scholarly journals From cytopenia to leukemia: the role of Gfi1 and Gfi1b in blood formation

Blood ◽  
2015 ◽  
Vol 126 (24) ◽  
pp. 2561-2569 ◽  
Author(s):  
Tarik Möröy ◽  
Lothar Vassen ◽  
Brian Wilkes ◽  
Cyrus Khandanpour
Keyword(s):  
Zinc Finger ◽  
Target Genes ◽  
Integration Site ◽  
Wide Spectrum ◽  
Human Leukemia ◽  
Specific Expression ◽  
Hematopoietic Stem ◽  
Proviral Integration Site ◽  
Cell Type Specific Expression

AbstractThe DNA-binding zinc finger transcription factors Gfi1 and Gfi1b were discovered more than 20 years ago and are recognized today as major regulators of both early hematopoiesis and hematopoietic stem cells. Both proteins function as transcriptional repressors by recruiting histone-modifying enzymes to promoters and enhancers of target genes. The establishment of Gfi1 and Gfi1b reporter mice made it possible to visualize their cell type–specific expression and to understand their function in hematopoietic lineages. We now know that Gfi1 is primarily important in myeloid and lymphoid differentiation, whereas Gfi1b is crucial for the generation of red blood cells and platelets. Several rare hematologic diseases are associated with acquired or inheritable mutations in the GFI1 and GFI1B genes. Certain patients with severe congenital neutropenia carry mutations in the GFI1 gene that lead to the disruption of the C-terminal zinc finger domains. Other mutations have been found in the GFI1B gene in families with inherited bleeding disorders. In addition, the Gfi1 locus is frequently found to be a proviral integration site in retrovirus-induced lymphomagenesis, and new, emerging data suggest a role of Gfi1 in human leukemia and lymphoma, underlining the role of both factors not only in normal hematopoiesis, but also in a wide spectrum of human blood diseases.

The role of CpG methylation in cell type-specific expression of the aquaporin-5 gene

2007 ◽  
Vol 353 (4) ◽  
pp. 1017-1022 ◽  
Author(s):  
Johji Nomura ◽  
Akinori Hisatsune ◽  
Takeshi Miyata ◽  
Yoichiro Isohama
Keyword(s):  
Cpg Methylation ◽  
Cell Type ◽  
Aquaporin 5 ◽  
Specific Expression ◽  
Cell Type Specific Expression ◽  
Cell Type Specific

scholarly journals Human leukemia mutations corrupt but do not abrogate GATA-2 function

2018 ◽  
Vol 115 (43) ◽  
pp. E10109-E10118 ◽  
Author(s):  
Koichi R. Katsumura ◽  
Charu Mehta ◽  
Kyle J. Hewitt ◽  
Alexandra A. Soukup ◽  
Isabela Fraga de Andrade ◽  
...  
Keyword(s):  
Dna Binding ◽  
Progenitor Cells ◽  
Zinc Finger ◽  
Erythroid Differentiation ◽  
Cell Types ◽  
Myeloid Differentiation ◽  
Human Leukemia ◽  
Hematopoietic Stem ◽  
Amino Terminal ◽  
Disease Mutations

By inducing the generation and function of hematopoietic stem and progenitor cells, the master regulator of hematopoiesis GATA-2 controls the production of all blood cell types. Heterozygous GATA2 mutations cause immunodeficiency, myelodysplastic syndrome, and acute myeloid leukemia. GATA2 disease mutations commonly disrupt amino acid residues that mediate DNA binding or cis-elements within a vital GATA2 intronic enhancer, suggesting a haploinsufficiency mechanism of pathogenesis. Mutations also occur in GATA2 coding regions distinct from the DNA-binding carboxyl-terminal zinc finger (C-finger), including the amino-terminal zinc finger (N-finger), and N-finger function is not established. Whether distinct mutations differentially impact GATA-2 mechanisms is unknown. Here, we demonstrate that N-finger mutations decreased GATA-2 chromatin occupancy and attenuated target gene regulation. We developed a genetic complementation assay to quantify GATA-2 function in myeloid progenitor cells from Gata2 −77 enhancer-mutant mice. GATA-2 complementation increased erythroid and myeloid differentiation. While GATA-2 disease mutants were not competent to induce erythroid differentiation of Lin−Kit+ myeloid progenitors, unexpectedly, they promoted myeloid differentiation and proliferation. As the myelopoiesis-promoting activity of GATA-2 mutants exceeded that of GATA-2, GATA2 disease mutations are not strictly inhibitory. Thus, we propose that the haploinsufficiency paradigm does not fully explain GATA-2–linked pathogenesis, and an amalgamation of qualitative and quantitative defects instigated by GATA2 mutations underlies the complex phenotypes of GATA-2–dependent pathologies.

