bluuebunny/crossref_metadata_2025_split huggingface dataset:
Overlapping but Distinct Role of p21WAF1/CDKN1 and Survivin in Hematopoietic Progenitor Cell Proliferation.
Authors: Fukuda Seiji , Abe Mariko , Yamaguchi Seiji , Pelus Louis M. 
Published: April 2020

Abstract
Survivin is a member of the inhibitor of apoptosis protein family that has been implicated in cell cycle control, anti-apoptosis and cell division. Our previous studies and others have shown that Survivin and the cyclin dependent kinase inhibitor p21WAF1/CDKN1 (p21) are functionally associated and are involved in cell cycle, anti-apoptosis and cytokinesis in cancer cells and in normal hematopoietic progenitor cells (HPC). P21 is highly expressed in quiescent hematopoietic stem cells (HSC) in steady state, but the proportion of quiescent HSCs in G0 phase is reduced in p21−/− mice. In contrast, p21 has been shown as positive regulator on cell cycle of normal HPC since p21 deficiency results in fewer total CFU in mouse bone marrow (BM) cells with fewer CFU in S-phase and retrovirus transduction of p21 in p21 deficient bone marrow cells restores total and cycling CFU. We have previously reported that Survivin increases the proliferation of mouse primary HPC and that this enhancing effect is on HPC proliferation is absent when p21 is functionally deleted, suggesting that p21 is required for Survivin to enhance HPC proliferation. In addition, ITD-Flt3 mutations that are normally expressed in patients with acute myeloid leukemia and associate poor prognosis increase expression of both Survivin and p21, implicating their involvement in aberrant proliferation of HPC expressing ITD-Flt3. Herein we have characterized the functional association between p21 and Survivin in normal and transformed cell proliferation. Antagonizing wild-type Survivin in mouse BaF3 cells by retrovirus transduction of a T34A dominant negative mutant Survivin or anti-sense increased p21 expression, even though Survivin requires p21 to enhance HPC proliferation. Ectopic p21 in Survivin+/+ primary mouse bone marrow cells increased the number of immunophenotypically defined c-kit+, lin− (KL) cells, which is consistent with a positive role of p21 in HPC proliferation, however; ectopic expression of p21 failed to increase HPC proliferation in Survivin deficient primary bone marrow cells, suggesting that p21 alone is not sufficient to substitute for Survivin’s enhancing function on normal HPC proliferation. Over-expression of ITD-Flt3 enhanced growth factor independent proliferation of primary mouse marrow c-kit+, Sca-1+, lin− (KSL) cell number; however, co-expression of p21 with ITD-Flt3 dramatically decreased the number of growth factor independent KSL cells (80±6% reduction: P&lt;0.01). Furthermore, the inhibitory effect of p21 on KLS proliferation was further enhanced by Survivin knockout bone marrow cells (64±5% reduction compared with presence of Survivin: P&lt;0.05). These findings indicate that Survivin and p21 have a overlapping but distinct roles in regulating normal HPC proliferation and that manipulating p21 and Survivin may represent a potential therapeutic target for acute leukemia cells expressing ITD-Flt3.
The Bone Morphogenetic Protein (BMP)-4 Is Involved in the Regulation of Human Megakaryocytic Differentiation during Thrombopoietin Signaling.
Authors: Nicolini Franck E , Jeanpierre Sandrine , Kaniewski Bastien , Dumontet Charles , Rimokh Ruth , Puisieux Alain , Maguer-Satta Véronique 
Published: April 2020

