Cholesterol supplementation reverses myelin status in TDP-43–deleted oligodendrocytes. (A) Schematic of cholesterol supplementation experiments using primary oligodendrocytes cultured from Tardbp^fl/fl (ctrl) and Cnp-Cre;Tardbp^fl/fl (cKO) mice. Water-soluble cholesterol (β-cyclodextrin cholesterol complex) was incubated with cKO oligodendrocytes. (B) Confocal images of MBP and TDP-43 staining of oligodendrocytes from ctrl, cKO, and cKO with cholesterol supplementation (cKO + Chol). Scale bar is 20 µm. (C) Quantification of MBP area in oligodendrocytes from ctrl, cKO, and cKO with cholesterol supplementation (cKO + Chol). Cholesterol supplementation restores the myelination phenotype caused by TDP-43 deletion. MBP area of individual oligodendrocytes (faded circle), and means (solid triangle) for each set of experiment (n = 3) plotted, total mean ± SEM derived from all sets of experiments. Significance was tested using unpaired t test, *, P < 0.05. Quantification was done from three independent experiments with at least 10 cells quantified per experiment. (D) Graphic summary and proposed model for how deletion of TDP-43 affects myelin via regulating SREBF2-mediated cholesterol metabolism in the oligodendrocytes. cKO, conditional knockout; ctrl, control.