Department of Neurology and Neurological Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan.
Center for Brain Integration Research, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan.
Nucleic Acids Res. 2021 May 21;49(9):4864-4876. doi: 10.1093/nar/gkab258.
Antisense oligonucleotide (ASO)-based therapy is one of the next-generation therapy, especially targeting neurological disorders. Many cases of ASO-dependent gene expression suppression have been reported. Recently, we developed a tocopherol conjugated DNA/RNA heteroduplex oligonucleotide (Toc-HDO) as a new type of drug. Toc-HDO is more potent, stable, and efficiently taken up by the target tissues compared to the parental ASO. However, the detailed mechanisms of Toc-HDO, including its binding proteins, are unknown. Here, we developed native gel shift assays with fluorescence-labeled nucleic acids samples extracted from mice livers. These assays revealed two Toc-HDO binding proteins, annexin A5 (ANXA5) and carbonic anhydrase 8 (CA8). Later, we identified two more proteins, apurinic/apyrimidinic endodeoxyribonuclease 1 (APEX1) and flap structure-specific endonuclease 1 (FEN1) by data mining. shRNA knockdown studies demonstrated that all four proteins regulated Toc-HDO activity in Hepa1-6, mouse hepatocellular cells. In vitro binding assays and fluorescence polarization assays with purified recombinant proteins characterized the identified proteins and pull-down assays with cell lysates demonstrated the protein binding to the Toc-HDO and ASO in a biological environment. Taken together, our findings provide a brand new molecular biological insight as well as future directions for HDO-based disease therapy.
反义寡核苷酸（ASO）疗法是下一代疗法之一，尤其针对神经紊乱。许多依赖 ASO 的基因表达抑制的案例已被报道。最近，我们开发了一种生育酚缀合的 DNA/RNA 杂双链寡核苷酸（Toc-HDO）作为一种新型药物。与亲本 ASO 相比，Toc-HDO 更有效、更稳定且能更有效地被靶组织吸收。然而，Toc-HDO 的详细机制，包括其结合蛋白，仍不清楚。在这里，我们使用从老鼠肝脏中提取的荧光标记核酸样品开发了天然凝胶电泳迁移率变动分析。这些分析揭示了两种 Toc-HDO 结合蛋白，膜联蛋白 A5（ANXA5）和碳酸酐酶 8（CA8）。后来，通过数据挖掘，我们又鉴定出两种蛋白质，即无嘌呤/无嘧啶内切核酸酶 1（APEX1）和侧翼结构特异性内切核酸酶 1（FEN1）。shRNA 敲低研究表明，这四种蛋白质在 Hepa1-6 即小鼠肝细胞中均调节 Toc-HDO 的活性。体外结合分析和用纯化的重组蛋白进行荧光偏振分析表征了鉴定出的蛋白质，并用细胞裂解物进行的下拉分析证明了这些蛋白质在生物环境中与 Toc-HDO 和 ASO 的结合。总之，我们的研究结果提供了全新的分子生物学见解，并为基于 HDO 的疾病治疗指明了未来的方向。
