The Study Of Signal Transduction Mechanism Of Ricin Intoxication

Ricin, toxin of Ricinus communis seeds, is a type 2 ribosome-inactivating protein. Ricin and related type 2 toxins are N-glycosidases which cleave the N-glycosidic bond of a single adenine residue in a defined position of rRNA(A4324 of rat liver 28S rRNA). Deadenylated ribosomes are unable to bind the elongation factor 2 with the consequent arrest of protein synthesis and cell death. The study of toxin has advanced in recent year. The present ricin not only inhibited protein synsthesis, but also could induce apoptosis of cultured human hepatoma cells, cytokine secreting of U937 cells and lipid peroxidation in mouse liver. We also demonstrated work here the activity change of some important signal transduction molecules so as to further reveal ricin mechanism. This showed that study consisted of four major parts as follows:Firstly, the apoptosis of human hepatoma cells could be induced by ricin. The evidences include cell morphology change, gel electrophoresis of DNA and FCM. The results futher confirmed that ricin in low concentratecan induce apoptosis of hepatoma cells distinctly, while in high concentrate, ricin has gradually resulted in cells necrosis.Secondly, ricin can induce the production of cytokine by U937. U937 cells were cultured with or without ricin at different time and...