DNA Topoisomerase 1a Promotes RNA-directed DNA Methylation and Histone Lysine 9 Dimethylation at Transposable Elements in Arabidopsis [RNA-Seq]

RNA-directed DNA methylation (RdDM) is a transcriptional silencing mechanism mediated by small and long noncoding RNAs produced by the plant-specific RNA polymerases Pol IV and Pol V, respectively. Through a chemical genetics screen with a luciferase-based DNA methylation reporter, LUCL, we found that camptothecin, a compound with anti-cancer properties that targets DNA topoisomerase 1a (TOP1a) was able to de-repress LUCL by reducing its DNA methylation and H3K9 dimethylation (H3K9me2) levels. Further studies with Arabidopsis top1a mutants showed that TOP1a promotes RdDM by facilitating the production of Pol V-dependent long non-coding RNAs, AGONAUTE4 recruitment and H3K9me2 deposition at transposable elements (TEs). Overall design: 5 small RNA libraries were sequenced

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Dinh TT, Gao L, Liu X, Li D, Li S, Zhao Y, O'Leary M, Le B, Schmitz RJ, Manavella PA, Li S, Weigel D, Pontes O, Ecker JR, Chen X