Age‐related SUMOylation of PLK1 is essential to meiosis progression in mouse oocytes

Abstract Polo like kinase 1 (PLK1) is a protein kinase involved in regulating the spindle assembly and cell cycle control in mammalian oocytes. SUMOylation, one way of post‐translational modification, regulates oocyte meiosis by controlling several substrates. However, the relation between PLK1 and SUMOylation in oocytes is still unknown. In this study, we investigated that whether PLK1 was modified by SUMOylation in oocytes and its potential relationship with age‐related meiotic abnormalities. We showed that PLK1 had colocalization and protein interaction with Small Ubiquitin‐Like Modifier (SUMO)‐1 and SUMO‐2/3 in mouse oocytes, indicating that PLK1 could be modified by SUMO‐1 and SUMO‐2/3. Overexpression of PLK1 SUMOylation site mutants PLK1 K178R and PLK1 K191R caused the increase of the abnormal spindle rate of oocytes and the decline of the first polar body extrusion rate with the abnormal localization of PLK1, suggesting that the SUMOylation modification of PLK1 is essential for normal meiosis in oocytes. Compared with young mice, the expression of PLK1 protein increased and the expression of SUMO‐1 and SUMO‐2/3 protein decreased in the oocytes of aged mice, indicating that the SUMOylation of PLK1 might be related to the mouse aging. Therefore, our data suggested that PLK1 could be SUMOylated by SUMO‐1 and SUMO‐2/3 in mouse oocytes and SUMOylation of PLK1 regulated the meiosis progression of oocytes which was related with aging.