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Transcriptional Regulation by Mediator Kinases during Starvation or Proliferation
Author(s) -
Rubin Jonathan D.,
Dowell Robin D.,
Taatjes Dylan J.
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.756.5
Subject(s) - mediator , cyclin dependent kinase 8 , rna polymerase ii , biology , kinase , transcription (linguistics) , transcriptional regulation , microbiology and biotechnology , transcription factor , promoter , gene , cancer research , genetics , gene expression , notch signaling pathway , linguistics , philosophy
The objective of this research is to better understand the role of Mediator kinase activity in transcriptional regulation. Mediator is a multi‐subunit protein complex necessary for regulated transcription of all RNA polymerase II (RNAPII) transcripts. Mediator kinases (CDK8 and CDK19) form 4 subunit modules which reversibly associate with Mediator affecting transcription in poorly understood ways. Overexpression of CDK8 has been shown to correlate with tumor aggressiveness and mortality in colorectal cancer patients and the kinase activity of CDK8 and CDK19 promotes proliferation of acute myeloid leukemia in cells and in vivo . The kinase activity associated with these enzymes and how this relates to transcriptional regulation is not well understood because specific inhibitors of Mediator kinase activity have only recently been discovered. The study of genome‐wide phenomena has been aided greatly by the development of next generation sequencing. A recent sequencing technique, global run‐on with sequencing (GRO‐Seq), measures genome‐wide nascent transcription and allows for the unprecedented characterization of general transcription machinery. Serum response facilitates the study of transcriptional regulation by coordinating cells and increasing transcription at known genes involved in serum response. We performed GRO‐Seq on cells during serum response with and without the specific Mediator kinase inhibitor Cortistatin A (CA). Preliminary results show that qualitatively, genes involved in serum response have increased GRO‐Seq read counts at initiation regions following Mediator kinase inhibition. RNAPII pausing as determined by a pausing index is significantly increased following CA treatment for a large number of genes. Gene ontology (GO) enrichment analysis revealed that these paused genes are associated with metabolic processes. Additionally, this dataset was analyzed using a newly developed technique which detects eRNAs from GRO‐Seq datasets and measures transcription factor (TF) motif enrichment at eRNA epicenters. We found that MNT was significantly more enriched at eRNAs following Mediator kinase inhibition with CA. MNT is a known antagonist of MYC, a major downstream effector of MAPK signaling, and is a key regulator of the MYC transcriptional network in vivo . These results suggest that Mediator kinase activity is involved in activating metabolic pathways during serum response potentially through the regulation of transcriptional pausing or elongation and TF activation. Support or Funding Information NIH SCR Training Grant ‐ T32 GM08759