Menin Regulates the Function of Lymphoid Progenitors and Hematopoietic Stem Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1257-1257
Author(s):  
Ivan Maillard ◽  
Ya-Xiong Chen ◽  
Anthony T. Tubbs ◽  
Olga Shestova ◽  
Warren S. Pear ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Malignant Transformation ◽  
Transcriptional Activation ◽  
Hox Genes ◽  
Type I ◽  
Hematopoietic Stem ◽  
Hox Gene ◽  
Men1 Gene ◽  
Mll Gene

Abstract Menin is the product of the Men1 gene, a tumor suppressor gene that is mutated in patients with multiple endocrine neoplasia type I (MEN1). In addition to its effects in endocrine tissues, Menin interacts with the Mixed Lineage Leukemia (Mll) gene product as part of a multiprotein complex with H3K4 methyltransferase activity. Menin is required to mediate malignant transformation induced by Mll gene rearrangements, an activity associated with transcriptional activation of Homeobox (Hox) gene expression, presumably through epigenetic regulation. To explore the normal function of Menin in hematopoiesis, we studied bone marrow (BM) progenitors after inactivation of the Men1 gene in adult mice. Loss of Menin led to a modest reduction in peripheral blood neutrophil, lymphocyte and platelet counts. In the absence of hematopoietic stress, numbers of multilineage and myeloerythroid BM progenitors were preserved, but pro-B cells and downstream B lineage progenitor subsets were significantly decreased. Competitive BM transplantation assays revealed a marked defect in the function of Menin-deficient hematopoietic stem cells (HSCs), including long-term HSCs. Furthermore, Menin-deficient mice had impaired hematopoietic recovery after chemoablation with 5-fluorouracil. However, expression of Hox genes in BM HSCs was not impaired in the absence of Menin. These observations reveal an essential role of Menin in the homeostasis of hematopoietic stem and progenitor cells. Furthermore, they suggest that Menin may regulate normal hematopoiesis through mechanisms that are distinct from its role in Hox gene-dependent malignant transformation.

BMP4 Favors Hematopoietic Differentiation from Murine Embryonic Stem Cells and Acts by Activation of the cdx-hox Pathway.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3613-3613
Author(s):  
Claudia Lengerke ◽  
Yuan Wang ◽  
Frank Yates ◽  
Leila Maouche-Chretien ◽  
George Q. Daley
Keyword(s):  
Gene Expression ◽  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Hox Genes ◽  
Embryonic Stem ◽  
Embryoid Bodies ◽  
Hematopoietic Stem ◽  
Hox Gene ◽  
Murine Embryonic Stem Cells

Abstract Cdx4 and cdx1, members of the caudal family of homeodomain-containing transcriptional regulators, are important for specifying the hematopoietic fate of mesoderm in the zebrafish. We have shown that the cdx4 gene plays a role in enhancing hematopoietic fate during in vitro differentiation of murine ESCs (Davidson et al., Nature 2003). Cdx4 induces hox genes, and genetic modification of mESCs with a combination of cdx4 and hoxb4 promotes long-term engraftment of ESC-derived HSCs in lethally irradiated primary and secondary mice (Wang et al, submitted). While cdx1 is known to be a direct target of signaling by the embryonic morphogens fgf, wnt3a, and retinoids, morphogens acting upstream of cdx4 have not yet been defined. Our goal is to determine optimal morphogen conditions for hematopoietic commitment from murine embryonic stem cells by evaluating activation of the cdx-hox pathway. We have developed quantitative RT-PCR assays for the cdx genes (cdx4, cdx1 and cdx2) and multiple hox genes as well as markers specific to hematopoietic stem cells and lineages. We have used these assays, together with a reporter line engineered to express GFP from the brachury locus (Fehling et al., Development 2003), to characterize the conditions for mesodermal induction and hematopoietic fate specification following addition of morphogens to differentiating cultures of ES cells under serum-free conditions. Among all morphogens tested (BMP4, activin, nodal, wnt3a, wnt5a, sonic hedgehog, indian hedgehog, retinoic acid), only BMP4 has been found to strongly induce CDX4 gene expression within the developing embryoid bodies, while addition of the BMP4 inhibitor noggin to serum suppressed CDX4 expression. Addition of BMP4 significantly increases the number of emerging CD41+ and CD45+ cells, the precursors of definitive hematopoietic stem cells. We are currently analyzing the functional changes following BMP4 exposure, and correlating hematopoietic maturation with changes in the Hox gene expression pattern. Analysis of the cdx-hox gene pathway provides a means of otpimizing induction of hematopoietic fate by application of embryonic morphogens.

