Disruption of mCry2 restores circadian rhythmicity in mPer2 mutant mice

Inactivation of the mCry2 gene in mPer2 mutant mice restores circadian rhythmicity.

• Circadian rhythms are regulated by an internal clock located in the suprachiasmatic nuclei (SCN) of the hypothalamus.
• The core oscillator consists of feedback loops involving clock genes, including mPer1, mPer2, mCry1, and mCry2.
• A mutation in the mPer2 gene leads to a gradual loss of circadian rhythms in mice under constant darkness.
• Restoration of circadian rhythmicity occurs with mCry2 inactivation in mPer2 mutant mice, suggesting a suppressive role of mCry2.
• In contrast, inactivation of mCry1 in mPer2 mutant mice causes complete behavioral arrhythmicity in constant darkness.
• These findings indicate that mCry1 and mCry2 have different roles in the circadian clock mechanism.

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