Download Role of inducible NO synthase in cell signalling

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The Journal of Experimental Biology 202, 645–653 (1999)
Printed in Great Britain © The Company of Biologists Limited 1999
JEB1881
REVIEW
INDUCIBLE NO SYNTHASE: ROLE IN CELLULAR SIGNALLING
KARL-FRIEDRICH BECK, WOLFGANG EBERHARDT, STEFAN FRANK, ANDREA HUWILER,
UDO K. MEßMER, HEIKO MÜHL AND JOSEF PFEILSCHIFTER*
Zentrum der Pharmakologie, Klinikum der Johann Wolfgang Goethe-Universität, Theodor-Stern-Kai 7, D-60590
Frankfurt am Main, Germany
*e-mail: [email protected]
Accepted 18 December 1998; published on WWW 17 February 1999
Summary
The discovery of endothelium-derived relaxing factor
intercellular messenger that acutely affects important
and its identification as nitric oxide (NO) was one of the
signalling pathways and, on a more long-term scale,
most exciting discoveries of biomedical research in the
modulates gene expression in target cells. These actions
1980s. Besides its potent vasodilatory effects, NO was
will form the focus of the present review.
found under certain circumstances to be responsible for
the killing of microorganisms and tumour cells by
activated macrophages and to act as a novel,
Key words: nitric oxide synthase, cell signalling, isoform, inducible
enzyme, apoptosis, nitric oxide, gene expression, guanylate cyclase,
unconventional type of neurotransmitter. In 1992, Science
protein kinase, protein phosphatase, transcription factor, redox
picked NO as the ‘Molecule of the Year’, and over the past
regulation.
years NO has become established as a universal
Introduction
In mammals, the synthesis of NO is catalysed by nitric
oxide synthase (NOS), which exists in at least three distinct
isoforms (Nathan and Xie, 1994). NOS catalyses the
oxidation of the amino acid L-arginine to give rise to citrulline
and NO. Molecular cloning and sequence analysis has
revealed the existence of three distinct NOS isotypes that are
either constitutively expressed in endothelial cells (eNOS)
and neurones (nNOS) or are induced (iNOS) by endotoxin
and by inflammatory cytokines such as interleukin 1 (IL-1)
or tumour necrosis factor α (TNF-α) in macrophages and
many other cell types (Moncada et al., 1991; Nathan and Xie,
1994). iNOS requires a delay of 6–8 h before the onset of NO
production but, once induced, this enzyme is active for hours
to days and produces NO in 1000-fold larger quantities than
the constitutive enzymes eNOS and nNOS. At low
concentrations, NO stimulates guanylate cyclase activity and
triggers the formation of cyclic GMP (cGMP), an important
messenger mediating physiological functions of NO such as
vascular homeostasis. Higher concentrations of NO produced
by iNOS interact with thiol groups or transition-metalcontaining proteins and can alter protein function or initiate
gene expression to protect cells. There is a continuous shift
at even higher concentrations of NO towards cell damage or
apoptosis, with other factors in the microenvironment of a
cell critically influencing the final outcome (Brüne et al.,
1998).
Regulation of iNOS expression
Two important observations were reported by different
groups when working on iNOS expression. First,
lipopolysaccharide (LPS) and interferon-γ (IFN-γ) are strong
inducers of iNOS in monocytes, whereas the cytokines TNFα and IL-1β have, if any, only marginal effects. In contrast,
most tissue-derived cells including hepatocytes, mesangial
cells, vascular smooth muscle cells, myocytes and pancreatic
β-cells, to name just a few, are more sensitive to the induction
of iNOS when challenged with TNF-α or, in particular, with
IL-1β. In nearly all cell types, LPS, IFN-γ, IL-1β and TNF-α
enhance iNOS expression synergistically. Second, rodent cells
can more easily be triggered to express iNOS than human cells.
For example, IL-1β is a strong stimulus for iNOS transcription
in rat mesangial cells (Pfeilschifter and Schwarzenbach, 1990),
whereas in human mesangial cells considerable iNOS
expression occurs only when combinations of cytokines were
administered as a cocktail (Nicolson et al., 1993). Conflicting
results were obtained concerning the role of cyclic AMP
(cAMP) in iNOS expression. Whereas in rat vascular smooth
muscle cells and rat mesangial cells, cAMP is a strong inducer
of iNOS mRNA (Koide et al., 1993; Mühl et al., 1994; Kunz
et al., 1994), cAMP reduces iNOS expression in other rodent
cells. Recently, other stimulators of iNOS expression such as
IL-2, IL-12, IL-18 and IFN-α have been described (Kröncke
et al., 1995).
Three main signalling pathways are thought to be
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K.-F. BECK AND OTHERS
responsible for iNOS expression. Induction of iNOS in murine
macrophages is mediated by γ-activated sites and IFN-γresponsive elements in the iNOS promoter (Xie et al., 1993;
Martin et al., 1994). In rat mesangial cells, binding of the
nuclear factor κB (NF-κB) at the appropriate site on the iNOS
promoter is essential for the induction of iNOS by IL-1β
(Eberhardt et al., 1994, 1998). In contrast, endothelin-1 inhibits
cytokine-induced iNOS expression without affecting NF-κB
binding, suggesting additional mechanisms that are essential
for cytokine-induced iNOS expression (Beck and Sterzel,
1996). For the induction of iNOS by cAMP, enhanced binding
of the transcription factors CAAT/enhancer-binding protein
(C/EBP) and cAMP-responsive element-binding protein
(CREB) on the iNOS promoter has been reported (Eberhardt
et al., 1998).
Many inflammatory diseases are accompanied by an
increase in NO production and, in appropriate animal models,
a beneficial action of iNOS inhibitors has been demonstrated.
Therefore, many groups are currently studying physiological
or synthetic agents that inhibit cytokine-induced iNOS
expression at the transcriptional level (Pfeilschifter et al.,
1996). As a common theme, cytokine-induced iNOS
expression is inhibited by agents that diminish activation or
binding of NF-κB. This has been shown for a variety of
pharmacological substances, including dithiocarbamates
(Eberhardt et al., 1994), dexamethasone (Pfeilschifter and
Schwarzenbach, 1990; Kunz et al., 1996) and cyclosporin A
(Mühl et al., 1993; Kunz et al., 1995). These novel therapeutic
approaches may provide new methods for treating
inflammatory diseases associated with pathological NO
overproduction.
Soluble guanylate cyclase as a target of NO action
The physiologically most relevant action of NO is the
activation of soluble guanylate cyclase by nitrosation of its
haem moiety (Ignarro, 1990). The subsequent increase in
cGMP level alters the activity of three main target proteins: (i)
cGMP-regulated ion channels, (ii) cGMP-regulated
phosphodiesterases, and (iii) cGMP-dependent protein kinases
(for a review, see Schmidt et al., 1993).
