The MAP kinase inhibitors, PD098059, UO126 and SB203580, inhibit IL-1beta-dependent PGE(2) release via mechanistically distinct processes

The role of Th-17 cells and IL-17 in the metastatic spread of breast cancer: As a means of prognosis and therapeutic target

Metastatic breast cancer is one of the most common and well-known causes of death for women worldwide. The inflammatory tumor cell and other cancer hallmarks dictate the metastatic form and dissemination of breast cancer. Taking these into account, from various components of the tumor microenvironment, a pro-inflammatory infiltrative cell known as Th-17 plays an immense role in breast cancer proliferation, invasiveness, and metastasis. It has been demonstrated that IL-17, a pleiotropic pro-inflammatory cytokine generated by Th-17, is upregulated in a metastatic form of breast cancer. Recent research updates stated that chronic inflammation and mediators like cytokines and chemokines are causative hallmarks in many human cancers, including breast cancer. Therefore, IL-17 and its multiple downward signaling molecules are the centers of research attention to develop potent treatment options for cancer. They provide information on the role of IL-17-activated MAPK, which results in tumor cell proliferation and metastasis via NF-kB-mediated expression of MMP signaling. Overall, this review article emphasizes IL-17A and its intermediate signaling molecules, such as ERK1/2, NF-kB, MMPs, and VEGF, as potential molecular targets for the prevention and treatment of breast cancer.

Participation of MAPK and PI3K in Regulation of Cytokine Secretion by Peripheral Blood Monocular Cells in Response to Escherichia coli LPS and rDer p 2 Combination

Search for the effective approaches to treat acute inflammation caused by combination of allergens and infectious agents is an important task for public health worldwide. House dust mites Dermatophagoides pteronyssinus are the source of allergens of the Der p groups and of microbial compounds, in particular, lipopolysaccharides (LPS). LPS and Der p 2 induce secretion of pro-inflammatory cytokines via activation of kinases p38 MAPK, MEK1/2, and PI3K. Participation of these kinases in the regulation of cells response to combined exposure to LPS and Der p 2 has not been sufficiently studied. We studied the effects of kinases (p38 MAPK, MEK1/2, and PI3K) inhibition on secretion of cytokines (TNF, IL-8, and IL-6) by peripheral blood mononuclear cells (PBMC) of healthy volunteers in response to E. coli LPS and rDer p 2. Contribution of kinases to the regulation of cell response to different agents (rDer p 2 and/or LPS) was revealed. It was found that p38 MAPK plays a key role in the regulation of secretion TNF by PBMC in response to the combination of LPS and rDer p 2. MEK1/2-dependent signaling is the main pathway for the synthesis of TNF and IL-8 in response to LPS and rDer p 2. PI3K-dependent signaling negatively regulates TNF production during rDer p 2-induced cell activation, but is not involved in the response to the combination of LPS and rDer p 2. PI3K-dependent signaling in the regulation of PBMC cytokine synthesis is most pronounced in response to their activation by rDer p 2. Understanding the mechanisms of immune cell responses to combinations of inflammatory agents could facilitate the search for new intracellular targets for anti-inflammatory therapy.

Platelet MAPKs-a 20+ year history: What do we really know?

The existence of mitogen activated protein kinases (MAPKs) in platelets has been known for more than 20 years. Since that time hundreds of reports have been published describing the conditions that cause MAPK activation in platelets and their role in regulating diverse platelet functions from the molecular to physiological level. However, this cacophony of reports, with inconsistent and sometimes contradictory findings, has muddied the waters leading to great confusion. Since the last review of platelet MAPKs was published more than a decade ago, there have been more than 50 reports, including the description of novel knockout mouse models, that have furthered our knowledge. Therefore, we undertook an extensive literature review to delineate what is known about platelet MAPKs. We specifically discuss what is currently known about how MAPKs are activated and what signaling cascades they regulate in platelets incorporating recent findings from knockout mouse models. In addition, we will discuss the role each MAPK plays in regulating distinct platelet functions. In doing so, we hope to clarify the role for MAPKs and identify knowledge gaps in this field that await future researchers. In addition, we discuss the limitations of current studies with a particular focus on the off-target effects of commonly used MAPK inhibitors. We conclude with a look at the clinical utility of MAPK inhibitors as potential antithrombotic therapies with an analysis of current clinical trial data.

Znf76 is associated with development of the eyes, midbrain, MHB, and hindbrain in zebrafish embryos

ZNF76 is a transcriptional repressor that targets the TATA-binding protein (TBP) and plays an essential role during brain development; however, its function during embryogenesis remains unclear. Here, we report the expression pattern and potential functions of znf76 in zebrafish embryos. Maternal transcripts of znf76 were detected at low levels in embryos at the 1-cell stage, with zygotic transcripts appearing at the sphere stage. At the bud stage, the distribution of znf76 transcripts was polarized to the anterior and posterior regions of the embryos, and znf76 transcripts were further restricted to the trigeminal placode and proctodeum posterior gut of the embryos at 18 h postfertilization (hpf). znf76 transcripts were localized to the midbrain–hindbrain boundary (MHB), hindbrain, and developing eyes at 24 hpf. Ectopic expression of znf76 with 5’-capped znf76 mRNA microinjected into embryos at the 1-cell stage caused phenotypic defects in the eyes, MHB, hindbrain, and spinal cord. Overexpression of znf76 resulted in a drastic reduction of pax2a, fgf8a, and rx1 transcripts in the optic stalk, MHB, and eyes, respectively. Taken together, these data indicate that Znf76 governs developmental processes in the MHB, hindbrain, and eyes in zebrafish embryos. We also discuss the Fgf8 signaling networks associated with the Znf76 function.

Peli1b governs the brain patterning via ERK signaling pathways in zebrafish embryos

Pellino proteins are associated with immune and stress responses through their effects on NF-κB signaling and B-cell development, and through their role as a scaffold in TLR/IL-1R signaling pathways. However, their function during embryonic development is unclear. Here, we report the developmental expression patterns and functions of peli1b, which encodes a zebrafish ortholog of human Pellino1. Maternal peli1b transcripts were present in zebrafish embryos at the 1-cell stage and zygotic transcripts appeared in the shield area at 6 hours post fertilization (hpf), particularly in the neural plate of the dorsal region. peli1b transcripts were concentrated in the somites, lens, myogenic cells, lateral plate mesoderm, and presomitic mesoderm at 12 hpf, but expression shifted to the telencephalon, diencephalon, hindbrain, and rhombomeres (r1-7) at 24 hpf. Distribution of peli1b transcripts was further restricted to the telencephalon, diencephalon, hindbrain, eyes, and pectoral fins at 48 hpf. Knock-down of peli1b with a peli1b antisense morpholino resulted in significant developmental defects and a reduction in size of the telencephalon, diencephalon, rhombomeres (r1-7), and spinal cord at 24 hpf. When peli1b-knock-down embryos were analyzed for zic3, a marker associated with the central nervous system, we found lower levels of zic3 transcripts in the shield area at 6 hpf and in the posterior diencephalon, dorsal neural plate, midbrain, and hindbrain at 14 hpf. Finally, the ERK3/4 inhibitor SB203580 also induced a significant reduction in the level of zic3 transcripts in the neural plate at 6 hpf and in the posterior diencephalon, dorsal neural plate, midbrain, hindbrain, segmental plate, dorsal spinal cord, and dorsal posterior neural plate at 14 hpf. It is thus likely that the association between Peli1b and brain development in zebrafish embryos occurs via ERK3/4 pathways.

A newly synthesized nickel chelate can selectively target and overcome multidrug resistance in cancer through redox imbalance both in vivo and in vitro

Induction of undesired toxicity and emergence of multidrug resistance (MDR) are the major obstacles for cancer treatment. Moreover, aggressive cancers are less sensitive towards existing chemotherapeutics. Therefore, selective targeting of cancers without inducing undesired side effects and designing proper strategies to overcome MDR has utmost importance in modern chemotherapy. Previously we revealed the anticancer properties of some transition metal chelates of Schiff base, but the effectiveness of nickel complex is still unrevealed. Herein, we synthesized and characterized a Schiff base nickel chelate, nickel-(II) N-(2-hydroxyacetophenone) glycinate (NiNG), through different spectroscopic means. NiNG proves to be a broad spectrum anticancer agent with considerable efficacy to overcome MDR in cancer. Antiproliferative effects of NiNG was evaluated using drug-resistant (CEM/ADR5000; NIH-MDR-G185; EAC/Dox), drug-sensitive aggressive (Hct116; CCRF-CEM; EAC/S) and normal (NIH-3T3) cells that reveal the selective nature of NiNG towards drug resistant and sensitive cancer cells without inducing any significant toxicity in normal cells. Moreover, NiNG involves reactive oxygen species (ROS)-mediated redox imbalance for induction of caspase 3-dependent apoptosis in aggressive drug-sensitive Hct116 and drug-resistant NIH-MDR-G185 cells through disruption of mitochondrial membrane potential. Moreover, intraperitoneal (i.p.) application of NiNG at non-toxic doses caused significant increase in the life-span of Swiss albino mice bearing sensitive and doxorubicin-resistant subline of Ehrlich ascites carcinoma cells. It is noteworthy that, in vitro NiNG can only overcome P-glycoprotein-mediated MDR while in vivo NiNG can overcome MRP1-mediated MDR in cancer. Therefore, NiNG has therapeutic potential to target and overcome MDR in cancer.

