Rab6a is a novel regulator of meiotic apparatus and maturational progression in mouse oocytes

Xiaojing Hou,Longsen Han,Ling Li,Juan Ge,Rujun Ma,Qiang Wang,Jiaqi Zhang

doi:10.1038/srep22209

Abstract

Rab family GTPases have been well known to regulate intracellular vesicle transport, however their function in mammalian oocytes has not been addressed. In this study, we report that when Rab6a is specifically knockdown, mouse oocytes are unable to progress normally through meiosis, arresting at metaphase I. Moreover, in these oocytes, the defects of chromosome alignment and spindle organization are readily observed during maturation, and resultantly increasing the aneuploidy incidence. We further reveal that kinetochore-microtubule attachments are severely compromised in Rab6a-depleted oocytes, which may in part mediate the meiotic phenotypes described above. In addition, when Rab6a function is altered, BubR1 levels on the kinetochores are markedly increased in metaphase oocytes, indicating the activation of spindle assembly checkpoint. In sum, we identify Rab6a as an important player in modulating oocyte meiosis, specifically the chromosome/spindle organization and metaphase-anaphase transition.

Highlights

By employing siRNA knockdown analysis, we discovered the involvement of Rab6a in meiosis of mouse oocyte, in controlling meiotic progression and meiotic structures, and report our findings below
By confocal microscopy we found that the predominant pattern of K-MT in normal oocytes is amphitelic attachment, in which the kinetochore of one chromosome is connected to the spindle pole and the kinetochore of the other chromosome is connected to the opposite spindle pole (Fig. 4A, chromosomes 1 and 2)
We discover a novel role for Rab6a during meiosis: the involvement in chromosome/spindle organization and metaphase/anaphase transition in mammalian oocytes

Summary

Introduction

By employing siRNA knockdown analysis, we discovered the involvement of Rab6a in meiosis of mouse oocyte, in controlling meiotic progression and meiotic structures, and report our findings below. We found that more than 35% of oocytes injected with Rab6a-siRNA were blocked in meiosis I, which was dramatically increased compared to controls. Rab6a-siRNA and control oocytes were immunolabeled with anti-tubulin antibody to visualize the spindle and co-stained with propidium iodide (PI) for chromosomes.

Results

Conclusion