Mitogen-activated protein kinase phosphatase 1 protects PC12 cells from amyloid beta-induced neurotoxicity

The mitogen-activated protein kinase（MAPK） signaling pathway plays an important role in the regulation of cell growth, proliferation, differentiation, transformation and death. Mitogen-activated protein kinase phosphatase 1（MKP1） has an inhibitory effect on the p38 MAPK and JNK pathways, but it is unknown whether it plays a role in Aβ-induced oxidative stress and neuronal inflammation. In this study, PC12 cells were infected with MKP1 sh RNA, MKP1 lentivirus or control lentivirus for 12 hours, and then treated with 0.1, 1, 10 or 100 μM amyloid beta 42（Aβ42）. The cell survival rate was measured using the cell counting kit-8 assay. MKP1, tumor necrosis factor-alpha（TNF-α） and interleukin-1β（IL-1β） m RNA expression levels were analyzed using quantitative real time-polymerase chain reaction. MKP1 and phospho-c-Jun N-terminal kinase（JNK） expression levels were assessed using western blot assay. Reactive oxygen species（ROS） levels were detected using 2′,7′-dichlorofluorescein diacetate. Mitochondrial membrane potential was measured using flow cytometry. Superoxide dismutase activity and malondialdehyde levels were evaluated using the colorimetric method. Lactate dehydrogenase activity was measured using a microplate reader. Caspase-3 expression levels were assessed by enzyme-linked immunosorbent assay. Apoptosis was evaluated using the terminal deoxynucleotidyl transferase d UTP nick end labeling method. MKP1 overexpression inhibited Aβ-induced JNK phosphorylation and the increase in ROS levels. It also suppressed the Aβ-induced increase in TNF-α and IL-1β levels as well as apoptosis in PC12 cells. In contrast, MKP1 knockdown by RNA interference aggravated Aβ-induced oxidative stress, inflammation and cell damage in PC12 cells. Furthermore, the JNK-specific inhibitor SP600125 abolished this effect of MKP1 knockdown on Aβ-induced neurotoxicity. Collectively, these results show that MKP1 mitigates Aβ-induced apoptosis, oxidative stress and neuroinflammation by inhibiting the JNK signaling pathway, thereby playing a neuroprotective role.

Bacteroides fragilis enterotoxin upregulates heme oxygenase-1 in dendritic cells via reactive oxygen species-,mitogen-activated protein kinase-,and Nrf2-dependent pathway

BACKGROUND Enterotoxigenic Bacteroides fragilis(ETBF)causes colitis and diarrhea,and is considered a candidate pathogen in inflammatory bowel diseases as well as colorectal cancers.These diseases are dependent on ETBF-secreted toxin(BFT).Dendritic cells(DCs)play an important role in directing the nature of adaptive immune responses to bacterial infection and heme oxygenase-1(HO-1)is involved in the regulation of DC function.AIM To investigate the role of BFT in HO-1 expression in DCs.METHODS Murine DCs were generated from specific pathogen-free C57BL/6 and Nrf2−/−knockout mice.DCs were exposed to BFT,after which HO-1 expression and the related signaling factor activation were measured by quantitative RT-PCR,EMSA,fluorescent microscopy,immunoblot,and ELISA.RESULTS HO-1 expression was upregulated in DCs stimulated with BFT.Although BFT activated transcription factors such as NF-κB,AP-1,and Nrf2,activation of NF-κB and AP-1 was not involved in the induction of HO-1 expression in BFT-exposed DCs.Instead,upregulation of HO-1 expression was dependent on Nrf2 activation in DCs.Moreover,HO-1 expression via Nrf2 in DCs was regulated by mitogenactivated protein kinases such as ERK and p38.Furthermore,BFT enhanced the production of reactive oxygen species(ROS)and inhibition of ROS production resulted in a significant decrease of phospho-ERK,phospho-p38,Nrf2,and HO-1 CONCLUSION These results suggest that signaling pathways involving ROS-mediated ERK and p38 mitogen-activated protein kinases-Nrf2 activation in DCs are required for HO-1 induction during exposure to ETBF-produced BFT.

A role for mitogen-activated protein kinase phosphatase 1(MKP1) in neural cell development and survival

The mitogen-activated protein kinase（MAPK）pathways are a group of conserved intracellular signalling pathways present in most cells including neurons and glia.These pathways respond to a variety of stimuli including growth factors,cytokines and oxidative stress to generate appropriate cellular responses such as modulation of gene expression,cell proliferation,differentiation and survival as well as the stress response（Korhonen and Moilanen,2014）.

