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Majewski IJ, Metcalf D, Mielke LA, Krebs DL, Ellis S, Carpinelli MR, Mifsud S, Di Rago L, Corbin J, Nicola NA, Hilton DJ, Alexander WS. A mutation in the translation initiation codon of Gata-1 disrupts megakaryocyte maturation and causes thrombocytopenia. Proc Natl Acad Sci U S A 2006; 103:14146-51. [PMID: 16966598 PMCID: PMC1599926 DOI: 10.1073/pnas.0606439103] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have generated mice from a N-ethyl-N-nitrosourea mutagenesis screen that carry a mutation in the translation initiation codon of Gata-1, termed Plt13, which is equivalent to mutations found in patients with acute megakaryoblastic leukemia and Down syndrome. The Gata-1 locus is present on the X chromosome in humans and in mice. Male mice hemizygous for the mutation (Gata-1Plt13/Y) failed to produce red blood cells and died during embryogenesis at a similar stage to Gata-1-null animals. Female mice that carry the Plt13 mutation are mosaic because of random inactivation of the X chromosome. Adult Gata-1Plt13/+ females were not anemic, but they were thrombocytopenic and accumulated abnormal megakaryocytes without a concomitant increase in megakaryocyte progenitor cells. Gata-1Plt13/+ mice contained large numbers of blast-like colony-forming cells, particularly in the fetal liver, but also in adult spleen and bone marrow, from which continuous mast cells lines were readily derived. Although the equivalent mutation to Gata-1Plt13 in humans results in production of GATA-1s, a short protein isoform initiated from a start codon downstream of the mutated initiation codon, Gata-1s was not detected in Gata-1Plt13/+ mice.
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Affiliation(s)
- Ian J. Majewski
- *The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia; and
| | - Donald Metcalf
- *The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia
| | - Lisa A. Mielke
- *The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia
| | - Danielle L. Krebs
- *The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia
| | - Sarah Ellis
- Peter MacCallum Cancer Centre, Trescowthick Research Laboratories, St. Andrew's Place, East Melbourne, Victoria 3002, Australia
| | - Marina R. Carpinelli
- *The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia
| | - Sandra Mifsud
- *The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia
| | - Ladina Di Rago
- *The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia
| | - Jason Corbin
- *The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia
| | - Nicos A. Nicola
- *The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia
| | - Douglas J. Hilton
- *The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia
| | - Warren S. Alexander
- *The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia
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202
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203
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Brink DS. Transient leukemia (transient myeloproliferative disorder, transient abnormal myelopoiesis) of Down syndrome. Adv Anat Pathol 2006; 13:256-62. [PMID: 16998319 DOI: 10.1097/01.pap.0000213039.93328.44] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Transient leukemia of Down syndrome (DS-TL), also known as transient myeloproliferative disorder of Down syndrome (DS) and transient abnormal myelopoiesis of DS, occurs in approximately 10% of DS neonates and in phenotypically normal neonates with trisomy 21 mosaicism. In DS-TL, peripheral blood analysis shows variable numbers of blasts and, usually, thrombocytopenia; other cytopenias are uncommon. Bone marrow characteristics of DS-TL are, likewise, variable, though (in contrast to other leukemias) the bone marrow blast differential can be lower than the peripheral blood blast differential. The blasts of DS-TL typically show light microscopic, ultrastructural, and flow cytometric evidence of megakaryocyte differentiation. DS-TL neonates have a approximately 15% risk of developing potentially fatal liver disease and show <10% incidence of hydrops fetalis. Additional manifestations of DS-TL include cutaneous involvement, hyperviscosity, myelofibrosis, cardiopulmonary failure, splenomegaly, and spleen necrosis. Despite its typical transient nature, 20% to 30% of DS-TL patients develop overt (nontransient) acute leukemia, usually within 3 years and typically of the M7 phenotype (acute megakaryoblastic leukemia). The pathogenesis of DS-TL (and of subsequent acute leukemia) involves mutation of GATA1 (on chromosome X), which normally encodes a transcription factor integral to normal development of erythroid, megakaryocytic, and basophilic/mast cell lines. The pathogenetic role of trisomy 21 in DS-TL is unclear. Though indications for chemotherapy in DS-TL have not been firmly established, the blasts of DS-TL are sensitive to low-dose cytosine arabinoside.
