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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Rights and Permissions Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Jones, L. C. Articles by Koeffler, H. P. Search for Related Content PubMed PubMed Citation Articles by Jones, L. C. Articles by Koeffler, H. P. Related Collections Hematopoiesis and Stem Cells Gene Expression Social Bookmarking                   What's this?  Previous Article  |  Table of Contents  |  Next Article  Blood, 15 March 2002, Vol. 99, No. 6, pp. 2032-2036 HEMATOPOIESIS Expression of C/EBP from the C/ebp gene locus is sufficient for normal hematopoiesis in vivo Letetia C. Jones, Meng-Liang Lin, Shih-Shun Chen, Utz Krug, Wolf-K. Hofmann, Stephen Lee, Ying-Hue Lee, and H. Phillip Koeffler From the Division of Hematology and Oncology, Department of Medicine, and the Department of Pathology, Cedars-Sinai Medical Center, University of California-Los Angeles School of Medicine; Laboratory of Molecular Pathology, Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan; School of Medical Technology, China Medical College, Taichung, Taiwan.     Abstract Top Abstract Introduction Materials and methods Results Discussion References CCAAT/enhancer-binding proteins (C/EBPs) are critical transcriptional regulators of differentiation of hematopoietic cells. Previous studies have shown that targeted disruption of the C/ebp gene results in a lack of granulocytic differentiation with an arrest at the stage of immature myeloblasts. By using a gene replacement strategy in which C/EBP was expressed from the C/ebp gene locus of C/EBP-null mice, we have evaluated the ability of C/EBP to function for C/EBP in directing differentiation along the granulocytic pathway. We show that the morphology and the differential cell counts of the bone marrow and peripheral blood cells from C/EBP knockin mice are indistinguishable from those of their wild-type littermates, indicating that hematopoiesis occurs normally in these animals. Additionally, we analyzed expression of 21 myeloid-specific genes, including markers for distinct stages of granulocytic differentiation, and found no significant differences in their levels of expression in the bone marrow of C/EBP knockin and wild-type mice. These results imply that C/EBP can substitute for C/EBP during hematopoiesis when expressed from the C/ebp gene locus. (Blood. 2002;99:2032-2036) © 2002 by The American Society of Hematology.     Introduction Top Abstract Introduction Materials and methods Results Discussion References CCAAT/enhancer-binding proteins (C/EBPs) are a family of structurally related transcription factors made up of 6 members (C/EBP, -, -, -, -, and -).1-7 All C/EBPs share conserved C-terminal regions that contain leucine-zipper dimerization motifs adjacent to basic DNA-binding domains.8 Their N-terminal regions are more diverse and contain transcriptional activation domains. Dimerization within the C/EBP family or with other transcription factors is a prerequisite for DNA binding and subsequent transactivation. With the exception of C/EBP, proteins in the C/EBP family are expressed in partially overlapping patterns in multiple tissues.9 However, targeted inactivation of C/EBP family genes in mice has demonstrated their individual contributions to cellular differentiation. Knockout mice models have defined a critical role for C/EBPs in hematopoietic tissues.10-14 Two members, C/EBP and C/EBP, play key roles in determining the fate of differentiating hematopoietic cells. For example, C/EBP is expressed in early myeloid cells,9 and its absence in C/EBP/ mice leads to a complete lack of granulocytic differentiation with an arrest at the stage of immature myeloblasts.10 Although mature neutrophils and eosinophils are absent in C/EBP-null mice, other hematopoietic lineages are not affected. C/EBP, however, appears to be a critical signaling molecule for more mature myeloid cells as well as for B lymphocytes because its expression is dramatically induced during macrophage differentiation9,15 and lymphopoiesis.12 Targeted deletion of C/EBP in mice