WHAMM is essential for spindle formation and spindle actin polymerization in maturing mouse oocytes

Area of Science:

• Cell Biology
• Reproductive Biology
• Cytoskeletal Dynamics

Background:

• WHAMM (WAS Protein Homolog Associated with Actin, Golgi Membranes, and Microtubules) is known for its roles in actin nucleation and microtubule binding.
• Its specific function in mammalian oocyte maturation remained largely uncharacterized.

Purpose of the Study:

• To investigate the role of WHAMM during mouse oocyte maturation.
• To elucidate WHAMM's contribution to cytoskeletal organization and cell division in oocytes.

Main Methods:

• Detection of WHAMM mRNA and protein expression throughout oocyte maturation.
• WHAMM knockdown using RNA interference.
• Immunofluorescence microscopy to assess WHAMM localization and cytoskeletal organization.
• Treatment with brefeldin A (BFA) to study WHAMM localization under disrupted Golgi transport.

Main Results:

• WHAMM is present and co-localizes with the actin cage surrounding the spindle in maturing mouse oocytes.
• WHAMM knockdown disrupts spindle formation, microtubule-organizing center localization, and spindle actin organization.
• Depletion of WHAMM leads to impaired chromosome alignment, potentially causing aneuploidy and asymmetric cell division.
• Brefeldin A treatment causes abnormal WHAMM localization, suggesting a link to Golgi-associated processes.

Conclusions:

• WHAMM is essential for proper mouse oocyte maturation, playing a critical role in actin cytoskeleton organization and spindle formation.
• WHAMM likely functions by activating the Arp2/3 complex to promote spindle actin formation, ensuring correct spindle length and chromosome alignment.
• These findings highlight WHAMM as a key regulator of cytoskeletal dynamics vital for female gamete development.