An RNA-dependent RNA polymerase is required for paramutation in maize

@article{Alleman2006AnRR,
  title={An RNA-dependent RNA polymerase is required for paramutation in maize},
  author={Mary M. Alleman and Lyudmila V Sidorenko and Karen M. McGinnis and Vishwas Seshadri and Jane E. Dorweiler and Joshua P. White and Kristin L Sikkink and Vicki L. Chandler},
  journal={Nature},
  year={2006},
  volume={442},
  pages={295-298}
}
Paramutation is an allele-dependent transfer of epigenetic information, which results in the heritable silencing of one allele by another. Paramutation at the b1 locus in maize is mediated by unique tandem repeats that communicate in trans to establish and maintain meiotically heritable transcriptional silencing. The mop1 (mediator of paramutation1) gene is required for paramutation, and mop1 mutations reactivate silenced Mutator elements. Plants carrying mutations in the mop1 gene also… 
RNA-mediated trans-communication can establish paramutation at the b1 locus in maize
TLDR
A role for mop1 is uncovered in the biogenesis of a subset of microRNAs (miRNAs) and it is uncovered that it functions at the level of production of the primary miRNA transcripts.
RNA-Dependent RNA Polymerase Is Required for Enhancer-Mediated Transcriptional Silencing Associated With Paramutation at the Maize p1 Gene
TLDR
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Specific Tandem Repeats Are Sufficient for Paramutation-Induced Trans-Generational Silencing
TLDR
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TLDR
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TLDR
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TLDR
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A Novel Snf2 Protein Maintains trans-Generational Regulatory States Established by Paramutation in Maize
TLDR
The RNA component of maize paramutation maintains small heterochromatic-like domains that can affect the stability of nascent transcripts from adjacent genes by way of a cotranscriptional repression process, highlighting a mechanism by which alleles of endogenous loci can acquire novel expression patterns that are meiotically transmissible.
Diverse Gene-Silencing Mechanisms with Distinct Requirements for RNA Polymerase Subunits in Zea mays
TLDR
A speculative hypothesis of locus-specific deployment of Pol II, Mop2-containing Pol V, or alternative versions of Pol V with second largest subunits other than MOP2 is proposed to explain the mechanistic differences in silencing at specific loci, including one example associated with paramutation.
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References

SHOWING 1-10 OF 32 REFERENCES
mediator of paramutation1 Is Required for Establishment and Maintenance of Paramutation at Multiple Maize Loci
TLDR
The observation that mop1 affects paramutation at multiple loci, despite major differences between these loci in their gene structure, correlations with DNA methylation, and stability of the paramutant state, suggests that a common mechanism underlies paramutation.
A mutation that prevents paramutation in maize also reverses Mutator transposon methylation and silencing
TLDR
It is shown that mutation of a gene, modifier of paramutation 1 (mop1), which prevents paramutation at three different loci in maize, can reverse methylation of Mutator elements reliably, and suggests that the mop1 gene acts on a subset of epigenetically regulated sequences in the maize genome.
Genetic factors required to maintain repression of a paramutagenic maize pl1 allele.
TLDR
Results suggest that RMR functions are intimately involved in maintaining the repressed expression state of paramutant Pl' alleles, and despite strong effects on Pl' repression, rmr mutant plants have no gross developmental abnormalities even after several generations of inbreeding, implying that R MR1 and RMR2 functions are not generally required for developmental homeostasis.
RNA-dependent RNA polymerase is an essential component of a self-enforcing loop coupling heterochromatin assembly to siRNA production.
TLDR
It is shown that a point mutation within the catalytic domain of Rdp1 abolished its RNA-dependent RNA polymerase activity and resulted in the loss of transcriptional silencing and heterochromatin at centromeres, together with defects in mitotic chromosome segregation and telomere clustering.
Differential Regulation of Strand-Specific Transcripts from Arabidopsis Centromeric Satellite Repeats
TLDR
Roles for transcribed repeats in the epigenetic inheritance and evolution of centromeres are proposed and Histone H3 lysine-9 dimethylation is associated with both classes of repeats.
RNA-mediated non-mendelian inheritance of an epigenetic change in the mouse
TLDR
This work reports a similar modification of the mouse Kit gene in the progeny of heterozygotes with the null mutant Kittm1Alf (a lacZ insertion), identifying an unexpected mode of epigenetic inheritance associated with the zygotic transfer of RNA molecules.
Properties of Unpaired DNA Required For Efficient Silencing in Neurospora crassa
TLDR
Using the Ascospore maturation-1 (Asm-1) gene, this work defined what needs to be “unpaired” to silence a gene and detected the unpairing-dependent loss of a transcript during meiotic silencing.
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