Ifnα Attenuates the Disease Phenotype and Extends Survival in Mouse Models of MPN

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 53-53
Author(s):  
Harini Nivarthi ◽  
Andrea Majoros ◽  
Eva Hug ◽  
Ruochen Jia ◽  
Sarada Achyutuni ◽  
...  
Keyword(s):  
Stem Cells ◽  
Bone Marrow ◽  
Hematopoietic Stem Cells ◽  
Mouse Models ◽  
Jak2 V617f ◽  
Type I ◽  
Type I Ifn ◽  
Hematopoietic Stem ◽  
Exon 9 ◽  
Ifn Treatment

The curative potential of Type I interferons for patients suffering from Myeloproliferative Neoplasms (MPNs) has been reported and these are the only class of drugs that can lead to reduction of the mutant allelic burden in patients. However, modelling IFN treatment in mice has been challenging. Here, we report the use of murine pegylated IFNα (murine ropeginterferon-a, mRopeg) developed by PharmaEssentia (Taipei, Taiwan) to model IFN treatment in transgenic MPN mouse models. We started treating JAK2V617Ff/+;vavCre and control vavCre mice (n=6-8) with PBS or mRopeg (600 ng/mouse/week), by subcutaneous injections from the time they were 4 weeks old. The mice were bled every 2 weeks from the facial vein and the blood parameters were monitored. We observed significant normalization of platelet and WBC counts in Jak2-V617F fl/+ vavCre mice to wild type levels. No effect on hematocrit and hemoglobin level was observed in the Jak2-V617F fl/+ vavCre mice. VavCre control animals showed no sign of negative effect such as cytopenia during the entire treatment course. We observed a highly significant prolongation of the survival of mRopeg treated JAK2V617Ff/+;vavCre mice over a duration of 80 days of treatment. While all the PBS treated JAK2V617Ff/+;vavCre mice died within 60 days, all the mRopeg treated mice were still alive till the end of the treatment duration. We also generated a novel transgenic mouse model that conditionally expresses hybrid mutant CALR protein (murine exons 1-8 and human CALR del52 exon9) from the endogenous murine Calr locus. We bred them into vavCre background (in both heterozyhous and homozygous states) to induce expression of CALR-del52 in hematopoietic cells. Upon Cre recombinase expression, the endogenous murine exon 9 is replaced by the human del52 exon 9 and the expression of the humanized Calr-del52 oncoprotein is detectable by Western blot analysis using mutant CALR specific antibodies. Calr-del52 animals develop an essential thrombocythemia (ET) like phenotype when expressed in a heterozygous state with elevated number of hematopoietic stem cells and megakaryocytes in the bone marrow. In the homozygous state, the thrombocythemia is more severe with splenomegaly and older animals show anemia with increased WBC. Bone marrow histology shows megakaryocytic hyperplasia with no sign of fibrosis up to age of one year. We treated a cohort of animals with 600 ng mRopeg/PBS once a week for 4 weeks. Peripheral blood counts were determined at baseline and at regular intervals during treatment. At the end of treatment, mice were sacrificed, and splenic and bone marrow cells were immunophenotyped and quantified by FACS. We observed correction of thrombocythemia in the homozygous Calr-del52 mice but no unspecific decrease of platelet count in the vavCre mRopeg treated animals. We observed significant specific reduction of the long-term hematopoietic stem cells (LT-HSCs/fraction A) in homozygous CALR-del52 mice. In conclusion, Type I IFN treatment significantly reduces platelet counts to normal levels in both JAK2 and CALR mutant driven MPN mouse models. The prolongation of survival of JAK2V617F transgenic mice upon Type I IFN treatment is particularly remarkable; as no survival data is reported until now in any clinical trials or other animal models. Further experiments are required to understand the mechanism of action of this phenomenon. Disclosures No relevant conflicts of interest to declare.

