THE FSH BETA-SUBUNIT PROMOTER DIRECTS THE EXPRESSION OF HERPES-SIMPLEX VIRUS TYPE-1 THYMIDINE KINASE TO THE TESTIS OF TRANSGENIC MICE

The bovine FSH beta-subunit promoter (2.3 kb) was coupled to the codin g sequence of the Herpes simplex virus type 1 thymidine kinase (HSV-tk ) gene and introduced into mouse embryos. A full-length tk transcript was found in the pituitary and testis. In the testis an additional tru ncated version of tk mRNA was also expressed. Two sets of primer exten sion fragments were identified, one corresponding to transcription ini tiation at or near the cap site of the FSH-beta gene, the other to tra nscription initiation within the tk gene. Furthermore, the latter, sho rter transcript contained a 227 bp deletion. Only the long transcript was translated into immunoreactive tk in the later stages of developin g spermatids. The tk protein was also functional in the testes, since spermatogenesis was either arrested or the germinal epithelium almost completely destroyed in transgenic males treated with the antiherpetic agent. If the FSH-beta-HSV-tk transgene also functions correspondingl y in the pituitary, these mice will provide a useful model for studies on FSH.