Abstract
It has been shown in the past that Activin A, BMP-2 and BMP-4, three members of the TGF-β family, are involved in the regulation of hematopoiesis and particularly erythropoiesis, in humans. In this study, we explored the role of these molecules in human megakaryopoiesis using an in vitro serum-free assay initiated with purified normal CD34+ human bone marrow (BM) cells (from allogeneic BM donors), that allows the analysis of the impact of such molecules on all stages of megakaryocytic differentiation. We could demonstrate for the first time, that in the absence of thrombopoietin (TPO), BMP-4 is able to induce CD34+ progenitor commitment and differentiation into megakaryocytes throughout all stages through means of cytology, flow cytometry, CFU and LTC-IC and ploidy assays, as well as in vitro platelet production. We analyzed as well the expression of megakaryocytic specific factors such as FOG-2, Fli-1 and PF4 by RQ-PCR, and PF4, BMP-4 secretion in culture supernatants. While we have previously shown that Activin A and BMP-2 are involved in the erythropoietic commitment even in the absence of erythropoietin, we were not able to demonstrate any effect of these molecules on megakaryopoietic commitment and differentiation. Using signaling pathways specific inhibitors such as AG490 (JAK-2 pathway inhibitor), PD98059 (ERK pathway inhibitor), LY294002 (PI3-K inhibitor) and Rapamycin (mTOR pathway inhibitor), we could show that BMP-4, as TPO, exerts its effects on human megakaryopoiesis involving specifically the JAK/STAT and mTOR signaling pathways. In addition, the specific inhibition of the BMP signaling pathway with blocking antibodies (CD34+ BM cells cultured in the presence of anti-TPO-R and mouse anti-BMP-4 Antibody), natural soluble inhibitors [such as FLRG (Follistatin related gene) protein or Follistatin], or soluble BMP-receptors (sBMPR-Ia, sBMPR-Ib) has revealed that TPO uses the BMP-4 pathway to induce the megakaryopoietic commitment of human BM CD34+ progenitors. Finally, we could demonstrate that TPO up-regulates a BMP-4 autocrine loop in megakaryocytic progenitors, by inducing their own production of BMP-4 associated to an up-regulation of BMP-receptor expression. In conclusion, this study illustrates that BMP-4 represents an important actor in the regulation of human megakaryopoiesis.
Transformation of E2A-Deficient Pluripotent Progenitors by BCR-ABL Generates Imatinib-Resistant Leukemic Stem Cells.
Authors: Minami Yosuke , Stuart Scott A. , Ikawa Tomokatsu , Abe Akihiro , Naoe Tomoki , Jamieson Catriona H.M. , Wang Jean Y.J. 
Published: April 2020

Abstract
Chronic myeloid leukemia (CML) is effectively treated with imatinib (imatinib mesylate, IM), a small molecule inhibitor of the BCR-ABL tyrosine kinase that is expressed in the entire hematopoietic compartment including stem cells (HSC) and progenitors. However, it is still unclear whether IM-therapy is able to eradicate BCR-ABL-positive HSC and progenitors. By transforming murine E2A-deficient pluripotent hematopoietic cells (Ikawa, et al., Immunity 04) with p210BCR-ABL, we determined that as few as 50 granulocyte macrophage progenitors (GMP)-like cells were sufficient to induce a transplantable CML-like disease in congenic mice, and that the leukemogenic GMP displayed higher levels of β-catenin activity than either the non-transformed GMP or the transformed nonGMP (most of which were myeloid differentiated cells), both in culture and in transplanted mouse bone marrow (Proc Natl Acad Sci USA 08, in press). The initiation of transformation required BCR-ABL kinase activity; however, whereas transformed nonGMP were sensitive to IM-treatment, expansion and survival of the leukemogenic progenitors in ex vivo-culture or in mice were not completely inhibited by IM-treatment. The drug resistance did not correlate with higher levels of BCR-ABL, mutations at ABL-kinase domain, induction of quiescence, stromal support or drug efflux. Additionally, the differential responses between the transformed progenitors and differentiated cells to IM-treatment were not affected by the restoration of E2A-function. These results imply that leukemic progenitors possess innate resistance to IM and that eradication of these cells with other drugs is required to cure CML. We are also investigating BCR-ABL-positive residual disease in HSC and progenitors of chronic phase CML patients on IM-therapy.
Activation of AKT1 in Hematopoietic Stem Cells Causes a Myeloproliferative Disease in a Tet-Inducible Mouse Model.
Authors: Brandts Christian , Rode Miriam , Lindtner Beate , Koehler Gabriele , Koschmieder Steffen , Mueller-Tidow Carsten , Berdel Wolfgang E. , Serve Hubert 
Published: April 2020

