A Mup promoter-thymidine kinase reporter gene shows relaxed tissue-specific expression and confers male sterility upon transgenic mice.

Abstract

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 Go males were sterile, or when fertile did not transmit the foreign gene, and the transgenic male descendants of Go females were also sterile. Seven "lines" were established by breeding from Go 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.The mouse major urinary proteins (MUPs) are coded for by a family of about 35 genes clustered on chromosome 4 (3, 12, 23). Four groups of Mup genes have been identified, the largest of which are the group 1 genes and the probably inert group 2 pseudogenes (3, 12, 25, 35, 51; R. Al-Shawi, P. Ghazal, A. J. Clark, and J. 0. Bishop, submitted for publication). Most group 1 genes are expressed exclusively in the liver, while a small subset are also expressed in the mammary glands of pregnant females (50, 52). Of the two smaller groups, the group 3 genes are also expressed in the liver, but under hormonal control different from the group 1 genes (35), and...

Apoptosis of the Thick Ascending Limb Results in Acute Kidney Injury

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Maintenance of Transgenes in Rats: The Contributions of Embryo Cryopreservation and Intracytoplasmic Sperm/Spermatid Injection.

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Accumulated HSV1-TK Proteins Interfere with Spermatogenesis through a Disruption of the Integrity of Sertoli-Germ Cell Junctions

“…58: [544][545][546][547][548][549][550][551] 2012) A suicide gene system, herpes simplex virus type 1 thymidine kinase (HSV1-TK) and its specific substrate, ganciclovir, is widely used for cancer therapy [1,2]. However, previous investigators also reported that HSV1-TK proteins are likely to play a toxic role in the developing mouse male germ cells in the absence of the nucleoside analog, ganciclovir, to induce defects in cell proliferation [3][4][5][6]. The major histological defects of HSV1-TK transgenic mice appeared to be an abnormal nuclear morphology of elongating spermatids and electron microscopy observation disclosed insufficient chromatin condensation and abnormal acrosome structures [4].…”