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Semin Thromb Hemost 2004; 30(4): 389-398
DOI: 10.1055/s-2004-833474
Copyright © 2004 by Thieme Medical Publishers, Inc., 333 Seventh Avenue, New York, NY 10001, USA.

Molecular Mechanisms of Megakaryocyte Differentiation

Harald Schulze1 , 2 , Ramesh A. Shivdasani1 , 2 , 3
  • 1Departments of Medical Oncology and Cancer Biology, Dana-Farber Cancer Institute; Departments of Medicine, Boston, Massachusetts
  • 2Harvard Medical School, Boston, Massachusetts
  • 3Associate Professor of Medicine, Brigham and Women's Hospital, Boston, Massachusetts
Further Information

Publication History

Publication Date:
08 September 2004 (online)

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Each bone marrow megakaryocyte (MK) releases thousands of platelets into the circulation, and the underlying molecular and cellular mechanisms recently have received intense scrutiny. Genetic studies are beginning to clarify the mechanisms by which transcription factors help distinguish MK progenitors from other blood cell lineages and subsequently confer unique cellular properties. Other investigations demonstrate that platelets are assembled de novo during a terminal phase of MK differentiation in which the cell extends cytoplasmic projections known as proplatelets. This review focuses on the roles of selected transcription factors with key roles in MK differentiation, and on human and murine models of thrombocytopenia that result from impaired MK differentiation. The findings we review help construct a framework to appreciate thrombopoietic mechanisms in the context of underlying lineage and morphologic transitions. Many of these mechanisms are unique to MKs but appear to rely both on genes that are expressed only in that lineage and others that are expressed widely.

