Identification and sequencing of pineal-specific enhancing region in the mouse tryptophan hydroxylase promoter

Pineal-specific expression of the tryptophan hydroxylase (TPH) gene has bee n demonstrated by a number of studies. However, little is known about the r egulatory mechanism for pineal-specific expression of the TPH gene. To iden tify the cis-acting region responsible for pineal-specific expression of th e TPH gene, we investigated a 6.1-kb 5'-flanking region of the mouse TPH ge ne using an immortalized pineal cell line (PGT-beta) derived from transgeni c mice. By deletion analysis, it was demonstrated that the pineal-specific enhancing region resides approximately between -6.1 and -4.7 kb upstream fr om the transcription initiation site of the mouse TPH gene. Additionally, n ucleotide sequence analysis of this region showed that the (AC/TG)(22) repe titive sequence is located approximately -5.78 kb upstream of the mouse TPH gene, and several known tissue-specific cis-acting elements, such as Pit-1 and the pituitary specific element (PSE), have also been identified in the region. We believe that the analysis of the sequence and several cis-actin g elements ire the pineal-specific enhancing region of the mouse TPH promot er would enhance our understanding of the precise mechanism of pineal-speci fic expression.