The O-Linked N-Acetylglucosamine Transferase Modifies HOXA9 and Inhibits HOXA9-Driven Immortalization

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4901-4901
Author(s):  
Jean-Francois M Rual ◽  
Jay L. Hess ◽  
Tao Xu ◽  
Cailin Collins ◽  
Honglai Zhang ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Bone Marrow Cells ◽  
Conflicts Of Interest ◽  
Therapeutic Benefit ◽  
Core Element ◽  
Hematopoietic Stem ◽  
Primary Bone ◽  
Functional Relevance ◽  
Primary Bone Marrow

Abstract The homeodomain-containing transcription factor HOXA9 is a core element of the HOXA9 enhanceosome, a critical DNA-protein complex that regulates hematopoietic stem cell self-renewal during hematopoiesis. Several genetic mutations observed in acute myeloid leukemia (AML) patients, including MLL translocations, are associated with aberrant up regulation of HOXA9, thus disrupting the hematopoietic balance towards leukemogenesis. While analyses of HOXA9 and cofactors have uncovered fundamental aspects of the mechanisms through which these proteins mediate their functions, questions remain. For example, what molecular mechanisms contribute to switching HOXA9 enhanceosomes off during myeloid differentiation? Could these mechanisms be targeted for the therapeutic benefit of leukemia patients? Characterization of the molecular interactions in which HOXA9 enhanceosome proteins are involved should shed light on the mechanisms that govern these proteins during both normal hematopoiesis and leukemogenesis. We recently discovered that HOXA9 interacts physically with OGT, the only O-linked N-acetyl glucosamine transferase in humans. We also demonstrated that HOXA9 is O-GlcNAcylated by OGT. Investigation of the functional relevance of this interaction to HOXA9-driven leukemogenesis is currently under way using interaction- and O-GlcNAcylation-deficient alleles of HOXA9 in a colony formation assay. Our preliminary results suggest that OGT inhibits HOXA9’s ability to transform primary bone marrow cells, thus suggesting OGT is a potential tumor suppressor of HOXA9-driven leukemogenesis. Current efforts focus on further dissecting the molecular interplay occurring between HOXA9 and OGT on chromatin, its impact on the regulation of HOXA9 targets and its role in HOXA9-driven leukemogenesis. Work is also under way to identify factors involved in the OGT-mediated regulation of HOXA9 enhanceosomes. Disclosures: No relevant conflicts of interest to declare.

scholarly journals RNA Methylation and Its Role in the Hematopoietic System

Blood ◽  
2017 ◽  
Vol 130 (Suppl_1) ◽  
pp. SCI-52-SCI-52
Author(s):  
Frank Lyko
Keyword(s):  
Dna Methyltransferase ◽  
Bone Marrow Cells ◽  
Conflicts Of Interest ◽  
Hematopoietic Stem ◽  
Rna Methylation ◽  
Trna Methyltransferase ◽  
A Cell ◽  
Regulatory Capacity ◽  
Primary Bone ◽  
Primary Bone Marrow

Abstract RNA methylation represents a novel expansion of traditional epigenetic concepts. RNAs can be methylated at adenine and at cytosine residues, and both modifications have distinct regulatory potential. Our work focuses on the DNMT2 enzyme, which is a member of the animal (cytosine-5) DNA methyltransferase family and has long been considered to function as a DNA methyltransferase. However, a DNA methyltransferase activity could not be confirmed conclusively and more recent work clearly demonstrates that DNMT2 is a tRNA methyltransferase. This unexpected substrate is interpreted to reflect an evolutionary ancient substrate switch from DNA to tRNA that expanded the epigenetic regulatory capacity of the DNMT family to also include RNA. To analyze the function of DNMT2, we performed a detailed analysis of knockout mice. These mice are viable and fertile, but also show a reduction of hematopoietic stem and progenitor cell populations and a cell-autonomous defect in their differentiation.1 RNA bisulfite sequencing revealed that Dnmt2 methylates C38 of tRNA Asp(GTC), Gly(GCC), and Val(AAC). Proteomic analyses from primary bone marrow cells uncovered systematic differences in protein expression that are due to specific codon mistranslation by tRNAs lacking DNMT2-dependent methylation. Together, these results illustrate the regulatory capacity of DNMT2-mediated tRNA methylation in genome recoding.2 Our current work addresses additional mechanistic aspects that link tRNA methylation to translational fidelity and investigates the relevance of DNMT2-mediated tRNA methylation for leukemogenesis. 1. Tuorto F, Herbst F, Alerasool N, et al. The tRNA methyltransferase Dnmt2 is required for accurate polypeptide synthesis during haematopoiesis. EMBO J. 2015;34(18):2350-2362. 2. Tuorto F, Lyko F. Genome recoding by tRNA modifications. Open Biol. 2016;6(12):160287. Disclosures No relevant conflicts of interest to declare.

