Article

An epigenetic role for maternally inherited piRNAs in transposon silencing.

Watson School of Biological Sciences, Howard Hughes Medical Institute, Cold Spring Harbor Laboratory (CSHL), 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.
Science (Impact Factor: 31.48). 12/2008; 322(5906):1387-92. DOI: 10.1126/science.1165171
Source: PubMed

ABSTRACT In plants and mammals, small RNAs indirectly mediate epigenetic inheritance by specifying cytosine methylation. We found that small RNAs themselves serve as vectors for epigenetic information. Crosses between Drosophila strains that differ in the presence of a particular transposon can produce sterile progeny, a phenomenon called hybrid dysgenesis. This phenotype manifests itself only if the transposon is paternally inherited, suggesting maternal transmission of a factor that maintains fertility. In both P- and I-element-mediated hybrid dysgenesis models, daughters show a markedly different content of Piwi-interacting RNAs (piRNAs) targeting each element, depending on their parents of origin. Such differences persist from fertilization through adulthood. This indicates that maternally deposited piRNAs are important for mounting an effective silencing response and that a lack of maternal piRNA inheritance underlies hybrid dysgenesis.

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