From the Laboratory of Molecular Cell Biology, The Rockefeller University, New York, New York 10021
Received for publication, December 23, 2002, and in revised form, February 23, 2003
![]() |
ABSTRACT |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The c-fos gene was one of the
earliest vertebrate genes shown to be transcriptionally induced by
growth factors. Intensive study of the promoter of c-fos
( The c-fos proto-oncogene encodes a basic leucine zipper
transcription factor, the gene of which is activated transcriptionally in response to a wide range of extracellular stimuli including mitogenic growth factors (1, 2). c-fos was one of the
founding members of the "immediate early" response genes and was
shown by run-on transcription analysis to be stimulated promptly but briefly at the transcriptional level (1, 3). Because of this initial
characterization, the c-fos promoter has been extensively studied, and binding sites for several DNA binding factors have been determined to lie between This basic framework was expanded by the discovery of several other
binding sites, some of which participate in the regulation of the
transfected c-fos promoter through other signaling
mechanisms. These mechanisms include a direct repeat element, a
sis-inducible element (SIE) that can bind to the STATs, two
TFII-I sites, and at least two cAMP-response element/AP-1-type sites
that effect responses to extracellular signaling proteins through
serine phosphorylation cascades (11-14). Histone modification of the
chromatin substrate for chromosomal c-fos activation has
been described recently (15, 16), but the assembly of resident nuclear
proteins on the c-fos promoter during gene activation has not.
No firm conclusion has been reached about the importance of the SIE to
the regulation of the chromosomal c-fos locus, which raises doubts about any role of the STATs in regulating
c-fos transcription. On the one hand, the SIE is conserved
across species (17), and in vivo footprinting has
demonstrated SIE protection within 20 min of epidermal growth factor
(EGF) stimulation (10). In an electrophoretic mobility shift assay
(EMSA), the SIE site can clearly bind to STAT proteins that have been
activated by treatment with platelet-derived growth factor and EGF,
among other cytokines (18, 19), and reporter constructs bearing the SIE confer transient platelet-derived growth factor inducibility in the
absence of the serum response element (13, 18). Also, mutations
of this site in transiently expressed as well as stably integrated
reporter constructs impair transcriptional responses not only to
sis/platelet-derived growth factor but also to TPA and serum
(4, 20).
However, other investigators have discounted the importance of STAT
regulation. For example, deletion of the SIE from a luciferase construct including the TCF/serum response element/AP-1 sites failed to
have any impact on EGF inducibility during the transfection of cultured
HeLa cells (21). In addition, the discovery of an overlapping TFII-I
site that is required for serum induction of c-fos (Fig.
1) has raised some doubts about whether
the previously characterized mutations in the SIE site were the result
of a loss of STAT or TFII-I function (14). Moreover the SIE does not
resemble an optimal STAT-binding site (13, 22, 23). However, all of
these transcription studies were not definitive for the native chromosomal c-fos gene. Also, the stimuli used
(e.g. growth hormone or EGF) have a very significant MAP
kinase component that is known to be a potent stimulus on its own
(e.g. TPA treatment) (22, 23). Therefore the extent to which
STAT activity alone or in combination contributes to the regulation of
the chromosomal gene has remained unclear.
325 to
80) by transient or permanent transfections of synthetic
DNA constructs has repeatedly shown the importance of several sequence
elements and the resident nuclear proteins that bind them
(e.g. ternary complex factor/ELK1; serum response factor,
cAMP response element-binding protein/amino-terminal fragment/AP-1). However these studies have left unanswered
numerous questions about the role of these proteins in the regulation
of the native chromosomal gene. In particular, the role of a site in
this enhancer that binds STATs has been controversial. We present evidence here that STAT3 and not STAT1 accumulates on the chromosomal c-fos promoter and provides a boost to transcription
without the activation of resident nuclear proteins through serine
kinases. Also, when resident nuclear proteins such as ELK1 are
activated to varying extents by mitogen-activated protein kinase
pathways, STAT3 activation provides a 2-fold boost regardless of the
final level of activated transcription. Thus the several proteins that interact with the c-fos enhancer apparently can act either
in a cooperative or independent manner to achieve very different levels
of transcription.
