Expression of Oocyte Vitellogenesis Receptor Was Regulated by C/EBPα in Developing Follicle of Wanxi White Goose

SIMPLE SUMMARY: The key factor affecting the development and mature of follicle in poultry is the incorporation of yolk precursor. The aim of this study was to investigate the mechanism of incorporation of yolk precursor into follicle. The correlation was analyzed between reproductive hormones and oocyte vitellogenesis receptor (OVR) expression, and the transcriptional regulatory factors of OVR were predicted, overexpressed and screened by cloning the promoter region, determining the OVR expression and lipid transportation. The expression of OVR was related to the follicle level (primary follicle, developing follicle and mature follicle) (p < 0.001), but not the serum hormones concentration (p > 0.05). Simultaneously, the expression of OVR was distributed in the granular cell layer and decreased with the maturation of follicles. The mRNA expression level of OVR was significantly increased in goose granulosa cells with C/EBPα and MF3 stimulated. Remarkably, the combined overexpression of C/EBPα and OVR significantly stimulated the transportation of lipid from culture medium to cytoplasm. The C/EBPα is a key transcription factor promoting OVR expression in goose follicle granulosa cells. ABSTRACT: Yolk precursor was synthesized under regulation of hormone secretion, while the mechanism of its incorporation into follicle is still unknown. The reproductive hormones, oocyte vitellogenesis receptor (OVR) expression at pre-, early-, peak- and ceased-laying period, and localization of Wanxi White goose were determined in this study. The results showed that the concentration of LH was lowest in serum at peak laying period compared to the other periods (p < 0.01). Moreover, the concentration of E2 was highest (p < 0.01) in serum at early laying period than that of other periods. Moreover, the gene expression level of OVR was highest at ceased laying period compared to other periods (p = 0.014) and was higher in developing follicles than other follicles (p < 0.01). The OVR was distributed in the granular cell layer and decreased with the maturation of follicles. Five transcription factors were predicted in the promoter of OVR, then were screened and verified by overexpression in granulosa cells. C/EBPα and MF3 significantly stimulated the expression of OVR. The combined overexpression of C/EBPα and OVR significantly stimulated the transportation of lipid from culture medium to cytoplasm. In conclusion, C/EBPα is the key transcription factor promoting OVR expression in goose follicle granulosa cells.