Paramutation: From Maize to Mice

@article{Chandler2007ParamutationFM,
  title={Paramutation: From Maize to Mice},
  author={Vicki L. Chandler},
  journal={Cell},
  year={2007},
  volume={128},
  pages={641-645}
}
  • V. Chandler
  • Published 23 February 2007
  • Biology, Medicine
  • Cell
Paramutation is the epigenetic transfer of information from one allele of a gene to another to establish a state of gene expression that is heritable for generations. RNA has recently emerged as a prominent mediator of this remarkable phenomenon in both maize and mice. 

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References

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TLDR
Potential mechanisms underlying paramutation are discussed, several other trans-sensing phenomena are compared, and the potential roles and evolutionary implications of these intriguing homology-Sensing mechanisms are speculated on.
Paramutation in maize
TLDR
Several potential roles for paramutation include localizing recombination to low-copy sequences within the genome, establishing and maintaining chromatin domain boundaries, and providing a mechanism for plants to transmit an environmentally influenced expression state to progeny.
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TLDR
Tandem repeats are prone to epigenetic silencing regulated by RNA interference, but siRNAs from single-copy sequences are exhausted by sequential use of downstream primers by RdRP, which could account for the formation of heterochromatin from tandem repeats.
An RNA-dependent RNA polymerase is required for paramutation in maize
TLDR
It is proposed that the mop1 RDRP is required to maintain a threshold level of repeat RNA, which functions in trans to establish and maintain the heritable chromatin states associated with paramutation.
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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.
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TLDR
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TLDR
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TLDR
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TLDR
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TLDR
Interestingly, this immunity to silencing increased as the generations progressed, consistent with a heritable chromatin state being formed at the transgene in plants carrying the mop1-1 and rmr2-1 mutations that becomes more resistant tosilencing in subsequent generations.
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