Differential actions of fibroblast growth factors on intracellular pathways and target gene expression in bovine ovarian granulosa cells

Abstract

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,SPRY2andSPRY4, and the orphan nuclear receptorsNR4A1andNR4A3. Both FGF1 and FGF4 decreased levels of mRNA encodingSPRY3and the pro-apoptotic factorBAX. 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.