Two Ck1δ transcripts regulated by m6A methylation code for two antagonistic kinases in the control of the circadian...

Area of Science:

• Molecular Biology
• Chronobiology
• Epigenetics

Background:

• N6-methylation of adenosine (m6A) is a prevalent mRNA modification, but its functional significance in many transcripts remains unclear.
• The circadian clock, a fundamental biological process, is known to be sensitive to global m6A levels.
• Casein Kinase 1 Delta (CK1δ) is crucial for circadian rhythms, cellular growth, and survival.

Purpose of the Study:

• To investigate the role of m6A in regulating Casein Kinase 1 Delta mRNA (Ck1δ).
• To characterize the functional consequences of Ck1δ mRNA methylation on protein isoforms and their impact on the circadian clock.

Main Methods:

• Quantification and localization of m6A in the transcriptome.
• Analysis of Ck1δ mRNA methylation inhibition.
• Assessment of alternatively spliced CK1δ isoform expression and activity.
• Investigation of PER2 protein phosphorylation by CK1δ isoforms.

Main Results:

• Ck1δ mRNA is negatively regulated by m6A.
• Inhibition of Ck1δ mRNA methylation increases the translation of two novel isoforms: CK1δ1 and CK1δ2.
• CK1δ1 and CK1δ2 exhibit distinct kinase activities and tissue-specific expression ratios.
• CK1δ1 accelerates the circadian clock by promoting PER2 decay, while CK1δ2 slows it by stabilizing PER2 through phosphorylation.

Conclusions:

• m6A-mediated regulation of Ck1δ mRNA generates functionally distinct isoforms.
• The opposing actions of CK1δ1 and CK1δ2 on PER2 phosphorylation necessitate a re-evaluation of established circadian clock models.
• The discovery of these isoforms highlights the complexity of CK1δ function and its regulation.