The Experts below are selected from a list of 10092 Experts worldwide ranked by ideXlab platform
Takuro Nakamura - One of the best experts on this subject based on the ideXlab platform.
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single translocation and double chimeric transcripts detection of nup98 HOXA9 in myeloid leukemias withhoxa11 or hoxa13 breaks of the chromosomal translocation t 7 11 p15 p15
Blood, 2002Co-Authors: Takashi Fujino, Kazuma Ohyashiki, A Suzuki, Yoshikazu Ito, Yoshiaki Hatano, Ikuo Miura, Takuro NakamuraAbstract:It has been demonstrated that the chromosomal translocation t(7;11)(p15;p15) in patients with human acute myelogenous leukemia (AML) and chronic myelogenous leukemia (CML) invariably involves fusion of the nucleoporin gene, NUP98, on chromosome 11 and the class 1 HOX gene, HOXA9, on chromosome 7, and that the fusion gene NUP98-HOXA9 is an important gene in myeloid leukemogenesis. Here are reported 2 novel chromosome 7p15 targets of the t(7;11)(p15;p15) chromosomal translocation in 2 patients with CML and myelodysplastic syndrome (MDS). Southern blot and polymerase chain reaction (PCR) analyses of leukemia cell DNA failed to show rearrangement of HOXA9,whereas NUP98 was found to be rearranged in both cases. Reverse transcription-PCR analysis using a NUP98 primer and a degenerate primer corresponding to the third helix of the homeodomain of HOXA demonstrated that NUP98 was fused in-frame to HOXA11 in the patient with CML and toHOXA13 in the patient with MDS. The chromosomal breakpoints on 7p15 were located within introns of HOXA11 orHOXA13 genes. In both patients chimericNUP98-HOXA9 transcripts were also observed. These findings suggest that AbdB-type HOXA genes are common targets of t(7;11)(p15;p15) chromosomal translocations and that a single translocation can produce more than oneNUP98-HOXA fusion gene, presumably because of altered splicing.
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single translocation and double chimeric transcripts detection of nup98 HOXA9 in myeloid leukemias with hoxa11 or hoxa13 breaks of the chromosomal translocation t 7 11 p15 p15
Blood, 2002Co-Authors: Takashi Fujino, Kazuma Ohyashiki, A Suzuki, Yoshikazu Ito, Yoshiaki Hatano, Ikuo Miura, Takuro NakamuraAbstract:It has been demonstrated that the chromosomal translocation t(7;11)(p15;p15) in patients with human acute myelogenous leukemia (AML) and chronic myelogenous leukemia (CML) invariably involves fusion of the nucleoporin gene, NUP98 , on chromosome 11 and the class 1 HOX gene, HOXA9 , on chromosome 7, and that the fusion gene NUP98 - HOXA9 is an important gene in myeloid leukemogenesis. Here are reported 2 novel chromosome 7p15 targets of the t(7;11)(p15;p15) chromosomal translocation in 2 patients with CML and myelodysplastic syndrome (MDS). Southern blot and polymerase chain reaction (PCR) analyses of leukemia cell DNA failed to show rearrangement of HOXA9, whereas NUP98 was found to be rearranged in both cases. Reverse transcription-PCR analysis using a NUP98 primer and a degenerate primer corresponding to the third helix of the homeodomain of HOXA demonstrated that NUP98 was fused in-frame to HOXA11 in the patient with CML and to HOXA13 in the patient with MDS. The chromosomal breakpoints on 7p15 were located within introns of HOXA11 or HOXA13 genes. In both patients chimeric NUP98-HOXA9 transcripts were also observed. These findings suggest that AbdB-type HOXA genes are common targets of t(7;11)(p15;p15) chromosomal translocations and that a single translocation can produce more than one NUP98 - HOXA fusion gene, presumably because of altered splicing.