scholarly journals Conditional ablation and conditional rescue models for Casq2 elucidate the role of development and of cell-type specific expression of Casq2 in the CPVT2 phenotype

2018 ◽  
Vol 27 (9) ◽  
pp. 1533-1544 ◽  
Author(s):  
Daniel J Flores ◽  
ThuyVy Duong ◽  
Luke O Brandenberger ◽  
Apratim Mitra ◽  
Aditya Shirali ◽  
...  
Keyword(s):  
Cell Type ◽  
Specific Expression ◽  
Cell Type Specific Expression ◽  
Cell Type Specific

scholarly journals GnRH Receptor Expression and Reproductive Function Depend on JUN in GnRH Receptor‒Expressing Cells

Endocrinology ◽  
2018 ◽  
Vol 159 (3) ◽  
pp. 1496-1510 ◽  
Author(s):  
Carrie R Jonak ◽  
Nancy M Lainez ◽  
Ulrich Boehm ◽  
Djurdjica Coss
Keyword(s):  
Target Genes ◽  
Reproductive Function ◽  
Gnrh Receptor ◽  
Receptor Expression ◽  
Specific Expression ◽  
Α Subunit ◽  
Estrous Cycles ◽  
Hormone Synthesis

Abstract Gonadotropin-releasing hormone (GnRH) from the hypothalamus regulates synthesis and secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the anterior pituitary gonadotropes. LH and FSH are heterodimers composed of a common α-subunit and unique β-subunits, which provide biological specificity and are limiting components of mature hormone synthesis. Gonadotrope cells respond to GnRH via specific expression of the GnRH receptor (Gnrhr). GnRH induces the expression of gonadotropin genes and of the Gnrhr by activation of specific transcription factors. The JUN (c-Jun) transcription factor binds to AP-1 sites in the promoters of target genes and mediates induction of the FSHβ gene and of the Gnrhr in gonadotrope-derived cell lines. To analyze the role of JUN in reproductive function in vivo, we generated a mouse model that lacks JUN specifically in GnRH receptor‒expressing cells (conditional JUN knockout; JUN-cKO). JUN-cKO mice displayed profound reproductive anomalies such as reduced LH levels resulting in lower gonadal steroid levels, longer estrous cycles in females, and diminished sperm numbers in males. Unexpectedly, FSH levels were unchanged in these animals, whereas Gnrhr expression in the pituitary was reduced. Steroidogenic enzyme expression was reduced in the gonads of JUN-cKO mice, likely as a consequence of reduced LH levels. GnRH receptor‒driven Cre activity was detected in the hypothalamus but not in the GnRH neuron. Female, but not male, JUN-cKO mice exhibited reduced GnRH expression. Taken together, our results demonstrate that GnRH receptor‒expression levels depend on JUN and are critical for reproductive function.

Role of Polycomb Repressive Complex 1 (PRC1) In Runx1 Mediated Gene Regulation

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 3863-3863
Author(s):  
Ming Yu ◽  
Tali Mazor ◽  
Hui Huang ◽  
Emily Huang ◽  
Katie Kathrein ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Board Of Directors ◽  
Target Genes ◽  
Polycomb Repressive Complex ◽  
Advisory Committees ◽  
Hematopoietic Stem ◽  
Human T Cell ◽  
Equity Ownership ◽  
Polycomb Repressive Complex 1

