白介素-1β通过JNK/p38信号转导通路调控肾系膜细胞表达α-平滑肌肌动蛋白

为探讨细胞内丝裂素原活化蛋白激酶 (MAPK)家族各亚类信号转导通路在炎症性细胞因子白介素 1β(IL 1β)对大鼠肾系膜细胞 (rMC)表型标志物α 平滑肌肌动蛋白 (α SMA)表达及其分布中的调控作用 ,以IL 1β(10ng/ml)刺激体外培养的rMC ,用电穿孔基因转染及免疫杂交法观察IL 1β对α SMA基因启动子活性及蛋白表达的作用 ,并用共聚焦荧光显微镜及透射电镜观察IL 1β刺激前后细胞内α SMA及微丝的分布变化。通过应用PD980 5 9和SB2 0 35 80特异阻断ERK和 p38通路、共转染显性失活JNKK基因特异阻断JNK通路 ,观察阻断对IL 1β刺激所致α SMA表达或启动子活性的影响。结果显示 ,IL 1β刺激 6h可明显上调α SMA启动子活性 ,在 1～ 2d内显著促进其蛋白合成 ;IL 1β刺激 2 4h后 ,细胞内α SMA及微丝在细胞核周的分布增加。阻断ERK通路对IL 1β诱导的α SMA表达无明显影响 ;阻断JNK及 p38通路均可使IL 1β诱导的α SMA表达明显受抑 ;阻断 p38通路的作用比阻断JNK通路更强 ,而且对基础状态的α SMA表达也有抑制作用。上述结果提示 ,IL 1β可刺激rMC发生表型转化 ,其表型标志物α SMA可通过基因转录增强而增加蛋白表达 ,在细胞内的分布向核周转位积聚。JNK及p38通路是介导IL 1β刺激rMCα

雌激素对阿尔茨海默病大鼠模型MAPK蛋白表达的影响

目的探讨雌激素对阿尔茨海默病(AD)大鼠模型学习记忆能力及丝裂霉原活化的蛋白激酶(MAPK)蛋白表达的影响。方法30只大鼠行卵巢切除术(OVX)后,均分成OVX组和雌激素替代治疗组(ERT),然后采用1μlofAβ1～40(10μg/μl)立体定位单侧海马内注射建立AD动物模型,通过水迷宫实验检测动物模型的学习、记忆能力;免疫组化检测MAPK蛋白表达情况。结果ERT组AD动物模型的水迷宫逃避潜伏期较OVX组明显缩短(P<0.05),同时ERT组AD动物模型的海马CA1、CA3区的MAPK表达上调(P<0.05)。结论雌激素可以改善AD动物模型的认知功能,其神经保护作用可能与上调海马MAPK表达有关。

