p38MAPK Signal Transduction Pathway Research Articles

TNF-α Regulates the Glucocorticoid Receptor Alpha Expression in Human Nasal Epithelial Cells Via p65-NF-κb and p38-MAPK Signaling Pathways.

Tumor necrosis factor (TNF)-α induces changes in the glucocorticoid receptor (GR) isoforms' expression in human nasal epithelial cells (HNECs) in chronic rhinosinusitis (CRS). However, the underlying mechanism of TNF-α induced GR isoforms' expression in HNECs remains unclear. Here, we explored changes in inflammatory cytokines and glucocorticoid receptor alpha isoform (GRα) expression in HNECs. To explore the expression of TNF-α in nasal polyps and nasal mucosa of CRS, fluorescence immunohistochemical analysis was employed. To investigate changes in inflammatory cytokines and GRα expression in HNECs, RT-PCR and western blotting were performed following the cells' incubation with TNF-α. Cells were pretreated with the nuclear factor-κB gene binding (NF-κB) inhibitor QNZ, the p38 inhibitor SB203580, and dexamethasone for one hour, then a TNF-α. Western blotting, RT-PCR, and immunofluorescence had been utilized for the cells' analysis and the ANOVA for the data analysis. The TNF-α fluorescence intensity was mainly distributed in nasal epithelial cells of nasal tissues. TNF-α prominently inhibited the expression of GRα mRNA from 6 to 24 h in HNECs. GRα protein was decreased from 12 to 24 h. Treatment with QNZ, SB203580, or dexamethasone inhibited the TNF-α and interleukin (IL)-6 mRNA expression and increased the GRα levels. TNF-α induced changes in the GR isoforms' expression in HNECs, and it was mediated through p65-NF-κB and p38-MAPK signal transduction pathways, which could be considered a promising neutrophilic CRS treatment.

IgG against the Membrane-Proximal Portion of the Desmoglein 3 Ectodomain Induces Loss of Keratinocyte Adhesion, a Hallmark in Pemphigus Vulgaris

Pemphigus vulgaris is a severe autoimmune blistering disease characterized by IgG autoantibodies (auto-abs) against the desmosomal adhesion molecules desmoglein (DSG) 3 and DSG1. Underlying mechanisms leading to blister formation upon binding of DSG-specific IgG auto-abs are not fully understood. Numerous studies showed the pathogenicity of IgG auto-ab binding to the aminoterminal region 1 (EC1) of the DSG3 ectodomain. However, auto-abs in pemphigus vulgaris are polyclonal, including IgG against both aminoterminal- and membrane-proximal epitopes of the DSG3 ectodomain. In this study, the pathogenicity of a previously uncharacterized murine monoclonal IgG antibody, 2G4, directed against the membrane-proximal region (EC5) of the DSG3 ectodomain was characterized and tested in various specificity and functionality assays. The results clearly show that 2G4 is capable of inhibiting intercellular keratinocyte adhesion and of inducing cellular DSG3 redistribution by activation of the p38MAPK signal transduction pathway. In this study, we provide evidence that an IgG auto-abs directed against the membrane-proximal region EC5 of DSG3 induces acantholysis, the hallmark in pemphigus vulgaris. These findings challenge the current concept that IgG auto-abs targeting the NH2-terminal portion of the DSG3 ectodomain are pathogenic only. Our study provides further aspects for a deeper understanding of desmosomal keratinocyte adhesion and improves our insight into the complex auto-ab‒induced blister formation in pemphigus vulgaris.

Basil Polysaccharide Reverses Development of Experimental Model of Sepsis-Induced Secondary Staphylococcus aureus Pneumonia.

Background Basil polysaccharide (BPS) represents a main active ingredient extracted from basil (Ocimum basilicum L.), which can regulate secondary bacterial pneumonia development in the process of sepsis-mediated immunosuppression. Methods In this study, a dual model of sepsis-induced secondary pneumonia with cecal ligation and puncture and intratracheal instillation of Staphylococcus aureus or Pseudomonas aeruginosa was constructed. Results The results indicated that BPS-treated mice undergoing CLP showed resistance to secondary S. aureus pneumonia. Compared with the IgG-treated group, BPS-treated mice exhibited better survival rate along with a higher bacterial clearance rate. Additionally, BPS treatment attenuated cell apoptosis, enhanced lymphocyte and macrophage recruitment to the lung, promoted pulmonary cytokine production, and significantly enhanced CC receptor ligand 4 (CCL4). Notably, recombinant CCL4 protein could enhance the protective effect on S. aureus-induced secondary pulmonary infection of septic mice, which indicated that BPS-induced CCL4 partially mediated resistance to secondary bacterial pneumonia. In addition, BPS priming markedly promoted the phagocytosis of alveolar macrophages while killing S. aureus in vitro, which was related to the enhanced p38MAPK signal transduction pathway activation. Moreover, BPS also played a protective role in sepsis-induced secondary S. aureus pneumonia by inducing Treg cell differentiation. Conclusions Collectively, these results shed novel lights on the BPS treatment mechanism in sepsis-induced secondary S. aureus pneumonia in mice.

