SF3B1
MT arrest erythroid terminal differentiation and activate the
EIF2AK1-induced response pathway to heme deficiency. A, UMAP plots of
scRNA-seq data for pooled single MNCs isolated from two HD (n =
5,049) and five SF3B1-mutant MDS-RS (n = 16,212)
samples. Each dot represents one cell. Different colors represent the sample origin
(left) and cluster identity (right). B, UMAP plot of scRNA-seq data from
A showing the 7 different stages of erythroid differentiation in the
total erythroblast population. C, Distribution of the 7 stages of
erythroid differentiation in the HD (top) and MDS-RS (bottom) erythroblast populations
shown in A. Arrows indicate the terminal steps of erythroid
differentiation. D, Pathway enrichment analyses of the genes that were
significantly upregulated in Pro-E (top), Baso-E (middle), Poly-E (bottom) from MDS-RS
samples as compared with those from HD samples (P ≤ 0.01) The top 10
Reactome gene sets are shown. E, Pathway enrichment analysis of the genes
that were significantly upregulated in Ortho-E from MDS-RS samples as compared with
those from HD samples (P ≤ 0.01) The top 10 Reactome gene sets are
shown. F, Left, the number of autophagic vesicles per cell in
SF3B1WT and SF3B1-mutant erythroblasts
from one representative SF3B1WT and one
SF3B1-mutant sample. Statistically significant differences were
detected using a two-tailed Student t test. Right, representative
transmission electron microscopy images of erythroblasts from the BM sections of one
SF3B1WT and one SF3B1-mutant MDS
sample. Scale bars, 500 nm. Baso-E, basophilic erythroblasts; BFU-E, burst-forming
unit-erythroid cells; B-Lympho, B-lymphocytes; CFU-E, colony formation unit-erythroid
cells; DC, dendritic cells; Ery, erythroblasts; HSPC, hematopoietic stem and
progenitor cells; Myelo, myeloid cells; Ortho-E, orthochromatic erythroblasts; Poly-E,
polychromatophilic erythroblasts; Pre-E, pre-erythrocytes; Pro-E, pro-erythroblasts;
T-Lympho/NK, T-lymphocytes, and natural killer cells; UMAP, uniform manifold
approximation and projection.