Papoutsi Maria, Dudas Jozsef, Becker Jürgen, Tripodi Marco, Opitz Lennart, Ramadori Giuliano, Wilting Jörg
Children's Hospital, Pediatrics I, Georg August University, Robert-Koch-Strasse 40, 37075, Göttingen, Germany.
Cell Tissue Res. 2007 Nov;330(2):209-20. doi: 10.1007/s00441-007-0477-4. Epub 2007 Sep 9.
The homeobox transcription factor Prox1 is expressed in embryonic hepatoblasts and remains expressed in adult hepatocytes. Prox1-null mice show severe deficiencies in liver development, although the underlying mechanisms are unknown. We have studied the effects of Prox1 on the transcriptional profile of met-murine hepatocytes (MMH) obtained on embryonic day 14 (ED14). These immortalized murine hepatoblasts express numerous hepatoblast markers, but not Prox1. We have performed stable transfection with Prox1 cDNA, analyzed the transcriptome with Agilent mouse whole-genome microarrays, and validated genes by quantitative reverse transcription/polymerase chain reaction. We have observed the up-regulation of 22 genes and the down-regulation of 232 genes, by more than 12-fold. Many of these genes are involved in metabolic hepatocyte functions and may be regulated by Prox1 directly or indirectly, e.g., by the down-regulation of hepatocyte nuclear factor 4alpha. Prox1 induces the down-regulation of transcription factors that are highly expressed in neighboring endodermal organs, suggesting a function during hepatoblast commitment. Prox1 does not influence the proliferative activity of MMH but regulates genes involved in liver morphogenesis. We have observed the up-regulation of both type-IValpha3 procollagen and functionally active matrix metalloproteinase-2 (MMP-2), an observation that places Prox1 at the center of liver matrix turnover. This is consistent with MMP-2 expression in hepatoblasts during liver development and with the persistence of a basal lamina around the liver bud in Prox1-deficient mice. Our studies suggest that Prox1 is a multifunctional regulator of liver morphogenesis and of hepatocyte function and commitment.
同源框转录因子Prox1在胚胎肝母细胞中表达，并在成年肝细胞中持续表达。Prox1基因敲除小鼠在肝脏发育方面表现出严重缺陷，但其潜在机制尚不清楚。我们研究了Prox1对在胚胎第14天（ED14）获得的间变性小鼠肝细胞（MMH）转录谱的影响。这些永生化的小鼠肝母细胞表达多种肝母细胞标志物，但不表达Prox1。我们用Prox1 cDNA进行了稳定转染，用安捷伦小鼠全基因组微阵列分析了转录组，并通过定量逆转录/聚合酶链反应验证了基因。我们观察到22个基因上调，232个基因下调，上调和下调幅度均超过12倍。这些基因中的许多参与肝细胞代谢功能，可能直接或间接受Prox1调控，例如通过下调肝细胞核因子4α。Prox1诱导在相邻内胚层器官中高表达的转录因子下调，提示其在肝母细胞定向分化过程中的作用。Prox1不影响MMH的增殖活性，但调节参与肝脏形态发生的基因。我们观察到I型α3前胶原和功能活性基质金属蛋白酶-2（MMP-2）均上调，这一观察结果表明Prox1处于肝脏基质更新的中心位置。这与肝脏发育过程中肝母细胞中MMP-2的表达以及Prox1缺陷小鼠肝芽周围基膜的持续存在相一致。我们的研究表明，Prox1是肝脏形态发生、肝细胞功能及定向分化的多功能调节因子。
