Forskolin induces circadian gene expression of rPer1, rPer2 and dbp in mammalian rat‐1 fibroblasts

Mammalian culture cells have the potential for periodicity, since high concentrations of serum can elicit the circadian expression of clock genes in rat‐1 fibroblasts. However, the mechanism by which serum affects circadian gene expression remains unclear. In the present study, we incubated rat‐1 cells with forskolin and successfully induced the rhythmic expression of Per1, Per2 and dbp. In the initial step of the circadian gene expression, a marked transient induction of Per1 was observed accompanied with CREB phosphorylation. Thus the present study strongly suggests that CREB activation through the cAMP/PKA pathway is involved in the generation of circadian rhythm in rat‐1 cells

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