Abstract 5235: Affecting activity of the linear ubiquitin chain assembly complex (LUBAC) with stapled alpha-helical peptides

Abstract

Abstract The linear ubiquitin chain assembly complex (LUBAC) is the only E3 ubiquitin ligase known to generate linear polyubiquitin chains in vitro. LUBAC is composed of three proteins - HOIL-1L, HOIP and SHARPIN - of which the interaction between HOIL-1L and HOIP has been shown to be critical for LUBAC assembly and function. This interaction occurs between the ubiquitin-like (UBL) domain of HOIL-1L and the ubiquitin-associated (UBA) domain of HOIP. One known substrate of LUBAC is the regulatory subunit NEMO (NF kappa B essential modulator), part of the IKK complex, which results in activation of NF-κB. We hypothesize that disruption of the HOIL-1L-HOIP interaction would prevent LUBAC ubiquitylation activity and result in down-regulated activation of NF-κB. We have synthesized a family of small inhibitor peptides designed to mimic aspects of the bent alpha-helical interacting interface of HOIP-UBA. Here we demonstrate how single amino acid substitutions and hydrocarbon stapling can affect overall peptide shape and helicity, and correlate that structural information to peptide binding affinity, ability to affect LUBAC complex formation and resulting effect on LUBAC ubiquitylation activity in vitro. These findings continue to validate inhibition of LUBAC via interference with the HOIL-1L-HOIP interaction as a potential target to affect NF-κB signaling. Compounds which affect LUBAC activity have potential use in LUBAC-dependent NF-κB activation in the activated B cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL), the DLBCL subtype that is most resistant to current therapies. Citation Format: Amanda L. Whiting, Francisco Aguilar-Alonso, Joseph J. Mitala, Federico Bernal. Affecting activity of the linear ubiquitin chain assembly complex (LUBAC) with stapled alpha-helical peptides [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5235. doi:10.1158/1538-7445.AM2017-5235