AQP7 Protects Vitrified Sheep GV-Stage Oocyte Maturation via Mitochondrial Activity

Oocyte vitrification imposes oxidative stress that compromises maturation competence. Aquaporin-7 (AQP7) has been implicated in cellular redox regulation, but its specific role in cryopreserved oocytes remains unclear. Here, germinal vesicle (GV) stage oocytes were vitrified and warmed with AQP7 inhibitor Z433927330 (0.5, 5, 50 μM). AQP7 inhibition disrupted redox balance, compromised mitochondrial function. Consequently, it severely compromised developmental competence, leading to significantly reduced cleavage (39.90% ± 6.17 vs. 52.93% ± 3.37) and blastocyst formation rates (1.67% ± 2.89 vs. 5.17% ± 2.49) in vitro. To confirm, we performed microinjection-mediated AQP7 knockdown and overexpression and assessed their effects on maturation. AQP7 knockdown further reduced the maturation rate of vitrified oocytes (20.22% ± 3.14 vs. 36.31% ± 2.10), whereas overexpression partially restored it (43.98% ± 4.71 vs. 33.74% ± 2.21). The mitochondrial-targeted antioxidant MitoQ partially rescued the maturation rate (53.13% ± 2.75 vs. 43.52% ± 2.71). Thus, AQP7 is essential for the maturation of vitrified sheep oocytes by safeguarding intracellular redox homeostasis, thereby preventing mitochondrial dysfunction and cytoskeletal damage, and loss of embryonic developmental potential.