Study On The Signal Molecules Of Apoptosis Of Taxus Cuspidate Cells Induced By Different Valence Of Cerium

In order to well-understand key signal events of T. cuspidata cells induced by different valence of cerium, the influence of Ce⁴⁺ and Ce³⁺ on burst of ROS, phosphorylation of ERK, caspase-like protease/cytochrome c pathway and activation of nuclease was compared systematically. By studying the specialties of these signals and apoptosis of T. cuspidata cells the mechanism of apoptosis of cells induced by Ce⁴⁺ will be well understood.According to the experiment, the burst of ROS and phosphorylation of ERK are two closed important upstream events of cells in response to various stimulators. The ROS may play a necessary but not sufficient role on the signal transduction of the apoptosis induced by Ce⁴⁺, and the key role was played by O2-·or·OH rather than H2O2. The 46-kDa ERK phosphorylating activity of cells may be not especially involved in signal way of apoptosis; it is only a mediator of intracellular signals in response to various stimulators. It is quite like that 21kD and19kD are the very nucleases which lead DNA into fragments rather than 34kD. The activation of 21kD and19kD nucleases needs the long existence of Ce⁴⁺ in the culture but the burst of ROS and the phosphorylation of ERK need only the short term effect of Ce⁴⁺. We conclude that the Ce⁴⁺-induced apoptosis in culture of T. cuspidata is most likely through release of cytochrome c from mitochondria to cytosol and activation of caspase-3, but these events were independent of MAPK cascades.Above all, the result that Ce³⁺ which also belonging to cerium element could not induce the apoptosis of T. cuspidata cells dues to the distinct signal events induced by Ce⁴⁺ and Ce³⁺. Through the research of signal role we explain some different biological effect of different valences of one element in a system. The burst of ROS and phosphorylation of ERK play a necessary but not sufficient role on the signal transduction of the apoptosis induced by Ce⁴⁺.