The GST tag was then removed using Prescission protease

habited the activation of NF-kappaB induced by H2O2 in the human lens epithelial cells. So we investigated whether inhibition of H2O2-induced NFkB activation was involved in the neuroprotection afforded by 20E. In most cases, NF-kB is kept inactive in the cytoplasm BIRB796 through binding of its inhibitor IkB. NF-kB activation in response to various extracellular signals requires IkB kinase activation, which phosphorylates IkBa, leading to IkBa’s degradation. Free NF-kB dimers are then rapidly translocated to the nucleus, wherein they bind to the DNA and activate transcription of target genes. At the same time, phosphorylation at multiple serine sites of the p65 subunit increases the transcriptional activity of NF-kB in the nucleus. In this study, we observed that phosphorylation of the p65 subunit in the nucleus under oxidative stress conditions is linked with the simultaneous increased phosphorylation of IkBa in the cytosol, both of which were inhibited by 20E to a similar degree as PDTC, a potent NF-kB inhibitor. These data support that 20E depressed H2O2-induced NF-kB activation in B35 neural cells. Further, PDTC and 20E also reduced iNOS expression and NO production induced by H2O2 in B35 neural cells. These results are consistent with several studies that have shown that NFkB activation is a key factor in the production of iNOS and NO. These data suggest that 20E reduced iNOS expression and NO 15 20-Hydroxyecdysone Inhibits Cerebral Injury production by suppressing activated NF-kB in H2O2 -treated B35 neural cells. Besides directly damaging effects, ROS/RNS have been found to initiate apoptosis signaling pathways. A growing body of evidence has suggested that ROS/RNS are potent inducers of c-Jun N-terminal kinases activation. JNK, also known as stress-activated protein kinase, is an important member of the mitogen-activated protein kinases superfamily. The specific molecular targets of JNK are closely related to apoptotic cell death factors. The ischemic/hypoxic condition is accompanied by the production of ROS/RNS. Thus, cerebral ischemia causes JNK activation. Inhibition of JNK activation would significantly reduce apoptosis induced by cerebral ischemia. In addition, activation of JNK has been observed in many neuronal ischemic models, and SP600125, a selective inhibitor of JNK, provides robust and long-term neuroprotection and improved neurological function after ischemia. In the present study, we observed that H2O2 induced the activation of JNK in B35 neural cells, which was inhibited by 20E. These data suggest that inhibition of JNK activation induced by oxidative stress is involved in the neuroprotective mechanisms of 20E. Because 20E-mediated neuroprotection appears to depend on the inhibition of JNK activation, we further investigated components of the JNK kinase signaling pathway targeted by 20E. Recently, ASK1 was found to be an upstream kinase of JNK. Various ASK1-dependent pathways are involved in JNK activation induced by multiple cell stressors such as reactive oxygen species and DNA damage. For example, ROS from either exogenous or endogenous sources induces ASK1 activation, which further activates both JNK and p38 by activating respective MAPKKs . ASK1 may be an important converging point of multiple pro-death signals that participate in ischemic neuronal death. Knockdown of ASK1 attenuates ischemia-induced JNK and p38 activation and cerebral ischemia insult. Thus, targeting ASK1 provides not only neuroprotection, but also