The molecular basis of the sensory systems of visualization
and olfaction is related to the action of cation channels which
are regulated by cellular cGMP levels. These proteins have
one binding site for cGMP. Binding of cGMP critically
determines the function of these sensors. Activation of the
vertebrate rod photoreceptor cells by light results in
hydrolysis of cGMP. The drop in cellular cGMP
concentration leads to closure of a cGMP-regulated cation
channel with subsequent hyperpolarization of the cell; this is
the primary neuronal response in visualization (Dhallan et al.,
1992). Activation of odorant receptors in olfactory cilia is
likely to be connected to an inositol-trisphosphate-mediated
rise in intracellular Ca2+ concentration and activation of a
constitutive NOS. NO increases cGMP levels in adjacent
neurones, which in turn mediates further activation of the
odorant signalling pathway by opening Ca2+ channels (Breer
and Shephard, 1993).
Phosphodiesterases play a key role in controlling the actions
of the second messengers cAMP and cGMP. Of the six family
members of phosphodiesterases, the enzyme activity of type II
and type III proteins is directly regulated by binding of cGMP
to conserved non-catalytic cGMP binding domains. Type II
phosphodiesterases are stimulated by cGMP binding, whereas
the type III enzymes are inhibited by cGMP. Therefore, cGMP
can increase cAMP levels via activation of type III
phosphodiesterase. In contrast, activation of type II enzymes
increases cAMP hydrolysis and accordingly decreases cAMP
concentrations (Schmidt et al., 1993).
Two major classes of cGMP-dependent protein kinases
have been identified, the soluble type I (GKI) and the
membrane-bound type II (GKII) enzymes. GKI is further
subdivided in α and β isoforms. GKI exists as a dimer,
whereas GKII is a monomer. Protein analysis of GKI
revealed a dimerization domain which includes an
autophosphorylation and an autoinhibitory site, two cGMP
binding domains and a catalytic domain. GKII is
predominantly expressed in the intestinal epithelial brush
border and is involved in intestinal Cl− absorption and
secretion. GKI is expressed in various tissues, and its role in
physiology is much better characterized. In myocytes,
activation of GKI modulates contractility by inhibiting an
inward Ca2+ current. In the kidney, GKI is expressed in
different cell types such as mesangial cells, smooth muscle
cells, microvascular pericytes and myofibroblasts.
Functionally, it has been demonstrated that GKI regulates an
amiloride-sensitive Na+ channel in the inner medullary
collecting duct. In the cerebellum, GKI is highly expressed
in Purkinje cells. However, its role in these cells is not yet
clear. Furthermore, in smooth muscle cells and platelets, GKI
inhibits agonist-induced elevations in Ca2+ concentration and
thus modulates smooth muscle contraction and platelet
activation (Schmidt et al., 1993).
Protein kinases and phosphatases as targets of NO action
The first evidence for an effect of NO on protein kinase
cascades was reported by Lander et al. (1993a), who found
that, in human peripheral blood mononuclear cells, NOgenerating compounds stimulated a membrane-associated
protein tyrosine phosphatase activity which led to a
dephosphorylation and activation of the src family protein
tyrosine kinase p56lck, which is critically involved in T cell
activation.
These authors later showed that NO activates all three
parallel mitogen-activated protein kinase (MAPK) cascades
(Fig. 1) in Jurkat T cells, i.e. the stress-activated protein
kinase/c-Jun N-terminal kinase (SAPK/JNK) cascade, the
stress-activated p38 MAPK cascade and the classical
ERK/MAPK cascade (Lander et al., 1996). A similar
stimulatory effect of NO on the different MAPK cascades was
observed in glomerular mesangial cells and endothelial cells
Role of inducible NO synthase in cell signalling
Fig. 1. NO modulation of signal flow in the
three main mitogen-activated protein kinase
(MAPK) pathways and the Janus kinase
(JAK)/signal transducer and activator of
transcription (STAT) cascade. Cdc42, a
member of the Ras superfamily of small GTPbinding proteins; ERK, extracellular signalregulated kinase; IL-1, interleukin 1; JAK,
Janus kinase; JNK, c-Jun N-terminal kinase;
LPS, lipopolysaccharide; MAPK, mitogenactivated protein kinase; MAPKK, MAPK
kinase; MAPKKK, MAPKK kinase; MEK,
MAPK or ERK kinase; MEKK, MEK kinase;
MKK, mitogen-activated protein kinase
kinase; PAK, p21-activated protein kinase;
p53, a tumour suppressing protein; R,
receptor; RK, reactivating protein kinase; Rac,
a member of the Ras superfamily of small
GTP-binding proteins; Raf, a serine/threonine
protein kinase; Ras, small GTP-binding
protein; SAPK, stress-activated protein
kinase; SEK, SAPK kinase; SMase,
sphingomyelinase; STAT, signal transducer
and activator of transcription; TAK,
transforming growth factor β-activated protein
kinase; TAO, thousand and one amino acid
protein kinase; TNF, tumour necrosis factor.
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Growth factors, NO
Cytokines (TNF-α, IL-1)
NO
SMase
Heat shock,
IL-1, LPS
NO
R
R
Ras
Rac/Cdc42
PAKs
JAKs
Raf
MEKK1–3
MEK1/2
SEK1/MKK4
TAK1/TAO
MKK3/6
MAPKKK
MAPKK
STATs
ERK1/2
(Pfeilschifter and Huwiler, 1996; Callsen et al., 1998; A.
Huwiler and J. Pfeilschifter, in preparation).
Mechanistically, activation of the different MAPK cascades
by NO may occur either by direct alterations to the kinases
themselves or by modulation of an upstream factor such as the
small GTP-binding protein p21ras (Lander et al., 1995; Yun et
al., 1998). The activation of p21ras by NO was reported to be
direct, reversible and initiated by S-nitrosylation of a critical
cysteine residue of p21ras that stimulates guanine nucleotide
exchange by interacting with a region of p21ras which normally
interacts with guanine nucleotide exchange factors (GEFs)
(Lander et al., 1995). Other potential direct targets for NO and
upstream factors in the MAPK cascades are the heterotrimeric
G-proteins. NO greatly enhanced GTPase activity of Gsα and
Giα both in T cells and in vitro when pure recombinant proteins
were used (Lander et al., 1993b).
Alternatively, NO may directly modulate members of the
different MAPK cascades and cause either activation or
inhibition of the enzymes. The NO-releasing compound Snitrosoglutathione (GSNO) was found to cause S-nitrosylation
and inactivation of the JNK2/SAPK cascade in vitro and may
thereby exert its antiapoptotic effect in B-lymphocytes (So et
al., 1998). Similarly, the NO-generating compound
diethylenetriamine nitric oxide inhibits JNK activation in
pheochromocytoma (PC12) cells (Park et al., 1996).
