Exploration of the effects of goose TCs on GCs at different follicular stages using a co-culture model

Granulosa cells (GCs) play a critical role in follicular development, which cannot be separated from the assistance of theca cells (TCs). In the present study, we used a transwell system to develop three stages of goose GCs in vitro mono-culture and co-culture models, and we analyzed the morphology, activity, intracellular lipid content and the expression of core genes involved in de novo lipogenesis (DNL), steroidogenesis, proliferation and apoptosis of the GCs. In the co-culture group, the activity of all three stages of GCs showed significant (P<0.01) changes, and they had a strong (P<0.01) correlation with culture time; further, the intracellular lipid deposition of hierarchical GCs was significantly different (P<0.01) between the two methods. Moreover, after co-culture, in pre-hierarchical GCs, the expression of SREBP, CYP11 and 3βHSD was promoted (P<0.01). In hierarchical GCs, the expression of ACC, SREBP, STAR, CYP11, 3βHSD and CCND1 was promoted at 48 h, but they were inhibited (P<0.05) at 96 h. In F1 GCs, the expression of ACC, FAS, SREBP, CYP11, BCL2 and CAS3 was inhibited (P<0.01). The results indicate that goose TCs had complex and time-dependent effects on the biological function of GCs at each corresponding stage, and the effects were distinct in the different stages. In addition, DNL, steroidogenesis, proliferation and apoptosis in hierarchical and F1 GCs might have some synergistic relationships in the effects of TCs on GCs. Furthermore, we speculated that TCs might play an important role in the differentiation and maturation of GCs during follicular development.