RNA decay protein helps regulate Arabidopsis’s circadian clock

Circadian clocks coordinate biological rhythms, while messenger RNAs (mRNAs) carry instructions from genes for making proteins. A preprint on Arabidopsis reports that the removal of these messages helps regulate the plant’s internal clock. This briefing is based only on the abstract.

The authors report that nearly all core clock genes belong to a group called high-amplitude clock-controlled genes: genes whose RNA levels fluctuate strongly under circadian control. Combining results from multiple transcriptome-wide mRNA decay studies, they found that messages from this group consistently had shorter half-lives, meaning they were cleared relatively quickly.

The researchers also identify DECAPPING PROTEIN 5 (DCP5), an activator of mRNA decapping, as a regulator of circadian RNA stability. Decapping is part of the machinery involved in breaking down mRNA. Using a technique called iCLIP to examine protein–RNA binding, they report that DCP5 preferentially binds messages from high-amplitude clock-controlled genes. These interactions occur at regions rich in the RNA building blocks A and U, within the messages’ 3′ untranslated regions—sections that do not encode protein.

Arabidopsis plants carrying a mutation in the DCP5 gene had a longer circadian period, the authors report, with effects observed at both physiological and molecular levels.

Together, the findings support the authors’ conclusion that RNA decay provides an additional layer of clock regulation after RNA has been produced. The proposed mechanism connects the timing of RNA removal with the pace of the circadian system.