Another family of protein kinases that plays a key role in
several signal-transducing pathways is the family of protein
kinase C (PKC) isoenzymes. Reactive oxygen species as well
as NO have been reported to increase PKC activity (Klann et
al., 1998). In contrast, NO was found to suppress PKC activity
JNKs/SAPKs
p38/RK
MAPK
Cell responses
in mesangial cells (Gopalakrishna et al., 1993; Studer et al.,
1996). However, neither of these studies gave any evidence for
a direct effect of NO on the activation state of PKC.
Recently, an additional class of protein kinases was shown
to be directly modulated by NO in vitro and in vivo, the Janus
kinases (JAKs). Both JAK2 and JAK3 autokinase activity were
found to be inhibited by NO, presumably by oxidation of
crucial dithiols to disulphides (Duhe et al., 1998). Such an
inhibition of JAK activity in vivo may contribute to the
immunosuppressive effects of NO because JAKs transmit
signals from almost all types of cytokine receptors.
Other possible targets for NO represent the family of
protein phosphatases. By direct interaction with this class of
enzyme, either an activation or inhibition of phosphatase
activity may be achieved, and this will lead to increased or
decreased phosphorylation of their target proteins which
include, importantly, members of the different MAPK
pathways. Activation of a membrane-bound phosphatase was
reported in T cells (Lander et al., 1993a). Furthermore,
protein tyrosine phosphatase activation was also observed in
rat aortic smooth muscle cells (Kaur et al., 1998). In contrast,
NO was reported to inactivate a low-molecular-mass protein
tyrosine phosphatase in vitro by S-nitrosylation of two
adjacent cysteine residues in the active site of the enzyme
(Caselli et al., 1994). Comparable data were described
recently for mesangial cells: NO was found directly to inhibit
a tyrosine phosphatase activity, leading to increased
phosphorylation and activation of the classical MAPKs
(Callsen et al., 1998). However, the identity of this tyrosine
phosphatase was not analysed further. Moreover, it has been
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K.-F. BECK AND OTHERS
reported that NO leads to an induction of MAPK
phosphatase-1 (MKP-1) mRNA in human embryonic lung
fibroblasts, which would suggest an increased MKP activity
and conversely a decreased MAPK activity in these cells
(Marquis and Demple, 1998).
In conclusion, these studies suggest that NO can, in
principle, deliver signals into all the major MAPK cascades
including the classical ERK, SAPK/JNK and p38 kinase
cascades as well as the JAK/signal transducer and activator of
transcription (STAT) pathway. An integration of signals will
lead to cell-type-specific responses that critically depend on
interactions between the individual constituents of a cell and
the components of the different signalling cascades. These
cascade events then trigger the phosphorylation of key nuclear
proteins, including transcription factors such as c-Jun, ternary
complex factors or STATs and, finally, perhaps lead to
alterations in gene expression.
Modulation of transcription factors and gene expression
by NO
The molecular mechanisms by which NO affects gene
expression are still poorly understood, and an ultimate ‘NOresponsive promoter element’ has yet to be identified.
However, increasing evidence is accumulating that NO
preferentially alters transcription factors that are sensitive to
changes in the cellular oxidation–reduction (redox) status. At
least two well-defined transcription factors, NF-κB and
activator protein 1 (AP-1) were shown to be regulated by the
intracellular redox state (Sen and Packer, 1996). NO is a
molecule with both anti-oxidant and pro-oxidant properties
depending on the availability and concentration of potential
reaction partners such as superoxide and hydrogen peroxide or
other reactive oxygen species (ROS). This may explain the
disparate observations that in some cells, including human
blood mononuclear cells and rat glomerular mesangial cells,
treatment with NO donors such as sodium nitroprusside (SNP),
S-nitroso-N-acetylpenicillamine (SNAP) and GSNO resulted
in enhanced binding activity of NF-κB family members
(Lander et al., 1993a; W. Eberhardt, unpublished results),
whereas in other cell types activation of NF-κB binding
following cytokine treatment could be inhibited by treatment
with NO donors (Peng et al., 1995). Endogenous NO may
function to scavenge reactive oxygen intermediates, thereby
inhibiting activation of NF-κB, as has been shown for the
expression of genes coding for monocyte chemoattractant
protein 1 (MCP-1) and macrophage colony stimulating factor
1 (CSF-1) (Zeiher et al., 1994; Peng et al., 1995). However, a
universal hypothesis for activation of NF-κB by ROS seems
uncertain and may be restricted to specific cell types (Brennan
and O’Neill, 1995). Alternative mechanisms for NF-κB
inhibition by NO include increased expression and nuclear
translocation of inhibitor protein IκBα, as demonstrated for
VCAM-1 gene expression in human endothelial cells (Spiecker
et al., 1997). A direct inhibition of the DNA-binding activity
of NF-κB family proteins by NO has been demonstrated in
vitro using recombinant p50/p65 proteins (Matthews et al.,
1996). It was observed that NO modifies a conserved cysteine
residue within the N-terminal region of the transcription factor
thought to be responsible for DNA binding, dimerization and
nuclear translocation.
A direct in vitro modification of transcriptional activators
has also been demonstrated for AP-1 (Tabuchi et al., 1994).
Single conserved cysteine residues within the DNA-binding
domains of c-Fos and c-Jun, the major components of AP-1,
seem to be responsible for redox regulation of AP-1 activity.
Nitrosylation of critical cysteines by NO may account for the
increase in junB and c-fos gene expression observed in some
mammalian cell types. Generally, protein modifications may
reflect a common mechanism for the activation of the phorbol
ester 12-O-tetradecanoylphorbol-13-acetate (TPA) responsive
element (TRE)-containing gene promoters by NO-releasing
agents and by cGMP analogues (Pilz et al., 1995).
Other molecular mechanisms by which NO may directly
influence transcription factors involve the destruction of
zinc–sulphur clusters and the release of zinc from
metallothioneins,
thereby
inhibiting
zinc-finger-type
transcription factors. NO-mediated nitrosylation of the zincfinger domains results in the formation of disulphide bonds and
the loss of in vitro DNA binding capacity, as demonstrated for
the yeast transcription factor LAC9 (Kröncke et al., 1994). It
seems quite plausible that NO may affect mammalian zincfinger transcription factors in a similar way.
During the last few years, an increasing number of genes
have been shown to be under regulatory control by nitric oxide,
including those for extracellular matrix proteins
(Chatziantoniou et al., 1998) and the corresponding proteases
(Sasaki et al., 1998), growth factors (Sasaki et al., 1998;
Tsurumi et al., 1997; Chin et al., 1997), cytokines (VanDervort
et al., 1994), chemokines (Villarete and Remick, 1995; Mühl
and Dinarello, 1997), receptors (Ichiki et al., 1998), enzymes
(Hartsfield et al., 1997; Mühl and Pfeilschifter, 1995) or even
hormones (Wang et al., 1998).
