Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:Q15744 (C/EBP epsilon)
 82 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human C/EBP epsilon is a newly cloned CCAAT/enhancer-binding transcription factor. Initial studies indicated it may be an important regulator of human myelopoiesis. To elucidate the range of expression of C/EBP epsilon, we used reverse transcription-polymerase chain reaction (RT-PCR) analysis and examined its expression in 28 hematopoietic and 14 nonhematopoietic cell lines, 16 fresh myeloid leukemia samples, and normal human hematopoietic stem cells and their mature progeny. Prominent expression of C/EBP epsilon mRNA occurred in the late myeloblastic and promyelocytic cell lines (NB4, HL60, GFD8), the myelomonoblastic cell lines (U937 and THP-1), the early myeloblast cell lines (ML1, KCL22, MDS92), and the T-cell lymphoblastic leukemia cell lines CEM and HSB-2. For the acute promyelocytic leukemia cell line NB4, C/EBP epsilon was the only C/EBP family member that was easily detected by RT-PCR. No C/EBP epsilon mRNA was found in erythroid, megakaryocyte, basophil, B lymphoid, or nonhematopoietic cell lines. Most acute myeloid leukemia samples (11 of 12) from patients expressed C/EBP epsilon. Northern blot and RT-PCR analyses showed that C/EBP epsilon mRNA decreased when the HL60 and KG-1 myeloblast cell lines were induced to differentiate toward macrophages. Similarly, Western blot analysis showed that expression of C/EBP epsilon protein was either unchanged or decreased slightly as the promyelocytic cell line NB4 differentiated down the macrophage-like pathway after treatment with a potent vitamin D3 analog (KH1060). In contrast, C/EBP epsilon protein levels increased dramatically as NB4 cells were induced to differentiate down the granulocytic pathway after exposure to 9-cis retinoic acid. Furthermore, very early, normal hematopoietic stem cells (CD34+/CD38-), purified from humans had very weak expression of C/EBP epsilon mRNA, but levels increased as these cells differentiated towards granulocytes. Likewise, purified granulocytes appeared to express higher levels of C/EBP epsilon mRNA than purified macrophages. Addition of phosphothiolated antisense, but not sense oligonucleotides to C/EBP epsilon, decreased clonal growth of HL-60 and NB4 cells by about 50% compared with control cultures. Taken together, our results indicate that expression of C/EBP epsilon is restricted to hematopoietic tissues, especially myeloid cells as they differentiate towards granulocytes and inhibition of its expression in HL-60 and NB4 myeloblasts and promyelocytes decreased their proliferative capacity. Therefore, this transcriptional factor may play an important role in the process of normal myeloid development.
 ...
PMID:A novel, myeloid transcription factor, C/EBP epsilon, is upregulated during granulocytic, but not monocytic, differentiation. 932 25

We and others have cloned a novel human gene CCAAT/enhancer-binding protein epsilon (C/EBP-epsilon) encoding a member of the C/EBP gene family. It is exclusively expressed in myeloid and T-lymphoid cells and appears to have an important role in inducing expression of several myeloid-specific genes. We used a polymerase chain reaction (PCR)-based technique to examine DNA from 93 hamster/human radiation hybrid clones in order chromosomally to map C/EBP-epsilon to 14q11.2 (between D14S264 and D14S275) which is telomeric to the T-cell receptor alpha and delta genes and centromeric to several other myeloid gene products including Cathepsin G (CTSG) and Chymase-1 (CMA1). To determine whether C/EBP-epsilon behaves as an altered tumor-suppressor gene, samples from patients with acute myelogenous leukemia (AML) and myelodysplastic syndrome (MDS) evolving to AML were studied for loss of heterozygosity (LOH) using microsatellite sequences that we identified within 0.2 kb of the amino-terminus of the human C/EBP-epsilon gene. Allelic loss of the C/EBP-epsilon gene was detected in four out of 20 (20%) evolving MDS cases and in none of the 17 AML and 17 T-cell leukemia cases. Mutational analysis of the gene was performed using PCR-SSCP on 37 AML and 40 MDS cases including those with LOH at the gene. No abnormalities were found suggesting that the altered gene in this region is not C/EBP-epsilon. Also, C/EBP-epsilon was examined by Southern blot analysis on DNA samples from 20 AML patients and 10 AML cell lines. No rearrangements or amplifications of the gene were detected. Taken together, we have mapped C/EBP-epsilon to 14q11.2, a region containing other myeloid and T-lymphoid specific genes. Furthermore, no structural alterations were detected in the C/EBP-epsilon gene.
 ...
PMID:C/EBP-epsilon: chromosomal mapping and mutational analysis of the gene in leukemia and preleukemia. 939 98

