Project description:Activation or maintenance of a leukemia stem cell self-renewal pathway in downstream myeloid cells is an important component of AML development We generated either MLL-AF9 mediated murine leukemias that originate from committed progenitor (GMP) cells or Hoxa9/Meis1a mediated murine leukemias that originate from hematopoietic stem cells (HSC). The leukemia stem cell fraction in these two type of leukemias shared a common self-renewal pathway with normal hematopoietic stem cells. Keywords: Cell type comparison Total RNA from HSC (KLS), CMP, and GMP, and from leukemia stem cells (LGMP) was isolated and hybridized to Affymetrix expresison microarrays.
Project description:This is a mathematical model describing the hematopoietic lineages with leukemia lineages, as controlled by end-product negative feedback inhibition. Variables include hematopoietic stem cells, progenitor cells, terminally differentiated HSCs, leukemia stem cells, and terminally differentiated leukemia stem cells.
Project description:Activation or maintenance of a leukemia stem cell self-renewal pathway in downstream myeloid cells is an important component of AML development We generated either MLL-AF9 mediated murine leukemias that originate from committed progenitor (GMP) cells or Hoxa9/Meis1a mediated murine leukemias that originate from hematopoietic stem cells (HSC). The leukemia stem cell fraction in these two type of leukemias shared a common self-renewal pathway with normal hematopoietic stem cells. Keywords: Cell type comparison
Project description:Gene expression profiling and proteome analysis of normal and malignant hematopoietic stem cells have firmly established the existence of shared core stemness properties. However, the discordance between mRNA and protein signatures underscores an important role for post-transcriptional regulation by miRNAs in governing this critical nexus. Here, we identify miR-130a as a regulator of hematopoietic stem cell (HSC) self-renewal and lineage differentiation. Integration of mass spectrometry and chimeric AGO2 eCLIP-seq identify TBL1XR1 as a primary miR-130a target. TBL1XR1 loss of function impairs lymphoid differentiation and expands long-term (LT)-HSC. This post-transcriptional regulation by miR-130a is usurped in t(8;21) acute myeloid leukemia (AML). Reduction of miR-130a levels in t(8;21) AML cells results in altered chromatin binding and composition of the AML1-ETO complex, demonstrating that miR-130a is critical for maintaining the oncogenic molecular program mediated by AML1-ETO. Our study establishes that comprehensive identification of the miRNA targetome within primary tissue enables the discovery of novel genes and molecular networks underpinning stemness properties of normal and leukemic cells.
Project description:High ploidy large cytoplasmic megakaryocytes (LCM) are critical negative regulators of hematopoietic stem cells (HSC) and are responsible for platelet formation. Using a mouse knockout model with normal megakaryocyte numbers but essentially devoid of LCM (MK-LCM KO), we demonstrated a pronounced increase in bone marrow HSC concurrent with endogenous mobilization and extramedullary hematopoiesis. When HSC isolated from a MK-LCM KO microenvironment were transplanted in lethally irradiated mice, the absence of LCM increased HSC in BM, blood and spleen. Severe thrombocytopenia was observed in animals with diminished LCM, although there was no change in megakaryocyte ploidy distribution. In contrast, WT HSC-generated LCM regulated a normal HSC pool and prevented thrombocytopenia. The present label-free quantitative LC-MSMS data was used to determine proteins that are differentially expressed in bone marrow cells of MK-LCM WT versus MK-LCM KO mice.
