人类跨膜蛋白转铁蛋白受体-1被认为是治疗剂全身递送的有希望的靶标。特别是核酸疗法,如短双链RNA。这种普遍存在的受体参与细胞铁的摄取,保持细胞内稳态。它在多种癌细胞类型中过表达,并通过网格蛋白介导的内吞作用内化。在以往的研究中,人类转铁蛋白受体1RNA适体,被鉴定为TR14ST1-3,被证明能够有效地内化到培养物中的细胞中,双链RNA在体外和体内,通过全身管理。为了理解,在分子水平上,适体与受体结合以及与治疗性RNA结合的影响,采用了多层次的计算机协议,包括蛋白质适体对接,分子动力学模拟和自由能计算。捆绑口袋的竞争,在适体和天然配体人类转铁蛋白之间,也进行了评估。结果表明,适体与转铁蛋白结合相同的区域,来自螺旋结构域的残基显示出关键作用。此外,与治疗性RNA的缀合,显示不影响适体结合。总的来说,这项研究提供了对适体与人转铁蛋白受体1的关联及其与短模型治疗性RNA缀合的原子水平的理解,还为旨在通过转铁蛋白受体提供其他基于寡核苷酸的疗法的期货研究提供重要线索。
The human transmembrane protein Transferrin Receptor-1 is regarded as a promising target for the systemic delivery of therapeutic agents, particularly of nucleic acid therapeutics, such as short double stranded RNAs. This ubiquitous receptor is involved in cellular iron uptake, keeping intracellular homeostasis. It is overexpressed in multiple cancer cell types and is internalized via clathrin-mediated endocytosis. In previous studies, a human transferrin receptor-1 RNA aptamer, identified as TR14 ST1-3, was shown to be capable of effectively internalizing into cells in culture and to deliver small, double stranded RNAs in vitro and in vivo, via systemic administration. To understand, at the molecular level, the aptamer binding to the receptor and the impact of conjugation with the therapeutic RNA, a multi-level in silico protocol was employed, including protein-aptamer docking, molecular dynamics simulations and free energy calculations. The competition for the binding pocket, between the aptamer and the natural ligand human Transferrin, was also evaluated. The results show that the aptamer binds to the same region as Transferrin, with residues from the helical domain showing a critical role. Moreover, the conjugation to the therapeutic RNA, was shown not to affect aptamer binding. Overall, this study provides an atomic-level understanding of aptamer association to human Transferrin Receptor-1 and of its conjugation with a short model-therapeutic RNA, providing also important clues for futures studies aiming to deliver other oligonucleotide-based therapeutics via Transferrin Receptor.