Transgenic mice demonstrate a testis-specific promoter for angiotensin-converting enzyme

There are two isozymes of angiotensin-converting enzyme (ACE), one produced by somatic tissues and a smaller protein synthesized by developing spermatozoa (testis ACE). To investigate the molecular control of testis ACE, we generated mice transgenic for a construct containing a putative testis-specific ACE promoter linked to the Escherichia coli reporter gene encoding beta-galactosidase. The transgenic mice express beta-galactosidase protein and RNA only within the testis. Histochemical analysis of the transgenic mice shows co-localization of beta-galactosidase protein and endogenous ACE within elongating spermatozoa. These studies demonstrate that transcription of testis ACE is controlled by a strong intragenic testis-specific promoter that is contained within a 698-base pair fragment immediately upstream from the transcription start site of testis ACE. Characterization of the testis ACE promoter may provide insights into the molecular mechanisms controlling cell stage-specific gene expression in the male germ line.