Mitogen-activated Protein Kinase Signaling Modules Research Articles

Protein phosphatase StTOPP6 negatively regulates potato bacterial wilt resistance by modulating MAPK signaling.

Potato (Solanum tuberosum) is an important crop globally and is grown across many regions in China, where it ranks fourth in the list of staple foods. However, its production and quality are severely affected by bacterial wilt caused by Ralstonia solanacearum. In this study, we identified StTOPP6, which belongs to the type one protein phosphatase (TOPP) family, and found that transient knock down of StTOPP6 in potato increased resistance against R. solanacearum. RNA-seq analysis showed that knock down of StTOPP6 activated immune responses, and this defense activation partly depended on the mitogen-activated protein kinase (MAPK) signal pathway. StTOPP6 inhibited the expression of StMAPK3, while overexpression of StMAPK3 enhanced resistance to R. solanacearum, supporting the negative role of StTOPP6 in plant immunity. Consistent with the results of knock down of StTOPP6, overexpressing the phosphatase-dead mutation StTOPP6m also attenuated infection and up-regulated MAPK3, showing that StTOPP6 activity is required for disease. Furthermore, we found that StTOPP6 affected the StMAPK3-mediated downstream defense pathway, eventually suppressing the accumulation of reactive oxygen species (ROS). Consistent with these findings, plants with knock down of StTOPP6, overexpression of StTOPP6m, and overexpression of StMAPK3 all displayed ROS accumulation and enhanced resistance to R. solanacearum. Taken together, the findings of our study demonstrate that StTOPP6 negatively regulates resistance to bacterial wilt by affecting the MAPK3-mediated pathway.

WD repeat domain 62 (WDR62) promotes resistance of colorectal cancer to oxaliplatin through modulating mitogen-activated protein kinase (MAPK) signaling

ABSTRACT WD repeat domain 62 (WDR62) is involved in embryonic brain growth through regulation of glial and neural cell populations. WDR62 is also implicated in the carcinogenesis of various cancers. The role of WDR62 in progression and chemoresistance of colorectal cancer (CRC) was investigated. Firstly, oxaliplatin-resistant CRC cells (HCT116/R and HT29/R) were sequentially exposed to an increasing concentration of oxaliplatin. The results showed that WDR62 was elevated in CRC tissues, and oxaliplatin resistance conferred up-regulation of WDR62 in CRC cells. Knockdown of WDR62 reduced cell proliferation and promoted the apoptosis of oxaliplatin-resistant CRC cells. Moreover, silencing of WDR62 increased fluorescence intensity of γH2AX, and decreased protein expression of p-DNA-PK and Rad51 in the oxaliplatin-resistant CRC cells. The protein expression of p-ERK, p-JNK, and p-p38 in oxaliplatin-resistant CRC cells were down-regulated by knockdown of WDR62. In conclusion, silencing of WDR62 suppressed oxaliplatin resistance and DNA damage repair of CRC cells through inactivation of MAPK signaling.

Corydalis decumbens Can Exert Analgesic Effects in a Mouse Neuropathic Pain Model by Modulating MAPK Signaling.

Objectives This study is aimed at investigating the analgesic effect of the administration of Corydalis decumbens (CD) in a mouse model of postherpetic neuralgia (PHN) and at elucidating its mechanism of analgesic action. Methods Adult Kunming (KM) mice were randomly divided into control, CD, and vehicle-treated groups. Neuropathic pain was induced with a single intraperitoneal injection of resiniferatoxin (RTX). Thermal hyperalgesia was assessed with a hot/cold plate test, and mechanical allodynia was evaluated using von Frey filaments. The activation states of astrocytes, microglia, and the mitogen-activated protein kinase (MAPK) pathway in the spinal cord were determined by immunofluorescence staining and Western blot analysis of Iba-1, GFAP, phospho-p38, and phospho-Jun N-terminal kinase (JNK). Results RTX diminished thermal sensitivity and gradually increased sensitivity to tactile stimulation. The expression of Iba-1, GFAP, phospho-p38 MAPK, and phospho-JNK was upregulated in the RTX-induced postherpetic neuralgia mouse model. Systemic treatment with CD significantly ameliorated thermal sensitivity and mechanical hyperalgesia and was accompanied by a reduction in the expression of Iba-1 and GFAP and reduced phosphorylation of p38 and JNK. Conclusions This study suggests that CD is effective at ameliorating mechanical hyperalgesia in PHN mice and that its mechanism of action may involve modulation of MAPK phosphorylation and glial cell activation. Thus, CD may be a promising alternative therapy for PHN.