KEYWORDS

Platelet - megakaryocyte - proplatelet - transcription factors - thrombopoiesis

REFERENCES

  • 1 Radley J M, Scurfield G. The mechanism of platelet release.  Blood. 1980;  56 996-999
    PubMedGoogle Scholar
  • 2 Italiano Jr J E, Lecine P, Shivdasani R A, Hartwig J H. Blood platelets are assembled principally at the ends of proplatelet processes produced by differentiated megakaryocytes.  J Cell Biol. 1999;  147 1299-1312
    CrossrefPubMedGoogle Scholar
  • 3 Shivdasani R A, Fujiwara Y, McDevitt M A, Orkin S H. A lineage-selective knockout establishes the critical role of transcription factor GATA-1 in megakaryocyte growth and platelet development.  EMBO J. 1997;  16 3965-3973
    CrossrefPubMedGoogle Scholar
  • 4 Nichols K E, Crispino J D, Poncz M et al.. Familial dyserythropoietic anaemia and thrombocytopenia due to an inherited mutation in GATA1.  Nat Genet. 2000;  24 266-270
    CrossrefPubMedGoogle Scholar
  • 5 Freson K, Devriendt K, Matthijs G et al.. Platelet characteristics in patients with X-linked macrothrombocytopenia because of a novel GATA1 mutation.  Blood. 2001;  98 85-92
    CrossrefPubMedGoogle Scholar
  • 6 Tsang A P, Fujiwara Y, Hom D B, Orkin S H. Failure of megakaryopoiesis and arrested erythropoiesis in mice lacking the GATA-1 transcriptional cofactor FOG.  Genes Dev. 1998;  12 1176-1188
    CrossrefPubMedGoogle Scholar
  • 7 Chang A N, Cantor A B, Fujiwara Y et al.. GATA-factor dependence of the multitype zinc-finger protein FOG-1 for its essential role in megakaryopoiesis.  Proc Natl Acad Sci USA. 2002;  99 9237-9242
    CrossrefPubMedGoogle Scholar
  • 8 Cantor A B, Katz S G, Orkin S H. Distinct domains of the GATA-1 cofactor FOG-1 differentially influence erythroid versus megakaryocytic maturation.  Mol Cell Biol. 2002;  22 4268-4279
    CrossrefPubMedGoogle Scholar
  • 9 Wechsler J, Greene M, McDevitt M A et al.. Acquired mutations in GATA1 in the megakaryoblastic leukemia of Down syndrome.  Nat Genet. 2002;  32 148-152
    CrossrefPubMedGoogle Scholar
  • 10 Mundschau G, Gurbuxani S, Gamis A S, Greene M E, Arceci R J, Crispino J D. Mutagenesis of GATA1 is an initiating event in Down syndrome leukemogenesis.  Blood. 2003;  101 4298-4300
    CrossrefPubMedGoogle Scholar
  • 11 Rainis L, Bercovich D, Strehl S et al.. Mutations in exon 2 of GATA1 are early events in megakaryocytic malignancies associated with trisomy 21.  Blood. 2003;  102 981-986
    CrossrefPubMedGoogle Scholar
  • 12 Hitzler J K, Cheung J, Li Y, Scherer S W, Zipursky A. GATA1 mutations in transient leukemia and acute megakaryoblastic leukemia of Down syndrome.  Blood. 2003;  101 4301-4304
    CrossrefPubMedGoogle Scholar
  • 13 Xu G, Nagano M, Kanezaki R et al.. Frequent mutations in the GATA-1 gene in the transient myeloproliferative disorder of Down syndrome.  Blood. 2003;  102 2960-2968
    CrossrefPubMedGoogle Scholar
  • 14 Lemarchandel V, Ghysdael J, Mignotte V, Rahuel C, Romeo P H. GATA and Ets cis-acting sequences mediate megakaryocyte-specific expression.  Mol Cell Biol. 1993;  13 668-676
    PubMedGoogle Scholar
  • 15 Deveaux S, Filipe A, Lemarchandel V, Ghysdael J, Romeo P H, Mignotte V. Analysis of the thrombopoietin receptor (MPL) promoter implicates GATA and Ets proteins in the coregulation of megakaryocyte-specific genes.  Blood. 1996;  87 4678-4685
    PubMedGoogle Scholar
  • 16 Minami T, Tachibana K, Imanishi T, Doi T. Both Ets-1 and GATA-1 are essential for positive regulation of platelet factor 4 gene expression.  Eur J Biochem. 1998;  258 879-889
    CrossrefPubMedGoogle Scholar
  • 17 Gaines P, Geiger J N, Knudsen G, Seshasayee D, Wojchowski D M. GATA-1- and FOG-dependent activation of megakaryocytic alpha IIB gene expression.  J Biol Chem. 2000;  275 34114-34121
