@article{1821c2dd3218402a874e26b9328b0637,
title = "Multimegabase Silencing in Nucleolar Dominance Involves siRNA-Directed DNA Methylation and Specific Methylcytosine-Binding Proteins",
abstract = "In genetic hybrids, the silencing of nucleolar rRNA genes inherited from one progenitor is the epigenetic phenomenon known as nucleolar dominance. An RNAi knockdown screen identified the Arabidopsis de novo cytosine methyltransferase, DRM2, and the methylcytosine binding domain proteins, MBD6 and MBD10, as activities required for nucleolar dominance. MBD10 localizes throughout the nucleus, but MBD6 preferentially associates with silenced rRNA genes and does so in a DRM2-dependent manner. DRM2 methylation is thought to be guided by siRNAs whose biogenesis requires RNA-DEPENDENT RNA POLYMERASE 2 (RDR2) and DICER-LIKE 3 (DCL3). Consistent with this hypothesis, knockdown of DCL3 or RDR2 disrupts nucleolar dominance. Collectively, these results indicate that in addition to directing the silencing of retrotransposons and noncoding repeats, siRNAs specify de novo cytosine methylation patterns that are recognized by MBD6 and MBD10 in the large-scale silencing of rRNA gene loci.",
keywords = "DNA, PROTEINS, RNA",
author = "Preuss, {Sasha B.} and Pedro Costa-Nunes and Sarah Tucker and Olga Pontes and Lawrence, {Richard J.} and Rebecca Mosher and Kasschau, {Kristin D.} and Carrington, {James C.} and Baulcombe, {David C.} and Wanda Viegas and Pikaard, {Craig S.}",
note = "Funding Information: S.P. conducted DNA methyltransferase and MBD knockdown screens as well as S1 nuclease protection, RT-PCR, DNA methylation, and ChIP analyses of these RNAi lines. P.C.N. performed siRNA blots, DCL3, and RDR2 knockdown screens and related S1 nuclease protection and RT-PCR assays of these lines. O.P. performed all microscopy. S.T. performed bioinformatic analyses identifying the hypermethylated intergenic spacer site and generated the figures showing siRNA positions and abundance. R.M, D.B., K.K., and J.C. provided siRNA deep sequencing data. W.V. and C.S.P. comentored P.C.N. C.S.P. wrote the manuscript. Pikaard lab research was supported by United States NIH grant no. GM60380. RNAi vector development was supported by United States National Science Foundation grant no. 9975930. P.C.N. was supported by fellowships SFRH/BD/6520/2001 and SFRH/BPD/30386/2006 from the Funda{\c c}{\~a}o para a Ci{\^e}ncia e Tecnologia, Portugal. The content of this paper is solely the responsibility of the authors and does not necessarily reflect the views of our sponsors.",
year = "2008",
month = dec,
day = "5",
doi = "10.1016/j.molcel.2008.11.009",
language = "English (US)",
volume = "32",
pages = "673--684",
journal = "Molecular cell",
issn = "1097-2765",
publisher = "Cell Press",
number = "5",
}