CTI-2 Inhibits Metastasis and Epithelial-Mesenchymal Transition of Breast Cancer Cells by Modulating MAPK Signaling Pathway.

Although some breast cancer patients die due to tumor metastasis rather than from the primary tumor, the molecular mechanism of metastasis remains unclear. Therefore, it is necessary to inhibit breast cancer metastasis during cancer treatment. In this case, after designing and synthesizing CTI-2, we found that CTI-2 treatment significantly reduced breast cancer cell metastasis in vivo and in vitro. Notably, with the treatment of CTI-2 in breast cancer cells, the expression level of E-cadherin increased, while the expression level of N-cadherin and vimentin decreased. In addition, after CTI-2 treatment, those outflow levels for p-ERK, p-p38, and p-JNK diminished, while no significant changes in the expression levels of ERK, JNK, or p38 were observed. Our conclusion suggested that CTI-2 inhibits the epithelial-mesenchymal transition (EMT) of breast carcinoma cells by inhibiting the activation of the mitogen-activated protein kinase (MAPK) signaling pathway, thereby inhibiting the metastasis of breast tumor cells. Therefore, we believe that CTI-2 is another candidate for breast tumor medication.

Neu5Ac Induces Human Dental Pulp Stem Cell Osteo-/Odontoblastic Differentiation by Enhancing MAPK/ERK Pathway Activation.

Dental pulp stem cells (DPSCs) must undergo odontoblastic differentiation in order to facilitate the process of dentin-pulp complex repair. Herein, we sought to explore the ability of Neu5Ac (one form of sialic acid) to influence DPSC osteo-/odontoblastic differentiation via modulating mitogen-activated protein kinase (MAPK) signaling. Methodology. DPSCs were isolated from human third permanent teeth and were grown in vitro. Fluorescent microscopy was used to detect the existence of sialic acid on the DPSC membrane. Following the treatment of different concentrations of Neu5Ac and removing sialic acid from the cell surface by neuraminidase, the osteo-/odontoblastic differentiation of these cells was evaluated via mineralization, alkaline phosphatase, and in vivo assays. In addition, the expression of genes related to osteo-/odontoblastic differentiation and MAPK signaling at different stages of this differentiation process was analyzed in the presence or absence of Neu5Ac. Results. The existence of sialic acid on the DPSC membrane was confirmed by fluorescent microscopy, and the ability of osteo-/odontoblastic differentiation was decreased after removing sialic acid by neuraminidase. Treatment of DPSCs with Neu5Ac (0.1 mM or 1 mM) significantly enhanced their mineralization ability and alkaline phosphatase activity. The expression levels of DMP1, DSPP, BSP, and RUNX2 were also increased. Treatment of nude mice with ManNAc (the prerequisite form of Neu5Ac) also enhanced DPSC mineralization activity in vivo. Furthermore, Neu5Ac treatment enhanced p-ERK expression in DPSCs, while ERK pathway inhibition disrupted the ability of Neu5Ac to enhance the osteo-/odontoblastic differentiation of these cells. Conclusions. Neu5Ac can promote DPSC osteo-/odontoblastic differentiation through a process associated with the modulation of the ERK signaling pathway activity.

Brucein D modulates MAPK signaling cascade to exert multi-faceted anti-neoplastic actions against breast cancer cells

