Abstract
The Polymerase Associated Factor 1 complex (PAF1c) is an epigenetic comodifying complex that directly contacts RNA polymerase II (RNAPII) and several epigenetic regulating proteins. Mutations, overexpression and loss of expression of subunits of the PAF1c are observed in various forms of cancer suggesting proper regulation is needed for cellular development. However, the biochemical interactions with the PAF1c that allow dynamic gene regulation are unclear. We and others have shown that the PAF1c makes a direct interaction with MLL fusion proteins, which are potent oncogenic drivers of acute myeloid leukemia (AML). This interaction is critical for the maintenance of MLL translocation driven AML by targeting MLL fusion proteins to the target genes Meis1 and Hoxa9. Here, we use a proteomics approach to identify protein-protein interactions with the PAF1c subunit CDC73 that regulate the function of the PAF1c. We identified a novel interaction with a histone H3 lysine 9 (H3K9) methyltransferase protein, SETDB1. This interaction is stabilized with a mutant CDC73 that is incapable of supporting AML cell growth. Importantly, transcription of Meis1 and Hoxa9 is reduced and promoter H3K9 trimethylation (H3K9me3) increased by overexpression of SETDB1 or stabilization of the PAF1c- SETDB1 interaction in AML cells. These findings were corroborated in human AML patients where increased SETDB1 expression was associated with reduced HOXA9 and MEIS1. To our knowledge, this is the first proteomics approach to search for CDC73 protein-protein interactions in AML, and demonstrates that the PAF1c may play a role in H3K9me3-mediated transcriptional repression in AML.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 22138-22151 |
| Number of pages | 14 |
| Journal | Oncotarget |
| Volume | 9 |
| Issue number | 31 |
| DOIs | |
| State | Published - Apr 24 2018 |
Funding
The authors thank Dr. Jean-Francois Rual for the SETDB1 isoform 3 construct, Dr. Eric Fearon for the β-catenin expression vector and Dr. Jianyong Shou for a SETDB1 expression construct. We also thank Drs. Mark Chiang, Tomek Cierpicki and Jolanta Grembecka for helpful discussion. AGM and JR designed the study and wrote the paper. JR, ZC, JS, WC and NS performed experiments. LZ, DM, and AIN assisted with statistical analyses. VB ran the LC-MS/MS. All authors reviewed and approved the final version of the manuscript. This work was supported by NIH grants R00CA158136 (A.G.M), R01GM94231 (A.I.N.), U24CA210967 (A.I.N.), T32CA140044 (J.R.); an American Cancer Society Scholar award RSG-15-046 (A.G.M.); Pilot Training Program in Translational Pathology, Department of Pathology, University of Michigan (J.R.).
Keywords
- H3K9 methyltransferase
- Leukemia
- Polymerase associated factor complex
- Protein-protein interaction
- Transcription
ASJC Scopus subject areas
- Oncology
