Circadian expression of transcription factor Fra-2 in the rat pineal gland.

Physiological changes in Fos-like immunoreactivity in the rat pineal gland are shown here to be due primarily to changes in a 42/46-kDa Fos-related antigen (Fra). Studies are presented that indicate this 42/46-kDa Fra is Fra-2, a poorly understood member of the Fos family of transcription factors. Both Fra-2 mRNA and protein are absent during the day and increase robustly at night on a circadian basis; organ culture studies indicate that regulation is mediated by an adrenergic-->cyclic AMP mechanism. AP-1 binding activity changes in parallel to changes in the level of Fra-2 protein.