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Autorrenovação de células-tronco hematopoiéticas : papel da via Hedgehog na mielodisplasia e da Arhgap21 na hematopoiese; Hematopoietic stem cells self-renew : the role of the Hedgehog pathway in myelodysplastic syndrome and Arhgap21 in hematopoiesis

Juliana Martins Xavier Ferrucio
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 20/02/2015 PT
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A hematopoiese, processo pelo qual a célula-tronco hematopoiética (CTH) dá origem a todas as células do sangue, é regulada através do seu contato com diversos tipos celulares que compõem o estroma da medula óssea, mantendo o balanço entre autorrenovação e diferenciação das CTHs, processos também regulados por vias de sinalização como a via Hedgehog e proteínas reguladoras de citoesqueleto como RhoGTPases. Sendo assim, os objetivos gerais do trabalho foram investigar a via Hedgehog na medula óssea de pacientes com síndromes mielodisplásica (SMD) e a função da ARHGAP21 na autorrenovação das CTH. Através de imunohistoquímica de bióspias de medula óssea de pacientes com SMD em comparação com anemia megaloblástica (usada como controle) observamos o aumento de células marcadas para os ligantes Sonic e Dessert Hedgehog e células positivas para c-Kit nas amostras de SMD. Em seguida, analisamos a expressão gênica dos membros da via Hedgehog em células totais de medula óssea de pacientes SMD e doadores normais. Não houve diferença na expressão de Patched (PTCH) em SMD em comparação com doadores saudáveis, porém quando as amostras são classificadas de acordo com a WHO 2008, observamos aumento significativo de PTCH nos pacientes com <5% de blastos na medula óssea (AR...

Linking immunity and hematopoiesis by bone marrow T cell activity

Monteiro,J.P.; Bonomo,A.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2005 EN
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Two different levels of control for bone marrow hematopoiesis are believed to exist. On the one hand, normal blood cell distribution is believed to be maintained in healthy subjects by an "innate" hematopoietic activity, i.e., a basal intrinsic bone marrow activity. On the other hand, an "adaptive" hematopoietic state develops in response to stress-induced stimulation. This adaptive hematopoiesis targets specific lineage amplification depending on the nature of the stimuli. Unexpectedly, recent data have shown that what we call "normal hematopoiesis" is a stress-induced state maintained by activated bone marrow CD4+ T cells. This T cell population includes a large number of recently stimulated cells in normal mice whose priming requires the presence of the cognate antigens. In the absence of CD4+ T cells or their cognate antigens, hematopoiesis is maintained at low levels. In this review, we summarize current knowledge on T cell biology, which could explain how CD4+ T cells can help hematopoiesis, how they are primed in mice that were not intentionally immunized, and what maintains them activated in the bone marrow.

Loss of Runx1 perturbs adult hematopoiesis and is associated with a myeloproliferative phenotype

Growney, Joseph D.; Shigematsu, Hirokazu; Li, Zhe; Lee, Benjamin H.; Adelsperger, Jennifer; Rowan, Rebecca; Curley, David P.; Kutok, Jeffery L.; Akashi, Koichi; Williams, Ifor R.; Speck, Nancy A.; Gilliland, D. Gary
Fonte: The American Society of Hematology Publicador: The American Society of Hematology
Tipo: Artigo de Revista Científica
Publicado em 15/07/2005 EN
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Homozygous loss of function of Runx1 (Runt-related transcription factor 1 gene) during murine development results in an embryonic lethal phenotype characterized by a complete lack of definitive hematopoiesis. In light of recent reports of disparate requirements for hematopoietic transcription factors during development as opposed to adult hematopoiesis, we used a conditional gene-targeting strategy to effect the loss of Runx1 function in adult mice. In contrast with the critical role of Runx1 during development, Runx1 was not essential for hematopoiesis in the adult hematopoietic compartment, though a number of significant hematopoietic abnormalities were observed. Runx1 excision had lineage-specific effects on B- and T-cell maturation and pronounced inhibition of common lymphocyte progenitor production. Runx1 excision also resulted in inefficient platelet production. Of note, Runx1-deficient mice developed a mild myeloproliferative phenotype characterized by an increase in peripheral blood neutrophils, an increase in myeloid progenitor populations, and extramedullary hematopoiesis composed of maturing myeloid and erythroid elements. These findings indicate that Runx1 deficiency has markedly different consequences during development compared with adult hematopoiesis...