Epo Engages a Tnfr-13c Pathway to Advance for Primary Bone Marrow (Pro)Erythroblast Development

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4238-4238
Author(s):  
Seema Singh ◽  
Arvind Dev ◽  
Pradeep Sathyanarayana ◽  
Donald J McCrann ◽  
Christine Emerson ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Late Stage ◽  
Molecular Mechanisms ◽  
Conflicts Of Interest ◽  
Cell Formation ◽  
Erythroid Cell ◽  
Erythroid Progenitors ◽  
Cell Numbers ◽  
Primary Bone ◽  
Primary Bone Marrow

Abstract Abstract 4238 In late stage erythroblasts, EPO can increase levels of Bclx, Bcl2 and/or Mcl1 anti-apoptotic factors. Proerythroblasts, however, are a key EPO target (and exhibit sharp dependence on EPO for growth, and survival). In these progenitors, however, Bclx, Bcl2 and Mcl1 are not prime EPO/EPOR targets. Via transcriptome-based analyses of EPO response circuits in developmentally staged primary bone marrow proerythroblasts (which we now analyze and present at a global level) an atypical TNF receptor, Tnfrsf13c proved to be among the top 1% of EPO/EPOR induced factors. Within lymphoid lineages, Tnfrsf13c is a known receptor for BAFF ligand; and BAFF is an essential mediator of B-cell survival and development. Possible effects of BAFF (a bone marrow stromal cell surface ligand) on primary erythroid cell formation therefore were assessed. Notably, limited BAFF exposure (15 hours) inhibited apoptosis; increased erythroid cell numbers; and enhanced the formation of late-stage Ter119pos erythroblasts. Specifically, cytoprotection by BAFF rivaled that afforded by EPO; cell numbers were enhanced 140% (in 15 hr); and frequencies of Ter119pos erythroblasts were enhanced to 200% of controls. In keeping with Tnfrsf13c's role as an EPOR target, each of the above effects further proved to depend upon proerythroblast exposure to EPO. With regards to Tnfrsf13c expression, analyses using primary erythroid progenitors with knocked-in minimal EPOR alleles indicated dependence for EPO- induction upon JAK2, STAT5 as well as EPOR C-terminal coupled pathways. Studies overall reveal a novel EPOR action route within primary proerythroblasts as a Tnfrsf13c/BAFF pathway (which engages non-canonical NF-kappaB molecular mechanisms). Disclosures: No relevant conflicts of interest to declare.

The Ryk Receptor Regulates Hematopoietic Stem and Progenitor Cell Proliferation and Their Sensitivity To Myeloablative Agents

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 796-796
Author(s):  
Benjamin Povinelli ◽  
Michael Nemeth
Keyword(s):  
Bone Marrow ◽  
Peripheral Blood ◽  
Blood Cells ◽  
Molecular Mechanisms ◽  
Bone Marrow Cells ◽  
Conflicts Of Interest ◽  
Peripheral Blood Cells ◽  
Hematopoietic Stem ◽  
Marrow Cells

