Human testis-specific lactate dehydrogenase-C promoter drives overexpression of mouse lactate dehydrogenase-1 cDNA in testes of transgenic mice

The three isozymes of lactate dehydrogenase, each encoded by a separate gene, are developmentally regulated and differentially expressed in tissue-specific patterns. The lactate dehydrogenase-C (LDHC, mouse Ldh3) gene is temporally expressed exclusively in the germ line during spermatogenesis, whereas lactate dehydrogenase-A (LDHA, mouse Ldh1) and B (LDHB, mouse Ldh2) genes are active in somatic tissues. To determine, therefore, whether overexpression of Ldh1 would perturb spermatogenesis, we constructed a transgene in which a sequence from the promoter region of human LDHC was coupled with mouse Ldh1 cDNA. Among nine (three males, six females) founder lines that were identified as being transgenic for the construct, one male transmitted the gene through its germ line. Homo- and heterotetramers containing the LDH-A subunit were detected in homogenates of testes from transgenic animals. We conclude that the human LDHC promoter contains the necessary regulatory sequence(s) for specific expression of mouse Ldh1 as a transgene during spermatogenesis. The fertility of the founder animal was not impaired.