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NEOPLASIA
From the Harvard Institutes of Medicine,
Harvard Medical School, Boston, MA; the Department of Internal
Medicine, Kumamoto University, Japan; the Department of Viral Oncology,
Institute for Virus Research, Kyoto University, Kyoto, Japan; the
Department of Medicine and Medical Biophysics, University of Toronto,
Canada; the Department of Medicine III, Grosshadern, Clinical
Cooperative Group Acute Myeloid Leukemia of the National Research
Center for Environment and Health (GSF), Munich, Germany.
The transcription factor PU.1 is required for normal blood cell
development. PU.1 regulates the expression of a number of crucial
myeloid genes, such as the macrophage colony-stimulating factor
(M-CSF) receptor, the granulocyte colony-stimulating factor (G-CSF) receptor, and the granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor. Myeloid cells derived from
PU.1 Although a number of oncogenes that affect
proliferation and cell death have been identified in leukemias, only a
few differentiation genes, such as AML1 or C/EBP The transcription factor PU.1 represents a unique transcriptional
regulator within the hematopoietic system.3,4 PU.1 is a
member of the Ets transcription family and is predominantly expressed
in hematopoietic cells.11-14 Ets factors contain a
characteristic DNA-binding domain of approximately 80 amino
acids.15 The PU.1 protein consists of 264 amino acids,
with the DNA-binding domain located in the carboxyl terminal part of
the protein, whereas the amino terminus contains the activation
domain.16 PU.1 is required for the proper generation of
both myeloid (macrophages and neutrophils) and lymphoid lineages (B-
and T- lymphocytes).14,17,18 PU.1 regulates the expression
of a number of myeloid genes, such as CD11b, the macrophage
colony-stimulating factor (M-CSF) receptor, the granulocyte
colony-stimulating factor (G-CSF) receptor, and the
granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor.19-24 PU.1 Patients
Mutational analysis
Plasmids PU.1 wild-type and mutants were subcloned between the BamHI and EcoRI sites of the pcDNA3 expression vector, and a FLAG sequence (ATG GAC TAC AAA GAC GAT GAC GAC AAG) was added in frame at the 5' end. PU.1 wild-type and the mutant G208fsX were fused in frame at the carboxyl end to the ligand-binding domain of the estrogen receptor alpha (ER ) in the
retroviral pBabePuro vector.30 As a control, the ER
sequence alone was also subcloned into the pBabePuro vector.
Immunoblotting Cells were lysed in RIPA buffer, and protein extracts were fractionated on 12% sodium dodecyl sulfate (SDS)-polyacrylamide gels and transferred to nitrocellulose membranes by electroblotting. PU.1 was detected with rabbit anti-rat PU.1 polyclonal serum (1:500; Santa Cruz Biotechnology, Santa Cruz, CA, catalog #sc-352) followed by an anti-rabbit IgG-horseradish peroxidase (HRP)-conjugated secondary antibody (Santa Cruz, catalog #sc-2004). A monoclonal FLAG-M2 antibody (Sigma, St Louis, MO, catalog #F-3165) was used at a concentration of 10 µg/mL and detected with an anti-mouse IgG-HRP-conjugated secondary antibody (Santa Cruz, catalog #sc-2055). A monoclonal anti-mouse -tubulin antibody served as a loading control (Boehringer
Mannheim, Indianapolis, IN, catalog #1111876) and was detected
with an anti-mouse IgG-HRP-conjugated secondary antibody (Santa Cruz,
catalog #sc-2005).