P38MAPK信号通路与uPA在卵巢癌细胞及组织中表达的相关性

背景与目的:P38丝裂原活化蛋白激酶(P38 mitogen-activated protein kinase,P38MAPK)信号通路参与多种肿瘤的发生、发展和转移过程,尿激酶型纤溶酶原激活剂(urokinase-type plasminogen activator,uPA)在肿瘤浸润和转移中发挥着重要作用。本实验研究卵巢癌组织中P38MAPK、细胞外信号调节激酶(extracellular signal-regulated kinase,ERK)、丝氨酸苏氨酸蛋白激酶(serine threonine kinase,AKT)及uPA的表达与临床病理特征的关系,并分析上述蛋白与u PA表达的相关性,探讨P38MAPK信号通路与uPA在卵巢癌细胞及组织中的表达及临床意义。方法:应用免疫组织化学法检测49例卵巢癌组织中u PA、P38MAPK、ERK和AKT蛋白的表达,采用蛋白[质]印迹法(Western blot)检测不同卵巢癌细胞系HO8910、HO-8910PM、SKOV3和CAOV3中uPA和P38MAPK蛋白的表达,使用特异性抑制剂SB203580阻断P38MAPK信号通路后检测u PA蛋白表达水平的变化。结果:uPA、P38MAPK、ERK和AKT蛋白在卵巢癌组织中的表达阳性率分别为61.22%、57.14%、53.06%和55.10%。uPA蛋白的表达与P38MAPK呈正相关(r=0.865,P=0.001),且与卵巢癌组织的临床病理分期(P=0.029)、分化(P=0.03)和转移程度(P淋巴=0.022,P大网膜=0.012)有关,而与患者的年龄(P=0.754)及组织学类型(P=0.652)无关。ERK、AKT蛋白的表达与卵巢癌淋巴结转移(PERK=0.011,PAKT=0.022)和大网膜转移(PERK=0.006,PAKT=0.000)有关,而与患者的年龄(PERK=0.000,PAKT=0.022)、组织类型(PERK=0.771,PAKT=0.245)及病理分期(PERK=1.000,PAKT=0.254)无关。卵巢癌细胞系HO-8910PM中uPA蛋白的表达水平明显高于HO8910、SKOV3和CAOV3细胞系,使用SB203580阻断P38MAPK信号通路后可降低uPA蛋白的表达,且随着SB203580浓度升高u PA蛋白表达水平逐渐降低。卵巢癌中P38MAPK及u PA蛋白的表达与卵巢癌的预后显著相关(Log-rank=3.897和11.044,P=0.048和0.001)。结论:卵巢癌组织中P38MAPK信号通路处于激活状态;P38MAPK信号通路的激活可上调u PA的表达,促进卵巢癌的恶性进展;P38MAPK信号通路和u PA可能在卵巢癌侵袭和转移的过程中发挥重要作用。P38MAPK和uPA蛋白有望成为卵巢癌预后评估的重要指标。

慢性间歇性缺氧状态下MAPK信号通路对舌下神经核调控的初步研究

目的探讨不同程度的慢性间歇性缺氧(chronic intermittent hypoxia, CIH)状态下,大鼠舌下神经核中MAPK通路相关蛋白(JNK、p38MAPK、ERK)激活后的表达水平。方法将18只雄性SD大鼠随机分为CIH 3周、8周组和常氧对照组。CIH组大鼠于氧浓度5%~21%之间循环的低氧舱中分别饲养3周和8周,对照组大鼠常氧舱的氧浓度保持在21%饲养8周,随后观察各组大鼠舌下神经核中p-JNK、p-p38MAPK、p-ERK的表达量。结果 CIH组p-JNK、p-p38MAPK和p-ERK在舌下神经核的表达量均显著增加,且随CIH时间呈现增高趋势。p-JNK和p-p38MAPK在腹侧核的表达更显著。结论舌下神经核对CIH的损伤与调节反应中,MAPK信号通路可能发挥了重要作用。腹侧核与背侧核对CIH的不同反应,可能是其所支配的上呼吸肌群调控的基础。

Involvement of MAPK/ERK kinase-ERK pathway in exogenous bFGF-induced Egr-1 binding activity enhancement in anoxia-reoxygenation injured astrocytes

Objective Intravenous administration of basic fibroblast growth factor （bFGF） is effective to reduce the volume of cerebral infract due to ischemia. This study was designed to investigate the molecular mechanism, especially the signal transduction pathways, involved in this protective role of bFGF. Methods Anoxia-reoxygenation treated atrocytes were used to study the role of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase （MAPK/ERK kinase, MEK）-ERK signaling pathway after exogenous bFGF administration by Western blot. Electrophoretic mobile shift assay was used to detect the binding activity of early growth response factor-1 （Egr-1）, an important transcription factor for endogenous bFGF. Results bFGF could protect some signal transduction proteins from the oxygen-derived free radicals induced degradation. ERK1/2 was activated and involved in Egr-1 binding activity enhancement induced by exogenous bFGF. Conclusion MEK-ERK MAPK cascade may be an important signal transduction pathway contributed to bFGF induced enhancement of Egr-1 binding activity in anoxia-reoxygenation injured astrocytes.