The gene for interleukin-8 (IL-8) has been revealed to be
under transcriptional control by NO. In human endothelial
cells, TNF-α-stimulated IL-8 production was inhibited by the
NOS inhibitor (L)-NG-nitroarginine methylester (L-NAME) in
a dose-dependent manner. Moreover, exogenously added NO
donors induced IL-8 expression in these cells (Villarete and
Remick, 1995). Besides IL-8, TNF-α is likely to be induced in
a paracrine manner by endothelial and smooth-muscle-derived
NO in human neutrophils (VanDervort et al., 1994).
Furthermore, expression of macrophage inflammatory protein
1α (MIP-1α), another member of the chemokine family, was
directly dependent on lipopolysaccharide-induced NO
synthesis in peripheral blood mononuclear cells (Mühl and
Dinarello, 1997).
Another group of target genes for NO action has been
detected recently: the extracellular matrix proteins and their
degrading enzymes, the matrix metalloproteinases (MMPs). In
the kidney, accumulation of extracellular matrix is often a
hallmark of chronic diseases eventually leading to the
Role of inducible NO synthase in cell signalling
development of glomerulosclerosis. Within this pathological
process, NO triggers the inhibition of collagen type I gene
expression in afferent arterioles and glomeruli. Hypertensive
transgenic mice harbouring a luciferase reporter gene under the
control of the collagen I-α2 chain promoter revealed a
pronounced four- to tenfold increase in promoter activity and
subsequent deposition of collagen I in the afferent arterioles
and glomeruli, respectively, in the presence of systemically
applied L-NAME (Chatziantoniou et al., 1998). Furthermore,
IL-1β-stimulated MMP-9 expression is triggered via an
autocrine NO loop in articular chondrocytes (Sasaki et al.,
1998).
Regulation of vascular endothelial growth factor (VEGF), a
growth factor mediating angiogenesis and vascular
permeability, was found to be modulated by NO. VEGF is
upregulated in smooth muscle cells of arterial walls in response
to endothelial injury. This up-regulation is inhibited by NO
donors known to interfere with the binding of AP-1 to the
VEGF promoter. This mechanism constitutes a negative
feedback loop in which NO released from the restored
endothelium shuts off VEGF expression (Tsurumi et al., 1997).
The development of a new blood vessel network connected to
the circulation is a crucial stage in tumour growth. VEGF
expression is induced by NO-donating agents in glioblastoma
and hepatocarcinoma cells. For both cell lines, however, NOinduced gene expression is mediated through the activation of
guanylate cyclase (Chin et al., 1997).
Finally, NO is even able to trigger transcription of its own
biosynthetic machinery: it was found to increase IL-1βinduced iNOS gene expression at the transcriptional level in
mesangial cells. Inhibition of NO synthesis clearly reduced IL1β-stimulated iNOS expression, suggesting that NO functions
in a positive feedback loop that speeds up and strengthens its
own biosynthesis (Mühl and Pfeilschifter, 1995). This potent
amplification mechanism may form the basis for the excessive
formation of NO in acute and chronic inflammatory diseases.
Powerful negatively acting regulatory pathways are required to
terminate amplification loops such as the one described above.
The most direct way to suppress NO-triggered amplification of
iNOS expression is by substrate depletion. Moreover, NO can
initiate apoptotic cell death in glomerular mesangial cells and
various other cell types (Mühl et al., 1996; Pfeilschifter and
Huwiler, 1996; Sandau et al., 1997; Brüne et al., 1998). This
may provide a delayed shut-off mechanism for the production
of NO by mesangial cells.
Apopotosis: cell signalling by redox regulation
Although ‘nitric oxide’ was treated as equivalent to NO•
under physiological conditions and with regard to therapeutic
aspects using various NO donors, NO can be interconverted
among different redox forms such as the nitrosonium cation
(NO+), the nitric oxide free radical (NO•) and the nitroxyl
anion (NO−), each with distinctive chemistry (Stamler, 1994).
Moreover, from a biological standpoint, the various and rapid
reactions of NO with oxygen, e.g. the reaction of NO with O2−
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in aqueous solution yielding peroxynitrite (ONOO−), and with
metal ions determine its ability to modulate signal
transduction. With respect to the complex NO redox chemistry,
innumerable studies have been undertaken to elucidate the
molecular switching mechanisms that transduce the chemical
(radical) signal into a functional cell response. NO-responsive
signalling proteins (transcription factors, enzymes, receptors,
ion channels) are usually characterized by the existence of thiol
and tyrosine residues strategically located at either allosteric or
active sites. Modification of thiol residues by NO resulting in
the formation of S-nitrosothiols has been described for many
different enzymes, such as the glycolytic enzyme
glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and
signal transduction components, such as the ras oncogene
product p21 (p21ras), and PKC predominantly inhibits its
enzymatic activities (see above). Regulation of GAPDH by NO
and ONOO− received attention because endogenously released
NO as well as NO supplied by NO donors stimulated Snitrosylation of GAPDH (Mohr et al., 1994). This modification
subsequently resulted in the transfer and covalent binding of
NADH to the cysteine residue accompanied by the inhibition
of enzymatic activity in vitro and in vivo (Dimmeler et al.,
1994; Meßmer and Brüne, 1996a) and an alteration in
intracellular distribution (Meßmer and Brüne, 1996a; Galli et
al., 1998). Comparably, signalling components were
differentially regulated by NO and its oxidation products
through S-nitrosylation. The biological activity of PKC and the
transcription factor AP-1 were blocked by a high-output NO
synthase, whereas NO induced activation of the pertussistoxin-sensitive G protein and p21ras (see above).
In addition to S-nitrosylation, nitration of tyrosine residues
is another class of reaction through which NO and ONOO−
influence signal transduction. Although many proteins contain
tyrosine residues, factors such as the nature of the nitrating
agents (NO, ONOO−, NO2•, etc.), protein folding and the
presence of glutamate in the local environment may serve as
markers for tyrosine nitration rather than simply the number of
tyrosine residues (Ischiropoulos, 1998). One important in vivo
target reported recently is the mitochondrial manganese
superoxide dismutase (Mn-SOD). In contrast to Cu/Zn-SOD,
which lacks tyrosine residues and therefore is not a target for
nitration, Mn-SOD enzymatic activity is blocked by the
exclusive nitration of Tyr 34 (Yamakura et al., 1998).
Similarly, prostacyclin synthase (Zou et al., 1997),
neurofilament L, actin and several other substrates have been
identified as in vivo protein targets. In addition to protein
nitration, N-nitrosation of DNA occurs when NO is released in
large amounts, and this reaction is considered to be a potential
toxic mechanism of NO• and other NO redox forms (Stamler,
1994).
