Light-regulated microRNAs shape dynamic gene expression in the zebrafish circadian clock

Area of Science:

• * Chronobiology and molecular genetics.
• * Vertebrate circadian rhythm research.

Background:

• * Circadian clocks synchronize with the day-night cycle via light input.
• * Zebrafish are a key model for studying light's effect on circadian rhythms.
• * While light-induced transcription is known, post-transcriptional regulation by microRNAs (miRNAs) is less understood.

Purpose of the Study:

• * To investigate if light directly influences miRNA function in zebrafish.
• * To identify light-regulated miRNAs and their mRNA targets.
• * To elucidate the role of miRNAs in light-mediated circadian clock regulation.

Main Methods:

• * Comprehensive sequencing of light-induced changes in zebrafish transcriptome, including mRNAs and small non-coding RNAs.
• * Bioinformatic analysis to identify light-regulated miRNAs and their predicted targets.
• * Luciferase reporter assays to validate miRNA-mRNA interactions.
• * Functional assays using miRNA mimics and inhibitors in zebrafish larvae.

Main Results:

• * Identification of light-regulated miRNAs and their mRNA targets, including circadian clock genes and redox homeostasis genes.
• * Validation of miR-204-3-3p and miR-430a-3p targeting of cryptochrome genes (cry1a, cry1b).
• * Demonstration that these miRNAs affect core clock gene expression and larval locomotor activity.

Conclusions:

• * Light directly regulates specific miRNAs in zebrafish.
• * These light-responsive miRNAs play a significant role in modulating circadian clock gene expression.
• * The findings reveal novel post-transcriptional mechanisms in the multi-level regulation of the circadian clock by light.