蛋白酶活化受体(PARs)在肝纤维化中的调节作用

肝星状细胞(hepatic stellate cell,HSC)激活并转化为肌纤维母细胞并分泌细胞外基质 (ECM)成分是肝纤维化发生、发展的核心环节,肝损伤是引发肝纤维化的始动环节．蛋白酶激活受体(protease activated receptors, PARS)属于G蛋白偶联受体家族成员,他可通过介导细胞外信号调节激酶(extracellar signal- regulated kinase,ERK1／2)信号转导通路,引起细胞核反应,激活多种细胞转录因子,参与调节肝纤维化过程中HSC细胞增殖、分化和分泌大量细胞外基质,促使肝纤维化的发生和发展的方法,寻找通过抑制蛋白酶激活受体以期发现能阻断肝纤维化的形成和发展,逆转已形成的肝纤维化,将为肝纤维化的治疗提供新的理论基础．     

sp600125对乙醛刺激的HSC-T6细胞株的影响

肝星状细胞(HSC)的增殖与凋亡在肝纤维化的形成缮中起作十分重要的作用.乙醛刺激的HSC增殖是导致酒精性肝纤维化发生的关键因素 [1-2].丝裂原激活蛋白激酶(MAPK)包括细胞外调节蛋白激酶、c-Jun氨基末端激酶和p38,是HSC激活、增殖并导致肝纤维化发生的主要信号传导通路之一,其中,JNK信号传导通路参与了细胞增殖、分化以及凋亡的调控.我们既往对肝纤维化发病机制的研究结果证实,乙醛刺激的HSC中,p-JNK水平随JNK信号传导通路特异阻断剂sp600 125浓度增加而减少[3].     

实验性大鼠肝纤维化中Smad3蛋白和细胞外信号调节激酶1的表达

对大鼠纤维化肝组织中Smad3蛋白和细胞外信号调节激酶1(ERK1)的表达进行检测，初步探讨这两种信号分子在肝纤维化发生中的作用。     

sp600125对乙醛刺激的大鼠肝星状细胞增殖及bcl-2、c-myc蛋白表达的影响

肝星状细胞（HSC）的活化与增殖是肝纤维化发生的关键环节。乙醛刺激HSC活化与增殖，是导致酒精性肝纤维化发生的关键因素。研究表明，丝裂原活化蛋白激酶（MAPK），包括细胞外信号调节激酶（ERK）、JNK、P38是HSC活化与增殖导致肝纤维化发生的主要信号传导通路之一。乙醛刺激HSC中JNK磷酸化水平随sp600125（JNK信号传导通路特异性阻断剂）浓度增加而减少。本实验用sp600125处理乙醛刺激的HSC，观察sp600125对HSC增殖以及bcl-2、c-myc蛋白表达的影响，以探讨酒精性肝纤维化的发生机制。     

瘦素促进大鼠肝星状细胞活化及其细胞外信号调节激酶磷酸化

近年研究发现，瘦素在肝纤维化病理形成中具有重要意义，可促进实验性动物肝脏炎症与纤维化病理发展。但是瘦素是否直接促进肝纤维化形成的关键细胞——肝星状细胞（HSC）活化尚不清楚。本实验采用大鼠HSCT6细胞株，观察不同浓度的瘦素对HSC-T6增殖、α-平滑肌肌动蛋白（α-SMA）与Ⅰ型胶原蛋白表达的作用．及其对细胞外信号调节激酶（ERK）磷酸化的影响．探讨瘦素对HSC活化的影响与部分作用机制。     

转化生长因子-β信号通路与肝纤维化分子治疗研究进展

肝星状细胞（HSC）是肝纤维化发生的关键细胞，转化生长因子-β（TGF-β）在肝纤维化发生、发展过程中具有活化HSC、促进细胞外基质（ECM）合成和沉积等作用。TGF-β-Smad信号通路是TGF-β发挥生物学效应的主要通路，其分子组成和分子调节复杂，与其他信号通路存在广泛交互影响。深入研究TGF-β-Smad信号通路可进一步阐述肝纤维化的发病机制，为肝纤维化的防治提供新的有效途径。     

有丝分裂原活化蛋白激酶/细胞外调节信号激酶信号转导通路与肝纤维化逆转的相关性

近年发现，无论是消除致病因素或是应用有效抗纤维化药物，都可逆转患者及模型动物的肝纤维化。但具体机制尚不明确。南于有丝分裂原活化蛋白激酶（MAPK）／细胞外调节信号激酶（ERK）信号通路在多种损伤修复过程中发挥重要作用，我们在建立肝纤维化自发逆转动物模型的基础上，检测MAPK／ERK信号通路的活性，以揭示该通路与肝纤维化逆转的相关性。     