“Three Methods and Three Points” regulates p38 mitogen-activated protein kinase in the dorsal horn of the spinal cord in a rat model of sciatic nerve injury

Tuina is a traditional Chinese treatment for sensory disturbances caused by peripheral nerve injury and related diseases. Our previous studies showed that tuina regulates relevant regions and indices of the spinal dorsal horn using the Dian, Bo, and Rou method in Yinmen（BL37）, Yanglingquan（GB34）, and Weizhong（BL40）. Treatment prevents muscle atrophy, protects spinal cord neurons, and promotes sciatic nerve repair. The mechanisms of action of tuina for treating peripheral nerve injury remain poorly understood. This study established rat models of sciatic nerve injury using the crushing method. Rats received Chinese tuina in accordance with the principle of ＂Three Methods and Three Points,＂ once daily for 20 days. Tuina intervention reduced paw withdrawal latency and improved wet weight of the gastrocnemius muscle, as well as promoting morphological recovery of sciatic nerve fibers, Schwann cells, and axons. The protein expression levels of phospho-p38 mitogen-activated protein kinase, tumor necrosis factor-α, and interleukin-1β also decreased. These findings indicate that ＂Three Methods and Three Points＂ promoted morphological recovery and improved behavior of rats with peripheral nerve injury.

Arabidopsis RNA polymerase Ⅱ C-terminal domain phosphatase-like 1 targets mitogen-activated protein kinase cascades to suppress plant immunity

Mitogen-activated protein kinase(MAPK) cascades play pivotal roles in plant defense against phytopathogens downstream of immune receptor complexes. The amplitude and duration of MAPK activation must be strictly controlled, but the underlying mechanism remains unclear. Here, we identified Arabidopsis CPL1(C-terminal domain phosphatase-like 1)as a negative regulator of microbe-associated molecular pattern(MAMP)-triggered immunity via a forward-genetic screen. Disruption of CPL1 significantly enhanced plant resistance to Pseudomonas pathogens induced by the bacterial peptide fg22. Furthermore, fg22-induced MPK3/MPK4/MPK6 phosphorylation was dramatically elevated in cpl1 mutants but severely impaired in CPL1 overexpression lines, suggesting that CPL1 might interfere with fg22-induced MAPK activation. Indeed, CPL1 directly interacted with MPK3 and MPK6, as well as the upstream MKK4 and MKK5. A firefy luciferase-based complementation assay indicated that the interaction between MKK4/MKK5 and MPK3/MPK6 was significantly reduced in the presence of CPL1. These results suggest that CPL1 plays a novel regulatory role in suppressing MAMP-induced MAPK cascade activation and MAMP-triggered immunity to bacterial pathogens.

Phosphoprotein Phosphatase 1 Isoforms Alpha and Gamma Respond Differently to Prodigiosin Treatment and Present Alternative Kinase Targets in Melanoma Cells

Reversible protein phosphorylation is a central regulatory mechanism of cell function. Deregulation of the balanced actions of protein kinases and phosphatases has been frequently associated with several pathological conditions, including cancer. Many studies have already addressed the role of protein kinases misregulation in cancer. However, much less is known about protein phosphatases influence. Phosphoprotein Phosphatase 1 (PPP1) is one of the major serine/threonine protein phosphatases who has three catalytic isoforms: PPP1CA, PPP1CB, and PPP1CC. Its function is achieved by binding to regulatory subunits, known as PPP1-interacting proteins (PIPs), which may prefer a catalytic isoform. Also, some inhibitors/enhancers may exhibit isoform specificity. Here we show that, prodigiosin (PG), a molecule with anticancer properties, promotes the formation of PPP1CA-AKT complex and not of PPP1CC-MAPK complex. Both, AKT and MAPK, are well-known PIPs from two pathways that crosstalk and regulate melanoma cells survival. In addition, the analysis performed using surface plasmon resonance (SPR) technology indicates that PPP1 interacts with obatoclax (OBX), a drug that belongs to the same family of PG. Overall, these results suggest that PG might, at least in part, act through PPP1C/PIPs. Also, this study is pioneer in demonstrating PPP1 isoform-specific modulation by small molecules.

Advanced oxidation protein products induce monocyte chemoattractant protein-1 expression via p38 mitogen-activated protein kinase activation in rat vascular smooth muscle cells

Background Advanced oxidation protein products （AOPPs） are new uremic toxins reported by Witko-Sarsat in 1996, which are associated with the pathogenesis of atherosclerosis. However, the mechanisms by which AOPPs enhance atherosclerosis have not been fully understood. Monocyte chemoattractant protein-1 （MCP-1） is a chemokine which stimulates migration of monocytes and plays a critical role in the development of atherosclerosis. In this study, we investigated the effect of AOPPs on MCP-1 expression in cultured vascular smooth muscle cells （VSMCs）.

