Article

DNA damage repair is suppressed in porcine aged oocytes

Tao Lin1,2, Ling Sun1,2, Jae Lee1, So Kim1, Dong Jin1,*
Author Information & Copyright
1Chungnam National University, Daejeon 34134, Korea.
2School of Life Sciences and Food Engineering, Hebei University of Engineering, Handan 056038, China.
*Corresponding Author: Dong Il Jin, Chungnam National University, Daejeon 34134, Korea, Republic of. E-mail: dijin@cnu.ac.kr.

© Copyright 2021 Korean Society of Animal Science and Technology. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: Jun 04, 2021; Revised: Jul 01, 2021; Accepted: Jul 09, 2021

Published Online: Jul 26, 2021

Abstract

This study sought to evaluate DNA damage and repair in porcine postovulatory aged oocytes. The DNA damage response, which was assessed by H2A.X expression, increased in porcine aged oocytes over time. However, the aged oocytes exhibited a significant decrease in the expression of RAD51, which reflects the DNA damage repair capacity. Further experiments suggested that the DNA repair ability was suppressed by the downregulation of genes involved in the homologous recombination (HR) and nonhomologous end-joining (NHEJ) pathways. The expression levels of the cell cycle checkpoint genes, <italic>CHEK1</italic> and <italic>CHEK2</italic>, were upregulated in porcine aged oocytes in response to induced DNA damage. Immunofluorescence results revealed that the expression level of H3K79me2 was significantly lower in porcine aged oocytes than in control oocytes. In addition, embryo quality was significantly reduced in aged oocytes, as assessed by measuring the cell proliferation capacity. Our results provide evidence that DNA damage is increased and the DNA repair ability is suppressed in porcine aged oocytes. These findings increase our understanding of the events that occur during postovulatory oocyte aging.

Keywords: oocyte aging; DNA damage; DNA repair; H3K79me2; pig