整合素与肝纤维化

整合素(integrin)是一类跨膜糖蛋白受体家族分子,主要介导细胞-细胞以及细胞-细胞外基质的粘附。细胞外基质-整合素-细胞骨架组成的焦点附着斑能激活粘附斑激酶,再通过Ras途径激活丝裂原活化蛋白激酶(Mitogen-activated protein kinase,MAPK),MAPK激活后通过调节基因表达等改变细胞行为,参与肝星状细胞(hepatic stellate cell,HSC)的增殖、收缩、粘附及迁移的调节。整合素在肝纤维化发生发展中的作用已成为当前研究的一个热点。     

细胞外信号调节激酶1与肝星状细胞增殖关系的体内实验研究

目的　探讨在纤维化发生中 ,细胞外信号调节激酶1(ERK1)与肝星状细胞 (HSCs)增殖的关系。方法　采用胆总管结扎 (BDL)方法建立大鼠肝纤维化模型 ,应用免疫组织化学及逆转录聚合酶链式反应 (RT PCR)技术研究ERK1及其mRNA在肝纤维化不同时期肝组织中的分布及含量的动态变化 ;采用免疫组织化学方法测定α SMA。结果　正常肝组织有少量α SMA、ERK1分布 ,随着肝纤维化发展 ,α SMA、ERK1阳性细胞明显增多 ;正常大鼠肝组织中有ERK1mRNA表达 ,分别于造模 2d开始上调 ,造模 4w表达最多。ERK1与α SMA呈显著正相关 (r =0 958,P <0 0 5)。结论　肝纤维化形成过程中ERK1及其mRNA表达明显增加 ,ERK1在HSCs增殖及肝纤维化形成过程中发挥重要作用     

整合素与肝纤维化

整合素(integrin)是一类跨膜糖蛋白受体家族分子，主要介导细胞-细胞以及细胞-细胞外墨质的粘附。细胞外基质-整合素-细胞骨架组成的焦点附着斑能激活粘附斑激酶，再通过Ras途径激活丝裂原活化蛋白激酶(Mitogen—activated protein kinase，MAPK)，MAPK激活后通过调节基因表达等改变细胞行为，参与肝星状细胞(hepatic stellate cell，HSC)的增殖、收缩、粘附及迁移的调节。整合素在肝纤维化发生发展中的作用已成为当前研究的一个热点。     

人纤维化肝组织中胞外信号调节激酶的表达

目的观察胞外信号调节激酶(ERK1)在人纤维化肝组织中的表达,探讨ERK1在肝纤维化发生中的作用机制。方法采用SABC免疫组化方法,对2001-01～2003-12华中科技大学附属同济医学院及广西壮族自治区人民医院外科手术切除的诊断明确的44例病理存档标本(其中包括12例正常肝组织、32例慢性乙型病毒性肝炎和肝硬化组织)中ERK1的表达及分布进行检测。结果免疫组化显示,ERK1主要表达于肝星状细胞(HSC)中。正常肝组织中,仅在汇管区少量非实质细胞中见ERK1弱阳性表达。在纤维化肝组织中,ERK1表达水平明显增强,与正常肝组织相比差异有显著性(P<0.01)。结论ERK激活促进了HSC活化增殖,参与了肝纤维化的发生发展过程。     

Essential role of Smad3 in angiotensin II-induced vascular fibrosis

Angiotensin II (Ang II) plays a pivotal role in vascular fibrosis, which leads to serious complications in hypertension and diabetes. However, the underlying signaling mechanisms are largely unclear. In hypertensive patients, we found that arteriosclerosis was associated with the activation of Smad2/3. This observation was further investigated in vitro by stimulating mouse primary aorta vascular smooth muscle cells (VSMCs) with Ang II. There were several novel findings. First, Ang II was able to activate an early Smad signaling pathway directly at 15 to 30 minutes. This was extracellular signal-regulated kinase 1/2 (ERK1/2) mitogen-activated protein kinase (MAPK) dependent but transforming growth factor-beta (TGF-beta) independent because Ang II-induced Smad signaling was blocked by addition of ERK1/2 inhibitor and by dominant-negative (DN) ERK1/2 but not by DN-TGF-beta receptor II (TbetaRII) or conditional deletion of TbetaRII. Second, Ang II was also able to activate the late Smad2/3 signaling pathway at 24 hours, which was TGF-beta dependent because it was blocked by the anti-TGF-beta antibody and DN-TbetaRII. Finally, activation of Smad3 but not Smad2 was a key and necessary mechanism of Ang II-induced vascular fibrosis because Ang II induced Smad3/4 promoter activities and collagen matrix expression was abolished in VSMCs null for Smad3 but not Smad2. Thus, we concluded that Ang II induces vascular fibrosis via both TGF-beta-dependent and ERK1/2 MAPK-dependent Smad signaling pathways. Activation of Smad3 but not Smad2 is a key mechanism by which Ang II mediates arteriosclerosis.     