The role in cell signalling of NO•- and NO•/O2−-derived
congenitors has been intensively studied for apoptotic cell
death. Since 1993, many different groups have described the
induction of apoptotic cell death following iNOS induction or
exogenous application of NO donors in different cell types
such as macrophages, mesangial cells and neurones (Brüne et
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K.-F. BECK AND OTHERS
al., 1998). Cell death by apoptosis is highly organized and
follows a universal pattern characterized by chromatin
condensation, DNA cleavage by an active endonuclease, cell
shrinkage, membrane blebbing and redistribution of
phosphatidylserine from the inner to the outer leaflet of the cell
membrane, an important mechanism for the recognition of
apoptotic cells by surrounding phagocytes. Following the
initial observations that endogenously derived NO• and the
application of various NO donors (e.g. SNP, GSNO) caused
apoptotic manifestations in different in vitro models, important
signalling pathways that provide mechanistic insights were
characterized in the mouse RAW 264.7 macrophage cell line.
One of the first signals to be established in NO-mediated cell
death was an accumulation of the tumour suppressor p53
(Meßmer et al., 1994). p53 accumulation occurred as an early
response following iNOS activation or NO donor treatment and
resulted from a decreased rate of protein degradation (Meßmer
and Brüne, 1996b). Initially described in RAW 264.7
macrophages, the requirement for p53 has been confirmed in
several other cellular systems (Brüne et al., 1998). The
accumulation of p53, an established guardian of the genome,
reflects DNA damage as an ultimate result of high levels of
NO production and places oxidative and nitrosative DNA
damage into the early apoptotic pathways. Following p53
accumulation, activation of caspases was described in NOmediated apoptosis (Meßmer et al., 1998). Caspases are a
family of cysteine proteases that assist in apoptotic cell death
by cleaving distinct cellular proteins such as the poly(ADPribose) polymerase (PARP), lamin, PKC-δ and MAPK kinase
(MEK) kinase 1 (MEKK1), which are subsequently selectively
inactivated or activated. PARP cleavage and caspase-3
activation, but not p53 upregulation, were prevented by Bcl-2
gene transfer (Meßmer et al., 1996).
It is important to note that different cells vary greatly in their
sensitivity to NO, and in this context the response of a cell can
be modulated by the simultaneous release of oxygen radicals.
For example, glomerular mesangial cells (Fig. 2) respond to
NO donor treatment with an induction of apoptosis, as do
RAW 264.7 macrophages, but in contrast to macrophages,
mesangial cells remain highly resistant to iNOS induction by
IL-1β (Nitsch et al., 1997). Whether endogenously produced
NO can fulfill the function of an apoptosis inducer may
critically depend on a balance between the reactive nitrogen
and oxygen species produced by mesangial cells. Appropriate
generation of O2− simultaneously with NO will therefore block
NO-donor-induced apoptosis in mesangial cells (Sandau et al.,
1997). Disturbing the NO/O2− balance by superinduction of IL1β-mediated NO release by basic fibroblast growth factor may
therefore be associated with increased mesangial cell apoptosis
(Kunz et al., 1997). Assuming that the simultaneous generation
of NO/O2− would result in ONOO− formation, we suggest that
the production of ONOO− represents a protective mechanism.
Supporting evidence comes from detailed experiments using
RAW 264.7 macrophages (Brüne et al., 1997), although
contradictory reports describe ONOO− as an inducer of
apoptotic cell death (Beckman and Koppenol, 1996).
Although NO is established as a potent inducer of apoptosis
in certain cell types, contradictory effects have been reported,
with NO displaying anti-apoptotic effects in lymphocytes, Bcells, eosinophils, hepatocytes and endothelial cells (for a
review, see Dimmeler and Zeiher, 1997). One major difference
from the apoptosis-inducing system is the amount of NO
required for these anti-apoptotic effects. Anti-apoptotic
activities of NO were observed at concentrations that are only
2–10 % of those needed for the induction of apoptosis
(Haendeler et al., 1997). Most interesting, but yet unresolved,
are the precise mechanisms responsible for the anti-apoptotic
effects of NO. Several groups reported and favoured a direct
inhibition of caspases by reversible S-nitrosylation and
therefore an interaction between NO•- and NO•/O2−-derived
congenitors and the executioners of apoptotic signal
transduction (Li et al., 1997; Haendeler et al., 1997; Dimmeler
TGF- β
PDGF
Steroids, CsA
Epithelial cells
Fig. 2. Schematic representation of the
inflammatory process in glomerulonephritis,
focusing on the role of NO generated by
glomerular mesangial cells and macrophages.
bFGF, basic fibroblast growth factor; C/EBP,
CCAAT/enhancer binding protein family of
transcription factors; CsA, cyclosporin A;
IFN-γ, interferon-γ; IL-1, interleukin 1; iNOS,
inducible nitric oxide synthase; LPS,
lipopolysaccharide; NF-κB, nuclear factor
κB; PDGF, platelet-derived growth factor;
TGF, transforming growth factor; TNF,
tumour necrosis factor.
IL-1
+ TNF-α
+ bFGF
+ Forskolin
LPS
+IFN-γ
NF-κ B
C/EBP
DNA
mRNA
iNOS
NO
Mesangial cells
DNA
Endothelial cells
iNOS
Macrophages
TNF-α
LPS
Role of inducible NO synthase in cell signalling
and Zeiher, 1997). Although a tempting hypothesis, questions
remain as to the in vivo relevance of S-nitrosylation of caspases
by NO. Uncertainties arise from differences between purified
enzymes or cytosolic cell extracts under strong reducing
conditions and the microenvironment of the enzymes in an
intact cell. Furthermore, there are striking differences in NO
donor concentrations required for in vitro S-nitrosylation of
crude caspases, which are 100- to 1000-fold higher than those
needed for cell culture experiments (Haendeler et al., 1997). In
general, one should consider that inhibition of an apoptotic
signalling cascade upstream of caspases will also prevent
caspase activation. Therefore, stress responses, induction of
heat-shock proteins and defence enzymes, such as Mn-SOD or
Cu/Zn-SOD, and activation of anti-apoptotic signalling
components provide alternative mechanisms for cell
protection.
This debate highlights the fact that NO is a double-edged
sword which, when produced in small amounts, by the
constitutively expressed NOS isoenzymes, exerts a protective
effect. However, a high output of NO by the inducible iNOS
may exert deleterious effects. Moreover, it is worth mentioning
that the cellular responses of cells that produce NO
constitutively, e.g. endothelial cells, can differ markedly from
those of cells that do not (Harrison, 1997).
Perspectives
Since the initital report of NO activity (Furchgott and
Zawaski, 1980), enormous progress has been made over the
last two decades in the field of NO research. Whereas most
physiological responses triggered by moderate concentrations
of NO are mediated by activation of soluble guanylate cyclase
and the subsequent production of cGMP as the principal
signalling messenger, recent studies have provided a wealth of
evidence for alternative signalling pathways in which
concentrations of NO are high. These signals operate in part
through redox-sensitive regulation of transcription factors and
gene expression and alter, on a more long-term basis, the
capacity of a cell to deal with stress conditions. Crosscommunication with other pro-oxidant or anti-oxidant
mediators will critically influence the fate of a cell under
pathological conditions when iNOS is expressed. It will be an
exciting challenge to unravel this delicate network of
interactions to yield the desired mechanistic insights needed
for the development of efficacious novel therapies.
