Scientists have discovered a protein that helps preserve egg chromosomes.

With age, the quality of eggs decreases, and the probability of errors in the distribution of chromosomes increases. This is one of the reasons for the age-related decrease in fertility and an increased risk of chromosomal abnormalities in embryos. Japanese researchers have discovered a protein that helps protect the chromosomes of eggs from such changes. Experiments on mice have shown that it supports the work of the molecular complex that holds the chromosomes together. The information that scientists have learned about the mechanisms of reproductive aging can be found in the Izvestia article.

Protein for protecting chromosomes

The study is published in the journal Nature Aging. A team led by Professor Keiichiro Ishiguro of Chiba University has discovered a previously unknown protein OMC1. It is present on the chromosomes of eggs from the prenatal period and persists into adulthood.

To understand its function, the scientists studied the activity of genes in immature eggs and male germ cells. By analyzing individual cells, they identified the Omc1 gene, the activity of which is characteristic of eggs before they enter a long-term dormant state. Further experiments showed that the OMC1 protein is located on chromosomes in the same regions as the REC8-cohesin complex.

This complex works as a molecular "glue": it holds copies of chromosomes together until they separate during egg maturation. Unlike many other proteins, REC8 is not replenished during a long period of rest, so its gradual loss can disrupt the correct distribution of chromosomes.

Scientists have noted the ability of the ovaries to change after menopause

What happens without OMC1

The researchers then created genetically modified mice that lacked the Omc1 gene. In their eggs, the REC8 protein began to disappear from the chromosomes earlier than usual. As a result, even in young animals, the connection between the chromosomes weakened and errors occurred during their separation — disorders that are often observed in aging eggs.

When the scientists restored the production of OMC1 in adult eggs, the level of REC8 on the chromosomes partially increased, and the number of errors in their distribution decreased. This indicates that OMC1 helps maintain the molecular machinery responsible for chromosome integrity.

Scientists have reported drastic changes in the body during menopause

The connection with early menopause

Humans have an analog of the Omc1 gene, CCDC201. In previous genetic studies, some of its variants were associated with early menopause and decreased ovarian function. To test the possible impact of such changes, the scientists studied a shortened version of the mouse protein OMC1, corresponding to one of the variants of the human gene.

It turned out that the altered protein could not attach itself to the chromosomes of the eggs and restore their cohesion. This suggests that disturbances in the OMC1/CCDC201 system may be related to differences in the rate of reproductive aging. At the same time, the main part of the experiments was conducted on mice. It is not yet known how precisely the discovered mechanism works in human eggs and whether it will be possible to use it to develop ways to preserve fertility.