Biological/Pharmacological Research Laboratories, Central Pharmaceutical Research Institute, Japan Tobacco Inc., 1-1 Murasaki-cho, Takatsuki, Osaka 569-1125, Japan.
Biochemistry. 2020 Mar 31;59(12):1242-1251. doi: 10.1021/acs.biochem.0c00055. Epub 2020 Mar 20.
Ganglioside GM3 is a sialylated membrane-based glycosphingolipid that regulates insulin receptor signaling via direct association with the receptor. The level of expression of GM3 synthase (GM3S) and GM3 is increased in tissues of patients with diabetes and murine models of diabetes, and obesity-induced insulin resistance is attenuated in GM3S-deficient mice. Therefore, GM3S has been considered a therapeutic target for type II diabetes; however, no GM3S inhibitors have been reported to date. In this study, we established a high-throughput scintillation proximity assay that can detect GM3S activity to screen GM3S inhibitors from our original chemical library. We also established methods for detecting the activity of GM3S and another sialyltransferase, ST3Gal3, through direct measurement of the enzyme products using an automatic rapid solid-phase extraction system directly coupled to a mass spectrometer. Consequently, we successfully identified two different chemotypes of GM3S-selective inhibitors with a mixed mode of inhibition. We believe that these compounds can be further developed into drugs to treat or prevent diabetes as well as contribute to the development of the ganglioside research field.
神经节苷脂 GM3 是一种唾液酸化的膜结合糖脂，通过与受体直接结合来调节胰岛素受体信号。糖尿病患者组织和糖尿病及肥胖诱导的胰岛素抵抗小鼠模型中的 GM3 合成酶 (GM3S) 和 GM3 的表达水平增加。因此，GM3S 已被认为是 II 型糖尿病的治疗靶点；然而，迄今为止尚未报道 GM3S 抑制剂。在这项研究中，我们建立了一种高通量闪烁接近测定法，可以检测 GM3S 活性，从而从我们的原始化学文库中筛选 GM3S 抑制剂。我们还通过使用直接连接质谱仪的自动快速固相萃取系统直接测量酶产物，建立了检测 GM3S 和另一种唾液酸转移酶 ST3Gal3 活性的方法。因此，我们成功地鉴定了两种具有混合抑制模式的 GM3S 选择性抑制剂的不同化学型。我们相信这些化合物可以进一步开发成治疗或预防糖尿病的药物，并为神经节苷脂研究领域的发展做出贡献。