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fusion of the nucleoporin gene nup98 to HOXA9 by the chromosome translocation t 7 11 p15 p15 in human myeloid leukaemia
Nature Genetics, 1996Co-Authors: Takuro Nakamura, David A Largaespada, Laura A Johnson, Kazuma Ohyashiki, Keisuke Toyama, Sai Juan Chen, Cheryl L Willman, Iming Chen, Andrew P Feinberg, Nancy A JenkinsAbstract:Expression of HoxaT and HOXA9 is activated by proviral integration in BXH2 murine myeloid leukaemias. This result, combined with the mapping of the HOXA locus to human chromosome 7p15, suggested that one of the HOXA genes might be involved in the t(7;11)(p15;p15) translocation found in some human myeloid leukaemia patients. Here we show that in three patients with t(7;11), the chromosome rearrangement creates a genomic fusion between the HOXA9 gene and the nucleoporin gene NUP98 on chromosome 11 p15. The translocation produces an invariant chimaeric NUP98/HOXA9 transcript containing the amino terminal half of NUP98 fused in frame to HOXA9. These studies identify HOXA9 as an important human myeloid leukaemia gene and suggest an important role for nucleoporins in human myeloid leukaemia given that a second nucleoporin, NUP214, has also been implicated in human myeloid leukaemia.
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cooperative activation of hoxa and pbx1 related genes in murine myeloid leukaemias
Nature Genetics, 1996Co-Authors: Takuro Nakamura, David A Largaespada, Nancy A Jenkins, John D Shaughnessy, Neal G CopelandAbstract:Abstract Retroviruses induce myeloid leukaemia in BXH-2 mice by the insertional mutation of cellular proto-oncogenes or tumour suppressor genes. Disease genes can thus be identified by proviral tagging through the identification of common viral integration sites in BXH-2 leukaemia. Here, we describe a new approach for proviral tagging that greatly facilitates the identification of BXH-2 leukaemia genes. Using this approach, we identify three genes whose expression is activated by proviral integration in BXH-2 leukaemias; Hoxa7, HOXA9, and a Pbx1-related homeobox gene, Meis1. Proviral activation of Hoxa7 or HOXA9 is strongly correlated with proviral activation of Meis1 implying that Hoxa7 and HOXA9 cooperate with Meis1 in leukaemia formation. These studies provide the first genetic evidence that Pbx1-related genes cooperate with Hox genes in leukaemia formation and identify a number of new murine myeloid leukaemia genes.
Scott A Armstrong - One of the best experts on this subject based on the ideXlab platform.
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HOXA9 is required for survival in human MLL-rearranged acute leukemias
Blood, 2009Co-Authors: Joerg Faber, Matthew C Stubbs, Andrew L Kung, Christian M Zwaan, Andrei V. Krivtsov, Renee Wright, Tina N. Davis, Marry M. Van Den Heuvel-eibrink, Scott A ArmstrongAbstract:Leukemias that harbor translocations involving the mixed lineage leukemia gene (MLL) possess unique biologic characteristics and often have an unfavorable prognosis. Gene expression analyses demonstrate a distinct profile for MLL-rearranged leukemias with consistent high-level expression of select Homeobox genes, including HOXA9. Here, we investigated the effects of HOXA9 suppression in MLL-rearranged and MLL-germline leukemias using RNA interference. Gene expression profiling after HOXA9 suppression demonstrated co–down-regulation of a program highly expressed in human MLL-AML and murine MLL-leukemia stem cells, including HOXA10, MEIS1, PBX3, and MEF2C. We demonstrate that HOXA9 depletion in 17 human AML/ALL cell lines (7 MLL-rearranged, 10 MLL-germline) induces proliferation arrest and apoptosis specifically in MLL-rearranged cells (P = .007). Similarly, assessment of primary AMLs demonstrated that HOXA9 suppression induces apoptosis to a greater extent in MLL-rearranged samples (P = .01). Moreover, mice transplanted with HOXA9-depleted t(4;11) SEMK2 cells revealed a significantly lower leukemia burden, thus identifying a role for HOXA9 in leukemia survival in vivo. Our data indicate an important role for HOXA9 in human MLL-rearranged leukemias and suggest that targeting HOXA9 or downstream programs may be a novel therapeutic option.
