IP₃R1 is required for meiotic progression and embryonic development by regulating mitochondrial calcium and oxidative...

Calcium ions (Ca²⁺) regulate cell proliferation and differentiation and participate in various physiological activities of cells. The calcium transfer protein inositol 1,4,5-triphosphate receptor (IP₃R), located between the endoplasmic reticulum (ER) and mitochondria, plays an important role in regulating Ca²⁺ levels. However, the mechanism by which IP₃R1 affects porcine meiotic progression and embryonic development remains unclear. We established a model in porcine oocytes using siRNA-mediated knockdown of IP₃R1 to investigate the effects of IP₃R1 on porcine oocyte meiotic progression and embryonic development. The results indicated that a decrease in IP₃R1 expression significantly enhanced the interaction between the ER and mitochondria. Additionally, the interaction between the ER and the mitochondrial Ca²⁺ ([Ca²⁺]_m) transport network protein IP₃R1-GRP75-VDAC1 was disrupted. The results of the Duolink II in situ proximity ligation assay (PLA) revealed a weakened pairwise interaction between IP₃R1-GRP75 and VDAC1 and a significantly increased interaction between GRP75 and VDAC1 after IP₃R1 interference, resulting in the accumulation of large amounts of [Ca²⁺]_m. These changes led to mitochondrial oxidative stress, increased the levels of reactive oxygen species (ROS) and reduced ATP production, which hindered the maturation and late development of porcine oocytes and induced apoptosis. Nevertheless, after treat with [Ca²⁺]_m chelating agent ruthenium red (RR) or ROS scavenger N-acetylcysteine (NAC), the oocytes developmental abnormalities, oxidative stress and apoptosis caused by Ca²⁺ overload were improved. In conclusion, our results indicated IP₃R1 is required for meiotic progression and embryonic development by regulating mitochondrial calcium and oxidative damage.