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1.
Proc Natl Acad Sci U S A ; 115(41): 10357-10362, 2018 10 09.
Artigo em Inglês | MEDLINE | ID: mdl-30257940

RESUMO

PAX5 is a well-known haploinsufficient tumor suppressor gene in human B-cell precursor acute lymphoblastic leukemia (B-ALL) and is involved in various chromosomal translocations that fuse a part of PAX5 with other partners. However, the role of PAX5 fusion proteins in B-ALL initiation and transformation is ill-known. We previously reported a new recurrent t(7;9)(q11;p13) chromosomal translocation in human B-ALL that juxtaposed PAX5 to the coding sequence of elastin (ELN). To study the function of the resulting PAX5-ELN fusion protein in B-ALL development, we generated a knockin mouse model in which the PAX5-ELN transgene is expressed specifically in B cells. PAX5-ELN-expressing mice efficiently developed B-ALL with an incidence of 80%. Leukemic transformation was associated with recurrent secondary mutations on Ptpn11, Kras, Pax5, and Jak3 genes affecting key signaling pathways required for cell proliferation. Our functional studies demonstrate that PAX5-ELN affected B-cell development in vitro and in vivo featuring an aberrant expansion of the pro-B cell compartment at the preleukemic stage. Finally, our molecular and computational approaches identified PAX5-ELN-regulated gene candidates that establish the molecular bases of the preleukemic state to drive B-ALL initiation. Hence, our study provides a new in vivo model of human B-ALL and strongly implicates PAX5 fusion proteins as potent oncoproteins in leukemia development.


Assuntos
Elastina/genética , Proteínas de Fusão Oncogênica/genética , Fator de Transcrição PAX5/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , Animais , Linfócitos B/patologia , Linfócitos B/fisiologia , Elastina/metabolismo , Regulação Leucêmica da Expressão Gênica , Técnicas de Introdução de Genes , Janus Quinase 3/genética , Camundongos Transgênicos , Mutação , Neoplasias Experimentais , Proteínas de Fusão Oncogênica/metabolismo , Fator de Transcrição PAX5/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 11/genética , Proteínas Proto-Oncogênicas p21(ras)/genética
3.
J Exp Med ; 221(1)2024 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-37930337

RESUMO

B cell acute lymphoblastic leukemia (B-ALL) is a multistep disease characterized by the hierarchical acquisition of genetic alterations. However, the question of how a primary oncogene reprograms stem cell-like properties in committed B cells and leads to a preneoplastic population remains unclear. Here, we used the PAX5::ELN oncogenic model to demonstrate a causal link between the differentiation blockade, the self-renewal, and the emergence of preleukemic stem cells (pre-LSCs). We show that PAX5::ELN disrupts the differentiation of preleukemic cells by enforcing the IL7r/JAK-STAT pathway. This disruption is associated with the induction of rare and quiescent pre-LSCs that sustain the leukemia-initiating activity, as assessed using the H2B-GFP model. Integration of transcriptomic and chromatin accessibility data reveals that those quiescent pre-LSCs lose B cell identity and reactivate an immature molecular program, reminiscent of human B-ALL chemo-resistant cells. Finally, our transcriptional regulatory network reveals the transcription factor EGR1 as a strong candidate to control quiescence/resistance of PAX5::ELN pre-LSCs as well as of blasts from human B-ALL.


Assuntos
Linfoma de Burkitt , Leucemia , Humanos , Janus Quinases , Fatores de Transcrição STAT , Transdução de Sinais , Células-Tronco
4.
Blood ; 117(21): 5719-22, 2011 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-21474671

RESUMO

Acute basophilic leukemia (ABL) is a rare subtype of acute leukemia with clinical features and symptoms related to hyperhistaminemia because of excessive growth of basophils. No known recurrent cytogenetic abnormality is associated with this leukemia. Rare cases of t(X;6)(p11;q23) translocation have been described but these were sporadic. We report here 4 cases of ABL with a t(X;6)(p11;q23) translocation occurring in male infants. Because of its location on chromosome 6q23, MYB was a good candidate gene. Our molecular investigations, based on fluorescence in situ hybridization and rapid amplification of cDNA ends, revealed that the translocation generated a MYB-GATA1 fusion gene. Expression of MYB-GATA1 in mouse lineage-negative cells committed them to the granulocyte lineage and blocked at an early stage of differentiation. Taken together, these results establish, for the first time, a link between a recurrent chromosomal translocation and the development of this particular subtype of infant leukemia.


