凋亡抑制蛋白Survivin在骨肉瘤中的表达及其与PTEN、cyclinD1蛋白表达的关系

[目的]探讨Survivin基因的表达在骨肉瘤发生、发展中的作用及其与PTEN、cyclinD1蛋白表达的相互关系。[方法]应用免疫组化（SP）法检测40例骨肉瘤组织、20例骨软骨瘤组织中Survivin、PTEN、cyclinD1蛋白的表达情况以及Survivin与PTEN、cyclinD1蛋白两者之间的相关性。[结果]Survivin在骨肉瘤中的阳性率为62．5％（25／40），明显高于对照组骨软骨瘤10．0％（2／20）的阳性率（P〈0．01）。PTEN蛋白在骨肉瘤中的阳性表达率为52．5％（21／40），而在骨软骨瘤中为95．0％（19／20），两者相比有显著差异（P〈0．01）。cyclinD1蛋白在骨肉瘤中的阳性率为80．0％（32／40），高于在骨软骨瘤中的45．0％（9／20），有统计学意义（P〈0．05）。Survivin和PTEN两者表达强度之间呈显著负相关（P〈0．01），而Survivin与cyclinD1表达呈正相关（P〈0．01）。[结论]Survivin在骨肉瘤组织中过表达与骨肉瘤的发生有关；PTEN在骨肉瘤组织中失表达，它可能下调Survivin表达，对骨肉瘤起抑制作用：Survivin和cyclinD1在骨肉瘤的发生发展中可能起协同作用。     

丝裂原蛋白激酶信号转导通路在机械通气相关性肺损伤中的作用

目的观察机械通气介导肺损伤（VILI）过程中丝裂原蛋白激酶（MAPK）的活性变化以及对细胞因子的影响，从中探讨VILI发生机制和MAPK的作用。方法72只SD大鼠随机分为未处理的对照组（不行机械通气）、正常通气组、过度通气组和采用MAPK抑制剂SP600125（JNK）、SB203580（p38）、PD98059（ERK）分别预处理上述3组。机械通气4h后取大鼠肺组织采用Western blot方法测定各组的总JNK、ERK、p-38蛋白激酶的表达及其磷酸化水平变化。同时以酶联免疫吸附试验（EUSA）方法测定大鼠肺组织、支气管肺泡灌洗液（BALF）和血浆中的肿瘤坏死因子-α（TNF-α）、巨噬细胞炎性蛋白-2（MIP-2）浓度。结果正常和过度机械通气4h后均能激活JNK、ERK、p38激酶，但以过度通气组为著（P〈0．01）。过度通气组大鼠肺组织、BALF、血浆中的TNF-α、MIP-2含量显著高于其他组（P〈0．01）。JNK、ERK、p38抑制剂显著降低肺组织、BALF中的TNF-α、MIP-2含量（P〈0．05或0．01），且JNK和ERK抑制剂作用强于p38抑制剂。结论过度机械通气激活了肺细胞中的JNK、ERK、p38激酶，且JNK、ERK、p38参与了VILI细胞因子的产生，即MAPK信号转导通路的激活可能是VILI发生机制之一。     

他莫昔芬通过丝裂原活化蛋白激酶抑制前列腺癌细胞系PC3细胞增殖

他莫昔芬是选择性雌激素受体（ER）调节剂（SERM）。丝裂原活化蛋白激酶（MAPK）主要包括细胞外信号调节蛋白激酶（ERK1／2）、c-JunN端应力激活蛋白激酶（JNK）和p38丝裂原活化蛋白激酶（p38）。他莫昔芬（TAM）通过ER可以激活MAPK。本实验旨在研究MAPK信号转导通路在他莫昔芬抑制雄激素非依赖性前列腺癌细胞株PC3生长中的作用。[第一段]     