Electrophoretic mobility shift assay Nuclear extracts were prepared after lysing cells with a small-gauge syringe as previously described.31,32 The M-CSF receptor promoter oligonucleotide (base pair [bp] 53 to 36
containing the PU.1 binding site) had the sequence
5'-TAAAAGGGGAAGAAGAGG-3'.20 For supershift experiments, 2 µl of PU.1 polyclonal rabbit serum were added using either a
commercially available PU.1 antibody (Santa Cruz, catalog #sc-352X)
directed against amino acids 251 to 271 of the murine PU.1 protein or
an antiserum directed against the amino terminus of the PU.1
protein.19
Flow cytometry 1 × 105 cells were incubated with 2 µL of phycoerythrin (PE)-conjugated mouse anti-human monoclonal CD11b antibody (PharMingen, San Diego, CA, catalog #30455X) or isotype control and analyzed on a FACScan flow cytometer (Becton Dickinson, Mountain View, CA) using Cellquest software. Human recombinant G-CSF (Pharmacia) was biotinylated using N-hydrosuccinimide ester (NHS-LC)-biotin (Pierce, Rockford, IL) following the manufacturer's procedure and utilized to measure G-CSF receptor levels as previously described.33Transient transfections NIH-3T3 cells at 70% confluency were transfected using Superfect Transfection Reagent (Qiagen) with 1 µg of PU.1 reporter plasmid with either wild-type or mutant PU.1 sites inserted into the promoterless luciferase vector pXP2,34,35 500 ng of expression vector, and 100 ng of cytomegalovirus (CMV)-LacZ construct. For experiments including PU.1 expression vectors, either 500 ng of a single PU.1 allele or 250 ng each of 2 PU.1 alleles were transfected. Luciferase activities were normalized for transfection efficiency with the cotransfected CMV-LacZ construct, using a chemiluminescent reporter gene assay for-galactosidase
(Tropix, Foster City, CA). F9 cells were transfected as
described previously.35 All transfection experiments were
repeated 3 times with different preparations of each plasmid. Equal
expression levels of PU.1 derivatives in transfected cells were
confirmed by Western blotting.
In vitro protein-protein binding assays Glutathione-S-transferase (GST) pull-down assays were performed as previously described.36 All GST proteins were quantitated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Coomassie blue staining. [35]S-methionine-labeled proteins were prepared using 1 µg of plasmid DNA as template for coupled in vitro transcription-translation (TNT; Promega, Madison, WI). For the in vitro binding assays, equal amounts of all GST proteins were incubated with 2 µL of [35]S-methionine-labeled proteins. The bead volume of all samples was adjusted to 50 µL with GST beads alone. Bound proteins were resolved on 10% SDS-PAGE gels and autoradiography, and the percentage of in vitro translated protein complexed with GST fusion proteins on beads was calculated with a phosphorimager (Molecular Dynamics, Sunnyvale, CA).Cell lines with conditional PU.1 expression Phoenix cells, a human packaging cell line,37 were transiently transfected with either the pBabePuro-estrogen receptor (ER) vector alone, the pBabePuro-PU.1 wild-type-ER, or the pBabePuro-PU.1 G208fsX mutant-ER plasmid using lipofectamine (Gibco BRL, Grand Island, NY). Supernatant containing viral particles was harvested after 4 days. PU.1 / cells (line
50324) were incubated in 4 mL of viral supernatant and 5 µg/mL of polybrene for 4 hours. A second infection cycle was
performed after 24 hours. PU.1/ cells were then grown
in 96-well plates, and selection was started 48 hours after the first
infection cycle in 0.5 µg/mL of puromycin. Clones were screened for
the presence of the PU.1 fusion gene by Western blot analysis using
PU.1 and/or FLAG antibody.
Detection of heterozygous mutations of the transcription factor PU.1 in AML The entire coding region of the PU.1 gene was amplified by PCR using cDNA (99 patients) or genomic DNA (27 patients). PCR products were directly sequenced to screen for mutations. FAB subtypes of the patients are shown in Table 2, and the karyotypes are described in Table 3. Of the 126 AML patients, 9 demonstrated at least one mutation of the PU.1 gene (7%). Subcloning of PCR products revealed that the wild-type sequence was present in all samples with PU.1 mutations, with the exception of patients #54 and #70. Since the percentage of wild-type clones was approximately 50% (ranging from 33% to 71%; Table 3), we therefore conclude that PU.1 mutations in AML patients generally are heterozygous.
