The Regulatory Mechanism of Src Familly Kinase in Lipopolysaccharide (LPS) induced HF-κB Activation Pathway

Src family tyrosine kinases(TK) have been found to be involved in LPS induction of signal cascades. Furthermore Lipopolysaccharide(LPS) or Tumor necrosis factor alpha (TNF-α) activate nuclear transcription factor κB(NF-κB) by inducing serine or tyrosine phosphorylation of the inhibitory subunit of NF-κ B(I κ B-α). In this study, it is our purpose to search the role of Src TK in LPS induced activation of NF-κ B and NF-κ B dependent induced inflammatory factors.

Nuclear extracts were prepared from RAW 264.7 cells pretreated with damnacanthal or PP1 and then stimulate with LPS. After that, we figured out the dffects of inhibition of Src family kinases on LPS-induced activation of NF-κB by EMSA. We investigated effects of damnacanthal of PP1 on the production of NO by Griess assay and LPS-induced serine phosphorylation and degradation of Iκ B-α by Western blots in LPS-stimulated RAW263.7 cells.

Inhibition of Src TK with damnacanthal or PP1 blocked LPS-induced NF-κB activation at the range of nanomolar concentrations. Substantial inhibition in LPS-induced production of NO was also observed in cells treated with damnacanthal or PP1. These kinase inhibitors blocked LPS-induced the serine phosphorylation, and the degradation of Iκ B-α.

we investigated the role of Src TK in NF-κ B activation and production of nitric oxide (NO) in LPS stimulated RAW 264.7 macrophages and the underlying mechanism by which Src TK play a role in LPS-induction of the possible pathways leading to NF-κ B activation. Src kinase specific inhibitors, damnacanthal and PP1 blocked LPS induced activating NF-κ B and producing Nitric Oxide in Raw 264.7 machrophages. Moreover, Damnacanthal and PP1 inhibited LPS induced serine phosphorylation and degradation of Iκ B-α.