CCL18/PARC stimulates hematopoiesis in long-term bone marrow cultures indirectly through its effect on monocytes

Wimmer, Antonia; Khaldoyanidi, Sophia K.; Judex, Martin; Serobyan, Naira; DiScipio, Richard G.; Schraufstatter, Ingrid U.
Fonte: The American Society of Hematology Publicador: The American Society of Hematology
Tipo: Artigo de Revista Científica
Publicado em 01/12/2006 EN
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Chemokines play a role in regulating hematopoietic stem cell function, including migration, proliferation, and retention. We investigated the involvement of CCL18 in the regulation of bone marrow hematopoiesis. Treatment of human long-term bone marrow cultures (LTBMCs) with CCL18 resulted in significant stimulation of hematopoiesis, as measured by the total number of hematopoietic cells and their committed progenitors produced in culture. Monocytes/macrophages, whose survival was almost doubled in the presence of CCL18 compared with controls, were the primary cells mediating this effect. Conditioned media from CCL18-treated mature monocytes fostered colony-promoting activity that increased the number of colonies formed by hematopoietic progenitor cells. Gene expression profiling of CCL18-stimulated monocytes demonstrated more than 200 differentially expressed genes, including those regulating apoptosis (caspase-8) and proliferation (IL-6, IL-15, stem cell factor [SCF]). Up-regulation of these cytokines was confirmed on the protein expression level. The contribution of SCF and IL-6 in CCL18-mediated stimulatory activity for hematopoiesis was confirmed by SCF- and IL-6–blocking antibodies that significantly inhibited the colony-promoting activity of CCL18-stimulated conditioned medium. In addition to the effect on monocytes...

Expression of Pitx2 in stromal cells is required for normal hematopoiesis

Kieusseian, Aurélie; Chagraoui, Jalila; Kerdudo, Cécile; Mangeot, Philippe-Emmanuel; Gage, Philip J.; Navarro, Nicole; Izac, Brigitte; Uzan, Georges; Forget, Bernard G.; Dubart-Kupperschmitt, Anne
Fonte: The American Society of Hematology Publicador: The American Society of Hematology
Tipo: Artigo de Revista Científica
Publicado em 15/01/2006 EN
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Although the expression of Pitx2, a bicoid family homeodomain transcription factor, is highly regulated during hematopoiesis, its function during this process was not documented; we thus studied hematopoiesis in Pitx2-null mice. We found that Pitx2–/– embryos display hypoplastic livers with reduced numbers of hematopoietic cells, but these cells had normal hematopoietic potential, as evidenced by colony-forming assays, immature progenitor cell assays, and long-term repopulation assays. Because the microenvironment is also crucial to the development of normal hematopoiesis, we established Pitx2–/– and Pitx2+/+ stromas from fetal liver and studied their hematopoietic supportive capacity. We showed that the frequency of cobblestone area-forming cells was 4-fold decreased when using Pitx2–/– stromal cells compared with Pitx2+/+ stromal cells, whatever the Pitx2 genotype of hematopoietic cells tested in this assay. This defect was rescued by expression of Pitx2 into Pitx2–/– fetal liver stromal cells, demonstrating a major and direct role of Pitx2 in the hematopoietic supportive capacity of fetal liver stroma. Finally, we showed a reduced capacity of MS5 stromal cells expressing Pitx2 RNAi to support human hematopoiesis. Altogether these data showed that Pitx2 has major functions in the hematopoietic supportive capacity of fetal liver and adult bone marrow stromal cells.

