A PEPTIDE NUCLEIC-ACID (PNA) IS MORE RAPIDLY INTERNALIZED IN CULTUREDNEURONS WHEN COUPLED TO A RETRO-INVERSO DELIVERY PEPTIDE - THE ANTISENSE ACTIVITY DEPRESSES THE TARGET MESSENGER-RNA AND PROTEIN IN MAGNOCELLULAR OXYTOCIN NEURONS

A peptide nucleic acid (PNA) antisense for the AUG translation initiat ion region of prepro-oxytocin mRNA was synthesized and coupled to a re tro-inverso peptide that is rapidly taken up by cells. This bioconjuga te was internalized by cultured cerebral cortex neurons within minutes , according to the specific property of the vector peptide. The RNA al one also entered the cells, but more slowly. Cell viability was unaffe cted when the RNA concentrations were lower than 10 mu M and incubatio n times less than for 24 h, Magnocellular neurons from the hypothalami c supraoptic nucleus, which produce oxytocin and vasopressin, were cul tured in chemically defined medium. Both RNA and vector peptide-RNA de pressed the amounts of the mRNA coding for prepro-oxytocin in these ne urons. A scrambled RNA had no effect and the very cognate prepro-vasop ressin mRNA was not affected. The antisense RNA also depressed the imm unocytochemical signal for prepro-oxytocin in this culture in a dose- and time-dependent manner. These results show that PNAs driven by the retro-inverso vector peptide are powerful antisense reagents for use o n cells in culture.