The role of clock genes and rhythmicity in the liver.

The liver is the important organ to maintain energy homeostasis of an organism. To achieve this, many biochemical reactions run in this organ in a rhythmic fashion. An elegant way to coordinate the temporal expression of genes for metabolic enzymes relies in the link to the circadian timing system. In this fashion not only a maximum of synchronization is achieved, but also anticipation of daily recurring events is possible. Here we will focus on the input and output pathways of the hepatic circadian oscillator and discuss the recently found flexibility of its circadian transcriptional networks.