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Updated: Jul 7, 2026
Meiotic Spindle Assessment in Mouse Oocytes by siRNA-mediated Silencing
Published on: October 11, 2015
MEK1/2 is a critical regulator of microtubule assembly and spindle organization during rat oocyte meiotic maturation
Shao-Chen Sun1, Bo Xiong, Sheng-Sheng Lu
1Animal Reproduction Institute, Guangxi Key Laboratory of Subtropical Bioresource Conservation and Utilization, Guangxi University, Nanning, China.
Abstract:
MEK (MAPK kinase) is an upstream protein kinase of MAPK in the MOS/MEK/MAPK/p90rsk signaling pathway. We previously reported the function and regulation of MAPK during rat oocyte maturation. In this study, we further investigated the localization and possible roles of MEK1/2. First, immunofluorescent staining revealed that p-MEK1/2 was restricted to the germinal vesicle (GV). After germinal vesicle breakdown (GVBD), p-MEK1/2 condensed in the vicinity of chromosomes and then translocated to the spindle poles at metaphase I, while spindle microtubules stained faintly. When the oocyte went through anaphase I and telophase I, p-MEK1/2 disappeared from spindle poles and became associated with the midbody. By metaphase II, p-MEK1/2 was again localized to the spindle poles. Second, p-MEK1/2 was localized to the centers of cytoplasmic microtubule asters induced by taxol. Third, p-MEK1/2 co-localized with gamma-tubulin in microtubule-organizing centers (MTOCs). Forth, treatment with U0126, a non-competitive MEK1/2 inhibitor, did not affect germinal vesicle breakdown, but caused chromosome mis-alignment in all MI oocytes examined and abnormal spindle organization as well as small cytoplasmic spindle-like structure formation in MII oocytes. Finally, U0126 reduced the number of cytoplasmic asters induced by taxol. Our data suggest that MEK1/2 has regulatory functions in microtubule assembly and spindle organization during rat oocyte meiotic maturation.
Insights
Mitogen-activated protein kinase kinase (MEK) 1/2 regulates microtubule assembly and spindle organization during rat oocyte maturation. Inhibition of MEK1/2 disrupts chromosome alignment and spindle formation in oocytes.
Area of Science:
- Cell Biology
- Developmental Biology
- Molecular Biology
Background:
- Mitogen-activated protein kinase kinase (MEK) is crucial in the MOS/MEK/MAPK/p90rsk signaling pathway.
- Previous studies established MAPK's role in rat oocyte maturation.
- This study focuses on the localization and function of MEK1/2 during this process.
Purpose of the Study:
- To investigate the spatiotemporal localization of phosphorylated MEK1/2 (p-MEK1/2) during rat oocyte meiosis.
- To elucidate the role of MEK1/2 in microtubule organization and spindle formation.
- To determine the effects of MEK1/2 inhibition on oocyte meiotic progression.
Main Methods:
- Immunofluorescent staining to track p-MEK1/2 localization.
- Taxol-induced microtubule aster formation assays.
- Co-localization studies with gamma-tubulin.
- Pharmacological inhibition of MEK1/2 using U0126.
Main Results:
- p-MEK1/2 dynamically localized to the germinal vesicle, chromosomes, spindle poles, and midbody during meiotic maturation.
- p-MEK1/2 localized to microtubule-organizing centers (MTOCs) and co-localized with gamma-tubulin.
- MEK1/2 inhibition (U0126) did not affect germinal vesicle breakdown but caused chromosome misalignment and abnormal spindle organization.
- U0126 treatment reduced taxol-induced cytoplasmic asters.
Conclusions:
- MEK1/2 plays a significant role in regulating microtubule assembly during rat oocyte meiosis.
- MEK1/2 is essential for proper spindle organization and chromosome alignment.
- These findings highlight MEK1/2's regulatory function in oocyte meiotic maturation.
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