Variegated transgene expression in mouse mammary gland is determined by the transgene integration locus
Variegated transgene expression in mouse mammary gland is determined by the transgene integration locus
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DOI：
10.1073/pnas.93.13.6659
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发表时间：
1996-06-25
影响因子：
11.1
通讯作者：
McClenaghan, M
中科院分区：
文献类型：
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作者：
Dobie, KW;Lee, M;McClenaghan, M
携带绵羊β-乳球蛋白（BLG）转基因的小鼠将BLG蛋白分泌到它们的乳汁中。为了探索转基因表达的稳定性，我们研究了三个BLG转基因小鼠系中的表达水平。出乎意料的是，两个品系表现出不同水平的转基因表达。品系内的拷贝数似乎是稳定的，并且没有转基因重排的证据。在最可变的系中，BLG生产水平在两次连续哺乳中在个体小鼠内稳定。回交证明遗传背景对变量表达没有显着贡献。组织原位杂交显示镶嵌的转基因表达的个体乳腺内的两个可变线，在低表达，离散补丁的细胞表达转基因观察。牛奶中转基因蛋白浓度反映了表达BLG mRNA的上皮细胞的比例。此外，染色体原位杂交显示，转基因阵列在两个线位于靠近着丝粒。我们提出，嵌合的转基因表达是染色体的位置和/或主要的转基因整合事件的性质的后果。
Mice carrying an ovine beta-lactoglobulin (BLG) transgene secrete BLG protein into their milk. To explore transgene expression stability, we studied expression levels in three BLG transgenic mouse lines. Unexpectedly, two lines exhibited variable levels of transgene expression. Copy number within lines appeared to be stable and there was no evidence of transgene rearrangement. In the most variable line, BLG production levels were stable within individual mice in two successive lactations. Backcrossing demonstrated that genetic background did not contribute significantly to variable expression. Tissue in situ hybridization revealed mosaicism of transgene expression within individual mammary glands from the two variable lines; in low expressors, discrete patches of cells expressing the transgene were observed. Transgene protein concentrations in milk reflected the proportion of epithelial cells expressing BLG mRNA. Furthermore, chromosomal in situ hybridization revealed that transgene arrays in both lines are situated close to the centromere. We propose that mosaicism of transgene expression is a consequence of the chromosomal location and/or the nature of the primary transgene integration event.