FOXO1 Suppresses SMAD-Induced <i>Fshb</i> Gene Expression.

<p>A–B. The −1000 murine <i>Fshb</i>-luc plasmid was transfected into LβT2 cells along with 100 ng of pALTER empty vector (EV), FOXO1-CA or FOXO1-CA-DBD mutant, as well as 100 ng of pRK5 EV, 50 ng SMAD3 or SMAD4 with 50 ng of pRK5, or 50 ng SMAD3 and SMAD4 expression vectors, as indicated. Cells were incubated in serum-free media for 24 h before harvest. The results represent the mean ± SEM of three experiments performed in triplicate and are presented as fold SMAD induction relative to the pRK5 EV. * indicates that <i>Fshb</i> transcription is significantly repressed by FOXO1-CA compared to EV using Student's <i>t</i>-test (A) while the different uppercase letters indicate that <i>Fshb</i> transcription is significantly repressed by FOXO1-CA compared to EV or FOXO1-CA-DBD using one-way ANOVA followed by Tukey's post-hoc test (B). C. 4×SBE-luc or 4×FLRE-luc plasmids were transfected into LβT2 cells along with 200 ng of pALTER EV, FOXO1-CA or FOXO1-CA-DBD. After overnight incubation in serum-free media, cells were treated for 6 h with 0.1% BSA or 10 ng/mL activin. The results represent the mean ± SEM of three experiments performed in triplicate and are presented as fold activin induction relative to the vehicle control. The different uppercase letters indicate that transcription of the 4×SBE-luc is significantly reduced by FOXO1-CA compared to EV or FOXO1-CA-DBD using one-way ANOVA followed by Tukey's post-hoc test while there is no significant difference in transcription of the 4×FLRE-luc.</p>