尿酸诱导树突状细胞成熟的信号转导机制研究

目的: 观察树突状细胞(DCs)成熟过程中MAPKs和NF-κB信号分子表达情况,探讨尿酸刺激DCs成熟的分子机制。方法: 用尿酸体外刺激大鼠未成熟 DCs,在不同时点(0~45 min),免疫印迹方法检测p- p38、p-ERK1/2、p-JNK和NF-κB p65表达情况;以MAPKs和NF-κB信号分子抑制剂分别联合尿酸刺激DCs 48 h后,用流式细胞术检测表面分子CD83、CD86、IA/IE的表达;ELISA法测定IL-12 p70的水平。结果: (1)尿酸刺激后15 min,DCs p- p38、p-ERK1/2、p-JNK和NF-κB p65表达量明显增加,30 min时达到最大值;使用相应信号分子抑制剂后,相关蛋白表达均不能测出。(2)经p38、JNK、NF-κB p65等信号通路抑制剂预处理后,与单独尿酸刺激相比,DCs CD83、CD86、IA/IE等表面分子表达及IL-12 p70分泌水平均出现下降(P＜0.05或P<0.01),ERK1/2抑制剂预处理者,则出现表达上升(P＜0.05)。结论: 尿酸可以调节DCs p38、ERK1/2、JNK、 NF-κB等信号分子的活化,从而促进DCs表面分子表达及IL-12 p70分泌。这可能为尿酸能诱导DCs成熟及提高免疫功能的分子机制之一。     

The stress kinase mitogen-activated protein kinase kinase (MKK)7 is a negative regulator of antigen receptor and growth factor receptor-induced proliferation in hematopoietic cells

The dual specificity kinases mitogen-activated protein kinase (MAPK) kinase (MKK)7 and MKK4 are the only molecules known to directly activate the stress kinases stress-activated protein kinases (SAPKs)/c-Jun N-terminal kinases (JNKs) in response to environmental or mitogenic stimuli. To examine the physiological role of MKK7 in hematopoietic cells, we used a gene targeting strategy to mutate MKK7 in murine T and B cells and non-lymphoid mast cells. Loss of MKK7 in thymocytes and mature B cells results in hyperproliferation in response to growth factor and antigen receptor stimulation and increased thymic cellularity. Mutation of mkk7 in mast cells resulted in hyperproliferation in response to the cytokines interleukin (IL)-3 and stem cell factor (SCF). SAPK/JNK activation was completely abolished in the absence of MKK7, even though expression of MKK4 was strongly upregulated in mkk7(-/-) mast cell lines, and phosphorylation of MKK4 occurred normally in response to multiple stress stimuli. Loss of MKK7 did not affect activation of extracellular signal-regulated kinase (ERK)1/2 or p38 MAPK. mkk7(-/-) mast cells display reduced expression of JunB and the cell cycle inhibitor p16INK4a and upregulation of cyclinD1. Reexpression of p16INK4a in mkk7(-/-) mast cells abrogates the hyperproliferative response. Apoptotic responses to a variety of stimuli were not affected. Thus, MKK7 is an essential and specific regulator of stress-induced SAPK/JNK activation in mast cells and MKK7 negatively regulates growth factor and antigen receptor-driven proliferation in hematopoietic cells. These results indicate that the MKK7-regulated stress signaling pathway can function as negative regulator of cell growth in multiple hematopoietic lineages.     