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HOXA9 represses bim expression in mll rearranged leukemia implications for drug therapy
Blood, 2007Co-Authors: Matthew C Stubbs, Joerg Faber, Andrew L Kung, Scott Cameron, Scott A ArmstrongAbstract:MLL translocations can be found in roughly 10% of acute leukemias, including over 70% of infant leukemias. These leukemias are often associated with a poor prognosis, making new therapeutics for this subtype of leukemias a priority. HoxA cluster genes have been shown to be upregulated by MLL fusion proteins, and make up a portion of a self-renewal associated gene expression signature found in murine models of MLL-AF9-expressing leukemia stem cells. The role of HoxA cluster genes in MLL-fusion mediated leukemia is not clearly understood, mainly due to lack of knowledge of HoxA downstream targets. One possible role for HoxA proteins in MLL-fusion induced leukemia is enhancement of growth and survival pathways. Evidence for this possibility can be found in C.elegans, where the pro-apoptotic BH3-only gene egl-1 is regulated by homeobox genes. Therefore we sought to determine whether a HoxA cluster gene could in fact regulate survival/apoptosis machinery. Here we demonstrate that HOXA9 serves as a repressor of the pro-apoptotic BH3-only family member Bim. Knockdown of HOXA9 using shRNA in the MLL-AF9 expressing AML cell line Molm14 leads to upregulation of Bim, and rapid induction of apoptosis. Interestingly, knockdown of Meis1 or Pbx2, known binding partners of HOXA9, showed only an intermediate effect, with slower growth, but without an increase in Bim levels. Other BH3-only family members Noxa and Puma showed no significant change in expression after HOXA9 suppression as determined by quantitative RT-PCR. Using a FLAG-HOXA9 expressing Molm14 cell line, we were able to determine by chromatin immunoprecipitation that HOXA9 is present at a DNA region containing a canonical HOX-PBX binding site (TGATTTAT) roughly 100bp downstream of the first exon-intron junction in the human Bim gene. As histone deacetylases (HDACs) are generally transcription repressors, it is plausible that HOXA9 recruits HDACs to the Bim gene, thus regulating its expression. Since HDAC inhibitors also activate BIM, we assessed BIM activation in Molm14 cells after treatment with an HDAC inhibitor, and noted similar kinetics of BIM activation, suggesting a possible link between HOXA9 mediated suppression of BIM and HDACs. We are now assessing HOXA9/HDAC interactions in MLL rearranged leukemia cells. These data suggest that HOXA9 ensures survival of leukemia cells by directly inhibiting transcription of the pro-apoptotic gene Bim, and that interfering with this mechanism may improve treatment for MLL-fusion bearing leukemias.
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the myocyte enhancer factor 2c mef2c is a direct transcriptional target of HOXA9 and mediates leukemia survival in human mixed lineage leukemias
Blood, 2007Co-Authors: Jorg Faber, Matthew C Stubbs, Andrew L Kung, Scott A Armstrong, Andrei V Krivstov, Marry Van Den Heuveleibrink, Christian M ZwaanAbstract:Leukemias that harbor rearrangements of the mixed-lineage leukemia gene ( MLL ) possess unique clinical and biological characteristics. Aberrant high-level expression of select Homeobox ( HOX ) genes including HOXA9 is a consistent feature of MLL -rearranged leukemias, implicating an important role of dysregulated HOX gene expression in this entity. Applying HOXA9 -directed RNAi, we have previously shown that aberrant HOXA9 expression is a prerequisite for leukemia survival in human MLL -rearranged leukemias and murine Mll -leukemia stem cells as HOXA9 suppression leads to a progressive induction of apoptosis in vitro and in vivo . In this study we aimed to identify potential direct HOXA9 target genes in human MLL -rearranged leukemias utilizing gene expression profiling after shRNA mediated HOXA9 knockdown and subsequent chromatin immunoprecipitation (ChIP) analysis. To establish efficient HOXA9 knockdown, 2 previously validated shRNA constructs targeting human HOXA9 with high efficiency (>80% mRNA suppression) were transduced into t(9;11) MOLM-14 AML cells. 72h after transduction, RNA was hybridized to Affymetrix HU 133A2.0 expression arrays. Supervised analysis identified a large group of genes concomitantly downregulated after HOXA9 suppression. Gene set enrichment analysis demonstrated significant enrichment of the top 300 genes in the HOXA9 suppression signature and genes more highly expressed in human MLL-AML as compared to other genetically defined AML subtypes (p=0.02). Interestingly, genes previously implicated in the pathogenesis of MLL -rearranged leukemias were among the most highly enriched ( HOXA5 , MEIS1 , PBX3 , MEF2C ). To analyze if any of this genes might be a direct physiological HOXA9 target, we performed ChIP assays from FLAG-tagged HOXA9 expressing MOLM-14 cells. Whereas the promotor regions of HOXA5 , MEIS1 and PBX3 did not show HOXA9 binding, the MEF2C promotor region DNA was highly enriched by ChIP. Furthermore HOXA9 binding was confined to the MEF2C promotor region as the regions -5kb 5’-upstream, +5kb and +10kb 3’-downstream of the MEF2C promotor region did not show any enrichment. Motive search analysis of the MEF2C promoter further revealed a perfect consensus binding site (TGATTTAT) for HOXA9 and its DNA binding partner PBX located at −721 to −714 from the transcriptional start site. We then analyzed if direct shRNA mediated targeting of MEF2C also abrogates leukemia survival in human MLL -rearranged leukemias similar to upstream HOXA9 suppression. Analysis of viability after MEF2C knockdown with two different shRNA constructs (>80% mRNA knockdown) in a panel of human 8 AML/ALL cell lines (4 MLL -rearranged; 4 MLL -wildtype) and primary AML patient cells (5 MLL -rearranged; 5 MLL -wildtype) revealed progressive induction of apoptosis which was significantly correlated with the presence of the MLL -fusion oncogene in the cell lines (mean viability at day 7: MLL -rearranged: 14.5% MLL -wildtype: 86.75%: p MEF2C as a direct downstream target of HOXA9 and aberrant MEF2C expression is necessary for survival of MLL -rearranged leukemias. Targeting the HOXA9-MEF2C program may be a novel therapeutic approach.
