A Feedback Loop Between the Liver-Enriched Transcription Factor Network and Mir-122 Controls Hepatocyte Differentiation
A Feedback Loop Between the Liver-Enriched Transcription Factor Network and Mir-122 Controls Hepatocyte Differentiation
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DOI：
10.1053/j.gastro.2011.09.001
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发表时间：
2012-01-01
期刊：
影响因子：
29.4
通讯作者：
Lemaigre, Frederic P.
中科院分区：
文献类型：
--
作者：
Laudadio, Ilaria;Manfroid, Isabelle;Lemaigre, Frederic P.
背景与目的：肝细胞分化受肝脏富集转录因子（LETF）控制。我们研究了LETF是否控制发育过程中microRNA的表达，以及这种控制是否是肝细胞分化所必需的。方法：使用体内DNA结合试验，我们确定miR-122作为LETF肝细胞核因子（HNF）6的直接靶点。以发育中的小鼠和斑马鱼为模型生物，通过功能获得和功能丧失实验，在体内和体外研究HNF 6-miR-122基因级联在肝细胞分化中的作用和机制。结果：HNF 6及其同源物Onecut 2是miR-122表达的强转录刺激因子。特定水平的miR-122是肝细胞分化的适当进展所必需的; miR-122刺激肝细胞特异性基因和大多数LETF（包括HNF 6）的表达。这表明HNF 6和miR-122形成了正反馈循环。miR-122对肝细胞分化的刺激在HNF 6基因敲除小鼠中消失，这表明转录因子可以介导microRNA的功能。所有肝细胞特异性基因，其表达由miR-122刺激结合HNF 6在体内，证实了他们的直接调节，由这个因素。结论：肝细胞分化是由一个正反馈环，包括转录因子（HNF 6）和microRNA（miR-122），在肝脏中特异性表达。这些发现可能导致体外诱导肝细胞分化的方法，并提高我们对病理条件下肝细胞去分化的理解。
BACKGROUND & AIMS: Hepatocyte differentiation is controlled by liver-enriched transcription factors (LETFs). We investigated whether LETFs control microRNA expression during development and whether this control is required for hepatocyte differentiation. METHODS: Using in vivo DNA binding assays, we identified miR-122 as a direct target of the LETF hepatocyte nuclear factor (HNF) 6. The role and mechanisms of the HNF6-miR-122 gene cascade in hepatocyte differentiation were studied in vivo and in vitro by gain-of-function and loss-of-function experiments, using developing mice and zebrafish as model organisms. RESULTS: HNF6 and its paralog Onecut2 are strong transcriptional stimulators of miR-122 expression. Specific levels of miR-122 were required for proper progression of hepatocyte differentiation; miR-122 stimulated the expression of hepatocyte-specific genes and most LETFs, including HNF6. This indicates that HNF6 and miR-122 form a positive feedback loop. Stimulation of hepatocyte differentiation by miR-122 was lost in HNF6-null mice, revealing that a transcription factor can mediate microRNA function. All hepatocyte-specific genes whose expression was stimulated by miR-122 bound HNF6 in vivo, confirming their direct regulation by this factor. CONCLUSIONS: Hepatocyte differentiation is directed by a positive feedback loop that includes a transcription factor (HNF6) and a microRNA (miR-122) that are specifically expressed in liver. These findings could lead to methods to induce differentiation of hepatocytes in vitro and improve our understanding of liver cell dedifferentiation in pathologic conditions.