Abstract 4303: TanshinoneIIA, an isolated compound from Salvia miltiorrhiza, inhibits cell growth in colorectal cancer via activation of p38MAPK signaling pathway

Abstract Tanshinone IIA (TSIIA) is an active ingredient extracted from the root of Danshen (Salvia miltiorrhiza Bunge), a Chinese traditional herb. Recent studies have indicated that TSIIA is a natural anti-tumor agent, however, the underlying mechanisms remain largely unknown. We studied the anti-tumor efficacy of TSIIA on human colon cancer cell lines in vitro and in vivo, and have further demonstrated that the molecular anti-cancer property of TanIIA is dependent on its inhibition of proliferation and induction of apoptotic cell death via p38MAPK signaling pathway. The results indicated that TanIIA were markedly more effective than control group in preventing tumor growth and increasing survival time. This phenomenon was accompanied by a decrease in cell growth in a concentration- and time-dependent manner. Hoechst 33258 stainning showed an increased number of apoptotic bodies in the cells after treatment with TanIIA. Flow cytometry analysis showed TanIIA could cause an obvious colon cacer cell apoptosis and arrest cells in the G0/G1 phase. After p38MAPK signaling pathway was blocked, the cell apoptotic rates and cell ratio of G0/G1 phase were decreased significantly. In addition, TanIIA increased p38MAPK phosphorylation, and up-regulated the protein expression of ATF-2, The ATF-2 expression was found to be significantly decreased in cells treated with p38MAPK-specific inhibitor. From our results, it is speculated that TanIIA may induce human colon cancer cells apoptosis and arrest cells in the G0/G1 phase involve up-regulation the expression of the ATF-2 mRNA via p38MAPK signal transduction pathway. Note: This abstract was not presented at the meeting. Citation Format: Yan Wang, Lihong Zhou, Qing Ji, Hua Sui, Xueqing Hu, Gang Cai, Qi Li. TanshinoneIIA, an isolated compound from Salvia miltiorrhiza, inhibits cell growth in colorectal cancer via activation of p38MAPK signaling pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4303.

CID-6033590 inhibits p38MAPK pathway and induces S-phase cell cycle arrest and apoptosis in DU145 and PC-3 cells

Metastatic prostate cancer, with no effective treatment, is among the leading causes of cancer-associated deaths in men. Overexpression of p38αMAPK has been observed in neuroendocrine prostate cancer patients and in both DU145 and PC-3 cell lines and represents a good drug target. Sulfonamide derivatives have shown biological activities against many human diseases, including cancer. CID-6033590, a sulfonylhydrazide compound, screened from PubChem database by molecular docking with p38αMAPK, was evaluated for anti-cancerous activities. CID-6033590 induced toxicity in both DU145 and PC-3 cells in a concentration and time-dependent manner with an IC50 value of 60 μM and 66 μM, respectively. Sub-cytotoxic concentrations of the compound significantly induced S-phase cell cycle arrest, inhibited cyclinA/CDK2 complex and blocked cell proliferation. Further, CID-6033590 downregulated phosphorylation of p38MAPK (P-p38) as well as its downstream targets, Activating transcription factor 2 (ATF-2) and Heat shock protein 27 (Hsp27). The compound increased ROS and decreased mitochondrial membrane potential (Δψm), downregulated Bcl-2 and survivin and cleaved poly ADP ribose polymerase (PARP) and caspase-3, indicating the induction of apoptosis. The evaluaion of the compound on noncancerous, human prostatic epithelial cell line RWPE-1, and healthy murine tissues yielded no significant toxicity. Taken together, we suggest CID-6033590 as a potential candidate for prostate cancer therapy.

Effects of p38 mitogen-activated protein kinase in rats with oleic acid-induced acute lung injury