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HOXA9 meis1a efficiently transform hematopoietic stem cells but not committed progenitors
Blood, 2007Co-Authors: Yingzi Wang, Scott A Armstrong, Andrei V. Krivtsov, Grigoriy LosyevAbstract:The homeobox transcription factors HOXA9 and Meis1a induce the expansion of hematopoietic stem cells (HSC) and cooperate to induce acute myeloid leukemia (AML). We have recently shown that HOXA9 and Meis1a are part of a self-renewal program found in leukemia stem cells (LSC) isolated from murine leukemias initiated by expression of MLL-AF9 in committed granulocyte macrophage progenitors (GMP). However, it remains unclear whether the HOXA9-Meis1a complex is sufficient to mimic the leukemogenic effects of MLL-AF9. Therefore we assessed the clonogenic and leukemogenic activity of HSC and GMP transduced with HOXA9-Meis1a and compared this to MLL-AF9 transduced HSC and GMP. We expressed either HOXA9-Meis1a or MLL-AF9 in HSC or GMP and sorted single cells into 96 well plates. The data demonstrate that the clonogenic potential of single HSC or GMP expressing HOXA9-Meis1a or MLL-AF9 are similar and both produce cells that can be replated in vitro for greater than 6 weeks. Remarkably, HOXA9-Meis1a induces leukemia with high efficiency when expressed in HSC but not committed GMP, while MLL-AF9 can fully transform both HSC and GMP. Next, we identified a population of cells from HOXA9-Meis1a leukemias that were enriched for LSC. Even though the leukemias were initiated from HSC, the LSC population possessed an immunophenotype and global gene expression program more consistent with differentiated myeloid cells. Further characterization of gene expression in the HOXA9-Meis1a LSC found that only a subset of the MLL-AF9 self-renewal signature is activated by HOXA9-Meis1a. These findings show that HOXA9-Meis1a can efficiently induce LSC from HSC but not GMP. This suggests HOXA9 and Meis1a induced leukemogenesis is dependent upon cellular context and require programs/pathways active in HSC in order to initiate leukemia. Thus MLL-AF9 must activate pathways critical for LSC development in addition to HOXA9-Meis1a in order to fully transform committed progenitor cells. Identification of these cooperating pathways should provide insight into MLL-rearranged and other AML.
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HOXA9 Knockdown Inhibits Proliferation and Induces Cell Death in Human MLL-Rearranged Leukemias.