Abstract Abstract 3863 The transcription factor Runx1 is required for the generation of all definitive hematopoietic stem cells (HSCs), and for normal megakaryocyte, lymphocyte and granulocyte terminal maturation. Runx1 and its cofactor CBF-β are also the most common targets of chromosomal translocations in human leukemias. Somatic and germline point mutations in Runx1 occur in myelodysplastic syndrome and undifferentiated leukemias, and are associated with a poor prognosis. Despite the key roles that Runx1 plays in normal and malignant hematopoiesis, its transcriptional mechanisms remain incompletely understood. In this study, we purified Runx1 containing multiprotein complexes from megakaryocytic cells and identified several associated chromatin-remodeling complexes, including Polycomb Repressive Complex 1 (PRC1), NuRD, SWI/SNF and MLL/TrxG. Interactions were validated by independent biochemical assays and demonstrate a direct interaction between Runx1 and the PRC1 component Bmi1. ChIP-seq studies identified a large overlap between Runx1/CBF-β and Ring1b (another PRC1 core component) occupied sites, with 45% of the peaks at these genes < 200 bp from each other. ShRNA mediated gene knockdown of CBF-β shows differential gene expression of many of the co-occupied genes. Among the direct CBF-β/Ring1b co-occupied targets are other key hematopoietic transcription factors including FOG-1, SCL and Lyl1, and a number of cell adhesion related genes. ShRNA knockdown of Ring1b impairs megakaryocyte endomitosis, partially phenocopying Runx1 deficient megakaryocytes. Morpholino mediated knockdown of Ring1b or Bmi1 in zebrafish embryos reduces the number of phenotypic definitive HSCs, also partially phenocopying Runx1 morphants. We also show that Runx1/CBF-β interact with Ring1b in the human T cell line Jurkat, and that Ring1b occupies Runx1/CBF-β bound sites of key direct target genes in primary murine thymocytes, including CD4, TCRβ, and Th-POK. Surprisingly, we did not find enrichment for histone 2A monoubiquitination at most of the megakaryocytic and T-lymphocyte co-occupied sites examined, suggesting that PRC1 acts through alternate mechanisms at these genes. Collectively, these data provide evidence for a broad role of PRC1 in Runx1 mediated gene regulation. Disclosures: Zon: FATE, Inc.: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; Stemgent: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Cantor:Amgen, Inc: Consultancy.

ASXL2 Is a Novel Mediator of RUNX1-ETO Transcriptional Function and Collaborates with RUNX1-ETO to Promote Leukemogenesis

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 302-302
Author(s):  
Jean-Baptiste Micol ◽  
Nicolas Duployez ◽  
Alessandro Pastore ◽  
Robert Williams ◽  
Eunhee Kim ◽  
...  
Keyword(s):  
Stem Cell ◽  
Cell Line ◽  
Hematopoietic Stem Cell ◽  
Binding Sites ◽  
Target Genes ◽  
Cell Function ◽  
Rna Seq ◽  
Hematopoietic Stem

