CREBRF regulates apoptosis and estradiol via ISG15/ISGylation in pig granulosa cells

Granulosa cells are pivotal in the reproductive processes of female animals; their proliferation, apoptosis, and hormonal secretion are crucial for follicular development and ovulation. Although the role and mechanisms of CREBRF in the reproductive system have garnered attention, its specific functions and underlying mechanisms in ovarian granulosa cells remain unexplored-this study aims to address these gaps. Using flow cytometry, transcriptome sequencing and other technologies, our research revealed elevated CREBRF expression in pig breeds correlated with diminished estrodiol (E2) levels. Further experimental results proved CREBRF could suppress apoptosis through the Bax/caspase3/caspase9 pathway and modulation of ISG15/ISGylation in porcine granulosa cells. When CREBRF was interfered with siRNA, the apoptosis of granulosa cells was increased. At the same time, the expression of apoptosis-related Bax, caspase3, caspase9 was significantly up-regulated, and the expression of anti-apoptotic factor BCL2 was significantly down-regulated. During this process, the expression of many genes changed in granulosa cells. Several genes (CMPK2, MX1, MX2, ZBP1, PML, CHAC1, and BAX) which were promoted apoptosis, were upregulated after CREBRF knockdown with siRNA. ISG15-protein conjugation genes (HERC5, UBA7, UBE2L6, ISG15) were also were upregulated. On the contrary, the expression of anti-apoptotic (RFK, SNAP23) genes decreased. In conclusion, CREBRF could regulate apoptosis of pig granulosa cells through BAX/caspase3/caspase9. Additionally, the study highlights significant alterations in the expression of ISG-related genes and other known apoptosis-related genes during this process. This discovery can novel insights for further elucidating the molecular mechanism of granulosa cells within ovarian granulosa cells and potentially identifies CREBRF as a molecular target for improvement of fertility.