Blood, 2006Co-Authors: Jorg Faber, Matthew C Stubbs, Andrew L Kung, Christian M Zwaan, Andrei V. Krivtsov, Renee Wright, Marry M. Van Den Heuvel-eibrink, Scott A ArmstrongAbstract:Homeobox containing (Hox) genes are implicated in the regulation of normal and leukemic hematopoesis. Using gene expression profiling we and others have previously shown that HOXA9 is highly expressed in lymphoid and myeloid leukemias harboring MLL translocations and that high level HOXA9 expression is associated with poor clinical prognosis. Furthermore, HOXA9 plays variable roles in MLL-fusion induced murine leukemias. In this study we aimed to elucidate the role of aberrant HOXA9 expression in human MLL-rearranged and non-rearranged leukemia’s utilizing an shRNA mediated knockdown approach. To establish an efficient knockdown assay three different shRNA constructs targeting human HOXA9 were synthesized and stably introduced into t(9;11) MOLM14 cells utilizing a lentiviral vector system. The shRNA construct which showed highest efficiency as measured by Taqman quantitative PCR (75–80% knockdown MLL-AF9 RNA) and Western Blot analysis was used for further experiments. In MOLM-14 cells, HOXA9 directed shRNA inhibited cell proliferation starting as early as 48h after transduction as determined by MTT assay, and at 72h demonstrated a markedly increased number of apoptotic cells as measured by Annexin V staining. This effect was rescued by introducing a non-targetable exogenous HOXA9 in MOLM-14 cells. To investigate if the HOXA9 knockdown related effects are specific for MLL rearranged cells we next analyzed cell growth and viability in 17 AML/ALL cell lines (7 MLL-rearranged, 10 non rearranged) after shRNA mediated HOXA9 knockdown. Interestingly, impaired cell proliferation and induction of apoptosis was significantly higher in the MLL rearranged cell lines (mean viability: 51.88%) than in the non-rearranged cells (mean viability: 90.98%; p=0.007). Moreover, the effect was also significantly correlated with the baseline HOXA9 mRNA expression before knockdown, with the greatest effect in cell lines expressing the highest HOXA9 levels (R= 0.8, p=0.00017). These findings prompted us to further analyze the effect of HOXA9 knockdown in MLL rearranged and non-rearranged primary human AML cells (6 MLL rearranged, 6 MLL germline). Similar to our findings in cell lines, we found a significantly higher effect on cell proliferation/viability in association with the presence of an MLL translocation (p=0.005) and a significant correlation with the baseline HOXA9 mRNA expression (R= 0.8, p=0.001). Next, we assessed the in vivo effect of HOXA9 knock down by transplanting luciferase-expressing SEMK2 (t4;11) cells and subsequent bioluminescent imaging. SEMK2 cells were transduced with either HOXA9 directed or control shRNA and intravenously injected into SCID-beige mice. Reconstitution was confirmed by in vivo bioluminescent imaging. 34 days after transplantation all mice in the HOXA9 shRNA group (n=4) are still alive with no signs of leukemia whereas all mice in the control group (n=3) have succumbed. Taken together our data implicates an important role for aberrant HOXA9 expression in human MLL rearranged leukemia cells.
Mark P Kamps - One of the best experts on this subject based on the ideXlab platform.
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nup98 nsd1 links h3k36 methylation to hox a gene activation and leukaemogenesis
Nature Cell Biology, 2007Co-Authors: Gang Greg Wang, Martina P. Pasillas, Ling Cai, Mark P KampsAbstract:Nuclear receptor-binding SET domain protein 1 (NSD1) prototype is a family of mammalian histone methyltransferases (NSD1, NSD2/MMSET/WHSC1, NSD3/WHSC1L1) that are essential in development and are mutated in human acute myeloid leukemia (AML), overgrowth syndromes, multiple myeloma and lung cancers. In AML, the recurring t(5;11)(q35;p15.5) translocation fuses NSD1 to nucleoporin-98 (NUP98). Here, we present the first characterization of the transforming properties and molecular mechanisms of NUP98-NSD1. We demonstrate that NUP98-NSD1 induces AML in vivo, sustains self-renewal of myeloid stem cells in vitro, and enforces expression of the HoxA7, HOXA9, HoxA10 and Meis1 proto-oncogenes. Mechanistically, NUP98-NSD1 binds genomic elements adjacent to HoxA7 and HOXA9, maintains histone H3 Lys 36 (H3K36) methylation and histone acetylation, and prevents EZH2-mediated transcriptional repression of the Hox-A locus during differentiation. Deletion of the NUP98 FG-repeat domain, or mutations in NSD1 that inactivate the H3K36 methyltransferase activity or that prevent binding of NUP98-NSD1 to the Hox-A locus precluded both Hox-A gene activation and myeloid progenitor immortalization. We propose that NUP98-NSD1 prevents EZH2-mediated repression of Hox-A locus genes by colocalizing H3K36 methylation and histone acetylation at regulatory DNA elements. This report is the first to link deregulated H3K36 methylation to tumorigenesis and to link NSD1 to transcriptional regulation of the Hox-A locus.
