Profiling of DNA replication timing in unsynchronized cell populations

Area of Science:

• Epigenetics
• Cell Biology
• Developmental Biology

Background:

• Chromatin profiling offers a signature for cell identity and developmental stage.
• DNA replication timing across loci indicates chromatin structure.
• This epigenetic profiling distinguishes pluripotent embryonic stem (ES) cells from lineage-restricted cells.

Purpose of the Study:

• To detail a DNA replication timing method for epigenetic profiling.
• To highlight its utility in understanding pluripotency and lineage induction.
• To present it as a potentially advantageous alternative to transcription-based profiling.

Main Methods:

• Pulse-labeling unsynchronized cell populations with 5-bromo-2'-deoxyuridine (BrdU).
• Fractionating cells based on cell-cycle stage.
• Determining candidate sequence abundance in newly replicated DNA via PCR.

Main Results:

• The described DNA replication timing method is robust and has been consistently used across laboratories.
• This epigenetic profiling reliably distinguishes cell types based on chromatin structure.
• The protocol requires 3-4 days to complete.

Conclusions:

• DNA replication timing provides a valuable epigenetic signature for cell characterization.
• This method is useful for studying pluripotency and lineage induction, particularly for stem cell therapy.
• The protocol offers potential advantages over conventional transcription-based profiling.