INTRODUCTION
TOP
ABSTRACT
INTRODUCTION
EXPERIMENTAL PROCEDURES
RESULTS
DISCUSSION
REFERENCES
325 and
60 upstream of the
c-fos start site (4). Of particular note, the transfection
of wild type and mutant c-fos promoter constructs has
demonstrated the critical importance of the Ets and serum
response elements at
320 (see Fig. 1). The Ets site is bound by
ternary complex factors (TCFs),1 Ets family members
(i.e. ELK1, SAP1a/b, or SAP2) that are subject to inducible
serine phosphorylation (4-7). In the case of ELK1, extracellular
ligands stimulate mitogen-activated protein kinase phosphorylation of
serine 383, leading to tighter association with serum response factor
homodimers constitutively bound to the serum response element and to
increased rates of transcription (8-10).
View larger version (20K):
[in a new window]
Fig. 1.
Diagram of the human c-fos
promoter. A, locations of regulatory sites in the
c-fos promoter with indicated 5' boundary (adapted from
Refs. 11, 14, and 21). The asterisks indicate the site
mutated in reporter studies. DR, direct repeat element.
B, sequence of mutant constructs used in this study ( 352
to
293 region of promoter).
In this series of experiments, we have examined chromosomal
c-fos transcription by STAT3 in the absence of detectable
STAT1 or MAP kinase activity. We find that STAT3 activation alone
induces c-fos mRNA accumulation. Chromatin
immunoprecipitation shows that STAT3 but not STAT1 can accumulate at
the c-fos promoter. This selectivity in chromatin
accumulation is not the result of differences in DNA-binding
preferences that are evident in in vitro DNA-binding assays,
and it is presumably the result of STAT3 interaction with other nuclear
proteins that are known to be on the promoter. Finally, we show that
although the STAT3-associated induction of c-fos in response
to human interleukin-6 (IL-6) is much weaker on its own than when
induction is brought about by TPA or EGF stimulation, it
maximizes the transcriptional response to either of these stimuli.
![]() |
EXPERIMENTAL PROCEDURES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Cell Culture and Antibodies-- HepG2 cells were obtained from ATCC and grown in Eagle's modified essential medium (with nonessential amino acids, Earle's salts, 2 mM L-glutamine, 1.5 g/liter sodium bicarbonate, and 1 mM sodium pyruvate) supplemented with penicillin/streptomycin (Invitrogen) and 10% fetal bovine serum (Hyclone). Before all experiments, cells were serum-starved overnight with minimum Eagle's medium containing 0.2% fetal bovine serum. Whole and fractionated cell extracts were prepared as described previously (24). Unless otherwise stated, recombinant IL-6 (R&D Systems) was used at a concentration of 2.5 ng/ml final concentration. 12-O-tetradecanoyphorbol-13-acetate (TPA, Sigma) was resuspended in Me2SO and used at a 100 ng/ml final concentration. Recombinant human epidermal growth factor (EGF, Calbiochem) was used at a 100 ng/ml final concentration. Kinase inhibitors were used at 50 µM for PD098059 (MEK1 inhibitor) and 2 µM for SB203580 (p38 inhibitor). Inhibitors were added 10-15 min before stimulation with cytokine or TPA. Durations of treatments were as stated in the text. Phosphospecific antibodies for pS727-STAT3, pY705-STAT3, pT202pY204-ERK1/2 monoclonal antibody, pT183pY185-JNK, and pT180pY182-p38 were obtained from Cell Signaling and used at a 1:1000 dilution for Western blotting. Antibodies to the STAT1 C terminus, STAT3 C terminus, ELK1, and pS383-ELK1 were obtained from Santa Cruz Biotechnology.
Electrophoretic Mobility Shift Assay--
EMSAs were performed
as described previously (24, 25). Blunt-ended EMSA probes were
phosphorylated by polynucleotide kinase in the presence of
[-32P]ATP to approximately the same specific activity.
The sequences for the oligonucleotide probes were (sense strand): SIE,
5'-GAGCAGTTCCCGTCAATCCCT-3'; and m67,
5'-GAGCATTTCCCGTAAATCCCT-3'.