scholarly journals Evidence for malignant transformation in acute myeloid leukemia at the level of early hematopoietic stem cells by cytogenetic analysis of CD34+ subpopulations

Blood ◽  
1995 ◽  
Vol 86 (8) ◽  
pp. 2906-2912 ◽  
Author(s):  
D Haase ◽  
M Feuring-Buske ◽  
S Konemann ◽  
C Fonatsch ◽  
C Troff ◽  
...  
Keyword(s):  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Hematopoietic Stem Cells ◽  
Malignant Transformation ◽  
Cell Sorting ◽  
Myeloid Leukemia ◽  
De Novo ◽  
Leukemic Cells ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Acute myeloid leukemia (AML) is a heterogenous disease according to morphology, immunophenotype, and genetics. The retained capacity of differentiation is the basis for the phenotypic classification of the bulk population of leukemic blasts and the identification of distinct subpopulations. Within the hierarchy of hematopoietic development and differentiation it is still unknown at which stage the malignant transformation occurs. It was our aim to analyze the potential involvement of cells with the immunophenotype of pluripotent stem cells in the leukemic process by the use of cytogenetic and cell sorting techniques. Cytogenetic analyses of bone marrow aspirates were performed in 13 patients with AML (11 de novo and 2 secondary) and showed karyotype abnormalities in 10 cases [2q+, +4, 6p, t(6:9), 7, +8 in 1 patient each and inv(16) in 4 patients each]. Aliquots of the samples were fractionated by fluorescence-activated cell sorting of CD34+ cells. Two subpopulations, CD34+/CD38-(early hematopoietic stem cells) and CD34+/CD38+ (more mature progenitor cells), were screened for karyotype aberations as a marker for leukemic cells. Clonal abnormalities and evaluable metaphases were found in 8 highly purified CD34+/CD38-populations and in 9 of the CD34+/CD38-specimens, respectively. In the majority of cases (CD34+/CD38-, 6 of 8 informative samples; CD34+/CD38+, 5 of 9 informative samples), the highly purified CD34+ specimens also contained cytogenetically normal cells. Secondary, progression-associated chromosomal changes (+8, 12) were identified in the CD34+/CD38-cells of 2 patients. We conclude that clonal karyotypic abnormalities are frequently found in the stem cell-like (CD34+/CD38-) and more mature (CD34+/CD38+) populations of patients with AML, irrespective of the phenotype of the bulk population of leukemic blasts and of the primary or secondary character of the leukemia. Our data suggest that, in AML, malignant transformation as well as disease progression may occur at the level of CD34+/CD38-cells with multilineage potential.

scholarly journals Tolerization of a Type I Allergic Immune Response through Transplantation of Genetically Modified Hematopoietic Stem Cells

2008 ◽  
Vol 180 (12) ◽  
pp. 8168-8175 ◽  
Author(s):  
Ulrike Baranyi ◽  
Birgit Linhart ◽  
Nina Pilat ◽  
Martina Gattringer ◽  
Jessamyn Bagley ◽  
...  
Keyword(s):  
Stem Cells ◽  
Immune Response ◽  
Hematopoietic Stem Cells ◽  
Genetically Modified ◽  
Type I ◽  
Hematopoietic Stem ◽  
Allergic Immune Response

scholarly journals Bone Morphogenetic Proteins Regulate the Developmental Program of Human Hematopoietic Stem Cells

1999 ◽  
Vol 189 (7) ◽  
pp. 1139-1148 ◽  
Author(s):  
Mickie Bhatia ◽  
Dominique Bonnet ◽  
Dongmei Wu ◽  
Barbara Murdoch ◽  
Jeff Wrana ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Hematopoietic Stem Cells ◽  
Bone Morphogenetic Proteins ◽  
Transforming Growth Factor ◽  
Critical Role ◽  
Type I ◽  
Hematopoietic Tissue ◽  
Hematopoietic Stem ◽  
Proliferation And Differentiation

