【Abstract】Objective To explore whether HIV TATprotein can affect the expression of Clock, Cry,Bmal1,Per in the cell. Methods HIVTat protein expression plasmids were transfected into PC12 with lipofectamine TM 2000, and Tat was expressed in PC12.mRNA and protein were extracted 48 hours after transfection, and the expression of rhythm gene was detected by realtime quantitative PCR and Western blot, respectively.Results The results showed that the expression level of Cry1was significantly increased（P＜0.05）. The expression ofClock was significantly decreased（P＜0.05）. The expression of Bmal1and Perwas not significantly changed in transfected Tatexpressing plasmid compared with untransfected and empty plasmid. Conclusion HIV Tat affects the expression of the circadian genes Cry1 and Clock, which is related to the decrease ofClock expression and the increase of Cry1 expression, Suggesting that TAT protein can affect the expression of rhythmic genes and may regulate the physiological function of cells through the influence of circadian rhythm.