Assuntos
Fator de Transcrição GATA1/genética , Leucemia Basofílica Aguda/genética , Proteínas de Fusão Oncogênica/genética , Oncogenes/genética , Proteínas Proto-Oncogênicas c-myb/genética , Animais , Western Blotting , Cromossomos Humanos Par 6/genética , Cromossomos Humanos X/genética , Feminino , Humanos , Hibridização in Situ Fluorescente , Lactente , Cariotipagem , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Prognóstico , RNA Mensageiro/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Translocação Genética , Ensaio Tumoral de Célula-Tronco
5.
Bull Cancer ; 110(3): 331-335, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36775700

RESUMO

This article highlights the presentations from the 2021 scientific meeting of the Club Hematopoiesis and Oncogenesis. This annual meeting focuses on hematopoiesis and oncogenic mechanisms. Various topics were presented: expansion of hematopoietic stem cells with in vivo and ex vivo strategies, the role of the hematopoietic stem cell niches in aging and leukemic resistance, the crossroad between hematology and immunology, the importance of the metabolism in normal hematopoiesis and hematopoietic defects, solid tumors and oncogenesis, the noncoding genome, inflammation in monocyte differentiation and leukemia, and importantly, the recent advances in myeloid malignancies, lymphoid leukemia and lymphoma.


Assuntos
Leucemia , Linfoma , Humanos , Hematopoese/genética , Células-Tronco Hematopoéticas , Transformação Celular Neoplásica/metabolismo , Transformação Celular Neoplásica/patologia
6.
iScience ; 26(4): 106385, 2023 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-37009219

RESUMO

B-cell acute lymphoblastic leukemia (B-ALL) reflects the malignant counterpart of developing B cells in the bone marrow (BM). Despite tremendous progress in B-ALL treatment, the overall survival of adults at diagnosis and patients at all ages after relapse remains poor. Galectin-1 (GAL1) expressed by BM supportive niches delivers proliferation signals to normal pre-B cells through interaction with the pre-B cell receptor (pre-BCR). Here, we asked whether GAL1 gives non-cell autonomous signals to pre-BCR+ pre-B ALL, in addition to cell-autonomous signals linked to genetic alterations. In syngeneic and patient-derived xenograft (PDX) murine models, murine and human pre-B ALL development is influenced by GAL1 produced by BM niches through pre-BCR-dependent signals, similarly to normal pre-B cells. Furthermore, targeting pre-BCR signaling together with cell-autonomous oncogenic pathways in pre-B ALL PDX improved treatment response. Our results show that non-cell autonomous signals transmitted by BM niches represent promising targets to improve B-ALL patient survival.

7.
Blood ; 115(15): 3089-97, 2010 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-20160164

RESUMO

PAX5 is the main target of somatic mutations in acute B lymphoblastic leukemia (B-ALL). We analyzed 153 adult and child B-ALL harboring karyotypic abnormalities at chromosome 9p, to determine the frequency and the nature of PAX5 alterations. We found PAX5 internal rearrangements in 21% of the cases. To isolate fusion partners, we used classic and innovative techniques (rolling circle amplification-rapid amplification of cDNA ends) and single nucleotide polymorphism-comparative genomic hybridization arrays. Recurrent and novel fusion partners were identified, including NCoR1, DACH2, GOLGA6, and TAOK1 genes showing the high variability of the partners. We noted that half the fusion genes can give rise to truncated PAX5 proteins. Furthermore, malignant cells carrying PAX5 fusion genes displayed a simple karyotype. These data strongly suggest that PAX5 fusion genes are early players in leukemogenesis. In addition, PAX5 deletion was observed in 60% of B-ALL with 9p alterations. Contrary to cases with PAX5 fusions, deletions were associated with complex karyotypes and common recurrent translocations. This supports the hypothesis of the secondary nature of the deletion. Our data shed more light on the high variability of PAX5 alterations in B-ALL. Therefore, it is probable that gene fusions occur early, whereas deletions should be regarded as a late/secondary event.