results in impaired macrophage function, lymphoproliferative disorders, and defective B lymphopoiesis. Differential expression of these 2 C/EBPs in hematopoietic tissues underscores their individual roles in the development of mature blood cells. In addition to their roles in the hematopoietic system, C/EBP and C/EBP are important for normal development of liver16,17 and adipose tissue.4,18 Mice lacking C/EBP die within 8 hours of birth because of a severe loss of liver function. However, a gene replacement approach in which C/EBP is knocked into the C/ebp gene locus of C/EBP-null mice restores liver function and, consequently, their viability.19 These mutant mice, C/ebp/, lack C/EBP but have a concomitant gain of C/EBP in tissues. In the current study, we evaluate the ability of C/EBP functionally to replace C/EBP in the hematopoietic system of C/ebp/ mice. We find that bone marrow and peripheral blood cells from C/EBP knockin mice are indistinguishable from those of their wild-type littermates, indicating that hematopoiesis occurs normally in these animals. We confirm this finding on a molecular level by analyzing the expression of 21 myeloid-specific genes, including markers for distinct stages of granulocytic differentiation. Our results reveal no significant differences in the levels of expression of these genes in bone marrow of C/EBP knockin and wild-type mice, thus implying that C/EBP can substitute for C/EBP during hematopoiesis when expressed from the C/ebp gene locus.     Materials and methods Top Abstract Introduction Materials and methods Results Discussion References Mice C/ebp/ mice were generated by using gene-targeting technology and the Cre/loxP DNA recombination system as reported previously.19 Mice were maintained in a specific pathogen-free animal facility at the Institute of Molecular Biology, Academia Sinica, Taipei. Five- to 6-week-old littermates from the heterozygote interbreedings were used in this study. Bone marrow morphologic analysis Bone marrow was collected from the femoral bone of wild-type and C/EBP knockin mice. Smears were prepared and stained with Wright-Giemsa. Bone marrow smears were analyzed by light microscopy. Differential cell counts Differential white cell counts for peripheral blood and bone marrow were determined manually by 2 independent investigators. Percentages were calculated according to the cell morphology of a total of 600 cells per peripheral blood smear and 700 cells per bone marrow smear. Values are given as mean ± SD from 3 independent animals. RNA isolation and reverse transcription-polymerase chain reaction Total RNA was isolated from mononuclear bone marrow cells of 4 wild-type and 4 C/EBP knockin mice by using TRIzol (Life Technologies, Grand Islands, NY). Two micrograms of DNAse I-treated RNA was reverse transcribed by using Moloney murine leukemia virus reverse transcriptase (Life Technologies), and 50 ng of the resulting complementary DNAs (cDNAs) was used as templates for polymerase chain reaction (PCR). Amplification was carried out by using HotStarTaq DNA polymerase (Qiagen, Valencia, CA) under the following conditions: an initial denaturation step at 95°C for 15 minutes followed by 35 cycles of 95°C for 30 seconds, 60°C for 30 seconds, and 72°C for 1 minute. The specificity of primer pairs used for amplification was confirmed by Southern blot by using internal oligonucleotides as probes. Reaction products were visualized on ethidium bromide-stained agarose gels, and images of C/EBP, C/EBP, and 18S DNAs were captured by using AlphaImager 2000 Gel Documentation software. Reverse transcriptase(RT)-PCR results were confirmed by varying input cDNA concentration and cycle number or by real-time PCR. For the latter, RT-PCR reactions were carried out by using HotStarTaq DNA polymerase (Qiagen), 50 ng cDNA for myeloid-specific genes (500-5 ng in serial dilutions for standard curves) or 1 pg for 18S (10-0.1 pg for standard curve), and SYBRGreenI nucleic acid gel staining solution in a 1:60 000 dilution. PCR conditions were as follows: a 95°C initial activation for 15 minutes followed by 45 cycles of 95°C for 15 seconds, 60°C for 15 seconds, and 72°C for 30 seconds, and fluorescence determination at the melting temperature of the product for 20 seconds on an ICycler detection system (BioRad, Hercules, CA).     