Al-Shawi R, Burke J, Jones C T, Simons J P, Bishop J O
Department of Genetics, University of Edinburgh, Scotland.
Mol Cell Biol. 1988 Nov;8(11):4821-8. doi: 10.1128/mcb.8.11.4821-4828.1988.
A hybrid gene was made by fusing the 2.2-kilobase 5' promoter region of a mouse group 1 major urinary protein (Mup) gene to the coding region of the herpes simplex virus type 1 thymidine kinase gene (HSV tk) and introduced into the genomes of mice by microinjection. Transgenic G0 males were sterile, or when fertile did not transmit the foreign gene, and the transgenic male descendants of G0 females were also sterile. Seven "lines" were established by breeding from G0 females and their transgenic female descendants. Six lines expressed HSV thymidine kinase activity in the liver, and activity correlated perfectly with the presence of HSV tk RNA. In three of four lines examined, expression was lower in female than in male liver, and in these lines the same sex difference was observed in the rate of run-on transcription of the foreign genes in liver nuclei. When females of one of the sexually dimorphic lines were treated with testosterone, the levels of HSV tk RNA and thymidine kinase activity were increased, although not to male levels. In these aspects of liver expression, and also in a lack of expression in seven other tissues, the hybrid gene exhibits many of the characteristics of an endogenous group 1 Mup gene. However, the gene was also expressed (at high levels) in the preputial gland and testis, two tissues in which Mup genes are not expressed. The gene, when introduced into five of the seven lines, carried a copy of the Escherichia coli supF gene attached beyond the 3' end of the HSV tk gene, but this did not affect the overall expression pattern. All of the lines were male sterile and expressed HSV thymidine kinase in the testis, but one line showed no activity in the liver, and another showed none in the preputial gland. Testicular expression is therefore the likely cause of sterility. Data are described which suggest that the causes of misexpression in the preputial gland and testis are different. Since expression in each tissue occurred in several lines, the structure of the hybrid gene must be responsible in each case. Five intensively studied lines showed at least four consistently different patterns of relative expression in preputial gland, testis, male liver, and female liver. These differences do not correlate in any way with the copy number of the foreign gene in the different lines and must be due to some other aspect of line specific integration.
通过将小鼠1组主要尿蛋白（Mup）基因的2.2千碱基5'启动子区域与单纯疱疹病毒1型胸苷激酶基因（HSV tk）的编码区域融合，构建了一个杂种基因，并通过显微注射将其导入小鼠基因组。转基因G0雄性小鼠不育，或者即便可育也不传递外源基因，而G0雌性小鼠的转基因雄性后代也不育。通过G0雌性小鼠及其转基因雌性后代进行繁殖，建立了7个“品系”。其中6个品系在肝脏中表达HSV胸苷激酶活性，且活性与HSV tk RNA的存在完全相关。在检测的4个品系中的3个品系中，雌性肝脏中的表达低于雄性肝脏，并且在这些品系中，肝脏细胞核中外源基因的连续转录速率也观察到相同的性别差异。当对其中一个表现出性别二态性的品系的雌性小鼠用睾酮处理时，HSV tk RNA和胸苷激酶活性水平升高，尽管未达到雄性水平。在肝脏表达的这些方面，以及在其他7个组织中缺乏表达的情况，杂种基因表现出许多内源性1组Mup基因的特征。然而，该基因也在包皮腺和睾丸中高水平表达，而Mup基因在这两个组织中并不表达。当将该基因导入7个品系中的5个品系时，携带了一个连接在HSV tk基因3'末端之外的大肠杆菌supF基因拷贝，但这并不影响整体表达模式。所有品系均雄性不育且在睾丸中表达HSV胸苷激酶，但一个品系在肝脏中无活性，另一个品系在包皮腺中无活性。因此，睾丸表达可能是不育的原因。所描述的数据表明，包皮腺和睾丸中表达异常的原因不同。由于每个组织中的表达在几个品系中都有发生，杂种基因的结构在每种情况下必定起了作用。5个经过深入研究的品系在包皮腺、睾丸、雄性肝脏和雌性肝脏中至少表现出4种始终不同的相对表达模式。这些差异与不同品系中外源基因的拷贝数没有任何关联，必定是由于品系特异性整合的其他方面所致。