Assuntos
Análise Citogenética , Mutação/genética , Fator de Transcrição PAX5/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras B/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Pontos de Quebra do Cromossomo , Cromossomos Humanos Par 9/genética , Clonagem Molecular , Estudos de Coortes , Feminino , França , Regulação Leucêmica da Expressão Gênica , Humanos , Cariotipagem , Masculino , Pessoa de Meia-Idade , Proteínas de Fusão Oncogênica/genética , Proteínas de Fusão Oncogênica/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras B/patologia , Adulto Jovem
8.
Blood Adv ; 6(2): 386-398, 2022 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-34638130

RESUMO

Myelodysplastic syndromes (MDS) represent a heterogeneous group of clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis leading to peripheral cytopenias and in a substantial proportion of cases to acute myeloid leukemia. The deletion of the long arm of chromosome 11, del(11q), is a rare but recurrent clonal event in MDS. Here, we detail the largest series of 113 cases of MDS and myelodysplastic syndromes/myeloproliferative neoplasms (MDS/MPN) harboring a del(11q) analyzed at clinical, cytological, cytogenetic, and molecular levels. Female predominance, a survival prognosis similar to other MDS, a low monocyte count, and dysmegakaryopoiesis were the specific clinical and cytological features of del(11q) MDS. In most cases, del(11q) was isolated, primary and interstitial encompassing the 11q22-23 region containing ATM, KMT2A, and CBL genes. The common deleted region at 11q23.2 is centered on an intergenic region between CADM1 (also known as Tumor Suppressor in Lung Cancer 1) and NXPE2. CADM1 was expressed in all myeloid cells analyzed in contrast to NXPE2. At the functional level, the deletion of Cadm1 in murine Lineage-Sca1+Kit+ cells modifies the lymphoid-to-myeloid ratio in bone marrow, although not altering their multilineage hematopoietic reconstitution potential after syngenic transplantation. Together with the frequent simultaneous deletions of KMT2A, ATM, and CBL and mutations of ASXL1, SF3B1, and CBL, we show that CADM1 may be important in the physiopathology of the del(11q) MDS, extending its role as tumor-suppressor gene from solid tumors to hematopoietic malignancies.


Assuntos
Molécula 1 de Adesão Celular/metabolismo , Leucemia Mieloide Aguda , Síndromes Mielodisplásicas , Animais , Molécula 1 de Adesão Celular/genética , Deleção Cromossômica , Cromossomos Humanos Par 11 , Feminino , Genes Supressores de Tumor , Humanos , Leucemia Mieloide Aguda/genética , Camundongos , Síndromes Mielodisplásicas/genética , Síndromes Mielodisplásicas/patologia
9.
Artigo em Inglês | MEDLINE | ID: mdl-33608382