We detected PU.1 mutations in the myelomonocytic or monocytic subtypes (M4, M5), in undifferentiated (M0) AML, and in one patient with erythroleukemia. One patient (#68) was originally diagnosed as M4, and subsequently reclassified as M1. However, no mutation was observed in 34 AML patients of the granulocytic lineage with the phenotypes M2 (23 patients) or M3 (11 patients). Karyotype analysis revealed that PU.1 mutations were not observed
in the 10 M4 patients with inv(16), the 3 M2 patients with the t(8;21)
AML1/ETO translocation, or in 11 M3 patients with the
PML-RAR To assess the possibility that the abnormal PU.1 sequences detected in some AML patients represented polymorphisms, we sequenced DNA from peripheral blood leukocytes of 43 healthy volunteers, and we did not detect any abnormalities in the coding region of PU.1. In addition, where possible we analyzed cells from patients with PU.1 mutations at remission to distinguish between germ-line or sporadic mutations. We obtained paraffin-embedded material at remission from one patient (#109); in this remission sample, we did not detect the Q210H mutation observed in the blasts of this AML patient at diagnosis. In a second patient (#104), we established Epstein-Barr virus (EBV)-immortalized B-cell lines and found only PU.1 wild-type sequences could be detected. We therefore conclude that the sequence variations observed in AML patients likely represent mutations rather than polymorphisms. Molecular anatomy of the PU.1 mutations The 10 mutations in the coding region of PU.1 comprised 5 deletions and 5 point mutations. Further details and the precise location of the mutations are presented in Table 3. There is no defined region with a strikingly increased frequency for mutational events. In the M0/M4/M5 patients, 8 of the 9 mutations occurred either in the PEST domain (between amino acids 105 and 150) or in the DNA-binding domain (between amino acids 208 and 254).Frame shift mutations in the PEST domain We identified 2 AML-M0 patients with deletions in the PEST domain that caused a frame shift (#57: P136fsX179 and #104: V105-H264del) with consequent loss of parts of the PEST domain and of the entire DNA-binding domain (Figure 1). Since these deletions involved the entire DNA-binding domain, we predicted that binding of these peptides to PU.1 target gene promoters would be abolished. Thus, the effect of these 2 mutations likely results in a significant decrease in the amount of functional PU.1 protein in a particular leukemic cell. To support this hypothesis, we were fortunate to obtain cells at diagnosis from one of these 2 patients (#104: V105-H264del) whose mutation was confirmed in both a cDNA sample and in genomic DNA. We determined that the amount of wild-type PU.1 protein in leukemic cells from this AML-M0 patient (#104) is reduced by at least 50% as compared to other AML-M0 patients without PU.1 mutations (#97 or #103 in Figure 2). We therefore confirmed that this mutation led to a significant decrease in the amount of functional PU.1 protein in leukemic cells of patient #104. Such a decrease in functional PU.1 protein may contribute to the early block in differentiation observed in malignant cells of this particular AML-M0 patient.
Mutations in the Ets domain of PU.1 PU.1 acts as a transactivator that requires coactivators to achieve potent activation function through physical interactions.35,38-40 The carboxyl terminus of the PU.1 Ets-homology domain is a winged helix-turn-helix (wHTH) motif that serves as a DNA-binding domain.41 The Ets domain of PU.1 has also been found to physically interact with many proteins, including the negative regulator GATA-1.39,42-44 We recently demonstrated that it is the3/4 region (amino acids 243-254) of PU.1, downstream of the wHTH motif, that mediates the
interaction with a number of myeloid regulators including c-Jun, AML1B,
and C/EBP.28,35,39
We identified 3 patients with heterozygous mutations in the Ets
domain of PU.1. One patient (#70) had a different mutation in each
allele, both of which affected the
We next tested the ability of these 2 mutants to synergistically
activate the M-CSF receptor together with AML1,28 a
function that has been attributed to the The #68 mutant G208fsX Whereas the deletion mutation of #70 (G253fsX) caused a loss of parts of the3/4 region in the Ets domain, the frame shift mutation of #68 (G208fsX) disrupted the entire wHTH motif and the
3/4 region (Figure 4A). Despite this deletion, the G208fsX mutant
encoded a stable protein (Figure 3B). We predicted that DNA binding
would be affected, and indeed no DNA-binding activity to the M-CSF
receptor promoter oligonucleotide was observed for the G208fsX mutant
(Figure 4C). Consequently, this mutant also failed to activate a M-CSF
receptor promoter construct in transient transfection assays (Figure
4D), consistent with its lack in DNA binding (Figure 4B). We next
tested the ability of this mutant to synergistically activate the M-CSF
receptor together with AML1 or c-Jun. Because G208fsX fails to
physically interact with AML1, and binds very weakly to c-Jun compared
to wild-type PU.1 (Figure 5), we
predicted that it might be defective in synergism with both factors.
The G208fsX mutant not only failed to synergize with AML1 (Figure 4C),
but it appeared to block AML1 function. Cotransfection of this mutant
together with AML1 results in luciferase activity that is only 36% of
what is observed with AML1 alone (Figure 4C). In addition, we observed
almost no synergy between the G208fsX mutant and c-Jun (Figure 4D). We
therefore conclude that this PU.1 mutation involving the 3/4
region negatively affects the coactivation of PU.1 by c-Jun.
