Age-related decrease of meiotic cohesins in human oocytes

PLoS One. 2014 May 7;9(5):e96710. doi: 10.1371/journal.pone.0096710. eCollection 2014.

Abstract

Aneuploidy in fetal chromosomes is one of the causes of pregnancy loss and of congenital birth defects. It is known that the frequency of oocyte aneuploidy increases with the human maternal age. Recent data have highlighted the contribution of cohesin complexes in the correct segregation of meiotic chromosomes. In mammalian oocytes, cohesion is established during the fetal stages and meiosis-specific cohesin subunits are not replenished after birth, raising the possibility that the long meiotic arrest of oocytes facilitates a deterioration of cohesion that leads to age-related increases in aneuploidy. We here examined the cohesin levels in dictyate oocytes from different age groups of humans and mice by immunofluorescence analyses of ovarian sections. The meiosis-specific cohesin subunits, REC8 and SMC1B, were found to be decreased in women aged 40 and over compared with those aged around 20 years (P<0.01). Age-related decreases in meiotic cohesins were also evident in mice. Interestingly, SMC1A, the mitotic counterpart of SMC1B, was substantially detectable in human oocytes, but little expressed in mice. Further, the amount of mitotic cohesins of mice slightly increased with age. These results suggest that, mitotic and meiotic cohesins may operate in a coordinated way to maintain cohesions over a sustained period in humans and that age-related decreases in meiotic cohesin subunits impair sister chromatid cohesion leading to increased segregation errors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age Factors
  • Aging / metabolism*
  • Aneuploidy
  • Animals
  • Cell Cycle Proteins / metabolism*
  • Chromosomal Proteins, Non-Histone / metabolism*
  • Female
  • Humans
  • Meiosis / physiology*
  • Mice
  • Middle Aged
  • Oocytes / metabolism*
  • Young Adult

Substances

  • Cell Cycle Proteins
  • Chromosomal Proteins, Non-Histone
  • cohesins

Grant support

This work was supported by grants from JSPS KAKENHI (22790334 and 25860255 to MT and 21028020 and 23013019 to HK, URL: http://www.jsps.go.jp/j-grantsinaid/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.