RESUMO

Diagnosis of B-cell chronic lymphocytic leukemia (B-CLL) is usually straightforward, involving clinical, immunophenotypic (Matutes score), and (immuno)genetic analyses (to refine patient prognosis for treatment). CLL cases with atypical presentation (e.g., Matutes ≤ 3) are also encountered, and for these diseases, biology and prognostic impact are less clear. Here we report the genomic characterization of a case of atypical B-CLL in a 70-yr-old male patient; B-CLL cells showed a Matutes score of 3, chromosomal translocation t(14;18)(q32;q21) (BCL2/IGH), mutated IGHV, deletion 17p, and mutations in BCL2, NOTCH1 (subclonal), and TP53 (subclonal). Quite strikingly, a novel PAX5 mutation that was predicted to be loss of function was also seen. Exome sequencing identified, in addition, a potentially actionable BRAF mutation, together with novel somatic mutations affecting the homeobox transcription factor NKX2-3, known to control B-lymphocyte development and homing, and the epigenetic regulator LRIF1, which is implicated in chromatin compaction and gene silencing. Neither NKX2-3 nor LRIF1 mutations, predicted to be loss of function, have previously been reported in B-CLL. Sequencing confirmed the presence of these mutations together with BCL2, NOTCH1, and BRAF mutations, with the t(14;18)(q32;q21) translocation, in the initial diagnostic sample obtained 12 yr prior. This is suggestive of a role for these novel mutations in B-CLL initiation and stable clonal evolution, including upon treatment withdrawal. This case extends the spectrum of atypical B-CLL with t(14;18)(q32;q21) and highlights the value of more global precision genomics for patient follow-up and treatment in these patients.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Epigênese Genética , Proteínas de Homeodomínio/genética , Leucemia Linfocítica Crônica de Células B/genética , Mutação , Fator de Transcrição PAX5/genética , Proteínas Proto-Oncogênicas B-raf/metabolismo , Fatores de Transcrição/genética , Idoso , Proteínas de Ciclo Celular/genética , Evolução Clonal , Proteínas de Homeodomínio/metabolismo , Humanos , Leucemia Linfocítica Crônica de Células B/tratamento farmacológico , Masculino , Fator de Transcrição PAX5/metabolismo , Prognóstico , Proteínas Proto-Oncogênicas B-raf/genética , Proteínas Proto-Oncogênicas c-bcl-2/genética , Receptor Notch1/genética , Fatores de Transcrição/metabolismo , Translocação Genética , Proteína Supressora de Tumor p53/genética , Sequenciamento do Exoma
10.
Eur J Immunol ; 39(8): 2270-80, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19609977

RESUMO

Macrophages are central players in both lipid metabolism and innate immunity. Their determinant role in the pathogenesis of atherosclerosis is under the control of the ATP-binding cassette transporter (ABCA1), which by minimizing cellular lipid content, limits development of pro-inflammatory foam cells. Considering the differential contribution of monocyte subsets to the generation of vascular lesions we analyzed the immunophenotype of ABCA1-expressing cells in the myeloid lineage, by the combined use of flow cytometry and real-time quantitative RT-PCR. ABCA1 expression is limited to "non-inflammatory" Ly6C(lo) circulating monocytes and tissue-resident macrophages expressing markers of alternative activation. In ABCA1(-/-) peritoneal macrophages the transcriptional programs induced by LPS/IFN-gamma or IL-4 cytokines are altered and deviated phosphorylation patterns of STAT transcriptional regulators in response to stimuli are observed.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Citocinas/farmacologia , Macrófagos/efeitos dos fármacos , Transportador 1 de Cassete de Ligação de ATP , Transportadores de Cassetes de Ligação de ATP/genética , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Western Blotting , Células Cultivadas , Ciclo-Oxigenase 2/metabolismo , Citometria de Fluxo , Perfilação da Expressão Gênica , Células HeLa , Humanos , Imunofenotipagem , Interferon gama/farmacologia , Interleucina-4/farmacologia , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Macrófagos/citologia , Macrófagos/metabolismo , Macrófagos Peritoneais/citologia , Macrófagos Peritoneais/efeitos dos fármacos , Macrófagos Peritoneais/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Camundongos Knockout , Fosforilação/efeitos dos fármacos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fator de Transcrição STAT1/metabolismo , Especificidade da Espécie
11.
Oncotarget ; 9(67): 32841-32854, 2018 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-30214688

RESUMO

Pax5 is the guardian of the B cell identity since it primes or enhances the expression of B cell specific genes and concomitantly represses the expression of B cell inappropriate genes. The tight regulation of Pax5 is therefore required for an efficient B cell differentiation. A defect in its dosage can translate into immunodeficiency or malignant disorders such as leukemia or lymphoma. Pax5 is expressed from two different promoters encoding two isoforms that only differ in the sequence of their first alternative exon. Very little is known regarding the role of the two isoforms during B cell differentiation and the regulation of their expression. Our work aims to characterize the mechanisms of regulation of the expression balance of these two isoforms and their implication in the B cell differentiation process using murine ex vivo analyses. We show that these two isoforms are differentially regulated but have equivalent function during early B cell differentiation and may have functional differences after B cell activation. The tight control of their expression may thus reflect a way to finely tune Pax5 dosage during B cell differentiation process.

