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Updated: Jun 28, 2026
Circadian Entrainment of Drosophila Melanogaster
Published on: June 3, 2020
Drosophila and vertebrate casein kinase Idelta exhibits evolutionary conservation of circadian function
Jin-Yuan Fan1, Fabian Preuss, Michael J Muskus
1Division of Molecular Biology and Biochemistry, University of Missouri, Kansas City, Missouri 64110, USA.
Abstract:
Mutations lowering the kinase activity of Drosophila Doubletime (DBT) and vertebrate casein kinase Iepsilon/delta (CKIepsilon/delta) produce long-period, short-period, and arrhythmic circadian rhythms. Since most ckI short-period mutants have been isolated in mammals, while the long-period mutants have been found mostly in Drosophila, lowered kinase activity may have opposite consequences in flies and vertebrates, because of differences between the kinases or their circadian mechanisms. However, the results of this article establish that the Drosophila dbt mutations have similar effects on period (PER) protein phosphorylation by the fly and vertebrate enzymes in vitro and that Drosophila DBT has an inhibitory C-terminal domain and exhibits autophosphorylation, as does vertebrate CKIepsilon/delta. Moreover, expression of either Drosophila DBT or the vertebrate CKIdelta kinase carrying the Drosophila dbt(S) or vertebrate tau mutations in all circadian cells leads to short-period circadian rhythms. By contrast, vertebrate CKIdelta carrying the dbt(L) mutation does not lengthen circadian rhythms, while Drosophila DBT(L) does. Different effects of the dbt(S) and tau mutations on the oscillations of PER phosphorylation suggest that the mutations shorten the circadian period differently. The results demonstrate a high degree of evolutionary conservation of fly and vertebrate CKIdelta and of the functions affected by their period-shortening mutations.
Insights
Mutations in casein kinase I (CKI) affect circadian rhythms differently in flies and vertebrates. This study reveals conserved functions of CKI in circadian clock mechanisms across species.
Area of Science:
- Chronobiology
- Molecular Biology
- Genetics
Background:
- Circadian rhythms are regulated by protein kinases, including casein kinase I (CKI).
- Mutations in CKI affect circadian period length, with differing effects observed between Drosophila and vertebrates.
- Investigating these differences is crucial for understanding conserved circadian clock mechanisms.
Purpose of the Study:
- To investigate the functional conservation of Drosophila Doubletime (DBT) and vertebrate casein kinase Iepsilon/delta (CKIepsilon/delta) in circadian rhythm regulation.
- To determine if mutations in DBT and CKI have similar effects on circadian period length in flies and vertebrates.
- To elucidate the evolutionary conservation of CKI function in circadian clocks.
Main Methods:
- In vitro kinase assays comparing Drosophila DBT and vertebrate CKI enzymes on period (PER) protein phosphorylation.
- Expression of Drosophila DBT and vertebrate CKIdelta carrying specific mutations in circadian cells of model organisms.
- Analysis of circadian rhythm period length and PER phosphorylation patterns.
Main Results:
- Drosophila dbt mutations affect PER protein phosphorylation similarly by both fly and vertebrate CKI enzymes in vitro.
- Drosophila DBT possesses an inhibitory C-terminal domain and autophosphorylation activity, similar to vertebrate CKIepsilon/delta.
- Expression of mutated DBT or CKIdelta generally leads to short-period circadian rhythms, indicating conserved functions.
- Specific mutations (dbt(L)) show differential effects on circadian period length between Drosophila and vertebrates, suggesting nuanced evolutionary divergence.
Conclusions:
- There is a high degree of evolutionary conservation between fly DBT and vertebrate CKIdelta.
- Period-shortening mutations in CKI affect conserved functions in circadian clock mechanisms.
- While core functions are conserved, specific mutations can lead to species-specific outcomes in circadian rhythm regulation.
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