DNA replication unfazed by disruption of cohesin-dependent DNA organisation

DNA replication unfazed by disruption of cohesin-dependent DNA organisation

DNA replication is a process fundamental to all known organisms on earth. This highly regulated process is linked to chromatin structure − the way DNA is organised in the cell. It has been hypothesised that chromatin structure determines the accessibility of DNA by the replication machinery and hence dictates DNA replication timing.

Cohesin, well-known for its function in separating sister chromatids during cell division, has been shown to help form loop-based chromatin structures called topologically associating domains (TADs). Increasing evidence showed that TADs correlate with replication domains, but a causative relationship has not been established.

Phoebe Oldach, a DPhil student from the Nieuduzynski Lab, studied the relationship between TADs and DNA replication timing by using a system that can rapidly cut down levels of cohesin. After confirming the efficiency and efficacy of the system, she showed that replication timing patterns are not impacted by the absence of cohesin in either G1 or S phases of the cell cycle, during which the cell prepares for and executes DNA replication, respectively. This indicates that replication timing is not driven by cohesin-dependent TADs.

Sheng Pong

Oldach P. and Nieduszynski C. A. (2019).

Genes, 10(3). pii: E196. doi: 10.3390/genes10030196.