Project description:Integration of index sorting and single cell functional assays identified two functionally distinct subsets of phenotypic haematopoietic stem cells and multipotent progenitors (HSC/MPPs) in the peripheral blood (PB) from healthy individuals. CD71- HSC/MPPs from PB are multipotent and can repopulate the NSG xenograft model. CD71+ HSC/MPPs are a subset of phenotypic HSC/MPPs that is uniquely restricted to give rise to erythroid and megakaryocytic lineages, and expands in conditions with chronic stimulation of platelet production (e.g. frequent platelet donation, idiopathic thrombocytopenic purpura, essential thrombocythaemia). Here, we report the bulk transcriptomes of pools of 20 cells from CD71- HSC/MPPs (CD19- CD38- CD45RA- CD34lo CD71-) and CD71+ HSC/MPPs (CD19- CD38- CD45RA- CD34lo CD71+). Altogether the data shows the transcriptional similarities and differences between both subsets. It shows, that the unique erythroid/megakaryocytic lineage-priming of CD71+ HSC/MPPs is already initiated at transcriptional level, and that CD71+ HSC/MPPs differ from CD71- HSC/MPPs with regards to their protein synthesis/metabolic pathways.
Project description:Aging and chronic inflammation are associated with overabundant myeloid-primed multipotent progenitors (MPPs) amongst hematopoietic stem and progenitor cells (HSPCs). While HSC differentiation bias has been considered a primary cause of myeloid bias, whether it is sufficient has not been quantitatively evaluated. Here, we analyzed bone marrow data from the IκB– (Nfkbia+/-Nfkbib-/-Nfkbie-/-) mouse model of inflammation with elevated NFκB activity, which shows increased myeloid-biased MPPs. We interpreted these data with differential equations models of population dynamics to identify alterations of HSPC proliferation and differentiation rates. This analysis revealed that short-term (ST) HSC differentiation bias alone is likely insufficient to account for the increase in myeloid-biased MPPs. To explore additional mechanisms, we used single-cell RNA sequencing (scRNA-seq) measurements of IκB– and wild-type HSPCs to track the continuous differentiation-trajectories from HSCs to erythrocyte/megakaryocyte, myeloid, and lymphoid primed progenitors. Fitting a partial differential equations model of population dynamics to these data revealed not only less lymphoid-fate specification amongst HSCs, but also increased expansion of early myeloid-primed progenitors. Differentially expressed genes along the differentiation-trajectories supported increased proliferation amongst these progenitors. These findings were conserved when wild-type HSPCs were transplanted into IκB– recipients, indicating that an inflamed bone marrow microenvironment is a sufficient driver. We then applied our analysis pipeline to published scRNA-seq measurements of HSPCs isolated from aged mice, as well as human myeloid neoplasm patients. These analyses identified the same myeloid-primed progenitor expansion as in the IκB– models, suggesting that it is a common feature across different settings of myeloid bias.
Project description:Knockdown of HSPA9 causes a dose-dependent decrease in erythroid maturation of CD34+ cells differentiated in culture. Due to differences in the degree of differentiation, a more homogeneous population was selected for using FACS and the gene expression profile of these cells was compared. We used a lentiviral vector (pLKO.1) expressing short hairpin RNAs targeting either luciferase (control shLUC) or HSPA9 (shHSPA9-433) to knock down expression of HSPA9. We isolated CD34+ cells from human cord blood (Day 0), transduced cells with a lentiviral vector (Day 1), selected for transduced cells with puromycin and differentiated them in erythroid culture media before FACS isolation of the CD34+/CD71- population (Day 5). Four independent CD34+ populations were isolated, differentiated and sorted for biologic replicates.
Project description:We report that Nup358, a nucleoporin linked to acute myeloid leukemia and myeloproliferative neoplasms, is required for the developmental progression of early myeloid progenitors. We found that loss of Nup358 in mice is associated with the accumulation of myeloid-primed multipotent progenitors (MPPs) in bone marrow and the loss of myeloid-committed progenitors and mature myeloid cells. Accumulated MPPs in Nup358 knockout mice are greatly restricted to megakaryocyte/erythrocyte biased MPP2 cells and fail to progress into committed myeloid progenitors.
Project description:Transcription cofactor Rcor1 has been linked biochemically both to neurogenesis and hematopoiesis. Here we studied the function of Rcor1 in vivo and showed it is essential to erythropoeisis during embryonic development. Rcor1 mutant proerythroblasts, unlike normal cells, can form myeloid colonies in vitro. To investigate the underlying molecular mechanisms for block of erythropoiesis and increased myeloid potential, we used RNA-seq to reveal the differentially expressed genes from erythroid progenitors due to depletion of Rcor1. RNA were extracted from FACS sorted CD71+,TER119- erythroid progenitors from control (Rcor1+/+ and Rcor1+/-) or Mutant (Rcor1-/- ) E13.5 fetal liver. Each library was made by pooling RNA from several fetal livers. Two biological replicates were made for either control or mutant condition.
Project description:Vaso-occlusive episodes (VOE) or acute pain events, involving complex interactions between sickle erythrocytes and other blood cells, are a hallmark symptom of sickle cell disease (SCD). In this study, we analyzed changes in peripheral blood transcriptomes between steady state and VOE in individuals with SCD. We followed a cohort of 174 individuals with SCD with or without chronic pain and collected peripheral blood at clinic visits (steady state) and during hospitalizations (VOE). We performed RNA-Seq profiling of CD45+ leukocytes and CD71+ erythroid cells. Pathways linked to complement activation, coagulation, and IL6-JAK-STAT3 signaling were enriched at VOE in the CD45+ cells. Contrastingly, the CD71+ cells showed an enrichment of pathways related to the cell cycle such as mTORC1 signaling and the G2M checkpoint. Expression of four genes—FAM20A, IL1B, MS4A4A, and SERPINB2—were elevated during VOE compared to steady state in a majority of patients.