p38/ATF-2通路参与C反应蛋白诱导的内皮细胞活化

目的:考察p38 MAPK/ATF-2通路在C反应蛋白(CRP)诱导的内皮细胞活化中的作用。方法:采用培养的人冠状动脉内皮细胞(HCAEC)第3~7代用于实验。CRP刺激诱导内皮细胞活化,给予p38抑制剂SB203580和SB202190干预。免疫印迹法检测p-e NOS、p-p38和p-ATF2的水平;ELISA法测定HCAEC分泌的黏附分子ICAM-1、VCAM-1和MCP-1的变化。结果:CRP呈浓度依赖性地抑制p-e NOS水平,CRP诱导HCAEC分泌ICAM-1、VCAM-1和MCP-1;CRP激活p38/ATF-2通路;SB203580和SB202190部分恢复p-e NOS水平和抑制CRP诱导的ICAM-1、VCAM-1和MCP-1分泌。结论:p38 MAPK/ATF-2通路参与CRP诱导的HCAEC活化。     

CP466722抑制HepG2细胞增殖并诱导细胞凋亡

目的:研究共济失调毛细血管扩张症突变蛋白(ATM)抑制剂CP466722对人肝细胞癌HepG2细胞增殖和凋亡的影响及其可能的分子机制。方法:MTT法检测CP466722对HepG2细胞活力的抑制作用,细胞集落形成实验观察CP466722对细胞增殖的影响,流式细胞术分析细胞周期的变化,TUNEL染色观察CP466722对细胞凋亡诱导作用,Western blotting检测细胞内蛋白的表达水平。结果:CP466722能够剂量依赖性地抑制HepG2细胞活力与细胞增殖;HepG2细胞经CP466722作用24 h后,细胞周期明显阻滞于G_2/M期,同时磷酸化细胞分裂周期蛋白2(p-Cdc2)、细胞分裂周期蛋白25 C(Cdc25C)和磷酸化Cdc25C(p-Cdc25C)的蛋白水平下降,而p27的蛋白表达则上调。较高浓度的CP466722诱导HepG2细胞发生凋亡,促进胱天蛋白酶3(caspase-3)和多腺苷二磷酸核糖聚合酶(PARP)的剪切。此外,CP466722抑制β-联蛋白(β-catenin)及其下游因子生存素(survivin)的表达,上调p38丝裂原活化蛋白激酶(p38 MAPK)的磷酸化水平。结论:CP466722抑制HepG2细胞增殖并诱导细胞发生凋亡,其机制可能与其抑制β-catenin信号途径和激活p38 MAPK相关。     

In situ demonstration of phosphorylated c-jun and p38 MAP kinase in epidermal keratinocytes following ultraviolet B irradiation of human skin

Ultraviolet B (UVB) irradiation is known to induce activation of cellular stress response pathways in cultured cells or intact human skin, as demonstrated by phosphorylation of MAP kinase family members and up- or down-stream targets, using biochemical assays. This study demonstrates by immunohistochemistry that low-dose UVB irradiation of normal human skin induces rapid and reversible phosphorylation of c-jun (a target of c-jun N-terminal kinase) and p38 mitogen activated protein kinase (p38 MAP kinase). Phosphorylation was maximal at 4-8 h and returned to normal levels at 48 h after irradiation. Nuclear localization of these phosphorylated substrates was found using antisera against the epitope containing the phosphorylated serine-73 of c-jun, and the dually phosphorylated epitope (threonine-180 and tyrosine-182) of p38 MAP kinase. Nearly all epidermal cells were positive for c-jun phosphorylation, whereas p38 phosphorylation was seen predominantly in the differentiated layers. In contrast to the massive activation of c-jun and p38, only a small population of the suprabasal cells showed nuclear translocation of nuclear factor kappa B (NFkappaB), and a few scattered cells became apoptotic, as determined by TUNEL (TdT mediated dUTP nick end labelling) staining. The expression of involucrin and skin-derived anti-leukoproteinase (SKALP)/elafin, two genes putatively under control of the c-jun and p38 pathways, was found to be increased. These findings establish the first cellular localization of UVB-induced protein phosphorylation of stress response proteins in human epidermis, thereby providing a link between cellular activation and gene expression in defined cell populations.     

消耗还原型谷胱甘肽抑制血管紧张素Ⅱ激活巨噬细胞c-Jun/ATF-2及NF-κB

目的:探讨还原型谷胱甘肽(GSH)在血管紧张素Ⅱ(AngⅡ)激活巨噬细胞转录因子c-Jun/ATF-2及NF-κB中的作用。方法:用荧光分光光度法测定细胞内GSH含量;用丁基硫堇硫氧胺(BSO)消耗细胞内GSH;用免疫印迹法测定细胞c-Jun/ATF-2磷酸化表达及NF-κBp65表达;用凝胶滞留法测定细胞NF-κB活性;用细胞免疫组化观察细胞c-Jun/ATF-2磷酸化表达的时间模式。结果:AngⅡ(1μmol/L)刺激30-60min可降低RAW264.7细胞内GSH;而后GSH逐渐适应性恢复。同时,AngⅡ刺激60min,呈剂量依赖性降低RAW264.7细胞内GSH。GSH特异性消耗剂BSO(0.5mmol/L)与RAW264.7细胞共同孵育18h,即可完全消耗细胞内GSH。AngⅡ(1μmol/L)可诱导RAW264.7巨噬细胞c-Jun/ATF-2磷酸化表达;BSO预先完全消耗细胞内GSH,AngⅡ(1μmol/L)不能诱导巨噬细胞c-Jun/ATF-2磷酸化。同样,AngⅡ(1μmol/L)可激活RAW264.7巨噬细胞NF-κB;BSO预先完全消耗细胞内GSH,AngⅡ(1μmol/L)不能激活巨噬细胞NF-κB。结论:还原型谷胱甘肽可能参与调控巨噬细胞转录因子c-Jun/ATF-2及NF-κB的转录活性。