Effect of Natural and Semisynthetic Pseudoguianolides on the Stability of NF-κB:DNA Complex Studied by Agarose Gel Electrophoresis
作者:Rodrigo Villagomez、Rajni Hatti-Kaul、Olov Sterner、Giovanna Almanza、Javier A. Linares-Pastén
DOI:10.1371/journal.pone.0115819
日期:——
The nuclear factor κB (NF-κB) is a promising target for drug discovery. NF-κB is a heterodimeric complex of RelA and p50 subunits that interact with the DNA, regulating the expression of several genes; its dysregulation can trigger diverse diseases including inflammation, immunodeficiency, and cancer. There is some experimental evidence, based on whole cells studies, that natural sesquiterpene lactones (Sls) can inhibit the interaction of NF-κB with DNA, by alkylating the RelA subunit via a Michael addition. In the present work, 28 natural and semisynthetic pseudoguianolides were screened as potential inhibitors of NF-κB in a biochemical assay that was designed using pure NF-κB heterodimer, pseudoguianolides and a ~1000 bp palindromic DNA fragment harboring two NF-κB recognition sequences. By comparing the relative amount of free DNA fragment to the NF-κB – DNA complex, in a routine agarose gel electrophoresis, the destabilizing effect of a compound on the complex is estimated. The results of the assay and the following structure-activity relationship study, allowed the identification of several relevant structural features in the pseudoguaianolide skeleton, which are necessary to enhance the dissociating capacity of NF-κB–DNA complex. The most active compounds are substituted at C-3 (α-carbonyl), in addition to having the α-methylene-γ-lactone moiety which is essential for the alkylation of RelA.
核因子κB(NF-κB)是一个很有希望的药物发现目标。NF-κB 是由 RelA 和 p50 亚基组成的异源二聚体复合物,可与 DNA 相互作用,调节多个基因的表达;其失调可诱发多种疾病,包括炎症、免疫缺陷和癌症。一些基于全细胞研究的实验证据表明,天然倍半萜内酯(Sls)可通过迈克尔加成作用使 RelA 亚基烷基化,从而抑制 NF-κB 与 DNA 的相互作用。本研究利用纯 NF-κB 杂二聚体、假胍内酯和含有两个 NF-κB 识别序列的约 1000 bp 的回旋 DNA 片段设计了一种生化试验,筛选出 28 种天然和半合成的假胍内酯作为 NF-κB 的潜在抑制剂。在常规琼脂糖凝胶电泳中,通过比较游离 DNA 片段与 NF-κB - DNA 复合物的相对量,可以估算出化合物对复合物的不稳定作用。根据检测结果和随后的结构-活性关系研究,确定了假瓜氨酸内酯骨架中的几个相关结构特征,这些特征是增强 NF-κB - DNA 复合物解离能力所必需的。最有活性的化合物在 C-3(α-羰基)处被取代,此外还具有对 RelA 烷基化至关重要的 α-亚甲基-γ-内酯分子。