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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2006-486v1 85/13_suppl/E18    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Anthony, R. V. Articles by Cantlon, J. D. Search for Related Content PubMed PubMed Citation Articles by Anthony, R. V. Articles by Cantlon, J. D.

Ribonucleic acid interference: A new approach to the in vivo study of gene function¹

Animal Reproduction and Biotechnology Laboratory, Department of Biomedical Sciences, Colorado State University, Fort Collins 80523-1683

² Corresponding author: russ.anthony{at}colostate.edu

The definition of hormone function was classically accomplished by ablation-replacement studies. However, as our knowledge of the complexity of hormones and growth factors has grown, it has become increasingly difficult to clearly define the necessity and function of many of the hormones, growth factors, and regulatory proteins under investigation. The use of homologous recombination within mouse embryonic stem cell lines allows functional gene ablation and has been used extensively during the past 15 yr to define specific gene function. The use of similar methodologies in livestock species has yet to yield an efficient approach. In contrast, the parallel development of our understanding of naturally occurring RNA interference, along with the development of efficient virus-based vectors for gene transfer, holds great potential for effectively "knocking down" specific gene function. Short-hairpin (sh) RNA-encoding cassettes, typically consisting of inverted repeats separated by a loop sequence and followed by a short poly(T) string to terminate transcription, are inserted downstream of an RNA polymerase III promoter within the viral vector of choice. Several viral vectors are useful for delivery of shRNA expression cassettes, each with particular attributes. Adenovirus- and lentivirus-derived vectors provide a high rate of infectivity in most mammalian cell types, with lentiviral vectors allowing stable integration into the host genome if the study of long-term effects is needed. Upon transcription, a shRNA is generated, and the loop is recognized by the processing enzyme Dicer, generating guide sequences. Guide sequences are incorporated into the RNA-induced silencing complex, which targets mRNA for degradation if recognized by the guide sequence. For each mRNA of interest, design and testing of a number of shRNA, along with adequate controls, are required to identify the most efficient construct before proceeding to in vivo use. This technology may become the method of choice for defining gene function in livestock.

Key Words: ribonucleic acid interference • gene ablation • virus-mediated infection