Junk DNA: goodbye!: transposons h ave aging function (Introduction)

by David Turell , Wednesday, August 19, 2020, 23:04 (1557 days ago) @ David Turell

More DNA so-called 'junk' found to function in aging:

https://phys.org/news/2020-08-clues-aging-junk-dna.html

"Tom LaRocca, an assistant professor in the Department of Health and Exercise Science and faculty member in the Columbine Heath Systems Center for Healthy Aging at CSU, led the study to investigate a growing body of evidence that repetitive elements—transposons and other sequences that occur in multiple copies in the human genome—may become active over time as we age.

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"To carry out the study, the researchers began by analyzing an existing RNA sequencing dataset gathered from skin cells in healthy human subjects aged 1-94 years old. Just as the Human Genome Project of the 1990s sought to sequence and map the approximately 20,500 genes in human DNA, RNA sequencing can provide a map of the entire transcriptome in the cells under study. From that analysis, which was all computational, the researchers found that transcripts from most major types of repetitive elements were increased in older subjects.

"In a second wave of study, the researchers verified their initial findings by performing their own lab analyses on skin cells from a biobank. Using fluorescent microscopy, the researchers tagged the transcript of a specific transposon, Charlie5, to see how it fluctuates with the age of cells: the brighter the tag appears under the microscope, the more Charlie5 transcript is detectable.

"As hypothesized, skin cells from older adults revealed a marked accumulation of Charlie5 transcript compared to cells from younger individuals, showing that repetitive element RNAs appear to accumulate with age.

"While an important observation, the grander outcome of this study is that repetitive RNA transcripts might be linked with biological age, or the health of a person's cells, as opposed to chronological age in years.

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"A link between repetitive element transcripts and biological age was further confirmed by studying skin cells from patients with Hutchinson-Gilford progeria syndrome (HGPS), a premature aging syndrome, and by studying an RNA-sequencing dataset from the roundworm Caenorhabditis elegans.

"Why might repetitive element transcripts increase with age? The researchers suspect that chromatin—the complex of DNA and protein in cells that typically represses repetitive elements from being expressed—might become disrupted, allowing for the transcription of repetitive elements.

"All in all, for a portion of the genome that scientists used to ignore, evidence is growing that noncoding RNAs and repetitive elements play vital roles in regulating the rest of the human genome, and in this case, as potentially targetable biomarkers of aging.

"'This is a really big chunk of the genome that, for the longest time, no one really knew what it did, so they just kind of assumed it was junk. But we're finding more and more that these noncoding regions might not only be doing something, but they might have actual health implications," Cavalier said."

Comment: As more and more DNA is found to function, the stronger the evidence for design.