    CrossrefPubMedGoogle Scholar
  • 18 Holmes M L, Bartle N, Eisbacher M, Chong B H. Cloning and analysis of the thrombopoietin-induced megakaryocyte-specific glycoprotein VI promoter and its regulation by GATA-1, Fli-1, and Sp1.  J Biol Chem. 2002;  277 48333-48341
    CrossrefPubMedGoogle Scholar
  • 19 Wang X, Crispino J D, Letting D L, Nakazawa M, Poncz M, Blobel G A. Control of megakaryocyte-specific gene expression by GATA-1 and FOG-1: role of Ets transcription factors.  EMBO J. 2002;  21 5225-5234
    CrossrefPubMedGoogle Scholar
  • 20 Blobel G A, Nakajima T, Eckner R, Montminy M, Orkin S H. CREB-binding protein cooperates with transcription factor GATA-1 and is required for erythroid differentiation.  Proc Natl Acad Sci USA. 1998;  95 2061-2066
    CrossrefPubMedGoogle Scholar
  • 21 Breton-Gorius J, Favier R, Guichard J et al.. A new congenital dysmegakaryopoietic thrombocytopenia (Paris-Trousseau) associated with giant platelet alpha-granules and chromosome 11 deletion at 11q23.  Blood. 1995;  85 1805-1814
    PubMedGoogle Scholar
  • 22 Krishnamurti L, Neglia J P, Nagarajan R et al.. Paris-Trousseau syndrome platelets in a child with Jacobsen’s syndrome.  Am J Hematol. 2001;  66 295-299
    CrossrefPubMedGoogle Scholar
  • 23 Hart A, Melet F, Grossfeld P et al.. Fli-1 is required for murine vascular and megakaryocytic development and is hemizygously deleted in patients with thrombocytopenia.  Immunity. 2000;  13 167-177
    CrossrefPubMedGoogle Scholar
  • 24 Kawada H, Ito T, Pharr P N, Spyropoulos D D, Watson D K, Ogawa M. Defective megakaryopoiesis and abnormal erythroid development in Fli-1 gene-targeted mice.  Int J Hematol. 2001;  73 463-468
    PubMedGoogle Scholar
  • 25 Eisbacher M, Holmes M L, Newton A et al.. Protein-protein interaction between Fli-1 and GATA-1 mediates synergistic expression of megakaryocyte-specific genes through cooperative DNA binding.  Mol Cell Biol. 2003;  23 3427-3441
    CrossrefPubMedGoogle Scholar
  • 26 Rekhtman N, Radparvar F, Evans T, Skoultchi A I. Direct interaction of hematopoietic transcription factors PU.1 and GATA-1: functional antagonism in erythroid cells.  Genes Dev. 1999;  13 1398-1411
    PubMedGoogle Scholar
  • 27 Zhang P, Behre G, Pan J et al.. Negative cross-talk between hematopoietic regulators: GATA proteins repress PU.1  Proc Natl Acad Sci USA. 1999;  96 8705-8710
    CrossrefPubMedGoogle Scholar
  • 28 Behre G, Whitmarsh A J, Coghlan M P et al.. c-Jun is a JNK-independent coactivator of the PU.1 transcription factor.  J Biol Chem. 1999;  274 4939-4946
    CrossrefPubMedGoogle Scholar
  • 29 Elagib K E, Racke F K, Mogass M, Khetawat R, Delehanty L L, Goldfarb A N. RUNX1 and GATA-1 coexpression and cooperation in megakaryocytic differentiation.  Blood. 2003;  101 4333-4341
    CrossrefPubMedGoogle Scholar
  • 30 Waltzer L, Ferjoux G, Bataille L, Haenlin M. Cooperation between the GATA and RUNX factors Serpent and Lozenge during Drosophila hematopoiesis.  EMBO J. 2003;  22 6516-6525
    CrossrefPubMedGoogle Scholar
  • 31 Song W J, Sullivan M G, Legare R D et al.. Haploinsufficiency of CBFA2 causes familial thrombocytopenia with propensity to develop acute myelogenous leukaemia.  Nat Genet. 1999;  23 166-175
    PubMedGoogle Scholar
  • 32 Michaud J, Wu F, Osato M et al.. In vitro analyses of known and novel RUNX1/AML1 mutations in dominant familial platelet disorder with predisposition to acute myelogenous leukemia: implications for mechanisms of pathogenesis.  Blood. 2002;  99 1364-1372
    CrossrefPubMedGoogle Scholar
