Genome-wide mapping of Myc, AP4, and phosphorylated RNA polymerase II binding in activated CD8 T cells by ChIP sequencing

The trasncription factor cMyc is an essential transcription factor that establishes a metabolically active and proliferative state in T cells after antigen priming. However, its expression is transient. To date, it remains unknown how T cell activation is maintained after cMyc down-regulation. Here, we identify AP4, encoded by the gene Tfap4, as the transcription factor that is induced by cMyc and sustains activation of antigen-specific CD8+ T cells. Despite normal priming, Tfap4–/– CD8+ T cells fail to continue transcription of a broad range of cMyc gene targets necessary for sustained proliferation. Genome-wide analysis suggests that many activation-induced metabolic genes are shared targets of cMyc and AP4. Thus, AP4 maintains Myc-initiated cellular activation programs in CD8+ T cells to control microbial infections. Overall design: Naive CD8+ T cells from C57BL6 mice were activated with anti-CD3 and anti-CD28 stimulation in vitro for two days and genome-wide occupancy of Myc, AP4 and Ser2 or Ser5 phipsphorylated RNA polymerase II was profiled by chromatin immunoprecipitation and high-throughput sequencing.