Minocycline targets multiple secondary injury mechanisms in traumatic spinal cord injury

Minocycline hydrochloride (MH), a semi-synthetic tetracycline derivative, is a clinically available antibiotic and anti-inflammatory drug that also exhibits potent neuroprotective activities. It has been shown to target multiple secondary injury mechanisms in spinal cord injury, via its anti-inflammatory, anti-oxidant, and anti-apoptotic properties. The secondary injury mechanisms that MH can potentially target include inflammation, free radicals and oxidative stress, glutamate excitotoxicity, calcium influx, mitochondrial dysfunction, ischemia, hemorrhage, and edema. This review discusses the potential mechanisms of the multifaceted actions of MH. Its anti-inflammatory and neuroprotective effects are partially achieved through conserved mechanisms such as modulation of p38 mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K)/Akt signaling pathways as well as inhibition of matrix metalloproteinases (MMPs). Additionally, MH can directly inhibit calcium influx through the N-methyl-D-aspartate (NMDA) receptors, mitochondrial calcium uptake, poly(ADP-ribose) polymerase-1 (PARP-1) enzymatic activity, and iron toxicity. It can also directly scavenge free radicals. Because it can target many secondary injury mechanisms, MH treatment holds great promise for reducing tissue damage and promoting functional recovery following spinal cord injury.

Cyclooxygenase 2: its regulation, role and impact in airway inflammation

Cyclooxygenase 2 (COX-2: official gene symbol - PTGS2) has long been regarded as playing a pivotal role in the pathogenesis of airway inflammation in respiratory diseases including asthma. COX-2 can be rapidly and robustly expressed in response to a diverse range of pro-inflammatory cytokines and mediators. Thus, increased levels of COX-2 protein and prostanoid metabolites serve as key contributors to pathobiology in respiratory diseases typified by dysregulated inflammation. But COX-2 products may not be all bad: prostanoids can exert anti-inflammatory/bronchoprotective functions in airways in addition to their pro-inflammatory actions. Herein, we outline COX-2 regulation and review the diverse stimuli known to induce COX-2 in the context of airway inflammation. We discuss some of the positive and negative effects that COX-2/prostanoids can exert in in vitro and in vivo models of airway inflammation, and suggest that inhibiting COX-2 expression to repress airway inflammation may be too blunt an approach; because although it might reduce the unwanted effects of COX-2 activation, it may also negate the positive effects. Evidence suggests that prostanoids produced via COX-2 upregulation show diverse actions (and herein we focus on prostaglandin E2 as a key example); these can be either beneficial or deleterious and their impact on respiratory disease can be dictated by local concentration and specific interaction with individual receptors. We propose that understanding the regulation of COX-2 expression and associated receptor-mediated functional outcomes may reveal number of critical steps amenable to pharmacological intervention. These may prove invaluable in our quest towards future development of novel anti-inflammatory pharmacotherapeutic strategies for the treatment of airway diseases.

DUSP1 Maintains IRF1 and Leads to Increased Expression of IRF1-dependent Genes: A MECHANISM PROMOTING GLUCOCORTICOID INSENSITIVITY

Although the mitogen-activated protein kinase (MAPK) phosphatase, DUSP1, mediates dexamethasone-induced repression of MAPKs, 14 of 46 interleukin-1β (IL1B)-induced mRNAs were significantly enhanced by DUSP1 overexpression in pulmonary A549 cells. These include the interferon regulatory factor, IRF1, and the chemokine, CXCL10. Of these, DUSP1-enhanced mRNAs, 10 including CXCL10, were IRF1-dependent. MAPK inhibitors and DUSP1 overexpression prolonged IRF1 expression by elevating transcription and increasing IRF1 mRNA and protein stability. Conversely, DUSP1 silencing increased IL1B-induced MAPK phosphorylation while significantly reducing IRF1 protein expression at 4 h. This confirms a regulatory network whereby DUSP1 switches off MAPKs to maintain IRF1 expression. There was no repression of IRF1 expression by dexamethasone in primary human bronchial epithelial cells, and in A549 cells IL1B-induced IRF1 protein was only modestly and transiently repressed. Although dexamethasone did not repress IL1B-induced IRF1 protein expression at 4-6 h, silencing of IL1B plus dexamethasone-induced DUSP1 significantly reduced IRF1 expression. IL1B-induced expression of CXCL10 was largely insensitive to dexamethasone, whereas other DUSP1-enhanced, IRF1-dependent mRNAs showed various degrees of repression. With IL1B plus dexamethasone, CXCL10 expression was also IRF1-dependent, and expression was reduced by DUSP1 silencing. Thus, IL1B plus dexamethasone-induced DUSP1 maintains expression of IRF1 and the IRF1-dependent gene, CXCL10. This is supported by chromatin immunoprecipitation showing IRF1 recruitment to be essentially unaffected by dexamethasone at the CXCL10 promoter or at the promoters of more highly repressed IRF1-dependent genes. Since IRF1-dependent genes, such as CXCL10, are central to host defense, these data may help explain the reduced effectiveness of glucocorticoids during asthma exacerbations.

Flavonoids as dopaminergic neuromodulators

SCOPE

The present study aimed to characterize and evaluate flavonoids effects on organic cation uptake in neuronal cells.

METHODS AND RESULTS

Uptake experiments were conducted using radiolabeled methyl-4-phenylpyridinuim ([(3) H]-MPP(+) ), in human neuronal dopaminergic cells, SH-SY5Y. Catechin did not alter [(3) H]-MPP(+) uptake, however its metabolite 4'-methyl-catechin decreased it by almost 50%. Epicatechin and its methylated metabolites also decreased [(3) H]-MPP(+) uptake. Interestingly, the quercetin flavonol and its metabolite conjugated with glucuronic acid, as well as the flavanones naringenin and hesperitin, increased [(3) H]-MPP(+) uptake.

CONCLUSION

These results showed that different classes of flavonoids, as well as its metabolites, differently influence neuronal organic cation uptake. Several xeno- and endobiotics, including neurotransmitters, are organic cations. Specific food recommendations may be beneficial in pathological conditions where levels of neurotransmitters, as dopamine, are either increased or decreased.

Nanoparticulate carbon black in cigarette smoke induces DNA cleavage and Th17-mediated emphysema

Chronic inhalation of cigarette smoke is the major cause of sterile inflammation and pulmonary emphysema. The effect of carbon black (CB), a universal constituent of smoke derived from the incomplete combustion of organic material, in smokers and non-smokers is less known. In this study, we show that insoluble nanoparticulate carbon black (nCB) accumulates in human myeloid dendritic cells (mDCs) from emphysematous lung and in CD11c⁺ lung antigen presenting cells (APC) of mice exposed to smoke. Likewise, nCB intranasal administration induced emphysema in mouse lungs. Delivered by smoking or intranasally, nCB persisted indefinitely in mouse lung, activated lung APCs, and promoted T helper 17 cell differentiation through double-stranded DNA break (DSB) and ASC-mediated inflammasome assembly in phagocytes. Increasing the polarity or size of CB mitigated many adverse effects. Thus, nCB causes sterile inflammation, DSB, and emphysema and explains adverse health outcomes seen in smokers while implicating the dangers of nCB exposure in non-smokers.

DOI:http://dx.doi.org/10.7554/eLife.09623.001

Smoking for many years damages the lungs and leads to a disease called emphysema that makes it difficult to breathe and is often deadly. There are thousands of chemicals in cigarette smoke and many of them have been linked to the development of lung cancer, although it has been difficult to pinpoint those that are responsible for smoking-related emphysema. Moreover, cigarette smoke also contains large numbers of small particles and relatively little is known about the role played by these particles in smoking-related disease.

One of the hallmarks of long-term smoking is a blackening of the lung tissue that persists even if someone stops smoking. Previously, little was known about the composition of the substance that causes this blackening, or its significance in the development of emphysema. Now, by studying lung tissue taken from smokers with emphysema, You et al. have shown that this black substance is made of nano-sized particles of a material called carbon black (which is also known as elemental carbon). These nanoparticles are produced by the incomplete combustion of the cigarettes. You et al. also confirmed that nanoparticles of carbon black can cause emphysema in mice.

Closer examination of the lung damage caused by the nanoparticles revealed that they trigger breakages in DNA, which leads to inflammation of the lung. And because the nanoparticles cannot be cleared, they are released into the lung when cells die, which perpetuates lung inflammation and damage.

