Related Experiment Video

Updated: Dec 22, 2025

In Vitro Bioluminescence Assay to Characterize Circadian Rhythm in Mammary Epithelial Cells
11:56

In Vitro Bioluminescence Assay to Characterize Circadian Rhythm in Mammary Epithelial Cells

Published on: September 28, 2017

10.3K

Mutation of a PER2 phosphodegron perturbs the circadian phosphoswitch

Shusaku Masuda1, Rajesh Narasimamurthy2, Hikari Yoshitane1

  • 1Department of Biological Sciences, School of Science, The University of Tokyo, 113-0033 Bunkyo-ku, Tokyo, Japan.

Proceedings of the National Academy of Sciences of the United States of America
|May 2, 2020
PubMed

Insights

Casein kinase 1 (CK1) phosphorylation of PER2 protein is crucial for circadian clock regulation. Disrupting this process in mice extended their circadian period, confirming its in vivo importance.

Area of Science:

  • Chronobiology
  • Molecular Biology
  • Genetics

Background:

  • Casein kinase 1 (CK1) regulates the mammalian circadian clock, primarily through PER2 protein phosphorylation and degradation.
  • The role of core circadian machinery degradation in clock regulation has been debated.
  • CK1 phosphorylation of PER2 at Ser478 creates a phosphodegron, recruiting β-TrCP for degradation, a process linked to temperature compensation.

Purpose of the Study:

  • To investigate the in vivo significance of the PER2 phosphodegron in regulating circadian period.
  • To provide direct evidence for the role of phosphorylation-regulated PER2 stability in the mammalian circadian clock.

Main Methods:

  • Generation and behavioral analysis of PER2-Ser478Ala knock-in mice.
  • Molecular analysis of PER2 protein levels and localization in mouse liver.
  • Assessment of circadian period properties, including three-phase decay and temperature compensation, in mouse embryonic fibroblasts.

Main Results:

  • PER2-Ser478Ala knock-in mice exhibited a significantly longer circadian period.
  • Mutant PER2 protein accumulated in the nucleus and cytoplasm of liver cells, with minimal changes in Per2 mRNA levels.
  • Increased nuclear levels of PER1, CRY1, and CRY2 were observed, suggesting stabilization of PER2-containing complexes.
  • Perturbations in three-phase decay and temperature compensation were noted in mutant mouse embryonic fibroblasts.

Conclusions:

  • Phosphorylation-regulated PER2 stability is critical for the in vivo function of the mammalian circadian clock.
  • The study validates the role of the PER2 phosphodegron and associated phosphoswitch mechanism in a mouse model.
  • These findings underscore the importance of protein degradation pathways in maintaining circadian rhythmicity.
Keywords:
Period2circadian clockknock-in mousephosphorylationtemperature compensation

More Related Videos

Rapid Analysis of Circadian Phenotypes in Arabidopsis Protoplasts Transfected with a Luminescent Clock Reporter07:42

Rapid Analysis of Circadian Phenotypes in Arabidopsis Protoplasts Transfected with a Luminescent Clock Reporter

Published on: September 17, 2016

13.2K
Analysis of Circadian Photoresponses in Drosophila Using Locomotor Activity00:08

Analysis of Circadian Photoresponses in Drosophila Using Locomotor Activity

1.5K

Related Concept Videos

Circadian Rhythms and Gene Regulation02:19

Circadian Rhythms and Gene Regulation

The biological clock is involved in many aspects of regulating complex physiology in all animals. It was in 1935 when German zoologists, Hans Kalmus and Erwin Bünning, discovered the existence of circadian rhythm in Drosophila melanogaster. However, the internal molecular mechanisms behind the circadian clock remained a mystery until 1984, when Jeffrey C. Hall, Michael Rosbash, and Michael W. Young discovered the expression of the Per gene oscillating over a 24-hour cycle. In subsequent...
4.4K
Phosphorylation01:02

Phosphorylation

The addition or removal of phosphate groups from proteins is the most common chemical modification that regulates cellular processes. These modifications can affect the structure, activity, stability, and localization of proteins within cells as well as their interactions with other proteins.
During phosphorylation, protein kinases transfer the terminal phosphate group of ATP to specific amino acid side chains of substrate proteins. Serine, threonine, and tyrosine are the most commonly...
53.4K
Position-effect Variegation02:32

Position-effect Variegation

In 1928, a German botanist Emil Heitz observed the moss nuclei with a DNA binding dye. He observed that while some chromatin regions decondense and spread out in the interphase nucleus, others do not. He termed them euchromatin and heterochromatin, respectively. He proposed that the heterochromatin regions reflect a functionally inactive state of the genome. It was later confirmed that heterochromatin is transcriptionally repressed, and euchromatin is transcriptionally active chromatin.
6.9K
Amplifying Signals via Enzymatic Cascade01:22

Amplifying Signals via Enzymatic Cascade

When a ligand binds to a cell-surface receptor, the receptor's intracellular domain changes shape, which may either activate its enzyme function or allow its binding to other molecules. The initial signal is amplified by most signal transduction pathways. This means that a single ligand molecule can activate multiple molecules of a downstream target. Proteins that relay a signal are most commonly phosphorylated at one or more sites, activating or inactivating the protein. Kinases catalyze...
16.7K
Abnormal Proliferation02:23

Abnormal Proliferation

Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the...
5.0K
Background and Environment Affect Phenotype02:27

Background and Environment Affect Phenotype

Although the genetic makeup of an organism plays a major role in determining the phenotype, there are also several environmental factors, such as temperature, oxygen availability, presence of mutagens, that can alter an organism’s phenotype.
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
7.3K