The expression patterns of FGF2 and FGFRs during COCs in vitro maturation Specific objectives were to: 1) illuminate the expression patterns of FGF2 and FGFRs in COCs, 2) determine the effects of FGF2/FGFR signaling on oocyte meiosis and cumulus expansion, and 3) explore the possible mechanisms by which FGF2/FGFR signaling regulates oocyte in vitro maturation. In the present study, mouse COCs, and isolated oocytes and cumulus cells, were employed to further explore the functions of FGF2/FGFR signaling on COCs during in vitro maturation (IVM). Furthermore, the role of paracrine trafficking of FGF2 between cumulus cells (CCs) and oocytes on oocyte meiosis has not been examined. However, the expression patterns of the ligand (FGF2) and receptors (FGFRs) in murine cumulus-oocyte complexes (COCs) have not been established. Collectively, these findings implicate FGF2 and FGFR in follicular development and oocyte maturation in mammals. For example, FGF2 promotes the proliferation of ovarian granulosa cells and germ cells through the activation of FGFR1 ( He et al. Previous studies demonstrate that FGF2 binds to and activates FGFR1 to carry out its diverse physiological functions in target tissues. FGFR1, FGFR2, and FGFR3 are expressed in mouse oocytes and embryos ( Lu et al. 2019), and in ovine oocytes and embryos ( Santos et al. 2012), in bovine cumulus cells ( Barros et al. FGF2 is expressed in caprine follicles ( Almeida et al. The FGFRs are tyrosine kinase receptors (TRKs) that are derived from four genes, namely Ffgr1, Fgfr2, Fgfr3, and Fgfr4 ( Price 2016). The biological functions of canonical FGFs are mediated by interactions with transmembrane receptors known as FGF receptors (FGFRs) ( Zhang & Ealy 2012 b). Collectively, these studies show that FGF2 can promote oocyte maturation however, the cell types and underlying mechanisms of FGF/FGFR regulation of oocyte meiosis remain unclear. Moreover, FGF2 could also improve early embryonic development ( Zhang & Ealy 2012 a, Abouzaripour et al. Abouzaripour et al (2018) indicated that the addition of FGF2 to the medium had beneficial effects on the IVM of mouse oocyte. The addition of FGF2 improved the efficiency of producing matured oocytes of pig ( Yuan et al. ( 2019) suggested that the addition of FGF2 to IVM medium increased the percentage of oocytes reaching GVBD. Additionally, Mondal et al (2015) reported that supplementation of maturation medium with FGF2 significantly increased the maturation rate of ovine COCs. FGF2 promotes follicular development in multiple species including the goat ( Almeida et al. These findings reveal a novel role for FGF2/FGFR signaling during in vitro maturation of COCs.įibroblast growth factor 2 (FGF2), also known as a basic fibroblast growth factor (bFGF), is a canonical member of FGF family ( Ornitz & Itoh 2015). Overall, this study suggests that FGF2 produced by cumulus cells, activates a FGF2/FGFR autocrine/paracrine loop within COCs to regulate cumulus expansion and oocyte meiosis. Furthermore, inhibition of FGFR in COCs interrupted the c-Mos/MAPK pathway and maturation-promoting factor (MPF), as indicated by downregulation of oocyte c-mos and Ccnb1 transcripts, respectively. Inhibition of FGF2/FGFR signaling also downregulated Ffgr1 expression, while supplemental FGF2 upregulated Fgfr1 expression. However, co-culture of DOs with COCs or supplementation with FGF2 promoted meiotic progression of DOs. Inhibition of FGFR had no effect on meiotic progression of denuded oocytes (DOs). Treatment with FGF2 increased Ptx3 and Has2 expression. Inhibition of FGFR with SU5402 reduced cumulus expansion and expressions of Ptx3, Has2 and Tnfaip6. In contrast, supplement of FGF2 promoted oocyte meiotic progression and upregulated Bmp15 and Gdf9 expression.
Treatment of COCs with the selective FGFR inhibitor SU5402 blocked oocyte meiotic progression and downregulated expression of Bmp15 and Gdf9. Ffgr1 was present in oocytes and cumulus cells, while Fgf2 was present in only cumulus cells. The transcripts for Fgf2 and Ffgr1 in COCs increased during IVM. Among four FGFRs, Ffgr1 was the most abundant in COCs. In this study, we investigated expression patterns and functions of FGF2/FGFR during in vitro maturation (IVM) of mouse cumulus-oocyte complexes (COCs). However, little is known regarding the role of FGF2/FGFR on oocyte meiosis. Fibroblast growth factor 2 (FGF2), a member of FGF family, binds with FGF receptors (FGFR) to initiate biological functions in various somatic cells.
0 kommentar(er)
