College of Biological and Environmental Engineering, Zhejiang University of Technology, Zhejiang 310032, China.
Chronobiol Int. 2010 Jan;27(1):1-18. doi: 10.3109/07420520903398625.
The synchronization of the master clock to photic cues is associated with a rapid induction of Per1, which plays an important role in initiating light-induced circadian resetting. However, the transcriptional mechanisms of clock gene expression in food-entrainable peripheral clocks have not been fully assessed. To understand how food cues might entrain a mammalian peripheral clock, we examined the responses in the expression of clock genes in rat livers to different feeding stimuli. The food-entrainable liver clock is more flexible than the light-entrainable SCN clock and can be reset rapidly at any time of day. A 30 min feeding stimulus was sufficient to significantly induce the expression of Per2 and Dec1 within 1 h and alter the transcript levels and circadian phases of other selected clock genes (Bmal1, Cry1, Per1, Per3, Dec2, and Rev-erba) in the liver clock at longer time intervals. Moreover, among the examined clock genes, Per2 was most sensitive to food cues, which could be significantly induced by a minimal amount of food. Furthermore, in contrast to the other hepatic clock genes, the feeding reversal-induced 12 h phase shift of Per2 could be rapidly and consistently accomplished, regardless of the shift of the light/dark cycle. In conclusion, the feeding-induced resetting of the circadian clock in the liver is associated with the acute induction of Per2 and Dec1 transcription, which may serve as the main and secondary input regulators that initiate this feeding-induced circadian resetting.
主钟对光刺激的同步与 Per1 的快速诱导有关,Per1 在启动光诱导的生物钟重置中起着重要作用。然而,食物可诱导的外周生物钟中时钟基因表达的转录机制尚未得到充分评估。为了了解食物线索如何使哺乳动物外周生物钟同步,我们研究了不同进食刺激对大鼠肝脏中时钟基因表达的反应。与光可诱导的 SCN 生物钟相比,食物可诱导的肝脏生物钟更加灵活,可以在一天中的任何时间快速重置。30 分钟的进食刺激足以在 1 小时内显著诱导 Per2 和 Dec1 的表达,并在较长时间间隔内改变其他选定的时钟基因(Bmal1、Cry1、Per1、Per3、Dec2 和 Rev-erba)在肝脏生物钟中的转录水平和昼夜相位。此外,在所检查的时钟基因中,Per2 对食物线索最敏感,只需少量食物即可显著诱导。此外,与其他肝脏时钟基因相比,进食逆转诱导的 Per2 12 小时相位偏移可以快速且一致地完成,而与光/暗周期的偏移无关。总之,肝脏中生物钟的进食诱导重置与 Per2 和 Dec1 转录的急性诱导有关,这可能是启动这种进食诱导的生物钟重置的主要和次要输入调节剂。