Abstract
In mammals, BMAL1 and CLOCK activate transcription of the period (Per1 and Per2) and cryptochrome (Cry1 and Cry2) genes via E-box binding in the promoter region of these genes, and the translated gene products negatively regulate their own transcription by binding the BMAL1/CLOCK heterodimer complex. Recently, it was revealed that rhythms in histone acetylation are necessary for rhythmic transcription of these genes and that the histone acetyl transferase responsible is CLOCK. We reported that Bmal1 expression oscillates in the peripheral organs of mice carrying the Bmal1 promoter reporter. To explore the role of histone acelylation in transcription of the Bmal1 gene and the circadian oscillation, we examined the effect of SRC-1, pCIP, and GRIP1 on the basal transcription and RORα-mediated transcription of the Bmal1 gene using a luciferase assay and real-time luciferase monitoring system. Here, we show that SRC-1, pCIP, and GRIP1 enhance the Bmal1 transcription and RORα-mediated transcription, and that SRC-1, pCIP, and GRIP1 enhance the amplitude of the circadian oscillation of the Bmal1 promoter reporter without changing the phase and period. [J Physiol Sci. 2007;57 Suppl:S62]
