microRNA-25 as a novel modulator of circadian Period2 gene oscillation

Abstract

Circadian rhythm: microRNAs keep the clock in order A newly identified microRNA plays a key role in fine-tuning the genetic interactions governing the circadian rhythms in mammals, according to researchers in South Korea. Numerous studies have suggested that the Period genes, which negatively regulate the CLOCK and BMAL1 genes to produce a 24-hour feedback loop, may be further modified by microRNAs after they are transcribed. Kyungjin Kim at Daegu Gyeongbuk Institute of Science and Technology, South Korea, and co-workers confirmed that a novel microRNA, miR-25-3p, reduces the expression of a Period gene, Per2, in mice. When miR-25-3p is over-expressed, it dampens and shortens the oscillations of Per2 levels. Interestingly, the researchers showed that natural miR-25-3p expression levels varied across different parts of the brain, supporting the theory that different tissues of the body maintain their own unique circadian cycles.