Dynein promotes porcine oocyte meiotic progression by maintaining cytoskeletal structures and cortical granule arrangement

Abstract

Cytoplasmic dynein is a family of cytoskeletal motor proteins that move towards the minus-end of the microtubules to perform functions in a variety of mitotic processes such as cargo transport, organelle positioning, chromosome movement and centrosome assembly. However, its specific roles during mammalian oocyte meiosis have not been fully defined. Herein, we investigated the critical events during porcine oocyte meiotic maturation after inhibition of dynein by Ciliobrevin D treatment. We found that oocyte meiotic progression was arrested when inhibited of dynein by showing the poor expansion of cumulus cells and decreased rate of polar body extrusion. Meanwhile, the spindle assembly and chromosome alignment were disrupted, accompanied by the reduced level of acetylated α-tubulin, indicative of weakened microtubule stability. Defective actin polymerization on the plasma membrane was also observed in dynein-inhibited oocytes. In addition, inhibition of dynein caused the abnormal distribution of cortical granules and precocious exocytosis of ovastacin, a cortical granule component, which predicts that ZP2, the sperm binding site in the zona pellucida, might be prematurely cleaved in the unfertilized dynein-inhibited oocytes, potentially leading to the fertilization failure. Collectively, our findings reveal that dynein plays a part in porcine oocyte meiotic progression by regulating the cytoskeleton dynamics including microtubule stability, spindle assembly, chromosome alignment and actin polymerization. We also find that dynein mediates the normal cortical granule distribution and exocytosis timing of ovastacin in unfertilized eggs which are the essential for the successful fertilization.

Sperm-borne small RNAs regulate α-tubulin acetylation and epigenetic modification of early bovine somatic cell nuclear transfer embryos

“…Ac α-Tubulin K40 is one of the most important post-translational modifications of microtubules (Schatten, Simerly et al 1988, Ly, Elkhatib et al 2016. Studies have shown that acetylation affects the stability of microtubules, and an increase in acetylated α-tubulin levels can enhance the stability of mitotic microtubules (Miao, Zhou et al 2017, Steinhauser, Kloble et al 2017. We hypothesized that the sperm-borne small RNA may regulate cytoskeleton function through the Ac α-tubulin K40, thus affecting microtubule assembly, cytokinesis, and chromosome segregation, and further affecting the embryonic first cleavage.…”

Cortical Granule Distribution and Expression Pattern of Genes Regulating Cellular Component Size, Morphogenesis, and Potential to Differentiation are Related to Oocyte Developmental Competence and Maturational Capacity In Vivo and In Vitro

“…Therefore, it is a further proof of the key importance of microfilaments in oocytes maturation and CGs dynamics. Miao et al described the important role of dynein (cytoskeletal motor proteins) in the meiotic progression of porcine oocytes through the regulation of cytoskeletal dynamics, including the stability of microtubules [46], reflecting the distribution of CGs and ovastacin exocytosis.…”

SIRT6 Maintains Redox Homeostasis to Promote Porcine Oocyte Maturation

“…In the present study, we used porcine oocytes as a model to explore the function of SIRT6 on meiotic maturation, as the developmental and physiological indexes of porcine oocytes including the diameter of oocytes and maturation time are more similar to humans in comparison with mice ( Schatten and Sun, 2009 ; Miao et al, 2017 ). We found that inhibition of SIRT6 activity impaired both nuclear and cytoplasmic maturation of oocytes, including the abnormal cytoskeleton assembly and cortical granule (CG) dynamics.…”