MIZUNO Kiyonobu Nagasaki University, Graduate School of Biomedical Sciences, Research Associate, 大学院・医歯薬学総合研究所, 助手 (40311865)
YOSHIDA Akira Nagasaki University, Graduate School of Biomedical Sciences, Associate Professor, 大学院・医歯薬学総合研究所, 助教授 (70257187)
Cortical neurons die in necrosis in the low-density (LD) culture, while in apoptosis in the high-density (HD) culture under the serum-free condition without any supplements. The neuronal death in LD culture was delayed by conditioned medium factors (CM) prepared from the HD culture. The CM switched the cell death mode from necrosis to apoptosis. The CM inhibited the rapid decrease in cellular ATP levels and [^3H]-2-deoxy glucose (2-DG) uptake in the LD culture. Inhibitors of phospholipase C and protein kinase C effectively abolished the CM-induced elevation of survival activity, [^3H]-2-DG uptake and ATP levels, and necrosis-apoptosis switch. All these results suggest that CM caused cell death, mode switch from necrosis to apoptosis through phospholipase C and protein kinase C-mediated mechanisms. Moreover, we identified NDI from CM as a key molecule to switch necrosis to apoptosis.
On the other hand, high-glucose treatment also inhibited necrotic cell death and rapid decrease in cellular ATP levels, possibly related to decreased 2-DG uptake under the LD and serum-free condition. Moreover, high-glucose treatment induced apoptosis through increase in Bax levels, cytochrome c release, caspase-3 activation and DNA ladder formation. These results suggest that high-glucose treatment causes cell death mode switch by inhibiting necrosis, while inducing apoptosis under serum free condition. In the retinal ischemia model in mice, the post-ischemic injection of glucose markedly inhibited the neuronal death including necrosis. These results suggest that glucose-induced switch from necrosis to apoptosis and endogenous neurotrophic factors may attenuate glucose-induced apoptosis at the same time. Moreover, we found that ocean factors inhibited neuronal necrosis under the LD and serum free condition and retinal ischemic injury.
In the present study, we discovered cell death mode switch factor, NDI, from CM and necrosis inhibition factors from ocean factors library.