Follistatin-Like 1 Promotes Bleomycin-lnduced Pulmonary Fibrosis through the Transforming Growth Factor Beta 1/Mitogen-Activated Protein Kinase Signaling Pathway

Background： Follistatin-like I （FSTL 1） is a novel profibrogenic factor that induces pulmonary fibrosis （PF） through the transforming growth factor-beta 1 （TGF-[B 1 ）/Smad signaling. Little is known about its effects on PF through the non-Smad signaling, like the mitogen-activated protein kinase （MAPK） pathway. Therefore, this study aimed to investigate the role ofFSTL 1 in PF through the MAPK signaling pathway and its mechanisms in lung fibrogenesis. Methods： PF was induced in Fstll~ and wild-type （WT） C57BL/6 mice with bleomycin. After 14 days, the mice were sacrificed, and lung tissues were stained with hematoxylin and eosin; the hydroxyproline content was measured to confirm PF. The mRNA and protein level of FSTLI and the change of MAPK phosphorylation were measured by quantitative polymerase chain reaction and Western blotting. The effect of Fst11 deficiency on fibroblasts differentiation was measured by Western blotting and cell immunofluorescence. MAPK signaling activation was measured by Western blotting in Fst11＋/ and WT fibroblasts treated with recombinant human FSTLI protein. We pretreated mouse lung fibroblast cells with inhibitors of the extracellular signal-regulated kinase （ERK）, p38, and Jun N-terminal kinase （JNK） signaling and analyzed their differentiation, proliferation, migration, and invasion by Western blotting, 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide analysis, and transwell assays. The Student＇s t-test was used to compare the differences between two groups. Results： Fstll deficiency attenuated phosphorylation of the ERK, p38, and JNK signaling in bleomycin-induced fibrotic lung tissue 14 days after injury （0.67 ± 0.05 vs. 1.22 ± 0.03, t = 14.92, P = 0.0001; 0.41 ± 0.01 vs. 1.15 ± 0.07; t = 11.19; P = 0.0004; and 0.41 ± 0.01 vs. 1.07± 0.07, t = 8.92, P = 0.0009; respectively）, compared with WT lungs at the same time and in primary lung fibroblasts （0.82 ± 0.01 vs. 1.01 ±0.04, t = 4.06, P = 0.0150; 1.04 ±0.03 vs. 1.24 ± 0.03, t= 4.44, P = 0.0100： and 0.76 ±0.05 vs. 0.99± 0.05, t = 4.48, P = 0.0100; respectively）, compared with TGF-β1-stimulated WT group. Recombinant human FSTLI protein in lung fibroblasts enhanced TG F-β1 -mediated phosphorylation of the ERK （ 1.19± 0.08 vs, 0.55 ± 0.04, t = 6.99, P = 0.0020）, p38 （ 1.18 ±0.04 vs. 0.66 ± 0.03, t = 11.20, P = 0.0020）, and .INK （ 1,11± 0.01 vs. 0.84 ± 0.04, t = 6.53, P = 0.0030）, compared with the TGF-β1-stimulated WT group. Fstll-deficient fibroblasts showed reduced alpha-smooth muscle actin （α-SMA） expression （0.70 ± 0.06 vs. 1.28 ±0.11, t = 4.65, P = 0.0035, compared with the untreated WT group; 1.40 ± 0.05 vs. 1.76± 0.02, t = 6.31, P = 0.0007; compared with the TGF-β1-treated WT group）. Compared with the corresponding condition in the control group, the TGF-β1/FSTL 1-mediated α-SMA expression was significantly suppressed by pretreatment with an inhibitor of p38 （0.73± 0.01 vs. 1.13 ± 0.10, t = 3.92, P = 0.0078） and JNK （0.78 ± 0.03 vs. 1.08 ± 0.06, t = 4.40,P = 0.0046） signaling. The proliferation of mouse lung fibroblast cells （MLgs） significantly decreased after treatment of an inhibitor of p38 （0.30 ±0.01 vs. 0.46 ±0.03, t = 4.64, P = 0.0009）, JNK （0.30 ± 0.01 vs. 0.49 ± 0.01, t = 12.84, P = 0.0001）, and Smad2/3 （0.18 ± 0.02 vs. 0.46 ±0.02, t = 12.69, P = 0.0001） signaling compared with the dimethylsulibxide group. The migration and invasion cells of MLgs significantly decreased in medium pretreated with an inhibitor of p38 （70.17 ±3.28 vs. 116.30 ± 7.11, t = 5.89, P = 0.0042 for the migratory cells; 19.87 ± 0.84 vs. 32.70 i 0.95, t =10.14, P = 0.0005 for the invasive cells）, JNK （72.30 ±3.85 vs. 116.30 ± 7.11, t = 5.44, P = 0.0056 for the migratory cells; 18.03 ± 0.94 vs. 32.70 ± 0.95, t = 11.00, P = 0.0004 for the invasive cells）, and Smad2/3 （64.76 ± 1.41 vs. 116.30 ± 7.11, t = 7.11, P = 0.0021 for the migratory cells; 18.03 ± 0.94 vs. 32.70 ±0.95, t = 13.29, P = 0.0002 for the invasive cells） signaling compared with the corresponding condition in the dimethylsulfoxide group. Conclusion： FSTL1 affects lung fibroblast differentiation, proliferation, migration, and invasion through p38 and JNK signaling, and in this way, it might influence the development of PF.

