Interconnected Feedback Loops in the Neurospora Circadian System

Mutations in frq can alter the level and timing of WC-1 expression in Neurospora crassa.

• WC-1 is rhythmically expressed from a steady pool of wc-1 transcript, indicating posttranscriptional regulation.
• Driven FRQ expression reduces its own levels while increasing WC-1 synthesis with an approximate 8-hour delay.
• FRQ has dual roles in the Neurospora circadian clock, contributing to a second feedback loop with WC-1.
• This feedback loop may enhance robustness and stability within the circadian system.
• The presence of interlocked loops in Drosophila and mouse suggests such mechanisms could be common in circadian systems.

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