Fig. 2: Transcriptomic profiles of senescent OPC subpopulations emerge in the aged mouse brain.

a T-distributed stochastic neighbor embedding (tSNE) plot of brain cells clustered according to cell-type markers in young (n = 8) and old (n = 8) male mouse brains from a publically available transcriptomic dataset18. b Cdkn2a/p16-expressing cells in young (b’) and old (b’’) brains. Inset = OPC cluster. c Plots showing mean number (c’) and mean percentage (c’’) of p16-expressing OPCs (total OPCs = 1134 young and 1005 old OPCs, n = 8 mice per age) (Welch’s t-test). d Visualization (as in a, b) of young and old cells expressing Cdkn2a/p16 (green) and Cdkn1a/p21 (red). Color gradient for co-expression is shown. e Bar plot displaying z-scores of significantly activated canonical pathways in p16-expressing OPCs derived from IPA. Exact p values are shown inside the bars (Fischer’s exact test). f Bar plot showing transcripts-per-million (TPM) fold change from young to old OPCs of precursor identity (light gray), mature lineage (black), and emerging OPC aging/senescence (dark gray) markers (f’). Relative change from young to old in the percentage of OPCs expressing the listed markers (f’’). g tSNE plot of OPCs from young (g’) and old (g’’) mice, showing average expression levels of OPC aging/senescence markers (Serpina3n, Meox1, Cdkn2b, Nol3, Skap2), derived from Seurat’s AddModuleScore function. h Plot of gene signature scores (visualized in g), calculated using AddModuleScore (h’) or UCell (h’’) in young and old OPCs24. Mann–Whitney test was used to compare ranks of module scores between young and old OPCs. i Relative expression of emerging OPC aging/senescence markers in the hippocampus and adjacent white matter of young (n = 11) and old (n = 13) mouse brains. Open circles indicate females, while open triangles indicate males. Bars represent mean ± SEM. Exact p values are shown.