To study the effects of p38 mitogen-activated protein kinase (p38MAPK) signal transduction pathway inhibitor SB203580 on the inflammatory reaction and lung water clearance, and to explore the role of p38MAPK in acute lung injury, to provide new way for p38MAPK inhibitor -SB203580 intervene fat embolism syndrome induced lung injury. Twenty-four adult male SD rats were randomly assigned to normal control group (OA group) (n=8), oleic acid-induced lung injury group (OA group, n=8)and SB203580 pretreatment group (n=8). OA-group was administered oleic acid (0.20 ml/kg) via right jugular vein; In SB203580-group, SB203580(5 mg/kg) was injected via jugular vein, followed 30 min before by OA infusion; At the 4 hours animals were sacrificed. Arterial blood gas, the wet/dry weight(W/D)of the right lower lung were examined, lung index(LI), pulmonary permeability index(PPI) and levels of tumor necrosis factor α(TNF-α) in bronchoalveolar lavage fluid(BALF) were examined. The expressions of p38MAPK and phospho-p38MAPK (p-p38MAPK) were determined by Western blot and immunohistochemical method. Pathological changes of the lung tissue were examined with light microscrope. Compared to control group, arterial oxygen partial pressure (PaO2) and PaO2/FiO2 were decreased in the animals of OA-group, while right lower lung wet/dry ratio, lung index, PPI, levels of TNF-α in BALF and the protein expression of p-p38MAPK were increased significantly (P<0.01). The pathological changes were observed significantly in injured lung tissue. Compared to OA-group, those indexes were improved in SB203580 pretreated group. p38MAPK signal transaction path mediated inflammatory response process and played an important role in acute lung injury. SB203580 could inhibit the expression of inflammatory cytokines, reduce lung edema, protect lung tissue of rats from OA-induced lung injury obviously. Therefore, inhibition of p38MAPK activity provides a new way for the clinical treatment of fat embolism syndrome induced lung injury.

Sika pilose antler type I collagen promotes BMSC differentiation via the ERK1/2 and p38-MAPK signal pathways

Context: Sika pilose antler type I collagen (SPC-I) have been reported to promote bone marrow mesenchymal stem cell (BMSC) proliferation and differentiation. However, the underlying mechanism is still unclear.Objective: This study investigates the molecular mechanisms of SPC-I on the BMSC proliferation and differentiation of osteoblast (OB) in vitro.Material and methods: The primary rat BMSC was cultured and exposed to SPC-I at different concentrations (2.5, 5.0 and 10.0 mg/mL) for 20 days. The effect of SPC-I on the differentiation of BMSCs was evaluated through detecting the activity of alkaline phosphatase (ALP), ALP staining, collagen I (Col-I) content, and calcified nodules. The markers of osteoblastic differentiation were evaluated using RT-PCR and Western-blot analysis.Results: SPC-I treatment (2.5 mg/mL) significantly increased the proliferation of BMSCs (p < 0.01), whereas, SPC-I (5.0 and 10.0 mg/mL) significantly inhibited the proliferation of BMSCs (p < 0.01). SPC-I (2.5 mg/mL) significantly increased ALP activity and Col-I content (p < 0.01), and increased positive cells in ALP staining and the formation of calcified nodules. Additionally, the gene expression of ALP, Col-I, Osteocalcin (OC), Runx2, Osterix (Osx), ERK1/2, BMP2 and p38-MAPK, along with the protein expression of ERK1/2, p-ERK1/2, p-p38 MAPK were markedly increased in the SPC-I (5.0 mg/mL) treatment group (p < 0.01) compared to the control group.Discussion and conclusions: SPC-I can induce BMSC differentiation into OBs and enhance the function of osteogenesis through ERK1/2 and p38-MAPK signal transduction pathways and regulating the gene expression of osteogenesis-specific transcription factors.

Role of human amnion-derived mesenchymal stem cells in promoting osteogenic differentiation by influencing p38 MAPK signaling in lipopolysaccharide -induced human bone marrow mesenchymal stem cells

Periodontitis is a chronic inflammatory disease induced by bacterial pathogens, which not only affect connective tissue attachments but also cause alveolar bone loss. In this study, we investigated the anti-inflammatory effects of Human amnion-derived mesenchymal stem cells (HAMSCs) on human bone marrow mesenchymal stem cells (HBMSCs) under lipopolysaccharide (LPS)-induced inflammatory conditions. Proliferation levels were measured by flow cytometry and immunofluorescence staining of 5-ethynyl-2′-deoxyuridine (EdU). Osteoblastic differentiation and mineralization were investigated using chromogenic alkaline phosphatase activity (ALP) activity substrate assays, Alizarin red S staining, and RT-PCR analysis of HBMSCs osteogenic marker expression. Oxidative stress induced by LPS was investigated by assaying reactive oxygen species (ROS) level and superoxide dismutase (SOD) activity. Here, we demonstrated that HAMSCs increased the proliferation, osteoblastic differentiation, and SOD activity of LPS-induced HBMSCs, and down-regulated the ROS level. Moreover, our results suggested that the activation of p38 MAPK signal transduction pathway is essential for reversing the LPS-induced bone-destructive processes. SB203580, a selective inhibitor of p38 MAPK signaling, significantly suppressed the anti-inflammatory effects in HAMSCs. In conclusion, HAMSCs show a strong potential in treating inflammation-induced bone loss by influencing p38 MAPK signaling.

Osmotic expression of aldose reductase in retinal pigment epithelial cells: involvement of NFAT5.

