Up-regulation of heme oxygenase-1 expression through the
Rac1/NADPH oxidase/ROS/p38 signaling cascade mediates the
anti-inflammatory effect of 15-deoxy-D12,14-prostaglandin J2in
Hye-Young Honga, Woo-Kwang Jeona, Byung-Chul Kima,b,*
aDepartment of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon 200-701, Republic of Korea
bResearch Institute of Life Sciences, College of Natural Sciences, Kangwon National University, Chuncheon 200-701, Republic of Korea
Received 22 November 2007; revised 6 January 2008; accepted 7 February 2008
Available online 20 February 2008
Edited by Robert Barouki
to the expression of heme oxygenase-1 (HO-1) in murine
macrophages in response to 15-deoxy-D12,14-prostaglandin J2
(15dPGJ2). 15dPGJ2caused dose- and time-dependent activa-
tion of Rac1, followed by a transient increase in reactive oxygen
species (ROS) via NADPH oxidase, which leads to downstream
activation of p38 kinase. Inhibition of 15dPGJ2-dependent HO-1
expression significantly attenuated suppression by 15dPGJ2of
LPS-induced iNOS expression and subsequent production of
nitric oxide (NO). Our findings strongly suggest that 15dPGJ2
exerts its anti-inflammatory activity through the Rac1-NADPH
oxidase-ROS-p38 signaling to the up-regulation of HO-1 in an
in vitro inflammation model.
? ? 2008 Federation of European Biochemical Societies. Published
by Elsevier B.V. All rights reserved.
We investigated the signaling pathway that leads
Keywords: 15-Deoxy-D12,14-prostaglandin J2; Heme
oxygenase-1; Rac1; NADPH oxidase; p38; Nitric oxide
15-Deoxy-D12,14-prostaglandin J2(15dPGJ2) is an immuno-
regulatory lipid metabolite derived from prostaglandin D2
(PGD2) dehydration in vivo, which is abundantly produced
by mast cells, dendritic cells, and alveolar macrophages [1–3].
As a ligand for the peroxisome proliferators activated recep-
tor-c (PPAR-c), 15dPGJ2 exhibits anti-inflammatory effects
that modulate the vascular inflammation and the atherosclero-
sis process [4,5]. However, other accumulating data suggest
that the PPAR-c-independent mechanism may account for
the major anti-inflammatory action of 15dPGJ2. For example,
15dPGJ2 repress several pro-inflammatory genes, including
inducible nitric oxide synthase (iNOS) and tumor necrosis fac-
tor-a (TNF-a) genes in macrophages derived from PPAR-c-
deficient embryonic stem cells [6,7]. 15dPGJ2also performs
its anti-inflammatory activity through direct inhibition of
signaling steps leading to nuclear factor-kappa B (NF-kB) acti-
vation [8,9], eventually down-regulating expression of pro-
inflammatory cytokines and immune mediators.
Heme oxygenase-1 (HO-1) is a microsomal enzyme, catalyz-
ing the breakdown of heme into equimolar amounts of carbon
monoxide (CO), biliverdin, and free iron using molecular oxy-
gen and reducing equivalents from NADPH:cytochrome P450
reductase [10,11]. HO-1 contributes to the host defense reac-
tion against oxidative injury through the antioxidant activities
of biliverdin and its metabolite, bilirubin, as well as the anti-
inflammatory action of CO [12,13]. A growing body of evi-
dence revealed that 15dPGJ2induces HO-1 expression through
mechanisms independent of PPAR-c activation and dependent
on cellular redox state in various cell types [14,15]. Further-
more, the anti-inflammatory actions of 15dPGJ2are function-
ally correlated with the induction of HO-1 expression ,
suggesting an important role of HO-1 in PPAR-c-independent
mechanism for anti-inflammatory action of 15dPGJ2. Despite
these reports, the detailed signaling pathway by which
15dPGJ2mediates induction of HO-1 expression remains lar-
Regarding the signaling mechanisms of HO-1 induction, sev-
eral studies have suggested involvement of reactive oxygen spe-
cies (ROS) [17,18]. ROS, such as hydrogen peroxide (H2O2),
ulator of various biological processes, including cell prolifera-
tion, apoptosis, and inflammation. An important ROS source
within phagocytic cells is the NADPH oxidase, which consists
(gp91phoxand p22phox) and the three cytosolic components
(p47phox, p67phox, and p40phox), and Rac1, a member of the
Rho family GTPases, plays a central role in activating this
complex . We here demonstrate that 15dPGJ2exerts its
in vitro anti-inflammatory activity through the Rac1-NADPH
oxidase-ROS-p38 signaling to the up-regulation of HO-1.
2) and hydroxyl radical (OH?), are important reg-
2. Materials and methods
15dPGJ2was obtained from Biomol (Plymouth Meeting, PA). Lipo-
polysaccharide (LPS), diphenylenepropodiumiodide (DPI), apocynin,
N-acetylcysteine (NAC), reduced glutathione (GSH) and buthionine
sulfoximine (BSO) were purchased from Sigma Chemical Co. (St.
Louis, MI, USA). The following were obtained from Calbiochem
*Corresponding author. Address: Department of Biochemistry and
Research Institute of Life Sciences, College of Natural Sciences,
Kangwon National University, 192-1 Hyoja-2-dong, Chuncheon 200-
701, Republic of Korea. Fax: +82 33 242 0459.
E-mail address: firstname.lastname@example.org (B.-C. Kim).
0014-5793/$34.00 ? 2008 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
FEBS Letters 582 (2008) 861–868
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