ROUND-SPOTTED PUFFERFISH (TETRAODON FLUVIATILIS) SNF5 GENE IS ORIENTED IN A TAIL-TO-TAIL MANNER WITH THE SET GENE WHICH ENCODES AN INHIBITOR OF PROTEIN PHOSPHATASE 2A

The round-spotted pufferfish Tetraodon fluviatilis has a genome size o f 380 Mb which is slightly smaller than that of another pufferfish Fug u rubripes rubripes (Fugu). Due to its compact genome and small intron s, Fugu has been introduced as a model for genome studies. Recently, t he round-spotted pufferfish has also been proposed as a nem model for genome studies because of the ease in obtaining material and high-sequ ence homology to that of Fugu. In this study, me have cloned and chara cterized the snf5 and set genes from the round-spotted pufferfish. The snf5 gene is composed of 9 exons spanning about 2.9 kb whereas the se t gene consists of 8 exons spanning about 2.7 kb. They are linked in a tail-to-tail manner with an intergenic region of about 6.5 kb. So far , the genomic structures of human snf5 and set genes are unknown. Base d on our data, the pufferfish SNF5 and SET display high amino acid seq uence identity (>90%) with the respective human genes. By primer exten sion and sequence analysis, we found that putative promoter region of the snf5 gene contains a typical TATA box and numerous potential bindi ng sites for transcription factors including AP1, AP2, AP3, c-Myb, HNF -5, and NF-IL6. As for the set gene, its promoter region does not have any TATA or CCAAT motif and contains a few potential binding sites fo r transcriptional factors such as c-Myb and gamma-IRE. When these prom oter regions were placed upstream of the CAT reporter gene and transfe cted into a carp CF cell line, the 5'-upstream 1.6-kb DNA fragment of the snf5 gene displayed stronger promoter activity, approximately thre e-fold higher than that of the 5'-upstream 1.3 kb DNA fragment of the set gene. By transient expression and immunofluorescent staining, we a lso showed that the pufferfish SNF5 and SET are nuclear proteins, cons istent with their postulated roles as transcriptional factors.