The 23rd International Symposium on Developmental Biotechnology[Eun-Seo Kim] > 학회발표

Spermidine Alleviates oocyte quality in Postovulatory Oocyte Aging by Restoring Mitochondrial Function and NAD⁺ Biosynthesis via eIF5A Hypusination

Eun-Seo Kim^1,2*, Hyo-Jin Park^{1, 2}, Yeo-Ryeong Kim^2,3 and Deog-Bon Koo^{1, 2, 3**}

¹Department of Biotechnology, College of Engineering, ²Center for Infertility, ³Department of Companion Animal Industry, College of Natural and Life Sciences, Daegu University, 201 Daegudae-ro Jillyang, Gyeongsan, Gyeongbuk 38453, Republic of Korea

Postovulatory aging (POA) of oocytes occurs when fertilization is delayed after ovulation. The POA model has been reported to be associated with mitochondrial dysfunction, NAD⁺ synthesis, and reduced developmental competence of subsequent embryos in pigs. However, studies on the anti-aging effects of spermidine (spd), a natural polyamine endogenously present in the female reproductive organs, in oocytes of the POA model are still limited. In the present study, we evaluated the effects of spd on NAD⁺ synthesis, mitochondrial function, and gene expression through hypusination of eIF5A(eIF5A^hyp) in the POA model oocytes. Immature porcine oocytes were first matured in vitro for 44 hours and then further cultured for an additional 24 hours in the presence of 50 µM spd to induce POA. To analyze differences and patterns in gene expression, RNA sequencing (RNA-seq) was performed, revealing that the expression of 39 genes were upregulated and 20 genes were downregulated (IVM vs POA group). Subsequently, mitochondrial function, NAD⁺ synthesis, and gene expression related to eIF5A^hyp were quantitatively analyzed by immunofluorescence (IF), western blotting, and qPCR. As a result, compared to aged control oocytes, spd-treated POA oocytes showed a significant decrease (p < 0.01) in the expression of aging-related genes (CLU, FAM111A), whereas the levels of ATP production (p < 0.05), mitochondrial membrane potential (MMP; p < 0.05), and NAD⁺ biosynthesis (p < 0.01), which were reduced by aging, were significantly restored. In addition, protein-level analysis showed that protein levels of eIF5A^hyp decreased in the POA model, whereas LC3B expression related to mitophagy increased.

In conclusion, spd induces eIF5A^hyp expression, alleviates mitochondrial dysfunction and subsequent decline in NAD⁺ synthesis during POA model, and maintains mitochondrial integrity and oocyte quality as an effective anti-aging modulator.

Key words: post-ovulatory aging(POA), spermidine(spd), mitochondrial metabolism, NAD⁺ synthesis, hypusination eIF5A(eIF5A^hyp)

E-mail: eskitty01@naver.com (Eun-Seo Kim)

Funding

This work was supported by the National Research Foundation of Korea (NRF) funded by the government (MSIT) of the Republic of Korea (RS-2021-NR061941 and RS-2022-NR069006). This study was supported by the Gyeongsangbuk-do Regional Innovation System and Education (RISE) Project.