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Updated: Jul 2, 2025

Meiotic Spindle Assessment in Mouse Oocytes by siRNA-mediated Silencing
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PAK1-Dependent Regulation of Microtubule Organization and Spindle Migration Is Essential for the Metaphase

Lei Peng1, Yijing He1, Weihan Wang1

  • 1MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.

Biomolecules
|February 24, 2024
PubMed

Insights

P21-activated kinase 1 (PAK1) is crucial for porcine oocyte maturation, regulating spindle organization and migration during the metaphase I to metaphase II transition. Inhibiting PAK1 disrupts these processes, affecting oocyte development.

Area of Science:

  • Cell Biology
  • Reproductive Biology
  • Molecular Biology

Background:

  • P21-activated kinase 1 (PAK1) regulates cytoskeletal dynamics, cell proliferation, and migration.
  • PAK1 is known to regulate spindle assembly in meiosis I, but its role in the metaphase I to metaphase II (MI-MII) transition in oocytes is unclear.

Purpose of the Study:

  • To investigate the function of PAK1 in regulating microtubule organization and spindle positioning during the MI-MII transition in porcine oocytes.
  • To elucidate the molecular mechanisms by which PAK1 influences oocyte maturation.

Main Methods:

  • Porcine oocytes were treated with PAK1 inhibitor IPA-3 at the MI stage.
  • Changes in first polar body extrusion, actin distribution, and MII spindle reassembly were assessed.
  • Co-immunoprecipitation was used to identify PAK1 interacting proteins involved in spindle assembly and migration.

Main Results:

  • Activated PAK1 expression increased from MI to MII and co-localized with α-tubulin.
  • Inhibiting PAK1 reduced first polar body extrusion, leading to arrest at the anaphase-telophase (ATI) stage.
  • IPA-3 treatment decreased actin distribution and increased MII spindle assembly defects with abnormal positioning, effects reversible with DTT.
  • PAK1 interacts with Aurora A, TACC3, and LIMK1 to regulate spindle assembly and migration.

Conclusions:

  • PAK1 is essential for proper microtubule organization and spindle migration during the MI-MII transition in porcine oocytes.
  • PAK1's function is mediated by its interactions with p-Aurora A, p-TACC3, and p-LIMK1.
  • These findings highlight PAK1 as a key regulator of oocyte meiotic maturation.
Keywords:
P21-activated kinase 1metaphase I–metaphase II transitionporcine oocytesspindle dynamics

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