[Regulation of adipose functions by molecular clocks]

Adipocytes play essential metabolic roles, not only serving as massive energy reserves but also secreting hormones and cytokines that regulate metabolic activities. The link between metabolic activity in adipocytes and circadian rhythm has long been studied, e.g., glucose and lipid homeostasis are well known to exhibit circadian variation. Therefore, molecular clock may play important roles in regulation of metabolic activity in adipocytes. In a previous study, we reported that white adipose tissue contains functional molecular clock and expression of several adipocytokines including leptin and plasminogen activator inhibitor-1 displays circadian rhythm. The diurnal rhythm in the level of these molecules suggests that molecular clock is, at least partly, associated with the onset of metabolic syndrome.