Fig. 6

Cxcl8 expression by HSPCs expands niche populations and favors early-pseudotime hematopoietic cells (A) UMAP plot showing cellular populations from 96-hpf zebrafish embryos. Data are pooled from four samples derived from two clutches of Runx1:cxcl8-2A-mCherry transgenics and clutchmate controls. Each sample was a pool of 15–20 dissociated embryos. (B) Expression of population-defining niche genes. (C) Expression of selected hematopoietic and signaling factors by niche cell clusters. (D) Differential representation of niche cell clusters according to experimental group. Positive values indicate enrichment in the Runx1:cxcl8-2A-mCherry group relative to clutchmate controls. Values were normalized according to the number of cells recovered per group. Sinusoidal, p = 0.03; lepr+ MSC, p = 6.0 × 10−18; osteoblast, p = 0.03; fibroblast, p = 0.0005; Fisher’s exact test. (E) GSEA enrichment plot for PKC-δ transcriptional targets. Expression data are ranked by differential expression in sinusoidal endothelial cells from Runx1:cxcl8-2A-mCherry embryos compared to control. (F) The log-transformed ratio of precursor and myeloid cells to lymphoid cells is shown. Boxes indicate mean ± SEM. For cxcl8 vs. control, 3.25 ± 0.19 vs. 2.76 ± 0.16, p = 0.049, Welch’s t test. (G) Pseudotime trajectory in the hematopoietic cell partition. The root node is indicated. (H) Stratification of progenitor/myeloid cells by experimental group. (I) Distribution of progenitor/myeloid cells from Runx1:cxcl8 transgenics and control clutchmates according to pseudotime. For cxcl8 vs. control, p = 3.4 × 10−5, two-sample Kolmogorov-Smirnov test. (J) Differential representation of niche cell clusters according to experimental group. Positive values indicate enrichment in the Runx1:cxcl8-2A-mCherry group relative to clutchmate controls. Values were normalized according to the number of cells recovered per group. Osteoblast, p = 0.0029; fibroblast, p = 2.7 × 10−5; sinusoidal endothelial cells, p = 0.013; Fisher’s exact test. See also Figures S5 and S6 and Tables S2–S4.