  • 33 Mucenski M L, McLain K, Kier A B et al.. A functional c-myb gene is required for normal murine fetal hepatic hematopoiesis.  Cell. 1991;  65 677-689
    CrossrefPubMedGoogle Scholar
  • 34 Emambokus N, Vegiopoulos A, Harman B, Jenkinson E, Anderson G, Frampton J. Progression through key stages of haemopoiesis is dependent on distinct threshold levels of c-Myb.  EMBO J. 2003;  22 4478-4488
    CrossrefPubMedGoogle Scholar
  • 35 Kasper L H, Boussouar F, Ney P A et al.. A transcription-factor-binding surface of coactivator p300 is required for haematopoiesis.  Nature. 2002;  419 738-743
    CrossrefPubMedGoogle Scholar
  • 36 Takahashi T, Suwabe N, Dai P, Yamamoto M, Ishii S, Nakano T. Inhibitory interaction of c-Myb and GATA-1 via transcriptional co-activator CBP.  Oncogene. 2000;  19 134-140
    CrossrefPubMedGoogle Scholar
  • 37 Lecine P, Blank V, Shivdasani R. Characterization of the hematopoietic transcription factor NF-E2 in primary murine megakaryocytes.  J Biol Chem. 1998;  273 7572-7578
    CrossrefPubMedGoogle Scholar
  • 38 Shavit J A, Motohashi H, Onodera K, Akasaka J, Yamamoto M, Engel J D. Impaired megakaryopoiesis and behavioral defects in mafG-null mutant mice.  Genes Dev. 1998;  12 2164-2174
    PubMedGoogle Scholar
  • 39 Onodera K, Shavit J A, Motohashi H, Yamamoto M, Engel J D. Perinatal synthetic lethality and hematopoietic defects in compound mafG::mafK mutant mice.  EMBO J. 2000;  19 1335-1345
    CrossrefPubMedGoogle Scholar
  • 40 Shivdasani R A, Rosenblatt M F, Zucker-Franklin D et al.. Transcription factor NF-E2 is required for platelet formation independent of the actions of thrombopoietin/MGDF in megakaryocyte development.  Cell. 1995;  81 695-704
    CrossrefPubMedGoogle Scholar
  • 41 Lecine P, Villeval J L, Vyas P, Swencki B, Xu Y, Shivdasani R A. Mice lacking transcription factor NF-E2 provide in vivo validation of the proplatelet model of thrombocytopoiesis and show a platelet production defect that is intrinsic to megakaryocytes.  Blood. 1998;  92 1608-1616
    PubMedGoogle Scholar
  • 42 Levin J, Peng J P, Baker G R et al.. Pathophysiology of thrombocytopenia and anemia in mice lacking transcription factor NF-E2.  Blood. 1999;  94 3037-3047
    PubMedGoogle Scholar
  • 43 Vyas P, Ault K, Jackson C W, Orkin S H, Shivdasani R A. Consequences of GATA-1 deficiency in megakaryocytes and platelets.  Blood. 1999;  93 2867-2875
    PubMedGoogle Scholar
  • 44 Lecine P, Italiano Jr J E, Kim S W, Villeval J L, Shivdasani R A. Hematopoietic-specific beta 1 tubulin participates in a pathway of platelet biogenesis dependent on the transcription factor NF-E2.  Blood. 2000;  96 1366-1373
    PubMedGoogle Scholar
  • 45 Nagata Y, Yoshikawa J, Hashimoto A, Yamamoto M, Payne A H, Todokoro K. Proplatelet formation of megakaryocytes is triggered by autocrine-synthesized estradiol.  Genes Dev. 2003;  17 2864-2869
    CrossrefPubMedGoogle Scholar
  • 46 Schwer H D, Lecine P, Tiwari S, Italiano Jr J E, Hartwig J H, Shivdasani R A. A lineage-restricted and divergent beta-tubulin isoform is essential for the biogenesis, structure and function of blood platelets.  Curr Biol. 2001;  11 579-586
    CrossrefPubMedGoogle Scholar
  • 47 Italiano Jr J E, Bergmeier W, Tiwari S et al.. Mechanisms and implications of platelet discoid shape.  Blood. 2003;  101 4789-4796
    CrossrefPubMedGoogle Scholar
  • 48 Shiraga M, Ritchie A, Aidoudi S et al.. Primary megakaryocytes reveal a role for transcription factor NF-E2 in integrin alpha IIb beta 3 signaling.  J Cell Biol. 1999;  147 1419-1430
    CrossrefPubMedGoogle Scholar
  • 49 Tiwari S, Italiano J E, Barral D C et al.. A role for Rab27b in NF-E2-dependent pathways of platelet formation.  Blood. 2003;  102 3970-3979