The work of the authors was supported by the Deutsche
Forschungsgemeinschaft (SFB 553) and the Commission of
the European Union (Biomed 2, PL950979).
References
Beck, K. F. and Sterzel, R. B. (1996). Cloning and sequencing of
the proximal promoter of the rat iNOS gene: activation of NFκB is
not sufficient for transcription of the iNOS gene in rat mesangial
cells. FEBS Lett. 394, 263–267.
651
Beckman, J. S. and Koppenol, W. H. (1996). Nitric oxide,
superoxide and peroxynitrite: the good, the bad and the ugly. Am.
J. Physiol. 271, C1424–C1437.
Breer, H. and Shepherd, G. M. (1993). Implications of the
NO/cGMP system for olfaction. Trends Neurosci. 1, 5–9.
Brennan, P. and O’Neill, L. A. J. (1995). Effects of oxidants and
antioxidants on nuclear factor κB activation in three different cell
lines: evidence against a universal hypothesis involving oxygen
radicals. Biochim. Biophys. Acta 1260, 167–175.
Brüne, B., Götz, C., Meßmer, U. K., Sandau, K., Hirvonen, M. R.
and Lapetina, E. G. (1997). Superoxide formation and
macrophage resistance to nitric oxide mediated apoptosis. J. Biol.
Chem. 272, 7253–7258.
Brüne, B., von Knethen, A. and Sandau, K. B. (1998). Nitric oxide
and its role in apoptosis. Eur. J. Pharmac. 351, 261–272.
Callsen, D., Pfeilschifter, J. and Brüne, B. (1998). Rapid and
delayed p42/p44 MAPK activation by nitric oxide: the role of
cGMP and tyrosine phosphatase inhibition. J. Immunol. 161,
4852–4858.
Caselli, A., Camici, G., Manao, G., Moneti, G., Pazzagali, L.,
Cappugi, G. and Ramponi, G. (1994). Nitric oxide causes
inactivation of the low molecular weight phosphotyrosine protein
phosphatase. J. Biol. Chem. 269, 24878–24882.
Chatziantoniou, C., Boffa, J. J., Ardaillou, R. and Dussaule, J. C.
(1998). Nitric oxide inhibition induces early activation of type I
collagen gene in renal resitance vessels and glomeruli in transgenic
mice. J. Clin. Invest. 101, 2780–2789.
Chin, K., Kurashima, Y., Ogura, T., Tajiri, H., Yoshida, S. and
Esumi, H. (1997). Induction of vascular endothelial growth factor
by nitric oxide in human glioblastoma and hepatocellular
carcinoma cells. Oncogene 15, 437–442.
Dhallan, R. S., Macke, J. P., Eddy, R. L., Shows, T. B., Reed, R.
R., Yau, K.-W. and Nathans, J. (1992). Human rod photoreceptor
cGMP-gated channel: amino acid sequence, gene structure and
functional expression. J. Neurosci. 12, 3248–3256.
Dimmeler, S., Meßmer, U. K., Tiegs, G. and Brüne, B. (1994).
Modulation of glyceraldehyde-3-phosphate dehydrogenase in
Salmonella abortus equi lipopolysaccharide-treated mice. Eur. J.
Pharmac. Mol. Pharmac. 267, 105–112.
Dimmeler, S. and Zeiher, A. M. (1997). Nitric oxide and apoptosis:
another paradigm for the double-edged role of nitric oxide. Nitric
Oxide: Biol. Chem. 1, 275–281.
Duhe, R. J., Evan, G. A., Erwin, R. A., Kirken, R. A., Cox, G. W.
and Farrar, W. L. (1998). Nitric oxide and the redox regulation
of Janus kinase activity. Proc. Natl. Acad. Sci. USA 95, 126–131.
Eberhardt, W., Kunz, D. and Pfeilschifter, J. (1994). Pyrrolidine
dithiocarbamate differentially affects interleukin 1 beta- and
cAMP-induced nitric oxide synthase expression in rat renal
mesangial cells. Biochem. Biophys. Res. Commun. 200, 163–170.
Eberhardt, W., Plüss, C., Hummel, R. and Pfeilschifter, J. (1998).
Molecular mechanisms of inducible nitric oxide synthase gene
expression by IL-1β and cAMP in rat mesangial cells. J. Immunol.
160, 4961–4969.
Furchgott, R. F. and Zawadski, J. V. (1980). The obligatory role of
endothelial cells in the relaxation of arterial smooth muscle by
acetylcholine. Nature 288, 373–376.
Galli, F., Rovidati, S., Ghibelli, L. and Canestrari, F. (1998). SNitrosylation of glyceraldehyde-3-phosphate dehydrogenase
decreases the enzyme affinity to the erythrocyte membrane. Nitric
Oxide: Biol. Chem. 2, 17–27.
Gopalakrishna, R., Chen, Z. H. and Gundimeda, U. (1993). Nitric
652
K.-F. BECK AND OTHERS
oxide and nitric oxide-generating agents induce a reversible
inactivation of protein kinase C activity and phorbol ester binding.
J. Biol. Chem. 268, 27180–27185.
Haendeler, J., Weiland, U., Zeiher, A. M. and Dimmeler, S.
(1997). Effects of redox-related congeners of NO on apoptosis and
caspase-3 activity. Nitric Oxide: Biol. Chem. 1, 282–293.
Harrison, D. G. (1997). Cellular and molecular mechanisms of
endothelial dysfunction. J. Clin. Invest. 100, 2153–2157.
Hartsfield, C. L., Alam, J., Cook, J. L. and Choi, A. M. (1997).
Regulation of heme oxygenase-1 gene expression in vascular
smooth muscle cells by nitric oxide. Am. J. Physiol. 273,
L980–L988.
Ichiki, T., Usui, M., Kato, M., Funakoshi, Y., Ito, K., Egashira, K.
and Takeshita, A. (1998). Downregulation of angiotensin II type
1 receptor gene transcription by nitric oxide. Hypertension 31,
342–348.
Ignarro, J. J. (1990). Biosynthesis and metabolism of endotheliumderived nitric oxide. Annu. Rev. Pharmac. Toxicol. 30, 535–560.
Ischiropoulos, H. (1998). Biological tyrosine nitration: a
pathophysiological function of nitric oxide and reactive oxygen
species. Arch. Biochem. Biophys. 356, 1–11.
Kaur, K., Yao, J., Pan, X., Matthews, C. and Hassid, A. (1998).
NO decreases phosphorylation of focal adhesion proteins via
reduction of Ca in rat aortic smooth muscle cells. Am. J. Physiol.
274, H1613–H1619.
Klann, E., Roberson, E. D., Knapp, L. T. and Sweatt, J. D. (1998).
A role for superoxide in protein kinase C activation and induction
of long-term potentiation. J. Biol. Chem. 273, 4516–4522.
