3.6-KB mouse cyclin C promoter fragment is predominantly active in the testis

Cyclin C is a highly conserved protein that regulates cell-cycle, messenger RNA transcription and cell adhesion. Recently published studies demonstrate that this protein is an essential player during early embryonic development of multicellular eukaryotes as well. In order to understand better its complex function at the level of tissues or organs, spatial expression characteristics of cyclin C and regulatory components of its expression are needed to be determined. In vitro studies on human cells suggested that approximately the first 3 kilobases of the cyclin C promoter might contain all the regulatory elements that might mimic transcription of cyclin C. To test the hypothesis, we generated reporter transgenic lines where the first 3.6-kilobase region of mouse cyclin C promoter fragment drives the transcription of a marker gene. Messenger RNA levels of the marker gene and cyclin C isoforms were measured in nine organs with reverse transcription coupled quantitative realtime polymerase chain reaction and their expression patterns were compared. The marker gene is predominantly transcribed in testes and does not follow the transcriptional regulation of the examined cyclin C isoforms. Thus, the isolated promoter fragment alone is not sufficient for the complete physiological modulation of cyclin C RNA levels, however, it is capable of enhancing testicular transcription which can be exploited in future applications.