Targeted 3′ Processing of Antisense Transcripts Triggers Arabidopsis FLC Chromatin Silencing

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Science  03 Dec 2009:
DOI: 10.1126/science.1180278


Noncoding RNA is emerging as an important regulator of gene expression in many organisms. We are characterizing RNA-mediated chromatin silencing of the Arabidopsis major floral repressor gene, FLC. Through suppressor mutagenesis, we identify a requirement for CstF64 and CstF77, two conserved RNA 3′-end-processing factors, in FLC silencing. However, FLC sense transcript 3′ processing is not affected in the mutants. Instead, CstF64 and CstF77 are required for 3′ processing of FLC antisense transcripts. A specific RNA-binding protein directs their activity to a proximal antisense polyadenylation site. This targeted processing triggers localized histone demethylase activity and results in reduced FLC sense transcription. Targeted 3′ processing of antisense transcripts may be a common mechanism triggering transcriptional silencing of the corresponding sense gene.