1: Leuk Res. 2005 Oct 7; [Epub ahead of print] Histologic and molecular characterizations of megakaryocytic leukemia in mice. Hao X, Shin MS, Zhou JX, Lee CH, Qi CF, Naghashfar Z, Hartley JW, Fredrickson TN, Ward JM, Morse HC 3rd. Laboratory of Immunopathology, National Institute of Allergy and Infectious Diseases, National Institute of Health, Rockville, MD 20852, USA. Six cases of megakaryocytic leukemia (MKL) were identified and analyzed for morphology and molecular features. MKL were composed of megakaryocyte lineage cells ranging from immature to quite mature cells. VWF, GATA1 and RUNX1 were strongly expressed in megakaryocytes in both normal spleen and MKL as analyzed by immunohistochemistry (IHC). Altered expression of Meis1, Pbx1 and Psen2 and Lef1 in MKL detected with oligonucleotide microarrays was confirmed by qPCR and IHC. This is the first report of spontaneous MKL in mice, defining VWF as a biomarker for diagnosis and suggesting possible involvement of a series of genes in disease pathogenesis. PMID: 16219351 [PubMed - as supplied by publisher] --------------------------------------------------------------- 2: Cancer Res. 2005 Sep 1;65(17):7596-602. The proto-oncogene ERG in megakaryoblastic leukemias. Rainis L, Toki T, Pimanda JE, Rosenthal E, Machol K, Strehl S, Gottgens B, Ito E, Izraeli S. Department of Pediatric Hematology-Oncology, Safra Children's Hospital and Hematology Institute, Sheba Cancer Research Center, Sheba Medical Center, Tel-Hashomer, Israel. Aneuploidy is one of the hallmarks of cancer. Acquired additions of chromosome 21 are a common finding in leukemias, suggesting a contributory role to leukemogenesis. About 10% of patients with a germ line trisomy 21 (Down syndrome) are born with transient megakaryoblastic leukemia. We and others have shown acquired mutations in the X chromosome gene GATA1 in all these cases. The gene or genes on chromosome 21 whose overexpression promote the megakaryoblastic phenotype are presently unknown. We propose that ERG, an Ets transcription factor situated on chromosome 21, is one such candidate. We show that ERG is expressed in hematopoietic stem cells, megakaryoblastic cell lines, and in primary leukemic cells from Down syndrome patients. ERG expression is induced upon megakaryocytic differentiation of the erythroleukemia cell lines K562 and UT-7, and forced expression of ERG in K562 cells induces erythroid to megakaryoblastic phenotypic switch. We also show that ERG activates the gpIb megakaryocytic promoter and binds the gpIIb promoter in vivo. Furthermore, both ERG and ETS2 bind in vivo the hematopoietic enhancer of SCL/TAL1, a key regulator of hematopoietic stem cell and megakaryocytic development. We propose that trisomy 21 facilitates the occurrence of megakaryoblastic leukemias through a shift toward the megakaryoblastic lineage caused by the excess expression of ERG, and possibly by other chromosome 21 genes, such as RUNX1 and ETS2, in hematopoietic progenitor cells, coupled with a differentiation arrest caused by the acquisition of mutations in GATA1. PMID: 16140924 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 3: Blood. 2005 Jun 1;105(11):4523-6. Epub 2005 Feb 10. AML1-FOG2 fusion protein in myelodysplasia. Chan EM, Comer EM, Brown FC, Richkind KE, Holmes ML, Chong BH, Shiffman R, Zhang DE, Slovak ML, Willman CL, Noguchi CT, Li Y, Heiber DJ, Kwan L, Chan RJ, Vance GH, Ramsey HC, Hromas RA. Division of Hematology-Oncology, Department of Medicine, Indiana University School of Medicine, 1044 W Walnut St, R4-202, Indianapolis, IN 46202-5254, USA. echan@iupui.edu Core binding factor (CBF) participates in specification of the hematopoietic stem cell and functions as a critical regulator of hematopoiesis. Translocation or point mutation of acute myeloid leukemia 1 (AML1)/RUNX1, which encodes the DNA-binding subunit of CBF, plays a central role in the pathogenesis of acute myeloid leukemia and myelodysplasia. We characterized the t(X;21)(p22.3;q22.1) in a patient with myelodysplasia that fuses AML1 in-frame to the novel partner gene FOG2/ZFPM2. The reciprocal gene fusions AML1-FOG2 and FOG2-AML1 are both expressed. AML1-FOG2, which fuses the DNA-binding domain of AML1 to most of FOG2, represses the transcriptional activity of both CBF and GATA1. AML1-FOG2 retains a motif that recruits the corepressor C-terminal binding protein (CtBP) and these proteins associate in a protein complex. These results suggest a central role for CtBP in AML1-FOG2 transcriptional repression and implicate coordinated disruption of the AML1 and GATAdevelopmental programs in the pathogenesis of myelodysplasia. PMID: 15705784 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 4: Br J Haematol. 2004 Jul;126(1):3-10. Leukaemia -- a developmental perspective. Izraeli S. Department of Paediatric Haemato-Oncology, Sackler Faculty of Medicine, Cancer Research Centre, Safra's Children's Hospital, Sheba Medical Centre, Tel-Aviv University, Tel-Hashomer, Ramat-Gan, Israel. izraelis@netvision.net.il Leukaemia is characterized by the accumulation of malignant haematopoietic precursors. Recent studies have revealed that acquired alterations in genes that regulate normal haematopoiesis are frequently detected in leukaemia. The progression to leukaemia depends on additional mutations that promote the survival of developmentally arrested cells. This review describes three examples of this general paradigm of leukaemogenesis: RUNX1 abnormalities in acute leukaemias, GATA1 mutations in the leukaemias of Down syndrome, and SCL and LMO2 ectopic