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persistent transactivation by meis1 replaces hox function in myeloid leukemogenesis models evidence for co occupancy of meis1 pbx and hox pbx complexes on promoters of leukemia associated genes
Molecular and Cellular Biology, 2006Co-Authors: Gang Greg Wang, Martina P. Pasillas, Mark P KampsAbstract:Homeobox transcription factors Meis1 and HOXA9 promote hematopoietic progenitor self-renewal and cooperate to cause acute myeloid leukemia (AML). While HOXA9 alone blocks the differentiation of nonleukemogenic myeloid cell-committed progenitors, coexpression with Meis1 is required for the production of AML-initiating progenitors, which also transcribe a group of hematopoietic stem cell genes, including Cd34 and Flt3 (defined as Meis1-related leukemic signature genes). Here, we use dominant trans-activating (Vp16 fusion) or trans-repressing (engrailed fusion) forms of Meis1 to define its biochemical functions that contribute to leukemogenesis. Surprisingly, Vp16-Meis1 (but not engrailed-Meis1) functioned as an autonomous oncoprotein that mimicked combined activities of Meis1 plus HOXA9, immortalizing early progenitors, inducing low-level expression of Meis1-related signature genes, and causing leukemia without coexpression of exogenous or endogenous Hox genes. Vp16-Meis1-mediated transformation required the Meis1 function of binding to Pbx and DNA but not its C-terminal domain (CTD). The absence of endogenous Hox gene expression in Vp16-Meis1-immortalized progenitors allowed us to investigate how Hox alters gene expression and cell biology in early hematopoietic progenitors. Strikingly, expression of HOXA9 or Hoxa7 stimulated both leukemic aggressiveness and transcription of Meis1-related signature genes in Vp16-Meis1 progenitors. Interestingly, while the HOXA9 N-terminal domain (NTD) is essential for cooperative transformation with wild-type Meis1, it was dispensable in Vp16-Meis1 progenitors. The fact that a dominant transactivation domain fused to Meis1 replaces the essential functions of both the Meis1 CTD and HOXA9 NTD suggests that Meis-Pbx and Hox-Pbx (or Hox-Pbx-Meis) complexes co-occupy cellular promoters that drive leukemogenesis and that Meis1 CTD and Hox NTD cooperate in gene activation. Chromatin immunoprecipitation confirmed co-occupancy of HOXA9 and Meis1 on the Flt3 promoter.
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Nup98-HOXA9 immortalizes myeloid progenitors, enforces expression of HOXA9, Hoxa7 and Meis1, and alters cytokine-specific responses in a manner similar to that induced by retroviral co-expression of HOXA9 and Meis1
Oncogene, 2002Co-Authors: Katherine R Calvo, Martina P. Pasillas, David B Sykes, Mark P KampsAbstract:The association between acute myeloid leukaemia (AML) and the aberrant expression of HOXA9 is evidenced by (1) proviral activation of HOXA9 and Meis1 in BXH-2 murine AML, (2) formation of the chimeric Nup98-HOXA9 transactivator protein as a consequence of the t(7;11) translocation in human AML, and (3) the strong expression of HOXA9 and Meis1 in human AML. In mouse models, enforced retroviral expression of HOXA9 alone in marrow is not sufficient to cause rapid AML, while co-expression of Meis1 and HOXA9 induces rapid AML. In contrast, retroviral expression of Nup98-HOXA9 is sufficient to cause rapid AML in the absence of enforced Meis1 expression. Previously, we demonstrated that HOXA9 could block the differentiation of murine marrow progenitors cultured in granulocyte-macrophage colony-simulating factor (GM–CSF). These progenitors lacked Meis1 expression, could not proliferate in stem cell factor (SCF), but could differentiate into neutrophils when switched into granulocyte colony-simulating factor (G-CSF). Ectopic expression of Meis1 in these HOXA9 cells suppressed their G-CSF-induced differentiation, permitted proliferation in SCF, and therein offered a potential explanation of cooperative function. Because Meis1 binds N-terminal HOXA9 sequences that are replaced by Nup98, we hypothesized that Nup98-HOXA9 might consolidate the biochemical functions of both HOXA9 and Meis1 on target gene promoters and might evoke their same lymphokine-responsive profile in immortalized progenitors. Here we report that Nup98-HOXA9, indeed mimicks HOXA9 plus Meis1 coexpression – it immortalizes myeloid progenitors, prevents differentiation in response to GM–CSF, IL-3, G-CSF, and permits proliferation in SCF. Unexpectedly, however, Nup98-HOXA9 also enforced strong transcription of the cellular HOXA9 , Hoxa7 and Meis1 genes at levels similar to those found in mouse AML's generated by proviral activation of HOXA9 and Meis1 . Using HOXA9^−/− marrow, we demonstrate that expression of HOXA9 is not required for myeloid immortalization by Nup98-HOXA9. Rapid leukaemogenesis by Nup98-HOXA9 may therefore result from both the intrinsic functions of Nup98-HOXA9, as well as of those of coexpressed HOX and MEIS1 genes.
