scholarly journals Effects of Ghrelin on iNOS-Derived NO Promoted LPS-Induced Pulmonary Alveolar Epithelial A549 Cells Apoptosis

2018 ◽  
Vol 49 (5) ◽  
pp. 1840-1855 ◽  
Author(s):  
Mian Zeng ◽  
Chunrong Huang ◽  
Haichong Zheng ◽  
Qingui Chen ◽  
Wanmei He ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Flow Cytometry ◽  
Protein Expression ◽  
Transmembrane Potential ◽  
A549 Cells ◽  
Protein S ◽  
Inos Expression ◽  
Mitochondrial Transmembrane Potential ◽  
No Production ◽  
Apoptosis Rate

Background/Aims: In the process of abnormal apoptosis of pulmonary alveolar type II epithelial A549 cells in acute respiratory distress syndrome (ARDS), inducible nitric oxide synthase (iNOS) activity in the lung, nitric oxide (NO) production, and the level of protein S-nitrosylation were increased. However, the role of excessive NO production in sepsis-induced ARDS is controversial. Additionally, ghrelin is a growth hormone that exerts an inhibitory role in cell apoptosis. We examined the effect of NO and S-nitrosylation on apoptosis of A549 cells induced by Lipopolysaccharide (LPS) and molecular mechanism underlying the anti-apoptotic effect of ghrelin in this process. Methods: Flow cytometry and qPCR were used to detect lentiviral infection efficiency and iNOS gene level, respectively. Extracellular and intracellular NO levels were observed by Griess assay kit and DAF-FM DA. Mitochondrial transmembrane potential, apoptosis rate and SNO levels were determined by flow cytometry, Biotin-Switch method and immunofluoresence staining. The expression of iNOS, apoptotic proteins and JNK were assessed by immunoblot analysis. Results: The results showed about two times increase in iNOS expression and intracellular NO levels response to LPS exposure at 24 hours (P< 0.05), while not in extracellular NO levels. NO donors, S-nitroso-N-acetylpenicillamine (SNAP) significantly raised (36.7%, P< 0.05; 38.4%, P< 0.05; 41.8%, P< 0.05) extracellular NO levels without influencing the intracellular NO levels. LPS increased the apoptosis rate (42.4%±2.6% vs 2.8%±1%, P< 0.05) of A549 accompanied by increased Bax levels and decreased Bcl-2 levels through activating JNK signaling, which was reversed when we diminished the iNOS expression in A549 cells using lentiviral vectors encoding iNOS shRNA in the presence of LPS (24.8%±3.8% vs 42.4%±2.6%, P< 0.05). However, the apoptosis rate was increased when SNAP was added (38.8%±1.3% vs 24.8%±3.8%, P< 0.05). Furthermore, we investigated whether ghrelin exert a protective role against LPS-induced apoptosis and the potential mechanism involved in. Ghrelin alone appeared to decrease iNOS expression (32.3%, P< 0.05; 42.3%, P< 0.05), which showed no signifiant difference between LPS+ghrelin group and LPS group. However, this study showed that ghrelin decreased the intracellular NO production (38.9%, P< 0.05), protein S-nitrosylation levels (33.5%, P< 0.05), Bax protein expression (70.2%, P< 0.05), whereas increasing Bcl-2 protein expression (14.1%, P< 0.05) and mitochondrial transmembrane potential (∆ΨM) (20.7%, P< 0.05) in the presence of LPS. Conclusion: The data suggested that NO derived from iNOS induced by LPS stimulation exerts an important role in promoting apoptosis of A549 cells, and ghrelin abolished intracellular NO production and protein S-nitrosylation levels, abrogating the apoptosis of A549 cells partly through inhibiting mitochondrial-dependent pathways.

scholarly journals Hydrogen Sulfide Increases Nitric Oxide Production and Subsequent S-Nitrosylation in Endothelial Cells

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Ping-Ho Chen ◽  
Yaw-Syan Fu ◽  
Yun-Ming Wang ◽  
Kun-Han Yang ◽  
Danny Ling Wang ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Endothelial Cells ◽  
Hydrogen Sulfide ◽  
Protein Kinase ◽  
Fluorescent Probe ◽  
Acid Methyl Ester ◽  
High Specificity ◽  
Protein S ◽  
No Production ◽  
No Donor

