Eckardt Dominik, Theis Martin, Döring Britta, Speidel Dina, Willecke Klaus, Ott Thomas
Genesis. 2004 Apr;38(4):159-65. doi: 10.1002/gene.20011.
Conditional gene targeting using the Cre/loxP technology generally includes integration of a selection marker cassette flanked by loxP recognition sites (floxed) in the target gene locus. Subsequent marker removal avoids possible impairment of gene expression or mosaicism due to partial and total deletions after Cre-mediated recombination in vivo. The use of deleter Cre mice for in vivo marker removal in floxed connexin43 mice revealed considerable mosaicism, but no selective marker removal. In addition, we noted that several Cre transgenic lines displayed spontaneous ectopic activity, reminiscent of deleter Cre mice, and required the confirmation of cell type-specific deletion in every individual mouse. When we used myosin heavy chain promoter Cre (alphaMyHC-Cre) mice for cardiomyocyte specific deletion, we observed, in addition to cardiomyocyte-restricted or complete excision, selective marker removal in a subgroup of mice as well. Thus, selective marker removal can be achieved as a byproduct of cell-type restricted deletion.
使用Cre/loxP技术进行条件性基因靶向通常包括在靶基因位点整合一个两侧带有loxP识别位点（floxed）的选择标记盒。随后去除标记可避免因体内Cre介导的重组后部分和完全缺失导致的基因表达受损或嵌合现象。在floxed连接蛋白43小鼠中使用Cre删除小鼠进行体内标记去除，发现有相当程度的嵌合现象，但没有选择性标记去除。此外，我们注意到几个Cre转基因品系表现出自发性异位活性，这与Cre删除小鼠类似，并且需要在每只小鼠中确认细胞类型特异性缺失。当我们使用肌球蛋白重链启动子Cre（αMyHC-Cre）小鼠进行心肌细胞特异性缺失时，除了心肌细胞限制性或完全切除外，我们还在一小部分小鼠中观察到了选择性标记去除。因此，选择性标记去除可以作为细胞类型限制性缺失的副产品实现。