Synthetic lethal short hairpin RNA screening reveals that ring finger protein 183 confers resistance to trametinib in colorectal cancer cells

Background: The mitogen-activated extracellular signal-regulated kinase 1/2(MEK1/2) inhibitor trametinib has shown promising therapeutic effects on melanoma, but its efficacy on colorectal cancer(CRC) is limited. Synthetic lethality arises with a combination of two or more separate gene mutations that causes cell death, whereas individual mutations keep cells alive. This study aimed to identify the genes responsible for resistance to trametinib in CRC cells,using a synthetic lethal short hairpin RNA(shRNA) screening approach.Methods: We infected HT29 cells with a pooled lentiviral shRNA library and applied next-generation sequencing to identify shRNAs with reduced abundance after 8-day treatment of 20 nmol/L trametinib. HCT116 and HT29 cells were used in validation studies. Stable ring finger protein 183(RNF183)-overexpressing cell lines were generated by pcDNA4-myc/his-RNF183 transfection. Stable RNF 183-knockdown cell lines were generated by infection of lentiviruses that express RNF183 shRNA, and small interference RNA(siRNA) was used to knock down RNF183 transiently.Quantitative real-time PCR was used to determine the mRNA expression. Western blotting, immunohistochemical analysis, and enzyme-linked immunosorbent assay(ELISA) were used to evaluate the protein abundance. MTT assay,colony formation assay, and subcutaneous xenograft tumor growth model were used to evaluate cell proliferation.Results: In the primary screening, we found that the abundance of RNF183 shRNA was markedly reduced after treatment with trametinib. Trametinib induced the expression of RNF183, which conferred resistance to drug-induced cell growth repression and apoptotic and non-apoptotic cell deaths. Moreover, interleukin-8(IL-8) was a downstream gene of RNF183 and was required for the function of RNF183 in facilitating cell growth. Additionally, elevated RNF183 expression partly reduced the inhibitory effect of trametinib on IL-8 expression. Finally, xenograft tumor model showed the synergism of RNF183 knockdown and trametinib in repressing the growth of CRC cells in vivo.Conclusion: The RNF183-IL-8 axis is responsible for the resistance of CRC cells to the MEK1/2 inhibitor trametinib and may serve as a candidate target for combined therapy for CRC.

Electroacupuncture attenuates chronic salpingitis via transforming growth factor-β1/p38 mitogen-activated protein kinase signaling pathway

OBJECTIVE:To explore the effect of electroacupuncture(EA)on rats with chronic fallopian tube inflammation and its potential mechanisms.METHODS:Thirty-six female Sprague-Dawley rats were divided into Control,Model and EA groups.The pathological morphology of the fallopian tubes was observed by hematoxylin-eosin(HE)and Masson staining.The results of transforming growth factor-β1(TGF-β1),P38 mitogen-activated protein kinase(MAPK),phosphorylation(p)-p38MAPK in rat oviduct tissues were detected by immunohistochemistry.Results of P38MAPK,p-P38MAPK and TGF-β1 in rat oviduct tissues were detected by immunofluorescence.The expression level of p38MAPK,p-P38MAPK,TGF-β1 protein in rats was detected by Western blot.Quantitative real-time polymerase chain reaction(RT-q PCR)was used to detect m RNA expression levels of TGF-β1.RESULTS:It found that collagen fibers counts decreased significantly in EA group compared to Model group.The phosphorylation of P38MAPK in EA group was significantly reduced compared to Model group.The serum TGF-β1 expressions in EA group increased decreased significantly.CONCLUSION:Electroacupuncture was able to attenuate chronic salpingitis through down-regulating TGF-β1/MAPK signaling pathway.