Breast cancer is a prominent type of malignancy among women with a high rate of mortality. A number of previous studies have demonstrated the anticancer potential of brucein D (BD), a quassinoid extracted from Brucea javanica, against the cancers of the pancreas, bone, and liver. We investigated the impact of BD on apoptotic as well on mitogen-activated protein kinase (MAPK) signaling cascades in breast cancer cells. The effect of BD on p38 MAPK and JNK signaling pathways and its downstream functions was deciphered in both MDA-MB-231 and MCF-7 cell lines. We noted that BD decreased the viability of breast cancer cells without affecting the growth of healthy mammary epithelial cells (MCF-10A). Flow cytometric analysis revealed that BD can increase sub-G1 cells and enhanced annexin-V-PI stained cells. The apoptogenic impact of BD was further substantiated by cleavage of procaspase-3/8 and downregulation of antiapoptotic proteins (Bcl-xL, XIAP, and survivin). Furthermore, BD also downmodulated the migratory ability, and chemokine triggered invasion of breast cancer cells. Interestingly, the pharmacological inhibition of p38 MAPK and JNK kinases abrogated the observed anticancer actions of BD. Overall, the data indicated that BD can induce substantial apoptosis and interfere with cellular invasion by modulating MAPK signaling pathway in breast cancer cells.

Sevoflurane Inhibits Proliferation and Invasion of Human Ovarian Cancer Cells by Regulating JNK and p38 MAPK Signaling Pathway.

AimSevoflurane is a halogen inhaled anesthetic, and we aimed to probe the effect of sevoflurane on proliferation and invasion of human ovarian cancer (OC) and its mechanism.MethodsOC cell lines were divided into 4 groups including control, sevoflurane low concentration (1.7%), medium concentration (3.4%) and high concentration (5.1%) groups. Flow cytometry and MTT assay were, respectively, employed to detect the cell apoptosis and proliferation. Transwell assay was applied to measure the cell migration and invasion viability. The gene and protein expressions were assessed using qRT-PCR and Western blot. The expressions of MAPK signaling pathway-related proteins were evaluated by Western blot. The p38 and JNK inhibitors were, respectively, added into the high concentration group to analyze the relationship between sevoflurane and modulatingmitogen-activated protein kinase (MAPK) pathway in OC. Nude mice models were constructed to explore the effect of sevoflurane on OC tumor growth in vivo.ResultsSevoflurane inhibited OC proliferation in vitro and in vivo. It could also promote OC cell apoptosis in a dose-dependent manner. Sevoflurane suppressed the OC cell migration and invasion, and these effects were positively correlated with the dose of sevoflurane. Moreover, sevoflurane treatment inhibited the expressions of PCNA, Twist, cleaved-caspase-3/caspase-3, MMP-2 and MMP-9. In addition, sevoflurane repressed the phosphorylation of JNK and p38 MAPK. When the MAPK pathway was interdicted, the cell proliferation, apoptosis, migration and invasion activity were recovered after sevoflurane treatment.ConclusionSevoflurane affected cell biological activities in OC by regulating JNK and p38 MAPK signaling pathway.

Housefly (Musca domestica) larvae powder, preventing oxidative stress injury via regulation of UCP4 and CyclinD1 and modulation of JNK and P38 signaling in APP/PS1 mice.

Housefly (Musca domestica) Larvae powder (HL) is rich in antioxidants. As oxidative stress is considered as one of the main pathogenesis in Alzheimer's Disease (AD), this study was designed to explore the protective effects of HL as an antioxidant on APP/PS1 mice. 2-Month-old APP/PS1 mice were divided into a model control (MC) group, a Donepezil group and a HL group, and C57BL/6 mice were used as the normal control (NC) group. After 180 days of treatment, the memory ability was measured by Morris Water Maze (MWM). The presence of Aβ and the expression of Uncoupling Protein 4 (UCP4) and CyclinD1 were detected by immunohistochemistry. The expressions of Superoxide Dismutase 1 (SOD1), Catalase (CAT) and Mitogen-activated Protein Kinase (MAPK) signal pathways were measured by western blotting. Compared with untreated APP/PS1 mice, the memory abilities of the HL-treated mice were significantly improved. Furthermore, the HL treatment not only down-regulated the deposition of Aβ and the expression of CylinD1, but also increased both the mRNA and protein levels of SOD, CAT, and UCP4, and enhanced the phosphorylation of JNK and P38 MAPK activation. In conclusion, these results suggest that HL may have a protective effect against memory impairment and prevent oxidative stress-induced injury via the regulation of UCP4 and CyclinD1 and the modulation of JNK and P38 MAPK signaling in AD.