Hematopoiesis and stem cell renewal in long-term bone marrow cultures containing catalase

Gupta, Rashmi; Karpatkin, Simon; Basch, Ross S.
Fonte: © 2006 by The American Society of Hematology Publicador: © 2006 by The American Society of Hematology
Tipo: Artigo de Revista Científica
Publicado em 01/03/2006 EN
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Culturing mouse bone marrow in the presence of catalase dramatically alters hematopoiesis. Granulocyte output is initially increased 4- to 5-fold. This increase is transient and granulocyte production declines as immature (Sca-1+/LIN-) cells accumulate. One third of these immature cells have a phenotype (Sca-1+/c-Kit+) characteristic of hematopoietic stem cells. At 2 to 3 weeks there are greater than 200-fold more Sca-1+/c-Kit+/LIN- cells in treated cultures than in controls. This population contains functional stem cells with both short-term and long-term bone marrow repopulating activity. In addition to myeloid progenitors, this Sca-1+/LIN- population contains a large number of cells that express CD31 and CD34 and have an active Tie-2 promoter, indicating that they are in the endothelial lineage. After 3 to 4 weeks hematopoiesis in treated cultures wanes but if catalase is removed, hematopoiesis resumes. After 7 to 10 days the cultures are indistinguishable from untreated controls. Thus, protected from H2O2, hematopoietic progenitors multiply and become quiescent. This sequence resembles in vivo development in normal marrow. These results make it clear that peroxide-sensitive regulatory mechanisms play an important role in controlling hematopoiesis ex vivo and presumably in vivo as well. They also indicate that manipulation of the peroxide levels can be used to enhance the growth of hematopoietic stem cells in culture.

Abnormal hematopoiesis in Gab2 mutant mice

Zhang, Yi; Diaz-Flores, Ernesto; Li, Geqiang; Wang, Zhengqi; Kang, Zizhen; Haviernikova, Eleonora; Rowe, Sara; Qu, Cheng-Kui; Tse, William; Shannon, Kevin M.; Bunting, Kevin D.
Fonte: American Society of Hematology Publicador: American Society of Hematology
Tipo: Artigo de Revista Científica
Publicado em 01/07/2007 EN
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Gab2 is an important adapter molecule for cytokine signaling. Despite its major role in signaling by receptors associated with hematopoiesis, the role of Gab2 in hematopoiesis has not been addressed. We report that despite normal numbers of peripheral blood cells, bone marrow cells, and c-Kit+Lin−Sca-1+ (KLS) cells, Gab2-deficient hematopoietic cells are deficient in cytokine responsiveness. Significant reductions in the number of colony-forming units in culture (CFU-C) in the presence of limiting cytokine concentrations were observed, and these defects could be completely corrected by retroviral complementation. In earlier hematopoiesis, Gab2-deficient KLS cells isolated in vitro responded poorly to hematopoietic growth factors, resulting in an up to 11-fold reduction in response to a cocktail of stem cell factor, flt3 ligand, and thrombopoietin. Gab2-deficient c-Kit+Lin− cells also demonstrate impaired activation of extracellular signal-regulated kinase (ERK) and S6 in response to IL-3, which supports defects in activating the phosphatidylinositol-3 kinase (PI-3K) and mitogen-associated protein kinase (MAPK) signaling cascades. Associated with the early defects in cytokine response, competitive transplantation of Gab2−/− bone marrow cells resulted in defective long-term multilineage repopulation. Therefore...

