Optimization of linear and cyclic peptide inhibitors of KEAP1-NRF2 protein-protein interaction.

Inhibition of KEAP1-NRF2 protein-protein interaction is considered a promising strategy to selectively and effectively activate NRF2, a transcription factor which is involved in several pathologies such as Huntington's disease (HD). A library of linear peptides based on the NRF2-binding motifs was generated on the nonapeptide lead Ac-LDEETGEFL-NH spanning residues 76-84 of the Neh2 domain of NRF2 with the aim to replace E78, E79 and E82 with non-acidic amino acids. A deeper understanding of the features and accessibility of the T80 subpocket was also targeted by structure-based design. Approaches to improve cell permeability were investigated using both different classes of cyclic peptides and conjugation to cell-penetrating peptides. This insight will guide future design of macrocycles, peptido-mimetics and, most importantly, small neutral brain-penetrating molecules to evaluate whether NRF2 activators have utility in HD.