Koide, M., Kawahara, Y., Nakayama, I., Tsuda, T. and
Yokoyama, M. J. (1993). CAMP-elevating agents induce an
inducible type of nitric oxide synthase in cultured vascular smooth
muscle cells. J. Biol. Chem. 268, 24959–24966.
Kröncke, K. D., Fehsel, K. and Kolb-Bachofen, V. (1995).
Inducible nitric oxide synthase and its product nitric oxide, a small
molecule with complex biological activities. Biol. Chem. HoppeSeyler 376, 327–343.
Kröncke, K. D., Fehsel, K., Schmidt, T., Zenke, F. T., Dasting, I.,
Wesener, J. R., Bettermann, H., Breunig, K. D. and KolbBachofen, V. (1994). Nitric-oxide destroys zinc–sulfur clusters
inducing zinc release from metallothionein and inhibition of the
zinc finger-type yeast transcription activator LAC9. Biochem.
Biophys. Res. Commun. 200, 1105–1110.
Kunz, D., Mühl, H., Walker, G. and Pfeilschifter, J. (1994). Two
distinct pathways trigger the expression of inducible nitric oxide
synthase in rat renal mesangial cells. Proc. Natl. Acad. Sci. USA
91, 5387–5391.
Kunz, D., Walker, G., Eberhardt, W., Messmer, U. K., Huwiler,
A. and Pfeilschifter, J. (1997). Platelet-derived growth factor and
fibroblast growth factor differentially regulate interleukin 1β- and
cAMP-induced nitric oxide synthase expression in rat renal
mesangial cells. J. Clin. Invest. 100, 2800–2809.
Kunz, D., Walker, G., Eberhardt, W., Nitsch, D. and Pfeilschifter,
J. (1995). Interleukin 1β-induced expression of nitric oxide
synthase in rat renal mesangial cells is suppressed by cyclosporin
A. Biochem. Biophys. Res. Commun. 216, 438–446.
Kunz, D., Walker, G., Eberhardt, W. and Pfeilschifter, J. (1996).
Molecular mechanisms of dexamethasone inhibition of nitric oxide
synthase expression in interleukin 1β-stimulated mesangial cells:
evidence for the involvement of transcriptional and
posttranscriptional regulation. Proc. Natl. Acad. Sci. USA 93,
255–259.
Lander, H. M., Jacovina, A. T., Davis, R. J. and Tauras, J. M.
(1996). Differential activation of mitogen-activated protein
kinases by nitric-oxide-related species. J. Biol. Chem. 271,
19705–19709.
Lander, H. M., Ogiste, J. S., Paerce, S. F. A., Levi, R. and
Novogrodsky, A. (1995). Nitric oxide-stimulated guanine
nucleotide exchange on p21ras. J. Biol. Chem. 270, 7017–7020.
Lander, H. M., Sehajpal, P., Levine, D. M. and Novogrodsky, A.
(1993a). Activation of human peripheral blood mononuclear cells by
nitric oxide-generating compounds. J. Immunol. 150, 1509–1516.
Lander, H. M., Sehajpal, P. K. and Novogrodsky, A. (1993b).
Nitric oxide signaling: a possible role for G proteins. J. Immunol.
151, 7182–7187.
Li, J., Billiar, T. R., Talanian, R. V. and Kim, Y. M. (1997). Nitric
oxide reversibly inhibits seven members of the caspase family via
S-nitrosylation. Biochem. Biophys. Res. Commun. 240, 419–424.
Marquis, J. C. and Demple, B. (1998). Complex genetic response
of human cells to sublethal levels of pure nitric oxide. Cancer Res.
58, 3435–3440.
Martin, E., Nathan, C. and Xie, Q. W. (1994). Role of interferon
regulatory factor 1 in induction of nitric oxide synthase. J. Exp.
Med. 180, 977–984.
Matthews, J. R., Botting, C. H., Panico, M., Morris, H. R. and
Hay, R. T. (1996). Inhibition of NF-κB DNA binding by nitric
oxide. Nucleic Acids Res. 24, 2236–2242.
Meßmer, U. K., Ankarcrona, M., Nicotera, P. and Brüne, B.
(1994). p53 expression in nitric oxide-induced apoptosis. FEBS
Lett. 355, 23–26.
Meßmer, U. K. and Brüne, B. (1996a). Modification of macrophage
glyceraldehyde-3-phosphate dehydrogenase in response to nitric
oxide. Eur. J. Pharmac. 302, 171–182.
Meßmer, U. K. and Brüne, B. (1996b). Nitric oxide-induced
apoptosis: p53-dependent and p53-independent signalling
pathways. Biochem. J. 319, 299–305.
Meßmer, U. K., Reed, J. C. and Brüne, B. (1996). Bcl-2 protects
macrophages from nitric oxide-induced apoptosis. J. Biol. Chem.
271, 20192–20197.
Meßmer, U. K., Reimer, D. M. and Brüne, B. (1998). Protease
activation during nitric oxide-induced apoptosis: Dissection
between PARP and U1-70kDa cleavage. Eur. J. Pharmac. 349,
333–343.
Mohr, S., Stamler, J. S. and Brüne, B. (1994). Mechanisms of
covalent
modification
of
glyceraldehyde-3-phosphate
dehydrogenase at its active site thiol by nitric oxide, peroxynitrite
and related nitrosating agents. FEBS Lett. 348, 223–227.
Moncada, S., Palmer, R. M. J. and Higgs, E. A. (1991). Nitric
oxide: physiology, pathophysiology and pharmacology. Pharmac.
Rev. 43, 109–142.
Mühl, H. and Dinarello, C. A. (1997). Macrophage inflammatory
protein-1 alpha production in lipopolysaccharide-stimulated human
adherent blood mononuclear cells is inhibited by the nitric oxide
synthase inhibitor NG-monomethyl-L-arginine. J. Immunol. 159,
5063–5069.
Mühl, H., Kunz, D. and Pfeilschifter, J. (1994). Expression of nitric
oxide synthase in rat glomerular mesangial cells mediated by cyclic
AMP. Br. J. Pharmac. 112, 1–8.
Mühl, H., Kunz, D., Rob, P. and Pfeilschifter, J. (1993).
Cyclosporin derivatives inhibit interleukin 1 induction of nitric
oxide synthase in renal mesangial cells. Eur. J. Pharmac. 249,
95–100.
Mühl, H. and Pfeilschifter, J. (1995). Amplification of nitric oxide
Role of inducible NO synthase in cell signalling
synthase expression by nitric oxide in interleukin-1β-stimulated rat
mesangial cells. J. Clin. Invest. 95, 1941–1946.
Mühl, H., Sandau, K., Brüne, B., Briner, V. A. and Pfeilschifter,
J. (1996). Nitric oxide donors induce apoptosis in glomerular
mesangial cells, epithelial cells and endothelial cells. Eur. J.
Pharmac. 317, 137–149.
