Species variation in the testicular angiotensin converting enzyme promoter studied in transgenic mice

We have studied the control of transcription of the testicular angiotensin converting enzyme (ACEt) in normal and transgenic mice. Northern analyses, including a developmental curve and separated germ cells, for ACEt mRNA suggest predominantly post-meiotic expression. Mice transgenic for a construct containing the proximal 298 bp of the rabbit ACEt promoter, with chloramphenicol acetyl transferase (CAT) as a recorder, showed correct tissue regulation while a 86 bp fragment of the promoter led to no expression. Many candidate transacting factor binding elements, previously identified as candidate regulators of transcription driving spermatogenesis, are scattered across this 298 bp in the rabbit (but not the mouse) promoter and may lead to tissue specificity. The recent finding that the proximal 91 bp of the mouse ACEt promoter leads to tissue specific expression of a recorder gene (Howard et al., 1993) emphasizes the difference between the two species and the importance of a cAMP response element (CRE) within this fragment for tissue specific expression. This CRE is conserved in the rabbit promoters we used.