Fig. 3

CDC42 in oocytes regulates the PI3K pathway to control follicle activation in neonatal ovaries. a Western blot showed that the activity of PI3K signaling was suppressed in ML141-treated ovaries. Levels of total FOXO3a, AKT, and β-actin were used as internal controls. The phosphorylation of FOXO3a and AKT was decreased in ML141-treated ovaries. b FOXO3a localizes to the nuclei (arrows) of dormant oocytes and to the cytoplasm (arrowheads) of activated oocytes when PI3K signaling is activated in 5 dpp ovaries. c Nuclear localization of FOXO3a (green fluorescence) was observed in oocytes of ML141-treated ovaries indicating suppressed PI3K signaling in oocytes of primordial follicles. Oocytes were stained with DDX4 (red). Nuclei were dyed with a Hoechst counter-stain (blue). d Overexpression of CDC42 led to premature follicle activation in ovaries. Cytoplasmic localization of FOXO3a (arrowheads, CL-FOXO3a) was observed in most of the oocytes. e, f The oocytes with CL-FOXO3a localization were quantified in ML141, Cdc42-OE and control ovaries. The proportion of CL-FOXO3a was significantly decreased (P < 0.005) in ML141-cultured ovaries but increased (P < 0.05) in Cdc42-OE-injected ovaries (Additional file 10: individual data values). The experiments were repeated at least three times, and representative images are shown. Scale bars, 40 μm