Potassium channels, megapolarization, and water pore formation are key determinants for cationic cell-penetrating peptide translocation into cells

Cell-penetrating peptides (CPPs) allow intracellular delivery of cargo molecules. CPPs provide efficient methodology to transfer bioactive molecules in cells, in particular in conditions when transcription or translation of cargo-encoding sequences is not desirable or achievable. The mechanisms allowing CPPs to enter cells are ill-defined and controversial. This work identifies potassium channels as key regulators of cationic CPP translocation. Using a CRISPR/Cas9-based screening, we discovered that KCNQ5, KCNN4, and KCNK5 positively modulate CPP cellular direct translocation by reducing transmembrane potential (Vm). Cationic CPPs further decrease the Vm to megapolarization values (about -150 mV) leading to the formation of ~2 nm-wide water pores used by CPPs to access the cell cytoplasm. Pharmacological manipulation to lower transmembrane potential boosted CPPs cellular uptake in zebrafish and mouse models. Besides identifying the first genes that regulate CPP translocation, this work characterizes key mechanistic steps used by CPPs to cross cellular membrane. This opens the ground for pharmacological strategies augmenting the susceptibility of cells to capture CPP-linked cargos in vitro and in vivo.