Similar molecular machineries control daily circadian rhythms and developmental timing. Image generated by Kathrin Braun with the assistance of ChatGPT.
November 4, 2025
One clock, two functions: from daily rhythms to development
Scientists at the FMI and the University of California-Santa Cruz have found that similar molecular machineries control daily circadian rhythms and developmental timing. Their work in worms shows that core timing systems can be repurposed through evolution to coordinate both daily cycles and the precise schedule of growth.
Circadian clocks tell our body when to sleep, eat, and wake, while separate developmental clocks control the timing of growth and cell differentiation. Traditionally, these two types of biological timers have been studied separately. Now, a collaboration between the Grosshans lab at the FMI and the Partch and Ward labs at the University of California-Santa Cruz shows that they may share a fundamental molecular machinery.
The discovery centers on LIN-42, a protein in the tiny worm C. elegans that is closely related to the mammalian PER protein, a key component of the circadian clock. While PER tracks daily cycles, LIN-42 orchestrates the worm’s developmental, putting events such as molting on a regular schedule. LIN-42 partners with and gets modified by another protein, KIN-20 — similarly to how PER gets modified by the CK1 protein in mammals. If these interactions are broken, molting schedules become irregular, as do circadian rhythms.
But the work shows that LIN-42 does more than just get modified by KIN-20, it also helps control where KIN-20 is in the cell and how active it is, keeping developmental —and likely circadian — rhythms on track.
By connecting circadian and developmental timing, the findings offer a new perspective on how organisms measure time in different biological contexts, says study co-author Helge Grosshans. “Our work shows how conserved molecular machinery can be repurposed to control both daily rhythms and developmental times,” he says. “Yet not all of the machinery is conserved — so what makes the conserved parts special, and what benefits come from the unique ones? That’s our next question.”
Original publication
Rebecca K. Spangler*, Kathrin Braun*, Guinevere E. Ashley*, Marit van der Does, Daniel Wruck, Andrea Ramos Coronado, James Matthew Ragle, Vytautas Iesmantavicius, Lucas J. Morales Moya, Keya Daly, Carrie L. Partch, Helge Großhans^, and Jordan D. Ward^ A conserved chronobiological complex times C. elegans development EMBO J (2025)
* co-first authors
^ co-corresponding authors
Similar molecular machineries control daily circadian rhythms and developmental timing. Image generated by Kathrin Braun with the assistance of ChatGPT.
About the FMI first author:
Born in Germany, close to the Swiss border, Kathrin Braun has lived there all her life. After high school, she began an apprenticeship as a biology lab technician at Roche in Basel. In 2015, she joined Helge Grosshans’s group at the FMI as a lab manager and later pursued a bachelor’s degree in molecular biology remotely at Johannes Gutenberg University in Mainz while continuing her work in the lab. Married since 2019 to her husband Thomas, she shares her home with two cats, Loui and Cleo. Outside the lab, she enjoys spending time in nature, tending her garden, painting and drawing, restoring old furniture, and exploring flea markets.
