Widespread plasticity in CTCF occupancy linked to DNA methylation

Area of Science:

• Genomics
• Epigenetics
• Molecular Biology

Background:

• CCCTC-binding factor (CTCF) is a key regulator of genome architecture and function.
• CTCF binding patterns were previously thought to be invariant across cell types due to its fundamental role.

Purpose of the Study:

• To investigate the plasticity and cell-type specificity of CTCF binding patterns genome-wide.
• To identify factors regulating CTCF occupancy and its relationship with DNA methylation.

Main Methods:

• Genome-wide ChIP-seq analysis of CTCF occupancy in 19 diverse human cell types.
• Comparison with massively parallel bisulfite sequencing data to assess DNA methylation status.

Main Results:

• CTCF binding landscapes are highly reproducible but exhibit significant cell-selective plasticity.
• 41% of variable CTCF binding sites are associated with differential DNA methylation at specific recognition sequence positions.
• Normal and immortal cell lines display distinct CTCF binding patterns, with immortal cells showing methylation-associated disruption despite increased CTCF expression.

Conclusions:

• CTCF occupancy is subject to strong cell-selective regulation, challenging the notion of invariant binding.
• DNA methylation plays a critical role in modulating CTCF binding patterns genome-wide.
• CTCF binding disruption in immortal cells is linked to epigenetic changes, highlighting altered genome regulation in cancer development.