On the contrary, Ser 529 and Ser 276 were phosphory lated in unstimulated cells, but they were not affected by TNF a stimulation. Effect of wedelolactone on TNF a induced NF B phosphorylation in C6 cells Wedelolactone, an inhibitor FTY720 structure of IKK, sup pressed TNF a induced I B phosphorylation. In addition, phosphorylation of NF B at both Ser 536 and Ser 468 was inhibited by wedelolactone. Wedelolactone, which by itself had little effect on the IL 6 levels, significantly suppressed TNF a induced IL 6 release. The suppressive effect was concentration dependent in the range between 1 and 50 uM. Effect of JAK inhibitor I on TNF Inhibitors,Modulators,Libraries a induced IL 6 release from C6 cells The JAK STAT pathway has an essential role in driving a variety of biological responses to cytokines. The effect of TNF Inhibitors,Modulators,Libraries a on the phosphorylation of STAT3 was examined.

Phosphorylation of STAT3 was marked at 60 min, and reached a peak 150 min after Inhibitors,Modulators,Libraries stimulation. The effect of JAK inhibitor I, an inhibitor of JAK 1, 2 and 3, on TNF a induced IL 6 release was examined. JAK inhibitor I, which by itself had little effect on the IL 6 levels, significantly suppressed TNF a induced IL 6 release. In addition, JAK inhibitor Inhibitors,Modulators,Libraries I truly suppressed TNF a induced phosphory lation of STAT3 in a concentration dependent manner between 10 and 100 nM. The TNF a induced phosphorylation of STAT3 was observed later than phosphorylation of I B, NF B or MAP kinases. This delayed phosphorylation is consistent with a previous report, showing that IL 1b phosphorylates STAT3 60 min after stimulation in C6 cells.

Effect of apocynin on TNF a induced IL 6 release from C6 cells Apocynin, an inhibitor of NADPH oxidase, which by itself had little effect on IL 6 levels, Inhibitors,Modulators,Libraries significantly sup pressed TNF a induced IL 6 release. This sup pressive effect was concentration dependent in the range between 1 and 100 uM. In addition, TNF a significantly induced IL 6 mRNA expression at 6 h after stimulation, thus suggesting that TNF a stimulates the synthesis of IL 6 in C6 glioma cells. The suppressive effect of apocynin on IL 6 release by TNF a could be due to protein synthesis suppression. Apocynin suppressed TNF a induced IL 6 mRNA expression. The effects of apocynin on TNF a induced phosphorylation of I B, NF B, p38 MAP kinase, SAPK JNK or STAT3 were examined to determine whether the apocynin effect on TNF a induced IL 6 release is dependent upon activation of the I B NF B pathway, the MAP kinase superfamily, and the JAK STAT3 pathway in C6 cells.

However, apocynin failed to affect the phosphorylation of these kinases. Discussion TNF a induced IL 6 release else is dependent on the I B NF B pathway. Several sites in the N terminal Rel homology domain, including Ser 276, or in the C termi nus transactivation domain region play a pivotal role in the finer regulation of NF B transcriptional activity.