Novel DOCK2-selective inhibitory peptide that suppresses B-cell line migration

Abstract Dedicator of cytokinesis 2 (DOCK2) is a key molecule for lymphocyte activation and migration. DOCK2 interacts with Ras-related C3 botulinus toxin substrate 1 (Rac1, GTPase) and mediates the GDP-GTP exchange reaction, indicating that inhibitors against protein-protein interaction (PPI) between DOCK2 and Rac1 would be good drug candidates for treating immune-related disorders. Here, we report DOCK2-selective PPI inhibitory peptides discovered using random peptide T7 phage display technology. These peptides inhibited DOCK2 activity at nanomolar concentrations and were delivered to intracellular compartments by combination with cell-penetrating peptide (CPP). Consequently, one peptide, R4-DCpep-2(V2W/K4R/ox)-NH 2 (Ac-RRRRCWARYHGYPWCRRRR-NH 2 ), inhibited migration in human B lymphocyte MINO cell line at IC 50  = 120 nM. To our knowledge, this is the first report of a DOCK2-selective peptide inhibitor; this study will contribute to the development of novel DOCK2-targeting immunosuppressive drugs.