2-arachidonyl glycerol modulates astrocytic glutamine synthetase via p38 and ERK1/2 pathways

BackgroundThe glutamine synthetase (GS), an astrocyte-specific enzyme, is involved in lipopolysaccharide (LPS)-induced inflammation which activates the mitogen-activated protein kinase (MAPK) signaling. Endocannabinoid 2-arachidonyl glycerol (2-AG) has been described to serve as an endogenous mediator of analgesia and neuroprotection. However, whether 2-AG can directly influence astrocytic GS and MAPK expressions remains unknown.MethodsIn the present study, the effects of 2-AG on astrocytic GS expression, p38 and ERK1/2 expression, cell viability, and apoptosis following LPS exposure were investigated.ResultsThe results revealed that LPS exposure increased GS expression with p38 activation in the early phase and decreased GS expression with activation of ERK1/2, decrease of cell viability, and increase of apoptosis in the late phase. Inhibition of p38 reversed GS increase in the early phase while inhibition of ERK1/2 reversed GS decrease in the late phase induced by LPS exposure. 2-AG protected astrocytes from increase of apoptosis and decrease of cell viability induced by the late phase of LPS exposure. In the early phase of LPS exposure, 2-AG could suppress the increase of GS expression and activation of p38 signaling. In the late phase of LPS exposure, 2-AG could reverse the decrease of GS expression and activation of ERK1/2 induced by LPS.ConclusionThese findings suggest that 2-AG could maintain the GS expression in astrocytes to a relatively stable level through modulating MAPK signaling and protect astrocytes from LPS exposure.

Identification on mitogen-activated protein kinase signaling cascades by integrating protein interaction with transcriptional profiling analysis in cotton

Plant mitogen-activated protein kinase (MAPK) cascades play important roles in development and stress responses. In previous studies, we have systematically investigated the mitogen-activated protein kinase kinase (MKK) and MAPK gene families in cotton. However, the complete interactions between MAPK gene family members in MAPK signaling cascade is poorly characterized. Herein, we investigated the mitogen-activated protein kinase kinase kinase (MAPKKK) family members and identified a total of 89 MAPKKK genes in the Gossypium raimondii genome. We cloned 51 MAPKKKs in G. hirsutum and investigated the interactions between MKK and MAPKKK proteins through yeast-two hybrid assays. A total of 18 interactive protein pairs involved in 14 MAPKKKs and six MKKs were found. Among these, 13 interactive pairs had not been reported previously. Gene expression patterns revealed that 12 MAPKKKs were involved in diverse signaling pathways triggered by hormone treatments or abiotic stresses. By combining the MKK-MAPK and MKK-MAPKKK protein interactions with gene expression patterns, 38 potential MAPK signaling modules involved in the complicated cross-talks were identified, which provide a basis on elucidating biological function of the MAPK cascade in response to hormonal and/or stress responses. The systematic investigation in MAPK signaling cascades will lay a foundation for understanding the functional roles of different MAPK cascades in signal transduction pathways, and for the improvement of various defense responses in cotton.

Juniperonic Acid Incorporation into the Phospholipids of Murine Macrophage Cells Modulates Pro-Inflammatory Mediator Production.

Juniperonic acid (JPA; Δ5,11,14,17-20:4), originally identified in certain gymnosperm seeds, is a rare n-3 polyunsaturated fatty acid (PUFA) with lipid-modulating effects on rats and anti-proliferative effects on fibroblast cell proliferation. However, little is known how JPA exerted its immunosuppressive effect. The objective of this study was to investigate whether JPA inhibited the production of inflammatory mediators through the modulation of cellular phospholipid fatty acid compositions. Using standard lipid chemistry techniques in conjunction with argentated column chromatography, high-purity JPA (> 98%) was extracted, isolated, and purified from Biota kernels. When murine RAW264.7 macrophages were incubated with increasing concentrations of JPA, amounts of cellular phospholipid total PUFA, JPA, and Δ7-docosatetraenoic acid (Δ7-DTA; elongation product of JPA) increased in a dose-dependent manner; however, the proportions of total monounsaturated fatty acid (MUFA) and arachidonic acid (AA) decreased. JPA suppressed the production of nitric oxide (NO), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) and the expression of inducible nitric oxide synthase (iNOS) up to 21, 75, 30, and 44%, respectively. The induction of cyclooxygenase-2 (COX-2) over-expression by JPA could account for the doubling of the PGE2 level. Furthermore, JPA suppressed the expression of phosphorylated mitogen-activated protein kinases (MAPK). In a separate study using the mouse ear edema model, we demonstrated that JPA also significantly suppressed inflammation, as measured by ear thickness and biopsy weight. The anti-inflammatory properties of JPA could be due, in part, to the incorporation of JPA into cellular phospholipids with subsequent modulation of membrane-mediated MAPK signaling.

