The Zebrafish Period2 Protein Positively Regulates the Circadian Clock through Mediation of Retinoic Acid Receptor (RAR)-related Orphan Receptor α (Rorα)

Zebrafish circadian clock gene per2 is essential for maintaining normal activity rhythms.

• Mutant zebrafish lacking per2 exhibit reduced activity levels in light-dark conditions and a 2-hour delay in activity under constant darkness.
• Analysis shows up-regulation of cry1aa, cry1ba, cry1bb, and aanat2, alongside down-regulation of per1b, per3, and bmal1b in per2 mutants.
• Per2 is indicated to play dual roles by repressing aanat2 expression and enhancing bmal1b expression via specific genetic elements.
• Evidence suggests that Per2 enhances bmal1b expression by binding to the orphan nuclear receptor Rorα.
• Mouse PER2 also influences Bmal1 transcription through RORα, despite its binding to REV-ERBα.
• Per2 appears to have tissue-specific regulatory functions across various peripheral organs in zebrafish.

AI simplified