Diabetic retinopathy is associated with osmotic stress resulting from hyperglycemia and intracellular sorbitol accumulation. Systemic hypertension is a risk factor of diabetic retinopathy. High intake of dietary salt increases extracellular osmolarity resulting in systemic hypertension. We determined the effects of extracellular hyperosmolarity, chemical hypoxia, and oxidative stress on the gene expression of enzymes involved in sorbitol production and conversion in cultured human retinal pigment epithelial (RPE) cells. Alterations in the expression of aldose reductase (AR) and sorbitol dehydrogenase (SDH) genes were examined with real-time RT-PCR. Protein levels were determined with Western blot analysis. Nuclear factor of activated T cell 5 (NFAT5) was knocked down with siRNA. AR gene expression in RPE cells was increased by high (25mM) extracellular glucose, CoCl2 (150μM)-induced chemical hypoxia, H2O2 (20μM)-induced oxidative stress, and extracellular hyperosmolarity induced by addition of NaCl or sucrose. Extracellular hyperosmolarity (but not hypoxia) also increased AR protein level. SDH gene expression was increased by hypoxia and oxidative stress, but not extracellular hyperosmolarity. Hyperosmolarity and hypoxia did not alter the SDH protein level. The hyperosmotic AR gene expression was dependent on activation of metalloproteinases, autocrine/paracrine TGF-β signaling, activation of p38 MAPK, ERK1/2, and PI3K signal transduction pathways, and the transcriptional activity of NFAT5. Knockdown of NAFT5 or inhibition of AR decreased the cell viability under hyperosmotic (but not hypoxic) conditions and aggravated the hyperosmotic inhibition of cell proliferation. The data suggest that sorbitol accumulation in RPE cells occurs under hyperosmotic, but not hypoxic and oxidative stress conditions. NFAT5- and AR-mediated sorbitol accumulation may protect RPE cells under conditions of osmotic stress.

The role of formyl peptide receptor 1 (FPR1) in neuroblastoma tumorigenesis.

BackgroundFormyl peptide receptor 1 (FPR1) is a G protein-coupled receptor mainly expressed by the cells of myeloid origin, where it mediates the innate immune response to bacterial formylated peptides. High expression of FPR1 has been detected in various cancers but the function of FPR1 in tumorigenesis is poorly understood.MethodsExpression of FPR1 in neuroblastoma cell lines and primary tumors was studied using RT-PCR, western blotting, immunofluorescence and immunohistochemistry. Calcium mobilization assays and western blots with phospho-specific antibodies were used to assess the functional activity of FPR1 in neuroblastoma. The tumorigenic capacity of FPR1 was assessed by xenografting of neuroblastoma cells expressing inducible FPR1 shRNA, FPR1 cDNA or control shRNA in nude mice.ResultsFPR1 is expressed in neuroblastoma primary tumors and cell lines. High expression of FPR1 corresponds with high-risk disease and poor patient survival. Stimulation of FPR1 in neuroblastoma cells using fMLP, a selective FPR1 agonist, induced intracellular calcium mobilization and activation of MAPK/Erk, PI3K/Akt and P38-MAPK signal transduction pathways that were inhibited by using Cyclosporin H, a selective receptor antagonist for FPR1. shRNA knock-down of FPR1 in neuroblastoma cells conferred a delayed xenograft tumor development in nude mice, whereas an ectopic overexpression of FPR1 promoted augmented tumorigenesis in nude mice.ConclusionOur data demonstrate that FPR1 is involved in neuroblastoma development and could represent a therapy option for the treatment of neuroblastoma.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-016-2545-1) contains supplementary material, which is available to authorized users.

Gastrointestinal Congestion Dilates the Hepatic Artery Through the P38 MAPK Signal Transduction Pathway During Liver Transplantation.

During the neohepatic stage of liver transplantation, hemodynamics change markedly. The current study aimed to investigate whether gastrointestinal congestion caused by inferior vena cava and hepatic portal vein clamping can dilate the hepatic artery and to determine the associated mechanisms. Ring segments of the hepatic artery were treated with the plasma from gastrointestinal congestion or the superior vena cava. The fractions in gastrointestinal congestion and the superior vena cava plasma were tested, and the effect of these fractions on the tone of the hepatic artery ring was examined. Different signal transduction blockers and different inhibitors were then used to determine the exact signal transduction pathway involved. In addition, endothelial cell structure was observed by transmission electron microscopy after treatment with the gastrointestinal congestion plasma or the superior vena cava plasma. Gastrointestinal congestion plasma contained more inflammatory cytokines than superior vena cava plasma, and these cytokines could cause hepatic artery ring dilatation. A P38 mitogen-activated protein kinase (P38 MAPK) signal transduction pathway blocker and nitric oxide (NO), prostaglandin (PGI2), nuclear factor-κB (NF-κB), and adenosine triphosphate (ATP)-sensitive K (KATP) channel inhibitors were able to significantly reverse the ring tension caused by gastrointestinal congestion plasma. The normal endothelium was also injured by treatment with gastrointestinal congestion plasma. The inflammatory cytokines in gastrointestinal congestion can cause hepatic artery ring dilatation through the P38 MAPK signal transduction pathway, and this phenomenon is also associated with NO, PGI2, NF-κB, and the KATP channel. These inflammatory cytokines can injure endothelial cells in the hepatic artery.

