title: Down-regulation of ether-a-go-go-related gene potassium channel protein through sustained stimulation of AT1 receptor by angiotensin II.
abstract: We investigated the effects of AT1 receptor stimulation by angiotensin II (Ang II) on human ether-a-go-go-related gene (hERG) potassium channel protein in a heterogeneous expression system with the human embryonic kidney (HEK) 293 cells which stably expressed hERG channel protein and were transiently transfected with the human AT1 receptors (HEK293/hERG). Western-blot analysis showed that Ang II significantly decreased the expression of mature hERG channel protein (155-kDa band) in a time- and dose-dependent manner without affecting the level of immature hERG channel protein (135-kDa band). The relative intensity of 155-kDa band was 64.7±6.8% of control (P<0.01) after treatment of Ang II at 100nM for 24h. To investigate the effect of Ang II on the degradation of mature hERG channel protein, we blocked forward trafficking from ER to Golgi with a Golgi transit inhibitor brefeldin A (10μM). Ang II significantly enhanced the time-dependent reduction of mature hERG channel protein. In addition, the proteasomal inhibitor lactacystin (5μM) inhibited Ang II-mediated the reduction of mature hERG channel protein, but the lysosomal inhibitor bafilomycin A1 (1μM) had no effect on the protein. The protein kinase C (PKC) inhibitor bisindolylmaleimide 1 (1μM) antagonized the reduction of mature hERG channel protein induced by Ang II. The results indicate that sustained stimulation of AT1 receptors by Ang II reduces the mature hERG channel protein via accelerating channel proteasomal degradation involving the PKC pathway.
authors.affiliation: The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Cai
authors.affiliation: The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China.
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Xu
authors.affiliation: The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Zuo
authors.affiliation: The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province; Department of Pharmacology, Hebei Medical University, Shijiazhuang 050017, China. Electronic address: yanfangxu@hotmail.com.
authors.forename: Yanfang
authors.initials: Y
authors.lastname: Xu
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology*; D020126:Brefeldin A / Q000494:pharmacology; D000072237:ERG1 Potassium Channel; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D051638:Ether-A-Go-Go Potassium Channels / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D018942:Macrolides / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex / Q000187:drug effects / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D055550:Protein Stability; D021381:Protein Transport / Q000187:drug effects; D059748:Proteolysis / Q000187:drug effects; D044140:Receptor, Angiotensin, Type 1 / Q000819:agonists* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection
chemical_list: D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; D007211:Indoles; C000606913:KCNH2 protein, human; D018942:Macrolides; D008301:Maleimides; D044140:Receptor, Angiotensin, Type 1; D000804:Angiotensin II; C067713:lactacystin; D020126:Brefeldin A; C040929:bafilomycin A1; D011493:Protein Kinase C; D046988:Proteasome Endopeptidase Complex; C088060:bisindolylmaleimide; D000111:Acetylcysteine
keywords: AT(1) receptor; Protein degradation; Protein kinase C; hERG channel protein