Cellular clocks: circadian rhythms in primary human fibroblasts

摘要

Almost 300 years ago, a French astronomer made the observation that daily leaf movement continues even when a plant is kept in constant darkness (De Mairan 1729). These so-called circadian rhythms exist at all levels of biology, ranging from gene expression to complex behaviours. They are controlled by a cellular clock that has been observed in organisms from all phyla. The underlying molecular mechanism has been described using genetic strategies that identified a set of clock genes that function in a transcriptional regulatory loop (Young and Kay 2001). Mutations in any of these genes can cause disruption in some facet of circadian timing, and micro-array studies suggest that - in complex organisms - most cells are capable of generating circadian oscillations (Panda et al 2002). Thus, circadian clocks are cell-based.