THE QUAIL TYROSINE-HYDROXYLASE GENE PROMOTER CONTAINS AN ACTIVE CYCLIC AMP-RESPONSIVE ELEMENT

A 1,5-kb genomic DNA fragment situated upstream from the quail tyrosine hydroxylase (TH) gene transcription site was isolated. This upstream region starts 15 bp from the translation initiation site. It contains two canonical TATA boxes, at positions -37 and -297, three putative glucocorticoid-responsive elements, at positions -1487, -1329, and -1268, and one putative cyclic AMP (cAMP)-responsive element (CRE) at position -53, as well as a putative negative regulatory element consensus sequence at position -735. The consensus POU-Oct site is partly conserved. Comparison of the 5' flanking sequences of quail and mammalian (bovine, human, and rat) TH genes revealed a strong sequence conservation within the 230 nucleotides upstream of the TATA box, with a distinct conservation of the CRE region. Constructs in which the bacterial chloramphenicol acetyltransferase (CAT) reporter gene was linked to promoter stretches of increasing lengths were transfected into three cell lines, two of them originating from quail and rat neural crest and the third derived from mouse fibroblasts. Reporter gene expression was specifically high in the quail and rat neural crest-derived cells compared to the fibroblast cell line. The physiological activity of this putative quail CRE was analyzed further in transfected neural crest cells of quail origin. Both cAMP analogues and agents that enhance intracellular cAMP increased CAT activity. The physiological relevance of this finding is sustained by the presence, in quail nuclear extracts, of a protein(s) that binds CRE consensus sequences.