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.
Highlights
Cells divide and reproduce in two ways: mitosis and meiosis
We show that Stag3 localizes on the spindle apparatus and is required for microtubule stability and spindle assembly
The result showed that fluorescent signals of Stag3 and α-tubulin were overlapped in the metaphase I oocytes (Figure 1B), Figure 1: Localization of Stag3 during mouse oocyte meiotic maturation
Summary
Chromosomes have to replicate and the resulting sister chromatids have to segregate in each cell cycle, which generates two genetically identical daughter cells [1, 2]. The major causes of these errors are mainly due to the deficient structure of spindles and segregation of chromosomes [9]. Correct spindle assembly depends on the speedy reorganization of dynamic microtubules which are composed of α- and β-tubulin dimers that make a highly dynamic state between rapid growth and shrinkage. Disruption of this dynamics would cause increased or decreased microtubule stability, which thereby results in defective spindle structures [10]. Numerous studies have been focused on the mechanisms regarding how cohesin and its regulators play essential roles in chromosome segregation, transcriptional regulation and DNA damage repair, the more biological processes involved remain to be explored
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