Challenges in synthetically designing mammalian circadian clocks

Synthetic biology, in which complex, dynamic biological systems are designed or reconstructed from basic biological components, can help elucidate the design principles of such systems. However, this engineering approach has only been applied to a few simple biological systems. The circadian clock is appropriate for this approach, since it is a dynamic system with complex transcriptional and post-transcriptional circuits that have been comprehensively described. Rational synthesis of the properties of the suprachiasmatic nucleus, the central clock tissue of the circadian system that controls many dynamic behaviors, will be important for understanding the neural-circuit systems that control physiological behaviors. These approaches will provide a deeper understanding of the biological clock, and of clinical problems associated with it, such as sleep disorders.