Project description:<p>We are studying the natural history, pathogenesis and treatment of patients with WHIM syndrome, an immunodeficiency disorder characterized by warts, hypogammaglobulinemia, recurrent infections and neutropenia usually due to autosomal dominant gain-of-function mutations in chemokine receptor <i>CXCR4</i>. We have identified a patient born with WHIM syndrome and the WHIM mutation <i>CXCR4<sup>R334X</sup></i> who has been disease-free for 20 years and who lacks <i>CXCR4<sup>R334X</sup></i> in myeloid cells, the cells that drive disease manifestations. She is a genetic and hematopoietic mosaic, since she still has the mutation in lymphoid cells and non-hematopoietic cells. Cytogenetics and microarray analysis revealed that the mechanism of loss of the mutation was deletion of the mutant allele from one copy of chromosome 2. Whole genome sequencing of patient neutrophil and skin fibroblast genomic DNA revealed that the mechanism of deletion was chromothripsis, a process of chromosome shattering resulting in deletions and rearrangements of the non-deleted chromosomal segments. In the patient, this process evidently occurred in a single hematopoietic stem cell (HSC), resulting in deletion of the disease allele <i>CXCR4<sup>R334X</sup></i> and one copy of 163 other genes on chromosome 2. This HSC evidently acquired a growth advantage and repopulated the HSC population and the myeloid lineage. Consistent with this, studies using gene targeted mice in competitive bone marrow transplantation experiments revealed that selective <i>Cxcr4</i> haploinsufficiency (inactivation of one copy of <i>Cxcr4</i> and not of any other genes) was sufficient to confer a strong engraftment advantage over bone marrow cells from wild type mice as well as bone marrow cells from a mouse model of WHIM syndrome. These results suggest that <i>CXCR4</i> knockdown may be a useful strategy to enhance bone marrow engraftment in the absence of toxic bone marrow conditioning regimens.</p>
Project description:αβT cell- and B cell-depleted HLA-haploidentical haematopoietic stem cell transplantation is a life-saving therapeutic option to treat patients with high-risk leukemia. The G-CSF treatment stimulates mobilization from the bone marrow to blood of hematopoietic stem cells (HSC), and this manipulated graft also contains mature donor-derived NK and γδT cells, both exerting graft-versus-leukemia activity and control of infections at early stages after transplantation. The G-CSF-induced mobilization in the donor causes relevant increases of different myeloid cells, including polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC). PMN-MDSC are present in high proportions in the graft and exert a sharp inhibition on the effector functions of co-infused mature NK cells. Conversely, low frequencies of PMN-MDSCs are detected in the blood of non-mobilized healthy donors. We used microarray technology to identify possible differences in the transcriptional programme of PMN-MDSCs isolated from blood of G-CSF mobilized donors as compared to those of non-mobilized healthy individuals.
Project description:<p>Hematopoietic stem cell (HSC) mutations can result in clonal hematopoiesis (CH) with heterogeneous clinical outcomes. Here, we investigated how the cell state preceding <em>Tet2</em> mutation impacts the pre-malignant phenotype. Using an inducible system for clonal analysis of myeloid progenitors, we found that the epigenetic features of clones at similar differentiation status were highly heterogeneous and functionally responded differently to <em>Tet2</em> mutation. Cell differentiation stage also influenced <em>Tet2</em> mutation response indicating that the cell of origin's epigenome modulates clone-specific behaviors in CH. Molecular features associated with higher risk outcomes include <em>Sox4</em> that sensitized cells to <em>Tet2</em> inactivation, inducing dedifferentiation, altered metabolism and increasing the <em>in vivo</em> clonal output of mutant cells, as confirmed in primary GMP and HSC models. Our findings validate the hypothesis that epigenetic features can predispose specific clones for dominance, explaining why identical genetic mutations can result in different phenotypes.</p>
Project description:We applied a novel approach of parallel transcriptional analysis of multiple, highly fractionated stem and progenitor populations from patients with acute myeloid leukemia (AML) and a normal karyotype. We isolated phenotypic long-term HSC (LT-HSC), short-term HSC (ST-HSC), and committed granulocyte-monocyte progenitors (GMP) from individual patients, and measured gene expression profiles of each population, and in comparison to their phenotypic counterparts from age-matched healthy controls. Bone marrow samples from AML patients with normal karyotype and age-matched healthy controls were used in this study. Hematopoietic stem and progenitor compartments were purified by multiparameter-high speed fluorescence-activated cell sorting (FACS) from CD34+ enriched bone marrow to isolate LT-HSC (Lin-/CD34+/CD38-/CD90+), ST-HSC (Lin-/CD34+/CD38-/CD90-), and GMP (Lin-/CD34+/CD38+/CD123+/CD45R+).
Project description:Highly purified Hematopoietic stem cells (HSC) from mouse bone marrow (BM) were compared to HSC after two days of cytoxan/GCSF treatment (Cyclophosphamide/granulocyte colony-stimulating factor) (Day2Mob) and leukemic HSC from mice lacking JunB. See Forsberg et. al. 2010 for details. CML - chronic myelogenous leukemia. Biological Replicate