Chromosome Research

, Volume 21, Issue 6–7, pp 573–586 | Cite as

A multitasking Argonaute: exploring the many facets of C. elegans CSR-1

  • Christopher J. Wedeles
  • Monica Z. Wu
  • Julie M. Claycomb


While initial studies of small RNA-mediated gene regulatory pathways focused on the cytoplasmic functions of such pathways, identifying roles for Argonaute/small RNA pathways in modulating chromatin and organizing the genome has become a topic of intense research in recent years. Nuclear regulatory mechanisms for Argonaute/small RNA pathways appear to be widespread, in organisms ranging from plants to fission yeast, Caenorhabditis elegans to humans. As the effectors of small RNA-mediated gene regulatory pathways, Argonaute proteins guide the chromatin-directed activities of these pathways. Of particular interest is the C. elegans Argonaute, chromosome segregation and RNAi deficient (CSR-1), which has been implicated in such diverse functions as organizing the holocentromeres of worm chromosomes, modulating germline chromatin, protecting the genome from foreign nucleic acid, regulating histone levels, executing RNAi, and inhibiting translation in conjunction with Pumilio proteins. CSR-1 interacts with small RNAs known as 22G-RNAs, which have complementarity to 25 % of the protein coding genes. This peculiar Argonaute is the only essential C. elegans Argonaute out of 24 family members in total. Here, we summarize the current understanding of CSR-1 functions in the worm, with emphasis on the chromatin-directed activities of this ever-intriguing Argonaute.


Small RNA Argonaute Gene regulatory pathway Chromatin C. elegans 





Co-suppression defective-1


Chromosome segregation and RNAi deficient-1


Chromatin immunoprecipitation




Dicer-related helicase-3


Double-stranded RNA


Enhancer of KSR-1 lethality-1


Enhancer of GLP-1


Enhanced RNAi


fem-3 mRNA binding factor


Holocentromere protein 3/centromeric protein A


Heritable RNA deficient-1


Histone variant H2AZ homolog


Model organism encyclopedia of DNA elements




P-element induced wimpy testes


RNAi deficient


RNA-dependent RNA polymerase


Exogenous RNA interference


Secondary Argonaute


Stem loop binding protein


Worm Argonaute



We are grateful to Michelle Francisco and other members of the Claycomb lab as well as Dr. Andrew Spence for insightful discussions regarding the many functions of our favorite Argonaute, CSR-1. J.M.C. is The Canada Research Chair in Small RNA Biology. C.J.W. was supported by a CIHR Banting and Best Master’s Fellowship. M.W. was supported by an Ontario Graduate Scholarship. Research in the Claycomb lab is supported by CIHR Grants MOP-274660, and CAP-262134, and NSERC Grant RGPIN-418.


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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Christopher J. Wedeles
    • 1
  • Monica Z. Wu
    • 1
  • Julie M. Claycomb
    • 1
  1. 1.Department of Molecular GeneticsUniversity of TorontoTorontoCanada

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