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Affiliation(s)
- David S Brink
- Department of Pathology, Saint Louis University School of Medicine, Saint Louis, MO 63104-1003, USA.
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204
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Pastos KM, Slayton WB, Rimsza LM, Young L, Sola-Visner MC. Differential effects of recombinant thrombopoietin and bone marrow stromal-conditioned media on neonatal versus adult megakaryocytes. Blood 2006; 108:3360-2. [PMID: 16888093 PMCID: PMC1895431 DOI: 10.1182/blood-2006-04-018036] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Umbilical cord blood (CB) is a valuable source of stem cells for transplantation, but CB transplantations are frequently complicated by delayed platelet engraftment. The reasons underlying this are unclear. We hypothesized that CB- and peripheral-blood (PB)-derived megakaryocytes (MKs) respond differently to the adult hematopoietic microenvironment and to thrombopoietin (Tpo). To test this, we cultured CB- and PB-CD34(+) cells in adult bone marrow stromal conditioned media (CM) or unconditioned media (UCM) with increasing concentrations of recombinant Tpo and compared the effects of these conditions on CB-versus PB-MKs. PB-MKs reached highest ploidy in response to UCM + 100 ng/mL rTpo, and the addition of CM inhibited their maturation. In contrast, CB-MKs reached highest ploidy in CM without rTpo, and high rTpo concentrations (> 0.1 ng/mL) inhibited their maturation. This is the first evidence that human neonatal and adult MKs have substantially different biologic responses to Tpo and potentially to other cytokines.
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Affiliation(s)
- Karen M Pastos
- Shands Cancer Center, University of Florida, Gainesville, FL, USA
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205
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Abstract
Identification of genes responsible for rare familial cases of cancer provides genetic and biochemical insight into the mechanisms of carcinogenesis at work in the more common, sporadic occurrences of the corresponding malignancy. Hematopoietic malignancy is no exception, and considerable evidence substantiates the role of genetic factors in the risk for leukemia. In a few instances, leukemia runs in families as a single gene, Mendelian disorder. Only a few genes conferring heritable risk for leukemia are known, however, and most are responsible for bone marrow failure syndromes. Thus, the identification of additional genetic risk factors for leukemia represents both a challenge and an opportunity. The high frequency of leukemia and transient leukemia in Down syndrome is beginning to yield the secrets of its unique clinical properties. The apparent phenomenon of anticipation (a declining of age of onset with each passing generation) in familial forms of bone marrow failure and leukemia is now affirmed through its association with mutations in genes responsible for maintaining telomere length. And, for the majority of leukemia cases, as with other common diseases that are not under the influence of a single, major gene, but rather result from the additive interactions of complex genetic and environmental factors, common variants in metabolic enzymes, and other genes awaiting discovery, are being teased out.
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Affiliation(s)
- Kathleen F Benson
- Division of Medical Genetics, Department of Medicine, University of Washington School of Medicine, Box 357720, Seattle, WA 98195, USA
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206
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Walters DK, Mercher T, Gu TL, O'Hare T, Tyner JW, Loriaux M, Goss VL, Lee KA, Eide CA, Wong MJ, Stoffregen EP, McGreevey L, Nardone J, Moore SA, Crispino J, Boggon TJ, Heinrich MC, Deininger MW, Polakiewicz RD, Gilliland DG, Druker BJ. Activating alleles of JAK3 in acute megakaryoblastic leukemia. Cancer Cell 2006; 10:65-75. [PMID: 16843266 DOI: 10.1016/j.ccr.2006.06.002] [Citation(s) in RCA: 242] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 04/21/2006] [Accepted: 06/01/2006] [Indexed: 12/18/2022]
Abstract
Tyrosine kinases are aberrantly activated in numerous malignancies, including acute myeloid leukemia (AML). To identify tyrosine kinases activated in AML, we developed a screening strategy that rapidly identifies tyrosine-phosphorylated proteins using mass spectrometry. This allowed the identification of an activating mutation (A572V) in the JAK3 pseudokinase domain in the acute megakaryoblastic leukemia (AMKL) cell line CMK. Subsequent analysis identified two additional JAK3 alleles, V722I and P132T, in AMKL patients. JAK3(A572V), JAK3(V722I), and JAK3(P132T) each transform Ba/F3 cells to factor-independent growth, and JAK3(A572V) confers features of megakaryoblastic leukemia in a murine model. These findings illustrate the biological importance of gain-of-function JAK3 mutations in leukemogenesis and demonstrate the utility of proteomic approaches to identifying clinically relevant mutations.
