Effects of RAC1 on Proliferation of Hen Ovarian Prehierarchical Follicle Granulosa Cells.

RAC1 belongs to the small G protein Rho subfamily and is implicated in regulating gene expression, cell proliferation and differentiation in mammals and humans; nevertheless, the function of RAC1 in growth and development of hen ovarian follicles is still unclear. This study sought to understand the biological effects of RAC1 on granulosa cell (GC) proliferation and differentiation of hen ovarian prehierarchical follicles. Firstly, our results showed expression levels of mRNA in the follicles with diameters of 7.0-8.0 mm, 6.0-6.9 mm and 1.0-3.9 mm were greater than other follicles ( < 0.05). The RAC1 protein was mainly expressed in oocyte and its around GCs and stromal tissues of the prehierarchical follicles by immunohistochemistry. Further investigation revealed the gene remarkably enhanced the mRNA and protein expression levels of FSHR (a marker of follicle selection), CCND2 (a marker of cell-cycle progression and GC differentiation), PCNA (a marker of GC proliferation), StAR and CYP11A1 (markers of GC differentiation and steroidogenesis) ( < 0.05). Furthermore, our data demonstrated siRNA interference of RAC1 significantly reduced GC proliferation ( < 0.05), while gene overexpression enhanced GC proliferation in vitro ( < 0.05). Collectively, this study provided new evidence that the biological effects of RAC1 on GC proliferation, differentiation and steroidogenesis of chicken ovary follicles.