Hydrogen sulfide (H2S) and nitric oxide (NO), two endogenous gaseous molecules in endothelial cells, got increased attention with respect to their protective roles in the cardiovascular system. However, the details of the signaling pathways between H2S and NO in endothelia cells remain unclear. In this study, a treatment with NaHS profoundly increased the expression and the activity of endothelial nitric oxide synthase. Elevated gaseous NO levels were observed by a novel and specific fluorescent probe, 5-amino-2-(6-hydroxy-3-oxo-3H-xanthen-9-yl)benzoic acid methyl ester (FA-OMe), and quantified by flow cytometry. Further study indicated an increase of upstream regulator for eNOS activation, AMP-activated protein kinase (AMPK), and protein kinase B (Akt). By using a biotin switch, the level of NO-mediated protein S-nitrosylation was also enhanced. However, with the addition of the NO donor, NOC-18, the expressions of cystathionine-γ-lyase, cystathionine-β-synthase, and 3-mercaptopyruvate sulfurtransferase were not changed. The level of H2S was also monitored by a new designed fluorescent probe, 4-nitro-7-thiocyanatobenz-2-oxa-1,3-diazole (NBD-SCN) with high specificity. Therefore, NO did not reciprocally increase the expression of H2S-generating enzymes and the H2S level. The present study provides an integrated insight of cellular responses to H2S and NO from protein expression to gaseous molecule generation, which indicates the upstream role of H2S in modulating NO production and protein S-nitrosylation.

Nitric oxide-mediated regulation of transepithelial sodium and chloride transport in murine nasal epithelium

1999 ◽  
Vol 276 (3) ◽  
pp. L466-L473 ◽  
Author(s):  
Heather L. Elmer ◽  
Kristine G. Brady ◽  
Mitchell L. Drumm ◽  
Thomas J. Kelley
Keyword(s):  
Nitric Oxide ◽  
Chloride Transport ◽  
Chloride Secretion ◽  
Inos Expression ◽  
Potential Difference ◽  
Nasal Epithelium ◽  
Sodium Absorption ◽  
No Production ◽  
Transepithelial Potential ◽  
Transepithelial Potential Difference

Transepithelial ion transport is regulated by a variety of cellular factors. In light of recent evidence that nitric oxide (NO) production is decreased in cystic fibrosis airways, we examined the role of NO in regulating sodium and chloride transport in murine nasal epithelium. Acute intervention with the inducible NO synthase (iNOS)-selective inhibitor S-methylisothiourea resulted in an increase of amiloride-sensitive sodium absorption observed as a hyperpolarization of nasal transepithelial potential difference. Inhibition of iNOS expression with dexamethasone also hyperpolarized transepithelial potential difference, but only a portion of this increase proved to be amiloride sensitive. Chloride secretion was significantly inhibited in C57BL/6J mice by the addition of both S-methylisothiourea and dexamethasone. Mice lacking iNOS expression [NOS2(−/−)] also had a decreased chloride-secretory response compared with control mice. These data suggest that constitutive NO production likely plays some role in the downregulation of sodium absorption and leads to an increase in transepithelial chloride secretion.

scholarly journals Effects of Resveratrol on Inflammatory Biomarkers in Glaucomatous Human Trabecular Meshwork Cells

Nutrients ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 984 ◽  
Author(s):  
Selom Avotri ◽  
Danita Eatman ◽  
Karen Russell-Randall
Keyword(s):  
Nitric Oxide ◽  
Trabecular Meshwork ◽  
Interleukin 1 ◽  
Inos Expression ◽  
No Production ◽  
Enos Expression ◽  
Average Value ◽  
Beneficial Effects ◽  
Trabecular Meshwork Cells ◽  
Oxide Synthase