TNFR-Fc对急性肺损伤炎症失衡中MAPK通路的影响

目的评价在脂多糖(LPS)导致的炎症反应失衡中,肿瘤坏死因子受体Fc段融合蛋白(TNFR-Fc)对丝裂原活化蛋白激酶(MAPKs)磷酸化水平的影响。方法24只BALB/c小鼠随机平均分为LPS组与TNFR-Fc+LPS组。气管内滴入LPS复制急性肺损伤(ALI)的炎症失衡小鼠模型,腹腔内注射TNFR-Fc中和肿瘤坏死因子(TNF-α),2小时后收集标本,ELISA法检测血清/支气管肺泡灌洗液(BALF)中白细胞介素-1β(IL-1β)、IL-6、IL-10、干扰素-γ(IFN-γ)浓度,RT-PCR法检测肺组织TNF-α与核因子-κB(NF-κB)基因转录强度,Western Blot检测肺组织MAPKs(包括Erk1/2、p38与JNK)磷酸化水平。结果两组小鼠在气管内滴入LPS后血清与BALF中IL-6浓度显著增高,TNF-α转录水平增高,MAPKs磷酸化水平增高;TNFR-Fc+LPS组小鼠血清与BALF中IL-6浓度较LPS组显著降低,TNF-α转录水平下降,MAPK磷酸化水平下降。结论TNFR-Fc中和TNF-α能下调炎症反应信号通路中MAPKs磷酸化水平,下调炎症反应强度,恢复ALI小鼠的炎症反应失衡。

Epithelial-to-mesenchymal and mesenchymal-to-epithelial transitions in the colon

Epithelial-to-mesenchymal and mesenchymal-to-epi- thelial transitions are well established biological events which have an important role in not just normal tissue and organ development, but in the pathogenesis of diseases. Increasing evidence has established their presence in the human colon during colorectal carcinogenesis and cancer invasion, chronic inflammation-related fibrosis and in the course of mucosal healing. A large body of evidence supports the role for transforming growth factor-13 and its downstream Smad signaling, the phosphatidylinositol 3＇-kinase/Akt/mTOR axis, the Ras-mitogen-activated protein kinase/Snail/Slug and FOXC2 pathway, and Hedgehog signaling and microR- NAs in the development of colorectal cancers via epi- thelial-to-mesenchymal transition. C-met and Frizzled-7, among others, seem to be the principle effectors of mesenchymal-to-epithelial transition, hence have a role not just in mucosal regeneration but in the progression of colonic wall fibrosis. Here we discuss a role for these pathways in the initiation and development of the transition events. A better understanding of their induction and regulation may lead to the identification of pathways and factors that could be potent therapeu- tic targets. The inhibition of epithelial-to-mesenchymal transition using mTOR kinase inhibitors targeting theATP binding pocket and which inhibit both mTORC1 and mTORC2, RNA aptamers or peptide mimetics, such as a Wnt5A-mimetic, may all be useful in both cancer treatment and delaying fibrosis, while the induction of mesenchymal-to-epithelial transition in induced pluripotent stem cells may enhance epithelial healing in the case of severe mucosal damage. The preliminary results of the current studies are promising, but more clinical investigations are needed to develop new and safe therapeutic strategies for diseases of the colon.

HBx activates FasL and mediates HepG2 cell apoptosis through MLK3-MKK7-JNKs signal module