Stress-activated kinases as therapeutic targets in pancreatic cancer

Pancreatic cancer is a dismal disease with high incidence and poor survival rates.With the aim to improve overall survival of pancreatic cancer patients,new therapeutic approaches are urgently needed.Protein kinases are key regulatory players in basically all stages of development,maintaining physiologic functions but also being involved in pathogenic processes.c-Jun N-terminal kinases(JNK)and p38 kinases,representatives of the mitogen-activated protein kinases,as well as the casein kinase 1(CK1)family of protein kinases are important mediators of adequate response to cellular stress following inflammatory and metabolic stressors,DNA damage,and others.In their physiologic roles,they are responsible for the regulation of cell cycle progression,cell proliferation and differentiation,and apoptosis.Dysregulation of the underlying pathways consequently has been identified in various cancer types,including pancreatic cancer.Pharmacological targeting of those pathways has been the field of interest for several years.While success in earlier studies was limited due to lacking specificity and off-target effects,more recent improvements in small molecule inhibitor design against stress-activated protein kinases and their use in combination therapies have shown promising in vitro results.Consequently,targeting of JNK,p38,and CK1 protein kinase family members may actually be of particular interest in the field of precision medicine in patients with highly deregulated kinase pathways related to these kinases.However,further studies are warranted,especially involving in vivo investigation and clinical trials,in order to advance inhibition of stress-activated kinases to the field of translational medicine.

Huangqi decoction(黄芪汤) attenuates renal interstitial fibrosis via transforming growth factor-β1/mitogen-activated protein kinase signaling pathways in 5/6 nephrectomy mice

OBJECTIVE: To investigate the effect of Huangqi decoction( 黄芪汤) on renal interstitial fibrosis and its association with the transforming growth factor-β1(TGF-β1)/mitogen-activated protein kinase(MAPK) signaling pathway. METHODS: 120 C57/BL mice were randomly divided into six groups: sham group, Enalapril(20 mg/kg) group, 5/6 nephrectomy model group, and 5/6 nephrectomy model plus Huangqicoction(0.12, 0.36 and 1.08 g/kg respectively) groups. Detecting 24hours urinary protein, blood pressure, serum creatinine, urea nitrogen content changes. Periodic Acid-Schiff stain(PAS) and Masson’s trichrome staining was used to observe the renal tissue pathological changes. Protein expression of TGF-β1, Phosphorylated P38 mitogen activated protein kinases(P-P38), Phosphorylated c-jun N-terminal kinase(P-JNK), Phosphorylated extracellular regulated proteinhnase(PERK), Fibroblast-specific protein-1(FSP-1), Alpha smooth muscle actin(α-SMA), Type Ⅲ collagen(Collagen Ⅲ), Connective tissue growth factor(CTGF),Bcl-2 Assaciated X protein(Bax) and B cell lymphoma 2(Bcl-2) were measured with western blot and immunohistochemical. RESULTS: Both Huangqi decoction and Enalapril improved the kidney function, 24 h urinary protein and the fibrosis in 5/6 nephrectomy mice, Huangqi decoction downregulated the expressions of TGF-β1, FSP-1, α-SMA, Collagen Ⅲ and CTGF in a dose-dependent manner, and it has a significant difference(P < 0.01) compared with model group.Huangqi decoction downregulated the expressions of P-P38, P-JNK, P-ERK and Bcl-2 in a dose-dependent manner, while upregulated the expression of Bax. CONCLUSIONS: The protective effect of Huangqi decoction for renal interstitial fibrosis in 5/6 nephrectomized mice via the inhibition of EpithelialMesenchymal Transitions and downregulating the TGF-β1/MAPK signaling pathway.

Effects of tetrandrine on phenotypic modulation of vascular smooth muscle cells and expression of p38 MAPK as well as MKP-1 after intimal injury of rabbit carotid arteries

Objective： To study the effects of tetrandrine （Tet） on phenotypic modulation of vascular smooth muscle cells （VSMCs） and expression of p38 mitogen-activated protein kinase （p38MAPK） as well as mitogen-activated protein kinase phosphatase-1 （MKP-1） after vascular intimal injury. Methods： HE staining was used to analyze vascular morphology of sham-injured group, injured group and Tet-treated group at day 28. lmmunohistochemistry, Western blot and RT-PCR were respectively used to detect the expression change of smooth muscle a-actin （SMa-actin）, proliferation cell nuclear antigen （PCNA）, p38MAPK and MKP-1 of injured group and Tet group at days 7, 14 and 28 after balloon injury. Results： ① All layers of vascular wall in sham-injured group were intact at day 28. The neointimal area was significantly increased and the lumen area notably decreased in injured group at day 28. The neointimal proliferation in Tet treated group was less than that in injured group, and the lumen area of Tet group was significantly increased than that of injured group at day 28. ②Compared with the injured group, the expression of SMa-actin, PCNA, p38MAPK and MKP-1 of vascular wall in Tet group was no difference, and the neointimal proliferation condition was also basically as same as injured group at day 7 after injury. The expression of PCNA and p38MAKP in Tet group was obviously lower than that in injured group, and the expression of MKP-1 in Tet group was obviously higher than that in injured group at days 14 and 28 after injury. The expression of SMa-actin in Tet group was slightly higher than that in injured group at days 14 and 28 after injury. Conclusions： Tet could reduce neointimal proliferation by inhibiting VSMCs phenotypic modulation and p38MAPK signaling transduction pathway as well as its down regulation.