Smad1 and Smad5 differentially regulate embryonic hematopoiesis

McReynolds, Lisa J.; Gupta, Sunny; Figueroa, Maria E.; Mullins, Mary C.; Evans, Todd
Fonte: American Society of Hematology Publicador: American Society of Hematology
Tipo: Artigo de Revista Científica
Publicado em 01/12/2007 EN
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The bone morphogenetic protein (BMP) signaling pathway regulates multiple steps of hematopoiesis, mediated through receptor-regulated Smads, including Smad1 and Smad5. Here, we use loss-of-function approaches in zebrafish to compare the roles of Smad1 and Smad5 during embryonic hematopoiesis. We show that knockdown of Smad1 or Smad5 generates distinct and even opposite hematopoietic phenotypes. Embryos depleted for Smad1 have an increased number of primitive erythrocytes, but fail to produce mature embryonic macrophages. In contrast, Smad5-depleted embryos are defective in primitive erythropoiesis, yet have normal numbers of macrophages. Loss of either Smad1 or Smad5 causes a failure in the generation of definitive hematopoietic progenitors. To investigate the mechanism behind these phenotypes, we used rescue experiments and found that Smad5 is unable to rescue the Smad1 loss-of-function phenotype, indicating that the 2 highly related proteins have inherently distinct activities. Microarray experiments revealed that the 2 proteins redundantly regulate the key initiators of the hemato-vascular program, including scl, lmo2, and gfi1. However, each also regulates a remarkably distinct genetic program, with Smad5 uniquely regulating the BMP signaling pathway itself. Our results suggest that specificity of BMP signaling output...

Hematopoiesis is not clonal in healthy elderly women

Swierczek, Sabina I.; Agarwal, Neeraj; Nussenzveig, Roberto H.; Rothstein, Gerald; Wilson, Andrew; Artz, Andrew; Prchal, Josef T.
Fonte: American Society of Hematology Publicador: American Society of Hematology
Tipo: Artigo de Revista Científica
Publicado em 15/10/2008 EN
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Clonality assays, based on X-chromosome inactivation, discriminate active from inactive alleles. Skewing of X-chromosome allelic usage, based on preferential methylation of one of the HUMARA alleles, was reported as evidence of clonal hematopoiesis in approximately 30% of elderly women. Using a quantitative, transcriptionally based clonality assay, we reported X-chromosome–transcribed allelic ratio in blood cells of healthy women consistent with random X-inactivation of 8 embryonic hematopoietic stem cells. Furthermore, we did not detect clonal hematopoiesis in more than 200 healthy nonelderly women. In view of the susceptibility of aging hematopoietic stem cells to epigenetic dysregulation, we reinvestigated the issue of clonality in elderly women. Forty healthy women (ages 65-92 years; mean, 81.3 years) were tested by a novel, quantitative polymerase chain reaction (qPCR) transcriptional clonality assay. We did not detect clonal hematopoiesis in any of the tested subjects. We also tested DNA from the same granulocyte samples using the methylation-based HUMARA assay, and confirmed previous reports of approximately 30% extensively skewed or monoallelic methylation, in agreement with likely age-related deregulated methylation of the HUMARA gene locus. We conclude that the transcriptionally based X-chromosome clonality assays are suitable for evaluation of clonal hematopoiesis in elderly women.

Expression of Scl in mesoderm rescues hematopoiesis in the absence of Oct-4

Kong, Kimi Y.; Williamson, Elizabeth A.; Rogers, Jason H.; Tran, Tam; Hromas, Robert; Dahl, Richard
Fonte: American Society of Hematology Publicador: American Society of Hematology
Tipo: Artigo de Revista Científica
Publicado em 02/07/2009 EN
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In embryonic stem cells, Oct-4 concentration is critical in determining the development of endoderm, mesoderm, and trophectoderm. Although Oct-4 expression is essential for mesoderm development, it is unclear whether it has a role in the development of specific mesodermal tissues. In this study, we have examined the importance of Oct-4 in the generation of hematopoietic cells using an inducible Oct-4 ESC line. We demonstrate that Oct-4 has a role in supporting hematopoiesis after specifying brachyury-positive mesoderm. When we suppressed Oct-4 expression before or after mesoderm specification, no hematopoietic cells are detected. However, hematopoiesis can be rescued in the absence of Oct-4 after mesoderm specification if the essential hematopoietic transcription factor stem cell leukemia is expressed. Our results suggest that, for hematopoiesis to occur, Oct-4 is required for the initial specification of mesoderm and subsequently is required for the development of hematopoietic cells from uncommitted mesoderm.