丝裂原活化蛋白激酶类和蛋白激酶C在转化生长因子β1诱导肾小管细胞结缔组织生长因子表达中的作用

目的了解转化生长因子β1（TGF-β1）诱导肾小管细胞结缔组织生长因子（CTGF）表达的机制，特别是蛋白激酶C（PKC）和丝裂原活化蛋白激酶（MAPK）在CTGF基因表达中的作用及其对Smad磷酸化的影响。方法分别应用PKC抑制剂G06850以及MAPK的3个组成成分ERK、JNK和p38MAPK的抑制剂PD98059、U0126、SP600125和SB203580阻断相应通路，观察其对TGF．131诱导的CTGF表达以及Smad2／Smad3磷酸化的影响。结果TGF-β1（5μg／L）以时间依赖方式诱导HK-2细胞中Smad2／Smad3的磷酸化，从基础值0．87±0．09上升至2h时高峰2．350±0.11。PKC抑制剂G06850（5μmol／L）和ERK抑制剂PD98059（10μmol／L）、U0126（10μmol／L）可部分抑制TGF-β1诱导的CTGF表达，而p38MAPK抑制剂SB203580（20μmol／L）和JNK抑制剂SP600125（10μmol／L）对TGF-β1诱导的CTGF的表达无影响。PKC抑制剂G06850（5μmol／L）可减少TGF-β1诱导的Smad2／Smad3磷酸化，而ERK抑制剂PD98059（10μmol／L）和U0126（10μmol／L）对Smad2／Smad3的磷酸化没有影响。结论在肾小管上皮细胞中，TGF-β1诱导CTGF的表达需要PKC和Ras／MEK／ERK的参与。PKC以Smad依赖的方式参与肾小管上皮细胞中TGF-β1诱导的CTGF的表达，而Ras／MEK／ERK对CTGF表达的调节不依赖于Smads。     

ras-MAPK信号通路在骨肉瘤中的表达及其意义

目的探讨骨肉瘤中ras—MAPK信号传导通路的相互关系，观察它们在骨肉瘤发生、发展中的作用。方法选取我科自2000年至2006年40例骨肉瘤手术标本，标本在切下后转入深低温保存。分别应用免疫组织化学和Westernblot检测在骨肉瘤和正常骨组织中的raS基因产物p21和MAPK信号通路标志蛋白p38的表达，并分析在ras p21不同表达的骨肉瘤组织中的p38的表达，探讨两者之间的相关性。结果免疫组织化学和蛋白检测结果显示，所有40例标本中ras p21、p38在骨肉瘤组织中的蛋白表达量与正常骨组织之间差异有统计学意义，骨肉瘤中的表达均明显高于正常骨（P〈0、05）；rasp21与p38的表达呈现明显的正相关：在ras p21含量较高的骨肉瘤组织中p38的含量较高，在ras p21含量较低的骨肉瘤组织中p38的含量较低（P〈0．05）。结论骨肉瘤中存在着ras—MAPK信号传导通路的表达，该传导通路的激活在骨肉瘤的发生、发展中起到一定作用。     

转化生长因子β1对肾小管上皮细胞中结缔组织生长因子基因启动子活性的影响

目的探讨转化生长因子[β1（TCF-β1）对人近端肾小管上皮细胞系HK-2中结缔组织生长因子（CTGF）基因启动子活性的调控作用，以及丝裂原激活蛋白激酶（MAPK）途径对该生长因子作用的影响。方法构建含有人类CTGF基因启动子的报告基因pCTGF-luc，将其瞬时转染HK-2细胞。通过检测荧光素酶的活性观察TGF-β1和MAPK途径抑制剂对CTGF基因启动子活性的影响。结果TGF-β1以剂量和时间依赖方式上调HK-2中CTGF基因启动子的活性。最佳刺激浓度是5ng／ml，最佳刺激时间为12h，荧光素酶相对活性分别为对照组的1．82倍和2．10倍（P〈0．05）。应用PD98059、SB203580和SP600125分别特异性抑制MAPK途径的胞外信号调节蛋白激酶（ERK）、蛋白激酶p38（p38MAPK）和c-Jun-氨基末端激酶（JNK）通路，对TGF-β1上调CTGF启动子活性的作用有不同影响。PD98059显著增加HK-2中pCTGF-luc的基础活性．并在一定浓度范围内（0．5～10μmol／L）促进TGF-β1的上调作用。SB203580对pCTGF-luc基础活性无影响，但以剂量依赖方式显著抑制TGF-β1的激活效应。而SP600125对基础状态和TGF-β1刺激下CTGF基因启动子活性无影响。结论TGF-β1以剂量和时间依赖方式上调HK-2中CTGF基因启动子活性，在转录水平调节CTGF表达。MAPK途径的ERK和p38MAPK通路可影响TGF-β1的这一调控作用。     

