Barash I, Faerman A, Ratovitsky T, Puzis R, Nathan M, Hurwitz D R, Shani M
Institute of Animal Science, Volcani Center, Bet Dagan, Israel.
Transgenic Res. 1994 May;3(3):141-51. doi: 10.1007/BF01973981.
We produced transgenic mice carrying the native sheep beta-lactoglobulin (BLG) or fusion genes composed of the BLG promoter and human serum albumin (HSA) minigenes. BLG was expressed exclusively in the mammary glands of the virgin and lactating transgenic mice evaluated. In contrast, transgenic females carrying the BLG/HSA fusion constructs also expressed the HSA RNA ectopically in skeletal muscle, kidney, brain, spleen, salivary gland and skin. Ectopic expression of HSA RNA was detected only in strains that express the transgene in the mammary gland. There was no obvious correlation between the level of the HSA RNA expressed in the mammary gland and that found ectopically. In three transgenic strains analysed, the expression of HSA RNA in kidney and skeletal muscle increased during pregnancy and lactation, whereas in the brain HSA expression decreased during lactation in one of the strains. HSA protein was synthesized in skeletal muscle and skin of strain #23 and its level was higher in lactating mice compared with virgin mice. Expression of HSA was also analysed in males and was found to be more stringently controlled than in females of the same strains. In situ hybridization analyses localized the expressed transgene in the skin, kidney, brain and salivary glands of various transgenic strains. Distinct strain-specific and cell-type specific HSA expression patterns were observed in the skin. This is in contrast to the exclusive expression of the HSA transgene in epithelial cells surrounding the alveoli of the mammary gland. Taken together, these results suggest that the absence of sufficient mammary-specific regulatory elements in the BLG promoter sequences and/or the juxtaposition of the BLG promoter with the HSA coding sequences leads to novel tissue- and cell-specific expression in ectopic tissues of transgenic mice.
我们培育了携带天然绵羊β-乳球蛋白（BLG）或由BLG启动子与人血清白蛋白（HSA）小基因组成的融合基因的转基因小鼠。在所评估的处女和泌乳转基因小鼠中，BLG仅在乳腺中表达。相比之下，携带BLG/HSA融合构建体的转基因雌性小鼠在骨骼肌、肾脏、大脑、脾脏、唾液腺和皮肤中也异位表达HSA RNA。仅在乳腺中表达转基因的品系中检测到HSA RNA的异位表达。乳腺中表达的HSA RNA水平与异位表达的水平之间没有明显的相关性。在分析的三个转基因品系中，肾脏和骨骼肌中HSA RNA的表达在怀孕和泌乳期间增加，而在其中一个品系中，大脑中的HSA表达在泌乳期间下降。HSA蛋白在品系#23的骨骼肌和皮肤中合成，与处女小鼠相比，泌乳小鼠中的HSA蛋白水平更高。还对雄性小鼠中的HSA表达进行了分析，发现其表达比同品系的雌性小鼠受到更严格的控制。原位杂交分析将表达的转基因定位在各种转基因品系的皮肤以及肾脏、大脑和唾液腺中。在皮肤中观察到了明显的品系特异性和细胞类型特异性HSA表达模式。这与HSA转基因仅在乳腺腺泡周围的上皮细胞中表达形成对比。综上所述，这些结果表明，BLG启动子序列中缺乏足够的乳腺特异性调控元件和/或BLG启动子与HSA编码序列的并列导致转基因小鼠异位组织中出现新的组织和细胞特异性表达。
