CircRALGPS2 modulates chicken follicle development through promotion of granulosa cell apoptosis and autophagy via the miR-200a-3p/TGFβ2/SMAD pathway

The reproductive performance of hens is predominantly determined by the growth and development of their follicles. Follicular development in chickens represents a highly complex and multi-regulatory biological process, wherein granulosa cells (GCs) play a crucial role in follicle selection. Recent studies have emphasized the critical role of circular RNAs (circRNAs) in regulating follicular growth and development in animals. In our previous study, employing circRNA RNA-seq, we identified differential expression of circRALGPS2 between healthy and atretic follicles in chickens. In the current investigation, we observed a marked increase in autophagy and apoptosis levels within atretic follicles. Notably, circRALGPS2 was shown to promote follicular atresia by enhancing autophagy and apoptosis in GCs. Moreover, we demonstrated that circRALGPS2 functions as a molecular sponge for miR-200a-3p, revealing that miR-200a-3p and circRALGPS2 exert antagonistic effects on GC autophagy and apoptosis. Mechanistically, circRALGPS2 targets miR-200a-3p, which subsequently modulates the expression of transforming growth factor β2 (TGFβ2), thereby activating the canonical TGFβ/SMAD signaling pathway. Collectively, our findings demonstrate that circRALGPS2 promotes apoptosis and autophagy in chicken GCs through activation of the TGFβ2/SMAD pathway via miR-200a-3p sequestration. These results provide valuable insights for advancing chicken genetic breeding technologies through marker-assisted selection.