PU.1 mutants involving the Many of the patients in this study had been previously analyzed for AML1 mutations.5 An H58N point mutation in the AML1 gene was detected in AML-M0 patient #57, which also harbored a heterozygous P136fsX179 mutation in PU.1. This AML1 mutation showed an increased transactivation potential of the M-CSF receptor.5 It is thus an interesting finding that this single patient harbored a "super-activating" mutation in AML1 and a mutation in PU.1 that abrogates interaction with wild-type AML1 (Figure 5) and most likely cannot synergize in activating target genes. As described above, we also studied synergistic effects between PU.1
and c-Jun.35 c-Jun does not directly bind to the M-CSF receptor promoter but associates via its basic domain with the Ets
domain of PU.1.35 Again, we used GST pull-down assays to test whether our mutants in the Ets domain, which do not
synergistically activate with c-Jun, have also lost the ability to
physically interact with c-Jun. As a control, we also tested the
ability of our mutant PU.1 proteins to interact with GATA-1, which
interacts with both the amino terminus and The G150R point mutation in the PEST domain in AML-M4/M5 patients We observed a G150R point mutation in the PEST domain of 2 AML patients. We did not detect this abnormality in DNA from 43 healthy volunteers. Unfortunately, no remission or nonleukemic material was available from these patients. Because this domain has been shown to mediate interaction with members of the interferon responsive factor (IRF) family, including IRF-4 and ICSBP,46-48 we hypothesized that the point mutation of amino acid 150 in these 2 AML patients (Figure 1) might affect IRF recruitment. However, the G150R mutant was still capable of properly binding to DNA, and both transactivation of the M-CSF receptor promoter and synergy with IRF family members in activating the interleukin (IL)-1 promoter was not significantly affected (data not shown). Furthermore, the G150R mutant protein was still capable of physically interacting with the interferon consensus sequence binding protein (ICSBP) in a manner similar to that of PU.1 wild-type in a GST pull-down assay
(data not shown). Therefore, the nature of the defect of the G150R
mutant, if any, remains unknown.
Loss of exons 3 to 5 in AML patients In one patient (#54), only a shortened splice variant and not the full-length PU.1 sequence could be identified using cDNA as a template (Figure 6). This variant deletes exons 3, 4, and much of exon 5. In this deletion, the sequence immediately following exon 2 derives from sequences 50 bp downstream of the translation stop codon in exon 5. Using genomic DNA from leukemic cells of this patient and exon-specific primers, we failed to amplify exons 3 to 5 by PCR (data not shown). We therefore believe that both alleles in this patient lack a large part of the wild-type sequence involving at least exons 3 to 5. Unfortunately, no material was available for confirmation by FISH analysis. No DNA binding to the M-CSF receptor oligonucleotide could be observed, and the potential to activate the M-CSF receptor promoter was completely abolished in transient transfection assays (data not shown). Loss of both alleles for the AML1 transcription factor has been previously described in patients with AML.7
Conditional expression of mutant G208fsX in PU.1 / cells represent early myeloid
precursors that can be induced to differentiate following transduction
with a retrovirus expressing the wild-type PU.1
protein.26,27 Therefore, we asked whether a PU.1 mutation
identified in AML patients had lost this potential. We transduced
PU.1/ cells with a retrovirus expressing either the
wild-type human PU.1-estrogen receptor fusion protein or the PU.1
mutant G208fsX estrogen receptor fusion protein (Figure
7A). Both constructs contained a FLAG
sequence at the amino terminus of PU.1. In the absence of estradiol,
the estrogen receptor (and thus the PU.1 protein fused to it) was
localized to the cytoplasm. Treatment of the cells with 1 mM estradiol
induced translocation of the PU.1-ER protein into the nucleus (data not
shown). Expression of wild-type PU.1 induced differentiation of
PU.1/ cells. CD11b is a PU.1 target gene19
that is up-regulated during myeloid differentiation.
PU.1/ cells expressing the PU.1-ER fusion showed a
dramatic increase in CD11b expression after 4 days of treatment with
estradiol (Figure 7B). In contrast, CD11b levels were unchanged after
treatment with estradiol in the parental PU.1/ cells.