Purpose: Resveratrol (RSV), an antioxidant polyphenol, has demonstrated beneficial effects in various ocular diseases including glaucoma. Our study was designed to evaluate the effects of RSV on nitric oxide synthase (NOS) enzymes, nitric oxide (NO) and interleukin-1 alpha (IL-1 α), in human glaucomatous trabecular meshwork (TM) cells. Methods: Western blot was utilized to determine endothelial and inducible NOS (eNOS, iNOS) expression. The concentration-related effects of RSV on IL-1 α and NO levels were assessed using the respective ELISA kits. Results: Densitometry data showed concentration-related increases in eNOS, and reduction in iNOS expression at high RSV concentrations. RSV treatment (0.1, 1, 10 and 100 µM) resulted in increased NO levels (6 ± 0.7, 7 ± 0.8, 7.3 ± 0.7 and 9.5 ± 1 nM/mg protein, respectively). The average value obtained for control was 4.8 ± 0.6 nM/mg protein. Significant increases in IL-1α levels were observed with lower concentrations of RSV. However, at higher RSV concentrations (10–100 μM), IL-1 levels decreased. Conclusions: Resveratrol increased NO in glaucomatous TM cells, possibly by increasing eNOS expression. Thus, RSV-induced NO production supports the beneficial effects of this antioxidant in glaucoma. Furthermore, our results showing a reduction in iNOS, a contributor to oxidative stress expression, further support RSV’s antioxidant capabilities in vision.

scholarly journals l-Arginine Availability Regulates Inducible Nitric Oxide Synthase-Dependent Host Defense against Helicobacter pylori

2007 ◽  
Vol 75 (9) ◽  
pp. 4305-4315 ◽  
Author(s):  
Rupesh Chaturvedi ◽  
Mohammad Asim ◽  
Nuruddeen D. Lewis ◽  
Holly M. Scott Algood ◽  
Timothy L. Cover ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Helicobacter Pylori ◽  
Protein Expression ◽  
Translation Initiation Factor ◽  
No Production ◽  
Dependent Manner ◽  
Inos Protein ◽  
Inos Protein Expression ◽  
H Pylori ◽  
Inducible Nitric Oxide

ABSTRACT Helicobacter pylori infection of the stomach causes an active immune response that includes stimulation of inducible nitric oxide (NO) synthase (iNOS) expression. Although NO can kill H. pylori, the bacterium persists indefinitely, suggesting that NO production is inadequate. We determined if the NO derived from iNOS in macrophages was dependent on the availability of its substrate, l-arginine (l-Arg). Production of NO by H. pylori-stimulated RAW 264.7 cells was dependent on the l-Arg concentration in the culture medium, and the 50% effective dose for l-Arg was 220 μM, which is above reported plasma l-Arg levels. While iNOS mRNA induction was l-Arg independent, iNOS protein increased in an l-Arg-dependent manner that did not involve changes in iNOS protein degradation. l-Lysine, an inhibitor of l-Arg uptake, attenuated H. pylori-stimulated iNOS protein expression, translation, NO levels, and killing of H. pylori. While l-Arg starvation suppressed global protein translation, at concentrations of l-Arg at which iNOS protein was only minimally expressed in response to H. pylori, global translation was fully restored and eukaryotic translation initiation factor α was dephosphorylated. H. pylori lacking the gene rocF, which codes for a bacterial arginase, induced higher levels of NO production by increasing iNOS protein levels. When murine gastric macrophages were activated with H. pylori, supraphysiologic levels of l-Arg were required to permit iNOS protein expression and NO production. These findings indicate that l-Arg is rate limiting for iNOS translation and suggest that the levels of l-Arg that occur in vivo do not permit sufficient NO generation by the host to kill H. pylori.

Angiotensin II modulates nitric oxide-induced cardiac fibroblast apoptosis by activation of AKT/PKB

2003 ◽  
Vol 285 (3) ◽  
pp. H1105-H1112 ◽  
Author(s):  
Bin Tian ◽  
Jian Liu ◽  
Peter Bitterman ◽  
Robert J. Bache
Keyword(s):  
Nitric Oxide ◽  
Angiotensin Ii ◽  
Cardiac Fibroblast ◽  
Inos Expression ◽  
No Production ◽  
Ang Ii ◽  
Phosphatidylinositol 3 Kinase ◽  
No Donor ◽  
At1 Antagonist ◽  
Phosphatidylinositol 3