Overexpression of MiR-633 Suppresses the Tumorigenicity of Gastric Cancer Cells and Induces Apoptosis by Targeting MAPK1

Objective MicroRNA(miRNA/miR)-633 is dysregulated in several types of cancers and is involved in tumorigenesis.However,the function and role of this miRNA in gastric cancer(GC)are not fully understood.The aim of the present study was to evaluate miR-633 expression in GC cell lines and in GC tissue vs.adjacent normal tissue,and to determine its association with clinicopathological data.This work was extended to investigate the effects of miR-633 overexpression on tumor cells in vitro.Methods Reverse transcription-quantitative PCR(RT-qPCR)was used to detect and compare the expression level of miR-633 in GC cells,as well as in GC and normal adjacent tissue samples.The clinical significance of miR-633 was also analyzed.MiR-633 lentivirus(LV-miR-633)and negative control lentivirus(LV-NC)were generated and used to transduce SGC-7901 and HGC-27 GC cells in order to analyze the effect of miR-633 on their phenotype.The effects of miR-633 overexpression on GC cell proliferation,apoptosis,migration and invasion were investigated.The target gene of miR-633 was predicted,then confirmed using a dual luciferase reporter gene assay,RT-qPCR and Western blotting.Results MiR-633 was significantly downregulated in GC cell lines,as well as in GC tissue compared with adjacent normal tissue.Moreover,miR-633 expression was associated with the tumor/node/metastasis(TNM)stage,invasion depth,Borrmann classification and lymph node metastasis(P<0.05).Compared with the LV-NC group,transduction with LV-miR-633 reduced the proliferation,the number of clones,the wound healing rate,the number of invading cells and the number of cells in the G1 phase of the cell cycle(P<0.01).LV-miR-633 also increased the apoptosis rate(P<0.01).The expression level of mitogen-activated protein kinase(MAPK)1,high-mobility group box 3(HMGB3),claudin 1(CLDN1)and MAPK13 were downregulated in LV-miR-633-transduced cells(P<0.01).The dual luciferase reporter assay confirmed that the 3′-untranslated region of MAPK1 was the target site of miR-633(P<0.01).Conclusion MiR-633 acts as a tumor suppressor in GC,and its expression level is associated with TNM stage,invasion depth,Borrmann type and lymph node metastasis.Overexpression of miR-633 inhibits the proliferation and migration of GC cells and induces apoptosis and cell cycle arrest at the in G1 phase.In addition,miR-633 negatively regulates the expression of MAPK1,HMGB3,CLDN1 and MAPK13 and directly targets MAPK1.

IL-1RⅠ/MyD88-TIR mimic AS-1 inhibits the activation of MyD88-dependent signaling pathway induced by IL-1β in vitro

Objective： To test whether IL-1 RI/My088-TIR mimic AS-1 can work as a new compound that targeted at blocking MyD88- dependent signaling pathway, we investigated the physical structure and biological function of AS-1. Methods：The crystallographic structure of AS-1 was examined by 1^H nuclear magnetic resonance. The toxicity of AS-1 was measured with Methyl thiazolyl tetrazolium （MTT） assay. The effect of AS-1 on phosphorylation state of p38 MAPK and IRAK-1 was observed with Western blot. Results：The crystallographic details of AS-1 demonstrated that it was a tri-peptide sequence[（F/Y）-（V/L/I）-（P/G）] of the IL-1R I -TIR domain BBloop. No toxicity of AS-1 was shown to HEK 293A cells. The phosphorylation of p38 MAPK, induced by IL-1β significantly increased from those in the control group. AS-1 significantly reduced the phosphorylation of p38 MAPK induced by IL-1β. IL-1β increased the phosphorylation of IRAK-1 significantly, which was prevented by AS-1. Conclusion：AS-1 is a competitive mimic between IL-1R I-TIR and MyD88-TIR domain, which most likely interferes with MyD88-dependent signaling pathway.

Cross-Talk between Extracellular S1P/S1P2 and P42/44 MAPK in bcr/abl Positive Chronic Myeloid Leukemia Cells

