Spermidine enhances steroidogenesis by elevating eIF5Ahyp level in hierarchical follicular granulosa cells of the goose

Imbalanced steroid hormone levels in female poultry can impair follicular development, thereby adversely affecting reproductive performance. Spermidine is reported to be involved in regulation of female reproduction and can provide aminobutyl as the only substrate required for the activation of eukaryotic translation initiation factor 5A (eIF5A^hyp). In this study, goose granulosa cells were treated with spermidine and interference/overexpression eIF5A with the aim of investigating the effects and mechanisms of spermidine on steroidogenesis. Estradiol (E2) and progesterone (P4) levels increased with spermidine concentration, peaking at 160 μmol/L (P < 0.01). Compared with control, eIF5A overexpression significantly increased E2 levels (P < 0.05), but had no effect on P4. Moreover, compared with the eIF5A overexpression, 160 μmol/L spermidine combined with eIF5A overexpression treatment further increased E2 level (P < 0.05). Mechanistically, we found that both spermidine and eIF5A overexpression treatments significantly increased eIF5A^hyp as well as StAR protein expression (P < 0.05). These results suggest that spermidine can enhance steroidogenic capacity of goose granulosa cells, and this effect is mainly realized by mediating eIF5A^hyp. Notably, protein functional annotation revealed that differentially expressed proteins were significantly enriched in steroid biosynthesis and metabolism pathways. HMOX1, COQ9, and SERPINE2 were preliminarily identified as key proteins for spermidine-eIF5A^hyp axis-regulated steroidogenesis in goose granulosa cells.