Chromatin Immunoprecipitation--
Formaldehyde fixation,
chromatin breakage, antibody precipitation protocols, and PCR
conditions were described previously (25). The following antibodies
were used for precipitation: pS383 ELK1 monoclonal antibody, STAT3
C-terminal polyclonal antibody, and STAT1 C-terminal polyclonal
antibody (all from Santa Cruz Biotechnology). In the case of
precipitation with monoclonal antibody, a protein A/G resin (Gamma
Bind, Amersham Biosciences) was added in addition to the normal
protein A, which was sheared salmon sperm slurry. The PCR
primers used for the analysis of the c-fos promoter,
which spanned 363 to
163 upstream of the c-fos
transcription start site: CHFOSU, 5'-GCAGCCCGCGAGCAGTT-3'; and
CHFOSL, 5'-GCCTTGGCGCGTGTCCTAATC-3'.
Reverse Transcriptase Polymerase Chain Reaction-- The RT-PCR protocol and primers for human IRF-1 and GAPDH were reported previously (24). Primers for c-fos, junB, and SOCS3 were: FOSU, 5'-AACCGGAGGAGGGAGCTGACTGAT-3' and FOSL 5'-GGGCCTGGATGATGCTGGGAACA-3'; JUNBU, 5'-CGGCGGTGGCGGCAGCTACTTTTC-3' and JUNBL, 5'-GGGGGTGTCACGTGGTTCATCTTG-3'; and SSI3U, 5'-ACCACTACATGCCGCCCCCTGGAG-3' and SSI3L, 5'-CCCCGGCAGCTGGGTGACTTTCTC-3'. For all samples, no detectable GAPDH amplification was detected before reverse transcription. Although 25 PCR cycles were used for the detection of any given transcript, the amount of input cDNA used was varied (see Fig. 6).
Reporter Gene Analysis--
A luciferase reporter construct
described previously and bearing 711 to +45 of the human
c-fos promoter (26) was used as a template for QuikChange
site-directed mutagenesis (Stratagene). The following mutants were
generated (wild type
mutant underlined): GAS-KO
5'-TTCCCGTCAA-3'
5'-CTCGAGTCAA-3'; M67/TFII-I KO
5'-TTCCCGTCAA-3'
5'-TTCCCGTAAA-3'; AP1-KO
5'-TCTGCGTCA-3'
5'-TCGCCGGCA-3'. Mutations were
evaluated for selective removal of original binding site without
detectable introduction of new sites by
TRANSFAC.2 All clones used
for reporter analysis were sequenced over the length of the promoter.
Transfections were performed in six-well plates with 3 µl of
Fugene (Roche Applied Science) and 1 µg of DNA (66 ng of
reporter plasmid, 333 ng of cytomegalovirus-enhanced green
fluorescent protein, 222 ng of cytomegalovirus-
- galactosidase, and
377 ng of RC/cytomegalovirus expression plasmid)/well. After a 4-h
transfection, cells were allowed to recover for 18-24 h and then
starved for 15-18 h in a low serum (0.2% fetal calf serum) medium. Cells were then activated in duplicate with IL-6 for
3.5 h, TPA for 3 h, IL-6 for 0.5 h followed by TPA for
3 h, or left untreated. Luciferase assays were performed according
to manufacturer directions (Promega). Because conditions that activate
c-fos were found to also markedly and consistently increase
- galactosidase expression, the average
- galactosidase activity
for the two untreated samples was used to normalize the transfections.
The error bars represent half of the difference
between duplicate measurements.
![]() |
RESULTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Mitogen-activated Protein Kinases and STATs Can Be Activated
Separately in HepG2 Cells--
Previous studies of STAT
activation of the c-fos promoter have often made use of
ligands for receptor tyrosine kinases that activate several signaling
pathways in addition to the STATs (1-7; see the Introduction).
Therefore the strong activation of the c-fos promoter by MAP
kinases might obscure the impact of the STATs on the regulation of this
locus. Furthermore, many ligands activate both STAT1 and STAT3. We
dissected the contribution of different STATs from each other and from
MAP kinases by using IL-6 at low concentrations that activated STAT3
preferentially to STAT1 (Fig.