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MESH Headings
- Alleles
- Animals
- Apoptosis/drug effects
- Benzamides
- Cell Line, Tumor
- Cell Proliferation/drug effects
- Cell Survival/drug effects
- Humans
- Imatinib Mesylate
- Janus Kinase 2
- Janus Kinase 3
- K562 Cells
- Leukemia, Experimental/genetics
- Leukemia, Experimental/metabolism
- Leukemia, Experimental/pathology
- Leukemia, Megakaryoblastic, Acute/genetics
- Leukemia, Megakaryoblastic, Acute/metabolism
- Leukemia, Megakaryoblastic, Acute/pathology
- Mice
- Mice, Inbred C57BL
- Models, Molecular
- Mutant Proteins/chemistry
- Mutant Proteins/genetics
- Mutant Proteins/metabolism
- Phosphorylation/drug effects
- Piperazines/pharmacology
- Protein Kinase Inhibitors/pharmacology
- Protein Structure, Tertiary/genetics
- Protein-Tyrosine Kinases/antagonists & inhibitors
- Protein-Tyrosine Kinases/genetics
- Protein-Tyrosine Kinases/metabolism
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins/metabolism
- Pyrimidines/pharmacology
- RNA, Small Interfering/genetics
- TYK2 Kinase
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207
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Mercher T, Wernig G, Moore SA, Levine RL, Gu TL, Fröhling S, Cullen D, Polakiewicz RD, Bernard OA, Boggon TJ, Lee BH, Gilliland DG. JAK2T875N is a novel activating mutation that results in myeloproliferative disease with features of megakaryoblastic leukemia in a murine bone marrow transplantation model. Blood 2006; 108:2770-9. [PMID: 16804112 PMCID: PMC1895587 DOI: 10.1182/blood-2006-04-014712] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Acute megakaryoblastic leukemia (AMKL) is a subtype of acute myeloid leukemia associated with a poor prognosis. However, there are relatively few insights into the genetic etiology of AMKL. We developed a screening assay for mutations that cause AMKL, based on the hypothesis that constitutive activation of STAT5 would be a biochemical indicator of mutation in an upstream effector tyrosine kinase. We screened human AMKL cell lines for constitutive STAT5 activation, and then used an approach combining mass spectrometry identification of tyrosine phosphorylated proteins and growth inhibition in the presence of selective small molecule tyrosine kinase inhibitors that would inform DNA sequence analysis of candidate tyrosine kinases. Using this strategy, we identified a new JAK2T875N mutation in the AMKL cell line CHRF-288-11. JAK2T875N is a constitutively activated tyrosine kinase that activates downstream effectors including STAT5 in hematopoietic cells in vitro. In a murine transplant model, JAK2T875N induced a myeloproliferative disease characterized by features of AMKL, including megakaryocytic hyperplasia in the spleen; impaired megakaryocyte polyploidization; and increased reticulin fibrosis of the bone marrow and spleen. These findings provide new insights into pathways and therapeutic targets that contribute to the pathogenesis of AMKL.