In addition, we determined expression of the G-CSF receptor as a marker
for neutrophil differentiation.33 Again, PU.1-ER expressing PU.1/ cells demonstrated a marked increase
in G-CSF receptor expression, whereas the levels remained unchanged in
the parental line. Finally, Wright-Giemsa staining of
PU.1/ cells expressing the PU.1-ER fusion protein
before and 7 days after treatment with 1 mM -estradiol
demonstrated neutrophilic differentiation of immature myeloid blasts
(Figure 7C). We therefore confirmed that expression of PU.1 protein in
PU.1/ cells is sufficient to induce terminal
granulocytic differentiation in this system as described
previously.27 We also tested the G150R mutant using this
system and found that this mutant retained the ability to induce
neutrophil differentiation and activate PU.1 target genes (data
not shown).
Consequently, we tested the PU.1 mutant G208fsX, which deletes the last
56 amino acids of the PU.1 gene, including the
We report here for the first time mutations in the PU.1 gene in malignant cells isolated from patients with cancer. Screening 126 AML patients, we identified 9 with mutations in the coding region of the PU.1 gene. As assessed by conventional karyotype analysis, 5 of these patients had an otherwise normal karyotype. Thus, PU.1 mutations represent the only genomic abnormalities detected so far in these particular patients. Comprehensive clinical information was available for 6 of the 9 AML patients with PU.1 mutations and for 66 of the 117 AML patients with wild-type PU.1. Based on the relatively small numbers of patients, we found that patients with PU.1 mutations fared worse than patients without PU.1 mutations (median survival, 80 days and 364 days, respectively; with a complete remission achieved in 33% and 57%). These results suggest that the presence of PU.1 mutations carries a worse prognosis, but clearly additional studies with more patients will be required to answer this question in a definitive fashion. In addition, no mutations were observed in a collection of 24 patients with a good risk karyotype involving either the t(8;21) or the t(15;17) translocation, or inv(16). These results suggest that mutations in PU.1 might define a distinct subgroup of AML patients, and therefore detection of PU.1 mutations may be of possible prognostic importance in the future. What is the significance of these PU.1 mutations? Since we identified
mutant and wild-type alleles in cells from AML patients with PU.1
mutations, one hypothesis is that haploinsufficiency contributes to
leukemogenesis, as has been described for the AML1 transcription
factor.6 Support for this idea comes from a recent report
demonstrating that PU.1+/ An emerging concept from the role of transcription factors in
hematopoiesis is that not only are single factors of importance, but
rather combination of factors are
needed.3,4,28,29,35,39,50 We previously reported that PU.1
synergizes with its coactivator c-Jun, as well as with AML1, in
activating target genes such as the M-CSF receptor.28,35
In both instances, it is the Of note is the fact that we were able to identify mutations in PU.1
predominantly in very immature (M0) or monocytic (M4/M5) AML subgroups
(as described above), while we previously found such mutations in the
myeloid transcription factor C/EBP The human PU.1 gene is located at chromosome 11p11.22, which is not a
site of known chromosome translocations in leukemia.1,3 The PU.1 gene itself has never been reported to be a partner gene of a
chromosomal translocation. This is similar to other transcription factors such as C/EBP
We thank Christian Busse and Chris Hetherington for assistance with
the mutational analysis; Pu Zhang for biotinylated G-CSF; Bruce Torbett
for PU.1
Submitted November 13, 2001; accepted March 28, 2002.
Supported by grants from the Swiss National Science Foundation (81BS-52825) (B.U.M.) and the National Institutes of Health (grants CA41456 and CA72009) (D.G.T.).
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: Daniel G. Tenen, Harvard Institutes of Medicine, 77 Avenue Louis Pasteur, Rm 954, Boston, MA 02115; e-mail: dtenen{at}caregroup.harvard.edu.