Genomic and proteomic analysis of the inhibition of synthesis and secretion of aldosterone hormone induced by quinocetone in NCI-H295R cells.

Quinoxaline 1,4-dioxides (QdNOs) are widely used as a kind of antibacterial growth promoter in animal husbandry. The adrenal cortex was found to be one of the main toxic targets of QdNOs, accompanied by a decreased aldosterone level. However, the way in which QdNOs decrease production of the hormone aldosterone is far from clear. To illustrate the mechanism by which QdNOs damage the adrenal cortex and decrease aldosterone hormone levels, the QdNOs were screened to choose the drug with most toxic effects on aldosterone production, and then to reveal the mechanism between the gene and protein profiles in human adrenocortical cells (NCI-H295R cells). The results found that quinocetone (QCT) showed the highest adrenal toxic effect among QdNOs. After exposing H295R cells to 10 and 20μM QCT for 24h, compared with blank cells, the gene and protein expression profiles obtained were analyzed by microarray and MALDI TOF/TOF mass spectrometry, respectively. The results of microarray analysis suggested that ABCG1 and SREBF1, which were involved in the cholesterol biosynthetic and metabolic processes, and CYP17A1, NR4A2 and G6PD, which were related to aldosterone biosynthesis, were important molecular targets. It has been speculated that PKC and ERK pathways might be involved in the reduction of aldosterone production caused by QCT, through enhanced mRNA expression of CYP17A1. Additionally, JNK and p38MAPK signal transduction pathways might participate in apoptosis induced by QCT. Twenty-nine and 32 protein spots were successfully identified when cells were treated with 10 and 20μM QCT, respectively. These identified proteins mainly included material synthesis and energy metabolism-related proteins, transcription/translation processing-related proteins, signal transduction proteins, cytoskeletal proteins, molecular chaperones, proteins related to response to stress, and transport proteins. Further investigations suggested that oxidative stress caused by QCT was exacerbated through disruption of the Keap1/Nrf2/ARE anti-oxidative stress pathway. Taken together, the data demonstrated for the first time that the Keap1/Nrf2/ARE pathway plays a crucial role in adrenal toxicity, and that CYP17A1 was the key switch to reduce the aldosterone production induced by QCT. Furthermore, large numbers of genes and proteins and entry points for research in the inhibition of aldosterone synthesis induced by QCT were offered, which will provide new insight into the adrenal toxicity of QdNOs and help to provide a theoretical foundation for the formulation of safety controls for products obtained from animals and to design new QdNOs with less harmful effects.

Accessible Method for the Development of Novel Sterol Analogues with Dipeptide-like Side Chains That Act as Neuroinflammation Inhibitors.

A number of novel sterol derivatives with dipeptide-like side chains were synthesized using an Ugi four-component condensation method and assayed to test their anti-inflammatory effects in activated microglial cells. Compound 18b ((3S,10R,13S)-N-((R)-1-(tert-butylamino)-1-oxo-3-phenylpropan-2-yl)-3-hydroxy-N,10,13-trimethyl-2,3,4,7,8,9,10,11,12,13,14,15-dodecahydro-1H-cyclopenta[a]phenanthrene-17-carboxamide) was identified as the most potent anti-inflammatory agent in the series of compounds analyzed. Compound 18b markedly inhibited the expression of proinflammatory factors, including inducible nitric oxide synthase, interleukin (IL)-6, IL-1β, tumor necrosis factor-α, and cyclooxygenase-2 in lipopolysaccharide-stimulated microglial cells. Further studies showed that compound 18b significantly suppressed the transcriptional activity of AP-1 and NF-κB in activated microglial cells, which was likely mediated by the inhibition of the p38 MAPK and JNK signal transduction pathways. In addition, compound 18b displayed neuroprotective effects in a microglial-conditioned medium/neuron coculture and an experimental focal ischemic mouse model.

