慢性缺氧对早期雄性仔鼠肝胰岛素样生长因子1基因启动子区域甲基化影响

目的:研究慢性间断性宫内缺氧(CIH)对新生雄性仔鼠肝胰岛素样生长因子1(IGF-1)基因表达及其甲基化的影响。方法:建立CIH孕大鼠模型,H-E染色观察1 d龄雄仔鼠肝细胞光镜下结构;免疫组织化学法检测肝细胞IGF-1蛋白的表达;实时荧光定量PCR法检测肝组织IGF-1 mRNA的表达;亚硫酸氢盐修饰后测序检测肝组织IGF-1启动子区域位点甲基化修饰情况。结果:CIH可致胎鼠宫内生长受限,缺氧组仔鼠低出生体质量,并出现追赶性生长;缺氧组1 d龄仔代雄大鼠光镜下肝细胞有微量脂肪滴存在,缺氧组IGF-1蛋白的表达较正常组显著下降;CIH子代大鼠肝IGF-1基因启动子甲基化率较对照组明显升高。结论:CIH可致缺氧1 d龄子代雄大鼠肝IGF-1基因启动子片段1、片段2甲基化水平增高,致肝细胞IGF-1蛋白表达水平下降,参与CIH后子代雄性大鼠肝非乙醇性脂肪肝的发生发展过程。

Effects of chronic hypoxia on the methylation of insulin-like growth factor-1 gene promoter in the liver of male offspring rats

Objective:To study the effect of chronic intermittent hypoxia (CIH)on liver insulin-like growth factor-1 (IGF-1 ) gene expression in male newborn rats.Methods:The hepatic microstructure were observed under light microscope.IGF-1 protein expression of liver cells in the two groups of 1 d old rats was detected by immunohistochemistry.Real-time PCR was used to compare the expression difference of IGF-1 mRNA of rat liver tissue in the two groups of 1 d old rats.Bisulfite modified sequencing (BSP)technique was used to detect methyl chemical modification in the liver tissue IGF-1 promoter subsites of the two groups of 1 d old male offspring rats.Results:Chronic intrauterine hypoxia led to fetal intrauterine growth restriction.Offspring rats in the hypoxia group had low weight at birth and catch-up growth.Optical microscope and electron microscope showed hepatocytes with a few fatty droplets in 1 d rats of the hypoxia group,suggesting that there were no alcoholic fatty liver disease and lipid metabolism disorder.Immunohistochemistry of liver tissue of the two sets of 1 d old male offspring rats showed that IGF-1 protein expression decreased significantly in the hypoxia group compared with the normal group.The methylation rate of rat liver IGF-1 promoter in the intrauterine hypoxia group was significantly higher than that of the control group.Conclusion:CIH can cause the increase of methylation level in IGF-1 gene start sequence 1 and sequence 2, the decrease of hepatic IGF-1 protein expression and is involved in the occurrence and development of nonalcoholic fatty liver disease of hypoxia 1 d offspring rats.