Oda T, Komatsu N, Muramatsu T
Division of Biochemistry, Faculty of Fisheries, Nagasaki University, Japan.
Biosci Biotechnol Biochem. 1997 Feb;61(2):291-7. doi: 10.1271/bbb.61.291.
Ricin D, one of the two isolectins from small caster beans showed stronger cytotoxicity than another one, ricin E, based on the inhibition of colony formation and the inhibition of protein synthesis. Both ricin D and ricin E induced cell lysis to different extents in each cell line tested, albeit ricin E was slightly less effective than ricin D. DNA fragmentation, a characteristic feature of apoptosis, was also induced by ricin D and ricin E in Vero cells. Scatchard plot analysis showed that ricin D binds to cells with higher affinity than ricin E, while the number of binding sites per cell was not much different, suggesting that the differences in the cytotoxicity between ricin D and ricin E is mainly due to their differential binding affinity to cells. In Vero cells, the cytolytic activities of ricin D and ricin E were inhibited by brefeldin A (BFA), which is known to effect the Golgi apparatus, but not significant effect of BFA was observed in a BFA-resistant cell line, MDCK cells. These results suggest that the Golgi apparatus may be involved in ricin-induced cell lysis.
蓖麻毒素D是小蓖麻籽中的两种异凝集素之一，基于对集落形成的抑制和对蛋白质合成的抑制，其细胞毒性比另一种蓖麻毒素E更强。在每个测试的细胞系中，蓖麻毒素D和蓖麻毒素E均在不同程度上诱导细胞裂解，尽管蓖麻毒素E的效果略逊于蓖麻毒素D。DNA片段化是细胞凋亡的一个特征性表现，在Vero细胞中，蓖麻毒素D和蓖麻毒素E也可诱导其发生。Scatchard作图分析表明，蓖麻毒素D比蓖麻毒素E以更高的亲和力结合细胞，而每个细胞的结合位点数没有太大差异，这表明蓖麻毒素D和蓖麻毒素E之间细胞毒性的差异主要归因于它们对细胞的不同结合亲和力。在Vero细胞中，已知作用于高尔基体的布雷菲德菌素A（BFA）可抑制蓖麻毒素D和蓖麻毒素E的细胞溶解活性，但在BFA抗性细胞系MDCK细胞中未观察到BFA的显著作用。这些结果表明，高尔基体可能参与了蓖麻毒素诱导的细胞裂解。