Hydralazine may induce autoimmunity by inhibiting extracellular signal-regulated kinase pathway signaling

OBJECTIVE: To determine whether hydralazine might decrease DNA methyltransferase (DNMT) expression and induce autoimmunity by inhibiting extracellular signal-regulated kinase (ERK) pathway signaling. METHODS: The effect of hydralazine on DNMT was tested in vitro using enzyme inhibition studies, and in vivo by measuring messenger RNA (mRNA) levels and enzyme activity. Effects on ERK, c-Jun N-terminal kinase, and p38 pathway signaling were tested using immunoblotting. Murine T cells treated with hydralazine or an ERK pathway inhibitor were injected into mice and anti-DNA antibodies were measured by enzyme-linked immunosorbent assay. RESULTS: In vitro, hydralazine did not inhibit DNMT activity. Instead, hydralazine inhibited ERK pathway signaling, thereby decreasing DNMT1 and DNMT3a mRNA expression and DNMT enzyme activity similar to mitogen-activated protein kinase kinase (MEK) inhibitors. Inhibiting T cell ERK pathway signaling with an MEK inhibitor was sufficient to induce anti-double-stranded DNA antibodies in a murine model of drug-induced lupus, similar to the effect of hydralazine. CONCLUSION: Hydralazine reproduces the lupus ERK pathway signaling abnormality and its effects on DNMT expression, and inhibiting this pathway induces autoimmunity. Hydralazine-induced lupus could be caused in part by inducing the same ERK pathway signaling defect that occurs in idiopathic lupus.     

基于网络药理学探讨消癥活络方通过ERK5通路抗大鼠肝纤维化的机制

目的基于网络药理学方法探索消癥活络方(XZHLF)防治肝纤维化的作用机制。方法通过TCMSP数据库、化学专业数据库、ETCM数据库、化源网数据库、PubChem数据库以及文献查阅,收集XZHLF各中药化学成分,利用Swiss ADME数据库筛选出XZHLF各中药活性成分,利用Swiss Target Prediction数据库预测XZHLF各中药活性成分靶点;通过GeneCards、OMIN数据库收集肝纤维化疾病靶点,利用韦恩图获得XZHLF防治肝纤维化的潜在作用靶点。使用Cytoscape 3.7.1软件建立XZHLF“药物-活性成分”网络和XZHLF防治肝纤维化的“活性成分-潜在作用靶点”网络。在Metascape数据库对潜在作用靶点进行GO和KEGG富集分析,选取富集基因数最多的前20条绘制气泡图。对前20条KEGG通路中的MAPK信号通路进行分析,绘制“活性成分-潜在作用靶点-通路”网络图。将健康的SD大鼠随机分为6组,分别为空白对照组(K组)、模型组(M组)、秋水仙碱阳性对照组(Y组)、XZHLF高(G组)、中(Z组)、低(D组)剂量组,利用CCl4诱导大鼠肝纤维化进行造模,造模同时给药,共8周。通过Western Blot法检测各组大鼠肝组织内ERK5、p-ERK5、MEK5、MEKK3蛋白的相对含量和表达情况。计量资料多组间比较采用单因素方差分析,进一步两两比较采用LSD-t检验。结果从XZHLF中筛选出110个活性成分,作用于923个活性成分靶点,与6823个肝纤维化疾病靶点相映射得到潜在作用靶点647个。XZHLF可能通过MAPK信号通路等通路,通过MAPK级联反应的调控等生物过程,作用于EGFR、AKT1、IKBKB、MAPK8、PDGFRB等多个蛋白靶点,从而发挥防治肝纤维化的作用。M组的大鼠肝组织内ERK5、p-ERK5、MEK5和MEKK3蛋白水平较K、Y、G、Z、D组明显增加,差异均有统计学意(P值均<0.05);K组的大鼠肝组织内ERK5、p-ERK5、MEK5和MEKK3蛋白水平较Y、G、Z、D组明显减少,差异均有统计学意义(P值均<0.05)。结论基于网络药理学的方法预测出XZHLF可能通过MAPK信号通路防治肝纤维化,通过实验验证XZHLF是通过MAPK信号通路家族中ERK5通路抗肝纤维化。XZHLF高剂量组的抗肝纤维化作用效果最为明显。     

Differential expression genes analyzed by cDNA array in the regulation of rat hepatic fibrogenesis.

