Wan Lei, Manickam Devika S, Oupický David, Mao Guangzhao
Department of Chemical Engineering and Materials Science, Wayne State University, Detroit, Michigan 48202, USA.
Langmuir. 2008 Nov 4;24(21):12474-82. doi: 10.1021/la802088y. Epub 2008 Oct 8.
Controlled intracellular disassembly of polyelectrolyte complexes of polycations and DNA (polyplexes) is a crucial step for the success of nonviral gene delivery. Motivated by our previous observation of different gene delivery performances among multiblock reducible copolypeptide vectors ( Manickam, D. S. ; Oupicky, D. Bioconjugate Chem. 2006, 17, 1395- 1403 ), atomic force microscopy is used to visualize plasmid DNA in various decondensed states from reducible polypeptide polyplexes under simulated physiological reducing conditions. DNA decondensation is triggered by reductive degradation of disulfide-containing cationic polypeptides. Striking differences in DNA release dynamics between polyplexes based on polypeptides of histidine-rich peptide (HRP, CKHHHKHHHKC) and nuclear localization signal (NLS, CGAGPKKKRKVC) peptide are presented. The HRP and NLS polyplexes are similar to each other in their initial morphology with a majority of them containing only one DNA plasmid. Upon reductive degradation by dithiothreitol, DNA is released from NLS abruptly regardless of the initial polyplex morphology, while DNA release from HRP polyplexes displays a gradual decondensation that is dependent on the size of polyplexes. The release rate is higher for larger HRP polyplexes. The smaller HRP polyplexes become unstable when they are in contact with expanding chains nearby. The results reveal potentially rich DNA release dynamics that can be controlled by subtle variation in multivalent counterion binding to DNA as well as the cellular matrix.
聚阳离子与DNA的聚电解质复合物（多聚体）在细胞内的可控解离是实现非病毒基因递送成功的关键步骤。基于我们之前对多嵌段可还原共多肽载体间不同基因递送性能的观察（马尼卡姆，D.S.；奥皮基，D.《生物共轭化学》2006年，第17卷，第1395 - 1403页），利用原子力显微镜在模拟生理还原条件下观察来自可还原多肽多聚体的处于各种解聚状态的质粒DNA。含二硫键的阳离子多肽的还原降解引发DNA解聚。呈现了基于富含组氨酸肽（HRP，CKHHHKHHHKC）和核定位信号（NLS，CGAGPKKKRKVC）肽的多聚体在DNA释放动力学上的显著差异。HRP和NLS多聚体在初始形态上彼此相似，其中大多数仅包含一个DNA质粒。经二硫苏糖醇还原降解后，无论初始多聚体形态如何，DNA从NLS中突然释放，而从HRP多聚体中释放的DNA呈现出逐渐解聚的过程，这取决于多聚体的大小。较大的HRP多聚体释放速率更高。较小的HRP多聚体在与附近伸展的链接触时变得不稳定。结果揭示了潜在丰富的DNA释放动力学，其可通过多价抗衡离子与DNA以及细胞基质结合的细微变化来控制。