Previously we found that interleukin-1β (IL-1β)-activated inducible nitric oxide (NO) synthase (iNOS) expression and that NO production can trigger cardiac fibroblast (CFb) apoptosis. Here, we provide evidence that angiotensin II (ANG II) significantly attenuated IL-1β-induced iNOS expression and NO production in CFbs while simultaneously decreasing apoptotic frequency. The anti-apoptotic effect of ANG II was abolished when cells were pretreated with the specific ANG II type 1 receptor (AT1) antagonist losartan, but not by the AT2 antagonist DP-123319. Furthermore, ANG II also protected CFbs from apoptosis induced by the NO donor diethylenetriamine NONOate and this effect was associated with phosphorylation of Akt/protein kinase B at Ser473. The effects of ANG II on Akt phosphorylation and NO donor-induced CFb apoptosis were abrogated when cells were preincubated with the specific phosphatidylinositol 3-kinase inhibitors wortmannin or LY-294002. These data demonstrate that ANG II protection of CFbs from IL-1β-induced apoptosis is associated with downregulation of iNOS expression and requires an intact phosphatidylinositol 3-kinase-Akt survival signal pathway. The findings suggest that ANG II and NO may play a role in regulating the cell population size by their countervailing influences on cardiac fibroblast viability.

scholarly journals Augmented inducible nitric oxide synthase expression and increased NO production reduce sepsis-induced lung injury and mortality in myeloperoxidase-null mice

2008 ◽  
Vol 295 (1) ◽  
pp. L96-L103 ◽  
Author(s):  
Viktor Brovkovych ◽  
Xiao-Pei Gao ◽  
Evan Ong ◽  
Svitlana Brovkovych ◽  
Marie-Luise Brennan ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Inducible Nitric Oxide Synthase ◽  
Bacterial Colonization ◽  
Inos Expression ◽  
No Production ◽  
Bacterial Killing ◽  
E Coli ◽  
Oxide Synthase ◽  
Inducible Nitric Oxide

The myeloperoxidase (MPO)-hydrogen peroxide-halide system is an efficient oxygen-dependent antimicrobial component of polymorphonuclear leukocyte (PMN)-mediated host defense. However, MPO deficiency results in few clinical consequences indicating the activation of compensatory mechanisms. Here, we determined possible mechanisms protecting the host using MPO−/−mice challenged with live gram-negative bacterium Escherichia coli. We observed that MPO−/−mice unexpectedly had improved survival compared with wild-type (WT) mice within 5–12 h after intraperitoneal E. coli challenge. Lungs of MPO−/−mice also demonstrated lower bacterial colonization and markedly attenuated increases in microvascular permeability and edema formation after E. coli challenge compared with WT. However, PMN sequestration in lungs of both groups was similar. Basal inducible nitric oxide synthase (iNOS) expression was significantly elevated in lungs and PMNs of MPO−/−mice, and NO production was increased two- to sixfold compared with WT. Nitrotyrosine levels doubled in lungs of WT mice within 1 h after E. coli challenge but did not change in MPO−/−mice. Inhibition of iNOS in MPO−/−mice significantly increased lung edema and reduced their survival after E. coli challenge, but iNOS inhibitor had the opposite effect in WT mice. Thus augmented iNOS expression and NO production in MPO−/−mice compensate for the lack of HOCl-mediated bacterial killing, and the absence of MPO-derived oxidants mitigates E. coli sepsis-induced lung inflammation and injury.

scholarly journals Cholecystokinin Inhibits Inducible Nitric Oxide Synthase Expression by Lipopolysaccharide-Stimulated Peritoneal Macrophages

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Rafael Simone Saia ◽  
Fabíola Leslie Mestriner ◽  
Giuliana Bertozi ◽  
Fernando Queiróz Cunha ◽  
Evelin Capellari Cárnio
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Inducible Nitric Oxide Synthase ◽  
Peritoneal Macrophages ◽  
Inos Expression ◽  
No Production ◽  
Camp Content ◽  
Systemic Complications ◽  
Oxide Synthase ◽  
Inducible Nitric Oxide

Cholecystokinin (CCK) was first described as a gastrointestinal hormone. However, apart from its gastrointestinal effects, studies have described that CCK also plays immunoregulatory roles. Taking in account the involvement of inducible nitric oxide synthase- (iNOS-) derived NO in the sepsis context, the present study was undertaken to investigate the role of CCK on iNOS expression in LPS-activated peritoneal macrophages. Our results revealed that CCK reduces NO production and attenuates the iNOS mRNA expression and protein formation. Furthermore, CCK inhibited the nuclear factor- (NF-)κB pathway reducing IκBαdegradation and minor p65-dependent translocation to the nucleus. Moreover, CCK restored the intracellular cAMP content activating the protein kinase A (PKA) pathway, which resulted in a negative modulatory role on iNOS expression. In peritoneal macrophages, the CCK-1R expression, but not CCK-2R, was predominant and upregulated by LPS. The pharmacological studies confirmed that CCK-1R subtype is the major receptor responsible for the biological effects of CCK. These data suggest an anti-inflammatory role for the peptide CCK in modulating iNOS-derived NO synthesis, possibly controlling the macrophage activation through NF-κB, cAMP-PKA, and CCK-1R pathways. Based on these findings, CCK could be used as an adjuvant agent to modulate the inflammatory response and prevent systemic complications commonly found during sepsis.

