Figure 12

The low, intermediate and high activity states of the UPR. The low activity state is shown in (a), where rapid but transient activation of CHOP is followed by the recovery of translational activity. In (b), the intermediate state is shown, which exhibits sustained oscillations in both CHOP and the rate of translation. This eventually leads to the activation of BAX on mitochondrial membrane. In (c), the high activity state is shown with elevated and sustained UPR activity, i.e. activation of PERK and expression of CHOP. The plot also shows severely reduced translation rates and the activation of apoptotic signals. The legend is given on top of the plots. The grey shades indicate active eIF2 α, which represents the relative rate of translation. The initial conditions have been extended towards the negative time axis in order to demonstrate the punctuality of the translational response. The stress conditions chosen are based on Figure 10.