2A); 2.5 ng/ml IL-6 affords
near maximal activation of STAT3 with only a trace of activated STAT1.
Because in some cell types IL-6 activates MAP kinase signaling (27) and
might contribute to c-fos activation through this route, we
determined the extent of MAP kinase activation in HepG2 cells under
conditions of low-dose IL-6 treatment. Western blotting with
phosphospecific antibodies to various MAP kinases and ELK1 established
that the level of IL-6 treatment used does not lead to detectable MAP
kinase activity (Fig. 2B, lanes 1-3). Likewise,
treatment with TPA, which stimulates various serine kinases, did not
lead to tyrosine phosphorylation of STAT3 (Fig. 2B, lanes 4 and 5). Thus the two activators, IL-6 and TPA, apparently
act through different signaling pathways under these conditions. As
reported previously, simultaneous co-treatment with TPA blocks
IL-6-mediated tyrosine phosphorylation of STAT3 (28). STAT3 serine
phosphorylation was found to be sensitive to application of the MEK1
inhibitor PD098059 (Fig. 2B, lanes 7-12),
thereby precluding the use of MAP kinase inhibitors to completely
remove the possibility of low level activation. In all cases in Fig. 2,
equal loading was confirmed by stripping the Western blots and probing
for equal STAT3 or ELK1 immunoreactivity (data not shown).
|
As judged by RT-PCR assays of mRNA concentration (Fig.
2C), TPA treatment led to a very large induction of the
chromosomal c-fos gene, whereas a much smaller induction
(~5%) of the c-fos gene followed IL-6 treatment (Fig.
2C). Similar patterns were also observed for
junB, an immediate early gene also thought to be subject to
regulation by STAT3 (29) (Fig. 3). The
IL-6-mediated stimulation of the c-fos and junB
genes was attenuated by the addition of the kinase inhibitor PD098059,
suggesting potential sensitivity of these promoters to STAT3 serine
phosphorylation, a modification known to be required for maximal STAT3
transcriptional activity (30). This sensitivity to PD098059 was also
observed for SOCS3, a target gene insensitive to TPA
stimulation alone (data not shown).
|
Although the data shown in Fig. 2 suggested that
IL-6-dependent STAT3 activation of c-fos
transcription is possible, definitive proof required more sensitive
examination of MAP kinase activity and direct evidence for binding to
the chromosomal c-fos promoter by STAT3. We therefore sought
a highly sensitive indicator of MAP kinase activity in HepG2 cells.
With two c-fos copies per cell, we reasoned that
c-fos promoter-bound phosphorylated ELK1, the terminal
substrate of the various MAP kinases, should provide a sensitive marker
for p38, ERK1/2, or c-Jun NH2-terminal kinase activity
(31). Chromatin immunoprecipitation with anti-pS383-ELK1 antibodies
showed the presence of serine phosphorylated ELK1 on the promoter after
30 min of TPA treatment but not after IL-6 treatment (Fig.
4A, lanes 6-8),
suggesting again that IL-6 does not activate a serine kinase cascade
that reaches the c-fos promoter. Therefore the IL-6
activation of the chromosomal c-fos gene is most likely to
occur through STAT3.
|
STAT3 but Not STAT1 Is Present at the c-fos Promoter in
Vivo--
We then turned to the importance of STAT3 compared with
STAT1 as an activator of c-fos by doing chromatin
precipitation with various antibodies both on the c-fos
promoter and the IRF-1 promoter, which is a gene activated
by IFN through the activation of STAT1. RT-PCR demonstrated that
IL-6 treatment leads to c-fos mRNA accumulation with
minimal or no IRF-1 accumulation, and IFN
leads to accumulation of
IRF-1 mRNA but not c-fos mRNA (Fig. 3). We then
performed chromatin immunoprecipitation experiments of the
c-fos and IRF promoters. The anti-STAT3 antibody
precipitated both c-fos and IRF-1 promoter DNA
after 30 min of IL-6 treatment (Fig. 4A, lanes
1-3). On the other hand, activation for 30 min with the
STAT1-specific cytokine IFN
led to STAT1 accumulation at the IRF-1
promoter but not the c-fos promoter (Fig. 4A,
lanes 4 and 5). As a control, precipitation of an
internal segment of the c-fos coding region was found not to
precipitate with either antibody (data not shown). Thus STAT3 accumulates at the c-fos promoter after IL-6 treatment, but
STAT1 does not, which indicates a specificity for STAT3 over STAT1. On
the other hand, both STAT3 and STAT1 accumulate on the IRF-1 promoter, but only STAT1 accumulation correlates with actual
transcriptional activation (Fig. 3).