You et al. then went on to show that nanoparticles of carbon black can be modified in a way that allows them to be cleared from the lungs. Such modifications could potentially protect people who are exposed to carbon black nanoparticles in the environment or in workplaces where carbon black is used, such as factories that produce automobile tires and other rubber products.

DOI:http://dx.doi.org/10.7554/eLife.09623.002

Investigation of MEK activity in COS7 cells entering mitosis

Although the mitogen-activated protein kinase (MAPK) pathway has been extensively investigated, numerous events remain unclear. In the present study, we examined mitogen-activated protein kinase kinase (MEK) expression from interphase to mitosis. Following nocodazole treatment, COS7 cells gradually became round as early as 4 h after treatment. Cyclin B1 expression gradually increased from 4 to 24 h in the presence of nocodazole. When cells were treated with nocodazole for 4 h, the level of epidermal growth factor (EGF)-mediated MEK phosphorylation did not significantly change between nocodazole-untreated and -treated (4 h) cells (P>0.05). However, EGF-mediated MEK phosphorylation was significantly inhibited upon treatment with nocodazole for 8 and 24 h compared to nocodazole-untreated cells (P<0.05). MEK phosphorylation levels were comparable between 1, 5, 10 and 50 ng/ml EGF treatments. Phorbol 12-myristic 13-acetate (PMA) did not activate MEK in mitotic cells. Following treatment of COS7 cells at the interphase with AG1478 or U0126, MEK phosphorylation was blocked. In addition, the investigation of the expression of proteins downstream of MEK demonstrated that EGF does not significantly affect the phosphorylation level of extracellular-signal-regulated kinase (ERK), ribosomal protein S6 kinase (RSK) and Elk in mitotic cells (P>0.05). The results showed that MEK expression is gradually inhibited from cell interphase to mitosis, and that MEK downstream signaling is affected by this inhibition, which probably reflects the requirements of cell physiology during mitosis.

A gain-of-function mutant p53-HSF1 feed forward circuit governs adaptation of cancer cells to proteotoxic stress

To overcome proteotoxic stress inherent to malignant transformation, cancer cells induce a range of adaptive mechanisms, with the master transcription factor heat-shock factor 1 (HSF1)-orchestrated response taking center stage. Here we define a novel gain-of-function of mutant p53 (mutp53), whereby mutp53-overexpressing cancer cells acquire superior tolerance to proteotoxic stress. mutp53 via constitutive stimulation of EGFR and ErbB2 signaling hyperactivates the MAPK and PI3K cascades, which induce stabilization and phosphoactivation of HSF1 on Ser326. Moreover, mutp53 protein via direct interaction with activated p-Ser326 HSF1 facilitates HSF1 recruitment to its specific DNA-binding elements and stimulates transcription of heat-shock proteins including Hsp90. In turn, induced Hsp90 stabilizes its oncogenic clients including EGFR, ErbB2 and mutp53, thereby further reinforcing oncogenic signaling. Thus, mutp53 initiates a feed forward loop that renders cancer cells more resistant to adverse conditions, providing a strong survival advantage.

Roles for the mitogen-activated protein kinase (MAPK) phosphatase, DUSP1, in feedback control of inflammatory gene expression and repression by dexamethasone

Glucocorticoids act on the glucocorticoid receptor (NR3C1) to repress inflammatory gene expression. This is central to their anti-inflammatory effectiveness and rational improvements in therapeutic index depend on understanding the mechanism. Human pulmonary epithelial A549 cells were used to study the role of the mitogen-activated protein kinase (MAPK) phosphatase, dual-specificity phosphatase 1 (DUSP1), in the dexamethasone repression of 11 inflammatory genes induced, in a MAPK-dependent manner, by interleukin-1β (IL1B). Adenoviral over-expression of DUSP1 inactivated MAPK pathways and reduced expression of all 11 inflammatory genes. IL1B rapidly induced DUSP1 expression and RNA silencing revealed a transient role in feedback inhibition of MAPKs and inflammatory gene expression. With dexamethasone, which induced DUSP1 expression, plus IL1B (co-treatment), DUSP1 expression was further enhanced. At 1 h, this was responsible for the dexamethasone inhibition of IL1B-induced MAPK activation and CXCL1 and CXCL2 mRNA expression, with a similar trend for CSF2. Whereas, CCL20 mRNA was not repressed by dexamethasone at 1 h, repression of CCL2, CXCL3, IL6, and IL8 was unaffected, and PTGS2 repression was partially affected by DUSP1 knockdown. At later times, dexamethasone repression of MAPKs was unaffected by DUSP1 silencing. Likewise, 6 h post-IL1B, dexamethasone repression of all 11 mRNAs was essentially unaffected by DUSP1 knockdown. Qualitatively similar data were obtained for CSF2, CXCL1, IL6, and IL8 release. Thus, despite general roles in feedback inhibition, DUSP1 plays a transient, often partial, role in the dexamethasone-dependent repression of certain inflammatory genes. Therefore this also illustrates key roles for DUSP1-independent effectors in mediating glucocorticoid-dependent repression.

c-Fos mediates repression of the apical sodium-dependent bile acid transporter by fibroblast growth factor-19 in mice

Fibroblast growth factor-19 (FGF-19), a bile acid-responsive enterokine, is secreted by the ileum and regulates a variety of metabolic processes. These studies examined the signal transduction pathways operant in FGF-19-mediated repression of the apical sodium-dependent bile acid transporter (ASBT). Responses to FGF-19 were assessed in Caco-2 and CT-26 cells and in mice where c-fos was conditionally silenced in the intestine by a cre-lox strategy. FGF-19 treatment of Caco-2 cells or wild-type mice led to a significant reduction in ASBT protein expression and enhanced phosphorylation of extracellular signaling kinase 1/2 (ERK1/2), c-Fos, and c-Jun. FGF-19 treatment of Caco-2 cells led to a reduction in activity of the human ASBT promoter and this repression could be blocked by treatment with a mitogen-activated protein kinase/ERK kinase (MEK1/2) inhibitor or by silencing jun kinase 1, jun kinase 2, c-fos, or c-jun. Site directed mutagenesis of a c-fos binding element in the ASBT promoter blocked FGF-19-mediated repression in luciferase reporter constructs. ASBT promoter activity was repressed by FGF-19 in CT-26 cells and this repression could be reduced by MEK1/2 inhibition or silencing c-fos. FGF-19-mediated repression of ASBT protein expression was abrogated in mice where c-fos was conditionally silenced in the intestine. In contrast, ASBT was repressed in the c-Fos expressing gallbladders of the same mice. The studies demonstrate that FGF-19 represses the expression of ASBT in the ileum and gallbladder via a signal transduction pathway involving MEK1/2, ERK1/2, JNK1, JNK2, and c-Fos.

Targeting the eIF4A RNA helicase blocks translation of the MUC1-C oncoprotein

The oncogenic MUC1 C-terminal subunit (MUC1-C) subunit is aberrantly overexpressed in most human breast cancers by mechanisms that are not well understood. The present studies demonstrate that stimulation of non-malignant MCF-10A cells with epidermal growth factor (EGF) or heregulin (HRG) results in marked upregulation of MUC1-C translation. Growth factor-induced MUC1-C translation was found to be mediated by PI3KAKT, and not by MEKERK1/2, signaling. We also show that activation of the mammalian target of rapamycin complex 1 (mTORC1)ribosomal protein S6 kinase 1 (S6K1) pathway decreases tumor suppressor programmed cell death protein 4 (PDCD4), an inhibitor of the eIF4A RNA helicase, and contributes to the induction of MUC1-C translation. In concert with these results, treatment of growth factor-stimulated MCF-10A cells with the eIF4A RNA helicase inhibitors, silvestrol and CR-1-31-B, blocked increases in MUC1-C abundance. The functional significance of the increase in MUC1-C translation is supported by the demonstration that MUC1-C, in turn, forms complexes with EGF receptor (EGFR) and promotes EGFR-mediated activation of the PI3KAKT pathway and the induction of growth. Compared with MCF-10A cells, constitutive overexpression of MUC1-C in breast cancer cells was unaffected by EGF stimulation, but was blocked by inhibiting PI3KAKT signaling. The overexpression of MUC1-C in breast cancer cells was also inhibited by blocking eIF4A RNA helicase activity with silvestrol and CR-1-31-B. These findings indicate that EGF-induced MUC1-C expression is mediated by the PI3KAKT pathway and the eIF4A RNA helicase, and that this response promotes EGFR signaling in an autoinductive loop. The findings also indicate that targeting the eIF4A RNA helicase is a novel approach for blocking MUC1-C overexpression in breast cancer cells.

