Foxl2 is a forkhead transcription factor widely studied in mammals for its crucial role in ovarian development, physiology and maintenance. Its role in teleost reproduction has been directly associated with the transcriptional activation of various steroidogenic enzyme genes, such as cyp19a1a or cyp19a1b. An ancient paralog named foxl3 (previously known as foxl2b) has only been studied in some teleost species, although it has been described in other vertebrate clades. Recent reports suggest that while Foxl2 seems to be involved in ovarian processes, Foxl3 could be more related with testis physiology. In this study, we first focused on the first year of life of the European sea bass (Dicentrarchus labrax). Expression of both genes in gonads is highly correlated with the female marker cyp19a1a during gonad differentiation. Then, using antibodies against Foxl2 and Foxl3 we studied their cellular localization in both male and female adult gonads. As both Foxl factors were present in ovarian follicular cells, we analyzed the effect of different factors potentially regulating foxl2 and foxl3 transcription in two ovary culture systems. 8Br-cAMP, an analog of cAMP, has a stimulatory effect on the transcription of both foxl genes, and Lh upregulates foxl2 expression. However, the effects of Fsh and estradiol are unclear and cortisol clearly represses foxl2 expression. Next, using cyp19a1a promoter luciferase constructs, we localized the Foxl2 DNA binding site. We demonstrate that, as for Foxl2, Foxl3 interacts with Ff1b (Nr5a1a) to upregulate in vitro cyp19a1a transcription through the same binding site. Combining this information with other reports, we suggest a binding matrix for Foxl3. All together we present for the first time data about gene expression regulation, cellular localization and DNA target sequence of Foxl3, providing innovative information on the putative role of Foxl3 in reproduction, which might be more ambiguous than initially suggested.

Comunicación presentada en la 27th Conference of European Comparative Endocrinologists, celebrada en Rennes, Francia, del 25 al 29 de agosto de 2014

Supported by MICINN (AGL2011-28890 to A.G., PhD-fellowship to O.L-C- W), GV (ACOMP/2013/085)

Peer Reviewed