fetal lung tissue, which the researchers used to measure how gene expression changes as the cells age
Steve Geischmeissner/Science Photo Library
Cellular aging may be linked to genetic errors that arise over time, a discovery that may bring us one step closer to identifying drug targets that slow down the process.
Payal Sen The National Institutes of Health in Maryland previously found that control of gene expression – the process of turning the information that is encoded in a gene into a function – breaks down into yeast and worm cells when they stop dividing but still produce energy, known as senescent cells. in people, previous studies have shown that as we age, the number of senescent cells increases.
To uncover a possible link between impaired gene expression and aging cells in people, Sen and his colleagues took cultured lung cells from a donated human embryo and divided them so many times that they showed signs of aging. Duplicated in three months, mimicking the process of
The team then used a sequencing method called Pro-Cap to analyze the length of newly generated RNA transcripts, which from DNA expression of genes make proteins in the cell.
The researchers found that these embryonic senescent cells gave rise to very few RNA transcripts. These could then fail to make proteins or make proteins that shouldn’t function as they should, says Sen, who hopes to investigate this further in the future.
increased variability in the gene expression that makes up these short transcripts are linked to aging, but we don’t know what’s going on, Sen says.
,[The short transcripts] It could be taking vital energy out of the cell that could be translated into proteins that aren’t useful,” she says. “But in truth, we don’t really know.”
In another part of the experiment, the researchers found similar impaired gene expression in aged liver cells from mice. “The fact that it is conserved in cells from yeast to mouse to human warrants further investigation of the mechanism’s role in aging,” says Sen.
For now, it is unclear whether senescent cells cause aging or whether aging causes cells to become senescent, she says.
“This study shows that the precise control of transcription breaks down with aging,” says Berenice Benayoun at the University of Southern California. She says this could provide us with a new target for drug development to manipulate the aging process.
But “we also need to temper this enthusiasm”, says jeffrey craig at Deakin University in Australia. There are probably several aspects of aging, such as telomere shortening, which occurs when a region of repetitive DNA at the end of a chromosome shortens over time.
“There may be no one-size-fits-all anti-aging intervention,” he says.
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