The genes encoding Hoxa9 and Meis1 are transcriptionally coactivated in a subset of acute myeloid leukemia (AML) in mice. In marrow reconstitution experiments, coexpression of both genes produces rapid AML, while neither gene alone generates overt leukemia. Although Hoxa9 and Meis1 can bind DNA as heterodimers, both can also heterodimerize with Pbx proteins. Thus, while their coactivation may result from the necessity to bind promoters as heterodimers, it may also result from the necessity of altering independent biochemical pathways that cooperate to generate AML, either as monomers or as heterodimers with Pbx proteins. Here we demonstrate that constitutive expression of Hoxa9 in primary murine marrow immortalizes a late myelomonocytic progenitor, preventing it from executing terminal differentiation to granulocytes or monocytes in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin-3. This immortalized phenotype is achieved in the absence of endogenous or exogenous Meis gene expression. The Hoxa9-immortalized progenitor exhibited a promyelocytic transcriptional profile, expressing PU.1, AML1, c-Myb, C/EBP alpha, and C/EBP epsilon as well as their target genes, the receptors for GM-CSF, G-CSF, and M-CSF and the primary granule proteins myeloperoxidase and neutrophil elastase. G-CSF obviated the differentiation block of Hoxa9, inducing neutrophilic differentiation with accompanying expression of neutrophil gelatinase B and upregulation of gp91phox. M-CSF also obviated the differentiation block, inducing monocytic differentiation with accompanying expression of the macrophage acetyl-low-density lipoprotein scavenger receptor and F4/80 antigen. Versions of Hoxa9 lacking the ANWL Pbx interaction motif (PIM) also immortalized a promyelocytic progenitor with intrinsic biphenotypic differentiation potential. Therefore, Hoxa9 evokes a cytokine-selective block in differentiation by a mechanism that does not require Meis gene expression or interaction with Pbx through the PIM.
 ...
PMID:Hoxa9 immortalizes a granulocyte-macrophage colony-stimulating factor-dependent promyelocyte capable of biphenotypic differentiation to neutrophils or macrophages, independent of enforced meis expression. 1075 11

The CCAAT enhancer binding protein alpha (C/EBP alpha) transcription factor plays a critical role in granulocytopoiesis. Mice with a disruption of the C/EBP alpha gene demonstrate an early block in granulocytic differentiation, and disruption of C/EBP alpha function is a common theme in many types of human acute myelogenous leukemia, which is characterized by a block in myeloid development. To characterize further the nature of this block, we derived cell lines from the fetal liver of C/EBP alpha-deficient animals. These lines resembled morphologically the immature myeloid blasts observed in C/EBP alpha(-/-) fetal livers and did not express messenger RNA encoding early myeloid genes such as myeloperoxidase. Similarly, granulocytic markers such as Mac-1 and Gr-1 were not expressed; nor were erythroid and lymphoid surface antigens. Introduction of an inducible C/EBP alpha gene into the line revealed that conditional expression of C/EBP alpha induced the C/EBP family members C/EBP beta and C/EBP epsilon and subsequent granulocyte differentiation. Similar results were obtained when C/EBP alpha(-/-) cells were stimulated with the cytokines interleukin-3 and granulocyte-macrophage colony-stimulating factor, but not with all-trans retinoic acid, supporting a model of at least 2 pathways leading to the differentiation of myeloid progenitors to granulocytes and implicating induction of other C/EBP family members in granulopoiesis.
 ...
PMID:Induction of granulocytic differentiation by 2 pathways. 1203 69

Internal tandem duplication (ITD) mutations of the juxtamembrane domain-coding sequence of the FLT3 gene are found in up to 34% of patients with acute myeloid leukemia (AML) and are associated with a poor prognosis. FLT3/ITDs result in constitutive activation of the tyrosine kinase domain and transform growth factor-dependent cell lines. FLT3 activation leads to antiapoptotic and proliferative signals, but little is known about the impact of FLT3/ITDs on differentiation. This study was designed to investigate the effect of FLT3/ITD expression on the differentiation of the 32Dcl3 (32D) myeloblastic cell line to neutrophils in response to granulocyte colony-stimulating factor (G-CSF). Expression of FLT3/ITD completely blocked morphologic differentiation and induction of myeloperoxidase (MPO), lysozyme, and CCAAT/enhancer-binding protein epsilon (C/EBPepsilon) in response to G-CSF. Wild-type FLT3 and vector-transfected 32D cells were able to differentiate, although the maturation of FLT3-transfected cells was delayed by FLT3 ligand (FL) stimulation. CEP-701, a potent FLT3 tyrosine kinase inhibitor, overcame the morphologic block in differentiation caused by FLT3/ITD expression and allowed G-CSF induction of myeloid maturation markers. These findings suggest that blocking differentiation may be one of the mechanisms by which FLT3/ITDs contribute to leukemogenesis. CEP-701 and other FLT3 inhibitors may be useful for overcoming the block to differentiation (as well as the block to apoptosis) in the leukemic cells of patients with AML.
 ...
PMID:Targeted inhibition of FLT3 overcomes the block to myeloid differentiation in 32Dcl3 cells caused by expression of FLT3/ITD mutations. 1239 74

