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Does mPER2 protein oscillate without its coding mRNA cycling?: post-transcriptional regulation by cell clock
Yoshito Fujimoto1, Kazuhiro Yagita, Hitoshi Okamura
1Division of Molecular Brain Science, Department of Brain Sciences, Kobe University Graduate School of Medicine, Chuo-ku, Kobe 650-0017, Japan.
Genes to Cells : Devoted to Molecular & Cellular Mechanisms
|April 25, 2006
Summary
The mammalian PER2 protein oscillates without its mRNA cycling, demonstrating post-transcriptional regulation by the internal clock. This occurs independently of mCRY binding, highlighting novel mechanisms in circadian rhythm.
Area of Science:
- Circadian Biology
- Molecular Biology
- Genetics
Background:
- The circadian clock regulates daily rhythms in mammals.
- The molecular basis of circadian rhythmicity involves transcriptional-translational feedback loops.
- The role of post-transcriptional regulation in circadian protein oscillations remains partially understood.
Purpose of the Study:
- To investigate whether the mammalian PER2 protein can oscillate independently of its coding mRNA cycling.
- To determine if mCRY binding is essential for PER2 protein oscillation.
- To explore post-transcriptional mechanisms governing circadian protein rhythms.
Main Methods:
- Generation of stable NIH3T3 fibroblast cell lines expressing exogenous FLAG-tagged full-length mPER2 or a C-terminal deleted form (lacking mCRY binding site).
- Utilized the Flp-In system for stable gene insertion under the human EF-1alpha promoter.
- Monitored mRNA and protein expression rhythms following serum shock induction.
Main Results:
- Exogenously expressed FLAG-mPER2 mRNA did not exhibit cycling, despite endogenous clock induction.
- FLAG-mPER2(full) and FLAG-mPER2(1-1068) proteins demonstrated clear oscillations.
- Protein oscillation of PER2 occurred independently of its mRNA cycling and mCRY binding.
Conclusions:
- The mammalian circadian clock system can regulate mPER2 protein oscillation post-transcriptionally.
- PER2 protein rhythms can be established without concurrent mRNA cycling.
- Direct interaction with mCRY is not a prerequisite for PER2 protein oscillation.
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