jnk-in-8 is a specific jnk1/2/3 inhibitor with ic50 value of 4.67, 18.7, 0.98 nm respectively [1].c-jun n-terminal kinase (jnk) 1, 2 and 3 belong to the mitogen-activated protein kinase (mapk) family, which are able to phosphorylate c-jun on the ser63 and ser73 residue.they are responsive for stress stimuli, including cytokines and heat shock, and get involved in t cell differentiation and cell apoptosis process. jnk 1 and 2 are ubiquitous in all cell types but jnk 3 is only found in cells of brain, heart and testes tissues.jnk-in-8 is a jnk1/2/3 inhibitor with high specificity. when jnk-in-8 was profiled with a panel of 400 kinases, it exhibited specific binding to jnk 1/2/3 but not to other kinases. crystallization study also found that jnk-in-8 forms covalent bonds with conserved cysteine residue of jnk 1/2/3, resulting in a conformational change of the activation loop that blocks the substrate binding, thereby inhibiting the activity of jnk 1/2/3 [1].in hela cells and a375 cells, pretreatment of cells with jnk-in-8 resulted in the inhibition of c-jun which is a direct phosphorylation substrate of jnk 1/2/3, confirming the inhibitory action of jnk-in-8 on jnk 1/2/3. in hek293-ilr1 cells following stimulation by anisomycin, the jnk-in-8 was observed to inhibit c-jun but not msk1 and p38, and the inhibition was not reversible by removing jnk-in-8 from culture medium. additionally, jnk-in-8 only exhibited on-pathway inhibition of jnk signaling pathway, which can be monitored by the phosphorylation of c-jun [1].
[1]. zhang t et al., discovery of potent and selective covalent inhibitors of jnk. chemical biology. 2012, 19(1):140-154.