Differential requirement for Gata1 DNA binding and transactivation between primitive and definitive stages of hematopoiesis in zebrafish

Belele, Christiane L.; English, Milton A.; Chahal, Jagman; Burnetti, Anthony; Finckbeiner, Steven M.; Gibney, Gretchen; Kirby, Martha; Sood, Raman; Liu, P. Paul
Fonte: American Society of Hematology Publicador: American Society of Hematology
Tipo: Artigo de Revista Científica
Publicado em 10/12/2009 EN
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The transcription factor Gata1 is required for the development of erythrocytes and megakaryocytes. Previous studies with a complementation rescue approach showed that the zinc finger domains are required for both primitive and definitive hematopoiesis. Here we report a novel zebrafish gata1 mutant with an N-ethyl-N-nitrosourea–induced point mutation in the C-finger (gata1T301K). The Gata1 protein with this mutation bound to its DNA target sequence with reduced affinity and transactivated inefficiently in a reporter assay. gata1T301K/T301K fish had a decreased number of erythrocytes during primitive hematopoiesis but normal adult hematopoiesis. We crossed the gata1T301K/T301K fish with those carrying the R339X mutation, also known as vlad tepes (vlt), which abolishes DNA binding and transactivation activities. As we reported previously, gata1vlt/vlt embryos were “bloodless” and died approximately 11 to 15 days after fertilization. Interestingly, the gata1T301K/vlt fish had nearly a complete block of primitive hematopoiesis, but they resumed hematopoiesis between 7 and 14 days after fertilization and grew to phenotypically normal fish with normal adult hematopoiesis. Our findings suggest that the impact of Gata1 on hematopoiesis correlates with its DNA-binding ability and that primitive hematopoiesis is more sensitive to reduction in Gata1 function than definitive hematopoiesis.

Development of multilineage adult hematopoiesis in the zebrafish with a runx1 truncation mutation

Sood, Raman; English, Milton A.; Belele, Christiane L.; Jin, Hao; Bishop, Kevin; Haskins, Rebecca; McKinney, Mary Cathleen; Chahal, Jagman; Weinstein, Brant M.; Wen, Zilong; Liu, P. Paul
Fonte: American Society of Hematology Publicador: American Society of Hematology
Tipo: Artigo de Revista Científica
Publicado em 08/04/2010 EN
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Runx1 is required for the emergence of hematopoietic stem cells (HSCs) from hemogenic endothelium during embryogenesis. However, its role in the generation and maintenance of HSCs during adult hematopoiesis remains uncertain. Here, we present analysis of a zebrafish mutant line carrying a truncation mutation, W84X, in runx1. The runx1W84X/W84X embryos showed blockage in the initiation of definitive hematopoiesis, but some embryos were able to recover from a larval “bloodless” phase and develop to fertile adults with multilineage hematopoiesis. Using cd41–green fluorescent protein transgenic zebrafish and lineage tracing, we demonstrated that the runx1W84X/W84X embryos developed cd41+ HSCs in the aorta-gonad-mesonephros region, which later migrated to the kidney, the site of adult hematopoiesis. Overall, our data suggest that in zebrafish adult HSCs can be formed without an intact runx1.

RapGEF2 is essential for embryonic hematopoiesis but dispensable for adult hematopoiesis

