Expression of the rabbit cytochrome P450 aromatase encoding gene uses alternative tissue-specific promoters

The aim of the present study was to analyse the tissue-specific expression of various promoter-derived transcripts from the gene encoding rabbit aroma tase cytochrome P450. A new promoter, named I.r, was identified, and promot ers II and I.r were sequenced. Promoter I.r-derived transcripts were found in preovulatory granulosa cells, corpus luteum, placenta and adipose tissue . An alternative splice variant of this transcript was found with tissue-sp ecific preference. Tissue-specific expression of promoter-derived variants was studied in the ovary before and after ovulation. While the level of pro moter II-derived transcript decreased dramatically after ovulation, that of promoter I.r-derived transcript remained unchanged, indicating that promot er II and promoter I.r were not controlled by a single regulation system. T he existence of this dual system of regulation suggests that the rabbit ova ry could be a useful model to study the promoter-specific regulation of aro matase.