    CrossrefPubMedGoogle Scholar
  • 50 Novak E K, Reddington M, Zhen L et al.. Inherited thrombocytopenia caused by reduced platelet production in mice with the gunmetal pigment gene mutation.  Blood. 1995;  85 1781-1789
    PubMedGoogle Scholar
  • 51 Detter J C, Zhang Q, Mules E H et al.. Rab geranylgeranyl transferase alpha mutation in the gunmetal mouse reduces Rab prenylation and platelet synthesis.  Proc Natl Acad Sci USA. 2000;  97 4144-4149
    CrossrefPubMedGoogle Scholar
  • 52 Ihara K, Ishii E, Eguchi M et al.. Identification of mutations in the c-mpl gene in congenital amegakaryocytic thrombocytopenia.  Proc Natl Acad Sci USA. 1999;  96 3132-3136
    CrossrefPubMedGoogle Scholar
  • 53 van den Oudenrijn S, Bruin M, Folman C C et al.. Mutations in the thrombopoietin receptor, Mpl, in children with congenital amegakaryocytic thrombocytopenia.  Br J Haematol. 2000;  110 441-448
    CrossrefPubMedGoogle Scholar
  • 54 Ballmaier M, Germeshausen M, Schulze H et al.. c-mpl mutations are the cause of congenital amegakaryocytic thrombocytopenia.  Blood. 2001;  97 139-146
    CrossrefPubMedGoogle Scholar
  • 55 Ballmaier M, Schulze H, Strauss G et al.. Thrombopoietin in patients with congenital thrombocytopenia and absent radii: elevated serum levels, normal receptor expression, but defective reactivity to thrombopoietin.  Blood. 1997;  90 612-619
    PubMedGoogle Scholar
  • 56 Letestu R, Vitrat N, Masse A et al.. Existence of a differentiation blockage at the stage of a megakaryocyte precursor in the thrombocytopenia and absent radii (TAR) syndrome.  Blood. 2000;  95 1633-1641
    PubMedGoogle Scholar
  • 57 Kelley M J, Jawien W, Ortel T L, Korczak J F. Mutation of MYH9, encoding non-muscle myosin heavy chain A, in May-Hegglin anomaly.  Nat Genet. 2000;  26 106-108
    PubMedGoogle Scholar
  • 58 Kunishima S, Kojima T, Matsushita T et al.. Mutations in the NMMHC-A gene cause autosomal dominant macrothrombocytopenia with leukocyte inclusions (May-Hegglin anomaly/Sebastian syndrome).  Blood. 2001;  97 1147-1149
    CrossrefPubMedGoogle Scholar
  • 59 Seri M, Pecci A, Di Bari F et al.. MYH9-related disease: May-Hegglin anomaly, Sebastian syndrome, Fechtner syndrome, and Epstein syndrome are not distinct entities but represent a variable expression of a single illness.  Medicine (Baltimore). 2003;  82 203-215
    CrossrefPubMedGoogle Scholar
  • 60 Lopez J A, Andrews R K, Afshar-Kharghan V, Berndt M C. Bernard-Soulier syndrome.  Blood. 1998;  91 4397-4418
    PubMedGoogle Scholar
  • 61 White J G, Gerrard J M. Ultrastructural features of abnormal blood platelets. A review.  Am J Pathol. 1976;  83 589-632
    PubMedGoogle Scholar
  • 62 Hayward C P, Cramer E M, Kane W H et al.. Studies of a second family with the Quebec platelet disorder: evidence that the degradation of the alpha-granule membrane and its soluble contents are not secondary to a defect in targeting proteins to alpha-granules.  Blood. 1997;  89 1243-1253
    CrossrefPubMedGoogle Scholar
  • 63 Gurney A L, Carver-Moore K, de Sauvage F J, Moore M W. Thrombocytopenia in c-mpl-deficient mice.  Science. 1994;  265 1445-1447
    PubMedGoogle Scholar
  • 64 Carver-Moore K, Broxmeyer H E, Luoh S M et al.. Low levels of erythroid and myeloid progenitors in thrombopoietin- and c-mpl-deficient mice.  Blood. 1996;  88 803-808
    PubMedGoogle Scholar
  • 65 Alexander W S, Roberts A W, Nicola N A, Li R, Metcalf D. Deficiencies in progenitor cells of multiple hematopoietic lineages and defective megakaryocytopoiesis in mice lacking the thrombopoietic receptor c-Mpl.  Blood. 1996;  87 2162-2170
    PubMedGoogle Scholar
