Caracciolo Giulio, Pozzi Daniela, Amenitsch Heinz, Caminiti Ruggero
Department of Chemistry, University of Rome "La Sapienza", P. le A. Moro 5, 00185 Rome, Italy.
Langmuir. 2007 Aug 14;23(17):8713-7. doi: 10.1021/la7017665. Epub 2007 Jul 24.
We propose a mechanism for DNA release from lipoplexes in cells that accounts for various observations of lipoplex-anionic lipid interactions. We examined the structural evolution of lipoplexes upon interaction with cellular lipids by synchrotron small-angle X-ray diffraction (SAXD), and the extent of DNA release from lipoplexes was determined by gel electrophoresis. We find that the interaction of lipoplexes with anionic cellular lipids is a two-stage process. In the first step, anionic lipids laterally diffuse into the complex and neutralize the cationic lipids. As a result, the membrane charge density of lipoplexes decreases and interactions between cationic lipids and DNA become weaker, but DNA is extremely poorly released. Only after the cationic charge of lipoplex membranes is completely neutralized by anionic lipids does DNA starts to be released significantly.
我们提出了一种细胞中脂质体释放DNA的机制，该机制解释了脂质体与阴离子脂质相互作用的各种观察结果。我们通过同步加速器小角X射线衍射（SAXD）研究了脂质体与细胞脂质相互作用时的结构演变，并通过凝胶电泳确定了脂质体释放DNA的程度。我们发现脂质体与阴离子细胞脂质的相互作用是一个两阶段过程。第一步，阴离子脂质横向扩散到复合物中并中和阳离子脂质。结果，脂质体的膜电荷密度降低，阳离子脂质与DNA之间的相互作用变弱，但DNA释放极少。只有在脂质体膜的阳离子电荷被阴离子脂质完全中和后，DNA才开始显著释放。
