Poster abstracts

Poster number 6 submitted by Antonia Duran

Fragment based lead discovery for the Brd4 ET domain

Antonia D. Duran (Ohio State Biochemistry Program, OSU), David Aceti (National Magnetic Resonance Facility at Madison, UW-Madison), Mark P. Foster (Chemistry and Biochemistry, OSU)

Abstract:
Brd4 is a bromodomain and extraterminal domain (BET) family protein that binds acetylated histone lysines via its bromodomains1, and recruits chromatin modifying proteins via its ET domain2. Brd4 plays an important role in regulating the transcription of several oncogenes, including MYC, and has thus been the target of extensive anti-cancer therapeutic development3. All Brd4-targeting therapeutics developed to date target the bromodomains and inhibit Brd4 activity by blocking binding to acetylated lysines. Bromodomain inhibitors have been shown to successfully inhibit Brd4 activity and cause apoptosis or senescence of cancer cells associated with high Brd4 oncogenic activity3. However, bromodomain inhibitors suffer from off-target toxicity in part due to the widespread nature of bromodomains in human proteins. We hypothesize that targeting the ET domain, which is unique to BET family proteins, may provide for higher specificity targeting. To test this hypothesis, we must first develop a cell permeable ligand of the ET domain. We are using fragment based lead discovery (FBLD) to develop such a ligand. Preliminary results of 1D 1H-NMR screening of a fragment library against the ET domain includes strong hits. These hits will be further confirmed using additional 1D 1H-NMR experiments, and their binding sites on the ET domain will be determined using 2D 1H-15N-HSQC titrations. The structure of confirmed hits in complex with the ET domain will be determined to inform optimization of a lead-like ligand for the ET domain. This work was supported by NIH grant R21AI124463 (MPF) and made use of the National Magnetic Resonance Facility at Madison, which is supported by NIH grant P41GM103399 (NIGMS).

References:
1. Zeng, L. & Zhou, M.-M. Bromodomain: an acetyl-lysine binding domain. FEBS Lett. 513, 124–128 (2002).
2. Rahman, S. et al. The Brd4 extraterminal domain confers transcription activation independent of pTEFb by recruiting multiple proteins, including NSD3. Mol. Cell. Biol. 31, 2641–52 (2011).
3. Liu, Z. et al. Drug Discovery Targeting Bromodomain-Containing Protein 4. J. Med. Chem. 60, 4533–4558 (2017)

Keywords: protein, drug discovery, NMR