Affinity Map of Bromodomain Protein 4 ( BRD4) Interactions with the Histone H4 Tail and the Small Molecule Inhibitor JQ1

作者：Jung Marie; Philpott Martin; Mueller Susanne; Schulze Jessica; Badock Volker; Eberspaecher Uwe; Moosmayer Dieter; Bader Benjamin; Schmees Norbert; Fernandez Montalvan Amaury; Haendler Bernard^*

来源：JOURNAL OF BIOLOGICAL CHEMISTRY, 2014, 289(13): 9304-9319.

DOI：10.1074/jbc.M113.523019

• Anticancer Drug
• Cancer Therapy
• Chromatin
• Histones
• Mutant
• Acetylation
• BET Family
• BRD4
• Bromodomain

Background: BRD4 is a reader of acetylated histones. Results: Mutational analysis of BRD4 BD1 allowed the identification of three groups with different binding profiles. Conclusion: Pro-82, Leu-94, Asp-145, and Ile-146 have a differentiated role in acetyl-lysine and inhibitor interaction. Significance: Identification of residues essential for BRD4 function will guide the design of novel inhibitors. %26lt;br%26gt;Bromodomain protein 4 (BRD4) is a member of the bromodomain and extra-terminal domain (BET) protein family. It binds to acetylated histone tails via its tandem bromodomains BD1 and BD2 and forms a complex with the positive transcription elongation factor b, which controls phosphorylation of RNA polymerase II, ultimately leading to stimulation of transcription elongation. An essential role of BRD4 in cell proliferation and cancer growth has been reported in several recent studies. We analyzed the binding of BRD4 BD1 and BD2 to different partners and showed that the strongest interactions took place with di- and tetra-acetylated peptides derived from the histone 4 N-terminal tail. We also found that several histone 4 residues neighboring the acetylated lysines significantly influenced binding. We generated 10 different BRD4 BD1 mutants and analyzed their affinities to acetylated histone tails and to the BET inhibitor JQ1 using several complementary biochemical and biophysical methods. The impact of these mutations was confirmed in a cellular environment. Altogether, the results show that Trp-81, Tyr-97, Asn-140, and Met-149 play similarly important roles in the recognition of acetylated histones and JQ1. Pro-82, Leu-94, Asp-145, and Ile-146 have a more differentiated role, suggesting that different kinds of interactions take place and that resistance mutations compatible with BRD4 function are possible. Our study extends the knowledge on the contribution of individual BRD4 amino acids to histone and JQ1 binding and may help in the design of new BET antagonists with improved pharmacological properties.

• 出版日期2014-3-28