Graduate School of Medical Science, Kyoto Prefectural University of Medicine.
Graduate School of Biomedical Sciences, Nagasaki University.
Chem Pharm Bull (Tokyo). 2023;71(3):250-256. doi: 10.1248/cpb.c22-00852.
Amphipathic peptides composed of cationic amino acids and hydrophobic amino acids have cell-penetrating ability and are often used as a delivery tool for membrane-impermeable compounds. Small interfering RNA (siRNAs) are one of the delivery targets for such cell-penetrating peptides (CPPs). Cationic CPPs can associate with anionic siRNAs by electrostatic interactions resulting in the formation of nano-sized complexes, which can deliver siRNAs intracellularly. CPPs containing unnatural amino acids offer promising tools to siRNA delivery. However, the detailed structure-activity relationship in siRNA delivery has been rarely studied. In the current study, we designed peptides containing dipropylglycine (Dpg) and explored the cellular uptake and cytotoxicity of peptide/siRNA complexes. The amphipathic structure of the peptides played a key role in complexation with siRNAs and intracellular siRNA delivery. In the amphipathic peptides, cellular uptake of siRNA increased with increasing peptide length, but cytotoxicity was reduced. A peptide containing four Dpg exhibited an effective gene-silencing effect with small amounts of peptides without cytotoxicity in medium containing serum. These findings will be helpful for the design of novel CPPs for siRNA delivery.
两亲性肽由阳离子氨基酸和疏水性氨基酸组成，具有细胞穿透能力，常用于将膜不可渗透的化合物递送至细胞内。小干扰 RNA（siRNA）是此类细胞穿透肽（CPP）的递送靶标之一。阳离子 CPP 可通过静电相互作用与阴离子 siRNA 结合，形成纳米大小的复合物，从而将 siRNA 递送至细胞内。含非天然氨基酸的 CPP 为 siRNA 递呈提供了有前途的工具。然而，siRNA 递呈的详细结构-活性关系很少被研究。在本研究中，我们设计了含二丙氨酸（Dpg）的肽，并探索了肽/siRNA 复合物的细胞摄取和细胞毒性。肽与 siRNA 形成复合物和细胞内 siRNA 递呈的能力与其两亲性结构有关。在两亲性肽中，随着肽长度的增加，siRNA 的细胞摄取增加，但细胞毒性降低。含有四个 Dpg 的肽在含有血清的培养基中以小量肽而不具有细胞毒性的情况下表现出有效的基因沉默作用。这些发现将有助于设计新型的 siRNA 递呈 CPP。
