Li Ya-Wen, Chiang Keng-Yu, Li Yen-Hsing, Wu Sung-Yu, Liu Wangta, Lin Chia-Ray, Wu Jen-Leih
Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.
Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan.
PLoS One. 2017 May 22;12(5):e0177887. doi: 10.1371/journal.pone.0177887. eCollection 2017.
MicroRNAs (miRs) are mRNA-regulatory molecules that fine-tune gene expression and modulate both processes of development and tumorigenesis. Our previous studies identified progranulin A (GrnA) as a growth factor which induces zebrafish hepatic outgrowth through MET signaling. We also found that miR-145 is one of potential fine-tuning regulators of GrnA involved in embryonic hepatic outgrowth. The low level of miR-145 seen in hepatocarinogenesis has been shown to promote pathological liver growth. However, little is known about the regulatory mechanism of miR-145 in embryonic liver development. In this study, we demonstrate a significant decrease in miR-145 expression during hepatogenesis. We modulate miR-145 expression in zebrafish embryos by injection with a miR-145 mimic or a miR-145 hairpin inhibitor. Altered embryonic liver outgrowth is observed in response to miR-145 expression modulation. We also confirm a critical role of miR-145 in hepatic outgrowth by using whole-mount in situ hybridization. Loss of miR-145 expression in embryos results in hepatic cell proliferation, and vice versa. Furthermore, we demonstrate that GrnA is a target of miR-145 and GrnA-induced MET signaling is also regulated by miR-145 as determined by luciferase reporter assay and gene expression analysis, respectively. In addition, co-injection of GrnA mRNA with miR-145 mimic or MO-GrnA with miR-145 inhibitor restores the liver defects caused by dysregulation of miR-145 expression. In conclusion, our findings suggest an important role of miR-145 in regulating GrnA-dependent hepatic outgrowth in zebrafish embryonic development.
微小RNA（miR）是一类mRNA调节分子，可微调基因表达，并调节发育和肿瘤发生过程。我们之前的研究确定前颗粒蛋白A（GrnA）是一种生长因子，它通过MET信号诱导斑马鱼肝脏生长。我们还发现miR-145是参与胚胎肝脏生长的GrnA潜在微调调节因子之一。在肝癌发生过程中观察到的低水平miR-145已被证明可促进病理性肝脏生长。然而，关于miR-145在胚胎肝脏发育中的调节机制知之甚少。在本研究中，我们证明了在肝脏发生过程中miR-145表达显著下降。我们通过注射miR-145模拟物或miR-145发夹抑制剂来调节斑马鱼胚胎中miR-145的表达。观察到miR-145表达调节后胚胎肝脏生长发生改变。我们还通过全胚胎原位杂交证实了miR-145在肝脏生长中的关键作用。胚胎中miR-145表达缺失导致肝细胞增殖，反之亦然。此外，分别通过荧光素酶报告基因检测和基因表达分析确定GrnA是miR-145的靶标，并且miR-145也调节GrnA诱导的MET信号。此外，将GrnA mRNA与miR-145模拟物共注射或MO-GrnA与miR-145抑制剂共注射可恢复由miR-145表达失调引起的肝脏缺陷。总之，我们的研究结果表明miR-145在斑马鱼胚胎发育中调节GrnA依赖性肝脏生长中起重要作用。
