Zebrafish ftz-f1 gene has two promoters, is alternatively spliced, and is expressed in digestive organs

Fushi-tarazu Factor-1 (FTZ-F1) is a family of nuclear receptors involved in various developmental processes. We have cloned a zebrafish FTZ-F1 gene, t ermed ff1, which belongs to the fetoprotein transcription factor/liver rece ptor homologue-1 (FTF/ LRH-1) subgroup of the FTZ-F1 family. Four transcrip ts arise as a result of differential promoter usage and alternative splicin g at the 3'-most exons. The longer transcript, form A, encodes a transcript ional activator. The shorter transcript, form B, lacks the activation domai n, and hence could not activate transcription. The difference in promoter u sage generates FF1 proteins with different N-terminal sequences. All four t ranscripts appear to be expressed in most of the adult tissues, whereas, du ring embryo development, the IIA form is the predominant transcript. Revers e transcriptase-PCR and in situ hybridization experiments showed that the f f1 transcript is expressed in the hypothalamus, spinal cord, mandibular arc h and digestive organs, including pancreas, liver, and intestine. The expre ssion of ff1 in the digestive organs implies its function in gut developmen t.