Abstract The molecular mechanisms that control the balance between quiescence and proliferation of hematopoietic stem and progenitor cells (HSPCs) are critical for maintaining life-long hematopoiesis. In a recent study (Povinelli, et al. Stem Cells, In Press, 2013) we demonstrated that the Wnt5a ligand inhibits HSPC proliferation through a functional interaction with a non-canonical Wnt ligand receptor termed Related to Receptor Tyrosine Kinase (Ryk). Expression of Ryk on HSPCs in vivo was associated with a decreased rate of proliferation. Following treatment with fluorouracil (5-FU), the percentage of Ryk+ HSPCs increased at the expense of Ryk-/low HSPCs. Based on these data, we hypothesized that one function of the Ryk receptor is to protect HSPCs from the effects of myeloablative agents. To test this hypothesis, we injected 6-8 week old C57BL/6 mice with 150 mg/kg of 5-FU and analyzed bone marrow 48 hours later for the presence of apoptotic HSPCs, defined as lineage negative (Lin-), Sca-1+, CD48- cells positive for active caspase-3. There was a 2.5-fold decrease in the percentage of apoptotic Ryk+ HSPCs (12.9 ± 1.7%) compared to Ryk-/low HSPCs (32.4 ± 5.3%, p < 0.001, n = 3). To test whether this effect was limited to 5-FU, we performed a similar study in which we irradiated C57BL/6 mice with 3 cGy of total body irradiation (TBI) and analyzed bone marrow 72 hours later for apoptotic HSPCs (for this experiment, defined by a Lin-, c-kit+, Sca-1+, CD150+, CD48- immunophenotype or LSK, SLAM). Comparable to the effects of 5-FU, there was a significant 3.0-fold reduction in the percentage of apoptotic Ryk+ HSPCs (3.1 ± 0.2%) compared to Ryk-/low HSPCs (9.2 ± 1.5%, p < 0. 001, n = 3) in mice receiving 3 cGy TBI. These results demonstrated an association between Ryk expression and survival of HSPCs following myeloablative injury. To determine whether in vivo targeting of the Ryk receptor would increase the sensitivity of HSPCs to myeloablative injury, we utilized a neutralizing rabbit anti-Ryk antibody (α-Ryk). We injected C57BL/6 mice with 5 mg/kg α-Ryk or rabbit IgG isotype for 2 consecutive days. Twenty-four hours after the second dose, we determined the frequency and cell cycle status of LSK SLAM cells. Treatment with α-Ryk significantly increased the percentage of LSK SLAM cells in the S/G2/M phases compared to control (α-Ryk: 17.8 ± 2.2%; isotype IgG: 11.6 ± 2.7%, p < 0.05, n = 3). This was associated with a decrease in the percentage of LSK, SLAM cells in G1 following treatment with α-Ryk (α-Ryk: 40.5 ± 3.2%, isotype IgG: 51.3 ± 2.2; p < 0.01, n = 3). The percentage of G0 LSK SLAM cells was unchanged (α-Ryk: 37.9 ± 2.6, isotype IgG: 35.7 ± 3.1% n = 3) indicating that inhibiting Ryk promoted the exit of LSK SLAM cells from G1. Treatment with α-Ryk also increased the percentage of whole bone marrow cells expressing the LSK SLAM phenotype by 1.4-fold compared to controls (p < 0.05, n = 3). To determine if α-Ryk treatment altered HSPC function, we transplanted whole bone marrow cells from C57BL/6 mice treated with two days of α-Ryk or isotype IgG at a 1:1 ratio with whole bone marrow from untreated Ubc-GFP transgenic mice into lethally irradiated B6.SJL mice. Four weeks after transplant, we analyzed peripheral blood cells for the percentage of CD45.2+ GFP- cells. There was no difference in engraftment by transplanted bone marrow cells from mice treated with α-Ryk or isotype IgG (α-Ryk: 61.6 ± 6.1% n = 4, isotype IgG: 52.8 ± 13.6%, n = 5), indicating that the neutralizing antibody does not inhibit short-term HSPC function on its own. We then tested whether blocking Ryk function resulted in greater sensitivity of HSPCs to 5-FU. We treated B6.SJL mice with 5 mg/kg α-Ryk or isotype IgG for 2 consecutive days, followed by 150 mg/kg of 5-FU. Forty-eight hours after 5-FU treatment, we transplanted 2x106 C57BL/6 whole bone marrow cells into treated B6.SJL mice without additional conditioning. Four weeks after transplant, we determined the percentage of donor-derived CD45.2+ peripheral blood cells. Treatment of recipient mice with α-Ryk prior to 5-FU treatment resulted in increased engraftment of donor bone marrow by 3.6-fold compared to isotype (p < 0.05, n = 5), suggesting that inhibition of Ryk resulted in increased elimination of host HSPCs by 5-FU. Collectively, these data suggest a model in which inhibition of the Ryk receptor results in increased proliferation of HSPCs, rendering them more sensitive to the effects of myeloablative agents such as chemotherapy or TBI. Disclosures: No relevant conflicts of interest to declare.