Results Top Abstract Introduction Materials and methods Results Discussion References Construction of a C/EBP knockin targeting vector and generation of homozygous C/ebp/ mice were described previously.19 These mice carry a mutant C/ebp allele in which the protein-coding region of C/ebp was deleted and replaced with that of C/ebp. C/ebp/ mice are viable, fertile, and grossly normal and exhibit growth rates that are identical to their wild-type littermates. Furthermore, they show none of the liver abnormalities found in the C/EBP-null mice, implying that C/EBP can functionally replace C/EBP in the liver when expressed from the C/ebp gene locus. The functional redundancy of C/EBP and C/EBP in liver raised the question of their redundancy in hematopoietic cells. Previous studies10 suggest that C/EBP is indispensable for differentiation along the granulocytic pathway because C/EBP-deficient mice lack mature neutrophils and eosinophils. Therefore, we evaluated the ability of C/EBP to compensate for C/EBP in the hematopoietic system of C/ebp/ mice. Analysis of peripheral blood from C/ebp/ mice and their wild-type littermates (Table 1) showed similar differential cell counts for all hematopoietic lineages, including myeloid elements from myeloblasts to mature neutrophils. Additionally, no differences in morphology were observed in Wright-Giemsa-stained bone marrow cells from C/EBP knockin and wild-type mice (Figure 1). C/EBP knockin and wild-type murine bone marrow also stained equally for the myeloid-specific, azurophilic protein myeloperoxidase and for Sudan black, a marker of myeloid progenitors (data not shown). The white blood cell counts of the C/EBP knockin mice were in the normal range (mean, 4.4 × 109/µL), and for unclear reasons the wild-type mice had a slightly elevated white blood cell count (mean, 7.8 × 109/µL).20 The morphology and number of neutrophils in the peripheral blood (Table 1 and data not shown) of the C/EBP knockin animals were normal,20 indicating that expression of C/EBP from the C/ebp gene locus overcomes the block in granulocytic differentiation observed in the C/EBP-null mice. To rule out the possibility that this rescue is due to in vivo compensatory mechanisms other than the expression of C/EBP, bone marrow cells from wild-type and C/EBP knockin mice were used for in vitro colony assays in the presence of granulocyte colony-stimulating factor. The number of granulocyte colonies formed from bone marrow cells from knockin mice was not different from that seen when using bone marrow cells from wild-type animals (data not shown). The granulocyte colonies contained similar percentages of neutrophils in assays of bone marrow cells from knockin and wild-type mice (85.7 ± 3.1 and 82.3 ± 3.5, respectively). These data imply that differentiation along the granulocytic pathway is due to functional replacement of C/EBP with C/EBP and is not likely to be attributable to C/EBP-independent pathways.                                View this table: [in this window] [in a new window]   Table 1. Analysis of peripheral blood and bone marrow from wild-type and C/EBP knockin mice View larger version (70K): [in this window] [in a new window]   Figure 1. Wright-Giemsa-stained bone marrow cells from wild-type and C/EBP knockin mice. Bone marrow smears from wild-type (A) and C/ebp/ (B) mice show maturation of the myeloid lineage to mature granulocytes (indicated by G). Magnification × 100. The presence of a mature granulocytic population in C/ebp/ mice implies that genes necessary for differentiation are appropriately expressed. To verify this at the molecular level, we evaluated the expression of 21 myeloid-specific genes in bone marrow cells from C/EBP knockin mice and their wild-type littermates. We first confirmed the lack of C/EBP expression in the bone marrow of C/ebp/ mice by RT-PCR (Figure 2). The knockin mice showed increased expression