In vivo distribution of myeloid transcription factors during granulopoiesis was investigated by Northern and Western blotting in 3 neutrophil precursor populations from human bone marrow: immature (myeloblasts [MBs] and promyelocytes [PMs]); intermediate mature (myelocytes [MCs] and metamyelocytes [MMs]); and mature neutrophil cells (band cells [BCs] and segmented neutrophil cells [SCs]). Nonneutrophil cells were removed with magnetic-bead-coupled antibodies against CD2, CD3, CD14, CD19, CD56, CD61, glycophorin-A, and CD49d (BCs/SCs) before RNA and protein extraction. Polymorphonuclear neutrophils (PMNs) from peripheral blood depleted with anti-CD49d antibodies were also included. Expression of acute myeloid leukemia 1b (AML-1b), c-myb, GATA-1, and CCAAT/enhancer binding protein gamma (C/EBP-gamma) was seen primarily in MBs/PMs, and little expression was found in more mature cells. The level of C/EBP-alpha was constant in the bone marrow-derived cells and decreased in PMNs. C/EBP-epsilon was found primarily in MCs/MMs and was almost absent in more mature cells. Expression of C/EBP-beta, C/EBP-delta, and C/EBP-zeta was observed from the MC/MM stage onward, with peak levels in the most mature cells. The amount of PU.1 increased throughout maturation whereas the level of Elf-1 reached a nadir in MCs/MMs The PU.1 coactivator c-jun and c-jun's dimerization partner c-fos were both detectable in MCs/MMs and increased in amount with maturity. CCAAT displacement protein (CDP) was found at comparable levels at all stages of differentiation. This demonstrates a highly individualized expression of the transcription factors, which can form the basis for the heterogeneous expression of granule proteins during granulopoiesis and cell cycle arrest in metamyelocytes.
 ...
PMID:The in vivo profile of transcription factors during neutrophil differentiation in human bone marrow. 1256 Feb 39

CCAAT enhancer-binding protein (CEBP) transcription factors play pivotal roles in proliferation and differentiation, including suppression of myeloid leukemogenesis. Mutations of CEBPA are found in a subset of acute myeloid leukemia (AML) and in some cases of familial AML. Here, using cytogenetics, fluorescence in situ hybridization (FISH), and molecular cloning, we show that 5 CEBP gene family members are targeted by recurrent IGH chromosomal translocations in BCP-ALL. Ten patients with t(8;14)(q11;q32) involved CEBPD on chromosome 8, and 9 patients with t(14;19)(q32;q13) involved CEBPA, while a further patient involved CEBPG, located 71 kb telomeric of CEBPA in chromosome band 19q13; 4 patients with inv(14)(q11q32)/t(14;14)(q11;q32) involved CEBPE and 3 patients with t(14;20)(q32;q13) involved CEBPB. In 16 patients the translocation breakpoints were cloned using long-distance inverse-polymerase chain reaction (LDI-PCR). With the exception of CEBPD breakpoints, which were scattered within a 43-kb region centromeric of CEBPD, translocation breakpoints were clustered immediately 5' or 3' of the involved CEBP gene. Except in 1 patient with t(14;14)(q11;q32), the involved CEBP genes retained germ-line sequences. Quantitative reverse transcription (RT)-PCR showed overexpression of the translocated CEBP gene. Our findings implicate the CEBP gene family as novel oncogenes in BCP-ALL, and suggest opposing functions of CEBP dysregulation in myeloid and lymphoid leukemogenesis.
 ...
PMID:Five members of the CEBP transcription factor family are targeted by recurrent IGH translocations in B-cell precursor acute lymphoblastic leukemia (BCP-ALL). 1717 Jan 24