AIM： To investigate the possible mechanism by which hepatitis B virus X protein （HBx） mediates apoptosis of HepG2 cells. METHODS： HBx expression vector pcDNA3.1-X was transfected into HepG2 cells to establish an HBx high- expression cellular model as pcDNA3.1-X transfected group. The pcDNA3.1-X and pSilencer3.1-shHBX （HBx antagonist） were cotransfected into HepG2 cells to es- tablish an HBx low-expression model as RNAi group. Untransfected HepG2 cells and HepG2 cells transfected with negative control plasmid were used as controls. Apoptosis rate, the expression of Fas/FasL signaling pathway-related proteins and the phosphorylation lev- els of MLK3, MKK7 and JNKs, which are upstream molecules of death receptor pathways and belong to the family of mitogen-activated protein kinases （MAPKs）,were measured in each group RESULTS： Compared with HepG2 cell group and RNAi group, apoptosis rate, the expression of Fas and FasL proteins, and the activation of MLK3, MKK7 and 3NKs were increased in the pcDNA3.1-X transfected group. The activation of JNKs and expression of FasL protein were inhibited in the pcDNA3.1-X transfected group when treated with a known JNK inhibitor, SP600125. When authors treated pcDNA3.1-X transfected group with K252a, a known MLK3 inhibitor, the activation of MLK3, MKK7 and 3NKs as well as expression of FasL protein was inhibited. Furthermore, cell apoptosis rate was also significantly declined in the presence of K252a in the pcDNA3.1-X transfected group. CONCLUSION： HBx can induce HepG2 cell apoptosis via a novel active MLK3-MKK7-JNKs signaling module to upregulate FasL protein expression.

p28^GANK inhibits endoplasmic reticulum stress-induced cell death via enhancement of the endoplasmic reticulum adaptive capacity

It has been shown that oncoprotein p28GANK, which is consistently overexpressed in human hepatocellular carcinoma （HCC）, plays a critical role in tumorigenesis of HCC. However, the underlying mechanism remains unclear. Here, we demonstrated that p28GANK inhibits apoptosis in HCC cells induced by the endoplasmic reticulum （ER） stress. During ER stress, p28GANK enhances the unfolded protein response, promotes ER recovery from translational repression, and thereby facilitates cell＇s ability to cope with the stress conditions. Furthermore, p28GANK upregulates glucose-regulated protein 78 （GRP78）, a key ER chaperone protein, which subsequently enhances the ER folding capacity and promotes recovery from ER stress. We also demonstrated that p28GANK increases p38 mitogen-activated protein kinase and Akt phosphorylation, and inhibits nuclear factor kappa B （NF-κB） activation under ER stress, which in turn contributes to GRP78 upregulation. Taken together, our results indicate that p28GANK inhibits ER stress-induced apoptosis in HCC cells, at least in part, by enhancing the adaptive response and GRP78 expression. We propose that p28GANK has potential implications for HCC progression under the ER stress conditions.

Components of the mitogen-activated protein kinase cascade are activated in hepatic cells by Echinococcus multilocularis metacestode

AIM： To explore the effect of Echinococcusmultilocularis on the activation of mitogen-activated protein kinase （MAPK） signaling pathways and on livercell proliferation.METHODS： Changes in the phosphorylation of MAPKs and proliferating cell nuclear antigen （PCNA）expression were measured in the liver of patients withalveolar echinococcosis （AE）. MAPKs, MEK1/2 [MAPK/extracellular signal-regulated protein kinase （ERK）kinase] and ribosomal S6 kinase （RSK） phosphorylationwere detected in primary cultures of rat hepatocytesin contact in vitro with （1） E. multilocu/aris vesicle fluid（EmF）, （2）E. multilocularis-conditioned medium （EmCM）.RESULTS： In the liver of AE patients, ERK 1/2 andp38 MAPK were activated and PCNA expression wasincreased, especially in the vicinity of the metacestode.Upon exposure to EmF, p38, c-Jun N-terminal kinase（JNK） and ERK1/2 were also activated in hepatocytesin vitro, as well as MEK1/2 and RSK, in the absenceof any toxic effect. Upon exposure to EmCM, only JNKwas up-regulated.CONCLUSION： Previous studies have demonstratedan influence of the host on the MAPK cascade inE. multilocularis. Our data suggest that the reverse,i.e. parasite-derived signals efficiently acting onMAPK signaling pathways in host liver ceils, is actuallyoperating.