Ang1 Functions as An Autocrine Activating Factor of Tie2 Signaling In Hematopoietic Stem Cells.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1548-1548
Author(s):  
Haruka Momose ◽  
Kazuya Takizawa ◽  
Madoka Kuramitsu ◽  
Takuo Mizukami ◽  
Atsuko Masumi ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Molecular Mechanisms ◽  
Bone Marrow Cells ◽  
Conflicts Of Interest ◽  
Lentiviral Vector ◽  
Down Regulation ◽  
Self Renewal ◽  
Hematopoietic Stem

Abstract Abstract 1548 Hematopoietic stem cells (HSCs) are clonogenic cells that possess the self-renewal capacity to produce more HSCs, as well as the multilineage potential that gives rise to a defined set of mature differentiated progeny for maintenance or repair of the whole blood system. HSCs lie in the hematopoietic niches located along the inner surface of the bone or the sinusoidal endothelium, and are in contact with niche cells. The cell-cell interactions with niche cells are believed to be an important prerequisite to trigger signaling events in HSCs, thereby controlling the balance between HSC self-renewal and differentiation. However, the precise molecular mechanisms regulating niche cell-HSC interactions are not well understood. One of the key molecules for those interactions is Angiopoietin-1 (Ang1). Ang1 is expressed by the niche cells and has been identified as an activating ligand for Tie2 (tyrosine kinase with Ig-like loops and epidermal growth factor homology domains 2). The expression of Tie2 is dominant in HSCs, and Tie2 in HSCs is supposed to be stimulated by Ang1 derived from niche cells. However, Ang1 is also expressed in HSCs. Detailed analysis has shown that Ang1 expression was found to be restricted in long-term HSCs (CD34-lineage-Sca-1+c-Kit+), indicating that Ang1 derived from HSCs plays a role in regulating HSCs. We attempted to elucidate a novel regulating system for HSCs through Ang1-Tie2 signaling by utilizing a hematopoietic cell line in which Tie2 was stably expressed (Ba/F3-Tie2). In Ba/F3-Tie2 cells, Tie2 was found to be phosphorylated on tyrosine residues, even without exogenous addition of Ang1. In the same cells, the expression level of endogenous Ang1 was increased four-fold. When Ang1 expression was down-regulated by transduction with a lentiviral vector expressing short hairpin RNA (shRNA) for Ang1 (shAng1), the phosphorylation of Tie2 was suppressed, suggesting that Tie2 expressed in Ba/F3-Tie2 cells could be stimulated by endogenous Ang1. To mimic the physiological circumstances of the bone marrow, Ba/F3-Tie2 cells were cultured on OP9 stromal cells. Under these culture conditions, the effect of endogenous Ang1 was investigated. Down-regulation of Ang1 by shAng1 demonstrated an approximate 50% reduction in the proliferation of Ba/F3-Tie2 cells on the OP9 cell layer. A HSC-rich population of cells prepared from bone marrow (lineage-Sca-1+c-Kit+; LSK) was also analyzed on OP9 cell layers. Similar to the results obtained from the analysis of Ba/F3-Tie2 cells, down-regulation of Ang1 by shAng1 resulted in an approximately 70% decrease in the proliferation of LSK cells cultured on OP9 monolayers. We confirmed that the suppressive effect on HSC proliferation was due to the lack of Ang1 from HSCs by culturing on Ang1-defective OP9 cells. Finally, we performed in vivo analysis to confirm the importance of endogenous Ang1 to HSCs. Ly5.2 LSK cells transduced with the shAng1 expressing vector were transplanted along with Ly5.1xLy5.2 bone marrow cells into lethally irradiated Ly5.1 mice. The Ly5.2 donor-derived cells in the recipient's peripheral blood were monitored every 2 weeks. As expected, shAng1-introduced donor cells were at decreased ratios at week four (mean ratios, 31.5% for control vs. 17.5% for shAng1), and were reduced to an even lower level at week 12 (mean ratios, 27.1% for control vs. 6.79% for shAng1). This phenomenon was also confirmed by histochemical results, where statistically fewer HSCs existed in the bone marrow of recipient mice in which shAng1-introduced HSCs were transplanted, as compared to the control. Altogether, our data suggested that Tie2 in HSCs could be stimulated by the Ang1 produced by the surrounding HSCs, and this possible autocrine regulation might control the functions of HSCs. Disclosures: No relevant conflicts of interest to declare.

