Abnormal expressions of circadian-clock and circadian clock-controlled genes in the livers and kidneys of long-term, high-fat-diet-treated mice.
OBJECTIVE
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.
Hsieh
M-C
MC
Institute of Physiological and Anatomical Medicine (formerly Institute of Integrative Physiology and Clinical Sciences), Tzu Chi University, Hualien, Taiwan. krshieh@mail.tcu.edu.tw
Yang
S-C
SC
Tseng
H-L
HL
Hwang
L-L
LL
Chen
C-T
CT
Shieh
K-R
KR
D000818:Animals; D001835:Body Weight / Q000235:genetics*; D056926:CLOCK Proteins / Q000235:genetics / Q000378:metabolism; D002940:Circadian Rhythm / Q000235:genetics*; D056925:Circadian Rhythm Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D004041:Dietary Fats / Q000008:administration & dosage; D005786:Gene Expression Regulation; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D024821:Metabolic Syndrome / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009765:Obesity / Q000235:genetics* / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics
D056925:Circadian Rhythm Signaling Peptides and Proteins; D004041:Dietary Fats; D015534:Trans-Activators; D056926:CLOCK Proteins; C538944:Clock protein, mouse