Aberrant cortex contractions impact mammalian oocyte quality.

Area of Science:

• Cell Biology
• Reproductive Biology
• Biophysics

Background:

• The oocyte cortex plays a crucial role in cell shape and chromosome segregation.
• Actin remodeling in the cortex is essential for proper oocyte function.
• The Arp2/3 complex is known to regulate cortical actin dynamics.

Purpose of the Study:

• To investigate the consequences of Arp2/3 complex absence on mouse oocyte cortical remodeling and function.
• To explore the impact of novel cortical contractions on cytoplasmic organization and female fertility.
• To examine the presence and implications of similar contractions in human oocytes.

Main Methods:

• Genetic manipulation to create Arp2/3 complex-deficient mouse oocytes.
• Advanced imaging techniques to visualize cortical actin dynamics and cytoplasmic activity.
• Machine learning approaches to analyze cellular contractions and their effects.
• In vitro fertilization (IVF) procedures for human oocyte collection and analysis.

Main Results:

• Oocytes lacking the Arp2/3 complex display cortical actin remodeling and unprecedented cortical contractions during division.
• These contractions lead to cytoplasmic stirring, disrupting organelle organization and activity.
• Impaired polyspermy prevention capacity reduces female fertility in affected mice.
• Similar contractions observed in human oocytes correlate with increased cytoplasmic motion but not spindle defects or aneuploidy.

Conclusions:

• Cortical F-actin dynamics and contractions exert multiscale effects on oocyte cytoplasmic organization.
• Uncontrolled cortical contractions negatively impact oocyte quality and female fertility.
• Findings reveal a conserved mechanism in mammalian oocytes with potential implications for IVF and reproductive health.