The nuclear export signal-dependent localization of oligonucleopeptides enhances the inhibition of the protein expression from a gene transcribed in cytosol

Upon endocytosis, most oligodeoxynucleotides (ODNs) accumulate in vesicular compartments; a tiny number of them cross the vesicle membrane, reach the cytosol and by passive diffusion enter the nucleus where they are entrapped . So far, the compartment in which an antisense ODN interacts with its mRNA target has not been precisely characterized. In an attempt to answer this question, ODN-peptides were designed with the aim of maintaining them in th e cytosol, This has been achieved by a short peptide sequence called the nu clear export signal (NES). Upon microinjection, ODN-NES peptide conjugates were efficiently and rapidly exported from the nucleus to the cytosol where as ODN-peptides containing an inactive NES were found to be located in the nucleus. The inhibitory activity of antisense ODN was tested in a system al lowing the specific transcription of a luciferase reporter gene in the cyto sol, Antisense propynylated ODN-NES peptide conjugates, directed against th e luciferase gene, efficiently inhibited (75%) the cytosolic expression of luciferase whereas at the same concentration the peptide-free propynylated ODN or the propynylated ODN-peptides containing an inactive NES were nearly inactive.