Fig. 4: Primitive UBA1^mut HSPCs are primed toward proinflammatory myeloid differentiation and prematurely aged.

a, Uniform manifold approximation and projection (UMAP) plot of human CD45⁺ cells, enriched in the CD34⁺ HSPC fraction, from the BM of mice transplanted with 100% UBA1^wt or UBA1^mut HSPCs. Clusters and associated cell types are indicated by name and color. b, B cell (top) and erythroid (bottom) pseudotime trajectories starting from the HSC or MPP cluster in the UMAP plot (left) and distribution of cells along the trajectory (right) from a. c, Heatmap showing normalized enrichment scores (NESs) for the GSEA performed within the differentiated clusters comparing 100% UBA1^mut versus UBA1^wt xenografts. Gray squares represent a mismatch between the DEGs of a selected cluster and the gene set as a result of the threshold for detecting the DEGs and the minimum gene set size for the calculation of the enrichment score. Wilcoxon’s rank-sum test with the Benjamini–Hochberg correction was used. d, Distribution of cells in G1, S or G2/M phases of the cell cycle within differentiated cell cluster and sample according to signatures from ref. ⁸⁷. e, UMAP plot of human CD34⁺ HSPCs from the BM of mice transplanted with 100% UBA1^wt or 40% UBA1^mut HSPCs. f, Distribution of cells across HSPC clusters from scRNA-seq in e. g, Heatmap as in c showing NESs for the GSEA performed within HSPC clusters in e comparing 40% UBA1^mut versus 100% UBA1^wt xenografts. Wilcoxon’s rank-sum test with the Benjamini–Hochberg correction was used. h, Distribution of cells in G1, S or G2/M phases of the cell cycle within HSPC clusters in e. i, Density plots showing the distribution of cells from the 100% UBA1^wt and 40% UBA1^mut groups on the BM reference map from Extended Data Fig. 3e. j,k, AUCell scores based on a monocyte signature from ref. ⁶⁹ (j) and aged HSC signatures from refs. ^71,72 (k) within primitive HSCs or MPPs according to projection on the BM reference map (n = 1,728 and 532 cells). The whiskers are located at 1.5× the IQR and the dots represent outliers. Wilcoxon’s rank-sum test with the Benjamini–Hochberg correction was used. **P < 0.01; ****P < 0.0001. Baso, basophils; conv, conventional; EMT, epithelial-to-mesenchymal transition; imm, immature; junc, junction; lympho, lymphoid; mast, mast cells; met, metabolism; myelo, myeloid cells; prec, precursors; prog, progression; prolif, proliferative; rej, rejection; sign, signalling; UPR, unfolded protein response.