Authors: Miller BH; McDearmon EL; Panda S; Hayes KR; Zhang J; Andrews JL; Antoch MP; Walker JR; Esser KA; Hogenesch JB; Takahashi JS
Abstract: Circadian rhythms of cell and organismal physiology are controlled by an autoregulatory transcription-translation feedback loop that regulates the expression of rhythmic genes in a tissue-specific manner. Recent studies have suggested that components of the circadian pacemaker, such as the Clock and Per2 gene products, regulate a wide variety of processes, including obesity, sensitization to cocaine, cancer susceptibility, and morbidity to chemotherapeutic agents. To identify a more complete cohort of genes that are transcriptionally regulated by CLOCK and/or circadian rhythms, we used a DNA array interrogating the mouse protein-encoding transcriptome to measure gene expression in liver and skeletal muscle from WT and Clock mutant mice. In WT tissue, we found that a large percentage of expressed genes were transcription factors that were rhythmic in either muscle or liver, but not in both, suggesting that tissue-specific output of the pacemaker is regulated in part by a transcriptional cascade. In comparing tissues from WT and Clock mutant mice, we found that the Clock mutation affects the expression of many genes that are rhythmic in WT tissue, but also profoundly affects many nonrhythmic genes. In both liver and skeletal muscle, a significant number of CLOCK-regulated genes were associated with the cell cycle and cell proliferation. To determine whether the observed patterns in cell-cycle gene expression in Clock mutants resulted in functional dysregulation, we compared proliferation rates of fibroblasts derived from WT or Clock mutant embryos and found that the Clock mutation significantly inhibits cell growth and proliferation.Keywords: Animals; CLOCK Proteins; Cell Cycle/genetics; *Cell Proliferation; Cells, Cultured; Circadian Rhythm/*genetics; Feedback, Physiological/*genetics; Gene Expression Profiling; *Gene Expression Regulation; Liver/metabolism; Mice/*genetics; Muscle, Skeletal/metabolism; Oligonucleotide Array Sequence Analysis; Reverse Transcriptase Polymerase Chain Reaction; Trans-Activators/*genetics
Journal: Proceedings of the National Academy of Sciences of the United States of America
Date: March 16, 2007
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Miller BH, McDearmon EL, Panda S, Hayes KR, Zhang J, Andrews JL, Antoch MP, Walker JR, Esser KA, Hogenesch JB, Takahashi JS (2007) Circadian and CLOCK-controlled regulation of the mouse transcriptome and cell proliferation. Proceedings of the National Academy of Sciences of the United States of America 104: 3342-7.