Abstract Mutations in Addition of Sex Combs Like 1 (ASXL1) are common in patients with myeloid leukemias. More recently, mutations in ASXL2, a paralog of ASXL1 with ~40% shared amino acid homology, have been discovered to occur specifically in patients with acute myeloid leukemia (AML) patients bearing the RUNX1-ETO (AML1-ETO; RUNX1-RUNX1T1) translocation and are amongst the most common mutations in RUNX1-ETO AML (mutated in 20-25% of patients). Although ASXL1 is critical for Polycomb Repressive Complex 2 function in myeloid hematopoietic cells and loss of Asxl1 recapitulates key aspects of myelodysplastic syndrome (MDS), the function of ASXL2 in normal or malignant hematopoiesis is unknown. We therefore set out to perform a functional comparison of ASXL1and ASXL2on hematopoiesis and transcription and determine the functional basis for frequent mutations in RUNX1-ETO AML. In vitro analyses of ASXL2 insertion/deletion mutations revealed that these mutations resulted in substantial reduction of ASXL2 protein expression, stability, and half-life. We therefore generated Asxl2 conditional knockout (cKO) mice to delineate the effect of ASXL2 loss on hematopoiesis. Competitive (Fig. 1A) and noncompetitive transplantation revealed that Asxl2 or compound Asxl1/2 loss resulted in cell-autonomous, rapid defects of hematopoietic stem cell function, self-renewal, and number with peripheral blood leukopenia and thrombocytopenia but without any obvious MDS features- phenotypes distinct from Asxl1 cKO mice. Mice with heterozygous deletion of Asxl2 demonstrated an intermediate phenotype between control and homozygous cKO mice indicating a gene dosage effect of Asxl2 loss. RNA sequencing (RNA-seq) of hematopoietic stem/progenitor cells from Asxl2- and Asxl1-deficient mice revealed twenty-fold greater differentially expressed genes in Asxl2 cKO mice relative to Asxl1 cKO mice. Interestingly, genes differentially expressed with Asxl2 loss significantly overlapped with direct transcriptional targets of RUNX1-ETO, findings not seen in Asxl1 cKO mice (Fig. 1B). Asxl2 target genes appeared to also be targets of RUNX1, a key gene repressed by RUNX1-ETO to promote leukemogenesis. Consistent with this, genome-wide analysis of Asxl2 binding sites through anti-Asxl2 ChIP-seq revealed that Asxl2 binding sites substantially overlap with those of Runx1. Overall, the above data suggest that Asxl2 may be a critical mediator of RUNX1-ETO mediated leukemogenesis by affecting the expression of RUNX1 and/or RUNX1-ETO target genes. RNA-seq of primary RUNX1-ETO AML patient samples revealed that ASXL2-mutant RUNX1-ETO patients form a distinct transcriptional subset of RUNX1-ETO AML (Fig. 1C) suggesting a specific role of ASXL2 in leukemogenesis. To functionally interrogate the role of ASXL2 loss in RUNX1-ETO mediated leukemogenesis we first utilized an in vitro model with RNAi-mediated depletion of ASXL1 or ASXL2 in the SKNO1 cell line (the only ASXL-wildtype human RUNX1-ETO cell line). RNA-seq revealed distinct target genes dysregulated by ASXL1 versus ASXL2 loss in these cells without any significant overlap. Anti-ASXL2, RUNX1, and RUNX1-ETO ChIPSeq in SKNO1 cells revealed significant co-occupancy of ASXL2 with RUNX1 and RUNX1-ETO binding sites. Moreover, analysis of histone modification ChIPSeq revealed an enrichment in intergenic and enhancer H3K4me1 abundance following ASXL2 loss in SKNO1 cells. Next, to understand the in vivo effects of Asxl2 loss in the context of RUNX1-ETO, we performed retroviral bone marrow (BM) transplantation assays using RUNX1-ETO9a in Asxl2 cKO mice. In contrast to the failure of hematopoietic stem cell function with Asxl2 deletion alone, mice reconstituted with BM cells expressing RUNX1-ETO9a in Asxl2-deficient background had a shortened leukemia-free survival compared to Asxl2 -wildtype control. Overall, these data reveal that ASXL2 is required for hematopoiesis and has differing biological and transcriptional functions from ASXL1. Moreover, this work identifies ASXL2 as a novel mediator of RUNX1-ETOtranscriptional function and provides a new model of penetrant RUNX1-ETO AML based on genetic events found in a substantial proportion of t(8;21) AML patients. Further interrogation of the enhancer alterations generated by ASXL2 loss in RUNX1-ETO AML may highlight new therapeutic approaches for this subset of AML. Figure 1. Figure 1. Disclosures No relevant conflicts of interest to declare.

scholarly journals Nostopeptolide plays a governing role during cellular differentiation of the symbiotic cyanobacteriumNostoc punctiforme

2015 ◽  
Vol 112 (6) ◽  
pp. 1862-1867 ◽  
Author(s):  
Anton Liaimer ◽  
Eric J. N. Helfrich ◽  
Katrin Hinrichs ◽  
Arthur Guljamow ◽  
Keishi Ishida ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Cellular Differentiation ◽  
Polyketide Synthase ◽  
Maldi Imaging ◽  
Free Living ◽  
Specific Expression ◽  
Living State ◽  
Cell Type Specific Expression ◽  
Cell Type Specific

Nostoc punctiformeis a versatile cyanobacterium that can live either independently or in symbiosis with plants from distinct taxa. Chemical cues from plants andN. punctiformewere shown to stimulate or repress, respectively, the differentiation of infectious motile filaments known as hormogonia. We have used a polyketide synthase mutant that accumulates an elevated amount of hormogonia as a tool to understand the effect of secondary metabolites on cellular differentiation ofN. punctiforme. Applying MALDI imaging to illustrate the reprogramming of the secondary metabolome, nostopeptolides were identified as the predominant difference in thepks2−mutant secretome. Subsequent differentiation assays and visualization of cell-type-specific expression of nostopeptolides via a transcriptional reporter strain provided evidence for a multifaceted role of nostopeptolides, either as an autogenic hormogonium-repressing factor or as a chemoattractant, depending on its extracellular concentration. Although nostopeptolide is constitutively expressed in the free-living state, secreted levels dynamically change before, during, and after the hormogonium differentiation phase. The metabolite was found to be strictly down-regulated in symbiosis withGunnera manicataandBlasia pusilla, whereas other metabolites are up-regulated, as demonstrated via MALDI imaging, suggesting plants modulate the fine-balanced cross-talk network of secondary metabolites withinN. punctiforme.

