CTCF-RNA interactions orchestrate cell-specific chromatin loop organization

Area of Science:

• Genomics
• Molecular Biology
• Cell Biology

Background:

• CCCTC-binding factor (CTCF) plays a critical role in chromatin organization.
• CTCF interacts with endogenous RNAs, and its ZF1 RNA-binding region is important for chromatin loop formation in mouse embryonic stem cells (ESCs).
• The functional significance of CTCF-ZF1 RNA interactions during cell differentiation remains largely unknown.

Purpose of the Study:

• To investigate the role of CTCF-ZF1 RNA interactions in maintaining cell-type-specific chromatin organization during differentiation.
• To elucidate the functional consequences of disrupting CTCF-ZF1 RNA interactions on gene regulation and cellular identity.

Main Methods:

• Utilized an in vitro model of ESC differentiation into neural progenitor cells (NPCs).
• Generated cells expressing a CTCF mutant lacking the ZF1 RNA-binding region (CTCF-ΔZF1).
• Identified and characterized NPC-specific RNAs interacting with CTCF-ZF1.
• Assessed the impact of truncating specific interacting RNAs (Podxl, Grb10) on chromatin loops.

Main Results:

• CTCF-ZF1 is essential for preserving cell-type-specific chromatin loops during NPC differentiation.
• Expression of CTCF-ΔZF1 disrupted chromatin loops and dysregulated genes involved in neuronal development.
• Truncation of NPC-specific RNAs, Podxl and Grb10, mimicked CTCF-ΔZF1 effects by disrupting chromatin loops in cis.

Conclusions:

• CTCF-ZF1 RNA interactions are fundamentally important for maintaining genome architecture and cellular identity during differentiation.
• These interactions ensure the proper regulation of cell-type-specific gene expression programs.