expression in T cell acute lymphoblastic leukaemia. Publication Types: Review PMID: 15198727 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 5: EMBO J. 2003 Dec 15;22(24):6516-25. Cooperation between the GATA and RUNX factors Serpent and Lozenge during Drosophila hematopoiesis. Waltzer L, Ferjoux G, Bataille L, Haenlin M. Centre de Biologie du Developpement, CNRS UMR 5547, 118 route de Narbonne, 31062 Toulouse, France. haenlin@cict.fr Members of the GATA and RUNX families of genes appear to have conserved functions during hematopoiesis from Drosophila to mammals. In Drosophila, the GATA factor Serpent (Srp) is required in blood cell progenitors for the formation of the two populations of blood cells (plasmatocytes and crystal cells), while the RUNX factor Lozenge (Lz) is specifically required for crystal cell development. Here we investigate the function and the mechanisms of action of Lz during hematopoiesis. Our results indicate that Lz can trigger crystal cell development. Interestingly, we show that Lz function is strictly dependent on the presence of functional Srp and that Srp and Lz cooperate to induce crystal cell differentiation in vivo. Furthermore, we show that Srp and Lz directly interact in vitro and that this interaction is conserved between Drosophila and mammals. Moreover, both Srp and mouse GATA1 synergize with mouse RUNX1 to activate transcription. We propose that interaction and cooperation between GATA and RUNX factors may play an important role in regulating blood cell formation from Drosophila to mammals. PMID: 14657024 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 6: Nat Genet. 2002 Dec;32(4):633-8. Epub 2002 Nov 18. Core-binding factor beta interacts with Runx2 and is required for skeletal development. Yoshida CA, Furuichi T, Fujita T, Fukuyama R, Kanatani N, Kobayashi S, Satake M, Takada K, Komori T. Department of Molecular Medicine, Osaka University Medical School, 2-2 Yamada-oka Suita, Osaka 565-0871, Japan. Core-binding factor beta (CBFbeta, also called polyomavirus enhancer binding protein 2beta (PEBP2B)) is associated with an inversion of chromosome 16 and is associated with acute myeloid leukemia in humans. CBFbeta forms a heterodimer with RUNX1 (runt-related transcription factor 1), which has a DNA binding domain homologous to the pair-rule protein runt in Drosophila melanogaster. Both RUNX1 and CBFbeta are essential for hematopoiesis. Haploinsufficiency of another runt-related protein, RUNX2 (also called CBFA1), causes cleidocranial dysplasia in humans and is essential in skeletal development by regulating osteoblast differentiation and chondrocyte maturation. Mice deficient in Cbfb (Cbfb(-/-)) die at midgestation, so the function of Cbfbeta in skeletal development has yet to be ascertained. To investigate this issue, we rescued hematopoiesis of Cbfb(-/-) mice by introducing Cbfb using the Gata1 promoter. The rescued Cbfb(-/-) mice recapitulated fetal liver hematopoiesis in erythroid and megakaryocytic lineages and survived until birth, but showed severely delayed bone formation. Although mesenchymal cells differentiated into immature osteoblasts, intramembranous bones were poorly formed. The maturation of chondrocytes into hypertrophic cells was markedly delayed, and no endochondral bones were formed. Electrophoretic mobility shift assays and reporter assays showed that Cbfbeta was necessary for the efficient DNA binding of Runx2 and for Runx2-dependent transcriptional activation. These findings indicate that Cbfbeta is required for the function of Runx2 in skeletal development. PMID: 12434152 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 7: Nat Genet. 2002 Sep;32(1):148-52. Epub 2002 Aug 12. Comment in: Nat Genet. 2002 Sep;32(1):83-4. Pediatr Res. 2002 Dec;52(6):831. Acquired mutations in GATA1 in the megakaryoblastic leukemia of Down syndrome. Wechsler J, Greene M, McDevitt MA, Anastasi J, Karp JE, Le Beau MM, Crispino JD. Ben May Institute for Cancer Research, University of Chicago, Chicago, Illinois 60637, USA. Children with Down syndrome have a 10-20-fold elevated risk of developing leukemia, particularly acute megakaryoblastic leukemia (AMKL). While a subset of pediatric AMKLs is associated with the 1;22 translocation and expression of a mutant fusion protein, the genetic alterations that promote Down syndrome-related AMKL (DS-AMKL) have remained elusive. Here we show that leukemic cells from every individual with DS-AMKL that we examined contain mutations in GATA1, encoding the essential hematopoietic transcription factor GATA1 (GATA binding protein 1 or globin transcription factor 1). Each mutation results in the introduction of a premature stop codon in the gene sequence that encodes the amino-terminal activation domain. These mutations prevent synthesis of full-length GATA1, but not synthesis of a shorter variant that is initiated downstream. We show that the shorter GATA1 protein, which lacks the N-terminal activation domain, binds DNA and interacts with its essential cofactor Friend of GATA1 (FOG1; encoded by ZFPM1) to the same extent as does full-length GATA1, but has a reduced transactivation potential. Although some reports suggest that the activation domain is dispensable in cell-culture models of hematopoiesis, one study has shown that it is required for normal development in vivo. Together, these findings indicate that loss of wildtype GATA1 constitutes one step in the pathogenesis of AMKL in Down syndrome. PMID: 12172547 [PubMed - indexed for MEDLINE] ---------------------------------------------------------------