Related Experiment Video
Updated: Jun 9, 2025
Evaluation of the Spindle Assembly Checkpoint Integrity in Mouse Oocytes
Published on: September 13, 2022
PAK4 is Required for Meiotic Resumption, Spindle Assembly, and Cortical Migration in Mouse Oocytes During Meiotic
Ke Song1, Dandan Chen1, Jingyu Li1
1Department of Human Reproductive Medicine, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing Maternal and Child Health Care Hospital, Beijing, 100020, China.
Abstract:
Oocyte meiotic errors can cause infertility, miscarriage, and birth defects. Here the role and the underlying mechanism of p21 activated kinase 4 (PAK4) in mouse oocyte meiosis is evaluated. It is found that PAK4 expression and its phosphorylation are detected in high level at germinal vesicle (GV) stage, and gradually decreased after meiotic resumption in oocytes. PAK4 has direct physical interaction with both mitogen-activated protein kinases 1/2 (MEK1/2) and Paxillin, they are colocalized on the spindle structure during metaphases I and II. Phospho-PAK4 is distributed beneath the cytoplasmic membrane and on the chromosomes, and colocalized with the microtubule organizing center (MTOC) proteins, Pericentrin and γ-tubulin, as well as phosphor-MEK1/2 and phosphor-Paxillin on spindle poles. PAK4 inhibition by chemical inhibitor LCH-7749944, specific Pak4 morpholino oligo or the dominant negative mutant Pak4K350, 351 M influence the meiotic resumption, spindle assembly and its cortical migration, and associated with the downregulation in the dephosphorylation of cyclin dependent kinase 1 (CDK1) and the levels of Cyclin B1, MEK1/2, Paxillin, g-tubulin, acetylated a-tubulin, Arp3, and Cofilin phosphorylation in oocytes. In sum, PAK4 functions to sustain the rational levels of Cyclin B1, MEK1/2, Paxillin, y-tubulin, acetylated a-tubulin, Arp3, and phosphor-Cofilin in mouse oocytes, thereby promotes the meiotic resumption, spindle assembly, and migration during meiotic maturation.
Insights
p21 activated kinase 4 (PAK4) is crucial for mouse oocyte meiosis, regulating spindle assembly and meiotic resumption. Its inhibition disrupts key proteins, impacting oocyte maturation and potentially fertility.
Area of Science:
- Cell Biology
- Developmental Biology
- Reproductive Biology
Background:
- Oocyte meiotic errors contribute to infertility, miscarriage, and birth defects.
- Understanding the molecular mechanisms governing oocyte meiosis is critical for reproductive health.
Purpose of the Study:
- To investigate the role and mechanism of p21 activated kinase 4 (PAK4) in mouse oocyte meiosis.
- To elucidate PAK4's interactions and localization during meiotic maturation.
Main Methods:
- PAK4 expression and phosphorylation analysis in oocytes.
- Co-immunoprecipitation to study protein interactions.
- Inhibition of PAK4 using chemical inhibitors, morpholinos, and dominant-negative mutants.
- Assessment of meiotic resumption, spindle assembly, and protein level changes.
Main Results:
- PAK4 is highly expressed and phosphorylated at the germinal vesicle stage, decreasing post-meiotic resumption.
- PAK4 interacts with MEK1/2 and Paxillin, localizing to spindle structures and spindle poles.
- PAK4 inhibition impairs meiotic resumption, spindle assembly, and cortical migration.
- Inhibition leads to downregulation of Cyclin B1, MEK1/2, Paxillin, and affects phosphorylation of key proteins like Cofilin.
Conclusions:
- PAK4 plays a vital role in maintaining appropriate levels of key proteins essential for meiotic maturation.
- PAK4 promotes meiotic resumption, spindle assembly, and spindle migration in mouse oocytes.
- PAK4's function is critical for successful oocyte meiotic progression, with implications for fertility.
Related Concept Videos
02:57Meiosis vs. Mitosis
Before the start of mitosis and meiosis I, the cell synthesizes DNA, resulting in two homologous copies of each chromosome. DNA synthesis is...
02:02Meiosis II
The timing and cell division patterns of meiosis differ between males and females. In male meiosis, the centrosomes are part of the formation of the meiotic spindle. However, in oocytes, including that of humans, Drosophila,...
02:50Spindle Assembly
In most cells, centrosomes are the primary microtubule nucleation centers. In the centrosome-mediated pathway, the G2-prophase transition triggers centrosome maturation and increased microtubule nucleation. Progressive nucleation results in a...
01:42Microtubule Associated Proteins (MAPs)
02:19The Spindle Assembly Checkpoint
Many proteins function together to control the spindle assembly checkpoint. Mutations affecting these proteins may allow cells to proceed into anaphase prematurely, resulting in the...
02:15M-Cdk Drives Transition Into Mitosis
Cyclin-dependent kinases, or Cdks, work in concert with cyclins to control cell cycle transitions. M-Cdk, a complex of Cdk1 bound to M cyclin, is a well-known example of this coordinated control that drives the transition from the G2 to the M phase.
M cyclin...