The Impact of Arp2/3 Complex Inhibition on Cytoskeleton Dynamics and Mitochondrial Function during Goat Oocyte Meiosis

SIMPLE SUMMARY: The actin-related protein complex 2/3 complex (Arp2/3) is a kind of actin regulatory protein that regulates the nucleation, aggregation and assembly of F-actin. In recent years, there have been reports at home and abroad about the effects of the Arp2/3 complex on oocyte maturation of mammals such as pigs and mice, but few studies are about its effects on goats. In present study we showed that the Arp2/3 complex is necessary for the maintenance of cytoskeletal meiotic dynamics, such as F-actin assembly and spindle organization in goat oocytes. Additionally, these cytoskeletal dynamics are essential for the regulation of mitochondrial distribution and function, including mitochondrial activity and redox homeostasis, which are critical for the meiotic maturation of goat oocytes. ABSTRACT: F-actin is of critical importance in oocyte meiotic maturation. Actin assembly and its dynamics are mainly regulated by actin nucleation factors. The actin-related protein complex 2/3 (Arp2/3) is responsible for the organization of F-actin filaments. However, the role of Arp2/3 complex in goat oocytes has not been fully elucidated. Our findings demonstrate that Arp2/3 complex activity is necessary for the maturation of goat oocytes. The Arp2/3 complex-specific inhibitor CK666 impairs the maturation of goat oocytes and alters the genes associated with cumulus expansion, both of which suggest that normal meiosis is affected. Arp2, one of the subunits of the Arp2/3 complex, was found to be mainly accumulated at the oocyte cortex and to co-localize with F-actin during goat oocyte maturation in our results. Thus, we further investigated the cytoskeleton dynamics and found that Arp2/3 complex inhibition disrupts the F-actin assembly and spindle organization. Further analysis revealed that, in addition to direct effects on the cytoskeleton, Arp2/3 complex could also induce ROS accumulation and oxidative stress by disrupting mitochondrial distribution and function, ultimately increasing the rate of early apoptosis in goat oocytes. Our study provides evidence that the Arp2/3 complex is a key regulator of goat oocyte maturation through its regulation of the cytoskeleton dynamics and mitochondrial function.