Transcriptional control of gene expression by microRNAs.
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.
Khraiwesh
Basel
B
Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestrasse 1, 79104 Freiburg, Germany.
Arif
M Asif
MA
Seumel
Gotelinde I
GI
Ossowski
Stephan
S
Weigel
Detlef
D
Reski
Ralf
R
Frank
Wolfgang
W
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
D035683:MicroRNAs; D010940:Plant Proteins; D018749:RNA, Plant; D034741:RNA, Small Interfering