  • 66 Bunting S, Widmer R, Lipari T et al.. Normal platelets and megakaryocytes are produced in vivo in the absence of thrombopoietin.  Blood. 1997;  90 3423-3429
    PubMedGoogle Scholar
  • 67 Zeigler F C, de Sauvage F, Widmer H R et al.. In vitro megakaryocytopoietic and thrombopoietic activity of c-mpl ligand (TPO) on purified murine hematopoietic stem cells.  Blood. 1994;  84 4045-4052
    PubMedGoogle Scholar
  • 68 Kirito K, Osawa M, Morita H et al.. A functional role of Stat3 in in vivo megakaryopoiesis.  Blood. 2002;  99 3220-3227
    CrossrefPubMedGoogle Scholar
  • 69 Kimura Y, Hart A, Hirashima M et al.. Zinc finger protein, Hzf, is required for megakaryocyte development and hemostasis.  J Exp Med. 2002;  195 941-952
    CrossrefPubMedGoogle Scholar
  • 70 Mikkola H K, Klintman J, Yang H et al.. Haematopoietic stem cells retain long-term repopulating activity and multipotency in the absence of stem-cell leukaemia SCL/tal-1 gene.  Nature. 2003;  421 547-551
    CrossrefPubMedGoogle Scholar
  • 71 Hall M A, Curtis D J, Metcalf D et al.. The critical regulator of embryonic hematopoiesis, SCL, is vital in the adult for megakaryopoiesis, erythropoiesis, and lineage choice in CFU-S12.  Proc Natl Acad Sci USA. 2003;  100 992-997
    CrossrefPubMedGoogle Scholar
  • 72 Zucker-Franklin D. Atlas of Blood Cells: Function and Pathology, Vol 2. Philadelphia; Lea & Febiger 1988
    Google Scholar
  • 73 Emambokus N R, Frampton J. The glycoprotein IIb molecule is expressed on early murine hematopoietic progenitors and regulates their numbers in sites of hematopoiesis.  Immunity. 2003;  19 33-45
    CrossrefPubMedGoogle Scholar
  • 74 Mikkola H K, Fujiwara Y, Schlaeger T M, Traver D, Orkin S H. Expression of CD41 marks the initiation of definitive hematopoiesis in the mouse embryo.  Blood. 2003;  101 508-516
    CrossrefPubMedGoogle Scholar
  • 75 Nakorn T N, Miyamoto T, Weissman I L. Characterization of mouse clonogenic megakaryocyte progenitors.  Proc Natl Acad Sci USA. 2003;  100 205-210
    CrossrefPubMedGoogle Scholar
  • 76 Debili N, Coulombel L, Croisille L et al.. Characterization of a bipotent erythro-megakaryocytic progenitor in human bone marrow.  Blood. 1996;  88 1284-1296
    PubMedGoogle Scholar
  • 77 Kaushansky K. Thrombopoietin: the primary regulator of platelet production.  Blood. 1995;  86 419-431
    PubMedGoogle Scholar
  • 78 Choi E S, Hokom M M, Chen J L et al.. The role of megakaryocyte growth and development factor in terminal stages of thrombopoiesis.  Br J Haematol. 1996;  95 227-233
    PubMedGoogle Scholar
  • 79 Odell Jr T T, Jackson C W. Polyploidy and maturation of rat megakaryocytes.  Blood. 1968;  32 102-110
    PubMedGoogle Scholar
  • 80 Raslova H, Roy L, Vourc’h C et al.. Megakaryocyte polyploidization is associated with a functional gene amplification.  Blood. 2003;  101 541-544
    CrossrefPubMedGoogle Scholar
  • 81 Nagata Y, Muro Y, Todokoro K. Thrombopoietin-induced polyploidization of bone marrow megakaryocytes is due to a unique regulatory mechanism in late mitosis.  J Cell Biol. 1997;  139 449-457
    CrossrefPubMedGoogle Scholar
  • 82 Wang Z, Zhang Y, Kamen D, Lees E, Ravid K. Cyclin D3 is essential for megakaryocytopoiesis.  Blood. 1995;  86 3783-3788
    PubMedGoogle Scholar
  • 83 Matsumura I, Tanaka H, Kawasaki A et al.. Increased D-type cyclin expression together with decreased cdc2 activity confers megakaryocytic differentiation of a human thrombopoietin-dependent hematopoietic cell line.  J Biol Chem. 2000;  275 5553-5559
    CrossrefPubMedGoogle Scholar
  • 84 Carow C E, Fox N E, Kaushansky K. Kinetics of endomitosis in primary murine megakaryocytes.  J Cell Physiol. 2001;  188 291-303
