Research and development of a new technology to track jump gene movement

Copyright © iCell Bioscience Inc, Shanghai 2018-2019

Nearly half of the DNA sequences in the human body are composed of jumping genes (also known as transposons). They hop within the genome of developing egg cells and play an important role in evolution. However, their movement can also lead to new mutations that can lead to diseases such as hemophilia and cancer. Little is known about the timing and location of their movement within the developing germ cells. After all, this is a key process to ensure that the jumping gene is transmitted in the offspring, but it can also cause the host to develop a genetic disease.

In a new study, researchers from the Carnegie Institute of Science in the United States have developed a new technology to track skip gene movement. It was also discovered that during a particular egg development, a group of hopping genes called retrotransposons hijacked specific cells called nurturing cells, which nurtured the developing eggs.

These hopping genes use infesting cells to produce invasive substances (their own copies, also known as virus-like particles) that migrate into nearby eggs and are subsequently integrated into the DNA of the egg.

Animals unwittingly produce a powerful system to inhibit the activity of jumping genes. This system uses small non-coding RNA called piRNA, which recognizes jumping genes and inhibits their activity. Sometimes, jumping genes still move successfully, suggesting that they have adopted special strategies to evade piRNA control. However, tracking jump gene movements to understand the strategies they take is a daunting task.

In this new study, these researchers used Drosophila melanogaster as a research object to develop a method to track the movement of jumping genes. To facilitate the study, piRNA inhibition was disrupted to increase the activity of these skipping genes, and then their movement was monitored during egg development, and strategies to allow skip gene movement were discovered.

These jumping genes hardly move within the stem cells that produce the developing egg cells, probably because these stem cells have only two copies of the genome for use by these skipping genes. Instead, these hopping genes use a supporting nurturing cell, each feeding cell providing up to thousands of copies of the genome, so that they can be used as a factory for large-scale production of virus-like particles. However, they are not integrated into the feeding cells that produce them. Instead, they wait for the opportunity until they are transported to the egg cells that are connected to the feeding cells, where hundreds of new copies of the jumping gene are integrated into the egg DNA.

Studies have shown how parasitic genetic elements adjust their activity according to time and distinguish between different cell types in order to strongly spread their own copies, promote evolutionary changes and cause disease.

The research team has found that mammalian egg development uses many of the same mechanisms as Drosophila, such as nurturing cells to nourish developing eggs. Therefore, these findings may also play an important role in understanding mammalian evolution and disease production.