The identification of molecules that regulate human hematopoietic stem cells has focused mainly on cytokines, of which very few are known to act directly on stem cells. Recent studies in lower organisms and the mouse have suggested that bone morphogenetic proteins (BMPs) may play a critical role in the specification of hematopoietic tissue from the mesodermal germ layer. Here we report that BMPs regulate the proliferation and differentiation of highly purified primitive human hematopoietic cells from adult and neonatal sources. Populations of rare CD34+CD38−Lin− stem cells were isolated from human hematopoietic tissue and were found to express the BMP type I receptors activin-like kinase (ALK)-3 and ALK-6, and their downstream transducers SMAD-1, -4, and -5. Treatment of isolated stem cell populations with soluble BMP-2, -4, and -7 induced dose-dependent changes in proliferation, clonogenicity, cell surface phenotype, and multilineage repopulation capacity after transplantation in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. Similar to transforming growth factor β, treatment of purified cells with BMP-2 or -7 at high concentrations inhibited proliferation yet maintained the primitive CD34+CD38− phenotype and repopulation capacity. In contrast, low concentrations of BMP-4 induced proliferation and differentiation of CD34+ CD38−Lin− cells, whereas at higher concentrations BMP-4 extended the length of time that repopulation capacity could be maintained in ex vivo culture, indicating a direct effect on stem cell survival. The discovery that BMPs are capable of regulating repopulating cells provides a new pathway for controlling human stem cell development and a powerful model system for studying the biological mechanism of BMP action using primary human cells.

Hoxb4-deficient mice undergo normal hematopoietic development but exhibit a mild proliferation defect in hematopoietic stem cells

Blood ◽  
2004 ◽  
Vol 103 (11) ◽  
pp. 4126-4133 ◽  
Author(s):  
Ann C. M. Brun ◽  
Jon Mar Björnsson ◽  
Mattias Magnusson ◽  
Nina Larsson ◽  
Per Leveén ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Hox Genes ◽  
Fetal Liver ◽  
Severe Combined Immunodeficiency ◽  
Hematopoietic Stem ◽  
Cell Counts ◽  
Mild Reduction

Abstract Enforced expression of Hoxb4 dramatically increases the regeneration of murine hematopoietic stem cells (HSCs) after transplantation and enhances the repopulation ability of human severe combined immunodeficiency (SCID) repopulating cells. Therefore, we asked what physiologic role Hoxb4 has in hematopoiesis. A novel mouse model lacking the entire Hoxb4 gene exhibits significantly reduced cellularity in spleen and bone marrow (BM) and a subtle reduction in red blood cell counts and hemoglobin values. A mild reduction was observed in the numbers of primitive progenitors and stem cells in adult BM and fetal liver, whereas lineage distribution was normal. Although the cell cycle kinetics of primitive progenitors was normal during endogenous hematopoiesis, defects in proliferative responses of BM Lin- Sca1+ c-kit+ stem and progenitor cells were observed in culture and in vivo after the transplantation of BM and fetal liver HSCs. Quantitative analysis of mRNA from fetal liver revealed that a deficiency of Hoxb4 alone changed the expression levels of several other Hox genes and of genes involved in cell cycle regulation. In summary, the deficiency of Hoxb4 leads to hypocellularity in hematopoietic organs and impaired proliferative capacity. However, Hoxb4 is not required for the generation of HSCs or the maintenance of steady state hematopoiesis.

Epigenetic Effects of IDH1/IDH2 Mutations

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. SCI-33-SCI-33 ◽  
Author(s):  
Ari M. Melnick ◽  
Ross L Levine ◽  
Maria E Figueroa ◽  
Craig B. Thompson ◽  
Omar Abdel-Wahab
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Malignant Transformation ◽  
Covalent Modification ◽  
Specific Gene ◽  
Gene Promoters ◽  
Loss Of Function ◽  
Hematopoietic Stem