Abstract
Activating mutations in Flt3, N- and K-Ras have been reported in all AML subtypes and represent common molecular defects in de novo AML. We have previously shown that these mutations lead to constitutive AKT phosphorylation and activation. As a consequence, Akt phosphorylation is found in myeloid blasts of the majority of AML patients. We reasoned that constitutively active AKT may contribute to leukemia development, and therefore we assessed the contribution of AKT in oncogenic transformation in vivo. For this purpose, we established an inducible mouse model expressing myristylated AKT1 under the control of the scl-3′ enhancer (MyrAKT1). This system restricts activated AKT1 to endothelium, hematopoietic stem cells and myeloid lineage cells at a low but detectable level. About 40% of induced mice developed a myeloproliferative disorder after latencies of 7 to 22 months. Onset of disease was frequently associated with hemangioma formation, due to endothelial MyrAKT1 expression. The myeloproliferative disorder was associated with splenomegaly with increased extramedullary hematopoiesis, while the peripheral blood contained mature granulocytes. Furthermore, the stem cell and progenitor cell compartment in spleens and bone marrow of these mice was altered compared to control mice. Colony formation assays with MyrAKT1-expressing bone marrow suggested that overactivation of AKT1 enhanced proliferation. The AKT1-induced disease was transplantable by both bone marrow and spleen cells. These findings highlight the oncogenic capacity of constitutively activated AKT1 in vivo and indicate that AKT is an attractive target for therapeutic intervention in AML.
HTLV-1 Infection of Human Hematopoietic Stem Cells Induces a Novel T Cell Lymphoma in Humanized SCID Mice
Authors: Banerjee Prabal , Crawford Lindsey , Sieburg Michelle , Green Patrick , Beilke Mark A , Harrington William J , Lairmore Michael D , Feuer Gerold 
Published: April 2020

Abstract
Human T-lymphotropic virus type-1 (HTLV-1) is a human retrovirus linked to cancer and is the etiologic agent of Adult T-cell leukemia/lymphoma (ATLL), an aggressive CD4+/CD25+ T cell malignancy. The early molecular events induced by HTLV-1 infection as well as the role of various viral genes in the induction of leukemia remain unclear, predominantly due to the lack of an animal model that recapitulates ATLL development. HTLV-1 infection of humanized NOD/SCID mice (HTLV-1- HU-SCID) was achieved by inoculation of NOD/SCID mice with CD34+ hematopoietic progenitor cells and stem cells (CD34+ HP/HSCs) infected ex vivo with HTLV-1. HTLV-1-HU-NOD/SCIDmice consistently developed CD4+CD25+ T cell lymphomas with clinical characteristics associated with ATLL and infected mice showed hyperproliferation of infected human stem cells (CD34+CD38−) in the bone marrow. Inoculation of NOD/SCID mice withCD34+ HP/HSCs transduced with a lentivirus vector (LV) expressing the HTLV-1oncoprotein (Tax1) also developed CD4+CD25+ lymphomas. The HTLV-1 bZIP protein(HBZ), encoded by the minus strand of the HTLV-1 genome, is expressed in all ATLL cells and has been implicated in the maintenance of leukemogenesis. HBZ has previously been previously shown to interact with numerous cellular factors and can modulate Tax1 activity in vitro. To establish the role of HBZ in HTLV-1 replication and leukemogenesis in vivo, HU-SCID mice were infected with an infectious proviral clone lacking functional HBZ (HTLV-1ΔHBZ). HTLV-1ΔHBZ-infected HU-SCID mice developed lymphoproliferations with an immature preleukemic CD4−CD8−CD90+ phenotype starting at ~10 weeks post-reconstitution. In contrast wild type HTLV-1 infection reproducibly induces a mature CD4+CD25+ CD90− lymphoma. Lymphoma cells successfully engrafted naïve NOD/SCID mice when injected into the peritoneal cavity and these cells maintain the expression of viral proteins, gp46env and p19gag. HTLV-1 infection of CD34+ HP/HSCs and the recapitulation of a lymphoma similar to ATLL in HU-NOD/SCID mice suggest that hematopoietic stem cells provide a relevant cellular target and viral reservoir in vivo and that infection of these cells contribute to viral lymphomagenesis in humans. The HTLV-1-HU-SCID mouse model presents a compelling in vivo model to characterize molecular initiation and progression of events in the generation of ATL and to establish the role of HTLV-1 auxiliary proteins in viral pathogenesis.
The GATA-1 Cofactor FOG-1 Recruits NuRD to Promote Normal Erythroid and Megakaryocyte Development and Maintain Lineage Fidelity by Restricting Mast Cell Gene Expression.
Authors: Gregory Gregory D , Wang Yuhuan , Hong Wei , Miccio Annarita , Bersenev Alexey , Yu Xiang , Wang Hongxin , Choi John , Shelat Suresh , Tong Wei , Poncz Mortimer , Blobel Gerd 
Published: April 2020

