PAK2 is essential for chromosome alignment in metaphase I oocytes.

As a highly conserved and ubiquitously expressed serine/threonine kinase, p21-activated kinase 2 (PAK2) participates in diverse biologic events. However, its roles in mouse oocyte meiotic maturation remain unclear. The present study revealed that mouse oocytes depleted of Pak2 were unable to completely progress through meiosis and that a majority were arrested at metaphase I. Pak2 depletion thus prompted MI arrest and induced meiotic chromosome alignment defects in mouse oocytes, in part due to a reduction in polo-like kinase (PLK1). We demonstrated that PAK2's interaction with PLK1 protected it from degradation by APC/C Cdh1 , and that it promoted meiotic progression and bipolar spindle formation. Our data collectively display critical functions for PAK2 in meiotic progression and chromosome alignment in mouse oocytes.