Hypomethylating agent therapy inhibits the EIF2AK1-induced response pathway to heme
deficiency in terminally differentiated cells in patients who became transfusion
independent. A, UMAP plots of scRNA-seq data for pooled single
Lin-CD34+ cells isolated from two SF3B1-mutant MDS-RS
patients at the time of diagnosis (n = 2,372) and at the time of
response to HMA therapy (n = 1,551). Each dot represents one cell.
Different colors represent the sample origin (left) and cluster identity (right).
B, UMAP plots of scRNA-seq data for pooled single MNCs isolated from
three SF3B1-mutant MDS-RS patients at the time of diagnosis
(n = 6,089) and response to HMA therapy (n =
6,156). Each dot represents one cell. Different colors represent the sample origin
(left) and cluster identity (right). C, Distribution of the stages of
erythroid differentiation in the total erythroblast population shown in B
at the time of diagnosis (left) and at the time of response to HMA therapy (right).
Arrows indicate Ortho-E. D, Pathway enrichment analysis of the genes in
the MDS-RS Pro-E, Baso-E, and Poly-E clusters shown B that were
significantly downregulated at the time of response to HMA therapy as compared with
the time of diagnosis (adjusted P ≤ 0.05). The top 10 Reactome gene
sets are shown. E, Pathway enrichment analysis of the genes in the MDS-RS
Ortho-E shown in B that were significantly downregulated at the time of
response to HMA therapy as compared with the time of diagnosis (P ≤
0.01). The top 10 Reactome gene sets are shown. Baso-E, basophilic erythroblasts;
BFU-E, burst-forming unit-erythroid cells; B-Lympho, B-lymphocytes; CFU-E, colony
formation unit-erythroid cells; Ery/Mk, erythroid/megakaryocytic; HSC, hematopoietic
stem cells; HSPC, hematopoietic stem and progenitor cells; Lympho, lymphoid; Mk,
megakaryocytic; Mono, monocytes; MPP, multipotent progenitors; Myelo, myeloid; NK,
natural killer cells; Ortho-E, orthochromatic erythroblasts; PC, plasma cells; Poly-E,
polychromatophilic erythroblasts; Pre-E, pre-erythrocytes; Pro-E, pro-erythroblasts;
Prog, progenitors; T-Lympho, T-lymphocytes; UMAP, uniform manifold approximation and
projection.