A64 trifluoroacetate

Biochem/physiol Actions

A64 is a cell-permeable, ATP site-targeting pyridone thiazolidinedione compound that acts as a potent HIPK2-selective homeodomain-interacting protein kinase inhibitor (IC50 = 74 nM and 136 nM against HIPK2 and HIPK1, respectively; [ATP] = 100 μM), affecting MPF only at higher concentrations (by 35% at 5 μM; [ATP] = 10 μM) and exhibiting little potency toward CDK1 (IC50 >10 μM). A64 (1 μM) effectively prevents ER stresser tunicamycin (1 μg/mL) -induced HIPK2/JNK phosphorylation and cell death in HEK293 and primary rat motor neuron cultures. HIPK2 inhibition by A64 treatment is also efficacious in protecting rat motor neurons from death upon exogenous SOD1 G93A or TDP-43 expression. ff-target kinases revealed by kinome profiling include DYRK1A, CSNK2A2, DAPK2, DAPK1, PIM3, CSNK2A1, PIM1 (Kd = 8.8, 6.1, 6.1, 9.5, 3.7, 31, 37 nM, respectively) and DYRK1B (IC50 = 62 nM).