Selectivity of STAT Accumulation at the c-fos Promoter Is Not Because of Differences in DNA Binding Properties-- Both STAT3 and STAT1 are known to bind to the SIE site in EMSA DNA binding assays (18, 32). Therefore the discovery of selective STAT3 retention at the c-fos locus during transcriptional activation raises two possibilities. One possibility is that STAT3 has decreased kinetics of DNA dissociation compared with STAT1 with similar Kd. For a previously reported STAT1 linker mutant, this sort of change in kinetics compared with wild type led to impaired chromatin accumulation and transcriptional inactivity (25). A second possibility is that STAT3 interacts with other proteins present at the c-fos promoter that serve to retain it.
We therefore repeated the observation that STAT1 and STAT3 bind
approximately equally (18) in EMSA analysis with either the SIE from
the c-fos gene (Fig.
5A, left) or a
mutated version of this site (variously termed M67 or hSIE) that has
increased binding for the STATs (Fig. 5A, right).
We then examined the off-rate of DNA binding by exposure of the DNA-
protein complex to unlabeled probe for the SIE site (m67
provided as reference) (Fig. 5B). The SIE exhibits rapid and
equal protein-DNA dissociation kinetics for both STAT1 and STAT3.
Therefore STAT3-specific accumulation on the c-fos promoter
(see Fig. 4A) does not rely on a markedly different
dissociation rate of STAT3 compared with STAT1, which strongly suggests
protein interaction between STAT3 and other proteins on the promoter as
the basis for stable STAT3 binding and chromatin accumulation.
|
Maximal Transcriptional Activation by the c-fos Promoter Requires
Both Activated STAT3 and MAP Kinase Activity--
Given the weak
induction of the c-fos gene by IL-6 alone, we examined the
effect of IL-6 treatment after co-treatment with TPA or the natural
polypeptide activator, EGF. As mentioned earlier, TPA treatment has the
effect of blocking STAT3 phosphorylation in HepG2 cells. To achieve
near simultaneous activation of STAT3 and proteins activated by
TPA/EGF, we pretreated cells with IL-6 for 5-30 min before a 30-min
TPA or EGF treatment and then examined c-fos mRNA
accumulation (Fig. 6). Although both TPA
and EGF result in much stronger c-fos mRNA accumulation,
the IL-6 pretreatment resulted in an ~2-fold boost to the large TPA
or EGF inductions. (To demonstrate this difference the RT-PCR reaction
was carried out under non-saturating conditions.)
|
We also carried out a transfection experiment to examine the
supplemental effect of IL-6 on TPA-induced transcription (Fig. 7) using a luciferase reporter assay.
Once again, under conditions of acute transfection there was an
~2-fold boost in signal by IL-6 compared with TPA alone. This effect
required an intact SIE site indicating the critical importance of STAT3
binding to the IL-6 supplementation.
|
![]() |
DISCUSSION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
This work addresses several different questions about activation of the chromosomal c-fos promoter. First, it has been concluded from many transfection (permanent and transient) experiments that the serum response factor-ELK1 complex, likely also including the nearby AP-1 proteins, is required for the optimal transcriptional response to growth factors and to phorbol esters (TPA). Yet there was also evidence from transfections that a STAT site (SIE) had a role in the regulation of c-fos. Whether activity of the chromosomal gene depended on this latter element was not settled. In these studies, we examined the role of the SIE in the regulation of the endogenous c-fos locus.
