Activation of p^(38) mitogen activated protein kinase induced by lipopolysaccharide and its role in TNF a gene expression

Objective: To study the molecular mechanisms of TNF--a expression induced by lipopolysaccharide (LPS) for exploring novel methods to prevent or treat clinical patients with endotoxic shock. Methods:Protein kinase assay was used to detect the kinase activity stimulated by LPS; Con focal laser scan technique was used to show the translocation of p38 on the activation; RT PCR and reporter gene system were used to study the molecular mechanism of TNF -a gene transcription. Results: In RAW cells it was found that p38 was activated on the stimulation of LPS. and activated p38 moved into nucleus from cytosol; TNF--a mRNA increased on the stimulation of LPS and the increased promoter transactivity induced by LPS could be inhibited significantly by specific inhibitor for p38. Conclusion: p38 mitogen activated protein kinase (MAPK ) was activated by the stimulation of LPS,which brought about its entry to the nucleus to act on transcription factors to regulate cellular processes. p38 MAPK Is an important regulator of TNF--a gene expression induced by LPS.

Differential activation of mitogen-activated protein kinases by γ-irradi-ation in IEC-6 cells: Role of intracellular Ca^(2+)

Objective: To explore the effects of γ-irradiation on mitogen-activated protein kinases (MAPKs) and role of intracellular calcium in this event in intestinal epithelial cell line 6 (IEC-6 cells). Methods: After cultured rat IIEC-6 cells with or without the pretreatment of intracellular Ca2+ chelator were exposed to Y-ir-radiation of 6 Gy, the total and phosphorylated MAPKs in the cells were determined with Western blotting and apoptosis was examined with flow cytometry. Activities of Extracellular signal-regulated protein kinase (ERK) and p38 MAPK were determined by using immuoprecipitation followed by Western blotting. Results: In response to γ-irradiation, phosphorylation of ERK was not significantly observed, while the levels of phosphorylated c-Jun NH2-terminal kinase (JNK) and p38 MAPK were increased in 30 min and reached the peak 2 h after exposure to 6 Gy γ-irradiation, though the cell viability was significantly lowered 12 h. On the other hand, no obvious changes were seen in the total protein levels of ERK, JNK and p38 MAPK. Chelation of intracellular Ca2+ almost completely suppressed the JNK and p38 MAPK phosphorylation induced by γ-irradia-tion, but removal of external Ca2+ had no such effect. Activation of p38 MAPK, but not of ERK, was seen to have a correlation with γ-irradiation induced apoptosis. Conclusion: The results suggest that γ-irradiation is a potent activator for JNK and p38 MAPK, and Ca2+ mobilized from intracellular stores plays an important role in the activation of MAPKs and the induction of apoptosis in IEC-6 cells.

Inflammation-and stress-related signaling pathways in hepatocarcinogenesis

It has been established that cancer can be promoted and exacerbated by inflammation.Hepatocellular carcinoma(HCC) is the fifth most common cancer worldwide,and its long-term prognosis remains poor.Although HCC is a complex and heterogeneous tumor with several genomic mutations,it usually develops in the context of chronic liver damage and inflammation,suggesting that understanding the mechanism(s) of inflammation-mediated hepatocarcinogenesis is essential for the treatment and prevention of HCC.Chronic liver damage induces a persistent cycle of necroinflammation and hepatocyte regeneration,resulting in genetic mutations in hepatocytes and expansion of initiated cells,eventually leading to HCC development.Recently,several inflammation-and stress-related signaling pathways have been identified as key players in these processes,which include the nuclear factor B,signal transducer and activator of transcription,and stress-activated mitogen-activated protein kinase pathways.Although these pathways may suggest potential therapeutic targets,they have a wide range of functions and complex crosstalk occurs among them.This review focuses on recent advances in our understanding of the roles of these signaling pathways in hepatocarcinogenesis.

淋巴瘤细胞膜P糖蛋白、信号转导与转录激活因子3及bcl-2表达水平与化疗耐药的相关性

目的探讨淋巴瘤细胞膜P糖蛋白（P—gP）、细胞胞内信号转导与转录激活因子3（STAT3）、bcl-2、白细胞介素（IL）-6及IL-10表达水平与淋巴瘤患者化疗耐药的相关性。方法对疑诊淋巴瘤的18例患者，手术活检淋巴结，应用流式细胞术（FCM）测定细胞膜P—gP、胞内STAT3、抗凋亡蛋白bcl-2、细胞因子IL-6及IL-10表达水平，前瞻性研究与化疗疗效的关系。其中，化疗耐药组10例，化疗敏感组8例，以10例炎性淋巴结增生为正常对照。结果化疗耐药组P—gP和bcl-2表达水平均高于化疗敏感组（P=0．01和P=0．039），而STAT3、IL-6及IL-10表达水平差异无统计学意义（P〉0．05）。淋巴瘤细胞膜P—gP表达水平高于炎性淋巴结增生（P=0．01），STAT3表达水平明显低于炎性淋巴结增生（P=0．04），淋巴瘤与炎性淋巴结增生bcl-2、IL-6及IL-10表达水平差异无统计学意义（P〉0．05）。结论bcl-2、P—gP表达水平的高低与恶性淋巴瘤化疗疗效密切相关，STAT3参与了淋巴瘤细胞的信号转导，是否参与了多药耐药信号转导尚不能肯定，而胞内IL-6、IL-10的表达与化疗疗效未见相关。

