Development of efficient gene disruption system in any tissues or organs

小鼠胚胎干（ES）细胞的基因破坏允许在建立目标ES细胞衍生的小鼠后研究内源性基因的功能。由于许多基因破坏会导致胚胎致死，因此不可能分析成年小鼠的特定基因功能。为了克服这些困难，我们采用了Cre/loxP系统。该系统允许以cre表达依赖的方式破坏具有相同定向loxP位点的基因。本研究尝试采用外源性和内源性两种方法将Cre重组酶导入小鼠基因组。对于前者，制备了含Gre的脂质体。在体外造血细胞中添加脂质体可导致含loxP基因的破坏（Pig-a）。然而，将这些细胞转移到受致命辐射的小鼠中，发现造血干细胞中没有发生猪-a破坏。这一结果表明，脂质体外源性Gre将Cre引入基因组有一定的局限性。对于后者，我们建立了一系列的转基因小鼠。Cre转基因在造血干细胞中非常有效。

Gene disruption in murine embryonic stem (ES) cells allows to study functions of endogenous genes after establishing mice derived from targeted ES cells. Since many gene disruptions cause embryonic lethality, it is not possible to analyze specific gene functions in adult mice. To circumvent these difficulties, we applied Cre/loxP system. The system allows to disrupt a gene flanked by identically oriented loxP sites with Cre-expression-dependent manner.In this study, we tried to apply two methods to introduce Cre recombinase into mouse genome, exogenous and endogenous way. For the former, liposome containing Gre was produced. Addition of the liposome to hematopoietic cells in vitro resulted in disruption of loxP containing gene (Pig-a). However, transfer of these cells into lethally irradiated mice revealed that Pig-a disruption did not occur in the hematopoietic stem cells. This result suggest that the exogenous Gre by the liposome has limitation to introduce Cre into the genome. For the latter, we established a series of Gre transgenic mice. Cre transgene worked very efficiently including hematopoietic stem cells.