The Use of Chemical Compounds to Identify the Regulatory Mechanisms of Vertebrate Circadian Clocks

Circadian clocks are intrinsic, time-tracking processes that confer a survival advantage on an organism. Under natural conditions, they follow approximately a 24-h day, modulated by environmental time cues, such as light, to maximize an organism’s physiological efficiency. The exact timing of this rhythm is established by cell-autonomous oscillators called cellular clocks, which are controlled by transcription–translation negative feedback loops. Studies of cell-based systems and wholeanimal models have utilized a pharmacological approach in which chemical compounds are used to identify molecular mechanisms capable of establishing and maintaining cellular clocks, such as posttranslational modifications of cellular clock regulators, chromatin remodeling of cellular clock target genes’ promoters, and stability control of cellular clock components. In addition, studies with chemical compounds have contributed to the characterization of light-signaling pathways and their impact on the cellular clock. Here, the use of chemical compounds to study the molecular, cellular, and behavioral aspects of the vertebrate circadian clock system is described.