Nathan, C. and Xie, Q. (1994). Regulation of biosynthesis of nitric
oxide. J. Biol. Chem. 269, 13725–13728.
Nicolson, A. G., Haites, N. E., McKay, N. G., Wilson, H. M.,
MacLeod, A. M. and Benjamin, N. (1993). Induction of nitric
oxide synthase in human mesangial cells. Biochem. Biophys. Res.
Commun. 193, 1269–1274.
Nitsch, D. D., Ghilardi, N., Mühl, H., Nitsch, C., Brüne, B. and
Pfeilschifter, J. (1997). Apoptosis and expression of iNOS are
mutually exclusive in renal mesangial cells. Am. J. Path. 150,
889–900.
Park, D. S., Stefanis, L., Yan, C. Y. I., Farinelli, S. E. and Greene,
L. A. (1996). Ordering the cell death pathway. Differential effects
of Bcl-2, an interleukin-1-converting enzyme family protease
inhibitor and other survival agents on JNK activation in
serum/nerve growth factor-deprived PC12 cells. J. Biol. Chem. 271,
21898–21905.
Peng, H. B., Rajavashisth, T. B., Libby, P. and Liao, J. K. (1995).
Nitric oxide inhibits macrophage-colony stimulating factor gene
transcription in vascular endothelial cells. J. Biol. Chem. 270,
17050–17055.
Pfeilschifter, J., Eberhardt, W., Hummel, R., Kunz, D., Mühl, H.,
Nitsch, D., Plüss, C. and Walker, G. (1996). Therapeutic
strategies for the inhibition of inducible nitric oxide synthase –
potential for a novel class of antiinflammatory agents. Cell Biol.
Int. 20, 51–58.
Pfeilschifter, J. and Huwiler, A. (1996). Nitric oxide stimulates
stress-activated protein kinases in glomerular endothelial and
mesangial cells. FEBS Lett. 396, 67–70.
Pfeilschifter, J. and Schwarzenbach, H. (1990). Interleukin 1 and
tumor necrosis factor stimulate cGMP formation in rat renal
mesangial cells. FEBS Lett. 273, 185–187.
Pilz, R. B., Suhasini, M., Idriss, S., Meinkoth, J. L. and Boss, G.
R. (1995). Nitric oxide and cGMP analogs activate transcription
from AP-1-responsive promoters in mammalian cells. FASEB J. 9,
552–558.
Sandau, K., Pfeilschifter, J. and Brüne, B. (1997). The balance
between nitric oxide and superoxide determines apoptotic and
necrotic death of rat mesangial cells. J. Immunol. 158, 4938–4946.
Sasaki, K., Hattori, T., Fujisawa, T., Takahashi, K., Inoue, H. and
Takigawa, M. (1998). Nitric oxide mediates interleukin-1-induced
gene expression of matrix metalloproteinases and basic fibroblast
growth factor in cultured rabbit articular chondrocytes. J. Biochem.
123, 431–439.
Schmidt, H. H. H. W., Lohmann, S. M. and Walter, U. (1993). The
nitric oxide and cGMP signal transduction system: regulation and
mechanism of action. Biochim. Biophys. Acta 1178, 153–175.
653
Sen, C. K. and Packer, L. (1996). Antioxidant and redox regulation
of gene transcription. FASEB J. 10, 709–720.
So, H. S., Park, R. K., Kim, M. S., Lee, S. R., Jung, B. H., Chung,
S. Y., Jun, C. D. and Chung, H. T. (1998). Nitric oxide inhibits
c-Jun N-terminal kinase 2 (JNK2) via S-nitrosylation. Biochem.
Biophys. Res. Commun. 247, 809–813.
Spiecker, M., Peng, H. B. and Lia, J. K. (1997). Inhibition of
endothelial vascular cell adhesion molecule-1 expression by nitric
oxide involves the induction and nuclear translocation of IκBα. J.
Biol. Chem. 272, 30969–30974.
Stamler, J. S. (1994). Redox signaling: nitrosylation and related
target interactions of nitric oxide. Cell 78, 931–936.
Studer, R. K., DeRupertis, F. R. and Craven, P. A. (1996). Nitric
oxide suppresses increases in mesangial cell protein kinase C,
transforming growth factor β and fibronectin synthesis induced by
thromboxane. J. Am. Soc. Nephrol. 7, 999–1005.
Tabuchi, A., Sano, K., Oh, E., Tsuchiya, T. and Tsuda, M. (1994).
Modulation of AP-1 activity by nitric oxide (NO) in vitro: NOmediated modulation of AP-1. FEBS Lett. 351, 123–127.
Tsurumi, Y., Murohara, T., Krasinski, K., Chen, D.,
Witzenbichler, B., Kearny, M., Couffinhal, T. and Isner, J. M.
(1997). Reciprocal relation between VEGF and NO in the
regulation of endothelial integrity. Nature Med. 3, 879–886.
VanDervort, A. L., Yan, L., Madara, P. J., Cobb, J. P., Wesley,
R. A., Corriveau, C. C., Tropea, M. M. and Danner, R. L.
(1994). Nitric oxide regulates endotoxin-induced TNF-α
production by human neutrophils. J. Immunol. 152, 4102–4109.
Villarete, L. H. and Remick, D. G. (1995). Nitric oxide regulation
of IL-8 expression in human endothelial cells. Biochem. Biophys.
Res. Commun. 211, 671–676.
Wang, H., Li, S. and Pelletier, G. (1998). Role of nitric oxide in the
regulation of gonadotropin-releasing hormone and tyrosine
hydroxylase gene expression in the male rat brain. Brain Res. 792,
66–71.
Xie, Q. W., Whisnant, R. and Nathan, C. (1993). Promoter of the
mouse gene encoding calcium-independent nitric oxide synthase
confers
inducibility
by
interferon
γ
and
bacterial
lipopolysaccharide. J. Exp. Med. 177, 1779–1784.
Yamakura, F., Taka, H., Fujimura, T. and Murayama, K. (1998).
Inactivation of human manganese-superoxide dismutase by
peroxynitrite is caused by exclusive nitration of tyrosine 34 to 3nitrotyrosine. J. Biol. Chem. 273, 14085–14089.
Yun, H.-Y., Gonzalez-Zulueta, M., Dawson, V. L. and Dawson, T.
M. (1998). Nitric oxide mediates N-methyl-D-aspartate receptorinduced activation of p21ras. Neurobiol. 95, 5773–5778.
Zeiher, A. M., Fisslthaler, B., Schray-Utz, B. and Busse, R. (1994).
Nitric oxide modulates the expression of monocyte chemoattractant
protein 1 in cultured human endothelial cells. Circulation Res. 76,
980–986.
Zou, M., Martin, C. and Ullrich, V. (1997). Tyrosine nitration as a
mechanism of selective inactivation of prostacyclin synthase by
peroxynitrite. Biol. Chem. Hoppe-Seyler 378, 707–713.