PDF Signaling Is a Key Part of the Internal Molecular Clock in Fruit Flies

A reciprocal negative regulation was identified between the master circadian regulator CLK and the expression of the neuropeptide pdf.

• Circadian clocks influence 24-hour rhythms in physiology and behavior.
• The study used fluorescent transcriptional reporters in a Drosophila brain culture system.
• PDF feedback is needed to maintain normal oscillation patterns in CLK-driven transcription.
• CLK and neuronal firing may suppress pdf transcription through shared transcription factors DHR38 and SR.
• Evidence suggests an uncharacterized feedback loop between CLK and PDF connects molecular oscillators with the circadian neuronal network.

Simplified