![Hmga1 deficiency prevents MPN phenotypes and expansion of long-term HSC and myeloid progenitors from JAKV617F/V617F mice in a transplantation model. (A) Experimental design to determine Hmga1 function in transplantation model. (B) Red blood cell (RBC) and platelet (PLT) counts from PB of age-matched recipients transplanted with JAK2V617F/V617F or JAK2V617F/V617F/Hmga1+/− BM cells (n = 6 or 7 per group). (C) Representative spleens and relative spleen size (mean ± standard deviation [SD]) in recipient mice transplanted with JAK2V617F/V617F or JAK2V617F/V617F/Hmga1+/− BM cells. (D) Representative BM (humerus; hematoxylin and eosin [H&E] stain) and spleen fibrosis (reticulin staining). Scale bar, 50 μm (left and middle panels). Megakaryocyte numbers per high-power field (Mks/HPF) in BM (humerus; mean ± SD) and splenic fibrosis scores (mean ± SD) from recipient mice transplanted with JAK2V617F/V617F or JAK2V617F/V617F/Hmga1+/− BM cells (n = 6 or 7 per group). (E) Representative flow cytometry plots of BM HSPC. Flow cytometric analysis (mean ± SD) assessed in BM or spleen from recipient mice transplanted with JAK2V617F/V617F or JAK2V617F/V617F/Hmga1+/− BM cells (n = 6 or 7 per group). (F) t-SNE plot of LSK transcriptomes from scRNAseq colored by clusters. The 2 genotypes (JAK2V617F/V617F and JAK2V617F/V617F/Hmga1+/−) are superimposed (left panel). t-SNE plot from JAK2V617F/V617F (middle panel) and JAK2V617F/V617F/Hmga1+/− (right panel) are shown separately to highlight the variation in distribution among the clusters. Hmga1 heterozygous deficiency decreases clusters with markers of HSC (cluster 7), megakaryocyte-biased progenitors (cluster 8), and megakaryocyte/erythroid-biased progenitors (clusters 5-6), while increasing clusters with lymphoid-biased progenitors (clusters 0 and 1). The clusters with the greatest differences across genotype are outlined. The table shows the fraction of LSK cells in clusters grouped by genotype (JAK2V617F/V617F vs JAK2V617F/V617F/Hmga1+/−); P values show differences between genotypes in clusters grouped by cell identity. *P < .05, **P < .01, ***P < .001, Mann–Whitney U test (B-C,E), 2-tailed Student t test (D).](https://ash.silverchair-cdn.com/ash/content_public/journal/blood/139/18/10.1182_blood.2021013925/4/bloodbld2021013925f3b.png?Expires=1723195393&Signature=MhVlkb0l474wTuz~K1zADnBc64vD3tpHMrAEGU91QD~rUtoS8pHZFsLxJN80~IJJaOm-IydnqFkn6idWU~t7PibidhsIjyK9452d93TCcjzWf3CJt2VyIRY5HJZ9-IPIwH0ZS-lefjvttfM-RKPW4lfP2Jub~WpjJB3Q0mGQcQr7dc2pClVqEztoZV72hjda8AV9fC6jWaJlQv9fFdJRsChqfIk7~0OU5sp7h~HQsgKex9xtC90rNQAf5ahfm4~Cz2dYgWhitRQO0~KAqkth-7aJG~3~YDm4b4ELwXeS4D4qKYiHXU~PYKwuELde7ie~ZBYV0nrcQq7suuezLjNfBw__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
Hmga1 deficiency prevents MPN phenotypes and expansion of long-term HSC and myeloid progenitors from JAKV617F/V617F mice in a transplantation model. (A) Experimental design to determine Hmga1 function in transplantation model. (B) Red blood cell (RBC) and platelet (PLT) counts from PB of age-matched recipients transplanted with JAK2V617F/V617F or JAK2V617F/V617F/Hmga1+/− BM cells (n = 6 or 7 per group). (C) Representative spleens and relative spleen size (mean ± standard deviation [SD]) in recipient mice transplanted with JAK2V617F/V617F or JAK2V617F/V617F/Hmga1+/− BM cells. (D) Representative BM (humerus; hematoxylin and eosin [H&E] stain) and spleen fibrosis (reticulin staining). Scale bar, 50 μm (left and middle panels). Megakaryocyte numbers per high-power field (Mks/HPF) in BM (humerus; mean ± SD) and splenic fibrosis scores (mean ± SD) from recipient mice transplanted with JAK2V617F/V617F or JAK2V617F/V617F/Hmga1+/− BM cells (n = 6 or 7 per group). (E) Representative flow cytometry plots of BM HSPC. Flow cytometric analysis (mean ± SD) assessed in BM or spleen from recipient mice transplanted with JAK2V617F/V617F or JAK2V617F/V617F/Hmga1+/− BM cells (n = 6 or 7 per group). (F) t-SNE plot of LSK transcriptomes from scRNAseq colored by clusters. The 2 genotypes (JAK2V617F/V617F and JAK2V617F/V617F/Hmga1+/−) are superimposed (left panel). t-SNE plot from JAK2V617F/V617F (middle panel) and JAK2V617F/V617F/Hmga1+/− (right panel) are shown separately to highlight the variation in distribution among the clusters. Hmga1 heterozygous deficiency decreases clusters with markers of HSC (cluster 7), megakaryocyte-biased progenitors (cluster 8), and megakaryocyte/erythroid-biased progenitors (clusters 5-6), while increasing clusters with lymphoid-biased progenitors (clusters 0 and 1). The clusters with the greatest differences across genotype are outlined. The table shows the fraction of LSK cells in clusters grouped by genotype (JAK2V617F/V617F vs JAK2V617F/V617F/Hmga1+/−); P values show differences between genotypes in clusters grouped by cell identity. *P < .05, **P < .01, ***P < .001, Mann–Whitney U test (B-C,E), 2-tailed Student t test (D).