DHEA inhibits measles virus through a mechanism independent of its ability to modulate the Raf/MEK/ERK signaling pathway

Aim: Despite the existence of an effective vaccine, measles infection is still frequent in many developing countries with reduced health infrastructure, and it is one of the major causes of child death globally. In the past decade numerous outbreaks have occurred in developed countries, giving a fresh impetus to antiviral research against measles virus. The aim of this study was to investigate the antiviral activity of the natural steroid hormone DHEA against measles virus and the role of the Raf/MEK/ERK signaling pathway in viral multiplication and DHEA’s antiviral activity. Materials & methods: The antiviral activity of DHEA and two ERK modulators, UO126 and anisomycin, was determined using a virus yield reduction assay. Furthermore, we studied DHEA’s virucidal activity and the viral multiplication step affected by the compound. The effect of virus infection on the Raf/MEK/ERK pathway and the activity of those compounds against measles virus spread and induced cytopathic effect were studied using western blot and indirect immunofluorescence. Results & conclusion: We found that DHEA and UO126 are active against measles virus and that they are able to diminish virus-induced cytopathic effects. Also, our study showed that early events in the viral multiplication cycle trigger ERK activation, suggesting that DHEA, a Raf/MEK/ERK modulator, may not exert its antiviral activity through the modulation of this pathway. Our results may provide a first step in the development of new antiviral agents against measles virus.

In vitro antiviral activity of dehydroepiandrosterone, 17 synthetic analogs and ERK modulators against herpes simplex virus type 1

In the present study the in vitro antiviral activity of dehydroepiandrosterone (DHEA) and 17 synthetic derivatives against herpes simplex type 1 (HSV-1) was determined. DHEA, epiandrosterone (EA), two synthetic DHEA analogs and three synthetic EA analogs showed a selective inhibitory effect on HSV in vitro multiplication. DHEA and E2, a synthetic derivative of EA, were not found to be virucidal to cell-free HSV-1 and did not impair virus adsorption or penetration. We determined that treatment with both compounds decreased viral protein synthesis. Moreover, inhibitory effect of DHEA and E2 on extracellular viral titer was stronger than the inhibition found on total viral infectivity, suggesting that the antiherpetic activity of these compounds may also be in part due to an inhibition in virus formation and release. Since DHEA is a known Raf/MEK/ERK signaling pathway activator, we studied the role of this pathway on HSV-1 infection. ERK1/2 phosphorylation was stimulated in HSV-1 infected cultures. UO126, a Raf/MEK/ERK signaling pathway inhibitor, impaired viral multiplication, while anisomycin, an activator of this pathway, enhanced it. Treatment with DHEA 6 h before infection enhanced HSV-1 multiplication. On the contrary, pre-treatment with E2, which does not modulate Raf/MEK/ERK signaling pathway, did not produce an increase of viral replication. Taking together these results, the antiviral activity of DHEA seems to occur via a mechanism independent of its ability to modulate ERK phosphorylation.

TEC and MAPK Kinase Signalling Pathways in T helper (TH) cell Development, TH2 Differentiation and Allergic Asthma

Significant advances in our understanding of the signalling events during T cell development and differentiation have been made in the past few decades. It is clear that ligation of the T cell receptor (TCR) triggers a series of proximal signalling cascades regulated by an array of protein kinases. These orchestrated and highly regulated series of events, with differential requirements of particular kinases, highlight the disparities between αβ+CD4+ T cells. Throughout this review we summarise both new and old studies, highlighting the role of Tec and MAPK in T cell development and differentiation with particular focus on T helper 2 (TH2) cells. Finally, as the allergy epidemic continues, we feature the role played by TH2 cells in the development of allergy and provide a brief update on promising kinase inhibitors that have been tested in vitro, in pre-clinical disease models in vivo and into clinical studies.

Activation and induction of cytosolic phospholipase A2 by TNF-α mediated through Nox2, MAPKs, NF-κB, and p300 in human tracheal smooth muscle cells

Cytosolic phospholipase A(2) (cPLA(2)) plays a pivotal role in mediating agonist-induced arachidonic acid (AA) release for prostaglandin (PG) synthesis during inflammation triggered by tumor necrosis factor-α (TNF-α). However, the mechanisms underlying TNF-α-induced cPLA(2) expression and PGE(2) synthesis in human tracheal smooth muscle cells (HTSMCs) remain unknown. Here, we report that TNF-α-induced cPLA(2) protein and mRNA expression, PGE(2) production, and phosphorylation of p42/p44 MAPK, p38 MAPK, and JNK1/2, which were attenuated by pretreatment with a ROS scavenger [N-acetyl-L-cysteine, (NAC)] and the inhibitors of NADPH oxidase [apocynin (APO) and diphenyleneiodonium chloride (DPI)], MEK1/2 (U0126), p38 MAPK (SB202190), and JNK1/2 (SP600125) or transfection with siRNA of Nox2, p47(phox) , MEK1, p42, p38, or JNK2. TNF-α-induced cPLA(2) expression was also inhibited by pretreatment with a selective NF-κB inhibitor [helenalin (HLN)] or transfection with dominant negative mutants of NF-κB inducing kinase (NIK) or IκB kinase (IKK)α/β. TNF-α-induced NF-κB translocation was blocked by pretreatment with NAC, DPI, APO, or HLN, but not by U0126, SB202190, or SP600125. In addition, pretreatment with curcumin (a p300 inhibitor) or transfection with p300 siRNA blocked cPLA(2) expression and PGE(2) synthesis induced by TNF-α. We further confirmed that p300 was associated with the cPLA(2) promoter which was dynamically linked to histone H4 acetylation stimulated by TNF-α, determined by chromatin immunoprecipitation assay. Association of p300 and histone H4 to cPLA(2) promoter was inhibited by U0126, SB202190, and SP600125. These results suggested that in HTSMCs, activation of p47(phox) , MAPKs, NF-κB, and p300 is essential for TNF-α-induced cPLA(2) expression and PGE(2) release.

Differential effects of growth factors on oligodendrocyte progenitor migration

Oligodendrocytes are myelinating cells of the CNS that originate as progenitor cells (OP) in discrete areas of the developing brain. During brain development, OP migrate significant distances prior to proliferating and myelinating the axons of the putative white matter tracts. Growth factors play a major regulatory role in the behavior of OP. Specifically, platelet-derived growth factor A (PDGF-A) and fibroblast growth factor 2 (FGF2) are two of the most well characterized regulators of OP development. Both growth factors interact with tyrosine kinase receptors, activating various intracellular signaling pathways. The current study advances our earlier research by comparing the effects of both PDGF-A and FGF2 on OP migration. Our results show that activation of ERK is required for OP migration. These findings correlate well with our previous demonstration of the ERK pathway mediating PDGF-A induced OP migration. We also demonstrate the significance of threshold levels of growth factors and temporal regulation for OP migration. In addition, ERK activation alone is not sufficient to induce OP migration. The current research supports the involvement of the non-ERK mediated signaling pathway in OP migration.

Alum interaction with dendritic cell membrane lipids is essential for its adjuvanticity

As an approved vaccine adjuvant for use in humans, alum has vast health implications, but, as it is a crystal, questions remain regarding its mechanism. Furthermore, little is known about the target cells, receptors, and signaling pathways engaged by alum. Here we report that, independent of inflammasome and membrane proteins, alum binds dendritic cell (DC) plasma membrane lipids with substantial force. Subsequent lipid sorting activates an abortive phagocytic response that leads to antigen uptake. Such activated DCs, without further association with alum, show high affinity and stable binding with CD4(+) T cells via the adhesion molecules intercellular adhesion molecule-1 (ICAM-1) and lymphocyte function-associated antigen-1 (LFA-1). We propose that alum triggers DC responses by altering membrane lipid structures. This study therefore suggests an unexpected mechanism for how this crystalline structure interacts with the immune system and how the DC plasma membrane may behave as a general sensor for solid structures.

Glucocorticoids inhibit IL-1beta-induced GM-CSF expression at multiple levels: roles for the ERK pathway and repression by MKP-1

In the present study, IL (interleukin)-1beta increased GM-CSF (granulocyte/macrophage colony-stimulating factor) expression from pulmonary A549 cells and primary HBE (human bronchial epithelial) cells. These responses were repressed by the glucocorticoid dexamethasone, allowing the use of A549 cells as a relevant model. IL-1beta induced GM-CSF release into the culture medium by 6 h and in cell lysates (cytosolic) at 2 h. These effects were profoundly inhibited by dexamethasone, yet IL-1beta-induced GM-CSF mRNA and unspliced nRNA (nuclear RNA; a surrogate of transcription rate) were modestly inhibited by dexamethasone at times up to 2 h. Although this indicates an effect on protein synthesis, actinomycin D chase experiments also indicated post-transcriptional repression by dexamethasone. Dexamethasone-dependent mRNA repression increased with time and was prevented by translational blockade. In addition, dexamethasone and the dissociated steroid RU24858 repressed GM-CSF release in an actinomycin D-sensitive manner, thereby implicating glucocorticoid-induced gene expression. At 2 h, IL-1beta-induced expression of GM-CSF protein, but not mRNA, was sensitive to the MEK [MAPK (mitogen-activated protein kinase)/ERK (extracellular-signal-regulated kinase) kinase] inhibitors PD098059 and U0126. Although this indicates a role for the MEK/ERK pathway in GM-CSF translation, PD098059 subsequently destabilized GM-CSF mRNA. Dexamethasone and RU24858 both reduced IL-1beta-induced ERK phosphorylation and increased MKP-1 (MAPK phosphatase-1) expression. Inhibition of ERK phosphorylation was reproduced by MKP-1 overexpression and prevented by MKP-1-targeting siRNA (small interfering RNA). Since MKP-1 prevented GM-CSF expression by transcriptional, post-transcriptional and translational processes, we propose that glucocorticoids induce MKP-1 expression to reduce both MEK/ERK activation and GM-CSF protein synthesis. Thus de novo gene expression, particularly of MKP-1, is involved in the repressive effects of glucocorticoids.

