title: Antagonistic function of the RNA-binding protein HuR and miR-200b in post-transcriptional regulation of vascular endothelial growth factor-A expression and angiogenesis.
abstract: 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 (Elavl1Mø 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 Elavl1Mø KO mice also showed alterations in expression of several miRNAs. Interestingly, computational analysis suggested that miR-200b, which is up-regulated in Elavl1Mø 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 Elavl1Mø KO BMDMs. Interestingly, tumor growth, angiogenesis, vascular sprouting, branching, and permeability were significantly attenuated in Elavl1Mø 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.
authors.affiliation: Center for Vascular Biology, Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, Cornell University, New York, New York 10065, USA.
authors.forename: Sung-Hee
authors.initials: SH
authors.lastname: Chang
authors.forename: Yi-Chien
authors.initials: YC
authors.lastname: Lu
authors.forename: Xi
authors.initials: X
authors.lastname: Li
authors.forename: Wan-Ying
authors.initials: WY
authors.lastname: Hsieh
authors.forename: Yuquan
authors.initials: Y
authors.lastname: Xiong
authors.forename: Mallika
authors.initials: M
authors.lastname: Ghosh
authors.forename: Todd
authors.initials: T
authors.lastname: Evans
authors.forename: Olivier
authors.initials: O
authors.lastname: Elemento
authors.forename: Timothy
authors.initials: T
authors.lastname: Hla
mesh_terms: D020413:3' Untranslated Regions; D000595:Amino Acid Sequence; D000818:Animals; D039481:CD11b Antigen / Q000096:biosynthesis; D051959:ELAV Proteins / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D017353:Gene Deletion; D018507:Gene Expression Regulation, Developmental; D057809:HEK293 Cells; D006801:Humans; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D051379:Mice; D035683:MicroRNAs / Q000378:metabolism*; D008969:Molecular Sequence Data; D009389:Neovascularization, Pathologic; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D015027:Zebrafish
chemical_list: D020413:3' Untranslated Regions; D039481:CD11b Antigen; D051959:ELAV Proteins; C533896:MIRN200 microRNA, human; D035683:MicroRNAs; C543719:Mirn200 microRNA, mouse; D042461:Vascular Endothelial Growth Factor A