1: Blood. 2005 Jan 15;105(2):689-96. Epub 2004 Jul 13. 

STAT3 regulates NF-kappaB recruitment to the IL-12p40 promoter in dendritic
cells.

Hoentjen F, Sartor RB, Ozaki M, Jobin C.

Center for Gastrointestinal Biology and Diseases, University of North Carolina
at Chapel Hill, USA.

Interleukin-10-deficient (IL-10(-/-)) mice develop an IL-12-mediated intestinal
inflammation in the absence of endogenous IL-10. The molecular mechanisms of the
dysregulated IL-12 responses in IL-10(-/-) mice are poorly understood. In this
study, we investigated the role of nuclear factor-kappa B (NF-kappaB) and signal
transducers and activators of transcription 3 (STAT3) in lipopolysaccharide
(LPS)-induced IL-12p40 gene expression in bone marrow derived-dendritic cells
(BMDCs) isolated from wild-type (WT) and IL-10(-/-) mice. We report higher
IL-12p40 mRNA accumulation and protein secretion in LPS-stimulated BMDCs
isolated from IL-10(-/-) compared with WT mice. LPS-induced NF-kappaB signaling
is similar in IL-10(-/-) and WT BMDCs as measured by IkappaBalpha
phosphorylation and degradation, RelA phosphorylation and nuclear translocation,
and NF-kappaB transcriptional activity, with no down-regulatory effects of
exogenous IL-10. Chromatin immunoprecipitation demonstrated enhanced NF-kappaB
(cRel, RelA) binding to the IL-12p40 promoter in IL-10(-/-) but not WT BMDCs.
Interestingly, LPS induced STAT3 phosphorylation in WT but not IL-10(-/-) BMDCs,
a process blocked by IL-10 receptor blocking antibody. Adenoviral gene delivery
of a constitutively active STAT3 but not control green fluorescence protein
(GFP) virus blocked LPS-induced IL-12p40 gene expression and cRel recruitment to
the IL-12p40 promoter. In conclusion, dysregulated LPS-induced IL-12p40 gene
expression in IL-10(-/-) mice is due to enhanced NF-kappaB recruitment to the
IL-12p40 promoter in the absence of activated STAT3.

PMID: 15251981 [PubMed - indexed for MEDLINE]


---------------------------------------------------------------


2: J Biol Chem. 2004 Jun 4;279(23):24873-80. Epub 2004 Mar 26. 

PIAS3 suppresses NF-kappaB-mediated transcription by interacting with the
p65/RelA subunit.

Jang HD, Yoon K, Shin YJ, Kim J, Lee SY.

Division of Molecular Life Sciences and Center for Cell Signaling Research, Ewha
Womans University, Seoul 120-750, Korea.

Nuclear factor-kappaB (NF-kappaB) is a transcription factor critical for key
cellular processes, including immune response, apoptosis, and cell cycle
progression. A yeast two-hybrid screening, using the Rel homology domain (RHD)
of the p65 subunit (RelA) of NF-kappaB as bait, led to the isolation of PIAS3,
previously identified as a specific inhibitor of STAT3. We show that PIAS3 can
directly associate with p65 using an in vitro pull-down and in vivo
coimmunoprecipitation assays. When overexpressed, PIAS3 inhibits
NF-kappaB-dependent transcription induced by treatment with tumor necrosis
factor alpha (TNF-alpha) or interleukin-1beta or by overexpression of TNF family
receptors such as RANK, TNFR1, and CD30 or signal transducers of TNF
receptor-associated factors (TRAFs), including TRAF2, TRAF5, and TRAF6.
Downregulation of PIAS3 by RNA interference reverses its effect on
TNF-alpha-mediated NF-kappaB activation. We found that an N-terminal region of
PIAS3 is necessary for both the interaction with p65 and the transcriptional
suppression activity. In addition, we found that an LXXLL coregulator signature
motif located within the N-terminal region of PIAS3 is the minimal requirement
for the interaction with p65. Furthermore, we demonstrate that PIAS3 interferes
with p65 binding to the CBP coactivator, thereby resulting in a decreased
NF-kappaB-dependent transcription. Taken together, these data suggest that PIAS3
may function in vivo as a modulator in suppressing the transcriptional activity
of p65.

PMID: 15140884 [PubMed - indexed for MEDLINE]


---------------------------------------------------------------


3: Blood. 2004 Apr 15;103(8):3175-84. Epub 2003 Dec 18. 

Nuclear factor-kappaB and STAT3 are constitutively active in CD138+ cells
derived from multiple myeloma patients, and suppression of these transcription
factors leads to apoptosis.

Bharti AC, Shishodia S, Reuben JM, Weber D, Alexanian R, Raj-Vadhan S, Estrov Z,
Talpaz M, Aggarwal BB.

Department of Bioimmunotherapy, The University of Texas M. D. Anderson Cancer
Center, Houston 77030, USA.

Chemoresistance is a major problem in the treatment of patients with multiple
myeloma (MM). Because of the central role of the nuclear transcription factors
nuclear factor-kappaB (NF-kappaB) and signal transducer and activator of
transcription 3 (STAT3) in chemoresistance, cell survival, and proliferation, we
investigated whether MM cells derived from patients express activated NF-kappaB
and STAT3 and if their suppression induces apoptosis. We assayed CD138+ cells
from the bone marrow of 22 MM patients and checked for the activated forms of
NF-kappaB and STAT3 by immunocytochemistry. We found that MM cells from all the
patients expressed the activated forms of NF-kappaB and STAT3 but to a variable
degree (NF-kappaB: low, 3 of 22; moderate, 5 of 22; or high, 14 of 22; STAT3:
none, 1 of 22; low, 3 of 22; moderate, 5 of 22; or high, 14 of 22). Constitutive
activation of NF-kappaB was in some cases also independently confirmed by
electrophoretic mobility gel shift assay. In contrast to MM patients, activated
forms of NF-kappaB and STAT3 were absent in cells from healthy individuals.
Suppression of NF-kappaB and STAT3 activation in MM cells by ex vivo treatment
with curcumin (diferuloylmethane) resulted in a decrease in adhesion to bone
marrow stromal cells, cytokine secretion, and in the viability of cells. When
compared with curcumin, dexamethasone was less effective in suppression of
NF-kappaB activation and induction of apoptosis in myeloma cells. Overall, our
results indicate that fresh cells from MM patients express constitutively active
NF-kappaB and STAT3, and suppression of these transcription factors inhibits the
survival of the cells.

PMID: 15070700 [PubMed - indexed for MEDLINE]


---------------------------------------------------------------


4: J Am Soc Nephrol. 2004 Mar;15(3):585-91. 

The STAT3 DNA-binding domain mediates interaction with NF-kappaB p65 and
iuducible nitric oxide synthase transrepression in mesangial cells.

Yu Z, Kone BC.

Department of Internal Medicine, The University of Texas Medical School at
Houston, Houston, TX 77030, USA.

Signal transducer and activator of transcription 3 (STAT3) and nuclear factor
kappaB (NF-kappaB) are important transcription factors involved in
glomerulonephritis and other inflammatory processes, including transcription of
the inducible nitric oxide synthase (iNOS) gene. The ability of STAT3 to
interact physically with NF-kappaB p65 in glomerular mesangial cells and thereby
to inhibit NF-kappaB-mediated transactivation of the iNOS gene was demonstrated
previously. STAT3 is a modular protein with several structurally and
functionally defined domains. For defining STAT3 domains that interact with
NF-kappaB p65, (35)S-labeled proteins that corresponded to each STAT3alpha
domain were synthesized, and their ability to bind specifically a GST-NF-kappaB
p65 fusion protein in GST pulldown assays was tested. The coiled-coil and
DNA-binding domains were specifically retained by GST-NF-kappaB p65, whereas the
N-terminal, linker domain, Src homology 2 domain, and transcriptional activation
domain failed to interact with NF-kappaB p65. Deletion of the region L(358)
through I(369) of the STAT3 DNA-binding domain greatly reduced binding to
GST-NF-kappaB p65. Alanine substitution mutations at four highly conserved
residues-L(358), N(359), K(363), and V(366)-in this region greatly abrogated the
ability of STAT3 to bind NF-kappaB p65. Moreover, in contrast to the
transrepression afforded by wild-type STAT3alpha, a STAT3alpha construct
harboring these mutations, failed to suppress endogenous NO production and to
transrepress iNOS promoter-reporter and kappaB element-reporter constructs in
IL-beta-stimulated mesangial cells. These data reveal a novel role for the
DNA-binding domain in the physical and functional coupling of STAT3 to NF-kappaB
p65 that is important for regulating the transcriptional activity of iNOS and
likely other NF-kappaB p65 responsive genes that are important for mesangial
cell responses.

PMID: 14978160 [PubMed - indexed for MEDLINE]


---------------------------------------------------------------


5: J Biol Chem. 2004 Jan 16;279(3):1768-76. Epub 2003 Oct 30. 

Interleukin 1 activates STAT3/nuclear factor-kappaB cross-talk via a unique
TRAF6- and p65-dependent mechanism.

Yoshida Y, Kumar A, Koyama Y, Peng H, Arman A, Boch JA, Auron PE.

New England Baptist Bone and Joint Institute, Beth Israel Deaconess Medical
Center and the Department of Medicine, Harvard Medical School, Boston, MA 02115,
USA.

Interleukins (IL) 1 and 6 are important cytokines that function via the
activation, respectively, of the transcription factors NF-kappaB and STAT3. We
have observed that a specific type of kappa B DNA sequence motif supports both
NF-kappaB p65 homodimer binding and cooperativity with
non-tyrosine-phosphorylated STAT3. This activity, in contrast to that mediated
by kappaB DNA motifs that do not efficiently bind p65 homodimers, is shown to be
uniquely dependent upon signal transduction through the carboxyl terminus of
TRAF6. Furthermore, STAT3 and p65 are shown to physically interact, in vivo, and
this interaction appears to inhibit the function of "classical" STAT3 GAS-like
binding sites. The distinct p50 form of NF-kappaB is also shown to interact with
STAT3. However, in contrast to p65, p50 cooperates with STAT3 bound to GAS
sites. These data argue for a novel transcription factor cross-talk mechanism
that may help resolve inconsistencies previously reported regarding the
mechanism of IL-1 inhibition of IL-6 activity during the acute-phase response.

PMID: 14593105 [PubMed - indexed for MEDLINE]


---------------------------------------------------------------


6: Cancer Res. 2003 May 1;63(9):2206-15. 

Constitutive activation of nuclear factor kappaB p50/p65 and Fra-1 and JunD is
essential for deregulated interleukin 6 expression in prostate cancer.

Zerbini LF, Wang Y, Cho JY, Libermann TA.

BIDMC Genomics Center and New England Baptist Bone and Joint Institute, Boston,
Massachusetts 02115, USA.

To date, no effective treatment for patients with advanced androgen-independent
prostate cancer is available, whereas androgen ablation therapy, surgery, and
radiation therapy are effective in treating local, androgen-dependent tumors.
The mechanisms underlying the differences between androgen-dependent and
-independent prostate cancer remain elusive. Interleukin (IL)-6 is a pleiotropic
cytokine whose expression under normal physiological conditions is tightly
controlled. However, aberrant constitutive IL-6 gene expression has been
implicated in prostate cancer progression and resistance to chemotherapy and has
been directly linked to prostate cancer morbidity and mortality. Particularly
striking is the large increase in the expression of IL-6 in hormone-refractory
prostate cancer. IL-6, in addition to its role as an immunomodulatory cytokine,
functions as a growth and differentiation factor for prostate cancer cells. To
determine the molecular mechanisms that lead to deregulated IL-6 expression in
advanced prostate cancer, we examined the regulatory elements involved in IL-6
gene expression in androgen-independent prostate cancer cells. We demonstrate
that, in contrast to the androgen-sensitive LNCaP cells, androgen-insensitive
PC-3 and DU145 cells express high levels of IL-6 protein and mRNA due to
enhanced promoter activity. Deregulated activation of the IL-6 promoter is for
the most part mediated by a combined constitutive activation of the nuclear
factor (NF)-kappaB p50 and p65 and the activator protein 1 (AP-1) JunD and Fra-1
family members as demonstrated by electrophoretic mobility shift assays,
site-directed mutagenesis, and transfection experiments. Mutation of the
NF-kappaB and AP-1 sites drastically reduces IL-6 promoter activity in both
androgen-independent prostate cancer cell lines. Additionally, inhibition of
these transcription factors using adenovirus vectors encoding either the
IkappaBalpha repressor gene or a dominant negative JunD mutant leads to a strong
down-regulation of IL-6 gene expression at the mRNA and protein level as
measured by real-time PCR and ELISA, respectively. Furthermore, the blockade of
IL-6 gene expression results in drastic inhibition of the constitutively
activated signal transducers and activators of transcription 3 signaling pathway
in DU145 cells. Our data demonstrate for the first time that a combined aberrant
activation of NF-kappaB p50 and p65 and AP-1 JunD and Fra-1 in
androgen-independent prostate cancer cells results in deregulated IL-6
expression, suggesting a novel potential entry point for therapeutic
intervention in prostate cancer.

PMID: 12727841 [PubMed - indexed for MEDLINE]


---------------------------------------------------------------


7: Immunology. 2003 Apr;108(4):539-47. 

Overexpressed nuclear factor-kappaB can participate in endogenous C-reactive
protein induction, and enhances the effects of C/EBPbeta and signal transducer
and activator of transcription-3.

Agrawal A, Cha-Molstad H, Samols D, Kushner I.

Department of Biochemistry, Case Western Reserve University, Cleveland, OH, USA.

C-reactive protein (CRP), the prototypical human acute phase protein, is
produced primarily by hepatocytes. Its expression is modestly induced by
interleukin (IL)-6 in Hep3B cells while IL-1, which alone has no effect,
synergistically enhances the effects of IL-6. In previous studies of the
proximal CRP promoter, we found that signal transducer and activator of
transcription-3 (STAT3) and C/EBPbeta -mediated IL-6-induced transcription and
that Rel p50 acted synergistically with C/EBPbeta, in the absence of p65, to
enhance CRP transcription. Neither a requirement nor a binding site for the
classic nuclear factor (NF)-kappaB heterodimer p50/p65 were found. The current
studies were undertaken to determine whether similar novel transcription factor
interactions might regulate the endogenous CRP gene. Transiently overexpressed
p50 or p65 induced CRP mRNA accumulation in Hep3B cells. The heterodimer p50/p65
was markedly more effective than p50 or p65 homodimers. Co-overexpression of p50
or p65 with C/EBPbeta or STAT3 synergistically enhanced CRP expression. Maximal
expression was observed with overexpression of all four transcription factors;
comparable effects were observed with IL-1beta treatment of cells overexpressing
STAT3 + C/EBPbeta. Data from the Human Genome Project revealed 13 potential
kappaB sites in the first 4000 bases of the CRP promoter, only one of which,
centred at -2652, bound nuclear p50/p65 heterodimer activated by IL-1beta. Our
findings indicate that classical NF-kappaB activation can participate in
endogenous CRP induction, and that activated NF-kappaB may synergistically
enhance the effects of C/EBPbeta and STAT3. They raise the possibility, not as
yet established, that NF-kappaB activation may be responsible for the
synergistic effect of IL-1beta on IL-6-induced CRP expression.

PMID: 12667216 [PubMed - indexed for MEDLINE]


---------------------------------------------------------------


8: Biochem J. 2002 Oct 1;367(Pt 1):97-105. 

Signal transducers and activators of transcription 3 (STAT3) inhibits
transcription of the inducible nitric oxide synthase gene by interacting with
nuclear factor kappaB.

Yu Z, Zhang W, Kone BC.

Departments of Internal Medicine and of Integrative Biology, Pharmacology and
Physiology, The University of Texas Medical School at Houston, 6431 Fannin, MSB
4.148, Houston, TX 77030, U.S.A.

Prolific generation of NO by inducible nitric oxide synthase (iNOS) can cause
unintended injury to host cells during glomerulonephritis and other inflammatory
diseases. While much is known about the mechanisms of iNOS induction, few
transcriptional repressors have been found. We explored the role of signal
transducers and activators of transcription 3 (STAT3) proteins in interleukin
(IL)-1beta- and lipopolysaccharide (LPS)+interferon (IFN)-gamma-mediated iNOS
induction in murine mesangial cells. Both stimuli induced rapid phosphorylation
of STAT3 and sequence-specific STAT3 DNA-binding activity. Supershift assays
with a STAT3 element probe demonstrated that nuclear factor kappaB (NF-kappaB)
p65 and p50 complexed with STAT3 in the DNA-protein complex. The direct
interaction of STAT3 and NF-kappaB p65 was verified in vivo by
co-immunoprecipitation and in vitro by pull-down assays with glutathione
S-transferase-NF-kappaB p65 fusion protein and in vitro -translated STAT3alpha.
Overexpression of STAT3 dramatically inhibited IL-1beta- or
LPS+IFN-gamma-mediated induction of iNOS promoter-luciferase constructs that
contained the wild-type iNOS promoter or ones harbouring mutated STAT-binding
elements. In tests of indirect inhibitory effects of STAT3, overexpression of
STAT3 dramatically inhibited the activity of an NF-kappaB-dependent promoter
devoid of STAT-binding elements without affecting NF-kappaB DNA-binding
activity. Thus STAT3, via direct interactions with NF-kappaB p65, serves as a
dominant-negative inhibitor of NF-kappaB activity to suppress indirectly
cytokine induction of the iNOS promoter in mesangial cells. These results
provide a new model for the termination of NO production by activated iNOS
following exposure to pro-inflammatory stimuli.

PMID: 12057007 [PubMed - indexed for MEDLINE]


---------------------------------------------------------------


9: Virology. 2001 Nov 10;290(1):1-10. 

Measles virus activates NF-kappa B and STAT transcription factors and production
of IFN-alpha/beta and IL-6 in the human lung epithelial cell line A549.

Helin E, Vainionpaa R, Hyypia T, Julkunen I, Matikainen S.

Department of Virology, University of Turku, Kiinamyllynkatu 13, FIN-20520
Turku, Finland. eija.helin@utu.fi

Epithelial cells of the respiratory tract are the primary targets of measles
virus (MV) infection. In this work we have studied the effect of MV infection on
the activation of transcription factors nuclear factor (NF)-kappa B and signal
transducer and activator of transcription (STAT) and the production of cytokines
in the lung epithelial A549 cell line. NF-kappa B and STAT activation were
induced by MV in A549 cells as analyzed by electrophoretic mobility shift assay.
NF-kappa B activation was rapid and it was not inhibited by the protein
synthesis inhibitor cycloheximide, suggesting that MV directly activates
NF-kappa B. In contrast, Stat1, Stat3, and interferon-stimulated gene factor 3
(ISGF3) DNA binding was induced by MV infection with delayed kinetics compared
to NF-kappa B activation. MV infection also resulted in an efficient interferon
(IFN)-alpha/beta and interleukin-6 production. Cycloheximide and neutralizing
anti-IFN-alpha/beta antibodies inhibited MV-induced activation of Stat1, Stat3,
and ISGF3 DNA binding in A549 cells. In conclusion, the results suggest that MV
infection activates transcription factors involved in the initiation of innate
immune responses in epithelial cells by two different mechanisms: directly by
leading to NF-kappa B activation and indirectly via IFN-alpha/beta leading to
STAT activation.

PMID: 11882993 [PubMed - indexed for MEDLINE]


---------------------------------------------------------------


10: J Virol. 2002 Feb;76(3):1533-6. 

Increased p50/p50 NF-kappaB activation in human papillomavirus type 6- or type
11-induced laryngeal papilloma tissue.

Vancurova I, Wu R, Miskolci V, Sun S.

Department of Pediatrics, Long Island Jewish Medical Center, New Hyde Park, New
York, USA.

We have observed elevated NF-kappaB DNA-binding activity in nuclear extracts
from human papillomavirus type 6- and 11-infected laryngeal papilloma tissues.
The predominant DNA-binding species is the p50/p50 homodimer. The elevated
NF-kappaB activity could be correlated with a reduced level of cytoplasmic
IkappaBbeta and could be associated with the overexpression of p21(CIP1/WAF1) in
papilloma cells. Increased NF-kappaB activity and cytoplasmic accumulation of
p21(CIP1/WAF1) might counteract death-promoting effects elicited by
overexpressed PTEN and reduced activation of Akt and STAT3 previously noted in
these tissues.

PMID: 11773428 [PubMed - indexed for MEDLINE]


---------------------------------------------------------------


11: J Immunol. 2001 Oct 1;167(7):3652-60. 

STAT5 induces macrophage differentiation of M1 leukemia cells through activation
of IL-6 production mediated by NF-kappaB p65.

Kawashima T, Murata K, Akira S, Tonozuka Y, Minoshima Y, Feng S, Kumagai H,
Tsuruga H, Ikeda Y, Asano S, Nosaka T, Kitamura T.

Division of Hematopoietic Factors, Institute of Medical Science, University of
Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan.

We recently demonstrated that STAT5 can induce a variety of biological functions
in mouse IL-3-dependent Ba/F3 cells; STAT5-induced expression of pim-1,
p21(WAF/Cip1), and suppressor of cytokine signaling-1/STAT-induced STAT
inhibitor-1/Janus kinase binding protein is responsible for induction of
proliferation, differentiation, and apoptosis, respectively. In the present
study, using a constitutively active STAT5A (STAT5A1*6), we show that STAT5
induces macrophage differentiation of mouse leukemic M1 cells through a distinct
mechanism, autocrine production of IL-6. The supernatant of STAT5A1*6-transduced
cells contained sufficient concentrations of IL-6 to induce macrophage
differentiation of parental M1 cells, and STAT3 was phosphorylated on their
tyrosine residues in these cells. Treatment of the cells with anti-IL-6 blocking
Abs profoundly inhibited the differentiation. We also found that the STAT5A1*6
transactivated the IL-6 promoter, which was mediated by the enhanced binding of
NF-kappaB p65 (RelA) to the promoter region of IL-6. These findings indicate
that STAT5A cooperates with Rel/NF-kappaB to induce production of IL-6, thereby
inducing macrophage differentiation of M1 cells in an autocrine manner. In
summary, we have shown a novel mechanism by which STAT5 induces its pleiotropic
functions. Cytokines

PMID: 11564778 [PubMed - indexed for MEDLINE]


---------------------------------------------------------------


12: Blood. 2000 Nov 15;96(10):3466-72. 

Interleukin 1beta inhibits interleukin 6-mediated rat gamma fibrinogen gene
expression.

Zhang Z, Fuller GM.

Department of Cell Biology, University of Alabama at Birmingham, Birmingham, AL,
USA.

Interleukin (IL)-1beta and IL-6 are the 2 major inducers of a group of hepatic
genes during acute inflammation; however, each cytokine uses different
intracellular signaling molecules. In most instances, the 2 cytokines interact
positively to enhance hepatic gene expression, but in one class of acute-phase
reactants, which includes fibrinogen, IL-1beta exerts a transient inhibitory
effect over the IL-6 stimulatory signal. This study explored the effects of
IL-1beta/nuclear factor kappaB (NF-kappaB) and IL-6/signal transducer and
activator of transcription 3 (STAT3) combinatory signaling on the
transcriptional regulation of the rat gamma fibrinogen gene. Northern blot and
functional analyses employing luciferase reporter constructs driven by the rat
gamma fibrinogen promoter demonstrated that IL-1beta inhibited the IL-6-mediated
transcription of this gene. Exposing primary rat hepatocytes to IL-1beta had no
effect on IL-6-mediated STAT3 activation; instead, IL-1beta-activated NF-kappaB
associated with 2 IL-6 responsive elements (STAT3 binding site) on the rat gamma
fibrinogen promoter and blocked STAT3 binding to these regions. The competitive
binding of NF-kappaB and STAT3 on the overlapping binding site provides a
mechanism for the inhibition by IL-1beta of the IL-6-mediated transactivation of
rat gamma fibrinogen.

PMID: 11071643 [PubMed - indexed for MEDLINE]


---------------------------------------------------------------


13: J Immunol. 2000 Oct 15;165(8):4592-7. 

The Rel family member P50 mediates cytokine-induced C-reactive protein
expression by a novel mechanism.

Cha-Molstad H, Agrawal A, Zhang D, Samols D, Kushner I.

Department of Biochemistry, Case Western Reserve University, Cleveland, OH
44106, USA.

Transcription of C-reactive protein (CRP) in Hep 3B cells is induced by IL-6,
acting through C/EBP isoforms and STAT3. IL-1beta, which alone has no effect,
greatly enhances IL-6-induced transcription by unknown mechanisms. Because
IL-1beta activates the NF-kappaB system, we explored the effects of
overexpressed Rel family members on CRP expression. Unexpectedly,
transactivation assays in transiently transfected Hep 3B cells showed p50
overexpression to markedly induce CRP transcription, acting in a region 3' to
-86. In the presence of overexpressed p50, IL-1beta induced a 3-fold increase in
CRP expression, and responses to IL-6 and to IL-6 plus IL-1beta were 4-fold
greater than seen in cells without p50 overexpression. In contrast,
overexpressed p65 abolished CRP induction by p50 and by cytokines. EMSA studies
demonstrated that recombinant p50 bound to a nonconsensus kappaB site
overlapping the proximal C/EBP binding site on the CRP promoter. Mutation of a
polypyrimidine tract in the p50-binding site inhibited the transactivating
effect of cytokines. P50- but not p65-containing dimers were found in nuclei of
Hep 3B cells 18 h after stimulation with IL-1beta, when C/EBPbeta is greatly
activated, in the presence or absence of IL-6. These findings suggest that
IL-1beta induces nuclear translocation of p50-containing dimers and that p50
interacts with C/EBPbeta activated by both IL-6 and IL-1beta to induce CRP
expression.

PMID: 11035101 [PubMed - indexed for MEDLINE]


---------------------------------------------------------------


14: Am J Pathol. 2000 Mar;156(3):997-1007. 

Prevention of hepatic apoptosis and embryonic lethality in RelA/TNFR-1 double
knockout mice.

Rosenfeld ME, Prichard L, Shiojiri N, Fausto N.

Department of Pathology, University of Washington, Seattle, Washington 98195,
USA.

Mice deficient in the nuclear factor kappaB (NF-kappaB)-transactivating gene
RelA (p65) die at embryonic days 14-15 with massive liver apoptosis. In the
adult liver, activation of the NF-kappaB heterodimer RelA/p50 can cause
hepatocyte proliferation, apoptosis, or the induction of acute-phase response
genes. We examined, during wild-type fetal liver development, the expression of
the Rel family member proteins, as well as other proteins known to be important
for NF-kappaB activation. We found these proteins and active NF-kappaB complexes
in the developing liver from at least 2 days before the onset of lethality
observed in RelA knockouts. This suggests that the timing of NF-kappaB
activation is not related to the timing of lethality. We therefore hypothesized
that, in the absence of RelA, embryos were sensitized to tumor necrosis factor
(TNF) receptor 1 (TNFR-1)-mediated apoptosis. Thus, we generated mice that were
deficient in both RelA and TNFR-1 to determine whether apoptotic signaling
through TNFR-1 was responsible for the lethal phenotype. RelA/TNFR-1 double
knockout mice survived embryonic development and were born with normal livers
without evidence of increased hepatocyte apoptosis. These animals became runted
shortly after birth and survived an average of 10 days, dying from acute
hepatitis with an extensive hepatic infiltration of immature neutrophils. We
conclude that neither RelA nor TNFR-1 is required for liver development and that
RelA protects the embryonic liver from TNFR-1-mediated apoptotic signals.
However, the absence of both TNFR-1 signaling and RelA activity in newborn mice
makes these animals susceptible to endogenous hepatic infection.

PMID: 10702415 [PubMed - indexed for MEDLINE]


---------------------------------------------------------------