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Inhibition of Rac1 GTPase activity affects porcine oocyte maturation and early embryo development
Si-Jing Song1, Qiao-Chu Wang1, Ru-Xia Jia1
1College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, China.
Abstract:
Mammalian oocyte asymmetric division relies on the eccentric positioning of the spindle, resulting in the polar body formation. Small signaling G protein Rac1 is a member of GTPases, which regulates a diverse array of cellular events, including the control of cell growth, cytoskeletal reorganization, and the activation of protein kinases. However, effects of Rac1 on the porcine oocyte maturation and early embryo development are not fully understood. In present study we investigated the role of Rac1 in oocyte maturation and embryo cleavage. We first found that Rac1 localized at the cortex of the porcine oocytes, and disrupting the Rac1 activities by treating with NSC 23766 led to the failure of polar body emission. In addition, a majority of treated oocytes exhibited abnormal spindle morphology, indicating that Rac1 may involve into porcine oocyte spindle formation. This might be due to the regulation of Rac1 on MAPK, since p-MAPK expression decreased after NSC 23766 treatments. Moreover, we found that the position of most meiotic spindles in treated oocytes were away from the cortex, indicating the roles of Rac1 on meiotic spindle positioning. Our results also showed that inhibition of Rac1 activity caused the failure of early embryo development. Therefore, our study showed the critical roles of Rac1 GTPase on porcine oocyte maturation and early embryo cleavage.
Insights
The small signaling G protein Rac1 is crucial for porcine oocyte maturation and early embryo development. Inhibiting Rac1 disrupts spindle formation and positioning, leading to failed polar body emission and embryo cleavage.
Area of Science:
- Cell Biology
- Developmental Biology
- Reproductive Biology
Background:
- Asymmetric cell division in mammalian oocytes is essential for polar body formation, driven by eccentric spindle positioning.
- The small signaling G protein Rac1, a GTPase, regulates critical cellular processes like cytoskeletal organization and kinase activation.
- The precise role of Rac1 in porcine oocyte maturation and early embryo development remains largely uncharacterized.
Purpose of the Study:
- To investigate the function of Rac1 in porcine oocyte maturation and early embryo cleavage.
- To elucidate the mechanisms by which Rac1 influences spindle formation, positioning, and polar body emission.
Main Methods:
- Rac1 localization was determined in porcine oocytes.
- Rac1 activity was inhibited using NSC 23766.
- Oocyte maturation, polar body emission, spindle morphology, and p-MAPK expression were assessed.
- Early embryo development and cleavage rates were evaluated.
Main Results:
- Rac1 was localized to the cortex of porcine oocytes.
- Inhibition of Rac1 led to failed polar body emission and abnormal spindle morphology.
- Rac1 inhibition decreased p-MAPK expression and disrupted meiotic spindle positioning.
- Blocking Rac1 activity resulted in the failure of early embryo development.
Conclusions:
- Rac1 GTPase plays a critical role in regulating meiotic spindle formation and positioning during porcine oocyte maturation.
- Rac1 is essential for successful polar body emission and early embryonic cleavage in pigs.
- These findings highlight Rac1 as a key regulator of reproductive processes in porcine oocytes.
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