Selective targeting of the αC and DFG-out pocket in p38 MAPK

The p38 MAPK cascade is a key signaling pathway linked to a multitude of physiological functions and of central importance in inflammatory and autoimmune diseases. Although studied extensively, little is known about how conformation-specific inhibitors alter signaling outcomes. Here, we have explored the highly dynamic back pocket of p38 MAPK with allosteric urea fragments. However, screening against known off-targets showed that these fragments maintained the selectivity issues of their parent compound BIRB-796, while combination with the hinge-binding motif of VPC-00628 greatly enhanced inhibitor selectivity. Further efforts focused therefore on the exploration of the αC-out pocket of p38 MAPK, yielding compound 137 as a highly selective type-II inhibitor. Even though 137 is structurally related to a recent p38 type-II chemical probe, SR-318, the data presented here provide valuable insights into back-pocket interactions that are not addressed in SR-318 and it provides an alternative chemical tool with good cellular activity targeting also the p38 back pocket.

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Cat.No. Product Name Information Publications Customer Product Validation
S1574 Doramapimod (BIRB 796) Doramapimod (BIRB 796) is a pan-p38 MAPK inhibitor with IC50 of 38 nM, 65 nM, 200 nM and 520 nM for p38α/β/γ/δ in cell-free assays, and binds p38α with Kd of 0.1 nM in THP-1 cells, 330-fold greater selectivity versus JNK2, weak inhibition for c-RAF, Fyn and Lck, insignificant inhibition of ERK-1, SYK, IKK2. (84) (5)

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