Angiotensin II induces circadian gene expression of clock genes in cultured vascular smooth muscle cells.
BACKGROUND
Daily rhythms of mammalian physiology and endocrinology are regulated by circadian pacemakers. The master circadian pacemaker resides in the suprachiasmatic nucleus, which is located in the hypothalamus of the brain, but circadian oscillators also exist in peripheral tissues. Because many studies have demonstrated apparent circadian variations in the frequency of cardiovascular disorders, it is of great interest to investigate a possible relation between circadian gene expression and cardiovascular function. We examined whether a circadian oscillation system exists in the aorta and/or in cultured vascular smooth muscle cells (VSMCs).


RESULTS
The mRNA levels of clock genes were assayed by northern blot analysis. The mouse aorta showed a clear circadian oscillation in the expression of mPer2, dbp, and Bmal1. Brief treatment of VSMCs with angiotensin II induced a robust increase in mPer2 gene expression, followed by a marked reduction in mPer2 mRNA levels and subsequent synchronous cycling of mPer2, dbp, and Bmal1 mRNAs. The induction of mPer2 in VSMCs by angiotensin II was completely abolished by treatment with CV11947, a specific angiotensin II type1 receptor antagonist.


CONCLUSIONS
The present results demonstrate that the aorta and VSMCs possess a circadian oscillation system which is comparable to that of the suprachiasmatic nucleus and that the circadian gene expression in VSMCs is induced by angiotensin II through the angiotensin II type1 receptor. Our in vitro system will provide a useful tool to further analyze the physiological significance of the peripheral clock in cardiovascular function.
Nonaka
H
H
Division of Cardiovascular and Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan.
Emoto
N
N
Ikeda
K
K
Fukuya
H
H
Rohman
M S
MS
Raharjo
S B
SB
Yagita
K
K
Okamura
H
H
Yokoyama
M
M
D056930:ARNTL Transcription Factors; D000804:Angiotensin II / Q000494:pharmacology*; D057911:Angiotensin Receptor Antagonists; D000818:Animals; D001013:Aorta, Thoracic / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D051792:Basic Helix-Loop-Helix Proteins; D001562:Benzimidazoles / Q000494:pharmacology; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology; D015415:Biomarkers / Q000032:analysis; D001713:Biphenyl Compounds; D015152:Blotting, Northern; D018797:Cell Cycle Proteins; D002478:Cells, Cultured; D002940:Circadian Rhythm / Q000187:drug effects* / Q000502:physiology; D004268:DNA-Binding Proteins; D015870:Gene Expression / Q000187:drug effects* / Q000502:physiology; D007093:Imidazoles / Q000494:pharmacology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D056950:Period Circadian Proteins; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D051381:Rats; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D013777:Tetrazoles / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D056930:ARNTL Transcription Factors; D000804:Angiotensin II; D057911:Angiotensin Receptor Antagonists; D051792:Basic Helix-Loop-Helix Proteins; D001562:Benzimidazoles; D015415:Biomarkers; D001713:Biphenyl Compounds; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D007093:Imidazoles; D009687:Nuclear Proteins; D056950:Period Circadian Proteins; D011725:Pyridines; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D013777:Tetrazoles; D014157:Transcription Factors; C538961:Bmal1 protein, mouse; C485975:DBP protein, rat; C498260:Dbp protein, mouse; C539023:Per1 protein, mouse; C539024:Per1 protein, rat; C513312:Per2 protein, mouse; C513311:Per2 protein, rat; C073402:PD 123319; C081643:candesartan