Danielian P S, Muccino D, Rowitch D H, Michael S K, McMahon A P
Department of Molecular and Cellular Biology Harvard University 16 Divinity Avenue, Cambridge Massachusetts 02138 USA.
Curr Biol. 1998 Dec 3;8(24):1323-6. doi: 10.1016/s0960-9822(07)00562-3.
The ability to generate specific genetic modifications in mice provides a powerful approach to assess gene function. When genetic modifications have been generated in the germ line, however, the resulting phenotype often only reflects the first time a gene has an influence on - or is necessary for - a particular biological process. Therefore, systems allowing conditional genetic modification have been developed (for a review, see [1]); for example, inducible forms of the Cre recombinase from P1 phage have been generated that can catalyse intramolecular recombination between target recognition sequences (loxP sites) in response to ligand [2] [3] [4] [5]. Here, we assessed whether a tamoxifen-inducible form of Cre recombinase (Cre-ERTM) could be used to modify gene activity in the mouse embryo in utero. Using the enhancer of the Wnt1 gene to restrict the expression of Cre-ERTM to the embryonic neural tube, we found that a single injection of tamoxifen into pregnant mice induced Cre-mediated recombination within the embryonic central nervous system, thereby activating expression of a reporter gene. Induction was ligand dependent, rapid and efficient. The results demonstrate that tamoxifen-inducible recombination can be used to effectively modify gene function in the mouse embryo.
在小鼠中产生特定基因修饰的能力为评估基因功能提供了一种强大的方法。然而，当在生殖系中产生基因修饰时，所产生的表型往往仅反映基因首次对特定生物学过程产生影响或成为其必需条件的情况。因此，已经开发出了允许进行条件性基因修饰的系统（综述见[1]）；例如，已经产生了来自P1噬菌体的可诱导形式的Cre重组酶，其能够响应配体催化靶标识别序列（loxP位点）之间的分子内重组[2][3][4][5]。在此，我们评估了他莫昔芬诱导型Cre重组酶（Cre-ERTM）是否可用于在子宫内的小鼠胚胎中修饰基因活性。利用Wnt1基因的增强子将Cre-ERTM的表达限制在胚胎神经管，我们发现向怀孕小鼠单次注射他莫昔芬可诱导胚胎中枢神经系统内的Cre介导的重组，从而激活报告基因的表达。诱导是依赖配体的、快速且高效的。这些结果表明，他莫昔芬诱导的重组可用于有效修饰小鼠胚胎中的基因功能。