Intratracheal administration of mitochondrial DNA directly provokes lung inflammation through the TLR9–p38 MAPK pathway

An increasing number of studies have focused on the phenomenon that mitochondrial DNA (mtDNA) activates innate immunity responses. However, the specific role of mtDNA in inflammatory lung disease remains elusive. This study was designed to examine the proinflammatory effects of mtDNA in lungs and to investigate the putative mechanisms. C57BL/6 mice were challenged intratracheally with mtDNA with or without pretreatment with chloroquine. Changes in pulmonary histopathology, cytokine concentrations, and phosphorylation levels of p38 MAPK were assayed at four time points. In in vitro experiments, THP-1 macrophages were pretreated or not pretreated with chloroquine, TLR9 siRNA, p38 MAPK siRNA, or SB203580 and then incubated with mtDNA. The levels of cytokines and p-p38 MAPK were detected by ELISA and Western blot, respectively. The intratracheal administration of mtDNA induced infiltration of inflammatory cells, production of proinflammatory cytokines (including IL-1β, IL-6, and TNF-α), and activation of p38 MAPK. The chloroquine pretreatment resulted in an abatement of mtDNA-induced local lung inflammation. In vitro experiments showed that the exposure of THP-1 macrophages to mtDNA also led to a significant upregulation of IL-1β, IL-6, and TNF-α and the activation of p38 MAPK. And these responses were inhibited either by chloroquine and TLR9 siRNA or by SB203580 and p38 MAPK siRNA pretreatment. The intratracheal administration of mtDNA induced a local inflammatory response in the mouse lung that depended on the interactions of mtDNA with TLR9 and may be correlated with infiltrating macrophages that could be activated by mtDNA exposure via the TLR9–p38 MAPK signal transduction pathway.

Interleukin-1β regulates the expression of glucocorticoid receptor isoforms in nasal polyps in vitro via p38 MAPK and JNK signal transduction pathways.

BackgroundTo explore the upstream signal transduction mechanisms responsible for the imbalanced expression of glucocorticoid receptor (GR) isoforms in chronic rhinosinusitis (CRS) mucosa.MethodsAn in vitro model of Glucocorticoid resistance was established by inducing nasal polyp tissue with IL-1β. Changes in the protein and mRNA expression of GRα, GRβ and the key enzymes in the p38 MAPK and JNK signal pathways were measured, respectively, before and after being induced with different doses of IL-1β and specific inhibitors of p38 MAPK, JNK, ERK, PI3K and PKC. The Glucocorticoid sensitivity was measured using in vitro Glucocorticoid binding assay. Analysis of variance (ANOVA) was used to analyze the data.ResultsThe mRNA and protein expression levels of GRα, GRβ and key enzymes of the p38 MAPK and JNK pathways increased both in time- and concentration-dependent manners in IL-1β-induced nasal polyp tissue. The expression of GRβ increased more significantly than that of GRα, and the GRα/GRβ ratio decreased in time- and concentration-dependent manners. Statistically significant differences were found in the GRα/GRβ ratio and the mRNA expression of phospho-p38 MAPK and phospho-JNK between the IL-1β-induced groups and the control groups (P < 0.05). Either a specific inhibitor of the p38 MAPK pathway or a specific inhibitor of the JNK pathway increased the GRα/GRβ ratio and the Glucocorticoid affinity. None of the specific inhibitors of ERK, PI3K or PKC had any influence on the expression of GR isoforms.ConclusionOur results demonstrated that the imbalanced expression of GR isoforms in nasal polyp tissue induced by IL-1β in vitro is mediated through the p38 MAPK and JNK signal pathways.

Effects of sinomenine on neuronal apoptosis in spinal dorsal horns in a rat model of neuropathic pain

Objective To evaluate the effects of sinomenine on neuronal apoptosis in the spinal dorsal horns in a rat model of neuropathic pain (NP).Methods One hundred and eight male Wistar rats,weighing 180-220 g,were randomly divided into 3 groups with 36 animals in each group:sham operation group (group S),NP group and sinomenine group (group SIN).The animals were anesthetized with intraperitoneal chloral hydrate.In groups NP and SIN,NP was induced by chronic constrictive injury.The sciatic nerve was exposed and four ligatures were placed on the right sciatic nerve at 1 mm intervals with 4-0 chromic catgut.In group S,the right sciatic nerves were exposed,but not ligated.In group SIN,sinomenine 40 mg/kg was injected intraperitoneally once a day starting from the end of operation until one day before the rats were sacrificed.In groups NP and S,the rats received the equal volume of normal saline instead of sinomenine.Twelve animals in each group were randomly chosen at 1 day before operation (T0) and 3,7 and 14 days after operation (T1-33) to measure mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL).The rats in each group were sacrificed at T1-3 after measurement of pain threshold and the lumbar segments (L4-6) of the spinal cord were removed for determination of caspase-3 mRNA and p38MAPK mRNA expression (by real-time fluorescent quantitative PCR) and cell apoptosis (by TUNEL) in the spinal dorsal horn.Apoptosis rate (AR =the number of apoptotic cells/the total number of cells examined) was calculated.Results Compared with group S,MWT and TWL were significantly decreased,the expression of caspase-3 mRNA and p38MAPK mRNA was up-regulated,and AR was increased at T1-3 in NP and SIN groups (P ＜ 0.05).Compared with group NP,MWT and TWL were significantly increased,the expression of caspase-3 mRNA and p38MAPK mRNA was down-regulated,and AR was decreased at T1-3 in group SIN (P ＜ 0.05).MWT and TWL were significantly lower,and the expression of caspase-3 mRNA and p38MAPK mRNA and AR were higher at T2,3 than at T1 in groups NP and SIN (P ＜ 0.05).Conclusion Sinomenine can attenuate NP through inhibiting the expression of p38MAPK signal transduction pathway and reducing neuronal apoptosis in the spinal dorsal horn of rats. Key words: Sinomenine; Neuralgia; Apoptosis; Spinal cord

Effects of lycopene on number and function of human peripheral blood endothelial progenitor cells cultivated with high glucose.

