In memory of FranÅoisD iederich who inspired ag eneration of scientists for tackling problems in molecular recognition Abstract: Bromodomain and extra-terminal (BET) family proteins,BRD2-4 and T, are important drug targets;however, the biological functions of each bromodomain remain illdefined. Chemical probes that selectively inhibit asingle BET bromodomain are lacking, although pan inhibitors of the first (D1), and second (D2), bromodomain are known. Here,w e develop selective BET D1 inhibitors with preferred binding to BRD4 D1. In competitive inhibition assays,w es how that our lead compound is 9-33 fold selective for BRD4 D1 over the other BET bromodomains.X -rayc rystallography supports ar ole for the selectivity based on reorganization of an onconserved lysine and displacement of an additional structured water in the BRD4 D1 binding site relative to our prior lead. Whereas pan-D1 inhibitors displace BRD4 from MYC enhancers,B RD4 D1 inhibition in MM.1S cells is insufficient for stopping Myc expression and may lead to its upregulation. Future analysis of BRD4 D1 gene regulation mayshed light on differential BET bromodomain functions.

We report the first set of small molecule co-crystal structures with the bromodomain of BPTF and describe several new leads for chemical probe development.

The bromodomain and extra terminal (BET) protein family recognizes acetylated lysines within histones and transcription factors using two N-terminal bromodomains, D1 and D2. The protein−protein interactions between BET bromodomains, acetylated histones, and transcription factors are therapeutic targets for BET-related diseases, including inflammatory disease and cancer. Prior work demonstrated that methylated-1,2,3triazoles are suitable N-acetyl lysine mimetics for BET inhibition. Here we describe a structure−activity relationship study of triazole-based inhibitors that improve affinity, D1 selectivity, and microsomal stability. These outcomes were accomplished by targeting a nonconserved residue, Asp144 and a conserved residue, Met149, on BRD4 D1. The lead inhibitors DW34 and 26 have a BRD4 D1 K d of 12 and 6.4 nM, respectively. Cellular activity was demonstrated through suppression of c-Myc expression in MM.1S cells and downregulation of IL-8 in TNF-α-stimulated A549 cells. These data indicate that DW34 and 26 are new leads to investigate the anticancer and anti-inflammatory activity of BET proteins.

19F NMR-guided development of a BPTF chemical probe through SAR and ligand deconstruction.