有氧运动与饮食干预对肥胖小鼠睾丸氧化应激的影响

目的:通过对肥胖小鼠施加有氧运动与饮食干预,探索运动与饮食干预对肥胖小鼠睾丸氧化应激和p38MAPK-NF-κB通路中的作用。方法:随机将17只C57BL/6J小鼠分为正常饮食组(ND),37只分为高脂饮食组(HFD),高脂饮食脂肪占比40%,喂养12周后,HFD组剔除3只肥胖抵抗小鼠,其余34只肥胖造模成功;随后将ND组分为正常饮食对照组(NC,n=8),正常饮食运动组(NE,n=9),肥胖高脂饮食对照组(OC,n=8),肥胖高脂饮食运动组(OE,n=9),肥胖正常饮食组(ONC,n=8),肥胖正常饮食运动组(ONE,n=9),各组继续饲养8周,其中NE、OE和ONE组以速度20 m/min,60 min/d,6 d/week,进行8周跑台运动,末次运动后36~40 h取血和睾丸组织,ELISA检测血清睾酮和睾丸氧化应激(MDA、T-SOD、T-AOC)水平,RT-PCR和Western blot检测睾丸p38MAPK-NF-κB水平。结果:与NC组比较,OC组小鼠体脂参数、睾丸MDA和睾丸p38MAPK-NF-κB mRNA和蛋白水平明显升高(P<0.01),睾丸SOD、睾丸系数和血睾酮明显降低(P<0.01);NE组小鼠体脂参数明显降低(P<0.05),血清睾酮明显升高(P<0.01)。与OC组比较,OE组小鼠体脂参数、睾丸MDA和睾丸p38MAPK-NF-κB mRNA和蛋白水平明显降低(P<0.05或0.01),睾丸SOD和血睾酮水平明显升高(P<0.01);ONC组小鼠体脂参数、睾丸MDA和睾丸p38MAPK-NF-κB mRNA和蛋白水平明显降低(P<0.01),睾丸SOD水平和睾丸系数明显升高(P<0.05);ONE组小鼠体脂参数、睾丸MDA和睾丸p38MAPK-NF-κB mRNA和蛋白水平明显降低(P<0.01),睾丸SOD、睾丸系数和血睾酮水平明显升高(P<0.01)。结论:肥胖引起小鼠睾丸发生氧化应激,上调睾丸p38MAPK-NF-κB水平,并降低血睾酮水平;运动、饮食和运动×饮食干预均能通过降低体脂,改善睾丸氧化应激,下调睾丸p38MAPK-NF-κB水平。

黄芪对肝纤维化大鼠肝损伤保护作用及机制研究

目的:研究黄芪对肝纤维化大鼠肝损伤的保护作用及相关机制。方法:将SD大鼠随机分为正常对照组、肝纤维化模型组、黄芪后处理组和阳性对照组,检测各组大鼠血清中ALT、AST活性和TBIL水平变化;逆转录-聚合酶链反应检测各组大鼠肝脏组织5种主要致纤维化因子p38MAPK、TGF-β1、α-SMA、CTGF和CollegenⅣmRNA表达水平;免疫印迹法检测p38MAPK信号通路上下游蛋白MKK3和ATF-2的表达变化。结果:与肝纤维化模型组比较,黄芪后处理组大鼠血清中ALT、AST和TBIL水平明显降低(P<0.05),肝纤维病理变化明显减轻,p38MAPK、MKK3和ATF-2蛋白表达量均降低(P<0.05)。结论:黄芪通过p38MAPK信号通路对实验性肝纤维化大鼠肝损伤具有效的保护作用。

中医药调控氧化应激相关信号通路防治支气管哮喘研究进展

支气管哮喘(简称哮喘)是一种临床常见的呼吸系统疾病,以气道出现慢性炎症反应为主要特征,发病机制繁杂,治疗周期漫长,缠绵难愈,且无特效药。氧化应激是哮喘发病机制研究中的新热点,也是其治疗的潜在关键靶标。生理状况下,体内氧化与抗氧化系统处于动态平衡,两者相互拮抗共同维持机体正常生命活动。哮喘发病阶段,活性氧(ROS)、丙二醛(MDA)、一氧化氮(NO)等氧化产物过量产生,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽(GSH)等抗氧化剂含量降低,氧化程度超出氧化物的清除,使氧化应激水平大幅提高。另外,ROS的过量生成,会激活氧化应激相关信号通路,产生促炎因子,加剧炎症反应。从而导致哮喘患者肺部和气道组织损伤。近年来,中医药在哮喘治疗中的优势得到国内外专家学者的关注,尤其在调节氧化还原平衡缓解哮喘患者氧化应激、减少炎症反应等方面已取得显著成效。中医药一方面通过抑制丝裂原活化蛋白激酶(MAPK)、核转录因子-κB(NF-κB)相关信号通路,从源头上降低氧化产物和促炎因子的含量;另一方面通过激活核因子E2相关因子2(Nrf2)相关信号通路,上调抗氧化酶的水平,增强抗氧化系统以中和过量堆积的氧化产物。因此,以中医药调节氧化平衡状态作为诊疗思路,可能是未来防治哮喘的新手段、新方向。该文章对氧化应激相关通路参与哮喘发病机制进行系统阐述,同时对中药提取物、中药复方调控氧化应激相关通路治疗哮喘的最新研究进行梳理,以期为中医药防治哮喘临床和基础研究的开展提供更充分、更坚实、更科学的理论依据。