Circadian expressions of related genes of cry2,per2,timeless and rev-erb in peripheral white blood cells in mice

Objective To investigate features of circadian expressions of related genes of cry2,per2,timeless and rev-erb in peripheral white blood cells in mice under the 12 h-light and 12 h-dark cycle conditions. Methods Forty-eight male C57 /BL6 mice were randomly divided into 6 groups,with each group directed to a corresponding time point. The animals were kept under the light regimen of LD cycle( 12L /12D) for four weeks. Then,peripheral blood samples were taken at 6 time points( 9: 00,13: 00,17: 00,21: 00,1: 00,5: 00) and white blood cells were separated. Total RNA was extracted from the white blood cells and mRNA levels of each gene( cry2,per2,timeless and rev-erb) were detected by reverse transcription polymerase chain reaction( real time PCR) at different time points. The data were analyzed both by the cosine function software and the amplitude F test to investigate the circadian rhythm. Results Under the light regimen of LD cycle,the four genes in white blood cells showed a significant circadian oscillation,with the apexes of different genes being obviously higher than the troughs( P 0. 01). The apex of per2 was at about 4: 00,while the apex of the other three genes were at about 11: 00-12: 00. From the standpoints of apex time and oscillation,the apex time of cry2,timeless and rev-erb was before that of per2,with a higher level of amplitude than that of per2. The apex time of cry2,timeless,rev-erb mRNA was before that of per2,with the amplitude being higher than that of per2. However,the mRNAs of cry2,timeless and rev-erb showed a similar apex time and amplitude. Conclusion Research findings demonstrated that the expressions of the 4 genes in peripheral white blood cells showed an obvious circadian rhythm. It seemed that the effects of cry2,timeless and rev-erb were stronger than that of per2 in the negative regulation,while the effect of rev-erb was similar in the negative regulation. This research might not only be helpful to the deep understanding of the circadian fluctuation of immune function in mammals,but provide a target for diagnosis and therapy of immune disorders as well. Further detail study was required to fully understand how these 4 genes regulate immune cells in the peripheral blood.