State Key Laboratory of Virology, College of Life Sciences, Wuhan University, China.
Chem Biol Interact. 2011 Oct 15;194(1):69-78. doi: 10.1016/j.cbi.2011.08.003. Epub 2011 Aug 16.
β(2)-Microglobulin (β(2)M) modified with advanced glycation end products (AGEs) is a major component of the amyloid deposits in hemodialysis-associated amyloidosis (HAA). However, the effect of glycation on the misfolding and aggregation of β(2)M has not been studied so far. Here we examine the molecular mechanism of aggregate formation of HAA-related ribosylated β(2)M in vitro. We find that the glycating agent d-ribose interacts with human β(2)M to generate AGEs that form aggregates in a time-dependent manner. Ribosylated β(2)M molecules are highly oligomerized compared with unglycated β(2)M, and have granular morphology. Furthermore, such ribosylated β(2)M aggregates show significant cytotoxicity to both human SH-SY5Y neuroblastoma and human foreskin fibroblast FS2 cells and induce intracellular reactive oxygen species (ROS). Presence of the antioxidant N-acetylcysteine (1.0mM) attenuated intracellular ROS and prevented cell death induction in both SH-SY5Y and FS2 cells, indicating that the cytotoxicity of ribosylated β(2)M aggregates depends on a ROS-mediated pathway in both cell lines. In other words, d-ribose reacts with β(2)M and induces the ribosylated protein to form granular aggregates with high cytotoxicity through a ROS-mediated pathway. These findings suggest that ribosylated β(2)M aggregates could contribute to the dysfunction and death of cells and could play an important role in the pathogenesis of β(2)M-associated diseases such as HAA.
β(2)-微球蛋白（β(2)M）与晚期糖基化终产物（AGEs）结合是血液透析相关淀粉样变性（HAA）中淀粉样沉积物的主要成分。然而，糖基化对β(2)M错误折叠和聚集的影响尚未得到研究。在这里，我们研究了体外 HAA 相关核糖化β(2)M 聚集体形成的分子机制。我们发现糖基化剂 d-核糖与人β(2)M 相互作用生成 AGEs，这些 AGEs以时间依赖性方式形成聚集体。与未糖基化的β(2)M相比，核糖化的β(2)M 分子高度寡聚化，并且具有颗粒状形态。此外，这种核糖化的β(2)M 聚集体对人 SH-SY5Y 神经母细胞瘤和人包皮成纤维细胞 FS2 细胞均具有显著的细胞毒性，并诱导细胞内活性氧物种（ROS）。抗氧化剂 N-乙酰半胱氨酸（1.0mM）的存在减轻了细胞内 ROS，并防止了 SH-SY5Y 和 FS2 细胞中的细胞死亡诱导，表明核糖化的β(2)M 聚集体的细胞毒性依赖于两条细胞系中的 ROS 介导途径。换句话说，d-核糖与β(2)M 反应并诱导核糖化蛋白通过 ROS 介导的途径形成具有高细胞毒性的颗粒状聚集体。这些发现表明，核糖化的β(2)M 聚集体可能导致细胞功能障碍和死亡，并在β(2)M 相关疾病（如 HAA）的发病机制中发挥重要作用。