Abstract LB-A33: Mitogen activated protein kinase (MAPK) signaling in neprilysin-hypermethylated breast cancer

Abstract Background: Neprilysin (NEP), or membrane metalloendopeptidase (MME), is a cell-surface enzyme that negatively regulates endothelin receptor signaling and is implicated in breast cancer. Our lab recently reported that NEP hypermethylation is a powerful prognostic indicator in stage I and triple negative breast cancer. Reactivation of NEP in MDA-MB-231 cells abrogated both invasion and mitogen activated protein kinase (MAPK) signaling. In this study, we further investigated the downstream signaling implications of neprilysin methylation in breast cancer. Methods: Methylation beta values from the Illumina HumanMethylation 450k platform and RPPA protein values were downloaded from the BRCA TCGA database. Values were sorted into methylated and unmethylated using a dichotomizing algorithm. Pathway analysis was performed using the CorePathway Database (Max Plank Institute) and analyzed using over-representation analysis with pathway-based sets using all linked databases with minimum overlap of 2 genes and a probability of 0.01 or less. MTT proliferation assays (ThermoFisher) and in vitro Matrigel invasion assays were performed with 10 μM PD98059 (Sigma). We used an MME expression vector from OriGene (RC223013) to over-express neprilysin in MDA-MB-231 cells. Results: We initially hypothesized that MAPK signaling would be induced in NEP-methylated breast cancer samples. Analyzing the TCGA database for pMEK levels in NEP-methylated and NEP-unmethylated breast cancer samples revealed a non-significant trend of increased pMEK levels in NEP-methylated samples. To determine if other proteins and pathways might be induced in NEP-methylated breast cancer, we analyzed all RPPA probes with higher expression in NEP-methylated compared to NEP-unmethylated cancers. In breast cancer samples with at least 75% tumor cells (low stromal contribution) and NEP-methylation, both MAPK1 and MAPK14 were up-regulated, as well as several MAPK signaling-associated proteins and a number of other cancer-promoting proteins. To experimentally test whether NEP-methylated cells were sensitive to MAPK inhibition, we conducted proliferation assays with MDA-MB-231 cells (NEP hypermethylated/low expression) and MCF7 cells (NEP unmethylated/moderate expression) in the presence and absence of the MEK inhibitor PD98059. MDA-MB-231 proliferation was significantly more inhibited by MAPK inhibition than MCF7 cells. MDA-MB-231 cell invasion was modestly but significantly inhibited in the presence of PD98059. Transfecting neprilysin in MDA-MB-231 cells more potently inhibited invasion than PD98059, but treating NEP-transfected cell lines with PD98059 did not further decrease invasion. These results are consistent with neprilysin modulating MAPK signaling as well as additional cancer-promoting protein pathways. Conclusion: We conclude that breast cancers with hypermethylated neprilysin have increased expression of a number of cancer-promoting proteins, including multiple proteins associated with MAPK signaling. Our in vitro data supports our hypothesis that while neprilysin likely functions to negatively regulate breast cancer invasion in part through MAPK signaling, neprilysin may regulate additional pathways in breast cancer invasion. These pathways, including MAPK, may be useful therapeutic targets in NEP-methylated breast cancers. Citation Format: Caleb Reagor, Mehdi Chaib, Rebecca E. Conway. Mitogen activated protein kinase (MAPK) signaling in neprilysin-hypermethylated breast cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr LB-A33.

ERK1 Directly Interacts With JNK1 Leading to Regulation of JNK1/c-Jun Activity and Cell Transformation.