of C/EBP compared with C/ebp+/+ mice, representing transcripts from both the C/ebp and C/ebp gene loci. View larger version (87K): [in this window] [in a new window]   Figure 2. Expression of C/EBP and C/EBP messenger RNAs in wild-type and C/EBP knockin mice. Gene expression was measured by RT-PCR using RNA from the bone marrow of wild-type and C/EBP knockin mice. After 35 (C/EBP and C/EBP) and 15 (18S) cycles, amplification products were gel separated and stained with ethidium bromide. Other genes evaluated include (1) markers for different stages of maturation along the granulocytic pathway (primary and secondary granule proteins), (2) eosinophil-specific proteins, (3) colony-stimulating factor receptors and other cytokine-signaling proteins, and (4) proteins involved in phagocytosis (components of nicotinamide adenine dinucleotide phosphate oxidase and an antimicrobial protein). The individual genes analyzed are listed in Table 2. Our studies revealed no differences in the expression of these genes in C/ebp/ and C/ebp+/+ mice (Figure 3). This finding is consistent with the lack of morphologic differences between the 2 genotypes.                                View this table: [in this window] [in a new window]   Table 2. Twenty-one myeloid-specific genes show no differences in expression in bone marrow cells of C/ebp/ as compared with wild-type mice View larger version (46K): [in this window] [in a new window]   Figure 3. Expression of myeloid-specific genes in wild-type and C/EBP knockin mice. Gene expression was measured by RT-PCR using RNA from the bone marrow of wild-type and C/EBP knockin mice. After 15 (18S) and 35 (all other genes) cycles, amplification products were gel separated and stained with ethidium bromide. G-CSF R indicates granulocyte-colony stimulating factor receptor; MPO, myeloperoxidase. For 7 of these genes, expression levels were quantified by using quantitative RT-PCR. RNA from the bone marrow of 4 wild-type and 4 C/EBP knockin mice were reverse transcribed, and the resulting cDNAs were analyzed by real-time PCR. The values for individual mice within each group were averaged, and expression values in C/EBP knockin mice are given in Table 3 relative to expression in wild-type animals (arbitrarily set at 1.0). Again, our results indicate that the levels of expression of these genes in C/EBP knockin mice do not significantly differ from those observed for the wild-type animals, suggesting that gene expression is normal in the knockin mice.                                View this table: [in this window] [in a new window]   Table 3. Real-time PCR analysis of gene expression in wild-type and C/EBP knockin mice     Discussion Top Abstract Introduction Materials and methods Results Discussion References Mice with targeted deletion of C/EBP die soon after birth from hypoglycemia, and analysis of their peripheral blood and bone marrow reveal hematopoietic abnormalities, including the absence of granulocytic differentiation.10 Thus, normal expression of C/EBP does not compensate for the C/EBP deficiency in the liver or hematopoietic tissue of C/EBP-null mice. However, recent studies showed that expression of C/EBP from the C/ebp gene locus, in addition to its expression from the C/ebp allele, restored liver function and overcomes the neonatal lethality of C/EBP/ mice.19 Similarly, in this report, we show that expression of C/EBP from the C/ebp locus restores normal hematopoiesis by overcoming the selective block in granulocytic differentiation observed in the C/EBP-null mice. The ability of C/EBP to function for C/EBP in hematopoietic cells of C/ebp/ mice is likely related to at least 2 aspects of expression from the C/ebp gene locus: (1) the level of transcriptional activity and (2) the timing of expression. In hepatic tissues of C/ebp/ mice, C/EBP messenger RNA expressed from the C/ebp locus is significantly higher than expression of C/EBP from its endogenous allele.19 Although our studies do not quantify the contribution of C/EBP messenger RNA from each locus in hematopoietic cells, we do observe higher expression of C/EBP in the