title: The multifunctional RNA-binding protein hnRNP A1 is required for processing of miR-18a.
abstract: hnRNP A1 is an RNA-binding protein involved in various aspects of RNA processing. Use of an in vivo cross-linking and immunoprecipitation protocol to find hnRNP A1 RNA targets resulted in the identification of a microRNA (miRNA) precursor, pre-miR-18a. This microRNA is expressed as part of a cluster of intronic RNAs, including miR-17, miR-18a, miR-19a, miR-20a, miR-19b-1 and miR-92, and potentially acts as an oncogene. Here we show that hnRNP A1 binds specifically to the primary RNA sequence pri-miR-18a before Drosha processing. HeLa cells depleted of hnRNP A1 have reduced in vitro processing activity with pri-miR-18a and also show reduced abundances of endogenous pre-miR-18a. Furthermore, we show that hnRNP A1 is required for miR-18a-mediated repression of a target reporter in vivo. These results underscore a previously uncharacterized role for general RNA-binding proteins as auxiliary factors that facilitate the processing of specific miRNAs.
authors.affiliation: Medical Research Council Human Genetics Unit, Western General Hospital, Edinburgh EH4 2XU, Scotland, UK.
authors.forename: Sonia
authors.initials: S
authors.lastname: Guil
authors.forename: Javier F
authors.initials: JF
authors.lastname: Cáceres
mesh_terms: D005786:Gene Expression Regulation; D006367:HeLa Cells; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D035683:MicroRNAs / Q000737:chemistry / Q000378:metabolism*; D012322:RNA Precursors / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D043244:Ribonuclease III / Q000378:metabolism
chemical_list: D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; C522576:MIRN18A microRNA, human; D035683:MicroRNAs; D012322:RNA Precursors; D016601:RNA-Binding Proteins; C517918:DROSHA protein, human; D043244:Ribonuclease III