We first uncoupled stimulation of the STAT proteins from the MAP kinase induction of the chromosomal gene by using low levels of IL-6. IL-6 treatment leads to STAT3 activation with little STAT1 activation, and IL-6 does not induce phosphorylation of ELK1 at the c-fos locus as does TPA, as measured by chromatin immunoprecipitation. Thus we conclude that IL-6 treatment alone induces c-fos gene transcription in the absence of demonstrable MAP kinase activation. Further, chromatin immunoprecipitation established that IL-6 stimulation correlates with binding by STAT3. Even though the IL-6 induction of c-fos was ~20-fold less than that stimulated by TPA or EGF, it is clear that IL-6 treatment augments by 2-3-fold either TPA or EGF stimulation of c-fos transcription.
Our experiments also shed light on mechanisms for inducing STAT1- or
STAT3-specific activation of chromosomal genes. For a number of years,
it has been clear that STAT3 and STAT1 have opposing roles in growth
control; STAT3 is activated in proliferative states and STAT1 in growth
arrest (33). However, the virtually identical DNA binding specificities
of these two STATs have raised the question of how these opposing
signals are interpreted at the DNA level (34). Using the
c-fos and IRF-1 genes, we demonstrate two ways that such a conundrum can be resolved. In the case of c-fos,
both STAT3 and STAT1 bind weakly to the nonoptimal SIE site, but only STAT3 is retained at the promoter, presumably because of protein contacts made by STAT3 that are not made by STAT1 (Fig. 4). Thus, IL-6
activates transcription of the c-fos gene and IFN does
not. In the case of IRF-1, a perfect STAT site is present in
the promoter ~150 bp from the start site, and both activated STAT3
and STAT1 bind to the chromatin at this site. However, only IFN
(through STAT1) leads to strong induction of the IRF-1
promoter. Although both STATs are retained on the chromatin, only STAT1
activates transcription. It should also be noted that these
specificities of transcriptional regulation make physiological sense,
because c-fos is a proto-oncogene and IRF-1 is a
proapoptosis gene, which fits the consensus for roles of STAT3 and
STAT1 (2, 35).
Therefore STAT specificity at the promoter level can be determined by selective factor retention or selective factor activity. We speculate that other transcriptionally active proteins bound to adjacent sites on these two promoters may govern this selective accumulation and activity of the STAT1 and STAT3 molecules. For example, c-Jun, which interacts more strongly with STAT3 than STAT1 (36), could be constitutively present on the AP-1 site(s) in the c-fos promoter and may help immobilize STAT3.
How do these findings affect thinking about the enhanceosome concept
popularized by studies on the IFN and TCR
gene promoters (37). In
those two cases, multiple proteins are bound to short DNA segments and
apparently physically interact with high spatial specificity in order
for fulsome transcriptional activation of the two genes. Previous work
with stably integrated c-fos reporter constructs suggested
that a productive transcriptional response from c-fos
requires the SIE, AP-1, and serum response element to work in concert
in a manner similar to the IFN
and TCR
gene enhanceosomes (20).
In our experiments, there may be protein-protein interaction on the
c-fos promoter between activated STAT3 and other
constitutively bound proteins. But the activation by serine phosphorylation of ELK1, a necessary event in TPA and EGF stimulation of transcription, does not have to occur in STAT3-driven transcription of c-fos. (Figs. 3 and 4). Nonetheless, simultaneous action
of STAT3 and phospho-ELK1 (plus perhaps other serine phosphorylations) does appear to maximize the transcriptional output from
c-fos. So even though large inductions are possible in the
absence of bound STAT3, maximal inductions may require
simultaneous binding and phosphorylation of constitutive factors and of
STAT3. This arrangement seems appropriate, because many growth factors
which activate MAP kinases are also sources of STAT3 activation
(38).
![]() |
ACKNOWLEDGEMENTS |
---|
We thank Lois Cousseau for assistance with manuscript preparation. We also thank Peter Shaw for helpful discussions.
![]() |
FOOTNOTES |
---|
* This work was supported by National Institutes of Health (NIH) Grants AI34420 and AI32489 (to J. E. D.), Medical Scientist Training Program Grant GM07739 (to E. Y.), and NIH Training Grant CA09673 (to E. Y. and D. B.)The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
To whom correspondence should be addressed. Tel.:
212-327-8796; Fax: 212-327-8801; E-mail:
darnell@mail.rockefeller.edu.
