Preparation and evaluation of histone H1.4 C-terminal peptide for cellular delivery of oligonucleotides

Human histone H1.4 C-terminal peptide (HC peptide) was prepared for the cellular delivery of oligonucleotide by using a recombinant expression vector (pGEX-6p-1). Initially, GST-fusion protein was prepared and following protease treatment produced HC peptide of 38 amino acids. The HC peptide formed stable complexes with oligonucleotides with no cytotoxicity on A375B3 melanoma carcinoma cells. Luciferase correction assay with A375B3-Luc cells which was designed to correct the aberrant splicing of luciferase gene by the splice switching oligonucleotide (SSO) demonstrated that HC peptide delivered SSO into the nucleus of cell and corrected aberrant splicing to normal by enhancing the luciferase activity. In addition, intracellular fluorescence images, captured after transfection of TAMRA-oligonucleotide/Alexa-HC peptide complexes, showed the distribution of TAMRA-oligonucleotides near reticuloendothelial system and perinuclear membrane space with minor location at nucleus. Overall, we confirmed that the HC peptide possessed the delivery capability of oligonucleotide into cells, which may be suited for the cellular delivery of oligonucleotide-based drugs.