Circadian-associated transcriptional repressor (CIART)

Circadian-associated transcriptional repressor (CIART, also called CHRONO) is a critical component of the mammalian circadian clock. It functions primarily as a transcriptional repressor, rhythmically expressed in opposition to core clock activators like BMAL1 and CLOCK. CIART binds the BMAL1 transcriptional complex and disrupts co-activator recruitment (such as CBP), reducing CLOCK:BMAL1 histone acetylation and thereby attenuating the amplitude and phase of circadian gene expression. This protein not only plays a central role in regulating the negative feedback loop of circadian rhythms but also integrates environmental and physiological signals—such as stress and UV exposure—into the clock mechanism. CIART is implicated in processes like metabolic regulation, especially glucose homeostasis, with perturbation linked to behavioral changes, metabolic pathophysiology, and possibly cancer. Currently, CIART is considered a promising target to understand and potentially modulate circadian biology but lacks direct pharmacological modulators.

Other names

CHRONOC1orf51GM129BC017397circadian associated repressor of transcriptionChIP-derived repressor of network oscillatorComputationally highlighted repressor of the network oscillator

Inhibition or activation of CIART would modulate the repressive effect on CLOCK/BMAL1-regulated transcription. Alteration of circadian gene expression amplitude and phase, potentially impacting metabolism, sleep, and stress response. Epigenetic or posttranslational modification (e.g., histone deacetylase-dependent repression).