Reactive oxygen species: A double-edged sword in oncogenesis

Reactive oxygen species (ROS) are molecules or ions formed by the incomplete one-electron reduction of oxygen. Ofinterest, it seems that ROS manifest dual roles, cancer promoting or cancer suppressing, in tumorigenesis. ROS participate simultaneously in two signaling pathways that have inverse functions in tumorigenesis, Ras-Raf-MEK1/2-ERK1/2 signaling and the p38 mitogen-activated protein kinases (MAPK) pathway. It is well known that Ras-Raf-MEK1/2-ERK1/2 signaling is related to oncogenesis, while the p38 MAPK pathway contributes to cancer suppression, which involves oncogene-induced senescence, inflammationinduced cellular senescence, replicative senescence, contact inhibition and DNA-damage responses. Thus, ROS may not be an absolute carcinogenic factor or cancer suppressor. The purpose of the present review is to discuss the dual roles of ROS in the pathogenesis of cancer, and the signaling pathway mediating their role in tumorigenesis.

Effects of lysophosphatidic acid on human colon cancer cells and its mechanisms of action

AIM： To study the effects of lysophosphatidic acid （LPA） on proliferation, adhesion, migration, and apoptosis in the human colon cancer cell line, SW480, and its mechanisms of action. METHODS： Methyl tetrazolium assay was used to assess cell proliferation. Flow cytometry was employed to detect cell apoptosis. Cell migration was measured by using a Boyden transweU migration chamber. Cell adhesion assay was performed in 96-well plates according to protocol. RESULTS： LPA significantly stimulated SW480 cell proliferation in a dose-dependent and timeependent manner compared with the control group （P 〈 0.05） while the mitogen-activated protein kinase （MAPK） inhibitor, PD98059, significantly blocked the LPA stimulation effect on proliferation. LPA also significantly stimulated adhesion and migration of SW480 cells in a dosedependent manner （P 〈 0.05）. Rho kinase inhibitor, Y-27632, significantly inhibited the upegulatory effect of LPA on adhesion and migration （P 〈 0.05）. LPA significantly protected cells from apoptosis induced by the chemotherapeutic drugs, cisplatin and 5-FU （P 〈 0.05）, but the phosphoinositide 3-kinase （PI3K） inhibitor, LY294002, significantly blocked the protective effect of LPA on apoptosis. CONCLUSION： LPA stimulated proliferation, adhesion,migration of 5W480 cells, and protected from apoptosis. The Ras/Raf-MAPK, G12/13-Rho-RhoA and PI3K- AKT/PKB signal pathways may be involved.

Molecular mechanism and functional consequences of lansoprazole-mediated heme oxygenase-1 induction

AIM： To investigate the molecular mechanism and functional consequences of heme oxygenase-1 （HO-1） activation by lansoprazole in endothelial cells and macrophages. METHODS： Expression of HO-1 mRNA was analyzed by Northern blotting. Western blotting was used to determine the HO-1 and ferritin protein levels. NADPH-dependent reactive oxygen species （ROS） formation was measured with lucigenin-enhanced chemiluminescence. HO-1 promoter activity in mouse fibroblasts, stably transfected with a 15-kb HO-1 gene that drives expression of the reporter gene luciferase, was assessed usingin vivo bioluminescence imaging. RESULTS： Lansoprazole levels in endothelial cells increased HO-1 mRNA and HO-1 protein levels in macrophages. In addition, lansoprazole-induced ferritin protein levels in both cell systems. Moreover, induction of the antioxidant proteins HO-1 and ferritin by lansoprazole was followed by a decrease in NADPH- mediated ROS formation. The radical scavenging properties of lansoprazole were diminished in the presence of the HO inhibitor, chromium mesoporphyrin IX. Induction of HO-1 gene expression by lansoprazole was not related to oxidative stress or to the activation of the mitogen-activated protein kinase pathway. However, the phosphatidylinositol 3-kinase inhibitor LY294002 showed a concentration-dependent inhibition of HO-1 mRNA and promoter activity.CONCLUSION： Activation of HO-1 and ferritin may account for the gastric protection of lansoprazole and is dependent on a pathway blocked by LY294002.

