Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, United States.
Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota 55905, United States.
Biochemistry. 2020 Oct 13;59(40):3856-3868. doi: 10.1021/acs.biochem.0c00529. Epub 2020 Sep 30.
Fatty acid-induced upregulation of death receptor 5 (DR5) and its cognate ligand, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), promotes hepatocyte lipoapoptosis, which is a key mechanism in the progression of fatty liver disease. Accordingly, inhibition of DR5 signaling represents an attractive strategy for treating fatty liver disease. Ligand competition strategies are prevalent in tumor necrosis factor receptor antagonism, but recent studies have suggested that noncompetitive inhibition through perturbation of the receptor conformation may be a compelling alternative. To this end, we used yeast display and a designed combinatorial library to identify a synthetic 58-amino acid affibody ligand that specifically binds DR5. Biophysical and biochemical studies show that the affibody neither blocks TRAIL binding nor prevents the receptor-receptor interaction. Live-cell fluorescence lifetime measurements indicate that the affibody induces a conformational change in transmembrane dimers of DR5 and favors an inactive state of the receptor. The affibody inhibits apoptosis in TRAIL-treated Huh-7 cells, an model of fatty liver disease. Thus, this lead affibody serves as a potential drug candidate, with a unique mechanism of action, for fatty liver disease.
脂肪酸诱导死亡受体 5（DR5）及其配体肿瘤坏死因子相关凋亡诱导配体（TRAIL）的上调促进了肝细胞脂肪凋亡，这是脂肪性肝病进展的关键机制。因此，抑制 DR5 信号转导代表了治疗脂肪性肝病的一种有吸引力的策略。配体竞争策略在肿瘤坏死因子受体拮抗作用中很常见，但最近的研究表明，通过改变受体构象的非竞争性抑制可能是一种更具吸引力的替代方法。为此，我们使用酵母展示和设计的组合文库来鉴定一种特异性结合 DR5 的合成 58 个氨基酸亲和体配体。生物物理和生化研究表明，该亲和体既不阻断 TRAIL 的结合，也不阻止受体-受体相互作用。活细胞荧光寿命测量表明，该亲和体诱导 DR5 跨膜二聚体的构象变化，并有利于受体的无活性状态。该亲和体抑制 TRAIL 处理的 Huh-7 细胞（脂肪性肝病模型）中的细胞凋亡。因此，这种先导亲和体作为一种具有独特作用机制的潜在药物候选物，可用于治疗脂肪性肝病。
