Decline in lymphoid signatures and increased differentiation-inactive signatures in HSCs in MA mice. (A) Bar graph representing the number of differentially expressed genes (DEGs) increased (red) and decreased (blue) in hematopoietic cell types in pooled data from MA vs young mice. (B) Volcano plot of DEGs in MA vs young HSCs. Significant differences (P < .01) are indicated by colored dots (increased expression in red and decreased expression in blue). (C) Principal component analysis of HSCs from young (circles) and MA (triangles) individual mice based on a defined HSC AS.³⁶ Colors represent AS score from low (purple) to high (yellow). (D) Enrichment score of top GO terms in genes significantly decreased in expression in MA vs young HSCs. Numbers within the bars indicate genes significantly decreased in expression out of total genes represented in the GO term. (E) Enrichment score of top GO terms in genes increased in MA vs young HSCs. Numbers within the bars indicate genes significantly increased in expression out of total genes represented in the GO term. (F-H) Enrichment score of (F) lymphoid, B-cell, and T-cell relevant GO terms, (G) myeloid-relevant GO terms, and (H) MK/erythroid-relevant GO terms in genes decreased (blue) and increased (red) in expression in MA vs young HSCs plotted against the number of genes in the GO term. The dotted horizontal lines indicate a threshold for significance of enrichment at P < .05. Each triangle represents 1 GO term. Complete data with significance testing can be found in supplemental Table 2. (I) Gene set enrichment analysis (GSEA) of signatures representing (left) LPS-induced acute inflammation in HSCs²⁸ and (right) IL-1-induced chronic inflammation in HSCs³⁰ in young vs MA HSCs in our data set. (J) GSEA of a differentiation-inactive HSC signature³⁰ in young vs MA HSCs. AS, aging signature; GMP, granulocyte macrophage progenitor; NK, natural killer, Y, young.