| Abstrakt: |
Gonadal aromatase (Cyp19a1a) plays a pivotal role in gonadal sex differentiation, especially in lower vertebrates like teleosts. The transcription of cyp19a1agene in the ovary has been shown to be up-regulated by Ftz-f1 homologues, which can be enhanced by Foxl2 synergistically. In the present study, a foxl2gene (efoxl2) and two Ftz-f1 homologue genes, designated as eff1aand eff1brespectively, were cloned from the gonad of ricefield eel. Furthermore, a C-terminal truncated form of eff1atranscripts, designated as eff1a-s, was also identified in the gonad. Sequence analysis showed that eff1a-slacked the ligand binding domain including motifs for I-Box, DRD, and AF-2, and is probably generated by 3'-end alternative splicing and polyadenylation of eff1atranscripts. RT-PCR analysis detected the expression of efoxl2, eff1b, eff1a, and eff1a-sin the gonads of ricefield eel, with higher expression levels of eff1ain the ovary than testis, and higher expression levels of eff1band eff1a-sin the testis than the ovary. As potential binding sites for Ftz-f1 and Foxl2 were observed in the proximal promoter region of ricefield eel cyp19a1a, an in vitro transient transfection assay was employed to examine the effects of eFoxl2, eFf1b, eFf1a, and eFf1a-s on the promoter activity of ricefield eel cyp19a1agene. Both eFf1b and eFf1a activated the transcription of cyp19a1a, whereas eFf1a-s repressed the basal as well as eFf1b and eFf1a-mediated transcription of cyp19a1a. eFoxl2 alone seemed to activate the transcription of cyp19a1awith higher potency than either eFf1b or eFf1a, and the activation was further enhanced very significantly in the presence of eFf1a, but not eFf1b. These results indicated that Foxl2 could interact with Ftz-f1 homologues to up-regulate the transcription of cyp19a1agene differentially, and the molecular basis for this differential interaction is worth further study. This research was supported by Natural Science Foundation of China (30970359, 30771651) and National High Technology Research and Development Program of China (863 Program) (No.2008AA09Z406).(poster) |
