CHLOROQUINE AND AMPHIPATHIC PEPTIDE HELICES SHOW SYNERGISTIC TRANSFECTION IN-VITRO

A pH-responsive peptide fragment modelled on the influenza virus haema gglutinin (INF7-SGSC) can promote the transfectional activity of poly( L)-lysine (pLL)/DNA complexes against 293 cells. Chloroquine also prom otes transfection, but the combination of INF7-SGSC and chloroquine gi ves an increased, synergistic, transfectional activity. This was unexp ected since the supposed modes of action of these two agents are expec ted to be incompatible. Microinjection of pLL/DNA complexes into the c ytoplasm of Xenopus oocytes produced greater gene expression than micr oinjection of free DNA, possibly reflecting nuclear-homing or protecti on from degradation by cytoplasmic nucleases. However, pretreatment of complexes with INF7-SGSC (but not chloroquine) before cytoplasmic mic roinjection promoted gene expression still further. When pLL/DNA compl exes were injected directly into the nucleus, INF7-SGSC again increase d gene expression. The mechanism of post-endosomal action of INF7-SGSC is unknown, but could reflect its polyanionic nature, possibly enhanc ing intranuclear dissociation of the complexes. Whatever the mechanism , it appears that INF7-SGSC mediates two effects - one probably endoso mal and the second post-endosomal, the latter showing a synergistic tr ansfection interaction with chloroquine.