Objective： BCR/ABL oncoprotein-expression is associated with uncontrolled cell growth. Sphingosine kinase 1 （SPK1） regulates the production of sphingosine 1-phosphate （S1P）, a key lipid signal molecular in cell proliferation and survival. The objective of this study was to elucidate the roles of S1P and its receptors in bcr/abl positive chronic myeloid leukemia （CML） cells. Methods： The expressions of SIP receptors： S1P1, S1P2 and S1P3 in CML cells were detected by RT-PCR. SPK1 expression, activity and extracellular S1P were determined in ECV304 and HL-60 cells which were transfected with bcr/abl gene. To elucidate the relationship between the BCR/ABL, ERK/MAPK （extracellular signal-regulated kinase/mitogen-activated protein kinase）, SPK/S 1P and S 1P/S 1 P2 signal pathways, bcr/abl positive CML cell line K562 was treated with STI571, PD98059, N,N-dimethyl sphingosine （DMS） and JTE-013. Results： Retrovirus-mediated overexpression of bcr/abl gene in ECV304 and HL-60 cells resulted in upregulation of the expression, activity of SPK1 and increase of the secretion of SIP, whereas treatment of STI571 and PD98059 decreased the BCR/ABL-induced S1P secretion. Treatment of DMS reduced S1P secretion and P42/44MAPK phosphorylation. S1P2-selective antagonist JTE-013 could also decrease P42/44MAPK phosphorylation. Conclusion： These results suggest that BCR/ABL up-regulates extracellular sphingosine 1-phosphate through sphingosine kinase 1 and there is cross-talk between SPK1/S1P/S1P2 and P42/44MAPK in bcr/abl positive CML cells.

Treatment time influences the effects of a low-frequency pulsed electric field on synthesis of tyrosine hydroxylase and dopamine in PC12 cells

BACKGROUND： Electromagnetic radiation can influence dopamine （DA） synthesis in brain tissues or ceils, but electromagnetic frequencies, intensities, and radiation time can produce different effects. In addition, the signal pathway by which electromagnetic radiation influences DA synthesis remains controversial. OBJECTIVE： To determine tyrosine hydroxylase （TH） expression in PC12 cells and DA levels in cell culture media after different periods of low-frequency pulsed electric field （LF-PEF） stimulation, and to determine how LF-PEF signaling stimulates TH synthesis using inhibitors. DESIGN, TIME AND SETTING： A parallel, controlled, cell experiment was performed at the Laboratory of Cell Biology, School of Life Science, East China Normal University, between January and October 2006. MATERIALS： PC12 cells were purchased from the Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, China. Nerve growth factor was purchased from PeproTech, USA. The protein kinase A inhibitor, H-89, and mitogen-activated protein kinase kinase inhibitor, U0126, were purchased from Sigma, USA. METHODS： （1） Following routine culture in Dulbecco＇s modified eagle medium, primary PC12 cells were stimulated under LF-PEF （pulse frequency 50.Hz, pulse width 20 μs, peak field strength 1 V/m） for 5, 10, 15, 20, and 30 minutes. （2） Inhibitors （H-89 or U0126, 1 μmol/L） were added 30 minutes before LF-PEF stimulation for 10 minutes. MAIN OUTCOME MEASURES： （1） TH expression was determined by Western blot in PC12 cells at 0.5, 1,2, 3, and 4 days after LF-PEF stimulation. Similarly, DA was measured by high-performance liquid chromatography in media at 2, 3, 4, or 5 days after LF-PEE （2） TH expression was detected 1 day after H-89 or U0126 treatment and LF-PEE RESULTS： （1） Short-term LF-PEF stimulation （5 and 10 minutes） increased TH expression and media DA levels after short-term culture （2 days） （P 〈 0.01）, but both parameters decreased with longer culture （3 4 days） （P 〈 0.01）. Long-term LF-PEF stimulation （15, 20, or 30 minutes） decreased TH and DA synthesis, followed by a rapid increase （P 〈 0.01）. （2） H89 could completely inhibit TH expression in PC12 cells stimulated by LF-PEF for 10 minutes, while the inhibition rate of U0126 was 53.2%. CONCLUSION： Short-term LF-PEF first promotes then inhibits, while long-term LF-PEF first inhibits then promotes, TH and DA synthesis. LF-PEF stimulation regulates TH expression primarily by activating protein kinase A to regulate DA synthesis.

Cross-talk between Smad4 and P38 Proteins in Non-small Cell Lung Cancer

Objective： Impaired signal transduction is associated with tumorigenesis and progression of various kinds of human cancers. Transforming growth factor （TGF）-beta/Smad and ras-mitogen activated protein kinase （MAPK） are two major signal transduction pathways for adjusting cell proliferation and differentiation. Little is known about TGF-beta/Smad4 in non-small cell lung cancer （NSCLC）. Hereby, we investigated the expression of Smad4 in NSCLC, its correlation with MAPK proteins （including p38, ERK1 and JNK1 proteins） and their clinical significance in NSCLC. Methods： The expressions of Smad4, p38, ERK1 and JNK1 were detected at protein level with Western blotting and immunohistochemistry, at transcription level with RT-PCR. Statistical analysis was performed for the comparisons of expressions of Smad4, p38, ERK1 and JNK1, and their correlation with various clinicopathological parameters and the prognosis of NSCLC. Results： The levels of protein and mRNA expression of Smad4 in lung cancer tissues were significantly lower than in normal tissues （P〈0.05）. All these four proteins were associated with TNM staging. There was a strongly negative correlation between p38 and Smad4. Expressions of Smad4, p38 and JNK1, as well as tumor differentiation and staging were significantly correlated with the prognosis of NSCLC by univariate analysis. By multivariate analysis, only Smad4, p38, tumor differentiation and staging were correlated with the prognosis. Taken together, the negative expression of p38 and positive expression of Smad4 were associated with a better prognosis of NSCLC. Conclusion： Smad4 could be of vital importance for the initiation and development of NSCLC. The expression of Smad4 might be inhibited by p38, supporting a cross-talk between main proteins of TGF-beta/Smad and ras-MAPK signal transduction pathways. Smad4 and p38 could be possible prognostic factors for NSCLC.

