Expression of a testis-specific form of TBP-related factor 2 (TRF2) mRNA during mouse spermatogenesis

The gene encoding TATA-binding protein-related factor 2 (TRF2/TLF/TLP/TRP), essential for the progress of spermiogenesis, is abundantly expressed in mammalian testis. A sequence database search revealed that mouse TRF2 is encoded by two mRNAs containing the same protein-coding region and different 5'-untranslated regions. Northern blot analysis using DNA probes specific for the 5'-untranslated regions demonstrated that these two mRNAs are distinguished from each other by the expression patterns: ubiquitous and testis-specific expression. The ubiquitously expressed form of TRF2 mRNA was present at a very low level throughout testicular development, whereas expression of the testis-specific form was first detectable in the 14-day-old testis, and the mRNA level abundantly increased at the later stages of testicular development. Western blot analysis indicated that the TRF2 level increases during testicular development, which is consistent with the expression pattern of the testicular form of TRF2 mRNA. Thus, the presence of the testis-specific form of TRF2 mRNA may account for overexpression of the TRF2 gene in the testis.