First Steps toward the Design of Peptides that Influence the Intracellular Palmitoylation Machinery.

Protein S-palmitoylation is a reversible posttranslational modification transferring the 16-carbon fatty acid palmitate to cysteines. It plays a critical role in many cellular processes by influencing protein function, localization, stability, and protein-protein interactions and has a significant impact on various physiological and pathological conditions. This emphasizes the need to develop new technologies to study and treat diseases associated with aberrant palmitoylation. To address these challenges, cell-permeable peptides containing an Asp-His-His-Cys (DHHC) palmitoylation motif are presented aiming to affect intracellular protein S-palmitoylation. A small library of peptides is generated and screened for cellular uptake and cell compatibility. Interestingly, the newly designed peptides internalize to high extent into different cell lines and human breast cell spheroids dependent on their palmitoylation motif. In addition, out of this screen, DC-2 is identified as very potent and this peptide is investigated in more detail concerning its impact on palmitoylated proteins that are connected to cancer progression. These initial explorations highlight that DC-2 affected the localization of HRas and altered S-palmitoylation-related signaling cascades of epidermal growth factor receptor. These findings suggest a peptide-driven impact on proteins having palmitoylation sites and highlight cell-permeable DHHC peptides as a potential tool to be further evolved in the context of palmitoylation and cancer.