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Multi-Photon Laser Ablation of Cytoplasmic Microtubule Organizing Centers in Mouse Oocytes
Published on: November 11, 2022
A soft cortex is essential for asymmetric spindle positioning in mouse oocytes
Agathe Chaigne1, Clément Campillo, Nir S Gov
11] CIRB, Collège de France, and CNRS-UMR7241 and INSERM-U1050, Equipe Labellisée Ligue Contre le Cancer, Paris F-75005, France.
Nature Cell Biology
|July 16, 2013
Summary
Cortical tension decreases during mouse oocyte meiosis I due to myosin-II exclusion and actin thickening, enabling spindle positioning. This softening cortex is essential for cell division accuracy.
Area of Science:
- Cell Biology
- Developmental Biology
- Biophysics
Background:
- Cortical tension typically increases at mitosis onset, facilitating cell division.
- Mouse oocytes exhibit decreased cortical tension during meiosis I, a counterintuitive observation given their stable, round shape and active spindle positioning needs.
Purpose of the Study:
- Investigate the mechanism behind reduced cortical tension in mouse oocytes during meiosis I.
- Determine the significance of this tension reduction for spindle positioning.
Main Methods:
- Micropipette aspiration to measure cortical tension.
- Studied the role of actin polymerization and myosin-II localization.
- Investigated the involvement of the Mos-MAPK pathway.
- Utilized theoretical modeling and artificial cortex stiffening.
Main Results:
- Identified an Arp2/3-dependent F-actin thickening crucial for spindle migration.
- Demonstrated cortical tension reduction via myosin-II exclusion from the cortex.
- Showed that F-actin thickening promotes cortical plasticity, leading to cortex softening.
- Confirmed that Mos-MAPK pathway triggers these events in a coordinated manner.
Conclusions:
- A soft, relaxed cortex is essential for accurate meiotic spindle positioning in mouse oocytes.
- The observed decrease in cortical tension is a regulated process vital for oocyte meiotic division.
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