Mitogen-activated protein kinase phosphatase-1 negatively regulates the expression of interleukin-6, interleukin-8, and cyclooxygenase-2 in A549 human lung epithelial cells

Mitogen-activated protein kinase phosphatase (MKP)-1 is a protein phosphatase that regulates the activity of p38 mitogen-activated protein (MAP) kinase and c-Jun NH2-terminal kinase (JNK) and, to lesser extent, p42/44 extracellular signal-regulated kinase. Studies with MKP-1(-/-) mice show that MKP-1 is a regulating factor suppressing excessive cytokine production and inflammatory response. The data on the role of MKP-1 in the regulation of inflammatory gene expression in human cells are much more limited. In the present study, we investigated the effect of MKP-1 on the expression of interleukin (IL)-6, IL-8 and cyclooxygenase (COX)-2 in response to stimulation with cytokines (tumor necrosis factor, IL-1beta, and interferon-gamma; 10 ng/ml each) in A549 human lung epithelial cells. Cytokines enhanced p38 and JNK phosphorylation and MKP-1 expression. p38 MAP kinase inhibitors 4-[4-(4-fluorophenyl)-5-(4-pyridinyl)-1H-imidazol-2-yl] phenol (SB202190) and 1-(5-tert-butyl-2-p-tolyl-2H-pyrazol-3-yl)-3(4-(2-morpholin-4-yl-ethoxy)naphthalen-1-yl)urea (BIRB 796) inhibited cytokine-induced phosphorylation of p38 substrate MAP kinase-activated protein kinase 2 and expression of IL-6, IL-8, and COX-2. An aminopyridine-based JNK inhibitor, N-(4-amino-5-cyano-6-ethoxypyridin-2-yl)-2-(2,5-dimethoxyphenyl)acetamide (JNK inhibitor VIII), inhibited phosphorylation of a JNK substrate c-Jun but did not have any effect on IL-6, IL-8, or COX-2 expression. Down-regulation of MKP-1 with small interfering RNA enhanced p38 and JNK phosphorylation and increased IL-6, IL-8, and COX-2 expression in A549 cells. In conclusion, cytokine-induced MKP-1 expression was found to negatively regulate p38 phosphorylation and the expression of IL-6, IL-8, and COX-2 in human pulmonary epithelial cells. Our results suggest that MKP-1 is an important negative regulator of inflammatory gene expression in human pulmonary epithelial cells, and compounds that enhance MKP-1 may have anti-inflammatory effects and control inflammatory response in the human lung.

Insulin-like growth factor-induced signals activate mitochondrial respiration

From experiments with lower eukaryotes it is known that the metabolic rate and also the rate of aging are tightly controlled by the insulin-like growth factor (IGF)/insulin signal transduction pathway. The mitochondrial theory of aging implies that an increased metabolic rate leads to increased mitochondrial activity; increased production of reactive oxygen species due to these alterations would speed up the aging process. To address the question if mitochondrial activity is influenced by insulin/IGF signaling, we have established an experimental system to determine the influence of IGF-I-dependent signaling on mitochondrial function. We used DU145 prostate cancer cells, known for the intact IGF signal transduction pathway, to address the influence of IGF receptor activation on mitochondrial function by high-resolution respirometry. These experiments revealed that indeed mitochondrial function is regulated by IGF signaling, and up-regulation of respiration seems to require phosphoinositide 3-kinase/AKT signaling, but is independent of IGF effects on cell cycle progression. Collectively these data establish a regulatory cross-talk between insulin/IGF signal transduction and mitochondrial function, two major pathways implicated in controlling the rate of aging.

Retinol and retinoic acid increase MMP-2 activity by different pathways in cultured Sertoli cells

Diseases such as atherosclerosis, arthritis and cancer have been related with imbalance in ROS production and failures in regulation of the MMPs. Authors suggested a relationship between MPP activity and ROS. Our research group has demonstrated that retinol 7 microM induced changes in Sertoli cell metabolism linking retinol treatment and oxidative stress. We verified MMP activity in Sertoli cells treated with vitamin A using gelatin zymography. We found that retinol (7 microM) and retinoic acid (1 nM) induced MMP-2 activity in Sertoli cells. Antioxidants reversed retinol-induced but not retinoic acid-induced MMP-2 activity. Moreover, retinol but not retinoic acid increased ROS production quantified by DCFH-DA oxidation. We found that retinol and retinoic acid induced ERK1/2 phosphorylation, but only retinol-increased MMP-2 activity was inhibited by UO126, an ERK1/2 phosphorylation inhibitor. Our findings suggested that retinol-induced MMP-2 activity, but not retinoic acid-induced MMP-2 activity, was related to ERK1/2 phosphorylation and ROS production.

Initiation of oligodendrocyte progenitor cell migration by a PDGF-A activated extracellular regulated kinase (ERK) signaling pathway

During CNS development, oligodendrocyte progenitor (OP) cells migrate from germinal zones to presumptive white matter tracts to generate myelinating oligodendrocytes. In vitro and in vivo studies indicate that platelet-derived growth factor-A (PDGF-A) is a potent chemoattractant for OP cells and important for normal distribution throughout the developing CNS. However, PDGF-A does not localize in concentration gradients corresponding to OP migratory pathways, as would be expected for a chemoattractant to direct migration. Therefore, the mechanism by which PDGF-A regulates OP distribution remains to be clarified. Here we show that PDGF-A induces OP migration and continuous exposure to PDGF-A is not required to maintain migration. Using pharmacological inhibitors, we show that a self-sustaining extracellular-regulated-kinase signaling pathway drives OP migration for up to 72 hours after the initial PDGF stimulus. These findings indicate PDGF-A may act to mobilize OP cells that then respond to distinct directional signals to distribute appropriately within the CNS.

Effects of the marine toxins okadaic acid and palytoxin on mussel phagocytosis

The present study analyzes the effects of the marine toxins okadaic acid (OA) and palytoxin (PTX) on the phagocytic activity of immunocytes from the mussel Mytilus galloprovincialis. In particular, we describe how the effects of the two biotoxins are influenced by the temperature and experimental stress applied before hemolymph withdrawal. The collected data indicate that OA increases phagocytic activity only when hemolymph incubation is performed at 25 degrees C, but not at 20 degrees C, suggesting a certain degree of dependence of OA effects from the status of mussel immunocytes. Conversely, PTX plays an active role in immunocyte signalling transduction pathways, increases the phagocytic activity and markedly promotes the involvement of p38 mitogen-activated protein (MAP) kinase in phagocytosis. Overall, we conclude that both OA and PTX influence mussel phagocytic activity, and the toxic effects may depend on both the mollusc conditions and the activation of specific signalling pathways.

Thalidomide induces limb anomalies by PTEN stabilization, Akt suppression, and stimulation of caspase-dependent cell death

Thalidomide, a drug used for the treatment of multiple myeloma and inflammatory diseases, is also a teratogen that causes birth defects, such as limb truncations and microphthalmia, in humans. Thalidomide-induced limb truncations result from increased cell death during embryonic limb development and consequential disturbance of limb outgrowth. Here we demonstrate in primary human embryonic cells and in the chicken embryo that thalidomide-induced signaling through bone morphogenetic proteins (Bmps) protects active PTEN from proteasomal degradation, resulting in suppression of Akt signaling. As a consequence, caspase-dependent cell death is stimulated by the intrinsic and Fas death receptor apoptotic pathway. Most importantly, thalidomide-induced limb deformities and microphthalmia in chicken embryos could be rescued by a pharmacological PTEN inhibitor as well as by insulin, a stimulant of Akt signaling. We therefore conclude that perturbation of PTEN/Akt signaling and stimulation of caspase activity is central to the teratogenic effects of thalidomide.

