earticle

영어

LINE-1 is an autonomous non-LTR retrotransposon in mammalian genomes and encodes ORF1P and ORF2P. ORF2P has been clearly identified as the enzyme supplier needed in LINE-1 retrotransposition. However, the role of ORF1P is not well explored and requires further elucidation. In this study, we depleted ORF1P to investigate its role in mouse oocyte meiotic maturation. The results showed that depletion of ORF1P caused oocyte arrest at the germinal vesicle (GV) stage as well as down-regulation of Cdc2 and Cyclin B1, components of the maturation promoting factor (MPF). Further analysis demonstrated a decreased expression of the P21 upstream factors Smad4 and Dcp1a after ORF1P depletion. However, SMAD4 and DCP1A became accumulated in the nucleus. This translocation would up-regulate the expression of P21. Furthermore, ORF1P knockdown also increased the expression of microRNA-494, which could decrease the expression of Cyclin B1 and Cdc2. Propidium Iodide (PI) staining after ORF1P depletion revealed abnormal chromatin configuration in the GV of mouse oocytes. Taken together, these results indicate that ORF1P is involved in the TGF-β pathway to modulate the GV breakdown (GVBD) during mouse oocyte meiotic maturation.