Heritable and stable gene knockdown in rats

The rat has served as an excellent model for studies on animal physiology and as a model for human diseases such as diabetes and alcoholism; however, genetic studies have been limited because of the inability to knock out genes. Our goal was to produce heritable deficiencies in specific gene function in the rat using RNA interference to knock down gene expression in vivo. Lentiviral-mediated transgenesis was used to produce rats expressing a short hairpin RNA targeting Dazl, a gene expressed in germ cells and required for fertility in mice [Ruggiu, M., Speed, R., Taggart, M., McKay, S. J., Kilanowski, F., Saunders, P., Dorin, J. & Cooke, H. J. (1997) Nature 389, 73–77]. Germ-line transmission of the transgene occurred, and its expression correlated with significant reductions in DAZL protein levels and male sterility, and the knockdown was stable over multiple generations (F1–F3). This study demonstrates an efficient system by which directed reverse genetic analysis can now be performed in the rat.