阳离子高分子序列结构与基因递送效率

阳离子高分子基因载体为基因治疗提供了有力工具。项目申请人在青年基金资助下开展了可脱落聚乙二醇修饰聚多肽基因载体的系统研究，取得了系列研究成果。为最大限度发挥聚多肽基因载体功能，本项目启发于自然界生物分子如病毒壳蛋白序列结构对基因转染效率的决定性作用，拟探索聚多肽的单体序列（赖氨酸与组氨酸序列结构）与基因递送效率的关系。将发展"寡聚体"新型缩聚方法构建具有精确单体序列特征的阳离子聚（组氨酸-赖氨酸），其中赖氨酸与组氨酸分别提供载体基因复合能力与内涵体逃逸能力。在合成得到的阳离子聚多肽主链中引入二硫键促进基因胞内释放。通过静电组装基因后，从细胞水平研究不同序列阳离子聚多肽细胞吞噬，内涵体逃逸，胞内释放行为差异。在此基础上，考察细胞水平下定性及定量基因表达行为，凝练序列结构与基因转染性能之间的关系。本项目的实施有望推动当前高分子科学对序列结构的关注及为基因载体科学设计提供新的视角。

Catiomer represents a promising gene carrier to facilitate successful gene delivery. In the implement of previous NSFC project for young program, we have investigated the effect of sheddable PEGylation on gene delivery capacity of cationic polypeptide and found sheddable PEGylation enable to significantly enhance gene transfection efficiency. Inspired by critically important role of monomer sequence of biomolecules in nature(e.g. amino acid sequence in virus) in efficient transfection of specific gene into one target,this project attempts to correlate monomer sequence of polypeptide with gene transfection capacity, to maximize gene transfection efficiency of nonviral gene vector. Lysine and histidine will be chosen as two monomers for its respectively high capacity on gene condensation and endosomal escape. Poly(lysine-co-histidine) with various pre-determined monomer sequence will be fabricated via the assembly of "oligomer" by condensation polymerization. Disulfide bond will be incorporated into the main chain of poly(lysine-co-histidine) between repeated oligomers, which can be cleavable under intracellular relevant glutathione concentration favorable for selectively intracellular release of genetic payload. Upon gene package by poly(lysine-co-histidine), the effect of monomer sequence on cellular endocytosis, trafficking, endosome escape behavior will be investigated. In particular, sequence effect on gene transfection capacity will be summarized. The implement of this project will push forward the scientific attention on monomer sequence and provide insight on rational design of efficient gene vector.