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Vampiric Isolation of Extracellular Fluid from Caenorhabditis elegans

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Published on: March 19, 2012

Function, targets, and evolution of Caenorhabditis elegans piRNAs.

Marloes P Bagijn¹, Leonard D Goldstein¹, Alexandra Sapetschnig¹

¹Gurdon Institute and Department of Biochemistry, University of Cambridge, The Henry Wellcome Building of Cancer and Developmental Biology, Tennis Court Rd, Cambridge CB2 1QN, UK.

Science (New York, N.Y.)

|June 16, 2012

Summary

Piwi-interacting RNAs (piRNAs) in C. elegans silence genes via secondary small RNA responses, not direct slicing. These piRNAs target transposons, ensuring germline integrity and fertility by triggering RNA interference.

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Area of Science:

Molecular Biology
Genetics
RNA Biology

Background:

Piwi-interacting RNAs (piRNAs) are crucial for maintaining germline integrity and fertility in many organisms.
The precise molecular mechanisms by which piRNAs exert their regulatory functions, particularly in trans-acting silencing, remain incompletely understood.

Purpose of the Study:

To elucidate the mechanism of action for piRNAs in Caenorhabditis elegans.
To investigate the role of piRNAs in silencing endogenous gene and transposon transcripts.
To explore the evolutionary relationship between piRNA clusters and mobile genetic elements.

Main Methods:

Analysis of piRNA-mediated transcript silencing in Caenorhabditis elegans.
Investigation of Piwi endonuclease activity and its role in silencing.
Characterization of secondary endogenous small interfering RNA (endo-siRNA) responses.
Examination of genomic loci associated with piRNA biogenesis.

Main Results:

C. elegans piRNAs silence transcripts in trans through imperfectly complementary sites, independent of Piwi endonuclease activity or slicing.
piRNAs initiate a localized secondary endo-siRNA response, leading to Piwi-dependent endo-siRNAs on target transcripts.
Protein-coding genes and transposons targeted by piRNAs show derepression in Piwi mutants.
Genomic piRNA biogenesis loci are depleted of protein-coding genes and overlap transposon boundaries.

Conclusions:

piRNAs in C. elegans function as heritable, sequence-specific triggers for RNA interference.
The piRNA pathway utilizes secondary endo-siRNA generation for transcript silencing.
Nematode piRNA clusters appear to be evolving to target active mobile genetic elements, contributing to genome stability.