    CrossrefPubMedGoogle Scholar
  • 85 Garcia P, Frampton J, Ballester A, Cales C. Ectopic expression of cyclin E allows non-endomitotic megakaryoblastic K562 cells to establish re-replication cycles.  Oncogene. 2000;  19 1820-1833
    CrossrefPubMedGoogle Scholar
  • 86 Bermejo R, Vilaboa N, Cales C. Regulation of CDC6, geminin, and CDT1 in human cells that undergo polyploidization.  Mol Biol Cell. 2002;  13 3989-4000
    CrossrefPubMedGoogle Scholar
  • 87 Geng Y, Yu Q, Sicinska E et al.. Cyclin E ablation in the mouse.  Cell. 2003;  114 431-443
    CrossrefPubMedGoogle Scholar
  • 88 Heijnen H F, Debili N, Vainchencker W, Breton-Gorius J, Geuze H J, Sixma J J. Multivesicular bodies are an intermediate stage in the formation of platelet alpha-granules.  Blood. 1998;  91 2313-2325
    PubMedGoogle Scholar
  • 89 Youssefian T, Cramer E M. Megakaryocyte dense granule components are sorted in multivesicular bodies.  Blood. 2000;  95 4004-4007
    PubMedGoogle Scholar
  • 90 Rojnuckarin P, Kaushansky K. Actin reorganization and proplatelet formation in murine megakaryocytes: the role of protein kinase Cα.  Blood. 2001;  97 154-161
    CrossrefPubMedGoogle Scholar
  • 91 De Botton S, Sabri S, Daugas E et al.. Platelet formation is the consequence of caspase activation within megakaryocytes.  Blood. 2002;  100 1310-1317
    CrossrefPubMedGoogle Scholar
  • 92 Ogilvy S, Metcalf D, Print C G, Bath M L, Harris A W, Adams J M. Constitutive Bcl-2 expression throughout the hematopoietic compartment affects multiple lineages and enhances progenitor cell survival.  Proc Natl Acad Sci USA. 1999;  96 14943-14948
    CrossrefPubMedGoogle Scholar
  • 93 Kaluzhny Y, Yu G, Sun S et al.. BclxL overexpression in megakaryocytes leads to impaired platelet fragmentation.  Blood. 2002;  100 1670-1678
    CrossrefPubMedGoogle Scholar
  • 94 Bouillet P, Metcalf D, Huang D C et al.. Proapoptotic Bcl-2 relative Bim required for certain apoptotic responses, leukocyte homeostasis, and to preclude autoimmunity.  Science. 1999;  286 1735-1738
    CrossrefPubMedGoogle Scholar
  • 95 Clarke M C, Savill J, Jones D B, Noble B S, Brown S B. Compartmentalized megakaryocyte death generates functional platelets committed to caspase-independent death.  J Cell Biol. 2003;  160 577-587
    CrossrefPubMedGoogle Scholar
  • 96 Hitchcock I S, Skerry T M, Howard M R, Genever P G. NMDA receptor-mediated regulation of human megakaryocytopoiesis.  Blood. 2003;  102 1254-1259
    CrossrefPubMedGoogle Scholar
  • 97 Delehanty L L, Mogass M, Gonias S L, Racke F K, Johnstone B, Goldfarb A N. Stromal inhibition of megakaryocytic differentiation is associated with blockade of sustained Rap1 activation.  Blood. 2003;  101 1744-1751
    CrossrefPubMedGoogle Scholar
  • 98 de Bruyn K M, Zwartkruis F J, de Rooij J, Akkerman J W, Bos J L. The small GTPase Rap1 is activated by turbulence and is involved in integrin [alpha]IIb[beta]3-mediated cell adhesion in human megakaryocytes.  J Biol Chem. 2003;  278 22412-22417
    CrossrefPubMedGoogle Scholar
  • 99 Eto K, Murphy R, Kerrigan S W et al.. Megakaryocytes derived from embryonic stem cells implicate CalDAG-GEFI in integrin signaling.  Proc Natl Acad Sci USA. 2002;  99 12819-12824
    CrossrefPubMedGoogle Scholar
  • 100 Battinelli E, Willoughby S R, Foxall T, Valeri C R, Loscalzo J. Induction of platelet formation from megakaryocytoid cells by nitric oxide.  Proc Natl Acad Sci USA. 2001;  98 14458-14463
    CrossrefPubMedGoogle Scholar

Ramesh A ShivdasaniM.D. Ph.D. 

Dana-Farber Cancer Institute

One Jimmy Fund Way, Boston, MA 02115

Email: ramesh_shivdasani@dfci.harvard.edu

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