SP600125对大鼠脑缺血再灌注神经元的保护作用

目的探讨SP600125-JNK特异性抑制剂对大鼠脑缺血再灌注神经元损伤的保护性作用及其作用机制。方法雄性SD大鼠54只,体重230～250g,随机分成假手术组（SH组）,缺血再灌注组（IR组）和JNK抑制剂SP600125组（SP组）,每组根据再灌注时间分为30min、24h和72h3个亚组,每亚组6只动物。采用4-VO法建立SD大鼠脑缺血模型,三组于缺血前30min侧脑室注射DMSO,DMSO及JNK抑制剂SP600125（溶媒采用DMSO）,容积均为10μl;脑缺血再灌注后30min、24h、72h免疫组织化学方法测定各时间点海马CA1区Bcl-2和Bax蛋白表达阳性细胞数量,TUNEL法检测CA1区凋亡细胞。结果缺血再灌注使海马CA1区Bcl-2和Bax阳性锥体细胞数目表达增加,再灌注24h阳性锥体细胞数目表达至高峰（P〈0.01）,再灌注24～72h可见阳性锥体细胞数目表达减少（P〈0.05）。其中SP组Bcl-2阳性锥体细胞数目显著多于IR组（P〈0.05）,而Bax阳性锥体细胞数目显著小于IR组（P〈0.05）。脑缺血再灌注后海马CA1区神经元存活数目SP组高于IR组（P〈0.01）,凋亡细胞数目低于IR组（P〈0.01）。结论 SP600125对大鼠脑缺血再灌注神经元损伤具有保护作用。     

C-jun氨基末端激酶(JNKs)与脑缺血性损伤

c-Jun氨基末端激酶（c-Jun N-terminal kinases,JNKs）为丝裂原活化蛋白激酶（mitogen activated protein kinase,MAPK）超家族之一,其参与胚胎发育、免疫反应、及细胞的生长、分化、增殖等多种生理过程,同时也参与了许多病理过程。近期研究表明其在脑缺血性损伤神经元死亡过程中起重要调控作用。现就其相关研究进展作一综述。     

Role of AMPK in pancreatic beta cell function

Pharmacological activation of AMP activated kinase (AMPK) by metformin has proven to be a beneficial therapeutic approach for the treatment of type II diabetes. Despite improved glucose regulation achieved by administration of small molecule activators of AMPK, the potential negative impact of enhanced AMPK activity on insulin secretion by the pancreatic beta cell is an important consideration. In this review, we discuss our current understanding of the role of AMPK in central functions of the pancreatic beta cell, including glucose-stimulated insulin secretion (GSIS), proliferation, and survival. In addition we discuss the controversy surrounding the role of AMPK in insulin secretion, underscoring the merits and caveats of methods used to date.     

5‐aminolevulinic acid induce apoptosis via NF‐κB/JNK pathway in human oral cancer Ca9–22 cells

J Oral Pathol Med (2010) 40 : 483–489 Background: 5‐aminolevulinic acid‐based photodynamic therapy (5‐ALA‐PDT) is being used to treat oral pre‐cancerous and cancerous lesions with some encouraging clinical outcomes. However, the exact mechanisms behind the photodynamic treatment are still not fully elucidated. Method: Flow cytometry, TdT‐mediated dUTP nick end labeling assay and Western blot analysis were used to investigate the effects of 5‐ALA‐PDT on human oral cancer Ca9–22 cells. Results: We found that 5‐ALA‐PDT induces apoptosis in Ca9–22 cells. Western blotting showed that 5‐ALA‐PDT activates both the caspase‐8 and caspase‐9 pathways, which differed from previous studies conducted in other cell types. Activation of JNK was evident as early as 30 min. The caspases activation was inhibited by JNK inhibitor SP600125. Treatment with NF‐κB inhibitor Bay 11‐7082 (Bay) completely abrogated ALA‐PDT‐induced JNK activation. In addition, Bay and SP600125 almost completely abolished ALA‐PDT‐induced apoptosis. Conclusion: These results demonstrate significant involvement of caspase‐8 and ‐9 and their upstream NF‐κB‐JNK pathways in ALA‐PDT‐induced apoptosis. Future studies on how NF‐κB and JNK activity regulate ALA‐PDT response should provide a better strategy for the treatment of oral cancer.     