Modeling and Targeting MLL-PTD/RUNX1 Related MDS/AML In Mouse

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2746-2746
Author(s):  
Yue Zhang ◽  
Xiaomei Yan ◽  
Aili Chen ◽  
Goro Sashida ◽  
Zhijian Xiao ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Median Survival ◽  
Molecular Mechanisms ◽  
Bone Marrow Cells ◽  
Conflicts Of Interest ◽  
Insertion Mutagenesis ◽  
Mouse Bone Marrow ◽  
Hematopoietic Stem ◽  
The Impact

Abstract Myelodysplastic syndromes (MDS) are heterogeneous disorders in which the hematopoietic stem cells (HSCs) in the bone marrow are defective, resulting in insufficient normal blood cells. MDS progress to secondary acute myeloid leukemia (sAML) in about one third of patients, as additional genetic abnormalities are acquired. Because of the similar molecular mechanisms under these two related disease categories, MDS with increased blasts (>5%) and AML with multilineage dysplasia and/or antecedent MDS, are also defined as MDS/AML. MLL and RUNX1/CBFb regulate normal hematopoiesis, and we have shown that they form a regulatory complex to regulate downstream target genes. Mutations of MLL1 (in-frame partial tandem duplication, MLL-PTD, or MLL translocations) or RUNX1 are found in about 28% of MDS, particularly in high-risk MDS or therapy-related MDS. sAML frequently contains both MLL-PTD and RUNX1 mutations, arguing for cooperative leukemogenic synergy between these two molecular lesions. However, Mll-PTD knock-in mice or Runx1Δ/Δ mice do not develop spontaneous MDS or AML. RUNX1 mutations can cause mouse MDS/AML in murine retroviral transduction mediated overexpression and BMT, however, the latency is long (8-14 months) and retroviral vector insertion mutagenesis at Evi1 or Mn1loci seems critical for MDS/AML development in this model. Indeed RUNX1 mutations cooperate with Evi1 upregulation in both murine MDS/AML model and human AML. Thus, we hypothesize that combining RUNX1 mutations with MLL-PTD may facilitate its transformation toward MDS and/or sAML. To understand the impact of RUNX1 mutation cooperativity with MLL-PTD, we first expressed MDS relevant patient-derived RUNX1 mutants (D171N and 291fsX300) in the context of Mll-PTD knock-in mouse bone marrow cells and performed BMT and in vitro CFU replating assay. RUNX1 mutations (D171N and 291fsX300) could not transform WT BM cells. However, they could transform MLL-PTD BM cells and undergo serial replating. Interestingly, D171N and 291fsX300 transformed MLL-PTD cells form different type of clones: MLL-PTD/D171N clones are bigger and diffuse, while MLL-PTD/291fsX300 clones are smaller but denser. In BMT assay, the MLL-PTD/D171N and MLL-PTD/291fsX300 BMT mice developed MDS and MDS/AML (2-10 months) after BMT. The MLL-PTD/D171N BMT mice developed anemia, neutropenia with leukodysplasia and left-shifted differential counts, and a hypo-cellular marrow with excess blasts, while MLL-PTD/291fsX300 BMT mice developed rather similar trilineage dysplasia features but present hyper-cellular marrow with high percent of blasts, some of the mice were diagnosed as MDS/AML. Interestingly, the MLL-PTD/291fsX300 BMT mice also develop myelo-fibrosis (MF) in the BM. We further generated Mll-PTD/Runx1Δ/Δ mice using Mx1-Cre mediated deletion. These mice showed thrombocytopenia one month after pI-pC injection, and developed pancytopenia 2-4 months later. The CBC exhibited increased MCV, RDW and severe anemia. All these Mll-PTD/Runx1Δ/Δ mice died of MDS induced complications within 8 months, and tri-lineages dysplasias (TLD) were found in bone marrow aspiration. Similar but accelerated lethal MDS were found in recipients transplanted with PTD/Runx1Δ/Δ BM cells compared with controls (median survival: 68 days VS undefined). Low dose decitabine (DAC 0.3 mg/kg, twice a week, subcutaneous injection) were used to treat these recipients, and we found significantly longer median survival in DAC treated recipients than controls (median survival: 94.5±6.4 VS 53.5±3.5 days, p<0.001). Neither Mll-PTD nor Runx1Δ/Δ BM cells could replate more than 4 times with M3434 methaltheloase, however, PTD/Runx1Δ/Δ BM cells could be replated more than 6 months in vitro. We also treated these cells in vitro with DAC (0.5 uM). Fewer colony numbers and increased differentiated cells (Gr1+/Mac1+) were found in DAC treated cells than PBS treated controls (CFU numbers/1x105seeded cells: 34±7.7 vs 619±30.5, p<0.001). In conclusion, our study demonstrates that: 1) RUNX1 mutations and complete deletions cause MDS or MDS/AML phenotypes in Mll-PTD background; 2) Decitabine is a promising drug to treat MLL-PTD/RUNX1 related MDS/AML. These exciting new models allow us to identify and analyze MDS/AML-initiating cells (MIC) and major targets that are critical for clonal evolution and pathogenesis of MDS/AML and therapeutic interventions. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Expression of Bcl-2 protein and the amplification of c-myc gene in patients with chronic myeloid leukemia

