title: Angiotensin II increases expression of alpha1C subunit of L-type calcium channel through a reactive oxygen species and cAMP response element-binding protein-dependent pathway in HL-1 myocytes.
abstract: Angiotensin II (Ang II) is involved in the pathogenesis of atrial fibrillation (AF). L-type calcium channel (LCC) expression is altered in AF remodeling. We investigated whether Ang II modulates LCC current through transcriptional regulation, by using murine atrial HL-1 cells, which have a spontaneous calcium transient, and an in vivo rat model. Ang II increased LCC alpha1C subunit mRNA and protein levels and LCC current density, which resulted in an augmented calcium transient in atrial myocytes. An approximately 2-kb promoter region of LCC alpha1C subunit gene was cloned to the pGL3 luciferase vector. Ang II significantly increased promoter activity in a concentration- and time-dependent manner. Truncation and mutational analysis of the LCC alpha1C subunit gene promoter showed that cAMP response element (CRE) (-1853 to -1845) was an important cis element in Ang II-induced LCC alpha1C subunit gene expression. Transfection of dominant-negative CRE binding protein (CREB) (pCMV-CREBS133A) abolished the Ang II effect. Ang II (1 micromol/L, 2 hours) induced serine 133 phosphorylation of CREB and binding of CREB to CRE and increased LCC alpha1C subunit gene promoter activity through a protein kinase C/NADPH oxidase/reactive oxygen species pathway, which was blocked by the Ang II type 1 receptor blocker losartan and the antioxidant simvastatin. In the rat model, Ang II infusion increased LCC alpha1C subunit expression and serine 133 phosphorylation of CREB, which were attenuated by oral losartan and simvastatin. In summary, Ang II induced LCC alpha1C subunit expression via a protein kinase C-, reactive oxygen species-, and CREB-dependent pathway and was blocked by losartan and simvastatin.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Chia-Ti
authors.initials: CT
authors.lastname: Tsai
authors.forename: Danny Ling
authors.initials: DL
authors.lastname: Wang
authors.forename: Wen-Pin
authors.initials: WP
authors.lastname: Chen
authors.forename: Juey-Jen
authors.initials: JJ
authors.lastname: Hwang
authors.forename: Chia-Shan
authors.initials: CS
authors.lastname: Hsieh
authors.forename: Kuan-Lih
authors.initials: KL
authors.lastname: Hsu
authors.forename: Chuen-Den
authors.initials: CD
authors.lastname: Tseng
authors.forename: Ling-Ping
authors.initials: LP
authors.lastname: Lai
authors.forename: Yung-Zu
authors.initials: YZ
authors.lastname: Tseng
authors.forename: Fu-Tien
authors.initials: FT
authors.lastname: Chiang
authors.forename: Jiunn-Lee
authors.initials: JL
authors.lastname: Lin
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000502:physiology*; D004247:DNA / Q000378:metabolism; D019808:Losartan / Q000494:pharmacology; D032383:Myocytes, Cardiac / Q000378:metabolism*; D019255:NADPH Oxidases / Q000502:physiology; D011493:Protein Kinase C / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020218:Response Elements / Q000502:physiology; D019821:Simvastatin / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D020746:Calcium Channels, L-Type; D017362:Cyclic AMP Response Element-Binding Protein; C419385:L-type calcium channel alpha(1C); D017382:Reactive Oxygen Species; D013481:Superoxides; D000804:Angiotensin II; D004247:DNA; D019821:Simvastatin; D019255:NADPH Oxidases; D011493:Protein Kinase C; D019808:Losartan; D002118:Calcium