小檗碱对胰岛素抵抗大鼠氧化应激和内质网应激的影响

目的观察小檗碱对胰岛素抵抗大鼠氧化/抗氧化状态和内质网应激(endoplasmic reticulum stress,ERstress)的影响,并探讨其改善胰岛素抵抗的分子机制。方法采用高脂高热卡饮食饲养8wk制备胰岛素抵抗大鼠模型,成模后随机分为小檗碱组(BER组)、Alpha-硫辛酸组(ALA组)和模型组(MOD组),各组以相应的药物干预4wk。另设正常组(NOR组),予普通饲料喂养,不予药物干预。比较各组大鼠空腹血糖(FBG)、空腹胰岛素水平(Fins)和胰岛素敏感性(ISI)。血清中丙二醛(MDA)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活性以观察药物对大鼠氧化和抗氧化的影响。Westernblot方法测定肝脏组织中的ER应激标志物c-Jun氨基端激酶(c-junNH2-terminal kinase,JNK)和Phospho-c-Jun(Ser73)(p-c-Jun)的含量变化。RT-PCR方法测定肝脏组织ER应激标志物葡萄糖调节蛋白GRP78(glucose regulated protein78,GRP78)mRNA表达水平,以观察小檗碱对胰岛素抵抗大鼠ER应激的影响。结果与NOR组比较,MOD组大鼠血清中MDA含量明显升高,SOD、GSH-Px活性明显降低(P均<0.05)。BER组大鼠SOD、GSH-Px的活性较MOD组明显升高(P<0.01,P<0.05),MDA含量较模型组明显下降。比较各组肝组织p-c-Jun/JNK的水平,MOD组较NOR组明显升高(P<0.01),BER组及ALA组较MOD组均明显下降(P均<0.01)。比较各组肝组织中GRP78mRNA水平,MOD组较NOR组明显升高(P<0.05),BER组及ALA组较MOD组均明显下降。结论小檗碱能提高胰岛素抵抗大鼠的胰岛素敏感性,增加其抗氧化能力,改善其ER应激状态,其作用机制可能与改善ER应激有关。     

JNK信号通路与神经退行性疾病

c-JunN端蛋白激酶(JNK)是细胞功能的重要激酶,在各种刺激以及生理状态下导致神经元凋亡中起着重要的作用。JNK主要与一些神经退行性疾病有着密切的关系。理解JNK信号通路能够为将来选择JNK作为靶点干预这些疾病条件。JNK参与这些神经退行性疾病的发病机制,因此抑制其活性成为有效治疗的靶点。     

金纳多对肾缺血/再灌注诱导的肾小管上皮细胞凋亡的影响

目的研究银杏叶提取物金纳多(Ginaton)注射液对大鼠肾脏缺血/再灌注(I/R)诱导的肾小管上皮细胞凋亡的保护作用及机制。方法采用双侧夹闭大鼠肾蒂缺血45min后再灌注20min、3、24h的方法制备动物模型。在预定时间点采用免疫印迹分析JNK及其底物c-Jun的激活和表达。TUNEL(原位末端标记法)及流式细胞术检测肾小管上皮细胞凋亡情况。结果肾脏缺血45min再灌注24h后肾小管上皮细胞凋亡明显增多,肾脏病理改变明显。肾脏缺血/再灌注20min时,JNK的磷酸化水平明显增加,缺血/再灌注3h,c-Jun的磷酸化水平明显增加。金纳多明显抑制了肾I/R诱导的JNK(vsI/R20min,P<0·05)和c-Jun(vsI/R3h,P<0·05)的磷酸化水平的增加。同时,金纳多明显减轻肾I/R诱导的肾小管上皮细胞凋亡(vsI/R24h,P<0·05),改善肾脏组织病理学改变。结论金纳多抑制肾I/R诱导的肾小管上皮细胞凋亡,保护缺血性肾损伤的作用,至少部分是通过抑制JNK通路的激活实现的。