knockin model, representing the combined expression from both loci. Radomska et al21 suggested that high levels of C/EBP at the stage of myeloid commitment is the molecular switch that directs myeloid precursors to the granulocytic pathway. Because myeloid progenitor cells express low levels of C/EBP, the amount of C/EBP in C/EBP-null mice is possibly insufficient to transactivate genes whose expression is required for granulocytic differentiation. Although it is low in early stages of myeloid differentiation, the level of C/EBP expression increases dramatically at later stages of differentiation especially in maturing macrophages.9 C/EBP/ mice have defects in macrophage function and develop lymphoproliferative disorders as a result, but deletion of C/EBP in mice does not adversely affect myeloid cell differentiation.13 Hence, its role in myelopoiesis is unclear. Expression of C/EBP from the C/ebp locus places the protein at the scene of hematopoietic differentiation earlier and probably at higher levels than when expressed from the C/ebp gene locus. Therefore, the rescue of granulocytic differentiation in C/ebp/ mice likely reflects changes in the temporal expression of C/EBP. Stages of differentiation in hematopoietic cells are driven not only by C/EBPs but also by other transcription factor groups including GATA-122,23 and GATA-2,24,25 Myb,26-28 Ets,29-31 and AML1.32-34 Perhaps high expression of C/EBP early in myelopoiesis is sufficient to maintain the integrity of protein-protein interactions that direct myeloid progenitors toward mature granulocytes. C/EBPs are highly homologous in their C-terminal dimerization and DNA-binding domains and are believed to bind the same recognition sites on DNA.35 Therefore, C/EBP conceivably can interact with dimerization partners of C/EBP and bind C/EBP-targeted promoters such as the receptors for granulocyte colony-stimulating factor36 and interleukin 6,37 myeloperoxidase,38 and neutrophil elastase.39 However, the N-terminal regions of C/EBPs are more diverse and mediate their transactivation functions. Given the complexity of transcriptional activation complexes, we are somewhat surprised that the transactivation domain of C/EBP can recruit necessary cofactors to activate promoters normally directed by the transactivation domain of C/EBP. Interestingly, C/EBP does not substitute for C/EBP in the expression of genes encoding adipocyte-specific factors adipsin and leptin.19 Abnormalities in fat storage but normal liver development and hematopoiesis suggest that the redundancy of C/EBP and C/EBP may be tissue and gene specific. Previous studies implicate C/EBP as a critical factor for granulocytic commitment of myeloid progenitor cells. Strain differences between mice may reconcile our findings with the strict requirement for C/EBP in granulocytic differentiation reported previously. However, it is more likely that C/EBP itself is less important than the timing and level of its expression.     Footnotes Submitted August 2, 2001; accepted November 14, 2001. Supported by grants from the National Institutes of Health (H.P.K.), the C. and H. Koeffler Fund, Parker Hughes Trust, Brian Harvey Fund, Frederick P. Begell Foundation, and the Joseph Troy Leukemia Foundation. L.C.J. is supported by grants from the American Cancer Society (PF-99-127-01-CNE) and the National Institutes of Health (T32 CA-75956). W.K.H. is a recipient of a scholarship from the Deutsche Forschungsgemeinschaft (HO2207/1-1). H.P.K. is a member of the Jonsson Comprehensive Cancer Center and holds the endowed Mark Goodson Chair of Oncology Research at Cedars-Sinai Medical Center/UCLA School of Medicine. The publication costs of this article were defrayed in part by page charge payment. Therefore, and solely to indicate this fact, this article is hereby marked "advertisement" in accordance with 18 U.S.C. section 1734. Reprints: Letetia C. Jones, Division of Hematology and Oncology, Cedars-Sinai Medical Center, UCLA School of Medicine, 8700 Beverly Blvd, Suite BM-1, Rm 109, Los Angeles, CA 90048; e-mail: Letetia.Jones{at}cshs.org.     