title: RAS is regulated by the let-7 microRNA family.
abstract: MicroRNAs (miRNAs) are regulatory RNAs found in multicellular eukaryotes, including humans, where they are implicated in cancer. The let-7 miRNA times seam cell terminal differentiation in C. elegans. Here we show that the let-7 family negatively regulates let-60/RAS. Loss of let-60/RAS suppresses let-7, and the let-60/RAS 3'UTR contains multiple let-7 complementary sites (LCSs), restricting reporter gene expression in a let-7-dependent manner. mir-84, a let-7 family member, is largely absent in vulval precursor cell P6.p at the time that let-60/RAS specifies the 1 degrees vulval fate in that cell, and mir-84 overexpression suppresses the multivulva phenotype of activating let-60/RAS mutations. The 3'UTRs of the human RAS genes contain multiple LCSs, allowing let-7 to regulate RAS expression. let-7 expression is lower in lung tumors than in normal lung tissue, while RAS protein is significantly higher in lung tumors, providing a possible mechanism for let-7 in cancer.
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, Yale University, P.O. Box 208103, New Haven, CT 06520, USA.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Johnson
authors.forename: Helge
authors.initials: H
authors.lastname: Grosshans
authors.forename: Jaclyn
authors.initials: J
authors.lastname: Shingara
authors.forename: Mike
authors.initials: M
authors.lastname: Byrom
authors.forename: Rich
authors.initials: R
authors.lastname: Jarvis
authors.forename: Angie
authors.initials: A
authors.lastname: Cheng
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Labourier
authors.forename: Kristy L
authors.initials: KL
authors.lastname: Reinert
authors.forename: David
authors.initials: D
authors.lastname: Brown
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Slack
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000235:genetics*; D002277:Carcinoma / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics; D019070:Cell Lineage / Q000235:genetics; D002471:Cell Transformation, Neoplastic / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D017930:Genes, Reporter / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics*; D008969:Molecular Sequence Data; D018631:ras Proteins / Q000235:genetics*
chemical_list: D020413:3' Untranslated Regions; D029742:Caenorhabditis elegans Proteins; D035683:MicroRNAs; C474488:let-7 microRNA, C elegans; C066646:let-60 protein, C elegans; D018631:ras Proteins