Thalidomide induces limb anomalies by PTEN stabilization, Akt suppression, and stimulation of caspase-dependent cell death

Thalidomide, a drug used for the treatment of multiple myeloma and inflammatory diseases, is also a teratogen that causes birth defects, such as limb truncations and microphthalmia, in humans. Thalidomide-induced limb truncations result from increased cell death during embryonic limb development and consequential disturbance of limb outgrowth. Here we demonstrate in primary human embryonic cells and in the chicken embryo that thalidomide-induced signaling through bone morphogenetic proteins (Bmps) protects active PTEN from proteasomal degradation, resulting in suppression of Akt signaling. As a consequence, caspase-dependent cell death is stimulated by the intrinsic and Fas death receptor apoptotic pathway. Most importantly, thalidomide-induced limb deformities and microphthalmia in chicken embryos could be rescued by a pharmacological PTEN inhibitor as well as by insulin, a stimulant of Akt signaling. We therefore conclude that perturbation of PTEN/Akt signaling and stimulation of caspase activity is central to the teratogenic effects of thalidomide.

Central role of the MEK/ERK MAP kinase pathway in a mouse model of rheumatoid arthritis: potential proinflammatory mechanisms

OBJECTIVE

To evaluate the role of the MEK/ERK MAP kinase pathway in murine collagen-induced arthritis (CIA) using the selective MEK inhibitor PD184352. We examined the effects of the inhibitor in cytokine-stimulated synovial fibroblasts and in cytokine-induced arthritis in rabbits to investigate its antiinflammatory mechanisms.

METHODS

Murine CIA was used to assess the effects of the selective MEK inhibitor on paw edema, clinical scores, weight loss, histopathologic features, and joint levels of p-ERK. Western blotting and immunohistochemistry techniques were used to assess p-ERK in human and rabbit synovial fibroblasts and synovial tissue from rheumatoid arthritis (RA) patients. Interleukin-1alpha (IL-1alpha)-stimulated stromelysin production in rabbit synovial fibroblasts was assessed by enzyme-linked immunosorbent assay. A rabbit IL-1alpha-induced arthritis model was used to assess the effects of the inhibitor on IL-1alpha-induced MEK activity, stromelysin production, and cartilage degradation.

RESULTS

In the CIA model, PD184352 inhibited paw edema and clinical arthritis scores in a dose-dependent manner. Disease-induced weight loss and histopathologic changes were also significantly improved by treatment. Inhibition of disease-induced p-ERK levels in the joints was seen with the inhibitor. Levels of p-ERK in the synovium were higher in RA patients than in normal individuals. PD184352 reduced IL-1alpha-induced p-ERK levels in human RA synovial fibroblasts. The production of p-ERK and stromelysin was also inhibited in IL-1alpha-stimulated rabbit synovial fibroblasts. We observed IL-1alpha-induced p-ERK in the synovial lining, subsynovial vasculature, and articular chondrocytes. IL-1alpha-induced stromelysin production and proteoglycan loss from the articular cartilage were reduced by PD184352.

CONCLUSION

These data demonstrate the inhibition of murine CIA by PD184352, support the hypothesis that antiinflammatory activity contributes to the mechanism of action of the inhibitor, and suggest that a selective inhibitor may effectively treat RA and other inflammatory disorders.

Rifampin inhibits prostaglandin E2 production and arachidonic acid release in human alveolar epithelial cells

Rifampin, a potent antimicrobial agent, is a major drug in the treatment of tuberculosis. There is evidence that rifampin also serves as an immunomodulator. Based on findings that arachidonic acid and its metabolites are involved in the pathogeneses of Mycobacterium tuberculosis infections, we investigated whether rifampin affects prostaglandin E(2) (PGE(2)) production in human alveolar epithelial cells stimulated with interleukin-1beta. Rifampin caused a dose-dependent inhibition of PGE(2) production. At doses of 100, 50, and 25 microg/ml, it inhibited PGE(2) production by 75%, 59%, and 45%, respectively (P < 0.001). Regarding the mechanism involved, rifampin caused a time- and dose-dependent inhibition of arachidonic acid release from the alveolar cells. At doses of 100, 50, 25, and 10 mug/ml, it significantly inhibited the release of arachidonic acid by 93%, 64%, 58%, and 35%, respectively (P < 0.001). Rifampin did not affect the phosphorylation of cytosolic phospholipase A(2) or the expression of cyclooxygenase-2. The inhibition of PGE(2), and presumably other arachidonic acid products, probably contributes to the efficacy of rifampin in the treatment of tuberculosis and may explain some of its adverse effects.

Sphingosine-1-phosphate stimulates aldosterone secretion through a mechanism involving the PI3K/PKB and MEK/ERK 1/2 pathways

We reported recently that sphingosine-1-phosphate (S1P) is a novel regulator of aldosterone secretion in zona glomerulosa cells of adrenal glands and that phospholipase D (PLD) is implicated in this process. We now show that S1P causes the phosphorylation of protein kinase B (PKB) and extracellularly regulated kinases 1/2 (ERK 1/2), which is an indication of their activation, in these cells. These effects are probably mediated through the interaction of S1P with the Gi protein-coupled receptors S1P1/3, as pretreatment with pertussis toxin or with the S1P1/3 antagonist VPC 23019 completely abolished the phosphorylation of these kinases. Inhibitors of phosphatidylinositol 3-kinase (PI3K) or mitogen-activated protein kinase kinase (MEK) blocked S1P-stimulated aldosterone secretion. This inhibition was only partial when the cells were incubated independently with inhibitors of each pathway. However, aldosterone output was completely blocked when the cells were pretreated with LY 294002 and PD 98059 simultaneously. These inhibitors also blocked PLD activation, which indicates that this enzyme is downstream of PI3K and MEK in this system. We propose a working model for S1P in which stimulation of the PI3K/PKB and MEK/ERK pathways leads to the stimulation of PLD and aldosterone secretion.

Inhibition of the MEK/ERK pathway reduces microglial activation and interleukin-1-beta expression in spinal cord ischemia/reperfusion injury in rats

OBJECTIVES

Ischemic spinal cord injury is a serious complication of aortic surgery. Although the extracellular signal-regulated kinases 1 and 2 are generally regarded as related to cell proliferation and survival, increasing evidence suggests that the role of the extracellular signal-regulated kinase pathway in ischemia/reperfusion injury is much more sophisticated.

METHODS

Spinal cord ischemia in rats was induced by occluding the thoracic descending aorta with a balloon catheter introduced through a femoral artery, accompanied by concomitant exsanguination. Rats in the control group were given dimethyl sulfoxide (vehicle) before undergoing spinal cord ischemia/reperfusion injury. In the U0126-treated group, rats were pretreated with a specific inhibitor of the mitogen-activated protein kinase/extracellular signal-regulated kinases 1 and 2, U0126, to inhibit extracellular signal-regulated kinases 1 and 2 phosphorylation. The sham-operated rats underwent aortic catheterization without occlusion. Parameters, including neurologic performance, neuronal survival, inflammatory cell infiltration, and interleukin-1beta production in the spinal cords, were compared between groups.

RESULTS

Early extracellular signal-regulated kinases 1 and 2 phosphorylation was observed after injury in the control group, followed by abundant microglial accumulation in the infarct area and increased interleukin-1beta expression. In the U0126 group, U0126 treatment completely blocked extracellular signal-regulated kinases 1 and 2 phosphorylation. Microglial activation and spinal cord interleukin-1beta levels were significantly reduced. Neuronal survival and functional performance were improved.

CONCLUSIONS

The mitogen-activated protein kinase/extracellular signal-regulated kinase pathway may play a noxious role in spinal cord ischemia/reperfusion injury by participating in inflammatory reactions and cytokine production. Targeting this pathway may be of potential value in terms of therapeutic intervention.

Matrix metalloproteinase-3 secretion from human pancreatic periacinar myofibroblasts in response to inflammatory mediators

OBJECTIVES

Matrix metalloproteinases (MMPs) play roles in the pathophysiology of pancreatic disorders. However, the regulation of MMP-3 secretion in the pancreas remains unclear. In this study, we assessed the expression of MMP-3 in human pancreatic periacinar myofibroblasts.

METHODS

MMP-3 secretion and MMP-3 mRNA expression were determined by enzyme-linked immunosorbent assay and real-time polymerase chain reaction, respectively.

RESULTS

In human pancreatic myofibroblasts, MMP-3 secretion and mRNA expression were induced by interleukin (IL)-17, IL-1beta, and tumor necrosis factor (TNF) -alpha, respectively. The effects of IL-17 were detected as similar in extent to those induced by IL-1beta or TNF-alpha. Costimulation by IL-17 plus IL-1beta and/or IL-17 plus TNF-alpha induced a synergistic increase in MMP-3 secretion, although the costimulatory effects of these combinations were not detected in tissue inhibitor of matrix metalloproteinase-1 secretion. Adenovirus-mediated transfer of a stable form of IkappaBalpha markedly inhibited the effects of IL-17, IL-1beta, and TNF-alpha. Mitogen-activated protein kinase inhibitors (U0126, PD098059, and SB203580) also blocked MMP-3 secretion. These findings indicate a role for nuclear factor-kappaB and mitogen-activated protein kinases in cytokine-induced MMP-3 secretion.