Nitric Oxide As a Mediator of Bone Marrow Fibrosis in Patients with Myelofibrosis

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4587-4587
Author(s):  
Ali Tabarroki ◽  
Daniel Lindner ◽  
Valeria Visconte ◽  
Nikolaos Papandantonakis ◽  
Jing Ai ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Bone Marrow ◽  
Growth Factor ◽  
Board Of Directors ◽  
Transforming Growth Factor ◽  
Myeloproliferative Neoplasms ◽  
Inos Expression ◽  
No Production ◽  
Advisory Committees ◽  
Extracellular Matrix Components

Abstract Bone marrow (BM) fibrosis is a key pathomorphologic feature of patients (pts) with primary myelofibrosis (PMF) and the fibrotic phases of essential thrombocythemia (post-ET MF) and polycythemia vera (post-PV MF). The degree of BM fibrosis appears to correlate with survival. Indeed worse survival has been associated with increased BM fibrosis. The BM stromal microenvironment is important in the pathogenesis of BM fibrosis. Cellular components (fibroblasts, macrophages, endothelial cells, adipocytes), structural fibrils (collagen, reticulin) and extracellular matrix components are all forming elements of the BM stroma. Increased stromal fibrosis has been linked to abnormalities in the number/ function of megakaryocytes and platelets in hematologic diseases. Several cytokines like Platelet Derived Growth Factor (PDGF) and Transforming Growth Factor-Beta (TGF-b) have been also linked to the pathophysiology of BM fibrosis. PDGF has been shown to increase fibroblast growth in megakaryocytes and platelets although increased PDGF did not correlate with increased production of either reticulin or collagenous fibrosis. Moreover, PMF pts have increased TGF-b levels in platelets, megakaryocytes, and monocytes. Nitric Oxide (NO) is a ubiquitous gas important in physiologic processes particularly vasodilatation. Dysregulation of NO levels has been implicated in pulmonary hypertension (PH), hemoglobinopathies, and cardiovascular diseases. In Peyronie’s disease, a localized fibrosis of the penile tunica albuginea, increased NO production by expression of iNOS decreases collagen deposition by neutralization of profibrotic reactive oxygen species and decreased myofibroblast formation. Aside from its role in maintaining normal vascular tone, NO also plays a role in fibroblast formation and collagen biosynthesis. We previously reported that ruxolitinib, a JAK1/2 inhibitor restores NO levels leading to improvement of PH in MF pts (Tabarroki et al., Leukemia 2014). We now hypothesize that plasma/serum NO level is a key regulator of BM fibrosis in MF and that ruxolitinib treatment (Tx) leads to improvement of BM fibrosis by NO modulation. Using a Sievers 280i NO analyzer we measured the plasma/serum NO level of a large cohort (n=75) of pts with myeloid and myeloproliferative neoplasms (MPN) [MDS, RARS/RCMD=8; MPN, ET=8, PV=8, MF=24, Mastocytosis=7; MDS/MPN, CMML=11, MDS/MPN-U, RARS-T=9]. Healthy subjects (n=10) were used as a control. MPN pts had low NO (nM) levels among the pts studied with the lowest level found in MF pts: MF=30.31±11.8, PV=39.0±16.1, ET=36±20.3, RARS=74.6±41.7 (P=.01), CMML=84.4±89.2 (P=.04), RCMD=163.4±103.8 (P<.001), RARS-T=131.1±99.8 (P<.001). In total, NO levels were lower in classic MPN (n=40, 35.3±16.6) compared to MDS (n=8, 119±62.8; P=.001) and MDS/MPN (n=20, 105±94.6; P=.008). When we looked at the correlation between NO levels and BM fibrosis grade we found that there is an inverse correlation between NO levels and worsening BM fibrosis grade from grade MF1 to MF3. NO levels in normal (n=10) vs MF1 (n=3) were 53.3 vs 39.1, P=.025; normal vs MF2 (n=7) were 53.3 vs 37, P=.021; normal vs MF3 (n=12) were 53.3 vs 34.4, P=.006. A total of 8 pts who were treated with ruxolitinib and had at least 1 pre and 1 post Tx (≥3 months from initiation of ruxolitinib) were tested for NO levels. Among the 8 pts, 4 pts who demonstrated improvement in BM scores had a trend towards improved NO levels after ruxolitinib Tx [NO pre vs post; pt #1: 6 vs 10.5; pt#2: 4.3 vs 6.4; pt#3 49.7 vs 52.1; pt#4 36 vs 41.3; P=.02] while 4 had worsening or had no change in BM fibrosis grade and had a minimal change or decline in the NO (pt#5: 18.4 vs 23, pt#6: 14.29 vs 12.1, pt#7: 32.7 vs 32.1, pt#8: 110.9 vs 40.4). One pt who had improvement in BM fibrosis grade after ruxolitinib Tx had increased iNOS expression by Western blotting (pt#1) while no iNOS expression (pt#5) was noted in the pt who did not have improvement in BM fibrosis. Of note, multi-analytic cytokines profile also showed an overall decrease in cytokines especially a 2.8 fold-decrease in IL8 levels post-Tx in the pt with improvement in BM fibrosis. In conclusion, NO is decreased in MPN particularly in MF and may be a key mediator of BM fibrosis in MF. Pharmacologic therapies such as JAK inhibitors may mediate improvement of BM fibrosis by modulation of NO levels in MF. Disclosures Tiu: Gilead: Membership on an entity's Board of Directors or advisory committees; Novartis: Speakers Bureau; Incyte : Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

