Antagonistic Function of the RNA-binding Protein HuR and miR-200b in Post-transcriptional Regulation of Vascular Endothelial Growth Factor-A Expression and Angiogenesis
Antagonistic Function of the RNA-binding Protein HuR and miR-200b in Post-transcriptional Regulation of Vascular Endothelial Growth Factor-A Expression and Angiogenesis
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DOI：
10.1074/jbc.m112.423871
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发表时间：
2013-02-15
影响因子：
4.8
通讯作者：
Hla, Timothy
中科院分区：
文献类型：
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作者：
Chang, Sung-Hee;Lu, Yi-Chien;Hla, Timothy
HuR，也称为Elavl 1，是一种RNA结合蛋白，调节胚胎发育，祖细胞存活和细胞应激反应。HuR在血管生成中的作用尚不清楚。使用骨髓特异性HuR敲除小鼠模型（Elavl 1 Mo KO），我们表明需要骨髓源性巨噬细胞（BMDM）中的HuR表达来维持3 '-UTR中富含AU元件和富含U元件的基因的表达。此外，来自ElavllMo KO小鼠的BMDM也显示出几种miRNA表达的改变。有趣的是，计算分析表明，在ElavllMo KO BMDM中上调的miR-200 b与非常接近HuR结合位点的骨髓mRNA相互作用，表明基因表达的竞争性调节。一种这样的mRNA编码血管内皮生长因子（VEGF）-A，血管生成的主要调节因子。RNA-蛋白质复合物的免疫沉淀和荧光素酶报告基因测定表明，HuR拮抗miR-200 b的抑制活性，下调miR-200 b表达，并促进VEGF-A表达。事实上，Vegf-a和其他血管生成调节转录物在ElavllMo KO BMDM中下调。有趣的是，肿瘤生长，血管生成，血管发芽，分支，和渗透性显着衰减Elavl 1 Mo KO小鼠，表明HuR调节的髓源性因子调节肿瘤血管生成的反式斑马鱼胚胎注射elavl 1吗啉寡聚体或miR-200 b模拟物显示血管生成缺陷的肠下静脉丛，和elavl 1 mRNA拯救miR-200 b的抑制作用。此外，miR-200 b和HuR吗啉代寡聚体抑制zVEGF 3 '-UTR荧光素酶报告基因构建体的活性。总之，这些研究揭示了一种进化上保守的转录后机制，涉及HuR和miR-200 b之间的竞争性相互作用，控制血管生成。
HuR, also known as Elavl1, is an RNA-binding protein that regulates embryonic development, progenitor cell survival, and cell stress responses. The role of HuR in angiogenesis is not known. Using a myeloid-specific HuR knock-out mouse model (Elavl1Mo KO), we show that HuR expression in bone marrow-derived macrophages (BMDMs) is needed to maintain the expression of genes enriched in AU-rich elements and U-rich elements in the 3'-UTR. In addition, BMDMs from Elavl1Mo KO mice also showed alterations in expression of several miRNAs. Interestingly, computational analysis suggested that miR-200b, which is up-regulated in Elavl1Mo KO BMDMs, interacts with myeloid mRNAs very close to the HuR binding sites, suggesting competitive regulation of gene expression. One such mRNA encodes vascular endothelial growth factor (VEGF)-A, a major regulator of angiogenesis. Immunoprecipitation of RNA-protein complexes and luciferase reporter assays indicate that HuR antagonizes the suppressive activity of miR-200b, down-regulates miR-200b expression, and promotes VEGF-A expression. Indeed, Vegf-a and other angiogenic regulatory transcripts were down-regulated in Elavl1Mo KO BMDMs. Interestingly, tumor growth, angiogenesis, vascular sprouting, branching, and permeability were significantly attenuated in Elavl1Mo KO mice, suggesting that HuR-regulated myeloid-derived factors modulate tumor angiogenesis in trans. Zebrafish embryos injected with an elavl1 morpholino oligomer or miR-200b mimic showed angiogenesis defects in the subintestinal vein plexus, and elavl1 mRNA rescued the repressive effect of miR-200b. In addition, miR-200b and HuR morpholino oligomer suppressed the activity of a zVEGF 3'-UTR luciferase reporter construct. Together, these studies reveal an evolutionarily conserved post-transcriptional mechanism involving competitive interactions between HuR and miR-200b that controls angiogenesis.