Discovery of a PCAF Bromodomain Chemical Probe

• Published in: Angewandte Chemie International Edition Vol. 56; no. 3; pp. 827 - 831
• Main Authors: Moustakim, Moses, Clark, Peter G. K., Trulli, Laura, Fuentes de Arriba, Angel L., Ehebauer, Matthias T., Chaikuad, Apirat, Murphy, Emma J., Mendez‐Johnson, Jacqui, Daniels, Danette, Hou, Chun‐Feng D., Lin, Yu‐Hui, Walker, John R., Hui, Raymond, Yang, Hongbing, Dorrell, Lucy, Rogers, Catherine M., Monteiro, Octovia P., Fedorov, Oleg, Huber, Kilian V. M., Knapp, Stefan, Heer, Jag, Dixon, Darren J., Brennan, Paul E.
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 16.01.2017; Wiley Subscription Services, Inc; John Wiley and Sons Inc
• Edition: International ed. in English
• Subjects: Azo Compounds - chemical synthesis; Azo Compounds - chemistry; Azo Compounds - pharmacology; Biocompatibility; bromodomains; chemical probes; Chemistry; Chemistry, Multidisciplinary; Communication; Communications; Crystal structure; Cycle ratio; Cytotoxicity; Dose-Response Relationship, Drug; Drug Discovery; epigenetics; Histone H3; Histones; Homology; Hydralazine - chemical synthesis; Hydralazine - chemistry; Hydralazine - pharmacology; Leukocytes (mononuclear); Lysine; medicinal chemistry; Microsomes; Molecular Probes - chemical synthesis; Molecular Probes - chemistry; Molecular Probes - pharmacology; Molecular Structure; p300-CBP Transcription Factors - antagonists & inhibitors; Peripheral blood mononuclear cells; Permeability; Phylogeny; Physical Sciences; Plasmodium falciparum; Rodents; Science & Technology; Selectivity; Structure-Activity Relationship; structure-based design; Toxicity; DESIGN; P300; TAT; IDENTIFICATION; TARGETING BROMODOMAINS; epigenetics; structure-based design; FAMILY; bromodomains; BRD9; chemical probes; INHIBITORS; BINDING; medicinal chemistry; ACETYLTRANSFERASE
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201610816

The p300/CBP‐associated factor (PCAF) and related GCN5 bromodomain‐containing lysine acetyl transferases are members of subfamily I of the bromodomain phylogenetic tree. Iterative cycles of rational inhibitor design and biophysical characterization led to the discovery of the triazolopthalazine‐based L‐45 (dubbed L‐Moses) as the first potent, selective, and cell‐active PCAF bromodomain (Brd) inhibitor. Synthesis from readily available (1R,2S)‐(−)‐norephedrine furnished L‐45 in enantiopure form. L‐45 was shown to disrupt PCAF‐Brd histone H3.3 interaction in cells using a nanoBRET assay, and a co‐crystal structure of L‐45 with the homologous Brd PfGCN5 from Plasmodium falciparum rationalizes the high selectivity for PCAF and GCN5 bromodomains. Compound L‐45 shows no observable cytotoxicity in peripheral blood mononuclear cells (PBMC), good cell‐permeability, and metabolic stability in human and mouse liver microsomes, supporting its potential for in vivo use. Let my PCAF go: The first potent, selective, and cell‐active inhibitor of PCAF bromodomains (Brd) is reported. L‐Moses was shown to disrupt the PCAF‐Brd/histone H3.3 interaction in cells using a nanoBRET assay, and a co‐crystal structure of L‐Moses with the homologous Brd PfGCN5 helps explain the high selectivity for PCAF and GCN5 bromodomains.