Scientists have discovered that certain “junk” DNA sequences, known as transposable elements (TEs), play a crucial role in regulating gene expression in the human genome.
Why it matters: This finding challenges the long-held belief that these sequences, which make up nearly 50 percent of human DNA, are non-functional genetic leftovers from ancient viruses. The study reveals that TEs, particularly a family called MER11, act as “genetic switches” that influence gene activity without altering the underlying DNA sequence.
The details:
- Researchers from Japan, China, Canada, and the US focused on MER11 sequences, which originated from an endogenous retrovirus that infected simian ancestors millions of years ago.
- The team developed a new classification system for MER11 sequences based on their evolutionary relationships and preservation in primate genomes, dividing them into four subfamilies (MER11_G1 through G4).
- Using a technique called lentiMPRA, the researchers tested approximately 7,000 MER11 sequences from humans and primates, finding that the youngest subfamily, MER11_G4, had a particularly strong influence on gene expression.
- MER11_G4 contains specific DNA motifs that attract transcription factors, proteins that regulate gene activity.
The study suggests that these “junk” DNA sequences have evolved to play important roles in gene regulation, especially during early human development.
What they’re saying:
- “Young MER11_G4 binds to a distinct set of transcription factors, indicating that this group gained different regulatory functions through sequence changes and contributes to speciation,” said lead author Xun Chen from the Chinese Academy of Sciences.
- “Transposable elements are thought to play important roles in genome evolution, and their significance is expected to become clearer as research continues to advance,” said study coauthor Fumitaka Inoue from Kyoto University.
The big picture: This research opens new doors to understanding genetic regulation and evolutionary history, highlighting the need for continued study in this area. By better understanding these sequences, scientists hope to uncover more about the complexities of our genetic makeup and the evolutionary history embedded within our DNA.
What’s next: Further research is needed to fully understand the roles of transposable elements in gene regulation and their potential implications for human health and evolution.
