Abstract: Background　Gestational diabetes mellitus（GDM） is a gestational complication commonly seen in clinical practice，which seriously threatens the life and health of the mother and the fetus.The analysis of the molecular mechanism of miR-let-7 mediated by H19（an imprinted gene） and its role in the development of GDM can provide a basis for targeted therapy for this disease.Objective　To study the molecular mechanism of H19-mediated miR-let-7 and its role in GDM.Methods　This experiment was conducted from January 2017 to January 2018.The 50 SPF grade experimental mice were purchased from Peking University Health Science Center.After 7 days of free diet，the mice were divided into normal-fat group （20 cases） and high-fat group （30 cases） according to their blood glucose and lipid levels.RT-qPCR was used to analyze the relative mRNA expression levels of H19，let-7，target genes LPL，INSR-β in the liver and IRS-2 in mice of the two groups.At the same time in mice myoblast cell lines，through cell transfection technique，small interfering RNA （siRNA） was transfected for the knockdown of the H19，and antisense strand iLet-7 was transfected for specifically blocking the let-7 to combine with target genes.3 and 6 weeks after transfection，cells were harvested，The relative mRNA expression levels of H19，let-7 and target genes LPL，INSR-β，IRS-2 and INSR were observed at different time points.And the same experimental procedure was carried out in human ovarian teratoma-derived cell line PA-1．Results　The normal-fat group showed significantly lower mRNA expression levels of H19，let-7 and LPL，and much higher mRNA expression levels of INSR-β，IRS-2 and INSR compared with the high-fat group （P<0.05）．The mRNA expression levels of the above-mentioned 6 indicators at baseline，and at the end of 3 weeks and 6 weeks of intervention were all significantly different in mice myoblast cell lines（P<0.05），as did they in human ovarian teratoma-derived cell line PA-1（P<0.05）．Conclusion　H19 mediates the molecular mechanism in miR-let-7 and plays a vital role in the development of GDM.Clinical detection of relevant indicators such as H19 and miR-let-7 in pregnant women should be strengthened in order to identify GDM as early as possible.

Key words: Diabetes, gestational；H19；miR-let-7；Molecular mechanism

摘要： 背景　妊娠期糖尿病作为临床中常见的妊娠期合并症，其严重威胁产妇及胎儿的生命健康。H19作为一种印记基因，进一步分析其为妊娠期糖尿病靶向治疗工作的开展提供依据。目的　研究H19介导miR-let-7的分子机制及其在妊娠期糖尿病中的作用。方法　2017年1月—2018年1月于北京大学医学部购进50只SPF级小鼠，根据小鼠的血糖以及血脂水平等将其分为正常组（n=20）和高脂组（n=30）。采用实时荧光定量反转录聚合酶链式反应（RT-qPCR）技术分析正常组和高脂组小鼠H19、let-7、靶基因脂蛋白脂肪酶（LPL）以及肝脏胰岛素受体β（INSR-β）和胰岛素通路相关因子2（IRS-2）、胰岛素受体（INSR）的相对mRNA表达水平。同时于小鼠成肌细胞株中，分别通过细胞转染技术转染干扰RNA（siRNA），特异性敲除小鼠H19，以及转染反义链抑制剂ilet-7，特异性阻断let-7结合靶基因，共转染后分别在第3、6周时收获细胞，观察不同时间点H19、let-7以及靶基因LPL、INSR-β、IRS-2和INSR的相对mRNA表达水平。在人卵巢畸胎瘤细胞系PA-1中，分别通过细胞转染技术转染siRNA，特异性敲除人H19，以及转染反义链抑制剂ilet-7，特异性阻断let-7结合靶基因，共转染后分别在第3、6周时收获细胞，观察各组中H19、let-7以及靶基因LPL、INSR-β、IRS-2及INSR的相对mRNA表达水平。结果　高脂组小鼠H19、let-7及LPL mRNA表达水平高于正常组，INSR-β、IRS-2及INSR mRNA表达水平低于正常组（P<0.05）。不同时间点小鼠成肌细胞株H19、let-7、LPL、INSR-β、IRS-2及INSR mRNA表达水平比较，差异均有统计学意义（P<0.05）。不同时间点人卵巢畸胎瘤细胞系PA-1 H19、let-7、LPL、INSR-β、IRS-2及INSR mRNA表达水平比较，差异均有统计学意义（P<0.05）。结论　H19在miR-let-7中发挥分子介导机制，且在妊娠期糖尿病的参与中发挥至关重要的作用，临床中应当加强对妊娠期孕妇的H19以及miR-let-7等相关指标的检测，实现对妊娠期糖尿病的早期预测。

关键词: 糖尿病, 妊娠；H19；miR-let-7；分子机制