Transcriptional Regulatory Regions of Testis-Specific PGK2 Defined in Transgenic Mice

The gene encoding testis-specific phosphoglycerate kinase 2 (PGK; ATP:3-phospho-D-glycerate 1-phosphotransferase, EC 2.7.2.3) is expressed only in meiotic and haploid male germ cells. Transgenic mice containing an 8-kilobase human genomic PGK2 gene express the human gene in a tissue-specific and developmentally regulated manner. To determine the nature and location of sequences controlling this expression, transgenic mice with various lengths of the human PGK2 5′ region fused to the chloramphenicol acetyltransferase (CAT) gene were analyzed for expression. A 323-base-pair region 5′ to the coding region was found to contain information essential for both tissue-specific and developmentally regulated expression of the CAT reporter gene. Transgenic mice containing a PGK2/luciferase-coding constrct were compared with mice containing an equivalent CAT construct. Luciferase gene expression was also testis-specific and was more sensitive than CAT gene expression, but otherwise regulation of the two reporter genes was similar in the germ cells of transgenic mice. Translation of both PGK2/CAT and PGK2/luciferase fusion genes was seen concurrently with the first detectable transcripts.