QUAIL PAX-6 (PAX-QNR) ENCODES A TRANSCRIPTION FACTOR ABLE TO BIND ANDTRANS-ACTIVATE ITS OWN PROMOTER

Proper growth and development of multicellular organisms requires prec ise regulation of developmental genes. One aspect of this regulation i s at the level of transcription from the gene promoters. As an initial approach to understanding the regulation of the Pax-6 gene, which pla ys an important role in eye development and perhaps in other developme ntal processes, we characterized a promoter region of the quail Pax-6 (Pax-QNR) gene. Sequence analysis of the 5' flanking region revealed a TATA-like box and a CAAT box as well as several putative cis-regulato ry elements. A 1.5-kilobase pair fragment, containing 1386 base pairs of 5' flanking sequence, the first exon, and a portion of the first in tron, was able to efficiently promote expression of the bacterial CAT gene in quail neuroretina cells. Cotransfection of the Pax-QNR promote r with a vector expressing the 46 kilodalton Pax-QNR protein resulted in an increase in Pax-QNR promoter activity. By electrophoretic migrat ion shift assay and immunoselection experiments, we showed that the Pa x-QNR protein can interact directly with the Pax-QNR promoter. By foot printing experiments, we identified the binding sites for the Pax-QNR protein within the promoter region. These results show that Pax-QNR en codes a transcriptional activator and that it potentially trans-activa tes its own promoter.