VRILLE helps regulate daily activity of the Clock gene in fruit fly's internal clock

The gene vrille (vri) is identified as a key repressor of Clk transcription within the Drosophila circadian oscillator.

• The circadian oscillator in Drosophila consists of interlocked feedback loops involving period (per), timeless (tim), and Clock (Clk).
• CLK and CYCLE (CYC) activate the transcription of per and tim while repressing Clk transcription.
• VRI, a gene activated by CLK-CYC, encodes a repressor that targets Clk transcription.
• VRI also represses the blue light photoreceptor gene cryptochrome (cry), indicating its potential role in regulating other rhythmic genes.

Simplified