食管鳞状细胞癌EMMPRIN蛋白的表达及临床意义

目的 探讨食管鳞状细胞癌（ESCC）中细胞外基质金属蛋白酶诱导因子（EMMPRIN）蛋白的表达及临床意义。方法 免疫组织化学染色法检测85例ESCC、18例癌旁不典型增生（AH）、38例癌旁“正常”鳞状上皮（NSEBC）和15例正常食管鳞状上皮（NSE）中EMMPRIN蛋白的表达。结果ESCC、AH、NSEBC和NSE中EMMPRIN蛋白的阳性率分别为80％（68／85）、39％（7／18）、66％（25／38）和20％（3／15）；ESCC中EMMPRIN蛋白阳性率高于非癌肿组织（P＜0．01，r=0．35）且阳性细胞分布区域不同；高、中度分化组ESCC中EMMPRIN蛋白阳性率高于低分化组（P＜0．01，r=0．29）；ESCC中EMMPRIN蛋白的表达与肿瘤浸润食管壁的深度、临床分期和淋巴结转移均无明显相关（P＞0．05）。结论 EMMPRIN蛋白在ESCC组织的表达与在非癌肿组织的表达存在显著不同，且它与癌肿的组织分化程度有密切关系。     

甲基化CpG结合域蛋白1在胰腺癌组织中的表达和意义

目的：检测甲基化CpG结合域蛋白I（MBD1）蛋白在胰腺癌组织中的表达，并探讨其临床意义。方法：应用S-P免疫组织化学法检测38例胰腺癌、17例胰腺癌旁组织、8例胰腺良性肿瘤、3例慢性胰腺炎和6例正常胰腺组织中MBD1蛋白的表达。结果：MBD1在胰腺癌组织、正常胰腺组织、胰腺良性肿瘤、胰腺癌旁组织中的表达阳性率分别是76．32％（29/38）、16．67％（1／6）、25．0％（2／8）、29．41％（5／17），3例慢性胰腺炎标本中未见表达；胰腺癌阳性表达率明显高于正常胰腺、慢性炎症、良性肿瘤和癌旁对照组织（P〈0．05）。MBD1表达水平的高低与病人的性别、年龄、肿瘤部位、肿瘤大小、分化程度和TNM分期无显著性差异（P〉0．05）；而与淋巴结转移密切相关，有淋巴结转移者胰腺癌组织MBD1的表达阳性率为92．31％（24／26），高于无淋巴结转移者的41．67％（5／12）（P〈0．01）。结论：胰腺癌中MBD1呈高水平表达，并与胰腺癌的高转移侵袭活性有关，其机制可能与MBD1介导抑制多个甲基化相关抑癌基因的表达有关。MBD1的转录调控机制有待进一步研究。     

P-糖蛋白和p38在人肝癌组织中的表达及其意义

目的观察P-精蛋白和p38蛋白在人肝癌组织中的表达。方法应用免疫组织化学方法检测62例人中晚期肝癌及其癌旁正常黏膜中P-糖蛋白和有丝分裂原活化蛋白激酶（MAPK）家族成员p38的表达。结果P-糖蛋白和p38在中晚期肝癌中的表达高于早期癌和正常黏膜，差异有统计学意义（66．67％比33．33％；83．87％比16．13％，P〈0．05）。结论中晚期肝癌中P-糖蛋白和p38处于过度表达状态，参与肝癌的发生、发展和转移。     

热休克蛋白gp96在骨肉瘤组织中的表达及其临床意义

目的观察热休克蛋白gp96（HSPgp96）在人骨肉瘤组织中的表达。方法采用免疫组织化学SP法检测45例骨肉瘤组织，其中骨母细胞型24例，软骨母细胞型20例，纤维母细胞型1例，以及5例正常骨组织中HSPgp96的表达情况。结果HSPgp96在正常骨组织与骨肉瘤组织中的表达率分别为20％（1／5）及100％（45／45），平均阳性细胞率分别为0．48％和97．23％，两者差异有统计学意义（P〈0．01），在骨母细胞型、软骨母细胞型与纤维母细胞型中阳性表达率之间差异无统计学意义。HSPgp96在骨肉瘤中的表达与病理分级明显相关（P〈0．05），与临床分期无关（P〉0．05）。结论HSPgp96在人骨肉瘤组织中高表达，可作为判断恶性程度的重要指标以及肿瘤免疫的重要靶位。     

