Signaling components that drive circadian rhythms.

In the past year, knowledge of how information is relayed in the regulation of circadian rhythms has advanced considerably. Experiments using genetic knockout animals suggest that circadian photoreception consists of an integration of multiple signaling pathways. Versatility of clock proteins is seen in terms of their function in the central pacemakers versus the periphery. This versatility also extends to previously identified molecules, such as retinoid receptors, redox factors and mitogen-activated protein kinase, that have newly identified roles in circadian signaling pathways. Advances in circadian research over the past year include the common themes of redundancy and plasticity.