GENOMIC STRUCTURE AND PROMOTER REGION OF C-FOS GENE OF ROUND-SPOTTED PUFFERFISH, TETRAODON NIGROVIRIDIS (SYN T-FLUVIATILIS)

The round-spotted pufferfish c-fos gene was isolated from a liver geno mic library. Complete DNA sequences, including 0.75-kb of-the promoter region were determined. Our data indicate that this gene is composed of 4 exons and 3 introns spanning about 3 kb. This gene encodes a prot ein of 374 amino acids with a molecular mass of 42 262 Da. The amino a cid sequence identities between this puffer fish c-fos protein and fug u (another pufferfish species), human, mouse, and chicken c-fos protei n are 90%, 58%, 58%, and 53%, respectively. Two potential transcriptio n initiation sites were located by primer extension analysis. Examinat ion of 0.75-kb of a 5'-flanking sequence revealed potential binding si tes for a variety of transcription factors such as CREB, E2A, Ets-l, G ATA-1, HNF-5, c-Myb, and Spt. When the 0.9-kb DNA fragment (-746 to +1 53) was placed upstream of the chloramphenicol acetyltransferase (CAT) reporter gene and transfected into a carp CF cell line, it could driv e the synthesis of CAT enzyme 2.7 times more efficiently than could th e RSV promoter. Although lacking the known serum-response element, the CAT activity of this region still could be induced by serum.