Zombie cells go through a process known as "cryptic transcription," wherein they erroneously make use of DNA snippets to produce small RNA molecules. Scientists may have now discovered why these cells do so.
Zombie Cells
Among the many cells lurking inside the body, zombie cells contribute to diseases linked to aging, such as osteoarthritis, Alzheimer's, and cancer. These cells produce strange and tiny "cryptic" molecules that are typically not observed in normal cells. Live Science notes that the molecules' exact function has remained a mystery. But now, scientists think that they have discovered the reason behind this mysterious molecule production.
As per The Scientist, these cells are scientifically referred to as senescent cells. Despite having hampered cell division, they still continue to persist within the body. Now, Payel Sen, a molecular biologist from the National Institutes of Health's (NIH) National Institute of Aging, and her team have started looking into the epigenetic changes that regulate the mysterious process. Their paper was published in the Nature Aging journal.
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Cryptic Transcription and Cell Aging
While cells typically start reading genes at specific areas in the DNA molecule, in cryptic transcription, cells start reading the middle of the sequence. As a result, the RNA produced is unusually short. Usually, RNA is used by cells to serve as blueprints for protein production and other processes.
The exact purpose of these unusual, cryptic RNA molecules still remains a mystery. Payel Sen notes, however, that she suspects that the tiny molecule production may have ended up consuming the resources of the cell. This, in turn, makes the cell less efficient as it ages over time. Other than this, the cells could also use instructions inside the RNA to produce small proteins that hamper the typical functions of cells.
According to The Scientist, looking into why and how these molecules are produced in aging cells and how they impact the cell itself could have vital implications on the field of longevity and aging. It could help point out if such zombie cells become less efficient over time or produce detrimental tiny proteins. By examining these potential roots, scientists may discover new ways to lengthen youth.
Given this, the scientists went on a journey to look into the "why" of the phenomenon. As part of the study, they were able to point out over 350 cryptic sites, or fragments of genes, from which the unusual RNA molecules were produced in zombie cells. They also noted epigenetic alterations in these specific sites that were not present in healthier and younger cells. This could potentially explain why the process takes place.
Epigenetics generally refers to the molecules that attach themselves to DNA and impact the genes for protein production. Among zombie cells, the epigenetic changes were specifically observed in histones, which are proteins in chromosomes that are like spools and in which DNA is wound around. These epigenetic changes appeared to be linked to the ages of the cells. These changes ended up exposing areas of the genome to the molecule-producers.
In contrast, among younger cells, the same gene fragments remained hidden and stayed unexpressed.
Such findings suggest that zombie cells go through cryptic transcription due to how their capacity for controlled gene expression tends to fade away over time. This is because of the epigenetic changes that build up on their DNA.
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