The herpes simplex virus type 1 thymidine kinase is expressed in the testes of transgenic mice under the control of a cryptic promoter.

Abstract

We reported previously that the herpes simplex virus type 1 (HSV-1) thymidine kinase reporter gene (tk) was expressed in the testes of transgenic mice when coupled to the promoter of a liver-specific mouse major urinary protein (MUP) gene. Here we show that HSV-1 tk is also expressed in the testis when coupled to a MUP pseudogene promoter, to a truncated MUP promoter that is not active in the liver, and to the promoter of the bovine thyroglobulin gene. Furthermore, HSV-1 tk itself was expressed in the testis, although its normal expression had been disabled by removing an upstream regulator of transcription. In every case, the same multiple transcripts were observed, with their 5' ends located downstream of the normal HSV-1 tk translation initiation codon. We conclude that the transcription of HSV-1 tk in the testis is directed by a cryptic TATA box-independent promoter located in the coding region of the gene. The longest HSV-1 thymidine kinase (TK) polypeptides synthesized in the testis were shorter than full-length TK and probably result from translational initiation at Met46 and Met6o, the second and third ATG codons of the tk reading frame. Male mice of most transgenic lines were sterile, and the severity of the lesion in spermatogenesis was directly related to the level of TK expression. In the most highly expressing lines, sperm counts were low and morphologically defective sperm were common. In other sterile lines, TK was expressed at a lower level and sperm counts were normal but sperm motility was greatly reduced. Lines with the lowest levels of HSV-1 TK expression were fertile. HSV-1 TK was expressed in germ line cells, mainly in the haploid spermatids. However, low-level HSV-1 TK activity was found in the testis before the first germ cells entered meiosis, showing that if expression is confined to the germ cells, it also occurs in spermatogonia.

Expression of thymidine kinase driven by an endothelial-specific promoter inhibits tumor growth of Lewis lung carcinoma cells in transgenic mice

“…Mice were maintained heterozygotes for the transgene by mating transgenic females with C57Bl/6 males. As previously documented, 76,77 TK gene induced male infertility.…”

Expression of Porcine FSH.BETA. Subunit Promoter-driven Herpes Simplex Virus Thymidine Kinase Gene in Transgenic Rats

“…Al-Shawi et al observed various levels of infertile transgenic mice [23]. Ellison and Bishop [25] described that ectopic expression of the TK gene mainly occurred at the 2nd ATG (46-48) producing TK protein of Mr 37 000, which induced male infertility in most transgenic mice.…”

“…Ellison and Bishop [25] described that ectopic expression of the TK gene mainly occurred at the 2nd ATG (46-48) producing TK protein of Mr 37 000, which induced male infertility in most transgenic mice. In addition, they argue that the severity of lesion in spermatogenesis is directly related to the level of TK gene [23]. We performed histological analysis of testes and observed that spermatogenesis of the transgenic rats was disrupted (Fig.…”

“…But in this study, as previously described, we did not detect the transcripts of the FSHβ subunit in the rat gonads (the testis and ovary). In addition, it has previously been suggested that a cryptic TATA box-independent promoter and transcription start site located in the coding region of the HSV-TK gene directs ectopic expression in the mouse testis [23]. Therefore, we attempted to detect the transcript of the TK gene transcribed from the transcription start site of the FSHβ-HSV-TK gene using a specific primer set, C, whose forward primer starts at the transcription start site of the porcine FSHβ gene (Fig.…”

Generation of Transgenic Rats with YACs and BACs: Preparation Procedures and Integrity on Microinjected DNA.

“…But the thymidine kinase gene of the herpes simplex virus in the amplification element of the YAC vector causes sterility in male founders [1], and the male founder cannot transmit the transgene to the next generation. To eliminate this problem, two different methods were adopted: removal of the thymidine kinase gene by restriction endonuclease after preparing YAC DNA by amplifying in yeast (AMP/RE), and preparing YAC DNA without amplification (AMP -).…”