{"id":1137,"date":"2021-01-05T05:03:57","date_gmt":"2021-01-05T05:03:57","guid":{"rendered":"https:\/\/www.diabetesasia.org\/magazine\/?p=1137"},"modified":"2025-03-24T10:56:07","modified_gmt":"2025-03-24T05:26:07","slug":"junk-dna-role-in-regulating-circadian-rhythms","status":"publish","type":"post","link":"https:\/\/www.diabetesasia.org\/magazine\/junk-dna-role-in-regulating-circadian-rhythms\/","title":{"rendered":"Junk DNA Role in Regulating Circadian Rhythms"},"content":{"rendered":"

 <\/p>\n

\n
\n
\n

Summary: <\/strong>Researchers reveal the role hundreds of miRNAs appear to play in modulating circadian rhythm.<\/em><\/p>\n

Source:\u00a0<\/strong>USC<\/em><\/p>\n

If you\u2019ve ever had a bad case of jet lag, you know how a disruption to your body\u2019s circadian rhythm makes it difficult to function. Molecular circadian \u201cclocks\u201d exist in cells throughout the body, governing more than just sleep and wake cycles \u2013 they are crucial to many aspects of human health. For more than a decade researchers have been trying to figure out what makes them tick, in search of new insights into diseases like Alzheimer\u2019s, cancer, and diabetes.<\/strong><\/p>\n

Until now, that research has focused on what is known as clock genes, which encode proteins that drive oscillating cycles of gene expression affecting physiology and behavior. But research just published in the\u00a0Proceedings of the National Academy of Sciences<\/em> reveals the discovery of a new cog in the circadian clock \u2013 a genome-wide regulatory layer made up of small chains of non-coding nucleotides known as micro RNAs (miRNAs).<\/p>\n

\u201cWe\u2019ve seen how the function of these clock genes is really important in many different diseases,\u201d said Steve Kay, Provost Professor of neurology, biomedical engineering, and quantitative computational biology at the Keck School of Medicine of USC. \u201cBut what we were blind to was a whole different funky kind of genes network that also is important for circadian regulation and this is the whole crazy world of what we call non-coding microRNA.\u201d<\/p>\n

\n
\n

\"Junk<\/p>\n

\u201cJunk DNA\u201d proves to be a valuable tool in circadian rhythms<\/strong><\/div>\n<\/div>\n<\/div>\n

Formerly thought to be \u201cjunk DNA,\u201d miRNAs are now known to affect gene expression by preventing messenger RNA from making proteins. Past research has indicated miRNAs may have a role in the function of circadian clocks but determining which of the hundreds of miRNAs in the genome might be involved remained a problem.<\/p>\n

Kay and his team, led by Lili Zhou, a research associate in the Keck School\u2019s Department of Neurology, turned to the Genomics Institute of the Novartis Research Foundation (GNF) in San Diego which has created robots capable of high throughput experiments. Working with scientists at the institute, Zhou developed a high throughput screen for a robot to test close to 1000 miRNAs by individually transferring them into cells the team had engineered to glow on and off, based on the cell\u2019s 24-hour circadian clock cycle.<\/p>\n

\u201cThe collaboration with GNF made it possible for us to conduct the first cell-based, genome-wide screening approach to systematically identify which of the hundreds of miRNAs might be the ones modulating circadian rhythms,\u201d said Zhou.<\/p>\n

\u201cMuch to our surprise,\u201d said Kay, \u201cwe discovered about 110 to 120 miRNAs that do this.\u201d<\/p><\/blockquote>\n

With the help of Caitlyn Miller, a biochemistry undergraduate from USC Dornsife, researchers then verified the impact on circadian rhythms by inactivating certain miRNAs identified by the screen in their line of glowing cells. Knocking out the miRNAs had the opposite effect on the cells\u2019 circadian rhythm as adding them to the cells.<\/p>\n

Physiologic and behavioral impacts of miRNAs<\/strong><\/p>\n

Junk, DNA, Circadian, Rhythms<\/strong><\/p>\n

Researchers also focused on the physiologic and behavioral impacts of miRNAs. They analyzed the behavior of mice with a particular cluster of miRNAs inactivated \u2013 miR 183\/96\/182 \u2013 and saw that inactivating the cluster interfered with their wheel-running behavior in the dark compared with control mice. They then examined the impact of the miRNA cluster on the brain, retina, and lung tissue, and found that inactivating the cluster affected circadian rhythms differently in each tissue type \u2013 suggesting that the way the miRNAs regulate the circadian clock is tissue-specific.<\/p>\n

\"This
Past research has indicated miRNAs may have a role in the function of circadian clocks but determining which of the hundreds of miRNAs in the genome might be involved remained a problem. The image is in the public domain.<\/figcaption><\/figure>\n

Understanding the impact of miRNAs on the circadian clock in individual tissue could reveal new ways of treating or preventing specific diseases.<\/p>\n

\n
\n