Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS.
SomaLogic, Boulder, CO.
J Immunol. 2024 Dec 1;213(11):1691-1702. doi: 10.4049/jimmunol.2400420.
Aptamers are short, single-stranded oligonucleotides that selectively bind to target biomolecules. Although they generally exhibit good binding specificity, their affinities are often limited because of the relative lack of hydrophobic groups in nucleic acids. Chemically modified nucleotides incorporating hydrophobic structures into uracil have been synthesized to address this obstacle. Modified DNA aptamers containing such nonstandard nucleotides have been developed for >20 different complement proteins. These modified aptamers show increased affinity and enhanced serum stability and have potential value as therapeutic agents. We recently conducted a structure/function study on a family of modified DNA aptamers that bind specifically to complement Factor B (FB). This work revealed that these aptamers selectively inhibit the complement alternative pathway (AP) by preventing the formation of the AP complement component C3 (C3) proconvertase complex, C3bB. Certain patients with atypical hemolytic uremic syndrome express gain-of-function variants of FB that enhance the formation of the proconvertase complex and/or decrease the efficacy of endogenous regulators against the C3 convertases they form. To investigate whether these FB-binding aptamers could override the effects of disease-causing mutations in FB, we examined how they interacted with several FB variants, including D279G, F286L, K323E, and K350N, in various assays of complement function. We found that the inhibitory effect of the FB-binding aptamers superseded the gain-of-function mutations in FB, although the aptamers could not dissociate preformed C3 convertases. These findings suggest that FB-binding aptamers could be further developed as a potential treatment for certain atypical hemolytic uremic syndrome patients or those with other diseases characterized by excessive complement activity.
适配子是短的、单链寡核苷酸，能够选择性地与靶生物分子结合。尽管它们通常表现出良好的结合特异性，但由于核酸中相对缺乏疏水性基团，它们的亲和力往往受到限制。已经合成了将疏水性结构引入尿嘧啶的化学修饰核苷酸，以解决这一障碍。已经开发出含有这些非标准核苷酸的修饰 DNA 适配子来结合 >20 种不同的补体蛋白。这些修饰的适配子显示出更高的亲和力和增强的血清稳定性，并具有作为治疗剂的潜在价值。我们最近对一组特异性结合补体因子 B (FB) 的修饰 DNA 适配子进行了结构/功能研究。这项工作表明，这些适配子通过阻止补体替代途径 (AP) 补体成分 C3 (C3) 原转化酶复合物 C3bB 的形成，选择性地抑制 AP。某些非典型溶血性尿毒综合征患者表达增强原转化酶复合物形成和/或降低内源性调节剂对其形成的 C3 转化酶的功效的 FB 功能获得性变体。为了研究这些 FB 结合适配子是否可以克服 FB 致病突变的影响，我们检查了它们如何与几种 FB 变体相互作用，包括 D279G、F286L、K323E 和 K350N，在补体功能的各种测定中。我们发现，FB 结合适配子的抑制作用超过了 FB 的功能获得性突变，尽管适配子不能解离预先形成的 C3 转化酶。这些发现表明，FB 结合适配子可以进一步开发为某些非典型溶血性尿毒综合征患者或其他补体活性过度疾病患者的潜在治疗方法。
