The expression of only a small number of cell death genes changes after NGF withdrawal. Bim, dp5, and puma mRNA levels have been previously shown to increase after NGF deprivation and in this study we have confirmed this for bim and dp5. We also found that the bmf, caspase 12, caspase 3, and caspase 4 mRNAs increase in level whereas the expression of cyto chrome c and prothymosin alpha decreases after NGF withdrawal. Thus in sympathetic neurons, as previously described for cerebellar granule Inhibitors,Modulators,Libraries neurons, the expression of the components of the intrinsic pathway, which are all essential for cell death, is not greatly altered by NGF withdrawal. However, what does change significantly is the level of expression of four genes that encode BH3 only proteins that activate the intrinsic pathway, dp5, bim, bmf and puma.
NGF deprived sympathetic Inhibitors,Modulators,Libraries neurons undergo several biochemical and morphological changes before commit ting to the neuronal death programme and some of these are likely to play an important role in triggering apoptosis. Interestingly, Carfilzomib levels of mitochondrial pro duced reactive oxygen species are known to increase early after NGF withdrawal and this causes a cellular pro oxidant state which appears to be required for the release of cytochrome c. The regulation of cellular redox balance is critically determined by the activity of several antioxidant systems one of which is the thioredoxin system. Thioredoxin itself is regulated by an endogenous inhibitor, Txnip and a reduction in thioredoxin activity due to an increase in Txnip levels might lead to increased oxida tion of thiol groups in cellular proteins and ultimately an increase in apoptosis.
We found a 9 fold increase in the level of the txnip mRNA Inhibitors,Modulators,Libraries Inhibitors,Modulators,Libraries after NGF withdrawal and this was reduced to 1. 73 fold in the presence of CEP 11004 which was confirmed in NGF depen dent differentiated PC6 3 cells. Impor tantly, the level of Txnip protein also increased significantly after NGF withdrawal and this increase was prevented by CEP 11004. These data suggest that txnip is a potential target of the MLK JNK c Jun pathway and may play an important role in triggering the apoptotic programme after NGF withdrawal. The endoplasmic reticulum plays a significant role in how cellular proteins are processed, folded, mod ified and transported. In neurodegenerative diseases, these cellular processes may go wrong leading to various levels of ER stress that may contribute to neuronal death. When sympathetic neurons are treated with the ER stressor, tunicamycin, c Jun becomes phosphory lated but this can be prevented using CEP 11004.