Anchoring Cationic Amphiphiles for Nucleotide Delivery Significance of DNA Release from Cationic Liposomes for Transfection
作者:Naohide Hirashima、Kazuhiro Minatani、Yoshifumi Hattori、Tomohiko Ohwada、Mamoru Nakanishi
DOI:10.1248/bpb.30.1117
日期:——
We have designed and synthesized lithocholic acid-based cationic amphiphile molecules as components of cationic liposomes for gene transfection (lipofection). To study the relationship between the molecular structures of those amphiphilic molecules, particularly the extended hydrophobic appendant (anchor) at the 3-hydroxyl group, and transfection efficiency, we synthesized several lithocholic and isolithocholic acid derivatives, and examined their transfection efficiency. We also compared the physico-chemical properties of cationic liposomes prepared from these derivatives. We found that isolithocholic acid derivatives exhibit higher transfection efficiency than the corresponding lithocholic acid derivatives. This result indicates that the orientation and extension of hydrophobic regions influence the gene transfection process. Isolithocholic acid derivatives showed a high ability to encapsulate DNA in a compact liposome–DNA complex and to protect it from enzymatic degradation. Isolithocholic acid derivatives also facilitated the release of DNA from the liposome–DNA complex, which is a crucial step for DNA entry into the nucleus. Our results show that the transfection efficiency is directly influenced by the ability of the liposome complex to release DNA, rather than by the DNA-encapsulating ability. Molecular modeling revealed that isolithocholic acid derivatives take relatively extended conformations, while the lithocholic acid derivatives take folded structures. Thus, the efficiency of release of DNA from cationic liposomes in the cytoplasm, which contributes to high transfection efficiency, appears to be dependent upon the molecular shape of the cationic amphiphiles.
我们设计并合成了以石胆酸为基础的阳离子两性分子,作为阳离子脂质体中基因转染(脂质转染)的组成部分。为了研究这些两性分子分子结构之间的关系,尤其是3-羟基基团处的延伸疏水附加物(锚)与转染效率之间的关系,我们合成了几种石胆酸和异石胆酸的衍生物,并检查了它们的转染效率。我们还比较了由这些衍生物制备的阳离子脂质体的物理化学性质。我们发现,异石胆酸衍生物的转染效率高于相应的石胆酸衍生物。这一结果表明,疏水区域的朝向和延伸影响了基因转染过程。异石胆酸衍生物展现出高能力在紧凑的脂质体–DNA复合物中包裹DNA,并保护其免受酶的降解。异石胆酸衍生物还促进了DNA从脂质体–DNA复合物的释放,这对于DNA进入细胞核是一个关键步骤。我们的结果表明,转染效率直接受脂质体复合物释放DNA能力的影响,而不是DNA包裹能力的影响。分子建模显示,异石胆酸衍生物呈现出相对延伸的构象,而石胆酸衍生物则呈现折叠的结构。因此,高转染效率所需的DNA从细胞质中阳离子脂质体释放的效率似乎依赖于阳离子两性分子的分子形状。