Satyanarayana, Ande; Gudmundsson, Kristbjorn Orri; Chen, Xiu; Coppola, Vincenzo; Tessarollo, Lino; Keller, Jonathan R.; Hou, Steven X.
Fonte: American Society of Hematology Publicador: American Society of Hematology
Tipo: Artigo de Revista Científica
Publicado em 21/10/2010 EN
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RapGEF2 is one of many guanine nucleotide exchange factors (GEFs) that specifically activate Rap1. Here, we generated RapGEF2 conditional knockout mice and studied its role in embryogenesis and fetal as well as adult hematopoietic stem cell (HSC) regulation. RapGEF2 deficiency led to embryonic lethality at ∼ E11.5 due to severe yolk sac vascular defects. However, a similar number of Flk1+ cells were present in RapGEF2+/+ and RapGEF2−/− yolk sacs indicating that the bipotential early progenitors were in fact generated in the absence of RapGEF2. Further analysis of yolk sacs and embryos revealed a significant reduction of CD41 expressing cells in RapGEF2−/− genotype, suggesting a defect in the maintenance of definitive hematopoiesis. RapGEF2−/− cells displayed defects in proliferation and migration, and the in vitro colony formation ability of hematopoietic progenitors was also impaired. At the molecular level, Rap1 activation was impaired in RapGEF2−/− cells that in turn lead to defective B-raf/ERK signaling. Scl/Gata transcription factor expression was significantly reduced, indicating that the defects observed in RapGEF2−/− cells could be mediated through Scl/Gata deregulation. Inducible deletion of RapGEF2 during late embryogenesis in RapGEF2cko/ckoERcre mice leads to defective fetal liver erythropoiesis. Conversely...

Cannabinoid receptor 2 and its agonists mediate hematopoiesis and hematopoietic stem and progenitor cell mobilization

Jiang, Shuxian; Alberich-Jorda, Meritxell; Zagozdzon, Radoslaw; Parmar, Kalindi; Fu, Yigong; Mauch, Peter; Banu, Naheed; Makriyannis, Alexandros; Tenen, Daniel G.; Avraham, Shalom; Groopman, Jerome E.; Avraham, Hava Karsenty
Fonte: American Society of Hematology Publicador: American Society of Hematology
Tipo: Artigo de Revista Científica
Publicado em 20/01/2011 EN
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Endocannabinoids are arachidonic acid derivatives and part of a novel bioactive lipid signaling system, along with their G-coupled cannabinoid receptors (CB1 and CB2) and the enzymes involved in their biosynthesis and degradation. However, their roles in hematopoiesis and hematopoietic stem and progenitor cell (HSPC) functions are not well characterized. Here, we show that bone marrow stromal cells express endocannabinoids (anandamide and 2-arachidonylglycerol), whereas CB2 receptors are expressed in human and murine HSPCs. On ligand stimulation with CB2 agonists, CB2 receptors induced chemotaxis, migration, and enhanced colony formation of bone marrow cells, which were mediated via ERK, PI3-kinase, and Gαi-Rac1 pathways. In vivo, the CB2 agonist AM1241 induced mobilization of murine HSPCs with short- and long-term repopulating abilities. In addition, granulocyte colony-stimulating factor -induced mobilization of HSPCs was significantly decreased by specific CB2 antagonists and was impaired in Cnr2−/− cannabinoid type 2 receptor knockout mice. Taken together, these results demonstrate that the endocannabinoid system is involved in hematopoiesis and that CB2/CB2 agonist axis mediates repopulation of hematopoiesis and mobilization of HSPCs. Thus...

Requirement for Dot1l in murine postnatal hematopoiesis and leukemogenesis by MLL translocation

Jo, Stephanie Y.; Granowicz, Eric M.; Maillard, Ivan; Thomas, Dafydd; Hess, Jay L.
Fonte: American Society of Hematology Publicador: American Society of Hematology
Tipo: Artigo de Revista Científica
Publicado em 05/05/2011 EN
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Disruptor of telomeric silencing 1-like (Dot1l) is a histone 3 lysine 79 methyltransferase. Studies of constitutive Dot1l knockout mice show that Dot1l is essential for embryonic development and prenatal hematopoiesis. DOT1L also interacts with translocation partners of Mixed Lineage Leukemia (MLL) gene, which is commonly translocated in human leukemia. However, the requirement of Dot1l in postnatal hematopoiesis and leukemogenesis of MLL translocation proteins has not been conclusively shown. With a conditional Dot1l knockout mouse model, we examined the consequences of Dot1l loss in postnatal hematopoiesis and MLL translocation leukemia. Deletion of Dot1l led to pancytopenia and failure of hematopoietic homeostasis, and Dot1l-deficient cells minimally reconstituted recipient bone marrow in competitive transplantation experiments. In addition, MLL-AF9 cells required Dot1l for oncogenic transformation, whereas cells with other leukemic oncogenes, such as Hoxa9/Meis1 and E2A-HLF, did not. These findings illustrate a crucial role of Dot1l in normal hematopoiesis and leukemogenesis of specific oncogenes.

