Hsieh MC, Yang SC, Tseng HL, Hwang LL, Chen CT, Shieh KR. Abnormal expressions of circadian-clock and circadian clock-controlled genes in the livers and kidneys of long-term, high-fat-diet-treated mice.
Int J Obes (Lond) 2009;
34:227-39. [PMID:
19901953 DOI:
10.1038/ijo.2009.228]
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Abstract
OBJECTIVES
Physiological and behavioral circadian rhythmicities are exhibited by all mammals and are generated by intracellular levels of circadian oscillators, which are composed of transcriptional/translational feedback loops involving a set of circadian-clock genes, such as Clock, Per1-3, Cry1-2, Bmal1, Dbp, E4BP4 and CK1varepsilon. These circadian-clock genes play important roles in regulating circadian rhythms and also energy homeostasis and metabolism. Determining whether obesity induced by high-fat diet affected the expressions of circadian-clock genes and their related genes in peripheral tissues, was the main focus of this study. To address this issue, we fed male C57BL/6 mice a high-fat diet for 11 months to induce obesity, hyperglycemic, hypercholesterolemic and hyperinsulinemic symptoms, and used quantitative real-time reverse transcription-PCR to measure gene expression levels.
RESULTS
We found that the expressions of circadian-clock genes and circadian clock-controlled genes, including Per1-3, Cry1-2, Bmal1, Dbp, E4BP4, CK1varepsilon, PEPCK, PDK4 and NHE3, were altered in the livers and/or kidneys.
CONCLUSIONS
These results indicate that obesity induced by high-fat diet alters the circadian-clock system, and obesity and metabolic syndrome are highly correlated with the expressions of circadian-clock genes and their downstream, circadian clock-controlled genes.
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