Polo-Like Kinase-1 Is a Pivotal Regulator of Microtubule Assembly During Mouse Oocyte Meiotic Maturation, Fertilization, and Early Embryonic Mitosis1

Abstract

Polo-like kinases (Plks) are a family of serine/threonine protein kinases that have been activated through phosphorylation. The activity of these kinases has been shown to be required for regulating multiple stages of mitotic progression in somatic cells. In this experiment, the changes in Plk1 expression were detected in mouse oocytes through Western blotting. The subcellular localization of Plk1 during oocyte meiotic maturation, fertilization, and early cleavage as well as after antibody microinjection or microtubule assembly disturbance was studied by confocal microscopy. The quantity of Plk1 protein remained stable during meiotic maturation and decreased gradually after fertilization. Plk1 was localized to the spindle poles of both meiotic and mitotic spindles at the early M phase and then translocated to the middle region. At anaphase and telophase, Plk1 was concentrated at the midbody of cytoplasmic cleavages. Plk1 was concentrated between the male and female pronuclei after fertilization. Plk1 disappeared at the spindle region when microtubule formation was inhibited by colchicine or staurosporine, while it was concentrated as several dots in the cytoplasm after taxol treatment. Plk1 antibody injection decreased the germinal vesicle breakdown rate and distorted MI spindle organization. Our results indicate that Plk1 is a pivotal regulator of microtubule organization during mouse oocyte meiosis, fertilization, and cleavage and that its functions may be regulated by other kinases, such as staurosporine-sensitive kinases.

Bub1 Prevents Chromosome Misalignment and Precocious Anaphase during Mouse Oocyte Meiosis

“…The mice with color gene type of aabbcc were from an inbred strain of Kunming white mice, a native breed widely used in biological research in China. 35 Ovaries were removed from 4-6 week-old female mice at 46-48 hours after PMSG injection. Prophase-stage oocytes displaying a germinal vesicle (GV) without cumulus cell masses were released from ovarian follicles and collected in M2 medium supplemented with 0.2 µM (IBMX) which prevented germinal vesicle breakdown (GVBD).…”

Septin2 is modified by SUMOylation and required for chromosome congression in mouse oocytes

“…After taxol treatment, septin2 disappeared from spindle fibers and translocated to the region around chromosomes. Importantly, localization of septin2 differs from other proteins involved in spindle formation that we previously studied (e.g., MDK, 43 BARC1, 44 and PLK1, 45 ), which are present at the center of microtubule organizing centers (MTOCs) after taxol treatment, participating in microtubule nucleation or organization. Moreover, it is reported that septins regulate microtubule dynamics through MAP4.…”

Synaptotagmin1 is required for spindle stability and metaphase-to-anaphase transition in mouse oocytes

“…After Syt1-MO knockdown, γ-tubulin failed to congress at the spindle poles but irregularly dispersed around the deformed spindles and redistributed into the oocyte cytoplasm. Therefore, it is clear that Syt1 distribution changes are similar to those of many MTOC-associated proteins, such as NEDD1, 32 Polo-like kinase1(Plk1) 33,34 and Astrin, 18 indicating a high level of correlation between Syt1 and the MTOC.…”