PURPOSE: To analyze the gene expression pattern in rat hepatic fibrogenesis and further assess the role of some key genes during the pathological process. METHODS: Hepatic fibrosis was induced by intraperitoneal injection of dimethylnitrosamine or carbon tetrachloride (CCl(4)) injection subcutaneously in rats, and identification of the hepatic fibrosis related genes with cDNA microarray was performed. After some key genes up-regulated during the development of hepatic fibrosis were screened and confirmed, their effects on the function of the activated rat hepatic stellate cells (HSC) were assessed using the small interfering RNA (siRNA) technique. RESULTS: Using an Atlas rat cDNA array, a number of differentially expressed genes in fibrotic liver tissues were identified compared with non-diseased control. A total of 15 genes predominantly associated with the mitogen-activated protein kinase (MAPK) signal transduction pathway were upregulated in the fibrotic liver. Immunohistochemical study revealed that the expressions of both extracellular signal-regulated kinases (ERK) and ribosomal protein S6 kinase (RSK), two of the key genes in the MAPK pathway, were remarkably induced, which was closely correlated to that of collagen types I and III during the development of hepatic fibrosis. Transfection of siRNA targeting ERK1 mRNA (siERK1) into HSC led to a 66% and 72% reduction of ERK1 mRNA and protein expression, respectively. Furthermore, siERK1 exerted the inhibition of the proliferation of HSC, accompanied by the induction of HSC apoptosis and reduction of collagen types I and III. In addition, siERK1 abolished the effect of platelet-derived growth factor-BB on the proliferation of HSC. CONCLUSIONS: The present study provided strong evidence for the participation of the MAPK pathway in the pathogenesis of hepatic fibrosis. Selective targeting of ERK1 inhibitors to HSC might present as a novel strategy for the treatment of hepatic fibrosis.     

Cell signaling in oxidative stress-induced liver injury

Oxidative stress is a common mechanism of liver injury. Recent investigations have demonstrated that oxidant-induced liver injury is mediated by the direct effects of reactive oxygen species on signal transduction pathways. Although the function of cell signaling in this form of injury is complex and likely variable depending on the type and duration of oxidative stress, common regulatory pathways of hepatocyte oxidant injury have been identified that include the mitogen-activated protein kinases extracellular signal-regulated kinase 1/2 (ERK1/2) c-Jun N-terminal kinase (JNK), and the nuclear factor kappaB (NF-kappaB) pathway. Studies in cultured hepatocyte and rodent models of oxidative stress have demonstrated that ERK1/2 typically induces resistance to oxidant stress, whereas JNK promotes cell death. The effects of NF-kappaB activation are more complex and cell-type specific. A further understanding of the signaling pathways that regulate oxidant-induced liver injury may suggest new therapies for hepatic diseases resulting from oxidative stress.     

Role of MAP kinases and their cross-talk in TGF-beta1-induced apoptosis in FaO rat hepatoma cell line

Transforming growth factor (TGF) beta1 is a potent inducer of apoptosis in the liver. During TGF-beta1-induced apoptosis, 3 mitogen-activated protein (MAP) kinases (extracellular signal-regulated kinase [ERK], c-Jun N-terminal kinase [JNK], and p38 kinase) showed simultaneously sustained activation in FaO rat hepatoma cells. TGF-beta1-induced apoptosis was markedly enhanced when ERK activation was selectively inhibited by the mitogen-activated protein kinase/extracellular signal-regulated kinase kinase inhibitor PD98059. In contrast, both interfering with p38 activity by overexpression of the dominant negative (DN) MKK6 mutant and inhibition of the JNK pathway by overexpression of the DN SEK1 mutant resulted in suppression of mitochondrial cytochrome c release, abrogating TGF-beta1-induced apoptosis. In addition, antiapoptotic Bcl-2 blocked mitochondrial cytochrome c release, suppressing TGF-beta1-induced activation of JNK and p38. Inhibition of ERK activity enhanced TGF-beta1-induced p38 and JNK activation. However, inhibition of the JNK pathway suppressed p38 but induced transient ERK activation. Similarly, interfering with the p38 pathway also attenuated JNK activation but generated transient ERK activation in response to TGF-beta1. These results indicate that disrupting one MAP kinase pathway affects the TGF-beta1-induced activation of other MAP kinases, suggesting cross-talk among MAP kinase pathways. In conclusion, we propose that the balance and integration of MAP kinase signaling may regulate commitment to TGF-beta1-induced apoptosis modulating the release of cytochrome c from mitochondria.     