References Top Abstract Introduction Materials and methods Results Discussion References 1. Landschulz WH, Johnson PF, Adashi EY, Graves BJ, McKnight SL. Isolation of a recombinant copy of the gene encoding C/EBP. Genes Dev. 1988;2:786-800[Abstract/Free Full Text]. 2. Akira S, Isshiki H, Sugita T, et al. A nuclear factor for IL-6 expression (NF-IL6) is a member of a C/EBP family. EMBO J. 1990;9:1897-1906[Medline] [Order article via Infotrieve]. 3. Roman C, Platero JS, Shuman JD, Calame K. Ig/EBP-1: a ubiquitously expressed immunoglobulin enhancer binding protein that is similar to C/EBP and heterodimerizes with C/EBP. Genes Dev. 1990;4:1401-1415. 4. Cao Z, Umek RM, McKnight SL. Regulated expression of three C/EBP isoforms during adipose conversion of 3T3-L1 cells. Genes Dev. 1991;5:1538-1552[Abstract/Free Full Text]. 5. Antonson P, Stellan B, Yamanaka R, Xanthopoulos KG. A novel human CCAAT/enhancer binding protein gene, C/EBP, is expressed in cells of lymphoid and myeloid lineages and is located on chromosome 14q11.2 close to the T-cell receptor alpha/delta locus. Genomics. 1996;35:30-38[CrossRef][Medline] [Order article via Infotrieve]. 6. Chumakov AM, Grillier I, Chumakova E, Chih D, Slater J, Koeffler HP. Cloning of the novel human myeloid-cell-specific C/EBP- transcription factor. Mol Cell Biol. 1997;17:1375-1386[Abstract]. 7. Ron D, Habener JF. CHOP, a novel developmentally regulated nuclear protein that dimerizes with transcription factors C/EBP and LAP and functions as a dominant-negative inhibitor of gene transcription. Genes Dev. 1992;6:439-453[Abstract/Free Full Text]. 8. Landschulz WH, Johnson PF, McKnight SL. The DNA binding domain of the rat liver nuclear protein C/EBP is bipartite. Science. 1989;243:1681-1688[Abstract/Free Full Text]. 9. Scott LM, Civin CI, Rorth P, Friedman AD. A novel temporal expression pattern of three C/EBP family members in differentiating myelomonocytic cells. Blood. 1992;80:1725-1735[Abstract/Free Full Text]. 10. Zhang D, Zhang P, Wang N, Hetherington C, Darlington GJ, Tenen DG. Absence of granulocyte colony-stimulating factor signaling and neutrophil development in CCAAT enhancer binding protein -deficient mice. Proc Natl Acad Sci U S A. 1997;94:569-574[Abstract/Free Full Text]. 11. Tanaka T, Akira S, Yoshida K, et al. Targeted disruption of the NF-IL6 gene discloses its essential role in bacteria killing and tumor cytotoxicity by macrophages. Cell. 1995;80:353-361[CrossRef][Medline] [Order article via Infotrieve]. 12. Chen X, Liu W, Ambrosino C, et al. Impaired generation of bone marrow B lymphocytes in mice deficient in C/EBP. Blood. 1997;90:156-164[Abstract/Free Full Text]. 13. Screpanti I, Romani L, Musiani P, et al. Lymphoproliferative disorder and imbalanced T-helper response in C/EBP beta-deficient mice. EMBO J. 1995;14:1932-1941[Medline] [Order article via Infotrieve]. 14. Yamanaka R, Barow C, Lekstrom-Himes J, et al. Impaired granulopoiesis, myelodysplasia and early lethality in C/EBP-deficient mice. Proc Natl Acad Sci U S A. 1997;94:13187-13192[Abstract/Free Full Text]. 15. Natsuka S, Akira S, Nishio Y, et al. Macrophage differentiation-specific expression of NF-IL6, a transcription factor for interleukin-6. Blood. 1992;79:460-466[Abstract/Free Full Text]. 16. Lee YH, Sauer B, Johnson PF, Gonzalez FJ. Disruption of the c/ebp gene in adult mouse liver. Mol Cell Biol. 1997;17:6014-6022[Abstract]. 17. Wang ND, Finegold MJ, Bradley A, et al. Impaired energy homeostasis in C/EBP knockout mice. Science. 1995;269:1108-1112[Abstract/Free Full Text]. 18. Yeh WC, Cao Z, Classon M, McKnight SL. Cascade regulation of terminal adipocyte differentiation by three members of the C/EBP family of leucine zipper proteins. Genes Dev. 1995;9:168-181[Abstract/Free Full Text]. 19. Chen SS, Chen JF, Johnson PF, Muppala V, Lee YH. C/EBP, when expressed from the C/ebp gene locus, can functionally replace C/EBP in liver but not in adipose tissue. Mol Cell Biol. 2000;20:7292-7299[Abstract/Free Full Text]. 20. Foster HL, Small JD, Fox JG. The Mouse in Biomedical Research. New York, NY: Academic Press; 1983:302-307. 