Abstract Abstract SCI-33 Epigenetic deregulation of gene expression through aberrant DNA methylation or histone modification plays an important role in the malignant transformation of hematopoietic cells. In particular, acute myeloid leukemias (AMLs) can be classified according to epigenetic signatures affecting DNA methylation or histone modifications affecting specific gene sets. Heterozygous somatic mutations in the loci encoding isocitrate dehydrogenase 1 and 2 (IDH1/2) occur in ∼20% of AMLs and are accompanied by global DNA hypermethylation and hypermethylation and silencing of a number of specific gene promoters. IDH1/2 mutations are almost completely mutually exclusive with somatic loss-of-function mutations in TET2, which hydroxylates methylcytosine (mCpG). DNA hydroxymethylation can function as an intermediate step in mCpG demethylation. TET2 mutant de novo AMLs also display global and promoter specific hypermethylation partially overlapping with IDH1/2 mutant cases. Mutations in the IDH1/2 loci result in a neomorphic enzyme that generates the aberrant oncometabolite 2-hydroxyglutarate (2HG) using α-ketoglutarate (αKG) as a substrate. 2HG can disrupt the activity of enzymes that use αKG as a cofactor, including TET2 and the jumonji family of histone demethylases. Expression of mutant IDH isoforms inhibits TET2 hydroxymethylation and jumonji histone demethylase functions. IDH and TET2 mutant AMLs accordingly exhibit reduced levels of hydroxymethylcytosine and a trend towards increased histone methylation. Mutant IDH or TET2 loss of function causes differentiation blockade and expansion of hematopoietic stem cells and TET2 knockout results in a myeloproliferative phenotype in mice. Hydroxymethylcytosine is in abundance in hematopoietic stem cells and displays specific distribution patterns, yet the function of this covalent modification is not fully understood. Recent data link TET2 with the function of cytosine deaminases as a pathway towards DNA demethylation, which has implications as well for B cell lymphomas and CML lymphoid blast crisis, which are linked with the actions of activation induced cytosine deaminase. Altogether, the available data implicate mutations in IDH1/2 and TET2 in promoting malignant transformation in several tissues, by disrupting epigenomics programming and altering gene expression patterning. Disclosures: Thompson: Agios Pharmaceuticals: Consultancy.

scholarly journals Canonical Notch Signaling Is Dispensable for the Maintenance of Adult Hematopoietic Stem Cells.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 267-267 ◽  
Author(s):  
Ivan Maillard ◽  
Seth E. Pross ◽  
Olga Shestova ◽  
Hong Sai ◽  
Jon C. Aster ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Hematopoietic Stem Cells ◽  
Notch Signaling ◽  
Transcriptional Activation ◽  
Cell Function ◽  
Fetal Life ◽  
Hematopoietic Stem

Abstract Canonical Notch signaling operates through a highly conserved pathway that regulates the differentiation and homeostasis of hematopoietic cells. Ligand-receptor binding initiates proteolytic release of the Notch intracellular domain (ICN) which migrates to the nucleus, binds the transcription factor CSL/RBPJk and activates target genes through the recruitment of transcriptional coactivators of the Mastermind-like family (MAML). Notch signaling is essential for the emergence of hematopoietic stem cells (HSCs) during fetal life, but its effects on adult HSCs are controversial. In gain-of-function experiments, activation of Notch signaling in adult HSCs increased their self-renewal potential in vitro and in vivo. However, loss-of-function studies have provided conflicting results as to the role of physiological Notch signaling in HSC maintenance and homeostasis. To address this question, we expressed DNMAML1, a GFP-tagged pan-inhibitor of Notch signaling, in mouse HSCs. We have shown previously that DNMAML1 interferes with the formation of the ICN/CSL/MAML transcriptional activation complex and blocks signaling from all four Notch receptors (Notch1-4) (Maillard, Blood 2004). Transfer of DNMAML1-transduced bone marrow (BM) as compared to control GFP-transduced BM into lethally irradiated recipients gave rise to similar long-term stable expression of GFP for at least 6 months after transplant. DNMAML1 and GFP-transduced cells contributed equally to all hematopoietic lineages, except to the T cell and marginal zone B cell lineages, which are Notch-dependent. Expression of DNMAML1 did not affect the size of the BM progenitor compartment (Lin negative, Sca-1 positive, c-Kit high, or LSK cells), or the proportion of LSK cells that were negative for Flt3 and L-Selectin expression (containing long-term HSCs). The stem cell function of DNMAML1-transduced LSK cells was further assessed with in vivo competitive repopulation assays in lethally irradiated recipients. DNMAML1 and GFP-transduced LSK cells competed equally well with wild-type BM, as judged by their contribution to the myeloid lineage up to 4 months post-transplant, through two successive rounds of transplantation. Our data indicate that canonical Notch signaling is dispensable for the maintenance of stem cell function in adult HSCs.

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