Ectopic protein interactions within BRD4-chromatin complexes drive oncogenic megadomain formation in NUT midline carcinoma

Academic Article

Abstract

  • To investigate the mechanism that drives dramatic mistargeting of active chromatin in NUT midline carcinoma (NMC), we have identified protein interactions unique to the BRD4-NUT fusion oncoprotein compared with wild-type BRD4. Using cross-linking, affinity purification, and mass spectrometry, we identified the EP300 acetyltransferase as uniquely associated with BRD4 through the NUT fusion in both NMC and non-NMC cell types. We also discovered ZNF532 associated with BRD4-NUT in NMC patient cells but not detectable in 293T cells. EP300 and ZNF532 are both implicated in feed-forward regulatory loops leading to propagation of the oncogenic chromatin complex in BRD4-NUT patient cells. Adding key functional significance to our biochemical findings, we independently discovered a ZNF532-NUT translocation fusion in a newly diagnosed NMC patient. ChIP sequencing of the major players NUT, ZNF532, BRD4, EP300, and H3K27ac revealed the formation of ZNF532-NUT-associated hyperacetylated megadomains, distinctly localized but otherwise analogous to those found in BRD4- NUT patient cells. Our results support a model in which NMC is dependent on ectopic NUT-mediated interactions between EP300 and components of BRD4 regulatory complexes, leading to a cascade of misregulation.
  • Authors

    Digital Object Identifier (doi)

    Author List

  • Alekseyenko AA; Walsh EM; Zee BM; Pakozdi T; Hsi P; Lemieux ME; Dal Cin P; Ince TA; Kharchenko PV; Kuroda MI
  • Start Page

  • E4184
  • End Page

  • E4192
  • Volume

  • 114
  • Issue

  • 21