| In most organisms from lower species to higher ones, various physiological and behavioral functions are expressed rhythmically across day and night. These daily rhythms, referred to as circadian, are controlled by self-sustained biological oscillators, which involve transcriptional- translational feedback loops of circadian genes, namely, Per1/2/3, Cry1/2, Clock, Bmal1, and CKIε. In mammals, the master circadian oscillator resides in the suprachiasmatic nuclei (SCN) of the hypothalamus, but it was also found in peripheral organs, such as liver, kidney, and fibroblast cells.Circadian fluctuations in the immune system have been observed for a long time. However, few reports were found in literature for the mechanism of circadian rhythms in the immune system in terms of circadian clock genes.Objective: To establish the cell model of biological clock in the immune system in order to provide basic data for the study on mechanisms of circadian rhythms outside the central system.Methods: The circadian expression pattern of the Clock and melatonin receptor genes(mt1,mt2) in peripheral lymphocytes were determined by semi-quantitative RT-PCR. The Clock-controlled genes were screened and identified by the techniques of differential display reverse transcription- polymerase chain reaction(DDRT-PCR), RNA interference(RNAi) and quantitative real-time PCR.Results: Thirty-one bands were screened based on differential expression in a circadian day. Among the 31 bands, 10 cDNA fragments were determined. Three of the 10 cDNA were identified as the clock-controlled genes(CCG), that is, the catalase, myelin proteolipid protein(plp) and histone acetylase gene.Conclusion: Biological clock genes underlying circadian rhythms were revealed in peripheral blood lymphocytes of rats, including the Clock gene, the clock-related genes of mtl and mt2, and the clock-controlled genes. The findings suggest that an independent clock system might exist in the mammalian lymphocytes.
|
PDF Full Text Request