IP 3 R1 regulates calcium balance in porcine oocyte maturation and early embryonic development.

The dynamic balance of Ca ²⁺ in oocytes promotes the recovery of the meiotic arrest phase, consequently promoting oocyte maturation. Hence, the analysis of the maintenance and role of calcium homeostasis in oocytes has important guiding significance for obtaining high-quality eggs and maintaining the development of preimplantation embryos. Inositol 1,4,5-trisphosphate receptors (IP ₃ Rs) are calcium channel proteins that regulate the dynamic balance between the endoplasmic reticulum (ER) and mitochondrial Ca ²⁺ . Nevertheless, the expression and role of IP ₃ R in normal pig oocytes have not been reported, and other studies have focused on the role of IP ₃ R in damaged cells. The purpose of this study was to investigate the potential role of IP ₃ R in regulating calcium homeostasis in oocyte maturation and early embryonic development. Our results showed that IP ₃ R1 is stably expressed at different stages of porcine oocyte meiosis, IP ₃ R1 gradually converges to the cortex, and cortical clusters are formed in MII stages. The loss of IP ₃ R1 activity contributeds to the failure of porcine oocyte maturation and cumulus cell expansion, as well as the obstruction of polar body excretion. Further analysis showed that IP ₃ R1 plays an important role in affecting calcium balance by regulating the IP ₃ R1-GRP75-VDAC1 channel between mitochondria and the endoplasmic reticulum (ER) during porcine oocyte maturation. Inhibiting IP ₃ R1 expression-induced ER dysfunction, contributeding to ER calcium concentration ([Ca ²⁺ ] _ER) release outwards into mitochondria and causing mitochondrial free calcium concentration ([Ca ²⁺ ] _m ) overload and mitochondrial oxidative stress, which was confirmed by the increase in the level of reactive oxygen species (ROS) and apoptosis. Thereby, IP ₃ R1 plays an important role in affecting calcium balance by regulating the IP ₃ R1-GRP75 -VDAC1 channel between mitochondria and the ER during porcine oocyte maturation, inhibiting IP ₃ R1 expression-induced calcium overload and mitochondrial oxidative stress, and increasing ROS levels and apoptosis.
Competing Interests: Declaration of competing interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled, “IP(3)R1 regulates calcium balance in porcine oocyte maturation and early embryonic development”.
(Copyright © 2023 Elsevier Inc. All rights reserved.)