Abstract
Tissue-specific nuclear factors can establish gene expression patterns in one cell lineage and suppress that of another. GATA-1 and its cofactor FOG-1 (Zfpm1) regulate erythroid and megakaryocyte development by activating and repressing gene transcription. We previously showed that a conserved motif within the N-terminus of FOG-1 binds the Nucleosome Remodeling and Deacetylase (NuRD) co-repressor complex. Here we report that mice bearing FOG-1 point mutations that disrupt the NuRD interaction display mild anemia with splenomegaly and macrothrombocytopenia, a phenotype reminiscent of that observed in animals bearing germline mutations that disrupt the GATA-1/FOG-1 interaction. Microarray studies revealed relatively few changes in gene expression pattern sin mutant erythroid cells and megakaryocytes. Among the most prominent findings was a marked increase in the levels of Gata2, which is normally silenced in mature erythroid cells. Strikingly, mutant erythroid cells also displayed activation of several genes of the mast cell lineage where FOG-1 is normally extinguished. Furthermore, mutant megakaryocytes misexpressed the same set of mast cell genes, suggesting that NuRD binding by FOG-1 is required to suppress mast cell fate throughout the erythro-megakaryocytic ontogeny. In agreement, prospectively isolated megakaryocytic-erythroid progenitors (MEP) not only exhibited elevated Gata2 and mast cell gene expression, but maintained a multilineage capacity, generating both mast cells and other myeloid lineage cells in culture. Upregulation of mast cell-specific genes is likely the combined consequence of the failure of mutant FOG-1 to function as a repressor and the high levels of GATA-2. Together, these results underscore the importance of the FOG-1-NuRD interaction as an effector of GATA-1 activity. In particular, recruitment of NuRD to GATA-1/FOG-1 regulated genes is required to optimize erythroid and megakaryocytic maturation and restrict a mast cell program in those lineages. More generally, recruitment of NuRD by lineage-specific transcription factors may be a common mechanism to narrow and focus gene expression during tissue maturation.
Accelerated Repair of Vascular Injury in Diabetes by TGF-β1 Modified Hematopoietic Stem Cells (HSC).
Authors: Bartelmez Stephen , Ruscetti Francis W , Iversen Patrick , Bhatwadekar Ashay , Grant Maria 
Published: April 2020

Abstract
Previously, we demonstrated that a transient blockade of endogenous transforming growth factor-beta type 1 (TGF-β1) in murine and human HSC accelerates bone marrow engraftment while dramatically reducing the number of HSC needed for long-term reconstitution. CD34+ cells give rise to endothelial progenitor cells (EPC) and have been shown to participate in the repair of damaged vasculature. CXCR4 is the receptor for stromal derived factor (SDF-1), a chemoattractant released by ischemic tissue that guides EPCs to damaged sites. In this study, we examined levels of TGF- β1 mRNA in CD34+ blood and bone marrow (BM) cells of diabetic and non diabetic individuals. We also treated CD34+ cells of diabetic and nondiabetic origin with antisense phosphorodiamidate morpholino oligomers (PMOs) to TGF-β1 and examined surface expression of CXCR-4, migratory response to SDF-1 as well as in vivo reparative function in a model of retinal ischemic injury. Our results show that CD34+ EPC from the blood of diabetic patients are markedly defective in their ability to repair damaged retinal vessels compared to control cells in contrast to CD34+ cells from the diabetic BM. Diabetic CD34+EPC from blood express elevated levels of TGF-β1 mRNA and have a blunted migratory response to SDF-1 compared to controls (p&lt;0.05 and p&lt;0.01 respectively). Transient (2–4 days) blockade of endogenous TGF-β1 using PMOs to TGF- β1 in diabetic CD34+/EPC increases CXCR-4 expression in these cells, enhances their migratory prowess and restores their ability to repair damaged retinal vessels. This approach is an enhanced autologous stem cell therapy based on a well studied, rapid and reversible modification of bone marrow CD34+EPCs derived from the diabetic patient.
Bone Morphogenetic Protein 4 Regulates Hematopoietic Stem Cell Maintenance in Vivo.
Authors: Goldman Devorah C. , Bailey Alexis S. , Pfaffle Dana L. , Christian Jan L. , Fleming William H. 
Published: April 2020