ERK1 and ERK2 share a great deal of homology and have been presumed to have similar functions. Available antibodies recognize both isoforms making the elucidation of functional differences challenging. Mitogen-activated protein (MAP) kinase networks are commonly depicted in the literature as linear and sequential phosphorylation cascades; however, the activation of these pathways is not mutually exclusive. Little doubt exists that MAP kinases engage in crosstalk, but the extent or the direct effect of these "conversations" is unclear. Here, we report the possible points of direct interaction as "crosstalk" points between ERK1 and JNK1 and a potential mechanism for ERK1 function in repressing Ras/JNK-mediated cell transformation. ERK1, but not ERK2, directly interacts with and antagonizes JNK1 phosphorylation and activity, resulting in suppression of neoplastic cell transformation mediated by the Ras/JNK/c-Jun signaling pathway. Interestingly, ERK1 phosphorylation was increased in normal tissues compared to liver cancer tissues. Furthermore, predominant JNK/c-Jun activation was observed in liver cancer tissues. These phenomena can provide evidence for the existence of a functional association between ERK and JNK signaling pathways during in vivo tumorigenesis. Overall, our findings provide new evidence supporting the paradigm of an ERK1/JNK1 antagonistic interaction as a novel mechanism of trans-regulation between different MAP kinase signaling modules. J. Cell. Biochem. 118: 2357-2370, 2017. © 2017 Wiley Periodicals, Inc.

The Role of MAPK and Dopaminergic Synapse Signaling Pathways in Antidepressant Effect of Electroacupuncture Pretreatment in Chronic Restraint Stress Rats.

Acupuncture has demonstrated the function in ameliorating depressive-like behaviors via modulating PKA/CREB signaling pathway. To further confirm the antidepressant mechanism of EA on the mitogen-activated protein kinase (MAPK) and dopaminergic synapse signaling pathways, 4 target proteins were detected based on our previous iTRAQ analysis. Rats were randomly divided into control group, model group, and electroacupuncture (EA) group. Except for the control group, all rats were subjected to 28 days of chronic restraint stress (CRS) protocols to induce depression. In the EA group, EA pretreatment at Baihui (GV20) and Yintang (GV29) was performed daily (1 mA, 2 Hz, discontinuous wave, 20 minutes) prior to restraint. The antidepressant-like effect of EA was measured by body weight and open-field test. The protein levels of DAT, Th, Mapt, and Prkc in the hippocampus were examined by using Western blot. The results showed EA could ameliorate the depression-like behaviors and regulate the expression levels of Prkc and Mapt in CRS rats. The effect of EA on DAT and Th expression was minimal. These findings implied that EA pretreatment could alleviate depression through modulating MAPK signaling pathway. The role of EA on dopaminergic synapse signaling pathways needs to be further explored.

Corosolic acid protects hepatocytes against ethanol-induced damage by modulating mitogen-activated protein kinases and activating autophagy

The reactive oxygen species(ROS)/mitogen-activated protein kinase (MAPK) destroyed autophagy and the reactive oxygen species/mitogen-activated protein kinase (MAPK) pathway are considered closely related to ethanol-induced hepatocellular injury. Previous work indicated that corosolic acid, the natural extracts of leaves of the banaba tree, Lagerstroemia speciosa L., could protect the liver against ethanol-induced damage, but the underlying mechanism is unclear. In the study we found that corosolic acid significantly inhibited ethanol-induced apoptosis, increased level of tumor necrosis factor-α(TNF-α) and reactive oxygen species accumulation in vitro. Corosolic acid inhibited ethanol-activated p38 and c-Jun N-terminal kinase MAPK signaling in BRL-3A and HepG2 cells as well as in experimental rats. Corosolic acid restored the ethanol-suppressed expression of autophagy-related genes, including beclin-1 and the ratio of microtubule-associated protein light chain 3II/I (LC3II/I) via AMP-activated protein kinase (AMPK) activation both in vitro and in vivo. In experimental rats, corosolic acid ameliorated the detrimental histopathological findings. Corosolic acid may protect the liver against ethanol-induced injury by modulation of MAPK signaling and autophagy activation. These findings suggested that corosolic acid might be a promising agent in treatment of alcoholic liver diseases.

Picrasma quassiodes (D. Don) Benn. attenuates lipopolysaccharide (LPS)-induced acute lung injury.

