Figure 3
From: A novel specific PERK activator reduces toxicity and extends survival in Huntington's disease models
MK-28 selectively activates PERK using purified components in vitro. (A) MK-28 was tested for its effect on isolated PERK in vitro, showing an activating effect starting in the nanomolar range with an EC50 of 490 nM (see Supplementary Fig. S2). It was compared to the PERK inhibitor GSK606414, which exhibited the opposite effect than MK-28, showing strong inhibition. The graph shows PERK activity compared to untreated control (100%) (see Methods), expressed as medians +- interquartile range of 3 independent experiments. P value MK-28 1.11 μM vs. 0.37 μM = 0.04. (B) MK-28 revealed an activating effect, but in the micromolar range, on the related EIF2AK4 kinase (GCN2) with an EC50 of 3.5 μM, while no effect was observed for EIF2AK1 or EIF2AK2. Graph as in (A), P value for GCN2, MK-28 3.33 μM vs. 1.11 μM = 0.03. (C) MK-28 was tested over a panel of 391 kinases at 1 μM in duplicate tests (red and blue). EIF2AK3 (PERK) was the highest hit of the panel with an activation of 181,4% of the control (black arrow), P value vs. untreated = 0.006. The experiment was performed by Reaction Biology Corp. (see Methods) and only the “Atypical kinase panel” results are shown, including the four eIF2α kinases, (see Supplementary Table S1 for complete results for all 391 kinases).