BACKGROUND/OBJECTIVESThe objectives of this study were to investigate the effects of lycopene on the migration, adhesion, tube formation capacity, and p38 mitogen-activated protein kinase (p38 MAPK) activity of endothelial progenitor cells (EPCs) cultivated with high glucose (HG) and as well as explore the mechanism behind the protective effects of lycopene on peripheral blood EPCs.MATERIALS/METHODSMononuclear cells were isolated from human peripheral blood by Ficoll density gradient centrifugation. EPCs were identified after induction of cellular differentiation. Third generation EPCs were incubated with HG (33 mmol/L) or 10, 30, and 50 µg/mL of lycopene plus HG. MTT assay and flow cytometry were performed to assess proliferation and apoptosis of EPCs. EPC migration was assessed by MTT assay with a modified boyden chamber. Adhesion assay was performed by replating EPCs on fibronectin-coated dishes, after which adherent cells were counted. In vitro vasculogenesis activity was assayed by Madrigal network formation assay. Western blotting was performed to analyze protein expression of both phosphorylated and non-phosphorylated p38 MAPK.RESULTSThe proliferation, migration, adhesion, and in vitro vasculogenesis capacity of EPCs treated with 10, 30, and 50 µg/mL of lycopene plus HG were all significantly higher comapred to the HG group (P < 0.05). Rates of apoptosis were also significantly lower than that of the HG group. Moreover, lycopene blocked phosphorylation of p38 MAPK in EPCs (P < 0.05). To confirm the causal relationship between MAPK inhibition and the protective effects of lycopene against HG-induced cellular injury, we treated cells with SB203580, a phosphorylation inhibitor. The inhibitor significantly inhibited HG-induced EPC injury.CONCLUSIONSLycopene promotes proliferation, migration, adhesion, and in vitro vasculogenesis capacity as well as reduces apoptosis of EPCs. Further, the underlying molecular mechanism of the protective effects of lycopene against HG-induced EPC injury may involve the p38 MAPK signal transduction pathway. Specifically, lycopene was shown to inhibit HG-induced EPC injury by inhibiting p38 MAPKs.

PRAK interacts with DJ-1 and prevents oxidative stress-induced cell death.

As a core member of p38 MAPK signal transduction pathway, p38 regulated/activated kinase (PRAK) is activated by cellular stresses. However, the function of PRAK and its downstream interacting partner remain undefined. Using a yeast two-hybrid system, we identified DJ-1 as a potential PRAK interacting protein. We further verified that DJ-1 bound to PRAK in vitro and in vivo and colocalized with PRAK in the nuclei of NIH3T3 cells. Furthermore, following H2O2 stimulation the majority of endogenous DJ-1 in PRAK+/+ cells still remained in the nucleus, whereas most DJ-1 in PRAK−/− cells translocated from the nucleus into the cytoplasm, indicating that PRAK is essential for DJ-1 to localize in the nucleus. In addition, PRAK-associated phosphorylation of DJ-1 was observed in vitro and in vivo of H2O2-challenged PRAK+/+ cells. Cytoplasmic translocation of DJ-1 in H2O2-treated PRAK−/− cells lost its ability to sequester Daxx, a death protein, in the nucleus, and as a result, Daxx gained access to the cytoplasm and triggered cell death. These data highlight that DJ-1 is the downstream interacting target for PRAK, and in response to oxidative stress PRAK may exert a cytoprotective effect by facilitating DJ-1 to sequester Daxx in the nucleus, thus preventing cell death.

Interaction mechanism and influence between fatty acid oxidation and p38MAPK signal transduction pathway in trophoblast cells incubated with fatty acids