Picrasma quassiodes (D.Don) Benn.(PQ) is a medicinal herb belonging to the family Simaroubaceae and is used as a traditional herbal remedy for various diseases. In this study, we evaluated the effects of PQ on airway inflammation using a mouse model of lipopolysaccharide(LPS)-induced acute lung injury(ALI) and LPS-stimulated raw264.7 cells. ALI was induced in C57BL/6 mice by the intranasal administration of LPS, and PQ was administered orally 3days prior to exposure to LPS. Treatment with PQ significantly attenuated the infiltration of inflammatory cells in the bronchoalveolar lavage fluid(BALF). PQ also decreased the production of reactive oxygen species(ROS) and pro-inflammatory cytokines, such as tumor necrosis factor(TNF)-α and interleukin(IL)-6 in BALF. In addition, PQ inhibited airway inflammation by reducing the expression of inducible nitric oxide synthase(iNOS) and by increasing the expression of heme oxygenase-1(HO-1) in the lungs. Furthermore, we demonstrated that PQ blocked the activation of mitogen-activated protein kinase(MAPK) and nuclear factor-κB(NF-κB) in the lungs of mice with LPS-induced ALI. In the LPS-stimulated RAW264.7 cells, PQ inhibited the release of pro-inflammatory cytokines and increased the mRNA expression of monocyte chemoattractant protein-1(MCP-1). Treatment with PQ decreased the translocation of nuclear factor(NF)-κB to the nucleus, and increased the nuclear translocation of nuclear factor erythroid-2-related factor2(Nrf2) and the expression of HO-1. PQ also inhibited the activation of p38 in the LPS-stimulated RAW264.7 cells. Taken together, our findings demonstrate that PQ exerts anti-inflammatory effects against LPS-induced ALI, and that these effects are associated with the modulation of iNOS, HO-1, NF-κB and MAPK signaling. Therefore, we suggest that PQ has therapeutic potential for use in the treatment of ALI.

Astragalus saponins Inhibits Lipopolysaccharide-Induced Inflammation in Mouse Macrophages.

Excessive nitric oxide (NO) and pro-inflammatory cytokines are produced during the pathogenesis of inflammatory diseases and cancer. It has been demonstrated that anti-inflammation contributes Astragalus membranaceus saponins (AST)'s beneficial effects in combination of conventional anticancer drugs. However, the immunomodulating property of AST has not been well characterized. In this study, we found that AST suppressed lipopolysaccharide (LPS)-induced generation of NO without causing cytotoxicity in the mouse macrophage RAW264.7. The gene and protein overexpression of inducible NO synthase (iNOS) as well as the production of tumor necrosis factor-[Formula: see text], evoked by LPS, was consistently down-regulated by AST. AST also inhibited the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and suppressed nuclear factor (NF)-[Formula: see text]B activation and the associated I[Formula: see text]B[Formula: see text] degradation during LPS insult. Furthermore, AST induced growth inhibition in promyelocytic leukemic HL-60 cells and T-lymphocyte leukemic Jurkat cells, but exerted no cytotoxic effects in normal human peripheral blood mononuclear cells (PBMC). It is known that the chemotherapeutic drug 5-FU can suppress the immune system, which can be identified by a reduced white blood cell count and decreased hematocrit, while the combination of AST and 5-FU can reverse the above hematologic toxicities. To summarize, non-cytotoxic concentrations of AST suppress LPS-induced inflammatory responses via the modulation of p38 MAPK signaling and the inhibition of NO and cytokine release. Importantly, AST can alleviate the hematologic side effects of current chemotherapeutic agents. These findings can facilitate the establishment of AST in the treatment of inflammatory diseases and inflammation-mediated tumor development.

Mitogen-Dependent Regulation of DUSP1 Governs ERK and p38 Signaling During Early 3T3-L1 Adipocyte Differentiation