Treatment of acute promyelocytic leukemia with retinoic acid (RA) results in differentiation of the leukemic cells and clinical remission. However, the cellular factors that regulate RA-induced myeloid differentiation are largely unknown, and other forms of acute myelogenous leukemia (AML) do not respond to this differentiation therapy. A greater understanding of the molecules that positively or negatively regulate RA-induced differentiation should facilitate the development of more effective differentiation therapies. In this study, we investigated the potential role of Src family kinases (SFK) in the regulation of RA-induced gene expression and myeloid differentiation. We report that inhibition of SFKs markedly enhanced RA-induced differentiation in myeloid cell lines and primary AML cells, as assessed by flow-cytometric analysis of cell surface markers, morphologic analysis, and nitroblue tetrazolium reduction. In addition, inhibition of SFKs enhanced expression from retinoic acid receptor (RAR) target genes encoding CCAAT/enhancer binding protein epsilon (C/EBPepsilon), PU.1, intercellular adhesion molecule-1 (ICAM-1), and cathepsin D. Moreover, a constitutively active Src inhibited RAR-dependent transcription, whereas a kinase-dead Src exerted little effect. These studies provide the first demonstration that SFKs act to negatively regulate RA-induced gene expression and myeloid differentiation and suggest that the combination of SFK inhibition and RA treatment may be therapeutically beneficial in AML.
 ...
PMID:Inhibition of Src family kinases enhances retinoic acid induced gene expression and myeloid differentiation. 1806 91

Our study explored the drug interaction of all-trans retinoic acid (ATRA) and RAD001 (everolimus), the inhibitor of mammalian target of rapamycin complex 1 (mTORC1), in acute myelogenous leukemia (AML) NB4 and HL60 cells. RAD001 (10 nM) significantly enhanced the ATRA-induced growth arrest and differentiation of these cells, as measured by colony-forming assay and cell cycle analysis, and expression of CD11b cell surface antigen and nitroblue tetrazolium reduction, respectively. ATRA (0.1-1 microM) upregulated levels of RTP801, a negative regulator of mTORC1, and inhibited mTORC1 signaling as assessed by measurement of the levels of p-p70S6K and p-4E-BP1 in HL60 and NB4 cells. ATRA (0.1-1 microM) in combination with RAD001 (10 nM) strikingly downregulated the levels of p-70S6K and p-4E-BP1 without affecting the total amount of these proteins. Notably, RAD001 (10 nM) significantly augmented ATRA-induced expression of CCAAT/enhancer-binding protein epsilon (C/EBPepsilon) and p27(kip1) and downregulated levels of c-Myc in these cells. Furthermore, RAD001 (5 mg/kg) enhanced the ability of ATRA (10 mg/kg) to inhibit the proliferation of HL60 cells growing as tumor xenografts in immune-deficient nude mice. Taken together, concomitant blockade of the RA and mTORC1 signaling may be a promising treatment strategy for individuals with AML.
 ...
PMID:Inhibition of mammalian target of rapamycin signaling potentiates the effects of all-trans retinoic acid to induce growth arrest and differentiation of human acute myelogenous leukemia cells. 1950 50

The DNA hypomethylating drug decitabine maintains normal hematopoietic stem cell (HSC) self-renewal but induces terminal differentiation in acute myeloid leukemia (AML) cells. The basis for these contrasting cell fates, and for selective CpG hypomethylation by decitabine, is poorly understood. Promoter CpGs, with methylation measured by microarray, were classified by the direction of methylation change with normal myeloid maturation. In AML cells, the methylation pattern at maturation-responsive CpGs suggested at least partial maturation. Consistent with partial maturation, in gene expression analyses, AML cells expressed high levels of the key lineage-specifying factor CEBPA, but relatively low levels of the key late-differentiation driver CEBPE. In methylation analysis by mass spectrometry, CEBPE promoter CpGs that are usually hypomethylated during granulocyte maturation were significantly hypermethylated in AML cells. Decitabine-induced hypomethylation was greatest at these and other promoter CpGs that are usually hypomethylated with myeloid maturation, accompanied by cellular differentiation of AML cells. In contrast, decitabine-treated normal HSCs retained immature morphology, and methylation significantly decreased at CpGs that are less methylated in immature cells. High expression of lineage-specifying factor and aberrant epigenetic repression of some key late-differentiation driver genes distinguishes AML cells from normal HSCs, and could explain the contrasting differentiation and methylation responses to decitabine.
 ...
PMID:CpG methylation patterns and decitabine treatment response in acute myeloid leukemia cells and normal hematopoietic precursors. 2183 12


1 2 Next >>