scholarly journals A novel role for Lef-1, a central transcription mediator of Wnt signaling, in leukemogenesis

2008 ◽  
Vol 205 (3) ◽  
pp. 515-522 ◽  
Author(s):  
Konstantin Petropoulos ◽  
Natalia Arseni ◽  
Christina Schessl ◽  
Christiane R. Stadler ◽  
Vijay P.S. Rawat ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Myeloid Leukemia ◽  
Human Leukemia ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Hematopoietic Development ◽  
Canonical Wnt ◽  
Limiting Dilution ◽  
Severe Disturbance

Canonical Wnt signaling is critically involved in normal hematopoietic development and the self-renewal process of hematopoietic stem cells (HSCs). Deregulation of this pathway has been linked to a large variety of cancers, including different subtypes of leukemia. Lef-1 is a major transcription factor of this pathway and plays a pivotal role in lymphoid differentiation as well as in granulopoiesis. Here, we demonstrate Lef-1 expression in murine HSCs as well as its expression in human leukemia. Mice transplanted with bone marrow retrovirally transduced to express Lef-1 or a constitutive active Lef-1 mutant showed a severe disturbance of normal hematopoietic differentiation and finally developed B lymphoblastic and acute myeloid leukemia (AML). Lef-1–induced AMLs were characterized by immunoglobulin (Ig) DH-JH rearrangements and a promiscuous expression of lymphoid and myeloid regulatory factors. Furthermore, single cell experiments and limiting dilution transplantation assays demonstrated that Lef-1–induced AML was propagated by a leukemic stem cell with lymphoid characteristics displaying Ig DH-JH rearrangements and a B220+ myeloid marker− immunophenotype. These data indicate a thus far unknown role of Lef-1 in the biology of acute leukemia, pointing to the necessity of balanced Lef-1 expression for an ordered hematopoietic development.

Histone Acetyltransferase Activity of p300 Is Required for Transcriptional Repression by the Promyelocytic Leukemia Zinc Finger Protein.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 359-359
Author(s):  
Fabien Guidez ◽  
Louise Howell ◽  
Mark Isalan ◽  
Marek Cebrat ◽  
Rhoda M. Alani ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Binding ◽  
Histone Deacetylase ◽  
Zinc Finger ◽  
Transcriptional Repression ◽  
Promyelocytic Leukemia ◽  
Promyelocytic Leukemia Zinc Finger ◽  
Hematopoietic Stem

Abstract The Promyelocytic Leukemia Zinc Finger (PLZF) gene was identified in a rare case of acute promyelocytic leukemia (APL) with translocation t(11;17)(q23;q21) and resistance to therapy with all-trans-retinoic acid. Recent studies have indicated a critical role of PLZF in maintenance of spermatogonial stem cells. Prominent expression of PLZF in hematopoietic stem cells, suggest that it may also play a similar role in this compartment. The wild type PLZF protein is a DNA sequence-specific transcription repressor containing nine Krüppel-like C2-H2 zinc fingers and an N-terminal BTB/POZ repression domain. Transcriptional repression by PLZF is mediated through recruitment of the nuclear receptor co-repressor (N-CoR/SMRT)/histone deacetylase (HDAC) complexes to its target genes, such as c-MYC and HOX genes. We now show that transcriptional repression by PLZF is surprisingly also dependent on the histone acetyl transferase (HAT) activity of the p300 protein. PLZF associates with p300 in vivo and its ability to repress transcription is specifically dependent on acetylation of PLZF on lysines in its C-terminal C2-H2 zinc-finger motifs. Acetylation of PLZF enhances its ability to bind its cognate DNA binding site in vitro as determined by EMSA and in vivo as measured by chromatin immunoprecipitation. An acetylation site mutant of PLZF fails to repress transcription despite retaining its abilities to interact with co-repressor/HDAC complexes, due to inefficient DNA binding. Inhibitors of p300 abolish transcriptional repression by PLZF and mutants of PLZF that mimic acetylation were insensitive to these inhibitory effects. Acetylation of PLZF by p300 was specific since over-expression of another HAT, p/CAF or the selective inhibition of p/CAF had no effect on PLZF activity despite the ability of the proteins to associate with each other. Taken together, our results indicate that a histone deacetylase dependent transcriptional repressor can be positively regulated through acetylation and point to an unexpected role of a co-activator protein in transcriptional repression.

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