藏红花素对大鼠缺氧心肌的保护作用及其机制研究

目的:研究藏红花素(Crocin)对大鼠缺氧损伤心肌细胞的保护作用及其机制.方法:采用原代培养SD大鼠心肌细胞,应用氯化钴(CoCl2)方法建立心肌细胞缺氧损伤实验模型.研究分为两部分,(1)实验分组(各组样品数η=6):空白对照组、CoCl2组(CoCl2 250 μ mol/L)、不同浓度藏红花素[10(-7~ -3)mol/L]+ CoCl2组和阳性对照组(丹参酮ⅡA 磺酸钠组).采用细胞活力和细胞毒性检测法测定不同浓度藏红花素对缺氧心肌细胞活力影响.应用生物化学方法测定心肌细胞超氧化物歧化酶活性和丙二:醛含量变化.(2)实验分组(各组样品数η=3):实验对照组,缺氧组(CoCl2 250 μ mol/L)、藏红花素(10-5 mol/L)组和藏红花素(10-5 mol/L)+ 缺氧细胞组.应用蛋白质印迹法和逆转录聚合酶链式反应检测心肌细胞缺氧诱导因子-1α、血管内皮生长因子、脯氨酰羟化酶1、2、3(PHD 1、2、3)蛋白和mRNA表达的变化.结果:①藏红花素10-5 moL/L+ CoCl2组与CoCl2组比较,心肌细胞活力增强(P<0.01),缺氧心肌细胞超氧化物歧化酶活性提高(P<0.01),丙二醛的含量降低(P<0.01).②藏红花素(10-5 mol/L) +缺氧细胞组与缺氧组比较,缺氧诱导因子-1α及其下游靶基因血管内皮生长因子蛋白表达均增高(P<0.01).③藏红花素(10-5 mol/L)+缺氧细胞组心肌细胞PHD2蛋白和mRNA表达较缺氧组均明显增加(P均<0.01),PHD3 蛋白和mRNA表达则均明显减少(P均<0.01),差异均有统计学意义.结论:藏红花素对缺氧损伤心肌细胞具有明显的保护作用,其作用机制与藏红花素激活缺氧诱导因子-1 介导的低氧反应通路有关,PHDs可能参与了该反应的病理生理调控过程.     

PHDs-HIFs-pVHL 通路在类风湿关节炎中的研究进展

缺氧诱导因子（HIFs）是对细胞低氧敏感的特异性转录因子,其活性受脯氨酸羟化酶（PHD）及 希佩尔林道病肿瘤抑制蛋白（pVHL）调控。在低氧条件下,PHDs 的活性受到抑制,pVHL 发生失活,导致HIFs 的降解受到抑制,HIFs 表达增加,参与低氧相关病理生理过程。该文总结PHDs-HIFs-pVHL 在类风湿关节炎中的研究进展,以期为类风湿关节炎的发病机制以及治疗研究提供新的思路。     

NADPH oxidase-mitochondria axis-derived ROS mediate arsenite-induced HIF-1α stabilization by inhibiting prolyl hydroxylases activity

Arsenic exposure has been shown to induce hypoxia inducible factor 1α (HIF-1α) accumulation, however the underlying mechanism remains unknown. In the present study, we tested the hypothesis that arsenic exposure triggered the interaction between NADPH oxidase and mitochondria to promote reactive oxygen species (ROS) production, which inactivate prolyl hydroxylases (PHDs) activity, leading to the stabilization of HIF-1α protein. Exposure of human immortalized liver cell line HL-7702 cells to arsenite induced HIF-1α accumulation in a dose-dependent manner, which was abolished by SOD mimetic MnTMPyP. Inhibition of NADPH oxidase with diphenyleneiodonium chloride (DPI) or inhibition of mitochondrial respiratory chain with rotenone significantly blocked arsenite-induced ROS production, and the mitochondria appeared to be the major source of ROS production. Arsenite treatment inhibited HIF-1α hydroxylation by prolyl hydroxylases (PHDs) and increased HIF-1α stabilization, but did not affect HIF-1α mRNA expression and Akt activation. Supplementation of ascorbate or Fe(II) completely abolished arsenite-induced PHDs inhibition and HIF-1α stabilization. In conclusion, these results define a unique mechanism of HIF-1α accumulation following arsenic exposure, that is, arsenic activates NADPH oxidase–mitochondria axis to produce ROS, which deplete intracellular ascorbate and Fe(II) to inactivate PHDs, leading to HIF-1α stabilization.