TIP110/p110nrb/SART3/p110 regulation of hematopoiesis through CMYC

Liu, Ying; Timani, Khalid; Mantel, Charlie; Fan, Yan; Hangoc, Giao; Cooper, Scott; He, Johnny J.; Broxmeyer, Hal E.
Fonte: American Society of Hematology Publicador: American Society of Hematology
Tipo: Artigo de Revista Científica
Publicado em 26/05/2011 EN
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Intracellular factors are involved in and essential for hematopoiesis. HIV-1 Tat-interacting protein of 110 kDa (TIP110; p110nrb/SART3/p110) is an RNA-binding nuclear protein implicated in the regulation of HIV-1 gene and host gene transcription, pre-mRNA splicing, and cancer immunology. In the present study, we demonstrate a role for TIP110 in the regulation of hematopoiesis. TIP110 was expressed in human CD34+ cells and decreased with differentiation of CD34+ cells. TIP110 mRNA was also expressed in phenotyped mouse marrow hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs). Using TIP110 transgenic (TIP110TG) and haploinsufficient (TIP110+/−) mice, we found that increased TIP110 expression enhanced HPC numbers, survival, and cell cycling, whereas decreased TIP110 expression had the opposite effects. Moreover, TIP110+/− bone marrow HPCs responded more effectively, and TIP110TG HPCs less effectively, than those of wild-type control mice to recovery from the cell-cycle–active drug 5-fluorouracil (5-FU). Unexplained sex differences were noted in HSC competitive repopulating ability, but not HPC numbers, in TIP110TG mice. Intracellularly, TIP110 regulated CMYC and GATA2 expression at the transcriptional level...

Quantitative trait mapping reveals a regulatory axis involving peroxisome proliferator-activated receptors, PRDM16, transforming growth factor-β2 and FLT3 in hematopoiesis

Avagyan, Serine; Aguilo, Francesca; Kamezaki, Kenjiro; Snoeck, Hans-Willem
Fonte: American Society of Hematology Publicador: American Society of Hematology
Tipo: Artigo de Revista Científica
Publicado em 01/12/2011 EN
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Hematopoiesis is the process whereby BM HSCs renew to maintain their number or to differentiate into committed progenitors to generate all blood cells. One approach to gain mechanistic insight into this complex process is the investigation of quantitative genetic variation in hematopoietic function among inbred mouse strains. We previously showed that TGF-β2 is a genetically determined positive regulator of hematopoiesis. In the presence of unknown nonprotein serum factors TGF-β2, but not TGF-β1 or -β3, enhances progenitor proliferation in vitro, an effect that is subject to mouse strain-dependent variation mapping to a locus on chr.4, Tb2r1. TGF-β2–deficient mice show hematopoietic defects, demonstrating the physiologic role of this cytokine. Here, we show that TGF-β2 specifically and predominantly cell autonomously enhances signaling by FLT3 in vitro and in vivo. A coding polymorphism in Prdm16 (PR-domain-containing 16) underlies Tb2r1 and differentially regulates transcriptional activity of peroxisome proliferator-activated receptor-γ (PPARγ), identifying lipid PPAR ligands as the serum factors required for regulation of FLT3 signaling by TGF-β2. We furthermore show that PPARγ agonists play a FLT3-dependent role in stress responses of progenitor cells. These observations identify a novel regulatory axis that includes PPARs...