The effect of C-terminal fragment of JNK2 on the stability of p53 and cell proliferation

The basal activity of JNK is low in normal growing cells and inactivated JNK targets p53 for ubiquitination. To elucidate if the C-terminal part of JNK is responsible for its binding to p53, the low background tet-off inducible NIH3T3 cell line was selected by luciferase reporter gene and a double stable C-JNK Aa (203-424) cell line was established. After withdrawing tetracycline, the C-JNK fragment expression was induced and cell growth was dramati- cally inhibited 24 h later. However, the expresion of p53 was found to be increased after the induction of C-JNK fragment, evaluated by transfecting p21waf-luciferase reporter genes. Our further studies showed that C-JNK fragment could form complex with p53 both in vivo and in vitro. Induction of C-JNK fragment in vivo can increase p53 stability by inhibiting p53 ubiquitination.

Effect of Yiguanjian decoction on cell differentiation and proliferation in CCl_4-treated mice

AIM： To investigate the cellular mechanisms of action of Yiguanjian （YGJ） decoction in treatment of chronic hepatic injury. METHODS： One group of mice was irradiated, and received enhanced green fluorescent protein （EGFP）- positive bone marrow transplants followed by 13 wk of CCh injection and 6 wk of oral YGJ administration. A second group of Institute for Cancer Research mice was treated with 13 wk of CCI4 injection and 6 wk of oral YGJadministration. Liver function, histological changes in the liver, and Hyp content were analyzed. The expres- sion of m-smooth muscle actin （α-SMA）, F4/80, albumin （AIb）, EGFP, mitogen-activated protein kinase-2 （PKM2）, Ki-67, fetoprotein （AFP）, monocyte chemotaxis pro- tein-1 and CC chemokine receptor 2 were assayed. RESULTS： As hepatic damage progressed, EGFP-po- sitive marrow cells migrated into the liver and were mainly distributed along the fibrous septa. They showed a conspicuous coexpression of EGFP with ^-SMA and F4/80 but no coexpression with AIb. Moreover, the expression of PKM2, AFP and Ki-67 was enhanced dy- namically and steadily over the course of liver injury. YGJ abrogated the increases in the number of bone marrow-derived fibrogenic cells in the liver, inhibited expression of both progenitor and mature hepatocyte markers, and reduced fibrogenesis. CONCLUSION： YGJ decoction improves liver fibrosis by inhibiting the migration of bone marrow cells into the liver as well as inhibiting their differentiation and suppressing the proliferation of both progenitors and hepatocytes in the injured liver.

Down-regulation of HIV-1 Infection by Inhibition of the MAPK Signaling Pathway

The human immunodeficiency virus type 1 （HIV-1） can interact with and exploit the host cellular machinery to replicate and propagate itself. Numerous studies have shown that the Mitogen-activated protein kinase （MAPK） signal pathway can positively regulate the replication of HIV-1, but exactly how each MAPK pathway affects HIV-1 infection and replication is not understood. In this study, we used the Extracellular signal-regulated kinase （ERK） pathway inhibitor, PD98059, the Jun N-terminal kinase （JNK） pathway inhibitor, SP600125, and the p38 pathway inhibitor, SB203580, to investigate the roles of these pathways in HIV-1 replication. We found that application of PD98059 results in a strong VSV-G pseudotyped HIV-1NL4-3 luciferase reporter virus and HIV-1NL4-3 virus inhibition activity. In addition, SB203580 and SP600125 also elicited marked VSV-G pseudotyped HIV-INL4-3 luciferase reporter virus inhibition activity but no HIV-1NL4-3 virus inhibition activity. We also found that SB203580 and SP600125 can enhance the HIV-1 inhibition activity of PD98059 when cells were treated with all three MAPK pathway inhibitors in combination. Finally, we show that HIV-1 virus inhibition activity of the MAPK pathway inhibitors was the result of the negative regulation of HIV-1 LTR promoter activity.