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MESH Headings
- Animals
- Bone Marrow Transplantation
- Cell Differentiation
- Cell Line, Tumor
- Colony-Forming Units Assay
- Enzyme Activation
- Humans
- Immunophenotyping
- Janus Kinase 2
- K562 Cells
- Leukemia, Megakaryoblastic, Acute/enzymology
- Leukemia, Megakaryoblastic, Acute/genetics
- Leukemia, Megakaryoblastic, Acute/pathology
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Models, Molecular
- Mutation
- Myeloproliferative Disorders/enzymology
- Myeloproliferative Disorders/etiology
- Myeloproliferative Disorders/genetics
- Myeloproliferative Disorders/pathology
- Phosphorylation
- Protein Conformation
- Protein-Tyrosine Kinases/chemistry
- Protein-Tyrosine Kinases/genetics
- Protein-Tyrosine Kinases/metabolism
- Proto-Oncogene Proteins/chemistry
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins/metabolism
- STAT5 Transcription Factor/metabolism
- Transduction, Genetic
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Affiliation(s)
- Thomas Mercher
- Division of Hematology, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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208
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Hollanda LM, Lima CSP, Cunha AF, Albuquerque DM, Vassallo J, Ozelo MC, Joazeiro PP, Saad STO, Costa FF. An inherited mutation leading to production of only the short isoform of GATA-1 is associated with impaired erythropoiesis. Nat Genet 2006; 38:807-12. [PMID: 16783379 DOI: 10.1038/ng1825] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Accepted: 05/16/2006] [Indexed: 11/10/2022]
Abstract
Acquired somatic mutations in exon 2 of the hematopoietic transcription factor GATA-1 have been found in individuals with Down syndrome with both transient myeloproliferative disorder and acute megakaryoblastic leukemia. These mutations prevent the synthesis of the full-length protein but allow the synthesis of its short isoform, GATA-1s. Experiments in mice suggest that GATA-1s supports normal adult megakaryopoiesis, platelet formation and erythropoiesis. Here we report a mutation, 332G --> C, in exon 2 of GATA1, leading to the synthesis of only the short isoform in seven affected males from two generations of a family. Hematological profiles of affected males demonstrate macrocytic anemia, normal platelet counts and neutropenia in most cases. Altogether, data suggest that GATA-1s alone, produced in low or normal levels, is not sufficient to support normal erythropoiesis. Moreover, this is the first study to indicate that a germline splicing mutation does not lead to leukemia in the absence of other cooperating events, such as Down syndrome.
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Affiliation(s)
- Luciana M Hollanda
- Department of Internal Medicine, Hemocentro, School of Medical Science, Universidade Estadual de Campinas, Campinas, São Paulo 13083-970, Brazil
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209
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Bourquin JP, Subramanian A, Langebrake C, Reinhardt D, Bernard O, Ballerini P, Baruchel A, Cavé H, Dastugue N, Hasle H, Kaspers GL, Lessard M, Michaux L, Vyas P, van Wering E, Zwaan CM, Golub TR, Orkin SH. Identification of distinct molecular phenotypes in acute megakaryoblastic leukemia by gene expression profiling. Proc Natl Acad Sci U S A 2006; 103:3339-44. [PMID: 16492768 PMCID: PMC1413912 DOI: 10.1073/pnas.0511150103] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Individuals with Down syndrome (DS) are predisposed to develop acute megakaryoblastic leukemia (AMKL), characterized by expression of truncated GATA1 transcription factor protein (GATA1s) due to somatic mutation. The treatment outcome for DS-AMKL is more favorable than for AMKL in non-DS patients. To gain insight into gene expression differences in AMKL, we compared 24 DS and 39 non-DS AMKL samples. We found that non-DS-AMKL samples cluster in two groups, characterized by differences in expression of HOX/TALE family members. Both of these groups are distinct from DS-AMKL, independent of chromosome 21 gene expression. To explore alterations of the GATA1 transcriptome, we used cross-species comparison with genes regulated by GATA1 expression in murine erythroid precursors. Genes repressed after GATA1 induction in the murine system, most notably GATA-2, MYC, and KIT, show increased expression in DS-AMKL, suggesting that GATA1s fail to repress this class of genes. Only a subset of genes that are up-regulated upon GATA1 induction in the murine system show increased expression in DS-AMKL, including GATA1 and BACH1, a probable negative regulator of megakaryocytic differentiation located on chromosome 21. Surprisingly, expression of the chromosome 21 gene RUNX1, a known regulator of megakaryopoiesis, was not elevated in DS-AMKL. Our results identify relevant signatures for distinct AMKL entities and provide insight into gene expression changes associated with these related leukemias.
