Paxillin mediates ARP2-dependent actin assembly for spindle migration in mammalian oocyte meiosis.

Paxillin is a multi-domain scaffold protein that is involved in several cellular functions, including focal adhesion, cell motility and cell aging. Previous studies have shown that Paxillin affects the resumption of meiosis in Xenopus oocytes. In the present study, we report the distinct roles of Paxillin in mammalian oocytes including mice and pigs. Our results indicate that Paxillin is expressed in mouse oocytes and is primarily concentrated in the cortical area, which is closely associated with actin. Disruption of Paxillin expression or function did not influence the process of germinal vesicle breakdown in either mouse or porcine oocytes at GV stage, as confirmed by the expression levels of Mos and MPF. Furthermore, Paxillin disruption did not alter spindle morphology but did affect meiotic spindle migration and polar body extrusion, likely due to a decrease in actin filaments. Further analysis revealed that the actin nucleators Arp2/3 and N-WASP were reduced in Paxillin-knockdown oocytes at MI stage. Overexpression of Paxillin also did not impact GV breakdown, spindle formation, or polar body extrusion. However, the supplementation of exogenous Paxillin mRNA rescued the defects in spindle positioning and polar body extrusion caused by Paxillin knockdown. Taken together, our findings suggest that Paxillin plays a critical role in spindle migration during oocyte meiosis by mediating actin dynamics through the Arp2/3 complex, highlighting functional differences between species.