The circadian transcriptional landscape in primary human mammary epithelial cells. Homo sapiens

Cells in peripheral tissue maintain a cell-autonomous molecular clock which is regulated through transcription-translation feedback mechanisms initiated by a core set of circadian proteins. Among these clock proteins are transcription factors and histone modifying enzymes which act in trans to influence the expression of a broad array of clock-controlled genes (CCGs). The CCG set, defined as transcripts with cyclic expression approximating a 24h period, is tissue-specific, such that the circadian transcriptome can only be assembled through experiments conducted in the cell type of interest. Here, we describe for the first time the circadian transcriptome in primary human mammary epithelial cells using time-series massively parallel sequencing. We also show that clinical instruments relying on gene expression, such as molecular subtyping and RNA-based predictive or prognostic biomarkers, provide measurements that are variable across circadian time. This data represents a valuable resource for advancing our understanding of the molecular underpinnings of circadian rhythm. Overall design: mRNA profiles of temperature synchronized (non-immortalized) human breast epithelial cells isolated from a 28 year-old woman undergoing breast reduction mammoplasty. The experiment was carried out over a 24-hour time period in duplicate and the samples were analyzed using the Illumina HiSeq 2000.