Cell cycle expression profiles in HeLa cells

Periodic expression of cell cycle genes highlights the importance of precise temporal control of transcription in regulating cell cycle events. We used HeLa cells enriched for different phases of the cell cycle to identify genes that are expressed in a periodic fashion in specific cell cycle phases. These data were generated for comparison with ChIP-Sequencing data obtained for two subunits of the B-Myb-MuvB complex, B-Myb and LIN9, in HeLa cells. HeLa cells were synchronized at the beginning of S phase by double thymidine block and then released into the cell cycle by washing out the thymidine resulting in tight synchrony at S, G2 and M phases of the cell cycle. Most cells entered mitosis at 8 hours after release as determined by visual inspection. Three independent replicas of double thymidine block and release experiments were performed. RNA was isolated at specific times after release from the thymidine block (0, 2, 4, 6, 8 and 12 hours) and used for generating expression profiles.