TPX2 deficiency leads to spindle abnormity and meiotic impairment in porcine oocytes

Abstract

The targeting protein for Xklp2 (TPX2) is a spindle assembly factor, that can stimulate microtubule formation and promote spindle completion during mitosis. However, the role of TPX2 in mammalian oocyte meiotic maturation is still not fully understood. This study was conducted to address the dynamic distribution and potential roles of TPX2 in microtubule nucleation during meiotic maturation in porcine oocytes by microinjecting specific siRNAs. Western blotting results revealed that the expression of TPX2 displayed a lower level from 0 to 22 h of culture, while its expression exhibited a higher level after 28 h of culture. Immunofluorescence staining demonstrated that TPX2 was distributed along the microtubules and enriched in the poles after meiotic spindle formation at the 28 and 44 h of culture. From immunoprecipitation, TPX2 can interact with the microtubule-associated proteins aurora kinase A (AURKA) and transforming acidic coiled-coil 3 (TACC3). Meanwhile, the dynamic changes in the expression and localization of AURKA and TACC3 were highly consistent with TPX2 during meiotic maturation. After knocking down TPX2 by siRNA injection, the proportion of oocytes with aberrant spindles and scattered cytoplasmic actin filaments was significantly increased. In addition, TPX2 depletion markedly downregulated the expression of AURKA and TACC3. Thus, these results suggested that TPX2 is essential for meiotic spindle formation in the porcine oocyte, and that this regulation is related to its effect on AURKA and TACC3 expression.