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Affiliation(s)
- Jean-Pierre Bourquin
- Department of Pediatric Oncology, Dana–Farber Cancer Institute and Children’s Hospital, Harvard Medical School, Boston, MA 02115
- Department of Pediatric Oncology, Universitäts-Kinderklinik Zurich, CH-8032 Zurich, Switzerland
| | - Aravind Subramanian
- The Broad Institute of Massachusetts Institute of Technology and Harvard University, Cambridge, MA 02141
| | | | - Dirk Reinhardt
- Medizinische Hochschule Hannover, D-30625 Hannover, Germany
| | - Olivier Bernard
- Institut National de la Santé et de la Recherche Médicale E0210, Hôpital Necker, F-75015 Paris, France
| | - Paola Ballerini
- Service d’Hématologie Biologique, Hôpital A Trousseau, F-75012 Paris, France
| | - André Baruchel
- Services d’Hématologie Pédiatrique et Adulte, Laboratoire Central d’Hématologie, Hôpital Saint-Louis, 75010 Paris, France
| | - Hélène Cavé
- Laboratoire de Biochimie Génétique, Hôpital Robert Debré, F-75019 Paris, France
| | - Nicole Dastugue
- Laboratoire d’Hématologie, Génétique des Hémopathies, Hôpital Purpan, F-31059 Toulouse, France
| | - Henrik Hasle
- Skejby Hospital, Aarhus University, 8200 Aarhus N, Denmark
| | - Gertjan L. Kaspers
- Department of Pediatric Hematology/Oncology, Vrije Universiteit Medical Center, 1007 MB Amsterdam, The Netherlands
- Dutch Childhood Oncology Group, The Hague, The Netherlands
| | - Michel Lessard
- Laboratoire d’Hématologie, Hôpital de Hautepierre, Hôpitaux Universitaires de Strasbourg, F-67098 Strasbourg, France
| | | | - Paresh Vyas
- Department of Haematology, Oxford Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
| | | | - Christian M. Zwaan
- Dutch Childhood Oncology Group, The Hague, The Netherlands
- Department of Pediatric Oncology, Erasmus Medical Center, 3000 CB Rotterdam, The Netherlands; and
| | - Todd R. Golub
- Department of Pediatric Oncology, Dana–Farber Cancer Institute and Children’s Hospital, Harvard Medical School, Boston, MA 02115
- The Broad Institute of Massachusetts Institute of Technology and Harvard University, Cambridge, MA 02141
| | - Stuart H. Orkin
- Department of Pediatric Oncology, Dana–Farber Cancer Institute and Children’s Hospital, Harvard Medical School, Boston, MA 02115
- To whom correspondence should be addressed. E-mail:
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210
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Abstract
Platelets, derived from megakaryocytes, have an essential role in thrombosis and hemostasis. Over the past 10 years, a great deal of new information has been obtained concerning the various aspects of hematopoiesis necessary to maintain a steady-state platelet level to support physiologic hemostasis. Here we discuss the differentiation of HSCs into megakaryocytes, with emphasis on the key cytokine signaling pathways and hematopoietic transcription factors. Recent insight into these processes elucidates the molecular bases of numerous acquired and inherited hematologic disorders. It is anticipated that the growing knowledge in these areas may be exploited for new therapeutic strategies to modulate both platelet numbers and their thrombogenicity.
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Affiliation(s)
- Liyan Pang
- Division of Hematology, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Pennsylvania 19104, USA.
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211
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Abstract
Abnormal number of chromosomes, aneuploidy, is the most common abnormality in leukemia and cancer. However, the casual relationship between aneuploidy and cancer is unclear. Additional copies of chromosome 21 are frequently found in leukemic cells. Constitutional trisomy 21 that characterizes Down Syndrome is associated with markedly increased risk for childhood leukemia. In this perspective I review recent studies that suggest that constitutional trisomy 21 promotes leukemic transformation during fetal hematopoiesis. As most of childhood leukemias arise in-utero, these studies are of general relevance to sporadic childhood leukemias.