12.
Mol Cell Biol ; 24(5): 1870-83, 2004 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-14966269

RESUMO

Analysis of cis-regulatory elements is central to understanding the genomic program for development. The scl/tal-1 transcription factor is essential for lineage commitment to blood cell formation and previous studies identified an scl enhancer (the +18/19 element) which was sufficient to target the vast majority of hematopoietic stem cells, together with hematopoietic progenitors and endothelium. Moreover, expression of scl under control of the +18/19 enhancer rescued blood progenitor formation in scl(-/-) embryos. However, here we demonstrate by using a knockout approach that, within the endogenous scl locus, the +18/19 enhancer is not necessary for the initiation of scl transcription or for the formation of hematopoietic cells. These results led to the identification of a bifunctional 5' enhancer (-3.8 element), which targets expression to hematopoietic progenitors and endothelium, contains conserved critical Ets sites, and is bound by Ets family transcription factors, including Fli-1 and Elf-1. These data demonstrate that two geographically distinct but functionally related enhancers regulate scl transcription in hematopoietic progenitors and endothelial cells and suggest that enhancers with dual hematopoietic-endothelial activity may represent a general strategy for regulating blood and endothelial development.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Elementos Facilitadores Genéticos , Hematopoese/fisiologia , Células-Tronco Hematopoéticas/fisiologia , Proteínas Proto-Oncogênicas/metabolismo , Fatores de Transcrição/metabolismo , Animais , Sequência de Bases , Fatores de Transcrição Hélice-Alça-Hélice Básicos , Linhagem da Célula , Proteínas de Ligação a DNA/genética , Embrião de Mamíferos/anatomia & histologia , Embrião de Mamíferos/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , Genes Reporter , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Dados de Sequência Molecular , Proteínas Nucleares , Proteína Proto-Oncogênica c-fli-1 , Proteínas Proto-Oncogênicas/genética , Alinhamento de Sequência , Proteína 1 de Leucemia Linfocítica Aguda de Células T , Transativadores/metabolismo , Fatores de Transcrição/genética , Transcrição Gênica
13.
Nat Commun ; 7: 11889, 2016 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-27297662

RESUMO

NKX2 homeobox family proteins have a role in cancer development. Here we show that NKX2-3 is overexpressed in tumour cells from a subset of patients with marginal-zone lymphomas, but not with other B-cell malignancies. While Nkx2-3-deficient mice exhibit the absence of marginal-zone B cells, transgenic mice with expression of NKX2-3 in B cells show marginal-zone expansion that leads to the development of tumours, faithfully recapitulating the principal clinical and biological features of human marginal-zone lymphomas. NKX2-3 induces B-cell receptor signalling by phosphorylating Lyn/Syk kinases, which in turn activate multiple integrins (LFA-1, VLA-4), adhesion molecules (ICAM-1, MadCAM-1) and the chemokine receptor CXCR4. These molecules enhance migration, polarization and homing of B cells to splenic and extranodal tissues, eventually driving malignant transformation through triggering NF-κB and PI3K-AKT pathways. This study implicates oncogenic NKX2-3 in lymphomagenesis, and provides a valid experimental mouse model for studying the biology and therapy of human marginal-zone B-cell lymphomas.


Assuntos
Proteínas de Homeodomínio/genética , Linfócitos/metabolismo , Linfoma de Zona Marginal Tipo Células B/genética , Receptores de Antígenos de Linfócitos B/genética , Transdução de Sinais/genética , Fatores de Transcrição/genética , Animais , Moléculas de Adesão Celular/genética , Moléculas de Adesão Celular/metabolismo , Perfilação da Expressão Gênica , Proteínas de Homeodomínio/metabolismo , Humanos , Estimativa de Kaplan-Meier , Tecido Linfoide/metabolismo , Linfoma de Zona Marginal Tipo Células B/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosforilação , Receptores de Antígenos de Linfócitos B/metabolismo , Quinase Syk/genética , Quinase Syk/metabolismo , Fatores de Transcrição/metabolismo
14.
J Immunol Methods ; 384(1-2): 103-10, 2012 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-22867746

