Angiotensin II does not influence expression of sarcoplasmic reticulum Ca2 + ATPase in atrial myocytes.
BACKGROUND
The sarcoplasmic reticulum Ca(2+) ATPase (SERCA) is essential for the regulation of the intracellular calcium level in cardiomyocytes. Previous studies have found that angiotensin II (Ang II) decreased SERCA2 gene expression in ventricular myocytes. Alteration of SERCA activity is important in the mechanism of atrial fibrillation. The present study was undertaken to examine Ang II effects on atrial myocytes.


METHODS
An approximately 1.75-kb promoter region of SERCA2 gene was cloned with the pGL3 luciferase vector. The direct effects of Ang II on SERCA2 gene expression in HL-1 atrial myocytes were examined by promoter activity assay, followed by Western blot analysis for protein levels and quantitative real-time reverse transcription polymerase chain reaction for mRNA amounts.


RESULTS
Ang II did not increase the promoter activity of the 1,754-bp promoter-receptor construct of the SERCA2 gene. The levels of SERCA2 protein and mRNA were also unchanged at different time points after Ang II treatment.


CONCLUSIONS
Although Ang II had prominent effects on SERCA2 in ventricular myocytes, it did not alter SERCA2 gene expression and protein levels in atrial myocytes. We provide a model for further investigation of the regulation of SERCA2 gene expression in atrial myocytes.
Wu
Cho-Kai
CK
Department of Internal Medicine, National Taiwan University College of Medicine and Hospital Yun-Lin Branch, Yun-Lin, Taiwan.
Tseng
Chuen-Den
CD
Huang
Yin-Tsen
YT
Hsieh
Chia-Shan
CS
Tsai
Wei-Shan
WS
Lin
Jiunn-Lee
JL
Chiang
Fu-Tien
FT
Tsai
Chia-Ti
CT
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001665:Binding Sites; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D006325:Heart Atria / Q000166:cytology*; D051379:Mice; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000201:enzymology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000235:genetics* / Q000378:metabolism*; D014162:Transfection
D012333:RNA, Messenger; D000804:Angiotensin II; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases