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*
Division of Cardiovascular Medicine and Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, CT 06536; and
Unit of Clinical Immunology, Department of Biological and Technical Research, San Raffaele Scientific Institute, Milan, Italy
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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, and
NF-
B is required for the regulated expression of all three genes.
Regulators of this pathway could potentially be potent immune
modulators. We studied the effect of a 3-hydroxy-3-methylglutaryl
coenzyme A reductase inhibitor, simvastatin, on cytokine-induced
expression of CAMs in HUVEC. Unexpectedly, pretreatment with
simvastatin potentiated the induction of all three endothelial CAMs by
IL-1 and TNF, but not LPS or PMA, as detected by flow cytometry.
Northern blot analysis demonstrated an increase in steady state
IL-1-induced E-selectin mRNA levels in cells pretreated with
simvastatin. This was associated with an increase in nuclear
translocation of NF-B, as detected by EMSA. The effect of
simvastatin was reversed by mevalonate and geranylgeranyl pyrophosphate
but not squalene, indicating that an inhibitory prenylated protein is
involved in endothelial responses to proinflammatory cytokines.
Pertussis toxin mimicked the effect of simvastatin, and the G protein
activator NaF inhibited the cytokine-induced expression of endothelial
CAMs, indicating that a Gi protein is involved. These
results demonstrate that cytokine-mediated activation of the
endothelium, and specifically CAM induction, can be modulated by a
heterotrimeric G protein-coupled pathway. This may represent a "basal
tone" of endothelial inactivation, which can either be disinhibited
or amplified, depending on the stimulus. |
Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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. ICAM-1 is
constitutively present on endothelial cells (EC) both in vitro and in
vivo, but its membrane expression is greatly augmented by the same
cytokines.
Molecular events leading to endothelial CAM induction have been
extensively studied. The aforementioned stimuli trigger transcriptional
activation of all three CAM genes in a NF-B-dependent fashion
(2). TNF- and IL-1 receptor engagement both result in
activation of kinase(s) that phosphorylate the NF-B cytosolic anchor
IB, thereby promoting its ubiquitination, dissociation, and
proteasomal degradation, with consequent NF-B nuclear
translocation and participation in transactivation. The complexities of
signaling events resulting in IB phosphorylation are beginning to
clarify (see Discussion). The diversity of receptor-mediated
NF-B activation is imparted by differential signal complex formation
and kinase activation.
Of the three CAMs mentioned above, E-selectin gene expression has been
most extensively studied. Several promoter elements, also called
positive regulatory domains (PDs), are necessary for cytokine
responsiveness (3). Three of these elements (PDI, -III,
and -IV) contain NF-B recognition sequences, whereas PDII is
inducibly bound by activating transcription factor-2/c-Jun complexes,
which is a target of the c-Jun N-terminal kinase/p38 mitogen-activated
protein kinase signaling pathway. Small GTP-binding proteins Rac1 and
CDC42 are upstream activators of this pathway (4), and
mitogen-activated protein kinase activation can also lead to NF-B
translocation (5). In the case of all three CAMs,
efficient transcriptional activation requires the coordination of both
the multiple of NF-B elements and the non-NF-B
factors/cis-elements. Indeed, the positive regulatory
influences imparted by various cytokines on individual CAM genes
continues to be elucidated. However, there is little information about
basal negative regulatory factors and/or parallel receptor-mediated
pathways that modulate the aforementioned cytokine responsiveness.
3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors,
or statins, effectively reduce cardiovascular events in patients with
coronary artery disease (6, 7). This benefit appears to
exceed the cholesterol-lowering effect of this class of drugs, possibly
through atherosclerotic plaque stabilization (8, 9).
Because leukocyte adhesion to the endothelium plays an important role
both in early atherogenesis and in plaque instability, the
hypothesis that statins inhibit endothelial CAM expression in
the inflammatory milieu was tested. We unexpectedly uncovered a
negative regulatory pathway in EC, disinhibited in the presence of the
HMG-CoA reductase inhibitor simvastatin. That is, we found that
simvastatin pretreatment potentiates cytokine-mediated endothelial CAM
induction, in a NF-B-dependent fashion. Use of various intermediates
in the cholesterol synthesis pathway indicated that inhibition of
protein prenylation is responsible for the statin effect, and further
pharmacologic analysis demonstrated that an inhibitory
Gi protein can modulate endothelial responses to
IL-1. Thus, we describe a counterregulatory pathway, heterotrimeric
G-protein-dependent, which influences the level of cytokine
responsiveness (and CAM induction) in EC.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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All the reagents were from Sigma (St. Louis, MO) unless
otherwise specified. Human recombinant IL-1ß was a kind gift from S.
Gillis (Immunex, Seattle, WA). Human recombinant TNF- was purchased
from Collaborative Biochemical Products (Bedford, MA). Pertussis toxin
and cholera toxin were purchased from Calbiochem (San Diego, CA).
Simvastatin prodrug (Merck, West Point, PA) was activated to its active
form as described (10, 11). In brief, 4 mg of simvastatin
prodrug was dissolved in 100 µl of ethanol. Then, 150 µl of 0.1 N
NaOH was added to the solution that was subsequently incubated at
50°C for 2 h. The pH was brought to 7.0 by HCl, and the final
concentration of the stock solution was adjusted to 4 mg/ml. The stock
solution was kept at 4°C.
Cell culture
Single-donor HUVEC were isolated and cultured as previously described (12, 13) on 0.5% gelatin-coated tissue culture plastic (Falcon, Lincoln Park, NJ) in M199 containing 20% FBS (Life Technologies, Grand Island, NY), 50 µg/ml endothelial cell growth factor (Collaborative Biomedical Products), 100 µg/ml porcine heparin, 2 mM L-glutamine (Life Technologies), 100 U/ml penicillin, and 100 µg/ml streptomycin. After confluence, HUVEC were harvested with trypsin-EDTA and were split 1:3. Cells were used within five passages and were identified as endothelial by their characteristic cobblestone morphology and immunocytochemical demonstration of factor VIII Ag. The cultures with >1% contaminating nonendothelial cells are routinely discarded.
FACS analysis
HUVEC were grown in 24-well plates. After reaching confluence, they were pretreated with simvastatin or vehicle control for 12–72 h, as indicated, following which cytokine or vehicle was added to the medium. At the end of the indicated time, cells were harvested with trypsin-EDTA, immunostained, and membrane molecular expression was quantified by FACS analysis on a FACSort (Becton Dickinson, San Jose, CA). A total of 5000 events was analyzed per experimental sample. The primary mouse mAbs used were anti-E-selectin (H4/18; gift of Dr. Pober, Yale University, New Haven, CT), anti-ICAM-1 (RR1.1; gift of Dr. Springer, Harvard University, Cambridge, MA), and anti-VCAM-1 (E1/6; gift of Dr. Bevilacqua, Source Pharmaceuticals, Boulder, CO). The secondary Ab was a polyclonal FITC-conjugated goat anti-mouse IgG (Zymed, San Francisco, CA). In experiments exploring the effect of various cholesterol synthesis pathway intermediates, these intermediates were added to the medium at the same time as simvastatin.
Northern blot
Total RNA was prepared from cells by extraction with Trizol (Life Technologies), according to the method of Chomczynski and Sacchi (14). Then, 20 µg of total RNA was subjected to Northern analysis as described (15). Signals were visualized by autoradiography, and densitometric analysis was performed on an ImageQuant densitometric scanner (Molecular Dynamics, Sunnyvale, CA). Steady-state E-selectin mRNA levels were normalized to that of GAPDH. To generate normalized values, E-selectin densitometric units were divided by corresponding GAPDH units. The ratio in the IL-1-activated experimental sample was defined as 1.0. The cDNA probes used were: ELAM/pi3HM (gift of Dr. Bevilacqua, Source Pharmaceuticals), and a 1.0-kb fragment of human GAPDH (Clontech Laboratories, Palo Alto, CA).
EMSA
After treatments, HUVEC monolayers (
4 x
106 cells/experimental sample) were harvested
with trypsin-EDTA. A total of 10 µg of nuclear protein was used in
EMSAs as previously described (16). The NF-B target
sequence used was derived from the PDI domain of the E-selectin
promoter region (5'-CATTGGGGATTTCCTCTTTA-3'). In some samples, a
50-fold excess of unlabeled oligonucleotide was added as
competitor.
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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HUVEC were pretreated with various doses of simvastatin before
cytokine exposure. Although some cell loss was observed, HUVEC
tolerated up to 1 µg/ml of simvastatin for 48 h. Lower
concentrations could be used for longer duration without significant
cell loss. Therefore, the minimal dose of simvastatin required to
consistently achieve the experimental effect was used. The effect of
simvastatin pretreatment on E-selectin induction in response to several
activating stimuli was assessed by flow cytometry. HUVEC were
pretreated with simvastatin 300 ng/ml (600 nM) for 18 h, following
which IL-1ß was added to the medium for 4 h, at a final
concentration of 6 U/ml. Fig. 1
A demonstrates a minor
induction of E-selectin by this submaximal concentration of IL-1ß.
Unexpectedly, simvastatin pretreatment potentiated the IL-1 effect,
whereas simvastatin alone did not induce E-selectin. A similar
potentiating effect of simvastatin was observed when a low
concentration of TNF- (6 U/ml) was used as the cytokine stimulus
(Fig. 1B). In parallel experiments, pretreatment with
mevastatin, another HMG-CoA reductase inhibitor, yielded similar
results (data not shown).
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-mediated E-selectin induction, simvastatin had either
a marginal (Fig. 1
C) or no effect on LPS responses, and none
on PMA responses (Fig. 1D). These findings suggest that
simvastatin affects the noted cytokine (IL-1 and TNF-) signaling
pathways, as opposed to primarily affecting downstream transcriptional
responses.
Because LPS has been shown to synergistically promote IL-1- and
TNF-- mediated CAM induction, the LPS-inactivator polymyxin B
sulfate (PMBS) was added to the activation experiments described above.
Whereas PMBS completely abrogated LPS-induced potentiation of
IL-1-mediated HUVEC E-selectin induction, it had no effect on
simvastatin-mediated potentiation (not shown), indicating that
contaminating LPS is not responsible for this effect.
Simvastatin effect on ICAM-1 and VCAM-1 induction
If simvastatin alters cytokine signaling pathways, modulatory
effects on other molecular inductions would be expected. Therefore,
similar experiments were performed to address whether simvastatin
potentiates IL-1ß induction of ICAM-1 and VCAM-1. After an
18-h simvastatin (300 ng/ml) pretreatment, HUVEC were IL-1 (3
U/ml)-treated for 6 h, following which VCAM-1 and ICAM-1 membrane
expression were assessed by flow cytometry. Fig. 1, E
and F, demonstrates that IL-1-mediated ICAM-1 and VCAM-1
induction, respectively, are also potentiated by simvastatin. The
magnitude of the potentiating effect, which can be seen at
concentrations as low as 25 ng/ml, is dose-dependent. Fig. 1G demonstrates that the potentiation of IL-1ß-mediated
ICAM-1 induction is greater at 200 than 25 ng/ml. The maximal effect is
observed at concentrations in the 500 ng/ml (1 µM) range, with a
required 12- to 72-h pretreatment. Higher concentrations and more
prolonged simvastatin exposure resulted in EC detachment and cell
death. Time points for CAM analysis were chosen based upon easily
interpretable expression levels. Analysis over multiple time points
demonstrated that simvastatin does not affect kinetics of CAM
expression (data not shown). At the high tolerable range, simvastatin
alone (in the absence of cytokine) promoted HUVEC ICAM-1 hyperinduction
(data not shown), indicating common regulatory pathways of basal and
cytokine-induced EC ICAM-1 expression, affected by HMG-CoA reductase
inhibition.
Simvastatin effect on E-selectin steady-state mRNA levels
Induction of endothelial CAMs by the aforementioned
proinflammatory cytokines is known to occur through gene activation. To
address whether the simvastatin-mediated increase in surface
E-selectin expression is reflective of greater mRNA levels,
Northern blot analyses were performed on RNA harvested from
IL-1-activated HUVEC, pretreated for 18 h with simvastatin or
carrier control. Fig. 2 demonstrates the
expected increase in detectable E-selectin mRNA in IL-1-activated cells
(lane 3), and an augmentation of the increased levels
in the setting of simvastatin pretreatment (lane 4).
This represents a 2.5-fold potentiation of mRNA expression, as
determined densitometrically with GAPDH-normalized signals (Fig. 2).
E-selectin mRNA was undetectable in HUVEC treated with simvastatin
alone (lane 2).
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B translocation
Because simvastatin does not potentiate all endothelial
CAM-inducing stimuli, its effect on mRNA levels is more likely to occur
at the level of cytokine-mediated signaling and consequent
transcription than mRNA stabilization. When comparing the promoter
regions of E-selectin, ICAM-1, and VCAM-1, the induced expression of
all of which are affected by simvastatin, both distinct and common
regulatory elements can be identified. NF-B binding sites are the
common cis elements found in all three genes. Therefore,
EMSAs were performed with nuclear extracts obtained from IL-1-activated
HUVEC, pretreated with simvastatin or carrier control. The NF-B PDI
domain of the E-selectin promoter was used as the target
oligonucleotide. As expected, there is an easily detectable gel
mobility shift, i.e., PDI binding, observed using IL-1-activated
extracts (Fig. 3, lane 3).
This IL-1-induced binding activity is greater in nuclear extracts from
simvastatin-pretreated cells (lane 4), whereas
simvastatin itself does not induce NF-B translocation
(lane 2). This suggests that the potentiating effect
of simvastatin occurs, at least in part, through amplifying NF-B
translocation and consequent gene activation.
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In cholesterol synthesis from Acetyl CoA, in which HMG-CoA
reductase is a proximal rate-limiting enzyme, there are several
potentially critical metabolic intermediaries with multiple byproducts,
some of which themselves have important cellular functions (Fig. 4) (17). Most notably,
farnesyl pyrophosphate and geranylgeranyl pyrophosphate are isoprenoids
that can contribute to important lipid modifications of a variety of
proteins (18). To determine whether the critical
modulatory event resulting in augmented CAM induction is reduction in
cholesterol or the lipid intermediates, attempts were made to reverse
simvastatin’s effect by the addition of various downstream byproducts
at the onset of simvastatin treatment, followed by cytokine activation
and cell harvest for flow cytometric CAM analysis. Fig. 5A demonstrates that
mevalonate (400 µM) completely reversed the ICAM-1 potentiating
effect of simvastatin, indicating that HMG-CoA reductase inhibition is
responsible for the noted affect. However, squalene, the immediate
precursor to cholesterol, which has been used extensively in cellular
studies to reverse cholesterol-mediated effects of statins
(19), had no effect on the potentiation of IL-1-induced
HUVEC ICAM-1 expression (Fig. 5B), demonstrating that
cholesterol synthesis inhibition, per se, does not result in this
response. In contrast, partial inhibition and complete reversal of the
simvastatin potentiating effect were observed with farnesyl
pyrophosphate (23 µM, Fig. 5C) and geranylgeranyl
pyrophosphate (20 µm, Fig. 5D), respectively. This
indicates that a prenylated protein, perhaps of an inhibitory class, is
involved in CAM regulation, and its inhibition is required for the
potentiating effect of simvastatin. Mevalonate, squalene, farnesyl
pyrophosphate, and geranylgeranyl pyrophosphate had no effect on ICAM-1
expression in control or IL-1ß-treated (no simvastatin) cells (data
not shown). Similar results were obtained for E-selectin (data not
shown). This effect on protein prenylation explains the necessary
extended period of pretreatment with simvastatin. That is, sufficient
time is required for turnover of preexisting prenylated proteins and
neosynthesis with inhibition of posttranslational modification.
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Prenylated proteins include small GTP-binding proteins (e.g., ras
and rho) and the 
subunit of heterotrimeric G proteins
(18). To further investigate the role of heterotrimeric G
proteins in cytokine-mediated CAM induction, the effects of cholera and
pertussis toxin, which ADP-ribosylate and modulate
Gs and Gi,
respectively, on IL-1ß-mediated HUVEC ICAM-1 were evaluated. Fig. 5E demonstrates that pretreatment with cholera toxin (100
ng/ml, 18 h, dotted line) did not affect ICAM-1 expression. In
contrast, pertussis toxin (100 ng/ml, 18 h, Fig. 5E,
dashed line) potentiated ICAM-1 induction by IL-1ß, at a level
similar to that seen with simvastatin. This suggests that
Gi modulates cytokine responses in HUVEC.
Cholera or pertussis toxin alone had no effect on ICAM-1 expression
(data not shown). Similar results were obtained when evaluating
E-selectin induction, and in response to TNF- rather than IL-1ß
(data not shown).
To confirm that G proteins are involved in HUVEC cytokine responses,
cells were pretreated with NaF (a potent activator of several
G proteins) before IL-1 exposure. NaF pretreatment (5
mM, 2 h) completely abrogated IL-1-mediated HUVEC ICAM-1
induction (Fig. 5F), also observed for E-selectin analysis
(data not shown). Although NaF effect on protein tyrosine phosphatase
activity cannot be excluded, these results strongly support a
modulatory effect of G protein signaling on cytokine responses in
EC.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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. The plasma levels obtained with a single dose of simvastatin
(up to 125 ng/ml) (20) are comparable to lower
concentrations used in this series of experiments. However, because
statins are thought to impart antiinflammatory influences in vivo, and
have been shown to reduce cardiovascular events in the setting of
atherosclerotic heart disease, this in vitro effect is an apparent
paradox. Leukocyte-endothelial interactions are the result of complex
phenomena involving both the endothelium and leukocytes. Statins have
been shown to reduce integrin expression on leukocytes
(21), and augment endothelial NO mRNA levels and NO
release (22). Both of these effects can be considered
antiinflammatory, with regard to leukocyte adhesion to the endothelium
and the resultant vascular pathology. It is likely that the net effect
of these inhibitors in vivo is, in fact, vasoprotective. Nevertheless,
the observed potentiation of CAM induction provides a potentially
important tool with which to dissect previously unappreciated
components of cytokine-mediated signaling in the endothelium.
The reversal of simvastatin’s potentiation by mevalonate but not
squalene demonstrates that HMG-CoA reductase, but not cholesterol
synthesis, inhibition is responsible for this effect. More
specifically, reversal achieved by the addition of the metabolic
intermediates geranylgeranyl pyrophosphate and farnesyl pyrophosphate
indicates that a prenylated (geranylgeranylated) protein is involved in
endothelial responses to cytokines, and disruption of this
posttranslational modification modulates the noted receptor-mediated
signaling. Potentially relevant, candidate prenylated proteins include
the subunit of heterotrimeric G proteins and small GTP binding
proteins. Members of the Rho family of small GTP binding proteins (Rho
A, Rho B, Rho C, CDC 42, and Rac) and at least eight subunits of
heterotrimeric G proteins are known to be posttranslationally modified
by geranylgeranylation (23).
To further dissect the level at which the simvastatin effect occurs,
thereby attempting to pinpoint a role(s) for G proteins in
cytokine-mediated endothelial activation, general features of CAM
induction were considered. Cytokine (IL-1 and TNF-) receptor
engagement triggers CAM gene activation and new mRNA synthesis. We have
determined by flow cytometry that the EC surface expression of neither
the p55 nor p75 TNF receptors is affected by simvastatin pretreatment
(data not shown), demonstrating that the statin effect is not simply
the consequence of enhanced membrane receptor levels. The
simvastatin-mediated augmentation in steady-state E-selectin mRNA
levels induced by IL-1 could be a consequence of enhanced transcription
or RNA stabilization. Indeed, HMG-CoA reductase inhibition has been
demonstrated to prolong the half-life of endothelial NO synthase mRNA,
in a Rho inhibition-dependent fashion (24). Although we
cannot exclude a CAM RNA stabilization mechanism, the increase in
NF-B translocation, as demonstrated by augmented E-selectin
PDI-binding activity within nuclear extracts of simvastatin-pretreated
cells, strongly supports that gene activation is enhanced. An effect on
NF-B activation is consistent with the simvastatin-mediated
potentiation of all three CAMs evaluated, E-selectin, ICAM-1, and
VCAM-1. Although each of the three genes has a specific set of 5'
regulatory elements and induced transcription factors, NF-B is an
important regulator of all three genes (2). Recently, the
signaling events leading to phosphorylation and degradation of the
cytosolic anchor IB, which are key triggers of NF-B
translocation, have been better defined. A "signalsome" protein
complex must be activated for NF-B translocation to occur. This
signalsome includes the kinases IB kinase- and -ß (IKK- and
IKK-ß), NF-B-inducing kinase (NIK), the NF-B essential
modulator IKK-, and the IKK complex-associated protein, as well as
the IBs, which must dissociate for proteasomal degradation
(25, 26, 27, 28, 29, 30, 31, 32, 33, 34). IKK-, IKK-ß, and NIK are differentially
regulated by distinct inflammatory mediators, e.g., TNF and LPS, and,
in turn, the IB proteins , ß, and 
are consequently
differentially phosphorylated and targeted to proteasomes
(35). That is, all NF-B-activating stimuli do not
follow the same signal transduction cascade. This allows for
simvastatin to affect IL-1 and TNF-mediated signal transduction, but
not that of LPS or phorbol esters. Furthermore, the TNF- (via TRAF2)
and IL-1 (via TRAF6 and IL-1 receptor-associated kinase) proximal
signaling pathways merge at NIK activation (30, 36).
Therefore, the specificity of the statin-mediated potentiation likely
lies within the complexity of these signaling cascades.
Although cholera toxin had no effect on cytokine-induced endothelial
CAM expression, pertussis toxin mimicked the simvastatin effect,
indicating that a Gi protein is involved in
this phenomenon, likely in an inhibitory fashion (37).
This is consistent with the effect of the direct G protein activator
NaF, which inhibited IL-1-mediated CAM induction, although a tyrosine
phosphatase inhibitory effect of NaF cannot be excluded. A role for
heterotrimeric G proteins in the modulation of endothelial responses to
the cytokines IL-1 and TNF has not been previously described. The human
IL-1RI cytoplasmic domain does contain a motif at positions 428–431,
which predicts G protein coupling (38). Pertussis toxin
has been reported to affect a range of IL-1 responses in various cell
(nonendothelial) types, including IL-2, PG, and macrophage CSF
production, and IL-2 receptor induction (39). Pertussis
toxin inhibits all these IL-1 responses. Similar to our findings, there
are established examples of cross-talk between IL-1 signaling and
inhibitory responses, such that modulating these pathways could either
disinhibit or prevent inhibition. Low dose IL-1 inhibits KCl-induced
increases in cortical synaptosome intracellular calcium
(40). This inhibition is abrogated by pertussis toxin.
Also, although not identified as heterotrimeric G protein-dependent,
inhibition of protein geranylgeranylation, either by a specific
inhibitor or lovastatin, promotes superinduction of IL-1-induced NO
synthase-2 expression (41). Thus, IL-1 responses can be
either positive or negative, and associated signaling
molecules/pathways can either positively or negatively affect IL-1
responses, depending on the cell type and function evaluated.
It is possible that, although not known as such, there could exist a G
protein-coupled IL-1 receptor. That is, IL-1 could initiate two
parallel responses, one traditionally stimulatory, as described above,
and a second that is G protein-coupled and inhibitory, which, if
inhibited, allows the stimulatory pathway to be unopposed.
Alternatively, there could be a non-IL-1-responsive, distinct
inhibitory Gi-coupled receptor that could
modulate IL-1 responses and, as such, confer a basal "inhibitory
tone" for endothelial CAM expression in vitro. This inhibitory
pathway could be sequentially coupled to a downstream kinase, such as
NIK, which is crucial for both IL-1 and TNF--mediated NF-B
translocation and consequent gene activation.
The toxin and NaF experiments indicate the involvement of a
heterotrimeric G protein. However, it remains possible that a small GTP
binding protein also plays a role in negatively modulating endothelial
responses to cytokines. CDC42 and Rac are involved in TNF--induced
E-selectin transcription, although in a positive regulatory fashion
(4). Experiments are currently underway to determine
whether, in addition to Gi, small GTP-binding
proteins can contribute to the inhibitory tone described above.
Although this HMG-CoA reductase-mediated potentiation of cytokine signaling was unexpected, it has uncovered a potentially novel component of such responses, and will allow a deeper molecular understanding of control on endothelial cell adhesion molecule expression, both stimulatory and inhibitory.
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Acknowledgments |
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Footnotes |
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2 Address correspondence and reprint requests to Dr. Jeffrey R. Bender, Boyer Center for Molecular Medicine 454C, 295 Congress Avenue, P.O. Box 9812, New Haven, CT 06536-0812.
3 Abbreviations used in this paper: CAM, cell adhesion molecule; HMG-CoA, 3-hydroxy-3-methylglutaryl coenzyme A; PMBS, polymyxin B sulfate; NIK, NF-B-inducing kinase; EC, endothelial cells; PD, positive regulatory domain.
Received for publication February 23, 2000. Accepted for publication June 15, 2000.
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References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
B and cytokine-inducible enhancers. FASEB J. 9:899.[Abstract]
B and TRAF-RAC/CDC42-JNK-c-Jun/ATF2 pathways. J. Immunol. 159:3508.[Abstract]
-induced E-selectin expression is activated by the nuclear factor-B and c-JUN N-terminal kinase/p38 mitogen-activated protein kinase pathways. J. Biol. Chem. 272:2753. subunit in coupling trimeric G proteins to A1 adenosine receptors. J. Biol. Chem. 271:18588.B kinase that activates the transcription factor NF-B. Nature 388:548.[Medline]
B kinases essential for NF-B activation. Science 278:860.B kinase. Cell 90:373.[Medline]
B kinase-ß: NF-B activation and complex formation with IB kinase- and NIK. Science 278:866.B kinase complex (IKK) contains two kinase subunits, IKK and IKKß, necessary for IB phosphorylation and NF-B activation. Cell 91:243.[Medline]
B induction by TNF, CD95 and IL-1. Nature 385:540.[Medline]
B kinase complex. Nature 395:297.[Medline]
B kinase complex essential for NF-B activation. Cell 93:1231.[Medline]
