Latest news with #transposableElements
Yahoo
28-07-2025
- Science
- Yahoo
Scientists Find Secret Code in Human DNA
One person's junk is another's treasure. An international team of scientists have found that strings of "junk" DNA in the human genome that were previously written off as having no useful function are actually pretty important after all. The work, published as a study in the journal Science Advances, focuses on transposable elements, a class of DNA sequences that can "jump," via a biological copy-and-paste mechanism, to different locations in a genome. These "jumping genes" take up nearly 50 percent of human DNA; in other organisms, the proportion is even higher. What the researchers from Japan, China, Canada, and the US found is that a particular family of these TEs, called MER11, can strongly influence gene expression and act like "genetic switches" — without actually changing the underlying DNA. "Our genome was sequenced long ago, but the function of many of its parts remain unknown," study coauthor Fumitaka Inoue from Kyoto University said in a statement about the work. MER11 sequences are what's known as long terminal repeat (LTR) retrotransposons. Spookily, these are believed to have originated from an endogenous retrovirus (ERV) that infected a simian ancestor tens of millions of years ago, hijacking the DNA of the cells it invaded to produce copies of its genetic makeup that have never gone away, but have largely remained inert. Per the researchers, at least eight percent of the human genome comes from these retroviruses. That, plus all the other TEs littering our genome, makes for a lot of puzzling clutter for human scientists to sift through. The authors argue that the current methods for classifying and annotating TEs are inaccurate, leading to DNA sequences being overlooked as genetic junk. This inspired them to test their own classification system. "The proper classification and annotation of LTR instances is critical to understanding their evolution, co-option and potential impact on the host," the authors wrote in the study. The researchers' system classified MER11 sequences based on their evolutionary relationships and how well they were preserved in primate genomes, according to the researchers' statement. Then, they divided MER11 into four separate subfamilies, MER11_G1 through G4, based on their age. This allowed the team to compare the MER11 subfamilies to what are known as epigenetic marks: chemicals that can affect how important proteins function, and as a consequence affect gene activity. Crucially, epigenetic marks don't have to physically alter a cell's DNA to modify a cell's behavior, such as silencing a gene that should be expressed. Accurately tying the MER11 subfamilies to the markers is a key step to revealing the extent of their impact on gene expression. With that as a springboard, the team tested some 7,000 MER11 sequences from humans and primates, measured how much each one affected gene activity, and found that the youngest MER11 subfamily, G4, had a strong ability to influence gene expression — namely, by bearing its own DNA "motifs" that attract proteins called transcription factors that regulate what genes are switched on and off. "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," lead author Xun Chen from the Chinese Academy of Sciences said in the statement. The implications are fascinating. Though these strands of DNA may have started as "junk," they have gradually insinuated their way to playing a role in gene regulation today — suggesting a vast portion of unknown evolutionary history that we're only scratching the surface of. "Transposable elements are thought to play important roles in genome evolution, and their significance is expected to become clearer as research continues to advance," Inoue said. More on genetics: Elon Musk Using Eugenics Startup to Inspect DNA of Potential Babies for Intelligence
Yahoo
28-07-2025
- Science
- Yahoo
Scientists Found a Hidden Code in the Human Genome
Here's what you'll learn when you read this story: Around 45 percent of human DNA is made up of transposable elements, or TEs—genetic leftovers from now-extinct viruses that scientists once believed to be 'junk DNA.' But that view is changing, and a new study—which grouped TEs based on evolutionary relationships and level of conservation—found that one family of sequences known as MER11 plays a role in gene expression. Nearly 80 years after their initial discovery, scientists are still finding new things about how TEs play a vital role in primate evolution. Ever since Swiss physician Friedrich Miescher first isolated DNA back in 1869, science has been on an incredible path of genomic discovery. One of the major moments in the journey occurred in the 1940s, when cytogeneticist Barbara McClintock discovered transposable elements (TE), also known as 'jumping genes.' Decades later, The Human Genome Project found that these elements made up a staggering 45 percent of the human genome, and managed to proliferate over millions of years thanks to a 'copy-and-paste' mechanism. Because these sequences are highly repetitive and nearly identical, they've been disregarded as 'junk DNA' for decades—genetic leftovers from long-extinct viruses. But in recent years, this unflattering view of these sequences has begun to change. Today, scientists believe that TEs play a role in genome function, chromosome evolution, speciation, and diversity. However, due to their repetitive nature, TEs remain difficult to research. Now, a new international study has found a novel method for analyzing these mysterious sequences, and they've discovered hidden patterns responsible for gene expression. The results of the study were published in the journal Science Advances. 'Our genome was sequenced long ago, but the function of many of its parts remain unknown,' Fumitaka Inoue, a co-author of the study from Kyoto University, said in a press statement. Understanding TEs would solve one of the biggest mysteries of the genome. In an attempt to better understand TEs, the researchers developed a new method for classifying them. Eschewing standard annotation tools, this study groups TEs based on both their evolutionary relationships and their conservation quality in the primate genome. Focusing on a family of sequences called MER11, the new method allowed scientists to divide the group into subgroups, named MER11_G1 through G4. The G1 subgroup represented the oldest evolutionary sequences, while G4 contained the youngest. By looking at MER11 through this new lens, researchers were able to compare these new subfamilies with epigenetic markers, and found that these groups appeared to have a regulatory function within the genome. In other words, they acted like on-off switches for gene expression—particularly in early human development. Of course, it's one thing to infer a pattern, and another to see it in action. So, the team used a technique known as 'lentiviral massively parallel reporter assay,' or lentiMPRA, to measure 7,000 MER11 sequences using human stem cells and early-stage neural cells. This showed that the youngest of the group (MER11_G4) had the strongest impact on gene expression. According to the study, this group makes use of regulatory 'motifs'—short stretches of DNA that influence gene development and response. By tracking the evolution of this group, scientists have shown that DNA originally inherited from ancient viruses can actively participate in the form and function of primate DNA. Even though the journey of understanding the human genome is more than 150 years in the making, it still has the remarkable ability to surprise us at seemingly every turn. You Might Also Like Can Apple Cider Vinegar Lead to Weight Loss? Bobbi Brown Shares Her Top Face-Transforming Makeup Tips for Women Over 50 Solve the daily Crossword