The effects of genistein on tyrosine protein kinase-mitogen activated protein kinase signal transduction pathway in hypertrophic scar fibroblasts

OBJECTIVE: To investigate the inhibitory effects of genistein on tyrosine protein kinase (TPK)-mitogen activated protein kinase (MAPK) signal transduction pathway in hypertrophic scar fibroblasts (HSFb), in order to explore the molecular mechanism of inhibition of scar hyperplasia by genistein. METHODS: HSFbs were isolated from human hypertrophic scar tissues and cultured in vitro. The cells were treated by genistein in different concentrations (25, 50, 100 micromol/L, respectively), followed by basic fibroblast growth factor (bFGF) stimulation. The activity of TPK was assessed with [gamma-32P] ATP substrate incorporation. The phosphorylation protein expression levels of main signal molecules in TPK-Ras-MAPK pathway including c-Raf, MEKl/2, extracellular signal regulated kinase (ERK), p38MAPK, c-Jun N-terminal kinase (JNK) were determined by Western blot. HSFbs treated with dimethylsulfoxid (DMSO) were used as control group. RESULTS: After being treated with genistein in concentration of 25, 50, 100 micromol/L, the activity of TPK in HSFbs was depressed significantly [(7.15 +/- 0.35) x 10(5), (5.62 +/- 0.88) x 10(5), (5.62 +/-0.88) x 10(5) 10(5) pmol x min(-1) x mg(-1), respectively] when compared with that in control group [(8.92 +/- 0.28) x 10(5) pmol x min(-1) x mg(-1), P < 0.05]. Compared with those in control group,the phosphorylation protein expression levels of c-Raf, MEK1/2, ERK1/2 and p38 MAPK were lowered in different degree (P < 0.05 or P < 0.01) after genistein treatment. The phospho-JNK levels after treatment with genistein were similar to that of control group. Under the condition of pretreatment with genistein, the activities of TPK and signal pathway protein expressions in HSFb showed a downward trend after stimulation with bFGF. CONCLUSION: Genistein can effect the proliferation and activation of HSFb by inhibiting the phosphorylation of receptor of TPK signal transduction pathway (TPK --> Raf --> MEK --> ERK/p38).     

肾病综合征氧化低密度脂蛋白脂质肾损伤的实验研究

目的 通过观察氧化低密度脂蛋白（oxidized low-density lipoprotein,ox-LDL）对系膜细胞（Mesangial Cells,MCs）分泌炎症介质功能的影响及MAPK信号通路和核因子-κB（nuclear factor kappa B,NF-κB）活性的改变,进一步阐明脂质在肾损伤中的作用机制.方法 利用ox-LDL诱导大鼠系膜细胞增殖,分别采用ELISA、real-time PCR、western blot技术检测MCs炎症介质、MAPK通路相关蛋白（p38、JNK、ERK）及NF-κB的表达水平.结果 利用ox-LDL诱导大鼠系膜细胞增殖并加入CXCR6受体后,其表面炎症因子[CXCL16、CD36、ADAM10、ADAM17、干扰素（IFN）、白细胞介素（IL6）、肿瘤坏死因子（TNF-α）]的表达水平以及MAPK信号通路（p38、JNK、ERK）、NF-κB的磷酸化水平显著升高（P〈0.01）.结论 ox-LDL可促使系膜细胞释放CXCL16、CD36、ADAM10、ADAM17、IFN、IL6、TNF-α等炎症介质,CXCR6可介导这一途径.ox-LDL激活MAPK信号转导通路,使p38、ERK1/2、SAPK/JNK的磷酸化水平升高,激活了NF-κB p65的活性,CXCR6-CXCL16介导MAPK信号途径.     

Mitogen-activated protein kinases signal inhibition of apoptosis in lipopolysaccharide-stimulated neutrophils.