Published, JBC Papers in Press, February 24, 2003, DOI 10.1074/jbc.M213073200
2 www.transfac.gbf.ed/dbsearch/clustalw.html.
![]() |
ABBREVIATIONS |
---|
The abbreviations used are:
TCF, ternary
complex factor;
SIE, sis-inducible element;
EGF, epidermal
growth factor;
EMSA, electrophoretic mobility shift assay;
STAT, signal
transducers and activators of transcription;
TPA, 12-O-tetradecanoylphorbol-13-acetate;
MAP, mitogen-activated
protein;
IFN, interferon;
TCR, T cell receptor
;
IL, interleukin;
RT, reverse transcriptase;
MEK, mitogen-activated protein kinase;
ERK, extracellular signal-related kinase;
JNK, c-Jun
NH2-terminal kinase;
GAPDH, glyceraldehyde-3-phosphate
dehydrogenase.
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
1. | Greenberg, M. E., and Ziff, E. B. (1984) Nature 311, 433-438[Medline] [Order article via Infotrieve] |
2. | Karin, M., Liu, Z., and Zandi, E. (1997) Curr. Opin. Cell Biol. 9, 240-246[CrossRef][Medline] [Order article via Infotrieve] |
3. | Lau, L. F., and Nathans, D. (1987) Proc. Natl. Acad. Sci. U. S. A. 84, 1182-1186[Abstract] |
4. | Hill, C. S., and Treisman, R. (1995) EMBO J. 14, 5037-5047[Abstract] |
5. | Gille, H., Sharrocks, A. D., and Shaw, P. E. (1992) Nature 358, 414-417[CrossRef][Medline] [Order article via Infotrieve] |
6. | Treisman, R. (1995) EMBO J. 14, 4905-4913[Medline] [Order article via Infotrieve] |
7. | Whitmarsh, A. J., Yang, S. H., Su, M. S., Sharrocks, A. D., and Davis, R. J. (1997) Mol. Cell. Biol. 17, 2360-2371[Abstract] |
8. | Marais, R., Wynne, J., and Treisman, R. (1993) Cell 73, 381-393[Medline] [Order article via Infotrieve] |
9. | Gille, H., Kortenjann, M., Thomae, O., Moomaw, C., Slaughter, C., Cobb, M. H., and Shaw, P. E. (1995) EMBO J. 14, 951-962[Abstract] |
10. | Herrera, R. E., Shaw, P. E., and Nordheim, A. (1989) Nature 340, 68-70[CrossRef][Medline] [Order article via Infotrieve] |
11. | Fisch, T. M., Prywes, R., and Roeder, R. G. (1987) Mol. Cell. Biol. 7, 3490-3502[Medline] [Order article via Infotrieve] |
12. | Fisch, T. M., Prywes, R., Simon, M. C., and Roeder, R. G. (1989) Genes Dev. 3, 198-211[Abstract] |
13. | Wagner, B. J., Hayes, T. E., Hoban, C. J., and Cochran, B. H. (1990) EMBO J. 9, 4477-4484[Abstract] |
14. |
Kim, D. W.,
Cheriyath, V.,
Roy, A. L.,
and Cochran, B. H.
(1998)
Mol. Cell. Biol.