Kazuma Ohyashiki - One of the best experts on this subject based on the ideXlab platform.
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single translocation and double chimeric transcripts detection of nup98 HOXA9 in myeloid leukemias withhoxa11 or hoxa13 breaks of the chromosomal translocation t 7 11 p15 p15
Blood, 2002Co-Authors: Takashi Fujino, Kazuma Ohyashiki, A Suzuki, Yoshikazu Ito, Yoshiaki Hatano, Ikuo Miura, Takuro NakamuraAbstract:It has been demonstrated that the chromosomal translocation t(7;11)(p15;p15) in patients with human acute myelogenous leukemia (AML) and chronic myelogenous leukemia (CML) invariably involves fusion of the nucleoporin gene, NUP98, on chromosome 11 and the class 1 HOX gene, HOXA9, on chromosome 7, and that the fusion gene NUP98-HOXA9 is an important gene in myeloid leukemogenesis. Here are reported 2 novel chromosome 7p15 targets of the t(7;11)(p15;p15) chromosomal translocation in 2 patients with CML and myelodysplastic syndrome (MDS). Southern blot and polymerase chain reaction (PCR) analyses of leukemia cell DNA failed to show rearrangement of HOXA9,whereas NUP98 was found to be rearranged in both cases. Reverse transcription-PCR analysis using a NUP98 primer and a degenerate primer corresponding to the third helix of the homeodomain of HOXA demonstrated that NUP98 was fused in-frame to HOXA11 in the patient with CML and toHOXA13 in the patient with MDS. The chromosomal breakpoints on 7p15 were located within introns of HOXA11 orHOXA13 genes. In both patients chimericNUP98-HOXA9 transcripts were also observed. These findings suggest that AbdB-type HOXA genes are common targets of t(7;11)(p15;p15) chromosomal translocations and that a single translocation can produce more than oneNUP98-HOXA fusion gene, presumably because of altered splicing.
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single translocation and double chimeric transcripts detection of nup98 HOXA9 in myeloid leukemias with hoxa11 or hoxa13 breaks of the chromosomal translocation t 7 11 p15 p15
Blood, 2002Co-Authors: Takashi Fujino, Kazuma Ohyashiki, A Suzuki, Yoshikazu Ito, Yoshiaki Hatano, Ikuo Miura, Takuro NakamuraAbstract:It has been demonstrated that the chromosomal translocation t(7;11)(p15;p15) in patients with human acute myelogenous leukemia (AML) and chronic myelogenous leukemia (CML) invariably involves fusion of the nucleoporin gene, NUP98 , on chromosome 11 and the class 1 HOX gene, HOXA9 , on chromosome 7, and that the fusion gene NUP98 - HOXA9 is an important gene in myeloid leukemogenesis. Here are reported 2 novel chromosome 7p15 targets of the t(7;11)(p15;p15) chromosomal translocation in 2 patients with CML and myelodysplastic syndrome (MDS). Southern blot and polymerase chain reaction (PCR) analyses of leukemia cell DNA failed to show rearrangement of HOXA9, whereas NUP98 was found to be rearranged in both cases. Reverse transcription-PCR analysis using a NUP98 primer and a degenerate primer corresponding to the third helix of the homeodomain of HOXA demonstrated that NUP98 was fused in-frame to HOXA11 in the patient with CML and to HOXA13 in the patient with MDS. The chromosomal breakpoints on 7p15 were located within introns of HOXA11 or HOXA13 genes. In both patients chimeric NUP98-HOXA9 transcripts were also observed. These findings suggest that AbdB-type HOXA genes are common targets of t(7;11)(p15;p15) chromosomal translocations and that a single translocation can produce more than one NUP98 - HOXA fusion gene, presumably because of altered splicing.
