title: Cis-acting elements in its 3' UTR mediate post-transcriptional regulation of KRAS.
abstract: Multiple RNA-binding proteins and non-coding RNAs, such as microRNAs (miRNAs), are involved in post-transcriptional gene regulation through recognition motifs in the 3' untranslated region (UTR) of their target genes. The KRAS gene encodes a key signaling protein, and its messenger RNA (mRNA) contains an exceptionally long 3' UTR; this suggests that it may be subject to a highly complex set of regulatory processes. However, 3' UTR-dependent regulation of KRAS expression has not been explored in detail. Using extensive deletion and mutational analyses combined with luciferase reporter assays, we have identified inhibitory and stabilizing cis-acting regions within the KRAS 3' UTR that may interact with miRNAs and RNA-binding proteins, such as HuR. Particularly, we have identified an AU-rich 49-nt fragment in the KRAS 3' UTR that is required for KRAS 3' UTR reporter repression. This element contains a miR-185 complementary element, and we show that overexpression of miR-185 represses endogenous KRAS mRNA and protein in vitro. In addition, we have identified another 49-nt fragment that is required to promote KRAS 3' UTR reporter expression. These findings indicate that multiple cis-regulatory motifs in the 3' UTR of KRAS finely modulate its expression, and sequence alterations within a binding motif may disrupt the precise functions of trans-regulatory factors, potentially leading to aberrant KRAS expression.
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA.|Institute for RNA Medicine, Department of Pathology, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, MA, USA.
authors.forename: Minlee
authors.initials: M
authors.lastname: Kim
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA.|Current address: Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
authors.forename: Nicole
authors.initials: N
authors.lastname: Kogan
authors.affiliation: Institute for RNA Medicine, Department of Pathology, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, MA, USA.
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Slack
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics*; D001483:Base Sequence; D015972:Gene Expression Regulation, Neoplastic; D017930:Genes, Reporter; D006801:Humans; D009369:Neoplasms / Q000235:genetics*; D011401:Promoter Regions, Genetic; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics*; D012323:RNA Processing, Post-Transcriptional; D012045:Regulatory Sequences, Nucleic Acid; D014407:Tumor Cells, Cultured
chemical_list: D020413:3' Untranslated Regions; C117307:KRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)
keywords: 3′ UTR; KRAS; miR-185; microRNAs (miRNAs); post-transcriptional regulation