Arp2/3 Complex Inhibition Prevents Meiotic Maturation in Porcine Oocytes

Fei Wang,Shao-Chen Sun,Nam-Hyung Kim,Ga-Young An,Yu Zhang,Hong-Lin Liu,Xiang-Shun Cui,Hongmei Wang

doi:10.1371/journal.pone.0087700

Fei Wang, Shao-Chen Sun + Show 6 more

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https://doi.org/10.1371/journal.pone.0087700

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Abstract

The Arp2/3 complex regulates actin nucleation, which is critical for a wide range of cellular processes, such as cell polarity, cell locomotion, and endocytosis. In the present study, we investigated the possible roles of the Arp2/3 complex in porcine oocytes during meiotic maturation. Immunofluorescent staining showed the Arp2/3 complex to localize mainly to the cortex of porcine oocytes, colocalizing with actin. Treatment with an Arp2/3 complex specific inhibitor, CK666, resulted in a decrease in Arp2/3 complex localization at the oocyte cortex. The maturation rate of porcine oocytes decreased significantly after CK666 treatment, concomitant with the failure of cumulus cell expansion and oocyte polar body extrusion. The fluorescence intensity of F-actin decreased in the cytoplasm, and CK666 also disrupted actin cap formation. In summary, our results illustrate that the Arp2/3 complex is required for the meiotic maturation of porcine oocytes and that actin nucleation is critical for meiotic maturation.

Highlights

IntroductionDuring the pre-ovulatory phase, cumulus cells undergo a series of transformations defined as cumulus expansion, which is essential for fertilization [1]
In mammals, oocytes undergo maturation before fertilization
We examined the subcellular localization of the Arp2/3 complex

Summary

Introduction

During the pre-ovulatory phase, cumulus cells undergo a series of transformations defined as cumulus expansion, which is essential for fertilization [1]. Cumulus expansion plays a key role in disseminating local and endocrine signals to oocytes [2]. Fully-grown oocytes are arrested at the germinal vesicle (GV) stage in mature ovarian follicles, and they resume meiosis only after being released from the follicle. The oocytes enter metaphase I (MI), followed by peripheral spindle migration and first polar body extrusion. The oocytes enter metaphase II (MII) and arrest at this stage until fertilization. During oocyte maturation in mice, the spindle moves from a central position to the cortex, resulting in the small polar body extrusion [5,6,7]

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