Differential impact of the HEN1 homolog HENN-1 on 21U and 26G RNAs in the germline of Caenorhabditis elegans.

RNA interference (RNAi)-related pathways affect gene activity by sequence-specific recruitment of Ago proteins to mRNA target molecules. The sequence specificity of this process stems from small RNA (sRNA) co-factors bound by the Ago protein. Stability of sRNA molecules in some pathways is in part regulated by Hen1-mediated methylation of their 3' ends.

piRNAs can trigger a multigenerational epigenetic memory in the germline of C. elegans.

Transgenerational effects have wide-ranging implications for human health, biological adaptation, and evolution; however, their mechanisms and biology remain poorly understood. Here, we demonstrate that a germline nuclear small RNA/chromatin pathway can maintain stable inheritance for many generations when triggered by a piRNA-dependent foreign RNA response in C. elegans.

Function, targets, and evolution of Caenorhabditis elegans piRNAs.

Piwi-interacting RNAs (piRNAs) are small RNAs required to maintain germline integrity and fertility, but their mechanism of action is poorly understood. Here we demonstrate that Caenorhabditis elegans piRNAs silence transcripts in trans through imperfectly complementary sites. Target silencing is independent of Piwi endonuclease activity or "slicing.

Piwi and piRNAs act upstream of an endogenous siRNA pathway to suppress Tc3 transposon mobility in the Caenorhabditis elegans germline.

The Piwi proteins of the Argonaute superfamily are required for normal germline development in Drosophila, zebrafish, and mice and associate with 24-30 nucleotide RNAs termed piRNAs. We identify a class of 21 nucleotide RNAs, previously named 21U-RNAs, as the piRNAs of C. elegans.