2006 ◽  
Vol 63 (4) ◽  
pp. 364-369 ◽  
Author(s):  
Milica Strnad ◽  
Goran Brajuskovic ◽  
Natasa Strelic ◽  
Biljana Zivanovic-Todoric ◽  
Ljiljana Tukic ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Alkaline Phosphatase ◽  
Chronic Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Molecular Mechanisms ◽  
Bone Marrow Cells ◽  
Chronic Phase ◽  
Blast Transformation ◽  
Hematopoietic Stem ◽  
Myc Gene

Background/Aim. Chronic myeloid leukemia (CML) represents a malignant myeloproliferative disease developed out of pluripotent hematopoietic stem cell that contains the fusion bcr-abl gene. Disorders that occur in the process of apoptosis represent one of the possible molecular mechanisms that bring about the disease progress. The aim of our study was to carry out the analysis of the presence of the amplification of the cmyc oncogene, as well as the analysis of the changes in the expression of Bcl-2 in the patients with CML. Methods. Our study included 25 patients with CML (18 in chronic phase, 7 in blast transformation). Using an immunohistochemical alkaline phosphatase-anti-alkaline phosphatase (APAAP) method, we analyzed the expression of cell death protein in the mononuclear bone marrow cells of 25 CML patients. By a differential PCR (polymerase chain reaction) method, we followed the presence of amplified c-myc gene in mononuclear peripheral blood cells. Results. The level of the expression of Bcl-2 protein was considerably higher in the bone marrow samples of the patients undergoing blast transformation of the disease. The amplification of c-myc gene was detected in 30% of the patients in blast transformation of the disease. Conclusion. The expression of Bcl-2 protein and the amplification of c-myc gene are in correlation with the disease progression.

Characterization of HOX Gene Expression During Myelopoiesis: Role of HOX A5 in Lineage Commitment and Maturation

Blood ◽  
1999 ◽  
Vol 93 (10) ◽  
pp. 3391-3400 ◽  
Author(s):  
John F. Fuller ◽  
Jeanne McAdara ◽  
Yifah Yaron ◽  
Mark Sakaguchi ◽  
John K. Fraser ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Bone Marrow Cells ◽  
Homeobox Genes ◽  
Erythroid Differentiation ◽  
Erythroid Progenitors ◽  
Effector Cells ◽  
Gm Csf ◽  
Important Regulator ◽  
Macrophage Colony

During the process of normal hematopoiesis, proliferation is tightly linked to maturation. The molecular mechanisms that lead to production of mature effector cells with a variety of phenotypes and functions from a single multipotent progenitor are only beginning to be elucidated. It is important to determine how these maturation events are regulated at the molecular level, because this will provide significant insights into the process of normal hematopoiesis as well as leukemogenesis. Transcription factors containing the highly conserved homeobox motif show considerable promise as potential regulators of hematopoietic maturation events. In this study, we focused on identification and characterization of homeobox genes of the HOX family that are important in regulating normal human myeloid differentiation induced by the hematopoietic growth factor, granulocyte-macrophage colony-stimulating factor (GM-CSF). We have identified three homeobox genes, HOX A5, HOX B6, and HOX B7, which are expressed during early myelopoiesis. Treating bone marrow cells with antisense oligodeoxynucleotides to HOX A5 resulted in inhibition of granulocytic/monocytic hematopoiesis and increased the generation of erythroid progenitors. Also, overexpression of HOX A5 inhibited erythroid differentiation of the K562 cell line. Based on these observations, we propose that HOX A5 functions as an important regulator of hematopoietic lineage determination and maturation.

