Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America.
PLoS One. 2011 May 10;6(5):e18778. doi: 10.1371/journal.pone.0018778.
Transgenes flanked by loxP sites have been widely used to generate transgenic mice where the transgene expression can be controlled spatially and temporally by Cre recombinase. Data from this approach has led to important conclusions in cancer, neurodevelopment and neurodegeneration. Using this approach to conditionally express micro RNAs (miRNAs) in mice, we found that Cre-mediated recombination in neural progenitor cells caused microcephaly in five of our ten independent transgenic lines. This effect was not associated with the types or the quantity of miRNAs being expressed, nor was it associated with specific target knockdown. Rather, it was correlated with the presence of multiple tandem transgene copies and inverted (head-to-head or tail-to-tail) transgene repeats. The presence of these inverted repeats caused a high level of cell death in the ventricular zone of the embryonic brain, where Cre was expressed. Therefore, results from this Cre-loxP approach to generate inducible transgenic alleles must be interpreted with caution and conclusions drawn in previous reports may need reexamination.
带有 loxP 位点的转基因已被广泛用于生成转基因小鼠，通过 Cre 重组酶可以实现转基因的时空表达调控。该方法的数据在癌症、神经发育和神经退行性变领域得出了重要结论。我们使用这种方法在小鼠中条件性表达 microRNAs（miRNAs），发现 Cre 介导的神经祖细胞中的重组导致我们的十个独立转基因品系中的五个出现小头畸形。这种效应与表达的 miRNAs 的类型或数量无关，也与特定靶标敲低无关。相反，它与多个串联转基因拷贝和倒置（头对头或尾对尾）转基因重复的存在相关。这些倒置重复的存在导致 Cre 表达的胚胎大脑室管膜区出现高水平的细胞死亡。因此，通过 Cre-loxP 方法生成诱导型转基因等位基因的结果必须谨慎解释，并且以前报告中的结论可能需要重新审查。
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