Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, School of Chemistry, Central China Normal University, Wuhan 430079, China.
Biomaterials. 2012 Nov;33(31):7884-94. doi: 10.1016/j.biomaterials.2012.07.017. Epub 2012 Jul 25.
We have demonstrated that the metal complexes of polybenzimidazoles are emerging likely as a new type of gene-delivery systems based on their strong DNA-condensing ability. However, the in vitro transfection efficacy of the DNA condensates formed with the metal complexes was relatively low. The positively charged peptides, such as cell-penetrating peptides and nuclear localization sequences (NLSs), have been reported to be capable of enhancing expression of the transgenes, likely as they promote entrance of their electrostatic complexes with DNA into the nuclear through nuclear pores. Here, we explored expression of the genes transferred by a series of Co(II) complexes in the presence of NLS (PKKKRKV) in normal and cancer cell lines. The results showed that the Co(II) complexes lead to the more pronounced DNA condensation in the presence of NLS than that in the absence of NLS. The binding of NLS prior to addition of the Co complexes can significantly reduce both the size and the population of the condensates at the given Co complexes/DNA ratios, compared with the NLS-free condensates. Meanwhile, the binding of NLS can considerably increase surface positive charges on the DNA nanoparticles. The suitable sizes and high surface positive charges facilitate the entrance of the nanoparticles into cells. Luciferase activity assay indicated that the transfection efficacy of the NLS-bound condensates was five-fold of that of the NLS-free ones in different cell lines, and comparable to that of the condensate formed with the commercially available carrier PEI. Moreover, cell viability assay of the NLS-bound condensates showed lower cytotoxicity than the NLS-free ones. Thus, the combination of NLS and cationic metal complexes might offer a new type of ternary delivery systems.
我们已经证明，聚苯并咪唑的金属配合物很可能成为一种新型的基因传递系统，基于它们强大的 DNA 凝结能力。然而，与金属配合物形成的 DNA 凝聚物的体外转染效率相对较低。带正电荷的肽，如穿透细胞膜的肽和核定位序列（NLSs），已被报道能够增强转基因的表达，可能是因为它们促进了与其 DNA 形成的静电复合物通过核孔进入细胞核。在这里，我们研究了一系列 Co(II)配合物在NLS（PKKKRKV）存在下在正常和癌细胞系中转基因的表达。结果表明，NLS 的存在导致 Co(II)配合物导致更明显的 DNA 凝聚，而 NLS 不存在时则没有。与无NLS 的凝聚物相比，在添加 Co 配合物之前结合 NLS 可以显著减少在给定的 Co 配合物/DNA 比例下凝聚物的大小和数量。同时，NLS 的结合可以显著增加 DNA 纳米颗粒表面的正电荷。合适的大小和高表面正电荷有助于纳米颗粒进入细胞。荧光素酶活性测定表明，NLS 结合的凝聚物在不同细胞系中的转染效率是无 NLS 凝聚物的五倍，与商用载体 PEI 形成的凝聚物相当。此外，NLS 结合的凝聚物的细胞活力测定显示出比无 NLS 结合的凝聚物更低的细胞毒性。因此，NLS 和阳离子金属配合物的结合可能提供了一种新型的三元传递系统。
