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.
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.
Tsai
Chia-Ti
CT
Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.
Wang
Danny Ling
DL
Chen
Wen-Pin
WP
Hwang
Juey-Jen
JJ
Hsieh
Chia-Shan
CS
Hsu
Kuan-Lih
KL
Tseng
Chuen-Den
CD
Lai
Ling-Ping
LP
Tseng
Yung-Zu
YZ
Chiang
Fu-Tien
FT
Lin
Jiunn-Lee
JL
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
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