Testis expression of hormone-sensitive lipase is conferred by a specific promoter that contains four regions binding testicular nuclear proteins

The testicular isoform of hormone-sensitive lipase (HSLtes) is encoded by a testis-specific exon and 9 exons common to the testis and adipocyte isofor ms. In mouse, HSLtes mRNA appeared during spermiogenesis in round spermatid s. Two constructs containing 1.4 and 0.5 kilobase pairs (kb) of the human H SLtes gene 5'-flanking region cloned upstream of the chloramphenicol acetyl transferase gene were microinjected into mouse oocytes. Analyses of enzyme activity in male and female transgenic mice showed that 0.5 kb of the HSLte s promoter was sufficient to direct expression only in testis, Cell transfe ction experiments showed that CREM tau, a testis-specific transcriptional a ctivator, does not transactivate the HSLtes promoter. Using gel retardation assays, four testis-specific binding regions (TSBR) were identified using testis and liver nuclear extracts. The testis-specific protein binding on T SBR4 was selectively competed by a probe containing a SRY/Sox protein DNA r ecognition site. Sox5 and Sox6 which are expressed in post-meiotic germ cel ls bound TSBR4. Mutation of the AACAAAG motif in TSBR4 abolished the bindin g. Moreover, binding of the high mobility group domain of Sox5 induced a be nd within TSBR4. Together, our results showed that 0.5 kb of the human HSLt es promoter bind Sox proteins and contain cis-acting elements essential for the testis specificity of HSL.