18,
3310-3320 |
15. | Cheung, P., Tanner, K. G., Cheung, W. L., Sassone-Corsi, P., Denu, J. M., and Allis, C. D. (2000) Mol. Cell 5, 905-915[Medline] [Order article via Infotrieve] |
16. | Thomson, S., Clayton, A. L., and Mahadevan, L. C. (2001) Mol. Cell 8, 1231-1241[Medline] [Order article via Infotrieve] |
17. | Treisman, R. (1985) Cell 42, 889-902[Medline] [Order article via Infotrieve] |
18. | Zhong, Z., Wen, Z., and Darnell, J. E., Jr. (1994) Science 264, 95-98[Medline] [Order article via Infotrieve] |
19. | Gronowski, A. M., Zhong, Z., Wen, Z., Thomas, M. J., Darnell, J. E., Jr., and Rotwein, P. (1995) Mol. Endocrinol. 9, 171-177[Abstract] |
20. | Robertson, L. M., Kerppola, T. K., Vendrell, M., Luk, D., Smeyne, R. J., Bocchiaro, C., Morgan, J. I., and Curran, T. (1995) Neuron 14, 241-252[Medline] [Order article via Infotrieve] |
21. | Leaman, D. W., Pisharody, S., Flickinger, T. W., Commane, M. A., Schlessinger, J., Kerr, I. M., Levy, D. E., and Stark, G. R. (1996) Mol. Cell. Biol. 16, 369-375[Abstract] |
22. |
Hodge, C.,
Liao, J.,
Stofega, M.,
Guan, K.,
Carter-Su, C.,
and Schwartz, J.
(1998)
J. Biol. Chem.
273,
31327-31336 |
23. | Meraz, M. A., White, J. M., Sheehan, K. C., Bach, E. A., Rodig, S. J., Dighe, A. S., Kaplan, D. H., Riley, J. K., Greenlund, A. C., Campbell, D., Carver-Moore, K., DuBois, R. N., Clark, R., Aguet, M., and Schreiber, R. D. (1996) Cell 84, 431-442[Medline] [Order article via Infotrieve] |
24. |
Yang, E.,
Wen, Z.,
Haspel, R. L.,
Zhang, J. J.,
and Darnell, J. E., Jr.
(1999)
Mol. Cell. Biol.
19,
5106-5112 |
25. |
Yang, E.,
Henriksen, M. A.,
Schaefer, O.,
Zakharova, N.,
and Darnell, J. E., Jr.
(2002)
J. Biol. Chem.
277,
13455-13462 |
26. | Schonthal, A., Herrlich, P., Rahmsdorf, H. J., and Ponta, H. (1988) Cell 54, 325-334[Medline] [Order article via Infotrieve] |
27. | Hirano, T. (1998) in The Cytokine Handbook (Thomson, A. W., ed) , pp. 197-228, Academic Press, San Diego, CA |
28. |
Sengupta, T. K.,
Talbot, E. S.,
Scherle, P. A.,
and Ivashkiv, L. B.
(1998)
Proc. Natl. Acad. Sci. U. S. A.
95,
11107-11112 |
29. | Coffer, P., Lutticken, C., van Puijenbroek, A., Klop-de Jonge, M., Horn, F., and Kruijer, W. (1995) Oncogene 10, 985-994[Medline] [Order article via Infotrieve] |
30. | Wen, Z., Zhong, Z., and Darnell, J. E., Jr. (1995) Cell 82, 241-250[Medline] [Order article via Infotrieve] |
31. | Whitmarsh, A. J., Shore, P., Sharrocks, A. D., and Davis, R. J. (1995) Science 269, 403-407[Medline] [Order article via Infotrieve] |
32. | Sadowski, H. B., Shuai, K., Darnell, J. E., Jr., and Gilman, M. Z. (1993) Science 261, 1739-1744[Medline] [Order article via Infotrieve] |
33. | Bromberg, J., and Darnell, J. E., Jr. (2000) Oncogene 19, 2468-2473[CrossRef][Medline] [Order article via Infotrieve] |
34. | Horvath, C. M., Wen, Z., and Darnell, J. E., Jr. (1995) Genes Dev. 9, 984-994[Abstract] |
35. | Tanaka, N., Ishihara, M., Kitagawa, M., Harada, H., Kimura, T., Matsuyama, T., Lamphier, M. S., Aizawa, S., Mak, T. W., and Taniguchi, T. (1994) Cell 77, 829-839[Medline] [Order article via Infotrieve] |
36. |
Zhang, X.,
Wrzeszczynska, M. H.,
Horvath, C. M.,
and Darnell, J. E., Jr.
(1999)
Mol. Cell. Biol.
19,
7138-7146 |
37. | Carey, M. (1998) Cell 92, 5-8[Medline] [Order article via Infotrieve] |
38. |
Darnell, J. E.
(1997)
Science
277,
1630-1635 |