Capture and Identification of Dual Specificity Mitogen-Activated Protein Kinase Kinase 7 as a Direct Proteomic Target of Berberine to Affect the c-JunN-Terminal Kinase Pathway

Seven photoaffinity-based and sixteen biotin-based berberine(BBR)probes were constructed and screened for their effects on c-Jun N-terminal protein kinases(JNK)phosphorylation(p-JNK)suppression at the cellular level.Taking active-photoaffinity probe 7c as a chemical tool,we first identified mitogen-activated protein kinase 7(MAP2K7),an upstream protein on the JNK/stress activated protein kinase(SAPK)pathway,as a direct proteomic target of BBR using activity-based protein profiling(ABPP)and other chemical proteomic techniques.Furthermore,BBR’s inhibitory effect on p-JNK was significantly attenuated in both the MAP2K7-knockdown and models,indicating a MAP2K7-dependent inhibition on the JNK signaling pathway.For the first time,we demonstrate the unique mechanism of BBR that directly targets MAP2K7 to inhibit p-JNK rather than JNK activity with the advantages of multiple activities and a good safety profile.