To explore the interaction mechanism and influence between fatty acids oxidation and p38MAPK signal transduction pathway in trophoblast cells stimulated by fatty acids of different chain lengths. Serum-free trophoblast cells cultured in vitro were divided into 5 groups, i.e. incubation with DMEM/F12 medium without FFA (F-FFA), short-chain fatty acids (SC-FFA), medium-chain fatty acids (MC-FFA), long-chain fatty acids (LC-FFA) and very long-chain fatty acids (VLC-FFA). Then cells in each group were stimulated by DMEM/F12 medium, NADPH oxidase inhibitor (Apocynin) and p38MAPK inhibitor (SB203580) and were subdivided into FFA plus-DMEM group, plus-NADPH-I and plus-p38MAPK-I groups. Expressions of mRNA and protein of LCHAD in trophoblast cells were detected by real-time polymerase chain reaction (PCR) and Western blot. (1) mRNA expression of LCHAD: the Δct of mRNA of LCHAD in F-FFA+DMED, SC-FFA+DMEM, MC-FFA+DMEM, LC-FFA+DMEM, LC-FFA+NADPH-I, LC-FFA+p38MAPK-I and VLC-FFA+DMEM, VLC-FFA+NADPH-I, VLC-FFA+p38MAPK-I groups were 4.57 ± 0.12, 4.36 ± 0.09, 4.55 ± 0.10, 6.84 ± 0.42, 4.45 ± 0.24, 5.08 ± 0.36, 2.23 ± 0.15, 3.90 ± 0.32, 3.81 ± 0.41. Compared with the F-FFA groups, the relative mRNA expressions of LCHAD significantly decreased in LC-FFA+DMEM/p38MAPK-I groups (P < 0.05) while increased in VLC-FFA groups (P < 0.05). Compared with the LC-FFA+DMEM groups, the relative mRNA expressions of LCHAD increased in LC-FFA+NADPH-I/p38MAPK-I groups (P < 0.05). The relative mRNA expressions of LCHAD in VLC-FFA+NADPH-I/p38MAPK-I groups significantly decreased versus VLC-FFA+DMEM group (P < 0.05). (2) Protein expression of LCHAD: The relative protein expressions of LCHAD in F-FFA+DMED, SC-FFA+DMEM, MC-FFA+DMEM, LC-FFA+DMEM, LC-FFA+NADPH-I, LC-FFA+p38MAPK-I and VLC-FFA+DMEM, VLC-FFA+NADPH-I, VLC-FFA+p38MAPK-I groups were 23.6 ± 13.0, 21.2 ± 10.2, 19.7 ± 1.9, 10.6 ± 2.6, 14.0 ± 1.8, 14.0 ± 2.8, 29.3 ± 1.9, 35.8 ± 3.2 and 35.2 ± 4.5 respectively. Compared with the F-FFA groups, the protein expressions of LCHAD significantly decreased in LC-FFA groups (P < 0.05) while increased in VLC-FFA+NADPH-I/p38MAPK-I groups (P < 0.05). Free fatty acids affect the gene and protein expressions of mitochondrial β-oxidation enzyme of LCHAD in trophoblastic cells. Fatty acid β-oxidation is impaired in trophoblast cells incubated with long-chain fatty acid. NADPH oxidase and p38MAPK inhibitors may alleviate such an effect. Thus p38MAPK signal transduction pathway may participate in this process. The correlation between very long chain fatty acids and fatty acid β-oxidation is confirmed. But their interactions require further explorations.

Effects of α3 neuronal nicotinic acetylcholine receptor on cell apoptosis and p38 MAPK signal transduction pathway in SH-SY5Y cells

To investigate the effects of α3 neuronal nicotinic acetylcholine receptor (nAChR) on apoptosis and p38 signal transduction pathway in SH-SY5Y cells and to assess the roles of α3 nAChR in the pathogenesis of Alzheimer's disease (AD). The levels of α3 nAChR mRNA and protein were measured by real-time PCR and Western blot, respectively, in SH-SY5Y cells transfected with α3 nAChR siRNA. The mRNA level of bcl-2 and bax was measured by the real-time PCR. The siRNA transfected SH-SY5Y cells and control were then treated with 10 µmol/L Aβ25-35 for another 48 h, and the change in apoptotic rate and the levels of p-p38 and p38 were measured by flow cytometry and Western blot. Subsequently these SH-SY5Y cells were exposed to a blocker of p38 protein, and the apoptotic rate was measured again. Compared to the controls, the expression of α3 nAChR at mRNA and protein levels in the SH-SY5Y cells transfected with α3 nAChR siRNA decreased by 95% and 86%, respectively; the mRNA levels of bax increased 2.11 times and that for bcl-2 decreased 0.53 times. The apoptotic rate was unaffected (3.40% ± 0.20%); but it increased after Aβ25-35 treatment (24.52% ± 1.59%); the level of p-p38 protein also increased by 178% in the α3 nAChR inhibited cells treated with Aβ25-35. Compared to controls, the Aβ25-35-treated SH-SY5Y cells and the Aβ25-35-treated and siRNA-transfected cells both showed a reduction in apoptosis after treatment with p38 blocker, especially in the former. The siRNA silencing of α3 nAChR mRNA may enhance the effect of Aβ25-35 on the cell apoptosis by increasing the levels of p38 protein and bax mRNA and decreasing the level of bcl-2 mRNA, which may play a role in the pathogenesis of AD.