Lentiviral vector-mediated down-regulation of IL-17A receptor in hepatic stellate cells results in decreased secretion of IL-6

AIM: To investigate the mechanism of interleukin (IL)-6 secretion through blocking the IL-17A/IL-17A recepto (IL-17RA) signaling pathway with a short hairpin RNA (shRNA) in hepatic stellate cells (HSCs) in vitro . METHODS: HSCs were derived from the livers of adul male Sprague-Dawley rats. IL-6 expression was evalu ated using real-time quantitative polymerase chain reaction and enzyme linked immunosorbent assay. The phosphorylation activity of p38 mitogen activated pro tein kinases (MAPK) and extracellular regulated pro tein kinases (ERK) 1/2 upon induction by IL-17A and suppression by IL-17RA shRNA were examined using Western blotting.RESULTS: IL-6 expression induced by IL-17A was significantly increased compared to control in HSCs (P < 0.01 in a dose-dependent manner). Suppression of IL17RA using lentiviral-mediated shRNA inhibited IL-6 expression induced by IL-17A compared to group with only IL-17A treatment (1.44 ± 0.17 vs 4.07 ± 0.43, P < 0.01). IL-17A induced rapid phosphorylation of p38 MAPK and ERK1/2 after 5 min exposure, and showed the strongest levels of phosphorylation of p38 MAPK and ERK1/2 at 15 min in IL-17A-treated HSCs. IL-6 mRNA expression induced by IL-17A (100 ng/mL) for 3 h exposure was inhibited by preincubation with specific inhibitors of p38 MAPK (SB-203580) and ERK1/2 (PD-98059) compared to groups without inhibitors preincubation (1.67 ± 0.24, 2.01 ± 0.10 vs 4.08 ± 0.59, P < 0.01). Moreover, lentiviral-mediated IL-17RA shRNA 1 inhibited IL-17A-induced IL-6 mRNA expression compared to random shRNA in HSCs (1.44 ± 0.17 vs 3.98 ± 0.68, P < 0.01). Lentiviral-mediated IL17RA shRNA 1 inhibited phosphorylation of p38 MAPK and ERK1/2 induced by 15 min IL-17A (100 ng/mL) exposure. CONCLUSION: Down-regulation of the IL-17RA receptor by shRNA decreased IL-6 expression induced by IL-17A via p38 MAPK and ERK1/2 phosphorylation in HSCs. Suppression of IL-17RA expression may be a strategy to reduce the inflammatory response induced by IL-17A in the liver.

FGF-receptor substrate 2 functions as a molecular sensor ntegrating external regulatory signals into the FGF pathway

Fibroblast growth factor （FGF） receptor substrate 2a （FRS2α） is the main mediator of signaling in the FGF pathway. Recent studies have shown that mitogen-activated protein kinase （MAPK） phosphorylates serine and threonine residues in FRS2, negatively affecting FGF-induced tyrosine phosphorylation （PY） of FRS2. Several kinds of stimuli can induce serine/threonine phosphorylation （PS/T） of FRS2, indicating that FRS2 may be useful for studying crosstalk between growth factor signaling pathways. Here, we report that FGF-induced PY of FRS2 can be attenuated by EGF co-stimulation in PC12cells; this inhibitory effect could be completely reversed by U0126, an inhibitor of MEK. We further identified the ERK1/2-binding motif in FRS2 and generated FRS2-3KL, a mutant lacking MAPK binding and PT upon FGF and/or EGF stimulation. Unlike wild-type （WT） FRS2, FGF-induced PY of FRS2-3KL could not be inhibited by EGF co-stimulation, and FRS2-3KL-expressing PC12 cells exhibited more differentiating potential than FRS2-WT-expressing cells in response to FGF treatment. These results suggest that PS/T of FRS2 mediated by the FRS2-MAPK negative regulatory loop may function as a molecular switch integrating negative regulatory signals from other pathways into FGFR-generated signal transduction.