BACKGROUND: Neutrophil (PMN) apoptosis is critical to the resolution of infection and the limitation of inflammation. Bacterial endotoxin (lipopolysaccharide [LPS]) inhibits PMN apoptosis and activates the p38 mitogen-activated protein kinase (MAPK) signal cascade. The role of p38 and other MAPKs (ERK and SAPK/JNK) in regulating PMN apoptosis after LPS stimulation is unknown. We hypothesize that MAPK activation by LPS signals inhibition of PMN apoptosis. METHODS: PMNs were isolated from the blood of healthy human volunteers and incubated with PD98059 (ERK inhibitor), SB203580 (p38 inhibitor), or 0.1% dimethyl sulfoxide (vehicle) for 1 hour before treatment with LPS (0, 10, or 1000 ng/mL). Neutrophil MAPK activation was determined by Western blot analysis for phosphorylated p38, ERK, and SAPK/JNK. Apoptosis was quantified by flow cytometry with use of propidium iodide and annexin V. RESULTS: LPS inhibited PMN apoptosis and activated p38 and ERK in a dose- and time-dependent fashion. SAPK/JNK was not activated by LPS. Treatment of cells with ERK inhibitor before LPS stimulation abrogated LPS signaled inhibition of PMN apoptosis. Conversely, p38 inhibition with SB203580 augmented inhibition of apoptosis by LPS. CONCLUSIONS: These data demonstrate opposing roles of MAPKs in mediating PMN apoptosis after LPS stimulation. We conclude that LPS signal transduction by ERK inhibits PMN apoptosis while activation of p38 promotes apoptosis.     

Arachidonic acid directly activates members of the mitogen-activated protein kinase superfamily in rabbit proximal tubule cells

BACKGROUND: To explore the roles of eicosanoids in arachidonic acid-induced mitogen-activated protein kinase (MAPK) signal transduction, we have shown that exposure of proximal tubular cells to arachidonic acid induces phosphorylation of c-Jun NH2-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK), two members of the MAPK superfamily. We observed that ketoconazole, an inhibitor of the cytochrome P450 pathway, blocked ERK but not JNK activation. METHODS: Direct regulation of arachidonic acid on mitogen-activated protein kinase (MAPK) signaling pathways was evaluated more directly by utilizing specific enzyme inhibitors of the cytochrome P450 metabolic pathway and by comparing the relative efficacy of arachidonic acid versus its cytochrome P450 metabolites (exogenous and endogenous), eicosatetraynoic acid (ETYA), and other fatty acids on the phosphorylation of members of the MAPK superfamily (ERKs, JNK, and p38(MAPK)), by utilizing early passage rabbit proximal tubular epithelial cells. RESULTS: Arachidonic acid activated p38(MAPK), a third member of the MAPK superfamily, in a time- and concentration-dependent manner. Studies designed to evaluate the ability of arachidonic acid and its cytochrome P450 metabolites (endogenously and exogenously) to stimulate ERKs, JNK, and p38(MAPK) found four conclusions. First, the metabolites of arachidonic acid generated endogenously by cytochrome P450 2C1 significantly augmented basal ERK activity, whereas the metabolites generated by the 2C2 isozyme significantly augmented basal p38(MAPK) activity. However, their effects were less profound than arachidonic acid itself. In contrast, there were no significant effects with transfection of either isozyme on basal JNK activity. Second, a variety of exogenous cytochrome P450 products were less potent than arachidonic acid on a molar basis in stimulating the activity of all three MAPKs. Third, ketoconazole and 17-octadecynoic acid, inhibitors of the cytochrome P450 pathway, as well as PPOH and DDMS, inhibitors of the epoxygenase and omega-hydroxylase pathways, respectively, failed to significantly reduce the effects of arachidonic acid to activate ERK and p38(MAPK) (JNK was not evaluated). Finally, arachidonic acid, its inactive analog ETYA, and other fatty acids with differing chain lengths and degrees of saturation stimulated the activity of all three MAPKs. CONCLUSIONS: These observations substantiate a role for arachidonic acid and other fatty acids in signaling linked to the MAPK superfamily in rabbit proximal tubular epithelium without the necessity of conversion to cytochrome P450 metabolites.     

Modulation of vascular smooth muscle cell alignment by cyclic strain is dependent on reactive oxygen species and P38 mitogen-activated protein kinase

