Effect of melatonin on ATG2B-mediated autophagy regulation in sheep granulosa cells with different Fec B genotypes

Melatonin (MLT) protects cells by reducing reactive oxygen species (ROS) levels, which are key for inducing cellular autophagy. The aim of this study was to investigate the molecular mechanisms underlying MLT regulation of autophagy in granulosa cells (GCs) with BMPR-1B homozygous (Fec BB) and wild type (Fec ++) mutations. GCs collected from small-tailed Han sheep with different Fec genotypes were typed using a TaqMan probe assay, and autophagy levels were found to be significantly higher in GCs with Fec BB than the levels in those with Fec ++. Autophagy-related 2 homolog B (ATG2B) was associated with cell autophagy and was highly expressed in GCs with the Fec BB genotype in small-tailed Han sheep. Overexpression of ATG2B in the GCs of sheep with both Fec genotypes promoted GC autophagy, and the contrary was observed after the inhibition of ATG2B expression. Subsequently, treatment of GCs with different genotypes of Fec and MLT revealed a significant decrease in cellular autophagy and an increase in ATG2B expression. Addition of MLT to GCs with inhibited ATG2B expression revealed that MLT could protect GCs by decreasing ROS levels, especially in GCs with Fec ++ genotype. In conclusion, this study determined that autophagy levels were significantly higher in sheep GCs with Fec BB genotype than the levels in those with Fec ++ genotype, which may have contributed to the difference in lambing numbers between the two Fec genotypes. Autophagy was regulated by ATG2B and was able to protect GCs by reducing the high levels of ROS produced following inhibition of ATG2B through the addition of MLT in vitro.