Several fibroblast growth factors (FGFs), including FGF1, FGF4 and FGF10, alter ovarian granulosa cell function. These ligands exhibit different patterns of receptor activation, and their mechanisms of action on granulosa cells remain unknown. The objective of this study was to identify the major pathways and target genes activated by FGF1, FGF4 and FGF10 in primary oestrogenic granulosa cells cultured under serum-free conditions. FGF1 and FGF4 increased levels of mRNA encoding Sprouty family members, SPRY2 and SPRY4, and the orphan nuclear receptors NR4A1 and NR4A3. Both FGF1 and FGF4 decreased levels of mRNA encoding SPRY3 and the pro-apoptotic factor BAX. FGF1 but not FGF4 stimulated expression of the cell cycle regulator, GADD45B. In contrast, FGF10 altered the expression of none of these genes. Western blot demonstrated that FGF4 activated ERK1/2 and Akt signalling rapidly and transiently, whereas FGF10 elicited a modest and delayed activation of ERK1/2. These data show that FGF1 and FGF4 activate typical FGF signalling pathways in granulosa cells, whereas FGF10 activates atypical pathways.
Zhongliang Jiang and Christopher A Price
Lizhu Ma, Yuxin Zheng, Xiaorong Tang, Huimin Gao, Ning Liu, Yan Gao, Lizhuang Hao, Shujie Liu and Zhongliang Jiang
It is well documented that granulosa cell apoptosis is the main reason for follicular atresia and death; however, increasing evidence suggests that autophagy plays an important role in the fate of granulosa cells. miR-21-3p regulates many fundamental biological processes and is pivotal in the autophagy of tumor cells; nevertheless, the autophagy in cattle ovary and how miR-21-3p regulates the follicular cells is unknown. In this study, we aimed to elucidate the autophagy and the role of miR-21-3p in cattle ovary using bovine primary ovarian granulosa cells (BGCs). The results showed the autophagy for the first time in BGCs in large follicle according to autophagic gene transcript of LC3, BECN-1, ATG3, protein expression of LC3, P62 and LC3 puncta, a standard marker for autophagosomes. miR-21-3p was identified as a novel miRNA that repressed BGCs autophagy according to the results from plasmids transfection of miR-21-3p mimics and inhibitor. Meanwhile, VEGFA was confirmed to be a validated target of miR-21-3p in BGCs using luciferase reporter assays and the results of VEGFA expression decreased with transfection of miR-21-3p mimics, while it increased with transfection of miR-21-3p inhibitor. In addition, small interference-mediated knockdown of VEGFA significantly inhibits BGCs autophagy signaling; however, overexpression of VEGFA in BGCs promoted autophagy in the presence of miR-21-3p. Finally, the results of AKT and its phosphorylation suggested that miR-21-3p suppressed VEGFA expression through downregulating AKT phosphorylation signaling. In summary, this study demonstrates that miR-21-3p inhibits BGCs autophagy by targeting VEGFA and attenuating PI3K/AKT signaling.