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Updated: May 16, 2026
Meiotic Spindle Assessment in Mouse Oocytes by siRNA-mediated Silencing
Published on: October 11, 2015
The microtubule-associated protein ASPM regulates spindle assembly and meiotic progression in mouse oocytes
Xiao-Ling Xu1, Wei Ma, Yu-Bo Zhu
1Institute of Animal Husbandry and Veterinary Medicine, Beijing Municipal Academy of Agriculture and Forestry Sciences, Beijing, China.
Abstract:
The microtubule-associated protein ASPM (abnormal spindle-like microcephaly-associated) plays an important role in spindle organization and cell division in mitosis and meiosis in lower animals, but its function in mouse oocyte meiosis has not been investigated. In this study, we characterized the localization and expression dynamics of ASPM during mouse oocyte meiotic maturation and analyzed the effects of the downregulation of ASPM expression on meiotic spindle assembly and meiotic progression. Immunofluorescence analysis showed that ASPM localized to the entire spindle at metaphase I (MI) and metaphase II (MII), colocalizing with the spindle microtubule protein acetylated tubulin (Ac-tubulin). In taxol-treated oocytes, ASPM colocalized with Ac-tubulin on the excessively polymerized microtubule fibers of enlarged spindles and the numerous asters in the cytoplasm. Nocodazole treatment induced the gradual disassembly of microtubule fibers, during which ASPM remained colocalized with the dynamic Ac-tubulin. The downregulation of ASPM expression by a gene-specific morpholino resulted in an abnormal meiotic spindle and inhibited meiotic progression; most of the treated oocytes were blocked in the MI stage with elongated meiotic spindles. Furthermore, coimmunoprecipitation combined with mass spectrometry and western blot analysis revealed that ASPM interacted with calmodulin in MI oocytes and that these proteins colocalized at the spindle. Our results provide strong evidence that ASPM plays a critical role in meiotic spindle assembly and meiotic progression in mouse oocytes.
Insights
The microtubule-associated protein ASPM is crucial for organizing the meiotic spindle and ensuring proper cell division in mouse oocytes. Its downregulation disrupts spindle assembly and halts meiotic progression, highlighting its essential role.
Area of Science:
- Cell Biology
- Developmental Biology
- Reproductive Biology
Background:
- Microtubule-associated protein ASPM (abnormal spindle-like microcephaly-associated) is vital for spindle organization in lower organisms.
- Its role in mammalian oocyte meiosis remains uncharacterized.
Purpose of the Study:
- To investigate the function of ASPM in mouse oocyte meiotic maturation.
- To analyze ASPM's localization, expression dynamics, and impact on meiotic spindle assembly and progression.
Main Methods:
- Immunofluorescence microscopy to determine ASPM localization.
- Taxol and nocodazole treatments to assess microtubule dynamics.
- Morpholino-mediated gene knockdown to study ASPM function.
- Co-immunoprecipitation and Western blot to identify interacting proteins.
Main Results:
- ASPM localizes to the entire spindle in metaphase I and metaphase II oocytes, co-localizing with acetylated tubulin.
- ASPM remains associated with microtubules during dynamic assembly and disassembly.
- ASPM downregulation leads to abnormal spindle formation and blocks oocytes at metaphase I.
- ASPM interacts with calmodulin in metaphase I oocytes and localizes to the spindle.
Conclusions:
- ASPM is essential for proper meiotic spindle assembly in mouse oocytes.
- ASPM plays a critical role in regulating meiotic progression during oocyte maturation.
- ASPM's interaction with calmodulin may contribute to its function in spindle organization.
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