GSE51008
Selective transcriptional regulation by Myc in cellular growth control and lymphomagenesis [RNA-Seq]
The c-myc proto-oncogene product, Myc, is a transcription factor that binds thousands of genomic loci. Recent work suggested that rather than up- and down-regulating selected groups of genes, Myc targets all active promoters and enhancers in the genome (a phenomenon termed "invasion") and acts as a general amplifier of transcription. However, the available data did not readily discriminate between direct and indirect effects of Myc on RNA biogenesis. We addressed this issue with genome-wide chromatin immunoprecipitation and RNA expression profiles during B-cell lymphomagenesis in mice, in cultured B-cells and fibroblasts. Consistent with long-standing observations, we detected general increases in total RNA or mRNA copies per cell (hereby termed "amplification") when comparing actively proliferating cells with control quiescent cells: this was true whether cells were stimulated by mitogens (requiring endogenous Myc for a proliferative response) or by deregulated, oncogenic Myc activity. RNA amplification and promoter/enhancer invasion by Myc were separable phenomena that could occur without one another. Moreover, whether or not associated with RNA amplification, Myc drove the differential expression of distinct subsets of target genes. Hence, while having the potential to interact with all active/poised regulatory elements in the genome, Myc does not directly act as a global transcriptional amplifier. Instead, our results imply that Myc activates and represses transcription of discrete gene sets, leading to changes in cellular state that can in turn feed back on global RNA production and turnover. Overall design: Total RNA profiling of gene expression upon Myc regulation in two different cell types by Illumina sequencing