PURPOSE: The aim of this study was to investigate the molecular targets of reactive oxygen species (ROS) and to determine whether cyclic strain induces smooth muscle cell (SMC) alignment via the ROS system. We assessed stretch-induced nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase activation and the redox sensitivity of cyclic strain-stimulated activation of the mitogen-activated protein kinase (MAPK) family. METHODS: SMCs were seeded on flexible collagen I-coated plates and exposed to cyclic strain. NAD(P)H oxidase activation was measured with lucigenin-enhanced chemiluminescent detection of superoxide. Activation of MAPK was detected by determining phosphorylation of extracellular signal-regulated protein kinase (ERK1/2), c-jun N-terminal kinase (JNK1/2), and p38 MAPK with immunoblotting. In other experiments, SMCs were exposed to diphenylene iodonium (DPI), an NAD(P)H inhibitor, 30 minutes before stretch. MAPK activation and cell orientation were then assessed. RESULTS: Cyclic strain elicits a rapid increase in intracellular NADH/NADPH oxidase in SMCs. There was also a rapid and robust phosphorylation of ERK1/2, JNK1/2, and p38 MAPK. Cyclic strain-induced intracellular NAD(P)H generation was almost completely blocked with DPI. DPI also inhibited the strain-induced phosphorylation of ERK1/2, JNK1/2, and p38 MAPK. Both the p38 MAPK specific inhibitor, SB 202190, and DPI blocked cyclic strain-induced cell alignment, but PD98059, an ERK1/2-specific inhibitor, and SP600125, an anthrazolone inhibitor of JNK, did not. CONCLUSION: Our results provide evidence that p38 MAPK is a critical component of the oxidant stress ROS-sensitive signaling pathway and plays a crucial role in vascular alignment induced by cyclic stain.     

细胞外信号调节激酶和p38丝裂原活化蛋白激酶的表达水平对人精子活动力的影响

目的:比较细胞外信号调节激酶(ERK)、P38丝裂原活化蛋白激酶(P38MAPK)的磷酸化和蛋白表达水平在正常精子和弱精子症患者精子中的差异,旨在探讨ERK和P38MAPK表达水平与精子活动力的相关性。方法:收集正常精液(精子浓度≥20×106/ml,a级精子≥25%或a+b级精子≥50%)和弱精子症患者精液(精子浓度≥20×106/ml,a级精子<25%或a+b级精子≤40%)各20份,洗涤后提取精子总蛋白,采用Western印迹方法分别检测ERK、P38MAPK的磷酸化和蛋白表达水平。结果:ERK和P38MAPK在正常精子和弱精子症患者精子中均有表达,ERK、P38MAPK蛋白表达水平和P38MAPK磷酸化水平在弱精子症患者组显著升高(P<0.05),而两组间ERK磷酸化水平差异无统计学意义(P>0.05)。结论:人精子ERK、P38MAPK蛋白表达水平和P38MAPK磷酸化水平升高可能是精子活动力低下的原因之一。     

Effects of insulin, contraction, and phorbol esters on mitogen-activated protein kinase signaling in skeletal muscle from lean and ob/ob mice

Effects of diverse stimuli, including insulin, muscle contraction, and phorbol 12-myristate-13-acetate (PMA), were determined on phosphorylation of mitogen-activated protein kinase (MAPK) signaling modules (c-Jun NH(2)-terminal kinase [JNK], p38 MAPK, and extracellular signal-related kinase [ERK1/2]) in skeletal muscle from lean and ob/ob mice. Insulin increased phosphorylation of JNK, p38 MAPK, and ERK1/2 in isolated extensor digitorum longus (EDL) and soleus muscle from lean mice in a time- and dose-dependent manner. Muscle contraction and PMA also elicited robust effects on these parallel MAPK modules. Insulin action on JNK, p38 MAPK, and ERK1/2 phosphorylation was significantly impaired in EDL and soleus muscle from ob/ob mice. In contrast, muscle contraction-mediated JNK, p38 MAPK, and ERK1/2 phosphorylation was preserved. PMA effects on phosphorylation of JNK and ERK1/2 were normal in ob/ob mice, whereas effects on p38 MAPK were abolished. In conclusion, insulin, contraction, and PMA activate MAPK signaling in skeletal muscle. Insulin-mediated responses on MAPK signaling are impaired in skeletal muscle from ob/ob mice, whereas the effect of contraction is generally well preserved. In addition, PMA-induced phosphorylation of JNK and ERK1/2 are preserved, whereas p38 MAPK pathways are impaired in skeletal muscle from ob/ob mice. Thus, appropriate MAPK responses can be elicited in insulin-resistant skeletal muscle via an insulin-independent mechanism.     

