[The roles of clock genes in obesity]

Several epidemiological studies have suggested that the perturbation of circadian rhythm has adverse metabolic consequences (e.g., obesity) in humans. At the molecular level, circadian rhythms are encoded by an autoregulatory loop composed of a set of transcription activators (BMAL1/CLOCK) that induce expression of repressors (PER/CRY). The mammalian molecular clock is not only expressed within the master suprachiasmatic nucleus pacemaker neurons, but also within nearly all cells. In addition to this core loop, BMAL1/CLOCK also induce expression of the orphan nuclear hormone receptor, which modulates Bmal1 transcription. Disruption of clock genes results in metabolic dysregulation in mice. In this article, the roles of clock genes in the regulation of metabolism were summarized based on the phenotypes of the knockout mice.