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Affiliation(s)
- Shai Izraeli
- Department of Pediatric Hemato-Oncology, Cancer Research Center, Safra's Children's Hospital, Sheba Medical Center, Sackler Faculty of Medicine, Tel-Aviv University, Israel.
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212
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Stachura DL, Chou ST, Weiss MJ. Early block to erythromegakaryocytic development conferred by loss of transcription factor GATA-1. Blood 2006; 107:87-97. [PMID: 16144799 PMCID: PMC1895362 DOI: 10.1182/blood-2005-07-2740] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Accepted: 08/24/2005] [Indexed: 12/31/2022] Open
Abstract
Transcription factor GATA-1 is essential at multiple stages of hematopoiesis. Murine gene targeting and analysis of naturally occurring human mutations demonstrate that GATA-1 drives the maturation of committed erythroid precursors and megakaryocytes. Prior studies also suggest additional, poorly defined, roles for GATA-1 at earlier stages of erythromegakaryocytic differentiation. To investigate these functions further, we stimulated Gata1- murine embryonic stem-cell-derived hematopoietic cultures with thrombopoietin, a multistage cytokine. Initially, the cultures generated a wave of mutant megakaryocytes. However, these were rapidly overgrown by a unique population of thrombopoietin-dependent blasts that express immature markers and proliferate indefinitely. Importantly, on restoration of GATA-1 function, these cells differentiated into both erythroid and megakaryocytic lineages, suggesting that they represent bipotential progenitors. Identical cells are also present in vivo, as indicated by flow cytometry and culture analysis of fetal livers from Gata1- chimeric mice. Our findings indicate that loss of GATA-1 impairs the maturation of megakaryocyte-erythroid progenitors. This defines a new role for GATA-1 at a relatively early stage of hematopoiesis and provides potential insight into recent discoveries that human GATA1 mutations promote acute megakaryoblastic leukemia, a clonal malignancy with features of both erythroid and megakaryocyte maturation.
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Affiliation(s)
- David L Stachura
- Cell and Molecular Biology Graduate Program, The University of Pennsylvania School of Medicine, Philadelphia, PA, USA
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213
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Sun L, Hwang WYK, Aw SE. Biological characteristics of megakaryocytes: Specific lineage commitment and associated disorders. Int J Biochem Cell Biol 2006; 38:1821-6. [PMID: 16730215 DOI: 10.1016/j.biocel.2006.03.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2005] [Revised: 03/21/2006] [Accepted: 03/21/2006] [Indexed: 10/24/2022]
Abstract
Megakayocytes (Megakaryocytes) are among the rarest type of haematopoietic cells and highly specialized precursors for platelets. Normal mature megakaryocytes are, perhaps, the largest cells in the marrow. In contrast, their annucleated platelets progeny are the smallest subcellular fragments in the circulation, which in spite of their size, play crucial roles in thrombostasis and haemostasis. Megakaryopoiesis involves complicated and multi-step biological processes. Research over the last decade has resulted in certain important new discoveries, such as the specific megakaryocyte-forming haematopoietic stem cell (HSC) subpopulation, thrombopoietin (Tpo), formation and release of platelets, etc. Substantial understanding of the specific lineage commitment, differentiation, and the molecular regulatory mechanisms of megakaryopoiesis has also been achieved. Despite existing controversies and questions, megakaryopoiesis remains an exciting field in biomedical research. Certain recent biological findings as well as future research in megakaryopoiesis are summarised in this article. Certain pathological changes associated with megakaryocytes, such as immune thrombocytopenia purpura (ITP), acute megakayoblastic leukaemia, etc., are also discussed in this article.
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Affiliation(s)
- Li Sun
- Department of Clinical Research, Singapore General Hospital, Outram Road, Singapore 169608, Republic of Singapore.
