Researchers discover cell self-protection against epigenetic changes
The liver can regenerate with age and remain amazingly functional, even though the chromatin in its cells undergoes significant changes due to epigenetic changes, researchers from the Max Planck Institute for Biology of Aging in Cologne have now discovered. Thus they discovered a possible reason why the conversion had almost no consequences.
© Max Planck Institute for Gerontology
The structure of the liver changes with age. Shown here is a histological image of small hepatocytes (left) and hepatocytes (right).
© Max Planck Institute for Gerontology
Changes in epigenetics are considered to be the cause of aging processes. Epigenetics itself describes changes in genetic information that do not change the sequence of the genes themselves, but affect their activity. This can be regulated, among other things, by the accessibility of proteins to DNA.
In this study, researchers in hepatocytes observed that the DNA of liver cells was significantly lower with age. This makes it more accessible to the proteins that bind to DNA and make the messenger molecule RNA. If DNA is accessible, we should also see greater amounts of RNA being synthesized. “This was not at all the case,” explains Peter Tesars, the study’s lead.
Shorter pause on DNA
The researchers directly offer a possible explanation for this. They found that RNA polymerase, a protein that binds to DNA and then makes RNA, drops DNA down faster in aging liver cells than in young cells. This lower stability means that although access to RNA is increased, no more RNA will be produced, and thus homeostasis is maintained within the cell.
“We believe we have discovered a new pathway in cells that compensates for age-related epigenetic changes. This may be a reason for the longevity of the liver. Whether a similar mechanism interferes with epigenetic changes in other tissues remains to be explored in the future. There, however, we also note Completely different genetic changes during aging,” says Tessars.