Decreased cofilin1 expression is important for compaction during early mouse embryo development

Area of Science:

• Developmental Biology
• Cell Biology
• Molecular Biology

Background:

• Early mouse development involves compaction, establishing cellular asymmetry through cell flattening and polarization.
• The cytoskeletal mechanisms underlying polarized molecule and organelle distribution during compaction are not fully understood.

Purpose of the Study:

• To investigate the role of cofilin1, an actin-binding protein, in mouse embryonic compaction.
• To elucidate the cytoskeletal basis for cell polarity establishment during this critical developmental stage.

Main Methods:

• RNA interference (siRNA) microinjection to down-regulate cofilin1 expression.
• Time-lapse video microscopy for continuous observation of embryonic development.
• Pronuclear microinjection of mutated cofilin1 plasmids.
• Fluorescein-phalloidin staining and scanning electron microscopy.

Main Results:

• Decreased cofilin1 expression accelerated compaction and promoted apical pole formation.
• Microinjection of anti-cofilin1 antibody or siRNA led to earlier cell adherence.
• Sustained active cofilin1 resulted in blastomeres that failed to adhere, indicating cofilin1 inactivation is crucial.
• Cofilin1 knockdown embryos showed microvilli formation on blastomeres.

Conclusions:

• Cofilin1 plays a significant role in regulating cortical cytoplasmic organization during mouse embryo compaction.
• Cofilin1 inactivation is essential for cell flattening, adherence, and polarity establishment.
• These findings highlight cofilin1's importance in the cytoskeletal dynamics governing early embryonic development.