RESUMO

Mice with virtually all T cells expressing a single T cell receptor (TCR) on their surface have been instrumental in understanding the development of immature thymocytes. For many years, such an engineering has been achieved essentially by inserting rearranged TCR α and ß chain coding sequences into the genome through co-microinjection into fertilized eggs (TCR transgenesis). More recently, a novel methodology relying on the reconstitution of T cell deficient hosts with retrovirally-transduced multipotent bone marrow cells has been developed. Hence, TCR retrogenesis allows for the in vivo study of given TCR specificities in a faster and less expensive manner. While initial procedures were taking advantage of 5-Fluorouracil (5-FU) treatment of RAG-deficient or SCID donor mice as source of haematopoietic stem cells, we used bone marrow cell suspensions enriched in lineage antigen-negative (Lin−) cells from untreated donors for TCR retrogenesis. In contrast to cells from 5-FU-treated donors, transduced Lin−cells consistently generated a sizable retrogenic pool of thymocytes and required less donor mice. In such retrogenic mice, immature thymocytes bearing a major histocompatibility complex (MHC) class II-restricted TCR differentiated into the expected CD4 mature T cell lineage and populated the peripheral lymphoid organs where they retained the capacity to react to their cognate ligand. Lin− cell-enriched BM cells represent therefore, a reliable alternative to 5-FU treatment for retroviral transduction of haematopoietic stem cells and TCR retrogenic derivation.


Assuntos
Células da Medula Óssea/imunologia , Linfócitos T CD4-Positivos/imunologia , Diferenciação Celular/imunologia , Receptores de Antígenos de Linfócitos T/imunologia , Animais , Antimetabólitos/farmacologia , Células da Medula Óssea/efeitos dos fármacos , Células da Medula Óssea/metabolismo , Linfócitos T CD4-Positivos/metabolismo , Diferenciação Celular/genética , Linhagem da Célula/genética , Linhagem da Célula/imunologia , Citometria de Fluxo , Fluoruracila/farmacologia , Células HEK293 , Humanos , Linfonodos/citologia , Linfonodos/imunologia , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos NOD , Camundongos Knockout , Camundongos SCID , Receptores de Antígenos de Linfócitos T/genética , Retroviridae/genética , Baço/citologia , Baço/imunologia , Timócitos/imunologia , Timócitos/metabolismo , Transdução Genética
15.
Exp Hematol ; 40(7): 588-598.e1, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22401818

RESUMO

The stem cell leukemia (Scl)/Tal1 gene is essential for normal blood and endothelial development, and is expressed in hematopoietic stem cells (HSCs), progenitors, erythroid, megakaryocytic, and mast cells. The Scl +19 enhancer is active in HSCs and progenitor cells, megakaryocytes, and mast cells, but not mature erythroid cells. Here we demonstrate that in vivo deletion of the Scl +19 enhancer (Scl(Δ19/Δ19)) results in viable mice with normal Scl expression in mature hematopoietic lineages. By contrast, Scl expression is reduced in the stem/progenitor compartment and flow cytometry analysis revealed that the HSC and megakaryocyte-erythroid progenitor populations are enlarged in Scl(Δ19/Δ19) mice. The increase in HSC numbers contributed to enhanced expansion in bone marrow transplantation assays, but did not affect multilineage repopulation or stress responses. These results affirm that the Scl +19 enhancer plays a key role in the development of hematopoietic stem/progenitor cells, but is not necessary for mature hematopoietic lineages. Moreover, active histone marks across the Scl locus were significantly reduced in Scl(Δ19/Δ19) fetal liver cells without major changes in steady-state messenger RNA levels, suggesting post-transcriptional compensation for loss of a regulatory element, a result that might be widely relevant given the frequent observation of mild phenotypes after deletion of regulatory elements.


Assuntos
Sequência de Bases , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Elementos Facilitadores Genéticos/fisiologia , Regulação da Expressão Gênica/fisiologia , Células-Tronco Hematopoéticas/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Deleção de Sequência , Animais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Hematopoese/fisiologia , Células-Tronco Hematopoéticas/citologia , Camundongos , Camundongos Mutantes , Proteínas Proto-Oncogênicas/genética , Estresse Fisiológico/fisiologia , Proteína 1 de Leucemia Linfocítica Aguda de Células T
16.
Blood ; 109(8): 3417-23, 2007 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-17179230

