summary: Researchers studying the molecular mechanisms of our circadian clock have made significant progress identifying key interactions that control the timing of our circadian clock.
The findings provide important insights into Familial Advanced Sleep Phase Syndrome (FASP), which is caused by genetic mutations that accelerate the body clock, resulting in 20-hour cycles instead of 24-hour cycles.
This mutation disrupts the interaction between the core clock protein period and the enzyme, creating an imbalance and shortening the clock cycle. This finding may pave the way for potential treatments for FASP and other sleep disorders.
Important facts:
- In this study, the interaction between the Period protein and an enzyme (casein kinase 1) was identified as a key determinant in the timing of the circadian clock.
- Mutations in Familial Advanced Sleep Phase Syndrome (FASP) shorten the clock cycle, causing people to work in 20-hour cycles instead of the usual 24-hour cycles.
- The researchers suggest that the newly discovered interactions could be potential targets for therapeutic intervention, thus opening the way to treating not only FASP but also other sleep cycle disruptions. .
sauce: University of California, Santa Cruz
Molecular clocks within our cells synchronize our bodies to the day and night cycle, signal sleep and wakefulness, and drive the daily cycle in nearly every aspect of physiology.
Scientists studying the molecular mechanisms of our body clock have identified key events that control the timing of the clock.
The new findings were published on May 18th. molecular cellrevealing important details of the molecular interactions that are disrupted in people with an inherited sleep disorder called familial sleep phase progression syndrome (FASP).
The syndrome is caused by a mutation in a gene that shortens the timing of the clock, causing people’s internal clocks to run on a 20-hour cycle, out of sync with the Earth’s 24-hour cycle, causing people to experience extreme “morning skylarks”. It’s going to be.
“It’s like permanent jet lag because your body clock never catches up with the day length,” says Carrie Purch, corresponding author and professor of chemistry and biochemistry at the University of California, Santa Cruz.
“The FASP mutation was discovered 20 years ago and we knew it would have a big impact, but we didn’t know how or why.”
FASP mutations affect one of the core clock proteins called Period, altering a single amino acid within the protein’s structure.
A new study shows how this one change interferes with the interaction of the Period protein with a kinase enzyme (casein kinase 1), making the Period protein less stable and shortening a critical step in the clock cycle. showing.
Lead author Jonathan Philpott, a postdoctoral fellow in the Perch lab at UCSC, says that kinase enzymes control Period by attaching phosphate groups, a process called phosphorylation, and that they can do this. I explained that there are two different parts of a protein that can be
Phosphorylation of the ‘degron’ region tags the Period protein for degradation, whereas phosphorylation of the FASP region stabilizes it.
The balance between degradation and stabilization determines clock cycle length, but mutations in FASP tip the balance towards degradation of Period and shortening of the cycle.
“Having this FASP mutation shortens the clock by about four hours,” says Philpott.
A key finding of the new study is that the phosphorylated FASP domain inhibits kinase activity. This feedback-inhibitory mechanism allows period to effectively modulate its own regulators, delaying phosphorylation of the degron region and prolonging the cycle.
“Without this pause button, you would have to slow down a very fast biochemical reaction,” Perch said.
The researchers showed that this inhibition is caused by the binding of the phosphorylated FASP domain to specific sites on the kinase, which may be targeted by drugs.
“You can start thinking of this as an adjustable system,” says Philpott. “We have identified regions on the kinase that could potentially be targeted to modulate its activity for therapeutic use.”
Perch pointed out that most drugs that target kinases work by blocking the enzyme’s active site.
“It’s basically a hammer that shuts off kinase activity,” she says. “However, the discovery of a new pocket unique to this kinase allows us to target them and modulate their activity in a more controlled manner.”
This could be helpful not only for people with advanced familial sleep phase syndrome, but also for those whose sleep cycles are disrupted by shift work, jet lag, and other challenges of modern society.
Another surprising finding in the new study is that feedback inhibition of kinase enzymes by period proteins also occurs in Drosophila, despite different phosphorylation sites.
“This short cycle mutant was found to be DrosophilaDiscovered in 1970, this mutation mimics the human short-cycle FASP mutation,” Perch said.
“This mechanism is thought to have existed throughout the evolution of multicellular animals. suggesting.”
Pertsch and Philpott said their collaboration with several laboratories at other institutions has allowed them to go beyond experimental observation to study clock mechanisms from different angles.
This study included NMR spectroscopy, molecular dynamics simulations, the use of genetically engineered human cell lines, as well as the characterization of the same molecular mechanisms in humans and humans. Drosophila Drosophila.
“It was a great collaborative team,” said Perch.
In addition to Philpott and Partch, co-authors include Alfred Freeberg, Sabrina Hunt, David Segal, Rafael Robles, and Sarvind Tripathi from UC Santa Cruz. Jiyoung Park, Kwangjun Lee, and Choogon Lee from Florida State University. Clarice Rich and Andrew McCammon of the University of California, San Diego. Rajesh Narasimamurthy and David Virshap of Duke NUS Medical College, Singapore. Yao Cai and Joanna Qiu of the University of California, Davis.
Funding: This study was funded by the US National Institutes of Health and the Singapore Ministry of Health.
About this Circadian Rhythm Research News
author: Tim Stevens
sauce: University of California, Santa Cruz
contact: Tim Stevens – University of California, Santa Cruz
image: Image credited to Neuroscience News
Original research: open access.
“PERIOD phosphorylation causes feedback inhibition of CK1 activity and regulates circadian cyclingBy Carrie Partch et al. molecular cell
overview
PERIOD phosphorylation causes feedback inhibition of CK1 activity and regulates circadian cycling
highlight
- CK1delta phosphorylates the familial late sleep (FASP) domain of human PER2
- FASP phosphorylation causes feedback inhibition of kinases
- Substrate immobilization increases phosphorylation kinetics and product inhibition.
- mammals and Drosophila Clocks share a conserved mechanism of feedback inhibition
summary
PERIOD (PER) and casein kinase 1delta regulate circadian rhythms through phosphate switches that control the stability of PER and the inhibitory activity of the molecular clock. CK1δ phosphorylation of the familial late sleep (FASP) serine cluster embedded within the casein kinase 1-binding domain (CK1BD) of mammalian PER1/2 inhibits its activity on phosphodegrons to stabilize PER and regulate circadian rhythms. Extend.
Here we show that the phosphorylated FASP domain (pFASP) of PER2 directly interacts with and inhibits CK1δ. Co-crystal structures combined with molecular dynamics simulations reveal how pFASP phosphoserine docks into a conserved anion-binding site near the active site of CK1δ. Limiting phosphorylation of the FASP serine cluster reduces product inhibition, decreases PER2 stability, and shortens the circadian cycle in human cells.
we found it Drosophila PER also regulates CK1delta through feedback inhibition through the phosphorylated PER-Short domain, revealing a conserved mechanism by which PER phosphorylation near CK1BD regulates CK1 kinase activity.
