Zachariah Hoell

Epigenetics focuses on the methods necessary to both study and manipulate the expression of genetic information. One major source of regulating gene expression is through proteins charged with reading the histone code. Part of the histone code includes a series of N-terminal modifications, such as acetylation on the histone proteins, which are essential for cellular function but when dysregulated can lead to diseases. A specific group of proteins targeted for epigenetic regulation of acetylated histones are human bromodomains, a protein family which binds to acetylated histones to read the histone code. The proteins in the bromodomain and extra-terminal domain (BET) family consist of two highly conserved domains. Upon inhibition of these bromodomains, reduced expression of oncogenes occurs leading to anti-cancer and anti-inflammatory effects. The molecule HU-10, studied here, has been developed as a unique selective inhibitor for BET proteins. In this study, the inhibitor’s piperidine ring nitrogen atom was systematically modified by attaching either a methyl or amide substituent to improve selectivity, affinity, and cellular uptake. Structural analysis of several related inhibitors bound to the protein revealed that side chains appended to the piperidine ring could improve binding interactions via a specific water molecule and acidic residue in the co-crystal structure. Using fluorescence polarization, the IC50 of the new analogs are compared to HU-10 and the pan-BET inhibitor (+)-JQ1 in both BRD4 domains to determine relative changes in both affinity and selectivity with hopes that future cellular studies related to their anti-inflammatory and anti-cancer effects will indicate improvements in activities.