Figure 5. A robust network repressing SOX9 expression and promoting estradiol signaling.
(A) Western blot analysis of SOX9 and GAPDH expression in the extracts of follicle cells treated with anti-FOXL2 and/or anti-ESR2 siRNA pools for 48 hr. A black arrow designates SOX9. (B–C) Histogram representation of Cyp19a1 expression determined by our microarray analyses. Error bar represents the standard deviation based on two biological replicates. (D) Western blot analysis of SOX9 and GAPDH expression in extracts of hormone-deprived follicular cells treated with anti-FOXL2, anti-ESR1 or anti-ESR2 siRNA pools for 24hr and/or 17β-estradiol for 10 hr. (E) Schematic representation of our findings on FOXL2 regulation of estradiol signaling. Our findings suggest that FOXL2 may regulate estradiol signaling through (i) regulation of the production of E2 and (ii) regulation of estrogen receptivity by modulating the expression of Esr2. FOXL2 cooperates with Activin/SMAD3 and possibly ESR2 itself in the latter process. Sox9 repression seems to rely on multiple pathways in addition to the one described here, as FOXL2 and ESR1 have been described to co-bind a SOX9 regulatory element in the ovary.