三羟基异黄酮对增生性瘢痕成纤维细胞受体型酪氨酸蛋白激酶-丝裂原活化蛋白激酶信号通路的影响

目的 了解5,7,4'-三羟基异黄酮(genistein)对增生性瘢痕成纤维细胞(HSFb)内受体型酪氨酸蛋白激酶-丝裂原活化蛋白激酶(TPK-MAPK)信号转导通路的影响,探讨genistein抑制瘢痕增生的分子机制. 方法体外分离培养HSFb,以不同浓度genistein(25、50、100μmol/L)处理细胞,再加入10 μg/L碱性成纤维细胞生长因子(bFGF)刺激,用[γ-32P]腺苷三磷酸底物掺入法检测细胞TPK活性;用蛋白质印迹法检测TPK-MAPK通路中主要信号蛋白分子c-Raf、丝裂原激活蛋白激酶激酶(MEK)、细胞外信号调节激酶(ERK)、p38 MAPK、c-Jun氨基末端激酶(JNK)磷酸化蛋白的表达变化.以二甲亚砜溶剂处理的HSFb为对照组. 结果 25、50、100μmol/L genistein作用后,HSFb内TPK活性分别为(7.15±0.35)、(5.62±0.88)、(3.17±0.94)×105 pmol·min-1·mg-1,与对照组(8.92±0.28)×105 pmol·min-1·mg-1比较,差异有统计学意义(P<0.05或P<0.01);细胞内磷酸化c-Raf、MEK1/2、ERK1/2、p38蛋白的含量均有不同程度降低,与对照组比较,差异有统计学意义(P<0.05或P<0.01).genistein各剂量组磷酸化JNK蛋白含量与对照组近似.在genistein预处理前提下,加入bFGF刺激的细胞内TPK活性及各信号蛋白的表达亦呈下降趋势. 结论 genistein可通过抑制细胞受体TPK信号转导途径影响HSFb的增殖与活化,主要信号通路可能为TPK→Raf→MEK→ERK/p38途径.     

p53 and mitogen‐activated protein kinase pathway protein profiles in fresh and frozen spermatozoa

Sperm or testicular tissue cryopreservation is performed in cases of male infertility as a treatment for the preservation of fertility. When these sperm cells are used in assisted reproductive techniques, fertilisation rates, developmental and implantation potential of embryos decrease and the abortion rates increase. In the present work, differences of both phosphorylation and expression levels of p53 and Mitogen‐activated protein kinases (MAPK) proteins were analysed in 61 individual sperm samples before and after cryopreservation. We observed that p53 protein residue at Ser 15 was phosphorylated after cryopreservation. Because MAPK pathway activations may be involved in p53 phosphorylation, MAPK/ERK, Stress‐activated protein kinases (SAPK)/JNK and p38MAPK proteins were also investigated. Analysis showed that p38MAPK phosphorylations increased significantly. However, ERK and JNK expressions and phosphorylations decreased, although the differences were not statistically significant. According to our results, it may be suggested that cryopreservation process activates p53 via p38 MAPK pathway that subsequently causes apoptosis, which may be related to sperm parameters.     

NMDA enhances stretching-induced differentiation of osteoblasts through the ERK1/2 signaling pathway

Activation of the excitatory neurotransmitter N-methyl-d-aspartate (NMDA) and stretching both increase Ca(2+) influx in osteoblastic cells. We postulated that NMDA would enhance the osteoblastic cell's response to stretching. The goal of this study was to investigate, in the presence of the neurotransmitter NMDA, the effect of mechanical loading on osteoblast's stage of differentiation and the mitogen-activated protein kinase (MAPK) signaling pathway associated with it. Rat primary osteoblastic cells were subjected to cyclic, equibiaxial stretch for 48 h in the presence or absence of NMDA. Pretreatment with 0.5 mM NMDA significantly enhanced the stretching magnitude-dependent increase in osteogenesis markers. MK801, an antagonist of NMDA receptors, abolished those responses. To further study the mechanism of this response, osteoblastic cells were stretched for 5, 15, or 60 min in the absence of NMDA. Cyclic stretch induced a rapid increase in extracellular signal-regulated kinase ERK1/2 phosphorylation with the peak at 15 min, but no changes were noted in p38 and JNK pathway signaling. NMDA could enhance ERK1/2 phosphorylation stimulated by stretching. U0126, an inhibitor of ERK1/2, blocked the increase in osteogenesis markers. In conclusion, the current study demonstrates that there is a synergistic effect between mechanical stimulation and NMDA in osteoblasts. ERK1/2 signaling may be the common pathway in the increased response to stretching in the presence of NMDA in osteoblastic cells.