title: Multiple tumor suppressor microRNAs regulate telomerase and TCF7, an important transcriptional regulator of the Wnt pathway.
abstract: The human TERT (hTERT) gene encodes the telomerase catalytic subunit which plays a role in telomerase regulation. Telomerase is activated in more than 90% of all human malignancies and understanding how telomerase is regulated is necessary for implementation of successful anti-cancer therapies. microRNAs (miRNAs) are important regulators of gene expression in eukaryotic cells but evidence of their role in telomerase regulation has not been documented. To determine whether hTERT activity is regulated by multiple miRNAs, eight miRNAs which have putative binding sites in the hTERT 3'UTR together with miR-138-5p were evaluated in luciferase assays with a reporter containing the hTERT 3'UTR. Six miRNAs (let-7g*, miR-133a, miR-138-5p, miR-342-5p, miR-491-5p, and miR-541-3p) specifically inhibited the expression of the reporter luciferase-driven constructs and let-7g*, miR-133a, miR-138-5p, and miR-491-5p also downregulated endogenous telomerase activity in cells. Moreover, all six miRNAs significantly inhibited cell proliferation. miRNAs (miR-133a, miR-138-5p, 342-5p, 491-5p, 541-3p) also have predicted binding sites within the 3'UTR of three genes involved in Wnt signaling (TCF7, MSI1, and PAX5). These miRNAs inhibited the expression of the luciferase reporter constructs containing 3'UTRs of these genes and downregulated protein expression of the TCF7 transcription factor, which mediates the canonical Wnt pathway. Together, these results suggest the existence of a miRNA regulatory network involving the hTERT and Wnt pathway.
authors.affiliation: Department of Molecular Biosciences, College of Natural Sciences, and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America.
authors.forename: Radmila
authors.initials: R
authors.lastname: Hrdličková
authors.affiliation: Department of Molecular Biosciences, College of Natural Sciences, and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America.
authors.forename: Jiří
authors.initials: J
authors.lastname: Nehyba
authors.affiliation: Department of Molecular Biosciences, College of Natural Sciences, and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America.
authors.forename: William
authors.initials: W
authors.lastname: Bargmann
authors.affiliation: Department of Molecular Biosciences, College of Natural Sciences, and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, United States of America.
authors.forename: Henry R
authors.initials: HR
authors.lastname: Bose
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015536:Down-Regulation / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D017930:Genes, Reporter / Q000235:genetics; D016147:Genes, Tumor Suppressor; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D051757:PAX5 Transcription Factor / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D051822:T Cell Transcription Factor 1 / Q000235:genetics* / Q000378:metabolism; D019098:Telomerase / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D060449:Wnt Signaling Pathway / Q000235:genetics*
chemical_list: D020413:3' Untranslated Regions; C491297:MSI1 protein, human; D035683:MicroRNAs; D009419:Nerve Tissue Proteins; D051757:PAX5 Transcription Factor; C497281:PAX5 protein, human; D016601:RNA-Binding Proteins; D051822:T Cell Transcription Factor 1; C497576:TCF7 protein, human; D008156:Luciferases; C509186:TERT protein, human; D019098:Telomerase