AF treatment through inhibiting atrial Kv1.5 expression.
authors.affiliation: Department of Cardiology, First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory on Assisted Circulation, Ministry of Health, Guangzhou 510080, China.
authors.forename: Guihua
authors.initials: G
authors.lastname: Lu
authors.affiliation: Department of Cardiology, First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory on Assisted Circulation, Ministry of Health, Guangzhou 510080, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Xu
authors.affiliation: Department of Cardiology, First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China.
authors.forename: Longyun
authors.initials: L
authors.lastname: Peng
authors.affiliation: Department of Cardiology, First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China.
authors.forename: Zhibin
authors.initials: Z
authors.lastname: Huang
authors.affiliation: Department of Cardiology, First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China. Electronic address: yesong_wang@yahoo.com.cn.
authors.forename: Yesong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Cardiology, First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China. Electronic address: xiurengao@163.com.
authors.forename: Xiuren
authors.initials: X
authors.lastname: Gao
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D006325:Heart Atria / Q000166:cytology / Q000378:metabolism; D051666:Kv1.5 Potassium Channel / Q000235:genetics*; D020935:MAP Kinase Signaling System; D008565:Membrane Proteins / Q000235:genetics; D032383:Myocytes, Cardiac / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism; D015398:Signal Transduction; D051899:Smad2 Protein / Q000235:genetics; D051900:Smad3 Protein / Q000235:genetics; D053773:Transforming Growth Factor beta1 / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C501119:Dlg1 protein, rat; D051666:Kv1.5 Potassium Channel; D008565:Membrane Proteins; D017382:Reactive Oxygen Species; D044140:Receptor, Angiotensin, Type 1; D051899:Smad2 Protein; C497784:Smad2 protein, rat; D051900:Smad3 Protein; C497787:Smad3 protein, rat; D053773:Transforming Growth Factor beta1; D000804:Angiotensin II
keywords: Angiotensin II; Antioxidant; ERK 1/2; Kv1.5; ROS; TGF-β(1)