Figure 1.

A phase-delaying element and a rhythm-generating element are required for robust cell-autonomous circadian gene expression of Per2. (A) Schematic representation of deletion mutants of the mPer2 promoter. +1 corresponds to the transcription start site. (B) Transcriptional oscillation of mPer2 was monitored by using the cell culture-based luminescent reporter assay. NIH3T3 cells were transfected with the mPer2-luc construct and then stimulated with a high concentration of serum. After the serum shock, in the presence of luciferin, light emission was measured and integrated for 1 min at intervals of 15 min (vertical scale: relative cpm; horizontal scale: 1440 min = 1 d). Peak values of the curves were set to 1. A representative result of three independent experiments is shown. (C) The signals obtained in B were detrended. The time of the first peak was calculated as a phase marker (mean ± SEM; n = 4). (D) Schematic representation of the results obtained from the deletion analysis.