B kinase complex. Nature 395:292.[Medline]
B kinase (IKK)-associated protein 1, a common component of the heterogeneous IKK complex. Mol. Cell. Biol. 19:1526.B kinase signalsome activation and IB proteolysis. J. Biol. Chem. 274:24625.B puzzle?. Curr. Biol. 8:R19.[Medline]
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 A. Rezaie-Majd, G. W. Prager, R. A. Bucek, G. H. Schernthaner, T. Maca, H.-G. Kress, P. Valent, B. R. Binder, E. Minar, and M. Baghestanian Simvastatin Reduces the Expression of Adhesion Molecules in Circulating Monocytes From Hypercholesterolemic Patients Arterioscler. Thromb. Vasc. Biol., March 1, 2003; 23(3): 397 - 403. [Abstract] [Full Text] [PDF]
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 H. Usui, K. Shikata, M. Matsuda, S. Okada, D. Ogawa, T. Yamashita, K. Hida, M. Satoh, J. Wada, and H. Makino HMG-CoA reductase inhibitor ameliorates diabetic nephropathy by its pleiotropic effects in rats Nephrol. Dial. Transplant., February 1, 2003; 18(2): 265 - 272. [Abstract] [Full Text] [PDF]
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W. Dichtl, J. Dulak, M. Frick, H. F. Alber, S. P. Schwarzacher, M. P.S. Ares, J. Nilsson, O. Pachinger, and F. Weidinger HMG-CoA Reductase Inhibitors Regulate Inflammatory Transcription Factors in Human Endothelial and Vascular Smooth Muscle Cells Arterioscler. Thromb. Vasc. Biol., January 1, 2003; 23(1): 58 - 63. [Abstract] [Full Text] [PDF]
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 S. M. Houten, J. Frenkel, G. T. Rijkers, R. J.A. Wanders, W. Kuis, and H. R. Waterham Temperature dependence of mutant mevalonate kinase activity as a pathogenic factor in Hyper-IgD and periodic fever syndrome Hum. Mol. Genet., December 1, 2002; 11(25): 3115 - 3124. [Abstract] [Full Text] [PDF]
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 O. Neuhaus, S. Strasser-Fuchs, F. Fazekas, B.C. Kieseier, G. Niederwieser, H.P. Hartung, and J.J. Archelos Statins as immunomodulators: Comparison with interferon-{beta}1b in MS Neurology, October 8, 2002; 59(7): 990 - 997. [Abstract] [Full Text] [PDF]
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 G. Weigel, P. Bertalanffy, and E. Wolner Depletion of Intracellular GTP Results in Nuclear Factor-kappa B Activation and Intercellular Adhesion Molecule-1 Expression in Human Endothelial Cells Mol. Pharmacol., September 1, 2002; 62(3): 453 - 462. [Abstract] [Full Text] [PDF]
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A. Rezaie-Majd, T. Maca, R. A. Bucek, P. Valent, M. R. Muller, P. Husslein, A. Kashanipour, E. Minar, and M. Baghestanian Simvastatin Reduces Expression of Cytokines Interleukin-6, Interleukin-8, and Monocyte Chemoattractant Protein-1 in Circulating Monocytes From Hypercholesterolemic Patients Arterioscler. Thromb. Vasc. Biol., July 1, 2002; 22(7): 1194 - 1199. [Abstract] [Full Text] [PDF]
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 F. R. Danesh, M. M. Sadeghi, N. Amro, C. Philips, L. Zeng, S. Lin, A. Sahai, and Y. S. Kanwar 3-Hydroxy-3-methylglutaryl CoA reductase inhibitors prevent high glucose-induced proliferation of mesangial cells via modulation of Rho GTPase/ p21 signaling pathway: Implications for diabetic nephropathy PNAS, June 11, 2002; 99(12): 8301 - 8305. [Abstract] [Full Text] [PDF]
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 J. C. M. Morel, C. C. Park, J. M. Woods, and A. E. Koch A Novel Role for Interleukin-18 in Adhesion Molecule Induction through NFkappa B and Phosphatidylinositol (PI) 3-Kinase-dependent Signal Transduction Pathways J. Biol. Chem., September 28, 2001; 276(40): 37069 - 37075. [Abstract] [Full Text] [PDF]
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