Selfish DNA is not only harmful, but plays a vital role in embryo development

Study finds that transposable elements, once thought to be parasitic, are crucial for early human development. Sinai Health researchers have shown that these genomic segments, called “selfish DNA”, in particular LINE-1, actively contribute to the proper formation of human embryos. Historically considered harmful, these elements represent approximately 20% of the human genome, while our functional genes represent less than 2%.

Transposons and early embryo development

Transposons, which have the ability to move through the genome, were initially compared to viruses because of their ability to replicate and disrupt normal genes. Dr. Juan Zhang, co-senior author and postdoctoral researcher, observed that LINE-1 RNA is particularly active in early stages of embryo development, contrary to the long-held belief that these elements primarily cause diseases such as cancer or hemophilia.

Crucial information from LINE-1 blockage

Dr. Zhang’s team found that when LINE-1 activity was blocked in human embryonic stem cells, the cells reverted to a stage known as the 8-cell stage. At this stage, the cells can still develop into embryonic and placental cells. This find demonstrates the importance of LINE-1 in helping the embryo develop specialized cells essential for its progression.

Organization of DNA within the nucleus

Further research has shown that LINE-1 plays an important role in organizing DNA within the cell nucleus. It moves chromosome 19, key at the 8-cell stage, to areas that regulate gene expression. This organization ensures that the embryo progresses smoothly through its stages of development.
Potential impact on medicine and disease research

These findings could impact fertility treatments and stem cell research, providing new insights into how early human development can be supported. Additionally, understanding the function of LINE-1 could shed light on its involvement in neurological disorders and cancers. Dr. Anne-Claude Gingras, another prominent research voice, acknowledged the importance of this study, emphasizing that much remains to be discovered about these intriguing genetics.