scholarly journals Role of Mitogen-Activated Protein Kinases in Peptidoglycan-Induced Expression of Inducible Nitric Oxide Synthase and Nitric Oxide in Mouse Peritoneal Macrophages: Extracellular Signal-Related Kinase, a Negative Regulator

2011 ◽  
Vol 18 (6) ◽  
pp. 994-1001 ◽  
Author(s):  
Kunal H. Bhatt ◽  
Ajit Sodhi ◽  
Rituparna Chakraborty
Keyword(s):  
Nitric Oxide ◽  
Transcription Factors ◽  
Inos Expression ◽  
No Production ◽  
Erk Pathway ◽  
Mitogen Activated Protein Kinases ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Oxide Synthase ◽  
Inducible Nitric Oxide

ABSTRACTThe expression of inducible nitric oxide synthase (iNOS) and the production of nitric oxide (NO) are important host defense mechanisms against pathogens in mononuclear phagocytes. The objectives of this study were to examine the roles of mitogen-activated protein kinases (MAPKs) and transcription factors (nuclear factor-κB [NF-κB] and activating protein 1 [AP-1]) in peptidoglycan (PGN)-induced iNOS expression and NO production in macrophages. PGN is a cell wall component of Gram-positive bacteria that stimulates inflammatory responses bothex vivoandin vivo. PGN stimulates the activation of all three classes of MAPKs, extracellular signal-related kinase (ERK), c-Jun N-terminal kinase (JNK), and p38mapkin macrophages, albeit with differential activation kinetics. Using a selective inhibitor of JNK (SP600125) and JNK1/2 small interfering RNA (siRNA) knocked-down macrophages, it was observed that PGN-induced iNOS and NO expression is significantly inhibited. This suggested that JNK MAPK plays an essential role in PGN-induced iNOS expression and NO production. In contrast, inhibition of the ERK pathway using PD98059 dose dependently enhanced PGN-induced iNOS expression and NO production. PGN-induced ERK activation was attenuated in ERK1/2 siRNA knocked-down macrophages; however, NO and iNOS expression were significantly enhanced. An electrophoretic mobility shift assay showed that SP600125 inhibited PGN-induced NF-κB and AP-1 activation, whereas inhibition of the ERK pathway enhanced NF-κB activation, but with no effect on AP-1. These results indicate that the JNK MAPK positively regulate PGN-induced iNOS and NO expression by activating NF-κB and AP-1 transcription factors, whereas the ERK pathway plays a negative regulatory role via affecting NF-κB activity.

Sign in / Sign up

Export Citation Format

Share Document