Abstract
The secreted signaling molecule Bone Morphogenetic Protein 4 (BMP4) is expressed by osteoblasts and other cell types that comprise the hematopoietic microenvironment. Therefore, we hypothesized that BMP4 may play an important regulatory role in the maintenance and function of hematopoietic stem cells (HSCs). As the deletion of BMP4 is lethal during early embryogenesis, we exploited a viable BMP4 hypomorph in which a point mutation in BMP4 reduces, but does not abolish the amount of active BMP4 ligand. In these mutants, peripheral blood cell lineages and bone marrow cellularity are normal during steady state conditions. However, consistent with our hypothesis, 40% fewer c-kit+, Sca-1+, lineage- (KSL) cells were present in the femurs of mutants (7.4 x103 ± 0.4 x103 SEM) than in age-and sex-matched wild-type (WT) controls (12.4 x103 ± 1.3 x103, p&lt;0.005). Transplantation of mutant KSL cells produced levels of hematopoietic engraftment indistinguishable from transplanted WT KSL cells, consistent with a stem cell extrinsic effect of BMP4. To functionally assess the mutant hematopoietic microenvironment, unfractionated WT bone marrow cells (BM) were transplanted into lethally irradiated mutants or WT controls. Although WT cells could engraft mutant primary recipients to the same degree as WT recipients, serial transplantation of these WT cells into secondary WT hosts revealed a marked depletion of hematopoietic reconstitution activity. Specifically, nearly a 4-fold reduction of donor cells was found in the peripheral blood of secondary recipients that received BM from reconstituted mutant hosts (p&lt;0.0005). To determine whether such defects in the mutant microenvironment exist in the absence of myeloablative conditioning and transplantation, a parabiotic mouse model was employed. CD45.1 WT mice were joined to CD45.2 BMP4 hypomorphs for 8 weeks and then separated. As early as one month following separation, a greater than 2- fold reduction in circulating WT donor cells was detected in mutant hosts relative to the number of mutant donor cells detected in the WT hosts (p&lt;0.005). Analysis of BM at 24 weeks following separation revealed a striking 23- fold reduction in WT donor hematopoietic cells in the mutant host BM compared to the number of mutant hematopoietic cells detected in WT host BM. Together, our findings reveal a novel, critical role for BMP4 in maintaining HSCs in vivo.
Urine Concentrating Ability in Infants with Sickle Cell Anemia: Baseline Data from the BABY HUG Trial.
Authors: Miller Scott T. , Wang Winfred C. , Iyer Rathi V. , Rana Sohail R , Lane Peter A. , Ware Russell E. , Rees Renee C ,   The BABY HUG Investigators
Published: April 2020

Abstract
A urine concentrating defect is quite common in sickle cell anemia (SCA), has its onset in early childhood, and may be reversible (with transfusion) until age 10 years. BABY HUG is an NHLBI-NICHD sponsored double-blind, placebo-controlled Phase III Clinical Trial (NCT00006400) designed to assess efficacy of hydroxyurea in preventing organ damage in young children with SCA (Hb SS or SβO thalassemia); primary endpoints are spleen function and glomerular filtration rate (GFR). Two hundred thirty-three infants, recruited without regard to disease severity, underwent eligibility screening. To assess urine concentrating ability as a secondary endpoint, parents were instructed to collect and save timed urine specimens from subjects after 4 to 10 hours of fluid deprivation (NPO) overnight for osmolality (OSM) determination. More prolonged deprivation was avoided due to safety concerns. A paired serum sample for OSM, urea nitrogen (BUN), and creatinine was obtained the next morning. All specimens were analyzed in a central laboratory. The analyses included 184 infants with a urine specimen and a reported period of fluid deprivation of at least four hours; 178 had concurrent sera. Mean age was 13.0±2.7 mo (range 7.5 – 17.9 mo) and mean duration of fluid deprivation was 7.4±2.4 hr (4–13 hr). Mean serum OSM was 286±6 mOsm/kg H2O and independent of age, height, weight, or duration NPO. Urine OSM (mean 410±152, median 433, range 58–794 mOsm/kg H2O) was significantly greater than serum osmolality (p&lt;0.0001) and correlated with duration NPO (p=0.001). One hundred forty-two infants (77.2%) concentrated urine (urine OSM &gt; [mean serum OSM + 1 SD]); twenty-two (12.0%) had urine/serum OSM ratio &gt; 2 and 54 (29.4%) had urine OSM &gt; 500 mOsm/L. In addition, five infants (2.7%) were isosthenuric (urine OSM within mean serum OSM ± 1 SD) and 37 (20.1%) hyposthenuric (&gt; 1 SD below mean serum OSM) despite instructions to withhold fluid. Urine OSM was associated with increasing 99mTc-DTPA GFR (p=0.024) and BUN (p&lt;0.0001), but not with serum OSM, age, height, weight or serum creatinine. We conclude that even with a variable, often limited, fluid deprivation challenge, 75 percent of young infants with SCD were able to concentrate urine. We anticipate that at the end of each infant’s two-year study drug treatment period parents will be more successful in achieving the recommended fluid deprivation and urine collection and that differences in concentrating ability between those taking hydroxyurea and those taking placebo will be discernable.