STRUCTURE AND CELL-CYCLE-REGULATED TRANSCRIPTION OF THE HUMAN CYCLIN-A GENE

Cyclin A is a cell cycle regulatory protein that functions in mitotic and S-phase control in mammalian somatic cells. Its deregulated expression may have a role in cellular transformation. We have cloned and sequenced the human cyclin A gene and cDNAs representing its mRNAs and have characterized its promoter. Using synchronized cultures of NIH 3T3 cells stably transfected with cyclin A promoter/luciferase constructs, we show that the promoter is repressed during the G(1) phase of the cell cycle and is activated at S-phase entry. Cell cycle regulation of the cyclin A gene promoter is mediated by sequences extending from -79 to +100 relative to the predominant transcription start site. It does not require the presence of a functional retinoblastoma protein.