Extended Data Figure 2. Enhanced EGFR expression in oligodendrocyte lineage cells prevents oligodendrocyte death and promotes proliferation of OPCs in white matter.

a–d, Representative 40x confocal images of Rep⁺PI⁺ cells from Nx and Hyp WM at P11 in Rep and Rep-hEGFR mice. e, At P11 and P18, Hyp resulted in a significant increase in the number of OL cells undergoing apoptosis (Rep⁺casp3⁺). Enhanced EGFR expression prevented this increase at all time points, except P60 where no difference was evident. Comparison of the Hyp Rep with the Hyp Rep-hEGFR groups demonstrates that hEGFR in OL lineage cells is protective against apoptosis induced by Hyp (n=4 mice per group and per age; One-way ANOVA, Bonferroni post hoc test for individual comparisons). f, PI was injected intraperitoneally (IP) 1-hour prior to sacrifice. A significant increase in the number of Rep⁺PI⁺ OL cells indicated membrane disruption contributing to cell death (n=3 mice per group; One-way ANOVA, Bonferroni post hoc test for individual comparisons). g–j, Representative 40x confocal images of Rep⁺NG2⁺ OPCs from Nx and Hyp WM at P18 in the Rep and Rep-hEGFR mice. k, At P11 and P18, Rep-hEGFR Nx mice had more NG2⁺ expressing OPCs compared to the Rep Nx group. Hyp resulted in a significant increase in the number of Rep⁺NG2⁺ OPCs in both Rep and Rep-hEGFR groups, however, overexpression of hEGFR did not have an additive effect (n=4 mice per group and per age; One-way ANOVA, Bonferroni post hoc test for individual comparisons). l, At P11 and P18, the Rep-hEGFR group had more Rep⁺Ki67⁺ cells, however this did not reach significance (P>0.05). Hyp resulted in enhanced OL-lineage proliferation at P11 and P18, but hEGFR overexpression did not have a significantly additive effect, when compared to the Rep Hyp group. k,l, n=4 mice per group and per age; One-way ANOVA, Bonferroni post hoc test for individual comparisons. m, More OPCs were in a proliferative state in Rep-hEGFR Nx mice compared to Rep Nx. Hyp enhanced OPC proliferation, and overexpression of hEGFR resulted in a significantly additive increase compared to the Rep Hyp group (n=3 mice per group; One-way ANOVA, Bonferroni post hoc test for individual comparisons). All histograms are presented as means ± s.e.m. Scale bars, 50μm (a–d, g–j). ^P=0.05; *P<0.05; **P<0.01.