CONCLUSIONS

Pancreatic periacinar myofibroblasts actively secrete MMP-3 in response to IL-17, IL-1beta, and TNF-alpha. Pancreatic myofibroblasts may play an important role in extracellular matrix turnover via MMP-3 secretion in the pancreas.

Concomitant activation of extracellular signal-regulated kinase and induction of COX-2 stimulates maximum prostaglandin E2 synthesis in human airway epithelial cells

The intracellular regulation and kinetics of prostaglandin (PG)E(2) synthesis in human airway epithelial (NCI-H292) cells was investigated. Interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha and lipopolysaccharide (LPS) all induced PGE(2) synthesis (p<0.001) and transient (5-15 min) phosphorylation of extracellular signal-regulated kinase (ERK). Phorbol myristate acetate (PMA) and calcium ionophore, A23187 further enhanced PGE(2) synthesis (p<0.001) and caused phosphorylation of ERK that was sustained for up to 16 h. COX-2 protein expression and PGE(2) synthesis were increased following exposure to combinations of stimuli that increased intracellular Ca(2+), and activated protein kinase C as well as ERK. Inhibition of ERK almost completely abrogated PGE(2) synthesis in response to all stimuli. Sustained, maximum PGE(2) synthesis was observed when cells were stimulated such that ERK phosphorylation was concomitant with increased COX-2 protein expression. These results argue against redundancy in pathways for PGE(2) synthesis, and suggest that at various stages of inflammation different stimuli may influence ERK activation and COX-2 expression, so as to tightly regulate the kinetics and amount of PGE(2) produced by airway epithelial cells in response to lung inflammation.

Involvement of PKC, p38 MAPK and AP-2 in IL-1beta-induced expression of cyclooxygenase-2 in human pulmonary epithelial cells

OBJECTIVE

The aim of this study was to identify the signal molecules involved in IL-1beta-induced expression of cyclooxygenase (COX)-2 in human pulmonary epithelial (A549) cells.

METHODS

A549 cells were stimulated with IL-1beta in the presence or absence of H-7 (a protein kinase C inhibitor), SB203580 (a p38 mitogen-activated protein kinase inhibitor) and PD098059 (a mitogen-activated and extracellular regulated kinase kinase (MEK1) inhibitor). The A549 cells were also transfected with adenovirus vector encoding activator protein (AP)-2alpha, or a plasmid containing a dominant-negative gene (AP-2Delta), in the presence or absence of IL-1beta.

RESULTS

IL-1beta induced expression of the COX-2 mRNA and protein in A549 cells in a time- and dose-dependent manner. SB203580 and H-7, but not PD098059, inhibited IL-1beta-induced expression of COX-2 protein. Overexpression of AP-2alpha increased expression of the COX-2 protein, whereas AP-2Delta decreased IL-1beta-induced COX-2 expression.

CONCLUSION

Protein kinase C, p38 mitogen-activated protein kinase and transcriptional factor AP-2alpha may play important roles in regulating IL-1beta-induced COX-2 expression in human pulmonary epithelial cells.

Cyclooxygenase inhibitors not inhibit resting lung cancer A549 cell proliferation

Cyclooxygenase (COX) inhibitors were regarded as anticarcinogenic agents for lung cancer at least partly via PGE2; but these were based on cytokin stimulation experiment on A549 cell. In order to clarify whether COX inhibitors directly inhibit A549 cell, three COX inhibitors, NS398 (selective COX-2 inhibitor), SC560 (selective COX-1 inhibitor), and acetyl salicylic acid (ASA, non-selective COX inhibitor), were studied. NS398, and ASA, can inhibit PGE2 generation via COX-2 inhibition. The viability of A549 cell was assayed by MTT. However, without cytokin stimulation, all the three inhibitors (NS398 0.2-20 microM; SC560 1.0-100 nM; ASA 0.01-1.0 mM) were not able to inhibit A549 cell proliferation, in the other way round, NS398 promoted cell growth. And arachidonic acid (AA) and lipopolysaccharide (LPS) did not disturb the property of its growth. These data suggested that without cytokin stimulation, COX and PGE2 may not be the kernel molecules involved in A549 cell proliferation, and COX inhibitors could not inhibit A549 cell growth directly.

Regulatory features of interleukin-1β-mediated prostaglandin E2 synthesis in airway smooth muscle

Exposure of airway smooth muscle (ASM) cells to the cytokine IL-1β results in an induction of PGE2 synthesis that affects numerous cell functions. Current dogma posits induction of COX-2 protein as the critical, obligatory event in cytokine-induced PGE2 production, although PGE2 induction can be inhibited without a concomitant inhibition of COX-2. To explore other putative regulatory features we examined the role of phospholipase A2 (PLA2) and PGE synthase (PGES) enzymes in IL-1β-induced PGE2 production. Treatment of human ASM cultures with IL-1β caused a time-dependent induction of both cytosolic PLA2 (cPLA2) and microsomal PGES (mPGES) similar to that observed for COX-2. Regulation of COX-2 and mPGES induction was similar, being significantly reduced by inhibition of p42/p44 or p38, whereas cPLA2 induction was only minimally reduced by inhibition of p38 or PKC. COX-2 and mPGES induction was subject to feed-forward regulation by PKA, whereas cPLA2 induction was not. SB-202474, an SB-203580 analog lacking the ability to inhibit p38 but capable of inhibiting IL-1β-induced PGE2 production, was effective in inhibiting mPGES but not COX-2 or cPLA2 induction. These data suggest that although COX-2, cPLA2, and mPGES are all induced by IL-β in human ASM cells, regulatory features of cPLA2 are dissociated, whereas those of COX-2 and mPGES are primarily associated, with regulation of PGE2 production. mPGES induction and, possibly, cPLA2 induction appear to cooperate with COX-2 to determine IL-1β-mediated PGE2 production in human ASM cells.

Up-regulation of astrocyte cyclooxygenase-2, CCAAT/enhancer-binding protein-homology protein, glucose-related protein 78, eukaryotic initiation factor 2 alpha, and c-Jun N-terminal kinase by a neurovirulent murine retrovirus

In susceptible strains of mice, infection with the mutant retrovirus MoMuLV-ts1 causes a neurodegeneration and immunodeficiency syndrome that resembles human human immunodeficiency virus-acquired immunodeficiency syndrome (HIV-AIDS). In this study the authors show increased expression of cyclooxygenase-2 (COX-2) in the brainstem tissues of ts1-infected mice. Up-regulated central nervous system (CNS) levels of this enzyme are associated with HIV-associated dementia and other inflammatory and neurodegenerative diseases such as amyotrophic lateral sclerosis, Alzheimer's disease, and Parkinson's disease. In brainstem sections, the authors find that astrocytes surrounding spongiform lesions contain increased amounts of immunoreactive COX-2. COX-2 is also up-regulated in cultured ts1-infected cells from the C1 astrocytic cell line, and activation of c-Jun N-terminal kinase, or JNK, pathway. Markers of endoplasmic reticulum (ER) stress, specifically the CCAAT/enhancer-binding protein (CHOP), the glucose-related protein 78 (GRP78), and phosphorylated eukaryotic initiation factor 2 alpha (eIF2 alpha), were also up-regulated in ts1-infected C1 astrocytes. Up-regulation of COX-2 and the above ER signaling factors was reversed by treatment of the infected cells with curcumin which specifically inhibits the JNK/c-Jun pathway. These findings indicate that the JNK/c-Jun pathway is most likely responsible for COX-2 expression induced by ts1 in astrocytes, and that ts1 infection in astrocytes may lead to up-regulation of both inflammatory and ER stress pathways in the central nervous system. Because COX-2 inhibitors are now widely used to treat inflammatory conditions in animals and humans, this finding suggests that these drugs may be useful for therapeutic intervention in neurodegenerative syndromes as well.

Novel p38 mitogen-activated protein kinase inhibitor R-130823 protects cartilage by down-regulating matrix metalloproteinase-1,-13 and prostaglandin E2 production in human chondrocytes

In order to study the involvement of mitogen-activated protein kinase p38 in osteoarthritis, we investigated the effect of novel p38 inhibitor R-130823 {2-(4-fluorophenyl)-4-(1-phenethyl-1,2,3,6-tetrahydropyridin-4-yl)-3-(pyridin-4-yl)-1H-pyrrole} on human chondrocytes and bovine cartilage. In human primary chondrocytes, the production of matrix metalloproteinase-13 and -1 (MMP-13 and -1) and prostaglandin E2 (PGE2) was induced by interleukin-1beta. Pretreatment with R-130823 inhibited the release of MMP-13, MMP-1 and PGE2 with IC50 values of 20, 230 and 3.9 nM, respectively. The inhibitory activity was also confirmed by a decrease in MMP-13 release from human chondrosarcoma cell line SW1353 with an IC50 value of 17 nM. Ribonuclease protection assay on human primary chondrocytes indicated that MMP-13 and MMP-1 mRNA levels almost reached the maximum 14 h after IL-1 stimulation, while cyclooxygenase-2 (COX-2) mRNA quickly reached the maximum 4 h after the stimulation. R-130823 down-regulated the steady-state levels of MMP-13 and MMP-1 mRNA with IC50 values of 4.2 and 79 nM, respectively. The COX-2 mRNA level was also suppressed with an IC50 value of 21 nM. In the explant culture of bovine nasal cartilage, R-130823 suppressed the collagen cleavage induced by interleukin-1alpha and oncostatin M, but not IL-1beta-mediated glycosaminoglycan release. These results suggest that activated p38 accelerates cartilage breakdown by enhancing the expression of MMPs responsible for collagen cleavage, which thus implies chondroprotective effects of p38 inhibitors in osteoarthritis.