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214
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Abstract
The development of mature blood cells from hematopoietic stem cells is regulated by transcription factors that control and coordinate the expression of lineage-specific genes. The GATA family consists of six transcription factors that function in hematopoietic and endodermal development. Among them, GATA-1 is expressed in erythroid, megakaryocytic, eosinophil and mast cell lineages, and GATA-2 is expressed in stem and progenitor cells, at more immature stage compared with GATA-1. Based on the characteristic phenotypes of GATA-1 and GATA-2 mutant mice, it has been suggested that mutations of these GATA genes in humans may result in the onset of certain clinical diseases. To date, mutations of GATA-1 gene have been found in inherited anemia and thrombocytopenia, and Down syndrome-related acute leukemia, which exhibits megakaryocytic phenotypes and frequently occurs in patients with Down syndrome. In contrast, no mutation of GATA-2 gene has been identified in hematological diseases; however, we found the expression level of GATA-2 is significantly decreased in CD34 positive cells in patients with aplastic anemia. Since GATA-2 functions in the proliferation of hematopoietic stem cells, the reduction of GATA-2 expression in CD34 positive cells may result in the decreased number of hematopoietic stem cells, which is the characteristic feature of aplastic anemia. Based on these lines of evidence, some types of hematological diseases may be defined as transcription factor diseases.
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Affiliation(s)
- Hideo Harigae
- Department of Rheumatology and Hematology, Tohoku University Graduate School of Medicine, Sendai, Japan.
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215
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Kuhl C, Atzberger A, Iborra F, Nieswandt B, Porcher C, Vyas P. GATA1-mediated megakaryocyte differentiation and growth control can be uncoupled and mapped to different domains in GATA1. Mol Cell Biol 2005; 25:8592-606. [PMID: 16166640 PMCID: PMC1265752 DOI: 10.1128/mcb.25.19.8592-8606.2005] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2005] [Revised: 05/18/2005] [Accepted: 07/10/2005] [Indexed: 11/20/2022] Open
Abstract
The DNA-binding hemopoietic zinc finger transcription factor GATA1 promotes terminal megakaryocyte differentiation and restrains abnormal immature megakaryocyte expansion. How GATA1 coordinates these fundamental processes is unclear. Previous studies of synthetic and naturally occurring mutant GATA1 molecules demonstrate that DNA-binding and interaction with the essential GATA1 cofactor FOG-1 (via the N-terminal finger) are required for gene expression in terminally differentiating megakaryocytes and for platelet production. Moreover, acquired mutations deleting the N-terminal 84 amino acids are specifically detected in megakaryocytic leukemia in human Down syndrome patients. In this study, we have systematically dissected GATA1 domains required for platelet release and control of megakaryocyte growth by ectopically expressing modified GATA1 molecules in primary GATA1-deficient fetal megakaryocyte progenitors. In addition to DNA binding, distinct N-terminal regions, including residues in the first 84 amino acids, promote platelet release and restrict megakaryocyte growth. In contrast, abrogation of GATA1-FOG-1 interaction leads to loss of differentiation, but growth of blocked immature megakaryocytes is controlled. Thus, distinct GATA1 domains regulate terminal megakaryocyte gene expression leading to platelet release and restrain megakaryocyte growth, and these processes can be uncoupled.
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Affiliation(s)
- Christiane Kuhl
- Department of Hematology, Weatherall Institute of Molecular Medicine, University of Oxford and John Radcliffe Hospital, Oxford OX3 9DU, United Kingdom
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Groet J, Mulligan C, Spinelli M, Serra A, McElwaine S, Cotter FE, Dagna-Bricarelli F, Saglio G, Basso G, Nizetic D. Independent clones at separable stages of differentiation, bearing different GATA1 mutations, in the same TMD patient with Down syndrome. Blood 2005; 106:1887-8. [PMID: 16113234 DOI: 10.1182/blood-2005-03-1071] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Hellebostad M, Carpenter E, Hasle H, Mitchell C, Vyas P. GATA1 mutation analysis demonstrates two distinct primary leukemias in a child with down syndrome; implications for leukemogenesis. J Pediatr Hematol Oncol 2005; 27:408-9. [PMID: 16012335 DOI: 10.1097/01.mph.0000172223.04694.c4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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