Maschio A, Brickell P M, Kioussis D, Mellor A L, Katz D, Craig R K
Department of Biochemistry, University College and Middlesex School of Medicine, London, U.K.
Biochem J. 1991 Apr 15;275 ( Pt 2)(Pt 2):459-67. doi: 10.1042/bj2750459.
We have generated transgenic mice carrying the entire guinea-pig alpha-lactalbumin gene. Lactating transgenic mice expressed high levels of correctly initiated and processed guinea-pig alpha-lactalbumin mRNA in the secretory epithelium of their mammary glands, and secreted guinea-pig alpha-lactalbumin in their milk. Transcripts were detectable after 7 days of pregnancy, indicating that the transgene was under correct hormonal control. Whereas no or negligible transcription was detectable in all other tissues tested, high levels of transcripts were found in the skin of lactating transgenic mice. Guinea-pig alpha-lactalbumin protein was undetectable in the skin, however. In situ hybridization analysis showed that expression was localized to the undifferentiated cells in the basal layer of the sebaceous glands. Further studies revealed high levels of endogenous beta-casein mRNA in normal lactating mouse skin, demonstrating that the transcription of milk protein genes in lactating mouse skin is a normal event, and is not peculiar to the transgene. This surprising finding highlights the developmental relationship of the mammary gland to other specialized structures of the skin, supports a role for epithelial-extracellular matrix interactions in the regulation of milk protein gene expression in vivo, and identifies the skin as a particularly accessible model system in which to study the regulation of milk protein gene expression. In addition, the guinea-pig alpha-lactalbumin gene will be a source of regulatory sequences with which to direct heterologous gene expression to the sebaceous glands of transgenic mice.
我们培育出了携带完整豚鼠α-乳白蛋白基因的转基因小鼠。泌乳的转基因小鼠在其乳腺的分泌上皮中表达高水平的正确起始和加工的豚鼠α-乳白蛋白mRNA，并在其乳汁中分泌豚鼠α-乳白蛋白。在怀孕7天后可检测到转录本，这表明转基因处于正确的激素控制之下。然而，在所有其他测试组织中未检测到或仅检测到可忽略不计的转录，而在泌乳转基因小鼠的皮肤中发现了高水平的转录本。不过，在皮肤中未检测到豚鼠α-乳白蛋白蛋白。原位杂交分析表明，表达定位于皮脂腺基底层的未分化细胞。进一步的研究揭示，正常泌乳小鼠皮肤中存在高水平的内源性β-酪蛋白mRNA，这表明泌乳小鼠皮肤中乳蛋白基因的转录是一个正常事件，并非转基因所特有。这一惊人发现突出了乳腺与皮肤其他特化结构的发育关系，支持上皮-细胞外基质相互作用在体内乳蛋白基因表达调控中的作用，并将皮肤确定为研究乳蛋白基因表达调控的一个特别易于研究的模型系统。此外，豚鼠α-乳白蛋白基因将成为调控序列的一个来源，可用于将异源基因表达定向到转基因小鼠的皮脂腺。