Low concentrations of aggregated β-amyloid induce neurite formation via the neurotrophin receptor p75

Aggregated beta-amyloid (Abeta) binds to the neurotrophin receptor p75 and induces signaling. We examined this signaling process in different cell lines which express p75 either naturally (Schwannoma RN22 cells) or which are stably transfected with wild-type p75 (MDCKwt and PCNA cells) or with a truncated form of p75 comprising only extracellular and transmembrane domains (MDCKtm cells). While Abeta in higher concentrations (10-100 microM) is known to cause apoptosis via p75, our experiments focused on the effects of low concentrations of Abeta (25 nM) which may occur in early stages of Alzheimer disease. Application of Abeta caused tyrosine phosphorylation of wild-type p75 and induced the Ras-ERK pathway as has been reported for nerve growth factor (NGF). Since Ras activation and ERK phosphorylation (via MEK) could not be observed in MDCKtm cells and since they were clearly reduced in cells transfected with a p75 antisense construct, these effects should have been mediated by p75. Abeta also induced Ras and ERK activation in cerebellar neurons of 2-day-old rats which express p75 at that developmental stage but not TrkA; other Trk receptors were inhibited by K252a. In these neurons, Abeta led to quick formation, branching and elongation of processes. But while NGF distinctly promoted neurite branching and elongation, Abeta was less effective in neurite elongation and counts of small processes and of growth cones remained clearly elevated after 24-h stimulation; these peculiarities might be linked to aberrant neuronal connections reported for an animal model of Alzheimer disease. Essentially, the observed effects were mediated by interaction of Abeta and p75.

The mitogen-activated protein kinase dependent expression of prostaglandin H synthase-2 and interleukin-8 messenger ribonucleic acid by myometrial cells: the differential effect of stretch and interleukin-1{beta}

Infection and uterine stretch are the common causes of preterm labor. IL-1beta plays a key role in infection-induced preterm labor and increases prostaglandin H synthase 2 (PGHS-2) and IL-8 expression. We have shown that mechanical stretch of uterine myocytes in vitro up-regulates the expression of PGHS-2 and IL-8. In this study, we tested the hypotheses that both IL-1beta and mechanical stretch increase the myometrial expression of PGHS-2 and IL-8 via MAPK activation and that their effects are synergistic. MAPK activation was assessed in myocytes obtained from pregnant women undergoing cesarean section before the onset of labor after exposure to IL-1beta and stretch either alone or in combination. Specific inhibitors of ERK, p38, and c-Jun N-terminal kinase were used to define the role of each in the increased expression of PGHS-2 and IL-8 mRNA. We found that both IL-1beta and stretch activated all three MAPK subtypes but that they had no synergistic effect. The inhibitor studies showed that stretch-induced increases in both PGHS-2 and IL-8 mRNA expression were ERK1/2 and p38 dependent and that IL-1beta-induced increases of PGHS-2 mRNA expression were also ERK1/2 and p38 dependent, but those of IL-8 were dependent only on ERK1/2 activation. These data show that exposure of human uterine myocytes to both stretch and IL-1beta activates the MAPK system, which is responsible for the increase in PGHS-2 and IL-8 mRNA expression. We found no evidence of a synergistic effect of IL-1beta and stretch on myometrial expression of PGHS-2 and IL-8 mRNA.

Regulation of the cyclooxygenase-2 system by interleukin-1beta through mitogen-activated protein kinase signaling pathways: a comparative study of human neuroglioma and neuroblastoma cells

Glial activation and inflammation following brain injury may initiate and maintain the process of neurodegeneration. Both glia and neurons synthesize proinflammatory mediators such as interleukin 1 beta (IL-1beta), cytosolic phospholipase A2 (cPLA2), cyclooxygenase-2 (COX-2), and prostaglandins. The molecular mechanisms by which IL-1beta regulates inflammatory genes such as cPLA2 and COX-2 in glial and neuronal cells are poorly understood. We have studied IL-1beta-mediated gene regulation in an established glial and neuronal human cell lines. We report that IL-1beta induced cPLA2 and COX-2 mRNA and protein expression and subsequent prostaglandin E2 (PGE2) release in a time-dependent manner in H4 neuroglioma cells. Both SB203580 and PD98059 [p38 and p42/44 mitogen-activated protein kinase (MAPKs) inhibitors, respectively] reduced IL-1beta-induced PGE2 production, while only SB203580 reduced both cPLA2 and COX-2 expression. Similarly, in SKNSH neuroblastoma cells, both SB203580 and PD98059 reduced IL-1beta-induced PGE2 release, with no detectable COX-2 and cPLA2 protein expression in these cells. Our results indicate that the signaling mechanisms of p38 and p42/44 MAPKs play a role in IL-1beta-mediated PGE2 release in both of these cell lines, with differences upstream at the level of cPLA(2)/COX-2 expression. IL-1beta-induced cPLA2 and COX-2 gene expression is modulated through the p38 MAPK pathway in both neuroglioma and neuroblastoma cells. Understanding the signaling mechanisms involved in IL-1beta-mediated inflammatory processes in both glia and neuronal cells may provide potential targets for therapeutic intervention for neurological disorders.

Selective activation of the MEK-ERK pathway is regulated by mechanical stimuli in forming joints and promotes pericellular matrix formation

It is well established that local modification of extracellular matrix (ECM) hyaluronan composition is vital in the regulation of cell behavior. Indeed, the formation of articulating chick joint cavities, which requires mechanical stimuli derived from skeletal movement, is dependent upon the accumulation of an ECM rich in hyaluronan (HA). However, the mechanisms responsible for such precise mechano-dependent regulation of cell behavior and the formation of a HA-rich ECM remain undefined. Here we show that extracellular-regulated kinase 1/2 (ERK1/2) is selectively activated in cells at sites of cavity formation and activity diminished by in ovo immobilization that induces cartilaginous fusion across presumptive joint interzones. In vitro analyses offer mechanistic support for the role of mechanical stimuli in promoting a MEK-dependent activation of ERK1/2. In addition, our direct regulation of ERK1/2 phosphorylation status via modulation of its up-stream "classical cascade" activator either pharmacologically or by transfection with dominant negative or constitutively active Mek confirms the essential role for ERK1/2 activation in the elaboration of HA-rich pericellular matrices. Together, our findings demonstrate that the MEK-ERK pathway, regulated by mechanical stimuli, controls HA-rich matrix assembly. The precision of ERK1/2 activation selectively distinguishing cells at the joint line suggests that it directly contributes to the loss of tissue cohesion essential for generating HA-rich cavities between joint elements during their development.

Differential effects of RU486 reveal distinct mechanisms for glucocorticoid repression of prostaglandin E2 release

In A549 pulmonary cells, the dexamethasone- and budesonide-dependent repression of interleukin-1beta-induced prostaglandin E2 release was mimicked by the steroid antagonist, RU486. Conversely, whereas dexamethasone and budesonide were highly effective inhibitors of interleukin-1beta-induced cyclooxygenase (COX)/prostaglandin E synthase (PGES) activity and COX-2 expression, RU486 (<1 microm) was a poor inhibitor, but was able to efficiently antagonize the effects of dexamethasone and budesonide. In addition, both dexamethasone and RU486 repressed [3H]arachidonate release, which is consistent with an effect at the level of phospholipase A2 activity. By contrast, glucocorticoid response element-dependent transcription was unaffected by RU486 but induced by dexamethasone and budesonide, whilst dexamethasone- and budesonide-dependent repression of nuclear factor-kappaB-dependent transcription was maximally 30-40% and RU486 (<1 microm) was without significant effect. Thus, two pharmacologically distinct mechanisms of glucocorticoid-dependent repression of prostaglandin E2 release are revealed. First, glucocorticoid-dependent repression of arachidonic acid is mimicked by RU486 and, second, repression of COX/PGES is antagonized by RU486. Finally, whilst all compounds induced glucocorticoid receptor translocation, no role for glucocorticoid response element-dependent transcription is supported in these inhibitory processes and only a limited role for glucocorticoid-dependent inhibition of nuclear factor-kappaB in the repression of COX-2 is indicated.