Regulation of Hepatitis C Virus Replication and Gene Expression by the MAPK-ERK Pathway

The mitogen activated protein kinases-extracellular signal regulated kinases （MAPK-ERK） pathway is involved in regulation of multiple cellular processes including the cell cycle. In the present study using a Huh7 cell line Conl with an HCV replicon, we have shown that the MAPK-ERK pathway plays a significant role in the modulation of HCV replication and protein expression and might influence IFN-a signalling. Epithelial growth factor （EGF） was able to stimulate ERK activation and decreased HCV RNA load while a MAPK-ERK pathway inhibitor U0126 led to an elevated HCV RNA load and higher NS5A protein amounts in Conl cells. It could be further demonstrated that the inhibition of the MAPK-ERK pathway facilitated the translation directed by the HCV internal ribosome entry site. Consistently, a U0126 treatment enhanced activity of the HCV reporter replicon in transient transfeetion assays. Thus, the MAPK-ERK pathway plays an important role in the regulation of HCV gene expression and replication. In addition, cyclin-dependent kinases （CDKs） downstream of ERK may also be involved in the modulation of HCV replication since roscovitine, an inhibitor of CDKs had a similar effect to that of U0126. Modulation of the cell cycle progression by cell cycle inhibitor or RNAi resulted consistently in changes of HCV RNA levels. Further, the replication of HCV replicon in Conl cells was inhibited by IFN-~z. The inhibitory effect of IFN-CZ could be partly reversed by pre-incubation of Con-1 cells with inhibitors of the MAPK-ERK pathway and CDKs. It could be shown that the MAPK-ERK inhibitors are able to partially modulate the expression of interferon-stimulated genes.

Insights into erlotinib action in pancreatic cancer cells using a combined experimental and mathematical approach

AIM:To gain insights into the molecular action of erlotinib in pancreatic cancer (PC) cells. METHODS:Two PC cell lines, BxPC-3 and Capan-1, were treated with various concentrations of erlotinib, the specific mitogen-activated protein kinase kinase (MEK) inhibitor U0126, and protein kinase B (AKT) inhibitor XIV. DNA synthesis was measured by 5-bromo-2'-deoxyuridine (BrdU) assays. Expression and phosphorylation of the epidermal growth factor receptor (EGFR) and downstream signaling molecules were quantified by Western blot analysis. The data were processed to calibrate a mathematical model, based on ordinary differential equations, describing the EGFRmediated signal transduction. RESULTS:Erlotinib significantly inhibited BrdU incorporation in BxPC-3 cells at a concentration of 1 mol/L, whereas Capan-1 cells were much more resistant. In both cell lines, MEK inhibitor U0126 and erlotinib attenuated DNA synthesis in a cumulative manner, whereas the AKT pathway-specific inhibitor did not enhance the effects of erlotinib. While basal phosphorylation of EGFR and extracellular signal-regulated kinase (ERK) did not differ much between the two cell lines, BxPC-3 cells displayed a more than five-times higher basal phospho-AKT level than Capan-1 cells. Epidermal growth factor (EGF) at 10 ng/mL induced the phosphorylation of EGFR, AKT and ERK in both cell lines with similar kinetics. In BxPC-3 cells, higher levels of phospho-AKT and phospho-ERK (normalized to the total protein levels) were observed. Independent of the cell line, erlotinib efficiently inhibited phosphorylation of EGFR, AKT and ERK. The mathematical model successfully simulated the experimental findings and provided predictions regarding phosphoprotein levels that could be verified experimentally. CONCLUSION:Our data suggest basal AKT phosphorylation and the degree of EGF-induced activation of AKT and ERK as molecular determinants of erlotinib efficiency in PC cells.