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目的:探讨血管紧张素Ⅱ(angiotensinⅡ,AngⅡ)对RIN-m细胞胰岛素基因表达的影响及其相关分子机制。方法:常规培养大鼠胰岛素瘤RIN-m细胞,分为3组:空白对照组、100 nmol·L~(-1)AngⅡ组和氯沙坦预处理组,干预24h,采用RTPCR法检测胰岛素基因表达,流式细胞仪检测2’,7’-二氯荧光素(DCF)的平均荧光强度,RT-PCR法检测胰十二指肠同源盒-1(PDX-1)及肌腱膜纤维肉瘤肿瘤基因同系物A(MafA)mRNA表达,Western-blot法检测PDX-1及MafA蛋白表达。结果:100nmol·L~(-1)AngⅡ组与空白组和氯沙坦预处理组间的胰岛素mRNA表达、活性氧(reactive oxygen species,ROS)水平、PDX-1、MafA mRNA及蛋白表达均有显著差异(P<0.05),后两者之间差异无统计学意义(P>0.05)。结论:AngⅡ可能通过氧化应激途径下调β细胞的PDX-1及MafA活性,进而抑制β细胞胰岛素基因表达。氯沙坦预处理可以拮抗AngⅡ对β细胞的氧化应激损伤,从而在胰岛素基因表达方面对β细胞起到保护作用。
Objective: To investigate the effect of angiotensin Ⅱ (AngⅡ) on insulin gene expression in RIN-m cells and its related molecular mechanisms. Methods: RIN-m cells were cultured routinely in rats. The cells were divided into 3 groups: blank control group, 100 nmol·L -1 AngⅡ group and losartan pretreatment group. After intervention for 24h, RTPCR was used to detect the expression of insulin gene The average fluorescence intensity of 2 ’, 7’-dichlorofluorescein (DCF) was detected by flow cytometry. The pancreaticoduodenal homeobox-1 (PDX-1) and aponeurotic fibrosarcoma The tumor gene homologue A (MafA) mRNA expression was detected by Western-blot and the protein expression of PDX-1 and MafA was detected. Results: The insulin mRNA expression, reactive oxygen species (ROS) level, PDX-1, MafA mRNA and protein expression in 100 nmol·L -1 AngⅡ group and losartan group were (P <0.05), but there was no significant difference between them (P> 0.05). CONCLUSION: AngⅡ may down-regulate the activity of PDX-1 and MafA in β-cells through oxidative stress, thereby inhibiting the expression of β-cell insulin. Losartan preconditioning can antagonize the oxidative stress injury induced by AngⅡon the β cells and thus protect theβcells in terms of insulin gene expression.