title: Transcriptional control of gene expression by microRNAs.
abstract: MicroRNAs (miRNAs) control gene expression in animals and plants. Like another class of small RNAs, siRNAs, they affect gene expression posttranscriptionally. While siRNAs in addition act in transcriptional gene silencing, a role of miRNAs in transcriptional regulation has been less clear. We show here that in moss Physcomitrella patens mutants without a DICER-LIKE1b gene, maturation of miRNAs is normal but cleavage of target RNAs is abolished and levels of these transcripts are drastically reduced. These mutants accumulate miRNA:target-RNA duplexes and show hypermethylation of the genes encoding target RNAs, leading to gene silencing. This pathway occurs also in the wild-type upon hormone treatment. We propose that initiation of epigenetic silencing by DNA methylation depends on the ratio of the miRNA and its target RNA.
authors.affiliation: Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestrasse 1, 79104 Freiburg, Germany.
authors.forename: Basel
authors.initials: B
authors.lastname: Khraiwesh
authors.forename: M Asif
authors.initials: MA
authors.lastname: Arif
authors.forename: Gotelinde I
authors.initials: GI
authors.lastname: Seumel
authors.forename: Stephan
authors.initials: S
authors.lastname: Ossowski
authors.forename: Detlef
authors.initials: D
authors.lastname: Weigel
authors.forename: Ralf
authors.initials: R
authors.lastname: Reski
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Frank
mesh_terms: D001483:Base Sequence; D019068:Bryopsida / Q000235:genetics* / Q000378:metabolism*; D019175:DNA Methylation; D005786:Gene Expression Regulation; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering; D014158:Transcription, Genetic
chemical_list: D035683:MicroRNAs; D010940:Plant Proteins; D018749:RNA, Plant; D034741:RNA, Small Interfering