Liver-Enriched Transcription Factors Regulate MicroRNA-122 That Targets CUTL1 During Liver Development
Liver-Enriched Transcription Factors Regulate MicroRNA-122 That Targets CUTL1 During Liver Development
复制标题
富含肝脏的转录因子在肝脏发育过程中调节靶向 CUTL1 的 MicroRNA-122
DOI：
10.1002/hep.23818
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发表时间：
2010-10-01
期刊：
影响因子：
13.5
通讯作者：
Qu, Liang-Hu
中科院分区：
文献类型：
--
作者：
Xu, Hui;He, Jie-Hua;Qu, Liang-Hu
microRNA -122 （miR-122）是一种肝脏特异性microRNA，其表达在小鼠胚胎发生过程中特异性开启，因此有望参与肝脏发育。然而，miR-122在肝脏发育中的作用及其潜在机制尚不清楚。在这里，我们发现miR-122的表达与四种肝富集转录因子（LETFs）密切相关-肝细胞核因子（HNF） 1 α, HNF3 β， HNF4 α和CCAAT/增强子结合蛋白(C/EBP) α -在发育中的小鼠胚胎和人肝细胞癌（HCC）细胞系的肝脏中。相应的，启动子分析显示这些letf协同参与miR-122的转录调控，三个hnf作为转录激活因子直接结合到miR-122启动子上。利用荧光素酶报告系统，我们确定了一组参与增殖和分化调控的miR-122靶点。在这些靶标中，最显著的抑制靶标是CUTL1，这是一种在多种细胞系（包括肝细胞）中指定终端分化的基因的转录抑制因子。我们发现，在小鼠肝脏发育过程中，CUTL1的表达在转录后水平上逐渐沉默。过表达和敲低研究均表明，miR-122抑制HCC细胞系中CUTL1蛋白的表达。最后，我们发现在HepG2细胞中稳定恢复miR-122可以抑制细胞增殖并激活三种肝细胞功能基因的表达，包括胆固醇-7 α羟化酶基因（CYP7A1），这是CUTL1在肝细胞中的已知靶点。结论：我们的研究提供了一个模型，其中miR-122作为letf的效应物，通过调节肝细胞增殖和分化之间的平衡，至少通过靶向CUTL1，促进肝脏发育。(肝脏病学52:1431 2010;1442)
MicroRNA-122 (miR-122) is a liver-specific microRNA whose expression is specifically turned on in the mouse liver during embryogenesis, thus it is expected to be involved in liver development. However, the role of miR-122 in liver development and its potential underlying mechanism remain unclear. Here, we show that the expression of miR-122 is closely correlated with four liver-enriched transcription factors (LETFs)-hepatocyte nuclear factor (HNF) 1 alpha, HNF3 beta, HNF4 alpha, and CCAAT/enhancer-binding protein (C/EBP) alpha-in the livers of developing mouse embryos and in human hepatocellular carcinoma (HCC) cell lines. Correspondingly, promoter analysis revealed that these LETFs are coordinately involved in the transcriptional regulation of miR-122, and three HNFs directly bind to the miR-122 promoter as transcriptional activators. Using a luciferase reporter system, we identified a group of miR-122 targets involved in proliferation and differentiation regulation. Among these targets, the most prominently repressed target was CUTL1, a transcriptional repressor of genes specifying terminal differentiation in multiple cell lineages, including hepatocytes. We show that CUTL1 expression is gradually silenced at the posttranscriptional level during mouse liver development. Overexpression and knockdown studies both showed that miR-122 repressed CUTL1 protein expression in HCC cell lines. Finally, we show that the stable restoration of miR-122 in HepG2 cells suppresses cellular proliferation and activates the expression of three hepatocyte functional genes, including the cholesterol-7 alpha hydroxylase gene (CYP7A1), a known target of CUTL1 in hepatocytes. Conclusion: Our study provides a model in which miR-122 functions as an effector of LETFs and contributes to liver development by regulating the balance between proliferation and differentiation of hepatocytes, at least by targeting CUTL1. (HEPATOLOGY 2010;52:1431-1442)