Cultivation of the Erythrocytic Stages of Plasmodium berghei in Primary Bone Marrow Cells

1976 ◽  
Vol 62 (5) ◽  
pp. 657 ◽  
Author(s):  
Clarence A. Speer ◽  
Paul H. Silverman ◽  
Steven G. Schiewe
Keyword(s):  
Bone Marrow ◽  
Plasmodium Berghei ◽  
Bone Marrow Cells ◽  
Primary Bone ◽  
Primary Bone Marrow ◽  
Marrow Cells

Kruppel-Like Factor 10 (KLF10)-Deficient Mice Have Marked Defects In EPC Differentiation, Function, and Angiogenesis

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4314-4314
Author(s):  
Akm Khyrul Wara ◽  
Kevin Croce ◽  
ShiYin Foo ◽  
Xinghui Sun ◽  
Basak Icli ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Bone Marrow Cells ◽  
Conflicts Of Interest ◽  
Hindlimb Ischemia ◽  
Hematopoietic Progenitor ◽  
Hematopoietic Stem ◽  
Deficient Mice ◽  
Tgf Β1 ◽  
Impaired Angiogenesis

Abstract Abstract 4314 Background: Emerging evidence demonstrates that endothelial progenitor cells (EPCs) may originate from the bone marrow and are capable of being recruited to sites of ischemic injury and contribute to neovascularization. However, the identities of these bone marrow cells and the signaling pathways that regulate their differentiation into functional EPCs remain poorly understood. Methods and Results: We previously identified that among hematopoietic progenitor stem cells, common myeloid progenitors (CMPs) and granulocyte-macrophage progenitors (GMPs) can preferentially differentiate into EPCs and possess high angiogenic activity under ischemic conditions compared to megakaryocyte-erythrocyte progenitors (MEPs), hematopoietic stem cells (HSCs), and common lymphoid progenitors (CLPs). Herein, we identify that a TGF-β1-responsive Kruppel-like Factor, KLF10, is robustly expressed in EPCs derived from CMPs and GMPs, compared to progenitors lacking EPC markers. KLF10–/– mice have marked defects in circulating EPCs (–23.6% vs. WT, P&lt;0.004). In addition, EPC differentiation and TGF-β induced KDR responsiveness is markedly impaired (CMPs: WT 22.3% vs. KO 8.64%, P&lt;0.0001; GMPs: WT 32.8% vs. KO 8.97%, P&lt;0.00001). Functionally, KLF10–/– EPCs derived from CMPs and GMPs adhered less to fibronectin-coated plates (CMPs: WT 285 vs. KO 144.25, P&lt; 0.0004; GMPs: WT 275.25 vs. KO 108.75, P &lt;0.0003) and had decreased rates of migration in transwell Boyden chambers (CMPs: WT 692 vs. KO 298.66, P&lt;0.00004; GMPs: WT 635.66 vs. KO 263.66, P&lt;0.00001). KLF10–/– mice displayed impaired blood flow recovery after hindlimb ischemia (day 14, WT 0.827 vs. KO 0.640, P &lt;0.009), an effect completely rescued by WT EPCs, but not KLF10–/– EPCs. Matrigel plug implantation studies demonstrated impaired angiogenesis in KLF10–/– mice compared to WT mice (WT 158 vs. KO 39.83, P&lt;0.00000004). Overexpression studies revealed that KLF10 rescued EPC formation from TGF-β1+/– CMPs and GMPs. Mechanistically, TGF-β1 and KLF10 target the VEGFR2 promoter in EPCs which may underlie these effects. Background: Collectively, these observations identify that TGF-β1 signaling and KLF10 are part of a key signaling pathway that regulates EPC differentiation from CMPs and GMPs and may provide a therapeutic target during cardiovascular ischemic states. Disclosures: No relevant conflicts of interest to declare.

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