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"Biotech and Mol Bio"
Research and innovation in Molecular Biology and Biotechnology (by @ramossonia)
Curated by sonia ramos
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Rescooped by sonia ramos from Arabidopsis
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RNA Polymerase V targets transcriptional silencing components to promoters of protein-coding genes - Zheng - The Plant Journal - Wiley Online Library

RNA Polymerase V targets transcriptional silencing components to promoters of protein-coding genes - Zheng - The Plant Journal - Wiley Online Library | "Biotech and Mol Bio" | Scoop.it

Summary

Transcriptional gene silencing controls transposons and other repetitive elements through RNA-directed DNA methylation (RdDM) and heterochromatin formation. A key component of the Arabidopsis RdDM pathway is ARGONAUTE4 (AGO4), which associates with siRNAs to mediate DNA methylation. Here, we show that AGO4 preferentially targets transposable elements embedded within promoters of protein-coding genes. We find that this pattern of AGO4 binding cannot be simply explained by the sequences of AGO4-bound siRNAs, but instead AGO4 binding to specific gene promoters is also mediated by long non-coding RNAs (lncRNAs) produced by RNA Polymerase V. lncRNA-mediated AGO4 binding to gene promoters directs asymmetric DNA methylation to these genomic regions and is involved in regulating the expression of targeted genes. Finally, AGO4-binding overlaps sites of DNA methylation affected by biotic stress response. Based on these findings, we propose that targets of AGO4-directed RdDM are regulatory units responsible for controlling gene expression under specific environmental conditions.

 

© 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd


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hedgeshandy's comment, October 17, 2013 6:31 AM
Its interesting
Rescooped by sonia ramos from Arabidopsis
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A histone acetyltransferase regulates active DNA demethylation in Arabidopsis (Science)

A histone acetyltransferase regulates active DNA demethylation in Arabidopsis (Science) | "Biotech and Mol Bio" | Scoop.it

Active DNA demethylation is an important part of epigenetic regulation in plants and animals. How active DNA demethylation is regulated and its relationship with histone modification patterns are unclear. Here, we report the discovery of IDM1, a regulator of DNA demethylation in Arabidopsis. IDM1 is required for preventing DNA hypermethylation of highly homologous multicopy genes and other repetitive sequences that are normally targeted for active DNA demethylation by Repressor of Silencing 1 and related 5-methylcytosine DNA glycosylases. IDM1 binds methylated DNA at chromatin sites lacking histone H3K4 di- or trimethylation and acetylates H3 to create a chromatin environment permissible for 5-methylcytosine DNA glycosylases to function. Our study reveals how some genes are indicated by multiple epigenetic marks for active DNA demethylation and protection from silencing.


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