title: Essential Role for endogenous siRNAs during meiosis in mouse oocytes.
abstract: The RNase III enzyme DICER generates both microRNAs (miRNAs) and endogenous short interfering RNAs (endo-siRNAs). Both small RNA species silence gene expression post-transcriptionally in association with the ARGONAUTE (AGO) family of proteins. In mammals, there are four AGO proteins (AGO1-4), of which only AGO2 possesses endonucleolytic activity. siRNAs trigger endonucleolytic cleavage of target mRNAs, mediated by AGO2, whereas miRNAs cause translational repression and mRNA decay through association with any of the four AGO proteins. Dicer deletion in mouse oocytes leads to female infertility due to defects during meiosis I. Because mouse oocytes express both miRNAs and endo-siRNAs, this phenotype could be due to the absence of either class of small RNA, or both. However, we and others demonstrated that miRNA function is suppressed in mouse oocytes, which suggested that endo-siRNAs, not miRNAs, are essential for female meiosis. To determine if this was the case we generated mice that express a catalytically inactive knock-in allele of Ago2 (Ago2ADH) exclusively in oocytes and thereby disrupted the function of siRNAs. Oogenesis and hormonal response are normal in Ago2ADH oocytes, but meiotic maturation is impaired, with severe defects in spindle formation and chromosome alignment that lead to meiotic catastrophe. The transcriptome of these oocytes is widely perturbed and shows a highly significant correlation with the transcriptome of Dicer null and Ago2 null oocytes. Expression of the mouse transcript (MT), the most abundant transposable element in mouse oocytes, is increased. This study reveals that endo-siRNAs are essential during meiosis I in mouse females, demonstrating a role for endo-siRNAs in mammals.
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Paula
authors.initials: P
authors.lastname: Stein
authors.affiliation: Cold Spring Harbor Laboratory, Watson School of Biological Sciences and Howard Hughes Medical Institute, Cold Spring Harbor, New York, United States of America.
authors.forename: Nikolay V
authors.initials: NV
authors.lastname: Rozhkov
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Fan
authors.initials: F
authors.lastname: Li
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Fabián L
authors.initials: FL
authors.lastname: Cárdenas
authors.forename: Olga
authors.initials: O
authors.lastname: Davydenko
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Olga
authors.initials: O
authors.lastname: Davydenk
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Lee E
authors.initials: LE
authors.lastname: Vandivier
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Gregory
authors.affiliation: Cold Spring Harbor Laboratory, Watson School of Biological Sciences and Howard Hughes Medical Institute, Cold Spring Harbor, New York, United States of America; CRUK Cambridge Institute, Li Ka Shing Centre, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Hannon
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.
authors.forename: Richard M
authors.initials: RM
authors.lastname: Schultz
mesh_terms: D000818:Animals; D060565:Argonaute Proteins / Q000235:genetics*; D004251:DNA Transposable Elements / Q000235:genetics; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D005854:Germ Cells / Q000166:cytology / Q000378:metabolism; D007247:Infertility, Female / Q000235:genetics*; D008540:Meiosis / Q000235:genetics*; D051379:Mice; D035683:MicroRNAs / Q000235:genetics; D009865:Oocytes / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics* / Q000378:metabolism
chemical_list: D060565:Argonaute Proteins; D004251:DNA Transposable Elements; D035683:MicroRNAs; D034741:RNA, Small Interfering