21. Radomska HS, Huettner CS, Zhang PU, Cheng T, Scadden DT, Tenen DG. CCAAT/enhancer binding protein  is a regulatory switch sufficient for induction of granulocytic development from bipotential myeloid progenitors. Mol Cell Biol. 1998;18:4301-4314[Abstract/Free Full Text]. 22. Pevny L, Simon M, Robertson E, et al. Erythroid differentiation in chimaeric mice blocked by a targeted mutation in the gene for transcription factor GATA-1. Nature. 1991;349:257-260[CrossRef][Medline] [Order article via Infotrieve]. 23. Simon M, Pevny L, Wiles M, Keller G, Costantini F, Orkin S. Rescue of erythroid development in gene targeted GATA-1 mouse embryonic stem cells. Nat Genet. 1992;1:92-98[CrossRef][Medline] [Order article via Infotrieve]. 24. Briegel K, Lim KC, Plank C, Beug H, Engel J, Zenke M. Ectopic expression of a conditional GATA-2/estrogen receptor chimera arrests erythroid differentiation in a hormone-dependent manner. Genes Dev. 1993;7:1097-1109[Abstract/Free Full Text]. 25. Tsai FY, Keller G, Kuo FC, et al. An early haematopoietic defect in mice lacking the transcription factor GATA-2. Nature. 1994;371:221-226[CrossRef][Medline] [Order article via Infotrieve]. 26. Clarke M, Kukowska-Latallo J, Westin E, Smith M, Prochownik E. Constitutive expression of a c-myb cDNA blocks Friend murine erythroleukemia cell differentiation. Mol Cell Biol. 1988;8:884-892[Abstract/Free Full Text]. 27. Gewirtz A, Calabretta B. A c-myb antisense oligodeoxynucleotide inhibits normal human hematopoiesis in vitro. Science. 1988;242:1303-1306[Abstract/Free Full Text]. 28. Graf T. Myb: a transcriptional activator linking proliferation and differentiation in hematopoietic cells. Curr Opin Genet Dev. 1992;2:249-255[CrossRef][Medline] [Order article via Infotrieve]. 29. Chen H, Zhang P, Voso M, et al. Neutrophils and monocytes express high levels of PU.1 (Spi-1) but not Spi-B. Blood. 1995;85:2918-2928[Abstract/Free Full Text]. 30. Klemsz M, McKercher S, Celada A, Beveren CV, Maki R. The macrophage and B cell-specific transcription factor PU.1 is related to the ets oncogene. Cell. 1990;61:113-124[CrossRef][Medline] [Order article via Infotrieve]. 31. Wotton D, Ghysdael J, Wang S, Speck N, Owen M. Cooperative binding of Ets-1 and core binding factor to DNA. Mol Cell Biol. 1994;14:840-850[Abstract/Free Full Text]. 32. Miyoshi H, Ohira M, Shimizu K, et al. Alternative splicing and genomic structure of the AML1 gene involved in acute myeloid leukemia. Nucleic Acids Res. 1995;23:2762-2769[Abstract/Free Full Text]. 33. Takahashi A, Satake M, Yamaguchi-Iwai Y, et al. Positive and negative regulation of granulocyte macrophage colony-stimulating factor promoter activity by AML1-related transcription factor, PEBP2. Blood. 1995;86:607-616[Abstract/Free Full Text]. 34. Tanaka T, Tanaka K, Ogawa S, et al. An acute myeloid leukemia gene, AML1, regulates hematopoietic myeloid cell differentiation and transcriptional activation antagonistically by two alternative spliced forms. EMBO J. 1995;14:341-350[Medline] [Order article via Infotrieve]. 35. Willams SC, Cantwell CA, Johnson PF. A family of C/EBP-related proteins capable of forming covalently linked leucine zipper dimers in vitro. Genes Dev. 1991;9:1553-1567. 36. Smith LT, Hohaus S, Gonzalez DA, Dziennis SE, Tenen DG. PU.1 (Spi-1) and C/EBP regulate the granulocyte colony-stimulating factor receptor promoter in myeloid cells. Blood. 1996;88:1234-1247[Abstract/Free Full Text]. 37. Zhang P, Iwama A, Datta MW, Darlington GJ, Link DC, Tenen DG. Upregulation of interleukin 6 and granulocyte colony-stimulating factor receptors by transcription factor CCAAT enhancer binding protein (C/EBP) is critical for granulopoiesis. J Exp Med. 1998;6:1173-1184. 38. Ford AM, Bennett CA, Healy LE, Towatari M, Greaves MF, Enver T. Regulation of the myeloperoxidase enhancer binding proteins PU.1, C/EBP, , and  during granulocytic-lineage specification. Proc Natl Acad Sci U S A. 1996;93:10838-10843[Abstract/Free Full Text]. 39. Oelgeschlager M, Nuchprayoon I, Luscher B, Friedman AD. C/EBP, c-Myb, and PU.1 cooperate to regulate the neutrophil elastase promoter. 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