Aurora B prevents aneuploidy via MAD2 during the first mitotic cleavage in oxidatively damaged embryos.

Jiena Li,Zhiling Li,En Lin,Yue Huang,Siyao Ha,Wanfen Xiao

doi:10.1111/cpr.12657

Abstract

ObjectivesA high rate of chromosome aneuploidy is exhibited in in vitro fertilization (IVF)‐derived embryos. Our previous experiments suggested that reactive oxygen species (ROS) can activate Mad2, a key protein in the spindle assembly checkpoint (SAC), and delay the first mitotic, providing time to prevent the formation of embryonic aneuploidy. We aimed to determine whether mitotic kinase Aurora B was involved in the SAC function to prevent aneuploidy in IVF‐derived embryos.Materials and MethodsWe analysed aneuploidy formation and repair during embryo pre‐implantation via 4ʹ,6‐diamidino‐2‐phenylindole (DAPI) staining and karyotype analysis. We assessed Aurora B activation by immunofluorescence and investigated the effect of Aurora B inhibition on embryo injury‐related variables, such as embryonic development, ROS levels, mitochondrial membrane potential and γH2AX‐positive expression.ResultsWe observed the expression and phosphorylation of Thr232 in Aurora B in oxidative stress‐induced zygotes. Moreover, inhibition of Aurora B caused chromosome mis‐segregation, abnormal spindle structures, abnormal chromosome number and reduced expression of Mad2 in IVF embryos. Our results suggest that Aurora B causes mitotic arrest and participates in SAC via Mad2 and H3S10P, which is required for self‐correction of aneuploidies.ConclusionsWe demonstrate here that oxidative stress–induced DNA damage triggers Aurora B‐mediated activation of SAC, which prevents aneuploidy at the first mitotic cleavage in early mouse IVF embryos.

Highlights

The spindle assembly checkpoint (SAC) represents a surveillance mechanism that ensures the accurate separation of sister chroma‐ tids during early mitosis.[1,2] Aurora kinase B (Aurora B) is a member of the chromosomal passenger complex and is required for proper regulation of chromosome alignment, cytokinesis and kinetochore‐ microtubule interactions
We found that 0.03 mmol/L hydrogen perox‐ ide(H2O2) administered at 7 hours post‐insemination (G1 phase) was the minimum concentration necessary to establish a model system that simulates the clinically inevitable oxidative stress expe‐ rienced by in vitro fertilization (IVF) embryos[20] and resulted in an increase in sex chro‐ mosome aneuploidy in mouse IVF embryos.[21]
We previously used isobaric tags for relative and absolute quantitation experi‐ ments to reveal that oxidative stress inhibited the expression of Raf kinase inhibitory protein (RKIP), which caused a defect in the mitotic SAC by reducing the centromere localization of Aurora B in some H2O2‐treated zygotes; this may be one of the important reasons for chromosomal aneuploidies in IVF‐derived embryos.[22,23]

Summary

| INTRODUCTION

The spindle assembly checkpoint (SAC) represents a surveillance mechanism that ensures the accurate separation of sister chroma‐ tids during early mitosis.[1,2] Aurora kinase B (Aurora B) is a member of the chromosomal passenger complex and is required for proper regulation of chromosome alignment, cytokinesis and kinetochore‐ microtubule interactions. We found that 0.03 mmol/L hydrogen perox‐ ide(H2O2) administered at 7 hours post‐insemination (hpi) (G1 phase) was the minimum concentration necessary to establish a model system that simulates the clinically inevitable oxidative stress expe‐ rienced by IVF embryos[20] and resulted in an increase in sex chro‐ mosome aneuploidy in mouse IVF embryos.[21]. We previously used isobaric tags for relative and absolute quantitation (iTRAQ) experi‐ ments to reveal that oxidative stress inhibited the expression of Raf kinase inhibitory protein (RKIP), which caused a defect in the mitotic SAC by reducing the centromere localization of Aurora B in some H2O2‐treated zygotes; this may be one of the important reasons for chromosomal aneuploidies in IVF‐derived embryos.[22,23]. We aimed to determine whether mitotic kinase Aurora B was involved in SAC function to prevent aneuploidy in IVF‐derived embryos. We evaluated the mechanism underlying the role of Aurora B during the first mitotic cleavage period

| MATERIALS AND METHODS

| DISCUSSION

Findings

CONFLICT OF INTERESTS