title: The RNA-binding protein KSRP promotes the biogenesis of a subset of microRNAs.
abstract: Consistent with the role of microRNAs (miRNAs) in down-regulating gene expression by reducing the translation and/or stability of target messenger RNAs, the levels of specific miRNAs are important for correct embryonic development and have been linked to several forms of cancer. However, the regulatory mechanisms by which primary miRNAs (pri-miRNAs) are processed first to precursor miRNAs (pre-miRNAs) and then to mature miRNAs by the multiprotein Drosha and Dicer complexes, respectively, remain largely unknown. The KH-type splicing regulatory protein (KSRP, also known as KHSRP) interacts with single-strand AU-rich-element-containing mRNAs and is a key mediator of mRNA decay. Here we show in mammalian cells that KSRP also serves as a component of both Drosha and Dicer complexes and regulates the biogenesis of a subset of miRNAs. KSRP binds with high affinity to the terminal loop of the target miRNA precursors and promotes their maturation. This mechanism is required for specific changes in target mRNA expression that affect specific biological programs, including proliferation, apoptosis and differentiation. These findings reveal an unexpected mechanism that links KSRP to the machinery regulating maturation of a cohort of miRNAs that, in addition to its role in promoting mRNA decay, independently serves to integrate specific regulatory programs of protein expression.
authors.affiliation: Howard Hughes Medical Institute, Department and School of Medicine, University of California, San Diego, 9500 Gilman Drive, Room 345, La Jolla, California 92093-0648, USA.
authors.forename: Michele
authors.initials: M
authors.lastname: Trabucchi
authors.forename: Paola
authors.initials: P
authors.lastname: Briata
authors.forename: Mariaflor
authors.initials: M
authors.lastname: Garcia-Mayoral
authors.forename: Astrid D
authors.initials: AD
authors.lastname: Haase
authors.forename: Witold
authors.initials: W
authors.lastname: Filipowicz
authors.forename: Andres
authors.initials: A
authors.lastname: Ramos
authors.forename: Roberto
authors.initials: R
authors.lastname: Gherzi
authors.forename: Michael G
authors.initials: MG
authors.lastname: Rosenfeld
mesh_terms: D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D006801:Humans; D051379:Mice; D035683:MicroRNAs / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D016601:RNA-Binding Proteins / Q000378:metabolism*; D043244:Ribonuclease III / Q000737:chemistry / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism*
chemical_list: C105789:KHSRP protein, human; C488352:Lin-28 protein, mouse; D035683:MicroRNAs; D016601:RNA-Binding Proteins; D015534:Trans-Activators; C487931:mirnlet7 microRNA, human; C517918:DROSHA protein, human; D043244:Ribonuclease III