Broad Epigenetic Shifts In The Aging Drosophila Retina Contribute To Its Altered Diurnal Rhythmic Transcriptome
Our bodies, and even the tiny fruit fly, operate on a daily schedule, with many genes turning on and off in a rhythmic fashion to manage everything from sleep to metabolism. This internal timing system, often called the circadian rhythm, is crucial for health. However, as we age, these daily rhythms can go awry, contributing to various age-related problems, especially in vital organs like the eye.
Recent research sheds light on why these daily gene expression patterns change with age in the retina, the light-sensing part of the eye. Scientists found that in aging fruit flies, the problem isn’t with the central “clock” genes that keep time. Instead, the issue lies in widespread changes to how DNA is packaged within cells. Think of DNA as a long instruction manual; it’s wrapped around proteins called histones. Chemical tags, like methyl groups, attach to these histones and act like dimmer switches, controlling how easily genes can be read.
The study revealed that as flies age, there’s a general decrease in these specific chemical tags (histone H3K4 methylation) across the entire genome in retinal cells. These changes in “epigenetic” tags directly impact the timing of gene activity. In fact, when researchers artificially reduced these tags in young flies, their gene rhythms started to look like those of older flies. This suggests that these broad changes in DNA packaging play a significant role in disrupting the retina’s daily gene activity patterns during aging, even when the core biological clock is still ticking away normally.
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