Eg5 orchestrates porcine oocyte maturational progression by maintaining meiotic organelle arrangement

Yan Xie,Bo Xiong,Minghui Cheng,Ying Chen,Yurong Qiu,Chen Pan,Shan Lu,Dongyu Yang,Qilong Yuan

doi:10.1186/s13008-018-0037-1

Abstract

BackgroundKinesin superfamily proteins are microtubule-based molecular motors essential for the intracellular transport of various cargos, including organelles, proteins, and RNAs. However, their exact roles during mammalian oocyte meiosis have not been fully clarified.ResultsHerein, we investigated the critical events during porcine oocyte meiotic maturation with the treatment of Eg5-specific inhibitor monastrol. We found that Eg5 inhibition resulted in oocyte meiotic failure by displaying the poor expansion of cumulus cells and reduced rate of polar body extrusion. In the meantime, the spindle assembly and chromosome alignment were compromised, accompanied by the decreased level of acetylated α-tubulin, indicative of less stable microtubules. Impaired actin dynamics and mitochondria integrity were also observed in Eg5-inhibited oocytes. Additionally, inhibition of Eg5 caused the abnormal distribution of cortical granules and ovastacin, a cortical granule component, potentially leading to the fertilization failure.ConclusionsOur findings reveal that Eg5 possesses an important function in porcine oocyte meiotic progression by regulating the organelle dynamics and arrangement.

Highlights

Kinesin superfamily proteins are microtubule-based molecular motors essential for the intracellular transport of various cargos, including organelles, proteins, and RNAs
Our findings show that Eg5 participates in porcine oocyte meiotic progression by regulating the cytoskeleton dynamics including microtubule stability, spindle assembly, chromosome alignment and actin polymerization
The quantification analysis showed that treatment with different concentrations of monastrol (10, 50 and 100 μM) resulted in the decreased rates of polar body extrusion (PBE) in varying degree in oocytes cultured for 44 h in vitro and supplementation with 100 μM inhibitor had a significant reduction compared to controls

Summary

Introduction

Kinesin superfamily proteins are microtubule-based molecular motors essential for the intracellular transport of various cargos, including organelles, proteins, and RNAs. To generate fertilizable female gametes, mammalian oocytes must undergo well-regulated meiotic maturation of both nucleus and cytoplasm, including resumption of meiosis, proper organelle assembly and arrangement, as well as first polar body extrusion [1]. Any errors during this process will lead to the failed meiotic progression. A large number of these proteins, or their orthologues, are involved in various vesicle transport and intracellular trafficking events and have been shown to participate in the fundamental biological processes in both the mitosis and the meiosis such as transport of vesicles and macromolecules, microtubule dynamics, spindle formation, mitochondria translocation, chromosome separation, cytokinesis and cell cycle progression [9].

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