Knowledge concerning mechanisms that control proliferation and differentiation of preadipocytes is essential to our understanding of adipocyte hyperplasia and the development of obesity. Evidence has shown that temporal regulation of mitogen-activated protein kinase (MAPK) phosphorylation and dephosphorylation is critical for coupling extracellular stimuli to cellular growth and differentiation. Using differentiating 3T3-L1 preadipocytes as a model of adipocyte hyperplasia, we examined a role for dual-specificity phosphatase 1 (DUSP1) on the timely modulation of MAPK signaling during states of growth arrest, proliferation, and differentiation. Using real-time reverse transcription PCR (qRT-PCR), we report that DUSP1 is induced during early preadipocyte proliferation concomitant with ERK and p38 dephosphorylation. As deactivation of ERK and p38 is essential for the progression of adipocyte differentiation, we further showed that de novo mRNA synthesis was required for ERK and p38 dephosphorylation, suggesting a role for "inducible" phosphatases in regulating MAPK signaling. Pharmacological and genetic inhibition of DUSP1 markedly increased ERK and p38 phosphorylation during early adipocyte differentiation. Based on these findings, we postulated that loss of DUSP1 would block adipocyte hyperplasia. However, genetic loss of DUSP1 was not sufficient to prevent preadipocyte proliferation or differentiation, suggesting a role for other phosphatases in the regulation of adipogenesis. In support of this, qRT-PCR identified several MAPK-specific DUSPs induced during early (DUSP2, -4, -5, & -6), mid (DUSP4 & -16) and late (DUSP9) stages of adipocyte differentiation. Collectively, these data suggest an important role for DUSPs in regulating MAPK dephosphorylation, with an emphasis on DUSP1, during early adipogenesis.

Unraveling the intricate nexus of molecular mechanisms governing rice root development: OsMPK3/6 and auxin-cytokinin interplay.

The root system is an imperative component of a plant, involved in water and nutrient acquisition from the soil. Any subtle change in the root system may lead to drastic changes in plant productivity. Both auxin and cytokinin are implicated in regulating various root developmental aspects. One of the major signaling cascades facilitating various hormonal and developmental allocations is the Mitogen Activated Protein Kinase (MAPK) cascade. Innumerable efforts have been made to unravel the complex nexus involved in rice root development. In spite of a plethora of studies, a comprehensive study aiming to decipher the plausible cross-talk of MAPK signaling module with auxin and cytokinin signaling components in rice is missing. In the present study, extensive phenomics analysis of different stages of rice roots; transcript profiling by qRT-PCR of entire gene family of MAPK, MAPKK and PIN genes; as well as protein level and activity of potential MAPKs was investigated using western and immuno kinase assays both on auxin and cytokinin treatment. The above study led to the identification of various novel rice root specific phenotypic traits by using GiA roots software framework. High expression profile of OsMPK3/6, OsMKK4/5 and OsPIN 1b/9 and their marked transcript level modulation in response to both auxin and cytokinin was observed. Finally, the protein levels and activity assay further substantiated our present findings. Thus, OsMPK3/6-OsMKK4/5 module is elucidated as the putative, key player in auxin-cytokinin interaction augmenting their role by differentially regulating the expression patterns of OsPIN 1b/9 in root development in rice.

Arctigenin Protects against Lipopolysaccharide-Induced Pulmonary Oxidative Stress and Inflammation in a Mouse Model via Suppression of MAPK, HO-1, and iNOS Signaling.

Arctigenin, a bioactive component of Arctium lappa (Nubang), has anti-inflammatory activity. Here, we investigated the effects of arctigenin on lipopolysaccharide (LPS)-induced acute lung injury. Mice were divided into four groups: control, LPS, LPS + DMSO, and LPS + Arctigenin. Mice in the LPS + Arctigenin group were injected intraperitoneally with 50 mg/kg of arctigenin 1 h before an intratracheal administration of LPS (5 mg/kg). Lung tissues and bronchoalveolar lavage fluids (BALFs) were collected. Histological changes of the lung were analyzed by hematoxylin and eosin staining. Arctigenin decreased LPS-induced acute lung inflammation, infiltration of inflammatory cells into BALF, and production of pro-inflammatory cytokines. Moreover, arctigenin pretreatment reduced the malondialdehyde level and increased superoxide dismutase and catalase activities and glutathione peroxidase/glutathione disulfide ratio in the lung. Mechanically, arctigenin significantly reduced the production of nitric oxygen and inducible nitric oxygen synthase (iNOS) expression, enhanced the expression of heme oxygenase-1, and decreased the phosphorylation of mitogen-activated protein kinases (MAPKs). Arctigenin has anti-inflammatory and antioxidative effects on LPS-induced acute lung injury, which are associated with modulation of MAPK, HO-1, and iNOS signaling.