Induction of c-fos and c-jun messenger ribonucleic acid expression by prostaglandin F2alpha is mediated by a protein kinase C-dependent extracellular signal-regulated kinase mitogen-activated protein kinase pathway in bovine luteal cells

PGF2alpha triggers the demise of the corpus luteum whereby progesterone synthesis is inhibited, the luteal structure regresses, and the estrus cycle resumes. Upon binding to its heterotrimeric G-protein-coupled receptors, PGF2alpha initiates the phospholipase C/diacylglycerol and inositol-1,4,5-trisphosphate/Ca(2+)-protein kinase C (PKC) signaling pathway. More recently, we have demonstrated that PGF2alpha activates extracellular signal-regulated kinase (ERK) mitogen-activated protein (MAP) kinase signaling through a Raf-dependent mechanism in bovine luteal cells. However, the relationship between PKC and ERK activation in PGF2alpha signaling has not been clearly defined. Moreover, the signaling pathway that PGF2alpha uses to regulate gene expression is unknown. In this report, primary cultures of bovine luteal cells were used to address the role of PKC in ERK activation and the signaling pathway for induction of c-fos and c-jun messenger RNA (mRNA) expression in response to PGF2alpha. By using a PKC inhibitor and a PKC-deficient luteal cell model, we observed that phorbol ester-responsive isoforms of PKC were required for ERK phosphorylation and activation by PGF2alpha (1 microM) or phorbol 12-myristate 13-acetate (PMA) (20 nM). In PGF2alpha- and PMA-treated cells, active ERK MAP kinase was localized in the nucleus. PGF2alpha-induced ERK phosphorylation was dose-dependently inhibited by the MEK1 inhibitor PD098059 (1-50 microM). The expression of c-fos and c-jun mRNA in luteal cells was markedly increased by treatment with PGF2alpha (1 microM) or PMA (20 nM) for 30 min. We also observed that activation of ERK MAP kinase was required for the expression of c-fos and c-jun mRNA in response to PGF2alpha and PMA because it was abrogated by blocking the ERK pathway with PD098059. In addition, PGF2alpha and PMA-induced c-fos and c-jun mRNA expression was abolished in the PKC-deficient cells. Taken together, our data demonstrate that a PKC-dependent ERK MAP kinase pathway mediates the expression of c-fos and c-jun mRNA in PGF2alpha-treated bovine luteal cells.     

和络舒肝胶囊对大鼠肝星状细胞丝裂原活化蛋白激酶的影响

目的:研究激活的肝星状细胞(HSC)丝裂原活化蛋白激酶(MAPKs)通路中ERK、JNK的活化情况,并探讨和络舒肝胶囊抗肝纤维化的作用机制。方法:用SD大鼠制备肝纤维化模型。造模成功后,药物组大鼠以每天1g/kg的和络舒肝胶囊,分两次灌胃;对照组大鼠灌以等体积生理盐水。连续灌胃30天后,下腔静脉取血离心并分离血清。采用盲法,用上述10%药物血清培养活化的HSCs24小时后,用Western blot方法检测各组HSCs磷酸化细胞外信号调节蛋白激酶(P-ERK)、磷酸化氨基末端蛋白激酶(P-JNK)蛋白表达水平。结果:肝纤维化大鼠经和络舒肝胶囊药物血清干预后(D组),P-ERK、P-JNK蛋白表达水平较肝纤维化模型组(C组)显著降低(P0.05);正常大鼠经和络舒肝胶囊药物血清干预后(B组)P-ERK、J-JNK蛋白表达水平与正常大鼠对照组(A组)相比也显著减少(P0.05)。结论:和络舒肝胶囊通过对活化的HSCsP-ERK和P-JNK表达的影响,阻断MAPK信号通路,抑制HSC分裂和增殖,可能是其抗肝纤维化的重要途径之一。