Teleost Growth Factor Independence (Gfi) Genes Differentially Regulate Successive Waves of Hematopoiesis

Cooney, Jeffrey D.; Hildick-Smith, Gordon J.; Shafizadeh, Ebrahim; McBride, Paul F.; Carroll, Kelli Jane; Anderson, Heidi; Shaw, George C.; Tamplin, Owen J.; Branco, Diana S.; Dalton, Arthur J.; Shah, Dhvanit I; Wong, Clara; Gallagher, Patrick G.; Zon, Le
Fonte: Elsevier BV Publicador: Elsevier BV
Tipo: Artigo de Revista Científica
EN_US
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Growth Factor Independence (Gfi) transcription factors play essential roles in hematopoiesis, differentially activating and repressing transcriptional programs required for hematopoietic stem/progenitor cell (HSPC) development and lineage specification. In mammals, Gfi1a regulates hematopoietic stem cells (HSC), myeloid and lymphoid populations, while its paralog, Gfi1b, regulates HSC, megakaryocyte and erythroid development. In zebrafish, gfi1aa is essential for primitive hematopoiesis; however, little is known about the role of gfi1aa in definitive hematopoiesis or about additional gfi factors in zebrafish. Here, we report the isolation and characterization of an additional hematopoietic gfi factor, gfi1b. We show that gfi1aa and gfi1b are expressed in the primitive and definitive sites of hematopoiesis in zebrafish. Our functional analyses demonstrate that gfi1aa and gfi1b have distinct roles in regulating primitive and definitive hematopoietic progenitors, respectively. Loss of gfi1aa silences markers of early primitive progenitors, scl and gata1. Conversely, loss of gfi1b silences runx-1, c-myb, ikaros and cd41, indicating that gfi1b is required for definitive hematopoiesis. We determine the epistatic relationships between the gfi factors and key hematopoietic transcription factors...

Is hematopoiesis under the influence of neural and neuroendocrine mechanisms?

Maestroni, G.J.M.
Fonte: Murcia : F. Hernández Publicador: Murcia : F. Hernández
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
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It is well recognized that the immune response is under the influence of a variety of neural or neuroendocrine mechanisms. Much less studied is the possible influence of these mechanisms on hematopoiesis. Here I review the existing evidence about a neural andlor neuroendocrine regulation of hematopoiesis. The physiology of the blood forming system seems to be controlled at three levels, i.e. at the cellular level by the bone marrow stroma, at the humoral level by hematopoietic cytokines and finally by catecholamines and neuroendocrine factors. Bone marrow catecholarnines originate from sympathetic nerve fibers and from hematopoietic cells directly. Catecholamines of neural origin show a circadian rhythmicity. Adrenoceptors present on bone marrow cells include the a l - subtype which seems to mediate the catecholaminergic control of hematopoiesis. Neuroendocrine factors including substance P, neurokinin-A and the pineal hormone melatonin might also influence hematopoiesis by affecting hernatopoietic cytokines. In particular, melatonin seems to affect hematopoiesis via the induction in bone marrow T-helper cells of two novel opioid cytokines. A complete understanding of the neural and neuroendocrine regulation of hematopoiesis might provide new conceptual and therapeutic perspectives in a variety of hematopoietic and immune diseases.

Niches for extramedullary hematopoiesis in the spleen

O'Neill, Helen C.
Fonte: AVES Publishing; Cellular Therapy and Regenerative Medicine Society Publicador: AVES Publishing; Cellular Therapy and Regenerative Medicine Society
Tipo: Artigo de Revista Científica Formato: 5 pages
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The spleen is a major site for extramedullary hematopoiesis and adult mouse and human spleens retain low numbers of hematopoietic stem cells (HSC). Hematopoiesis is however dependent on stromal microenvironments that provide appropriate molecular signals. Recent evidence now suggests that a distinct stromal cell type exists in the spleen which can function as a niche for hematopoiesis. This review considers the role of the spleen in hematopoiesis, and the possibility that the spleen can be utilized or amplified as a site for hematopoiesis during HSC transplantation. If stromal cells can be isolated and used to expand HSC 'in vitro', or provided as an ectopic niche 'in vivo' for the same purpose, then the potential exists to enhance hematopoiesis in patients undergoing myeloablative treatment, HSC transplantation or involution of lymphoid tissue with ageing; NHMRC (National Health and Medical Research Council of Australia)