"Zombie cells" that hide in the body and contribute to age-related diseases produce
The peculiarity of “zombie cells” is that theydo not die, but stop dividing due to damage or stress. Some studies show they help repair damaged tissue. But as the body ages, these zombies begin to accumulate and cause inflammation, which contributes to age-related diseases such as cancer, Alzheimer's disease and osteoarthritis.
According to The Scientist, in additionBy releasing inflammatory molecules, the “zombie cells” undergo a process scientists call “cryptic transcription.” Cells mistakenly use ultra-short fragments of DNA—simple fragments of genes—to build tiny molecules of RNA, a molecular relative of deoxyribonucleic acid. Cells typically use RNA as blueprints to make proteins, among other things.
And usually cells read genes, startingfrom certain sections of the DNA molecule (as a capital letter marks the beginning of a sentence, and a period marks its end). Genes also have the same starting and ending points. However, with hidden transcription, cells can read the DNA “sentence” from the middle. As a result, the cell produces an unusually short RNA molecule.
The exact function of these cryptic RNAs remainsunknown. However, Payel Sen, a molecular biologist at the Institute on Aging at the National Institutes of Health, suspects that the production of these small molecules depletes the cell's resources, causing it to grow less efficiently as it ages. Additionally, the cell can use the instructions inside the RNA to create tiny proteins that somehow interfere with the cell's normal functions.
Studying why zombie cells undergoThe mysterious transcription and how it affects aging will help scientists better understand the aging process, as well as prolong life and prevent age-related diseases.
The team identified more than 350 “mysteriousareas" in aging human cells. This means that they identified the gene fragments that make up the “strange” RNAs. They also identified "epigenetic" changes in these regions that were not present in young, healthy cells. Scientists are confident that they can explain the reasons for hidden transcription.
Epigenetic changes observedin zombie cells were especially noticeable in histones—the protein “coils” on chromosomes around which DNA is wound. And scientists associated these changes with the age of the cells. In “zombie cells,” these epigenetic changes exposed parts of the genome to the cell's RNA production machinery. And in the young, the same gene fragments were “hidden” and, therefore, were not expressed.
The new discovery supports the idea thatZombie cells undergo latent transcription because their ability to control gene expression declines over time due to the accumulation of epigenetic changes in their DNA.
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Cover image: Flickr by arbyreed
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