Rhamnus crenata leaf extracts exhibit anti-inflammatory activity via modulating the Nrf2/HO-1 and NF-κB/MAPK signaling pathways

Objective:To elucidate the potential anti-inflammatory mechanisms of Rhamnus crenata leaf extracts using RAW264.7 cells.Methods:We used 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay to measure cell viability.Nitric oxide(NO)production was measured using Griess reagent.Western blotting and RT-PCR assays were carried out for analyzing the protein and gene expressions of pro-inflammatory mediators,respectively.Moreover,PD98059(ERK1/2 inhibitor),SB203580(p38 inhibitor),SP600125(JNK inhibitor),and BAY11-7082(NF-κB inhibitor)were used to evaluate the anti-inflammatory mechanism of Rhamnus crenata leaf extract.Results:Rhamnus crenata leaf extracts significantly inhibited the production of the pro-inflammatory mediators such as NO,iNOS,COX-2,IL-1β,and TNF-αin lipopolysaccharide(LPS)-stimulated RAW264.7 cells.Rhamnus crenata leaf extracts also suppressed LPS-induced degradation of IκB-αand nuclear accumulation of p65,which resulted in the inhibition of NF-κB activation in RAW264.7 cells.Additionally,the extracts attenuated the phosphorylation of p38,ERK1/2,and JNK in LPS-stimulated RAW264.7 cells.Moreover,HO-1 expression induced by Rhamnus crenata leaf extracts was significantly downregulated by SB230580,PD98059,SP600125 and BAY11-7082.Conclusions:Rhamnus crenata leaf extract may upregulate HO-1 expression through inhibition of p38,ERK1/2,and NF-κB activation,which may contribute to the anti-inflammatory activity of the extracts.Rhamnus crenata leaf extracts may have great potential for the development of anti-inflammatory drugs to treat acute and chronic inflammatory diseases.

Regulatory Effects of AT1R-TRAF6-MAPKs Signaling on Proliferation of Intermittent Hypoxia-induced Human Umbilical Vein Endothelial Cells

Summary： Endothelial dysfunction induced by intermittent hypoxia （IH） participates in obstructive sleep apnea syndrome （OSAS）-associated cardiovascular disorders. Myeloid differentiation primary response 88 （MyD88） and tumor necrosis factor receptor-associated factor 6 （TRAF6） regulate nu- merous downstream adaptors like mitogen-activated protein kinases （MAPKs） and the subsequent oxidative stress and inflammatory responses. This study aimed to characterize the role of MyD88/TRAF6 in IH-treated cell function and its associated signaling. Human umbilical vein endo- thelial cells （HUVECs） were randomly exposed to IH or normoxia for 0, 2, 4 and 6 h. Western blot- ting was used to detect the expression pattern of target gene proteins [angiotensin 1 receptor （AT1R）, p-ERK1/2, p-p38MAPK, MyD88 and TRAF6], and the relationships among these target genes down-regulated by the corresponding inhibitors were studied. Finally, the influence of these target genes on proliferation of HUVECs was also assessed by EdU analysis. Protein levels of AT1R, TRAF6 and p-ERK1/2 were increased after IH exposure, with a slight rise in MyD88 and a dynamic change in p-p38MAPK. The down-regulation of TRAF6 by siRNA reduced ERK1/2 phosphorylation during IH without any effects on ATIR. Blockade of AT1R with valsartan decreased TRAF6 and p-ERK1/2 protein expression after IH exposure. ERK1/2 inhibition with PD98059 suppressed only AT1R expression. IH promoted HUVECs proliferation, which was significantly suppressed by the in- hibition of TRAF6, AT1R and ERK1/2. The findings demonstrate that TRAF6 regulates the prolifera- tion of HUVECs exposed to short-term IH by modulating cell signaling involving ERK1/2 down- stream of AT1R. Targeting the AT1R-TRAF6-p-ERK1/2 signaling pathway might be helpful in re- storing endothelial function.