Testis hormone-sensitive lipase expression in spermatids is governed by a short promoter in transgenic mice

A testicular form of hormone-sensitive lipase (HSLtes), a triacylglycerol lipase, and cholesterol esterase, is expressed in male germ cells. Northern blot analysis showed HSLtes mRNA expression in early spermatids. Immunolocalization of the protein in human and rodent seminiferous tubules indicated that the highest level of expression occurred in elongated spermatids. We have previously shown that 0.5 kilobase pairs of the human HSLtes promoter directs testis-specific expression of a chloramphenicol acetyltransferase reporter gene in transgenic mice and determined regions binding nuclear proteins expressed in testis but not in liver (Blaise, R,, Grober, J,, Rouet, P., Tavernier, G., Daegelen, D., and Langin, D. (1999) J. Biol. Chem. 274, 9327-9334). Mutation of a SRY/Sox-binding site in one of the regions did not impair in vivo testis-specific expression of the reporter gene. Further transgenic analyses established that 95 base pairs upstream of the transcription start site were sufficient for correct testis expression. In gel retardation assays using early spermatid nuclear extracts, a germ cell-specific DNA-protein interaction was mapped between -46 and -29 base pairs. The DNA binding nuclear protein showed properties of zinc finger transcription factors. Mutation of the region abolished reporter gene activity in transgenic mice, showing that it is necessary for testis expression of HSLtes.