Gonadotrope-specific expression and regulation of ovine follicle stimulating hormone Beta: transgenic and adenoviral approaches using primary murine gonadotropes.

ABSTRACT: The beta subunit of follicle stimulating hormone (FSHB) is expressed specifically in pituitary gonadotropes in vertebrates. Transgenic mouse studies have shown that enhancers in the proximal promoter between -172/-1 bp of the ovine FSHB gene are required for gonadotrope expression of ovine FSHB. These enhancers are associated with regulation by activins and gonadotropin releasing hormone (GnRH). Additional distal promoter sequence between -4741/-750 bp is also required for expression. New transgenic studies presented here focus on this distal region and narrow it to 1116 bp between -1866/-750 bp. In addition, adenoviral constructs were produced to identify these critical distal sequences using purified primary mouse gonadotropes as an in vitro model system. The adenoviral constructs contained -2871 bp, -750 bp or -232 bp of the ovine FSHB promoter. They all showed gonadotrope-specific regulation since they were induced only in purified primary gonadotropes by activin A (50 ng/ml) and inhibited by GnRH (100 nM) in the presence of activin (except -232FSHBLuc). However, basal expression of all three viral constructs (in the presence of follistatin to block cellular induction by activin) was relatively high in pituitary non-gonadotropes as well as gonadotropes. Thus, gonadotrope-specific regulation associated with the proximal promoter was observed as expected, but the model was blind to distal promoter elements between -2871/-750 necessary for gonadotrope-specific expression of ovine FSHB in vivo. The new adenoviral-based in vitro technique did detect, however, a novel GnRH response element between -750 bp and -232 bp of the ovine FSHB promoter. We conclude that adenoviral-based studies in primary gonadotropes can adequately recognize regulatory elements on the ovine FSHB promoter associated with gonadotrope-specific regulation/expression, but that more physiologically based techniques, such as transgenic studies, will be needed to identify sequences between -1866/-750 bp of the ovine FSHB promoter that are also required for tissue/cell specific expression in vivo.

SUBMITTER: Jia J 

PROVIDER: S-EPMC3715487 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature