// Mianqun Zhang 1 , Xiaoxin Dai 1 , Yalu Sun 1 , Yajuan Lu 1 , Changyin Zhou 1 , Yilong Miao 1 , Ying Wang 2 , Bo Xiong 1 1 College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China 2 Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing 100191, China Correspondence to: Bo Xiong, email: xiongbo@njau.edu.cn Keywords: Stag3, spindle assembly, chromosome alignment, microtubule stability, aneuploid egg Received: October 20, 2016 Accepted: November 12, 2016 Published: November 29, 2016 ABSTRACT Stag3, a meiosis-specific subunit of cohesin complex, has been demonstrated to function in both male and female reproductive systems in mammals. However, its roles during oocyte meiotic maturation have not been fully defined. In the present study, we report that Stag3 uniquely accumulates on the spindle apparatus and colocalizes with microtubule fibers during mouse oocyte meiotic maturation. Depletion of Stag3 by gene-targeting morpholino disrupts normal spindle assembly and chromosome alignment in oocytes. We also find that depletion of Stag3 reduces the acetylated level of tubulin and microtubule resistance to microtubule depolymerizing drug, suggesting that Stag3 is required for microtubule stability. Consistent with these observations, kinetochore-microtubule attachment, an important mechanism controlling chromosome alignment, is severely impaired in Stag3-depleted oocytes, resultantly causing the significantly increased incidence of aneuploid eggs. Collectively, our data reveal that Stag3 is a novel regulator of microtubule dynamics to ensure euploidy during moue oocyte meiotic maturation.
