Kühbandner S, Brummer S, Metzger D, Chambon P, Hofmann F, Feil R
Institut für Pharmakologie und Toxikologie, Technische Universität München, München, Germany.
Genesis. 2000 Sep;28(1):15-22. doi: 10.1002/1526-968x(200009)28:1<15::aid-gene20>3.0.co;2-c.
Ligand-dependent site-specific recombinases are powerful tools to engineer the mouse genome in specific somatic cell types at selected times during pre- and postnatal development. Current efforts are primarily directed towards increasing the efficiency of this recombination system in mice. We have generated transgenic mouse lines expressing a tamoxifen-activated Cre recombinase, CreER(T2), under the control of the smooth muscle-specific SM22 promoter. Both a randomly integrated transgene [SM-CreER(T2)(tg)] and a transgene that has been "knocked in" into the endogenous SM22 locus [SM-CreER(T2)(ki)] were expressed in smooth muscle-containing tissues. The level of CreER(T2) expression and tamoxifen-induced recombination was lower in SM-CreER(T2)(tg) mice compared with SM-CreER(T2)(ki) mice. Whereas no recombinase activity could be detected in vehicle-treated SM-CreER(T2)(ki) mice, administration of tamoxifen induced the excision of a loxP-flanked reporter transgene in up to 100% of smooth muscle cells. The recombined genome persisted for at least four months after tamoxifen treatment. SM-CreER(T2)(ki) transgenic mice should be useful to study the effects of various somatic mutations in smooth muscle.
配体依赖性位点特异性重组酶是在出生前和出生后发育的特定时间对特定体细胞类型的小鼠基因组进行工程改造的强大工具。目前的工作主要致力于提高该重组系统在小鼠中的效率。我们已经构建了在平滑肌特异性SM22启动子控制下表达他莫昔芬激活的Cre重组酶CreER(T2)的转基因小鼠品系。一个随机整合的转基因[SM-CreER(T2)(tg)]和一个“敲入”到内源性SM22基因座的转基因[SM-CreER(T2)(ki)]都在含有平滑肌的组织中表达。与SM-CreER(T2)(ki)小鼠相比，SM-CreER(T2)(tg)小鼠中CreER(T2)的表达水平和他莫昔芬诱导的重组水平较低。在用载体处理的SM-CreER(T2)(ki)小鼠中未检测到重组酶活性，而给予他莫昔芬可诱导高达100%的平滑肌细胞中loxP侧翼报告基因转基因的切除。他莫昔芬治疗后重组基因组持续至少四个月。SM-CreER(T2)(ki)转基因小鼠应该有助于研究平滑肌中各种体细胞突变的影响。
