Ribonucleic Acid Export 1 Is a Kinetochore-Associated Protein That Participates in Chromosome Alignment in Mouse Oocytes.

Ribonucleic acid export 1 (Rae1) is an important nucleoporin that participates in mRNA export during the interphase of higher eukaryotes and regulates the mitotic cell cycle. In this study, small RNA interference technology was used to knockdown Rae1, and immunofluorescence, immunoblotting, and chromosome spreading were used to study the role of Rae1 in mouse oocyte meiotic maturation. We found that Rae1 is a crucial regulator of meiotic maturation of mouse oocytes. After the resumption of meiosis (GVBD), Rae1 was concentrated on the kinetochore structure. The knockdown of Rae1 by a specific siRNA inhibited GVBD progression at 2 h, finally leading to a decreased 14 h polar body extrusion (PBE) rate. However, a comparable 14 h PBE rate was found in the control, and the Rae1 knockdown groups that had already undergone GVBD. Furthermore, we found elevated PBE after 9.5 h in the Rae1 knockdown oocytes. Further analysis revealed that Rae1 depletion significantly decreased the protein level of securin. In addition, we detected weakened kinetochore-microtubule (K-MT) attachments, misaligned chromosomes, and an increased incidence of aneuploidy in the Rae1 knockdown oocytes. Collectively, we propose that Rae1 modulates securin protein levels, which contribute to chromosome alignment, K-MT attachments, and aneuploidy in meiosis.