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meis1 and hoxa7 genes in human acute myeloid leukemia
Leukemia Research, 2000Co-Authors: Olubunmi Afonja, Kazuma Ohyashiki, John Smith, Debbie M Cheng, Alec Goldenberg, Edward L Amorosi, Takashi Shimamoto, Shuji Nakamura, Junko H Ohyashiki, Keisuke ToyamaAbstract:Co-activation of Meisl with Hoxa7 or HOXA9 homeobox genes by retroviral gene insertion has recently been reported to be leukemogenic in murine myeloid leukemia. In this study we determined their expression in human leukemia. Most human myeloid leukemia cell lines co-expressed MEIS1 with HOXA7 and HOXA9. Among patients with acute leukemia, 50% of AML patients expressed MEIS1, while the majority of ALL patients were negative. A total of 89.5% of patients expressing MEIS1 co-expressed HOXA7. In unadjusted models, poorer response to chemotherapy was associated with expression of HOXA7 regardless of MEIS1 status and older patients were more likely to express either gene.
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fusion of the nucleoporin gene nup98 to HOXA9 by the chromosome translocation t 7 11 p15 p15 in human myeloid leukaemia
Nature Genetics, 1996Co-Authors: Takuro Nakamura, David A Largaespada, Laura A Johnson, Kazuma Ohyashiki, Keisuke Toyama, Sai Juan Chen, Cheryl L Willman, Iming Chen, Andrew P Feinberg, Nancy A JenkinsAbstract:Expression of HoxaT and HOXA9 is activated by proviral integration in BXH2 murine myeloid leukaemias. This result, combined with the mapping of the HOXA locus to human chromosome 7p15, suggested that one of the HOXA genes might be involved in the t(7;11)(p15;p15) translocation found in some human myeloid leukaemia patients. Here we show that in three patients with t(7;11), the chromosome rearrangement creates a genomic fusion between the HOXA9 gene and the nucleoporin gene NUP98 on chromosome 11 p15. The translocation produces an invariant chimaeric NUP98/HOXA9 transcript containing the amino terminal half of NUP98 fused in frame to HOXA9. These studies identify HOXA9 as an important human myeloid leukaemia gene and suggest an important role for nucleoporins in human myeloid leukaemia given that a second nucleoporin, NUP214, has also been implicated in human myeloid leukaemia.
Nancy A Jenkins - One of the best experts on this subject based on the ideXlab platform.
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fusion of the nucleoporin gene nup98 to HOXA9 by the chromosome translocation t 7 11 p15 p15 in human myeloid leukaemia
Nature Genetics, 1996Co-Authors: Takuro Nakamura, David A Largaespada, Laura A Johnson, Kazuma Ohyashiki, Keisuke Toyama, Sai Juan Chen, Cheryl L Willman, Iming Chen, Andrew P Feinberg, Nancy A JenkinsAbstract:Expression of HoxaT and HOXA9 is activated by proviral integration in BXH2 murine myeloid leukaemias. This result, combined with the mapping of the HOXA locus to human chromosome 7p15, suggested that one of the HOXA genes might be involved in the t(7;11)(p15;p15) translocation found in some human myeloid leukaemia patients. Here we show that in three patients with t(7;11), the chromosome rearrangement creates a genomic fusion between the HOXA9 gene and the nucleoporin gene NUP98 on chromosome 11 p15. The translocation produces an invariant chimaeric NUP98/HOXA9 transcript containing the amino terminal half of NUP98 fused in frame to HOXA9. These studies identify HOXA9 as an important human myeloid leukaemia gene and suggest an important role for nucleoporins in human myeloid leukaemia given that a second nucleoporin, NUP214, has also been implicated in human myeloid leukaemia.
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cooperative activation of hoxa and pbx1 related genes in murine myeloid leukaemias
Nature Genetics, 1996Co-Authors: Takuro Nakamura, David A Largaespada, Nancy A Jenkins, John D Shaughnessy, Neal G CopelandAbstract:Abstract Retroviruses induce myeloid leukaemia in BXH-2 mice by the insertional mutation of cellular proto-oncogenes or tumour suppressor genes. Disease genes can thus be identified by proviral tagging through the identification of common viral integration sites in BXH-2 leukaemia. Here, we describe a new approach for proviral tagging that greatly facilitates the identification of BXH-2 leukaemia genes. Using this approach, we identify three genes whose expression is activated by proviral integration in BXH-2 leukaemias; Hoxa7, HOXA9, and a Pbx1-related homeobox gene, Meis1. Proviral activation of Hoxa7 or HOXA9 is strongly correlated with proviral activation of Meis1 implying that Hoxa7 and HOXA9 cooperate with Meis1 in leukaemia formation. These studies provide the first genetic evidence that Pbx1-related genes cooperate with Hox genes in leukaemia formation and identify a number of new murine myeloid leukaemia genes.