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M. Papetti and A. I. Skoultchi Reprogramming Leukemia Cells to Terminal Differentiation and Growth Arrest by RNA Interference of PU.1 Mol. Cancer Res., October 1, 2007; 5(10): 1053 - 1062. [Abstract] [Full Text] [PDF]
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D. C. Link, G. Kunter, Y. Kasai, Y. Zhao, T. Miner, M. D. McLellan, R. E. Ries, D. Kapur, R. Nagarajan, D. C. Dale, et al. Distinct patterns of mutations occurring in de novo AML versus AML arising in the setting of severe congenital neutropenia Blood, September 1, 2007; 110(5): 1648 - 1655. [Abstract] [Full Text] [PDF]
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P. Wlodarski, Q. Zhang, X. Liu, M. Kasprzycka, M. Marzec, and M. A. Wasik PU.1 Activates Transcription of SHP-1 Gene in Hematopoietic Cells J. Biol. Chem., March 2, 2007; 282(9): 6316 - 6323. [Abstract] [Full Text] [PDF]
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M. J. Walter, R. E. Ries, J. R. Armstrong, J. S. Park, E. R. Mardis, and T. J. Ley Expression of a bcr-1 isoform of RAR{alpha}-PML does not affect the penetrance of acute promyelocytic leukemia or the acquisition of an interstitial deletion on mouse chromosome 2 Blood, February 1, 2007; 109(3): 1237 - 1240. [Abstract] [Full Text] [PDF]
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W. Cook Is PU.1 pivotal to APL? Blood, April 15, 2006; 107(8): 3017 - 3018. [Full Text] [PDF]
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B. U. Mueller, T. Pabst, J. Fos, V. Petkovic, M. F. Fey, N. Asou, U. Buergi, and D. G. Tenen ATRA resolves the differentiation block in t(15;17) acute myeloid leukemia by restoring PU.1 expression Blood, April 15, 2006; 107(8): 3330 - 3338. [Abstract] [Full Text] [PDF]
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D. Metcalf, A. Dakic, S. Mifsud, L. Di Rago, L. Wu, and S. Nutt Inactivation of PU.1 in adult mice leads to the development of myeloid leukemia PNAS, January 31, 2006; 103(5): 1486 - 1491. [Abstract] [Full Text] [PDF]
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Y. Du, S. E. Spence, N. A. Jenkins, and N. G. Copeland Cooperating cancer-gene identification through oncogenic-retrovirus-induced insertional mutagenesis Blood, October 1, 2005; 106(7): 2498 - 2505. [Abstract] [Full Text] [PDF]
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F. Rosenbauer, S. Koschmieder, U. Steidl, and D. G. Tenen Effect of transcription-factor concentrations on leukemic stem cells Blood, September 1, 2005; 106(5): 1519 - 1524. [Abstract] [Full Text] [PDF]
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H. Iwasaki, C. Somoza, H. Shigematsu, E. A. Duprez, J. Iwasaki-Arai, S.-i. Mizuno, Y. Arinobu, K. Geary, P. Zhang, T. Dayaram, et al. Distinctive and indispensable roles of PU.1 in maintenance of hematopoietic stem cells and their differentiation Blood, September 1, 2005; 106(5): 1590 - 1600. [Abstract] [Full Text] [PDF]
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M. J. Walter, J. S. Park, R. E. Ries, S. K. M. Lau, M. McLellan, S. Jaeger, R. K. Wilson, E. R. Mardis, and T. J. Ley Reduced PU.1 expression causes myeloid progenitor expansion and increased leukemia penetrance in mice expressing PML-RAR{alpha} PNAS, August 30, 2005; 102(35): 12513 - 12518. [Abstract] [Full Text] [PDF]
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G. Yang, W. Khalaf, L. van de Locht, J. H. Jansen, M. Gao, M. A. Thompson, B. A. van der Reijden, D. H. Gutmann, R. Delwel, D. W. Clapp, et al. Transcriptional Repression of the Neurofibromatosis-1 Tumor Suppressor by the t(8;21) Fusion Protein Mol. Cell. Biol., July 15, 2005; 25(14): 5869 - 5879. [Abstract] [Full Text] [PDF]
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 B. T. Porse, D. Bryder, K. Theilgaard-Monch, M. S. Hasemann, K. Anderson, I. Damgaard, S. E. W. Jacobsen, and C. Nerlov Loss of C/EBP{alpha} cell cycle control increases myeloid progenitor proliferation and transforms the neutrophil granulocyte lineage J. Exp. Med., July 5, 2005; 202(1): 85 - 96. [Abstract] [Full Text] [PDF]