RESUMO

We report a novel t(7;9)(q11;p13) translocation in 2 patients with B-cell acute lymphoblastic leukemia (B-ALL). By fluorescent in situ hybridization and 3' rapid amplification of cDNA ends, we showed that the paired box domain of PAX5 was fused with the elastin (ELN) gene. After cloning the full-length cDNA of the chimeric gene, confocal microscopy of transfected NIH3T3 cells and Burkitt lymphoma cells (DG75) demonstrated that PAX5-ELN was localized in the nucleus. Chromatin immunoprecipitation clearly indicated that PAX5-ELN retained the capability to bind CD19 and BLK promoter sequences. To analyze the functions of the chimeric protein, HeLa cells were cotransfected with a luc-CD19 construct, pcDNA3-PAX5, and with increasing amounts of pcDNA3-PAX5-ELN. Thus, in vitro, PAX5-ELN was able to block CD19 transcription. Furthermore, real-time quantitative polymerase chain reaction (RQ-PCR) experiments showed that PAX5-ELN was able to affect the transcription of endogenous PAX5 target genes. Since PAX5 is essential for B-cell differentiation, this translocation may account for the blockage of leukemic cells at the pre-B-cell stage. The mechanism involved in this process appears to be, at least in part, through a dominant-negative effect of PAX5-ELN on the wild-type PAX5 in a setting ofPAX5 haploinsufficiency.


Assuntos
Linfoma de Burkitt/genética , Cromossomos Humanos Par 7/genética , Cromossomos Humanos Par 9/genética , Elastina/genética , Genes Dominantes , Proteínas de Fusão Oncogênica/genética , Fator de Transcrição PAX5/genética , Translocação Genética , Adolescente , Adulto , Animais , Antígenos CD19/biossíntese , Antígenos CD19/genética , Linfoma de Burkitt/metabolismo , Linfoma de Burkitt/patologia , Diferenciação Celular/genética , Núcleo Celular/genética , Núcleo Celular/metabolismo , Núcleo Celular/patologia , Elastina/biossíntese , Células HeLa , Humanos , Masculino , Camundongos , Células NIH 3T3 , Proteínas de Fusão Oncogênica/biossíntese , Fator de Transcrição PAX5/biossíntese , Regiões Promotoras Genéticas/genética , Transcrição Gênica/genética
17.
J Neurochem ; 97(2): 345-55, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16539677

RESUMO

The notion that the ATP-binding cassette transporter-A2 (ABCA2) may be involved in brain sterol homeostasis and is associated with early onset Alzheimer's disease led us to explore its neural expression. Our data support and extend the previous reports on ABCA2 expression by oligodendrocytes. They evidence that ABCA2 (i) is located in intracellular vesicles, identified in transfected cells as lysosome-related organelles only partially overlapping with classical endolysosomes; (ii) is a marker of neural progenitors as it is expressed in the subventricular zone of the lateral ventricle and the dentate gyrus of the hippocampal formation, sites of continual neurogenesis in the adult brain, and in nestin(+) cells differentiated in vitro from embryonic stem cells; (iii) persists, in the adult rodent brain, in a subset of GABAergic and glutamatergic neurons. Considering that the latter are targets of Alzheimer's lesions, these data provide a new rationale to explore the neuropathological consequences of ABCA2 functional dysregulations.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Encéfalo/citologia , Neurônios/metabolismo , Células-Tronco/fisiologia , Animais , Biomarcadores/metabolismo , Western Blotting/métodos , Antígeno CD24/metabolismo , Diferenciação Celular/fisiologia , Células Cultivadas , Embrião de Mamíferos , Imunofluorescência/métodos , Expressão Gênica/fisiologia , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Proteína Glial Fibrilar Ácida/metabolismo , Ácido Glutâmico/metabolismo , Humanos , Proteínas Luminescentes/metabolismo , Proteína 1 de Membrana Associada ao Lisossomo/metabolismo , Proteína 2 de Membrana Associada ao Lisossomo/metabolismo , Camundongos , Proteínas Associadas aos Microtúbulos/metabolismo , Neurônios/classificação , Ratos , Frações Subcelulares/metabolismo , Fatores de Tempo , Transfecção/métodos , Ácido gama-Aminobutírico/metabolismo
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