Figure 8: Activation of p-eIF2α-mediated signalling by guanabenz protects OLs and enhances myelination. | Nature Communications

Figure 8: Activation of p-eIF2α-mediated signalling by guanabenz protects OLs and enhances myelination.

From: Regulation of PERK–eIF2α signalling by tuberous sclerosis complex-1 controls homoeostasis and survival of myelinating oligodendrocytes

Figure 8

(a) OPCs from control and Tsc1cKO mice treated with 5 μM guanabenz for 24 h in T3-containing differentiation medium immunostained with cl-Casp3 and Sox10. Scale bar, 25 μm. (b) The percentage of cl-Casp3+/Sox10+ cells from guanabenz-treated OPCs from control and Tsc1cKO mice. Data represent the mean±s.e.m. from three independent experiments. ***P<0.001, Student’s t-test. (c) Western blot analysis of p-eIF2α and eIF2α in OPCs from guanabenz or vehicle-treated Tsc1cKO animals; α-tubulin, loading control. (d) The corpus callosum of control and Tsc1cKO mice treated with vehicle and guanabenz from P7 to P14 was removed at P15, and immunostained with PDGFRα and CC1. Scale bar, 50 μm. (e,f) Numbers of CC1+ cells in the corpus callosum (e) and PDGFRα+ cells in the cortex (f) from vehicle or guanabenz-treated control and Tsc1cKO mice. Whiskers in boxplots show the minimum and maximum, boxes extend from the first to the third quartiles with cross lines at the medians. n=6 animals per group. *P<0.05. One-way analysis of variance with Tukey's multiple-comparison test. (g) Percentage of Ki67+ and Olig2+ cells from the cortex of control and Tsc1cKO mice treated with vehicle or guanabenz. Data represent the mean±s.e.m. from six animals. (h) Representative images showing MBP in the corpus callosum of control and Tsc1cKO mice treated with vehicle or guanabenz. Scale bar, 50 μm. (i) Western blot analysis of MBP in the cortices from control and Tsc1cKO animals treated with vehicle or guanabenz; β-actin, loading control. (j) A schematic diagram of Tsc1/2 mutation-induced ER stress in OL homoeostasis. Tsc1 loss leads to mTOR activation, resulting in excessive protein translation and ER stress by activating the PERK–eIF2α–ATF4 adaptation pathway and Fas/p-JNK apoptotic programs. Sustained ER stress coupled with apoptotic pathway activation contributes to the cell death during OL differentiation in Tsc1 mutants. Inhibition of Gadd34-PP1 by guanabenz (GBZ) enhances p-eIF2α-mediated adaptive responses and partially rescues OL death and myelination defects in Tsc1 mutants.

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