Cationic lipids destabilize lysosomal membrane in vitro.
Addition of cationic lipids to plasmid DNA considerably increases the efficiency of transfection. The mechanism has not yet been elucidated. A possibility is that these compounds destabilize biological membranes (plasma, endosomal, lysosomal), facilitating the transfer of nucleic molecules through these membranes. We have investigated the problem by determining if a cationic lipid N-(1-(2,3-dioleoxy)propyl)-N,N,N,-trimethylammonium methyl-sulfate (DOTAP, Boehringer, Mannheim, Germany) affects the integrity of rat liver lysosomal membrane. We have measured the latency of beta-galactosidase, a lysosomal enzyme, and found that incubation of lysosomes with low concentrations of DOTAP causes a striking increase in free activity of the hydrolase and even a release of the enzyme into the medium. This indicates that lysosomal membrane is deeply destabilized by the lipid. The phenomenon depends on pH, it is less pronounced at pH 5 than at pH 7.4. Anionic compounds, particularly anionic amphipathic lipids, can to some extent prevent this phenomenon. It can be observed with various cationic lipids. A possible explanation is that cationic liposomes interact with anionic lipids of lysosomal membrane, allowing a fusion between the lipid bilayers which results in a destabilization of the organelle membrane.
Wattiaux
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Laboratoire de Chimie Physiologique, Facultés Universitaires Notre-Dame de la Paix, Namur, Belgium. Robert_Wattiaux@fundp.ac.be
Jadot
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Warnier-Pirotte
M T
MT
Wattiaux-De Coninck
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S
D000818:Animals; D002412:Cations; D002474:Cell-Free System; D004247:DNA / Q000737:chemistry; D005229:Fatty Acids, Monounsaturated / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007425:Intracellular Membranes / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry*; D008247:Lysosomes / Q000737:chemistry*; D008297:Male; D010957:Plasmids; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D051381:Rats; D017208:Rats, Wistar; D014162:Transfection / Q000379:methods; D001616:beta-Galactosidase / Q000378:metabolism
D002412:Cations; D005229:Fatty Acids, Monounsaturated; D008055:Lipids; D000644:Quaternary Ammonium Compounds; D004247:DNA; D001616:beta-Galactosidase; C070046:1,2-dioleoyloxy-3-(trimethylammonium)propane