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H. Zhong, A. Takeda, R. Nazari, H. Shio, G. Blobel, and N. R. Yaseen Carrier-independent Nuclear Import of the Transcription Factor PU.1 via RanGTP-stimulated Binding to Nup153 J. Biol. Chem., March 18, 2005; 280(11): 10675 - 10682. [Abstract] [Full Text] [PDF]
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S. L. Nutt, D. Metcalf, A. D'Amico, M. Polli, and L. Wu Dynamic regulation of PU.1 expression in multipotent hematopoietic progenitors J. Exp. Med., January 18, 2005; 201(2): 221 - 231. [Abstract] [Full Text] [PDF]
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W. D. Cook, B. J. McCaw, C. Herring, D. L. John, S. J. Foote, S. L. Nutt, and J. M. Adams PU.1 is a suppressor of myeloid leukemia, inactivated in mice by gene deletion and mutation of its DNA binding domain Blood, December 1, 2004; 104(12): 3437 - 3444. [Abstract] [Full Text] [PDF]
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F. Rosenbauer, K. Wagner, P. Zhang, K.-P. Knobeloch, A. Iwama, and D. G. Tenen pDP4, a novel glycoprotein secreted by mature granulocytes, is regulated by transcription factor PU.1 Blood, June 1, 2004; 103(11): 4294 - 4301. [Abstract] [Full Text] [PDF]
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J. W. Lee, H. Y. Chung, L. A. Ehrlich, D. F. Jelinek, N. S. Callander, G. D. Roodman, and S. J. Choi IL-3 expression by myeloma cells increases both osteoclast formation and growth of myeloma cells Blood, March 15, 2004; 103(6): 2308 - 2315. [Abstract] [Full Text] [PDF]
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R. Zheng, A. D. Friedman, M. Levis, L. Li, E. G. Weir, and D. Small Internal tandem duplication mutation of FLT3 blocks myeloid differentiation through suppression of C/EBP{alpha} expression Blood, March 1, 2004; 103(5): 1883 - 1890. [Abstract] [Full Text] [PDF]
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T. J. Ley, P. J. Minx, M. J. Walter, R. E. Ries, H. Sun, M. McLellan, J. F. DiPersio, D. C. Link, M. H. Tomasson, T. A. Graubert, et al. A pilot study of high-throughput, sequence-based mutational profiling of primary human acute myeloid leukemia cell genomes PNAS, November 25, 2003; 100(24): 14275 - 14280. [Abstract] [Full Text] [PDF]
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K. Dohner, K. Tobis, T. Bischof, S. Hein, R. F. Schlenk, S. Frohling, H. Dohner, B. U. Mueller, T. Pabst, M. Osato, et al. Mutation analysis of the transcription factor PU.1 in younger adults (16 to 60 years) with acute myeloid leukemia: a study of the AML Study Group Ulm (AMLSG ULM) Blood, November 15, 2003; 102(10): 3850 - 3851. [Full Text] [PDF]
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K. S. Choe, F. Radparvar, I. Matushansky, N. Rekhtman, X. Han, and A. I. Skoultchi Reversal of Tumorigenicity and the Block to Differentiation in Erythroleukemia Cells by GATA-1 Cancer Res., October 1, 2003; 63(19): 6363 - 6369. [Abstract] [Full Text] [PDF]
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 T. Kummalue and A. D. Friedman Cross-talk between regulators of myeloid development: C/EBP{alpha} binds and activates the promoter of the PU.1 gene J. Leukoc. Biol., September 1, 2003; 74(3): 464 - 470. [Abstract] [Full Text] [PDF]
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B. U. Mueller, T. Pabst, M. Osato, N. Asou, L. M. Johansen, M. D. Minden, G. Behre, W. Hiddemann, Y. Ito, and D. G. Tenen Heterozygous PU.1 mutations are associated with acute myeloid leukemia Blood, March 1, 2003; 101(5): 2074 - 2074. [Full Text] [PDF]
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R. K. Vangala, M. S. Heiss-Neumann, J. S. Rangatia, S. M. Singh, C. Schoch, D. G. Tenen, W. Hiddemann, and G. Behre The myeloid master regulator transcription factor PU.1 is inactivated by AML1-ETO in t(8;21) myeloid leukemia Blood, January 1, 2003; 101(1): 270 - 277. [Abstract] [Full Text] [PDF]
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C. Lamandin, C. Sagot, C. Roumier, P. Lepelley, S. De Botton, A. Cosson, P. Fenaux, and C. Preudhomme Are PU.1 mutations frequent genetic events in acute myeloid leukemia (AML)? Blood, December 15, 2002; 100(13): 4680 - 4680. [Full Text] [PDF]
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Abstract
Introduction
